摘要
天然气水合物的形成会造成氢、氧同位素的分馏。在实验室合成研究中,利用天然海水[(含0.03%十二烷基硫酸钠(SDS)]与甲烷气体反应,通过对水合物生成前后溶液中的Cl-的质量浓度和氢、氧同位素组成的测定,研究了天然气水合物生成过程中氢、氧同位素的分馏情况。实验证明氢、氧的重同位素易于富集在水合物中,其在天然海水-甲烷体系中的分馏系数分别为1.018～1.036和1.0034～1.0063,这一分馏系数稍大于前人在纯水和NaCl溶液中所测得的分馏系数。
Gas hydrate is one of sediments beside continental slopes the most important potential energy and continental perennial frost zones. resources, distributing mainly in marine On the other hand, owing to its instability and high methane contents, gas hydrates is a factor inducing geological hazards and global climate changes. At present, element geochemical data about gas hydrates are from sediments containing gas hydrates and related pore fluids. Due to the instability of gas hydrates, sampling processes are often unable to guarantee the actual situations of the gas hydrates strata. As a whole, studies on element geochemistry during gas hydrates forming processes are relatively inadequate. Purposes of this study are to illustrate the characteristics of hydrogen and oxygen isotopic fractionation during gas hydrates formation through experimental simulation. Seawater added by 0.01% sodium dodecyl sulfate （SDS） and pure methane are used to form methane hydrate, and then Cl^- mass concentration and hydrogen and oxygen isotopic compositions of remain fluid are analyzed. Fractionation factors of H and O isotope are calculated by using the equations （Tatsuo Maekawa, 2004）, and they are 1. 018-1. 036 and 1. 003 4-1. 006 3, respectively. The results show that the heavier isotopes have an aptitude to concentrate in gas hydrates and the lighter isotopes have an aptitude to concentrate in liquid. Considering the ubiquitous isotope anomalies in the sediment pore-waters rich in gas hydrates,it is thought that salt exclusion during gas hydrate formation is the cause for these anomalies.
出处
《地球化学》
CAS
CSCD
北大核心
2005年第6期605-611,共7页
Geochimica
基金
国家高技术研究发展计划项目(2001AA6110-20)~~
关键词
天然气水合物
实验模拟
同位素分馏
氢同位素
氧同位素
gas hydrate
experimental simulation
isotope fractionation
hydrogen isotope
oxygen isotope
