光度法研究太湖表层沉积物中磷形态分布及动力学特征

表层沉积物是水体污染物的源和汇。研究表明，太湖地区特别是梅梁湾和东太湖表层沉积物中磷等营养元素污染严重。采用SMT法(standards measurements and testing)和钼锑抗分光光度法对太湖18个采样点表层沉积物样品进行前处理和磷形态分析，结合我国、加拿大和美国标准对总磷进行污染评价。通过拟合建立了吸附-解吸动力学特征方程，并在不同pH、水土比的环境条件下获得磷的吸附特性。同时也在不同温度和pH下对磷进行解吸特征研究。结果表明： S₉采样点总磷、无机磷、有机磷和酸磷含量均最高，S₁₁采样点碱磷含量最高。对于所有采样点，各形态磷平均值大小排序为(μg·g-1)： 无机磷(401.43)>酸磷(377.81)>有机磷(175.37)>碱磷(25.53)。污染评价结果表明： 除S₁₂，S₁₄~S₁₆及S₁₈采样点外，其余采样点均有不同程度的污染。表层沉积物对磷的吸附-解吸过程均符合伪二级动力学方程。吸附过程最佳水土比为25∶1，且pH值对吸附和解吸有不同程度的影响。研究结果为掌握太湖梅梁湾和东太湖区域磷的污染现状提供理论依据，同时为研究磷在沉积物-水界面的迁移规律提供可信的实验数据。

Distribution of Phosphorus Fractions and Kinetics Characteristics in Surface Sediments of Taihu Lake by Using Spectrophotometry

The surface sediments are the source and sink of many pollutants of water. Studies have shown that phosphorus and other nutrient elements in surface sediments of Taihu Lake area, specially in Meiliang Bay and East Taihu Lake, are seriously polluted.SMT method (Standards Measurements and Testing) and molybdenum antimony anti-spectrophotometry were used to pretreat and analyze phosphorus of the 18 surface sediment samples in Taihu Lake, China, and the total phosphorus pollution was evaluated in comparison with the standards of China, Canada and the United States, respectively. Moreover, the adsorption and desorption kinetics equations were established by linear fitting, the adsorption characteristics of phosphorus under different pH and soil/water ratio were obtained. And we also studied the desorption characteristics of phosphorus under different temperature and pH conditions. The results showed that the highest contents of total phosphorus, inorganic phosphorus, organic phosphorus and acid phosphorus all appeared in S₉ sampling sites, the highest content of alkali phosphorus was found in S₁₁ sampling site. For all sampling sites, the order of average contentof each fraction phosphorus was (μg·g-1): inorganic phosphorus (401.43)>acid phosphorus (377.81)>organic phosphorus (175.37)>alkali phosphorus (25.53). The results of pollution evaluation showed that except for S₁₂，S₁₄~S₁₆ and S₁₈, other sampling sites suffered varying degrees of contamination. Both adsorption and desorption processes of phosphorus on the surface sediments followed the pseudo-second-order kinetics equation. The optimum soil/water ratio was 25∶1. The pH had different effects on adsorption and desorption, respectively. The results provided not only a theoretical basis for governing the phosphorus pollution but also credible experimental data for studying the migration of phosphorus at the sediment-water interface in Meiliang Bay and Taihu Lake.