Liu Zhao-Dong, Wang Hai-Cui, Zhou Qin, Xu Ren-Kou
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China.
Ecotoxicol Environ Saf. 2017 Nov;145:207-213. doi: 10.1016/j.ecoenv.2017.07.033. Epub 2017 Jul 20.
Iron (Fe) and aluminum (Al) hydroxides in variable charge soils attached to rice roots may affect surface-charge properties and subsequently the adsorption and uptake of nutrients and toxic metals by the roots. Adhesion of amorphous Fe and Al hydroxides onto rice roots and their effects on zeta potential of roots and adsorption of potassium (K) and cadmium (Cd) by roots were investigated. Rice roots adsorbed more Al hydroxide than Fe hydroxide because of the greater positive charge on Al hydroxide. Adhesion of Fe and Al hydroxides decreased the negative charge on rice roots, and a greater effect of the Al hydroxide. Consequently, adhesion of Fe and Al hydroxides reduced the K and Cd adsorption by rice roots. The results of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and desorption of K and Cd from rice roots indicated that physical masking by Fe and Al hydroxides and diffuse-layer overlapping between the positively-charged hydroxides and negatively-charged roots were responsible for the reduction of negative charge on roots induced by adhesion of the hydroxides. Therefore, the interaction between Fe and Al hydroxides and rice roots reduced negative charge on roots and thus inhibited their adsorption of nutrient and toxic cations.
可变电荷土壤中附着在水稻根上的氢氧化铁（Fe）和氢氧化铝（Al）可能会影响表面电荷性质，进而影响根系对养分和有毒金属的吸附与吸收。研究了无定形氢氧化铁和氢氧化铝在水稻根上的吸附及其对根的zeta电位以及根系对钾（K）和镉（Cd）吸附的影响。由于氢氧化铝上的正电荷更多，水稻根吸附的氢氧化铝比氢氧化铁更多。氢氧化铁和氢氧化铝的吸附降低了水稻根上的负电荷，且氢氧化铝的影响更大。因此，氢氧化铁和氢氧化铝的吸附降低了水稻根对钾和镉的吸附。衰减全反射傅里叶变换红外光谱（ATR-FTIR）结果以及钾和镉从水稻根上的解吸表明，氢氧化铁和氢氧化铝的物理掩蔽以及带正电荷的氢氧化物与带负电荷的根之间的扩散层重叠是导致氢氧化铝吸附引起根上负电荷减少的原因。因此，氢氧化铁和氢氧化铝与水稻根之间的相互作用减少了根上的负电荷，从而抑制了它们对养分和有毒阳离子的吸附。
