夏秋季珠江口水域COD、DO、营养盐分布特征及其富营养化评价

Distribution characteristics of COD,DO and nutrients in Pearl River Estuary and its eutrophication assessment in summer and autumn

在2012年夏季(8月)和秋季(11月)对珠江口海域进行化学需氧量(COD)、溶解氧(DO)和氮磷营养盐调查分析,并研究了其分布特征,采用富营养化指数法和潜在性富营养化法对珠江口水体营养化状况进行了分析和评价.结果显示,珠江口海域COD质量浓度较低,夏季平均值为1.85 mg/L,秋季为1.10 mg/L;DO质量浓度较高,夏季平均值为6.95 mg/L,秋季为7.63 mg/L;无机氮污染严重,平均质量浓度夏季为0.85 mg/L,秋季为0.79mg/L,总体上从北向南递减;无机磷秋季平均质量浓度(0.015 mg/L)显著低于夏季平均质量浓度(0.010 mg/L).富营养化严重海域主要集中在东北部及伶仃洋一带,基本呈自北向南逐级递减趋势.秋季富营养化程度显著高于夏季,珠江口海域基本上属于磷限制潜在性富营养水平.

Basedoninvestigationsofchemicaloxygendemand（COD）,dissolvedoxygen（DO）and nutrients （nitrogen and phosphorus）in the Pearl River Estuary in summer （August）and autumn （No-vember）in 201 2,the distribution characteristics of physic-chemical parameters of Pearl River estuary were analyzed.Meanwhile,the eutrophication index （EI）and the potential eutrophication assessment were employed to assess the eutrophication state of the study area.The results indicated that the COD was low and the average values in summer and autumn were 1.85 mg/L and 1.1 0 mg/L respectively.The DO in waters was high and the average values in summer and autumn were 6.95 mg/L and 7.63 mg/L.The critical pollutant in the waters was dissolved inorganic nitrogen.It decreased from north to south in the study area,with the average concentration of 0.85 mg/L in summer and 0.79 mg/L in autumn.The av-erage concentration of dissolved inorganic phosphorus in autumn （0.024 mg/L）was much higher than that in summer （0.01 0 mg/L）.Moreover,the most severe eutrophication phenomenon mainly occurred in the northeast of the estuary and the area of Lingdingyang waters.The level of the eutrophication index＆amp;nbsp;dropped off from north to south as a whole.The data revealed that the eutrophication level was higher in autumn than in summer and the waters was basically at potential eutrophication of phosphorus limit.