长寿湖表层沉积物氮磷和有机质污染特征及评价

测定了重庆市长寿湖62个采样点表层沉积物中总氮(TN)、总磷(TP)及有机质(OM)的含量,并与国内其他城市(郊)湖库进行比较,以揭示其空间分布特征,分析了TN、TP、OM间相关性及C/N变化.结果表明,TN平均含量2 255.89 mg.kg-1,TP平均含量622.03 mg.kg-1,湖区氮磷污染严重且空间分布差异明显.OM含量平均2.80%,与其他湖库相比,TN、TP及OM含量均处于中间水平.C/N的87.10%介于5～14间(其中72.58%同样介于6～13间),3.23%介于2.8～3.4间,表明长寿湖表层沉积物中OM多源于湖中藻类及浮游动植物,还有少部分源于水生生物.OM与TN间极显著相关(Pearson系数为0.849),含量均为西部与中部水体高于东部水体,分布特征相似,但OM与TP相关性较小.通过有机指数与有机氮评价湖区污染情况,表明有机指数平均值为0.386,处于Ⅲ级,属尚清洁范畴;有机氮平均值为0.214%,达Ⅳ级,属有机氮污染程度,说明长寿湖受氮污染情况相对严重.

Pollution Characteristics and Evaluation of Nitrogen, Phosphorus and Organic Matter in Surface Sediments of Lake Changshouhu in Chongqing, China

In order to reveal spatial distribution characteristics of nutrient in the surface sediments of Lake Changshouhu, contents of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) of 62 surface sediments samples were determined and compared with other urban (suburban) lakes in China. C/N and the correlation of TN, TP and OM had also been analyzed. The results showed that the average contents of TN and TP were 2 255.89 mg x kg(-1) and 622.03 mg x kg(-1) respectively. Nitrogen and phosphorus pollution were very serious all over the lake, with a significantly different spatial distribution. The average content of OM was 2.80%. So the contents of TN, TP and OM were in the middle level compared with other lakes. 87.10% of C/N was between 5 and 14 (72.58% within which was between 6 and 13) and 3.23% of C/N was between 2.8 and 3.4, which showed that OM came from algae, phytoplankton and zooplankton. Besides, a small part of OM came from aquatic organisms. OM and TN were significantly correlated (Pearson coefficient was 0.849), but with less significant correlation to TP. The spatial distribution characteristics of OM were very similar with that of TN. The content of OM in water samples collected from western and middle waterbody was higher than that in eastern waterbody, which was the same as TN. By evaluating pollution situation with organic index and organic nitrogen, the average organic index was 0.386 which was on the III level still belonged to clean category. However, the average number of organic nitrogen was up to 0.214% which was on the IV level indicated the pollution degree. This showed that the lake Changshouhu was in a serious pollution situation especially in nitrogen pollution.