富营养湖泊沉积物中磷组分对硫酸盐的响应

采用室内模拟实验于厌氧条件下持续6周,研究不同外源硫酸盐浓度下南湖沉积物和上覆水之间的硫酸盐转化及还原情况,采用31P核磁共振(31P-NMR)研究沉积物磷组分所受影响.结果表明,硫酸盐输入促进了上覆水中pH值的升高,而氧化还原电位则呈相反的变化趋势.上覆水中SO24-浓度随时间推移而降低,但间隙水中SO24-浓度的增加幅度并不与上覆水中降低幅度一致,表明沉积物中SO24-发生了转化.沉积物的硫酸盐还原指数随SO24-输入浓度的增大而增加,沉积物中硫酸盐还原菌(SRB)的数量在第2周达到峰值,输入硫酸盐的S500和S1000处理中SRB数量远远高于未加硫酸盐的对照(CK).利用31P-NMR测定了南湖沉积物NaOH-EDTA萃取物中各种磷化合物的相对含量,南湖沉积物中的磷组分主要有正磷酸盐、磷酸单酯、磷酸二酯和焦磷酸盐,且正磷酸盐含量占绝对优势(占总磷的84.10%～95.54%),沉积物中其它磷组分含量顺序为磷酸单酯>磷酸二酯>焦磷酸盐.从总趋势来看,硫酸盐促进了沉积物中正磷酸盐的释放,且在硫酸盐还原菌数量较高时使沉积物中磷酸单酯、磷酸二酯和焦磷酸盐含量增加.

Response of Phosphorus Components in Sediments from Eutrophic Lake to External Sulfate

A six week experiment under indoor simulated condition was carried out to investigate the external sulfate transformation between the sediments and overlying water from Lake Nanhu in Wuhan, China, and the influence of sulfate on the phosphorus components was also studied. The results showed that the sulfate input increased the pH and lowered the Eh in the overlying water. The sulfate concentration in the overlying water decreased with time, and it was assumed that there existed an obvious transformation of sulfate to other forms of sulfur compounds according to the variation of sulfate concentration in the pore water. The sulfate reduction index increased with higher input content of sulfate. The amount of sulfate reducing bacteria (SRB) in the sediments achieved the peak value in the second week, and the SRB amounts of S500 and S1000 were much higher than that of the control.³¹ P-NMR was used to characterize the relative quantity of phosphorus compounds in the sediment extracts leached by NaOH-EDTA. The components of phosphorus in Nanhu Lake sediment were mainly orthophosphate, phosphate monoester, phosphodiester and pyrophosphate. The predominant one was orthophosphate (84.10%-95.54% of total phosphorus). The contents of other phosphorus components were followed: phosphate monoester>phosphodiester>pyrophosphate, and they increased due to the input of sulfate during the first four weeks, and decreased in the last two weeks. The external sulfate accelerated the release of orthophosphate from sediments to overlying water in a whole, and increased the contents of phosphate monoester, phosphodiester and pyrophosphate in sediments when the amounts of sulfate reducing bacteria were high.