适于冻融过程的砷镉复合污染土壤稳定化材料筛选

Screening of stabilization materials for arsenic and cadmium co-contaminated soil suitable for freeze-thaw process

冻融交替是影响北方地区污染土壤重金属稳定化修复效果的重要因素,但目前相关研究并不多见。本研究针对常见的19种重金属稳定化材料,通过模拟15周期冻融过程,探究冻融交替作用对不同材料修复土壤的理化性质及As、Cd稳定效果的影响。结果表明:(1)稳定化修复材料提高了复合污染土壤pH和电导率(EC),施加黏土矿物(SL)、调理剂(MCA、SA2)及生物炭(MBC、FBC1、FBC2)6种材料能够同步降低土壤有效态As和Cd的含量,分别降低15.0%~32.0%和14.0%~33.0%,其中MCA对土壤Cd和As的稳定效果最佳,生物炭MBC次之;(2)冻融交替显著影响稳定化修复效果,15周期冻融后,稳定化修复土壤pH值呈上升趋势,生物炭类材料(MBC、FBC1、FBC2)进一步降低了修复土壤中重金属的有效性,其中MBC对As、Cd稳定化效果分别提高14.2%和12.5%。总体上,芭蕉生物炭(MBC)适用于北方寒冷地区As、Cd复合污染土壤的稳定化修复。

Freezing-thawing alternation is an important factor affecting the stabilization and remediation of heavy metals in contaminated soils in northern China,but few studies are available at present.In this study,19 kinds of common heavy metal stabilized materials were used to explore the effects of freeze-thaw alternation on soil physicochemical properties and stabilization of As and Cd with 15 freezing-thawing cycles.The results showed that the stabilized materials increased pH and electric conductivity of compound contaminated soil.The application of six materials,including clay minerals(SL),amendment(MCA,SA2),biochar(MBC,FBC1,FBC2),stabilized 15.0%-32.0%As and 14.0%-33.0%Cd simultaneously,with MCA having the best stabilization effect,followed by MBC.The stabilization effect on As and Cd was significantly affected by freeze-thaw alternation.After 15 cycles of freeze-thaw,the pH of stabilized soil showed a rising trend.Under such environment,biochar(MBC,FBC1,FBC2)addition further reduced the availability of heavy metals in soil.MBC addition increased the stabilization effect on As and Cd by 14.2%and 12.5%,respectively.In general,biochar(MBC)befits the remediation of As and Cd contaminated soil in the cold northern China.