Effects Of Heavy Metal Combined Pollution On Physiological Indexes Of Vegetables And Health Risk Assessment In Huludao Metallurgical Area

To understand the contamination of heavy metals in metallurgical area and their harm to human,the area around Huludao Zinc Plant was selected to investigate the occurrences of heavy metals contents in eight vegetables;the bioaccessibility of heavy metals in vegetables was evaluated by in vitro gastrointestinal experiments,and the calculation methods of health risk assessment were calibrated.And then a pot experiment was conducted to estimate changes of population characteristics of soil animals as well as the variation of vegetables growth and nutrients contents with Cd and Cu mixtures addition to soil,in order to clarify the influences of Cd and Cu mixtures to soil and vegetables.The main conclusions were outlined as following:The contents of heavy metals?excepted Cu?in vegetable samples in the study area exceeded the standard in different degrees,indicating that the combined pollution of heavy metals in vegetables was serious in this area.Their bioaccessibility showed Cd?67.67%?>Pb?50.70%?>Cu?44.69%?>Hg?3.09%?in stomach phase;and Pb?48.90%?>Cd?40.66%?>Cu?32.88%?>Hg?13.12%?in intestinal phase.Upon bioaccessibility correction,the target hazard quotient?THQ?of heavy metal contamination for local residents via dietary consumption of vegetables followed:Cd>Pb>Cu>Hg.THQ and TTHQ for heavy metals based on bioaccessibility in intestinal phase were calculated to be less than 1,but THQ for Cd in stomach phase exceeded 1,indicating that intake of heavy metals through consuming vegetables would pose potential health risks to individuals in the vicinity of Zinc plant.Additionally,THQ and TTHQ of four heavy metals for adults were higher than those of children.Cd and Cu added to soil resulted in the serious pollution of Cd and Cu in soil,and Cd and Cu content were up to 0.08-22.21 mg·kg^-1and 9.64-343.91 mg·kg^-1,respectively.Cd and Cu mixtures addition caused 23.1%-79.5%reduction of soil animals.The concentrations of Cd and Cu in carrot were up to 0.02-3.31 mg·kg^-11 and1.28-7.03 mg·kg^-1,respectively;0.01-6.64 mg·kg^-1 and 0.10-1.87 mg·kg^-1 in pakchoi,respectively.Addition of Cd(20 mg·kg^-1)and Cu(400 mg·kg^-1)mixture in soil caused the maximum reduction of biomass?78.01%?and length?68%?of carrot root and the maximum reduction of biomass?54.34%?and length?56.92%?of pakchoi shoot,respectively.Cd(20 mg·kg^-1)caused maximum reduction of sugar content?45.29%?in carrot root;whereas,maximum reduction in carotene content?75.73%?in carrot root,sugar content?75.1%?and vitamin C content?70.58%?in pakchoi shoot were observed with the addition of Cd(20 mg·kg^-1)and Cu(400 mg·kg^-1)mixture.Therefore,the combined pollution of Cd and Cu in soil aggravated the heavy metal pollution of vegetables.The growth and accumulation of nutrients were inhibited,which leads to the increase of the health risk and decrease yield and nutritional value of vegetables.