防城港西湾及邻近海域水体重金属的季节性和年际变化特征

Seasonal and Interannual Variation of Heavy Metals in West Bay and Its Adjacent Area of Fangchenggang Bay

关键词:  西湾  水体  重金属  污染  评估

Key words:  West Bay  seawater  heavy metals  pollution  evaluation

摘要:

为评估防城港市西湾及邻近海域水体重金属的污染状况，本研究获取了2020年6月、9月和12月及2011-2018年西湾水体重金属的监测数据，2010-2020年防城江的监测数据，采用单因子污染指数(P_i）法、综合污染指数（Water Quality Index，WQI）法、内梅罗污染指数（F）法和主成分分析（Principal Component Analysis，PCA）法进行分析与评价。2020年防城江水体各重金属含量无季节性差异，基本上符合第一类海水水质标准。2020年西湾水体重金属含量为锌（Zn）>铜（Cu）>砷（As）>铅（Pb）≈铬（Cr）>镉（Cd）>汞（Hg），Pb、Zn和Hg存在超第一类海水水质标准的情况，超标率分别为（9.1±0）%、（10.6±14.6）%和（24.2±22.9）%。F显示局部区域处于轻污染状态，超标率为（7.5±5.3）%。WQI和F显示，2010-2020年防城江重金属污染水平随时间呈变好趋势，2019-2020年处于较清洁状态。WQI和F显示2011-2020年西湾水体污染水平随时间虽然有波动，但是整体有向好趋势。西湾水体中重金属的来源和污染程度受到人类活动和生物地球化学过程的共同影响。防城港市钢工业的持续发展，仍存在加重防城港湾重金属污染水平的风险，应继续加强对周边污染源的治理与评估。

Abstract:

In order to evaluate the pollution status of heavy metals in West Bay (WB) of Fangchenggang City and its adjacent waters, the monitoring data of heavy metals in West Bay in June, September and December 2020 and from 2011 to 2018, and the monitoring data of Fangchengjiang River in 2010-2020 were obtained in this study. Single factor index (P_i), Water Quality Index (WQI), Nemerow pollution index (F) and Principal Component Analysis (PCA) methods were used for analysis and evaluation. There was no seasonal difference in contents of heavy metals in Fangchengjiang River in 2020, which basically met the first class of seawater quality standards. Contents of heavy metals in WB exhibited the following order:Zn>Cu>As>Pb≈Cr>Cd>Hg in 2020. Contents of Pb, Zn and Hg exceeded the first class of seawater quality standards, and the exceeding rates were (9.1±0)%, (10.6±14.6)% and (24.2±22.9)%, respectively.F showed that partial area was in a light pollution state and the exceeding rate was (7.5±5.3)%. WQI and F indicated that the heavy metal pollution level of Fangchengjiang River showed a good trend over time from 2010 to 2020, and it was in a relatively clean state from 2019 to 2020.WQI and F showed that although the water pollution level in West Bay fluctuated over time from 2011 to 2020, the overall trend was positive.Sources and pollution levels of heavy metals in WB were jointly affected by human activities and biogeochemical processes. With the sustainable development of the steel industry in Fangchenggang City, there is still a risk of increasing the level of heavy metal pollution in Fangchenggang Bay. It is necessary to strengthen the management and evaluation of surrounding pollution sources.