黄棕壤土柱中铁锰的淋溶淀积及其对Pb2+的吸附解吸

以湖北省孝感市的黄棕壤B层土壤为装柱材料,在干湿交替(pH=5)条件下,分别加入不同浓度(0~0.08 mol/L)FeSO_4和MnCl_2的铁、锰混合溶液,淋溶土柱60次,分析土壤中游离态和非晶质态铁、锰氧化物的淋溶淀积规律及其对重金属Pb~(2+)的吸附与解吸特点。结果表明:当淋溶液的铁浓度分别为0.04和0.08 mol/L时,淋溶液中锰浓度增加,土壤中的锰含量呈增加趋势,铁含量无明显变化;淋溶后土壤中游离和非晶质铁氧化物的淀积量均高于锰氧化物的淀积量,同一处理土柱上层(0~10 cm)的铁、锰淀积量基本上大于下层(20~30cm);淋溶60次后,土壤样品对Pb~(2+)的吸附量随平衡溶液浓度的增大而增加,上层的最大吸附量为167 mmol/kg,下层的最大吸附量为195 mmol/kg;淋溶后黄棕壤对Pb~(2+)的吸附量随土壤中锰淀积量的增加而增加,而对Pb~(2+)的解吸量却呈相反的趋势;Pb~(2+)的解吸量随其吸附量的增加而增加。

Leaching and deposition of Fe and Mn in the yellow brown soil columns and its adsorption and desorption of Pb2+

Lower the alternating wet and dry conditions with pH 5.0,the mixed solutions of FeSO 4 and MnCl2 with different concentrations (0.00-0.08 mol/L)were added to yellow-brown soil columns with soil profile layer B leaching 60 times from the Xiaogan City,Hubei Province.The leaching and depo-sition of iron-manganese oxides of different forms and its adsorption and desorption characteristics on Pb2 + were investigated.The results showed that the manganese oxide content of the soil surface showed an increasing trend with the increase of leaching solution of manganese concentration,and the iron oxide content did not change obviously when the concentration of Fe2 + in the leaching solution was 0.04 mol/L and 0.08 mol/L.The deposition amount of free and amorphous iron oxides indicators was higher than that of manganese oxides in the soil surface,mostly upper layer (0-10 cm)>lower layer (20-30 cm)low-er the same treatment.The adsorption quantities of Pb2 + in the soil samples after leaching 60 times in-creased with the increase of equilibrium concentration.The maximum of adsorption in upper layer and lower layer was 1 67 mmol/kg and 1 95 mmol/kg,respectively.The adsorption quantities of Pb2 + in the yellow-brown soil samples increased with the increase of the amount of manganese deposition.However, the desorption of Pb2 + showed the opposite trend.The trend of Pb2 + desorption quantities increased with the increase of Pb2 + adsorption quantities.