Different Forms Of Phosphorus Research Articles

The effect of bacteria on uranium sequestration stability by different forms of phosphorus

ABSTRACT Immobilisation of uranium (U (VI)) by direct precipitation of uranyl phosphate (U-P) exhibits a great potential application in the remediation of U (VI)-contaminated environments. However, phosphorus, vital element of bacteria’s decomposition, absorption and transformationmay affect the stability of U (VI) with ageing time. The main purpose of this work is to study the effect of bacteria on uranium sequestration mechanism and stability by different forms of phosphorus in a water sedimentary system. The results showed that phosphate effectively enhanced the removal of U (VI), with 99.84%. X-Ray Diffraction (XRD), Scanning Electron Microscopy and Energy Dispersive Spectrometer (SEM-EDS), and X-ray Photoelectron Spectroscopy (XPS) analyses imply that U (VI) and U (IV) co-exist on the surface of the samples. Combined with BCR results, it demonstrated that bacteria and phosphorus have a synergistic effect on the removal of U (VI), realising the immobilisation of U (VI) from a transferable phase to a stable phase. However, from a long-term perspective, the redissolution and release of uranium immobilisation of U (VI) by pure bacteria with ageing time are worthy of attention, especially in uranium mining environments rich in sensitive substances. This observation implies that the stability of the uranium may be impacted by the prevailing environmental conditions. The novel findings could provide theoretical evidence for U (VI) bio-immobilisation in U (VI)-contaminated environments.

Genomic and phenotypic characterization of 26 novel marine bacterial strains with relevant biogeochemical roles and widespread presence across the global ocean.

Prokaryotes dominate global oceans and shape biogeochemical cycles, yet most taxa remain uncultured and uncharacterized as of today. Here we present the characterization of 26 novel marine bacterial strains from a large isolate collection obtained from Blanes Bay (NW Mediterranean) microcosm experiments made in the four seasons. Morphological, cultural, biochemical, physiological, nutritional, genomic, and phylogenomic analyses were used to characterize and phylogenetically place the novel isolates. The strains represent 23 novel bacterial species and six novel genera: three novel species pertaining to class Alphaproteobacteria (families Rhodobacteraceae and Sphingomonadaceae), six novel species and three new genera from class Gammaproteobacteria (families Algiphilaceae, Salinispheraceae, and Alteromonadaceae), 13 novel species and three novel genera from class Bacteroidia (family Flavobacteriaceae), and one new species from class Rhodothermia (family Rubricoccaceae). The bacteria described here have potentially relevant roles in the cycles of carbon (e.g., carbon fixation or energy production via proteorhodopsin), nitrogen (e.g., denitrification or use of urea), sulfur (oxidation of sulfur compounds), phosphorus (acquisition and use of different forms of phosphorus and remodeling of membrane phospholipids), and hydrogen (oxidation of hydrogen to obtain energy). We mapped the genomes of the presented strains to the Tara Oceans metagenomes to reveal that these strains were globally distributed, with those of the family Flavobacteriaceae being the most widespread and abundant, while Rhodothermia being the rarest and most localized. While molecular-only approaches are also important, our study stresses the importance of culturing as a powerful tool to further understand the functioning of marine bacterial communities.

Organic Phosphorus Fractions in Relation to Soil Aggregate Fractions of Black Soil

Knowledge of long-term phosphorus behavior is essential to improve soil structure, nutrient supply potential, and the sustainability of cropping systems. A 45-year long-term experimental trial was used to observe organic phosphorus fractionation and its effects on soil aggregation and nutrient distribution at three depths (0–20, 20–40, and 40–60 cm) in Vojvodina Province, Serbia, under maize monoculture and maize/barley rotation. Five fertilizing systems were studied, including Control, NPK, NPK + maize remains, NPK + manure, and NPK + manure in rotation. Soil aggregates were fractionated into four size categories (>2000, 2000–250, 250–53, and <53 μm) using a wet sieving method. The samples were analyzed for main indicators, including different forms of phosphorus, total and available (PT and PA), as well as its organic forms (Labile Po, Biomass Po, Mod. Labile Po, Fulvic acid Po, Humic acid Po, and Resistant Po), and other fertility parameters. Significant differences in total and available phosphorus as well as all observed organic phosphorus fractions were evident between treatments with and without organic amendments, particularly in the 0–20 and 20–40 cm soil layers. Moderately labile P forms were dominant across all treatments, while labile forms constituted a smaller proportion. The most notable differences between treatments were observed in the labile and moderately labile forms, as well as in the resistant form of organic phosphorus. Manure application led to increased nutrient content in macroaggregates (>250 μm) compared to microaggregates. Microaggregates (<250 μm) were predominant across all depths, while stable structural aggregates did not show a significant increase after manure application. PCA highlighted significant correlations between soil characteristics, including total and available P, total organic carbon, clay content, and enzyme activity, across different aggregate sizes and organic P fractions. Overall, long-term mineral fertilization combined with organic amendment application induced variations in phosphorus fractions and the content of carbon, nitrogen, and phosphorus associated with aggregates in the first two soil layers, except for aggregate size classes.

Forms and Distribution of Phosphorus along A Toposequence at the University of Benin, Nigeria

The experiment was conducted at University of Benin, Nigeria, involving soil samples from four toposequence sites (Crest, Middle, Lower, and Bottom) at different depths (0-15 cm, 15-30 cm, and 30-45 cm). A total of 36 samples were collected and analyzed for various parameters using standard procedures. The parameters included particle size distribution, pH, total organic carbon (TOC), total nitrogen (N), available phosphorus (P), Carbon (C), Hydrogen (H), Magnesium (Mg), Potassium (K), Sodium (Na), ECEC, and Aluminum (Al). Results indicated that pH was lowest in the Crest area (pH 4.10 at 30-45 cm depth) and highest in the Bottom area (pH 5.80 at 0-15 cm to 30-45 cm depth). Different soil properties showed varying highest values across the toposequence depths. These properties included Total organic C, Total N, Available P, Ca, K, Mg, H, Na, ECEC, sand content, and the various forms of phosphorus. The correlation table revealed significant positive and negative relationships between different forms of phosphorus and various soil physical and chemical properties. The experiment demonstrated distinct variations in soil properties along the toposequence sites and depths. The findings contribute to a better understanding of soil characteristics in the studied region, aiding in informed agricultural practices and land management decisions.

Inference of Rock Phosphate, Phosphorus Solubilizing Bacteria and Lime on Phosphorus Content and Economic Yield of Green Gram

Aim: To study the effect of Rock Phosphate, Phosphorus Solubilizing Bacteria, and Lime on phosphorus content in the soil, Phosphorus Uptake, and Economic yield of green gram (var. DGGS-4).
 Study Design: This experiment was conducted through a completely randomized design with 10 treatments and 3 replications.
 Place and Duration of Study: The research was conducted at the Department of Soil Science and Agricultural Chemistry, Central Agricultural University, Imphal between February 2019- November 2019.
 Methodology: Available phosphorus content in soil was estimated spectrophotometrically by Bray and Kurtz No. 1 method, the Active Phosphorus was determined by the addition of Saloid-bound phosphate, Aluminum phosphate, iron phosphate, and calcium phosphate, and total Inorganic P is the summation of all the inorganic forms of P. Total Phosphorus (Total P) in Soil was estimated by using Murphy-Riley solution and 5M NaOH and the intensity of yellow color was read at 730 nm in a spectrophotometer, organic P was calculated from the difference between total phosphorus and total mineral P, and the uptake of phosphorus was computed from the data on P concentration and dry matter yield.
 Results: The release and fixation pattern of different forms of phosphorus, its uptake, and the economic yield of green gram were significantly affected by the application of rock phosphate singly or combination with PSB and lime. Comparing among the different treatments, significantly higher accumulation of available Phosphorus, Phosphorus uptake, and economic yield were recorded in soil treated with Rock phosphate in combination with Phosphocare, Bacillus megatherium, and lime which is at par with treatment with Rock phosphate in combination with Bacillus megatherium and lime.
 Conclusion: The investigation revealed that the release and fixation pattern of different forms of phosphorus, its uptake, and the yield of green gram are significantly affected by the application of RP singly or combination with PSB and lime.

Efficient protection of the Baltic Sea needs a revision of phosphorus metric

Eutrophication of the Baltic Sea is driven by phosphorus and nitrogen. While the anthropogenic point source loads of both nutrients have decreased markedly, further reductions are needed. This is true particularly for phosphorus, as highlighted by its stringent abatement targets in HELCOM’s Baltic Sea Action Plan. To meet the targets, more results need to be achieved in non-point source abatement, specifically from agricultural sources. The growing pressure for phosphorus abatement from agriculture may lead to environmentally and economically inefficient outcomes unless we account for the variability in how different forms of phosphorus respond to abatement measures, and how these forms contribute to eutrophication. The precautionary and efficiency improving way to advance policies is to either replace or supplement the Total Phosphorus metric with a metric more accurate in reflecting the biologically available phosphorus. This policy fix becomes more important as the relative share of agricultural emissions of total pollution increases.

Concentration of different forms of phosphorus in soils affected by the little auk (Alle alle) and their relationship with tundra vegetation in Spitsbergen (Svalbard, High Arctic)

The purpose of the present study was to determine the link between planktivorous little auks (Alle alle) and their soil fertilization, the concentration of total, and different forms of phosphorus in the surface layer of the High Arctic soils and the vascular plant composition of the tundra vegetation. Samples of the surface soil layer (0–10 cm) were collected along three pairs of transects (affected and unaffected by little auks) at different locations in Spitsbergen (Svalbard). The surface layer of soils affected by little auks was characterized by a significantly higher mean concentration of Ptot (1.02–1.44 g kg−1) compared to those not affected by seabirds (0.58–0.77 g kg−1). The mean concentration of different forms of P was also generally higher in soils affected by seabirds (i.e., labile P: 0.13–0.34 g kg−1, moderately labile P: 0.31–0.90 g kg−1, stable P: 0.27–0.39 g kg−1) than in unaffected soils (labile P: 0.04–0.18 g kg−1, moderately labile P: 0.30–0.37 g kg−1, stable P: 0.12–0.24 g kg−1); however, the differences were not always significant, most likely due to the high heterogeneity of specific environmental conditions at the local scale such as soil type, soil chemical composition, and vegetation type. Vascular plant cover was significantly and positively related to the concentration of the P forms studied in the soil. The phosphorus gradient significantly altered the composition of the vascular plants and explained 58.4% of its variation. Little auks are an important source of soil phosphorus in terrestrial ecosystems in the High Arctic that significantly affect the cover and composition of vascular plants.

Interannual variations in the nutrient cycle in the central Bohai Sea in response to anthropogenic inputs

In recent decades, there has been growing concern regarding the effects of human activities on the coastal nutrient cycle. However, interannual variations in the coastal nutrient cycle in response to anthropogenic nutrient input have rarely been quantified. In this study, a hydrodynamic-ecological model capable of describing the nitrogen and phosphorus cycles was used to analyze interannual variations in the nutrient cycle in the central Bohai Sea, a typical semi-enclosed sea in the Northwest Pacific. The results showed an increasing trend of dissolved inorganic nitrogen and particulate nitrogen from 1998 to 2017, whereas different forms of phosphorus showed no obvious interannual variations. The annual nutrient budgets were also quantitatively estimated from 1998 to 2017. This indicates that atmospheric nitrogen deposition plays an important role in interannual variations in the nitrogen cycle. A large amount of nitrogen from anthropogenic inputs was mainly removed by sedimentation processes instead of increasing the standing stock of nitrogen in the sea. With the reduction of anthropogenic inputs, the model showed that a variety of forms of nitrogen concentration decreased linearly, whereas phosphorus concentration increased slightly. Therefore, although environmental governance can effectively alleviate water eutrophication, it is necessary to avoid the situation where the dissolved inorganic nitrogen concentration in the sea becomes too low for phytoplankton to grow, which may determine the primary productivity and eventually affect fishery resources.

Simultaneous adsorption removal of organic and inorganic phosphorus from discharged circulating cooling water on biochar derived from agricultural waste

A high level of organic and inorganic phosphorus exists in discharged circulating cooling water (DCCW), therefore, the efficient removal of phosphorus from DCCW is necessary. Herein, the adsorption performance and mechanism of hydroxyethylidene diphosphonic acid (HEDP) and phosphate from DCCW on pyrolysis biochar derived from agricultural waste (wheat and corn straw wastes, and peanut shell powder) were systematically investigated. Among them, biochar prepared from wheat straw and modified with MgCl2 and CeCl3 (molar ratio 3:1), i.e., WS-3Mg/Ce, showed optimal phosphorus removal from DCCW. The pseudo-second-order and Freundlich model well described the adsorption of HEDP, PO43−, and total phosphorus (TP) on WS-3Mg/Ce. Further, negative Gibbs free energy (ΔG) indicated that WS-3Mg/Ce adsorbed HEDP and phosphate through physical adsorption and chemical reactions, with the chemical reaction being dominant. Scanning electron microscopy-energy dispersive X-ray spectroscopy and X-ray diffraction results revealed that CePO4 and Mg3(PO4)2 appeared on WS-3Mg/Ce after adsorption, and the diffraction bands of metal oxides or hydroxides decreased. Fourier transform infrared and X-ray photoelectron spectroscopy results showed that O–H, M-O, M-O-P, and O–P on the surface of WS-3Mg/Ce participate in the reaction. This suggests that the adsorption of HEDP and phosphate on WS-3Mg/Ce mainly involves metal binding via Ce and Mg, and chemical complex via OH−. This study provides a promising approach for removing different forms of phosphorus simultaneously from DCCW via biochar and contributes to the resource recovery of agricultural and forestry waste. Future work is needed for the optimization of the biochar to promote the adsorption capacity and renewability in treating real DCCW.

Changes in soil properties and the phoD-harboring bacteria of the alfalfa field in response to phosphite treatment.

- Phosphite and phosphate increase the total phosphorus and available phosphorus.- The pH was the dominant factor influencing the phoD-harboring bacterial community under phosphite fertilizer.- The response of soil properties and phoD-harboring bacterial community to phosphate and phosphite fertilizers differed in the alfalfa field.

Biochar reduces bioavailability of phosphorus during swine manure composting: Roles of phoD-harboring bacterial community

The bioavailability of phosphorus is a vital index for evaluating the quality of compost products. This study examined the effects of adding wheat straw biochar (WSB) and bamboo charcoal (BC) on the transformation of various phosphorus fractions during composting, as well as analyzing the roles of the phoD-harboring bacterial community in the transformation of phosphorus fractions. Adding WSB and BC reduced the available phosphorus content in the compost products by 35.2 % and 38.5 %, respectively. Redundancy analysis showed that the alkaline phosphatase content and pH were the most important factors that affected the transformation of phosphorus fractions. The addition of biochar resulted in changes in the composition and structures of the phoD-harboring bacteria communities during composting. In addition, the key bacterial genera that secreted alkaline phosphatase and decomposed different forms of phosphorus under WSB and BC were different compared with those under control. Network and correlation analysis demonstrated that the activities of phoD-harboring bacteria could have been enhanced by biochar to accelerate the consumption of available phosphorus, and the activities of key phosphorus-solubilizing bacteria (Lysobacter, Methylobacterium, and Saccharothrix) might be inhibited when the pH increased, thereby increasing the insoluble phosphorus content.

Influence of Optimal Land Use Allocation on Phosphorus Loss in the Process of Rainfall and Runoff

In order to explore the impact of optimized land use allocation on phosphorus loss in the runoff process of a small watershed in the Three Gorges Reservoir area, a traditional agricultural model catchment area (CG) and a catchment area after optimized land use allocation in the Shipanqiu watershed in Zhong County, Chongqing (EG) were selected as the research object, sampling at the outlets of the two catchment areas, respectively, to monitor the runoff process and different forms of phosphorus in rainfall events and to analyze the influence of land use configuration on the law of phosphorus loss. The results showed that:① in the 10 monitored rainfall and runoff processes, the ρ[total phosphorus (TP)] of EG was lower than that of CG, and the ranges of the two were 0.09-0.75 mg·L-1 and 0.13-2.82 mg·L-1, respectively. Compared with that of CG, EG significantly reduced the peak value of TP. ② The average EMC of TP, total dissolved phosphorus (TDP), dissolved inorganic phosphorus (DIP), and particulate phosphorus (PP) in the process of rainfall and runoff was lower than that of CG, and EG and CG showed significant differences in EMC of TP, TDP, and DIP (P<0.05); the main form of phosphorus loss in the two catchment areas in the process of rainfall and runoff was TDP, but the average TDP/TP of EG was larger. ③ The output load of EG was 45%, 43%, 57%, and 47% lower than that of the TP, TDP, DIP, and PP in CG. The output load of EG and CG of various forms of phosphorus was significantly correlated with the total runoff (P<0.01). In addition, the slope of the linear fitting of various phosphorus forms in the CG catchment area to the total amount of runoff was 1.66 to 1.75 times that of EG. The output load of various phosphorus forms of CG was more sensitive to runoff than that of EG, and the output per unit area in the process of rainfall and runoff was more sensitive than that of EG. The amount of sand could have caused the difference in phosphorus concentration and output load more than the output per unit area. Optimizing land use configuration can effectively reduce the loss of various forms of phosphorus and provide a reference for the prevention and control of phosphorus loss in small watersheds in the Three Gorges Reservoir area.

Blowout dynamics in lime‐rich and lime‐poor coastal dunes in the Netherlands

AbstractBlowouts can mitigate the negative effects of acidification in the topsoil, especially in industrialized countries with high atmospheric nitrogen (N) deposition. However, blowout activity may differ between lime‐rich and lime‐poor dunes, which creates different regional responses and interactions between processes and patterns.To further explore this, five Dutch dune sites were selected over the gradient from lime‐rich and lime‐poor dunes. We mapped blowout activity in 5 years between 1996 and 2017 with aerial photographs, and used transport potential, atmospheric N‐deposition and rabbit density as explanatory variables. We also studied soil and plant parameters in the field in different stages of succession.All sites showed fluctuations, but blowout activity net increased in the lime‐rich sites, and decreased in the lime‐poor sites. Differences in blowout activity could not be explained by sand transport potential, which differed between years, but not sites. Differences in blowout activity could to some extent be explained by rabbit density and exceedance of the critical N load, although the transition site between lime‐rich and lime‐poor dunes showed high blowout activity despite low rabbit density.Differences in blowout activity between lime‐rich and lime‐poor dunes were also related to differences in topsoil chemistry, especially with respect to lime content, Fe content and different forms of phosphorus (P). High pH was a key factor, which reduced sensitivity to high N deposition through reduced P‐availability to the vegetation, higher proportion of arbuscular mycorrhizal plants, which may improve food quality for rabbits, and lower root biomass, which may increase erodibility of the dune soil. High pH and low P availability may even occur in lime‐poor dunes with a little lime, as long as blowouts stay active and counteract acidification. However, when pH values drop below 6.5, P availability to the vegetation will increase and start feedback processes leading to blowout stabilization.

Effect of precipitation and sediment concentration on the loss of nitrogen and phosphorus in the Pasikhan River

Abstract Natural and anthropogenic factors influence the entry of pollutants into surface waters and their accumulation in aquatic ecosystems. This study aimed to investigate precipitation and sediment concentration on the outflow of different forms of phosphorus (P) and nitrogen (N) in three primary land-use types along the Pasikhan River, the biggest river entering the Anzali Wetland in the Southern Caspian sea. Water sampling was performed on a monthly basis during the time bracket of 2017–2018. Different forms of P including total, soluble, particulate, total reactive, and dissolved reactive, and total Kjeldahl N, soluble N, particulate N, and were determined in the water samples. Total phosphorus and total Kjeldahl nitrogen contents lay within the range of 2.2–4.7 and from 0.14 to 0.33 mg l−1, respectively, downstream of the river. The highest monthly outflow of P from the watershed at the Agriculture station was recorded in October. Substantial conformity was found between the monthly trends of and and the trend of precipitation. The results indicated that sediment load intensified after an increase in the rainfall rate, leading to elevated N and P concentrations in the river water, mainly as particulate phosphorus and soluble nitrogen. It can also be inferred from the result that the concentration of N and P is directly related to the sediment concentration increase due to the rainfall. Increasing levels of nutrients such as N and P in the Pasikhan River can cause eutrophication in the Anzali Wetland, which needs conservative measures for reducing these elements' dynamic in the watershed.

Variation entry of sediment, organic matter and different forms of phosphorus and nitrogen in flood and normal events in the Anzali wetland

Abstract Phosphorus (P), nitrogen (N) and organic component are released from the soil into surface bodies by runoff and erosion, causing the pollution and eutrophication of water resources. This study aimed to investigate the seasonal changes in loads of N and P components, and organic matter (OM) in the Pasikhan River in flood and normal conditions. Sampling was performed monthly during normal flow conditions and for five flood events. The concentrations of P and N components were measured in the samples. The OM of the suspended sediments was determined by the combustion method. Under the normal flows, the maximum loads of total P and OM were about 0.553 mg l−1 (STD = 0.11) (November) and 3.41% (STD = 1.17) (November) in the autumn, respectively. The total N concentration of 0.533 mg l−1 (STD = 0.12) was observed in the winter. In the flood events, the TP, TN and OM ranged from 0.48 to 3.5 mg l−1, 0.28 to 0.79 mg l−1 and 1.24 to 4.11%, respectively. The results indicated a high risk of eutrophication in the Pasikhan River. Also, the study revealed that in a severe flood event, some 113.9 tons h−1 of OM can be released from the river watershed. Furthermore, there was a high correlation between the amount of P and OM losses with the concentration of suspended sediments in different flood events. Finally, it is concluded that if the floods are not controlled, they not only cause a rapid loss of soil nutrients and OM but also lead to severe eutrophication in the Anzali wetland.

Biogenic silica, eutrophication risk and different forms of phosphorus in surface sediments of Anzali wetland, Caspian Sea

This investigation aimed to determine the contents of biogenic SiO2 and different phosphorus forms (P) and to evaluate phosphorus ecological risk in surface sediment of Anzali wetland. According to the results, biogenic SiO2 ranged from 0.29 to 3.04%. Also, the average biogenic SiO2 at all studied stations was 1.36 ± 0.83%. Results indicated that total P (TP) was between 493 and 771 ppm, averaged 637.20 ± 79.41 ppm. Moreover, inorganic P (INTP) ranged from 256.63 to 376.89 ppm and composed 51.46 ± 4.68% of total P. The percentage of P-forms was in descending order: residual-P > Fe-P > Ca-P > Al-P > labile-P. Phosphorus pollution index (PPI) ranged from 0.82 to 1.29, with an average of 1.06 in the sediment of the Anzali wetland. The Sediment P saturation (SPS) values varied considerably from 40.96 to 83.57, with an average SPS value of 49.1. Based on the eutrophication risk index, all stations except one had a low eutrophication risk index.

Different adsorption behavior of inorganic and organic phosphorus on synthetic schwertmannite: Assessment and mechanism of coexistence

Schwertmannite (Sch) is a common secondary-iron (Fe)-hydroxylsulfate mineral that is found in acidic environments containing high concentrations of iron and sulfate (SO42-). The presence of Sch affects the occurrence states, mobility, transportation pathways, and transformation processes of elements. To understand the interaction between Sch and different forms of phosphorus in the hydrosphere, the inorganic phosphorus (iP) and organic phosphorus (oP) were selected as adsorbates to investigate their adsorption behavior on synthetic Sch. The results showed that iP and oP have good adsorption effects on Sch; the maximum adsorption capacities of iP and oP were 87.9 mg·g−1 and 18.4 mg·g−1 (as P), respectively. Their adsorption processes can be effectively described by the Langmuir isotherm. Both iP and oP were competitively adsorbed onto Sch, but the adsorption affinity of iP was greater than that of oP. The adsorption of iP occurred by the exchange of SO42- ions on the surface and in the tunnels of Sch, whereas oP was adsorbed primarily by the exchange of SO42- ions on Sch surface. These results showed that, the formation of Sch in acidic environments can influence the mobility and transport of various forms of P and inhibit the eutrophication of water bodies.

Dynamic stormwater management to mitigate phosphorous export

Altered stormwater flow characteristics and associated changes in nutrient and sediment fluxes due to urbanization threaten the water quality of many water bodies. For example, particle-bound phosphorus in stormwater runoff adds to the nutrient pool that can produce harmful algal blooms, and the associated particulate material can endanger fish and other living organisms in surface waters by increasing turbidity. While many studies have investigated how Total Solids (TS) particle size distributions vary in urban stormwater and the associated design criteria for Best Management Practices (BMPs) to remove TS, few studies have included different forms of phosphorus and their association with particle sizes to characterize design criteria to specifically maximize Total Phosphorus (TP) removal. This highlights a gap in our understanding of how the particle size distributions of TP and TS are related, and how these particle size distributions vary within and between storm events. Bridging this knowledge gap can improve design methods for BMPs specifically targeting phosphorus removal. This study characterizes within event (i.e., hourly) TP and TS particle size distributions and associated fluxes from urban catchments in the City of Cambridge, Massachusetts, to characterize potential TP and TS removal based on four different diversion and treatment strategies. The stormwater diversion strategies integrate new insights on temporal variations in particle size distributions and mass loading characteristics. In terms of diverted stormwater, the volume of stormwater treated tends to control more than what water is treated (e.g., first flush, event high flows, or smaller event flows). Based on the event data obtained in this study, considering flow volume different diversion approaches are optimal for TP vs TS, but treatment combined with particles sizes < 100 μm is best for both TP and TS.

The Influence of Mechanical Composition and Mineral Composition of Calcareous Soil on Slope Farmland on Phosphorus Fixation

Soil erosion on slope farmland causes the degradation of soil quality and eutrophication of water bodies due to the loss of phosphorus. In order to explore the influence of soil mechanical composition and mineral composition on phosphorus fixation, we selected calcareous soil on slope farmland in the Three Gorges Reservoir area as the research object and separated the samples on the basis of particle size. Next, we determined the content of different forms of phosphorus for each particle size, and then characterized and analyzed the mineral composition. The adsorption performance of each particle size was also studied. The results show that the calcareous soil on slope farmland has a high proportion of coarse fractions, and the carbonate minerals enriched in coarse fractions will fix a large amount of phosphorus and degrade soil quality. As slope farmland is prone to soil erosion, when the soil undergoes selective migration, the loss of fine fractions will increase the proportion of coarse fractions and aggravate soil quality degradation. Meanwhile, because of the large amount of phosphorus adsorbed by fine fractions, the available phosphorus is easily lost with fine fractions, leading to eutrophication of water bodies.

Study of distribution of various fractions of Phosphorous as influenced by long term nutrient management practices in Vertisol

A long term field experiment was conducted at Instructional Farm of College of Agriculture, Indira Gandhi Agricultural University, Raipur, Chhattisgarh to evaluate the effect of long term nutrient management practices on distribution of various fractions of Phosphorous in Vertisol. The experiment was consisted 5 treatment replicated four times in a randomised block design. The treatments were T1 (control), T2 (GRD), T3 (YT 5t ha-1), T4 (YT 6t ha-1) and T5 (YT 6t ha-1 with FYM). Fertilizer prescription equation for rice developed in previous under STCR project as FN =4.05T-0.57SN-0.78 ON, FP = 1.46 T - 3.09 SP-0.31 OP and FK = 1.61 T - 0.10 SK -0.14 OK were used to calculating the fertilizer doses for yield targeted treatments. Initial soil value of phosphorus under different treatments was varied from 6.13 to 25.40 kg ha-1due to long term nutrient management practices. All the P fractions were significantly higher in T2 followed by T5, T4, T3 and lowest in T1. All P fractions (Saloid, Al, Red, Fe, and Ca P) were recorded higher values with the treatment T2 (GRD) due addition of a large amount of phosphorous applied in soil. The sequential order of dominance of different forms of phosphorus in Vertisol were “Ca-P > Red-P > Fe-P > Al-P >Saloid-P”. The percentage contribution of different fractions to the total P was in the order of “Ca-P > Red-P > Fe-P > Al-P >Saloid-P. The highest grain and straw yield were recorded in T5 (YT 6t ha-1 with FYM) followed by T4 (YT 6t ha-1), T2(GRD) and lowest in T1(control). Among different P fractions, Red-P was found the most important P fractions contributing toward grain yield with ‘R2’values 0.88.