Journal articles on the topic 'In-stream nutrient concentrations'
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1
Bernal, S., A. Lupon, M. Ribot, F. Sabater, and E. Martí. "Riparian and in-stream controls on nutrient concentrations along a headwater forested stream." Biogeosciences Discussions 11, no. 7 (July 29, 2014): 11597–634. http://dx.doi.org/10.5194/bgd-11-11597-2014.
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Abstract. Headwater streams have a strong capacity to transform and retain nutrients, and thus, a longitudinal decrease in stream nutrient concentrations would be expected from in-stream nutrient removal alone. Yet, a number of other factors within the catchment, including biogeochemical processing within the riparian zone and export to streams, can contribute to stream nutrient concentration, which may overcome the effect of in-stream biogeochemical processing. To explore this idea, we analyzed the longitudinal patterns of stream and riparian groundwater concentrations for chloride (Cl−), nitrate (NO3−), ammonium (NH4+), and phosphate (PO43−) along a 3.7 km reach at an annual scale. The reach showed a gradual increase in stream and riparian width, riparian tree basal area, and abundance of riparian N2-fixing tree species. Concentrations of Cl− indicated a~strong hydrological connection at the riparian-stream edge. However, stream and riparian groundwater nutrient concentrations showed a moderate to null correlation, suggesting high biogeochemical processing at the riparian-stream edge and within the stream. A mass balance approach along the reach indicated that, on average, in-stream net nutrient uptake prevailed over release for NH4+ and PO43−, but not for NO3−. On an annual basis, in-stream processes contributed to change stream input fluxes by 11%, 26%, and 29% for NO3−, NH4+, and PO43−, respectively. Yet, longitudinal trends in concentration were not consistent with the prevailing in-stream biogeochem ical processes. During the riparian dormant period, stream concentration decreased along the reach for NO3−, but increased for NH4+ and PO43−. During the riparian vegetative period, NO3− and PO43− increased along the reach while NH4+ showed no clear pattern. These longitudinal trends were partially related to riparian forest features and groundwater inputs, especially for NO3− and PO43−. Our study suggests that even though in-stream biogeochemical processing was substantial, the riparian zone can modulate the longitudinal variation in stream nutrient chemistry in this headwater stream.
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Cortelezzi, Agustina, Carolina Ocón, María V. López van Oosterom, Rosana Cepeda, and Alberto Rodrigues Capítulo. "Nutrient enrichment effect on macroinvertebrates in a lowland stream of Argentina." Iheringia. Série Zoologia 105, no. 2 (June 2015): 228–34. http://dx.doi.org/10.1590/1678-476620151052228234.
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ABSTRACT One of the most important effects derived from the intensive land use is the increase of nutrient concentration in the aquatic systems due to superficial drainage. Besides, the increment of precipitations in South America connected to the global climate change could intensify these anthropic impacts due to the changes in the runoff pattern and a greater discharge of water in the streams and rivers. The pampean streams are singular environments with high natural nutrient concentrations which could be increased even more if the predictions of global climate change for the area are met. In this context, the effect of experimental nutrient addition on macroinvertebrates in a lowland stream is studied. Samplings were carried out from March 2007 to February 2009 in two reaches (fertilized and unfertilized), upstream and downstream from the input of nutrients. The addition of nutrients caused an increase in the phosphorus concentration in the fertilized reach which was not observed for nitrogen concentration. From all macroinvertebrates studied only two taxa had significant differences in their abundance after fertilization: Corbicula fluminea and Ostracoda. Our results reveal that the disturbance caused by the increase of nutrients on the benthic community depends on basal nutrients concentration. The weak response of macroinvertebrates to fertilization in the pampean streams could be due to their tolerance to high concentrations of nutrients in relation to their evolutionary history in streams naturally enriched with nutrients. Further research concerning the thresholds of nutrients affecting macroinvertebrates and about the adaptive advantages of taxa in naturally eutrophic environments is still needed. This information will allow for a better understanding of the processes of nutrient cycling and for the construction of restoration measures in natural eutrophic ecosystems.
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Bernal, S., A. Lupon, M. Ribot, F. Sabater, and E. Martí. "Riparian and in-stream controls on nutrient concentrations and fluxes in a headwater forested stream." Biogeosciences 12, no. 6 (March 24, 2015): 1941–54. http://dx.doi.org/10.5194/bg-12-1941-2015.
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Abstract. Headwater streams are recipients of water sources draining through terrestrial ecosystems. At the same time, stream biota can transform and retain nutrients dissolved in stream water. Yet studies considering simultaneously these two sources of variation in stream nutrient chemistry are rare. To fill this gap of knowledge, we analyzed stream water and riparian groundwater concentrations and fluxes as well as in-stream net uptake rates for nitrate (NO3−), ammonium (NH4+), and soluble reactive phosphorus (SRP) along a 3.7 km reach on an annual basis. Chloride concentrations (used as conservative tracer) indicated a strong hydrological connection at the riparian–stream interface. However, stream and riparian groundwater nutrient concentrations showed a moderate to null correlation, suggesting high in-stream biogeochemical processing. In-stream net nutrient uptake (Fsw) was highly variable across contiguous segments and over time, but its temporal variation was not related to the vegetative period of the riparian forest. For NH4+, the occurrence of Fsw > 0 μg N m−1 s−1 (gross uptake > release) was high along the reach, while for NO3−, the occurrence of Fsw < 0 μg N m−1 s−1 (gross uptake < release) increased along the reach. Within segments and dates, Fsw, whether negative or positive, accounted for a median of 6, 18, and 20% of the inputs of NO3−, NH4+, and SRP, respectively. Whole-reach mass balance calculations indicated that in-stream net uptake reduced stream NH4+ flux up to 90%, while the stream acted mostly as a source of NO3− and SRP. During the dormant period, concentrations decreased along the reach for NO3−, but increased for NH4+ and SRP. During the vegetative period, NH4+ decreased, SRP increased, and NO3− showed a U-shaped pattern along the reach. These longitudinal trends resulted from the combination of hydrological mixing with terrestrial inputs and in-stream nutrient processing. Therefore, the assessment of these two sources of variation in stream water chemistry is crucial to understand the contribution of in-stream processes to stream nutrient dynamics at relevant ecological scales.
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Elsdon, Travis S., and Karin E. Limburg. "Nutrients and their duration of enrichment influence periphyton cover and biomass in rural and urban streams." Marine and Freshwater Research 59, no. 6 (2008): 467. http://dx.doi.org/10.1071/mf07085.
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Although it is well known that land use affects nutrient dynamics and algal growth in streams, the responses to different durations of nutrient supply are poorly understood. The associations of benthic (periphyton-dominated) biomass with concentrations of dissolved nitrogen and phosphorus in rural and urban streams in New York were quantified. Biomass was significantly greater (2-fold) in the urban compared with the rural stream, which was associated with differences in dissolved nutrients. Experimental field enrichment of nutrient concentrations and duration of exposure altered benthic periphyton. Increasing nutrients by 60–99% of ambient concentrations increased periphyton percentage cover and biomass. Periphyton abundance also increased with increasing duration of exposure to nutrients (2, 4 and 8 weeks); however, short-term pulses of nutrients (2 weeks) had no significant effect in the rural stream. These results indicate that effective management of nutrient delivery, by reducing time periods of high nutrient load, will minimise impacts to benthic environments.
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Dodds, Walter K., Val H. Smith, and Kirk Lohman. "Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams." Canadian Journal of Fisheries and Aquatic Sciences 59, no. 5 (May 1, 2002): 865–74. http://dx.doi.org/10.1139/f02-063.
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Knowledge of factors limiting benthic algal (periphyton) biomass is central to understanding energy flow in stream ecosystems and stream eutrophication. We used several data sets to determine how water column nutrients and nonnutrient factors are linked to periphytic biomass and if the ecoregion concept is applicable to nutrientperiphyton relationships. Literature values for seasonal means of biomass of periphyton, nutrient concentrations, and other stream characteristics were collected for almost 300 sampling periods from temperate streams. Data for benthic chlorophyll and nutrient concentrations from a subset of 620 stations in the United States National Stream Water-Quality Monitoring Networks were also analyzed. The greatest portion of variance in models for the mean and maximum biomass of benthic stream algae (about 40%) was explained by concentrations of total N and P. Breakpoint regression and a two-dimensional KolmogorovSmirnov statistical technique established significant breakpoints of about 30 µg total P·L1 and 40 µg total N·L1, above which mean chlorophyll values were substantially higher. Ecoregion effects on nutrientchlorophyll relationships were weak. Ecoregion effects were cross-correlated with anthropogenic effects such as percent urban and cropland area in the watershed and population density. Thus, caution is necessary to separate anthropogenic effects from natural variation at the ecoregion level.
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Matej-Lukowicz, Karolina, Ewa Wojciechowska, Nicole Nawrot, and Lidia Anita Dzierzbicka-Głowacka. "Seasonal contributions of nutrients from small urban and agricultural watersheds in northern Poland." PeerJ 8 (February 6, 2020): e8381. http://dx.doi.org/10.7717/peerj.8381.
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Diffuse sources of pollution like agricultural or urban runoff are important factors in determining the quality of surface waters, although they are more difficult to monitor than point sources. The objective of our study was to verify assumptions that the inflow from agricultural nutrient sources is higher than from urbanized ones. It has been done by comparing the nutrients and organic matter concentrations and loads for three small streams in northern Poland (Pomerania Region). Two streams flowing through agricultural catchments and an urban stream flowing through the city of Gdansk were analysed. Concentrations of nutrients: N-NO${}_{3}^{-}$ N-NH${}_{4}^{+}$, P-PO${}_{4}^{3-}$, total phosphorus, total nitrogen and COD were measured 1–3 times per month in the period from July 2017 to December 2018 in agricultural watersheds and from October 2016 to March 2018 for an urban stream. Seasonal changes in concentrations were analysed with descriptive statistics tools. Principal Component Analysis (PCA) was used to point out the most significant factors determining variations in nutrients and organic matter concentrations with respect to different seasons. The factors included a number of characteristics regarding the catchment and streams: total catchment area, stream length, watershed form ratio, stream slope, flow rate and land use with respect to paved areas, agricultural areas and green areas (parks, forests, meadows and pastures). Although concentrations of nitrogen compounds were higher in streams flowing through agricultural areas, our study showed that total concentrations of phosphorus were higher in the urban stream, especially in summer. In agricultural areas the summer concentrations of nutrients were not high, which was probably due to dense vegetation. The correlation between P-PO${}_{4}^{3-}$ concentration and size of agricultural area in the catchment was observed in winter when no vegetation field cover exists. Our study shows an urgent need to monitor the nutrient loads carried with urban streams especially if discharged into receivers prone to eutrophication.
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Johnston, N. T., E. A. MacIsaac, P. J. Tschaplinski, and K. J. Hall. "Effects of the abundance of spawning sockeye salmon (Oncorhynchus nerka) on nutrients and algal biomass in forested streams." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 3 (March 1, 2004): 384–403. http://dx.doi.org/10.1139/f03-172.
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We used natural variation in sockeye salmon (Oncorhynchus nerka) spawner biomass among sites and years in three undisturbed, forested watersheds in interior British Columbia to test the hypotheses that salmon were a major source of particulate organic matter inputs to the streams and that carcass biomass determined stream-water nutrient concentrations and epilithic algal production. Sockeye carcasses were retained at the spawning sites, primarily (7580%) by large woody debris (LWD) or pools formed by LWD. The abundance and distribution of sockeye salmon determined stream-water nutrient concentrations and epilithic chlorophyll a concentrations during late summer and early fall when most primary production occurred in the oligotrophic streams. Periphyton accrual rates were elevated at sites with high salmon biomass. Peak chlorophyll a concentration increased with increasing carcass biomass per unit discharge above a threshold value to reach maxima 10-fold greater than ambient levels. Epilithic algae were dominated by a few common, large diatom taxa. Salmon carcasses were the dominant source of particulate organic carbon in low gradient stream reaches. Nutrient budget modeling indicated that most of the salmon-origin nutrients were exported from the spawning streams or removed to the terrestrial ecosystem; diffuse impacts may extend over a much larger area than simply the sites used for spawning.
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Alarcon, Vladimir J., and Gretchen F. Sassenrath. "Nitrate, Total Ammonia, and Total Suspended Sediments Modeling for the Mobile River Watershed." International Journal of Agricultural and Environmental Information Systems 8, no. 2 (April 2017): 20–31. http://dx.doi.org/10.4018/ijaeis.2017040102.
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This paper presents details of a water quality model of the Mobile River watershed that estimates total suspended sediments at the outlet of the watershed. The model is capable of simulating Nitrate (NO3), Total Ammonia (TAM), and Total Suspended Sediments (TSS) for extended periods of time at a daily temporal resolution (1970-1995). The Hydrological Simulation Program Fortran is used for modeling the hydrological, nitrogenous constituents, and sediment processes. Based on the nutrient simulation and exploration of the effects of two management practices (filter strips and stream bank stabilization and fencing) on nutrient removal, the resulting sediment model is used to implement the most efficient nutrient management practice and explore its effects on TSS concentrations in the Mobile River. Results show that the implementation of the management practice “stream bank stabilization and fencing” to agricultural lands in sub-watersheds that had intense agricultural activities produced the highest reductions of NO3 concentration (up to 14.06%) and TAM concentrations (8.01%). Based on the nutrient simulation and identification of “stream bank stabilization and fencing” as the most efficient BMP for nutrient concentration reduction, the sediment model was used to explore its effects on TSS concentrations in the Mobile River. Implementing “stream bank stabilization and fencing” produced monthly median TSS concentration reductions ranging from 3.6% to 10.6% in the Mobile River.
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Barrientos-Pérez, Ana Aurora, Maria Mercedes Castillo, Manuel Mendoza-Carranza, and Aarón Jarquín-Sánchez. "Developing nutrient criteria for the Grijalva basin, Mexico." Revista Internacional de Contaminación Ambiental 38 (November 8, 2022): 493–510. http://dx.doi.org/10.20937/rica.54408.
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Excess nutrient inputs are a major cause of aquatic ecosystem impairment worldwide. Increased total phosphorus (TP) and total nitrogen (TN) concentrations can lead to eutrophication affecting ecosystem functioning and environmental services provided by streams and rivers. Establishing numeric nutrient criteria is a strategy to reduce nutrient inputs into freshwater ecosystems. Our objective was to estimate nutrient concentrations that could be used as guides to establish nutrient criteria for TP and TN in the Grijalva basin, Mexico. We applied the frequency distribution method to water quality monitoring data for subregions (upper, middle, and lower Grijalva) and for the whole basin, considering two stream size categories. Nutrients were also compared among subregions, land uses, and stream sizes. Agriculture and urban areas showed higher nutrient concentrations than other land uses, probably due to the use of fertilizers and inputs of domestic and industrial wastewater. Higher nutrient concentrations were found in the middle Grijalva and in low-order streams. Nutrient concentrations at the 75th percentile for the reference sites were higher than those obtained at the 5th, 16.7th, and 25th percentiles for the general nutrient data, probably due to the high level of human disturbance in the Grijalva basin. Nutrient concentrations at the 25th percentile are probably too high to protect the aquatic ecosystems in the basin, while concentrations at the 5th percentile can be too restrictive for the basin. Based on our results, nutrient concentrations at the 16.7th percentile are proposed as a first approximation for nutrient criteria to protect river systems in the Grijalva basin.
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von Schiller, D., S. Bernal, and E. Martí. "Technical Note: A comparison of two empirical approaches to estimate in-stream nutrient net uptake." Biogeosciences Discussions 7, no. 5 (October 15, 2010): 7527–42. http://dx.doi.org/10.5194/bgd-7-7527-2010.
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Abstract. To establish the relevance of in-stream processes on nutrient export at catchment scale it is important to accurately estimate whole-reach net nutrient uptake rates that consider both uptake and release processes. Two empirical approaches have been used in the literature to estimate these rates: (a) the mass balance approach, which considers changes in nutrient loads corrected by groundwater inputs between two stream locations separated by a certain distance, and (b) the spiralling approach, which is based on the patterns of longitudinal variation in ambient nutrient concentrations along a reach following the nutrient spiralling concept. In this study, we compared the estimates of in-stream net nutrient uptake rates of nitrogen (N) and the associated uncertainty obtained with these two approaches at different ambient conditions using a data set of monthly samplings in two contrasting stream reaches during two hydrological years. The rates calculated with the mass balance approach tended to be higher than those calculated with the spiralling approach but only at high ambient N concentrations. Uncertainty associated with these estimates also differed between both approaches, especially for ammonium due to the lack of significant longitudinal patterns in concentration. The advantages and disadvantages of each of the approaches are discussed.
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von Schiller, D., S. Bernal, and E. Martí. "Technical Note: A comparison of two empirical approaches to estimate in-stream net nutrient uptake." Biogeosciences 8, no. 4 (April 8, 2011): 875–82. http://dx.doi.org/10.5194/bg-8-875-2011.
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Abstract. To establish the relevance of in-stream processes on nutrient export at catchment scale it is important to accurately estimate whole-reach net nutrient uptake rates that consider both uptake and release processes. Two empirical approaches have been used in the literature to estimate these rates: (a) the mass balance approach, which considers changes in ambient nutrient loads corrected by groundwater inputs between two stream locations separated by a certain distance, and (b) the spiralling approach, which is based on the patterns of longitudinal variation in ambient nutrient concentrations along a reach following the nutrient spiralling concept. In this study, we compared the estimates of in-stream net nutrient uptake rates of nitrate (NO3) and ammonium (NH4) and the associated uncertainty obtained with these two approaches at different ambient conditions using a data set of monthly samplings in two contrasting stream reaches during two hydrological years. Overall, the rates calculated with the mass balance approach tended to be higher than those calculated with the spiralling approach only at high ambient nitrogen (N) concentrations. Uncertainty associated with these estimates also differed between both approaches, especially for NH4 due to the general lack of significant longitudinal patterns in concentration. The advantages and disadvantages of each of the approaches are discussed.
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Greenwood, Jennifer L., and Amy D. Rosemond. "Periphyton response to long-term nutrient enrichment in a shaded headwater stream." Canadian Journal of Fisheries and Aquatic Sciences 62, no. 9 (September 1, 2005): 2033–45. http://dx.doi.org/10.1139/f05-117.
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We maintained elevated but moderate concentrations of nitrogen and phosphorus continuously for 2 years in a heavily shaded headwater stream and compared effects on stream periphyton with a reference stream. Both streams were sampled for 1 year before treatment. Some measures of periphyton biomass (ash-free dry mass and chlorophyll a) responded positively to enrichment. Increased chlorophyll a was likely a result of higher chlorophyll per cell, as total algal biovolume did not change with enrichment. These differences were greatest during high-light months (November-May), when cellular growth rates (a proxy for production) were also highest with enrichment. Algal assemblages were dominated by diatoms and remained similar between the treatment and reference streams throughout the enrichment period. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass.
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Guo, Xiaolan, Xiuli Yan, Hongyan Bao, Junwen Wu, and Shuhji Kao. "Differential Response of Nutrients to Seasonal Hydrological Changes and a Rain Event in a Subtropical Watershed, Southeast China." Water 14, no. 5 (March 7, 2022): 834. http://dx.doi.org/10.3390/w14050834.
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A large amount of terrestrial nutrients are discharged into the ocean through rivers. However, the impact of seasonal hydrological variations on riverine nutrient concentrations and fluxes remains unclear, especially in the medium-sized subtropical rivers that are highly influenced by human activities. In this study, we investigated the monthly changes in nutrient concentrations (soluble reactive phosphorus, SRP; dissolved silicate, DSi; and dissolved inorganic nitrogen, DIN) in the North Stream (NS) and West Stream (WS) of the Jiulong River (JLR). The results show that the concentrations of SRP and DSi in the NS and the WS displayed a similar seasonal variability, which was different from the pattern of DIN. Hydrological conditions, chemical fertilizer loss and biogeochemical processes are responsible for the seasonal changes in the nutrients in the two streams, especially during extreme rain events. Nutrient concentrations in the NS exhibited a clockwise trajectory along with river discharge during rain events, while a reverse pattern in the WS was observed since it experienced a moderately long rain event. Different rainfall features between the two main tributaries resulted in the majority of nutrients being exported at the start of the rain event in the NS and the end of rain event in the WS. Indeed, the annual high flow (Q/Qm > 3) accounts for ~17.3% of the annual nutrient flux in the JLR even though this period spans only ~4.0% of a year, which suggests the importance of rain events on nutrient export in these subtropical rivers. Although the annual fluxes of DIN and SRP in the JLR were smaller than many rivers worldwide, higher areal yields of DIN and SRP were observed, indicating that the JLR is highly influenced by human activities. Our study systematically evaluated the response of nutrient concentrations to hydrological changes in two tributaries of the JLR, which is useful in better understanding the nutrient dynamics in medium-sized subtropical rivers.
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McDowell, William H. "Internal nutrient fluxes in a Puerto Rican rain forest." Journal of Tropical Ecology 14, no. 4 (July 1998): 521–36. http://dx.doi.org/10.1017/s0266467498000376.
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Throughfall and soil solution chemistry were studied for 1 y in a tropical montane forest in the Luquillo Mountains of Puerto Rico. Passage of precipitation through the forest canopy resulted in an increase in the concentration and flux of all solutes except H+ and NO3−. Throughfall chemistry showed no strong seasonal patterns, but concentrations of many solutes declined during weeks of high rainfall. Enrichment in throughfall relative to precipitation was similar to values reported recently for several other tropical sites, with the exception of NH4+, which was particularly high at this site. Based on net throughfall deposition of Cl−, dry deposition of marine aerosols appears to be a relatively minor component (c. 15%) of total deposition. In soil solution, no seasonal patterns in concentration were evident and variability was highest for elements with high biological activity (especially N). Concentrations and fluxes of K+ and dissolved organic carbon (DOC) showed the largest declines as throughfall passed through the soil profile; concentrations of most other elements increased or were relatively constant. Declining DOC flux through the soil profile appears to be due to sorption processes similar to those observed in many temperate forests. Concentrations and fluxes of HCO3− and SiO2 increased substantially in soil solution, but never approached those observed in the stream. This suggests that additional weathering must occur as groundwater moves from this ridgetop site to the stream.
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Spänhoff, Bernd, and Mark O. Gessner. "Slow initial decomposition and fungal colonization of pine branches in a nutrient-rich lowland stream." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 10 (October 1, 2004): 2007–13. http://dx.doi.org/10.1139/f04-145.
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Mass loss, fungal colonization, and chemical changes of submerged pine (Pinus sylvestris) branches were monitored in a nutrient-rich lowland stream. Branches retrieved from the stream were analyzed for water-soluble substances to assess mass loss by leaching. Concentrations of substances soluble in hot 1% NaOH were determined in order to detect changes in wood-tissue structure indicating microbial degradative activity, and fungal colonization was estimated as ergosterol concentration. Decomposition of the pine branches was slow, with a mean mass loss of 8.3% within 13 months and an overall decay coefficient, k, of 0.074·year1. Concentrations of water-soluble substances in wood decreased from 2.8% to 1.7% after 5 weeks and in bark from 5.6% to 3.8% within 2 weeks. No further losses were noted, nor were significant changes observed in concentrations of substances soluble in hot dilute NaOH. Fungal biomass in bark increased within the first 5 weeks (1469 µg ergosterol·g1dry mass) but was invariably low in wood. These results indicate that decomposition of intact fully corticated pine branchwood in streams proceeds very slowly, with little fungal colonization and no notable changes in wood structure occurring after more than a year even when dissolved nutrients in stream water are readily available.
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Donato-R, Jhon Charles, Hooz A. Mendivelso, Edna L. Pedraza-Garzón, and Sergi Sabater. "Drivers of the diversity of diatoms in an oligotrophic Andean stream." International Journal of Limnology 58 (2022): 2. http://dx.doi.org/10.1051/limn/2022003.
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An in situ experiment determined that the addition of ammonia N-NH4+, nitrate N-NO3– and phosphate P-PO43– to an oligotrophic Andean stream significantly affected diatom composition and diversity. Over a nine-month period, fertilized and non-fertilized sections of the stream were studied for their environmental characteristics and diatom composition. Nutrient concentrations were increased three times in a downstream section with respect to those occurring naturally upstream. Alpha diversity (Shannon-Wiener [H”] and Simpson [S] indices) were determined monthly. In the non-fertilized control section, diatom diversity was significantly (p ≤ 0.05) related to water flow and P and N concentrations. In the fertilized section diversity was associated to the enhanced ammonia and phosphorus. A redundancy analysis (RDA) showed that conductivity, water flow and nutrient concentrations contributed to the diatom assemblage composition (83% along the first two axes). Achnanthidium minutissimum, Cocconeis placentula, and Epithemia sorex occurrence was related to low phosphorus concentration. Epithemia adnata var. minor, Nitzschia dissipata, and Reimeria sinuata were associated with high P concentrations, high water flow and low conductivity Navicula rynchocephala, Gomphonema parvulum, Navicula capitatoradiata, and Melosira varians were associated with high P.
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Kurz, I., H. Tunney, and C. E. Coxon. "The impact of agricultural management practices on nutrient losses to water: data on the effects of soil drainage characteristics." Water Science and Technology 51, no. 3-4 (February 1, 2005): 73–81. http://dx.doi.org/10.2166/wst.2005.0577.
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Against the background of increasing nutrient concentrations in Irish water bodies, this study set out to gain information on the potential of agricultural grassland to lose nutrients to water. Overland flow, flow from artificial subsurface drains and stream flow were gauged and sampled during heavy rainfall events. Dissolved reactive phosphorus (DRP), potassium (K), total ammonia (TA), and total oxidised nitrogen (TON) were measured in water samples. When the nutrient concentrations in water were examined in relation to the grassland management practices of the study catchments it emerged that soil P levels, the application of organic and inorganic fertilisers before heavy rainfall and the presence of grazing animals could all influence nutrient concentrations in surface and subsurface drainage water. Overall, the drainage characteristics of soil were found to have a considerable influence on the potential of land to lose nutrients to water.
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Erina, Oxana, Dmitriy Sokolov, Maria Tereshina, Jessica Vasil’chuk, and Nikolay Kasimov. "Seasonal dynamics of nutrients and organic matter in urban stream." E3S Web of Conferences 163 (2020): 03004. http://dx.doi.org/10.1051/e3sconf/202016303004.
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The study presents the results of water quality evaluation in the Setun River watershed, located entirely within the limits of the Moscow City. Multiple point and non-point sources of pollution cause the nutrient and organic matter content of the river and its tributaries to significantly differ from the natural background. Maximum nitrogen and phosphorus concentrations were observed at the upper reaches of the river during the summer low flow due to the landfill impact. Because of the extreme nutrient pollution at the river’s upper course, subsequent water inflow, even from significantly polluted tributaries, has a diluting effect, and the nutrient concentration decreases downstream. The effect of urbanization on the organic matter content is reflected in elevated COD and BOD values that exceed the national environmental guidelines. Seasonal dynamics of organic matter content includes increased organic matter during snowmelt and its relatively low content during summer.
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Levi, Peter S., Jennifer L. Tank, Scott D. Tiegs, Janine Rüegg, Dominic T. Chaloner, and Gary A. Lamberti. "Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?" Canadian Journal of Fisheries and Aquatic Sciences 68, no. 8 (August 2011): 1316–29. http://dx.doi.org/10.1139/f2011-067.
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Streams often rely on nutrient subsidies, and variation in nutrient delivery may alter the ecosystem response. Pacific salmon (Oncorhynchus spp.) provide marine-derived nutrients to their natal streams but also cause benthic disturbance, with the net effect determined by watershed and stream characteristics. To understand the factors contributing to variation in salmon-derived nutrients (SDN), we studied nutrient concentration and export in seven streams with varying physical characteristics due to timber harvest (e.g., channel complexity) over three years in Southeast Alaska, USA. Salmon increased concentrations and export of dissolved and particulate nitrogen, phosphorus, and carbon, but the magnitude of increase varied up to 41-fold among streams. The density of live salmon best predicted the increase in nutrient concentration and export, whereas the density of carcasses had a negligible effect. Nutrient export was predicted by transient storage before and after the salmon run. Streams in harvested watersheds with simplified channels had greater nutrient export than those in pristine watersheds with complex channels. However, enrichment from salmon overrode the effect of timber harvest on export during the run. Our study demonstrates that enrichment via SDN is short-lived and related to run size, whereas timber harvest and carcasses exert little influence on SDN dynamics.
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Tokareva, I. V., M. A. Korets, and A. S. Prokushkin. "Nutrients in streams draining the different types of wetlands in Western Siberian Plain." IOP Conference Series: Earth and Environmental Science 1093, no. 1 (September 1, 2022): 012018. http://dx.doi.org/10.1088/1755-1315/1093/1/012018.
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Abstract Two second order streams were compared to test the influence of peatbog type (minerotrophic vs. oligotrophic) on dissolved nutrient composition and dynamics during several hydrologic years. A significant spatio-temporal variation in the concentration of nutrients in the channel runoff is shown. It depends on the catchment characteristics and the hydrological period of the year. In general, the concentrations of phosphates, nitrates and nitrites are lower in the stream draining an area dominated by a minerotrophic bog that indicates nutrients removal by more intense microbiological activity. This is also confirmed by the greater amount of ammonium nitrogen present in the streamflow. In the annual runoff of both streams, the ammonium form dominates dissolved inorganic nitrogen. The minimum concentration of phosphates is observed in winter, and ammonium in the spring flood. In the territory with a predominance of minerotrophic bogs the stream runoff is enriched in calcium, magnesium and silicon indicating specific major cation-rich groundwater input.
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Reinaldo Finkler, Nícolas, Flavia Tromboni, Iola Boëchat, Björn Gücker, and Davi Gasparini Fernandes Cunha. "Nitrogen and Phosphorus Uptake Dynamics in Tropical Cerrado Woodland Streams." Water 10, no. 8 (August 14, 2018): 1080. http://dx.doi.org/10.3390/w10081080.
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Pollution abatement through phosphorus and nitrogen retention is a key ecosystem service provided by streams. Human activities have been changing in-stream nutrient concentrations, thereby altering lotic ecosystem functioning, especially in developing countries. We estimated nutrient uptake metrics (ambient uptake length, areal uptake rate, and uptake velocity) for nitrate (NO3–N), ammonium (NH4–N), and soluble reactive phosphorus (SRP) in four tropical Cerrado headwater streams during 2017, through whole-stream nutrient addition experiments. According to multiple regression models, ambient SRP concentration was an important explanatory variable of nutrient uptake. Further, best models included ambient NO3–N and water velocity (for NO3–N uptake metrics), dissolved oxygen (DO) and canopy cover (for NH4–N); and DO, discharge, water velocity, and temperature (for SRP). The best kinetic models describing nutrient uptake were efficiency-loss (R2 from 0.47–0.88) and first-order models (R2 from 0.60–0.85). NO3–N, NH4–N, and SRP uptake in these streams seemed coupled as a result of complex interactions of biotic P limitation, abiotic P cycling processes, and the preferential uptake of NH4–N among N-forms. Global change effects on these tropical streams, such as temperature increase and nutrient enrichment due to urban and agricultural expansion, may have adverse and partially unpredictable impacts on whole-stream nutrient processing.
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Crandall, Trevor, Erin Jones, Mitchell Greenhalgh, Rebecca J. Frei, Natasha Griffin, Emilee Severe, Jordan Maxwell, et al. "Megafire affects stream sediment flux and dissolved organic matter reactivity, but land use dominates nutrient dynamics in semiarid watersheds." PLOS ONE 16, no. 9 (September 23, 2021): e0257733. http://dx.doi.org/10.1371/journal.pone.0257733.
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Climate change is causing larger wildfires and more extreme precipitation events in many regions. As these ecological disturbances increasingly coincide, they alter lateral fluxes of sediment, organic matter, and nutrients. Here, we report the stream chemistry response of watersheds in a semiarid region of Utah (USA) that were affected by a megafire followed by an extreme precipitation event in October 2018. We analyzed daily to hourly water samples at 10 stream locations from before the storm event until three weeks after its conclusion for suspended sediment, solute and nutrient concentrations, water isotopes, and dissolved organic matter concentration, optical properties, and reactivity. The megafire caused a ~2,000-fold increase in sediment flux and a ~6,000-fold increase in particulate carbon and nitrogen flux over the course of the storm. Unexpectedly, dissolved organic carbon (DOC) concentration was 2.1-fold higher in burned watersheds, despite the decreased organic matter from the fire. DOC from burned watersheds was 1.3-fold more biodegradable and 2.0-fold more photodegradable than in unburned watersheds based on 28-day dark and light incubations. Regardless of burn status, nutrient concentrations were higher in watersheds with greater urban and agricultural land use. Likewise, human land use had a greater effect than megafire on apparent hydrological residence time, with rapid stormwater signals in urban and agricultural areas but a gradual stormwater pulse in areas without direct human influence. These findings highlight how megafires and intense rainfall increase short-term particulate flux and alter organic matter concentration and characteristics. However, in contrast with previous research, which has largely focused on burned-unburned comparisons in pristine watersheds, we found that direct human influence exerted a primary control on nutrient status. Reducing anthropogenic nutrient sources could therefore increase socioecological resilience of surface water networks to changing wildfire regimes.
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Clark, Gregory M., David K. Mueller, and M. Alisa Mast. "NUTRIENT CONCENTRATIONS AND YIELDS IN UNDEVELOPED STREAM BASINS OF THE UNITED STATES." Journal of the American Water Resources Association 36, no. 4 (August 2000): 849–60. http://dx.doi.org/10.1111/j.1752-1688.2000.tb04311.x.
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Christensen, V. G., P. P. Rasmussen, and A. C. Ziegler. "Real-time water quality monitoring and regression analysis to estimate nutrient and bacteria concentrations in Kansas streams." Water Science and Technology 45, no. 9 (May 1, 2002): 205–19. http://dx.doi.org/10.2166/wst.2002.0240.
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An innovative approach currently is underway in Kansas to estimate and monitor constituent concentrations in streams. Continuous in-stream water-quality monitors are installed at selected U.S. Geological Survey stream-gaging stations to provide real-time measurement of specific conductance, pH, water temperature, dissolved oxygen, turbidity, and total chlorophyll. In addition, periodic water samples are collected manually and analyzed for nutrients, bacteria, and other constituents of concern. Regression equations then are developed from measurements made by the water-quality monitors and analytical results of manually collected samples. These regression equations are used to estimate nutrient, bacteria, and other constituent concentrations. Concentrations then are available to calculate loads and yields to further assess water quality in watersheds. The continuous and real-time nature of the data may be important when considering recreational use of a water body; developing and monitoring total maximum daily loads; adjusting water-treatment strategies; and determining high constituent concentrations in time to prevent adverse effects on fish or other aquatic life.
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Duarte, Sofia, Cláudia Pascoal, Frédéric Garabétian, Fernanda Cássio, and Jean-Yves Charcosset. "Microbial Decomposer Communities Are Mainly Structured by Trophic Status in Circumneutral and Alkaline Streams." Applied and Environmental Microbiology 75, no. 19 (July 31, 2009): 6211–21. http://dx.doi.org/10.1128/aem.00971-09.
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ABSTRACT In streams, the release of nitrogen and phosphorus is reported to affect microbial communities and the ecological processes they govern. Moreover, the type of inorganic nitrogen (NO3, NO2, or NH4) may differently impact microbial communities. We aimed to identify the environmental factors that structure aquatic microbial communities and drive leaf litter decomposition along a gradient of eutrophication. We selected five circumneutral (Portuguese) and five alkaline (French) streams differing in nutrient concentrations to monitor mass loss of alder leaves, bacterial and fungal diversity by PCR-denaturing gradient gel electrophoresis, fungal biomass and reproduction, and bacterial biomass during 11 weeks of leaf immersion. The concentrations of inorganic nutrients in the stream water ranged from 5 to 300 μg liter−1 soluble reactive phosphorus, 0.30 to 5.50 mg liter−1 NO3-N, 2 to 103 μg liter−1 NO2-N, and <4 to 7,100 μg liter−1 NH4-N. Species richness was maximum in moderately anthropized (eutrophic) streams but decreased in the most anthropized (hypertrophic) streams. Different species assemblages were found in subsets of streams with different trophic statuses. In both geographic areas, the limiting nutrient, either nitrate or phosphate, stimulated the microbial activity in streams of intermediate trophic status. In the hypertrophic streams, fungal biomass and reproduction were significantly lower, and bacterial biomass dramatically decreased at the site with the highest ammonium concentration. The limiting nutrients that defined the trophic status were the main factor structuring fungal and bacterial communities, whatever the geographic area. A very high ammonium concentration in stream water most probably has negative impacts on microbial decomposer communities.
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Hauer, FR, and CN Spencer. "Phosphorus and Nitrogen Dynamics in Streams Associated With Wildfire: a Study of Immediate and Longterm Effects." International Journal of Wildland Fire 8, no. 4 (1998): 183. http://dx.doi.org/10.1071/wf9980183.
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Stream nutrient data were collected both during a wildfire and over a subsequent five-year period. Sampling was from a series of paired watersheds located within and outside of the wildfire. Phosphorus and nitrogen concentrations increased from 5 to 60 fold over background levels during the first few days of the month-long wildfire with maximum recorded concentrations as high as 135 μg/L soluble reactive phosphorus, 261 μg/L ammonium, and 61 μg/L nitrate. Total phosphorus and total nitrogen during this same time period increased up to 206 μg/L and 349 mμg/L, respectively. Nutrient concentrations declined to background levels (<5-10 μg/L) within a few weeks after the fire. Over the following five years we observed dissolved nutrient concentrations reaching >40 μg/L soluble reactive phosphorus and >125 μg/L nitrate in impacted streams, concentrations >5 fold over those observed in control streams. In high gradient watersheds, all nutrients were easily transported to the streams with most notable impact during the early years after the fire. In less steep terrain, soluble reactive phosphorus concentrations were significantly higher 3 to 5 years after the fire, which also corresponded to relatively high spring hydrographs. In contrast, nitrogen compounds were observed to be significantly higher in concentration in fire impact streams in the years immediately following the fire. We attribute these differences in the rate of nutrient loads to be the result of the different mobilization mechanisms of phosphorus and nitrogen and the different soil and geomorphic settings of the watersheds drained by the different streams.
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Lázár, Attila N., A. J. Wade, P. G. Whitehead, C. Neal, and M. Loewenthal. "Reconciling observed and modelled phytoplankton dynamics in a major lowland UK river, the Thames." Hydrology Research 43, no. 5 (April 27, 2012): 576–88. http://dx.doi.org/10.2166/nh.2012.029.
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This study aims to elucidate the key mechanisms controlling phytoplankton growth and decay within the Thames basin through the application of a modified version of an established river-algal model and comparison with observed stream water chlorophyll-a concentrations. The River Thames showed a distinct simulated phytoplankton seasonality and behaviour having high spring, moderate summer and low autumn chlorophyll-a concentrations. Three main sections were identified along the River Thames with different phytoplankton abundance and seasonality: (i) low chlorophyll-a concentrations from source to Newbridge; (ii) steep concentration increase between Newbridge and Sutton; and (iii) high concentrations with a moderate increase in concentration from Sutton to the end of the study area (Maidenhead). However, local hydrologic (e.g. locks) and other conditions (e.g. radiation, water depth, grazer dynamics, etc.) affected the simulated growth and losses. The model achieved good simulation results during both calibration and testing through a range of hydrological and nutrient conditions. Simulated phytoplankton growth was controlled predominantly by residence time, but during medium–low flow periods available light, water temperature and herbivorous grazing defined algal community development. These results challenge the perceived importance of in-stream nutrient concentrations as the perceived primary control on phytoplankton growth and death.
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Altuna, Maddi, Eugènia Martí, Francesc Sabater, José Ramón Díez, Joan Lluís Riera, Félix Izco, and Arturo Elosegi. "Incorporating In-Stream Nutrient Uptake into River Management: Gipuzkoa Rivers (Basque Country, North Spain) as a Case Study." Sustainability 11, no. 9 (May 11, 2019): 2692. http://dx.doi.org/10.3390/su11092692.
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Gipuzkoa (Basque Country, North Spain) is an industrial region where investments in sanitation and wastewater treatment have improved water quality and partially recovered river biological communities. However, further technological improvements are unlikely. Our objective was to assess whether in-stream self-purification may contribute to improvement of the trophic state of rivers. We propose an integrative approach to assessing river water quality, which diagnoses problems, identifies likely causes and prescribes solutions. We first analysed the loads of nutrients transported by Gipuzkoa rivers and compared them with the potential nutrient uptake rates (estimated from published empirical regressions). In reaches where both of them were within one order of magnitude, we considered that the self-purification capacity of river channels may influence nutrient concentrations. Then, we selected some river reaches where no other water quality problems beyond nutrient concentrations occurred and ran the expert system STREAMES 1.0 to diagnose the problems and detect their causes. The studied reaches differed in their problems and in their potential solutions. We empirically determined nutrient retention in two streams by means of mass balances and slug nutrient additions. We detected large differences in retention capacity between reaches and siltation as one of the main problems affecting the self-purification capacity of the study streams. Finally, we used STREAMES 1.0 to identify potential solutions to specific river sections. The results obtained so far point towards an important potential of in-stream bioreactive capacity to reduce nutrient loads and to specific restoration activities that may improve the functionality and trophic status of the streams in Gipuzkoa.
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Fail, Joseph L., Bruce L. Haines, and Robert L. Todd. "Riparian forest communities and their role in nutrient conservation in an agricultural watershed." American Journal of Alternative Agriculture 2, no. 3 (1987): 114–21. http://dx.doi.org/10.1017/s0889189300001752.
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AbstractRiparian forests situated adjacent to agricultural uplands were studied to test the hypothesis that riparian forests intercept and utilize nutrients lost from these uplands. Production rates, tissue nutrient concentrations, and nutrient accretion rates of woody plants were compared between sites that were contiguous to agricultural areas (test sites) and sites that were separated from agricultural areas by grass buffer zones (reference sites). Net primary production was 10,344 kg ha–1yr–1, but trees within a riparian forest that received runoff directly from a pigpen (test site) had production rates that were 2.5 times higher than the average for all other sites. Above ground forest nutrient accretion rates were also highest at the pigpen test site. Woody plants in test site forests had, on the average, higher branch wood and leaf nutrient concentrations than plants in reference site forests. The data provide evidence that riparian forest communities within agricultural environments absorb and retain nutrients lost from agricultural uplands. As such they are important components of agricultural ecosystems helping to maintain acceptable stream water quality. It is suggested that ecologically sound agricultural practice should include longterm maintenance of natural riparian vegetation zones within agricultural areas.
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Smiley, Peter C., Kevin W. King, and Norman R. Fausey. "Public health perspectives of channelized and unchannelized headwater streams in central Ohio: a case study." Journal of Water and Health 8, no. 3 (March 9, 2010): 577–92. http://dx.doi.org/10.2166/wh.2010.160.
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Headwater streams constitute the majority of watersheds in the United States and many in the midwest have been channelized for agricultural drainage. Public health implications of water chemistry and aquatic insects within channelized and unchannelized headwater streams have not been explored. We sampled water chemistry and aquatic insects in two channelized and two unchannelized headwater streams in central Ohio from December 2005 until November 2008. Maximum concentrations of ammonium, nitrate plus nitrite, and chlorothalonil were greater in channelized streams. Nitrate plus nitrite and atrazine also exceeded drinking water standards more often in channelized streams. Maximum concentrations of simazine and the percentage of times it exceeded the drinking water standards were greater in unchannelized streams. The predicted hazard potential of nutrient and pesticide mixtures was greater in channelized streams. Mosquito abundance did not differ between stream types. Chironomid abundance was greater in channelized streams. Biting dipterans did not exhibit consistent abundance trends and only differed between stream types in the summer and fall. Our results suggest that if whole stream uptake of nutrients and pesticides is minimal in channelized headwater streams then nutrient and pesticide inputs from these streams may impact downstream drinking water sources. Our results also suggest channelized and unchannelized headwater streams are not serving as a significant source of mosquitoes.
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Ulén, Barbro. "Nutrient Exports from Two Agriculture-Dominated Watersheds in Southern Sweden." Hydrology Research 29, no. 1 (February 1, 1998): 41–56. http://dx.doi.org/10.2166/nh.1998.0003.
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Nutrient concentrations and exports were monitored for eight years in two agriculture-dominated watersheds in the central part of the Västgöta Plain in Sweden. The hydrology and the nutrient concentrations in the streams were very similar. Concentrations (monthly flow-weighted) of dissolved phosphate-phosphorus (PO4P) varied substantially during the year (from 0.03 to 0.27 mg 1−1) whereas concentrations of particulate phosphorus (PartP) varied less (from 0.03 to 0.16 mg −1). No trends in nutrient export during the eight years were found after flow-normalization of export data. Three wet periods dominated the long-term loads of the streams. Although a few events dominated annual yields of suspended solids (SS) from drainage pipes, standard deviation of annual mean SS concentration was reasonably constant between different years. However, when further developing phosphorus load models the variation in SS concentration should probably be considered. In-stream processes may contribute nearly as much to the phosphorus export as those occurring on and in arable soils in terms of their impact on the magnitude of phosphorus export. Total nitrogen (TotN) mean concentration was 5 mg 1−1 and was similar in drainage pipes and in the streams.
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Pucher, Matthias, Peter Flödl, Daniel Graeber, Klaus Felsenstein, Thomas Hein, and Gabriele Weigelhofer. "Complex interactions of in-stream dissolved organic matter and nutrient spiralling unravelled by Bayesian regression analysis." Biogeosciences 18, no. 10 (May 25, 2021): 3103–22. http://dx.doi.org/10.5194/bg-18-3103-2021.
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Abstract. Uptake and release patterns of dissolved organic matter (DOM) compounds and co-transported nutrients are entangled, and the current literature does not provide a consistent picture of the interactions between the retention processes of DOM fractions. We performed plateau addition experiments with five different complex DOM leachates in a small experimental stream impacted by diffuse agricultural pollution. The study used a wide range of DOM qualities by including leachates of cow dung, pig dung, corn leaves, leaves from trees, and whole nettle plants. We measured changes in nutrient and dissolved organic carbon (DOC) concentrations along the stream course and determined DOM fractions by fluorescence measurements and parallel factor (PARAFAC) decomposition. To assess the influences of hydrological transport processes, we used a 1D hydrodynamic model. We developed a non-linear Bayesian approach based on the nutrient spiralling concept, which we named the “interactions in nutrient spirals using Bayesian regression” (INSBIRE) approach. This approach can disentangle complex interactions of biotic and abiotic drivers of reactive solutes' uptake in multi-component DOM sources. It can show the variability of the uptake velocities and quantify their uncertainty distributions. Furthermore, previous knowledge of nutrient spiralling can be included in the model using prior probability distributions. We used INSBIRE to assess interactions of compound-specific DOM and nutrient spiralling metrics in our experiment. Bulk DOC uptake varied among sources, showing decreasing uptake velocities in the following order: corn > pig dung > leaves > nettles > cow dung. We found no correlations between bulk DOC uptake and the amounts of protein-like compounds or co-leached soluble reactive phosphorus (SRP). The fastest uptake was observed for SRP and the tryptophan-like component, while the other DOM components' uptake velocities more or less resembled that of the bulk DOC. Almost all DOM components showed a negative relationship between uptake and concentration, known as efficiency loss. Furthermore, we observed a few negative and (weak) positive interactions between the uptake and the concentration of different components, such as a decreased uptake of protein-like compounds at high concentrations of a high-molecular-weight humic-like compound. We also found an influence of the wetted width on the uptake of SRP and a microbially derived humic substance, which indicates the importance of the sediment–water interface for P and humic C cycling in the studied stream. Overall, we show that bulk DOC is a weak predictor of DOC uptake behaviour for complex DOM leachates. Individual DOM compound uptake, including co-leached nutrients, is controlled by both internal (quality-related) and external (environmental) factors within the same aquatic ecosystem. We conclude that the cycling of different C fractions and their mutual interaction with N and P uptake in streams is a complex, non-linear problem, which can only be assessed with advanced non-linear approaches, such as the presented INSBIRE approach.
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Díaz-Villanueva, Verónica. "Dissolved organic matter as P source for biofilms in two contrasting low-order streams." Fundamental and Applied Limnology / Archiv für Hydrobiologie 193, no. 2 (December 1, 2019): 131–42. http://dx.doi.org/10.1127/fal/2019/1234.
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Forest streams receive large amounts of leaves whose leachates are an important source of dissolved organic matter (DOM), providing not only carbon but also organic nutrients to the microbial communities in streams. I carried out a field study to evaluate the effect of different DOM concentrations on the biofilm structure and functional traits in two similar forest streams belonging to the same catchment. I compared biofilm biomass and nutri- ent content throughout one year, algal species composition, and biofilm community-level physiological profiles in two streams with different DOM concentration and aromaticity. Dissolved nutrient concentrations were higher in the stream with higher DOM concentration, with a concomitant higher biofilm biomass, and there was also a temporal pattern, with higher values during the autumn. Phosphorus content in biofilms was also higher in the high DOM stream, coincidently with a higher capacity of the community to utilize organic P source (glucose-1-P) as a substrate. In contrast, the biofilms from the stream with lower DOM concentrations preferentially used N-organic substrates (amino acids and amines). These results reveal that the biofilms of forest streams make use of organic matter nutrients, so that streams with different DOM loads may differ in biofilm biomass due to changes in both bacterial and autotrophic biomass. In addition, biofilm dynamics may be related to forest phenology, as the highest OM input in this deciduous forest is represented by tree leaves, which supply DOM through leachates, and in particular, with P-rich leachates. In conclusion, different DOM concentrations in two nearby streams led to differences in the community-level physiological profile, as has been previously demonstrated at larger spatial scales in oceans, lakes and along larger rivers.
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Hall, Lenwood W., Ronald D. Anderson, William D. Killen, and Raymond W. Alden. "An Analysis of Multiple Stressors on Resident Benthic Communities in a California Agricultural Stream." Air, Soil and Water Research 11 (January 1, 2018): 117862211877776. http://dx.doi.org/10.1177/1178622118777761.
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This 3-year study (2015-2017) was designed to characterize benthic communities (macroinvertebrates) and physical habitat in an agriculturally dominated waterbody in the Central Coast area of California (Santa Maria River). Benthic communities as represented by various metrics that represent richness, composition, tolerance/intolerance and trophic measures were used as response variables for the various stressors described below. Concurrent water quality evaluations, physical sediment parameters (grain size and total organic carbon [TOC]), pyrethroids, bulk metals—including simultaneously extracted metals (SEM) and acid volatile sulfides (AVS) ratios—and nutrients were measured. The relationship of various benthic metrics to physical habitat metrics, pyrethroids, metals, nutrients and sediment characteristics was evaluated for the 3-year data set. Total physical habitat scores in this watershed were considered to be poor. Samples collected for various sediment chemistry measurements were from depositional areas (fine grain areas primarily silt and clay) where hydrophobic chemicals such as pyrethroids could be found if sources exist. Dominant benthic taxa collected were generally considered to be tolerant to moderately tolerant of environmental stressors and rated as impaired based on a benthic index. Potentially toxic sediment concentrations of arsenic, cadmium and nickel were reported at various sites based on a comparison with existing threshold effect levels. Pyrethroid concentrations interpreted by using a highly protective toxics units approach with a laboratory sensitive taxon ( Hyalella) suggested potential toxicity at various sites. Nutrient concentrations could not be interpreted within the context of potential impairment because the State of California has not developed nutrient criteria. The results of the stepwise linear regression models comparing benthic metrics with all environmental variables showed that TOC was the most important variable shaping the benthic communities. In contrast, pyrethroids, metals and physical habitat were not shown to be significant factors shaping benthic communities. The summary multivariate canonical correlation analysis indicated that less stressed, more diverse benthic communities tended to be associated more with TOC-rich finer sediments and lower concentrations of phosphorous-based nutrients, and more stressed, less diverse benthic communities tended to be associated with less organically rich, somewhat less fine sediments and higher phosphorous concentrations.
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Gooseff, Michael N., David Van Horn, Zachary Sudman, Diane M. McKnight, Kathleene A. Welch, and William B. Lyons. "Stream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica." Biogeosciences 13, no. 6 (March 21, 2016): 1723–32. http://dx.doi.org/10.5194/bg-13-1723-2016.
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Abstract. Stream channels in the McMurdo Dry Valleys are characteristically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of the Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream ( ∼ 20 years of monitoring). Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.
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Ludlam, John P., and Allison H. Roy. "Understanding effects of small dams on benthic metabolism and primary production in temperate forested streams." Fundamental and Applied Limnology / Archiv für Hydrobiologie 193, no. 3 (April 21, 2020): 227–37. http://dx.doi.org/10.1127/fal/2020/1260.
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Dams can alter the chemical and physical conditions of downstream environments by increasing stream temperatures, altering nutrient limitation, reducing flow variability, and reducing fine sediment deposition. However, little is known about how fundamental stream ecosystem processes like productivity and respiration respond to dams. Nutrient diffusing substrates were installed in three dam streams and three control streams to evaluate the effect of dams on benthic gross primary productivity (GPP), respiration (R), and chlorophyll α production. Dam streams were an average of 5.6 °C warmer than control streams but GPP, R and chlorophyll α were not different between control and dam streams. Phosphorus enrichment increased heterotrophic R relative to controls (~1.8×) but not autotrophic GPP, R or chlorophyll α. Stream nutrient concentrations and nutrient limitation of heterotrophic R were similar in dam and control streams, suggesting that the dams had limited effects on nutrient transport downstream. Autotrophic GPP, R and chlorophyll α were limited by light and varied within and across streams, potentially masking our ability to detect differences caused solely by dams. Dams may alter stream ecosystem func- tion but consideration of other factors associated with and independent of dams is critical for predicting ecosystem responses to dams.
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Liu, Shuci, Dongryeol Ryu, J. Angus Webb, Anna Lintern, Danlu Guo, David Waters, and Andrew W. Western. "A Bayesian approach to understanding the key factors influencing temporal variability in stream water quality – a case study in the Great Barrier Reef catchments." Hydrology and Earth System Sciences 25, no. 5 (May 20, 2021): 2663–83. http://dx.doi.org/10.5194/hess-25-2663-2021.
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Abstract. Stream water quality is highly variable both across space and time. Water quality monitoring programmes have collected a large amount of data that provide a good basis for investigating the key drivers of spatial and temporal variability. Event-based water quality monitoring data in the Great Barrier Reef catchments in northern Australia provide an opportunity to further our understanding of water quality dynamics in subtropical and tropical regions. This study investigated nine water quality constituents, including sediments, nutrients and salinity, with the aim of (1) identifying the influential environmental drivers of temporal variation in flow event concentrations and (2) developing a modelling framework to predict the temporal variation in water quality at multiple sites simultaneously. This study used a hierarchical Bayesian model averaging framework to explore the relationship between event concentration and catchment-scale environmental variables (e.g. runoff, rainfall and groundcover conditions). Key factors affecting the temporal changes in water quality varied among constituent concentrations and between catchments. Catchment rainfall and runoff affected in-stream particulate constituents, while catchment wetness and vegetation cover had more impact on dissolved nutrient concentration and salinity. In addition, in large dry catchments, antecedent catchment soil moisture and vegetation had a large influence on dissolved nutrients, which highlights the important effect of catchment hydrological connectivity on pollutant mobilisation and delivery.
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Gooseff, M. N., D. Van Horn, Z. Sudman, D. M. McKnight, K. A. Welch, and W. B. Lyons. "Biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica." Biogeosciences Discussions 12, no. 17 (September 8, 2015): 14773–96. http://dx.doi.org/10.5194/bgd-12-14773-2015.
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Abstract. Stream channels in the McMurdo Dry Valleys are typically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream (~20 years of monitoring). Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, suspended sediments, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.
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Bolton, S. M., and T. J. Ward. "Scale Effects of Sediment-Related Transport of Phosphorus." Water Science and Technology 28, no. 3-5 (August 1, 1993): 473–81. http://dx.doi.org/10.2166/wst.1993.0450.
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Sediment and nutrient data from USGS gauged stream sites in New Mexico and from rainfall simulation experiments were compiled and analyzed. Above a suspended sediment concentration of about 500 mg/l, associated concentrations of total phosphorus are highest in overland flow and then progressively decrease from agricultural drains to ephemeral washes to undammed rivers. Within a stream type, sediment-related concentrations of total phosphorus typically differed between larger and smaller basins. Small rivers had higher phosphorus transport per unit of sediment load than larger rivers. Small and medium sized washes had different relationships between phosphorus and sediment than did large and very large washes.
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Mitchell, A., J. Reghenzani, J. Faithful, M. Furnas, and J. Brodie. "Relationships between land use and nutrient concentrations in streams draining a 'wet-tropics' catchment in northern Australia." Marine and Freshwater Research 60, no. 11 (2009): 1097. http://dx.doi.org/10.1071/mf08330.
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Differences in stream nutrient concentrations typically reflect upstream differences in land use. In particular, nitrate concentrations are greatly increased by losses from nitrogen (N) fertiliser applied to areas of intensive cropping. In the present study, a relationship between the area of such land use and the nitrate concentrations in the receiving streams was predicted. This relationship was tested using several data sets from the Tully basin, in the wet-tropics bioregion of north Queensland, Australia. The proportions of fertiliser-additive land use (FALU), mostly sugarcane and bananas, were correlated with the concentrations of nutrients in streams that drain these land uses. The data compared included two long-term sampling studies in the Tully River catchment and more recent, broader catchment sampling and plot-scale studies in this region. A strong relationship was shown for nitrate, but weaker relationships were observed for other N-nutrient and P-nutrient forms. Comparisons were made with contemporary and historical land-use changes in the Tully basin. The strong relationship of FALU with nitrate provides evidence that the nitrate exports from this catchment are largely derived from fertiliser use. This relationship can be used to derive nitrate run-off coefficients for fertilised land use in catchment models or to monitor changes following management to reduce fertiliser usage.
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Kämäri, J., K. Rankinen, L. Finér, S. Piirainen, and M. Posch. "Modelling the response of soil and runoff chemistry to forest harvesting in a low deposition area (Kangasvaara, eastern Finland)." Hydrology and Earth System Sciences 2, no. 4 (December 31, 1998): 485–95. http://dx.doi.org/10.5194/hess-2-485-1998.
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Abstract. A simple dynamic soil model developed to analyse the effects of atmospheric deposition and nutrient cycling on terrestrial ecosystems, SMART 2, was applied to the Kangasvaara catchment in eastern Finland. Given the historical deposition and forest growth patterns and reasonable values for the input parameters, SMART 2 was calibrated successfully to reproduce present-day soil and Kangasvaara catchment on the soil and runoff water chemistry under a future deposition scenario (GRP scenario). These impacts were also compared to the effects of further reducing the deposition of sulphur and nitrate under the maximum feasible reduction (MFR) scenario. The model demonstrates the consequences of breaking the nutrient cycle, and predicts that final cutting results in increased leaching of inorganic nitrogen and base cations from the cut part of the catchment for about 10 years. The resulting concentrations in the stream will depend on the ability of the buffer zones surrounding the stream to capture and utilize these nutrients.
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van Biervliet, Olly, Robert J. McInnes, Jonathan Lewis-Phillips, and Jonah Tosney. "Can an Integrated Constructed Wetland in Norfolk Reduce Nutrient Concentrations and Promote In Situ Bird Species Richness?" Wetlands 40, no. 5 (March 11, 2020): 967–81. http://dx.doi.org/10.1007/s13157-019-01247-7.
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Abstract Integrated Constructed Wetlands (ICWs) are potentially effective tools in the effort to restore aquatic ecosystems, and also they incorporate multiple co-benefits. An ICW was constructed in Norfolk, UK, to address the degradation of a stream and lake receiving treated effluent from a small Sewage Treatment Works (STW). Results demonstrated that: (1) nutrient concentrations significantly reduced from the ICW influent to the effluent (percentage reductions: total phosphorus [TP]: 78%, orthophosphate: 80%, total oxidised nitrogen [TON]: 65%, nitrate: 65%, nitrite: 67%, ammoniacal nitrogen: 62%), and mean dissolved oxygen concentrations increased (influent mean: 6.4 ± 1.4 mg l−1 effluent mean: 17.8 ± 3.3 mg l−1), (2) there were non-significant reductions in nutrient concentrations in the receiving stream (percentage reductions: TP: 23%, orthophosphate: 23%, TON: 26%, nitrate: 26%), with the exception of ammoniacal nitrogen (127% increase) and nitrite (76%) after ICW commissioning, and (3) mean in situ avian species richness increased from 10 to 27 species. Thus, the ICW substantially reduced nutrient concentrations, and had in situ conservation benefits. It is recommended that appropriately designed ICWs should be implemented widely and statutory authorities should ensure: 1) best-practice maintenance and 2) final effluent monitoring at both the STW and at the ICW outflows.
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Płaczkowska, Eliza, Karolina Mostowik, Heye Reemt Bogena, and Michael Leuchner. "The Impact of Partial Deforestation on Solute Fluxes and Stream Water Ionic Composition in a Headwater Catchment." Water 15, no. 1 (December 28, 2022): 107. http://dx.doi.org/10.3390/w15010107.
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To ensure the good chemical status of surface water across Europe, it is necessary to increase research on the comprehensive impact of land use and land cover changes, i.e., deforestation, on the natural environment. For this reason, we used data from 9-year environmental monitoring in the Wüstebach experimental catchment of the TERENO (Terrestrial Environmental Observatories) network to determine the impact of partial deforestation on solute fluxes and stream water ionic composition. In 2013, a partial deforestation experiment was conducted in the study area using a cut-to-length logging method. To this end, two headwater catchments were compared: one partially deforested (22% of the catchment area) and one untreated control catchment. The concentrations of ions in stream water, groundwater, and precipitation were analyzed: Ca2+, Mg2+, Na+, K+, Al3+, Fetot, Mn2+, NO3−, SO4−, and Cl−. Most of the ions (Na+, Ca2+, Mg2+, Cl−, and SO4−) showed decreasing trends in concentrations after deforestation, indicating a dilution effect in stream water due to the reduction of the supply of solutes with precipitation in the open deforested area. The fluxes of these ions decreased by 5–7% in the first year after deforestation, although the stream runoff increased by 5%. In the second year, the decrease in ion fluxes was greater, from 6% to 24%. This finding confirms that only limited soil erosion occurred after the deforestation because the soil was well protected during logging works by covering harvester lanes with branches. Only K+ and NO3− ions showed increasing trends in both concentrations and fluxes in the partially deforested catchment in the first two to three years after deforestation. Spruce die-offs, common in Europe, may decrease the concentration and fluxes of base cations in surface water in a nutrient-limited environment. However, the simultaneous planting of young broad-leaved trees with post-harvesting regrowth could create a nutrient sink that protects the catchment area from nutrient depletion.
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Li, Jiu Yi, Nian Peng Wu, Jin Li, Ai Min Wang, Yong Chen, Guo Tian Wang, and Dan Zheng. "Efficient Biological Nutrient Removal in a Membrane Bioreactor Using Denitrifying Phosphorus Removal and Simultaneous Nitrification and Denitrification." Applied Mechanics and Materials 507 (January 2014): 693–701. http://dx.doi.org/10.4028/www.scientific.net/amm.507.693.
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Biological nutrient removal (BNR) is generally integrated in municipal wastewater treatment plants to alleviate the impact of treated effluent on receiving watersheds. This paper studies the performance of BNR in a membrane bioreactor system consisting of anaerobic, anoxic, micro-aerobic and aerobic compartments treating a synthetic wastewater containing low organic matters. The membrane bioreactor system designed an anti-stream, stepwise return flow scheme to produce ideal conditions for the occurrence of simultaneous nitrification and denitification and denitrifying phosphorus removal processes. The proposed membrane reactor system has established higher biomass concentrations and ideal environments for biological nutrient removal processes, which results in high nutrient removal efficiencies treating low organic wastewaters. Four compartment configurations in the reactor system minimized the impact of oxidized nitrogen species in return flow on phosphorus release in the anaerobic tank and the anti-stream, stepwise return flow scheme encouraged the utilization of nitrate as the electronic acceptor in phosphorus uptake in the micro-aerobic tank. Denitrifying phosphorus removal and simultaneous nitrification and denitrification processes are the main mechanisms responsible for efficient nutrient removal. High phosphorus release activities and high phosphate concentration in the anaerobic tank make it is potentially feasible to recover phosphorus resource from wastewater.
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Williams, Clayton J., Paul C. Frost, Brian K. Ginn, Jiri Marsalek, and Marguerite A. Xenopoulos. "Add a dash of salt? Effects of road de-icing salt (NaCl) on benthic respiration and nutrient fluxes in freshwater sediments." Limnetica 42, no. 2 (February 17, 2023): 1. http://dx.doi.org/10.23818/limn.42.17.
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Winter road salt applications are increasing chloride concentrations in many freshwater ecosystems. This trend is alarming, giv¬en chloride’s potential to impair aquatic ecosystems. Short- and long-term exposure to salt could affect ecosystem metabolism and nutrient cycles. Here, we examine connections between chloride concentrations, water quality conditions, benthic respi¬ration, and sediment-water nutrient flux throughout a large (722 km2) lake and its catchment. Aquatic locations experiencing high concentrations of chloride are indicators of anthropogenic activities and are often associated with additional pollutants. We used sediment core flow-through incubations under ambient and enriched chloride concentrations to determine the effects of road salt on benthic respiration and nutrient fluxes in stream, stormwater pond, and lake sites. Salt (as sodium chloride) ad¬ditions caused a significant overall increase in benthic respiration. Acute exposure to road salt caused the strongest increase in benthic respiration when water was warm and at sites that had low (< 50 mg Cl-/L) or high (> 400 mg Cl-/L) ambient chloride concentrations or when water was cold and sites had intermediate (100-400 mg Cl-/L) ambient chloride concentrations. Nitrate flux responded less uniformly to salt additions. Depending on waterbody type and season, ambient nitrate flux into the sediment was similar, increased, or decreased post-chloride addition. Dissolved phosphorus flux was not significantly impacted by salt additions. Across lake and stream sites, our results supported the hypothesis that chloride causes increased respiration while nutrient cycles were weakly and inconsistently altered under experimental pulse road salt additions.
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Larsen, S. E., B. Kronvang, J. Windolf, and L. M. Svendsen. "Trends in diffuse nutrient concentrations and loading in Denmark: statistical trend analysis of stream monitoring data." Water Science and Technology 39, no. 12 (June 1, 1999): 197–205. http://dx.doi.org/10.2166/wst.1999.0547.
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The Danish Monitoring Programme reveals that diffuse sources are currently the major source of nutrient input to the aquatic environment. Nutrient concentration and loading data for about 50 small agricultural catchments and seven undisturbed catchments reveal that agriculture is the major diffuse source, average annual nitrogen (N) and phosphorus (P) concentration and loading being respectively, 5.1- and 6.8-fold, and 2.7- and 3.9-fold greater in streams draining agricultural catchments than in streams draining undisturbed catchments during the period 1989–96. A statistical trend analysis (discharge adjusted Mann-Kendall seasonal test) applied to long-term time series (1967–96) in three streams revealed an upward trend in nitrate concentration in Skjern Å (p<0.1%), Odense Å (p=5.7%) and GudenÅ (p=11%) during the 15-year period 1967-81, whereas there was no significant trend during the following 15-year period (1982-96). There was a significant downward trend in P concentration in all three streams over the 30-year period. Statistical analysis of recent trends (1989-96) in 77 (N) and 40 (P) streams draining small agricultural catchments revealed a median annual decrease of 0.073 mg N 1−1 and 0.0034 mg P 1−1 (Sen's slope estimator). The observed trend was only significant in 6 of the streams tested at the 5% level and 27 at the 10% level, however. The median annual decrease in N and P concentrations was higher in streams draining loamy catchments (0.092 mg N 1−1 and 0.0035 mg P 1−1) than in streams draining sandy catchments (0.040 mg N 1−1 and 0.0005 mg P 1−1).
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Gorski, Galen, and Margaret A. Zimmer. "Hydrologic regimes drive nitrate export behavior in human-impacted watersheds." Hydrology and Earth System Sciences 25, no. 3 (March 18, 2021): 1333–45. http://dx.doi.org/10.5194/hess-25-1333-2021.
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Abstract. Agricultural watersheds are significant contributors to downstream nutrient excess issues. The timing and magnitude of nutrient mobilization in these watersheds are driven by a combination of anthropogenic, hydrologic, and biogeochemical factors that operate across a range of spatial and temporal scales. However, how, when, and where these complex factors drive nutrient mobilization has previously been difficult to capture with low-frequency or spatially limited data sets. To address this knowledge gap, we analyzed daily nitrate concentration (c) and discharge (Q) data for a 4-year period (2016–2019) from five nested, agricultural watersheds in the midwestern United States that contribute nutrient loads to the Gulf of Mexico. These records allow us to investigate nutrient mobilization patterns at a temporal and spatial resolution not previously possible. The watersheds span two distinct landforms shaped by differences in glacial history, resulting in natural soil properties that necessitated different drainage infrastructure across the study area. To investigate nutrient export patterns under different hydrologic conditions, we partitioned the hydrograph into stormflow and baseflow periods and examined those periods separately through the analysis of their concentration–discharge (c–Q) relationships on annual, seasonal, and event timescales. Stormflow showed consistent chemostatic patterns across all seasons, while baseflow showed seasonally dynamic c–Q patterns. Baseflow exhibited chemodynamic conditions in the summer and fall and more chemostatic conditions in the winter and spring, suggesting that water source contributions during baseflow were nonstationary. Baseflow chemodynamic behavior was driven by low-flow, low-NO3- conditions during which in-stream and near-stream biological processing likely moderated in-stream NO3- concentrations. Additionally, inputs from deeper groundwater with longer residence times and lower-NO3- concentration likely contributed to low-NO3- conditions in stream, particularly in the larger watersheds. Stormflow c–Q behavior was consistent across watersheds, but baseflow c–Q behavior was linked to the intensity of agriculture and the density of built drainage infrastructure, with more drainage infrastructure associated with higher loads and more chemostatic export patterns across the watersheds. This suggests that the way humans replumb the subsurface in response to geologic conditions has implications for hydrologic connectivity, homogenization of source areas, and, subsequently, nutrient export during both baseflow and stormflow. Our analysis also showed that anomalous flow periods greatly influenced overall c–Q patterns, suggesting that the analysis of high-resolution records at multiple scales is critical when interpreting seasonal or annual patterns.
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Abelho, M., M. Moretti, J. França, and M. Callisto. "Nutrient addition does not enhance leaf decomposition in a Southeastern Brazilian stream (Espinhaço mountain range)." Brazilian Journal of Biology 70, no. 3 suppl (October 2010): 747–54. http://dx.doi.org/10.1590/s1519-69842010000400007.
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A decomposition experiment using eucalyptus leaves was carried out in a Southeastern Brazilian mountain stream located at the transition between the Cerrado and the Atlantic Forest to test whether nutrient addition increases microbial and invertebrate colonisation and accelerates breakdown rates. The results show that none of the tested variables was significantly affected by nutrient addition, despite the average increase in ATP concentrations and invertebrate colonisation observed in the fertilised leaf bags. This could mean that breakdown in the stream was already at its maximum due to the relatively high water temperature and nutrient content, or that the breakdown rate of eucalyptus leaves was too fast to allow the detection of any effects of nutrient addition. Breakdown rates of eucalyptus leaves were much faster than the values reported in literature for most species in Brazilian Cerrado streams, suggesting that the replacement of the natural vegetation by eucalyptus may affect nutrient dynamics in the region.
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Hill, Alan R., and Donna J. Lymburner. "Hyporheic zone chemistry and stream-subsurface exchange in two groundwater-fed streams." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 2 (February 1, 1998): 495–506. http://dx.doi.org/10.1139/f97-250.
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Data from two headwater streams in southern Ontario provide support for conceptual models that suggest that hyporheic zone influence on stream nutrient retention is determined by the extent of surface-groundwater exchange and subsurface chemical transformation rates. The hyporheic zone (>10% stream water) was delineated by a chemical mixing equation using differences in background stream and groundwater chloride concentrations and by injections of chloride to stream flow. Good agreement between the two methods confirmed that the extent of stream-groundwater exchanges can be successfully estimated using background conservative ions as a tracer technique. During low stream flows in May-October the depth of the hyporheic zone was 2-15 cm in a 12-m sand-bottom pool, debris dam, pool reach of Glen Major stream and 15-20 cm in a 16-m gravel riffle reach of Duffin Creek. Differences between observed NO3 concentrations and concentrations predicted from background chloride indicated depletion of NO3 in the hyporheic zone at a few locations in Glen Major and at 5-10 cm depth throughout the Duffin Creek reach. NO3 and NH4 injected into stream water were reactive at only a few hyporheic sites in the streams. Upstream-downstream comparisons during injections indicated that stream retention was minor.
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Chase, Justin W., Glenn A. Benoy, and Joseph M. Culp. "Combined effects of nutrient enrichment and inorganic sedimentation on benthic biota in an experimental stream system." Water Quality Research Journal 52, no. 3 (August 8, 2015): 151–65. http://dx.doi.org/10.2166/wqrj.2017.038.
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Sedimentation and nutrient loading are among the most prevalent threats to fluvial ecosystem integrity. This study employed artificial streams (mesocosms) to simulate individual and combined impacts of nutrient enrichment and deposited fine sediment on benthic biota. Ninety-six circular mesocosms were used in a 21-day crossed experiment that measured the impact of three substrate compositions (0, 25, and 50% fines <2 mm) and four nitrogen concentrations (17, 22, 43, and 94 μg L–1 (soluble inorganic nitrogen)) on periphyton and benthic macroinvertebrate assemblages. Permutational multivariate analysis of variance (PERMANOVA) of macroinvertebrate assemblages indicated substantial shifts in structural composition, while univariate models for Lepidostomatidae and total Ephemeroptera, Plecoptera and Trichoptera revealed that nutrient and sediment subsidies related to single factors were suppressed by an additional stressor. Stressor mechanism overlap was evident at higher treatment levels, as moderate nutrient enrichment increased nutritional resources but high nitrogen concentrations lead to substrate smothering by periphyton, contributing to habitat degradation originating from inorganic sedimentation. Our study is consistent with research showing that nutrient loading and sedimentation interact to deteriorate lotic systems beyond levels attributable to either individual stressor. Management practices and pollution standards need to incorporate relationships between stressors tightly co-vary in natural settings.