Arsenic content and groundwater geochemistry of the San Antonio-El Triunfo, Carrizal and Los Planes aquifers in southernmost Baja California, Mexico

 The San Antonio-El Triunfo mining district, located at a mountainous region 45 km south-east of La Paz, Baja California, has been worked since the late 1700s. Mine waste material produced during 200 years of mineral extraction area poses a risk of local groundwater pollution and eventually, regional pollution to the Carrizal (west basin) and the Los Planes (east basin) aquifers. There are different types of deposits in the mining area. These are dominated by epithermal veins, in which arsenopyrite is an important component. Carrillo and Drever (1998a) concluded that, even though the amount of mine waste is relatively small in comparison to the large scale area, significant As in groundwater derived from the mine waste piles is found locally in the groundwater. This paper shows the results of geochemical analyses of groundwater samples from the San Antonio-El Triunfo area and the Carrizal and Los Planes aquifers during several years of monitoring (1993–1997). The highest values of total dissolved solids (TDS) and As are in the mineralized area where the mining operations occurred (∼1500 ppm TDS and 0.41 ppm As). The lowest concentrations of TDS and As are, in general, away from the mineralized area (∼500 ppm TDS and 0.01 ppm As). Sulfate and bicarbonate (alkalinity) are, in general, high near the mineralized area and low away from it. The arsenic concentrations vary seasonally, especially after the heavy summer thunderstorms. Geochemical modeling (MINTEQA2 and NETPATH) and analysis of the regional geochemical evolution of the groundwater from the mining area towards the aquifer of Los Planes shows that the most likely hydrochemical processes include: dilution, precipitation of calcite, and adsorption of As onto surfaces of iron oxyhydroxides (ferrihydrite). These processes act as natural controls to the extent and amount of As pollution in the Carrizal and Los Planes aquifers. Received: 4 May 1999 · Accepted: 22 February 2000     

Toxic metal contamination in the lateral lakes of the Coeur d'Alene River valley, Idaho

 The 11 lateral lakes of Coeur d'Alene River valley in northern Idaho have received heavy metal contamination from over a century of upstream mining. The lateral lakes lie within the flood plain of the Coeur d'Alene River, and in their bottom sediments is preserved a stratigraphic record of the upstream mining operations. To characterize the contaminated sediments in the lateral lakes, sampling techniques, including the Livingston piston corer and the Huttenen freeze box, have been developed by Quaternary geologists to preserve the vertical stratigraphy in the samples. From 26 cm to over 55 cm of undisturbed tailing sediments, commonly with “varve-like” features, have been found in each of the lateral lakes, with maximum concentrations by weight of lead at 3.8%, zinc at 3.4%, arsenic at 340 mg/kg, cadmium at 120 mg/kg and mercury at 7 mg/kg. The contamination in the lakes appears to be restricted to the shallow subsurface and heavy metal concentrations generally drop to background levels within a meter of depth. Received: 22 May 1998 · Accepted: 21 September 1998     

九江市城市垃圾卫生填埋场场址适宜性评价优选

利用层次分析法对九江市5个候选垃圾场地进行了适宜性评价优选,通过场地评价影响因子定权重和采用多目标线性加权函数数学模型计算各候选场址的综合评价得分,结果依次为场地5>场地1>场地2>场地3>场地4。可见场地5为5个候选场地中最佳适宜性垃圾填埋场场址,在很大程度上减少了选址过程中人为主观因素影响和定性分析过多的缺点,为九江市重建垃圾填埋场地选址提供了客观依据。     

Geotechnical Engineering Issues in Ocean Waste Disposal: A Review

Marine pollution has received considerable attention during the past few years as the news media has focused on such topics as contaminated seafoods, algae blooms, fish and mammal kills, and dirty beaches. The source of these pollution problems are many and include: sewage outfalls, industrial discharges, storm runoff from agricultural lands and metropolitan areas, waste sludges, dredge materials, and highly concentrated chemical and radioactive wastes. Although the United Nations has banned marine dumping, there is still the problem of legacy wastes and low level discharges into the coastal zone. Disposal of these wastes in the marine environment typically involves either: their placement directly on or within the seabed or dilution in the water column. If wastes are diluted in the water column, they have the potential to be adsorbed onto the surface of sediment particles which are settling to the seabed. As particles settle through the water column they are subjected to extensive dispersal and may eventually be injested by bottom-feeding organisms or bio-accumulation by plankton and, thus, enter the food chain. Geotechnical engineers working as members of multidisciplinary teams apply quantitative knowledge about the behavior and physical performance of earth materials toward designing systems for disposing of these wastes in the oceans and aid in monitoring waste disposal sites. In dredged material disposal geotechnical engineers assist in selecting disposal equipment, predict stable characteristics of dredged material mounds, design mound caps, and predict erodibility of the material. With sewage outfalls, geotechnical engineers design foundation and anchor elements, estimate scour potential around the outfalls, and determine the stability of deposits made up of discharged materials. Geotechnical engineers also consider the influence that pollutants have on the engineering behavior of marine sediment and the extent to which changes in behavior affect the performance of structures founded on the sediment. In each of these roles, careful application of geotechnical engineering principles can contribute toward more efficient and environmentally safe disposal operations.     

Fecundity of the snapper Chrysophrys auratus (Pisces: Sparidae) from the Hauraki Gulf

Fecundity estimates were made for snapper Chrysophrys auratus, a serial spawning fish, for the 1974–75 and 1975–76 spawning seasons. Weighed sub‐samples of ovaries were used, and eggs were counted manually. All eggs >0.1 mm diameter were considered potentially capable of being spawned; estimates of these eggs were made at the beginning and end of spawning, and their difference was considered to be the actual fecundity. A log‐log transformation of egg numbers against length offish gave a linear relationship. Fecundity estimates ranged from 297 000 at 25 cm to 4 528 000 at 50 cm in 1974–75, and from 83 000 at 25 cm to 6 164 000 at 50 cm in 1975–76. Counts of ripe eggs were also made, and batch sizes ranging from 13 000 at 25 cm to 104 000 at 50 cm were predicted. By combining these data with fecundity estimates the number of batches spawned was estimated to be 23–44 in 1974–75, depending on and increasing with length; and 6–59 in 1975–76.     

钻探工程废弃钻井液处理技术及进展

介绍了国内外废钻井液处理方法的发展现状,研究了废弃钻井液对环境的危害和影响,阐述了坑内填埋、固液分离法、固化处理、循环使用以及几种特殊的钻井液处理技术。在此基础上,提出了一些建议,如开发新型环保钻井液和钻井液添加剂;加强固控,减少废钻井液的排放;综合开发利用如微生物法等新技术等,为其他类似区域钻井工程的环境保护提供参考。     

Spatial distribution and source of heavy metals in reclaimed lands of Homebush Bay: The venue of the 2000 Olympic Games,Sydney, New South Wales

A large part of the Sydney 2000 Olympic Site at Homebush Bay was reclaimed over several decades using an estimated 9 Mt of domestic, commercial and industrial waste. Past activities, such as reclamation of wetlands, land clearing, shoreline remodelling and industrial practices, have caused an adverse environmental impact on the Homebush Bay site. Core samples (n = 4513) collected from the reclaimed lands of Homebush Bay show that, prior to remediation, soil contaminated by heavy metals (Cr, Cu, Pb, Zn) may have posed a threat to groundwater in the area. Mean Pb concentrations from the three land types at the Olympic site range from 65 to 374 μg/g in reclaimed areas, 78–167 μg/g in landfill areas and 44–52 μg/g in non‐infilled areas, respectively. Heavy‐metal concentrations in soils from non‐infilled areas indicate that these parts of the site were uncontaminated. The distribution of heavy metals in soil samples revealed a close association between elevated concentrations and the presence of fill materials at the site. Metal concentrations were frequently above Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The Olympic Coordination Authority's remediation strategy to clean up the Homebush Bay site included consolidating contaminated waste into landscaped hills, which were capped with impermeable clay and thermal destruction of scheduled waste on site. The primary aims of the current study were to provide a scientific foundation for the remediation/rehabilitation of natural systems, and to make a contribution to the Olympic Coordination Authority's Development Plan and Environmental Management System for the site.     

纳米ZnO-La_2O_3固体碱的制备及其催化废弃煎炸油制备生物柴油

本文采用共沉淀法,以草酸铵为沉淀剂制备了ZnO-La2O3固体碱,并将其应用于催化废弃煎炸油与甲醇的酯交换反应制备生物柴油,通过X射线衍射(XRD)、电感耦合等离子体原子发射光谱(ICP-AES)以及扫描电子显微镜(SEM)对催化剂的组成和形貌进行表征。结果表明:700℃煅烧制备的催化剂具有较好的催化活性,催化剂是由ZnO和La2O3组成,锌镧摩尔比为3∶1,粒径在100nm左右。该催化剂用量5%(为油的质量)、醇油摩尔比36∶1、200℃反应3h,得到的脂肪酸甲酯(FAME)产率达到91.6%;催化剂经过洗涤和干燥,无需活化可继续使用,连续使用第四次后,脂肪酸甲酯的产率仍保持在80%以上。     

GLOBAL sensitivity analysis,GIS and multi‐criteria evaluation for a sustainable planning of a hazardous waste disposal site in Spain

A novel application of Sensitivity Analysis is presented. Useful applications of Global SA (GSA) already exist in the field of numerical modelling. In this paper, we explore the joint use of GSA, Geographical Information Systems (GIS) and Multi‐Criteria Evaluation. In this preliminary case study, 11 factors have been used to find the best place to locate a hazardous waste landfill. Two variance‐based methods (Sobol' and E‐FAST) are used to compute sensitivity indices in order to identify the factors that determine the variance of the model output. The results show that only three factors jointly account for 97% of the output variance. This information is employed to make a simplification of the original model, retaining only these three influential factors. In addition, if the SA is carried out in a pilot area where the spatial properties are similar to those of the whole region, we can infer the results to the whole area. This procedure achieves the goal of the study with an optimized allocation of resources for GIS data acquisition.