垃圾渗滤液污染含水层不同氧化还原带沉积物的pH缓冲能力

通过砂柱模拟实验研究含水层沉积物的pH缓冲能力及其在不同氧化还原带中的变化.结果表明,pH缓冲容量的本底值为324.93.pH-1mmol/kg,其中阳离子交换缓冲容量、碳酸钙缓冲容量、硅酸盐缓冲容量和次级缓冲容量的本底值分别为41.77.pH-1、86.53.pH-1、47.33.pH-1和149.31.pH-1mmol/kg.产甲烷带/硫酸盐还原带(MGZ/SRZ)、铁还原带(IRZ)、硝酸盐还原带(NRZ)和氧还原带(ORZ)中总的pH缓冲容量相对于本底值依次分别增加了12.4%、10.8%、19.8%和11.1%;各氧化还原带沉积物中的交换性阳离子(CEC)和交换性盐基离子(BEC)均小于本底值的11.59.pH-1和8.52.pH-1mmol/kg,各氧化还原带沉积物的盐基饱和度先升高后降低,都高于本底值的63.47%.因此,含水层沉积物有较强的pH缓冲能力.对垃圾渗滤液污染含水层不同氧化还原带沉积物pH缓冲能力的研究可为污染场地的修复提供理论依据.

pH Buffering Capacity of Landfill Leachate Contaminated Aquifer Sediments in Different Redox Zones

A simulated column filled with fine sand was constructed to investigate pH buffering capacity of aquifer sediments and its variation in different redox zones. Experimental results indicated that background pH buffering capacity of sediments was 324.93 pH^-1 mmol/kg, and the buffering capacities of cation exchange, calcium carbonate, silicate and secondary were 41.77·pH^-1, 86.53·pH^-1, 47.33·pH^-1 and 149.31·pH^-1 mmol/kg, respectively. pH buffering capacity increased 12.4%,10.8%,19.8% and 11.1% in MGZ/SRZ, IRZ, NRZ and ORZ, respectively. Cation exchange capacity (CEC) and base exchangeable cation (BEC) content of sediments in redox zones were lower than background content which was 11.59·pH^-1 and 8.52·pH^-1 mmol/kg, respectively. Base cation saturation was increasing first and then then decreasing, and it was higher than background of 63.47%. Therefore, the aquifer sediments have high pH buffering capacity. Research on the pH buffering capacity of landfill leachate polluted aquifer sediments in redox zones could provide theoretical evidences for remediation of polluted sites.