冻融对生物炭稳定化修复中土壤镉形态的影响  

Effects of freeze-thaw cycles on cadmium speciation in soils during stabilization remediation of biochar

作　　者：王月 孙剑平[1] 孙梨宗[2] 贾春云[2] 台培东[2] WANG Yue;SUN Jian-ping;SUN Li-zong;JIA Chun-yun;TAI Pei-dong(School of Municipal and Enuironmental Engineering,Shenyang Jianzhu University,Shen-yang 110168,China;Key Laboratory of Pollution Ecology and Environmental Engineering,Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]沈阳建筑大学市政与环境工程学院,沈阳110168 [2]中国科学院污染生态与环境工程重点实验室,中国科学院沈阳应用生态研究所,沈阳110016

出　　处：《生态学杂志》2021年第11期3711-3719,共9页Chinese Journal of Ecology

基　　金：国家重点研发课题(2018YFC1800703);国家自然科学基金项目(41877146,41673132);沈阳市中青年科技人才支持计划项目(RC200123)资助。

摘　　要：冻融是北方寒冷地区重要的气候变化过程,是影响土壤及稳定化材料性质的重要因素。本研究通过模拟冻融循环过程,考察了冻融对生物炭稳定化修复过程中镉(Cd)形态变化的影响,探讨冻融交替影响Cd形态变化的主要机理。结果表明:在生物炭稳定化修复过程中,冻融交替16次,土壤中弱酸提取态Cd含量提高了16.07%,可还原态Cd含量提高6.67%,可氧化态Cd含量升高15.37%,残渣态含量变化不明显,总体上土壤有效态Cd含量升高,增加了Cd的生态风险。其可能原因有:一方面,冻融交替16次,未加生物炭土壤自身弱酸提取态Cd含量升高11.74%,可还原态Cd含量升高13.53%;土壤毛管孔隙度从41.72%增加到57.63%,土壤p H值略有降低,土壤溶解性有机碳的含量呈现先显著升高15.38%后降低10.17%的趋势,共同促进了土壤-Cd体系中弱酸提取态和可还原态Cd的升高;另一方面,冻融交替过程中,生物炭的孔道管状结构及完整性遭破坏,羟基-OH、烷烃CH、芳香结构等伸缩振动峰减弱且发生偏移,碳酸盐成分减少,导致了生物炭对Cd吸附位点减少,吸附能力降低。Freeze-thawing is an important process in northern cold region of China,and it is an important factor affecting the properties of soil and materials for stabilizing heavy metals. In this study,a test of freeze-thaw cycles was carried out to examine the effects of freeze-thaw on the transformations of cadmium( Cd) form during the remediation of biochar for contaminated soils,with the underlying mechanism being analyzed. The results showed that,in the remediation process of biochar,after 16 cycles of freezing and thawing,the contents of weak acid extracted form Cd,reducible form Cd,and oxidizable form Cd in soil increased by 16.07%,6.67%,and15.37%,respectively,while the residue content remained stable. On the whole,the increasing content of available Cd will pose serious ecological risks. Two major reasons were responsible for such alterations. Firstly,without biochar addition,the content of weak acid extracted form Cd and reducible form Cd in soil increased by 11.74% and 13.53%,respectively. Soil capillary porosity increased from 41.72% to 57.63%,soil p H decreased slightly,and the content of soil dissolved organic carbon increased significantly by 15. 38% firstly and then decreased by 10. 17%over time. The combined effects of the above-mentioned factors increased weak acid extracted and reducible form Cd in soil-Cd system. Secondly,during the freeze-thaw process,the tubular structure and integrity of biochar were destroyed,the stretching vibrational absorptions of hydroxylOH,carbon-hydrogen bond C-H,and aromatic composition were weakened and shifted,and the carbonate composition were decreased,which resulted in the decrease of adsorption sites and adsorption capacity of biochar for Cd.

关 键 词：生物炭 冻融 镉形态 稳定化修复 

分 类 号：X53[环境科学与工程—环境工程]