深圳坝光湿地地表水水环境质量评价

Assessment of Surface Water Quality in Baguang Wetland in Shenzhen

为了解深圳坝光银叶树湿地水环境状况及其污染程度,在坝光湿地设置了20个采样点,于2017年10月、12月和2018年4月、6月进行水样采集,对地表水盐分、pH、化学需氧量(CODCr)、生物需氧量(BOD5)、营养元素(TP、TN、NO3^-N、NH4^+-N)含量、氟化物(F-)及重金属(Cu、Zn、Cd、Pb、Cr^6+、As)含量进行了测定,采用单因子指数法、综合指数法、水质标识指数法、灰色关联法、变权欧式距离模型法及主成分分析法对地表水水环境质量进行了评价。结果表明,湿地园地表水总磷含量(TP)普遍偏低,达到地表水Ⅲ类等级以上,而地表水总氮含量(TN)偏高,水质等级为Ⅱ类与V~劣V类;湿地园地表水重金属(Cu、Zn、Cd、Pb、Cr^6+、As)含量均达到地表水Ⅰ类水质等级,而汞(Hg)含量介于Ⅲ类~Ⅳ类等级之间,存在Hg重金属污染。采用水质标识指数法与灰色关联度法进行地表水环境等级评价结果基本一致,湿地园坝光水库(SKS)地表水水质为Ⅱ类等级,而淡水水塘(STD)与咸淡水水塘(STX)、银叶树沼泽湿地(ZZS)、海边(LHS)地表水水质较差,介于Ⅲ类~Ⅳ类水质等级,灰色关联度法评价的地表水水质等级优于水质标识指数法。主成分分析可知,坝光水库(SKS)地表水水质最好,淡水水塘(STD)和咸淡水水塘(STX)地表水次之,而临海(LHS)海水与银叶树群落沼泽湿地(ZZS)地表水最差。

This study aims to explore water contamination condition in Baguang wetland in Shenzhen. We set up totally 20 sampling sites, and collected water samples in October and December 2017, and April and June in 2018. Water quality indexes including salinity, pH, CODCr, BOD5, TP, TN, NO3^-N, NH4^+-N, F-, Cu, Zn, Cd,Pb, Cr^6+ and As were measured. We used multiple evaluation approaches to evaluate the water quality, including single factor index, synthetical index, water quality index, grey correlation, Euclidean distance model with varying weights and principal component analysis. The results showed that, TP in Baguang wetland was relatively low and reached the standard of Ⅲ or better, while TN was relatively high and most ranked V or worst. All of Cu, Zn, Cd,Pb, Cr^6+ and As were ranked Ⅰ, but Hg ranked between Ⅲ and Ⅳ indicative of Hg contamination. Evaluation results by water quality index and grey correlation were similar, and showed that the surface water quality in SKS was standard Ⅱ, while qualities in STD, STX, ZZS and LHS were between Ⅲ and Ⅳ. The water quality grade by using grey correlation was better than by using water quality index. Principal component analysis showed that surface water quality in SKS was best among all sites, LHS and ZZS were worst, and the other two sites(STD and STX) were intermediate.