Coupled study of water-stable isotopes and anions in porewater for characterizing aqueous transport through the Mesozoic sedimentary series in the eastern Paris Basin

This study presents data on chloride and bromide concentrations in porewater, water and anion diffusion coefficients, and their accessible porosities based on radial diffusion experiments on rock samples collected from a 2000 m-deep borehole (EST433) drilled by Andra in the eastern Paris Basin. The distributions of water stable isotope and chloride concentrations in porewater along this column reveal transient flows of water and solutes between the aquitard layers and the surrounding aquifers. These distributions confirm the occurrence of two separate aquitard/aquifer systems: “Oxfordian/Callovo–Oxfordian/Dogger” and “Dogger/Liassic/Rhaetian”. This separation is confirmed by Cl⁻/Br⁻ ratios, which are low in Liassic and Dogger porewater, suggesting the influence of primary brines, and which are close to the marine ratio in the Dogger groundwater. Based on these results, transport simulations in the two systems were carried out according to different scenarios. The simulation results confirm that transport properties obtained in the laboratory at sample scale may be extrapolated to the formation scale. It is highly probable that diffusion is the main transport process in the Callovo–Oxfordian formation. This may also be the case in the Dogger/Liassic layer, although a limited contribution from advection cannot be totally excluded. By testing different scenarios of boundary conditions in diffusive models, it is proposed that the Dogger aquifer was first activated in the Early Miocene.     

A comparison of non-linear least square and GLUE for model calibration and uncertainty estimation for pesticide transport in soils

The problems of calibrating soil hydraulic and transport parameters are well documented, particularly when data are limited. Programs such as CXTFIT, UUCODE and PEST, based on well established principles of statistical inference, will often provide good fits to limited observations giving the impression that a useful model of a particular soil system has been obtained. This may be the case, but such an approach may grossly underestimate the uncertainties associated with future predictions of the system and resulting dependent variables. In this paper, this is illustrated by an application of CXTFIT within the generalised likelihood uncertainty estimation (GLUE) approach to model calibration which is based on a quite different philosophy. CXTFIT gives very good fits to the observed breakthrough curves for several different model formulations, resulting in very small parameter uncertainty estimates. The application of GLUE, however, shows that much wider ranges of parameter values can provide acceptable fits to the data. The wider range of potential outcomes should be more robust in model prediction, especially when used to constrain field scale models.     

水中溴化物的测定方法改进

介绍了酚红分光光度法测定水中溴化物的改进方法。通过调整氧化剂的浓度使反应速度加快,在可接受的时间内测定显色反应产生的最大吸光度,使其在不同的显色环境温度下都能得到最大的灵敏度。显色温度、反应时间、氧化剂氯胺T的浓度是影响显色反应的主要因素。通过实验条件对比,建立了一种可在不同季节都能采用的检测方法。     

Analysis of bromate and bromide in drinking water by ion chromatography-inductively coupled plasma mass spectrometry

A method for the detection of bromate and bromide in drinking water by ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) was developed. The optimized conditions of IC including pH and concentration of the effluent were studied. The results showed that the above two species of bromine were baseline separated within nine minutes under the optimized conditions. The detection limits (S/N=3) of bromate and bromide were 0.23 and 0.12 μg/L, respectively. The RSD (n=6) of the peak areas was 1.2%-3.5%. The method has been successfully applied to the determination of the type bromide in drinking water samples. The recoveries were 95%-109%. The method can be used for the regular analysis of bromate and bromide in real drinking water samples.     

Bromine and stable isotopic profiles of formation waters from potash mine-shafts, Saskatchewan, Canada

Sixty-five inflow samples from access shafts were collected at three separate potash mines in order to construct three 1000 m deep hydrochemical profiles. Bromine concentrations, and δD and δ¹⁸O stable isotopic compositions, increase with depth in each case. Measured isotopic ratios have not changed in 15+ years since the mine-inflows were first sampled, implying little change in the hydraulic regimes at the mines over time. However, the bromine concentrations are typically a factor of five lower than previously reported. Newer analytical techniques have improved the accuracy, precision and resolution of the hydrochemical profiles. Results indicate that the salinity of the inflow waters originated as mixtures of evaporatively concentrated seawater, meteoric water, and brine derived from halite dissolution. Extremely concentrated brines (TDS > 525 g/L) were found at the Cory and Allan potash mines some 55 km apart, but their role in the paleohydrogeology of the basin remains uncertain.     

钾盐矿床中Br的地球化学特征及研究进展

本文概述了Br的地球化学行为及其在钾盐矿床中的应用,重点论述了Br的分配系数和热力学模型的新发展。指出近年来用海相蒸发岩盐中的溴来评价显生宙海水组分变化行为,对于重新认识贫硫酸盐型的钾盐矿床有十分重要的意义。由于大洋中脊热液流体组分改变和海底扩张作用,使古海水组分发生变化,这种作用比碳酸盐白云石化或硫酸镁缺损使古海水组分发生变化更为重要。指出研究老挝贫硫酸盐型钾盐矿床对在我国兰坪一思茅盆地寻找钾盐矿床有重要的指导意义。