渤海东海海洋沉积物中碳氮稳定同位素标准物质研制

摘要

海洋沉积物中碳氮稳定同位素因其能够确定有机质的来源,有助于了解碳循环、气候变化、有机质迁移转化而备受关注,但其分析测试过程中尚缺乏海洋沉积物碳氮稳定同位素标准物质进行质量监控.本文依据ISO导则35和国家《一级标准物质技术规范》(JJG1006-1994),研制了三个海洋沉积物碳氮稳定同位素标准物质(MSCNI-1、MSCNI-2和MSCNI-3),候选物样品分别采自我国渤海锦州湾湿地、东海闽浙近岸和东海冲绳海槽,定值组分为总碳氮同位素(δ13C-TC、δ15N-TN)和有机碳氮同位素(δ13C-Corg、δ15N-Norg),定值方法采用元素分析-同位素比值质谱法(EA-IRMS)多家实验室协同定值.经检验,三个标准物质候选物均匀性良好,一年内定值组分均无显著变化,具有良好的稳定性;δ13C和δ15N的标准不确定度分别小于0.15%和0.24%,标准值和标准不确定度合理.该套标准物质是我国以海底沉积物为介质的基体型碳氮稳定同位素标准物质,定值方法准确可靠,可供海洋、地质及环境等相关领域实验室用于仪器校准、方法评价和质量监控等.%The stable isotope of carbon and nitrogen (δ13C and δ15N) in marine sediments have received much attention as they can be used to trace the sources of organic matter and are helpful in understanding the carbon cycle, climate change and the transformation of organic matter in the ambient environment.However, during stable carbon and nitrogen isotopic analysis and testing, the standard reference materials for quality control are limited.Three reference materials of carbon and nitrogen stable isotope (MSCNI-1, MSCNI-2 and MSCNI-3) have been developed from marine sediments in the Bohai Jinzhou Bay, the coast of Fujian and Zhejiang in the east part of the China sea and the ocean through Okinawa within the East China Sea, respectively.All of these reference materials have certified values of the total carbon and nitrogen isotope (δ13C-TC, δ15N-TN) and organic carbon and nitrogen isotope (δ13C-Corg, δ15N-Norg) which were determined by an inter-laboratory comparison of 8 participating laboratories, using Element Analysis-Isotope Ratio Mass Spectrometry (EA-IRMS).The analytical results indicate that three reference materials were homogeneous (in Table 1) and stable (in Table 2) as the certified values had no statistically variations within a year.The standard uncertainties of δ13C and δ15N were less than 0.15% and 0.24% (in Table 4), respectively.Both of the certified values and uncertainties are within acceptable limits.The reference materials of natural carbon and oxygen isotopes were initially developed based on marine sediments in China.The test method was accurate and reliable, thus it is anticipated that it can be used for instrument calibration, method evaluation and quality control in related laboratories such as marine, geological and environmental fields.