Deng Ji-Bao, Zhang Chun-Lai, Xu Wei-Hong
College of Resources and Environment, Southwest University, Chongqing 400715, China.
Huan Jing Ke Xue. 2020 Apr 8;41(4):1888-1903. doi: 10.13227/j.hjkx.201910135.
The effects of nano-magnesium hydroxide and common magnesium hydroxide (100, 200, and 300 mg·kg) on the forms of cadmium in different types of cadmium contaminated soils (1, 5, 10, and 15 mg·kg) 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 Cd. The minima of soil EX-Cd FDC were found on the 14th day under 1 mg·kg Cd and 5 mg·kg Cd treatments, whereas the minima of soil EX-Cd FDC were observed on the 4th day under 10 mg·kg Cd and 15 mg·kg 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 4th day, whereas the minima of soil CAB-Cd, FeMn-Cd, and OM-Cd FDC were observed on the 14th 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 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 14th 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 Cd treatments, respectively. The EX-Cd content of alkaline soil reached the lowest value on the 7th day of culture, and the EX-Cd content of acidic soil reached the lowest value on the 21st day under 1, 5, and 10 mg·kg 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.
通过28天的连续培养实验，研究了纳米氢氧化镁和普通氢氧化镁（100、200和300 mg·kg）对不同类型镉污染土壤（1、5、10和15 mg·kg）中镉形态的影响。在中性土壤中，培养28天期间，在1、5、10和15 mg·kg镉处理下，土壤交换态镉（EX-Cd）形态分布比例（FDC）随培养时间先降低后升高。在1 mg·kg镉和5 mg·kg镉处理下，土壤EX-Cd FDC的最小值出现在第14天；而在10 mg·kg镉和15 mg·kg镉处理下，土壤EX-Cd FDC的最小值出现在第4天。土壤碳酸盐结合态镉（CAB-Cd）、铁锰氧化态镉（FeMn-Cd）和有机结合态镉（OM-Cd）的FDC先升高，然后降低，最后趋于稳定，土壤CAB-Cd、FeMn-Cd和OM-Cd FDC的最大值出现在第4天，而土壤CAB-Cd、FeMn-Cd和OM-Cd FDC的最小值出现在第14天。土壤残留态镉（RES-Cd）FDC在培养28天期间逐渐升高，然后趋于稳定。在1、5、10和15 mg·kg镉处理下，土壤EX-Cd FDC为66.7%-81.8%，是土壤中镉的主要形态。土壤镉形态的FDC顺序为EX-Cd > CAB-Cd > RES-Cd > FeMn-Cd > OM-Cd。土壤EX-Cd FDC在第14天达到最低值。纳米氢氧化镁和普通氢氧化镁均降低了土壤EX-Cd FDC，且随氢氧化镁用量增加而降低。在0-28天培养期间，在1、5、10和15 mg·kg镉处理下，土壤EX-Cd FDC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）。在1、5和10 mg·kg镉处理下，碱性土壤的EX-Cd含量在培养第7天达到最低值，酸性土壤的EX-Cd含量在第21天达到最低值。中性、酸性和碱性土壤中EX-Cd含量随氢氧化镁含量增加而降低，土壤中EX-Cd含量随氢氧化镁用量增加而降低。在相同用量下，纳米氢氧化镁处理对土壤EX-Cd的钝化效果优于普通氢氧化镁处理。
