漳州市城市公园灰尘重金属来源及健康风险评价

Heavy metal sources and health risk assessment of dust in Zhangzhou urban parks

为了探析福建省漳州市公园灰尘重金属的来源以及重金属对人体健康的危害,通过分析其市区主要公园灰尘的六种重金属(Cr、Ni、Cu、Zn、As、Pb)含量,结合多元统计方法和暴露剂量模型进行解析。结果表明:漳州市公园灰尘的Cr、Ni、Cu、Zn、As和Pb平均含量分别为61.74 mg∙kg^(−1)、25.20 mg∙kg^(−1)、77.89 mg∙kg^(−1)、379.95 mg∙kg^(−1)、7.05 mg∙kg^(−1)、71.74 mg∙kg^(−1),均高于福建省土壤环境背景值。各个公园中重金属元素的异常值和最大值主要出现在入口区和游乐区附近,休憩区、道路区的各种重金属元素的含量相对较少。Ni、Cu、Zn、Pb元素的来源主要受交通和金属器材风化、油漆脱落的混合影响;Cr元素的来源主要受汽车配件和交通因素的影响;As元素的来源较为复杂,可能为自然和人为活动的混合源。从健康风险评价的结果来看,手—口摄入是暴露的最主要途径,目前,无论是儿童或成人的致癌危害指数还是非致癌危害指数均还处在安全范围内,但是六种重金属的非致癌危害叠加指数已经超过1,应引起人们的重视。

Background,aim,and scope The surface dust is produced by various non-point source channels such as traffic,industry,construction,and atmospheric deposition.It is deposited on or cover the impervious underlying surface of the city under various external forces.It can be suspended in the atmosphere again under a series of external disturbances.A large number of toxic substances such as heavy metals,polycyclic aromatic hydrocarbons,and polychlorinated biphenyls,among which the heavy metals are persistent,difficult to degrade,and toxic.This harms not only the aquatic ecological environment but also human health by inducing several diseases.The park is an area for human enjoyment,which is especially visited by children who are involved in hand-to-mouth activities.Their autoimmune system functions are not completely developed and are more likely to be the target of dust pollution.Some local scholars have studied the heavy metals within the surface dust based on the parameters such as the distribution,source,ecological risk assessment,health risk assessment,etc.using samples collected from the parks located in big cities.However,there were no extensive studies conducted in Zhangzhou,the third tier city.Therefore,this paper mainly analyzes the pollution sources and health risk assessment of heavy metals in the dust samples from Zhangzhou parks,hoping to provide the scientific basis for the protection of citizen’s health and urban environmental management.Materials and methods The road dust was collected in polyethylene plastic bags from six parks located in Zhangzhou City using a brush and wooden shovel.A total of 73 dust samples were collected.The samples were dried under normal environmental conditions.After removing the foreign matter,the dust particles were passed through a 200 mesh nylon screen.Six heavy metal elements(Cu,Zn,Pb,Cr,As,and Ni)were detected in the dust from the Zhangzhou parks using the X-SeriesⅡICP-MS(inductively coupled plasma mass spectrometry)imported from the United States.The quality range of detection was 0-260 u.According to ArcGIS 10.5,the sampling point map of heavy metals in the dust from the Zhangzhou urban parks was obtained.The correlation analysis,principal component analysis,and cluster analysis were obtained using the SPSS 25 software.Results The average concentrations of Cr,Ni,Cu,Zn,As,and Pb were found to be 61.74 mg∙kg^(−1),25.20 mg∙kg^(−1),77.89 mg∙kg^(−1),379.95 mg∙kg^(−1),7.05 mg∙kg^(−1),and 71.74 mg∙kg^(−1),which were higher than the environmental background values of soil present in the Fujian Province.Discussion The regions of abnormal and maximum values can be found using the box-type diagram for heavy metals present in the dust sample collected from each park.This was used to identify the source area,and then classify the sampling points into different functional areas,such as the entrance area,rest area,recreation area,and road area.The high-value areas were further verified using the content of the dust heavy metals in the functional area.The correlation analysis,principal component analysis,and cluster analysis were performed to demonstrate the sources of the heavy metals.Finally,the carcinogenic and non-carcinogenic risks of heavy metals present in the dust from the Zhangzhou urban parks to children and adults were evaluated by the exposure dose model.Conclusions The abnormal and maximum concentration values of dust heavy metals in each park mainly appear near the entrance and recreation areas,which are greatly affected by traffic,weathering of metal equipment,and paint wear off.The concentration of heavy metals in the rest area and road area is relatively small.The weathering of metallic coating,paint peeling and pollution from the traffic lead to the accumulation of Ni,Cu,Zn,and Pb.Cr is used in automobile parts and thus comes from traffic pollution.The source of As is complex as it involves a combination of natural and human activities.Based on the health risk assessment results,hand-to-mouth intake is the primary way of exposure.Both the carcinogenic and non-carcinogenic indices of children and adults were in the safe range.However,the non-carcinogenic accumulation index of six heavy metals exceeded the value of 1,which should arouse people’s attention.Recommendations and perspectives Tourists should take proper protection against the exposure to surface dust,especially in the entrance and recreation areas of the park.It is suggested to develop the habit of washing hands frequently after playing in the park.Park supervisors and concerned environmental protection departments should also pay attention to the health risks.Future research will be focused on sampling more urban parks in Zhangzhou City,not only to study the surface dust but also to study the heavy metals in the park soil.It is expected to lead to the detection and evaluation of more heavy metals,especially the elements with high toxicity coefficient.