Trace element characterization of fine particulate matter and assessment of associated health risk in mining area, transportation routes and institutional area of Dhanbad, India.

Samples of PM2.5 were collected on PTFE filters at 11 monitoring stations in Dhanbad, India, from March, 2014, to February, 2015, for the quantification of 10 PM2.5-bound trace elements by using ICP-OES, source apportionment by using principal component analysis and health risks posed by PM2.5-bound trace elements by using health risk assessment model developed by US EPA. The average annual PM2.5 concentration (149 ± 66 µg/m3) exceeded the national ambient air quality standards by factor of 3.7, US EPA national ambient air quality standards by factor of 10 and WHO air quality guidelines by factor of 15. The sum total of average annual concentration of all PM2.5-bound trace elements was found to be 3.206 µg/m3 with maximum concentrations of Fe (61%), Zn (21%) and Pb (11%). Coal mining, coal combustion, vehicular emission, tyre and brake wear and re-suspension of road dust were identified as dominant sources of PM2.5-bound trace elements from the results of correlation and chemometric analysis. The significantly high HQ values posed by PM2.5-bound Co and Ni and intensification of HI values (15.7, 10.8 and 8.54 in mining area, transportation routes and institutional area, respectively) for multielemental exposure indicate high potential of non-carcinogenic health risk associated with inhalation exposure. The carcinogenic health risk due to multielemental exposure in mining area (2.27 × 10-4) and transportation routes (1.57 × 10-4) for adults were significantly higher than threshold value indicating the vulnerability of adults toward inhalation-induced carcinogenic risk posed by PM2.5-bound trace elements.

Variation in effects of four OP insecticides on photosynthetic pigment fluorescence of Chlorella vulgaris Beij.

Effects of the insecticides quinalphos, chlorfenvinphos, dimethoate and phorate on photosystem activity of Chlorella vulgaris were investigated by different chlorophyll fluorescence measurements. Exposure to each of the insecticides increased the proportion of inactivated PS II reaction center. Quinalphos and chlorfenvinphos caused OJIP fluorescence reduction at all levels by decreasing the proportion of Q(A)-reducing PS II reaction centers (RCs). The other two insecticides affected OJIP fluorescence rise by hindering the electron transport beyond Q(A). Insecticide treatment resulted in decrease of the density of active RC and performance indices (PI) by enhanced dissipated energy flux per active RC. Antenna size was severely minimized by quinalphos and chlorfenvinphos treatment whereas other two insecticides had no such effect. Each insecticide treatment caused increase of photosystem antenna/core and PS II/PS I fluorescence ratios. Quinalphos and chlorfenvinphos affected the donor sides of photosystems whereas dimethoate and phorate inhibited electron transfer beyond Q(A) (acceptor side).