水溶性有机物在土壤中的吸附及对Cu沉淀的抑制作用

Adsorption of Dissolved Organic Matter in Soil and Dissolved Organic Matter Effect on the Copper Precipitation in High pH Range

通过室内序批试验研究了来自绿肥(GM)和猪粪(PM)的水溶性有机物(DOM)在潮土和红壤中的吸附行为以及来自绿肥和猪粪堆肥(PMC)的DOM对Cu在高pH下沉淀的影响.结果表明,当没有外源DOM加入时,潮土、红壤中存在DOM的净释放,分别为33.58mg.L-1和17.17mg.L-1.随外源DOM加入量的增加土壤净释放量减小,存在土壤对DOM的吸附作用.与绿肥DOM相比,土壤对猪粪DOM的吸附能力更强,m、Kd分别为0.424 1、2.946(红壤),0.284 6、1.58(潮土).比绿肥对应高出32.9%、57.1%(红壤),67%、93.7%(潮土).红壤由于Fe、Al、Mn等氧化物含量较高及低pH值,使其对DOM的亲和力比潮土强.试验结果还表明绿肥和猪粪堆肥DOM能够明显地抑制Cu的沉淀,在pH6~10范围内效果明显,其中Cu的沉淀率分别降低了43.6%(Cu+GM),22.6%(Cu+PMC).

Batch experiments were performed to study the dissolved organic matter （DOM） derived from green manure and pig manure sorption in acidic and calcareous soils and the effect of DOM derived from green manure and pig manure compost on the precipitation of copper at different pH in solution. The results showed that there was a significant net release of dissolved organic carbon （DOC） in soil （33.58mg·L^-1 for calcareous soil and 17.17mg·L^-1 for acidic soil） when a DOC-free solution was added. As the amount of added DOC increased, the release of DOC from soils decreased. This indicates that parts of the added DOC were sorbed by the soil material and this effect was influenced by DOM＇s properties and soil properties. In this experiment the initial mass （IM） isotherm was used to describe the DOM sorption in soil which has been shown to be a useful tool for describing the sorption of DOC in soils because it takes into consideration the release of indigenous DOM from soil. As compared to green manure DOM, pig manure DOM had high m and Kd values, which indicated that it had a higher affinity with soil. As compared to that of green manure DOM, the m and Kd values are 0.424 1,2.946 in acidic soil and 0.284 6,1.58 in calcareous soil, respectively. What＇s more, the results also indicated that the acidic soil with higher Fe-oxide and Al-oxide content exhibited much higher DOC adsorption ability than calcareous soil rich in 2：1 minerals. In this experiment, green manure and pig manure compost DOM were selected to investigate the effects of DOM on the precipitation-dissolution behavior of copper at different pH. It can be found that DOM can inhibit the copper precipitation especially at high pH range because of the formation of DOM^Cu complex. From pH 6 to pH 10, as compared to the control treatment with no DOM added, the precipitation rate average decreased by 43.6 % for the treatment with green manure DOM added and 22.65 % for the treatment with pig manure compost DOM.