Study On Pollution Of Lead,Cadmium And Mercury Of Vegetables In 14 Prefectures Of Gansu Province

Objectives:To evaluate median,P₉₀,P₉₅,detection rate and the exceeding standard rate of Lead,Cadmium and Mercury in commercial vegetables,identify pollution characteristics in different vegetables in different regions,and provide scientific evidence for improving Pb,Cd,Hg surveillance and ensure food security through surveying Pb,Cd,and Hg of commercial vegetables in 14 prefectures from2011 to 2014.Methods:Mercury content in vegetables was detected with automatic mercury analyzer.Lead and Cadmium content was detected with Graphite Furnace Atomic Absorption Spectrometry method according to GB 5009.12-2010 and GB/T5009.15-2003 separately.The content of Lead,Cadmium and Mercury was measured with median,P₉₀ and P₉₅.Lead,Cadmium,Mercury content in different prefectures,different species and different sampling sites was compared with Chi-square test.Cadmium,Mercury content in different years was compared with Chi-square test for trend.Results:Lead,Cadmium,Mercury content in different years:Both P₉₅ and P₉₀ of Pb were highest in 2011;detection rate of Lead was highest in 2013,but there was overall upward trend from 2011 to 2014(χ²_trend=9.32,P<0.05);the exceeding standard rate of Pb was highest in 2011 and there was yearly downward trend from2011 to 2014(χ²_trend=6.50,P<0.05).The P₉₅ in 2012 and P₉₀ in 2011 of Cd was highest separately;detection rate of Cd was highest in 2013,and there was overall upward trend from 2011 to 2014(χ²_trend=94.01,P<0.05);the exceeding standard rate of Cd was highest in 2011 and there was yearly downward trend from 2011 to 2014(χ²_trend=31.95,P<0.05).Both P₉₅ and P₉₀ of Hg were highest in 2012;detection rate of Hg was highest in 2012,and there was overall upward trend from 2011 to 2014(χ²_trend=109.82,P<0.05);the exceeding standard rate of Hg was highest in 2012.Lead,Cadmium,Mercury content in different prefectures:the top three of Pb median were Dingxi（0.0951mg/kg）,Tianshui（0.0900mg/kg）and Qingyang（0.0880mg/kg）seperately,the top three of Cd median were Baiyin（0.0082mg/kg）,Longnan（0.0081mg/kg）and Qingyang（0.0076 mg/kg）seperately;the top four of Hg median were Qingyang（0.0012mg/kg）,Lanzhou（0.0010mg/kg）,Tianshui（0.0009mg/kg）and Baiyin（0.0009mg/kg）separately.There was statistically difference on detection rate of Pb（χ²=28.27,P<0.05）and no on exceeding standard rate（χ²=17.93,P﹥0.05）in different prefectures;there was statistically difference on detection rate of Cd（χ²=23.34,P<0.05）and no on exceeding standard rate（P﹥0.05）;there was statistically difference both on detec tion rate（χ²=31.75,P<0.05）and exceeding standard rate（P<0.05）of Hg.Lead,Cadmium,Mercury content in different types of vegetable:the Pb media in different types of commercial vegetable showed the following order:fungus>tubers>roots>leafs>fruits>flowers;the Cd media in different types of commercial vegetable showed the following order:fungus>roots>tubers>leafs>fruits>flowers;the Hg media in different types of commercial vegetable showed the following order:fungus>leafs>roots>tubers>fruits>flowers.The media of Pb,Cd and Hg were lowest in flowers and fruits.There was statistically difference on detection rate（χ²=92.12,P<0.05）and exceeding standard rate（χ²=41.58,P<0.05）of Pb in different types of vegetable;there was statistically difference on detection rate（χ²=154.09,P<0.05）and exceeding standard rate（χ²=147.10,P<0.05）of Cd in different types of vegetable;there was statistically difference on detection rate of Hg（χ²=183.33,P<0.05）and no on exceeding standard rate（P﹥0.05）.Lead,Cadmium,Mercury content in vegetable sampled from different sites:the detection rate of Pb,Cd and Hg in vegetables from supermarket were higher than that from farmers market;the exceeding standard rate of Cd and Hg in vegetables from supermarket were higher than that from farmers market.Conclusions:Pb,Cd and Hg in most commercial vegetable in Gansu Province were consistent with the national food safety standards,but the Pb,Cd and Hg in some regions and some types of vegetables exceeded the national food safety standards,which showed that there was potential pollution of Pb,Cd and Hg.The further monitoring should be continued and provide warning to people’s health.Pb content were generally high in vegetables;the Cd content in Baiyin,Longnan and Qingyang were higher than other regions;the Hg content in Qingyang,Lanzhou,Baiyin and Tianshui were higher than other regions.This study showed some reasons of Pb,Cd and Hg in commercial vegetable maybe caused by industrial pollution,which showed that it is necessary to strengthen the industrial"three wastes"governance and environmental governance.Pb,Cd and Hg is higher in fungus.The management in product process and Pb,Cd and Hg surveillance in raw materials should be strengthened.Heavy metals surveillance in fungus should focused on in food safety monitoring.Detection rate of Pb,Cd and Hg in vegetable from supermarket were higher than that from farmers market,which indicated that heavy metals surveillance in packaging materials（plastic wrap,cardboard packaging）in circulation should be strengthened.Reduce the heavy metal pollution come from warehousing and transportation link.