珠江口近岸海域水质状况评价及富营养化分析

Water quality assessment and eutrophication analysis in coastal waters of Pearl River estuary

为了解珠江口近岸海域水质现状及富营养程度,于2016年7-9月对珠江口近岸海域进行水环境现状调查,运用有机污染指数法和营养状况指数法对珠江口近岸海域水质进行分析与评价,并通过主成分分析法和聚类分析对调查海域水环境影响因素进行富营养化分析研究。结果表明:调查海域营养盐污染严重,无机氮含量变化范围为1.32~4.31 mg/L,平均值为2.12 mg/L;活性磷酸盐含量变化范围为0.05~0.39 mg/L,平均值为0.11 mg/L;调查海域无机氮和活性磷酸盐均劣于国家Ⅳ类海水水质标准;无机氮中以硝酸盐氮含量为主,氨氮次之,亚硝酸盐氮最低;调查海域空间分布特征均呈现茅洲河入海口附近海域向湾外逐渐降低的趋势;采用主成分分析法得到调查海域富营养化的主要影响因子为氮磷营养盐、化学需氧量。研究表明,珠江口近岸海域水质环境较差,有机污染呈严重污染,营养状况呈富营养化水平,水环境质量有待于进一步提高。

pH, salinity, and levels of dissolved oxygen(DO), chemical oxygen demand(CODMn), active phosphate(DIP), nitrite nitrogen(NO-2-N), nitrate nitrogen(NO-3-N), ammonia nitrogen(NH3-N), total nitrogen(TN), total phosphorus(TP) and chlorophyll a(Chl-a) were monitored in coastal waters sampled from 20 sampling sites near Pearl River estuary from July to September, 2016, and the quality and eutrophication of the seawater were assessed by organic pollution index and nutrient quality index(NQI), and by main factors from principal component analysis. It was found that nutrient pollution in the Pearl River estuary sea area was become worse, with inorganic nitrogen content ranging from 1.32 mg/L to 4.31 mg/L, on average of 2.12 mg/L. The contents of active phosphate were varied from 0.05 mg/L to 0.39 mg/L, with average of 0.11 mg/L, indicating that COD and DIP levels in all the sampling stations were graded as Ⅳ below;nitrate nitrogen was the most prevalent inorganic nitrogen, followed by ammonia nitrogen, and the minimal nitrite nitrogen. Organic pollution index and NQI revealed that the waters were within the eutrophication level, with the spatial distribution of a trend of gradually decreasing from the Maozhou River estuary to the south. The principal component analysis indicated that DIP, DIN, and CODMnwere the main factors impacting the eutrophication of the seawater. The findings showed that the water quality was poor and future improved in coastal water of Pearl River estuary.