The contemporary Asian silver cycle: 1-year stocks and flows

The stocks and flows of silver throughout the Asian economy for 1997 have been quantified, with major flows examined over their entire life cycle, including mining, production, fabrication, and manufacture, product use, and waste management. By compiling the findings of 11 country-level material flow analyses, a regional analysis was created. The reliability and availability of the data varied, with the most confidence given to the earlier life stages and the most uncertainty existing later. Overall, Asia is a net importer of silver, requiring nearly 7000 Mg of silver in 1997. Approximately 2200 Mg Ag are mined, and production waste totals about 640 Mg Ag. The flow of silver into use equals 9900 Mg Ag, with a considerable build-up of 7100 Mg Ag entering in-use stock. Silver waste sent directly to the environment, in addition to landfilled waste, totals 1600 Mg Ag. Much variation exists when examining country-level silver flows on a per capita basis. India and Thailand’s fondness for silver jewelry greatly increases their silver flows into use and in-use stock. Japan’s high overall consumption reflects its high GDP per capita. Regionally, a significant potential exists to tap the silver contained in the in-use stocks and to enhance the recycling rates.     

Anwendung differenzierter Untersuchungsmethoden zur Sedimentbewertung

The aquatic sediments have special significance as habitats of species-rich biocoenoses and as the place where manifold transformation processes occur. Because of their high potential for accumulation of contaminants, sediments are particularly sensitive to anthropogenic impacts, which may disturb the natural state of sediments. In order to protect the aquatic life community, such impacts must be identified, assessed, and the chemical causes of toxic effects must be found. Since the end of the 1980s, the interest for a possibly comprehensive assessment of sediments has increased. This problem can be tackled only by an integrated approach, which combines the detection of toxicity under standardized laboratory conditions with chemical data and biologicalin situ studies into a holistic view. The information value of the results depends essentially on the selection of a diversity of test methods, which are able to indicate contaminant effects differentially. This paper presents results from a comprehensive test approach, which integrates standardized methods (DIN) with pore waters and eluates, as well as tests using the whole sediment. To cover a wider variety of contaminants in the sediment, solvent extracts and fractions thereof were also examined by different bioassays. Chemical analyses examined the structural parameters and identified priority contaminants. Non-target screening could detect a variety of further substances and substance classes. The model organisms of the bioassays responded very differentially and sometimes very intensively to the contaminants in the various investigation media. Especially in sediment extracts, some fractions, and consequently also substances and groups of substances, proved to be particularly toxic. It could be shown that the selected chemical, ecotoxicological, and biological study methods contribute to a holistic assessment. Further, possibly very sensitive bioassays and benthos-biological parameters should be examined aiming to optimize the very wide battery of tests.     

HYDROLOGIC DATA ACQUISITION AM) THE INSTRLMENTATION GAP1

Any scheme for developing our water resources must eventually focus on the hydrologic theme for answers to pressing questions about anticipated availability of water. These answers will only be as realistic as the data is reliable, inferring accuracy as well as sufficiency. To that effect, more hydrologic and meteorologic data collection stations must be added to the existing network throughout the country, and the basic instrumentation presently in use should be made more versatile, but without an accompanying near-astronomical increase in cost and in complexity. The ubiquitous so-called current meters are a case in point. Current meters have almost certainly received more man-hours of use in the field of Water Resources than any other instrument ever devised to measure stream velocity. In spite of more esoteric equipment appearing on the specialized market each year, the time-honored method of stream gaging by the velocity-area method is still widely practiced, and the basic instrument remains the current meter. The same persistent use is essentially true for the anemometer, or “wind current meter.” Over the past 30 years, a great many studies have been made to define operational parameters, particularly with respect to the statistics of data reliability. Today's needs are different from those acceptable a few years back, yet in many instances yesterday's instrument can be metamorphosed to satisfy present practice. Besides a discussion of some of the fundamental problems of data collection which must be accounted for in all areas of water resources where water and air currents must be known in space and in time, the authors present a brief critique of several new hybrid types of current meters. Two of these meters were designed especially to fill the gap between sophisticated and specialized equipment of high cost, and relatively inexpensive simpler devices lacking however the advantages of automation and self-recording features. Since the mechanical performance of current meters has been the subject of many past studies fully reported in various professional journals, it appeared advantageous to develop electronic refinements on such a type of widely used instrument. A period of research, first at Washington State University and presently at Clarkson College of Technology, produced two electronic packages applicable to current meters. The rationale of these studies was to increase the usefulness of current meters by providing velocity readout, either instantaneous or time-averaged; to include data recording on tape if and when such would be desired, together with the necessary playback facility; and to keep the electronic system independent of the current meter size. The paper describes in some detail the photo-electronic tachometer which seems to offer more reliability and flexibility of operation than induction-type transducers. One of the features most worthy of consideration is the adaptability of such device to any size of current meter frame and vanes. The rotation of an impeller one-half inch in diameter is recorded by the instrument as faithfully as that of one six inches in diameter. Where velocity transients are to be observed, the advantages of a greatly reduced inertia are evident. The inherent ruggedness of low current drain transistors and integrated circuits should make this light-actuated meter readout device well-suited for remote applications.     

Formation and control of nitrogenous DBPs from Western Australian source waters: Investigating the impacts of high nitrogen and bromide concentrations

We studied the formation of four nitrogenous DBPs(N-DBPs) classes(haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines), as well as trihalomethanes and total organic halogen(TOX), after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection.     

Ecosystem Service Restoration after 10 Years of Rewetting Peatlands in NE Germany

The restoration of ecosystem services, i.e., production, regulation, and information, is a global challenge, which the federal state of Mecklenburg-Vorpommern in NE Germany addressed in 2000 by rewetting over 20,000 ha of degraded peatlands within the Mire Restoration Program. We evaluated ecosystem services in 23 rewetted sites by assessing the following mire parameters within a ten year period: (a) dominant vegetation at the ecosystem level, (b) peat formation potential at the landscape level, and (c) aboveground biomass and nutrient levels. Seven to 10 years after rewetting, the wetlands formed a mosaic of vegetation types with the highest potential for peat formation and several dominant, peat-forming species accumulated high levels of aboveground biomass and nutrients (C, N, P). Common reed (Phragmites australis) accumulated the most biomass (up to 24 t dry matter/ha), and N+P during the growing season. A future management option is to annually harvest aquatic and wetland plants to reduce nutrient levels in restored mire ecosystems.     

Listening to local voices: Tuvaluans respond to climate change

Climate change has become a permanent feature on the global media scene and in the decision-making of policy makers. The voices of academics, scientists, politicians and commentators dominate the climate change debate, yet local knowledges and beliefs, local realities, as well as local voices and actions are essential elements of navigating the way forward. Drawing on Paton's postgraduate research, this paper broadens the current dialogue by providing a platform for grassroots Tuvaluan voices to enter the climate change debate. It explores their local realities, knowledges and beliefs, and captures what Tuvaluans hold dear – factors which must play a central role in decision-making processes. To ensure the local population is fully mobilised, it will be argued that processes for engaging local voices must build on existing forums for engagement.     

The composition and biosynthesis of lipids in Thysanoessa raschi from the Clyde Estuary,Scotland

The lipid composition and biosynthesising activity of Thysanoessa raschi collected from the Clyde Estuary, Scotland, in May 1981 were examined. Triacylglycerols were the major lipid class present, although 16.7% of the total lipid were wax esters in which phytol was the dominant fatty alcohol. The thoracic contents (hepatopancreas) of the krill were capable of biosynthesising lipids in vitro from various labelled substrates. Radioactivity from [1-¹⁴C] palmitic acid was incorporated into lipids in the order phospholipids>triacylglycerols>wax esters; the bulk of the radioactivity was present in all cases in the fatty acyl moieties of the lipids. [U-¹⁴C] glucose labelled lipids in the order phospholipids>triacylglycerols>free fatty acids> was esters; in the first two lipids the radioactivity was mainly in the glycerol moieties, whereas in was esters it was solely in the fatty acyl moieties. The extent of labelling of these lipids from [U-¹⁴C] alanine was less than that from [U-¹⁴C] glucose, but the pattern of labelling was generally similar. More than 90% of the radioactivity incorporated into total lipid from ³H₂O was present in free fatty acids from which it was calculated that the hepatopancreas of T. raschi can synthesise 2.5 g of fatty acid per hour at 15°C. This value is approximately three times lower than that previously determined for T. inermis from Balsfjorden, northern Norway. The results are discussed in terms of the sources of the dietary lipids of krill and the role of endogenous biosynthesis in contributing to its lipid reserves.     

A spatiotemporal analysis of cattle herd movement in relation to drinking-water sources: implications for Cryptosporidium control in rural Kenya

Environmental Science and Pollution Research - Given the increasing evidence that domestic contact with livestock is a risk factor for child diarrhoea in low- and middle-income countries, there...     

Chemical Stability of Capped Dredged Material Disposal Mounds in Long Island Sound,Usa

Geochemical analysis and visual inspection of cores collected from capped dredged material mounds revealed that in many cores, cap material was clearly distinguishable, both visually and chemically, from mound material. Contaminated dredged sediments were disposed in Long Island Sound eleven and seven years prior to sampling, and capped with uncontaminated dredged sediments. Core data provided no conclusive evidence of physical disturbance of, or chemical migration from, the contaminated mound sediments. Obvious chemical gradients of contaminant concentrations, which we propose are indicators of chemical migration, were not detected in the cores. Heterogeneity of the cap and mound sediments in some cores made the interface less distinct. We postulate that the preservation of spatial variability of sediment texture and associated contaminants observed within dredged material mounds is a result of the dredging process. Preservation of the textural and contaminant history of dredged sediments within finegrained cohesive cap materials provides evidence of the absence of physical or chemical disturbance.