四川某地区土壤中Cd、Se微量元素含量水平及有效性特征初步研究

A Preliminary Study on the Content Levels and Availability Characteristics of Cd and Se Trace Elements in Soil of a Region in Sichuan Province

为合理布局种植规划,保障土壤环境质量及农产品安全,采集区内表层土壤(0~20 cm),分析检测Cd、Se、有效镉、有效硒含量及pH值,通过数理统计的方法,对区内土壤中Cd、Se元素含量水平进行评价,探讨其有效性特征。区内土壤中Cd元素含量范围为0.21~1.22 mg/kg,均未超过“管控值”,92.19%的样品超过“筛选值”,可能存在生态环境风险,土壤pH≤6.5条件下Cd元素平均含量(0.44 mg/kg)低于其在pH>6.5条件下平均含量(0.72 mg/kg),Cd元素有效度与土壤pH值均呈负相关,表现为Cd元素有效性随土壤pH值升高呈明显下降趋势;Se元素平均含量(0.63 mg/kg)达到富硒土壤要求(大于0.40 mg/kg),其含量、有效度与土壤pH值关系较弱,含量基本稳定。区内分布大片高镉富硒土地属自然背景继承,酸性土壤环境下Cd元素活性程度较大,随pH值升高Cd元素活性程度下降趋势明显,表明农作物吸收土壤中Cd元素水平呈下降趋势亦明显,同时Se元素活性程度受土壤pH值影响较弱。可通过控制土壤pH值,合理布局种植规划,为规避或降低土壤中高镉可能带来的生态环境风险,发展清洁富硒农产品提供科学依据及思路。

In order to rationally arrange planting planning,ensure the quality of soil environment and the safety of agricultural products,this paper collected the topsoil(O~20 cm)in the study area,analyzed and tested the contents of Cd,Se,available cadmium,available selenium and pH value.evaluated the content levels of Cd and Se elements,discussed its availability characteristics by means of mathematical statistics.The content of Cd elements range from 0.21~1.22 mg/kg,which did not exceed the"control value",and 92.19%of samples exceeded the"Screening values"in soil in the area,which may have ecological environment risk.The average content of Cd elements(0.44 mg/kg)under soil pH≤6.5 is lower than that under soil pH>6.5(0.72 mg/kg),and the availability of Cd elements was negatively correlated with soil pH value,because the availability of Cd element significantly decrease with the increase of soil pH value:The average content of Se element(0.63 mg/kg)reaches the requirements of Selenium-enriched soil(more than 0.40 mg/kg),and its content and availability degree have a weak relationship with soil pH value,and basically stable.Large areas of land with high content cadmium element and selenium-enriched soil in the area are inherited from the natural background.The degree of activity of Cd element is larger in the acidic soil environment,with the increase of soil pH value the activity degree of Cd element shows downward trend obviously,indicating that the level of Cd element in soil by crops also significantly decreasing,while the activity of Se element is weakly affected by soil pH value.The ecological and environmental risks caused by high cadmium in soil can be avoided or reduced by controlling soil pH value and rational planting planning.It provides scientific basis and ideas for developing clean selenium-rich agricultural products.