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.

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.

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.

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.

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.

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.

Phosphorus transformation under the influence of aluminum,organic carbon,and dissolved oxygen at the water-sediment interface:A simulative study

The effects of sediment aluminum(Al),organic carbon(OC),and dissolved oxygen(DO)on phosphorus(P)transformation,at the water-sediment interface of a eutrophic constructed lake,were investigated via a series of simulative experiments.The above three factors had various influences on dissolved P concentration,water pH,water and surface sediment appearance,and P fractions.Additions of Al had the greatest effect on suppressing P release,and the water p H remained alkaline in the water-sediment system under various OC and DO conditions.No dissolution of the added Al was detected.31P-N M R characterization suggested that OC addition did not promote biological P uptake to polyphosphates under oxic conditions.The simulation result on the added phytate indicated the absence of phytate in the original lake sediment.As compared to the reported natural lakes and wetland,the water-sediment system of the constructed lake responded differently to some simulative conditions.Since Al,OC,and DO can be controlled with engineering methods,the results of this study provide insights for the practical site restorations.

Distribution, residence time, autotrophic production, and heterotrophic removal of DOP in the Mirs Bay, northern South China Sea

The importance of dissolved organic phosphorus(DOP) as a potential nutrient source for primary producers in marine systems has been recognized for up to eight decades, but currently, the understanding of the biogeochemistry of DOP is in its infancy. In the present study, monthly data between 2000 and 2014 were used to analyze the temporal and spatial distributions of DOP in the Mir Bay, the northern South China Sea. The DOP residence time(TDOP) was also investigated using a simple regression analysis in combination with chlorophyll a(Chl a) measurements while excess DOP(ΔDOP), produced by the biogeochemical processes of autotrophic production and heterotrophic removal, was determined using a two-component mixing mass-balance model in combination with salinity measurements. The results showed that the DOP concentration was(0.017±0.010) mg/L higher in the surface-water compared with the bottom-water and higher in the inner Tolo Harbour and waters adjacent to Shatoujiao compared with the main zone of the bay. Although seasonal changes and annual variability in the DOP were small, the surface DOP concentration was higher in the wet season(April–September)than in the dry season(October–March) due to the impacts of seaward discharges and atmospheric deposition into the bay. Measurement and regression results showed that the DOP release rate from phytoplankton production was about 1.83(gP)/(gChl a) and the TDOP was about 7 d, which implied that the DOP cycle in the bay was rapid. The ΔDOP was calculated from the model to be about 0.000 mg/L in the main zone of the bay and about 0.002 mg/L in the inner Tolo Harbour and waters adjacent to Shaotoujiao, suggesting that the autotrophic production of DOP was almost balanced by the heterotrophic removal in the main zone of the bay and dominated in the inner Tolo Harbour and waters adjacent to Shaotoujiao. In conclusion, the Mirs Bay is very productive and fairly heterotrophic.

不同类型含磷营养物质对微小亚历山大藻(Alexandrium minutum)生长和毒素产生的影响

采用显微镜细胞计数和麻痹性贝毒的高效液相色谱分析方法,通过对比磷酸二氢钾、磷酸甘油和三磷酸腺苷(ATP)等含磷营养物质对微小亚历山大藻生长和毒素产生的影响,研究了微小亚历山大藻对不同类型含磷营养物质的利用情况。结果表明,在磷限制条件下,加入磷酸二氢钾、磷酸甘油和ATP均能促进微小亚历山大藻的生长,所获得的最大藻细胞密度分别为22700、28400和27800藻细胞/ml,对数期生长速率分别为0.12/d、0.14/d和0.15/d,溶解态有机磷对藻生长的促进作用稍好于溶解态无机磷。三种含磷营养物质对毒素产生的效应没有明显差别,稳定期藻细胞毒素含量分别为22.87、23.98和21.80fmol/cell。磷限制对毒素组成的影响很大,磷限制条件下膝沟藻毒素GTX1/4的含量占绝对优势,GTX2/3含量很少。在添加含磷营养物质后,GTX1/4所占比例降低,GTX2/3比例增加,说明磷限制显著改变了微小亚历山大藻的毒素组成。对藻体碱性磷酸酶活性分析的结果显示,磷限制组具有最高的碱性磷酸酶活性,添加有机磷化合物实验组的碱性磷酸酶活性显著高于添加无机磷化合物的实验组。研究结果表明,微小亚历山大藻可以利用实验中采用的无机磷化合物和有机磷化合物,但其利用溶解态有机磷化合物的机制尚不清楚,可能是通过诱导合成碱性磷酸酶来水解培养基中的溶解态含磷有机物,从而释放无机磷酸盐用于藻细胞的生长。

渗育性水稻土渗滤液中的磷组分研究

本试验在太湖地区长江岸边砂质渗育性(漏水型)水稻土上进行,研究在麦稻轮作条件下连续两年施用不同磷肥(每季P 0、30、70、150和300 kg hm-2),稻季各层次土壤溶液中(30、60和90 cm)磷的组分,以探讨磷素在剖面中垂直纵向移动的规律。结果表明:施肥处理在施肥初期提高了30 cm处土壤溶液中溶解磷浓度,对60 cm处溶解磷浓度影响不大,对90 cm处溶解磷浓度没有影响。各处理60 cm和90 cm处土壤溶液中溶解磷的浓度几乎全部超过水体富营养化磷的阈值,故在研究该地区水体富营养化时,要注意渗漏磷排放可能的贡献。特别应指出的是,除6月13日对照处理外,各处理90 cm处土壤溶液中的磷均以溶解有机磷为主,占总溶解磷的56%~100%,表明有机磷(外源加入或内源残留的)比无机磷对环境的潜在威胁将更大。

太湖地区渗育性水稻土径流中磷组分的研究

本试验于 2 0 0 2年在太湖地区渗育性水稻土上进行 ,研究不同施磷水平下 (P 0、30、70、15 0和30 0kghm-2 )麦稻轮作中土壤径流磷的损失。研究结果表明 :在麦稻轮作期间 ,除最高施磷处理P 30 0kghm-2的径流磷损失达到P 0 75kghm-2 外 ,其余各施肥处理与对照无显著差异。虽然径流损失的磷最多也不足施磷量的 0 1% ;但径流中溶解磷浓度均已超过水体富营养化磷浓度的阈值 ( 0 0 2mgL-1) ,故农田径流携带的磷长期进入水体也会加重水体富营养化。径流携带的磷以产生第一次径流时为最多 ;径流磷中以颗粒磷为主占总磷的 6 0 %以上 ;溶解磷则在 4 0 %以下 ,而溶解磷中以有机磷为主 ,除P 30 0kghm-2 处理外 ,其余处理的径流中溶解有机磷占总溶解磷的 5 2 0 %～ 76 2 %之间。因此 ,仅测定溶解的无机磷作为溶解磷组分 ,必将低估径流溶解磷的数量及其贡献 ;

夏季滇池不同来源溶解性有机磷特征及其生物有效性

夏季选取了滇池不同来源（滇池湖体、入湖河流和大气降雨）水样,研究了其溶解性有机磷（DOP）含量及分布特征,并利用酶水解技术表征了其 DOP 生物有效性.结果表明,滇池湖体、入湖河流和大气降雨 DOP 浓度分别在0.001~0.117,0.002~1.722,0.006~0.112mg/L（平均0.027,0.197,0.037mg/L）,分别占溶解性总磷（DTP）的18.3%~92.5%,4.2%~100%,25.4%~100%（平均55.3%,60%,58.9%）,不同来源 DTP 均以DOP 为主,入湖河流 DOP 浓度明显高于滇池湖体和大气降雨.不同来源 DOP 酶可水解磷（EHP）浓度分别为n.d.~0.058,n.d.~0.673,n.d.~0.031mg/L（平均0.017,0.064,0.010mg/L）,分别占 DOP 的0%~127.5%,0%~105.6%,0%~55.6%（平均77.9%,38.7%,23.2%）.不同来源DOP酶水解率（EHP/DOP）较高,滇池湖体DOP酶水解率明显高于入湖河流和大气降雨.不同来源DOP时空分布特征明显,且其生物有效性存在较大差异.其中,滇池湖体EHP以活性单酯磷和类植酸磷为主,入湖河流和大气降雨EHP以活性单酯磷为主,尤其是大气降雨二酯磷和类植酸磷含量较少,滇池湖体、入湖河流和大气降雨DOP生物有效性依次降低.不同来源DOP是与溶解性反应磷（SRP）同等规模的生物可利用磷源,二者共同维持了滇池富营养化.滇池治理要从全流域出发,考虑不同来源各形态磷对水质的影响.

基于ICP-AES法测定太湖溶解态有机磷的初步研究

以2010年5月27日太湖水样为测试对象,进行典型溶解性有机磷（草甘膦和植酸）的ICP-AES加标回收试验验证C18柱去除有机磷的能力,探讨了样品消解在ICP-AES法测定TSP过程的作用,使用ICP-AES法测定水样中不同形态磷含量间接定量太湖DOP水平,并与传统方法测得的DOP含量作对比。结果表明,过C18柱可去除水样中96%以上的有机磷,能实现过滤前后水样有机物差异的效果;水样经过消解后测定值（TSP）为0.025~0.095 mg/L,大大高于未消解系列测得值（0.009~0.030 mg/L）,ICP-AES法测定有机磷含量较高的水样时需要经过消解的预处理步骤;使用ICP-AES与C18柱相结合的方法测得太湖DOP含量为0.014~0.069 mg/L之间,大大高于传统比色法DOP测得值0.026~0.083 mg/L,前法能更准确的间接定量水体中DOP水平,而后法可能会大大高估DOP在水环境中的实际含量。

Degree of nutrient consumption as an aging index of upwelling or vertically mixed water in the northern Taiwan Strait

In order to determine the relative aging status of upwelled or vertically mixed water in the northern Taiwan Strait, a recently developed method of calculating the degree of nutrient consumption (DNC) was employed. Upwelling was detected at a water depth of about 75 m in summer. Bottom waters in the aphotic zone and newly-upwelled waters in the euphoric zone were found to be low in terms of their DNC. In general, a low DNC was noted alongside the other traditional upwelling indicators, such as lower temperature and degree of oxygen saturation, but higher salinity, apparent oxygen utilization, nutrient contents and chlorophyll-a. Enhanced vertical mixing, but without an apparent upwelling signal, was detected near the same location in winter.

Cyanobacterial extracellular alkaline phosphatase:detection and ecological function

Dissolved inorganic phosphorus is an important form of directly bioavailable phosphorus for cyanobacteria in natural water.Dissolved organic phosphorus could be used by cyanobacteria via alkaline phosphatase,which is produced mainly by bacteria and also cyanobacteria itself.Herein,we review the current knowledge of extracellular phosphatase excreted by cyanobacteria,highlighting the development of detection method and its ecological roles in regulating pho sphorus cycling in freshwater systems,which is based on reports for around 100 species of cyanobacteria.Recommendations are suggested concerning the extracellular phosphatase produced by bloom-forming cyanobacteria in terms of the ecological role,followed by a discussion of the future prospects for the study.

Analysis on Biological Stability and Influencing Factors of Northern Living District Water Distribution System

A northern living strict water network was employed to investigate interaction among biological stability and classical water quality indexes. Key water quality indexes on water quality were determined by the static test,then the correlations between biological stability and traditional water quality parameters were analyzed. Traditional water quality parameters and limited factors on bacteria were measured in summer and winter respectively. The results show that BDOC concentration change differently in summer and winter.Among classical parameters turbidity has a positive relation with BDOC but pH has a negative relation with BDOC. Total bacteria number shows a positive correlation with BDOC in the water distribution system.Residual chlorine shows a negative relation with total bacteria number. Fe content increasing will induce turbidity rising in water. To guarantee water safety,BDOC and chlorine content control must be incorporated together to restrict bacteria regrowth.

台湾海峡中北部上升流区各种形态磷的化学特性

根据1988年7月调查资料讨论了台湾海峡中北部海域夏季上升流区各种形态磷的分布特征。结果表明,上升流中心区(即海坛岛东侧一带水域)具有低温、高盐、低溶解氧;DIP,TDP,PP,TP较高;DOP较低(0.27);及DIP/DOP比值(约为1)较高的特性。DOP是该海域磷的主要形态(占TP的49.2％),其含量分布及其形态转化与生物活动直接相关,是该海域生物生产力高的体现。

Growth and alkaline phosphatase activity of Chattonella marina and Heterosigma akashiwo in response to phosphorus limitation

The growth and alkaline phosphatase activity（APA） of two raphidophyceae species Chattonella marina and Heterosigma akashiwo were investigated in response to P-limitation and subsequent addition of dissolved inorganic phosphorus（DIP, Na H2PO4） and two dissolved organic phosphorus（DOP） compounds： guanosine 5-monophosphate（GMP） and triethyl phosphate（TEP）. APA levels increased greatly after P-starvation as the decrease of the cellular phosphorus quotes（Qp）. C. marina responded to P-limitation quickly and strongly, with 10-fold increase in APA within 24 hr after P-starvation. The larger difference between maximal and minimal QP values in C. marina indicated its high capacity in P storage. APA of H. akashiwo was maximally enlarged about 2.5 times at 48 hr of P-starvation. After the addition of nutrients, cell numbers of C. marina increased in all treatments including the P-free culture, demonstrating the higher endurance of C. marina to P-limitation. However, those of H. akashiwo increased only in DIP and GMP cultures. APA increased only after the addition of the monophosphate ester GMP. The results suggest that quick responses of C. marina to P-limitation, high capacity in P storage as well as endurance for P-depletion provide this species an ecological advantage in phytoplankton community competition under DIP-limited conditions.

夏季青岛大气气溶胶中不同形态磷的浓度、来源及沉降通量

利用2016年6~7月在青岛采集的总悬浮颗粒物(TSP)样品,分析了其中不同形态磷的浓度,讨论了夏季气溶胶中总磷(TP)、溶解态磷(DP)、溶解态无机磷(DIP)和溶解态有机磷(DOP)的分布特征及来源,并估算了大气P的沉降通量.结果表明,夏季青岛大气气溶胶中TP的浓度为(49.3±30.6)ng·m^(-3),其中DP浓度为(15.5±10.4)ng·m^(-3),对TP的贡献为30.9%±11.0%.DP中以DIP占主导,其贡献平均约为60%.气溶胶中不同形态P的来源分析结果显示,夏季青岛气溶胶中P的来源复杂,受地壳源、人为源、生物质燃烧、农业施肥等多种源的共同影响.其中TP的38%来自土壤源的贡献,农业活动源和工业源的贡献分别为20%左右;DP中DIP主要受到农业活动源及燃烧源的影响,其贡献分别为51%和24%;DOP主要来源于土壤源及农业活动源,其贡献分别为41%和27%.观测期间,大气TP的干沉降通量为(51.7±31.7)μg·(m^2·d)^(-1),其中DP对TP干沉降通量的贡献为23.2%±8.2%.DP中DOP有重要贡献,约为DP干沉降通量的40%.DP的干沉降通量可支持黄海(0.5±0.3)mg·(m^2·d)^(-1)浮游植物碳的生产,对新生产力的贡献约为1%.