连续三年施用改良剂对镉污染稻田的修复效果研究

Remediation of Cadmium-contaminated Rice Fields by Three Consecutive Years of Amendment Application

[目的]本研究目的为探讨连续三年施用石灰、生物炭和硅肥对中度镉污染稻田的修复效果。[方法]以湖南省典型双季稻区土壤-水稻系统为研究对象,采用随机区组设计,共设对照(T_(1))、施用石灰(T_(2))、施用生物炭(T_(3))和施用硅肥(T_(4))4个处理,分析施用不同改良剂的稻田土壤理化性质和水稻镉含量特征,通过冗余分析与回归分析探究土壤因子对镉在土壤-水稻系统中迁移转运的影响。[结果]相较于T_(1)处理,T_(2)处理土壤pH显著增加至6.92±0.05,土壤有效镉降低至0.41±0.09 mg kg^(-1);T_(3)、T_(4)处理与T_(1)处理相比,土壤pH、有效镉、活性有机质均无显著差异。T_(3)处理早稻和晚稻糙米镉含量最高,分别为0.54±0.07和0.11±0.04 mg kg^(-1);T_(2)处理最低,分别为0.16±0.00和0.03±0.01 mg kg^(-1)。冗余分析结果表明:糙米中镉含量(RiCd)与土壤pH负相关,与有效镉含量(DPTA-Cd)正相关。糙米中镉含量与土壤有效镉含量的关系式为:RiCd(mg kg^(-1))=-0.0822+0.297 DPTA-Cd(mg kg^(-1))(R_(adj)^(2)=0.503,P<0.05)。[结论]连续三年施用石灰对中度镉污染稻田有较好修复效果,其主要通过提升土壤pH,降低土壤有效镉含量,进而降低水稻糙米镉含量。

[Objective]The aims were to investigate the remediation effect of lime,biochar and silicon fertilizer on moderate Cdcontaminated rice fields after three consecutive years of application.[Method]The soil and rice system of typical double-cropping rice area in Hunan Province was selected as the research object.Four treatments,control(T_(1)),application of lime(T_(2)),biochar(T3)and silicon fertilizer(T_(4)),were used in conducted in a randomized group design to analyze the physicochemical properties of paddy soil and the cadmium content of rice with different amendments.The effects of soil factors on cadmium transport in soil-rice system were investigated by redundancy analysis and regression analysis.[Results]The results showed that T_(2) increased soil pH to 6.92±0.05,soil available Cd decreased to 0.41±0.09 mg kg^(-1) compared with T_(1).There were no significant differences in soil pH,available Cd and dissolved organic matter in T_(3) and T_(4) treatments compared with T_(1) treatments.Cd content in brown rice in T3 treatment were the highest in the early and late season at 0.54±0.07 and 0.11±0.04 mg kg^(-1).The T_(2) treatment had the lowest at 0.16±0.00 and 0.03±0.01 mg kg^(-1).The redundancy analysis showed that Cd content in brown rice was negatively correlated with soil pH and positively correlated with soil available Cd(DPTA-Cd).The relationship between brown rice cadmium content(RiCd)and soil available Cd was as follows:RiCd mg kg^(-1)=-0.0822+0.297 DPTA-Cd mg kg^(-1)(R_(adj)^(2)=0.503,P<0.05).[Conclusion]Continuous application of lime for 3-year effectively remediated paddy fields under moderately cadmium pollution due to soil pH increase and soil available cadmium reduction,could cut down the Cd content in brown rice.