大明湖主要营养元素内外源负荷的分析与评价

Analysis and Assessment on Main Nutritious Elements from Inner and Exterior Contamination in Daming Lake

通过引入泉水置换大明湖1/2湖水,分析、评价换水后大明湖水质的季节变化特征,主要营养元素的内、外源负荷,考察大明湖中叶绿素a(Chl.a)、总氮(TN)、总磷(TP)和化学需氧量(CODcr)随季节变化的规律。结果表明:换水后大明湖水质出现短期改善,半年后又退回到富营养化状态;截外源污水不彻底导致湖体内主要营养盐逐渐累积;每年磷(P)累积量约为882 kg、氮(N)累积量约为5 483 kg;疏松沉积物积累约为8.06×107kg,测得沉积物富含营养元素P约为1.30×105kg,N约为1.90×105kg,湖水中的P、N的量分别仅占湖泊系统TP、TN的0.23%和2.29%,内源沉积物是影响水质的另一重要因素。

Characteristics of the water quality together with main nutritious elements from inner and exterior contamination in Daming Lake with seasonal variation are analyzed and evaluated since one half of the water in Daming Lake is replaced by spring water.What is more,transformation characteristics of Chl.a,TN,TP and CODcr are investigated with seasonal variation.The results show that the water quality is kept well in a short time and deterioration appeares after one half of a year;the exterior contamination leads to the accumulation of main nutrition;every year,about 882 kg phosphorus,5 483 kg nitrogen,and about 8.06×107 kg sediment are accumulated in the lake,and about 1.30×105 kg phosphorus and 1.90×105 kg nitrogen in the sediment are determined.The quantity of phosphorus and nitrogen containing in the water system is only about 0.24% and 2.29%,partly of the whole lake system,which means that inner sediment is an important factor to the water quality.