大亚湾坝光海域表层海水和沉积物中酸可挥发性硫化物含量的分布和污染评价

Distribution and pollution assessment of AVS content in surface seawater and surface sediments of Baguang waters in Daya Bay

于2011年10月对大亚湾坝光海域表层海水和沉积物的酸可挥发性硫化物(AVS)及相关环境因子进行了调查研究.结果显示,20个测站表层海水的AVS含量在0.039～0.129 mg/dm3之间,平均0.070 mg/dm3,区域分布规律不显著;12个测站的表层沉积物中均检测出AVS,其含量(干重)范围是12.8～867.7 mg/kg,平均为272.4 mg/kg,整体呈近岸较高、离岸较低的分布规律.相关性分析显示,表层水体pH值、CCOD和CDO等环境因子与CAVS相关系数的绝对值均较小,相关性特征不明显;表层沉积物中的CAVS与Eh之间的相关系数为-0.957,呈高度相关性,符合挥发性硫化物含量较高的沉积物处于较强还原状态的普遍规律;大亚湾表层沉积物中的CAVS与pH值、CTOC的相关系数分别为-0.065和0.219,相关性不显著.单因子污染指数评价结果表明,大亚湾坝光海域表层海水硫化物含量已超过所在自然保护区(一类标准)和养殖区(二类标准)所要求的水质标准,局部水体已受到污染;表层沉积物中硫化物含量符合国家一类标准,环境质量良好.

Investigation of acid volatile sulfides （AVS） and other environmental factors were carried out in Baguang areas of Daya Bay in October 2011. Of all 20 stations, AVS content in surface seawater was measured between 0. 039 and 0. 129 mg/dm3 with average weight 0. 070 mg/dm3, and no obvious pattern of regional distribution observed. The AVS（dry weight）in surface sediments of 12 stations varied from 12. 8 to 867.7mg/kg with average weight 272.4 mg/kg. AVS in surface sediments decreased from inshore region to offshore area. Based on the Pearson correlation analysis, there were weak relations of CAvs to pH, CcoD and CDO in surface seawater. CAVs of surface sedments showed a rather close relationship with Eh for its high correlation coefficient of -0. 957, which accorded with the common rule that the higher the concentration of AVS is, the stronger the reduction characteristics of surface sediments appears. Owing to their low correlation coefficients of -0. 065 and 0. 219, there were also weak relations between CAVs and pH, CTOc in surface sediments. According to the pollution index of single factor, the content of AVS in surface seawater was over the limitation value for the water quality in natural protection areas and the farming areas. The sediment quality of AVS was in rather good condition as its content was all below the limitation value of the first class in surface sediments in Baguang area.