Chemistry and buffering capacity of fog water collected in and around New Delhi, India.

Abstract

In this study, fog water samples collected from New Delhi and its satellite township Sonipat for 2years 2015-16 and 2016-17 are characterized by soluble ions and internal buffering capacity. The pH of fog water is close to 5.6 due to the limited contributions of Ca2+ and Mg2+ ions by virtue of low wind speed during winters. NH4+ and Ca2+ were dominant cations in fog at both sites during both sampling years. NH4+ and Ca2+ contributions were similar in New Delhi during 2015-16, but Ca2+ increased during 2016-17 on account of construction activities. Emissions from agriculture fields through fertilizer applications and animal breeding lead to an increase of NH4+ compared to Ca2+ at Sonipat. SO42- was comparable with Cl-, followed by NO3- ions. Plastic burning in this region during wintertime was a possible source of Cl- ions. Acid neutralization decreases as NH4+ > Ca2+ and Mg2+ for all samples in Sonipat and as Ca2+ > NH4+ and Mg2+ in New Delhi. Higher NO3- in New Delhi was due to vehicular emissions. Vehicular emissions in New Delhi and agriculture fields in Sonipat were dominant sources of organic acids. Observed internal buffering capacity was different than theoretical values over a pH range from 4 to 7 in New Delhi, whereas both buffering capacities were close to each other in Sonipat samples. Lead in fog water at both sites was higher than prescribed safe limits for drinking water. Pollution sources were responsible for higher concentrations of metals, organic acids, and soluble ions in fog in New Delhi compared to that in Sonipat.