Chemical characterization of road dust during diwali festival in Guwahati city of Assam, Northeast India.

The present study focuses on the elemental analysis of road dust in Guwahati, the largest city of Assam and the largest metropolis of Northeast India during the Diwali festival. Road dust samples were collected on pre-Diwali (PD), the Day after Diwali (DaD), and one week after Diwali (WaD) from two sites (Lankeshwar; LKW and Patharquarry; PTQ). Three composite samples were collected from 3 points at each site. The elemental concentration was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of Ba and Sr increased by 1.6 and 1.7 times, respectively, after Diwali. Among other firework-related elements (FREs), Mg, Al, K, and Cu increased at LKW following Diwali (both DaD and WaD), whereas Mg, Al, and K increased in DaD dust at PTQ. The average concentration of Traffic Related Elements (TREs) at PTQ was significantly higher than at LKW (p < 0.05; 75.40 mg/kg vs 63.96 mg/kg). Cd had the highest enrichment (EF), followed by Ni and Zn. EF for Cd, Ni, and Zn ranged from high to extremely high enrichment. Ni and Cd exhibited moderate contamination (CF). The ecological risk (ER) values for Cd at LKW and PTQ were 54.32 and 56.71, respectively, indicating a moderate ER. Pearson's correlation was performed to study the relationship between elements, while PCA analysis was used to identify the main sources of these elements. Although the health hazard indices presently do not suggest any immediate danger, hazard quotient (HQ) values for ingestion, inhalation, and dermal exposure were higher for children than adults. In children, the contribution of HQing to HI (total risk) was the highest, accounting for more than 65% of all elements. There is no apparent lifetime cancer risk due to road dust exposure through inhalation.

Particulate matter exposure in biomass-burning homes of different communities of Brahmaputra Valley.

Biomass burning for cooking prevalent in the developing countries is an issue which has been a concern for the past several decades for the noxious emissions and subsequent effects on the health of women and children due to the exposure of particulate matter (PM) and other gases. In this study, PM (PM1, PM2.5, and PM10) were measured in biomass-burning households for different communities of Brahmaputra Valley region northeast India by a 31-channel aerosol spectrometer. The levels of emission of PM in the case of different community households were found to be significantly different. Also, the emission characteristics of different cooking time of the day were found to be different across communities. The emission levels in the biomass-burning households were compared with emission in household using "clean" LPG fuel, and it was found that the biomass fuels emitted 10-12 times more PM2.5 and 6-7 times more PM10. The number densities of the emission were found to be more with smaller sizes of particulates which could explain why such biomass-burning emissions can pose with greater health risks. The exposure doses were calculated and were found to be about three times higher in biomass-burning houses than "clean" LPG fuel. It is important to note that the exposure from biomass burning while cooking has a gender perspective. The woman of the house generally takes care of the activities in the kitchen and get exposed to the noxious PM and the gases. Children often accompany their mothers and face the same fate.

Trace metals in indoor dust from a university campus in Northeast India: implication for health risk.

This study reports concentrations of trace metals and the associated health risks in settled dust of different microenvironments of a university in Northeast India. Settled dust samples were collected from the most accessible indoor locations by the students of Tezpur University, a rural-residential university of mid Brahmaputra Valley of Assam. Collected samples were digested in an aqua regia-assisted microwave digestion system and analyzed for iron (Fe), nickel (Ni), zinc (Zn), cadmium (Cd), and lead (Pb) using atomic absorption spectroscopy (AAS). The highest concentration was obtained for Fe with a mean value of 1353.51 ± 123 mg/kg. Cadmium showed the lowest concentration with a mean value of 0.75 ± 0.57 mg/kg. Cadmium was the highly enriched element followed by Pb, Zn, and Ni. The metals mostly fall in the "extremely high enrichment" category. The study revealed that infiltrated soil or street dust, eroding wall paints, and automotive sources were the main contributing sources of the metals. The calculated Hazard Index (HI) value, 0.39, was lower than the acceptable HI value of 1 indicating no significant non-cancer risk to the students from exposure to these heavy metals at present. The study also found no carcinogenic risk on exposure to the metals present in the indoor dust samples.

Chemical characterization and source apportionment of aerosol over mid Brahmaputra Valley, India.

Aerosol samples (as PM10, n = 250) were collected from three rural/remote receptor locations in the mid Brahmaputra plain region and were chemically characterized for metals (Al, Fe, Co, Cu, Cr, Cd, Mn, Ni, Pb), ions (Ca2+, Mg2+, Na+, K+, NH4+, F-, Cl-, NO3-, SO42-), and carbon. Vital ratios like NO3-/SO42-, EC/OC, K+/EC, K+/OC, enrichment factors and inter-species correlations were exploited to appreciate possible sources of aerosol. These empirical analyses pointed towards anthropogenic contributions of aerosol, particularly from biomass burning, vehicular emission, and road dust. The chemically characterized concentration data were subsequently fed into two receptor models viz. Principal Component Analysis-Multiple Linear Regression (PCA-MLR) and Chemical Mass Balance (CMB) for apportionment of sources of aerosol. The PCA-MLR estimates identified that the combustion sources together accounted for ∼42% of aerosol and the contribution of secondary formation to be 24%. Road and crustal dusts have been well apportioned by PCA-MLR, which together accounts for ∼26% of the aerosol. The CMB model estimates explained that the combustion sources taken together contributed ∼47% to the aerosol, which includes biomass burning (27%), vehicular emission (13%), coal (1%), kerosene (4%), and petroleum refining (2%). Other major sources that were apportioned were road dust (15%), crustal dust (26%), and construction dust (6%). There are inherent limitations in the source strength estimations because of uncertainty present in the source emission profiles that have been applied to the remote location of India. However, both the models (PCA-MLR and CMB) estimated the contribution of combustion sources to 42 and 47% respectively, which is comparable.