海泡石对镉污染红壤的钝化修复效应研究

The effects of sepiolite on immobilization remediation of Cd contaminated red soil

采用盆栽试验,研究了海泡石对土壤pH值,镉(Cd)有效态含量以及对菠菜的生物量与品质安全性的影响.结果表明,在1.25、2.5和5mg.kg-1Cd污染土壤中,投加海泡石显著地提高土壤pH值(p<0.05).土壤有效态Cd含量则随海泡石投加量的增加而降低,与未投加海泡石处理相比,分别减少了11.0%～44.4%、7.3%～23.0%和4.1%～17.0%.施加海泡石缓解了Cd对菠菜的胁迫效应,植物地上部生物量有所增加,然而海泡石处理显著抑制了菠菜对Cd的吸收,其地上部Cd含量(干重)分别比对照处理下降了78.6%～300.4%、44.6%～169.0%和18.1%～89.3%.在Cd含量为1.25mg.kg-1的土壤中,当海泡石投加量≥1%时,菠菜可食部Cd含量(鲜重)低于0.2mg.kg-1(FW)(国家食品中污染物限量标准Cd含量阈值,GB2762—2005);而在2.5和5mg.kg-1Cd污染土壤中,当海泡石投加量达到5%时,菠菜可食部Cd含量才满足污染物预防品种的Cd含量标准,可以安全食用.

Pot experiment was conducted to investigate the effects of sepiolite on soil pH, available Cd concentration, and spinach dry biomass, quality and safety. The results showed that under the Cd contamination of 1.25, 2.5 and 5 mg.kg^-1 , the application of sepiolite significantly increased soil pH （p 〈 0.05 ） , while the available Cd contents decreased by 11.0% -44.4% , 7.3% - 23.0% and 4.1% - 17.0% , respectively, with the increase of sepiolite concentration, when compared with unamended soil. The dry biomass of spinach was observed a certain degree increase due to the alleviation of Cd phytotoxicity to spinach by using sepiolite. In contrast, the concentrations of Cd in the shoots of spinach significantly decreased after applying sepiolite to soil, and reduced by 78.6% -300.4% , 44.6% - 169.0% and 18.1%- 89.3% , respectively, with respect to the control group. Under soil Cd concentration of 1.25 mg.kg^-1 , the concentration of Cd in the edible parts of spinach at ≥1% sepiolite was lower than 0.2 mg. kg^-1 fresh weight （FW） , the maximum permissible concentration （MPC） for Cd in vegetable （ GB 2762-2005 ）. Under 2.5 and 5 mg.kg^-1 Cd contaminated soil, it met the MPC of pollution-safe cuhivars （PSCs） when the treatment of sepiolite was up to 5%.