防城港湾连续10年海水水质变化及其影响因素分析

Analysis of Seawater Quality Variation and Influencing Factors in Fangchenggang Bay for the Past Ten Years

关键词:  港湾  水质变化  影响因素  广西  防城港

Key words:  harbor  water quality change  influence factor  Guangxi  Fangchenggang Bay

摘要:

选取防城港湾（东湾、西湾和外湾）2010-2019年近岸海域海水水质的数据，对其海水环境变化情况及影响因素进行分析。研究参数包括化学需氧量（COD）、活性磷酸盐（DIP）、氨氮（NH₄⁺-N）、亚硝酸盐氮（NO₂^--N）和硝酸盐氮（NO₃^--N）。采用综合污染指数法和富营养指数法对防城港湾近岸海域海水水质变化进行评价，营养盐与各影响因子的相互关系采用Pearson相关性分析。研究结果表明，在近10年工业开发过程中，防城港湾海域水质状况总体良好，海水水质污染级别为较好至轻度污染，主要超标因子为活性磷酸盐。海域富营养化水平在轻度富营养化至中度富营养化之间，营养盐浓度整体呈现西湾>东湾>外湾，内湾大于外湾的分布趋势。西湾无机氮随季节变化明显，而活性磷酸盐随季节变化不明显；丰水期西湾和东湾无机氮浓度差异显著，这可能与西湾防城江入海径流夏季大量输出有关。个别年份如2013年和2017年出现水质超标的原因与该地区环境基础设施未完善以及工业企业污染物超标排放有关。

Abstract:

The seawater quality data of coastal waters in Fangchenggang Bay (East Bay, West Bay and Outer Bay) from 2010 to 2019 were selected to analyze the changes of the seawater environment and the influencing factors.The research parameters include chemical oxygen demand (COD), active phosphate (DIP), ammonia nitrogen (NH₄⁺-N), nitrite nitrogen (NO₂^--N) and nitrate nitrogen (NO₃^--N).The comprehensive pollution index method and the eutrophication index method were used to evaluate the water quality changes in the coastal waters of Fangchenggang Bay.Pearson correlation analysis was used to analyze the relationship between nutrients and each influencing factor.The results showed that the water quality of Fangchenggang Bay was generally good in the process of industrial development in the past 10 years.The pollution level of seawater quality ranged from good to light, and the main exceeding factor was active phosphate.The eutrophication level in the sea area was between mild eutrophication and moderate eutrophication.The concentration of nutrient salt was in the order of West Bay > East Bay > Outer Bay, and the distribution of Inner Bay was greater than that of Outer Bay.The inorganic nitrogen in the West Bay changed significantly with seasons, but the active phosphate did not change significantly with seasons.The concentration of inorganic nitrogen in the West Bay and the East Bay was significantly different during the wet season, which might be related to the large output of the coastal runoff of Fangcheng River in the West Bay in summer.In individual years, such as 2013 and 2017, the reasons for the excessive water quality were related to inadequate infrastructure in the area and the excessive discharge of pollutants from industrial enterprises.