太湖北部蓝藻集聚区水体富营养化时空变化研究

Study on temporal and spatial changes of water eutrophication in cyanobacteria accumulation area of Taihu Lake

于2016—2018年对太湖北部蓝藻集聚区(竺山湾、梅梁湾)以及竺山湾的湖滨带开展水体与沉积物的营养盐状态研究。结果表明,梅梁湾水体中TN年际变化较大,TP年际变化相对较小;沉积物中TN及高锰酸盐指数等均呈现出湖岸边际效应及明显的年际变化,TP的年际差别不显著。太湖湾水体不同点位及时间的叶绿素a(Chl-a)波动范围较大,Chl-a总体与TN呈正相关,与溶解性无机氮(DIN)呈负相关。综合评价认为,太湖湾水体表现为轻度富营养化,沉积物均表现为有机氮污染,且污染物分布区域性较强。潜在性富营养评价结果表明,太湖湾水体为磷限制潜在性富营养状态。竺山湾的水体和沉积物中磷的矿化时间分别为96、235 min左右,水体中磷的矿化速率比沉积物中的矿化速率快。

The nutrient status of water body and surface sediment in cyanobacteria accumulation area of northernTaihu Lake(Zhushan Bay and Meiliang Bay)and the coastal zone of Zhushan Bay were studied during 2016-2018.The results showed that the interannual variation of TN in Meiliang Bay was larger,while that of TP was relatively smaller.TN and permanganate index in the sediment showed lakeshore marginal effect and obvious interannual variation,while TP showed no significant interannual difference.The Chl-a had a large fluctuation range at different points and times in Taihu Bay.The Chl-a was positively correlated with TN and negatively correlated with dissolved inorganic nitrogen(DIN).The comprehensive evaluation suggested that the water bodies in Taihu Bay were slightly eutrophic,and the sediments were evaluated as organic nitrogen pollution,with strong regional distribution of pollutants.The potential eutrophication assessment showed that the water bodies of Taihu Bay were in phosphorus limited potential eutrophication state.The mineralization time of phosphorus in the water body and sediment of Zhushan Bay was about 96 min and 235 min,respectively.The mineralization rate of phosphorus in the water body was faster than that in the sediment.