珠江口水、沉积物及生物体As含量分布特征及生态风险评价

摘要

Concentrations of arsenic in water, sediments, and aquatic animals from the Pearl River estuaries were studied in February, May, August, and November 2008. The results showed that the average arsenic concentration in water was 2.88µg ·L-1, which was lower than the Class I standard for sea water quality. The arsenic concentration in water was significantly higher in November than in the other three months according to ANOVA (P < 0.05). The geographical distribution for the annual average content of arsenic in water from the eight estuaries was, in descending order: Humen, Jitimen, Modaomen, Yamen, Honglimen, Jiaomen, Hengmen, and Hutiaomen. The average arsenic concentration in the sediments was 38.73 mg·kg-1, which was higher than the Class I standard for marine sediment quality, but did not exceed the Class III standard. The results showed that surface sediments from the Hengmen estuary had the highest arsenic content, (70.5 ± 2.0) mg·kg-1, which was significantly higher than in samples from the other seven estuaries (P< 0.05 ), which had no significant differences between them. The arsenic content for the eight estuaries was, in decreasing order: Hengmen, Honglimen, Jitimen, Humen, Yamen, Modaomen, Hutiaomen, and Jiaomen. The geo-accumulation pollution index and the potential ecological risk index were used to evaluate arsenic pollution in sediments. The results showed that arsenic in sediment from the Hengmen estuary was moderately polluted, and that sediments from the other estuaries were slightly polluted. Representative biological samples were collected for analysis, and the results showed that the average arsenic concentration in 11 species of fish was 0.587 mg·kg-1. Some of the fish samples had an arsenic content that exceeded the limits for toxic and hazardous materials in aquatic products by 37.8%. Furthermore, the arsenic concentration in predatory fish was higher than that in omnivorous fish, but the arsenic concentration in fish was not significantly different with regard to distinct feeding habits or habitat (P > 0.05). However, the arsenic concentration in shrimp was 0.314 mg·kg-1, which was lower than the permitted limits. The average arsenic concentration in the environment and in aquatic organisms from the Pearl River estuaries has increased in recent years, and the estuaries have a higher degree of contamination compared with other estuaries in China.%　　于2008年2、5、8及11月对珠江口进行了水、沉积物和生物体As含量的调查，分析其分布特征以及进行生态评价。结果表明：珠江口水体中As含量平均值为2.88µg·L-1，符合一类海水水质标准；其中，11月份显著高于其它3个月份(P <0.05)。全年珠江口水体八个河口在地域分布上As平均含量由高到低依次为：虎门、鸡啼门、磨刀门、崖门、洪沥门、蕉门、横门、虎跳门。表层沉积物As含量平均值为38.73 mg·kg-1，沉积物中As含量均超过海洋沉积物质量一类标准，但均未超三类标准。结果显示，表层沉积物横门含量最高，为(70.5±2.0) mg·kg-1，显著高于其它7个口门(P <0.05)，而其它7个口门差异不显著。各口门含量从大到小依次为横门、洪沥门、鸡啼门、虎门、崖门、磨刀门、虎跳门、蕉门。表层沉积物地质累积指数评价结果与潜在生态风险系数评价结果一致，横门为中等污染水平，其余站点均为低污染水平。采集代表性生物样品，其中11种鱼类As平均含量为0.587 mg·kg-1，部分受检鱼类超出水产品中有毒有害物质限量要求，超标率为37.8%，肉食性鱼类平均含量要略低于杂食性鱼类，但不同食性和不同生活水层的鱼类As含量差异不显著(P >0.05)。受检生物样品虾的含量为0.314 mg·kg-1，符合水产品中有毒有害物质限量要求。与历年比较发现珠江口水、沉积物和生物体中As含量有上升的趋势，与其它河口相比较发现珠江口As污染在对比的河口和海湾中受污染程度较高。