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