Abstract
Road runoff collected in a residential area in Tokyo was analyzed to determine the concentration level and their forms of heavy metals (i.e., Ni, Cu, Zn, and Pb) and inorganic nitrogen (i.e., NO2-N, NO3-N, and NH4-N). In comparison with previous literature values on highway runoff, the Ni, Cu, and Pb concentrations were to be low owing to the difference in traffic volume. However, the Zn and NO3-N concentrations were the same as the previously reported values. In the road runoff, particulate fraction was dominant to the dissolved fraction for Ni and Pb, whereas the dissolved fraction was comparable to the particulate fraction for Cu and Zn. Nitrate in road runoff was the most dominant among the various forms of inorganic nitrogen, which accounted for 80±11% of total inorganic nitrogen. Moreover, the contributions of road surface deposits and atmospheric deposition to the heavy-metal and nitrogen load in road runoff were estimated. The results showed that a larger antecedent dry period gave a larger contribution of atmospheric deposition to the heavy-metal and nitrogen load in road runoff. The contribution of road surface deposit to heavy-metal load was larger than that to nitrogen load.
