模拟再生水灌溉下污灌土壤中盐分离子交换运移的试验研究

为研究再生水灌溉下原污灌区土壤中主要盐分离子交换运移规律，采用有污水灌溉背景的两种质地土壤，根据再生水的基本性质及其盐分离子组分，配制4种浓度水平的入渗液，进行土柱模拟试验。结果表明，不同质地土壤在低Na^＋配制液淋洗下的穿透曲线都出现下凹现象，但Na^＋在壤土中富集的表现并不显著，而在粉质砂壤土中部分Na^＋吸附累积时间较长；模拟再生水入渗溶液中不同组分的盐分离子在不同程度上影响污灌土壤中发生的离子化学反应的进行，导致各处理下Na穿透时间发生显著差异；长期再生水灌溉会对HCO3^-含量较高且粉粒比重大的土壤的入渗等性能产生更为不利的影响。

Experimental Research on Soil Salinity and Ion Exchange and Transport in Sewage Irrigated Soil Under Simulated Recycled Water Irrigation

To assess the effects of irrigation with recycled water in sewage irrigated soils, soil column studies were carried out using two different texture soils from the sewage irrigated districts. Based on the ionic forms of salinity and the concentration in the recycled water, four levels of solutions were adopted in this experiment. Each sewage irrigated soil was leached with these four types solutions, several conclusions were gained by the analysis of the Breakthrough Curves（BTCs）of the Na^＋, Ca^2＋, Mg^2＋, and Cl^-. The＂concave＇phenomenon which appeared in BTCs of leachate Na^＋ under simulated recycled water irrigation was due to the high contents of indigenous exchanged Na^＋ in sewage irrigated soils, but the retention time of Na^＋ in the soil with high in silt was much longer than one with high in sand; Different forms and concentration of ions in the simulated recycled water and the sewage irrigated soil affected the ion exchange and dissolution-precipitation processes in the soils, which induced the difference of Sodium breakthrough time under the treatments. Long-term recycled water irrigation on sewage irrigated soil with high indigenous HCO3^- and silt contents deduced its infiltrability.