Co-transport of dissolved organic matter and heavy metals in soils induced by excessive phosphorus applications

To evaluate the effects of long-term applications of phosphorus fertilizers on mobility of dissolved organic matter （DOM） and heavy metals in agricultural soils, a sandy soil and a loamy soil were spiked with ammonium phosphate at application rates of 0, 25, 50, 100, 250, and 500 mg P per kilogram of soil. A series of 15-cm long soil columns were constructed by packing incubated soils of varying concentrations of P. The soil columns were consecutively leached by simulated rainfalls for six cycles. The contents of water extractable organic carbon in both sandy and loamy soils increased significantly with increasing rates of P applications. Relatively high rates of P applications could induce a marked increase in DOM concentrations in the leachates, the effects were larger with the sandy soil rather than with the loamy soil. Applications of P changed the partitioning of trace metals in the soil solids and the soil solutions. The increased P application rates also seemed to elevate the leaching of Cu, Cd, and Zn from soils. The concentrations of Cu, Cd, and Zn in the leachates were positively correlated with DOM, probably due to the formation of metal-DOM complexes. In contrast, Pb concentrations in the leachates were negatively correlated with DOM, and decreased with increasing rates of P applications. The boosted leaching of DOM induced by high rates of P applications was probably due to the added phosphate ions competing for adsorption sites in the soil solids with the indigenous DOM.

High-Resolution Profiles of Dissolved Reactive Phosphorus in the Porewaters of Lake Sediments Assessed by DGT Technique

The technique of DGT (diffusive gradients in thin films) was applied to obtain high-resolution vertical profiles of dissolved reactive phosphorus (DRP) in sediment porewater of Lake Chaohu, a shallow eutrophication lake. Three kinds of DGT probes (with three thicknesses of diffusive gel: 0.38 mm, 0.78 mm and 1.18 mm) measured vertical concentration and induced flux from solid to solution phase which had intricate variations with depth. The results indicated that higher concentrations and induced fluxes of DRP were achieved by using DGT probe with thicker diffusion layer (CDGT1.18 > CDGT0.78 > CDGT0.38) and relatively stable DRP concentration profiles using DGT probes with 0.78 mm diffusive gel were obtained in each sediment core. The DRP concentrations displayed a clear gradient from Core C1 to Core C3 in sediment porewaters due to different sources and exchange degrees of reactive phosphorus. Compared to the concentrations obtained by the centrifugation technique, the concentrations of DRP resulting from the DGT technique were higher because some dissolved reactive phosphorus compounds have always been neglected using conventional centrifugation method.

Environmental dynamics of nitrogen and phosphorus release from river sediments of arid areas

Human activities lead to the accumulation of a large amount of nitrogen and phosphorus in sediments in rivers.Simultaneously,nitrogen and phosphorus can be affected by environment and re-enter the upper water body,causing secondary pollution of the river water.In this study,laboratory simulation experiments were conducted initially to investigate the release of nitrogen and phosphorus from river sediments in Urumqi City and the surrounding areas in Xinjiang Uygur Autonomous Region of China and determine the factors that influence their release.The results of this study showed significant short-term differences in nitrogen and phosphorus release characteristics from sediments at different sampling points.The proposed secondary kinetics model(i.e.,pseudo-second-order kinetics model)better fitted the release process of sediment nitrogen and phosphorus.The release of nitrogen and phosphorus from sediments is a complex process driven by multiple factors,therefore,we tested the influence of three factors(pH,temperature,and disturbance intensity)on the release of nitrogen and phosphorus from sediments in this study.The most amount of nitrate nitrogen(NO_(3)^(–)-N)was released under neutral conditions,while the most significant release of ammonia nitrogen(NH_(4)^(+)-N)occurred under acidic and alkaline conditions.The release of nitrite nitrogen(NO_(2)^(-)-N)was less affected by pH.The dissolved total phosphorus(DTP)released significantly in the alkaline water environment,while the release of dissolved organic phosphorus(DOP)was more significant in acidic water.The release amount of soluble reactive phosphorus(SRP)increased with an increase in pH.The sediments released nitrogen and phosphorus at higher temperatures,particularly NH_(4)^(+)-N,NO_(3)^(–)-N,and SRP.The highest amount of DOP was released at 15.0℃.An increase in disturbance intensity exacerbated the release of nitrogen and phosphorus from sediments.NH_(4)^(+)-N,DTP,and SRP levels increased linearly with the intensity of disturbance,while NO_(3)^(–)-N and NO_(2)^(–)-N were more stable.This study provides valuable information for protecting and restoring the water environment in arid areas and has significant practical reference value.

Modelling nitrogen and phosphorus cycles and dissolved oxygen in the Zhujiang EstuaryⅠ.Model development

An ecosystem-based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamic and sediment model. As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both there nutrient cycles each using five variables, namely, dissolved inorganic nutri- ent, detritic organic matter, benthic matter, phytoplankton and zooplankton.

Effect of dissolved phosphorus on alkaline phosphatase activity in marine microalgae

Alkaline phosphatase activity (APA) and dissolved phosphorus were monitored during the batch cultures of two bone microalgae. Results indicate that variation of APA was in the shape of 'S' curve. Different specs of dissolved phaphorus had different effects on APA. The concentrations of dis solved inorganic phosphorus (DIP) and and molecular dissolved organic phosphorus (SDOP) had a sig nificant effect on APA, while the concentration of large molecular dissolved organic phosphorus (LDOP) had a little effect on APA., and the increase of APA could accelerate the decomposing of LDOP in the medium. Results also show that algae species and abundance had why a little effect on APA.

Simultaneous nitrogen and phosphorus removal under low dissolved oxygen conditions

A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODCr, TN and TP varied in a range of 352.9 mg/L-1338.2 mg/L, 34.4 mg/L-96.3 mg/L, and 2.21 mg/L-24.0 mg/L, the average removal efficiencies were 94.9%, 86.7% and 93.0%, respectively. During the test period of two months, effluent meas of CODCr,, BOD5, NH3-N, TN and TP were below 50 mg/L, 25 mg/L, 10 mg/L and 1.0 mg/L respectively. The low dissolved oxygen activated sludge process has a simple flow sheet, fewer facilities and high N and P removal efficiency. It is very convenient to retrofit the conventional activated sludge process with the above process.

Continuous flow analysis of dissolved total phosphorus in seawater by UVK_(2)S_(2)O_(8) online digestion method

Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determinationmethods presently. The compounds used for the phosphorus recovery test were categorized into three groups accordingto their chemical structure. It was found that low power UV irradiation can decompose POC or PC bonds efficientlybut may be inefficient for POP bonds. Heating-bath in acid condition is useful for decomposing POP bonds. Usingthe continuous flow analysis system (Auto-analyzer II), UV digestion and heating-bath, series experiments were carriedout based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and thefactors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally,the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flowanalysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of33%~51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decompositionefficiency for dissolved phosphorus based on the continuous flow analysis system.

MECHANISM OF PHOSPHORUS RELEASE FROM THE SEDIMENT-WATER INTERFACE IN XIAMEN BAY

The adsorption/desorption of phosphorus across the sediment -water interface is the main mechanism that controls the buffering capacity of DRP in coastal and estuarine water. Determination by three processes revealed that: 1) DRP flux from early diagenesis in surface sediment is F = 31.9ug/(m2.d ), which is only 1/1600 of the ammonia released; 2) at normal temperature and in the long term, the TDP released by adsorption /desorption across the sediment-water interface is a function of the major environmental factors; and 3) based on the determined SODR and assumed average water depth H(m) and residence time tR(d), the maximum flux of DRP can be estimated.

Synthesis and Structural Characterization of Organophosphorus Ylide-1-(3-nitrophenyl)-2-(triphenyl phosphoranylidene)ethanone

The title compound Ph3P=C（H）C（O）PhNO2 （L） has been prepared by the addition of triphenylphosphine in acetone as solvent to 2-bromo-1-（3,nitrophenyl）ethanone followed by the addition of alkaline solution of sodium hydroxide. The yellow crystals of the title ylide were grown in methanol/chloroform solution by drop method without stirring at room temperature. The solid state structure of ylide has been established by X-ray crystallography analysis. In the molecule of the title compound, the geometry around the P atom is nearly tetrahedral and the O atom is in synperiplanar orientation to the P atom. The nitrophenyl ring is twisted with respect to the plane of the carbonyl group through an angle of 36.6（1）°. The crystal （C26H20NO3P, Mr = 425.40） belongs to the monoclinic system, space group P21/n with a = 10.889（3）, b = 14.467（3）, e = 13.872（4）A, β = 103.08（3）°, V = 2128.6（10） A3, Z= 4, T= 100（2） K, R = 0.059 and wR = 0.163 for 3984 observed reflections with I〉 2σ（I）.

离子液体在Phosphor-aldol反应中的应用

主要介绍1-丁基-3-甲基咪唑氟硼酸盐离子液体作为反应溶剂,用于Phosphor-aldol反应。与有机溶剂作介质的反应条件相比,离子液体中的反应条件相对温和,一般情况下反应可在常温、常压下进行,在反应速率、转化率和选择性上与有机溶剂相近。同时,离子液体能循环利用,节约了资源,倡导了绿色化学的理念。

Composition characterization and transformation mechanism of dissolved organic phosphorus in wastewater treatment using 31P NMR spectroscopy

The migration and transformation of phosphorus components in wastewater treatment plants(WWTPs)play a crucial role in the convergence and circulation of phosphorus.However,the composition and variation of dissolved organic phosphorus(DOP)in WWTPs were unclear because of its complex nature,hindering its efficient detection.In this study,the DOP species and their transformation during the treatment process in WWTP were comprehensively analyzed.First,two enrichment methods were assessed for their effectiveness at facilitating wastewater analysis:lyophilization and aluminum salt precipitation.Aluminum salt precipitation was found to be better because its application allowed 31P nuclear magnetic resonance(31P NMR)spectroscopy to identify more species in the secondary effluent:orthophosphate(Ortho-P)(81.1%–89.3%of the dissolved total phosphorus),pyrophosphates(Pyro-P)(0%–2.3%),orthophosphate monoesters(Mono-P)(7.0%–10.77%),orthophosphate diesters(Di-P)(1.0%–2.96%),and phosphonate(Phos-P)(1.7%–5.16%).Furthermore,the variation and transformation mechanism of phosphorus,particularly those of DOP,during the entire sewage-treatment process were elucidated.Among the treatment steps,biological treatment combined tertiary treatment achieved better DOP removal efficiencies.Therein,biological treatment mainly removed Mono-P and Di-P with removal efficiencies of 33.3%and 41.7%compared with the effluent of the grit chamber.Di-P has higher bioavailability and is more easily converted and utilized by microorganisms than Mono-P.However,Phos-P,with low bioavailability,was hardly utilized by microorganisms,which showed only 18.4%removal efficiency in biological treatment.In tertiary treatment,coagulation process exhibited higher removal ability of Ortho-P(69.1%)and partial removal efficiencies of DOP,resulting in an increase in the DOP proportion in TP.In addition,Phos-P could not be effectively removed through the biological treatment and was only partially reduced via the adsorption process by large particles,zoogloea or multinuclear hydroxyl complexes.The results of this study can provide a theoretical basis for efficient phosphorus removal in WWTPs.

Study of colloidal phosphorus variation in estuary with salinity

The variation of colloidal phosphorus with salinity in estuary was studied in this paper, which was compared with those of particle and truly dissolved phosphorus with the purpose of finding out the similarities and differences between their behaviors in the estuary. Distribution patterns of phosphorus in particle, colloidal and truly dissolved phase at different salinities and their relationships with suspended particulate matter were also studied to understand the transformation and transporta- tion of colloidal phosphorus in estuarine area. The result showed that the concentrations of total colloidal phosphorus, organic colloidal phosphorus and inorganic colloidall phosphate all descended from river-end to sea-end, illustrating their terrigenous source. Rat.ios of organic to total colloidal phosphorus decreased with salinity＇s increment, indicating that organic phosphorus was influenced by scavenging process of colloid more significantly as compared with inorganic phosphate. Both of the phosphorus variation tendencies and the proportion between organic and inorganic phosphorus in colloidal phase was similar with that in truly dissolved phase while different from that in particle phase.

Interactive effects of irrigation and exponential fertilization on nutritional characteristics in Populus 3 euramericana cv. ‘74/76' cuttings in an open-air nursery in Beijing, China

Nutritional characteristics determine tree stock quality to a considerable extent. Exponential fertilization can induce nutrient reserves within juvenile trees, but its validity on poplar is contingent on interaction with a scientific irrigation regime due to limited water resources under global warming. In the present study, we raised 3200 Populus 9 euramericana cv. ＇74/76＇ cuttings under four irrigation regimes of 0（I0）, 60 %（I60）, 80 %（I80）, and100 %（I100） of field capacity for soil moisture content with or without（control） the employment of nitrogen（N） addition delivered as exponential fertilization at the rate of 8 g N cutting^（-1）（E8） in an open-air nursery in Beijing, China. Both height and diameter increased with the increment of soil moisture ratio or in response to exponential fertilization（EF） without any interactive effects. In general, concentrations of N, phosphorus（P）,and potassium（K） declined with time in stem but foliar N concentration did not change. Under the I100 regime, EF increased foliar N concentration relative to the control but failed to affect N concentration in stem in September, when both N concentration and N content were increased by EF under the I80 regime. Stem-K content and concentration by EF under the I80 regime also increased in September,therefore EF-treated cuttings had a higher ratio of K content in stem to that in whole plant（%ANAR）. Vector diagnosis for nutritional status indicated that EF resulted in dilution of K concentration but induced a steady-state P uptake in leaves under all irrigation regimes. Therefore, EF of N addition could promote N uptake to leaves of P. 9 euramericana cv. ＇74/76＇ cuttings, but it had a null effect on N and P reserves in stem and impaired K reserves.In conclusion, the irrigation regime of 80 % field capacity of soil moisture content was suggested for the culture of juvenile P. 9 euramericana cv. ＇74/76＇ cuttings. As the interactive meaning, EF was also suggested for its excellent promotion on both N and K uptakes.

Storm phosphorus concentrations and fluxes in artificially drained landscapes of the US Midwest

This study investigates phosphorus (P) concentrations and fluxes in tile drains, overland flow, and streamflow at a high temporal resolution during 7 spring storms in anagricultural watershed in Indiana, USA. Research goals include a better understanding of 1) how bulk precipitation and antecedent moisture conditions affect P concentrations and fluxes at the watershed scale;2) how P concentrations and fluxes measured in tile drains translate to the whole watershed scale;3) whether P losses to the stream are significantly affected by overland flow. Results indicate that bulk precipitation and antecedent moisture conditions are not good predictors of SRP or TP losses (either concentration or flux) to the stream. However, along with previously published storm data in this watershed, results indicate a threshold-based behavior whereby SRP and TP fluxes significantly increase with precipitation when bulk precipitation exceeds 4 cm. Although total SRP and TP fluxes are very much driven by flow, SRP and TP fluxes are somewhat limited by the amount of P available for leaching for most storms. On average, SRP fluxes in tile drains are 13% greater than in the stream, and stream SRP fluxes account for 45% of TP fluxes at the watershed scale. Our results indicate that when P is the primary concern, best management practices aimed at reducing P losses via tile drains are likely to have the most effect on P exports at the watershed scale.

Effect of Waterscape Structures on Nitrogen and Phosphorus Removal Efficiency in Revetment Wetland System

The effect of aeration and waterscape structures reaeration system on nitrogen and phosphorus removal efficiency in revetment wetlands was studied by laboratory simulation. The results showed that the removal efficiency of TN, TP in tranquil flow waterscape was 61% and 72%; aeration and waterscape structure system promoted nitrogen and phosphorus removal efficiency in revetment wetland through increasing the DO content in the water, compared with system without artificial oxygen, the removal efficiency of TP in waterscape structures increased by 11. 6%-19. 1%, and that of TN increased by 10.5%-16. 1%; meanwhile, disturbance brought by the waterscape structure systems enhanced the adsorption of TP and flocculation effect; in addition, nitrification was confirmed as the main control step of TN removal in revetment wetland system.

Field Utilization of Dried Water Hyacinth for Phosphorous Recovery from Source-Separated Human Urine

This research demonstrated the feasibility of converting source-separated human urine into a solid fertilizer by means of continuous absorption and solar thermal evaporation using dried water hyacinth as adsorbent. In a preliminary experiment, the dried petioles of water hyacinth (DWH) absorbed urine in a mean rate of 18.78 ml·g-1 within 7 d, retrieving about 3.46% urine dissolved solids (UDS). In an advanced experiment, the DWH’s capacity of urine absorption declined from an initial 2.73 L·kg-1·d-1 to 0.68 L·kg-1·d-1, with a requirement of material change in about 25 effective days and an average ratio of 25 (L) to 1 (kg). Phosphorus (P2O5) concentration in the adsorbent increased from 0.46% (material baseline) to 3.14% (end product), suggesting a satisfactory recovery of the element. In field application, the urine was discharged, not in wet weather, onto the DWH via a tube connected to a waterless urinal. There are several ways to use the UDS-DWH as P(K)-rich fertilizer, e.g., making soluble fertilizer for foliage spraying to encourage prolific flowering and fruiting. Apparently, utilization of water hyacinth waste to recover dissolved plant nutrient elements from source-separated urine will benefit the environment in a wide range of perspectives. The herein innovative use of water hyacinth is also expected to be useful in the recycling of certain dissolved hazardous materials.

Integrating Source and Transport Factors with Best Management Practices to Derive an Index for Assessing Phosphorus Mobilization Risks from Mauritius Sugarcane Fields

Application of phosphorus (P) fertilisers to sugarcane fields in Mauritius increased almost four-fold per unit area over the past 60 years. Some of the applied P accumulated in the soils and can therefore be transported eventually to surface waters resulting in the eutrophication thereof. Precaution measures such as an appropriate P index as a management tool is required. Source factors (dissolved P, particulate P, P application rates, methods and timing), transport factors (soil erosion, runoff potential and precipitation factor) and a best management practices multiplier were integrated to derive an index for assessing risks of P mobilisation from the island’s sugarcane fields. Farmers and their advisors can use the proposed P index during the planning process before sugarcane fields are planted and will be applicable for the whole crop cycle of 6 - 7 years if factors in the index do not change. The index can be also valuable in the selection of alternative management practices that could reduce the risks of P losses from sugarcane fields where the potential of P movement is initially high. Sensitivity analyses and edge-to-plot field tests showed that the P index needs further improvement, especially the estimation of soil erosion rates. The P index can, however, be applied by farmers and their advisors if they are well informed about the index’s capability.

Structural Characters and Isolated Stability of Phosphorus Polyanions

The optimized geometries at the RHF/6-311++G** level, the relatively stable energy at the MPW1PW91/6-311++G** level and the structural characters of anions have been acquired, indicating the stability is related to the chemical bonding of μ2?P atoms and the distri- bution of negative charges. The configurations of cage units P8 4- and P9 5- are stable due to the less torsion, but their ES values are relatively higher than that of P7 3- with more μ2?P atoms and the isolated stability is lower than that of P7 . They potentially play an important role as intermediate 3- in chemical reaction of producing complicated polyphosphides. Based on the related electronic properties, a stable polyanion must have low valence electron concentration, no (μ2?P)?(μ2?P) bond and a little dispersive charge. The earmark IR frequencies of cage units have been assigned to the vibration models in the end.

Impact of Feedlot on Soil Phosphorus Concentration

Raising cattle in feedlots is becoming more common in Argentina, but there is little information available about the effects of this practice on soil phosphorus (P) dynamics. In this study, concentrations of water and Bray -1 extractable soil P were quantified in a feedlot (upper and lower slope positions in the feedlot pen), runoff area and pasture during 2006 - 2008. The feedlot showed higher P concentrations in all P forms, soluble reactive P, soluble nonreactive, total soluble P, and Bray-P1 when compared to runoff area and pasture. Most of the total soluble P was soluble reactive P from the soil in the feedlot and the runoff area, while soluble nonreactive P predominated in the pasture. Concentrations of total soluble P were elevated in the feedlot at the soil surface, ranging on average from 158.71 to 245.86 mg?P?kg?1, and had a rapid decrease within the first 20 cm and remained relatively low, about 25.53 - 27.33 mg?P?kg?1. The evidence that total soluble P concentration in the feedlot was significantly (p < 0.05) higher than that registered in the pasture at 20 - 40 and 40 - 60 cm soil depth suggests a potential transfer of P through the soil from the surface. Although the feedlot had a moderate increase of 23.05 to 24.55 mg?P?kg?1 from the background concentration, it may represent a long-term source of increased nutrient loading to groundwater. Soil extractable Bray-1 P in the top 0 - 2.5 cm fluctuated from 659.26 to 45.36 mg?P?kg?1 in the feedlot and pasture, respectively. The relationship between soil P extracted by test and TSP was linear, and correlation coefficient was r2 = 0.95.

Dissolved organic carbon,a critical factor to increase the bioavailability of phosphorus during biochar-amended aerobic composting

Considerable research efforts have been devoted to increase phosphorus(P)availability during aerobic composting.However,there is little discussion weather the dissolved organic carbon(DOC)controls the transformation among P-fractions.Thus,we investigated the changes in DOC compositions and P-fractions during biochar-amended composting(wet weight basis,5%and 10%).TP content continuously increased since the'concentration effect'during aerobic composting.NaHCO_(3)-Pi,NaOH-Pi and HCl-Pi were main P-fractions,and biochar can improve P-bioavailability by transforming NaOH-Pi and HCl-Pi into NaHCO_(3)-Pi.Structure equation models(SEMs)indicated that biochar enhanced the P-bioavailability through regulating the decomposition of DOC.Our results at least hint that the activation mechanism on P under the influence of DOC during biochar-amended composting.