Pressure-assisted chelation extraction of lead from contaminated soil

Soil contamination by metallic elements including lead occurs frequently. Contaminant metals in soil pose a serious risk to public health and groundwater supplies. Extraction using chelants is seen as a remediation option; however, it is often hampered by access to the contaminants that are shielded by the soil matrix. We have developed a novel extraction technique that utilizes a mildly elevated pressure in consecutive cycles of compression and decompression along with a chelating agent for the soil slurry. Complete extraction of 3300 mg/kg of Pb from soil was achieved by 100 mM of EDTA (ethylenediaminetetraacetic acid) in 10 min using 20 pressure cycles at 150 psi (10 atm). Extraction was studied according to pressure, number of pressure cycles, chelant concentration, solid content, pH, agitation, and use of consecutive washings. Heightened extraction is attributed to fracturing of the soil particles that leads to enhanced contaminant exposure to the chelating agent.     

Metal prices and the business cycle

Metal price fluctuations have recently been of interest not only because of their cyclical volatility but also of their interaction with business cycles. A related issue is whether metal prices move together sufficiently to collectively reflect macroeconomic influences. Correlation or the tendency for prices to move together has been termed “comovement”, where the commonality in prices reflects the tendency of commodity markets to respond to common business cycle and trend factors. Metal prices are known to respond to macroeconomic influences and the latter might well explain the common factor which causes them to move together. Our goal is to provide an estimate of the common factor in metal prices and to relate this factor to important macroeconomic influences. The prices we study are for aluminum, copper, tin, lead and zinc; the macroeconomic variables include industrial production, consumer prices, interest rates, stock prices, and exchange rates. Our results confirm that the common factor in metal prices can be related to such macroeconomic influences.     

Evaluation method of automobile recycling systems for Asia considering international material cycles: application to Japan and Thailand

To examine an appropriate recycling system for end-of-life vehicles (ELVs) from Japan in the context of Asia, an Asian international automobile recycling input-output (AI-ARIO) analysis is presented. The AI-ARIO analysis spatially expands the existing ARIO analysis within the framework of the waste input-output (WIO) analysis developed by Nakamura et al., which considers the interdependence between the flow of goods and wastes in a country. This analysis focuses on the local and global cycles for ELVs in Asia and can evaluate the environmental and economic effects of alternative recycling systems. We estimated the AI-ARIO table for Japan and Thailand and applied it to scenario analyses covering the restriction of ELV trade between the two countries, the introduction of new recycling techniques in Thailand, and centralized treatment in Japan. We verified the applicability and effectiveness of the AI-ARIO analysis through the scenario analyses.     

几个影响室内土动力试验的重要试验参数

室内土动力试验是研究土动力特性的重要方法之一,其结果受到很多试验参数的影响,其中加载频率、应变速率(加载速率)、加载类型和循环次数是4个重要的试验参数,也是目前国内外的研究热点。总结了国内外关于这4个试验参数对土动力特性影响的研究成果,经过比较分析后认为对于应变速率(加载速率)、加载类型以及循环次数对土动力特性的影响,研究者的认识基本一致,但对有关加载频率对土动力特性的影响却尚持不同的观点。     

A geostatistical approach for mapping thematic classification accuracy and evaluating the impact of inaccurate spatial data on ecological model predictions

Spatial information in the form of geographical information system coverages and remotely sensed imagery is increasingly used in ecological modeling. Examples include maps of land cover type from which ecologically relevant properties, such as biomass or leaf area index, are derived. Spatial information, however, is not error-free: acquisition and processing errors, as well as the complexity of the physical processes involved, make remotely sensed data imperfect measurements of ecological attributes. It is therefore important to first assess the accuracy of the spatial information being used and then evaluate the impact of such inaccurate information on ecological model predictions. In this paper, the role of geostatistics for mapping thematic classification accuracy through integration of abundant image-derived (soft) and sparse higher accuracy (hard) class labels is presented. Such assessment leads to local indices of map quality, which can be used for guiding additional ground surveys. Stochastic simulation is proposed for generating multiple alternative realizations (maps) of the spatial distribution of the higher accuracy class labels over the study area. All simulated realizations are consistent with the available pieces of information (hard and soft labels) up to their validated level of accuracy. The simulated alternative class label representations can be used for assessing joint spatial accuracy, i.e., classification accuracy regarding entire spatial features read from the thematic map. Such realizations can also serve as input parameters to spatially explicit ecological models; the resulting distribution of ecological responses provides a model of uncertainty regarding the ecological model prediction. A case study illustrates the generation of alternative land cover maps for a Landsat Thematic Mapper (TM) subscene, and the subsequent construction of local map quality indices. Simulated land cover maps are then input into a biogeochemical model for assessing uncertainty regarding net primary production (NPP).     

On the transmission of the effects of monetary policy to the regions

In the paper the theoretical framework is that of credit rationing theory, the regional differences being examined in terms of both financial markets and the real economy. Empirically the focus is upon regional trends in market conditions and the timelags experienced in the effects of monetary policies in two different regions. The period of time examined is from 1970 to 1978, the changes in the marginal interest on central bank credit issued to the commercial banks being taken as the indicator of monetary policy and data on employment opportunities vacant in the regions as representing market conditions and the delay‐effects of monetary policy. The methods used are those of cross‐correlation analysis.     

Physical,Chemical and Microbiological Water Quality of the Manyas Lake,Turkey

Manyas, also known as the Bird Paradise Lake, is situated near the south-eastern coasts of the Marmara Sea in Turkey. This shallow lake, is a unique natural reserve providing habitat for migratory birds with its rich fauna and plankton species. The objective of this work is to study the ecological and water quality changes resulting from increasing anthropogenic pollution and human intervention on the natural variations of the water level. For this purpose, physical, chemical and microbiological aspects of the aquatic ecosystem in the lake of Manyas are being measured semimonthly since more than a year. After the completion of field measurements associations between different parameters will be searched by means of a water quality model. Results obtained will be used in the sustainable restoration of the lake. In this paper, firstly the nutrient and trophic dynamics of the planktonic ecosystem are associated with the bio-geochemical water cycle in the lake. Secondly, space and time distributions of all physical, chemical and microbiological data are presented and interactions between the nutrient availability and some microscopic communities are discussed.     

干湿循环与垃圾渗滤液耦合作用下GCL防渗性能

开展膨胀指数和渗透系数测定试验,研究干湿循环与垃圾渗滤液渗透耦合作用下膨润土的膨胀性能和土工合成黏土衬垫（GCL）防渗性能变化规律.结果表明,干湿循环与垃圾渗滤液渗透耦合作用对膨润土的膨胀性能和GCL的防渗性能具有显著负面影响：在7次干湿循环后,垃圾渗滤液饱和的膨润土的膨胀指数从20mL/2g降低至7.5mL/2g,GCL的渗透系数从1.65×10^-11m/s增加到1.89×10^-7m/s.膨胀指数下降和渗透系数升高的根本原因是膨润土渗透膨胀性能的丧失.单纯的垃圾渗滤液渗透不会改变GCL的渗透系数.将有效应力从20kPa升高至150kPa,可以促使GCL的渗透系数降低4个数量级,满足填埋场防渗要求（< 5.0x10^-11m/s）.     

水稻土中铁-氮循环耦合体系影响镉活性机理研究

关于铁-氮循环耦合体系对镉(Cd)活性影响的研究目前尚鲜见报道.本文采用淹水培养试验,研究不同硝酸根(NO_3~-)、铵根(NH_4~+)处理条件下,南方典型Cd污染水稻土中铁氧化还原与氮形态转化耦合关系及其对Cd活性影响的机理.结果表明:随着培养时间延长,不同处理的pH值逐渐向7.0靠拢,Eh值由273~321 mV持续下降至118~132 mV,pe+pH值(e-活度的负对数值与H+活度的负对数值之和)从10.62~11.19持续下降至8.55~8.83,土-水体系处于中度还原条件;化学反硝化(Chemodenitrification)和NO_3~-依赖的厌氧铁氧化过程(Microbial NO_3~--dependent FeIIoxidation,NDFO)生成无定形氢氧化铁(Fe(OH)_3(amorp)),其对Cd~(2+)专性吸附及与Cd~(2+)共沉淀降低了有效态Cd浓度,加之pH值上升增大Cd~(2+)在土壤固相表面的吸附量,导致水稻土中Cd活性下降;NH_4~+被Fe(OH)_3(amorp)厌氧氧化(Anaerobic NH_4~+oxidation coupled to FeIII reduction,Feammox)会消耗H+而提高体系的pH值,在一定程度上会降低Cd活性,但其自身与Cd~(2+)对土壤固相表面吸附位点的竞争,可能会更大程度地减少Cd~(2+)在土壤固相表面的吸附量,而导致Cd活性提高.本研究成果可为丰富和拓展水稻土中Cd的生物地球化学理论,并为南方Cd污染农田修复及治理提供科学依据.     

Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model

Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO₂ concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century.