Distribution, occurrence, and environmental risks of heavy metals in hazardous waste: A regional study in Beijing, China

Abstract

Hazardous waste from industrial production has become a global concern because of its impact on the environment and human health. However, studies on heavy metals in regional hazardous waste are rare. Thus, this study examined 93 hazardous waste samples in Beijing in 2019, to assess the distribution, occurrence, and potential eco-environmental risks of heavy metals in such waste. The results indicated high concentrations of Zn, Cu, and Ni in hazardous waste, and the leaching toxicity of Ni (270.60 mg/L), Cu (524.1 mg/L), and Pb (136.23 mg/L) exceeded Chinese identification standards for hazardous waste. Heavy metals in hazardous waste have been primarily found in remote counties around the locations of industrial enterprises. The total amount of the heavy metals followed the order: Zn > Cu > Ni > Ba > Mn > Pb. Based on the migration abilities of their detected forms, heavy metals were classified into three categories (high, middle, and low migration abilities) to characterize their potential to enter the environment. The detected amounts of heavy metals with high and middle migration ability followed the order: Zn > Cu > Ni > Mn > Pb > Ba. The potential environmental risk of heavy metals was evaluated using the potential environmental risk index, resulting in the following ranking: Ni > Pb > Mn > Zn > Cu > Ba. Daxing District exhibited the highest total environmental risk and environmental risk per unit area, whereas Miyun District showed the highest environmental risk per secondary sector of the economy and unit of GDP. This was attributed to Beijing's industrial structure. The results of this study provide fundamental data for the management and control of hazardous waste in Beijing and are expected to aid in preventing and managing environmental risks caused by such waste.