College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, PR China.
Environ Pollut. 2020 Feb;257:113592. doi: 10.1016/j.envpol.2019.113592. Epub 2019 Nov 14.
This study was carried out to investigate the effect of biochar amendment on cadmium (Cd) availability in a paddy soil with biochar amendment and its effect on the accumulation in rice. Biochar was applied once at rates of 0 (A0), 10 (A10), 20 (A20), 30 (A30), and 40 (A40) t ha on the soil surface layer (0-17 cm). Results showed that the soil organic matter (SOM) content and pH in 0-17 cm soil layer increased as biochar application rate increased, whereas the content of dissolved organic carbon (DOC), and available iron (Fe), manganese (Mn), aluminum (Al) in diethylenetriamine pentaacetic acid (DTPA) extracts declined with biochar added. Available Cd in DTPA extracts in the 0-17 and 17-29 cm soil layer of A40 treatments was significantly lower (p < 0.05) by 49.4 and 51.7% than that in A0. Compared with A0, the distribution factor (DF) of DTPA extracted Cd in the 0.053-0.25 mm and <0.053 mm aggregates of A40 treatments increased by 136 and 269%, respectively, and the DF values in these micro-aggregates of A40 treatments were greater than 1.0. Based on European Community Bureau of Reference (BCR) sequential extraction results, 40 t ha rate of applied biochar reduced the proportion of acid extractable Cd fractions in both 0-17 and 17-29 cm soil layers, but increased the Cd in the oxidizable and residual fractions. The Cd concentration in the rice plants of different biochar treatments was in the order of A0>A10 > A20 > A30 > A40. DTPA extractable Cd concentration in soil was the key factor affecting the Cd uptake by rice roots. In conclusion, biochar application at 40 t ha can effectively reduce the availability of Cd in soil profile, enhance the available Cd enrichment in micro-aggregates, and thus limit the Cd uptake by rice.
本研究旨在探讨生物炭改良对土壤中镉（Cd）有效性的影响及其对水稻积累的影响。生物炭以 0（A0）、10（A10）、20（A20）、30（A30）和 40（A40）t/ha 的剂量一次性添加到土壤表层（0-17cm）。结果表明，随着生物炭施用量的增加，0-17cm 土层土壤有机质（SOM）含量和 pH 值增加，而二乙三胺五乙酸（DTPA）提取物中溶解有机碳（DOC）、有效铁（Fe）、锰（Mn）和铝（Al）含量降低。A40 处理的 0-17 和 17-29cm 土层中 DTPA 提取物中有效 Cd 含量分别显著降低（p<0.05）49.4%和 51.7%。与 A0 相比，A40 处理 0.053-0.25mm 和<0.053mm 团聚体中 DTPA 提取 Cd 的分布因子（DF）分别增加了 136%和 269%，且 A40 处理这些微团聚体中 DF 值均大于 1.0。根据欧洲共同体参考局（BCR）顺序提取结果，施用 40t/ha 的生物炭降低了 0-17 和 17-29cm 土层中酸可提取 Cd 分数的比例，但增加了可氧化和残留分数中的 Cd。不同生物炭处理的水稻植株 Cd 浓度顺序为 A0>A10>A20>A30>A40。土壤中 DTPA 可提取 Cd 浓度是影响水稻根系吸收 Cd 的关键因素。综上所述，施用 40t/ha 的生物炭可有效降低土壤剖面中 Cd 的有效性，增强微团聚体中有效 Cd 的富集，从而限制水稻对 Cd 的吸收。
