Academic literature on the topic 'Dissolved reactive phosphorus'

The simplified acid peroxydisulphate digestion of soil water extract was evaluated for determination of total dissolved phosphorus by molybdenum-blue colorimetry in comparison with direct P-detection in water extract by the ICP-AES technique. The research was conducted on 79 agricultural soils with different agrochemical characteristics. The results of the colorimetric P detection in water extract without digestion and ICP phosphorus detection were different. The median of values determined by ICP-AES was 1.7 times higher than that of colorimetry, but the correlations between the two measurements were quite close (r = 0.993). Differences between the colorimetric phosphorus and ICP-AES phosphorus were irregular, increasing as the phosphorus level in soils decreased. The simplified procedure of acid peroxydisulphate digestion is useful for routine determination of total water-extracted phosphorus in soils when the soil testing laboratory is not equipped with the ICP-AES technique. The two-tailed paired t-test did not prove any difference in the values between the direct ICP-AES P-detection in water extract of soils and colorimetric P-detection in the acid peroxydisulphate digest.  

The aim of this study was to examine the stability and bioavailability of different phosphorus fractions of pulp and paper mill effluents in order to assess the environmental benefits of reducing their phosphorus discharges. Two types of effluent were studied: activated sludge treated bleached kraft mill effluent and activated sludge treated paper mill effluent. Phosphorus was characterized on the basis of its solubility and chemical reactivity. The stability of particulate phosphorus was studied in long-term (6-8 weeks) degradation tests. The bioavailability of different phosphorus fractions was measured by algal growth potential tests. In bleached kraft mill effluent (BKME) the proportion of dissolved phosphorus in relation to the total phosphorus was on an average 80%, and of this, approximately 80-90% was reactive phosphorus. During a 6-8 week incubation period some 60-70% of the particulate phosphorus in BKME was dissolved as soluble phosphorus, and most of it was of the reactive type. Approximately 90% of the dissolved phosphorus and 45% of the particulate phosphorus in BKME was biologically available phosphorus (BAP). Altogether some 80% of the total phosphorus in activated sludge treated BKME was available for algae either immediately or after inherent degradation. The percentages of dissolved and particulate phosphorus of paper mill effluent (PME) total phosphorus were of the same order of magnitude as those of BKME, but less than 20% of the dissolved phosphorus was of the reactive type. Approximately 50-60% of the particulate phosphorus in PME was dissolved in degradation tests, and 90% of it was biologically available.

This study investigated the relation between seasonal stratification and sediment phosphorus release in a seasonally stratified lake. Lake quality monitoring was conducted for 10 months from April 2010 to January 2011 in Lake Hongfeng, southwestern China. Destratification generated strong mixing from surface to bottom waters in the early autumn. The lake water was well-mixed vertically within 3 days and became anoxic within next few months. Total phosphorus concentrations of the whole water column increased by 15-20% as a result of high surface sediment concentrations of total phosphorus and reactive phosphorus. In seasonally stratified lakes, high reactive phosphorus content in sediments may form a larger flux of dissolved phosphorus in the sedimentwater interface following turnover. Technical measures should be taken to increase dissolved oxygen concentration and control the water circulation in this lake, especially during the cooling period, to weaken the effect of destratification and prevent sediment phosphorus release.

Untilled dairy pasture has the potential to release more phosphorus to the environment than a regularly ploughed pasture. In this paper we report the initial results of a study comparing the effects of cultivation, phosphorus (P) fertiliser (10, 35, and 100 kg P/ha), and two types of vegetation (ryegrass (Lolium perenne) or ryegrass mixed with clover (Trifolium repens)) in a randomised complete block design. Phosphorus was measured in soil samples taken from depths of 0–20 mm and 0–100 mm. Waters extracted from the 0–20 mm samples were also analysed. In all cases, the P concentrations (Olsen P, Colwell P, Total P, CaCl2extractable P, Dissolved Reactive P, and Total Dissolved P) in the top 20 mm declined with ploughing. Dissolved Reactive P measured in the soil water was 70% less overall in the ploughed plots compared with the unploughed plots, and by 35 weeks after P treatments the decrease in Dissolved Reactive P was 66%. The effects of the fertiliser and pasture treatments were inconclusive. The data suggest that ploughing can lower the risk of P exports from intensive dairy farms in the trial area.

Summary. The dissolution of North Carolina phosphate rock (NCPR) in soil was investigated in a laboratory study using surface soils sampled from 28 permanent pasture sites. The relationships between phosphorus (P) dissolved, P availability and various soil properties were investigated using simple and multiple linear regression and the findings related to the relative effectiveness of NCPR for pasture production at the sites. The extent of dissolution of NCPR was positively correlated to P buffering capacity (r2 = 0.42). Phosphorus buffering capacity and titratable acidity together accounted for 72% of the variance in dissolution. Bicarbonate-extractable P (‘available’ P) generally increased as dissolution increased. However, the increase in available P was consistently lower for soils with higher P buffering capacity. The proportion of dissolved P that was available also decreased with increasing P buffering capacity (r2 = 0.63). Consequently, the increase in available P was highest for soils with very low to low P buffering capacity. This suggests that the effectiveness of NCPR as a fertiliser may be more closely related to the availability of dissolved P, than to the amount of NCPR dissolved in a soil. Consistent with this laboratory finding, the agronomic effectiveness of NCPR relative to superphosphate measured in the field tended to decrease with increasing P buffering capacity. The agronomic effectiveness of NCPR was comparable with superphosphate only at certain sites, and with some noted exceptions, most of these had surface soils with very low to low P buffering capacity. The high relative effectiveness of NCPR at these sites was mostly attributed to the loss of superphosphate by leaching. Since NCPR dissolves much more slowly than superphosphate, only a small amount of the P applied as NCPR would be lost during leaching events. Slow dissolution of the remaining NCPR probably supplied a small amount of dissolved P over an extended period of time, and due to the low P buffering capacity, much of this was available to plants.

We evaluated phosphorus (P) and inorganic nitrogen (IN) export from two agricultural and two forested watersheds on the nutrient-rich but relief-poor Boreal Plain. One agricultural stream was in a watershed that contained cropland, while the second consisted of mixed agricultural activities. Over the 2-year study, total dissolved phosphorus (TDP) concentrations were proportionately high, particularly in the agricultural streams. Flow-weighted TDP averaged 82% of the total phosphorus (TP) in the agricultural streams and 43% in the forested streams. In all watersheds, TDP was almost exclusively dissolved reactive phosphorus and most of the annual P export was in summer. The type of agricultural activity in the watershed influenced IN speciation; in the mixed agricultural watershed, 94% of IN export was ammonium, whereas 98% of IN load was nitrate from the cropland watershed. Disproportionately high TDP to TP export from agricultural watersheds suggests that, in areas of low relief and relatively high soil water P content, land clearing may influence dissolved more than particulate phosphorus export.

Overlying sediment and pore waters were collected in summer and winter at upstream (Jintang) and downstream (Neijiang) sites of the Tuohe River, which is one of the five largest tributaries of the Yangtze River in China. Phosphorus species, including soluble reactive phosphorus (SRP), soluble unreactive phosphorus (SUP), and total dissolved phosphorus (TDP), and some diagenetic constituents including dissolved Fe(II), Mn(II), and sulfide in overlying and pore waters, were measured systematically. The seasonal variations and vertical distributions of phosphorus species in overlying and pore waters at both sampling sites were obtained to elucidate some aspects of the transport and transformations of phosphorus. Based on the profiles of pore and overlying waters as well as the TDN/TDP data during an algal bloom in 2007, it was clearly demonstrated that phosphorus was the main factor limiting the phytoplankton growth in the Tuohe River.

Eutrophication has long been an environmental problem and the effects from fertilizingarable land is a known source. The degree of phosphorus saturation (DPS)and easily soluble phosphorus (P) are different variables used in different countriesto try to predict the leaching of P from soils. The purpose of this master thesiswas to investigate what variable can be used as a predictor for leached P from soilsand to investigate what extent P leaching from the topsoil can be readsorbed inthe subsoil. The extraction method used for DPS was the Swedish standard lactateextraction and for easily soluble P were distilled water, CaCl2-solution and artificialrainwater with recipe from SMHI used. Three different soils in Sweden were used,two arable soils with different chemical properties and one forest soil. The soilswere filtered (2 mm) and put into columns since the texture was of interest ratherthan the structure. CaCl2-solution was used to saturate the samples and artificialrainwater was used for irrigation. The results showed that easily soluble P is areasonable indicator for leached P and that the subsoil affects the total leachingof P. However, no significant correlation was found between DPS and leached P,indicating that it may not be a suitable indicator of leaching. On the other hand,DPS can be seen as a reasonable indicator for easily soluble P since the correlationtest showed almost significant correlation. The results also showed that the electricconductivity in the leachate correlates to the leached P for the arable soils. For amore reliable result, more soils should be analyzed during more days.

Eutrophication due to phosphorus (P) enrichment continues to be a primary water quality concern affecting freshwater and marine estuaries around the world. Excessive anthropogenic P inputs, driven by the need to meet the rising food and energy demands of a growing and increasingly urbanized population, have resulted in the buildup of P creating legacy (historical) P pools in agricultural landscapes. There is growing evidence that remobilization of accumulated legacy P can interfere with conservation efforts aimed at curbing eutrophication and improving water quality. Less is known about the magnitude and effects of these legacy P pools on dissolved reactive P (DRP) losses in tile-drained systems. This dissertation consists of three separate inquiries into how legacy P may affect DRP losses in tile drains. In the first inquiry, we examined the possibility of developing a suitable pedo-transfer function (pedoTF) for estimating P sorption capacity (PSC). Subsequent PSC-based indices (Phosphorus Saturation Ratio (PSR) and Soil Phosphorus Storage Capacity (SPSC)) were evaluated using daily water quality data from an in-field laboratory. The pedoTF derived from soil aluminum and organic matter accurately predicted PSC (R² = 0.60). Segmented-line models fit between PSR and soluble P (SP) concentrations in both desorption assays (R² = 0.69) and drainflows (R² = 0.66) revealed apparent PSR thresholds in close agreement at 0.21 and 0.24, respectively. Linear relationships were observed between negative SPSC values and increasing SP concentrations (R² = 0.52 and R² =0.53 respectively), and positive SPSC values were associated with very low SP concentrations in both desorption assays and drainflows. Zero SPSC was suggested as a possible environmental threshold. Thus, PSC-based indices determined using a pedoTF could estimate the potential for SP loss in tile drains. Also, both index thresholds coincided with the critical soil test P level for agronomic P sufficiency (22 mg kg^-1 Mehlich 3 P) suggesting that the agronomic threshold could serve as an environmental P threshold. In the second inquiry, PSC- based indices in addition to other site characteristics present in a P index (PI), were used as inputs in the development of a multi-layer feed-forward artificial neural network (MLF-ANN). The MLF-ANN was trained, tested, and validated to evaluate its performance in predicting SP loss in tile drains. Garson’s algorithm was used to determine the weight of each site characteristic. To assess the performance of ANN-generated weights, empirical data from an in-field laboratory was used to evaluate the performance of an unweighted PI (PI_NO), a PI weighted using Lemunyon and Gilbert weights (PI_LG), and an ANN-weighted PI (PI_ANN) in estimating SP losses in tile effluent. The MLF-ANN provided reliable predictions of SP concentrations in tile effluent (R² = 0.99; RMSE = 0.0024). Soil test P, inorganic fertilizer application rate (FPR), SPSC, PSR, and organic P fertilizer application rate (OPR), with weights of 0.279, 0.233, 0.231, 0.097, and 0.084, respectively, were identified as the top five site characteristics with the highest weights explaining SP loss in tile discharge. These results highlighted the great contribution of both contemporary and legacy P sources to SP concentrations in tile discharge. Also, PI_ANN was the only PI with a significant exponential relationship with measured annual SP concentrations (R² = 0.60; p < 0.001). These findings demonstrated that MLF-ANNs coupled with Garson’s algorithm, can accurately quantify weights for individual site characteristics and develop PIs with a strong correlation with measured SP in tile discharge. Finally, in the third inquiry, we compared DRP loads and flow-weighted mean DRP (FDRP) concentrations in P source and P sink soils and evaluated the predominant DRP concentration – discharge (C-Q) behavior in these soils on a daily and event scale. At the daily scale, C-Q patterns were linked to the soil P status whereby a chemostatic and dilution behavior was observed for P source and P sink soils, respectively. At the event scale, C-Q patterns were linked to soil P status, flow path connectivity, and mixing of event water, matrix water, and rising shallow groundwater. The predominant anti-clockwise rotational pattern observed on P source soils suggested that, as the discharge event progressed, contributions from P poor waters including matrix and shallow groundwater resulted in lower DRP concentrations on the rising limb compared to the falling limb. However, the variable flushing and dilution behavior observed on the rising limb suggested that, in addition to discharge and soil P status, rapid exchanges between P pools, the magnitude of discharge events (Q), and the relative number of days to discharge peak (D_rel) also regulated DRP delivery. On the other hand, the predominant non-hysteretic C-Q behavior in P sink soils suggest that DRP loss from these soils can be discounted. Our collective results highlight the need for nutrient and conservation practices focused on P drawdown, P sequestration, and P supply close to the crop needs, which will likely be required to convert P sources to sinks and to avoid the conversion of P sinks to sources.

Phosphorus (P) loss from agricultural soils has been identified as one of the major causes of eutrophication of surface waters. This study was conducted to evaluate the suitability of various measures of soil P as indicators of risk potential for P loss from agricultural soils to surface waters. To fulfill the research objective, soil samples were collected from six major soil series in southern Ontario, and were subjected to simulated precipitation and to leaching. Relationships between various soil P measures and dissolved reactive P (DRP) concentration in surface runoff and subsurface flow were assessed. Amongst the selected soil test P (STP) and the estimates of degree of P saturation (DPS), DPSM3-2 [Mehlich-3 P/(Mehlich-3 Al + Fe)], DPSM3-3 (Mehlich-3 P/Mehlich-3 Al), and water extractable P (WEP) had the highest correlation with DRP concentration in surface runoff and leachate across all six soil series. The Fe-oxide coated filter paper P (FeO-P) method gave the second best predictor of DRP concentration through a split-line linear model. The Olsen P test was significantly correlated to DRP losses in runoff and leachate but it was generally not as strongly correlated to DRP losses as were other soil P measures. Given that soil WEP concentration can represent risk of soil P loss, a study with a greater range of soils (n=391) suggested that DPSM3-2 and DPSM3-3 tended to overestimate P losses from alkaline soils, especially when soils had high DPSM3-2 or DPSM3-3. In comparison, soil FeO-P and DPSOl-b [Olsen P/(Olsen P + P sorption index)] each were significantly correlated to DRP concentrations in surface runoff, subsurface water and soil WEP concentration, and showed reasonable accuracy. Compared to STP and routine DPS, a detailed soil DPS estimated from P sorption isotherm (DPSsorp) and P buffering capacity (PBC0), could provide reliable predictions of runoff DRP concentration across different soil types. Within each soil type, runoff DRP concentration increased linearly with increasing DPSsorp following a common slope of approximately 1.79, while the common change point was at a PBC0 value of approximately 0.29 L mg-1. A unit change in the PBC0 value resulted in a much greater change in runoff DRP concentration below the change point than above the change point.
The OMAFRA (Ontario Ministry of Agriculture, Food, and Rural Affaires) – MOE (Ontario Ministry of Environment) Nutrient Management Joint Research Program and the University of Guelph-OMAFRA (Environmental Sustainability Research Theme) Research Program.

The aim of this diploma thesis was to clarify the differences among three different ponds (Bolevecký, Třemošenský, Šídlovský) situated in Pilsen. All of the above mentioned ponds are recreational areas where Bolevecký pond is best known for his water quality improvements since 2006 (after application of Fe and Al - colagulants and also fish - stock changes). The main difference was based on the growth of submersed water plants. The macrophytes were growing slowly or not at all in Bolevecký pond. There was a huge expansion of macrophytes (mainly Myriophyllum spicatum species) in Třemošenský and Šídlovský ponds therefore the water plants must be regulated during summer seasons by mechanical harvesting. The water in all three ponds proves the same qualities but the differences may be found in the nutrient composition of sediments. The fractionation analysis (the founders Psenner and Puczsko) confirmed the fact that all localities are poor in phosphorus however the differences were found in content of iron. The increased content of iron was observed in sediments of Šídlovksý and Třemošenský ponds (mainly in BD fraction - the iron was unstable under redox potential changes). The result of this analysis proves that phosphorus is potentially more available for macrophytes in sediments of Třemošenský and Šídlovský...

Indiana University-Purdue University Indianapolis (IUPUI)
This study investigated nutrient export during three spring storm events in two different land use watersheds (agricultural and mixed land use) in a glacial till landscape of the Midwestern, USA. The objectives of the study were: (1) to determine how land use affects water, nitrate, soluble reactive phosphorus (SRP) and dissolved organic carbon (DOC) delivery (timing, amount) to streams during spring storms in two central Indiana watersheds with contrasting land use; and (2) to determine nitrate, SRP and DOC flow pathways to streams during spring storms. High frequency stream sampling of nutrients and cations, coupled with hydrograph separations using δ18O, was used to identify water flow pathways and event and pre-event water contributions to the streams. Data indicate land use and storm characteristics play a role in the export of water and nutrients. In the agricultural watershed (Watershed A), the storm hydrograph is dominated by pre-event water, whereas the mixed land use watershed (Watershed M) storm hydrograph is more event water dominated. Watershed A also contains higher nutrient concentrations, especially nitrate. High bulk precipitation and greater maximum intensity export more nitrate, SRP, and DOC to the streams. Results also indicate nitrate, DOC, and SRP concentrations display distinct temporal patterns during spring storm events. DOC concentration increased with stormflow and peaked on the rising limb/with maximum discharge regardless of land use or storm event. In Watershed A, SRP concentration followed a similar pattern to DOC during small storms; therefore they are believed to be exported together with flushing of saturated near-surface soil waters via macropores/overland flow. However, SRP likely has multiple flowpaths, one dominated over another depending on the storm. Nitrate concentrations matched Ca2+, Mg2+, and Na+ trajectories and decreased with stormflow, suggesting a tile drain/subsurface flowpath. Nitrate and SRP peak concentrations are delayed relative to DOC in Watershed M. The wet retention ponds in the headwaters are believed to delay the stormflow response, and therefore, the delivery of nutrients to the stream.

The happy insight that biology and geology meet through chemistry has been seen throughout this book when life and rocks interact. A chemical called water transformed this planet’s rocks and opened them to give life its elemental building blocks. The energy in the Earth became the energy in simple cells through chemical wheels. Sunlight split the water with the help of dissolved rocks, and the oxygen from that reaction brought yet more elements out of the rocks and into life. That insight addresses a long-standing mystery here. Long ago, the biggest biologi­cal change in the history of the planet created plant and animal life. What caused the seas to teem with weird new life? I think the periodic table connects that biological event to a previous global geological change. If so, then once again, chemical reactions opened up geology to provide new possibilities for biological complexity. Chemistry shaped the flow of geology and biology at once. The evidence for this connection is like something that happened with the ekko sculpture in northwest Scotland from Chapter 2 (Figure 2.1). After the sculpture had been built, an archaeologist dropped by and found incisions in ekko’s rocks. The archaeologist read the shape and depth of the incisions and concluded that the stones were older than everyone thought, and must have been used for a structure now lost. Like in ekko, there are “incisions” on the Earth made by massive geological processes. Geologists have read these and have concluded that a worldwide event altered the planet’s surface. This geological event was also a chemical event. Soon after, a profusion of fossils filled the rocks. This biological event was also a chemical event. The common denominator of chemistry connects the geology to the biology. The geological event provided chemicals that life used in new ways: especially oxygen, phosphorous, and calcium, resulting in new energy, shells, and signals for life. This hypothesis is that chemical availability drove the evolution of life, and that the periodic table shaped the timing of life’s greatest expansion.