扎龙湿地表层沉积物营养盐空间分布特征及评价

对扎龙湿地271 个采样点表层沉积物中总氮(TN)、总有机碳(TOC)和总磷(TP)进行了测定,分析了其空间分布特征,评价了其污染水平,并进一步探讨了沉积物碳-氮、碳-磷的耦合关系,揭示其污染来源。结果表明,TOC、TN及TP的平均值分别为21 047.2、1 961.9 和404.4 mg·kg^-1,含量分布存在明显的差异性。从空间分布格局上看,扎龙湿地表层沉积物中营养盐含量北部高于南部,西部高于东部,TOC和TN高值区位于西南,TP的高值区位于东北和西南。表层沉积物中TOC、TN和TP的富集系数平均值分别为2.3、6.7 和1.3,富集程度顺序为TN>TOC>TP;TOC、TN和TP 的污染指数平均值分别为2.1、3.6 和0.7,表明沉积物已经受到污染,但绝大部分仍属于多数底栖生物可承受的污染水平。扎龙湿地表层沉积物C/N平均值为11,表明沉积物中的有机质具有明显的双重来源,其中陆源有机质主要集中在北部、东部,其次为西部;C/P值高于C/N值,沉积物中的有机质主导着C/P值的变化趋势。

Spatial Distribution and Evaluation of Nutrients in Surface Sediments of Zhalong Wetland

A total of 271 sediments samples from Zhalong Wetland were analyzed for concentration and distribution of nutrients (TOC, TN and TP). It was followed by the evaluation of their pollution level. Then the linkages of C/N and C/P were discussed so as to find out the pollution sources. The results can be summarized as follows: The average values of TOC, TN and TP were 21047.2, 1961.9 and 404.4 mg·kg^-1 respectively. Their spatial distributions were distinctly different. The concentration of nutritive salt in the north was higher than that in the south and the west was higher than the east. In southwest, the values of TOC and TN were relatively high, and in northeast and southwest, the value of TP was high. The average accumulation indexes of TOC, TN and TP were 2.3, 6.7 and 1.3 respectively with the sequence of TN>TOC>TP. The average pollution index of TOC, TN and TP were 2.1, 3.6 and 0.7, meaning that the sediments had been polluted, but still within the standing point for most benthos. The average value of C/N was 11, indicating that the organic matter in sediments had double sources. The organic matter was mainly distributed in the north and east, followed by the west. The value of C/P was higher than that of C/N. The organic matter in sediments dominated the change of C/P value.