四川XX地土壤–农作物有害元素和硒的地球化学评价及根系土镉形态分析

Geochemical Evaluation of Harmful Elements and Selenium in Soil to Crops and Speciation Analysis of Cadmium in the Rhizosphere in XX, Sichuan Province

摘要: 土壤中有害元素的高含量对农作物的品质影响很大，易造成农作物中有害元素富集，从而对人体或动物造成毒性；研究因开采硫铁矿制硫酸而造成的土壤污染区农作物有害元素的特征状况具有重要意义。本文以土壤–农作物为研究对象，针对水稻、玉米、蔬菜及其根系土的有害元素及有益元素硒等进行研究，水稻籽实及玉米符合稻谷污染物限量标准，部分蔬菜中镉含量超标。不同农作物对同一元素的富集作用不同，研究区内各农作物对硒元素的富集作用主要表现为水稻 > 玉米 > 萝卜 > 青菜 > 红薯 > 白菜 > 莴笋，对镉元素富集作用表现为莴笋 > 萝卜 > 青菜 > 水稻 > 红薯 > 白菜 > 玉米。各农作物根系土的镉含量较高，以部分蔬菜根系土镉含量最高，蔬菜根系土中的镉大多以离子交换态的赋存形式存在，这类镉的活性较大，在自然界中易迁移转化，能够被植物吸收，是造成部分蔬菜镉含量高从而超过食品安全标准的主要原因。水稻及玉米中镉含量低的原因，除了与土壤镉含量及镉形态有关外，土壤中硒和锌的高含量也有一定的抑制农作物对镉的吸收作用，研究区水稻及玉米中富硒，可发展富硒稻谷和富硒玉米。

Abstract: The high content of harmful elements in soil has great influence on crops. It is easy to cause harmful elements in crops to be enriched so as to cause toxicity to the human body, animals and plants; it is of great significance to study the characteristics of harmful elements in crops in the polluted areas caused by the exploitation of pyrite to produce sulphuric acid. In this paper, we take soil to crops as the object of study; the harmful elements and selenium in rice, corn, vegetables and rhizosphere are studied; the content of pollutant elements in the corn seeds and rice accord with the rice pollutant limit standard, while the content of Cd in some vegetables exceeded standard. The crops in the study area have different ability to enrich same element, rice has the greatest ability to enrich Se, then followed by corn, radish, greengrocery, sweet potato, cabbage and lettuce. Lettuce has the greatest ability to enrich Cd, then followed by radish, greengrocery, rice, sweet potato, cabbage and corn. The content of cadmium in the rhizosphere is high, especially in the rhizosphere of some vegetable; cadmium ion exchange state is the main form of cadmium in the rhizosphere of vegetable; it is more active, easy to migrate and change in nature, and can be absorbed by plants. It is the main reason that causes high the cadmium content of some vegetables to exceed the food safety standards. The cadmium content of rice and corn are low; in addition to the cadmium content and cadmium forms in soil, high content of selenium and zinc in soil also has certain inhibitory effects on crop absorption of cadmium. Due to the high selenium content of rice and corn in the study area, we can develop selenium-enriched rice and selenium-enriched corn.