Статті в журналах з теми "Internal loading of nitrogen and phosphorus"
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1
Findlay, D. L., R. E. Hecky, L. L. Hendzel, M. P. Stainton, and G. W. Regehr. "Relationship Between N2-Fixation and Heterocyst Abundance and its Relevance to the Nitrogen Budget of Lake 227." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 10 (October 1, 1994): 2254–66. http://dx.doi.org/10.1139/f94-229.
Повний текст джерелаАнотація:
A significant relationship between seasonal N2-fixation rate and heterocyst abundance has been found in Lake 227 and can be modelled to estimate areal rates of N2-fixation based on the known historical phytoplankton records. Experimental imposition of low nitrogen (N): phosphorus (P) loading ratios stimulated N,-fixation. The N:P molar ratio of the internal pool of nutrients oscillates around a mean of 30:1, despite experimental loading ratios that vary from 13:1 to 0. Maintenance of this internal nutrient mass ratio requires preferential regeneration of N through time at all loading rates. Heterocystous, cyanobacteria blooms are most predictable during imposition of a very low external loading N:P ratio and high P loading relative to natural sources. Knowledge of the internal loading N:P ratio and relative contribution of internal and external loadings are required for predicting blooms at intermediate external N:P loading rates. The internal N:P ratio has fluctuated within narrow limits over 25 yr of nearly constant P loading because of adjustments in N2-fixation, N sedimentation, and denitrification, which have counterbalanced changing experimental N loading regimes.
2
Zhu, Yafei, Andrew McCowan, and Perran L. M. Cook. "Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon." Biogeosciences 14, no. 19 (October 6, 2017): 4423–33. http://dx.doi.org/10.5194/bg-14-4423-2017.
Повний текст джерелаАнотація:
Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.
3
Huang, Jian Jun, Yu Hong Li, and Ya Jie Gao. "Ferric Nitrate Suppresses Internal Phosphorus Loading in Municipal River." Advanced Materials Research 393-395 (November 2011): 1242–46. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.1242.
Повний текст джерелаАнотація:
The application of nitrate is an accepted procedure to manage eutrophication municipal rivers by controlling the phosphorus release from sediments into overlying water and offering electron acceptor for microorganism metabolism. In situ laboratory studies were carried out in simulated reactors to evaluate the potential of ferric nitrate for remediation municipal river sediment. Ferric nitrate could greatly improve the ability of bio-treatment properties for sediment. Two dose remediation experiment of ferric nitrate (70g and 35g per square meter) was carried out lasting 28 weeks. Observations showed that ferric nitrate could suppressed the release of phosphorus from the sediments. At the same time the TN concentration could reduce to common level compared to blank reactor by denitrification. As a whole the dose of 35g per square meter ferric nitrate is better. The results suggest that knowledge of a municipal river’s nitrogen budget may be a useful tool in the design of municipal river remediation efforts.
4
White, Sarah A., Milton D. Taylor, Stewart L. Chandler, Ted Whitwell, and Stephen J. Klaine. "Remediation of Nitrogen and Phosphorus from Nursery Runoff during the Spring via Free Water Surface Constructed Wetlands." Journal of Environmental Horticulture 28, no. 4 (December 1, 2010): 209–17. http://dx.doi.org/10.24266/0738-2898-28.4.209.
Повний текст джерелаАнотація:
Abstract Agricultural operations face increasing pressure to remediate runoff to reduce deterioration of surface water quality. Some nursery operations use free water surface constructed wetland systems (CWSs) to remediate nutrient-rich runoff. Our objectives were twofold, first to examine the impact of two hydraulic retention times (HRT, 3.5 and 5.5 day) on CWS performance, and second to determine if increased nutrient loading from internal CWS and nursery sources during the spring contributed to nutrient export in excess of regulatory limits. We quantified nutrient loading and removal efficiency in a free water surface CWS from late winter through late spring over three years and monitored various water quality parameters. Total nitrogen in runoff was reduced from 20.6 ± 2.8 mg·liter−1 (ppm) to 4.1 ± 1.3 mg·liter−1 (ppm) nitrogen after CWS treatment. Phosphorus dynamics in the CWS were more variable and unlike nitrogen dynamics were not consistently influenced by water temperature and hydraulic loading rate. Phosphorus concentrations were reduced from 1.7 ± 0.8 mg·liter−1 (ppm) PO4-P in influent to 1.2 ± 0.6 mg·liter−1 (ppm) PO4-P in CWS effluent, but substantial variability existed among years in both phosphorus loading and removal rates. The CWS was able to efficiently remediate nitrogen even under high spring loading rates.
5
Ding, Shiming, Musong Chen, Mengdan Gong, Xianfang Fan, Boqiang Qin, Hai Xu, ShuaiShuai Gao, Zengfeng Jin, Daniel C. W. Tsang, and Chaosheng Zhang. "Internal phosphorus loading from sediments causes seasonal nitrogen limitation for harmful algal blooms." Science of The Total Environment 625 (June 2018): 872–84. http://dx.doi.org/10.1016/j.scitotenv.2017.12.348.
Повний текст джерела
6
Buzzelli, C., Y. Wan, P. H. Doering, and J. N. Boyer. "Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA." Biogeosciences Discussions 10, no. 2 (February 11, 2013): 2377–413. http://dx.doi.org/10.5194/bgd-10-2377-2013.
Повний текст джерелаАнотація:
Abstract. Interactions among watershed nutrient loading, circulation, and biogeochemical cycling determine the capacity of estuaries to accommodate introduced nutrients. Baseline quantification of loading, flushing time, export, and internal processes is essential to understand responses of sub-tropical estuaries to variable climate and nutrient loading. The goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River Estuary (CRE) and the St. Lucie Estuary (SLE), from 2002–2008 spanning various climatic conditions. The Land Ocean Interactions in the Coastal Zone (LOICZ) Biogeochemical Model was used to generate water, salt, and (DIN and DIP) budgets. The predicted increase in internal DIN production for the CRE vs. the SLE was associated with increased external DIN loading. Water column DIN concentrations decreased and stabilized in both estuaries as flushing time increased to > 10 d. The CRE demonstrated heterotrophy or balanced metabolism across all seasonal budgets. Although the SLE was also sensitive to DIN loading, system autotrophy and net ecosystem metabolism increased with DIP loading to this estuary. This included a huge DIP consumption and bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge in 2005. Additionally, while denitrification offered a loss pathway for inorganic nitrogen in the CRE, this potential was not evident for the smaller and more anthropogenically altered St. Lucie Estuary. Disparities between total and inorganic loading ratios suggested that management actions should examine the role of dissolved organic nitrogen (DON) in attempts to reduce both nitrogen and phosphorus inputs to the SLE. Establishment of quantitative loading limits for anthropogenically impacted estuaries requires an understanding of the inter-seasonal and inter-annual relationships for both N and P, circulation and flushing, variability in plankton community composition, and the dynamics of DON.
7
Zhan, Ju Hong, Sha Deng, Zhao Xin Li, Yu Luo, Ting Ting Zhao, Hua Ying Liu, Xiao Li, and Xue Jun Pan. "The Effects of Estuary Dredging on Removing Nitrogen and Phosphorus in Dianchi Lake, China." Advanced Materials Research 518-523 (May 2012): 2895–99. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.2895.
Повний текст джерелаАнотація:
Sediment dredging is currently the most commonly selected option for getting rid of contaminated sediments. In this study, the effects of estuary dredging on removing nitrogen and phosphorus were investigated by comparing the different vertical nutrient content between the dredged and un-dredged areas in Dianchi Lake. The results showed that the contents of total nitrogen and total phosphorus in the un-dredged areas were relatively higher than that in dredged areas. Besides, the contents of bio-available nitrogen and phosphorus represented the similar results, only a few dredged spots showed a higher potential releasing capacity. Therefore, with the reduction of internal nutrient loading, it indicated that sediment dredging might be an effective and reliable way to improve such eutrophic lakes.
8
Lee, Hye Won, Yong Seok Lee, Jonggun Kim, Kyoung Jae Lim, and Jung Hyun Choi. "Contribution of Internal Nutrients Loading on the Water Quality of a Reservoir." Water 11, no. 7 (July 9, 2019): 1409. http://dx.doi.org/10.3390/w11071409.
Повний текст джерелаАнотація:
Sediment plays an important role in the water quality of a lake by acting as both a nutrient source and sink. The amount of phosphorus and nitrogen in the water depends on the internal load from the sediment as well as the external load. To estimate the effects of sediment load on the water quality of a reservoir, we applied a three-dimensional hydrodynamic and transport model based on the benthic chamber experimental results at Euiam Lake, South Korea. As shown in the sensitivity analysis results, the eutrophication period could be significantly extended by a change of phosphorus flux rates from the sediments. The increased phosphorus flux from the sediments intensifies the algal growth of Euiam Lake, which could cause serious algal bloom during spring and fall. This study provides information on nutrient concentrations in the sediment of Euiam Lake, verifies the role of the sediment as a source or sink of nutrients, and evaluates the effect of sediment release of nutrients and contaminants on water quality. This research is a useful tool in determining the effects of internal load in lakes and establishing the operation guideline for sediment management in order to maintain feasible water quality for beneficial use.
9
Lehman, John T. "Nuisance cyanobacteria in an urbanized impoundment: interacting internal phosphorus loading, nitrogen metabolism, and polymixis." Hydrobiologia 661, no. 1 (November 6, 2010): 277–87. http://dx.doi.org/10.1007/s10750-010-0535-x.
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10
Buzzelli, C., Y. Wan, P. H. Doering, and J. N. Boyer. "Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA." Biogeosciences 10, no. 10 (October 24, 2013): 6721–36. http://dx.doi.org/10.5194/bg-10-6721-2013.
Повний текст джерелаАнотація:
Abstract. Interactions among geomorphology, circulation, and biogeochemical cycling determine estuary responses to external nutrient loading. In order to better manage watershed nutrient inputs, the goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River estuary (CRE) and the St. Lucie Estuary (SLE), from 2002 to 2008. The Land–Ocean Interactions in the Coastal Zone (LOICZ) approach was used to generate water, salt, and DIN and DIP budgets. Results suggested that internal DIN production increases with increased DIN loading to the CRE in the wet season. There were hydrodynamic effects as water column concentrations and ecosystem nutrient processing stabilized in both estuaries as flushing time increased to >10 d. The CRE demonstrated heterotrophy (net ecosystem metabolism or NEM < 0.0) across all wet and dry season budgets. While the SLE was sensitive to DIN loading, system autotrophy (NEM > 0.0) increased significantly with external DIP loading. This included DIP consumption and a bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge to the SLE in 2005. Additionally, while denitrification provided a microbially-mediated N loss pathway for the CRE, this potential was not evident for the SLE where N2 fixation was favored. Disparities between total and inorganic loading ratios suggested that the role of dissolved organic nitrogen (DON) should be assessed for both estuaries. Nutrient budgets indicated that net internal production or consumption of DIN and DIP fluctuated with inter- and intra-annual variations in freshwater inflow, hydrodynamic flushing, and primary production. The results of this study should be included in watershed management plans in order to maintain favorable conditions of external loading relative to internal material cycling in both dry and wet seasons.
11
Dondajewska, Renata, Ryszard Gołdyn, Beata Messyasz, Katarzyna Kowalczewska-Madura, and Sławek Cerbin. "A shallow lake in an agricultural landscape – water quality, nutrient loads, future management." Limnological Review 19, no. 1 (March 1, 2019): 25–35. http://dx.doi.org/10.2478/limre-2019-0003.
Повний текст джерелаАнотація:
Abstract Qualitative analyses of nitrogen and phosphorus loads reaching the lake ecosystem provide a basis for pollution control, which is of paramount importance in shallow lakes due to the rapid turn-over of matter and energy. The studies of both external and internal loading were conducted in Lake Łeknenskie, a very shallow, through-flow lake situated in Western Poland. Strong eutrophication is manifested in rich rush vegetation and a lack of submerged macrophytes as well as nitrogen and phosphorus concentrations (max 13.04 mg N dm−3 and 0.32 mg P dm−3, respectively). Constant domination of cyanobacteria in the phytoplankton community was noted in almost all seasons with a 98% share in summer, resulting in 20 cm water transparency and 223 μg dm−3 of chlorophyll-a. The zooplankton community was dominated by rotifers. The main source of nutrients was the River Nielba. Spatial external nutrient loading was 1.93 g P m−2 yr−1 and 77.55 g N m−2 yr−1. An even higher load of phosphorus was released from the bottom sediments, 2.18 g P m−2 yr−1. A comprehensive action plan is required, aiming at the reduction of both external and internal nutrient loading. A series of solutions regarding local environmental conditions should be applied in the lake catchment, including biogeochemical barriers, denitrification walls, artificial retention basins or wetlands, but most of all – improvement in the functioning of the wastewater treatment plant. Restoration is possible, however, protection measures reducing external loading should be undertaken prior to phosphorus inactivation in the water column and in the bottom sediments, supported by biological methods e.g. biomanipulation.
12
Kowalczewska-Madura, Katarzyna, Renata Dondajewska-Pielka, and Ryszard Gołdyn. "The Assessment of External and Internal Nutrient Loading as a Basis for Lake Management." Water 14, no. 18 (September 12, 2022): 2844. http://dx.doi.org/10.3390/w14182844.
Повний текст джерелаАнотація:
Successful management of lake ecosystems used for recreation requires firstly an identification of nutrient sources. It is necessary to identify the factors causing the deterioration of water quality and to plan measures for their mitigation. Analyses of the external and internal nutrient loading were carried out for the hypereutrophic Raczyńskie Lake. The study included flows from lake tributaries, stormwater runoff from impermeable areas and direct catchment impact as external sources of nitrogen and phosphorus, as well as bottom sediments as an internal source of phosphorus. In the case of external sources, the largest load (about 80% of N and 67% of P) is supplied from croplands via the shoreline. Both external and internal loading was characterized by distinct seasonal variability. The loads from watercourses supplying the lake played the most significant role in spring, whereas the release of phosphorus from bottom sediments (accounting for 81.4% of the total P load) was responsible for cyanobacterial blooms in summer. In order to improve Raczyńskie Lake water quality it is crucial to implement both in-catchment and in-lake measures by means of diversion of stormwater runoff, reduction of nutrient content in some of tributaries at their inflow to the lake (gabions filled with dolomite surrounded by macrophytes) and restoration treatments aiming at the inactivation of phosphorus in the water column and reduction of its release from sediments.
13
Kauppi, L., O. P. Pietiläinen, and S. Knuuttila. "Impacts of Agricultural Nutrient Loading on Finnish Watercourses." Water Science and Technology 28, no. 3-5 (August 1, 1993): 461–71. http://dx.doi.org/10.2166/wst.1993.0449.
Повний текст джерелаАнотація:
Eutrophication of lakes, rivers and coastal waters is the main environmental problem caused by agriculture in Finland. Water quality of most Finnish watercourses is good or excellent, but in the intensively cultivated region of southern and western Finland the turbidity of water as well as algal blooms are a common problem. Generally, phosphorus is the limiting nutrient for primary production in Finnish lakes, but in eutrophic lakes and coastal waters the role of nitrogen becomes more important. Nitrogen from agriculture enters the watercourses mainly in dissolved form. By contrast, most phosphorus is transported in association with small particles. According to bioassays the algal availability of this paniculate P is very low. Therefore, the eutrophying effect of agriculture can be estimated on the basis of dissolved nutrients. In shallow lakes, typical in agricultural regions, the release of dissolved P from the bottom sediment often induces the development of N2-fixing blue- green algal blooms. In some cases the internal load may exceed the external load. For the recovery of such a lake the introduction of better agricultural practices in the drainage basin has to be coupled with in-lake measures.
14
Kneis, D., R. Knoesche, and A. Bronstert. "Analysis and simulation of nutrient retention and management for a lowland river-lake system." Hydrology and Earth System Sciences 10, no. 4 (August 8, 2006): 575–88. http://dx.doi.org/10.5194/hess-10-575-2006.
Повний текст джерелаАнотація:
Abstract. In the context of the European Water Framework Directive, we studied the possible impact of reduced emissions on phosphorus and nitrogen concentrations in a lowland river-lake system (Havel River, Germany). As a prerequisite, we quantified the retention of nutrients in the river from mass balances and deduced its seasonal variation. We detected that about 30% of the total nitrogen input is retained within the surveyed river section. In contrast, phosphorus release from sediments was shown to cause a considerable increase in present P concentrations. Average net phosphorus release rates of about 20 mg P m−2 d−1 in late summer were estimated for the Havel Lakes. Based on the observed patterns of N retention and P release we parametrized a newly developed water quality simulation program (TRAM), which allows alternative model approaches of different complexity to be implemented and tested. To account for the future trend of internal P loading, the phosphorus excess in lake sediments was estimated from core samples and included in the model as a state variable. For analyzing scenarios of reduced nutrient emissisions, the water quality simulation program was linked to mesoscale hydrological catchment models for the first time. From scenario simulations we conclude that internal P loading is likely to counteract efforts of emission control for decades. Even by significant reductions in external P loads, a persistent phosphorus limitation of primary production can hardly be established in the analyzed time frame of 13 years. Though in the short run a continued reduction in nitrogen loads appears to be the more promising approach of eutrophication management, we recommend enhanced efforts to diminish both N and P emissions.
15
Kim, K. S., K. M. Cho, H. Choi, and I. S. Kim. "A pilot study on nitrogen and phosphorus removal by a modified photostrip process." Water Science and Technology 42, no. 3-4 (August 1, 2000): 199–204. http://dx.doi.org/10.2166/wst.2000.0380.
Повний текст джерелаАнотація:
A pilot plant with a capacity of 20∼30m3/day was operated for 10 months for simultaneous removal of nitrogen and phosphorus by a modified Phostrip process. In the process, a denitrification tank was installed before the aeration tank in the Phostrip process, which was developed mainly for phosphorus removal. To maintain the effluent TKN concentration in the range of 1∼3 mg/L, the allowable maximum TKN loading rate in the aeration tank was found to be 0.065 kg TKN/kg MLSS·d. The nitrification rate in the aeration tank increased as the influent COD/TKN ratio declined. The optimal internal recycle rate from the aeration tank to the denitrifier was found to be 2Q when the yearly average COD and TKN concentration of the influent was 197 mg/L and 37.1 mg/L, respectively. To keep the effluent T-P concentration below 1 mg/L, T-P loading to the aeration tank should be less than 0.008 kg T-P/kg MLSS·d at the sludge recycle rate of 0.3Q from the 2nd clarifier to P-stripper. However, the loading should be kept at less than 0.0065 kg T-P/kg MLSS·d at the sludge recycle rate of 0.15Q.
16
Sosiak, Al. "Long-term response of periphyton and macrophytes to reduced municipal nutrient loading to the Bow River (Alberta, Canada)." Canadian Journal of Fisheries and Aquatic Sciences 59, no. 6 (June 1, 2002): 987–1001. http://dx.doi.org/10.1139/f02-071.
Повний текст джерелаАнотація:
The biomass of periphyton and aquatic macrophytes (Potamogeton vaginatus and Potamogeton pectinatus) in the Bow River was sampled over 16 years to assess the response of these plants to improved phosphorus (19821983) and nitrogen removal (19871990) at Calgary's two municipal wastewater treatment plants. These improvements in treatment reduced total phosphorus loading to the Bow River by 80%, total ammonia loading by 53%, and nitrite + nitrate loading by 50%. No change in periphytic biomass was detected after enhanced phosphorus removal where total dissolved phosphorus (TDP) in river water remained relatively high (1033 μg·L1). However, periphytic biomass declined at sites further downstream with TDP < 10 μg·L1. Regression analysis predicted that nuisance periphyton biomass (>150 mg·m2) occurred at TDP > 6.4 μg·L1 (95% confidence interval: 1.97.6 μg·L1). Macrophyte biomass was inversely correlated with discharge and was lower during high-discharge years. Biomass also declined following enhanced nutrient removal, with the greatest decrease following reduced nitrogen discharge. These results provide the first evidence for a response of periphyton and aquatic macrophytes to enhanced nutrient removal from municipal wastewater.
17
Kneis, D., R. Knoesche, and A. Bronstert. "Model-based analysis of nutrient retention and management for a lowland river." Hydrology and Earth System Sciences Discussions 2, no. 6 (November 30, 2005): 2549–79. http://dx.doi.org/10.5194/hessd-2-2549-2005.
Повний текст джерелаАнотація:
Abstract. In the context of the European Water Framework Directive options for improving the water quality of the lowland river Havel (Germany) were assessed. The lower section of this river is actually a polytrophic river-lake system suffering from high external nutrient loading and exhibiting significant in-river turnover. In order to gain a better understanding of present conditions and to allow integrated scenarios of nutrient management to be evaluated the catchment models SWIM and ArcEGMO-Urban were coupled with a simple, newly developed nutrient TRAnsport Model (TraM). Using the TraM model, the retention of nitrogen and phosphorus in a 55 km reach of the Lower Havel River was quantified and its temporal variation was analyzed. It was examined that about 30% of the external nitrogen input to the Lower Havel is retained within the surveyed river section. A comparison of simulation results generated with and without consideration of phosphorus retention/release revealed that summer TP concentrations are currently increased by 100–200% due to internal loading. Net phosphorus release rates of about 20 mg P m−2 d-1 in late summer were estimated for the Havel lakes. Scenario simulations with lowered external nutrient inputs revealed that persistent phosphorus limitation of primary production cannot be established within the next decade. It was shown that a further reduction in nitrogen concentrations requires emissions to be reduced in all inflows. Though the TraM model needs further extension it proved to be appropriate for conducting integrated catchment and river modeling.
18
Verschoor, Mark J., Chistopher R. Powe, Eric McQuay, Sherry L. Schiff, Jason J. Venkiteswaran, Jiahua Li, and Lewis A. Molot. "Internal iron loading and warm temperatures are preconditions for cyanobacterial dominance in embayments along Georgian Bay, Great Lakes." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 9 (September 2017): 1439–53. http://dx.doi.org/10.1139/cjfas-2016-0377.
Повний текст джерелаАнотація:
Previous work suggests that a high rate of internal ferrous iron (Fe2+) loading from anoxic sediments into overlying waters favours cyanobacteria dominance (>50% of the phytoplankton biomass) over eukaryotic algae. This Cyanobacteria–Ferrous conceptual model was assessed along the Georgian Bay coastline of Lake Huron, Ontario, in one meso-eutrophic and three oligotrophic embayments that experience natural hypolimnetic anoxia. Cyanobacteria dominated all embayments in the relatively warmer summer of 2012 but not in the much cooler summer of 2014, although hypolimnetic anoxia and internal Fe2+ loading were observed in both summers in all embayments. A cyanobacteria bloom large enough to turn the lake visibly green was observed only in warmer 2012 in the meso-eutrophic embayment. Results show that warm summer temperatures and internal Fe2+ loading are necessary preconditions for cyanobacteria dominance, while high nutrient levels are needed to form large blooms. There were no consistent patterns between dominance and total and dissolved phosphorus (P), total nitrogen, ammonium, and nitrate. Internal P loading was not a necessary precondition for dominance. While P removal programs will decrease phytoplankton biomass in eutrophic waters, oxidized surficial sediments must be maintained throughout an aquatic system to prevent cyanobacteria dominance.
19
Salifu, K. F., and V. R. Timmer. "Optimizing nitrogen loading of Picea mariana seedlings during nursery culture." Canadian Journal of Forest Research 33, no. 7 (July 1, 2003): 1287–94. http://dx.doi.org/10.1139/x03-057.
Повний текст джерелаАнотація:
Plant growth and nutrient uptake response to increased fertilization can be conceptually described by cur vi linear relationships depicting phases of nutrient deficiency, sufficiency, luxury consumption, and toxicity to rationalize fertilizer prescriptions and improve nutrient diagnosis. We validated this model to determine optimum nitrogen storage of young black spruce (Picea mariana (Mill.) BSP). Container seedlings were supplied with a mixed nitrogenphosphoruspotassium (NPK) fertilizer at rates ranging from 0 to 80 mg N/seedling and reared in a greenhouse for one growing season. Plant growth and nutritional parameters of the plants exhibited classic responses of N deficiency, luxury consumption, and toxicity that were corroborated by vector diagnosis and appeared consistent with the conceptual model. Seedling biomass production was maximized at sufficiency (30 mg N/seedling), whereas N content of tissues peaked at the optimum loading rate (64 mg N/seedling). Toxicity occurred at the 80 mg N/seedling dose rate that increased plant N concentration (5%) but reduced growth (17%) and N content (14%) relative to the optimum level. Plant N content was raised 150% by optimum loading, exemplifying the effectiveness of this practice for building internal N reserves prior to planting. The newly validated model will help refine fertilizer recommendations and nutrient diagnosis for other species or cultural systems.
20
Julian, Paul, Todd Z. Osborne, and Rex Ellis. "Evaluation of Biogeochemical Changes in Channelized and Restored Portions of a Subtropical Floodplain." Hydrobiology 2, no. 1 (December 20, 2022): 1–18. http://dx.doi.org/10.3390/hydrobiology2010001.
Повний текст джерелаАнотація:
Floodplains are critically important ecosystems that provide a whole suite of ecosystem services, including nutrient and carbon sequestration, flood mitigation, water storage, and critical wildlife habitat. However, human modification of rivers and floodplains through channelization, artificial levee construction, reductions in the active floodplain area, and water management can significantly reduce the ecosystem function of river–floodplain systems. In this study, we evaluated the changes in the nutrient loading of the Kissimmee River floodplain during the restoration of the river–floodplain system. In addition to time-series loading analysis, we also evaluated soil nutrient concentrations across the lower portion of the Kissimmee River floodplain. During the 44-year nutrient loading time-series, the floodplain remained a nutrient exporter with changes in nutrient loading generally corresponding to both water quality (i.e., point source reductions) and hydrologic restoration activities in the watershed and Kissimmee River floodplain. During the study period, inputs of total phosphorus and total nitrogen loads from upstream either significantly increased or remained the same. In addition to external sources of nutrients, internal sources of nutrients from floodplain soils can also contribute to the total nutrient export from the system. These internal sources could be organic via the decomposition of organic matter or geologic from the original excavation of the canal and/or restoration backfilling. Soil nutrient concentrations vary between vegetative communities and landscape position and could be a significant source of phosphorus to the downstream system, which is plagued by eutrophic conditions. Therefore, as floodplain function in the Kissimmee River continues to be restored and managed, additional effort may be needed to address nutrient inputs and internal legacy nutrients.
21
Sun, Chuanzhe, Shaoming Wang, Hongwei Wang, Xiaokang Hu, Fanyan Yang, Mengyao Tang, Min Zhang, and Jicheng Zhong. "Internal nitrogen and phosphorus loading in a seasonally stratified reservoir: Implications for eutrophication management of deep-water ecosystems." Journal of Environmental Management 319 (October 2022): 115681. http://dx.doi.org/10.1016/j.jenvman.2022.115681.
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22
Zhong, Ji-Cheng, Ju-Hua Yu, Xiao-Lan Zheng, Shuai-Long Wen, De-Hong Liu, and Cheng-Xin Fan. "Effects of Dredging Season on Sediment Properties and Nutrient Fluxes across the Sediment–Water Interface in Meiliang Bay of Lake Taihu, China." Water 10, no. 11 (November 8, 2018): 1606. http://dx.doi.org/10.3390/w10111606.
Повний текст джерелаАнотація:
The influence of dredging season on sediment properties and nutrient fluxes across the sediment–water interface remains unknown. This study collected sediment cores from two sites with different pollution levels in Meiliang Bay, Taihu Lake (China). The samples were used in simulation experiments designed to elucidated the effects of dredging on internal loading in different seasons. The results showed that dredging the upper 30 cm of sediment could effectively reduce the contents of organic matter, total nitrogen, and total phosphorus in the sediments. Total biological activity in the dredged sediment was weaker (p < 0.05) than in the undredged sediment in all seasons for both the Inner Bay and Outer Bay, but the effect of 30-cm dredging on sediment oxygen demand was negligible. Dredging had a significant controlling effect on phosphorus release in both the Inner Bay and Outer Bay, and soluble reactive phosphorus (SRP) fluxes from the dredged cores were generally lower (p < 0.05) than from the undredged cores. In contrast, NH4+-N fluxes from the dredged cores were significantly higher (p < 0.05) than from the undredged cores in all seasons for both sites, this indicates short-term risk of NH4+-N release after dredging, and this risk is greatest in seasons with higher temperatures, especially for the Inner Bay. Dredging had a limited effect on NO2−-N and NO3−-N fluxes at both sites. These results suggest that dredging could be a useful approach for decreasing internal loading in Taihu Lake, and that the seasons with low temperature (non-growing season) are suitable for performing dredging projects.
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McCarty, James A. "Sediment Phosphorus Release in a Shallow Eutrophic Reservoir Cove." Transactions of the ASABE 62, no. 5 (2019): 1269–81. http://dx.doi.org/10.13031/trans.13309.
Повний текст джерелаАнотація:
Abstract. Internal phosphorus (P) loading is a leading contributor to eutrophication in reservoirs and can cause harmful algal blooms as well as treatment issues for drinking water reservoirs. Coves are an area of reservoirs that have not received adequate attention, even though they experience higher nutrient and sediment deposition and primary production per unit area when compared to the pelagic zone of the reservoir. This study investigates a shallow eutrophic cove in a northwest Arkansas reservoir called Beaver Lake to better understand the cove’s potential to contribute to P loading and eutrophication within the reservoir. The study period was 3 to 16 July 2018. Water column profiles of depth, temperature, and dissolved oxygen were measured with a floating sensor platform that also contained a weather station. Cove bed sediment samples were collected at three locations in the cove and analyzed for chemical composition through Mehlich III extraction and P, nitrate + nitrite (N+N), and ammonia release rates with aerobic and anaerobic sediment core incubations. Bathymetry data were collected using a depth sonar system. Sensor platform profiles indicated dynamic bottom temperature and dissolved oxygen conditions with transient influxes of hypoxic waters that occurred several times for less than 24 h. The P release rates from bed sediment incubations were as high as 2.02 mg m-2 d-1 under aerobic conditions and 4.45 mg m-2 d-1 under anaerobic conditions. Upon initiation of nitrogen gas bubbling in the sediment cores, anaerobic conditions were delayed by the presence of N+N. Phosphorus release did not occur until denitrification decreased the N+N concentrations enough for reducing conditions to be present. For the study period, a P flux into the water of roughly 1 kg was determined using cove profiles, bathymetry, and P release rates. When compared to whole-lake P release averages for Beaver Lake, eutrophic coves are a disproportionate source of P per unit area within the reservoir. This may offer opportunities for more efficient use of internal loading remediation techniques, such as alum application. The results of this study also suggest that we should not continue to overlook shallow-area bed sediment P flux when considering the P mass balance of a reservoir. Keywords: Eutrophication, Sediment core incubation, Stratification.
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Zhang, Rufeng, Liancong Luo, Min Pan, Feng He, Chunliang Luo, Di Meng, Huiyun Li, et al. "Estimations of Water Volume and External Loading Based on DYRESM Hydrodynamic Model at Lake Dianchi." Water 14, no. 18 (September 12, 2022): 2832. http://dx.doi.org/10.3390/w14182832.
Повний текст джерелаАнотація:
There are many rivers flowing from complex paths into Lake Dianchi. At present, there is a lack of inflow and water quality monitoring data for some rivers, resulting in limited accuracy of statistical results regarding water volume and external loading estimations. In this study, we used DYRESM to estimate the water volume entering Waihai of Lake Dianchi from 2007 to 2019 without historical hydrological observation data. Then, we combined this information with the monthly monitoring data of water quality to calculate the annual external loading. Our results showed that: (1) DYRESM could effectively capture the extreme changes of water level at Waihai, showing its reliable applicability to Lake Dianchi. (2) The average annual inflow of rivers entering Waihai was about 6.69 × 108 m3. The fitting relationship between river inflow and precipitation was significant on annual scale (r = 0.74), with a higher inner-annual fitting coefficient between them (r = 0.98), thus suggesting that precipitation and its caused river inflows are the main water source for Waihai. (3) From 2007 to 2010, the river loadings remained at a high level. They decreased to 2445.44 t (total nitrogen, TN) and 106.53 t (total phosphorus, TP) due to a followed drought in 2011. (4) The river loading had annual variation characteristics. The contribution rates of TN and TP loading in the rainy season were 63% and 67% respectively. (5) Panlong River, Daqing River, Jinjia River, Xinbaoxiang River, Cailian River and Hai River were the main inflow rivers. Their loadings accounted for 81.3% (TN) and 80.3% (TP) of the total inputs. (6) River loadings have gradually reduced and the water quality of Waihai has continually improved. However, Pearson analysis results showed that the water quality parameters were not significantly correlated with their corresponding external loading at Waihai, indicating that there might be other factors influencing the water quality. (7) The contribution rates of internal release to the total loads of TN and TP at Waihai were estimated to be 7.6% and 8.9% respectively, suggesting that the reductions of both external and internal loading should be considered in order to significantly improve the water quality at Waihai of Lake Dianchi.
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Yiheng, DU, LIU Cheng, CHEN Kaining, GU Xiaozhi, HUANG Wei, and WEI Zhong. "Occurrence and internal loadings of nitrogen and phosphorus in the sediment of Lake Baiyangdian." Journal of Lake Sciences 30, no. 6 (2018): 1537–51. http://dx.doi.org/10.18307/2018.0606.
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Egemose, Sara, Inmaculada de Vicente, Kasper Reitzel, Mogens R. Flindt, Frede Ø. Andersen, Torben L. Lauridsen, Martin Søndergaard, Erik Jeppesen, and Henning S. Jensen. "Changed cycling of P, N, Si, and DOC in Danish Lake Nordborg after aluminum treatment." Canadian Journal of Fisheries and Aquatic Sciences 68, no. 5 (May 2011): 842–56. http://dx.doi.org/10.1139/f2011-016.
Повний текст джерелаАнотація:
Loading, retention, and in-lake cycling of phosphorus (P), nitrogen, silica, and dissolved organic carbon (DOC) were studied 1 year before and 3 years after P-inactivation by aluminum (Al) hydroxide in Danish Lake Nordborg in 2006. Simultaneously, external P loading was reduced by 40% via establishment of precipitation ponds in two inlets. After Al treatment, the internal P loading (sediment P release) during summer declined 90%–94%, owing to adsorption to aluminum hydroxide. Also, silicate regeneration from the sediment was reduced by 69%–76%, and sediment oxygen uptake as well as ammonium release declined markedly. Consequently, lake water total P, dissolved inorganic P, silicate, and DOC decreased by 73%, 97%, 87%, and 46%, respectively. The Secchi depth increased in the summer period during the first post-treatment year, but declined afterwards to pre-treatment levels, even though the mean lake-water total P concentration during summer was reduced from ∼240 µg·L–1 before treatment to 26–65 µg·L–1 in the first three post-treatment years. We conclude that a further reduction in external P loading is needed to obtain the full effect of the Al treatment in Lake Nordborg.
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Parsons, Chris T., Fereidoun Rezanezhad, David W. O'Connell, and Philippe Van Cappellen. "Sediment phosphorus speciation and mobility under dynamic redox conditions." Biogeosciences 14, no. 14 (July 27, 2017): 3585–602. http://dx.doi.org/10.5194/bg-14-3585-2017.
Повний текст джерелаАнотація:
Abstract. Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O2) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N2), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous- and solid-phase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low ( ∼ 2.5 µM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl2 and NaHCO3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h−1 kg−1 indicated the potential for rapid mineralization of organic P (Po), in particular during periods of aeration when the activity of phosphomonoesterases was 37 % higher than under N2 sparging. The results emphasize that the magnitude and timing of internal P loading during periods of anoxia are dependent on both P redistribution within sediments and bottom-water nitrate concentrations.
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Lee, H., Y. M. Min, C. H. Park, and Y. H. Park. "Automatic control and remote monitoring system for biological nutrient removal on small wastewater treatment plants in Korea." Water Science and Technology 50, no. 6 (September 1, 2004): 199–206. http://dx.doi.org/10.2166/wst.2004.0377.
Повний текст джерелаАнотація:
Many small-size wastewater treatment plants in KoreaÕs rural communities are designed to remove organic and suspended matter only, and they generally show a large fluctuation in the influent loading compared to municipal wastewater treatment plants (MWWTPs). They also have no professional engineers stationed for efficient operation against mechanical breakdown. For those reasons, the wastewater treatment plants have low efficiency in treatment of nitrogen and phosphorus as well as organic matter. In order to solve those problems, this study developed an automatic control system and RMS (remote monitoring system), which can keep efficiency stable despite any change in the small plants' loading rates and are capable of removing nutrient materials such as nitrogen or phosphorus. According to the results of the Experimental SBR system of the automatic control program, complete nitrification was made under oxic conditions and denitrification occurred as NO3-N concentration decreased by 0.5 mg/l in anoxic conditions and excellent nitrogen removal efficiency was seen generally. The Experimental SBR system created “phosphate release and uptake” effectively and displayed phosphate-removing efficiency up to more than 80% as the concentration of effluent was kept low by 0.4 mg/l. RMS developed in this study transmits a plants data and operation states to clients in remote locations in real-time interval through the Internet. Therefore, although you are in a remote location, it allows you to see if a plant is properly operated or there is any breakdown.
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Luo, Liancong, Hucai Zhang, Chunliang Luo, Chrisopher McBridge, Kohji Muraoka, Hong Zhou, Changding Hou, Fenglong Liu, and Huiyun Li. "Tributary Loadings and Their Impacts on Water Quality of Lake Xingyun, a Plateau Lake in Southwest China." Water 14, no. 8 (April 15, 2022): 1281. http://dx.doi.org/10.3390/w14081281.
Повний текст джерелаАнотація:
Lake Xingyun is a hypertrophic shallow lake on the Yunnan Plateau of China. Its water quality (WQ) has degraded severely during the past three decades with catchment development. To better understand the external nutrient loading impacts on WQ, we measured nutrient concentrations in the main tributaries during January 2010–April 2018 and modelled the monthly volume of all the tributaries for the same period. The results show annual inputs of total nitrogen (TN) had higher variability than total phosphorus (TP). The multi-year average load was 183.8 t/year for TN and 23.3 t/year for TP during 2010–2017. The average TN and TP loads for 2010–2017 were 36.6% higher and 63.8% lower, respectively, compared with observations in 1999. The seasonal patterns of TN and TP external loading showed some similarity, with the highest loading during the wet season and the lowest during the dry season. Loads in spring, summer, autumn, winter, and the wet season (May–October) accounted for 14.2%, 48.8%, 30.3%, 6.7%, and 84.9% of the annual TN load and 14.1%, 49.8%, 28.1%, 8%, and 84.0% of the annual TP load during 2010–2017. In-lake TN and TP concentrations followed a pattern similar to the external loading. The poor correlation between in-lake nutrient concentrations and tributary nutrient inputs at monthly and annual time scales suggests both external loading and internal loading were contributing to the lake eutrophication. Although effective lake restoration will require reducing nutrient losses from catchment agriculture, there may be a need to address a reduction of internal loads through sediment dredging or capping, geochemical engineering, or other effective measures. In addition, the method of producing monthly tributary inflows based on rainfall data in this paper might be useful for estimating runoff at other lakes.
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Yin, Hongbin, Jincan Zhu, and Wanying Tang. "Management of nitrogen and phosphorus internal loading from polluted river sediment using Phoslock® and modified zeolite with intensive tubificid oligochaetes bioturbation." Chemical Engineering Journal 353 (December 2018): 46–55. http://dx.doi.org/10.1016/j.cej.2018.07.112.
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Zhan, Qing, Cleo N. Stratmann, Harm G. van der Geest, Annelies J. Veraart, Kristof Brenzinger, Miquel Lürling, and Lisette N. de Senerpont Domis. "Effectiveness of phosphorus control under extreme heatwaves: implications for sediment nutrient releases and greenhouse gas emissions." Biogeochemistry 156, no. 3 (October 2, 2021): 421–36. http://dx.doi.org/10.1007/s10533-021-00854-z.
Повний текст джерелаАнотація:
AbstractEutrophication has been identified as the primary cause of water quality deterioration in inland waters worldwide, often associated with algal blooms or fish kills. Eutrophication can be controlled through watershed management and in-lake measures. An extreme heatwave event, through its impact on mineralization rates and internal nutrient loading (phosphorus—P, and nitrogen—N), could counteract eutrophication control measures. We investigated how the effectiveness of a nutrient abatement technique is impacted by an extreme heatwave, and to what extent biogeochemical processes are modulated by exposure to heatwaves. To this end, we carried out a sediment-incubation experiment, testing the effectiveness of lanthanum-modified bentonite (LMB) in reducing nutrients and greenhouse gas emissions from eutrophic sediments, with and without exposure to an extreme heatwave. Our results indicate that the effectiveness of LMB may be compromised upon exposure to an extreme heatwave event. This was evidenced by an increase in concentration of 0.08 ± 0.03 mg P/L with an overlying water volume of 863 ± 21 mL, equalling an 11% increase, with effects lasting to the end of the experiment. LMB application generally showed no effect on nitrogen species, while the heatwave stimulated nitrification, resulting in ammonium loss and accumulation of dissolved oxidized nitrogen species as well as increased dissolved nitrous oxide concentrations. In addition, carbon dioxide (CO2)-equivalent was more than doubled during the heatwave relative to the reference temperature, and LMB application had no effect on mitigating them. Our sediment incubation experiment indicates that the rates of biogeochemical processes can be significantly accelerated upon heatwave exposure, resulting in a change in fluxes of nutrient and greenhouse gas between sediment and water. The current efforts in eutrophication control will face more challenges under future climate scenarios with more frequent and intense extreme events as predicted by the IPCC.
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Yin, Hongbin, Jingfu Wang, Runyu Zhang, and Wanying Tang. "Performance of physical and chemical methods in the co-reduction of internal phosphorus and nitrogen loading from the sediment of a black odorous river." Science of The Total Environment 663 (May 2019): 68–77. http://dx.doi.org/10.1016/j.scitotenv.2019.01.326.
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Lusk, Mary G., and Kylie Chapman. "Chemical Fractionation of Sediment Phosphorus in Residential Urban Stormwater Ponds in Florida, USA." Urban Science 5, no. 4 (October 20, 2021): 81. http://dx.doi.org/10.3390/urbansci5040081.
Повний текст джерелаАнотація:
Stormwater ponds collect and transform pollutants (including nutrients, such as nitrogen and phosphorus) in urban runoff and are often hydrologically connected to downstream waters, making it important to maximize their pollutant retention efficiency. A key mechanism for phosphorus (P) removal in stormwater ponds is sedimentation. However, sediment P in stormwater ponds may be present in several chemical forms with varying bioavailability and potential to move from sediments into the overlying water column. The purpose of this study was to characterize the chemical fractions of sediment P in residential urban stormwater ponds, with the goal of better understanding expected movement of P from sediments to water. We used a chemical fractionation scheme to separate sediment P into the following pools: loosely adsorbed and readily available P, Fe- and Al-bound P, Ca- and Mg-bound P, NaOH-exchangeable organic P, and refractory P. From six stormwater ponds in the Tampa Bay, Florida urban area, we found the pool of readily available P was less than 3% of total sediment P, and the refractory P pool was 28–40% of Total P. However, both Fe/Al-bound and Ca/Mg-bound P each accounted for about 18% of total sediment P. These latter pools may become available under anoxic or low pH (<6) conditions, respectively, demonstrating that a change in environmental conditions could cause internal P loading from sediments to pond water.
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Niemistö, Juha, and Lars Chresten Lund-Hansen. "Instantaneous Effects of Sediment Resuspension on Inorganic and Organic Benthic Nutrient Fluxes at a Shallow Water Coastal Site in the Gulf of Finland, Baltic Sea." Estuaries and Coasts 42, no. 8 (October 31, 2019): 2054–71. http://dx.doi.org/10.1007/s12237-019-00648-5.
Повний текст джерелаАнотація:
Abstract Climate change is leading to harsher resuspension events in shallow coastal environments influencing benthic nutrient fluxes. However, we lack information on the quantitative connection between these fluxes and the physical forces. Two identical experiments that were carried out both in May and August provided novel knowledge on the instantaneous effects of resuspension with known intensity on the benthic dissolved inorganic (phosphate: DIP, ammonium: NH4+, nitrite+nitrate: NOx, silicate, DSi) and organic nutrient (phosphorus: DOP, nitrogen: DON, carbon: DOC) fluxes in the shallow soft bottoms of the archipelago of Gulf of Finland (GoF), Baltic Sea. Resuspension treatments, as 2 times the critical shear stress, induced effluxes of one to two orders of magnitude higher than the diffusive fluxes from the studied oxic bottoms. The presence of oxygen resulted in newly formed iron oxyhydroxides and the subsequent precipitation/adsorption of the redox-dependent nutrients (DIP, DSi, organic nutrients) affecting their fluxes. Resuspension-induced NH4+ and NOx fluxes were associated with the organic content of sediments showing the highest values at the organic rich sites. NH4+ showed the strongest responses to resuspension treatments in August, but NOx at the time of high oxygen concentrations in near-bottom water in May. Foreseen increases in the frequency and intensity of resuspension events due to climate change will most likely enhance the internal nutrient loading of the studied coastal areas. The fluxes presented here, connected to known current velocities, can be utilized in modeling work and to assess and predict the internal nutrient loading following climate change.
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Grochowska, Jolanta, and Renata Tandyrak. "The Influence of the Modernization of the City Sewage System on the External Load and Trophic State of the Kartuzy Lake Complex." Applied Sciences 11, no. 3 (January 21, 2021): 974. http://dx.doi.org/10.3390/app11030974.
Повний текст джерелаАнотація:
A study was carried out in the Kartuzy lake complex, which has been a receiver of raw domestic sewage since the 1950s. In 2018, the city’s sewage system of Kartuzy was modernized. An analysis of the water quality prior to the modernization of the sewage system revealed that the total phosphorus (TP) load that was introduced to the individual lakes from external sources substantially exceeded the dangerous load concentration (defined by Vollenweider) that causes accelerated eutrophication. The annual TP load introduced to the analyzed lakes in 2017 exceeded the critical load by 200% (Mielenko) to 1000% (Klasztorne Duże). Protective measures reduced the external loading of nutrients. In the case of Mielenko Lake, a 37% decrease in the external TP load was noted, and also a 32% decrease in the external TP load in Karczemne Lake, a 66% decrease in Klasztorne Małe Lake and a 54% decrease in Klasztorne Duże Lake was noted. The protective measures resulted in a slight decrease in the concentrations of phosphorus and nitrogen in the water. However, these changes did not improve the environmental conditions in the lakes. In a situation where the internal fertilization process in the lakes has started, the improvement of water quality will only be possible through restoration efforts with methods adjusted to the individual characteristics of each lake.
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Wang, J. W., T. Z. Zhang, and J. N. Chen. "Operating costs for reducing total emission loads of key pollutants in municipal wastewater treatment plants in China." Water Science and Technology 62, no. 5 (September 1, 2010): 995–1002. http://dx.doi.org/10.2166/wst.2010.321.
Повний текст джерелаАнотація:
Total emission load reduction of COD, NH4-N, TN, and TP is the key measure in controlling water pollution and eutrophication. Municipal wastewater treatment plants (MWWTPs) are major contributors in lowering energy consumption and reducing pollutant discharge. The flow-based operating costs have not been directly established to relate to costs of pollutant reduction based on an investigation of 11 MWWTPs in China. However, energy consumption to eliminate one kilogram of COD or NH4-N was observed to decrease when the total reduced pollutants is increased. Additional energy consumption required to remove nitrogen and phosphorus is allotted for mixers and internal return pumps. Major factors for operating costs include influent and effluent concentration, design capacity, and flow loading rate. Therefore, an operating cost model for the total emission load reduction of COD, NH4-N, TN, and TP was developed based on energy consumption and the above mentioned major factors. Using this model to calculate the operating costs for MWWTPs would facilitate more reduction of key pollutants than the flow-based method.
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McQueen, D. J., and D. R. S. Lean. "Hypolimnetic Aeration: An Overview." Water Quality Research Journal 21, no. 2 (May 1, 1986): 205–17. http://dx.doi.org/10.2166/wqrj.1986.015.
Повний текст джерелаАнотація:
Abstract Hypolimnetic aerators are now being widely used throughout Europe and are beginning to appear in small and medium sized eutrophic lakes in temperate North America. This activity has produced approximately 42 published reports dealing with experiments conducted at 16 lakes. Taken together, the evidence from these experiments suggests that well designed aerators do not cause significant destratification or warming of hypolimnetic water, but do result in measurable Increases in hypolimnetic oxygen concentration and decreases in dissolved hydrogen sulfide, methane and ammonia. Early experiments suggested that phosphorus sedimentation was unpredictable, but recent work has demonstrated that when the ratio of total iron to soluble reactive phosphorus exceeds 10:1 and pH is < 7.5, phosphorus sedimentation is assured and internal loading greatly reduced. Early experiments also showed that ammonia volatilization was unpredictable, but at pH > 8.0, ammonia volatilization will occur. Because both phosphorus sedimentation and nitrogen reduction are pH dependent, both cannot be optimally removed during the same period of time and so the experimenter is advised to select for the maximum removal of one or the other through pH manipulation. Hypolimnetic aeration induces oxygen consumption and this must be considered when choosing an appropriate compressor size. Most studies show little impact on phytoplankton blomass, but one recent experiment showed that aeration during spring turnover resulted in reduced concentrations of chlorophyll a and TP. Zooplankton populations are, for the most part, unaffected and a number of American studies have shown that hypolimnetically aerated lakes can support cold water fish populations. The aggregate practical and experimental experience suggests that well designed hypolimnetic aeration systems yield measurable improvements in water quality and will almost certainly prove to be one of the major methods used for future in situ lake restoration.
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Griffiths, Erin, and Jason C. Stevens. "Managing nutrient regimes improves seedling root-growth potential of framework banksia-woodland species." Australian Journal of Botany 61, no. 8 (2013): 600. http://dx.doi.org/10.1071/bt13181.
Повний текст джерелаАнотація:
Limited success of restoring framework banksia-woodland species has been attributed to the failure of seedlings to establish deep root systems before the onset of the summer drought. The present glasshouse study investigated how optimising nutrient application during nursery production may increase new-root production after outplanting. Two experimental streams were established to (1) optimise nutrient application rates during nursery production and (2) utilise nutrient-loading techniques to improve root production of Banksia menziesii R.Br., Banksia attenuata R.Br. and Eucalyptus todtiana F.Muell after outplanting. Optimal nutrient-application rates were determined by measuring plant growth and internal nutrient responses to eight application levels of slow-release fertiliser (0–18 kg m–3, nitrogen (N) : phosphorus (P) : potassium (K) = 17 : 1.6 : 8.7). Nutrient-loading treatments utilised seedlings that had been grown under common industry fertiliser conditions (3 kg m–3 native Osmocote, N : P : K = 17 : 1.6 : 8.7) supplied with ‘low’ or ‘high’ loading doses of liquid Thrive continuously over 6 weeks, immediately before outplanting. Seedlings from both experiments were then outplanted to 1-m-deep poly-pipe tubes containing habitat soil. After 12 weeks, plants were harvested and new-root production and shoot growth were measured. Optimal concentrations of slow-release fertiliser for maximum outplanting success as indicated by increased root investment (root : shoot ratio and new-root production) were 8–12 kg m–3 for all species. Nutrient loading increased N and P concentrations of plants by up to 80% and 127%, respectively, by luxury nutrient consumption, and after planting, nutrient-loaded seedlings produced 1.5-fold the biomass of conventionally fertilised seedlings, this being the result of greater root productivity. In conclusion, optimising nursery nutrient regimes for framework species may increase root-growth potential, assisting in improving plant establishment in restoration programs.
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Chen, Xi, Yanhua Wang, Tian Sun, Yu Huang, Yan Chen, Mingli Zhang, and Chun Ye. "Effects of Sediment Dredging on Nutrient Release and Eutrophication in the Gate-Controlled Estuary of Northern Taihu Lake." Journal of Chemistry 2021 (January 19, 2021): 1–13. http://dx.doi.org/10.1155/2021/7451832.
Повний текст джерелаАнотація:
Estuarine zones are regarded as the ecotones connecting the rivers and lakes. Sediment dredging is a conventional treatment technology that is widely used to remove the internal loading in estuarine zones worldwide. However, what is the characteristic of nutrient release in the gate-controlled estuary and how long this practice is effective are still unclear. Hence, sediment and water samples were collected from dredged and undredged regions around the gate-controlled estuary of northern Taihu Lake for laboratory experiments, in which they were subjected to different temperatures, depths, and disturbance levels. The total nitrogen (TN) and total phosphorus (TP) concentrations of the dredged region were lower than those from the undredged region under stable hydrodynamic conditions. A high dynamic release rate (R) of nutrients in the dredged sediments (RTN = 164.75 mg/m2·d and RTP = 5.83 mg/m2·d) existed under dynamic release conditions (stirring speeds: 90 and 120 r/min). The effect of disturbance and temperature on release rate and nutrient form was completely different for the static and dynamic release cases. The nutrient loads from dynamic release were 4–17 times greater than those from static release. For unstable hydrodynamic conditions, the release rate from the bottom sediment exceeded that from the surface sediment in the undredged region. These results indicated that, under stable hydrodynamic conditions, dredging improves long-term water quality. However, dredging alone in unstable hydrodynamic conditions may not remove the potential risk of internal release in the long term. Specific ecological and engineering measures should be combined with dredging practice to restore estuary habitats and minimize the release of internal pollutants.
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Lizotte, Richard E., Lindsey M. W. Yasarer, Ronald L. Bingner, Martin A. Locke, and Scott S. Knight. "Long-Term Oxbow Lake Trophic State under Agricultural Best Management Practices." Water 13, no. 8 (April 20, 2021): 1123. http://dx.doi.org/10.3390/w13081123.
Повний текст джерелаАнотація:
A key principle of agricultural best management practices (BMPs) is to improve water quality by reducing agricultural-sourced nutrients and associated eutrophication. Long-term (1998–2016) lake summer trophic state index (TSI) trends of an agricultural watershed with agricultural best management practices (BMPs) were assessed. Structural BMPs included vegetative buffers, conservation tillage, conservation reserve, a constructed wetland, and a sediment retention pond. TSI included Secchi visibility (SD), chlorophyll a (Chl), total phosphorus (TP), and total nitrogen (TN). Summer TSI 1977 was >80 in 1998–1999 (hypertrophic) and decreased over the first 10 years to TSI 1977 ≈ 75 (eutrophic). TSI 1977 decrease and changing TSI deviations coincided with vegetative buffers, conservation tillage, and conservation reserve. The TSI(SD) decrease (>90 to <70) coincided with vegetative buffers and TSI(TP) decrease (>90 to <75) coincided primarily with conservation tillage and the sediment retention pond. TSI(Chl) increase (<60 to >70) coincided with conservation tillage and vegetative buffer. Results indicate watershed-wide BMPs can modestly decrease summer trophic state through increased water transparency and decreased TP, but these changes are off-set by increases in chlorophyll a to reach a new stable state within a decade. Future research should assess algal nutrient thresholds, internal nutrient loading, and climate change effects.
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Hampel, Justyna J., Mark J. McCarthy, Wayne S. Gardner, Lu Zhang, Hai Xu, Guangwei Zhu, and Silvia E. Newell. "Nitrification and ammonium dynamics in Taihu Lake, China: seasonal competition for ammonium between nitrifiers and cyanobacteria." Biogeosciences 15, no. 3 (February 6, 2018): 733–48. http://dx.doi.org/10.5194/bg-15-733-2018.
Повний текст джерелаАнотація:
Abstract. Taihu Lake is hypereutrophic and experiences seasonal, cyanobacterial harmful algal blooms. These Microcystis blooms produce microcystin, a potent liver toxin, and are linked to anthropogenic nitrogen (N) and phosphorus (P) loads to lakes. Microcystis spp. cannot fix atmospheric N and must compete with ammonia-oxidizing and other organisms for ammonium (NH4+). We measured NH4+ regeneration and potential uptake rates and total nitrification using stable-isotope techniques. Nitrification studies included abundance of the functional gene for NH4+ oxidation, amoA, for ammonia-oxidizing archaea (AOA) and bacteria (AOB). Potential NH4+ uptake rates ranged from 0.02 to 6.80 µmol L−1 h−1 in the light and from 0.05 to 3.33 µmol L−1 h−1 in the dark, and NH4+ regeneration rates ranged from 0.03 to 2.37 µmol L−1 h−1. Nitrification rates exceeded previously reported rates in most freshwater systems. Total nitrification often exceeded 200 nmol L−1 d−1 and was > 1000 nmol L−1 d−1 at one station near a river discharge. AOA amoA gene copies were more abundant than AOB gene copies (p < 0.005) at all times; however, only abundance of AOB amoA (not AOA) was correlated with nitrification rates for all stations and all seasons (p < 0.005). Nitrification rates in Taihu Lake varied seasonally; at most stations, rates were highest in March, lower in June, and lowest in July, corresponding with cyanobacterial bloom progression, suggesting that nitrifiers were poor competitors for NH4+ during the bloom. Regeneration results suggested that cyanobacteria relied extensively on regenerated NH4+ to sustain the bloom. Internal NH4+ regeneration exceeded external N loading to the lake by a factor of 2 but was ultimately fueled by external N loads. Our results thus support the growing literature calling for watershed N loading reductions in concert with existing management of P loads.
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Zhang, Min, Shuailong Wen, Tao Wu, Shaoming Wang, Xin Li, Wanqing Gong, Hongwei Wang, Cheng Liu, and Jicheng Zhong. "Patterns of internal nitrogen and phosphorus loadings in a cascade reservoir with a large water level gradient: Effects of reservoir operation and water depth." Journal of Environmental Management 320 (October 2022): 115884. http://dx.doi.org/10.1016/j.jenvman.2022.115884.
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Wu, Jiasen, Haiping Lin, Lianhua Guo, Jiaqi Dong, Luyao Zhang, and Weijun Fu. "Biomass and Nutrients Variation of Chinese Fir Rooted Cuttings under Conventional and Exponential Fertilization Regimes of Nitrogen." Forests 10, no. 8 (July 25, 2019): 615. http://dx.doi.org/10.3390/f10080615.
Повний текст джерелаАнотація:
Exponential fertilization has been regarded as an important technique for improving seedling quality at the initial plant-growth stage. In our study, containerized one-year-old Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) rooted cuttings were reared at four nitrogen (N) fertilizer levels (0, 0.5, 1.0, 2.0 g cutting−1 season−1) under two topdressing methods (conventional and exponential) for a 210-day greenhouse rotation to evaluate growth and nutrient loading capacity of seedlings. N fertilizer was applied 20 times at an interval of 10 days during the study period. The results indicated that the schedule and rate of fertilization significantly affected the height, ground diameter, and biomass of Chinese fir rooted cuttings. The nitrogen concentration of different plant organs followed the order of leaves > root > stem. Compared to the CK, the N concentrations in root, stem, and leaves increased by 39.6%, 16.6%, and 41.1% in the conventional fertilizer treatment, and by 22.6% to 81.4%, 27.3% to 152.6%, and 73.6% to 135.5% in exponential fertilization treatments, respectively. The N concentrations of root, stem, and leaves of Chinese fir rooted cuttings under EF2 (1.0 N g cutting−1) were significantly higher than that of conventional fertilization (p < 0.05). However, there was no significant difference of phosphorus and potassium concentrations among different plant organs. Steady-state nutrition and superior growth performance were achieved by rooted cuttings fertilized exponentially at the rate of 1.0 g cutting−1 yielding (EF2).
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Ji, Gaohua, and Karl Havens. "Periods of Extreme Shallow Depth Hinder but Do Not Stop Long-Term Improvements of Water Quality in Lake Apopka, Florida (USA)." Water 11, no. 3 (March 15, 2019): 538. http://dx.doi.org/10.3390/w11030538.
Повний текст джерелаАнотація:
We recently documented that during times of extreme shallow depth, there are severe effects on the water quality of one of the largest shallow lakes in the southeastern USA—Lake Apopka. During those times, total phosphorus (TP), total nitrogen (TN), chlorophyll-a (Chl-a) and toxic cyanobacteria blooms increase, and Secchi transparency (SD) declines. The lake recovers when water levels rise in subsequent years. In this paper, we determined whether extreme shallow depth events, particularly when they re-occur frequently, can stop the long-term recovery of a shallow eutrophic lake undergoing nutrient reduction programs. Apopka is an ideal location for this case study because the State of Florida has spent over 200 million USD in order to reduce the inputs of P to the lake, to build large filter marshes to treat the water, and to remove large quantities of benthivorous fish that contribute to internal P loading. We obtained data from 1985 to 2018, a period that had relatively stable water levels for nearly 15 years, and then three successive periods of extreme shallow depth, and we examined the long-term trends in TP, TN, Chl-a, and SD. There were significant decreasing trends in all of these water quality variables, and even though water quality deteriorated during periods of extreme shallow depth, and reduced the slope of the long-term trends, it did not stop the recovery. However, in the future, if climate change leads to more frequent shallow depth events, which in lakes such as Apopka, result in the concentration of water and nutrients, it is unclear whether the resilience we document here will continue, vs. the lake not responding to further nutrient input reductions.
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Szatmári, Gábor, Mihály Kocsis, András Makó, László Pásztor, and Zsófia Bakacsi. "Joint Spatial Modeling of Nutrients and Their Ratio in the Sediments of Lake Balaton (Hungary): A Multivariate Geostatistical Approach." Water 14, no. 3 (January 26, 2022): 361. http://dx.doi.org/10.3390/w14030361.
Повний текст джерелаАнотація:
Eutrophication, water quality, and environmental status of lakes is a global issue that depends not only on external loadings from industrial, agricultural, and municipal sources but often also on internal loadings from lake sediments. In the latter case, in addition to the quality and quantity of nutrients stored in sediments, their relative content may be an important factor. In the example of Lake Balaton, we jointly modeled the spatial distribution of the nutrients nitrogen (N) and phosphorus (P) and their ratio (i.e., N:P) in the sediments of the lake and then provided spatial predictions at different scales (i.e., point, basin, and entire lake) with the associated uncertainty. Our aim was to illustrate the merits of applying multivariate geostatistics when spatial modeling of more than one variable is targeted at various scales in water ecosystems. Variography confirmed that there is a spatial interdependence between the nutrients. The results revealed that multivariate geostatistics allows this interdependence to be taken into account and exploited to provide coherent and accurate spatial models. Additionally, stochastic realizations, reproducing the joint spatial variability, can be generated that allow providing spatially aggregated predictions with the associated uncertainty at various scales. Our study highlighted that it is worthy of applying multivariate geostatistics in case spatial modeling of two or more variables, which jointly vary in space, is targeted in water ecosystems.
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Giraldo, E., and A. Garzón. "The potential for water hyacinth to improve the quality of Bogota River water in the Muña Reservoir: comparison with the performance of waste stabilization ponds." Water Science and Technology 45, no. 1 (January 1, 2002): 103–10. http://dx.doi.org/10.2166/wst.2002.0014.
Повний текст джерелаАнотація:
The potential application of Water Hyacinth (Eichhornia crassipes) in organic matter degradation, sedimentation, nutrient and heavy metal absorption and sulfur reduction in the Muña Reservoir has been tested in experimental lagoons. The lagoons were operated at hydraulic retention times (HRT) of 6, 9 and 15 days. One lagoon was covered with Water Hyacinth, which is naturally growing in the Muña Reservoir, while another lagoon was operated as a conventional oxidation pond. The Water Hyacinth lagoon had better removal efficiencies for almost all parameters measured: BOD5, total suspended solids, COD, nitrogen, phosphorus and heavy metals. The oxidation lagoon was facultative for HRT of 9 and 15 days, and anoxic when operated at 6 days HRT. At HRT of 15 days the water quality in the effluent of the covered lagoon corresponded to 12 mg/l of BOD, 6 mg/l of suspended solids and 0.8 mg/l of hydrogen sulfide. Hydrogen sulfide levels in the Muña reservoir can be substantially reduced at HRT higher than 15 days in both lagoons. The uncovered lagoon had better hydrogen sulfide removal during the day but presents high levels at night. If the hydraulic retention time in the Muña reservoir is increased, the water quality of the Bogota river can be substantially improved for all the HRTs tested in the pilot units. HRT seems to give a better prediction of overall effluent water quality than surface loading. More research is needed in order to define the optimum water hyacinth density in the Muña reservoir to determine its influence on the water quality of the effluent. The influence is expected to be negative due to an internal increase of BOD, solids, nutrients and metals loads due to plant decay.
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Kunimatsu, T., T. Otomori, K. Osaka, E. Hamabata, and Y. Komai. "Evaluation of nutrient loads from a mountain forest including storm runoff loads." Water Science and Technology 53, no. 2 (January 1, 2006): 79–91. http://dx.doi.org/10.2166/wst.2006.041.
Повний текст джерелаАнотація:
Water quality and flow rates at a weir installed on the end of Aburahi-S Experimental Watershed (3.34 ha) were measured once a week from 2001 to 2003 and in appropriate intervals from 30 min to 6 h during five storm runoff events caused by each rainfall from 8 mm to 417 mm. The average annual loads of total nitrogen (TN) and total phosphorus (TP) were calculated to be 19.0 and 0.339 kg ha−1 y−1 from the periodical data by using the integration interval-loads method (ILM), which did not properly account for storm runoff loads. Three types of L(Q) equations (L=aQb) were derived from correlations between loading rates L and flow rates Q obtained from the periodic observation and from storm runoff observation. L(Q) equation method (LQM), which was derived from the storm runoff observation and allowed for the hysteresis of discharge of materials, gave 9.68 and 0.159 kg ha−1 y−1, respectively, by substitution of the sequential hourly data of flow rates. L(R) equation (L=c(R−r)d) was derived from the correlations between the loads and the effective rainfall depth (R−r) measured during the storm runoff events, and L(R) equation method (LRM) calculated 9.83±1.68 and 0.175±0.0761 kg ha−1 y−1, respectively, by using the rainfall data for the past 16 years. The atmospheric input-fluxes of TN and TP were 16.5 and 0.791 kg ha−1 y−1.
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Ritzenhofen, Lukas, Anna-Lucia Buer, Greta Gyraite, Sven Dahlke, Annemarie Klemmstein, and Gerald Schernewski. "Blue mussel (Mytilus spp.) cultivation in mesohaline eutrophied inner coastal waters: mitigation potential, threats and cost effectiveness." PeerJ 9 (May 20, 2021): e11247. http://dx.doi.org/10.7717/peerj.11247.
Повний текст джерелаАнотація:
The EU-water framework directive (WFD) focuses on nutrient reductions to return coastal waters to the good ecological status. As of today, many coastal waters have reached a steady state of insufficient water quality due to continuous external nutrient inputs and internal loadings. This study focuses first on the current environmental status of mesohaline inner coastal waters to illustrate their needs of internal measures to reach demanded nutrient reductions and secondly, if mussel cultivation can be a suitable strategy to improve water quality. Therefore, nitrogen, phosphorus, chlorophyll a, and Secchi depth of nine mesohaline inner coastal waters in north east Germany were analyzed from 1990 to 2018. Two pilot mussel farms were used to evaluate their effectiveness as a mitigation measure and to estimate potential environmental risks, including the interactions with pathogenic vibrio bacteria. Further, estimated production and mitigation potential were used to assess economic profitability based on the sale of small sized mussels for animal feed and a compensation for nutrient mitigation. The compensation costs were derived from nutrient removal costs of a waste water treatment plant (WWTP). Results show that currently all nine water bodies do not reach the nutrient thresholds demanded by the WFD. However, coastal waters differ in nutrient pollution, indicating that some can reach the desired threshold values if internal measures are applied. The mitigation potential of mussel cultivation depends on the amount of biomass that is cultivated and harvested. However, since mussel growth is closely coupled to the salinity level, mussel cultivation in low saline environments leads to lower biomass production and inevitably to larger cultivation areas. If 50% of the case study area Greifswald Bay was covered with mussel farms the resulting nitrogen reduction would increase Secchi depth by 7.8 cm. However, high chlorophyll a values can hamper clearance rates (<20 mg m−3 = 0.43 l h−1 dry weight g−1) and therefore the mitigation potential. Also, the risk of mussel stock loss due to high summer water temperatures might affect the mitigation potential. The pilot farms had no significant effect on the total organic content of sediments beneath. However, increased values of Vibrio spp. in bio deposits within the pilot farm (1.43 106 ± 1.10 106CFU 100 ml−1 (reference site: 1.04 106 ± 1.45 106 CFU 100 ml−1) were measured with sediment traps. Hence, mussel farms might act as a sink for Vibrio spp. in systems with already high vibrio concentrations. However, more research is required to investigate the risks of Vibrio occurrence coupled to mussel farming. The economic model showed that mussel cultivation in environments below 12 PSU cannot be economic at current market prices for small size mussels and compensations based on nutrient removal cost of WWTPs.
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Lijklema, Lambertus. "Phosphorus accumulation in sediments and internal loading." Hydrobiological Bulletin 20, no. 1-2 (November 1986): 213–24. http://dx.doi.org/10.1007/bf02291164.
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Welch, Eugene B., and T. Scott Kelly. "Internal Phosphorus Loading and Macrophytes: an Alternative Hypothesis." Lake and Reservoir Management 6, no. 1 (July 1990): 43–48. http://dx.doi.org/10.1080/07438149009354694.
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