Wet Deposition of Mercury and Dissolved Organic Carbon during Pre-Monsoon and Monsoon Periods at Sitapuri Site in Delhi (India)

Abstract

This rainwater chemistry study was carried out during monsoon and pre-monsoon seasons in 2018. The rainwater samples were collected in the residential area of Sitapuri which is situated the southwest zone of city Delhi. The rainwater samples were collected with the help of the funnel and bottle assembly on event basis. To refrain any contamination from the ground, the assembly was mounted at 5m above the ground level on a terrace. The assembly was always installed on the onset of rain and retrieved soon after the rain stopped. The collected samples were filtered. The samples were analyzed for Mercury (Hg0), Total Nitrogen (TN) and Dissolved Organic Carbon (DOC). The Hg(o) determination was done using Differential Pulse Anodic Stripping Voltammetry through standard addition methods and DOC species and TN species were determined using DOC/TN analyzer (Shimadzu model LCPH/CPN). The average concentration of Hg0 was recorded as 54.9 μg/l, while that of DOC and TN as 160.2 mg/l and 12.6 mg/l respectively. The study indicated that Hg0 and DOC were not contributed by common emission sources. Also, the study indicated that pre-monsoon air was more contaminated with Hg (0), TN and DOC as compared to the monsoon season.