2020年夏季渤海中部底层水体低氧现象成因分析

Analysis on the causes of hypoxia in the bottom of the central Bohai Sea in summer 2020

在气候变化和人类活动的双重作用下,海湾富营养化及其导致的季节性低氧成为近海生态安全风险评估的核心指标之一。本文根据2020年夏季渤海中部现场调查的结果,分析了渤海中部夏季DO的分布状况及其影响因素。监测结果表明,2020年夏季在黄河口东北部底层海域(38°N)出现约1300 km^(2)的低氧区,DO最低浓度为2.18 mg/L。分析结果表明,2020年夏季渤海中部底层低氧区的形成受水体层化和富营养化的共同影响,富营养化导致了底层有机物的累积,有机物分解消耗了大量DO,而夏季层化作用阻碍水体的垂直混合,导致底部消耗的DO得不到及时补充,从而产生低氧区。本文对2020年夏季渤海中部底层水体低氧现象的研究,可为将来渤海生态环境监测和生态安全风险评估提供资料,具有一定的科学意义。

Under the multiple effects of climate change and human activities,eutrophication and the resulting seasonal hypoxia are the core of the coastal ecological security risk assessment.This paper analyzes the distribution and influencing factors of DO according to the results of field investigation in the central Bohai Sea in summer of 2020.The results showed that in the summer of 2020,a hypoxic area of about 1300 km^(2 )appeared in the bottom of the northeastern waters of the Yellow River Estuary,the center of the hypoxic area was located at 38°N,and the lowest concentration of DO was 2.18 mg/L.In the summer of 2020,the formation of the bottom hypoxic zone in the central Bohai Sea was affected by the combined effects of water stratification and eutrophication.The stratification hinders the vertical mixing of the water and reducing the replenishment of DO at the bottom;eutrophication leads to the accumulation of bottom organic matter,and the increase of bottom organic matter intensifies the decomposition process,resulting in the consumption of DO and the decrease of pH.The research on the hypoxia phenomenon in the bottom of the central Bohai Sea in the summer of 2020 can provide a reference for the ecological environment monitoring and ecological security risk assessment of the Bohai Sea in the future.