太湖草/藻型湖区沉积物-水界面环境特征差异

Environmental characteristics of sediment-water interface of phytoplankton and macrophyte dominated zones in Lake Taihu

在太湖草、藻型湖区进行冬、夏两季多点采样,分别对采样点的水环境特征、泥面以上5 cm上覆水中营养盐以及沉积物的含水量、中值粒径、有机碳、氮、磷、金属元素和溶解氧进行测定.结果表明:夏季藻型湖区表层水体pH高于中、底层,冬季草型湖区各层水体pH高于藻型;草型湖区水体浊度夏季低于藻型,冬季反之;藻型湖区上覆水中的硝态氮和磷酸根浓度显著高于草型;草型湖区沉积物中含水量冬季显著高于夏季;草型湖区沉积物中总有机碳显著高于藻型;Fe、Zn、Ca、Pb、Na和K等元素在草、藻型湖区间差异显著;沉积物中溶解氧表现为冬季深于夏季,藻型深于草型的规律.

The investigation was conducted within large, shallow Lake Taihu, in winter and summer. 5 sites in phytoplankton dom- inated zone and 3 sites in macrophyte dominated zone were chosen for sampling. Parameters of sampling sites including water quali- ty, nutrients concentrations in 5-cm overlaying water and vertical profiles of water content, mean value of grain size （ D50）, total organic carbon （TOC）, nitrogen, phosphorus, metals and dissolved oxygen were analyzed. Results showed that, surface water pH in phytoplankton dominated zone was higher than that in the other two layers and water pH in winter was higher in macrophyte dom- inated zone than that in phytoplankton dominated zone ; water nephelometric turbidity unites in macrophyte dominatd zone was high- er than those in phytoplankton dominated zone in summer and contrarily in winter; concentrations of NO3- -N and PO3 -P of overla- ying water were significantly higher in phytoplankton dominated zone than those in macrophyte dominated zone; sediment water contents in macrophyte dominated zone in winter was significant higher than those in summer; sediment TOC in macrophyte domi- nated zone was significant higher than thai in phytoplankton dominated zone. Tbcl＇e was significant difference of sediment metal concentration, including Fe, Zn, Ca, Pb, Na and K between macrophytc and phytoplankton dominated zone; oxygen penetration depths were deeper in winter than those in summer, and in phytoplankton dominated zone than in macrophyte dominated zone.