温度和过饱和度对海水中碳酸钙沉淀速率的影响Ⅰ.镁方解石

摘要

Using the constant addition system, the precipitation of Mg-calcite in seawater was experimentally investigated at 5, 15, and 25 ℃. It was observed that, at each temperature, the relation between Mg-calcite precipitation rates and saturation states can be well expressed in the kinetic form of R=k(Ω-1)<'n> or Log(R)=nLog(Ω-1)+Log(k). The change of pCO2 would result in the remarkable variation of Mg-calcite precipitation rates, while it would not affect the kinetic expression of Mg-calcite precipitation. On the other hand, there are remarkable discrepancies among the kinetic expressions obtained at different temperatures, which indicate the thermodynamic relevance of the kinetic process of Mg-calcite precipitation.%采用稳定加液一反应系统对5、15和25 ° C下镁方解石沉淀在海水中的形成过程进行了研究.结果表明镁方解石的沉淀速率(R)对过饱和度(Ω)的响应均可通过R=k(Ω-1)°或Log(R)=nLog(Ω-1)+Log(k)形式的动力学方程加以表达.pCO2的变化会显著改变过饱和度进而影响到镁方解石沉淀速率,但这一变化并不会对镁方解石沉淀形成过程的动力学表达产生影响.相比之下,不同温度下镁方解石沉淀形成的动力学方程存在明显差异,表明这一动力学过程同时还具有强烈的热力学相关性.