Study On Typical Heavy Metal Influence On The Growth Of Leaf Vegetables And Its Distribution And Conversion Characteristics

The prevention-control of the influence from the soil contamination to the grain crops is extremely urgent,is the priority of researches,and is also one of the research hotpots and difficulties.This thesis researches the growing influences and transference characters of the common metals to the daily-used vegetable-basket,whose result will provide the relative fist for further researching the transferring law of heavy metals in the soil and the food chain,and will have the guiding function and meaning for the distinguishing and dealing of the heavy metal poisoning vegetables,the precaution of food security and the subsequent restoration of soil.In the experiment of the soil cultivation,with the precondition that the content of the two typical metals,Pb and Cd exceeds 0,1,2,3,4 times(calculated according to the secondary standard of GB15618-2008,plumbum ≤ 300mg/kg,cadmium ≤ 0.30mg/kg),pakchoi,swamp cabbage,amaranth and pakchoi,swamp cabbage and spinach are cultivated separately,establishing the blank controller of heavy metals meanwhile.The experiment records the budding time and budding rate during the budding period,observes the plant height change and the appearance condition during the growing period,and measures the chlorophyll content and the raw weight during the mature period.Then it investigates the influence of different containing heavy metals to this vegetables.After harvest,it measures the enrichment concentration of the heavy metals in the vegetables and the content in root,stem and leaf;and measures the concentration distribution of different heavy metals in the method of amendatory BCR(three extraction step-by-step),in order to further research the transference features and mechanism of heavy metals.The conclusions from the experiment are:1.In different levels of pollution,the influence features conclusion of the two heavy metals to the vegetables during the growing period.1.1 The influence to the budding time and budding rate:when Pb exceeds 1,2,3,4times,water spinach and amaranth both sprout in the third day,with the budding rates of85,85,75,70(%);50,40,55,60(%).In the same condition,water spinach and amaranth in blank group sprout in the fifth day and the seventh day,with the budding rates of 100%and 70%.When Cd exceeds 1,2,3,4 times,pakchoi,water spinach and spinach sprout inthe fifth day,the fifth day and the sixth day separately,with the budding rates of 95,90,95,90(%);100,90,95,80(%);95,90,90,85(%).In the same condition,the three vegetables in blank group sprout in the seventh day,the seventh day and the eighth day separately,with the budding rates of 90%,90%,100%.1.2 The influence to the growing speed: when Pb exceeds 1,2,3,4 times,the fastest growing speeds of pakchoi,water spinach and amaranth are 40,32,30,30(mm/week);56,52,52,50(mm/week);23,24,25,24(mm/week).In the same condition,the fastest growing speeds of the three vegetables in blank group are 30,75,25(mm/week).When Cd exceeds 1,2,3,4 times,the fastest growing speeds of pakchoi,water spinach and spinach are 23,20,23,23(mm/week);50,54,52,45(mm/week);25,24,26,26(mm/week).In the same condition,the fastest growing speeds of the three vegetables in bland group are 22,54,29(mm/week).1.3 The observation of the growing condition: when the heavy metal Pb exceeds once,the pakchoi leaves wilt and the swamp cabbage leaves whiten and wilt;when it exceeds twice,the amaranth leaves wilt.When the heavy metal Cd exceeds once,the leaves of pakchoi and swamp cabbage are becoming yellow.1.4 The influence to the chlorophyll content and raw weight: when Pb exceeds 1,2,3,4 times,the chlorophyll contents of pakchoi,water spinach and amaranth are 89,87.5,75,66.5(mg/kg);127.5,116,101.5,88(mg/kg);106,102.5,88,84.5(mg/kg).The raw weights are 7.5,8.2,6.8,5.2(g);16.7,16.1,15.3,15.1(g);1.6,1.8,1.5,1.2(g).When Cd exceeds 1,2,3,4 times,the chlorophyll contents of pakchoi,water spinach and spinach are110,95,85,75(mg/kg);142.5,128,107.5,94(mg/kg);122,113.5,102.5,87.5(mg/kg).The raw weights are 5.21,5.17,5.22,5.09(g);11.4,11.1,10.5,9.2(g);5.98,5.85,5.77,5.64(g).2.The transferring features of the two metals in the three kinds of vegetables under different levels of pollution.2.1 Enrichment of heavy metalsThe enrichment ability of the three vegetables to Pb: amaranth > pakchoi > swamp cabbage.When plumbum exceeds 300mg/kg,the Pb contents in pakchoi,water spinach and amaranth are 0.27,0.42,0.69,0.82(mg/kg);0.24,0.41,0.68,0.82(mg/kg);0.28,0.43,0.80,0.93(mg/kg).The enrichment ability of the three vegetables to Cd: spinach > pakchoi > water spinach.When the cadmium exceeds 0.3mg/kg,the Cd contents in pakchoi,water spinach and spinach are 0.044,0.046,0.051,0.079(mg/kg);0.041,0.043,0.049,0.070(mg/kg);0.0510,0.060,0.061,0.071(mg/kg)。2.2 The content of heavy metals in the roots,stems and leavesThe Pb contents in the root,stem and leaves of pakchoi,swamp cabbage,amaranth are 0.217,0.113,0.334(mg/kg);0.177,0.213,0.162(mg/kg);0.185,0.147,0.162(mg/kg).The Cd contents in the roots,stem and leaves of pakchoi,swamp cabbage,amaranth are 0.057,0.035,0.033(mg/kg);0.056,0.033,0.052(mg/kg);0.072,0.052,0.041(mg/kg).2.3 The form distribution of the root,stem and leavesThe four form distributions(exchangeable form,reducible form,oxidable form,residual form)of Pb in the pakchoi root,stem and leaves are 18,8,66,9(%),12,0,70,18(%),11,0,46,43(%);and in the swamp cabbage root,stem,and leaves are 26,0,64,10(%),25,0,53,22(%),34,12,54,0(%).The four form distributions(exchangeable form,reducible form,oxidable form,residual form)of Cd in the pakchoi root,stem and leaves are 46,35,10,9(%),52,35,6,7(%),48,41,7,4(%);and in the swamp cabbage root,stem,and leaves are 44,37,11,8(%),49,35,8,8(%),46,40,6,8(%).