Abstract

The strict lockdown measures not only contributed to curbing the spread of COVID-19 infection, but also improved the environmental conditions worldwide. The main goal of the current study was to investigate the co-benefits of COVID-19 lockdown on the atmosphere and aquatic ecological system under restricted anthropogenic activities in South Asia. The remote sensing data (a) NO₂ emissions from the Ozone Monitoring Instrument (OMI), (b) Aerosol Optical Depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS), and (c) chlorophyll (Chl-a) and turbidity data from MODIS-Aqua Level-3 during Jan–Oct (2020) were analyzed to assess the changes in air and water pollution compared to the last five years (2015–2019). The interactions between the air and water pollution were also investigated using overland runoff and precipitation in 2019 and 2020 at a monthly scale to investigate the anomalous events, which could affect the N loading to coastal regions. The results revealed a considerable drop in the air and water pollution (30–40% reduction in NO₂ emissions, 45% in AOD, 50% decline in coastal Chl-a concentration, and 29% decline in turbidity) over South Asia. The rate of reduction in NO₂ emissions was found the highest for Lahore (32%), New Delhi (31%), Ahmadabad (29%), Karachi (26%), Hyderabad (24%), and Chennai (17%) during the strict lockdown period from Apr–Jun, 2020. A positive correlation between AOD and NO₂ emissions (0.23–0.50) implies that a decrease in AOD is attributed to a reduction in NO₂. It was observed that during strict lockdown, the turbidity has decreased by 29%, 11%, 16%, and 17% along the coastal regions of Karachi, Mumbai, Calcutta, and Dhaka, respectively, while a 5–6% increase in turbidity was seen over the Madras during the same period. The findings stress the importance of reduced N emissions due to halted fossil fuel consumption and their relationships with the reduced air and water pollution. It is concluded that the atmospheric and hydrospheric environment can be improved by implementing smart restrictions on fossil fuel consumption with a minimum effect on socioeconomics in the region. Smart constraints on fossil fuel usage are recommended to control air and water pollution even after the social and economic activities resume business-as-usual scenario.

摘要

严格的封锁措施不仅有助于遏制COVID-19感染的蔓延，而且还改善了全世界的环境条件。本研究的主要目的是调查在南亚人为活动受限的情况下，COVID-19锁定对大气和水生生态系统的共同好处。遥感数据（a）NO ₂臭氧监测仪（OMI）的排放，（b）中分辨率成像光谱仪（MODIS）的气溶胶光学深度（AOD），以及（c）MODIS-Aqua Level-3的叶绿素（Chl-a）和浊度数据分析了1月至10月（2020年）与过去五年（2015年至2019年）相比空气和水污染的变化。还使用2019年和2020年的陆上径流和降水量每月调查一次空气和水污染之间的相互作用，以调查异常事件，这可能会影响到沿海地区的氮负荷。结果表明，空气和水污染显着下降（NO ₂减少30–40％排放量，AOD的45％，沿海Chl-a浓度下降了50％，浊度下降了29％）。拉合尔（32％），新德里（31％），艾哈迈达巴德（29％），卡拉奇（26％），海得拉巴（24％）和金奈（17％）的NO ₂排放减少率最高。在2020年4月至6月的严格锁定期内。AOD与NO ₂排放量（0.23-0.50）之间呈正相关，意味着AOD的减少归因于NO ₂的减少。据观察，在严格锁定期间，卡拉奇，孟买，加尔各答和达卡沿海地区的浊度分别降低了29％，11％，16％和17％，而浊度则提高了5–6％在同一时期在马德拉斯上空被看到。研究结果强调了减少化石燃料消耗以及减少氮与空气和水污染之间关系的重要性。结论是，可以通过对化石燃料消耗实施明智的限制来改善大气和水圈环境，而对该区域的社会经济影响最小。即使在社会和经济活动恢复正常后，仍建议对化石燃料的使用采取明智的限制措施，以控制空气和水的污染。