CSIR-National Institute of Oceanography, 176 Lawsons Bay Colony, Visakhapatnam, 530017, India.
ESSO-National Centre for Coastal Research, Chennai, India.
Environ Sci Pollut Res Int. 2021 Oct;28(39):55202-55219. doi: 10.1007/s11356-021-14703-x. Epub 2021 Jun 15.
Perennial increase in atmospheric pollution over the Bay of Bengal (BoB) and South China Sea is reported due to increase in human population and industrial activity in South and Southeast Asia. Based on total aerosol optical depth (AOD) derived from MODIS (moderate resolution imaging resolution imaging spectroradiometer), natural and anthropogenic fractions were derived. The seasonality and spatial variability in rate of increase in total, natural, and anthropogenic AOD fractions were examined over the BoB using data collected between 2001 and 2019. Both total and anthropogenic AOD displayed statistically significant rate of increase in the northwest BoB (NWB) and western coastal BoB (WCB) regions during 2001 to 2019 whereas the long-term changes are insignificant in the other regions of BoB. Significant increase in AOD in the NWB and WCB regions is mainly contributed by dominant outflow of anthropogenic emissions from Indo-Gangetic Plain (IGP) area of Indian subcontinent. The magnitude of AOD decreased by half from northern BoB to equatorial region due to increase in distance from the source region. The contribution of anthropogenic AOD was >70% to total AOD with higher contribution during winter and lower during summer. The rate of increase in both total and anthropogenic AOD was close to 0.104 and 0.099 per decade in the NWB and 0.069 and 0.059 per decade in the WCB region between 2001 and 2019. The rate of increase in total and anthropogenic AOD decreased from 2001-2009 (0.164 and 0.115 per decade respectively) to 2010-2019 (0.068 and 0.076 per decade respectively) in the NWB region. Significant increase in anthropogenic AOD by 50 and 30% was observed during El Niño and La Niña periods respectively than normal year in both northwest BoB (NWB) and western coastal (WCB) regions due to change in strength and direction of winds. Although some fraction of anthropogenic AOD is found over the entire BoB, significant rate of increase in anthropogenic AOD is found only about 23% of the area of BoB than hitherto reported as entire BoB. The impact of atmospheric deposition of anthropogenic aerosols on biogeochemical processes, such as primary production and ocean acidification, needs further evaluation.
据报道，由于南亚和东南亚人口增长和工业活动的增加，孟加拉湾（BoB）和南海的大气污染常年增加。本研究基于 MODIS（中等分辨率成像光谱仪）获得的总气溶胶光学深度（AOD），推导了自然和人为分数。利用 2001 年至 2019 年收集的数据，研究了 BoB 地区总、自然和人为 AOD 分数的季节性和空间变化率。在 2001 年至 2019 年期间，BoB 的西北（NWB）和西部沿海（WCB）地区的总 AOD 和人为 AOD 均呈现出统计学上显著的增长率，而 BoB 其他地区的长期变化则不显著。在 NWB 和 WCB 地区，AOD 的显著增加主要归因于印度次大陆印度-恒河平原（IGP）地区人为排放的主导流出。由于距离源区的增加，从 BoB 的北部到赤道地区，AOD 的幅度减少了一半。人为 AOD 对总 AOD 的贡献率>70%，在冬季贡献较高，夏季较低。在 NWB 和 WCB 地区，2001 年至 2019 年间，总 AOD 和人为 AOD 的增长率均接近 0.104 和 0.099 每十年和 0.069 和 0.059 每十年。在 NWB 地区，总 AOD 和人为 AOD 的增长率从 2001-2009 年（分别为 0.164 和 0.115 每十年）下降到 2010-2019 年（分别为 0.068 和 0.076 每十年）。在 NWB 和 WCB 地区，厄尔尼诺和拉尼娜期间人为 AOD 分别比正常年份增加了 50%和 30%，这是由于风的强度和方向发生了变化。尽管在整个 BoB 地区都发现了人为 AOD 的一部分，但与迄今为止报道的整个 BoB 相比，仅在 BoB 约 23%的地区发现了人为 AOD 的显著增长率。需要进一步评估人为气溶胶大气沉降对生物地球化学过程（如初级生产和海洋酸化）的影响。
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