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.     

Isolated sulfite oxidase deficiency: mutation analysis and DNA-based prenatal diagnosis

Isolated sulfite oxidase deficiency is an autosomal recessive, neurological disorder resulting from a defect in SUOX, the gene encoding the enzyme that catalyzes the terminal reaction in the sulfur amino acid degradation pathway. In its classical, severe form, sulfite oxidase deficiency leads to intractable seizures, severe and progressive brain pathology and death at an early age. We report here on clinical features and mutational analysis of the genetic defect in a newborn with sulfite oxidase deficiency. Cultured fibroblasts from this patient exhibited no detectable sulfite oxidase activity, and a unique four base pair deletion was present in the cDNA isolated from the same source. Identification of the same genetic defect in a heterozygous state in each of the parents and the monitoring of subsequent pregnancies in this family by DNA-based prenatal diagnosis are also described. The deletion mutation was identified in a homozygous state in uncultured chorionic villus tissue from the second pregnancy that was subsequently terminated. In the third pregnancy, the presence of sulfite oxidase activity and identification of the mutation in a heterozygous state suggested that the fetus was not affected. This pregnancy resulted in the birth of a normal child. Copyright © 2002 John Wiley & Sons, Ltd.     

Relationships Between Macroinvertebrate Assemblages of Stony Littoral Habitats and Water Chemistry Variables Indicative of Acid-stress

Gradient analyses were used to correlatively determine the importance of acid-related variables for littoral macroinvertebrate assemblages. To better ascertain the effects of acidity on macroinvertebrate assemblages we removed sites judged to be affected by other stressors such as agriculture, urbanization and liming. PCA of land use and water chemistry confirmed the presence of an acidity gradient; several acidity variables (e.g. pH and buffering capacity) were strongly correlated with the first PC axis, which explained Ca 32% of the variance in the environmental data. Partial constrained ordination of littoral macroinvertebrate assemblages with water chemistry, after removing the effect of other confounding variables (e.g. land use/type), showed that acidity variables accounted for significant amounts of among-lake variability in assemblage structure. Regression of canonical scores (a metric of community composition) and diversity with pH and alkalinity was used to visually determine ecological breakpoints or threshold values. Five classes were established for pH: pH?<?5 (extremely acid), 5?<?pH?≤?5.6 (very acid), 5.6?<?pH?≤?6.2 (acid), 6.2?<?pH?≤?6.8 (weakly acid) and pH?>?6.8 (neutral-alkaline). Similarly, three classes were determined for alkalinity/acidity: <0.02, 0.02–0.1 and >0.1 meq/L.     

Mode of reproduction,recruitment, and genetic subdivision in the brooding sponge<Emphasis Type="Italic"> Haliclona</Emphasis> sp.

Sponges display a variety of reproductive strategies that have the potential to influence population genetic structure. Histological examination of ten reproductive individuals of the Western Australian sponge Haliclona sp. showed that this species broods embryonic larvae that are potentially limited in dispersal capabilities. Because sponges have the potential to propagate in a number of modes, allozyme electrophoresis was used to assess the relative importance of asexual and sexual reproduction to recruitment, and to quantify genetic subdivision over different spatial scales. Tissue samples from 227 sponges were collected from reefs within two areas 400 km apart: Hamelin Bay and Rottnest Island. Contrary to expectations for highly clonal populations, genotypic diversity within sites was high, no linkage disequilibrium was found, and there was no evidence of genotypic clustering within reefs. There was no genetic evidence that asexual reproduction is important for the maintenance of populations. Genetic comparisons were consistent with mixing of sexually produced recruits within reefs, on a scale up to a few hundred metres, but significant genetic subdivision between reefs (F_ST=0.069 at Hamelin Bay, 0.130 at Rottnest Island) indicated that water gaps of several hundred metres are effective at preventing dispersal. Subdivision between the two areas, separated by 400 km, was moderately greater (F_ST=0.142) than within, but the same alleles were predominant in the two areas. These genetic patterns are consistent with limited dispersal capabilities of brooded larvae.Communicated by G.F. Humphrey, Sydney     

DEVELOPMENT OF NUTRIENT SUBMODULES FOR USE IN THE GRIDDED SURFACE SUBSURFACE HYDROLOGIC ANALYSIS (GSSHA) DISTRIBUTED WATERSHED MODEL1

Abstract: A primary water quality problem caused by non-point source pollution (NPSP) is eutrophication, from excess nutrients in receiving water bodies. The control of nutrients arising from NPSP is difficult because the source areas can be hard to identify and typical treatment methods are infeasible due to the distributed nature of the pollutants. It may be possible to reduce nutrient related water quality problems through the restoration of highly disturbed watersheds with best management practices (BMPs). While restoration attempts may provide significant returns, they can be costly to implement and often are met with resistance in agricultural communities. Extending model results beyond the range of calibration to model future conditions such as for restoration scenarios requires the use of physically-based models that include the important processes that generate streamflow and material transport, uptake, loss, transformation, and recycling of nutrients and other material. The research and development objectives of the US. Army Engineer Research and Development Center (ERDC) in Vicksburg, Mississippi, are to develop a watershed assessment and management model to simulate transport, uptake, loss, transformation, and recycling of nutrients such as nitrogen and phosphorus and associated material such as sediment and organic matter. In this study we will discuss current efforts at the ERDC's Environmental Laboratory to develop a state-of-the-art watershed water quality model.     

Studies on the reproductive cycles of the calcareous sponges Clathrina coriacea and C. blanca

The reproductive cycles of two closely related calcareous sponges, Clathrina coriacea (Montagu, 1818) and C. blanca (Miklucho-Maclay, 1868), were studied to determine whether they were reproductively isolated. Populations of both species were sampled at Santa Catalina Island, California, USA, for 2.5 years. The reproductive period is from July to October in C. coriacea, and from April to August in C. blanca. Seawater temperature and habitat influence reproduction in both species. Fragmentation occurs in C. coriacea in the summer, while asexual reproduction by means of budding is seen in C. blanca throughout the year. The results of the study confirm that the two sponges are separate species.     

Polychlorinated chemical residues in fish from major watersheds near the Great Lakes, 1979

Over 50 non-PCB polyhalogenated organic chemicals have been identified by GC/MS in fish from the Great Lakes and other major watersheds near the Great Lakes. p,p′-DDE, hexachlorobenzene, and components of tech-chlordane were the most frequently found chemicals. Also described are advances in sample preparation methodology which allow the identification of many frequently occuring unusual chemicals. Several chemicals not previously reported in environmental samples are identified.     

Establishing an effective production sharing type regime for petroleum

The primary reason for developing a nation's petroleum resources for export is to generate government revenues. The goal of most governments is to maximize the net present value of their petroleum revenues subject to efficient exploration and production practices and depletion considerations. This paper seeks to provide a basis for the determination of an effective tax regime that will achieve this goal. The analysis focuses on 12 standard production sharing contract options applied to four hypothetical exploration environments. A relatively recent Resource Rent Tax option is also examined as an add-on to production sharing contracts or other tax regimes. The results highlight the need for governments to understand and to use: (1) appropriate profit criteria, (2) an understanding of multi-national petroleum corporation behaviour, and (3) a priori geologic information in establishing effective tax regimes for petroleum.