广西典型岩溶区农田土壤-作物系统Cd迁移富集影响因素  

Factors Affecting the Translocation and Accumulation of Cadmium in a Soil-Crop System in a Typical Karst Area of Guangxi Province,China

作　　者：马宏宏 彭敏[1,2,3] 郭飞 刘飞 唐世琪[1,2,3] 杨峥[1,2,3] 张富贵[1,2,3] 周亚龙 杨柯[1,2,3] 李括 刘秀金[1,2,3] MA Hong-hong;PENG Min;GUO Fei;LIU Fei;TANG Shi-qi;YANG Zheng;ZHANG Fu-gui;ZHOU Ya-long;YANG Ke;LI Kuo;LIU Xiu-jin(Institute of Geophysical&Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang 065000,China;Research Center of Geochemical Survey and Assessment on Land Quality,China Geological Survey,Langfang 065000,China;Key Laboratory of Geochemical Cycling of Carbon and Mercury in the Earth's Critical Zone,Chinese Academy of Geological Sciences,Langfang 065000,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,廊坊065000 [2]中国地质调查局土地质量地球化学调查评价研究中心,廊坊065000 [3]中国地质科学院地球表层碳-汞地球化学循环重点实验室,廊坊065000

出　　处：《环境科学》2021年第3期1514-1522,共9页Environmental Science

基　　金：中国地质调查局地质调查项目(DD20160313,DD20190522);中国地质科学院地球物理地球化学勘查研究所基本科研业务项目(JY201906)。

摘　　要：为揭示岩溶区农田土壤-作物系统Cd迁移富集主要影响因素,选择广西典型岩溶区根系土-水稻籽实Cd含量及土壤pH值、有机质(OM)、氧化物含量和质地数据,通过Spearman相关性分析和主成分分析(PCA),开展了土壤理化性质对土壤和水稻籽实Cd含量的影响研究.结果表明,相比于全国土壤背景基准值,研究区土壤中总氧化铁(TFe_(2)O_(3))、三氧化二铝(Al_(2)O_(3))和氧化锰(MnO)相对富集,平均含量分别为20.2%、19.0%和0.2%,且区内广泛发育Fe-Mn结核;而二氧化硅(SiO_(2))相对亏损,平均含量为41.0%,呈现出典型的"脱硅富铝铁"特征,表明研究区土壤经历了较强烈的风化淋溶作用.相关性分析结果显示,土壤TFe_(2)O_(3)和MnO含量分别与土壤总Cd含量和残渣态Cd百分比呈显著的正相关性,与有效态Cd含量、水稻籽实Cd含量和Cd的生物富集系数(BCF)呈显著的负相关性.PCA分析结果也显示,土壤TFe_(2)O_(3)和MnO含量是影响土壤-作物系统Cd迁移富集的主要因素,而土壤pH值、OM和Al_(2)O_(3)含量等影响程度较小,SiO2含量和土壤质地间接地影响土壤-作物系统Cd的迁移富集.综合研究认为,土壤在交替氧化和还原条件下所形成的新生体Fe-Mn结核对Cd具有较强的吸附和固定作用,导致Cd在残渣态中相对富集,降低了土壤Cd的活动性,因此Fe-Mn结核是研究区土壤Cd生物有效性的主要影响因素.To understand the main factors influencing the translocation and accumulation of cadmium(Cd)in soil-crop systems in typical karst areas,68 sets of paddy soil and rice grain samples were collected in Guangxi Province.These were used to analyze Cd concentrations and soil properties(pH,organic matter(OM)content,oxide content,and texture).Spearman’s correlation coefficients and principal component analysis(PCA)were used to examine the effects of soil properties on Cd concentrations and identify the main influencing factors.The studied soils were highly enriched in iron oxide(TFe_(2)O_(3)),aluminum oxide(Al_(2)O_(3)),and manganese oxide(MnO)compared to background levels,with average concentrations of 20.2%,19.0%,and 0.2%,respectively.However,the soils are relatively depleted in silica(SiO2),with an average concentration of 41.0%.The soils are strongly weathered and leached in study area,giving rise to rich occurrences of Fe-Mn nodules.The concentrations of TFe_(2)O_(3) and MnO in the study soils were significantly correlated with soil Cd,rice seed Cd,and the Cd bioconcentration factor(BCF).The PCA analysis further showed that TFe_(2)O_(3)and MnO in soils were the main factors affecting the migration and enrichment of Cd while soil pH,OM,and Al_(2)O_(3) had less of an influence.Furthermore,SiO2 and soil texture indirectly affected the migration and enrichment of Cd.It is suggested that the Fe-Mn nodules effectively adsorb and immobilize Cd in the study area soils,acting as a heavy metal scavenger that reduced the biological accessibility of Cd.

关 键 词：岩溶区 CD 生物有效性 Fe-Mn结核 土壤-作物系统 

分 类 号：X171.5[环境科学与工程—环境科学]