中国太湖环境土壤磷测试与磷释放

A microtiter plate assay (MPA) for soluble reactive phosphorus (SRP) was applied to samples in overlying water and pore water as well as in three forms of environmental soil test phosphorus (P) types: water soluble phosphorus (WSP), diluted calcium chloride extractable phosphorus (PCaCl2), and Olsen-P in the sediments of Taihu Lake, China, where potential P release in response to pH was analyzed. MPA for rapid P analysis was shown to be promising when applied on samples of natural water and sediment extracts. Concentrations of WSP and PCaCl2 in the sediments were much lower than those of Olsen-P. Olsen-P levels in the littoral sediments along the north coast of Meiliang Bay in Taihu Lake (80 to 140 mg kg^-1) were much higher than those in the mouth of the bay (less than 50 mg kg^-1). The risk of P release in the mouth area of Meiliang Bay was lower than that in the north littoral zone with a risk of sediment P release induced by pH increases.     

Lake Sediments from Dianchi Lake： A Phosphorus Sink or Source？

Dianchi Lake is a highly eutrophic lake in southwestern China where phosphorus (P) is the limiting element for eutrophication and where lake sediments play an important role in the P cycle. One hundred and eighteen sites were sampled throughout Dianchi Lake in 2002 to investigate the P loading of the lake sediments, while fresh surface sediments were studied in the laboratory to clarify its role for phosphorus. The results showed that concentrations of total phosphorus(TP) in sediments were very high, with a maximum value of 6.66 g kg^-1, and decreased with sediment depth. P adsorption on surface sediments was rapid with adsorption amounts higher in acidic than in alkaline conditions. The release experiments showed that P release increased as pH rose from 7.0 to 10.5. Additionally, compared with aerobic conditions, P release was much higher under anaerobic conditions, especially with low P content in the lake water. At present, the sediments in Dianchi Lake still function as a sink for phosphorus at high P levels in lake water. However, if the external P load was reduced and P content in lake water became low, the sediment would have a large potential for P release under anaerobic conditions.     

滇池沉积物的功能: 磷源还是磷库?

Dianchi Lake is a highly eutrophic lake in southwestern China where phosphorus (P) is the limiting element for eutrophication and where lake sediments play an important role in the P cycle. One hundred and eighteen sites were sampled throughout Dianchi Lake in 2002 to investigate the P loading of the lake sediments, while fresh surface sediments were studied in the laboratory to clarify its role for phosphorus. The results showed that concentrations of total phosphorus (TP) in sediments were very high, with a maximum value of 6.66 g kg^-1, and decreased with sediment depth. P adsorption on surface sediments was rapid with adsorption amounts higher in acidic than in alkaline conditions. The release experiments showed that P release increased as pH rose from 7.0 to 10.5. Additionally, compared with aerobic conditions, P release was much higher under anaerobic: conditions, especially with low P content in the lake water. At present, the sediments in Dianchi Lake still function as a sink for phosphorus at high P levels in lake water. However, if the external P load was reduced and P content in lake water became low, the sediment would have a large potential for P release under anaerobic conditions.     

滇池水和沉积物中氮磷空间变化

Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) and total phosphorus (TP) through analysis of bottom water and sediment (3 depths) samples collected at 118 sites around Dianchi Lake. The concentrations of K-N and TP for the lake bottom water in the Caohai part of the lake were much higher than those in the Waihai part, generally decreasing from north to south. In the sediments, the K-N concentration was higher in the Caohai part and the middle of the Waihai part. On the other hand, TP in the sediments was greater in the southern and western parts. Both K-N and TP had similar spatial distributions for the sediment samples of three different depths.Vertically, the KoN and TP concentration in the sediments decreased with an increase in depth. This was evidence that eutrophication and pollution of Dianchi Lake was becoming gradually more severe. Exterior factors including uncontrolled input of domestic and industrial effluents as well as non-point pollution around the lake were the main reasons for serious eutrophication; therefore, controlling these was the first step in reducing eutrophication of Dianchi Lake.     

底泥疏浚对磷形态和磷释放的影响

A laboratory experiment was carried out through a six-month incubation of undredged （control） and dredged cores to study the effect of sediment dredging on phosphorus （P） release from the sediment in the Taihu Lake. During the experiment, dredging the upper 30 cm layer could efficiently reduce the interstitial PO4^3-P concentration and different P forms in the sediment. The P fluxes of the undredged and dredged cores ranged from -5.1 to 3047.6 and -60.7 to 14.4μg·m^-2·d^-1, respectively. The fluxes of the dredged cores were generally lower than those of the control. Differences in the fluxes between the dredged and undredged cores were statistically significant （P 〈 0.05） from March to June 2006. The sediment P in the dredged cores had a lower release potential than that in the control. Dredging can be considered as a useful measure for rehabilitating the aquatic ecosystem after the external P loading in the Talhu Lake catchment was efficiently reduced.     

上海郊区河流沉积物N、P释放的初步研究

A laboratory study was conducted to observe the release of nitrogen and phosphorus from the sedimentsunder both anaerobic and aerobic conditions. The samples used were five creek sediments and a fish-pondsediment (as a comparison) obtained from suburban Shanghai. High loads of nitrogen and phosphoruswere found in the creek sediments. Total nitrogen of the sediments ranged from 1.17 to 5.95 g kg^-1; totalphosphorus from 608.63 to 2 033.95 mg kg^-1. Making up more than 90% of the total nitrogen, organicnitrogen was the dominant nitrogen fraction in the sediments; where as inorganic phosphorus was the dominant phosphorus fraction, which made up more than 85 percent of the total phosphorus. Cabound phosphorus fraction dominated inorganic phosphorus, which occupied more than 50% of the total. A large amount of ammonium was released from the sediments under both aerobic and anaerobic conditions, and the anaerobic releases were slightly greater than the aerobic. In addition, ammonium contents in the aerobic waters decreased sharply after reaching the peaks because of strong nitrification, compared with the relatively maintained ammonium peaks in the anaerobic waters. Anaerobic phosphate releases were much greater than the aerobic and the released ortho-phosphate was mainly from Fe-bound phosphorus. Ammonium and ortho-phosphate releases from the sample of the dredged creek were the lowest, showing that creek dredging could effectively remove contaminants from the surface of sediments and weaken the release potentials of nitrogen and phosphorus. Ammonium and ortho-phosphate releases from the fish-pond sediment were greater than those from the creek sediments though its total nitrogen and phosphorus were not the highest, which was probably due to the larger amount of biologically degraded organic matter in the fish-pond sediment.     

黄土高原土壤养分的损失

The soil nutrient losses due to excessive soil loss on Loess Plateau were studied by means of runoff plots and systematical determination of soil nutrients both in sediments and runoff.The results show that the amounts of nutrient losses depended on the amounts of ersoion sediments.Along with sediment,11-197kg nitrogen/hectare and 9-174kg phosphorus/hectare were lost,accounting for 92.46-99.47 percent of the total amount of nitrogen loss and 99.85-99.99 percent of the total amount of phosphorus loss respectively.The nutrient losses,very small in runoff,were mainly attributed to erosion of a few rainstorms during a year.The nutrient level in sediment was mostly higher than that in the original soil.Planting grass evidently redued the losses of soil nutrients.The N level was lower in runoff than in rainfall so that the N loss from runoff could be made up by rainfall.Fertilizer application to crops raised the nutrient level in runoff.     

再氧化对土壤的通气性变异的影响

The interplay between soil physical parameters during the recovery from anoxic stresses (reoxidation) is largely unrecognized. This study was conducted to characterise the soil aeration status and derive correlations between variable aeration factors during reoxidation. Surface layers (0-30 cm) of three soil types, Haplic Phaeozem, Mollic Gleysol, and Eutric Cambisol (FAO soil group), were selected for analysis. The moisture content was determined for a range of pF values (0, 1.5, 2.2, 2.7, and 3.2), corresponding to the available water for microorganisms and plant roots. The variability of a number of soil aeration parameters, such as water potential (pF), air-filled porosity (Eg), oxygen diffusion rate (ODR), and redox potential (Eh), were investigated. These parameters were found to be interrelated in most cases. There were significant (P < 0.001) negative correlations of pF, Eg, and ODR with Eh. A decrease in water content as a consequence of soil reoxidation was manifested by an increase in the values of aeration factors in the soil environment. These results contributed to understanding of soil redox processes during recovery from flooding and might be useful for development of agricultural techniques aiming at soil reoxidation and soil fertility optimisation.     

中国长江中下游地区浅水湖泊沉积物有机磷研究

Thirteen sediment core samples （0 10 cm） were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus （P） fractions in the sediments of the shallow lakes in the area. The organic P fractions in the sediments were in the order of moderately labile organic P （MLOP） 〉 moderately resistant organic P （MROP） 〉 highly resistant organic P （HROP） 〉 labile organic P （LOP）, with average proportional ratios of 13.2：2.8：1.3：1.0. LOP, MLOP, and MROP were significantly related to the contents of total organic carbon （TOC）, water-soluble P （WSP）, algal-available P （AAP）, NaHCO3-extractable P （Olsen-P）, total P （TP）, organic P （OP）, and inorganic P （IP）. However, HROP was significantly related to OP and weakly correlated with TOC, WSP, AAP, Olsen-P, TP or IP. This suggested that organic P, especially LOP and MLOP in sediments, deserved even greater attention than IP in regards to lake eutrophication. In terms of organic P, sediments were more hazardous than soils in lake eutrophication. Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment, LOP and MLOP were higher in the heavily polluted sediment, which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.     

太湖、巢湖、龙感湖沉积物中磷的地球化学形态

A sequential extraction method for the fractionation of phosphorus （P） in lake sediments was used to analyze phos- phorus fractions of sediments taken from three large, shallow. eutrophic freshwater lakes of China-Talhu Lake. Chaohu Lake, and Long.an Lake. All three lakes are located in the lower reaches of the Changjiang River （Yangtze River）. In Taihu Lake and Chaohu Lake, algae blooms occurred every year, while Longgan Lake was a macrophyte-dominated lake. Results showed that exchangeable phosphorus fractions were much higher in the eutrophic lake sediments than in the macrophyte-flourishing lake sediment. Also, the ratio of Fe：P in the sediments of the algae-predomlnant lakes was generally much lower than that in the macrophyte-predominant lakes. Thus, the geochemical fractions of phosphorus in sediments had a closer relationship with the type of aquatic vegetation.     

Variations of Phosphorus Release from Sediments in Stratified Lakes

The aim of this investigation was to study the temporal variation in phosphorus release from the sediments and its influence on water quality of stratified lakes. The concentrations of soluble reactive phosphorus (SRP), calcium and sulfate in the interstitial water and the pH in the wet sediments of dimictic lakes were investigated during the spring circulation and at the end of summer stratification. Multiple regression analysis using the calculated diffusive fluxes of SRP out of the sediments and the morphometric characteristics of the lakes (reduced water depth), explained 73 % of the variance of the SRP-accumulation in the hypolimnia during summer stagnation. At the end of surnmer stratification diffusive fluxes of SRP out of the sediments increased and pH-values and sulfate-concentrations decreased at the sediment surface (0–2 em) and in the hypolimnia. The maximum diffusive flux of SRP was calculated to be 5.8 mg/m²/d at the end of summer stagnation. Prob able reasons for these higher diffusive fluxes of SRP at the end of summer stagnation are higher supply of labile organic matter and thereby higher mineralization rates. lower redox potential and thus higher dissolution of redox sensitive P-binding forms and/or dissolution of phosphorus being bound to Ca-phases at lower pH.     

达里诺尔湖磷赋存特征及底泥释放影响因素

[目的]揭示封闭性内陆湖磷组成特点及底泥释放影响因素,为控制达里湖磷元素污染提供理论支持。[方法]对达里诺尔湖水体总磷(TP)、溶解性总磷(DTP)、溶解性无机磷(DIP),沉积物形态磷进行监测,并利用因子分析的方法对影响沉积物底泥释放的因素分类讨论。[结果]达里湖上覆水总磷(TP)均值2.00±0.02mg/L,间隙水TP均值2.50±0.02mg/L,沉积物TP在206.09~940.49mg/kg之间。沉积物中无机磷(IP)占TP的47.9%,是沉积物主要的磷形态之一。钙磷(Ca-P)是IP中含量最多的形态磷(217.76±47.01mg/kg),其次为铁铝结合态磷(Fe/Al-P,62.73±28.34mg/kg)和交换态磷(Ex-P,36.50±19.13mg/kg),有机磷(OP,200.28±135.13mg/kg)含量占TP的41.8%;通过因子分析法将影响底泥释放的因素分为三类:沉积物TP,Ca-P,Fe/Al-P和生物有效性磷含量归为沉积物磷因子;水体pH,DO,Eh值以及间隙水磷含量归为界面影响因子;湖水水深归为湖泊自身特征因子。[结论]达里湖存在沉积物磷底泥释放的风险,根据因子分析的结果可知,影响沉积物底泥释放的因素分为沉积物磷、水—沉积物界面理化指标和湖水水深3大类。     

沉积物中核酸态有机磷及其矿化过程研究

水体沉积物界面中磷的释放机制非常复杂,生物作用导致的pH值和氧化还原条件变化对湖泊沉积物矿化能力有显著影响。普遍认为沉积物中有机磷的矿化过程是对水体富营养化具有重要贡献的环节之一,而核酸态有机磷可从一定程度上表征微生物水平,反应微生物对矿化作用的影响。据此采用DNA提取的方法对沉积物中核酸态有机磷的含量进行测定,并模拟沉积物中核酸在不同pH和溶解氧条件下的矿化过程。结果表明,DNA提取方法可以快速、准确提取沉积物中核酸磷;沉积物中核酸磷含量为0．43～0．61μg·g^-1,占有机磷总量的0．27％～0．37％,精确度为1．58％～3．63％。模拟实验结果表明,在两种情况下上覆水中总磷浓度均呈波动式上升,在pH接近7时沉积物中核酸磷较低,有氧条件下核酸磷呈下降趋势。     

巢湖沉积物磷的形态及其与间隙水磷的关系

采用磷形态的连续提取法,研究了巢湖沉积物中磷的地球化学形态及间隙水中总溶解性磷（DTP）、可溶性磷酸盐（DIP）、可溶性有机磷（DOP）含量的垂向分布特征。结果表明,西湖区的沉积物总磷含量明显高于东湖区。表层沉积物中活性磷含量占总磷的44％-81％,金属氧化物结合态磷（NaOH—P）作为活性磷的主要存在形式,在西湖区含量比例达到47％-60％,对磷释放起重要贡献;磷形态剖面表明,西湖区的金属氧化物结合态磷、可还原态磷（BD—P）含量高于东湖区。金属氧化物结合态磷、可还原态磷、钙结合态磷（HCl-P）受人类活动影响较大,有机磷（Org—P）受外源磷污染影响很小;BD—P、NaOH—P随深度增加而减小,说明巢湖近期磷负荷有增加的趋势;DTP、DIP、DOP在水-沉积物界面的浓度梯度反映它们有自间隙水向上覆水扩散的趋势;巢湖间隙水不同形态磷与BD—P、NaOH—P显著相关（α=0．01）。这项研究可为巢湖内源污染和富营养化的控制与治理提供理论参考。     

扰动强化河道底泥对磷持留能力的研究

以城市河道上覆水和底泥为材料,研究了扰动对底泥持留磷能力的强化作用,并分析了强化机理。结果表明,底泥扰动促进了上覆水中磷向底泥中迁移。与对照试验相比,溶解性磷酸盐（DIP）和总磷（TP）平衡浓度分别降低了73．02％和42．39％;与原底泥相比,扰动试验底泥中溶解性磷酸盐（DIP）的释放量降低了173．77mg·kg^-1,对照试验底泥中DIP的释放量基本保持一致。另外,底泥扰动后,钙结合态磷（Ca—P）含量显著增加,并接近总磷的增加量;而对照试验底泥中,总磷的净增加量比较均匀地分配到弱吸附态磷（NH4Cl-P）、铁结合态磷（Fe—P）、钙结合态磷（Ca—P）中。     

Factors Regulating the Flux of Phosphate at the Sediment - Water Interface of a Subtropical Calcareous Lake: a Simulation Study with Intact Sediment Cores

Different factors which interactively control the flux of soluble reactive phosphorus (SRP) at the sediment water irterface (SWI) of Lake Kinneret were studied seasonally. The influence of pH, Eh and microbial activity on SRP flux at the SWI was investigated by manipulating the conditions in the overlying water of intact sediment cores. The calculated diffusive SRP flux out of the sediment was lower in cores sampled during winter and spring than during the period of amixis. Potential SRP release, as measured in the absence of microbial activity, was strongly enhanced upon the transition from oxic to anoxic conditions indicating P release from iron(III)-bound phosphorus. In spring and summer cores, an enhanced SRP flux from sediments at pH 7 in comparison to pH 8 indicated P release from carbonate-bound P which sedimented previously as result of high pH values during the algal spring bloom. Microbial uptake at the SWI was the most important sink for SRP and no net-flux occured under oxic conditions. The higher net-flux of P under anoxic conditions was linked to carbon limitation ofthe bacteria at the SWI.     

混养鱼塘水中磷含量及表层沉积物中磷赋存形态的初步探究

为更好地揭示养殖系统的磷收支和污染程度,以上海郊区3口团头鲂（Megalobrama amblycephala）混养鱼塘即池塘A、B、C以及水源D为研究对象,定期测定养殖期间水体中总磷（TP）、活性磷酸盐（PO4-P）以及沉积物中总磷的含量,并探究沉积物中不同形态磷,包括交换态磷（Ex-P）、铝结合磷（Al-P）、铁结合磷（Fe-P）、闭蓄态磷（Oc-P）、原生碎屑磷（De-P）、钙结合磷（Ca-P）和有机磷（Or-P）的分布变化特征。试验发现,该养殖场水源水TP（0.17±0.06）mg·L－1及PO4-P（0.11±0.06）mg·L－1含量一直维持在稳定的较低水平,养殖生产导致池塘A、B、C水中TP大大增加,已超过地表水Ⅲ类标准和淡水养殖池塘排放标准（Ⅱ类）。养殖池塘及水源沉积物中TP浓度分别是（0.69±0.04）、（0.70±0.07）、（0.68±0.09）、（0.79±0.13）mg·g－1,池塘表层沉积物中TP含量变化不大,而水源沉积物TP变化波动性明显。池塘表层沉积物中磷主要由Fe-P（18.03±6.01）%、Oc-P（22.82±5.34）%、Ca-P（27.48±8.15）%和Or-P（20.29±6.60）%组成,Ex-P（3.07±1.06）%、Al-P（7.62±3.11）%,尤其是De-P（0.69±0.35）%