Bioindicator responses and performance of plant species along a vehicular pollution gradient in western Himalaya.

Loss of green cover, and increasing pollution is a prime global concern. The problem calls for screening of pollution-tolerant tree species that can be integrated into plantation drives. Recognizing this, the study analyzed bio-indicator responses and performance of commonly occurring plant species along a pollution gradient in western Himalaya. Based on distance from the road, three sites viz., highly polluted (HP), moderately polluted (MP), and least polluted (LP), were identified. From these sites, leaves of commonly occurring 26 tree species were collected and analyzed for dust accumulation, total chlorophyll, relative water content (RWC), ascorbic acid, and pH using standard protocols. Later, assessment of Air Pollution Tolerance Index (APTI) and Anticipated Performance Indices (API) was carried out. The results revealed variations in biochemical characteristics. The pH, RWC, and total chlorophyll increased with decreasing pollution while ascorbic acid increased with increasing pollution. Dust capturing potential of Ficus carica (1.191 mg/m2) and Toona ciliata (0.820 mg/m2) was relatively higher. Based on the results of APTI, Grevillea robusta was classified as tolerant. It scored significantly higher values (21.06, 21.19, and 19.61 in LP, MP, and HP sites, respectively). Quercus floribunda, G. robusta (68.75% each), Juglans regia (68.7%), and T. ciliata (62.50%) were good performers in HP sites. Acer caesium, Betula utilis, and Morus alba that had low API scores (43.75%) were predicted as poor performers. Thus, G. robusta, Q. floribunda, J. regia, T. ciliata, and F. carica were evaluated as best performers. They could be integrated into plantations drives for environmental management.

Geospatial distribution of metal(loid)s and human health risk assessment due to intake of contaminated groundwater around an industrial hub of northern India.

The study focused on analyzing concentrations of metal(loid)s, their geospatial distribution in groundwater around an industrial hub of northern India. Human health risk posed due to the intake of contaminated groundwater was also evaluated. For this, 240 samples were assayed using inductively coupled plasma emission spectrophotometer. For risk assessment, the methodology proposed by US Environmental Protection Agency was adopted. Geometric mean of Al, As, Mo, Cd, Co, Cr, Fe, Mn, Ni, Pb, Se, and Zn was 193.13, 27.35, 4.22, 2.85, 92.81, 14.97, 271.78, 25.76, 54.75, 19.50, 16.94, and 1830.27 µg/l, respectively. Levels of Al (84%), As (63%), Ni (63%), Pb (49%), and Se (41%) exceeded the Bureau of Indian Standards (BIS). Principal component analysis is accounted for ~ 88% of the total variance and reflected pollution loads of Al, As, Mo, Cr, Fe, Se, and Pb in the groundwater. Based on it, four sources of metal(loid)s, namely geogenic (34.55%), mixed (industrial and agricultural, 26.76%), waste dumping (15.31%), and industrial (11.25%) were identified. Semi-variogram mapping model demonstrated significant geospatial variations of the metal(loid)s. Hazard index (HI) suggested potential non-carcinogenic risks to the inhabitants due to As, Al, Ni, Se, and Pb, which were the largest contributors. Based on maximum concentrations of metal(loid)s, HI for child and adult was above unity. Arsenic was identified as the most hazardous pollutant that may have chronic carcinogenic health implications. At western side of study area, carcinogenic health risks exceeded critical threshold of 1 × 10-4, indicating that As posed health risks to residents by intake of groundwater.