组配改良剂对稻田土壤中镉铅形态及糙米中镉铅累积的影响

通过田间实验,研究了镉(Cd)和铅(Pb)复合污染稻田土壤中施加组配改良剂(LS,石灰石+海泡石)对黄华占和丰优9号2种水稻种植土壤中p H、Cd和Pb形态转化以及水稻糙米中Cd和Pb累积量的影响.结果表明,施加LS,通过提高2种水稻土壤的p H值,可以有效地改变土壤中Cd和Pb的存在形态,使土壤Cd和Pb由酸可提取态不同程度地转化为铁锰氧化态和有机结合态.LS施加量为2.0~8.0 g·kg-1时,使黄华占水稻土壤中Cd和Pb的酸可提取态含量分别降低19.6%~23.8%、7.7%~14.3%,丰优9号水稻土壤中Cd和Pb的酸可提取态含量分别降低7.6%~31.1%、11.7%~24.8%,且降低效果为CdPb.LS还能显著降低2种水稻糙米中Cd和Pb含量,LS施加量为2.0~8.0 g·kg-1时,黄华占和丰优9号2种水稻糙米中Cd含量分别降低了56.5%~67.2%、29.0%~38.7%,Pb含量分别降低了9.8%~34.2%、6.8%~45.4%,同种水稻Cd和Pb含量降低效果为CdPb.研究表明,土壤中Cd和Pb酸可提取态含量能很好地反映土壤中Cd和Pb的生物有效性和迁移性.

Effects of combined amendment on forms of cadmium/lead in paddy soil and accumulation of cadmium/lead in brown rice

This paper studied the effects of combined amendment on pH changes and transformation of cadmium (Cd)/lead (Pb) species in paddy soil and changes of Cd/Pb contents in brown rice. Combined amendment of LS (limestone+sepiolite) was applied on two types of rices (Huanghuazhan and Fengyou 9) in an in-situ experiment. Results showed that applying LS could significantly increase soil pH values, which changed effectively the species of Cd/Pb in paddy soil and transferred Cd/Pb from acid extractable fractions to Fe-Mn oxide and organic fractions in different extents. When application ratios of LS ranged 2.0~8.0 g·kg^-1, the acid extractable fractions of Cd and Pb decreased 19.6%~23.8% and 7.7%~14.3% in the paddy soil planting Huanghuazhan and 7.6%~31.1% and 11.7%~24.8% in the paddy soil planting Fengyou 9, respectively. Reduction of soil acid extractable fraction for Cd was apparently greater than that for Pb. In addition, applying LS could reduce significantly Cd/Pb contents in brown rice. When applying LS from 2.0 g·kg^-1 to 8.0 g·kg^-1, 56.5%~67.2% of Cd in Huanghuazhan brown rice and 29.0%~38.7% of Cd in Fengyou 9 brown rice decreased, respectively. Meanwhile, 9.8%~34.2% of Pb in Huanghuazhan brown rice and 6.8%~45.4% of Pb in Fengyou 9 brown rice decreased, respectively. For the same type of rice, the order of reduction in brown rice was Cd > Pb. The experimental results also indicated that concentrations of acid extractable fractions of soil Cd/Pb could reflect the bioavailability and mobility of Cd/Pb in soil.