26 typical samples were collected from paddy soils in Southern Jiangxi Province and the total Selenium (Se) concentrations, phosphate extractable Se, pH and SOM were analyzed to better understand the composition and features of bioavailable Se in the hilly red paddy soil of Southern China. The total soil Se concentration was 234.7μg/kg (n = 26), which belonged to the moderate level. Organic Se was the predominant fraction in the soil extract, approximately accounting for 90% of the available Se in soil (8.88μg/kg). The concentration of Selenite (0.62μg/kg, n=26) in the soil extract was higher than that of Selenate (0.47μg/kg,n=21). Se species including organic Se, inorganic Se and Selenate in the soil extract were significantly positively correlated with the total Se in soil and Se in soil extract (P<0.05). Soil pH slightly increased with land elevations while the species of Se in the soil extract decreased except Selenite. There was no significant correlation between pH, SOM and Se species in soil extract (P>0.05), however, the effect of SOM on transformation of Selenite in soil and its bioavailability need further study.%为了更好地了解我国南方低丘红壤水稻土中生物有效硒的组成与特性,在赣南地区采集了26份代表性土样,并对土壤总硒、磷酸盐提取态硒及土壤pH、土壤有机质等进行了测定分析.结果表明:研究区域土壤总硒为234.7μg/kg(n=26),属于中等含硒水平土壤.有机硒是土壤浸提液中硒的主要存在方式,约占土壤可提取态硒(8.88μg/kg)的90%.土壤浸提液中亚硒酸盐含量(0.62μg/kg,n=26)高于硒酸盐(0.47μg/kg,n=21).除亚硒酸盐外,土壤浸提液中各形态硒(包括有机硒、无机硒和硒酸盐)与土壤总硒或可提取态硒均具有显著的正相关关系(P<0.05).随高程增加土壤pH略有升高,而土壤各形态硒(亚硒酸盐除外)则有不同程度的下降趋势.土壤pH、有机质与土壤浸提液中各形态硒均无明显的相关关系(P>0.05),不过,有机质对土壤中亚硒酸盐的形态转化及其生物有效性的影响值得进一步研究.
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