Toxicity of artificial runoff fostered with dry deposition particulates from industrial, commercial, and highway area in Gwangju, Korea

The adverse effects of rainwater and artificial urban runoff (an imitation of urban runoff during rainfall event) were investigated using a battery of bioassays employing three test species. Urban dusts were collected at three representative sites; commercial, industrial and highway areas. The water quality parameters of rainwater and artificial runoff revealed low hardness (23.4 ∼ 34.2 mg·L⁻¹ as CaCO₃) and alkalinity (7.0 ∼ 34.2 mg·L⁻¹ as CaCO₃). High toxicities were observed in the bioassays for the artificial runoffs. The average toxic units for D. magna, S. capricornutum, and O. latipes were 1.26(±0.84), 1.34(±1.10) and 2.05(±1.08), respectively. Of these species, O. latipes revealed significantly higher toxicity compared to D. magna and S. capricornutum (p<0.05). Embryo lesions were observed with 6.25% treatments, and these significantly increased at 12.5% treatments (p<0.05). The EC₅₀ values for each artificial runoff were 22.5, 22.6 and 25.4% for commercial, industrial and highway areas, respectively. With 12.5% treatment, significant delays in hatching times were observed (p<0.05); all embryos tested did not hatched at 100% treatment. Similarly, a significant decrease in hatching success was observed at every sampling point from 25% treatment (p<0.05). The adverse effects of artificial runoff on the three test species suggests that urban surface runoff can cause significant impairment in aquatic ecosystems.