防城港珍珠湾海水富营养化和重金属特征综合分析与评价

Comprehensive analysis and evaluation of seawater eutrophication and heavy metal characteristics in Pearl Bay, Fangchenggang

关键词:  珍珠湾  表层海水  富营养化  重金属  污染评价

Key words:  Pearl Bay  surface seawater  eutrophication  heavy metals  pollution assessment

摘要:

为掌握防城港珍珠湾海水富营养化和重金属的分布特征和污染状况，本研究根据2022年9月在广西防城港市珍珠湾海域采集的20站位表层海水,测定水温、盐度、pH、溶解氧(DO)、溶解无机氮(DIN)、溶解无机磷(DIP)、化学需氧量(COD_Mn)、悬浮物、石油类、叶绿素a(Chl-a)、砷(As)、镉(Cd)、铬(Cr)、铜(Cu)、汞(Hg)、铅(Pb)、锌(Zn)等17项指标,利用单因子指数、综合污染指数、营养状态质量指数、富营养化指数和有机污染指数对海水状况进行综合评价。结果表明：珍珠湾海域海水状况整体属于一类海水；营养状态质量指数NQI均值为1.94,富营养化指数E均值为0.67,整体属于贫营养化水平,N/P比值均值为40.63,整体属于磷中等限制潜在性富营养,DIN污染明显,有机污染指数A均值为0.39,整体水质良好,北侧入海口与西侧出现轻度或中度富营养和污染；单因子污染指数显示湾内海水仅受悬浮物和pH污染,综合污染指数WQI远小于1,属于清洁海域；相关性分析显示,盐度、pH、DIP、As、Cu、Zn、Cd主要受海水潮汐影响,DO、DIN、COD_Mn、悬浮物、石油类、Chl-a、Cr、Hg、Pb主要受河流径流、养殖排放影响。

Abstract:

In order to understand the distribution characteristics and pollution status of seawater eutrophication and heavy metals in Pearl Bay, Fangchenggang, this study was conducted based on 20 stations of surface seawater collected in Pearl Bay waters of Fangchenggang City, Guangxi Province, in September 2022. The study aimed to determine 17 indicators including water temperature, salinity, pH, dissolved oxygen (DO), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), chemical oxygen demand (CODMn), suspended solids, petroleum, chlorophyll-a (Chl-a), As, Cd, Cr, Cu, Hg, Pb and Zn. Single-factor indices, comprehensive pollution indices, trophic quality index of single-factor index, integrated pollution index, nutrient quality index, eutrophication index, and organic pollution index were utilized to comprehensively evaluate the seawater condition. The results show that the seawater quality in the Pearl Bay area meets the first-class of seawater standard; the average NQI of the nutrient status quality index is 1.94, the average value of the eutrophication index E is 0.67, which is characterized by the low level of eutrophication. The average value of the N/P ratio is 40.63, which is characterized by the medium-restricted level of eutrophication, and the DIN pollution was obvious. The average value of the organic pollution index A is 0.39, and the overall water is clean, Only the north and west estuaries have mild or moderate eutrophication and pollution; the single-factor pollution index shows that the seawater in the bay is only polluted by suspended solids and pH, and the comprehensive pollution index WQI is much less than 1, which belongs to the clean sea area. Salinity, pH, DIP, As, Cu, Zn and Cd are mainly affected by seawater tides according to the correlation analysis, while DO, DIN, CODMn, suspended solids, petroleum, Chl-a, Cr, Hg, and Pb are mainly affected by river runoff and aquaculture.