考洲洋海域水质季节变化及评价方法初步研究

Preliminary Study on Seasonal Variation of the Sea Water Quality and Its Evaluation Methods in the Sea of Kaozhou Bay

文章于2018年1月(冬季)、4月(春季)、7月(夏季)、10月(秋季)对我国考洲洋海域海水中的溶解氧(DO)、化学需氧量(COD)、无机氮(DIN)、活性磷酸盐(DIP)4个主要海水水质因子进行了综合调查。结果表明,4个水质因子DIP、DIN、COD、DO的平均浓度由高到低的季节变化分别为:冬季(0.058 mg/L)、春季(0.046 mg/L)、夏季(0.009 mg/L)、秋季(0.006 mg/L);冬季(0.465 mg/L)、春季(0.171 mg/L)、夏季(0.064 mg/L)、秋季(0.040 mg/L);夏季(1.57 mg/L)、冬季(1.26 mg/L)、秋季(1.22 mg/L)、春季(0.89 mg/L);冬季(11.70 mg/L)、夏季(7.41 mg/L)、秋季(7.36 mg/L)、春季(7.18 mg/L)。评价结果显示,春季和冬季主要超标因子为DIP和DIN,夏季超标因子为DIP,秋季水质因子均满足要求。同时,本研究利用单因子标准指数法、富营养化指数法和有机污染评价指数法对考洲洋地区水质状况进行评价并对其进行初步比较和分析,结果表明,3种方法在季节性变化上的评价结果基本一致(由高到低均为:冬季、春季、夏季、秋季),然而,同一季节不同评价方法的超标站位比例不同(单因子指数法:冬季占100%,春季占80%,夏季占10%,秋季则无;富营养化指数法:冬季占90%,春季占70%,夏季和秋季均为无;有机污染指数评价法:冬季和春季均占80%,夏季和秋季均为无),比较分析表明,3种评价方法具有不同的评价作用和适用性。

In this study,four main factors,including Dissolved Oxygen(DO),Chemical Oxygen Demand(COD),Dissolved Inorganic Nitrogen(DIN),and Dissolved Inorganic Phosphate(DIP),in the sea of Kaozhou Bay,were investigated in January(winter),April(spring),July(summer),and October(autumn)2018.Results showed that the changes seasonally for average concentrations of DIP,DIN,COD,DO were,respectively,winter(0.058 mg/L)>spring(0.046 mg/L)>summer(0.009 mg/L)>autumn(0.006 mg/L),winter(0.465 mg/L)>spring(0.171 mg/L)>summer(0.064 mg/L)>autumn(0.040 mg/L),summer(1.57 mg/L)>autumn(1.26 mg/L)>winter(1.22 mg/L)>spring(0.89 mg/L),winter(11.70mg/L)>summer(7.41 mg/L)>autumn(7.36 mg/L)>spring(7.18 mg/L);The evaluation results showed that DIP and DIN were out of water quality standard both in spring and summer,DIP in summer,and all the water quality factors met the requirements in autumn.At the same time,using single factor index method,eutrophication index method,and organic pollution index method,the water quality situation were evaluated and their evaluation results were compared by three methods.This study showed the evaluation results of water quality on the seasonal variation were basically identical(from high to low were:winter>spring>summer>autumn)among three methods,however,proportions of over standard stations were different in the same season by using three different kinds of evaluation methods(Single Factor Index Method:winter(100%),spring(80%),summer(10%),autumn(0%);Eutrophication Index Method:winter(90%),spring(70%),summer and autumn(0%);Organic Pollution Index Method:winter and spring(80%),summer and autumn(0%),the comparative analysis showed,there were clearly different evaluation target and discrepant applicability.