胶州湾富营养化现状及趋势分析

Current status and changing tendency of eutrophication of Jiaozhou Bay

于2014—2019年间对胶州湾海域开展6年、每年分4个季度月的连续监测,分析该海域COD、无机氮(DIN)和活性磷酸盐(RP)等主要水质指标的变化,并对海域富营养化现状与变化趋势进行了分析。结果表明:2014—2018年间该海域COD、活性磷酸盐、无机氮年均值均达到或好于国家二类海水水质标准;COD和活性磷酸盐总体稳定,无机氮呈逐年下降趋势,表明胶州湾水质逐步好转。2019年10月的调查数据表明,胶州湾潜在性富营养化程度较低,富营养覆盖海域比例为23.9%,富营养化区域主要分布在湾东北角,潜在性富营养化的区域均为磷限制。基于富营养化指数的评价结果显示,胶州湾海域贫营养化海域面积扩大、富营养化海域面积减少,富营养化程度总体呈现逐年下降趋势。

A continuous investigation was conducted in Jiaozhou Bay,Shandong Province,from 2o14 to 2019,4 seasonal cruises each year.Simultaneously,the temporal and spatial variations of seawater quality indices including chemical oxygen consumption(COD),dissolved inorganic nitrogen(DIN)and reactive phosphate among others were assayed.The results showed that annual mean concentrations of COD,DIN and RP are either close to or better than the class II Seawater Quality Standards while DIN decreased,COD elevated and RP was relatively stable.These findings indicated that the seawater quality of Jiaozhou Bay has been improving steadily.Analysis on the eutrophication status based on data collected in Oct.,2019 revealed that potential eutrophication is low and the proportion of eutrophicated area is about 23.9%,covering mainly the northeast corner of the bay.Phosphorus was found to be a restricting factor in the eutrophicated area.The eutrophication index showed that the area of hypotrophic sea area of Jiaozhou Bay is expanding while the area of eutrophic sea area is decreasing,and the degree of eutrophication is decreasing year by year.