The effects of road salt application on the accumulation and speciation of cations and anions in an urban environment

摘要

This study aimed to assess the quality of road runoff in heavy traffic and residential areas of Hamedan province, in the western region of Iran. To investigate the effects of salt pollution, 14 runoff samples were collected from streets during the winter and spring of 2009. Streets received different amounts of deicing salt depending on the traffic density. Results showed that deicing salt has major affects on sodium (Na~+), calcium (Ca~(2+)), magnesium (Mg~(2+)), chloride (Cl~-), bicarbonate (HCO_3~-), sulfate (SO_4~(2-)) and phosphate (PO_4~(3-)) pollution. This is important because this type of watercourse contamination can lead to serious problems, such as eutrophication. We also found an increase in lead (Pb~(2+)) concentration, which was not attributable to the application of deicing agents, but that was due to the combustion of leaded gasoline. Speciation of Ca, Mg, Pb and P chemical species in the samples was calculated using Visual Minteq 2.6 program. The results indicated that CS and Mg were mainly present as free ions, Pb was mainly present as PbCO_3 (aq), while the dominant P species were HPO_4~(2-) and H_2PO_4~-.