北部湾沉积物中重金属元素的地球化学特征及物源初探

The geochemical characteristics and the source of heavy metals in sediment for the Beibu Gulf

本文根据北部湾沉积物岩心样调查结果计算了铜、铅、锌、镉、汞、砷等重金属元素的背景值,并分析了其与南海陆架区和南海全海域沉积物背景值、广西土壤背景值之间的差异。对北部湾表层沉积物中重金属含量及近10a的变化趋势以及岩心样中重金属元素含量近百年以来的变化趋势综合分析结果表明:北部湾近岸海域沉积物中铜、砷、汞、镉重金属元素含量总体呈增长趋势,北部湾中部海域沉积物中重金属元素含量的年际变化有升有降,至湾口处沉积物中重金属元素的含量基本不变。综合评价结果表明,北部湾近岸沉积物中砷、汞、镉等重金属元素的地球化学特征明显受到广西人类活动的影响。北部湾沉积物中的重金属元素主要来源于人类活动影响下的广西沿岸陆源输入,经由琼州海峡的外部海域物质输入也有贡献。

The environmental background values for Cu, Zn, As, Pb, Hg, Cd in the Beibu Gulf are measured by the investigation data obtained in 2007, and their difference from background values of the South China Sea and terrigenous soil are also studied. The trend analysis of heavy metal contents in surface sediments and core sediments in the Beibu Gulf shows that in recent 100 a, the contents of Cu, As, Hg and Cd in coastal sediments are basically increasing; the trends in the middle of the Beibu Gulf are complicated; heavy metal contents in the sediments of the mouth of the gulf are stable. According to the distribution and trends of the heavy metal contents in sediments, it is qualitatively concluded that the environmental behaviors of heavy metals in the Beibu Gulf are affected by the human activity in Guangxi coastal areas, among which Cd, Hg, As are deeply affected. The main sources of heavy metals in the Beibu Gulf are terrigenous input from Guangxi, ocean currents via Qiongzbou Strait also contributed to heavy metal inputs.