基于时间序列模型的饮用水源地重金属健康风险分析与预测

Analysis and Prediction of Health Risk from Heavy Metals in Drinking Water Sources Based on Time Series Model

饮用水源地作为高敏感环境风险受体,重金属健康风险的时间变化特征和预测分析对于饮用水源地的风险管控、水环境治理和生态系统安全保障等具有积极的意义.为评价饮用水源地重金属健康风险及掌握健康风险的时间变化特征,以某饮用水源地为研究对象,监测并记录了该点位重金属As、Cd、Cu、Hg、Ni和Zn在2015年1月至2018年12月的浓度值,并以月均值作为研究基础数据,对饮用水源地重金属健康风险评价,并进一步利用Spearman秩相关系数法和ARIMA模型对重金属健康风险时间变化特征进行分析.结果表明,部分月份的重金属浓度值超过我国地表水环境质量标准(GB 3838-2002)规定的Ⅲ类水质的标准限值,尤其是Hg,其浓度最小值超过该标准的4倍;饮用水源地重金属致癌风险和非致癌风险的大小顺序分别为:As>Cd和As>Hg>Cd>Zn>Cu>Ni,儿童健康风险均高于成人健康风险,在2015年2月之外的所有月份的成人综合非致癌风险均低于1,儿童综合非致癌风险在2017年10月之后均低于或接近1,而儿童综合致癌风险均超过10^(-4);As的儿童致癌风险、儿童综合非致癌风险和儿童综合致癌风险在数据监测期间总体上具有明显的下降趋势,其Spearman秩相关系数分别为-0.714069、-0.773122和-0.62234,但是儿童综合致癌风险在2018年的Spearman秩相关系数为0.902098,均有显著地上升趋势,对应的儿童综合致癌风险均值为0.000234;基于ARIMA(3,1,3)模型预测的饮用水源地重金属儿童综合致癌风险具有较高的预测效果,预测结果表明后续两年内的儿童综合致癌风险的范围为0.000200~0.000302,需引起关注.

Health risk analysis can predict and control the risks posed by heavy metals,especially in drinking water,which is a highly sensitive environmental receptors.In order to evaluate heavy metal pollution in drinking water,the monthly average concentrations of As,Cd,Cu,Hg,Ni,and Zn were used to assess the health risk between January 2015 and December 2018 in a drinking water source.Furthermore,Spearman rank correlation coefficient and the ARIMA model were used to analyze temporal variations.The results showed that the monthly average concentrations of heavy metals exceeded the classⅢvalues as specified by Chinese environmental quality standard for surface water(GB 3838-2002),especially Hg with a minimum monthly average four times more than that set by the standard limits.Overall,the order of carcinogenic risk of As and Cd was decreased;the non-carcinogenic risk of Zn,Cu,Ni,Pb,and Hg was increased.Further,the comprehensive non-carcinogenic risk for adults was lower than 1 throughout the study period except February 2015,when the comprehensive non-carcinogenic risk for children was lower than or close to 1 after October 2017,and the comprehensive carcinogenic risk for children was more than 10^(-4).Meanwhile,the children's health risks are higher than that for adults,with the main health risk characteristic factors of As,Cd,and Hg.The Spearman rank correlation coefficient were-0.714069,-0.773122,and-0.62234,indicating the significant downward trend from 2015 to 2018.However,the children's comprehensive carcinogenic risk,whose average value was 0.000234 much more than 10-4,had significant upward trend in 2018 with Spearman rank correlation coefficient 0.902098.The ARIMA(3,1,3)model was able to predict the comprehensive carcinogenic risk for children from heavy metals in drinking water,and the result indicated the children comprehensive carcinogenic risk should be monitored to ensure levels between 0.000200 and 0.000302.The study has positive significance for risk warning and environmental management compared to the analysis and prediction of health risk from heavy metals in drinking water sources based on time series models.