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标题:Chlorine weaken the immobilization of Cd in soil-rice systems by biochar



Cd2+流实验处理方法:5天的水稻幼苗,6mM NaCl瞬时处理

Cd2+流实验测试液成份:0.1mM KCl, 0.1 mM CaCl2, 0.01mM CdCl2, pH= 5.8



Rice (Oryza sativa L.) was cultivated in a Cd-contaminated soilswith rice straw biochar (BC) and water-washed rice straw biochar (W-BC) wereapplied to investigate the underlying mechanisms and possible reasons for biochar'sweakening effects on the immobilization of Cd in soil-rice system.

The results indicated that W-BC reduced the Cd concentration inpore water as well as in the roots and shoots of rice by 26.24%, 53.23% and62.47% respectively. On the contrary, there was an increase in Cd contents by50.27% in pore water, 2.32% in the roots, and 12.80% in the shoots of riceunder BC treatment. Furthermore, Cd content in rice shoot was significantly andpositively correlated with Cl− addition to the soil (P<0.01).

This phenomenon could be attributed to several combined effects:(1) the increase of Cl− in the soil decreased the soil pH, enhanced thedissolved organic carbon in soil pore water and increased the complexes of Cd2+and Cl−, resulting in the release of Cd from solid phase into solution phase,(2) the chloride in the soil increased the uptake of CdCl+ instead of Cd2+ bythe roots, thereby causing an increase of Cd in rice tissues. These resultsdemonstrate for the first time that biochar with high chloride content couldweaken its immobilization effects on soil Cd and even enhance Cd uptake byrice.


水稻(Oryza sativa L.)在镉污染土壤中种植稻草生物炭(BC)和水洗稻草生物炭(W-BC),以研究生物炭对生物炭减弱作用的潜在机制和可能的原因。土壤 - 水稻体系中Cd的固定化。

结果表明,W-BC使孔隙水以及水稻根冠中Cd含量分别降低26.24%,53.23%和62.47%。相反,在BC处理下,孔隙水中Cd含量增加50.27%,根中Cd含量增加2.32%,水稻枝条中Cd含量增加12.80%。水稻中Cd含量与土壤中Cl-的含量呈显着正相关(P <0.01)。

这种现象可归因于以下几种综合效应:(1)土壤中Cl-的增加降低了土壤pH值,增加了土壤孔隙水中溶解的有机碳,增加了Cd2+和Cl-的络合物,导致了土壤的释放。 Cd从固相进入溶液相,(2)土壤中的氯化物增加了CdCl+对Cd2+的吸收,从而导致水稻组织中Cd的增加。这些结果首次表明,氯含量高的生物炭可以减弱其对土壤Cd的固定化效应,甚至可以提高水稻对Cd的吸收。