Concentrations of Mercury and Other Inorganic Ions in Wet Precipitation Collected from a Mountain Mining Zone and an Urban Area in Central Mexico

We measured and compared mercury (Hg) and other ions in rainwater collected in San Joaquin (mining zone) and Juriquilla (urban area), central Mexico, from 2009 to 2012. A total of 274 rainwater samples were collected and analyzed for pH, electrical conductivity, \({\text{NO}}_{3}^{ - },\;{\text{SO}}_{4}^{{2 - }},\) Cl−, \({\text{NH}}_{4}^{+},\) Na+, K+, Ca2+, Mg2+ and Hg. Mercury concentrations in rainwater varied from 24.21 to 248.89 (x-bar = 86.97 ± 10.77) µg L− 1 in San Joaquin (mining zone) and 11.26 to 176.91 (x-bar = 81.51 ± 10.24) µg L− 1 in Juriquilla (urban area). Rainwater sample were collected over periods 1–3 days, depending upon precipitation frequency. Significant correlations (p < 0.05) were found between \({\text{SO}}_{4}^{{2 - }},\) Cl−, \({\text{NO}}_{3}^{ - },\) Na+, K+, Ca2+, Mg2+ and Hg at the San Joaquin site. Significant correlations were obtained between \({\text{SO}}_{4}^{{2 - }},{\text{NO}}_{3}^{ - },\;{\text{NH}}_{4}^{+},\) Na+, K+, Ca2+, Mg2+ and Hg at the Juriquilla site. In order to determine if there were significant differences among each measured parameter in rainwater collected in San Joaquin and Juriquilla, Kruskal–Wallis test was applied to data. We emphasized that the distribution and concentrations of Hg and the studied ions in rainwater samples were affected by atmospheric dust and local meteorological conditions of wind-speed and direction.