D. M. Chate

Reductions in India's crop yield due to ozone

This bottom-up modeling study, supported by emission inventories and crop production, simulates ozone on local to regional scales. It quantifies, for the first time, potential impact of ozone on district-wise cotton, soybeans, rice, and wheat crops in India for the first decade of the 21st century. Wheat is the most impacted crop with losses of 3.5 ± 0.8 million tons (Mt), followed by rice at 2.1 ± 0.8 Mt, with the losses concentrated in central and north India. On the national scale, this loss is about 9.2% of the cereals required every year (61.2 Mt) under the provision of the recently implemented National Food Security Bill (in 2013) by the Government of India. The nationally aggregated yield loss is sufficient to feed about 94 million people living below poverty line in India.

Premature mortality in India due to PM2.5 and ozone exposure

This bottom-up modeling study, supported by new population census 2011 data, simulates ozone (O3) and fine particulate matter (PM2.5) exposure on local to regional scales. It quantifies, present-day premature mortalities associated with the exposure to near-surface PM2.5 and O3 concentrations in India using a regional chemistry model. We estimate that PM2.5 exposure leads to about 570,000 (CI95: 320,000–730,000) premature mortalities in 2011. On a national scale, our estimate of mortality by chronic obstructive pulmonary disease (COPD) due to O3 exposure is about 12,000 people. The Indo-Gangetic region accounts for a large part (~42%) of the estimated mortalities. The associated lost life expectancy is calculated as 3.4 ± 1.1 years for all of India with highest values found for Delhi (6.3 ± 2.2 years). The economic cost of estimated premature mortalities associated with PM2.5 and O3 exposure is about 640 (350–800) billion USD in 2011, which is a factor of 10 higher than total expenditure on health by public and private expenditure.

Collection efficiencies of large water drops collecting aerosol particles of various densities

Abstract A laboratory experiment to study the effect of the density of aerosol material on collection efficiency of water drops, is conducted with MgS0 4 and MnCl 2 particles. When compared with the earlier results for NaCl and other particles, our observations show that the collection efficiency of water drops increases wish increase in impaction parameter, irrespective of whether the change in impaction parameter is caused by the change in the density of particles or the size of particles/water drop. Our results are correlated through the aerodynamical diameter parameter and with earlier experimental results of other investigators for particles of different densities. The agreement between our experimental results and the theory of Slinn (1983, Precipitation Scavenging in Atmospheric Sciences and Power Production , Chap. 11. Division of Biomedical Environmental Research, U.S. Department of Energy) increases with the increase in the density or size of the particles. Moreover, our experimental results confirm the prediction of Slinns theory that inertial impaction mechanism is dominant for smaller particles if their density is higher.

Radiative forcing of black carbon over Delhi

The radiative effects of black carbon (BC) aerosols over New Delhi, the capital city of India, for the period August 2010–July 2011, have been investigated using Santa Barbara DISTORT Atmospheric Radiative Transfer (SBDART) model in the present paper. The monthly mean BC concentrations in Delhi, an urban location, vary in between 15.935 ± 2.06 μg m−3 (December 2010)–2.44 ± 0.58 μg m−3 (July 2011). The highest value for monthly mean BC forcing has been found to be in November 2010 (66.10 ± 6.86 Wm−2) and the lowest in July 2011 (23 ± 3.89 Wm−2). Being the host city for the XIX Commonwealth Games (CWG-2010), government of Delhi set up a plan to reduce emissions of air pollutants during Games, from 03 October to 14 October, 2010. But opposite to the expectations, the emission controls implemented were not sufficient to reduce the pollutants like black carbon (BC), and therefore relatively a high value of BC radiative forcing (44.36 ± 2.4) was observed during the month of October 2010.

Large inter annual variation in air quality during the annual festival 'Diwali' in an Indian megacity.

A network of air quality and weather monitoring stations was established under the System of Air Quality Forecasting and Research (SAFAR) project in Delhi. We report observations of ozone (O3), nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter (PM2.5 and PM10) before, during and after the Diwali in two consecutive years, i.e., November 2010 and October 2011. The Diwali days are characterised by large firework displays throughout India. The observations show that the background concentrations of particulate matter are between 5 and 10 times the permissible limits in Europe and the United States. During the Diwali-2010, the highest observed PM10 and PM2.5 mass concentration is as high as 2070µg/m3 and 1620μg/m(3), respectively (24hr mean), which was about 20 and 27 times to National Ambient Air Quality Standards (NAAQS). For Diwali-2011, the increase in PM10 and PM2.5 mass concentrations was much less with their peaks of 600 and of 390μg/m(3) respectively, as compared to the background concentrations. Contrary to previous reports, firework display was not found to strongly influence the NOx, and O3 mixing ratios, with the increase within the observed variability in the background. CO mixing ratios showed an increase. We show that the large difference in 2010 and 2011 pollutant concentrations is controlled by weather parameters.

Pre- and post-monsoon variations in the magnetic susceptibilities of soils of Mumbai metropolitan region: implications to surface redistribution of urban soils loaded with anthropogenic particulates

Mumbai metropolitan region (MMR) in India represents one of the most industrialized and thickly populated areas of the monsoon dominated Asian region. We present here pre- and post-monsoon magnetic susceptibility variations in the top-soils representing sampling domains of industrial, heavy traffic and forested areas within MMR. The rock magnetic studies (including isothermal and anhysteric remanent magnetization and hysteresis loop analysis) infer predominant pseudo single domain to multi domain grains in an overall ferrimagnetic dominant mineralogy of the soils. The susceptibility-temperature variations (from −190 to 700°C) infer maghemite (γ-Fe2O3) as the chief mineral component of pedogenic origin, and the pure magnetite (Fe3O4) is of anthropogenic nature. Spatial distribution of ferrimagnetic concentration is in agreement with polluting sources. The post-monsoon redistribution pattern is greatly controlled by the surface runoff and topographic conditions. The study demonstrates that in a ferrimagnetically reach substrate like MMR, the spatial distribution patterns derived from routine concentration- and grain-size-dependent rock magnetic parameters integrated with topographic and seasonal attributes yield significant information on the style and surface re-distribution of anthropogenically loaded soils and sediments to identify its seasonal dumping. Alternatively, knowing the source of signal, the magnetic susceptibility can be further used as a robust parameter to produce detailed maps to monitor the pollutions in urban areas.

Assessments of population exposure to environmental pollutants using air quality measurements during Commonwealth Games-2010

Abstract During the “Commonwealth Games” 2010 (CWG-2010) in Delhi, the Indian government has implemented an ambitious project “System of Air quality Forecasting And Research (SAFAR)” for monitoring and forecasting air-quality scenario. Using high-precision spatio-temporal measurements of criteria pollutants from the SAFAR network, the number of cases are estimated for total, cardiovascular and respiratory mortalities and hospital admissions. In a thinly populated airport area, the excess number of cases for total mortality show ∼10 for PM2.5 and 25 for PM10, whereas, ∼110 for PM2.5 and ∼300 for PM10 in most populous Delhi University (DU) area. Cardiovascular mortality in airport area show ∼5 and <10 for PM2.5 and PM10, respectively, but, in DU area show ∼55 for PM2.5 and ∼140 for PM10. In DU locality, respiratory mortality shows ∼7 and ∼20 for PM2.5 and PM10 and, hospital admissions show ∼11 and ∼30 for PM2.5 and PM10, respectively. In airport area, excess cases of respiratory mortality and hospital admission tends to one for exposure to PM2.5 or PM10 levels indicating effective exposure is the key factor for health hazards. As public health gains, low air pollution levels were observed before the CWG due to effective washout by monsoonal rain and during CWG under policy-induced air quality measures could increase the life expectancy as against to post-CWG period. These results are important for the megacities in developing world as the SAFAR project is internationally recognized by the Global Urban Research Meteorology and Environment of the World Meteorological Organization.

Tethered balloon-born and ground-based measurements of black carbon and particulate profiles within the lower troposphere during the foggy period in Delhi, India

The ground and vertical profiles of particulate matter (PM) were mapped as part of a pilot study using a Tethered balloon within the lower troposphere (1000m) during the foggy episodes in the winter season of 2015-16 in New Delhi, India. Measurements of black carbon (BC) aerosol and PM <2.5 and 10μm (PM2.5 & PM10 respectively) concentrations and their associated particulate optical properties along with meteorological parameters were made. The mean concentrations of PM2.5, PM10, BC370nm, and BC880nm were observed to be 146.8±42.1, 245.4±65.4, 30.3±12.2, and 24.1±10.3μgm-3, respectively. The mean value of PM2.5 was ~12 times higher than the annual US-EPA air quality standard. The fraction of BC in PM2.5 that contributed to absorption in the shorter visible wavelengths (BC370nm) was ~21%. Compared to clear days, the ground level mass concentrations of PM2.5 and BC370nm particles were substantially increased (59% and 24%, respectively) during the foggy episode. The aerosol light extinction coefficient (σext) value was much higher (mean: 610Mm-1) during the lower visibility (foggy) condition. Higher concentrations of PM2.5 (89μgm-3) and longer visible wavelength absorbing BC880nm (25.7μgm-3) particles were observed up to 200m. The BC880nm and PM2.5 aerosol concentrations near boundary layer (1km) were significantly higher (~1.9 and 12μgm-3), respectively. The BC (i.e BCtot) aerosol direct radiative forcing (DRF) values were estimated at the top of the atmosphere (TOA), surface (SFC), and atmosphere (ATM) and its resultant forcing were - 75.5Wm-2 at SFC indicating the cooling effect at the surface. A positive value (20.9Wm-2) of BC aerosol DRF at TOA indicated the warming effect at the top of the atmosphere over the study region. The net DRF value due to BC aerosol was positive (96.4Wm-2) indicating a net warming effect in the atmosphere. The contribution of fossil and biomass fuels to the observed BC aerosol DRF values was ~78% and ~22%, respectively. The higher mean atmospheric heating rate (2.71Kday-1) by BC aerosol in the winter season would probably strengthen the temperature inversion leading to poor dispersion and affecting the formation of clouds. Serious detrimental impacts on regional climate due to the high concentrations of BC and PM (especially PM2.5) aerosol are likely based on this study and suggest the need for immediate, stringent measures to improve the regional air quality in the northern India.

Time-elapsed evolution of aerosol size distributions by snow particles after the passage of blizzards over the Maitri Antarctica

Measurements of the aerosol size distribution in the diameter range 0.003–20 μm were made by a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS) at Maitri (70° 45′ 52′′ S, 11° 44′ 03′′ E, Antarctica) during the 24th Indian Antarctic Expedition, which took place in January and February 2005. Time-elapsed evolutions of the aerosol size distributions on 30 January and 17 and 20 February 2005, after the passage of blizzards, were selected for estimation of the scavenging coefficient by considering the aerosol size distribution changes with snowfall over Antarctica. Scavenging efficiencies of snow particles and ice crystals collecting aerosols are obtained from the observed scavenging coefficients for 0.002–10μm aerosols. Also, theoretical snow scavenging efficiencies of snow particles and ice crystals in the diameter range 0.02–10 mm for 0.002–10 μm aerosols are determined and, thereupon, scavenging coefficients are calculated by assuming snowfall rates of 0.25 and 4 mm h−1 (in view of the reported decadal mean annual Antarctica snowfall accumulation rate of 180 mm yr−1). Snow scavenging efficiencies based on the scavenging coefficients found by considering the aerosol size distribution changes with snowfall after the occurrences of blizzards are higher than theoretical scavenging efficiencies and those of laboratory experiments for planar and columnar ice crystals. Also, the scavenging coefficients found are higher by two to three orders of magnitude than theoretical scavenging coefficients. Scavenging coefficients found from aerosol size distribution changes by snowfall after the passage of blizzards on 30 January and 17 and 20 February 2005 over Antarctica suggest that the orders of magnitude of their best estimation and the corresponding scavenging efficiencies can be viewed as being on a par with the natural snow scavenging of aerosols over this remote region.

Charge separation associated with splashing of water drops on solid surfaces

Our laboratory experiments show that the charge separation when water drops splash on a brass surface is about an order of magnitude higher than when they splash on surfaces typical of ground surface, such as soil, silica or grass on which raindrops generally splash on the earths surface. The change being separated has been observe to increase as the drop diameter increases from 3.6 to 7.0 mm. The size distribution of fragment droplets which result from a splash show that the total number of fragments is much larger when the splash occurs on brass surface as compared to that when it occurs on the soil, silica or grass surface. The results indicate that small drops in the range of 5.8 to 7.0 mm diameter are more efficient in changing the kinetic energy of the drop to electrical energy. Results of the experiment have been used to estimate the charge that is generated when raindrops splash on ground. Results of the experiment have been discussed in terms of the hardness of the target surface and the degree of violence of the splash.