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

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

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Cd〉Pb.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Cd〉Pb.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.

This paper studied the effects of combined amendment on p H 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 p H 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. 0g·kg-1to 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.