Yu Huan-Yun, Liu Chuanping, Zhu Jishu, Li Fangbai, Deng Dong-Mei, Wang Qi, Liu Chengshuai
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, China.
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, China.
Environ Pollut. 2016 Feb;209:38-45. doi: 10.1016/j.envpol.2015.11.021. Epub 2015 Dec 7.
Cadmium (Cd) availability can be significantly affected by soil properties. The effect of pH value on Cd availability has been confirmed. Paddy soils in South China generally contain high contents of iron (Fe). Thus, it is hypothesized that Fe fractions, in addition to pH value, may play an important role in the Cd bioavailability in paddy soil and this requires further investigation. In this study, 73 paired soil and rice plant samples were collected from paddy fields those were contaminated by acid mine drainage containing Cd. The contents of Fe in the amorphous and DCB-extractable Fe oxides were significantly and negatively correlated with the Cd content in rice grain or straw (excluding DCB-extractable Fe vs Cd in straw). In addition, the concentration of HCl-extractable Fe(II) derived from Fe(III) reduction was positively correlated with the Cd content in rice grain or straw. These results suggest that soil Fe redox could affect the availability of Cd in rice plant. Contribution assessment of soil properties to Cd accumulation in rice grain based on random forest (RF) and stochastic gradient boosting (SGB) showed that pH value should be the most important factor and the content of Fe in the amorphous Fe oxides should be the second most important factor in affecting Cd content in rice grain. Overall, compared with the studies from temperate regions, such as Europe and northern China, Fe oxide exhibited its unique role in the bioavailability of Cd in the reddish paddy soil from our study area. The exploration of practical remediation strategies for Cd from the perspective of Fe oxide may be promising.
镉（Cd）的有效性会受到土壤性质的显著影响。pH值对Cd有效性的影响已得到证实。中国南方的水稻土通常含铁（Fe）量较高。因此，据推测，除pH值外，铁的形态可能在水稻土中镉的生物有效性方面发挥重要作用，这需要进一步研究。在本研究中，从受含镉酸性矿山排水污染的稻田中采集了73对土壤和水稻植株样本。无定形铁和DCB可提取铁氧化物中的铁含量与稻米或稻草中的镉含量显著负相关（稻草中DCB可提取铁与镉的关系除外）。此外，由Fe(III)还原产生的HCl可提取Fe(II)浓度与稻米或稻草中的镉含量呈正相关。这些结果表明土壤铁的氧化还原作用会影响水稻植株中镉的有效性。基于随机森林（RF）和随机梯度提升（SGB）对土壤性质对稻米中镉积累的贡献评估表明，pH值应该是影响稻米中镉含量的最重要因素，无定形铁氧化物中的铁含量应该是第二重要因素。总体而言，与欧洲和中国北方等温带地区的研究相比，铁氧化物在我们研究区域的赤红壤水稻土中镉的生物有效性方面发挥了独特作用。从铁氧化物的角度探索镉的实际修复策略可能很有前景。
