Behaviors and potential health risks of Cd in urban environment of industrial area:A case study in Banshan industrial area of Hangzhou

The mobilization and potential biohazard of Cd contaminants in circumstance are among the most critical issues in environmental risk assessment.In order to investigate behaviors and health risks of Cd in urban environment,an extensive survey was conducted in north Hangzhou,in which the total concentrations of heavy metals (Cd,etc.) in the main environmental media (soil-dust-water-plant),and Cd chemical partitioning in soil,dust and mud samples were determined.The results suggested that Cd in urban environment migrated in two paths.The first one was spread through dust in surface environment,and the other was transferred by surface runoff or effluent into aquatic environment (water and bottom muds).The main environmental media in the studied area mentioned above were contaminated by Cd in different degree,and Cd load was generally high.Among these media,street dusts were the most seriously polluted with Cd content 14.1 times higher than the average background value of surface soils in the city,and locally even up to 64 times.Moreover,14% of the green-land soil samples were classified into III Grade based on the National Environmental Quality Standards in Soils of China (GB15618—1995).10% of water samples were classified into V Grade based on the National Environmental Quality Standards for surface water of China (GB3838—2002).And 50% of bottom mud samples exceeded the III Grade based on GB15618—1995 with the highest content up to 14.6 times of the III Grade's.Chemical partitioning analysis revealed that Cd in soil,dust,and mud were highly mobile with 32%～59% of Cd bounded in acetic acid extractable phase,and the mobility of Cd was in the order of bottom mud soil dust.Elevated contents of Cd in crops and moss samples revealed that Cd in urban environment presented high bioavailability.Furthermore,39% of vegetable and 60% of rice samples with Cd contents exceeding the limited values of National Food Sanitary Standards showed clearly that Cd contamination in the study area posed potential hazard to human health.