湛江湾水体化学需氧量分布特征及影响因素

Distribution Characteristics and Influencing Factors of Chemical Oxygen Demand in Zhanjiang Bay

关键词:  化学需氧量  营养盐  季节变化  人类活动  湛江湾

Key words:  COD  nutrients  seasonal variation  human activity  Zhanjiang Bay

摘要:

本研究在于分析湛江湾水体化学需氧量（Chemical Oxygen Demand，COD）的分布特征，为科学评价、防控该海域水质污染提供建设性依据。于2017年冬季和春季对半封闭海湾湛江湾水体COD及其他环境因子展开调查，分析该海湾COD的季节变化、环境效应和影响因素。结果显示，春季湛江湾水体COD浓度[0.36-2.70 mg/L，平均为（1.24±0.42） mg/L]高于冬季[0.43-1.92 mg/L，平均为（1.11±0.27） mg/L]，主要受春季陆源输入增加及养殖活动增多影响。受人类活动影响，春季和冬季湛江湾水体COD浓度分布特征相似，高值均出现在上湾区，并向湾外逐渐降低。与近30年历史数据相比，湛江湾水体COD浓度呈增长趋势，其主要受近年来湛江经济快速发展的影响。对湛江湾水体COD评价结果显示，冬季所有站位COD污染指数（0.22-0.95）均未超标，但春季（0.38-1.35）存在超标现象，超标率为8%。相关性分析显示，冬季和春季湛江湾水体COD浓度与营养盐均呈显著正相关关系，说明它们同源，可能受邻近区域人类活动的影响。该研究结果表明，随着径流量输入增加及养殖活动增多，春季湛江湾水体COD浓度升高，需加强警惕。

Abstract:

The purpose of this study is to analyze the distribution characteristics of Chemical Oxygen Demand (COD) in Zhanjiang Bay, and provide a constructive basis for scientific evaluation and prevention of water pollution in this area.COD and other environmental factors in Zhanjiang Bay, a semi-enclosed bay, were investigated in winter and spring of 2017. The seasonal variation, environmental effects and influencing factors of COD in Zhanjiang Bay were analyzed. The results show that the COD concentration in Zhanjiang Bay in spring[0.36-2.70 mg/L, average (1.24±0.42) mg/L] is higher than that in winter[0.43-1.92 mg/L, average (1.11±0.27) mg/L], which is mainly due to the increase of land-based input and aquaculture activities in spring. Affected by human activities, the distribution of COD concentration in Zhanjiang Bay is similar in spring and winter. The high values occur at the top of the Bay and gradually decrease towards the outer bay.Compared with the historical data of nearly 30 years, the COD concentration in Zhanjiang Bay shows an increasing trend, which is mainly affected by the rapid economic development of Zhanjiang in recent years. The evaluation results of COD in Zhanjiang Bay show that the COD pollution index of all stations (between 0.22 and 0.95) do not exceed the standard in winter, but it exceeds the standard in spring (between 0.38 and 1.35), with an over-standard rate of 8%.The correlation analysis shows that there is a significant positive correlation between COD content and nutrients in Zhanjiang Bay in winter and spring, indicating that they are homologous and might be affected by human activities in adjacent areas.This study shows that with the increase of runoff input and aquaculture activities in spring, the COD concentration in Zhanjiang Bay increases in spring, which needs to be vigilant.