木炭施用对镉污染土壤小白菜生长及镉吸收的影响

以镉污染土壤和小白菜为供试对象,采用盆栽试验,研究了木炭在用量分别为5、10、25、50 g·kg~(-1)水平时对土壤理化性质、小白菜生长及吸收镉的影响。结果表明,木炭的施入可改善土壤理化性质,当施用量≥25 g·kg~(-1)时能显著提高土壤pH值;与对照相比,添加木炭的各处理土壤有机质含量、碱解氮含量和有效磷含量等指标均显著增加,土壤速效钾含量在木炭用量为25 g·kg~(-1)时达最大,达显著水平(P0.05)。木炭的施用还促进了小白菜生长,使其地上部生物量、叶绿素含量和根部生物量均呈增加趋势。同时,木炭的添加降低了土壤镉有效性,减少了小白菜对镉的吸收。与对照相比,在木炭用量为5~50 g·kg~(-1)范围内,土壤Ca Cl2提取态镉含量、小白菜地上部镉含量和小白菜根部镉含量的降幅分别为5.05%~20.57%、6.08%~35.98%和5.13%~31.50%,小白菜各部位对镉的富集随处理水平呈递减趋势。研究表明添加适当比例的木炭可以抑制蔬菜对镉的吸收,并改良土壤。

Effects of charcoal on growth and Cd uptake by Brassica chinensis in Cd-contaminated soils

A pot experiment was conducted in Cd-contaminated soils to investigate the effects of amendment with charcoal at 5, 10, 25, and 50 g·kg^-1 on soil physicochemical properties, the growth of Brassica chinensis, and the absorption of Cd. The results showed that the application of charcoal could improve the physicochemical properties of soil. Soil pH significantly increased when the application amount was greater than or equal to 25 g·kg^-1. The SOM, available N, and available P content under the charcoal application treatment were all significantly higher than those of the CK. The content of available K in soil was highest when charcoal was applied at 25 g·kg^-1 or higher, and this differed significantly from that of the CK(P<0.05). The application of charcoal also promoted the growth of Brassica chinensis in terms of increase in above ground biomass, chlorophyll content, and root biomass. The application of charcoal also reduced Cd availability to and absorption by B. chinensis. Compared with that in the CK, the soil CaCl₂-extracted Cd content and Cd content in the shoot and root were decreased from 5.05% to 20.57%, 6.08% to 35.98% and 5.13% to 31.50% respectively, when the charcoal amount ranged from 5 to 50 g·kg^-1. The Cd accumulation in each part of B. chinensis tended to decrease with increase in the amount of charcoal application. The results of the present study indicated that the appropriate application of charcoal can depress the absorption of Cd in vegetables and improve soil quality.