真空蒸馏技术提取土壤水实验研究

Soil water extraction using vacuum distillation technology

简要介绍共沸蒸馏、真空蒸馏、离心分离、锌的微量蒸馏4种土壤水提取技术,并对其优缺点进行了比较.对黏土含量较高且达到田间持水量的土壤在提取温度为100℃、连续加热5 h条件下,真空蒸馏提取土壤水进行氢氧稳定同位素分析.结果表明:真空蒸馏技术在提取温度为100℃和连续加热5 h条件下,土壤水提取百分比接近100%;土壤中有部分弱束缚水被提取出来,约占提取水分的0.45%;对土壤含水量较高的黏土,δ(D)和δ(18O)最大提取误差(提取的土壤水与加入水同位素的差值)分别为-1.2%和-0.07%,提取的土壤水同位素都贫化.

Four kinds of methods for soil water extraction, azeotropic, vacuum, centrifugal and zinc micro-distillation, are introduced and compared. The stable hydrogen and oxygen isotopic concentrations of the soil water from soils with high clay content and required field capacity, extracted using vacuum distillation technology with an extraction temperature of 100℃ and continuous heating for five hours, were analyzed. The results show that the percentage of soil water extraction when using the vacuum method is close to 100% under the conditions described above; some weakly bound water in the soils is extracted, making up about 0.45 % of the extracted water. For clay soils with a high water content, the maximum extraction errors （isotopic differences between the extracted water and the added water） of δ （D） and δ（^ 18O） are - 1.2% and - 0.07%, respectively, and the isotopic concentrations of extracted water are lower than those of the added water.