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气候变化背景下,极端气候事件对河口生态环境的影响已引起许多研究者的关注.基于2011年夏季的调查资料,分析了珠江口在极端干旱情况下溶解氧的分布特征及其与海水稳定性、营养盐和浮游植物分解之间的关系,并对河口底层低氧区的成因进行初步探讨.调查结果发现,在珠江特低径流量的情况下,珠江口邻近海域底层明显出现低氧状态,DO的最低值仅为1.38 mg.L-1.相关性分析显示,表层水和底层水之间的ΔDO与ΔT、ΔS、ΔDIN、ΔSS和ΔPOC都达到显著相关的水平,其中ΔDO与ΔT和ΔPOC呈极显著的正相关,而与ΔS呈极显著的负相关关系.研究表明,与1999年和2009年夏季不同,2011年夏季珠江口底层低氧环境的形成主要与极端干旱气候下低径流导致河口水体滞留时间延长及颗粒态有机物质在沉降过程中的分解耗氧有关.另外,从最低DO值的角度分析,珠江口季节性缺氧程度在过去20 a间并未呈现显著的变化趋势.
Under the background of climate change, the impact of extreme climate events on the estuary ecological environment has attracted the attention of many researchers.Based on the survey data of summer 2011, the distribution characteristics of dissolved oxygen in the Pearl River Estuary in extreme drought conditions and its relationship with seawater stability , The relationship between nutrients and phytoplankton decomposition, and the origin of the hypoxic zone in the bottom of the estuary was discussed.It was found that under the condition of the special low-flow rate of the Pearl River, hypoxia obviously occurred in the bottom of the Pearl River estuary, The lowest DO was only 1.38 mg.L-1. Correlation analysis showed that ΔDO between surface water and bottom water reached significant correlations with ΔT, ΔS, ΔDIN, ΔSS and ΔPOC, with ΔDO with ΔT and ΔPOC But significant negative correlation with ΔS.The results show that the formation of hypoxic environment in the bottom of the Pearl River Estuary in summer 2011 differs from that in summer of 1999 and 2009 mainly due to the low runoff under extreme arid climate Estuary water body retention time and the decomposition of particulate organic matter in the process of sedimentation oxygen consumption.In addition, from the perspective of the lowest DO value, the Pearl River estuary seasonal anoxia in the past 20 a It did not show significant trends.