Effects of sulfur passivator on restraining Pb and Cd accumulations in Brassica juncea Cosson

The Pb and Cd contaminations,which commonly occur in vegetables,were used as the target to study the effect of sulfur passivators on Brassica juncea Cosson.The commonly applied calcium,magnesium,and phosphate heavy metal passivators were used as control to compared with the sulfur reagent.Experimental results indicated that the accumulated amounts of Pb and Cd in B.juncea Cosson decreased by 9.8%-44.0% and 8.6%-21.1%,respectively,when calcium,magnesium,phosphate and sulfur passivators were applied.On the passivators’ effect of reducing Pb content in vegetable,the sulfur passivator in low dosage was equivalent to calcium,magnesium,or phosphate passivators.On Cd reduction,application of sulfur passivator with moderate and high dosages was almost same as calcium,magnesium,or phosphate counterparts.There was a significantly negative correlation between the contents of Pb and Cd in B.juncea Cosson and the dosage of sulfur passivator.Regression equations were YPb=10.332-1.122x (R2=0.941**) and YCd=1.1573-0.055x (R2=0.883**).Gray correlation analysis showed that the correlation coefficient between Pb content in B.juncea Cosson and that in soil was the highest,i.e.,0.725.That between Pb in vegetable and soil pH was the next highest,and followed by that between Pb in vegetable and available Pb in soil.On the other hand,the correlation between Cd content in B.juncea Cosson and available Cd in soil was highest with a correlation coefficient of 0.736.It was followed by the correlation between the Cd in vegetable and the total amount of Cd,and pH of soil.