Zheng Ruilun, Sun Guoxin, Li Cui, Reid Brian J, Xie Zubin, Zhang Bo, Wang Qinghai
Research and Development Center for Grasses and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, People's Republic of China.
State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China.
Environ Sci Pollut Res Int. 2017 Mar;24(7):6532-6542. doi: 10.1007/s11356-016-8282-9. Epub 2017 Jan 10.
Greenhouse experiments were conducted to investigate the influence of rice straw biochar (RSB) on soil cadmium (Cd) availability and accumulation in lettuce. The RSB was applied either in bands or broadcast in the test site of four greenhouses with soil Cd concentrations ranging from 1.70-3.14 μg g. Biochar doses applied in bands were half of those broadcast. The Cd levels in the shoots of lettuce were observed to be reduced by up to 57% with increasing RSB application rate (0, 6, 12, 18 t ha). Following RSB application, shoot Cd concentrations of lettuce were reduced to below the Chinese threshold value set for food, and hazard quotients for Cd associated with vegetable consumption were reduced from 0.70-1.11 to 0.42-0.65. A decrease in soil bulk density (11%) and increases in water holding capacity (16%), available phosphorus (30%), available potassium (197%), and lettuce yield (15%) were observed after RSB application. Multiple linear regression analysis suggested that the soil extractable Cd level (but not biomass dilution) and soil bulk density, as influenced by RSB addition, were the dominant contributors to the shoot Cd levels in lettuce and lettuce yield, respectively. These results highlight the potential for RSB to mitigate the phytoaccumulation of Cd and thereby to reduce human exposure from vegetable consumption. Application of biochar in band, rather than broadcasting over the entire area, represents an opportunity to halve the biochar cost while retaining a good remediation effect.
开展了温室试验，以研究稻草生物炭（RSB）对生菜土壤镉（Cd）有效性及镉积累的影响。在四个土壤镉浓度为1.70 - 3.14μg/g的温室试验场地，以条施或撒施方式施用RSB。条施的生物炭剂量是撒施剂量的一半。随着RSB施用量增加（0、6、12、18 t/ha），观察到生菜地上部镉含量降低了57%。施用RSB后，生菜地上部镉浓度降至中国食品设定阈值以下，与蔬菜消费相关的镉的危害商数从0.70 - 1.11降至0.42 - 0.65。施用RSB后，观察到土壤容重降低（11%），持水量增加（16%），有效磷增加（30%），速效钾增加（197%），生菜产量增加（15%）。多元线性回归分析表明，RSB添加影响的土壤可提取镉水平（而非生物量稀释）和土壤容重，分别是生菜地上部镉含量和生菜产量的主要影响因素。这些结果凸显了RSB减轻镉的植物积累从而减少蔬菜消费导致人体暴露风险的潜力。条施生物炭而非全田撒施，是一个既能将生物炭成本减半又能保持良好修复效果的机会。
