纳米氢氧化镁对不同类型土壤镉形态的影响

Effects of Nano-magnesium Hydroxide on the Forms of Cadmium in Different Types of Soil

采用28 d室内连续培养实验,以纳米氢氧化镁和普通氢氧化镁(100、200和300 mg·kg^-1)为镉污染土壤钝化剂,研究了纳米氢氧化镁和普通氢氧化镁对不同类型镉污染土壤(1、5、10和15 mg·kg^-1)中镉形态的影响.结果表明,在中性土壤上,1、5、10和15 mg·kg^-1镉处理中土壤交换态Cd(EX-Cd)形态分布比例FDC为66.7%~81.8%,为土壤镉主要形态.土壤镉含量大小顺序为EX-Cd>碳酸盐结合态Cd(CAB-Cd)>残渣态Cd(RES-Cd)>铁锰氧化态Cd(FeMn-Cd)>有机结合态Cd(OM-Cd).培养第14d时,土壤EX-Cd FDC达到最低值.培养0~28 d期间,在1、5、10和15 mg·kg^-1镉处理下,纳米氢氧化镁和普通氢氧化镁处理的土壤EX-Cd FDC较对照(CK)分别降低了11.4%~67.7%、7.8%~37.2%、7.7%~36.4%、5.0%~28.8%(纳米氢氧化镁)和0.5%~49.5%、0.6%~15.0%、1.0%~18.1%、0.7%~14.6%(普通氢氧化镁).碱性土EX-Cd含量均在培养的第7 d时达到最低;酸性土在1、5和10 mg·kg^-1镉处理中土壤EX-Cd含量在第21d时达到最低值.纳米氢氧化镁和普通氢氧化镁均降低了中、酸、碱性土壤EX-Cd含量,且随氢氧化镁施加量的增加,土壤EX-Cd含量呈降低趋势.相同用量下,钝化土壤活性镉的效果以纳米氢氧化镁优于普通氢氧化镁.

The effects of nano-magnesium hydroxide and common magnesium hydroxide(100,200,and 300 mg·kg^-1)on the forms of cadmium in different types of cadmium contaminated soils(1,5,10,and 15 mg·kg^-1)were studied under 28 days of continuous culture experiment.In the neutral soil,during the 28 days of culture,soil exchange Cd(EX-Cd)form distribution ratio(FDC)decreased at first and then increased with the culture time increasing under treatment of 1,5,10,and 15 mg·kg^-1 Cd.The minima of soil EX-Cd FDC were found on the 14 th day under 1 mg·kg^-1 Cd and 5 mg·kg^-1 Cd treatments,whereas the minima of soil EX-Cd FDC were observed on the 4 th day under 10 mg·kg^-1 Cd and 15 mg·kg^-1 Cd treatments.The FDC of soil carbonate bound Cd(CAB-Cd),iron manganese oxidized Cd(FeMn-Cd),and organic bound Cd(OM-Cd)increased at first,then decreased,and finally,became stable,and the maxima of soil CAB-Cd,FeMn-Cd,and OM-Cd FDC were found on the 4 th day,whereas the minima of soil CAB-Cd,FeMn-Cd,and OM-Cd FDC were observed on the 14 th day.Soil residual Cd(RES-Cd)FDC increased gradually and then tended to becomes stable during the 28 days of culture.The soil EX-Cd FDC was 66.7%-81.8%at 1,5,10,and 15 mg·kg^-1 Cd treatments,which was the main form of the soil.The FDC of soil Cd forms was in the order of EX-Cd>CAB-Cd>RES-Cd>FeMn-Cd>OM-Cd.Soil EX-Cd FDC reached the lowest value on the 14 th Day.Soil EX-Cd FDC was reduced by nano-magnesium hydroxide and common magnesium hydroxide,and it decreased with the increase of the amount of magnesium hydroxide.During 0-28 days of culture,the soil EX-Cd FDC decreased by 11.4%-67.7%,7.8%-37.2%,7.7%-36.4%,5.0%-28.8%(nano-magnesium hydroxide)and 0.5%-49.5%,0.6%-15.0%,1.0%-18.1%,0.7%-14.6%(ordinary magnesium hydroxide)at 1,5,10,and 15 mg·kg^-1 Cd treatments,respectively.The EX-Cd content of alkaline soil reached the lowest value on the 7 th day of culture,and the EX-Cd content of acidic soil reached the lowest value on the 21 st day under 1,5,and 10 mg·kg^-1 Cd treatments.The content of EX-Cd in neutral,acidic,and alkaline soils decreased with the increase of magnesium hydroxide content,and the content of EX-Cd in soil decreased with the increase of magnesium hydroxide amount.At the same amount,the effect of passivating soil EX-Cd under nanometer magnesium hydroxide treatment was superior to ordinary magnesium hydroxide treatment.