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氢氧稳定同位素示踪技术是研究土壤-作物-大气连续体(SPAC)水分循环的重要手段。激光同位素分析仪以其独特的优点逐渐得到广泛应用,但其在测量植物水时,与同位素质谱仪的测量结果存在差异。本文采用Los Gatos Research公司生产的激光同位素分析仪DLT-100分别测定植物水、土壤水、雨水和地下水等共19个样品,并用其开发的光谱污染矫正软件标记和量化水样品的污染,修正污染水样品的同位素值,然后与同位素质谱仪进行比对。结果表明:土壤水、雨水和地下水等样品均未受到污染,而植物样品均受到一定程度的光谱干扰;植物水的δD和δ18O修正范围分别是1.21‰～26.65‰和0.50‰～18.27‰。该修正方法消除了δD测定的差异,并大大降低了δ18O的偏差。可见,激光同位素分析仪法在测量土壤水、雨水和地下水同位素时可以有效地代替传统的同位素质谱仪法,但对植物水的测量时,则首先需要判断样品是否受到光谱干扰,如果受到污染,仍需同位素质谱法进行确认。
Hydrogen-oxygen stable isotope tracing technique is an important method to study the water cycle of soil-crop-atmosphere continuum (SPAC). Laser isotope analyzers are gaining popularity due to their unique advantages. However, they are different from isotope mass spectrometry when measuring plant water. In this paper, a total of 19 samples such as plant water, soil water, rainwater and groundwater were measured by laser isotope analyzer DLT-100 manufactured by Los Gatos Research Company. The developed spectral pollution correction software was used to mark and quantify the contamination of water samples and to correct the pollution Isotopic values of water samples are then compared with isotope mass spectrometers. The results showed that soil water, rainwater and groundwater samples were not contaminated, while plant samples were affected by some spectral interferences. The correction ranges of δD and δ18O of plant water were 1.21 ‰ ~ 26.65 ‰ and 0.50 ‰ ~ 18.27 ‰, respectively. This correction method eliminates the difference in the δD determination and greatly reduces the deviation of δ18O. It can be seen that the laser isotope analyzer method can effectively replace the traditional isotope mass spectrometry when measuring isotopes of soil water, rainwater and groundwater. However, when measuring water of plants, the first step is to determine whether the sample is subject to spectral interference. If it is contaminated, Is still to be confirmed by isotope mass spectrometry.