7-Oct-2021: Dust transport from NW India, Pakistan & Arabian Sea main aerosol sources in central Himalayan region

Mineral dust, biomass burning, secondary sulfate, secondary nitrate from northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area, and long-range transported marine mixed aerosols are the main sources of aerosols in the central Himalayan region, shows a study. This dust transport and forest fires are the main sources of total suspended particles (TSP), particularly in pre-monsoon period (March-May) when TSP concentration peaks in the region. The study on source apportionment of atmospheric pollution, which elucidates the atmospheric chemistry, emission source origins, and transport pathways of aerosol over the central Himalayan region, will help assessment of contributions and temporal variability of sources that influence the area through regional transport as well as climate impacts assessment.

With a unique role in the Asian climate, the Himalayan region is considered a vulnerable environment. Several chemical speciation studies have been performed for carbonaceous aerosols and inorganic species over the western and central Himalayan regions during the last decade, reporting the dominance of transported aerosol plumes from the Indo-Gangetic Plains. However, there is a knowledge gap regarding the primary and secondary organic carbon (POC, SOC) fractions, along with a lack of statistical methods for identifying and quantifying the sources of air pollutants at a receptor location (receptor model) in the central Indian Himalaya.

In order to address this, researchers at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, an autonomous research institute under the Department of Science and Technology (DST), Govt. of India, along with Indian and foreign collaborators, studied the chemical composition and source apportionment of total suspended particulate (TSP, which includes all the aerosols and air pollution) in the central Himalayan region. The main source regions for aerosols at this remote background location (Nainital) were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area.

The study led by Mr. Rahul Sheoran (Ph. D. Student ARIES, Nainital, India), Dr. Umesh Chandra Dumka (Scientist, ARIES, Nainital, India), along with the contributions by collaborators revealed that the main aerosol sources (factors) in Nainital were mineral dust (34%), biomass burning (27%), secondary sulfate (20%), secondary nitrate (9%), and long-range transported marine mixed aerosols (10%), exhibiting distinct seasonal patterns. There was predominance of mineral dust in spring and summer and biomass burning and secondary sulfate in winter. The transported marine mixed aerosol source was mainly associated with SW monsoon air masses during the summer season.

The results of the study published in the journal of ‘Atmosphere show that Carbonaceous aerosols (Organic Carbon (OC) and Elemental Carbon (EC) were the maximum in winter due to the intensification of biomass burning over the Indo Gangetic Plains and the Himalayas because of domestic heating and shallower mixing layer. The researchers also suggested a significant effect of biomass-burning aerosols, while the relatively high water-soluble organic carbon and significant contributions of biomass burning, secondary, or aged organic aerosols over Nainital.

3-Sep-2021: Impact of Aerosols and Clouds on Solar Energy generation leading to financial loss

A team of Indian and international researchers have found that aerosols, dust, and clouds reduce solar energy generation from photovoltaic and rooftop solar installations resulting in substantial economic impact. They estimated that the impact of total aerosol optical depth on Photovoltaic and rooftop installations amount to annual financial loss of upto 1.55 million Rupees, and the corresponding financial loss due to dust and clouds is 0.56 and 2.47 million Rupees. This estimation can help the Indian solar energy producers and the electricity handling entities for efficient transmission and distribution system operations and grid stability optimization.

Recently, solar energy generation has been widely used in developing countries such as India, which has sufficient solar resources. However, clouds and aerosols limit the solar irradiance causing performance issues in the PV and CSP plant installations. To achieve the large-scale development of a solar system requires proper planning, and there is a need to estimate the solar potential.

Researchers at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, an autonomous research institute of the Department of Science and Technology (DST) Govt. of India and National Observatory of Athens (NOA), Greece, studied the impact of aerosols and clouds on the solar energy potential over a high-altitude remote location in the central Himalayan region with analysis and model simulations.

The study published in the journal of Remote Sensing show that on an annual basis, the total aerosol attenuation for the total solar radiation incident on a horizontal surface or global horizontal irradiance (GHI) was 105 kWh m-2 and 266 kWh m-2 for direct solar radiation received from the sun or beam horizontal irradiance (BHI); respectively. The effects of the corresponding cloud are much stronger, with an attenuation of 245 kWh m-2 and 271 kWh m-2 on GHI and BHI, respectively. The scientists also calculated the annual financial loss due to this loss in energy.

The research’s led by Dr. Umesh Chandra Dumka (Scientist, ARIES, Nainital, India) along with the contributions by Prof. Panagiotis G Kosmopoulos (Scientist, NOA, Greece), Dr. Shantikumar S. Ningombam (Scientist, IIA Bangalore, India), and Akriti Masoom (Faculty, IIT Roorkee, India) provide a comprehensive investigation of the impact of aerosols and clouds on solar energy production over the region. Furthermore, this study attempts a financial loss analysis by simulating a hypothetical scenario of a PV (photovoltaic) and concentrated solar power (CSP) system with nominal power of 1 MW assumed to be installed in the central Himalayan region.

The scientists are now planning to connect the solar energy production levels and distribution with the consumption at selected local administrative units across India and quantify the aerosol and cloud effects into the solar forecasting and energy trading principles for a decentralized energy ecosystem.

11-Jun-2021: Aerosol particles below 3 nm which can reach sizes having climatic impacts, formed frequently in urban locations in India

Scientists tracing the concentration, size and evolution of aerosol particles smaller than 3 nanometres at an urban location in India have found frequent formation of sub-3nm aerosol particles in the atmosphere. This has critical importance as a major fraction of these newly formed particles can reach to sizes of cloud condensation nuclei where they have climatic impacts.

The formation of small molecular clusters of sub-3nm size is technically called aerosol nucleation, and subsequent growth of these newly formed clusters to the large sizes is called atmospheric new particle formation (NPF). NPF occurs everywhere in the terrestrial troposphere, and therefore it is a large source of aerosol numbers to the atmosphere. Though extensively studied globally using field observations, laboratory experiments and modelling approach, it is largely unexplored in India.

Scientists from the University of Hyderabad measured neutral sub-3nm particles for the first time at an urban location in India. Dr Vijay Kanawade and Mr. Mathew Sebastian used AIRMODUS nano Condensation Nucleus Counter (nCNC) to measure particle size distribution in the size range of 1 to 3 nm.

In the study supported by the Department of Science & Technology (DST) under Climate Change Programme Division, they conducted continuous observations since January 2019 at the University of Hyderabad campus site and reported the formation rate of small molecular clusters in sub-3nm size regime, where aerosol nucleation triggers. This work has been recently published in the journal ‘Atmospheric Environment’.

The research showed that a pool of sub-3nm particles is often present in the atmosphere, but how fast these clusters grow depends on various factors. The scientists observed that only half of these events showed newly formed molecular clusters growing past 10 nm size. Thus particle size distributions display a conventional banana-shaped aerosol growth, which is indicative of regional NPF event.

The team found a strong positive correlation between sub-3nm particle concentrations and sulphuric acid concentrations, confirming the potential role of sulfuric acid in the formation of sub-3nm particles. While NPF often starts with sulphuric acid in the atmosphere, sulphuric acid alone fails to explain observed particle formation and growth rates in the atmosphere. Other vapours such as ammonia, amines and organics play a crucial role in the growth of newly formed particles. Moreover, these newly formed particles did not always grow to large sizes, and the team hypothesized that the particle growth was limited by lower concentrations of condensable vapours such as organic compounds, calling for research using state-of-the-art instrumentation to understand the mechanisms driving NPF in diverse environments across India. 

5-Jun-2020: Aerosol characterization and radiative effects at High Altitude site in Western-Trans Himalayas

Researchers at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital an autonomous research institute under the Department of Science and Technology (DST) Govt. of India have found that aerosol radiative forcing larger than the global averages, implying some amount of radiative effects, in spite of the clean atmosphere over the trans-Himalayas. The paper under publication in the journal Science of the Total Environment shows that monthly-mean atmospheric radiative forcing of aerosols leads to heating rates of0.04 to 0.13 C day-1.  Further, the temperature over the Ladakh region is increasing 0.3 to 0.4 degrees Celsius per decades from the last 3 decades.

The atmospheric aerosols play a key role in the regional/global climate system through scattering and absorption of incoming solar radiation and by modifying the cloud microphysics. Despite the large progress in quantifying the impact of different aerosols on radiative forcing, it still remains one of the major uncertainties in the climate change assessment. Precise measurements of aerosol properties are required to reduce the uncertainties, especially over the oceans and high altitude remote location in the Himalayas where they are scarce.

The study led by Dr. Umesh Chandra Dumka (Scientist, ARIES, Nainital, India) along with contributions by Dr. Shantikumar S. Ningombam (Scientist, IIA, Bangalore, India), Dr. Dimitris G. Kaskaoutis (Scientist, National Observatory of Athens, Greece), Dr. B. L. Madhavan (Scientist, National Atmospheric Research Laboratory, India) and other team members analysed the variability of aerosol optical, physical and radiative properties from January 2008 to December 2018 and the role of fine and coarse particles in aerosol radiative forcing (ARF) assessment. ARF is the effect of anthropogenic aerosols on the radiative fluxes at the top of the atmosphere and at the surface and on the absorption of radiation within the atmosphere.

The observations of the scientists show that the aerosol optical depth (AOD) exhibited a distinct seasonal variation with higher values (0.07) in May and lower (0.03) in winter months. The lower values of Ångström exponent (AE) in spring indicated dominance of coarse-mode dust aerosols. An aerosol classification based on FMF and SSA revealed a dominance of medium-sized mixed aerosols over the Hanle and Merak, especially in Spring (53%). Pure and polluted dust exhibited fractions between 16% and 23%, with a low frequency of less than 13% of absorbing aerosols, denoting weak influence of anthropogenic aerosols and Black Carbon over the trans-Himalayan sites.  Further, the aerosol radiative forcing ARF values at top of the atmosphere were mostly low (-1.3 Wm-2) over Hanle and Merak.

"A deep scientific study of aerosol generation, transport, and its properties have important implications in our understanding and mitigation of climate change via atmospheric warming, which among many things, impacts the snow and glacier dynamics over the trans-Himalayan region," said Prof Ashutosh Sharma, Secretary, DST.

The results from the study can help better understanding the aerosol optical and microphysical properties and improving the modeling of aerosol effects in view of aerosol-climate implications via modifications in atmospheric warming and changes in the snow/glacier albedo over the trans-Himalayan region.

Measurements of aerosol optical and microphysical properties started during the last decade at the Indian Astronomical Observatory (IAO) at the high altitude background sites of Hanle and Merak in the trans-Himalayas under the frameworks of Aerosol Radiative Forcing over India (ARFI) and Astronomical Site Survey program of Indian Institute of Astrophysics (IIA), Bangalore. In addition to this, few in-situ measurements of carbonaceous aerosols and ionic species have also been performed at Himansh Observatory (Spiti Valley) in the western Himalayas.

The transport of light-absorbing carbonaceous aerosols and dust from the polluted Indo-Gangetic Plain and desert areas over the Himalayas constitutes a major climatic issue due to severe impacts on atmospheric warming and glacier retreat. This heating over the Himalayas facilitates the “elevated-hat pump” that strengthens the temperature gradient between land and ocean and modifies the atmospheric circulation and the monsoon rainfall. A better understanding of the aerosol optical and microphysical properties through the study can improving the modeling of aerosol effects in view of aerosol-climate implications via modifications in atmospheric warming and changes in the snow/glacier albedo over the trans-Himalayan region.

27-Jul-2021: Measures Adopted To Reduce Pollution during Coal Transportation & To Check Illegal Mining of Coal

Coal mining operations have some impact on environment in terms of change in land use pattern, dust, air, water and noise pollution. It is mandatory for all projects of CIL to get the Environmental Management Plan (EMP) approved by the competent authority before commencing the mining operations. A detailed Environment Impact Assessment (EIA) is carried out for each project considering pre and post mining conditions for preparing EMPs which are discussed in detail by the Environmental Appraisal Committee (EAC) of experts under MoEF&CC. On the basis of the discussions, EAC recommends the case and accordingly Environment Clearance (EC) is granted by the MoEF&CC. While granting EC, MoEF&CC stipulates conditions/ mitigation measures for implementing the EMPs which have to be complied with by the project proponents. On obtaining EC, the project proponent also secures Consent to Establish (CTE) and Consent to Operate (CTO) under the provisions of Water and Air Acts from the concerned State Pollution Control Boards (SPCB). During the course of implementation of the project, the compliance of the conditions laid in the EC is being monitored through regional offices of MoEF&CC, SPCBs and internally by coal companies. Measurements of pollutant levels for coal mines as enumerated in GSR 742 (E) dated 25.09.2000 is implemented and the report so generated is sent to regional offices of MoEF&CC and SPCB. Further, Ministry of Railways has issued guidelines/directions to all Zonal Railways in April 2018, for action to be taken with regard to handling of pollution intensive commodities at sidings and goods sheds in accordance with the provisions of State Pollution Control Board.

The following control measures adopted by CIL for Air Pollution caused due to transportation of Coal:

1. Low capacity tippers (10-12 Tonne) are progressively being replaced by large tippers (35 tonne) to reduce the number of trips resulting in reduction in air pollution levels.
2. Roads are black-topped, coal carrying trucks are optimally loaded and covered with tarpaulin.
3. Mobile water sprinklers are deployed along the haul roads;
4. Projects have started implementing effective methods for dust control on roads by deploying Road sweeping machines. Wheel washing is also being progressively implemented in mines.
5. Quantum of coal transported by conveyors as part of First Mile Connectivity (FMC) projects to siding is being continuously increased to minimise generation of dust due to road transportation.
6. Tree plantation:
   1. Plantation on inactive OB Dumps is done to minimize soil erosion;
   2. Tree Plantation is done around the source of air pollution like mine, infrastructure and roads to reduce air pollution;
   3. Green belt has been provided around the mine as well as residential colony for noise attenuation;

Keeping above objectives in view, extensive tree plantation programme is undertaken every year by the coal companies. CIL has planted more than 94 lakh of saplings over an area of about 3,873 Ha in inside mine lease area and around 7.13 lakh saplings over an area of about 500 Ha in outside mine lease area during last five years i.e. from FY 2016-17 to FY 2020-21.

CIL has taken steps to augment the mechanized coal transportation and loading system under 'First Mile Connectivity' projects. In Phase-I, 35 projects are being implemented for a capacity of 414.5 MTPA. On commissioning of the same, a huge quantum of road transport will be eliminated, thereby leading to reduced air pollution & CO2 emissions.

Illegal mining of coal is reported to be carried out mainly from abandoned mines, shallow coal seams situated at remote/isolated places from the mines and are scattered over a large area. It is a Law & Order problem which is a State subject, hence primarily; falls under the domain of the State/District administration to take necessary deterrent action to stop/curb illegal mining of coal.

The Management of Subsidiary Companies lodges FIR with local Thana to take necessary action.

Following steps are taken by Coal India Limited to check Illegal mining of coal:

1. Concrete walls have been erected on the mouth of the abandoned mines to prevent access and illegal activities in these areas.
2. Surprise raids/checks being conducted jointly by security personnel and law and order authorities of the concerned State Government.
3. Dumping of the overburden is being done on the outcrop zones.
4. Installation of check-posts at vulnerable points.
5. Training of existing security/CISF personnel, refresher training and basic training of new recruits in security discipline for strengthening the security setup;
6. Maintaining close liaison with the State authorities.
7. Committee/task force has been constituted at different level (block level, sub-divisional level, district level, state level) in some subsidiaries of CIL to monitor different aspects of illegal mining.

The Government of India has launched one mobile app namely “Khanan Prahari” and one web app Coal Mine Surveillance and Management System (CMSMS) for reporting unauthorized coal mining activities so that monitoring and taking suitable action on it can be done by Law & Order authority.