珠江口及其邻近海域重金属的河口过程和沉积物污染风险评价

Heavy metals' process in water and pollution risk assessment in surface sediments of the Zhujiang River Estuary

根据2006年到2007年,"908专项"珠江口附近海域海水与沉积物的调查资料,研究珠江口海域海水和沉积物中重金属含量分布特征;珠江口及附近海域海水中铜、铅、锌、镉、总铬、汞、砷的含量平均值均符合国家一类海水水质标准,采用数理统计相关分析计算出各重金属元素与各环境因子之间的相关,发现在河口重金属主要以稀释混合过程为主,悬浮颗粒物中重金属在酸化作用下以解吸作用为主,氧化还原作用的影响不大。沉积物中铜-锌、铅-锌、铜-镉、铅-镉、锌-镉、铅-铬,锌-铬、镉-铬8组元素间具有显著的相关性,表明它们具有相似的元素地球化学性质和来源;并运用Hakanson潜在生态危害系数法对其潜在生态危害程度进行评估,珠江口沉积物的潜在生态风险的来源是镉和汞占据主要权重,尤其珠江口沉积物中镉的污染程度和潜在生态风险局部激增的特点值得重点关注。

On the basis of the data of four seasons of seawater and sediments from the 908 survey in the Pearl River Estuary, the concentration distribution characteristics of the heavy metals in seawater and sediments were made; results show that the mean content of seven heavy metals （Cu,Pb,Zn,Cd,Cr, Hg, As） in Pearl River Estuary and surrounding seas all belonged to the I- level seawater quality standard, and the correlation between the heavy met- als and environmental factors is obtained through mathematic statistic method. The result indicates that in the estuarine the heavy metals＇ main process is diluting and mixing, the heavy metals in SPM mainly desorb under acidification effect, and oxidation-reduction has little influence. There was a statistically significant correlation between the element Cu-Zn, Pb-Zn, Cu-Cd, Pb-Cd, Zn-Cd, Pb-Cr, Zn-Cr, and Cd-Cr in sediments, which indicates that they have similar geochemical properties and sources. The method of potential ecological risk index presented by Lars Hakanson was used to assess the heavy metals＇ ecological risk. The main source of the potential ecological risk of the sediment are Cd, Hg, which is worth the key attention that the pollution levels and the potential ecological risks of Cd local surged in sediments.