流沙湾表层沉积物中碳、氮、磷的分布特征和污染评价

2012年5月至2013年1月，每季度在流沙湾内湾养殖区、外湾养殖区和外湾非养殖区采集沉积物和水质样品，测定沉积物的总有机碳（TOC）、总氮（TN）和总磷（TP）质量分数，以及底层水溶解氧（DO）和水温（T），结合水动力分析，研究其表层沉积物中富营养物质碳（ C）、氮（N）、磷（P）的分布特征和受污染程度。结果表明，流沙湾的物理地形决定了湾内流场水流缓慢、内外湾之间水交换过程缓慢的固有特征。底层水 DO 自春季开始逐步升高，冬季达到最大值。内湾养殖区的底层水 DO 均值低于外湾。表层沉积物 TOC 和 TP 质量分数没有明显的季节差异，但 TN 质量分数在春、夏季明显高于秋、冬季。养殖区的 TOC、TN 质量分数均显著高于非养殖区，且以内湾养殖区最高，其 TP 空间差异不显著。流沙湾表层沉积物 TOC 年平均有机碳污染指数为1.29，TN污染指数达2.98，而 TP 磷污染指数仅为0.92，表明该海域已受到中等水平的氮污染和低水平的有机碳污染，且现有养殖格局加速了养殖区的富营养物质沉积。

Distribution characteristics of C,N and P in Liusha Bay surface sediment and their pollution assessment

We collected the sediment and water samples from breeding areas,farming areas and non-farming areas outside Liusha Bay quar-terly during May,2012 to January,2013,and determined the total organic carbon（TOC）,total nitrogen（TN）and total phosphorus（TP） content in the sediment,as well as dissolved oxygen（DO）and temperature（T）in the bottom water,hydrodynamically analyzing the distri-bution characteristics of C,N,P and their pollution. The results indicate that the physical terrain of Liusha Bay determined the slow flow of water inside the bay and the slow water exchange between inner and outer parts of the bay. The DO in bottom water significantly rose from spring to winter and reached the maximum. The DO in bottom water in inner bay was lower than that in outer bay. The TOC and TP contents in surface sediment had no significant seasonal changes,but the TN contents in spring and summer were obviously higher than those in au-tumn and winter. The TOC and TN contents in the sediment of the breeding areas were significantly higher than those in the non-breeding ar-ea,being the highest in the inner bay. The TP content showed no significant time and spatial difference. The annual average pollution indi-ces for TOC,TN and TP were 1. 29,2. 98 and 0. 92,respectively,which indicated that the bay had suffered medium organic carbon pollu-tion and low nitrogen pollution,and current aquaculture status had significantly accelerated eutrophic sedimentation in Liusha Bay.