Solubilities of nitrogen and argon in basalt melt under oxidizing conditions
Solubilities of nitrogen and argon in basalt melt under oxidizing conditions
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氧化条件下氮和氩在玄武岩熔体中的溶解度
DOI：
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发表时间：
2008
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通讯作者：
N. Sugiura
中科院分区：
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作者：
A. Miyazaki;H. Hiyagon;N. Sugiura
我们使用15N15N标记的空气（Ptotal=1 atm）在1300°C高氧化条件下（P(O2)=0.16 ~ 0.37 atm）测量了玄武岩熔体中氮和氩的溶解度。得到的溶解度（Henry’s常数）分别为K(N2)=（1.3‐2.9）×10−9 mol/g/atm和K(Ar)=（2.6‐4.5）×10−9 mol/g/atm，表明在高氧化条件下，氮的溶解度略低于Ar。溶解度实验中使用的15N15N标记气体同位素不平衡，但15N15N含量高，即气体中14N14N: 14N15N: 15N15N的比值不是1:2r: r2，其中r=15Ntotal/14Ntotal。从合成玄武岩玻璃中回收的气体也表现出类似的同位素不平衡。这表明在熔体中气体溶解过程中，N2分子之间没有发生同位素交换。换句话说，在目前（高度氧化）的实验条件下，溶解在玄武岩中的氮以分子形式融化。
We measured solubilities of nitrogen and argon in basalt melt at 1300 °C under highly oxidizing conditions (P(O2)=0.16‐0.37 atm) using 15N15N‐labeled air (Ptotal=1 atm). The obtained solubilities (Henry’s constants) are K(N2)=(1.3‐2.9)×10−9 mol/g/atm and K(Ar)=(2.6‐4.5)×10−9 mol/g/atm, respectively, showing that the solubility of nitrogen is slightly lower than that of Ar under highly oxidizing conditions. The 15N15N‐labeled gas used in the solubility experiment was not isotopically in equilibrium but highly enriched in 15N15N, that is, the ratios of 14N14N: 14N15N: 15N15N in the gas were not 1: 2r: r2, where r=15Ntotal/14Ntotal. The recovered gas from the synthetic basalt glass also showed similar isotopic disequilibrium. This suggests that isotopic exchange among N2 molecules did not occur during dissolution of the gas in the melt. In other words, nitrogen dissolved in the basalt melt as molecules in the present (highly oxidizing) experimental conditions.