基于BP神经网络的北京城区公园土壤PAHs含量预测

Prediction of Polycyclic Aromatic Hydrocarbons(PAHs)Content in Soil of Urban Parks in Beijing Based on BP Neural Network

城市公园是城市生态环境的重要组成部分,其环境质量与人类健康息息相关.选择北京市121个城区公园,采集公园土壤样品并分析其中7种多环芳烃(PAHs)含量,评价城区公园土壤中PAHs的含量水平,并基于BP神经网络预测了2020年和2023年土壤PAHs含量.结果表明:北京城区公园土壤中w(PAHs)(7种PAHs总含量)范围为0.033~4.182 mg kg,低于GB 36600-2018《土壤环境质量建设用地土壤污染风险管控标准(试行)》土壤污染风险筛选值,且7种PAHs的毒性当量浓度(TEQ)均低于世界卫生组织标准值(1 mg kg),对人体健康的毒性风险较小.将14个影响指标(8个社会经济因子与6个公园特征因子)作为输入层、土壤w(PAHs)作为输出层,建立BP神经网络的拟合优度达0.845.预测结果显示,2020年和2023年北京城区公园土壤中w(PAHs)范围分别为0.008~0.969 mg kg和0.022~1.988 mg kg,整体均低于GB 36600-2018土壤污染风险筛选值,但随时间推移呈上升趋势,尤其朝阳区和海淀区将有大幅增长.研究显示:城市化发展因素对土壤w(PAHs)的增加有明显影响,城市发展进程影响不容忽视;至2023年,北京城区公园土壤若不加管理,其w(PAHs)将持续增长.

Urban parks are an important part of the urban ecological environment.The environmental quality of parks is related to human health.The soil samples from 121 parks in Beijing were collected and the contents of 7 polycyclic aromatic hydrocarbons(PAHs)were analyzed.It order to evaluate the contents of PAHs,the PAHs contents in 2020 and 2023 were predicted based on the BP neural network.The results showed that the 7 PAHs in the soil in Beijing urban parks ranged from 0.033 to 4.182 mg kg,which was lower than the soil pollution risk screening values in the Soil Environmental Quality Risk Control Standard for Soil Contamination of Development Land(GB 36600-2018).The toxic equivalent concentration(TEQ)of 7 PAHs in soils of urban parks was lower than the World Health Organization(WHO)standard value of 1 mg kg.The toxicity risk to human health is low.Fourteen influencing indicators(8 socio-economic factors and 6 park characteristic factors)were collected as input layers,and the output layers were PAHs content.The fitting degree of BP neural network was as high as 0.845.The range of PAHs content in soil in 2020 and 2023 was predicted to be 0.008-0.969 mg kg and 0.022-1.988 mg kg,respectively.Although they were lower than the soil pollution risk screening values on the whole,they showed an upward trend over time,especially in Chaoyang district and Haidian District.This study have shown that the factors of urbanization development have an obvious influence on the increase of soil PAHs content.By 2023,the PAHs content in the soil of Beijing urban parks will continue to increase if the soil is not managed.