Historical overview of hypoxia in the Bay of Bengal
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摘要: 世界沿海地区快速的经济发展和人口的增加, 以及农业和渔业生产的增加, 给沿海生态系统带来了巨大的环境压力. 环境压力的最主要症状是缺氧, 这是指低氧或贫氧(≤ 2 mg/L)的区域, 动物可能会窒息而死. 本研究旨在通过之前有效相关的文献并利用NOAA的世界大洋图集数据, 认知从20世纪70年代至2018年期间孟加拉湾低氧区历史概观. 除2018年, 至20世纪70年代以来, 孟加拉湾氧气浓度在一定程度上保持稳定, 在水深100 m (≤ 1.6 mg/L) 区域低氧区长期存在. 由于孟加拉湾在2013—2018年期间发生了一些热带气旋, 2018年地表和地下水中的氧气浓度突然增加. 次表层水中溶解氧含量的上升主要是由于剧烈的垂向混合、下沉流和上升流. 风暴导致的上升流会导致溶解氧含量的下降. 相比起中层水(100~500 m)中耗竭的氧浓度, 在水深0~100 m 和1000 m的区域氧浓度是较高的. 然而, 由于各种临近河流的大量淡水输入以及高降雨量, 孟加拉湾水体层化现象显著. 结合相关物理过程, 这种垂向水体分层控制了表层和次表层水的输运和垂向交换, 加剧了低氧区的形成, 进而影响此区域内浮游植物和水生生物的生长.
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Key words:
- dissolved oxygen /
- hypoxia /
- stratification /
- Bay of Bengal
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Fig. 1 Trends in annual average concentration of DO at a depth of 0~1000 m in the BoB (8 ~ 20°N, 80 ~ 100°E)
Note: 1976 data were adapted from Naqvi et al [7] and other data were derived from NOAA World Ocean Atlas
Fig. 2 Salinity (‰) (left) and dissolved oxygen (mg/L) (right) at the sediment-water interface in the western BoB
Note: Source from Suokhrie et al [10]
Tab. 1 Summary of previously reported hypoxia (O2 ≤ 2 mg/L) and OMZ (O2 ≤ 0.7 mg/L) and their proximity within the BoB
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