苏南典型区农田土壤硒-镉拮抗作用研究

以苏南典型区2027套稻米-土壤样品的Se、Cd含量及其相关的元素地球化学调查数据为基础,通过元素相关性统计分析及生物富集系数(BCF)等分布特征研究,本文探讨了农田土壤中Se与Cd的拮抗作用及其控制因素。结果表明：1)土壤中Se和Cd分布共消长特征明显,两者之间具有显著正相关性、相关系数R最高可达0.87；2)有关岩石、陶瓷原料、河泥等均可成为农田富集Se、Cd的物质来源,且多为富Cd强于富Se,只有源于富硒岩石的富硒土壤可排除Cd污染干扰、其开发利用价值最高；3)稻米Se与Cd的生物富集系数多介于0.1～0.8之间,土壤偏碱性有利于稻籽吸收Se、偏酸性则有助于稻籽吸收Cd,受土壤Se、Cd同富集之影响,富硒米与镉超标大米可能同时出现；4)土壤富Se抑制稻米Cd吸收是有条件的,当土壤Se大于0.4mg/kg、总有机碳大于1.5%时,稻米Cd与土壤Se、Cd生物富集系数与土壤Se之间均存在显著负相关性,相关系数R分别为-0.74、-0.56；5)pH与Cd生物富集系数、TOC与Se生物富集系数之间也有显著负相关性,其相关系数R分别为-0.79、-0.65。

Antagonism Between Se and Cd in Typical Farmland Soil in Southern Jiangsu Province

Based on the geochemical data of Se, Cd and other elements of 2 027 rice-soil samples in the typical areas of southern Jiangsu Province, this paper discussed the antagonism and controlling factors of Se and Cd in farmland soils by statistical analysis of element correlation and distribution characteristics such as biological enrichment coefficient (BCF). The results showed that:1) The distributions of Se and Cd in soils had obvious characteristics of co-fluctuation, and significant positive correlation existed between the two elements (correlation coefficient r=0.87). 2)Rocks, ceramic raw materials, river mud and so on could be the substance sources of Se and Cd enrichment in farmland, and Cd enrichment was usually stronger than Se enrichment. Only Se-enriched soils derived from Se-enriched rocks could eliminate the interference of Cd pollution and produce natural Se-enriched foods. 3)BCFs of Se and Cd in rice were mostly between 0.1 and 0.8, alkaline soil was beneficial for rice seeds to absorb Se and acid soil was beneficial for rice seeds to absorb Cd. Under the influence of soil Se and Cd co-enrichment, rice could simultaneously be Se-enriched while Cd-excessed. 4)Soil Se-enrichment inhibited Cd uptake in rice under certain conditions, when soil Se concentration > 0.4 mg/kg and total organic carbon >15 g/kg, significant negative correlations existed between rice Cd concentration and soil Se concentration (r=-0.74), and between rice Cd BCF and soil Se concentration (r=-0.56), significant negative correlations also existed between soil pH and rice Cd BCF (r=-0.79), and between soil total organic carbon and rice Se BCF (r=-0.65).