Comparative soil CO2 flux measurements and geostatistical estimation methods on Masaya volcano, Nicaragua

We present a comparative study of soil CO₂ flux () measured by five groups (Groups 1–5) at the IAVCEI-CCVG Eighth Workshop on Volcanic Gases on Masaya volcano, Nicaragua. Groups 1–5 measured using the accumulation chamber method at 5-m spacing within a 900 m² grid during a morning (AM) period. These measurements were repeated by Groups 1–3 during an afternoon (PM) period. Measured ranged from 218 to 14,719 g m⁻² day⁻¹. The variability of the five measurements made at each grid point ranged from ±5 to 167%. However, the arithmetic means of fluxes measured over the entire grid and associated total CO₂ emission rate estimates varied between groups by only ±22%. All three groups that made PM measurements reported an 8–19% increase in total emissions over the AM results. Based on a comparison of measurements made during AM and PM times, we argue that this change is due in large part to natural temporal variability of gas flow, rather than to measurement error. In order to estimate the mean and associated CO₂ emission rate of one data set and to map the spatial distribution, we compared six geostatistical methods: arithmetic and minimum variance unbiased estimator means of uninterpolated data, and arithmetic means of data interpolated by the multiquadric radial basis function, ordinary kriging, multi-Gaussian kriging, and sequential Gaussian simulation methods. While the total CO₂ emission rates estimated using the different techniques only varied by ±4.4%, the maps showed important differences. We suggest that the sequential Gaussian simulation method yields the most realistic representation of the spatial distribution of , but a variety of geostatistical methods are appropriate to estimate the total CO₂ emission rate from a study area, which is a primary goal in volcano monitoring research.Editorial responsibility: H Shinohara     

Coring experiments with cryogenic water and carbon dioxide ices—toward planetary surface operations

As a prelude to the design of sampling devices able to extract materials from the icy surfaces of comets, outer-planet satellites, and the martian poles, it is necessary to understand some of the physical properties of these ices. To this end we have investigated the mechanical resistance displayed by two ices subjected to coring operations at low temperatures and under vacuum. The ices used in this study were water ice, frozen from liquid water, and carbon dioxide ice grown from its vapour. The coring tool employed had dimensions and required power levels that were comparable to a sample extraction system designed for a present-day spacecraft lander. The specific cutting strength, a parameter that measures the toughness of the material, has been measured while coring these two ices. For water ice this property rose from at an ice temperature of , to at . At the lower temperature of , pore-free carbon dioxide ice has also been measured to have a specific cutting strength approximately half that of water ice at the same temperature. These laboratory-based measurements may be used as guides for the power levels needed to core solid water and CO₂ ices at certain rates.     

南极昭和站大气中CO_2浓度变化

本文作者于1987～1988年由国家南极考察委员会派遣随JARE29赴日本南极昭和站、瑞穗站和阿斯加等站进行考察,根据日本同行提供的1984～1988年昭和站大气中二氧化碳浓度连续变化资料以及相应年份该站年平均气温资料进行研究,结果表明:从1984年到1988年该站大气中二氧化碳浓度变化趋势与该站年平均气温变化趋势是相当一致的,二者呈明显正相关。此外,还给出该地区从1984年到1988年大气中二氧化碳浓度变化的年增长率,其值分别为1.21ppmV/年(1984～1985年)、1.35ppmV/年(1985～1986年)、1.68ppmV/年(1986～1987年)和1.99ppmV/年(1987～1988年)。     

利用化探精查技术检测二氧化碳气藏

化探精查技术检测二氧化碳气藏异常方法是基于油气渗透理论,通过对CO₂(土壤或水中)和土壤全烃、碳酸钙、汞、同位素、荧光等地表地球化学指标组合异常的分析,结合地质—地球物理资料,预测CO₂气藏分布。笔者通过对济阳坳陷花沟地区化探方法、化探资料和气藏分布的综合分析,在区域地球化学背景分析研究基础上,指出区带异常,并结合油气地质、地球物理资料,对圈定的化探异常区进行分级评价,预测CO₂气藏聚集的有利区带,探索化探精查预测技术检测CO₂气藏的方法。     

古海水pH值代用指标——海洋碳酸盐硼同位素研究进展

仪器测量的海水pH记录太短，无法评估海水pH自然变化的频率和幅度,并预测未来大气CO₂急剧增加后海水酸度的响应。海相碳酸盐的硼同位素是目前恢复古海洋pH的有效途径，倍受古气候—环境学家的重视。评述了近年来海洋碳酸盐的硼同位素的最新研究成果和研究现状，重点探讨了海相碳酸盐的硼同位素的测定方法、硼同位素—pH模型和古海水pH恢复等前沿内容，旨在提供一个系统的海洋碳酸盐硼同位素—pH系统的基本概念及研究思路，以利于气候学、地质学界了解这一交叉领域的发展动态。     

Determination of carbon fractionation factor between aqueous carbonate and CO2(g) in two-direction isotope equilibration

The experiments were conducted in the open CO₂ system to find out the equilibrium fractionation between the carbonate ion and CO₂(g). The existence of isotopic equilibrium was checked using the two-direction approach by passing the CO₂−N₂ gases with different δ¹³C compositions (− 1.5‰ and − 23‰) through the carbonate solution with δ¹³C = − 4.2‰. The Δ_{CO3T²⁻−CO2(g)} equilibrium fractionation is given as 6.03 ± 0.17‰ at 25 °C. Discussion is provided about the significance of carbonate complexing in determination of Δ_{CO3T²⁻−CO2(g)} and Δ_{HCO3T⁻−CO2(g)} fractionations. Finally, an isotope numerical model of flow and kinetics of hydration and dehydroxylation is built to predict the isotopic behaviour of the system with time.     

磷石膏碳酸化固定二氧化碳的实验研究

基于"以废治废"的理念,通过湿式碳酸化法对磷石膏固定CO₂的反应温度、时间、液固比和氮硫比对固碳率的影响进行了研究。采用XRD和SEM-EDS对磷石膏原料和碳酸化产物的物相组成、显微形貌等进行了分析与表征。结果表明: 磷石膏中的石膏在碳酸化过程中全部转化为方解石,而硬石膏由于溶解度小仅有部分转化为方解石,石英对于碳酸化反应是惰性的。优化的碳酸化工艺条件为: 反应温度为65℃,碳酸化时间为60 min,液固比为3.0,氮硫比为2.25,固碳率达到95.24%。实验结果对固碳减排和磷石膏的进一步资源化利用具有一定的实际意义。     

二氧化钛表面键合配位体固相萃取填料的制备及其吸附性能研究

有机配位体/无机纳米复合材料作为固相萃取填料用于重金属离子分离富集是当前分析化学研究的热点课题。本文将含有N、S配位原子的氨基硫脲通过缩合反应接枝于纳米二氧化钛表面,制备了一种新型纳米Ti O2/TSC复合固相萃取填料。通过红外光谱、X射线衍射、X射线光电子能谱和扫描电镜表征,此填料与共混法制备的聚合物包覆纳米二氧化钛复合填料相比,二氧化钛粒子(尺寸200~300 nm)分布更均匀,结构更稳定。用该填料制备的固相萃取小柱静态吸附Sb3+、Cd2+和Ba2+在30℃时饱和吸附量分别为13.9mg/g、12.9 mg/g和11.2 mg/g,在优化的实验条件下三种金属离子的吸附回收率分别达到97.94%、95.65%和94.04%,实验数据重现性高(RSD5.5%),吸附性能优于聚苯乙烯-甲基丙烯醛-氨基硫脲包覆纳米二氧化钛和纳米二氧化钛两种填料。本填料结合ICP-MS测定水样中以上三种离子的检出限分别为0.061μg/L、0.013μg/L和0.075μg/L。