Study On The Effect Of Mercury, Cadmium, Lead Compound-Pollution To Vegetables And It's Amendments

The agro-environment contaminated by heavy metal influenced the growth,quality and safety of the vegetables;thus the heavy metal always turn up in the forms of compound pollution,the origin research can neither reflect the problem nor solve it basically,consequencely,doing compound pollution study is desirable.Probe into it's effect to the agriculture,then quest the resolvent can boost not only the quality,but also the quantity of the vegetables.This sudy based on the soil and vegetables in south of China discussed the effect of compound pollution of heavy metal to the vegetables and also probe into the amendments study,additionally discussed the effect of use of Ca(OH)₂ before planting,mainly on the change of the content of bio-availity.The results as the following:1.Low-level compound of Hg,Cd,Pb pollution didn't reduce the quantity of the vegetable,on the contrary,boost it slightly.But when the concentration reach the 3-grade level,it restrain the growth significantly.From the whole geow progress,as the content of the heavy metal increase,the Chlorophyll a,Chlorophyll b,and the total content of vegetables decreased.Thus the content of the FAA increased.The nitrate and nitrite content of Chinese cabbage decreased and then increase;The nitrate and nitrite content of lettuce increased.There is no change of soluble solid content.2.The use of Ca(OH)₂ can't decrease all the content of available forms of heavy metal,and it depends on the quantity of Ca(OH)₂ and the time of it treated.The available Pb,Cd decreased as the quantity use of Ca(OH)₂,and it becomes lower with the time went on.The available Cr,Hg increased as the quantity use of Ca(OH)₂.The available Cu in cinnamon and latosol soil decreased as the quantity use of Ca(OH)₂,but it increased in lateriotic red soil;The available Zn in latosol soil decreased as the quantity use of Ca(OH)₂,but increased in lateriotic red soil;The quantity used of Ca(OH)₂ 3g/(kg soil) in lateriotic red soil and treated 10d can reduce available Zn significant(p＜0.05).The quantity used of Ca(OH)₂ lg/(kg soil) in cinnamon and treated 20d can reduce available Zn significant(p＜0.05);The available As in latosol soil and cinnamon decreased as the quantity use of Ca(OH)₂,and decreased in lateriotic red soil when the quantity used of Ca(OH)₂ 1g/(kg soil).3.It can boost the growth of vegetables when used Ca(OH)₂ in suitable quantity, when the pH of soil adjusted to 6.45,the quantity reach the summit,and then decreased. The quality of cabbage best when pH adjusted to 5.10—7.72.The reciduce of heavy metal in cabbage reduced when pH increased.In that rang,the more used of Ca(OH)₂ the lettuce grow better.The quality of lettuce best of when pH adjusted to 7.72, meanwhile the heavy metal become low level.4.When use Na₂S 5g/(Kg soil) or more can reduce the quality and quantity of the vegetables,and the use of Na₂S can reduce the recidue of heavy metal in cabbage.The use of Na₂S increased the content of the heavy metal in the stem of lettuce,but reduced the distribution coefficient.With the used of Na₂S increased,the available Hg,Pb increased, but Cd reduced.5.Humic acid can't increase the production of the vegetables,but as it use,nitrate and nitrite reduced and the content of soluble solid increased,The use of Humic acid not only increased the content of the heavy metal in the stem of lettuce,but also reduced the distribution coefficient.6.From the result of continous cropping,only Ca(OH)₂ have effect on the next crop, and the more used previous,the more usefull to the next crop.