浙江建德市耕地表层土壤硒分布、来源及生态效应

硒是重要的生命元素之一,对动物及人体健康具有重要意义。系统总结了建德市耕地表层土壤硒地球化学特征,分析了土壤硒的分布规律及其与黑色岩系之间的成因联系,探讨了黑色岩系富硒机制,研究了水稻植株中硒富集规律。结果表明,建德市耕地表层土壤硒含量介于0.06~11.5 mg/kg之间,均值为0.35 mg/kg,不同地质背景、成土母质、土壤类型中土壤硒含量差异显著。根据土壤硒和重金属含量,圈出清洁富硒土壤2 647 hm²,主要分布于寒武系灰岩、碳质页岩、钙质泥岩等岩石出露区,指示土壤富硒与这套寒武系“黑色岩系”有密切关系。古沉积学研究认为,黑色岩系形成于缺氧滞水的沉积环境,富含有机质的海底沉积物大量吸附来自地幔的硒,成岩后形成富含硒等元素的黑色岩系。水稻根系土中硒形态组成分析表明,醋酸溶解态硒占比较小,残渣态占比较大,说明水稻根系土中硒可利用性较低。稻米、莲子、草莓及其根系土采样分析表明,稻米对土壤硒的富集系数最高,水稻植株中硒含量具有根>叶>茎≈籽实的特征。

Distribution,Sources and Ecological Effects of Selenium in Topsoil of Cultivated Land in Jiande City,Zhejiang Province

Selenium is one of the important life elements, which is of great significance to animal and human health. In this paper, we systematically summarized the geochemical characteristics of selenium in topsoil of cultivated land, and analyzed the distribution law of selenium in soil and the genetic relationship between selenium and black rock series. We also discussed the selenium enrichment mechanism in black rock series, and studied the selenium enrichment law in rice plants. We hope that these studies are helpful to reveal the source and ecological effect of selenium in soil of Jiande City. Our results show that the selenium content in topsoil of cultivated land in Jiande City ranges from 0.06 to 11.5 mg/kg, with an average of 0.35 mg/kg. The difference of selenium content in soil is very significant in different geological background, soil parent materials and soil types. In our study aera, 2,647 hectare of clean selenium-rich soils were delineated according to the content of selenium and heavy metals in the soil. Selenium-rich soils are mainly distributed in Cambrian limestone, carbonaceous shale, calcareous mudstone, indicating that the enrichment of selenium in the soil is closely related to the Cambrian “black rock series”. Paleosedimentology research shows that the black rock series were formed in the sedimentary environment of anoxic stagnant water. The organic-rich submarine sediments adsorbed a large amount of selenium from the mantle. After the consolidation and diagenesis, the black rock series which are rich in selenium and other elements were formed. The morphological characteristics of selenium in rice root soil in this study area show that the proportion of acetic acid soluble selenium is relatively small, while the proportion of residual selenium is relatively large, indicating that the availability of selenium in rice root soil is low. The selenium contents in rice, lotus seed and strawberry show that rice has the highest selenium enrichment coefficient, and the selenium content in rice plants was characterized by root > leaf > stem ≈ seed.