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Enhanced transport of dust with the prevailing mid to upper tropospheric westerly winds from arid regions in South-west Asia and North-west India into the Indo-Gangetic Plain (IGP) and the influx of marine aerosol from the Arabian Sea (AS), Tropical Indian Ocean (TIO) and Southern Bay of Bengal (SBoB) into India along with the low level south-west wind flow during the onset of the South-west (SW) monsoon, 2014 was observed in campaign mode. Ambient airborne particulates (PM 2.5 and PM 10 ) were collected at 9 sites in and around IGP, India, viz. Patiala, Delhi, Lucknow, Varanasi, Giridih, Kolkata, Darjeeling, Bhubaneswar and Nagpur; over AS, TIO and SBoB providing a glimpse into the aerosol loading and its transport mechanisms. The highest average PM 2.5 (61.8 ± 18.6 μg m −3 ) and PM 10 (182.2 ± 58.0 μg m −3 ) mass concentrations were recorded at Delhi (upper IGP) and Lucknow (middle IGP) respectively. Average PM 2.5 (18.1 ± 10.1 μg m −3 ) and PM 10 (39.6 ± 15.8 μg m −3 ) levels recorded over the open oceanic regions in AS, TIO and SBoB were much lower than those observed over the land stations and the average PM 2.5 recorded over coastal AS and SBoB (49.1 ± 28.7 μg m −3 ). Cluster analysis, Potential Source Contribution Function (PSCF) and Concentration Weighted Trajectory (CWT) analysis portray that PM 2.5 and PM 10 levels at the land stations were influenced by weak to moderate contributions from AS, BoB, the arid South-west Asia and North-west India, peninsular India and from the polluted IGP region.

CSIR-CSMCRI's Chlorella variabilis (ATCC 12198) was evaluated through autotrophic, mixotrophic and heterotrophic growth for lipid production. Autotrophic growth was assessed by providing sodium bicarbonate/sodium carbonate/CO2 (air in a medium). Higher lipid productivity (115.94 mg L−1 d−1) with higher biomass productivity (724.98 mg L−1 d−1) of this strain was attained through bicarbonate and CO2 sequestration in a photobioreactor. Ability to regulate the pH in favorable bicarbonate/carbonate ratio showed its potential in alkaline effluent based carbon sequestration system for biofuel generation. The simultaneous study was also conducted to understand the effect of elevated CO2 (0.4, 1 and 1.2 g L−1) in air on the culture to assess adaptation, growth and lipid in the closed chamber conditions. It was observed that CO2 sequestration by the microalgae from the CO2 enriched environment was optimum at 1 g L−1 C. variabilis adapted to comparatively higher CO2 (1 g L−1) but grew better in low CO2 (0.4 g L−1). It was also observed that the growth, lipid content and fatty acid composition was significantly affected by CO2 supply strategies. The effect of intermittently added sodium bicarbonate at different pH on microalgal lipid content and composition of fatty acids was observed which could affect the quality of biodiesel. The effect on fatty acid composition was observed in response to carbon supply mode during the microalgal growth at different pH dictating the properties of biodiesel.

The objective of this study is to understand the fatty acid composition of a naturally floating microalgal mat with respect to seasonal variations in the water of a eutrophic lagoon on the west coast of India. The floating microalgal mat was explored for its bioaccumulation of metals and lipids for sustainable utilization in biofuel production. The effects of the nutrient profile and heavy metals in the water on the community composition of microalgal mat in different seasons were also studied and a principal component analysis was performed. It was observed that the unsaturated fatty acids such as C18:1 n 9c and C18:2 n 6c increased in low temperatures. The reverse effect was observed during the pre-monsoon season with augmented C16:0 fatty acid and an overall increment in saturated fatty acids. The Cyanophyceae and diatom community nurtured the growth during the pre-monsoon season by acquiring a higher bioaccumulation concentration factor (BCF) for Mn (3812.6 ± 680), As (90.47 ± 15.38), Ni (1620 ± 163.64), Cr (73.27 ± 21.23), and Cu (46.40 ± 11.44). The higher abundance of Cyanophyceae in the microalgal mat exhibited better metal endurance during the pre-monsoon season, which could be obviously tilized for the bioremediation of heavy metals. The biodiesel prepared from the microalgal mat met European biodiesel standards.

Heavy metal concentrations in suspended particulate matter (SPM) were investigated for their distribution and source in the atmosphere of coastal industrial town, Mithapur, Gujarat, India. SPM, at 10 locations covering three seasons, were trapped on glass fibre filters using high volume samplers and quantification of metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) was done using Atomic Absorption Spectrometry employing HNO3 based wet digestion. Results show relatively low concentrations of SPM (211.3 to 375.2 μg/m3) compared to National Ambient Air Quality Standard (NAAQS), specified By Central Pollution Control Board (CPCB, India), however, they were 2–3 times higher as compared to reference site. Among the heavy metals Cr, Mn and Pb levels were low, while Ni and Cd found to be exceeding the USEPA standards. The metal levels were also compared with those reported for other rural, coastal, industrial and urban parts around the world. Enrichment Factor analysis indicated that Cd, Zn, Cu, Pb and Ni were highly enriched relative to their crustal ratios (to Fe) and correspond to substantial contribution of anthropogenic source of these metals. The source identification was carried out by principal component analysis by applying a Varimax Rotated Component Matrix.