Study On The Characteristic Of Heavy Metal Pollution In Typical Tungsten Ore Area And Screening Of Low Accumulation Of Different Vegetables To Cadmium And Copper

This paper,taking soils and vegetables surrounding Gannan tungsten mine as the research object,analyze and evaluate heavy metal pollution of soils and vegetables,and screening low accumulation vegetables based on Cd,Cu stress factors.The experiment chose 9 different vegetables,including Chinese cabbage,pakchoi,garden chrysanthemum,radish,baby bokchoi,lettuce,pepper,eggplant,tomato,set up different Cd-Cu pollution treatment,respectively harvest in their mature stage.By analyzing the heavy metal content and physiological and biochemical characteristics of vegetables,screening of low accumulation vegetables to Cd and Cu.The main conclusions were as follows.(1)The contents of heavy metals(Cd,Cr,Cu,Zn,Pb,Hg)in soils were measured in Gannan tungsten mine.Geo-accumulation index were employed to evaluate the heavy metal pollution in soils.The results showed that the average contents of Cd,Cu posed more than the standard in soils.respectively more than 15~20 times and 3~ 4 times.The contents of Zn,Hg,Pb,Cr were not exceed the standard.Geo-accumulation index indicated Cd posed extreme contaminations,Cu posed slight to contaminations.(2)The contents of heavy metals(Cd,Cr,Cu,Zn,Pb,Hg)in vegetables were measured in Gannan tungsten mine.Vegetables risk index were employed to evaluate the heavy metal pollutions in vegetables.The results also showed that the average contents of Cd,Cu posed extreme contaminations.The rules of accumulation of heavy metals in vegetables:leafy vegetable>root vegetable>fruit vegetable.The contents of Cr,Pb,Hg were not obvious contaminations,and the contents of Zn was less than the standard.(3)From the accumulation of low vegetable screening experiment,with the concentration increasing of Cd-Cu,the contents of Cd,Cu in 9 kinds vegetables of aboveground and underground were increased,Cd accumulation quantity was slight in aboveground of garden chrysanthemum and pepper,the average accumulation were 0.5 mg/kg and 0.9 mg/kg,the underground of garden chrysanthemum and pepper Cd contents were less than other vegetables.The contents of Cd in lettuce aboveground was more than 8 times of standard,and underground part contents were 2.45 mg/kg.The accumulation of Cu content in eggplant and baby bokchoi were less than other vegetables,enrichment coefficient and transfer coefficient showed the same rules.Accumulation of Cd,Cu in pepper,tomato,eggplant fruits,Cd accumulation average value were 0.05 mg/kg,0.02 mg/kg,0.08 mg/kg,the content of pepper and tomato Cd accumulation lower than the limit standard of Cd,accumulation of Cu average value were 8.98 mg/kg,7.30 mg/kg,5.23 mg/kg,lower than the limit standard of Cu.(4)The changes of biomass and chlorophyll had the same trend.With concentration increasing of Cd-Cu,the contents of chlorophyll in tomato,eggplant were higher in different Cd-Cu level,and tomato chlorophyll synthesis level was highest in 9 kinds of vegetables,the second was eggplant;from the SOD,POD,CAT activities changes can be seen,as the concentration of Cd-Cu rising,the activities of SOD,POD and CAT in chinese cabbage,pakchoi,radish,pepper were express different degree,the activities of SOD,POD,CAT in garden chrysanthemum,baby bokchoi,lettuce,tomato,eggplant always improve greatly;MDA in garden chrysanthemum,tomato,eggplant were emerge different rule,and MDA contents in tomato,eggplant were lowest in 9 kinds of vegetables,average 2.13 nmol/g,1.78 nmol/g,and the stress to a minimum.with concentration increasing of Cd-Cu,the contents of soluble sugar and soluble protein in garden chrysanthemum,lettuce,pepper were decrease gradually,chinese cabbage,pakchoi,baby bokchoi,radish increased first and then decreased,tomato,eggplant always increased.Compared with the variation of all the characteristics,draw a conclusion that tomato and eggplant maybe more safty planting in soils of Cd-Cu compound pollution,the second is pepper.Garden chrysanthemum,baby bokchoi more suitable planting in single contaminations soils of Cd,Cu,lettuce,Chinese cabbage,pakchoi has a planting potential risk in soils of Cd and Cu pollution.