Delhi urbanization footprint and its effect on the earth's subsurface state-of-stress through decadal seismicity modulation.

Urban land and its expansion have profoundly impacted the global environment, including the stress change in the earth's subsurface, even though urban land is a small fraction of the global land surface. Divulging such effects has never been more important, given the role of stress in determining the safety of the urban population against earthquakes. However, knowledge of this time-dependent non-linear effect of urbanization on the subsurface remains in the gray area. This study focuses on the area surrounding Delhi, the capital city of India, to understand the relative contribution of the building load created by rapid urbanization in exacerbating the subsurface state-of-stress. The results highlight that, since 2010, the modulation in the seismicity rate and the stability of basement thrust faults is linked not only to urbanization but also to decadal groundwater storage. Mounting evidence suggests that the rapid urbanization, and the resulting non-tectonic horizontal compression, stabilize faults in the Aravalli Delhi belt, which are destabilized due to the extensive groundwater extraction. This affects the decadal seismicity trend around the Aravalli Delhi fold belt. Nonetheless, the magnitude of this time-dependent deformation influence on the seismicity modulation remains uncertain. The findings from this study quantify the geomechanical impacts of urbanization in the Delhi area for the first time.

Evolution of Pollution Levels from COVID-19 Lockdown to Post-Lockdown over India.

The spread of the COVID-19 pandemic forced the administration to lock down in many countries globally to stop the spread. As the lockdown phase had only the emergency use of transportation and most of the industries were shut down, there was an apparent reduction in pollution. With the end of the lockdown period, pollution is returning to its regular emission in most places. Though the background was abnormally low in emissions (during the lockdown phase) and the reduced pollution changed the radiation balance in the northern hemispheric summer period, a modified pollution pattern is possible during the unlock phases of 2020. The present study analysed the unlock 1 and 2 stages (June-July) of the COVID-19 lockdown over India. The rainfall, surface temperature and cloud cover anomalies of 2020 for understanding the differences in pollutants variation were also analysed. The unlock phases show remarkable differences in trends and mean variations of pollutants over the Indian region compared to climatological variations. The results indicated changing high-emission regions over India to climatological variations and identified an AOD dipole with future emissions over India.

Establishing a link between fine particulate matter (PM2.5) zones and COVID -19 over India based on anthropogenic emission sources and air quality data.

The spread of coronavirus disease of 2019 (COVID-19) pandemic around the globe is affecting people. The majority of Indian urban complexes are reeling under high emissions of deadly fine particulate matter PM2.5 and resulting in poor air quality. These fine particles penetrate deep into the body and fuel inflammation in the lungs and respiratory tract, leading to the risk of having cardiovascular and respiratory problems, including a weak immune system. In the present study, we report the first national-scale study over India, which establishes a strong relationship between the PM2.5 emission load and COVID-19 infections and resulting deaths. We find a significant correlation (R2 = 0.66 & 0.60) between the states as well as districts having varied levels of PM2.5 emissions with corresponding COVID-19 positive cases respectively, and R2 = 0.61 between wavering air quality on a longer time scale and the number of COVID-19 related deaths till 5 November 2020. This study provides practical evidence that cities having pollution hotspot where fossil fuel emissions are dominating are highly susceptible to COVID-19 cases.

Quantifying the high resolution seasonal emission of air pollutants from crop residue burning in India.

Biomass burning, a recurring global phenomenon is also considered an environmental menace, making headlines every year in India with onset of autumn months. Agriculture is demographically the broadest economic sector and plays a significant role in the overall socio-economic fabric of India. Hence, disposal of crop residue is done mainly by burning leading to deterioration of air quality. Residue burning in parts of India is blamed for changing air quality in nearby cities. The spatial distribution of these emissions has always been a challenge due to various data constraints. We hereby present a comprehensive spatially resolved seasonal high resolution gridded (∼10 km × âˆ¼10 km) emission inventory of major pollutants from crop residue burning source in India for the latest year 2018. The winter months contributes almost around ∼50% of total emission followed by summer (∼48%), which is the prime cause of changing air quality in nearby cities. Among all the crops; rice, wheat, maize and sugarcane accounts ∼90% of total PM10 load in the country. The estimated emission for PM2.5, PM10, BC and OC, CO, NOx, SO2, VOC, CH4 and CO2 are found to 990.68 Gg/yr, 1231.26 Gg/yr, 123.33 Gg/yr, 410.99 Gg/yr, 11208.18 Gg/yr, 484.55 Gg/yr, 144.66 Gg/yr, 1282.95 Gg/yr, 785.56 Gg/yr and 262051.06 Gg/yr respectively. The cropping pattern and its role in different geographic regions are analysed to identify all potential emission hotspots regions scattered across the country. The developed gridded emissions inventory is envisaged to serve as an important input to regional atmospheric chemistry transport model to better quantify its contribution in deteriorating air quality in various regions of India, paving the way to policy makers to better plan the mitigation and control strategies. The developed fundamental tool is likely to be useful for air quality management.

Changing air pollution scenario during COVID-19: Redefining the hotspot regions over India.

The present study investigates the air pollution pattern over India during the COVID-19 lockdown period (24 March-31 May 2020), pre-lockdown (1-23 March 2020) and the same periods from 2019 using Moderate Resolution Imaging Spectroradiometer (MODIS) Terra aerosol optical depth (AOD) with level 2 (10 km × 10 km) and level 3 (1° × 1° gridded) collection 6.1 Dark Target Deep Blue (DT-DB) aerosol product the Tropospheric Monitoring Instrument (TROPOMI) NO2 and SO2 data with a spatial resolution of 7 km × 3.5 km. We also use long-term average (2000-2017) of AOD for March-May to identify existing hotspot regions and to compare the variations observed in 2019 and 2020. The aim of the present work is to identify the pollution hotspot regions in India that existed during the lockdown and understanding the future projection scenarios reported by previous studies in light of the present findings. We have incorporated Menn-Kendall trend analysis to understand the AOD trends over India and percentage change in AOD, NO2 and SO2 to identify air pollution pattern changes during the lockdown. The results indicate higher air pollution levels over eastern India over the coal-fired power plants clusters. By considering the earlier projected studies, our results suggest that eastern India will have higher levels of air pollution, making it a new hotspot region for air pollution with highest magnitudes.

Significant change in air quality parameters during the year 2020 over 1st smart city of India: Bhubaneswar.

Prevention of Coronavirus results in lockdown in India from 24 March 2020 to 31 May 2020. Eastern India, which is having a dense cluster of coal-fired power plants and home to many mines, mineral industries, has not shutdown power plants and coal mines during this lockdown period, though other industrial and vehicular emissions were almost zero. The present study attempts to find the change in various atmospheric pollutants during this lockdown period over an eastern tropical Indian station-Bhubaneswar, which is the first smart city proposed in smart city mission of Government of India. The study analyses hourly concentrations of PM2.5, PM10, NO X , O3, and CO for March-May 2019 and 2020. The study shows a significant increase (rather than decrease) in PM2.5 and PM10, increase in O3 and a decrease in CO and NO X during the lockdown period. Results are advocating the impact of transported pollution over the study area for maintaining the PM2.5 and PM10 values even during the lockdown situation.

Seasonal progression of surface ozone and NOx concentrations over three tropical stations in North-East India.

Monitoring of surface ozone (O3) and Nitrogen Oxides (NOx) are vital for understanding the variation and exposure impact of these trace gases over the habitat. The present study analyses the in situ observations of surface O3 and NOx for January-December 2016, for the first time over three sites of North-Eastern India (Aizwal, Gauhati and Tezpur). The sites are major cities of north-eastern India, located in the foothills of Eastern Himalaya and have no industrial impacts. We have analysed the seasonal variation of O3 and NOx and found that the site Tezpur, which is in the valley area of Eastern Himalaya, is experiencing higher values of pollutants persisting for a long time compared to the other two stations. The correlation of surface O3 with the air temperature at all three sites suggested that all the O3 may not be locally produced, but has the contribution of transported pollution reaching to stations. The study also attempts to discover the existing variability in the surface O3 and NOx over the study area by employing continuous wavelet analysis.