Investigation and Risk Assessment of Petroleum Hydrocarbon and COD_Cr Pollution in a Residential Area

Through the investigation and analysis of the pollution route and soil pollution status in a residential block, it was determined that the indicators exceeded the standard in the block including COD_Cr, chroma and petroleum hydrocarbon (C₁₀-C₄₀). The distribution of exceeding the standard points gradually spread to the periphery with the suspected seepage pit as the center, and the concentration changes from high to low with this trend. According to the investigation results of soil pollution in this block, through the analysis and research of hazard identification, exposure assessment, toxicity assessment and risk characterization, it was considered that the over-standard indicators in the block included petroleum hydrocarbon (C₁₀-C₄₀), COD_Cr and chromaticity. The petroleum hydrocarbons (C₁₀-C₁₂ and C₁₃-C₁₆), which exceed the standard pollutants in groundwater, can bring health risks to human body. Hence, this block needed to be repaired. COD_Cr and chroma indicators in groundwater have no health risks, but their exceeding standards were caused by suspected seepage pits. Based on environmental hazards and risks, they should be treated in the same time.