I also declare that the matter included in this thesis is the result of investigations carried out by me at the Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India. India, the 2nd most populous country, is identified as the 11th Mega Biodiversity Center in the world and 3rd in Asia. Therefore, this study was conducted in Assam, which is identified as one of the 200 ecoregions of the world and the most populous state of Northeast India.
Size-separated samples collected at selected sites were carefully analyzed and discussed in terms of regional deposition in the human respiratory tract using absorption and deposition curves. The concentrations of PM10 and PM2.5 at the five locations exceeded the prescribed standards of the Central Pollution Control Board (CPCB).
INTRODUCTION
- PREAMBLE
- NEED OF THE STUDY
- BROAD OBJECTIVES OF THE STUDY
- WORK PLAN
- NOVELITY OF THE STUDY
- ORGANIZATION OF THESIS
However, these health effects are determined by the size of PM due to its potential to enter human respiratory tract (Deshmukh et al., 2013a). In Indian scenario, where high concentrations of PM vary from thoracic to alveolar size fractions, wet scavenging plays a critical role (Gobre et al., 2010;. Both dry and wet deposition mechanisms are strongly size dependent whose particle removal efficiency varies with different particles sizes in several orders of magnitude (Seinfeld et al., 1998).
In addition, studies have shown that sulfur and nitrogen acidification has turned 7-17% of the world's surface in natural ecosystems into high risk (Bouwman et al., 2002). It is thus identified as one of the 200 ecoregions in the world and recognized as the center for two United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Sites (Chatterjee et al., 2006).
LITERATURE REVIEW
GENERAL
IMPROVE) and Southeastern Aerosol Research and Characterization (SEARCH) have contributed more to the fact that they issue real-time specified aerosol data (Reff et al., 2007). For this purpose, three main approaches are used: chemical transport model, receptor-oriented analysis and emission inventories and dispersion modeling (Belis et al., 2013). Among the many chemical models, the chemical mass balance (CMB) model is frequently used, although it has limitations such as the unavailability of locally determined source profiles (Watson et al., 2001).
Therefore, this chapter presents a consolidated view of the literature review based on broad objectives of the study. The chapter ends with a summary of the critical assessment of the literature and the goals formulated on the basis of the literature survey.
STUDIES ON WET DEPOSITION
The variation in the chemical composition of rainwater depends on the sources, long-range transport of air masses and meteorological conditions (Herrera et al., 2009; Kulshrestha et al., 1999; Zunckel et al., 2003). Multivariate receptor techniques are used to identify the sources and their contributions of rainwater (Qiao et al., 2018; Qiao et al., 2015a; Qiao et al., 2015b). Using PCA, three major sources, soil dust, sea salt and fossil fuel combustion, were reported as major sources influencing rainwater chemistry in Nainital, Central Himalaya, India (Bisht et al. used the PMF model from the US EPA and reported that rainwater composition was strongly influenced by soil dust (with Ca2+ as the dominant cation) and fossil fuel consumption (SO42- as the dominant anion).
In contrast to only a few previous studies (see for example (Balachandran and Khillare, 2001; Kulshrestha et al., 2014)) that witnessed acid rain events, most studies (see for example (Al-Momani et al., 1995)) ) reported the alkaline nature (pH>5.6) of rainwater due to its neutralization by airborne dust and ammonia released from natural and anthropogenic sources. Omitting the analysis of non-monsoon rainfall could lead to erroneous conclusions about rainwater chemistry (Kumar et al., 2014b).
STUDIES ON DRY DEPOSITION
- Diverse sources of PM over India
- Diverse sources of PM during episodic analysis over India
- Studies on size resolved PM in India
A study at a residential region (Deka et al., 2016), using PCA multiple linear regression (MLR), identified three main sources: biomass burning (23%), dust emissions (26%) and vehicle emissions (22%) ). Identification of the major sources for TSP using PMF revealed that dust emissions (57%), biomass burning (10%), vehicle emissions (17%) and marine source (5%) are the resolved factors (Raman et al. , 2010). Five times increase in PM10 concentration was observed during Diwali in Kolkata in Eastern India (Chatterjee et al., 2013).
4 to 10 times increase in PM10 concentrations was observed during Diwali in Nagpur in central India (Khaparde et al., 2012). Similar increase in the metals associated with fireworks burning was reported in Delhi (Sarkar et al., 2010).
CRITICAL APPRAISAL OF LITERATURE
However, very few studies have focused on assessing deposition in the human respiratory tract, limited to particulate mass, and there is not much information on deposition of chemical species and sources directly related to the cause of adverse effects on human health (Gupta and Elumalai, 2017; Nag et al., 2005). Most size-segregated PM studies have been conducted in urban areas with limited or no information at background locations determining the influence of long-range pollutant transport on the atmosphere (Chelani et al., 2010; Kumar et al., 2018 ). . Also, only limited wet deposition studies have been conducted in northeastern India, lacking analyzes during the non-monsoon period.
All other Indian cities reported alkaline nature (pH>5.6) of rainwater due to its neutralization by dust in the air, and acid rain was witnessed only in Northeast India.
OBJECTIVES AND SCOPE OF THE STUDY
Isotope analysis of collected wet deposition samples to understand the source origin of rainwater droplets during monsoon and non-monsoon seasons. Receptor-oriented analysis using PMF to understand the dominant sources and their contributions responsible for human health impacts.
SUMMARY
METHODOLOGY
- INTRODUCTION
- STUDY AREA AND SAMPLING
- Wet deposition
- Dry deposition
- CHEMICAL CHARACTERIZATION AND QUALITY CONTROL
- Trace elements and total organic carbon (TOC)
- Water soluble ions
- ISOTOPE ANALYSIS OF WET DEPOSITION SAMPLES
- ESTIMATION OF REGIONAL DEPOSITION OF SIZE RESOLVED PM IN THE
- SOURCE IDENTIFICATION
- EF analysis
- PMF analysis
- CMB analysis
- Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analysis
- SUMMARY
Wet sediment samples were collected on the roof of the building approximately 10 m from the ground and 50 cm from the roof floor. Immediately after collection, the pH was measured in an aliquot of the unfiltered sample with a digital pH meter. Method calibration and component quantification was performed using MERCK reference standards (CertiPUR) 1, 2, 5 ppm for anions and 2, 5, 10 ppm for cations.
Calibration and quantification of components was performed using MERCK reference standards (CertiPUR) 1, 2, 5 ppm for anions and 2, 5, 10 ppm for cations (https://www.merckmillipore.com) (Chaturvedi et al., 2017 ). ). In order to determine the acid neutralizing capacity of alkaline species (Ca2+, Mg2+ and K+) and check the degree of acidification due to acid rain pollution in this study region, the neutralization factor (NF) for alkaline species was calculated using Eq 1-3 (Kulshrestha et al ., 1995). For rainwater samples, isotopic analysis was performed using a 10 mL aliquot that was stored without filtration to avoid evaporative losses.
Mn is based on earth crust average abundance of the metals taken from CRC handbook (Lide, 2007). Based on the given concentration and uncertainty data, PMF provides source profiles and source contributions to each sample and the detailed description is given in the EPA PMF 5.0 guide (Norris et al., 2014). PMF uses the specified concentration (Xij) of sample 'i' and species 'j' and estimates the number of sources 'l', the source profile 'f' and the amount of mass 'g'.
The robustness of the model lies in the ability to weight each individual data point using the measured uncertainties and the appropriate method detection limit (MDL) (Hopke, 2016). The model requires the uncertainty of each of the environmental and source profile concentration data, and the error is propagated in an iterative solution that determines the contributions and their uncertainties. The model provides a number of goodness-of-fit tests such as t-statistics, chi-square and R2 to check the accuracy of the solution.
RESULTS AND DISCUSSION
- Acidity and chemical composition
- Isotope analysis
- Source identification
- Summary
RESULTS OF DRY DEPOSITON OF PM IN FIVE LOCATIONS OF ASSAM
- Seasonal variation of PM 10 and PM 2.5 concentrations
- Fractional deposition of PM in the human respiratory tract
- Source identification
- Comparison of source contributions in urban and rural sites
- Seasonal variation of source contributions of dominant sources in all the sites
- Episodic analysis at a selected location (S1)
- Comparison of sources between wet and dry depositions at a selected location
- Summary
SUMMARY OF THE THESIS
The seasonal variations in the characteristics of wet and dry PM deposits are determined in Assam, a northeastern state of India. Therefore, the determination of PM varies from region to region and therefore requires a location/region specific analysis. Therefore, the main objective of the present study is to investigate the sources of wet and dry deposits of PM in Assam.
Sized PM was collected during January 2018 to December 2018 at five locations (i.e. three urban and two rural) in Assam. Detailed chemical characterizations of both wet and dry deposits using advanced laboratory methods were performed. Also, the isotopic analysis of the collected rainwater samples was performed to locate the moisture source of raindrops.
Results obtained from chemical characterization were further used to identify the sources and their contributions using the receptor-oriented method. Critical observations and resulting conclusions are presented in this chapter, along with the limitations and expandable future scope of the current study.
MAJOR CONCLUSIONS
LIMITATIONS AND FUTURE SCOPE
5/PM10 concentrations and particle-bound polycyclic aromatic hydrocarbons in the atmospheric environment of Zonguldak, Turkey. Health Infrastructure, National Health Profile (NHP) of India–2018, Central Bureau of Health Intelligence, Government of India, New Delhi. Size distribution and seasonal variation of size-separated particulate matter in ambient air of Raipur city, India.
Water-soluble ionic composition of PM2.5–10 and PM2.5 aerosols in the lower troposphere of an industrial city of Raipur, east-central India. Seasonal air quality profile of size-segregated aerosols in the ambient air of a central Indian region. Trace metal composition of airborne particles in the coal mining and non-mining areas of Dhanbad region, Jharkhand, India.
Particulate-phase polycyclic aromatic hydrocarbons in the ambient atmosphere of a protected and ecologically sensitive area in a tropical megacity. Emissions and accumulation of metals in the atmosphere due to crackers and sparklers during the Diwali festival in India. Dynamic interaction of trace gases (VOCs, ozone and NOx) in the rural atmosphere of subtropical India.
Evaluation of particle deposition in the human respiratory tract during winter in Nanjing using size and. Source apportionment of PM10 and PM2.5 at multiple sites in the Strait of Gibraltar by PMF: impact of ship emissions. Short-term introduction of pollutants into the atmosphere at a site in the Brahmaputra basin: A case study.
Water-soluble ionic species in atmospheric aerosols: Concentrations and sources at Agra in the Indo-Gangetic Plain (IGP). Source apportionment of size-segregated atmospheric particles and the influence of particle deposition in the human respiratory tract at five sites in Assam, India.
