Aqueous pyrite oxidation by dissolved oxygen and by ferric iron

Rates of aqueous, abiotic pyrite oxidation were measured in oxygen-saturated and anaerobic Fe(III)-saturated solutions with initial pH from 2 to 9. These studies included analyses of sulfite, thiosulfate, polythionates and sulfate and procedures for cleaning oxidation products from pyrite surfaces were evaluated. Pyrite oxidation in oxygen-saturated solutions produced (1) rates that were only slightly dependent on initial pH, (2) linear increases in sulfoxy anions and (3) thiosulfate and polythionates at pH > 3.9. Intermediate sulfoxy anions were observed only at high stirring rates. In anaerobic Fe(III)-saturated solutions, no intermediates were observed except traces of sulfite at pH 9. The faster rate of oxidation in Fe(III)-saturated solutions supports a reaction mechanism in which Fe(III) is the direct oxidant of pyrite in both aerobic and anaerobic systems. The proposal of this mechanism is also supported by theoretical considerations regarding the low probability of a direct reaction between paramagnetic molecular oxygen and diamagnetic pyrite. Results from a study of sphalerite oxidation support the hypothesis that thiosulfate is a key intermediate in sulfate production, regardless of the bonding structure of the sulfide mineral.     

Control of disinfection by products formation potential by enhanced coagulation

Jar-test experiments were conducted to study enhanced coagulation effectiveness in removal of disinfection by products (DBPs) from Zayandehrud River at Isfahan Province-the center part of Iran-in 2004. In this study, the removal of suspended and colloidal particles and natural organic matter (NOM) at various coagulant doses and coagulation pHs was assessed through raw and treated water measurements of turbidity, UV₂₅₄ absorbance, TOC, and dissolved organic carbon (DOC). The trihalomethane formation potential (THMFP) was also determined by a mathematical relationship with TOC. Results indicated that NOM removal was a function of coagulant type, coagulant dose, and pH of coagulation. In general, TOC, DOC, and UV₂₅₄ absorbance removal enhanced with increasing coagulant dose. However, further increases in coagulant dosage had little effect on disinfection by-products precursors removal. Ferric chloride was consistently more effective than alum in removing NOM. Coagulation pH was appeared to be a determining factor for maximum NOM removal and the removal of DBPs precursors by enhanced coagulation was significantly enhanced at pH 5.5 in comparison with initial pH of water. Furthermore, it is specified that preadjustment of pH with sulfuric acid reduced the coagulant dosage and thus, production of sludge. The reduction in THMFP was consistent with the trends observed for DBPs precursors removal data (i.e. UV₂₅₄ and TOC data).     

ZJB(BP)-30A型变频调速高压注浆泵的研制

介绍ZJB（BP）－30A型变频调速高压注浆泵的设计思路、研制过程以及其主要技术参数和性能特点。     

用FPAS分析气势--以琼东南盆地为例

地层流体受两大流体系统的控制：压实流和重力流。利用流体势分析系统(简称FPAS)研究地下流体势及压力分布可克服井资料不系统的局限性，有效地进行油气资源的预测评价。由于琼东南盆地地质务件极其复杂，海洋油气勘探程度很低，勘探成本高，石油地质研究水平也比较低，分析认为区内有巨大的油气资源前景，但油气运移方向和路程均不清楚。用地下流体力场和势分析的方法可以统一处理和定量解释油气的运移和聚集规律，明确预测油气运移的主通道，确定有利的油气勘探靶区，显著提高钻探成功率。综合本区剖面、平面流体势及压力特征，结合其他有关地质资料，找出最有利的勘探目的层位。该方法在琼东南盆地松东地区的应用，取得了良好的效果。     

明沟排水与竖井排灌

本文在分析干旱细土平原区水文地质条件的基础上 ,论述了盐渍化地区在不同排水条件下水中盐份的运移和积聚的过程 ,比较了明沟排水和竖井排灌的优劣 ,从而提出竖井排灌是改良土壤盐渍化 ,防止土壤返盐的有效措施     

Annual stream flow simulation by ARMA processes and prediction by Kalman filter

Algeria is a semi-arid country where water resources are not sufficient to cope with the important socio-economic development demands. Any sustainable development strategy is basically dependent on a rigorous management of water resources potential, which presents a true challenge to be tackled for such countries. Classic mathematical models based on time invariability and ignorance of the stochastic and non-linear nature of hydrological variables are not sufficient for simulation and prediction studies. The present study subscribes to the stochastic hydrological processes modeling and prediction in case of time-varying linear systems through adaptive Kalman filter (KF) methodology. It focuses upon stream flows as a water resources component, which is directly related to the socio-economic development meanwhile it opts for Kalman filter as principal tool of work. The main objective is the application of (KF) technique to model and predict annual streamflow volumes in Northern Algeria and the obtained results are satisfactory.     

Nitrate sorption by organosmectites

The use of organoclays as adsorbents in the remediation of polluted water has been the subject of many recent studies. In this present work, a Tunisian smectite modified by two cationic surfactants was used as a sorbent for the investigation of the adsorption kinetics, isotherms and thermodynamic parameters of nitrate ions at various contact time, initial concentrations and temperatures. Two simplified kinetic models, first-order and second-order, were used to predict the adsorption constants. It was found that the adsorption kinetics of nitrate was best described by the second-order model. Adsorption isotherms and equilibrium adsorption capacities were determined by the fittings of the experimental data to two well-known isotherm models including Langmuir and Freundlich. The results showed that Langmuir model appears to fit the adsorption better than Freundlich model. The equilibrium constants were used to calculate thermodynamic parameters, such as the change of free energy, enthalpy and entropy.     

Hydrocarbons occluded by asphaltenes

Homologous series of n-alkenes and dimethylalkanes with the odd or even number of carbon atoms in the molecule have been identified in chloroform extracts from the organic matter of Upper Paleozoic deposits of the Vilyui syneclise penetrated by the superdeep well SV-27 at depths below 5 km. It is presumed that these unusual hydrocarbons resulted from the destruction of asphaltene occlusions under severe P-T conditions at great depths and that the hydrocarbon generation began in the zone of postdiagenetic transformations of sediments. This hypothesis was tested in the sections of deposits whose organic matter underwent catagenesis of different grades. On the basis of these results, zones of emergence, transition, and destruction of occlusions have been recognized.     

War,by Conservation

In this paper I argue that there has been a critical shift towards war by conservation in which conservation, security and counter insurgency (COIN) are becoming more closely integrated. In this new phase concerns about global security constitute important underlying drivers, while biodiversity conservation is of secondary importance. This is a significant break from earlier phases of fortress conservation and war for biodiversity. In order to develop a better understanding of these shifts, this paper analyzes the existing conceptual approaches, notably environmental security which seeks to understand how resources cause or shape conflict, and political ecology approaches that focus on the struggles over access to and control over resources. However, this paper indicates the limitations of these existing debates for understanding recent shifts, which require a fresh approach. I chart the rise of the narrative I call poachers-as-terrorists, which relies on the invocation of the idea that ivory is the white gold of Jihad, a phrase which is closely associated with an Elephant Action League (EAL) report in 2012 which claimed Al Shabaab used ivory to fund its operations. This narrative is being extended and deepened by a powerful alliance of states, conservation NGOs, Private Military Companies and international organizations, such that it is shaping policies, especially in areas of US geo-strategic interest in Sub-Saharan Africa. As a result conservation is becoming a core element of a global security project, with significant implications for conceptual debates and for conservation practice on the ground.