外源硫酸盐对武汉南湖表层沉积物磷形态的作用

Effect of external sulfate on fraction of phosphorus in the surface sediment from Lake Nanhu in Wuhan

采用室内模拟实验,选取武汉市南湖表层沉积物及相应上覆水,研究了硫酸盐的输入对沉积物磷形态的影响.结果表明,硫酸盐输入水体后提高了沉积物磷的迁移活性,导致上覆水中总磷(TP)、溶解性正磷酸盐(SRP)含量升高,上升幅度随硫酸盐输入量的增加而增加.硫酸盐扩散到沉积物后,先是生成酸可挥发性硫(AVS),进而转变成铬还原硫.硫酸盐输入提高了沉积物pH值,而使Eh降低.沉积物不同磷形态对外源硫酸盐的响应有所差异,二钙磷(Ca2-P)含量随输入硫酸盐浓度的增加而增加,含量最高的铁磷(Fe-P)为800mg/kg左右,占总磷的51.4%～56.6%,受硫酸盐的影响极显著(P<0.01),在沉积物中含量降低而向上覆水中释放.上覆水中溶解性铁和TP、SRP均呈显著正相关.硫酸盐对沉积物中闭蓄态铁磷(O-Fe-P)也产生显著影响(P<0.05),总体而言是促进其释放.

The response of phosphorus fraction in the sediments from Lake Nanhu in Wuhan to the input of sulfate was investigated based on the indoor simulation experiments.It showed that sulfate input improved the mobility of phosphorus in sediments,resulting in the increase of concentrations of total phosphorus（TP） and soluble reactive phosphorus（SRP） in the overlying water.Higher external sulfate concentration experienced greater increase of phosphorus contents in the overlying water.The contents of acid volatile sulfur（AVS） in the sediments initially increased and then fell,while the chromium reducible sulfur kept the trend of increase.It indicated that the AVS in the sediments was produced after the sulfate penetrated to the sediments,followed by the transformation of AVS to chromium reducible sulfur.pH increased and Eh decreased due to the reduction of sulfate in the sediments.The effect of sulfate input was much different for the different fractions of phosphorus in the sediments.The contents of Ca2-P increased with the increase of sulfate concentration.The Fe-P with the highest content in the sediments（51.4%~56.6 % of total phosphorus）,was significantly influenced by the sulfate（P0.01）.It released from sediments to overlying water,and the soluble iron in the overlying water had positive correlation with the TP and SRP.The O-Fe-P was also affected by the external sulfate and showed release mobility from the sediments.