长期定位试验点土壤镉的吸附解吸及形态分配

Adsorption,Desorption and Speciation of Cadmium in Soils of Long-term Positioning Experimental Sites

以中国生态系统研究网络和国家土壤肥力和肥料效应长期定位监测网络5个农业生态实验站的表层土壤为材料,研究了不同区域农田土壤对Cd的吸附解吸特性;同时,在研究长期定量施肥对封丘潮土和祁阳红壤Cd积累及其有效性影响的基础上,对不同施肥处理进行了土壤Cd形态分级。结果表明,5种农田土壤中,中厚黑土的吸附量较大,旱地红壤的吸附量较小,土壤的最大吸附量与土壤有机碳含量、土壤CEC及土壤pH有关;长期施用化肥对封丘黄潮土和祁阳红壤Cd积累的作用不明显,长期施用有机肥可增加土壤Cd的积累,但内源性有机肥(秸秆)使黄潮土Cd含量增加的幅度远低于外源性有机肥(猪粪)使红壤Cd含量增加的幅度,长期施用有机肥对土壤Cd有"活化"作用。黄潮土和红壤中Cd的形态分配顺序均为:残渣态>弱酸提取态>可还原态>可氧化态,但黄潮土中残渣态Cd的比例显著高于红壤中残渣态Cd的比例。化肥和有机肥均可影响Cd在黄潮土和红壤中的形态分配。

With the samples collected from five stations of Chinese ecosystem research network and national long-term monitoring network of soil fertility and fertilizer effects,adsorption and desorption characteristics of Cd in agricultural soils distributed in different regions in China were studied.Also,based on the study of effects on the Cd accumulation and its＇ availability in Fengqiu fluvo-aquic soil and Qiyang upland red soil under the condition of long-term fixed ratio fertilization,soil Cd fractions in different treatments were analyzed as well.Results indicate that black soil had the highest Cd2＋ adsorption amount,while red soil had lowest Cd adsorption amount,and the maximum Cd2＋ adsorption amount had relationship with content of soil organic carbon,soil CEC and soil pH.Long-term application of chemical fertilizers had little effect on the accumulation of Cd in both fluvo-aquic soil and red soil,while long-term application of organic fertilizers increased the accumulation of Cd,but the Cd concentration increase degree in fluvo-aquic soil were much lower than that of in red soil since inner source organic matters（composted wheat straw） had been used in fluvo-aquic soil,and out source organic manure（fecal from hoggery） had been applied in red soil.Long-term application of organic fertilizers could active soil Cd.Both fluvo-aquic soil and upland red soil had the order of speciation as： residual acidic reducible oxidisable fraction,but the residuble proportion in calcareous fluvo-aquic soil was higher than that in upland red soil.Chemical and organic fertilizers affected speciation of Cd in both fluvo-aquic soil and red soil.