Minerals in East-West trade: An overview

This paper examines recent trends in East-West trade in general. During the later 1960s and early 1970s trade between East and West grew faster than world trade. But after 1976 this growth slowed as trade between Eastern Europe and the West collapsed, although the USSR continued to trade with the West. It is shown that the second oil price rise in 1979 produced enhanced terms of trade for the USSR. The major products traded between East and West are identified and it is noted that the future direction of East-West trade will be profoundly influenced by whether or not the USSR undertakes significant economic reform.     

Patterns in natural resource policy: The US experience

Institutional arrangements (formal governmental policies) are the key to many resource problems. However, few efforts have been made to explain changes in natural resource policy over time. This paper traces the changing pattern in US resource policy during the 20th century. Trends in natural resource institutions since 1900 are divided into three distinct periods. Each period is characterized in terms of the criteria used to evaluate policy, the management tools used to implement policy, the role of government in resource policy, and distributional issues of the day. The paper ends with speculation about the source of fundamental changes in resource policy and the role of economists in the policy-making process.     

Landfill leachate treatment methods: A review

Landfilling of municipal waste is still a major issue of the waste management system in Europe. The generated leachate must be appropriately treated before being discharged into the environment. Technologies meant for leachate treatment can be classified as follows (i) biological methods, (ii) chemical and physical methods. Here we review briefly the main processes currently used for the landfill leachates treatments.     

趋磁细菌的分子生物学研究进展

趋磁细菌菌体内含有磁小体,能够沿地球磁力线方向定位、运动.趋磁细菌和磁小体的研究具有重要的理论意义和应用价值.本文对趋磁细菌及其胞内产物磁小体作了介绍,论述了该领域分子生物学方面的研究进展,包括与磁小体相关的基因和蛋白的研究、趋磁细菌遗传体系及基因组方面的研究等,展望了该领域今后的发展前景.图3表1参35     

Degradation of three phenylurea herbicides (chlortoluron, isoproturon and diuron) by micromycetes isolated from soil

As part of a study conducted on the fate of xenobiotics in the environment, a selection of 100 strains of micromycetes (Ascomycetes, Basidiomycetes and Yeasts) have been cultivated in liquid synthetic medium with 3 phenylurea herbicides: chlortoluron and isoproturon (100mg L-1) and diuron (20mg L-1). While 17 strains depleted isoproturon over 50% only 4 depleted diuron and 2 chlortoluron at the same level. The best results were obtained with Bjerkandera adusta and Oxysporus sp which were the most efficient towards the 3 substrates. After 2 weeks Bjerkandera adusta depleted chlortoluron 98%, diuron 92% and isoproturon 88%.     

Liquid chromatography study of pyrene degradation by two micromycetes in a freshwater sediment.

Pyrene biodegradation in a freshwater sediment without fungi supply, or inoculated with two sediment micromycetes, Mucor racemosus var. sphaerosporus and Phialophora alba was studied after 0, 5, 13, 28, 60 and 90 days. The influence of glucose addition was estimated, and a liquid chromatographic method for simultaneous quantitative determination of residual anthracene, fluoranthene and pyrene in the sediment was developed. Samples with PAHs were extracted in Soxhlet with ethyl acetate, and LC analysis was performed on a 5 microm Supelcosil column (150 x 4.6 mm I.D.) with gradient elution (2 ml min(-1)) of acetonitrile-water and UV detection at 254 nm. Recoveries of anthracene, fluoranthene and pyrene were 90.3%+/-1.1%, 93.2%+/-0.9% and 90.42%+/-1.9%, respectively, without interference. The native sediment microorganisms (with or without glucose added) have shown 35% pyrene degradation and sediment with glucose inoculated by the strains revealed 40%.     

Chlorination of bisphenol A: kinetics and by-products formation

The kinetics of initial chlorination of bisphenol A (BPA) was studied between pH 2 and 11 at room temperature (20 +/- 2 degrees C). pH Profile of the apparent second-order rate constant of the reaction of BPA with chlorine were modeled considering the elementary reactions of HOCl with BPA species and an acid-catalyzed reaction. The predominant reactions at near neutral pH were the reactions of HOCl with the two phenolate species of BPA (k = 3.10 x 10(4) M(-1)s(-1) for BPA- and 6.62 x 10(4) M(-1) s(-1) for BPA(2-)). At near neutral pH, half-life times of BPA were calculated to be less than 1.5 h for chlorine residual higher than 0.2 mg l(-1). Chlorination of synthetic treated waters spiked with BPA showed that BPA disappeared within 4 h and that chlorinated bisphenol A congeners were rapidly formed and remained in solution for up to 10-20 h when low chlorine dosages are applied (0.5-1 mg l(-1)). To limit their presence in drinking water networks, it is then necessary to maintain high chlorine residuals that rapidly produce and decompose chlorinated bisphenol A congeners.     

Seasonal and monthly variations of columnar aerosol optical properties over east Asia determined from multi-year MODIS,LIDAR, and AERONET Sun/sky radiometer measurements

Multi-year records of MODIS, micro-pulse lidar (MPL), and aerosol robotic network (AERONET) Sun/sky radiometer measurements were analyzed to investigate the seasonal, monthly and geographical variations of columnar aerosol optical properties over east Asia. Similar features of monthly and seasonal variations were found among the measurements, though the observational methodology and periods are not coincident. Seasonal and monthly cycles of MODIS-derived aerosol optical depth (AOD) over east Asia showed a maximum in spring and a minimum in autumn and winter. Aerosol vertical extinction profiles measured by MPL also showed elevated aerosol loads in the middle troposphere during the spring season. Seasonal and spatial distributions were related to the dust and anthropogenic emissions in spring, but modified by precipitation in July–August and regional atmospheric dispersion in September–February. All of the AERONET Sun/sky radiometers utilized in this study showed the same seasonal and monthly variations of MODIS-derived AOD. Interestingly, we found a peak of monthly mean AOD over industrialized coastal regions of China and the Yellow Sea, the Korean Peninsula, and Japan, in June from both MODIS and AERONET Sun/sky radiometer measurements. Especially, the maximum monthly mean AOD in June is more evident at the AERONET urban sites (Beijing and Gwangju). This AOD June maximum is attributable to the relative contribution of various processes such as stagnant synoptic meteorological patterns, secondary aerosol formation, hygroscopic growth of hydrophilic aerosols due to enhanced relative humidity, and smoke aerosols by regional biomass burning.     

Effects of sewage sludge amendments on pesticide sorption and leaching through undisturbed Mediterranean soils

The Gharb region in Morocco is an important agricultural zone where soils receive pesticide treatments and organic amendments to increase yields. The groundwater aquifer in the Gharb region is relatively shallow and thus vulnerable. The objective of this work was to study the influence of organic amendments on diuron, cyhalofop-butyl and procymidone leaching through undisturbed soil columns. Two soils were sampled from the Gharb region, a Dehs (sandy soil) and a R’mel (loamy clay soil). Following elution (124.5 mm), the amount of pesticide residues in the leachates of the sandy soil (0.06–0.21 %) was lower than in those of the loamy clay soil (0.20–0.36 %), which was probably due to preferential flow through the loamy clay soil. The amount of procymidone leached through the amended soil columns was greater than the control for the sandy soil only. The organic amendments did not significantly influence diuron and cyhalofop-butyl leaching in either of the soils. The application of organic amendments affected the amounts of dissolved organic matter (DOM) eluted and thus pesticide leaching as a function of soil-type. Nevertheless, in some case, the formation of pesticide-DOM complexes appeared to promote pesticide leaching, thus increasing groundwater contamination risks.     

Organochlorinated contaminants in decapod crustaceans from the coasts of Brittany and Normandy (France)

The contamination and distribution of organochlorinated compounds were considered in three crustacean species (edible crab, Cancer pagurus; spider crab, Maja brachydactyla; velvet swimming crab, Necora puber) from five sites along the coasts of Brittany and Normandy (Western and North-Western France). PCBs (16 single congeners), pp'-DDE and HCB were measured in hepatopancreas, gonads and muscle: in all, 175 samples were analysed. The spider crab was the only species found in the five sampling sites, thus enabling comparison between areas. Specimens from Antifer were much more contaminated (summation operator 16 PCBs in hepatopancreas=2000-4000 ng g(-1) dry weight) than those from other sites (50-1000 ng g(-1) d.w.). Among all the three species, the spider crab appeared more contaminated by PCBs than the edible crab, by a factor 2-3, probably in relation with specific differences in their life cycle. There was no difference due to the gender of the species. Within the different analysed tissues, contamination levels increased from muscle to gonads and hepatopancreas in relation with the fat content. A very similar PCB composition was observed in all samples, PCB fingerprints being characterised by the relative importance of the more persistent PCB congeners: CB153, 138, 180, 187, and 118. Finally, these results were compared to recent food regulations first of maximum marker PCB intake and secondly of maximum dioxin-like PCB intake. By considering the muscle, all samples were far below the regulatory limits; for hepatopancreas and gonads, however, some samples were unfit for human consumption.