四种浸提剂对果园与菜地土壤有效硒浸提效果的对比研究

有效硒是评价土壤中硒对植物供给能力的重要指标,我国目前尚无测试有效硒的国家标准方法。浸提剂的选择对于准确测定有效硒的含量至关重要,本文根据浸提的有效硒与硒形态的关联性来确定最优浸提剂种类。实验中选取了碳酸氢钠、磷酸二氢钾、硝酸和盐酸四种浸提剂,对天津果园和菜地的土壤进行有效硒浸提,采用原子荧光光谱法测定各形态硒的含量,并分别对浸提的有效硒与水溶态+离子交换态+碳酸盐结合态硒的最小值、25%处数据值、中位数、75%处数据值和最大值进行比较分析和差异性检验。结果表明:采用碳酸氢钠和磷酸二氢钾提取菜地土壤有效硒的平均含量均约为0.039mg/kg,高于硝酸和盐酸的提取量;采用碳酸氢钠、磷酸二氢钾、硝酸和盐酸提取果园土壤有效硒的含量依次降低。两种土壤中,磷酸二氢钾浸提有效硒的最小值、25%处数据值、中位数、75%处数据值和最大值与水溶态+离子交换态+碳酸盐结合态硒的含量最为接近,而且无显著差异性。研究认为,0.1mol/L磷酸二氢钾适合作为天津果园和菜地土壤有效硒的浸提剂。

A Comparative Study of Four Extractants on the Extraction of Available Selenium in Vegetable and Orchard Soils

BACKGROUND: Available selenium is an important index to evaluate the supply capacity of selenium from soil to plants. However, there is no national standard method to test available selenium in China. The selection of extractants is very important for the accurate determination of available selenium.
OBJECTIVES: To determine the optimum extractant based on the correlation between available selenium and selenium species.
METHODS: Four extractants, sodium bicarbonate, potassium dihydrogen phosphate, nitric acid and hydrochloric acid, were selected to extract the available selenium from vegetable and orchard soils in Tianjin. Atomic fluorescence spectrometry was used to determine the content of various forms of selenium, and the minimum, 25 percentile, median, 75 percentile, maximum value of the effective selenium and water-soluble+ion-exchange+carbonate-combined selenium were used for comparative analysis and the difference.
RESULTS: The average content of available selenium extracted from vegetable soils by sodium bicarbonate and potassium dihydrogen phosphate was 0.039mg/kg, which was higher than that of nitric acid and hydrochloric acid. The contents of available selenium extracted from orchard soils by sodium bicarbonate, potassium dihydrogen phosphate, nitric acid and hydrochloric acid decreased in turn. The minimum, 25 percentile, median, 75 percentile, and maximum values of available selenium extracted by potassium dihydrogen phosphate in the two soils were closer to the content of sum of water-soluble, ion-exchange and carbonate combined selenium.
CONCLUSIONS: Potassium dihydrogen phosphate with a concentration of 0.1mol/L was the optimum extractant of available Se for vegetable and orchard soils in Tianjin.