粤西海域表层沉积物生源要素分布与污染评价

Distribution of biogenic elements and potential contamination assessment in surface sediments from western Guangdong coasts

采集2006年7月至2007年11月中国粤西海陵湾、水东港、雷州湾和流沙湾表层沉积物,分析沉积物中生物硅(biogenic silica,BSi)、总有机碳(total organic carbon,TOC)、总氮(total nitrogen,TN)和总磷(total phosphorus,TP)4种生源要素含量.结果表明,粤西海域生源要素含量与国内外港湾相比属中等水平,整体来说夏季各种生源要素含量较高,BSi、TOC、TN和TP的平均质量分数分别为0.27%、0.90%、0.27%和0.027%,冬季BSi、TOC、TN和TP的平均质量分数分别为0.24%、0.67%、0.06%和0.022%.沉积物中TOC/TN值表明,海陵湾、水东港和雷州湾的TOC主要来源于水生,流沙湾TOC主要源自陆源.BSi的含量在春夏秋3个季节均较高,反映了较高的硅藻生产力;而夏季丰富的TOC、TN和TP含量则反映了夏季较高的初级生产力和大量陆源输入.生源要素污染评价表明,4个港湾中,TOC除流沙湾属Ⅱ类污染,其余3个港湾属于Ⅰ类污染;TP均属于Ⅰ类污染;而TN均属于Ⅱ类污染.

The concentrations of four types of biogenic elements, biogenic silica （BSi）, total organic carbon （TOC）, total nitrogen （TN） and total phosphorus （TP）, were determined in surface sediments collected from western Guangdong coasts between July 2006 and November 2007. Results showed that concentrations of biogenic elements from Guangdong Western Coasts were within moderate levels compared with those from other coastal areas in the world. BSi, TOC, TN, and TP contents were in average levels of 0. 27%, 0. 90%, 0. 27% and 0. 027% in summer, and were 0. 24%, 0. 67%, 0. 06% and 0. 022% in winter respectively. From the TOC/TN ratios, it is suggested marine origin of TOC in Hailing Bay, Shuidong Harbor and Leizhou Bay, and terrestrial origin of TOC in Liusha Bay. BSi contents were high in three seasons except for the winter, displaying the higher diatom production.Higher TOC, TN and TP concentrations in summer represented sufficient inputs from runoff in flood season. Contamination assessment of biogenie elements indicated that TOC and TP in most samples belonged to Class Ⅰ pollution, TN belonged to Class Ⅱ pollution. Samples indicated some toxicity effects on benthos.