Comparison of three sequential extraction procedures for partitioning of heavy metals in car park dusts

The aim of this study was to elucidate the amount of metal released at each step by using different extractants in three sequential extraction schemes for the partitioning of metal contents of car park deposited dust samples. For this purpose, three different sequential extraction procedures (SEP) were employed for the metal fractionation in car park dust samples collected from the campus of Erciyes University, Kayseri, Turkey. While two of the sequential extraction procedures contain five steps the other, namely the BCR sequential extraction scheme, has three steps. The first two methods fractionate metals to be exchangeable, bound to carbonates, bound to Mn oxides, bound to Fe oxides and bound to organic matter, and the BCR protocol fractionates the metals as acid soluble and exchangeable, reducible, and oxidisable. Determination of the metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn was performed by flame atomic absorption spectrometry (FAAS). The results obtained by the three methods were compared and showed that the amount of metal released at each step of the leaching procedure depended both on the type of reagents used and the sequence in which they were applied. The most mobile elements were Cd, Pb and Zn which are metals potentially toxic to the environment and are also known to originate from traffic. The calculated enrichment factors for Cd and Pb were substantially high (73.5-187 and 18.4-27.5, respectively) and somewhat lower for Zn (5.1-6.8). These results confirm that they are important metal pollutants for car parks. Detection limits and recoveries were found in the range of 0.01-1.39 microg ml(-1) and 68-126%, respectively, for the metals studied and the three sequential extraction procedures.     

四川黄河流域区生态环境现状、问题及对策

本文根据2001年现场考察与研究获得的信息，结合前人研究的资料，论述了四川黄河流域区生态环境恶化、沼泽退化的状况，其主要表现为：湖沼萎缩，沼泽旱化，沼泽逆向生态演替，区域土地沙化，土壤质量下降，野生动物种类、种群数量减少，草场退化和鼠害猖獗。分析了区域生态环境退化与人类活动干扰、自然因素作用的关系，提出四川黄河流域区生态环境保护的对策与措施。     

垫江土地资源可持续利用研究

通过对垫江县目前土地资源利用特点，存在问题及其原因的详细分析，结合垫法实际，提出了垫江县土地资源可持续利用分区的设想，针对各区不同的土地利用特点，提出了土地持续利用方向及主要措施。     

Building disaster-resilient communities: The road to the second World Conference on Disaster Reduction, January 2005, Kobe, Hyogo, Japan

The statistics paint a shocking picture: Over the past ten years around 7,000 ‘natural’ disasters have occurred, killing more than 300,000 people and resulting in over US$800 billion in economic losses (Munich Re, 2003). Increasing interest in global warming has provoked intense debate on the issue of climate change and its implications for more frequent and intense extreme weather events, placing more people at risk than ever. While all countries may be threatened by natural hazards, experience shows that developing countries are disproportionately affected, with losses sometimes exceeding years of hard‐won and desperately needed economic development. The World Conference on Disaster Reduction,1 to be held in Japan in 2005, aims to address these and other crucial issues that are posing an unprecedented challenge to the international community.     

A NEW METHOD FOR ESTIMATING FUTURE RESERVOIR STORAGE CAPACITIES1

ABSTRACT: A new method has been developed for estimating future reservoir storage capacities, allowing for sediment deposition and compaction. Reservoir sedimentation surveys for 117 reservoirs, conducted by the Illinois State Water Survey over the past 60 years, were used to determine regional constants K to represent the severity of sediment deposition in the reservoirs. More than half of the 82 water supply reservoirs investigated had records of reservoir sedimentation surveys, and their K values were calculated by using data from those sediment surveys. The average K values of the remaining non-surveyed water supply reservoirs were estimated from the regional distribution of the K values. Other important factors considered in the estimation of future reservoir storage capacities are the trap efficiency of the reservoirs and the variation of density of sediment deposits due to compaction. The model can also be used for analyzing the economics of alternative sites and of design features that can be incorporated in dams for reducing reservoir sedimentation.     

Enhancing Hyrdological Simulation Program – FORTRAN Model Channel Hydraulic Representation1

Abstract: The hydrological simulation program – FORTRAN (HSPF) is a comprehensive watershed model that employs depth‐area‐volume‐flow relationships known as the hydraulic function table (FTABLE) to represent the hydraulic characteristics of stream channel cross‐sections and reservoirs. An accurate FTABLE determination for a stream cross‐section site requires an accurate determination of mean flow depth, mean flow width, roughness coefficient, longitudinal bed slope, and length of stream reach. A method that uses regional regression equations to estimate mean flow depth, mean flow width, and roughness coefficient is presented herein. FTABLES generated by the proposed method (Alternative Method) and FTABLES generated by Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) were compared. As a result, the Alternative Method was judged to be an enhancement over the BASINS method. First, the Alternative Method employs a spatially variable roughness coefficient, whereas BASINS employs an arbitrarily selected spatially uniform roughness coefficient. Second, the Alternative Method uses mean flow width and mean flow depth estimated from regional regression equations whereas BASINS uses mean flow width and depth extracted from the National Hydrography Dataset (NHD). Third, the Alternative Method offers an option to use separate roughness coefficients for the in‐channel and floodplain sections of compound channels. Fourth, the Alternative Method has higher resolution in the sense that area, volume, and flow data are calculated at smaller depth intervals than the BASINS method. To test whether the Alternative Method enhances channel hydraulic representation over the BASINS method, comparisons of observed and simulated streamflow, flow velocity, and suspended sediment were made for four test watersheds. These comparisons revealed that the method used to estimate the FTABLE has little influence on hydrologic calibration, but greatly influences hydraulic and suspended sediment calibration. The hydrologic calibration results showed that observed versus simulated daily streamflow comparisons had Nash‐Sutcliffe efficiencies ranging from 0.50 to 0.61 and monthly comparisons had efficiencies ranging from 0.61 to 0.84. Comparisons of observed and simulated suspended sediments concentrations had model efficiencies ranging from 0.48 to 0.56 for the daily, and 0.28 to 0.70 for the monthly comparisons. The overall results of the hydrological, hydraulic, and suspended sediment concentration comparisons show that the Alternative Method yielded a relatively more accurate FTABLE than the BASINS method. This study concludes that hydraulic calibration enhances suspended sediment simulation performance, but even greater improvement in suspended sediment calibration can be achieved when hydrological simulation performance is improved. Any improvements in hydrological simulation performance are subject to improvements in the temporal and spatial representation of the precipitation data.     

Influence of Fibers on the Mechanical Properties of Cassava Starch Foams

The utilization of renewable resources in packaging can provide solutions to ecological problems such as waste quantity. Agricultural resources are alternative raw materials, among which there is starch, a natural polysaccharide that can be used to form resistant foam under wet and warm conditions. The starch foam is obtained by thermo pressing process where cassava starch, water and additives are processed to form a rigid structure by swelling, gelatinization and network formation. Natural fibers can be used to improve the mechanical properties of starch foams. In this project was investigated the influence of the addition of fibers in the levels of 1, 2 and 3% of cassava (short fiber) and 1, 2 and 3% of wheat fiber (powered fiber) in the starch dough. The foams were characterized by physical methods of strength, flexibility, density and by Scanning Electron Microscopy (SEM). The increase in fibers quantity has resulted in foams with higher density and less flexibility, whatever the fiber type. Most fibers quantity did not improve the foam strength. Foam made with 1% of cassava fiber showed higher compression strength; by increasing the percentage quantity there was a decrease on the compression resistance. Foam made with wheat fiber presented a lower result in 2%. The fiber type had no statistical significance in strength, flexibility and density foam. Only the fiber quantity was significant. The results showed that both fibers presented limited dimensions to improve the reinforcement of the starch foams up to 1%.     

A Mediation Case for Resolving the Energy and Environment Dispute at Aliağa-İzmir, Turkey

A mediation exercise to resolve the ongoing dispute against these power plant projects at Aliağa was recommended and participated in by the author in 1997. In this article the basis of the continuing environmental concern about the feared impacts of the new power plants, procedure, and results of this mediation are mentioned. The basis of the “energy versus environment” dispute in Aliağa are introduced. Mediation exercise and its end results have been criticized.     

Yeasts as a model for assessing the toxicity of the fungicides Penconazol, Cymoxanil and Dichlofluanid

In the present work the sensitivity of yeast strains of Kluyveromyces marxianus, Pichia anomala, Candida utilis, Schizosaccharomyces pombe and Saccharomyces cerevisiae, to the fungicides cymoxanil, penconazol, and dichlofluanid, was evaluated. Dichlofluanid induced the most negative effects, whereas penconazol in general was not very toxic. Overall, our results show that the parameters IC50 for specific respiration rates of C. utilis and S. cerevisiae and C(D) for cell viability of S. cerevisiae can be applied to quantify the toxicity level of the above compounds in yeast. Hence, could be explored as an alternative or at least as a complementary test in toxicity studies and, therefore, its potential for inclusion in a tier testing toxicity test battery merits further research.     

Mercury in sediments and vegetation in a moderately contaminated salt marsh (Tagus Estuary, Portugal)

Depth variations of total mercury (Hg) and methylmercury (MeHg) concentrations were studied in cores from non-colonized sediments, sediments colonized by Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima and belowground biomass, in a moderately contaminated salt marsh (Tagus Estuary, Portugal). Concentrations in belowground biomass exceeded up to 3 (Hg) and 15 (MeHg) times the levels in sediments, and up to 198 (Hg) and 308 (MeHg) times those found in aboveground parts. Methylmercury in colonized sediments reached 3% of the total Hg, 50 times above the maximum values found in non-colonized sediments. The absence of correlations between total Hg concentrations in sediments and the corresponding MeHg levels suggested that methylation was only dependent on the environmental and microbiological factors. The analysis of belowground biomass at high-depth resolution (2 cm) provided evidence that Hg and MeHg were actively absorbed from sediments, with higher enrichment factors at layers where higher microbial activity was probably occurring. The results obtained in this study indicated that the biotransformation of Hg to the toxic MeHg could increase the toxicity of plant-colonized sediments.