长江河口生态系现状及修复研究

2000～2003年5月和8月对长江口及邻近水域的水质、表层沉积物、浮游生物的监测数据进行了综合评价,计算2000～2003年水质综合指数得分4,年平均为2.15,年得分逐步增加.参照水质参数污染等级划分标准,显示长江口水域水环境综合质量已处于严重污染水平,且呈逐年恶化趋势.其中油类、锌超标程度明显逐年加大.计算2000～2003年表层沉积物综合指数得分4,年平均为0.78,参照表层沉积物参数污染等级划分标准,显示长江口水域表层沉积物环境质量处于中污染水平.但2003年得分为1.06,显著高于前3年,表明2003年表层沉积物质量已处于重污染水平.计算2000～2003年浮游生物多样性综合指数得分4,年平均为0.53,年际变化幅度较小,参照浮游生物参数污染等级划分标准,显示生物环境质量处于中度污染水平.对2000～2003年水质、表层沉积物和浮游生物生态质量进行综合评价,总得分为1.15,2003年综合得分显著高于前3年,参照综合参数污染等级划分标准,长江河口综合环境质量处于重度污染水平,2003年综合环境质量进一步明显下降.相对应,自1995年以后,长江口捕捞产量一直趋于下降,目前除凤鲚资源尚属稳定外,其余均已形不成渔汛;长江口的蟹苗在2000年以后已没有蟹苗汛出现,蟹苗产量降至谷底.针对长江口生物及非生物环境现状及所面临的胁迫压力,提出建立以长江口生态系统为基础的管理机制,开展对污染物控制、关键种群和重要生境的保护及修复等对策,使退化的长江口生态系尽快得到修复.

The current situation and restoration research of the Yangtze River estuarine ecosystem

The monitoring data in the May and August from 2000 to 2003 of water quality,sediment and biological diversity were used to assess the comprehensive situation of Yangtze River estuary ecosystem.The four year average score of water quality index was 2.15,and the score increases from 2000 to 2003.The comprehensive situation of water quality in Yangtze River estuary was on serious contaminate level if referring to the standard of water quality index and the oil and Zn showed an increasing trend.The four year average score of surface sediment index was 0.78,but in 2003 the score was 1.06.If referring to the standard of sediment quality index,the comprehensive situation of sediment quality was on middle contaminate level,whereas in year 2003 was on heavy pollution level,which showed a bad trend of sediment quality.The four year average score of biodiversity index was 0.53,and no significant change was viewed among years.If referring to the standard of biodiversity index,the comprehensive situation of biological environment quality was on middle contaminate level.The four year average score of integrated index was 1.15,but in 2003 the score was significant larger than that of 2000,2001 and 2002.If referring to the standard of integrated index,the comprehensive situation of water quality,sediment and biodiversity was on the heavy pollution level,but year 2003 showed a further decreased trend when compared with the other three year.Correspondingly,the catch in Yangtze River estuary continued to decrease after 1995 and the fishing period had almost disappeared except Coilia mysfus.The fishing period for larva of Eriocheir sinensis also had disappeared since 2000 and the yield declined to lowest.The restoration strategies were based on the analysis of the main stress and the current situation of Yangtze River estuary.A working system about Yangtze River estuary restoration strategies should be setup in the future.In this system the ecosystem-based management was the core,working with other three act plans: waste controled,conservation and restoration of important habitat and key species.The effective and feasible ecosystem management acts were composed by a long-time and dynamic environment monitoring system,cooperation among government agencies and application of biological restoration techniques on the important aquatic zones.