Ye Feng, Huang Xiao-ping, Shi Zhen, Liu Qing-xi
State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
Huan Jing Ke Xue. 2013 May;34(5):1707-14.
More and more attention has focused on assessing impacts of extreme hydrologic events on estuarine ecosystem under the background of climate change. Based on a summer cruise conducted in the Pearl River Estuary in 2011 (extreme drought event), we have investigated the spatial distribution of dissolved oxygen (DO) and its relationships to water column stability, nutrient concentrations, and organic matter; besides, the major reason which caused the oxygen depletion was discussed. Under the influence of the extreme drought event, low bottom water dissolved oxygen was apparent in regions characterized by great depths, with an oxygen minimum value of 1.38 mg x L(-1). Statistical analysis shows significant correlations among deltaDO, deltaT, deltaS and deltaPOC. A comparison was conducted to show the mechanisms of oxygen depletion during the summers of 1999, 2009 and 2011, respectively. The result indicates that prolonged residence time of water due to the extremely low discharge and the subsequently decomposition of organic substance are major factors causing the formation of hypoxia during the summer drought in 2011. Despite the changing nutrient and organic matter regime in the Pearl River Estuary, there was no apparent trend in the minimum values of DO over the past 2 decades.
在气候变化背景下，极端水文事件对河口生态系统的影响评估受到越来越多的关注。基于2011年在珠江口进行的一次夏季巡航（极端干旱事件），我们研究了溶解氧（DO）的空间分布及其与水柱稳定性、营养盐浓度和有机物的关系；此外，还讨论了导致氧气消耗的主要原因。在极端干旱事件的影响下，在深度较大的区域，底层水溶解氧明显偏低，最低氧值为1.38mg·L⁻¹。统计分析表明，溶解氧变化量（deltaDO）、温度变化量（deltaT）、盐度变化量（deltaS）和颗粒有机碳变化量（deltaPOC）之间存在显著相关性。分别对1999年、2009年和2011年夏季氧气消耗的机制进行了比较。结果表明，2011年夏季干旱期间，极低流量导致的水体停留时间延长以及随后有机物的分解是导致缺氧形成的主要因素。尽管珠江口的营养盐和有机物状况不断变化，但过去20年中溶解氧的最低值没有明显趋势。
