Chemical composition monitoring of tropical rainwater during an atypical dry year

• The effects of a dry year on the rainwater were investigated in Southeast Brazil.
• The samples characteristics were associated with the influence of air masses.
• Rainwater chemical composition was studied on the driest year in the last 10 years.
• Samples from dry season period presented higher analytes concentrations.

The effects of an atypical dry year on the rainwater chemical composition were investigated. Conductivity, pH, major inorganic ions (Na+, K+, Mg2 +, Ca2 +, H+, Cl−, NO3−, SO42 − and HCO3−) and trace-elements (As, Cd, Cu, Mn and Pb) were determined in 53 rainwater samples, which were collected on a daily basis over 12 months, in a meteorological station from Juiz de Fora city, Southeast Brazil. The rainwater conductivity ranged from 3.9 a 46.5 μS cm− 1 and the pH ranged from 5.04 to 7.10. The analytes concentrations decreased in the following order: Ca2 + > Na+ > K+ > Mg2 + > H+ for cations, NO3− > Cl− > HCO3− > SO42 − for anions and Cu > Mn > Pb > Cd > As for trace-elements. In general, higher analytes concentrations were observed during the dry season. The total annual rainfall in 2014 was 964.4 mm. This value is significantly lower than the historic annual mean of Juiz de Fora, which is 1550 mm. Therefore, the year 2014 was characterized as a very dry year.