Wang Zi-Yu, Zhou Hang, Zhou Kun-Hua, Tan Wen-Tao, Jiang Yi, Tang Qi, Wu Gang-Fan, Gu Jiao-Feng, Zeng Peng, Liao Bo-Han
College of Environment Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China.
Hunan Engineering Laboratory for Control of Rice Quality and Safety, Changsha 410004, China.
Huan Jing Ke Xue. 2023 Jul 8;44(7):4109-4118. doi: 10.13227/j.hjkx.202207005.
A field experiment was conducted in a lightly Cd-contaminated rice field in Ningxiang City, Hunan Province, to study the effects of straw removal measures on the soil Cd bioavailability and rice Cd accumulation. The results showed that:① two consecutive seasons of straw removal measures (T1-T4 treatments) effectively increased soil pH by 0.04-0.58 units, reduced soil organic matter by 0.68%-25.87%, and reduced the Cd content of rhizosphere soil by 3.76%-12.78%. ② The proportions of Cd in the acid-extractable fraction and oxidizable fraction decreased, and the proportion of Cd in the residual fraction increased. Furthermore, straw removal measures significantly reduced the bioavailability of Cd in rhizosphere soil, and the Cd contents in TCLP, DTPA, and CaCl extracts all significantly decreased compared with those in CK. ③ The straw removal measure could significantly reduce the content of DOC and Cd in soil pore water; and the contents of Cd in soil pore water decreased by 4.54%-40.00% and 2.75%-67.34% under the straw removal measure (T1-T4) for two consecutive seasons, respectively, indicating that DOC was one of the key factors affecting the content of Cd in soil pore water. ④ Two consecutive straw removal measures (T1-T4) reduced the accumulation of Cd in different rice tissues, among which, under the treatment of all straw and root removal (T4), the Cd contents of brown rice in late rice planting in 2020 and early rice planting in 2021 decreased by 18.52% and 39.69%, respectively. Therefore, full or partial removal of straw in Cd-contaminated rice fields is a powerful measure to reduce the risk of exceeding Cd levels in brown rice.
在湖南省宁乡市轻度镉污染稻田开展田间试验，研究秸秆去除措施对土壤镉生物有效性及水稻镉积累的影响。结果表明：①连续两季秸秆去除措施（T1 - T4处理）有效提高土壤pH值0.04 - 0.58个单位，降低土壤有机质0.68% - 25.87%，降低根际土壤镉含量3.76% - 12.78%。②酸可提取态和可氧化态镉的比例降低，残渣态镉的比例增加。此外，秸秆去除措施显著降低根际土壤镉的生物有效性，与对照相比，TCLP、DTPA和CaCl提取液中的镉含量均显著降低。③秸秆去除措施能显著降低土壤孔隙水中DOC和镉的含量；连续两季秸秆去除措施（T1 - T4）下，土壤孔隙水中镉含量分别降低4.54% - 40.00%和2.75% - 67.34%，表明DOC是影响土壤孔隙水中镉含量的关键因素之一。④连续两季秸秆去除措施（T1 - T4）降低了不同水稻组织中镉积累，其中，在全量秸秆和根系去除处理（T4）下，2020年晚稻和2021年早稻糙米镉含量分别降低18.52%和39.69%。因此，在镉污染稻田中完全或部分去除秸秆是降低糙米镉超标风险的有力措施。
