老挝万象盆地钾盐矿床成盐晚期沉积环境: 来自硼酸盐矿物的证据

老挝万象盆地蕴含着丰富的钾资源,是研究古蒸发岩和古海水形成演化的热点地区之一.老挝万象盆地含盐建造包含3个蒸发岩?碎屑岩沉积韵律,而钾镁盐矿赋存在下盐段顶部.通过对老挝通芒钾盐矿区钾镁盐矿层的硼酸盐矿物的提取,发现在成钾晚期硼酸盐矿物有方硼石单晶和鲕粒方硼石两种形式.钻孔中方硼石单晶含量较少,而鲕粒方硼石分布较多且基本...     

磷石膏制备硫酸钙晶须的结晶行为

以磷石膏为原料制备硫酸钙晶须,从固液比、溶剂浓度、溶解温度以及降温速率对晶须影响的4个方面研究了晶须的结晶行为。对磷石膏和晶须进行了分析测试;利用显微观察及图像分析,讨论了实验条件对晶须长度、长径比和晶须形貌的影响;结合结晶学原理讨论了晶须的结晶行为。结果表明,随固液比的增大,晶须长度和长径比先降后升;随溶剂浓度的增大,晶须的长度和长径比上升;随溶解温度的增大和降温速率的增加,晶须的长度和长径比下降。所制备的晶须平均长度为200~400μm,平均长径比为25~30。晶须长度和长径比的变化能够反映晶须形貌的变化。晶须的结晶分为晶核的形成和晶须的生长两个阶段,实验条件通过影响晶核形成的速率、过饱和度以及磷石膏的溶解量对晶须的结晶行为产生影响。     

Spectral response of different eroded soils in subtropical china: A case study in Changting County,China

Hyper-spectral data is widely used to determine soil properties. However, few studies have explored the soil spectral characteristics as response to soil erosion. This study analysed the spectral response of different eroded soils in subtropical China, and then identify the spectral characteristics and soil properties that better discriminate softs with different erosion degrees. Two methods were compared： direct identification by inherent spectral characteristics and indirect identification by predictions of critical soft properties. Results showed that the spectral curves for different degrees of erosion were similar in morphology, while overall reflectance and characteristics of specific absorption peaks were different. When the first method is applied, some differences among different eroded groups were found by integration of associated indicators. However, the index of such indicators showed apparent mixing and crossover among different groups, which reduced the accuracy of identification. For the second method, the correlation between critical soil properties, such as soil organic matter （SOM）, iron and aluminium oxides and reflectance spectra, was analysed. The correlation coefficients for the moderate eroded group were primarily between -0.3 to -0.5, which were worse than the other twogroups. However, the maximum value of R2 was obtained as 0.86 and 0.94 for the non-apparent eroded and the severe group. Furthermore, these two groups also showed some differences in the spectral response of iron complex state （Fep）, Aluminium amorphous state （Alo） and the modelling results for soil organic matter （SOM）. The study proved that it is feasible to identify different degrees of soil erosion by hyperspectral data, and that indirect identification by modelling critical soil properties and reflectance spectra is much better than direct identification. These results indicate that hyper-spectral data may represent a promising tool in monitoring and modelling soil erosion.     

Zooplankton response to long-term liming: Comparison of 15 limed and 15 reference lakes in Sweden

Taxonomic composition and variation in density of zooplankton were studied since 1989 to investigate possible long-term effects of anthropogenic acidification and liming in Sweden (the Integrated Studies of the Effects of Liming in Acidified Water (ISELAW) programme). In the programme, 15 long-term (18-31 years) limed lakes were studied in parallel with 8 untreated circumneutral lakes (representing target conditions) and 7 acid lakes. Five-year means from these lakes were used to evaluate differences between the three lake groups. Water chemistry (including trace metals), phytoplankton, invertebrate predators and fish were also monitored. Older records from 8 of the limed lakes obtained during the acid period preceding the initial liming were compared with records from the limed period. The number of taxa more than doubled in 6 lakes after liming. Total present-day zooplankton biovolume showed insignificant differences between the neutral and limed groups, i.e., conformed with the target conditions. Trace metals, including inorganic aluminium, appeared in low concentrations in limed and neutral lakes whereas zooplankton in one acid lake was Al-intoxicated. Daphnid populations in 4 other lakes may suffer from effects of high Cd or Cu concentrations. “Bottom-up” regulation of the zooplankton biovolumes was indicated by positive regressions between total phosphorus-phytoplankton and phytoplankton-zooplankton. Corresponding tests showed no “top-down” regulation of zooplankton by fish and of phytoplankton by zooplankton. Biomasses of planktivorous fish were higher in the neutral reference lakes than in both the acid and the limed lake groups, but neither zooplankton density and biovolume nor mean body size were lower in the neutral references. A higher production and turnover of zooplankton in neutral reference lakes may explain similar densities and structure of zooplankton in spite of a heavier predation pressure.     

Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 1. The tropical diatom Nitzschia closterium

Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species’ upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32 °C); and (iii) the effects of wastewater (at 27 and 32 °C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7 °C and 33.1 °C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC₅₀s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000) μg L⁻¹, respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC₅₀s > 100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species.     

From surface acidity to surface reactivity; inhibition of oxide dissolution

Paul Schindler's early work on the acid-base chemistry of oxides was instrumental for the development of the concept of surface complexation. This approach has not only been important in establishing a theory on the adsorption of metal ions and ligands as a function of pH and solution variables, but has become essential in establishing surface speciation (coordinative structural and electronic arrangement at the solidwater interface) which in turn determines surface reactivity. The factors that affect dissolution of Fe(III) (hydr)oxides and inhibition of dissolution are discussed. A few examples for the inhibition of reductive and ligand-promoted dissolution by binuclear complexes of oxoanions (phosphate, borate) and of protonpromoted dissolution by Cr(III) are given.     

硼矿床含硼地层的二元结构模式

通过对与沉积作用有关的硼矿床结构的研究表明，含硼地层都具有二元结构，即下部是富含硼的凝灰岩、安山岩或酸性岩，是成矿的物质基础；其上是弱盐化－强盐化环境下形成的含硼矿层的蒸发岩沉积，蒸发岩环境是成矿的必要条件。二元结构的含硼地层的形成与裂谷构造、板块俯冲带和碰撞带的发生、发展、演化紧密相关。硼矿床含硼地层二元结构模式的提出，将硼矿床成矿机制进一步深化，具有理论意义和指导找矿的实际意义     

湖南七里坪－半边街镁质矽卡岩硼矿床微量元素地球化学

湖南七里坪－半边街接触交代型硼矿，矿体产于中石炭统壶天群白云岩与燕山期花岗岩接触带的矽卡岩中，产状受岩体顶板形态的控制，多为似层状、透镜状、囊状等。一般离岩体较远的部位硼矿石的品位较富，但靠近岩体的部位矿体较厚大。据微量元素相关系数聚类谱系图分析，Ｂ元素在岩体中呈分散状态，在高温热液中易于聚集，在矽卡岩中富集成矿，在蚀变的白云岩中有轻微的富集。     

Detecting a field gradient of PAH exposure in decapod crustacea using a novel urinary biomarker

Norwegian coastal waters are subject to PAH contamination from electrochemical industries such as aluminium smelters. Evidence of PAH exposure has been established in fish and bivalves. The present study tests the applicability of a novel crustacean PAH exposure biomarker to a PAH contamination gradient in the field (Karmsund Strait, SW Norway). Fluorescence analysis of urine samples collected from crabs at each site revealed 1-OH pyrene "equivalent" levels (indicative of pyrogenic PAH contamination) decreased with increasing distance from a point source of pyrogenic PAH (a large aluminium works). The assay was shown to be suitable for the detection of PAH exposure in wild crustacean populations, for discriminating between contaminated and clean sites and is also sufficiently sensitive to detect gradients of PAH contamination. The method provides a rapid, inexpensive and non-destructive measure of biologically available PAH in crustaceans.     

Mobilization of aluminium in the wathering profiles of the African surface in Malawi

Leaching of aluminium from the weathering profile of the African surface in Malawi was deduced from the chemistry of a vadose profile. Its loss occurs where congruent kaolinite dissolution results in saprolite collapse, leaving a weakly lateritized, sandy residual mantle. This leaching is a contemporary process, as shown by the precipitation of aluminosilicate evaporites in the dambos (seasonally waterlogged bottomlands). This paper presents the results of determinations, by ICP-OES and AAS-graphite furnace, of aluminium levels in groundwaters, examining the effects of a variety of pretreatments. Filtration (0.45 μm) substantially reduces the levels of total aluminium, showing it to be in particulate form. Subsequent acidification causes precipitation of < 0.45 μm forms of aluminium, further reducing the apparent levels to below ICP-OES detection limit. This is consistent with mobilization in organically bound forms which are destabilized at low pH, and accords with earlier work which showed that indigenous micro-organisms can cause dissolution of kaolinite. Organically bound mobilization provides an explanation for aluminium leaching at near-neutral pH in conjunction with the presence of silica in solution. The identification of this mechanism of kaolinite dissolution and aluminium evacuation from vadose profiles provides a realistic process for the levelling of extensive planation surfaces; the contingent collapse of the kaolinized saprolite would lower the interfluves, progressively narrowing the vadose zone until the landsurface approaches the planar form of the stable, regional water-table.