Sources Analysis Of Cadmium Pollution In Dingshu Town Based On Emission Inventory

Cadmium(Cd),a widely concerned heavy metal,is toxic to human and ecosystems.After the reform and opening up,with the development of economy,a larger number of raw materials,including Cd,were used.However,the supervision lags behind,which makes the soil in China seriously polluted by heavy metals,including Cd.In this study,a Cd-polluted town,named Dingshu,in southeast China was selected to study the emission characteristics of Cd emitted by anthropogenic sources into water,soil and atmosphere,and analyze the main source and transmission channels of soil Cd pollution based on the current situation of soil Cd pollution.The research results show that:(1)The total amount of Cd emitted into the environment in 2015 was approximately 43.5kg,and the majority of those emissions were discharged into the water,accounting for approximately 90.4%of the total Cd emissions.The remaining Cd emissions into the soil and atmosphere accounted for 9.5%and 0.1%,respecti-vely.According to the proportion of pollution source emissions,the ranking as follows:Industrial production(62.1%)>Aquaculture(9.7%),>Waste/water treatment(9.3%)>Living consumption(8.2%)>Crop farming(5.9%)>Animal breeding(4.8%).From the perspective of total emissions,pigment production is the main source of anthropogenic Cd emission,accounting for 61.1%of the total emissions.Among the sources of water Cd emission,pigment production is also the advantage emission source,accounting for about 67.6%.Among the sources of soil Cd emission,the proportion of residents'feces and urine is the largest,accounting for 73.5%.Atmospheric Cd comes from the production of lead-acid battery.(2)In terms of spatial distribution,the total Cd emissions in Dingshu are distributed unevenly with high concentration in the central part of the town,including Xiwang,Dingshujianchengqu,Sandongqiao and Taoyuan,accounting for approximately 63.9%of total Cd emissions.Among the sources of water Cd emission,the spatial distribution is similar to the total emissions,which is also concentrated in Xiwang,Sandongqiao,Dingshujianchengqu and Taoyuan,accounting for 69.6%of total Cd emissions.Soil emission sources are concentrated in rural areas on the edge of towns,including Chuanbu,Renshu and Qianluo.There is only one source of Cd emitted into the atmosphere,which is derived from the production of lead-acid batteries in Yangan.(3)According to the results of Cd concentration analysis of soil in the study area,the high value of soil Cd appeared in the central area of the town and the adjacent Xiwang,Shuangqiao,Ssandongqiao and Dingshujianchengqu,and its spatial distribution presented a"granular structure".With the latest national standard of soil Cd concentration,the soil Cd pollution areas in the study area are concentrated,and the pollution index of soil screening value and controlled value indicates that the soil in Xiwang and its vicinity has been seriously polluted.(4)The correlation analysis results shows that Cd pollution in the local soil mainly comes from the nearby pigment enterprises.Through the spatial location of the pigment enterprises and the distribution of the watercourses,it can be found that the rivers used for irrigation are the transmission channels of Cd pollution.Based on the results of this research,the researcher provides the following policy implications from the aspects of Cd emission,transmission and final pollution:(1)Strengthen the construction of wastewater treatment infrastructure such as wastewater treatment pipe network and wastewater treatment plant,and reduce the direct emission of wastewater containing Cd;(2)Conducting surveys of heavy metals concentration in the soils through the whole town,especially the river sediments near key polluting enterprises,and breaking the transmission channels of heavy metals;(3)Under the premise of not affecting normal agricultural planting,various approaches,including fallow,deep ploughing,use of soil remediation agents and planting heavy metal hyperaccumulative plants,should be adopted to reduce soil heavy metal pollution.