九龙江近岸表层沉积物重金属污染评价及来源解析

Pollution assessment and source analysis of heavy metals in offshore surface sediments from Jiulong River

采用电感耦合等离子体质谱法(ICP-MS)、原子荧光光谱法(AFS)和原子吸收光谱法(AAS)分析测定了九龙江39个近岸表层沉积物中26种重金属的含量,运用地质累积指数法和潜在生态风险指数法评价重金属污染特征及潜在生态风险,并运用多元统计方法进行源解析.研究结果表明:各金属在九龙江不同区域(北溪、西溪和河口)分布存在差异,其中Mn、Zn、Cd、Mo、Sb、Cs、Y、Th和U元素的高含量出现在北溪和西溪,Fe、Ni、Cr、V、Co、Sc、Li、Rb、Sr、Tl和Ga元素的高含量出现在河口区域.大部分金属已存在一定程度的富集.地质累积指数法表明Cd的污染程度最高,10.3%的采样点达严重污染.10种重金属的潜在生态风险程度顺序为Cd>Hg>Cu>Pb>Ni>Co>Cr>Mn>Zn>V,Cd和Hg对综合潜在生态风险的贡献最大,分别为78.1%和12.1%.多元统计分析结果表明,九龙江近岸表层沉积物中,Fe、Mn、Zn、Pb、Cu、Cr、Cd、Hg、Mo、Sb和Bi元素主要来源于农业生产活动和采矿活动;Ni、Co、Sc、Li、Rb、Sr、Be、Ga和Tl元素主要来源于化石燃料燃烧释放;Ba、Y、V、Th、U和Cs元素主要来源于流域花岗岩等岩石风化.

Contents of 26 heavy metals in the 39 offshore surface sediments of Jiulong River were determined by inductively coupled plasma mass spectrometry（ICP-MS）, atomic fluorescence spectrometry（AFS） and atomic absorption spectrometry（AAS）. Geo-accumulation index and potential ecological risk index were applied to evaluate the pollution degree and potential ecological risk of heavy metals, and multivariate statistical methods were applied to speculate the main sources of these heavy metals. The results showed that the distributions of heavy metals were different in three regions of Jiulong River（north creek, western creek and estuary）, the high contents of Mn, Zn, Cd, Mo, Sb, Cs, Y, Th and U elements appeared in the north creek and western creek, and the high contents of Fe, Ni, Cr, V, Co, Sc, Li, Rb, Sr, Tl and Ga elements appeared in the estuary. Most of these elements were enriched in the sediments. The results of pollution assessment by geo-accumulation index revealed that the pollution degree of Cd was the highest and at a serious polluted level in 10.3% of the samplings. The assessment results of potential ecological risk indicated that the potential ecological risk of heavy metals showed the order of CdHgCuPbNiCoCrMnZnV. Cd and Hg contributed the most to the total potential ecological risk, accounting for 78.1% and 12.1%, respectively. The results of multivariate statistics analysis indicated that the source of Fe, Mn, Zn, Pb, Cu, Cr, Cd, Hg, Mo, Sb and Bi were mainly from agricultural activities and mining activities; the source of Ni, Co, Sc, Li, Rb, Sr, Be, Ga and Tl were mainly from burning fossil fuels; and the source of Ba, Y, V, Th, U and Cs were mainly from the rock weathering of granite.