Evidence of degradation of polybrominated biphenyls in soil samples from Michigan

Soil samples obtained from the former polybrominated biphenyls (PBB) manufacturing site in Michigan were analyzed by gas chromatography and gas chromatography with mass spectrometric detection. The results indicate significant degradation of the PBB residue in the soil sample. The soil sample with the highest concentration of PBB had the greatest degree of degradation. Principal degradation products include 2,3', 4,4', 5-pentabromobiphenyl, 2,2', 4,4', 5-pentabromobiphenyl and two unidentified tetrabromobiphenyls. The degradation pattern observed supports a photochemical decomposition mechanism. These degraded residues may be more toxic than the original Firemaster residues. The implications of the results are discussed.     

Use of earth observation satellite data for land degradation mapping and monitoring in Mediterranean ecosystems: Towards a satellite-observatory

The degradation of the permanent seminatural vegetation and the resulting acceleration of soil degradation and erosion processes constitute major elements of land degradation in the Mediterranean basin. Given the European Commission's interest in mapping and controlling desertification phenomena in the Mediterranean member states, the Environmental Mapping and Modelling Unit (EMAP) of the Joint Research Centre is investigating possibilities for using operational earth observation satellites for mapping and repeated monitoring of vegetation and soil characteristics. In the context of previous experiments, approaches have been developed that can already be routinely applied to large regions. This paper discusses the problems of standardized retrieval of remotely sensed primary parameters (such as reflectance), concepts relating to the thematic interpretation of reflectance data, and the definition of satellite-derived degradation indices. In addition, this paper presents requirements for designing an operational satellite observatory for monitoring Mediterranean land degradation.     

The effect of humic acids on the sequential extraction of metals in soils and sediments using ICP-AES and chemometric analysis

The effect of humic acids on the sequential extraction of metals from various soils and sediments has been studied. A new multi-element extraction method optimised via experimental design has been employed. The method uses centrifugation to pass the extractant solution, at varying pH, through the sediment sample. The sequential leaches were collected and analysed by ICP-AES. Chemometric data processing was utilised to identify the composition of the physico-chemical components in order to characterise the sample. A sediment sample collected from Carnon River (Cornwall, UK) and a reference material (NIST 2711 agricultural soil) were spiked with humic acids and the sequential extraction scheme was used to monitor the changes in metal distribution. The method has proved a quick and reliable way to evaluate different sediment samples, and has potential as a new tool for environmental geochemistry analysis.     

A LANDSCAPE‐BASED APPROACH TO ESTIMATE RIPARIAN HYDROLOGICAL AND NITRATE REMOVAL FUNCTIONS1

ABSTRACT: This study evaluates a conceptual model developed for riparian zones in Ontario, Canada, that links landscape hydrogeological characteristics to riparian ground water hydrology and nitrate removal efficiency. Data from a range of riparian sites in the United States and Europe suggest that the riparian zone types identified in the model are consistent with patterns of riparian hydrology and nitrate flux and removal in many humid temperate landscapes. These data also support the view that a riparian width of less than 20 m is often sufficient for effective nitrate removal unless riparian sediments are coarse grained or nitrate transport occurs mainly in surface‐fed ground water seeps. This study assesses the possibility of using topographic, soil, surficial geology, and vegetation maps to determine landscape attributes linked by the model to riparian zone hydrological functioning and nitrate removal efficiency. Although mappable data can help in determining broad classes of riparian zones, field visits are necessary to determine non‐mappable riparian attributes such as seeps, organic horizons, and permeable sediment depth in the riparian zone. This research suggests that the conceptual model could be used for landscape management purposes in most temperate landscapes with minor modifications and that the hydrological component of the model could be adapted for contaminants other than nitrate.     

A Hydrological Model for Predicting the Effects of Dams on the Shoreline Vegetation of Lakes and Reservoirs

/ The species richness of shoreline vegetation of unregulated lakes in Nova Scotia, Canada, is known to increase as a function of catchment area, a topographic variable governing water level fluctuations. Predictions based on catchment area however, fail to account for richness patterns at the margins of lakes enlarged by dams. Here, we compare the vegetation and hydrological regimes of regulated and unregulated systems. Hydrological regimes of regulated systems deviated from natural systems of similar catchment area by being either hypovariable or hypervariable for both within-year and among-year fluctuations in water level. Plant communities of dammed systems were less diverse, contained more exotic species, and were, with one exception, devoid of rare shoreline herbs. Data from "recovering," or previously dammed systems indicated that shoreline communities can be restored upon return of the appropriate hydrological regime. Using observed within-year and among-year water level fluctuation data, we propose a general model for the maintenance or restoration of diverse herbaceous wetlands on shorelines of temperate lakes or reservoirs. Managers can manipulate the within-year water level variation within prescribed limits (1-2 m), while ensuring that among-year variation (SD of summer levels) is less than 25% of within-year variation. This preliminary model is based on data from low-fertility, temperate lakes in river systems. To calibrate the model, plant community data from other regions are needed, as are long-term water-level data for unregulated lakes, data which are essential but largely lacking in many areas.KEY WORDS: Catchment area; Regulated lakes; Shoreline restoration; Rare plants; Exotic plants; Diversity     

Short communication the natural history of fetal cytomegalovirus infection as assessed by serial ultrasound and fetal blood sampling: A case report

A patient in whom intrauterine fetal cytomegalovirus (CMV) infection was diagnosed at approximately 25 weeks' gestation is presented. The fetus was evaluated by serial fetal blood samplings and ultrasound examinations. The fetus manifested evidence of severe thrombocytopenia and hepatic inflammation, with recovery over a period of approximately 8 weeks. The initial sonographic findings of marked fetal ascites and cardiomegaly gradually resolved; ventriculomegaly developed during the third trimester. At delivery, the baby was morphologically normal with the exception of mild ventriculomegaly. Cord blood was negative for CMV IgM but urine was culture-positive for CMV. At age 3, the child has a severe but stable unilateral hearing deficit and is otherwise developmentally normal. This case demonstrates the utility of serial ultrasound and fetal blood sampling in the prenatal diagnosis and management of fetal CMV infection.     

Are chaos and catastrophe theories relevant to environmental sciences?

Data acquired in the area of Environmental Sciences are by their very nature often discontinuous and abrupt. As such, the mathematical theories of catastrophe and chaos may be of use in analyzing such scientific data and in formulating mathematical models.     

Long-term trends in the trophic structure of the North Sea fish community: evidence from stable-isotope analysis, size-spectra and community metrics

Fishing has wide-ranging impacts on marine ecosystems. One of the most pervasive signs of intensive fishing is "fishing down the food web", with landings increasingly dominated by smaller species from lower trophic levels. Decreases in the trophic level of landings are assumed to reflect those in fish communities, because size-selective mortality causes decreases in the relative abundance of larger species and in mean body size within species. However, existing analyses of fishing impacts on the trophic level of fish communities have focused on the role of changes in species composition rather than size composition. This will provide a biased assessment of the magnitude of fishing impacts, because fishes feed at different trophic levels as they grow. Here, we combine body size versus trophic level relationships for North Sea fishes (trophic level assessed using nitrogen stable-isotope analysis) with species-size-abundance data from two time-series of trawl-survey data (whole North Sea 1982-2000, central and northern North Sea 1925-1996) to predict long-term trends in the trophic structure of the North Sea fish community. Analyses of the 1982-2000 time-series showed that there was a slow but progressive decline in the trophic level of the demersal community, while there was no trend in the trophic level of the combined pelagic and demersal community. Analyses of the longer time-series suggested that there was no trend in the trophic level of the demersal community. We related temporal changes in trophic level to temporal changes in the slopes of normalised biomass size-spectra (which theoretically represent the trophic structure of the community), mean log₂ body mass and mean log₂ maximum body mass. While the size-based metrics of community structure showed long-term trends that were consistent with the effects of increased fishery exploitation, these trends were only correlated with trophic level for the demersal community. Our analysis suggests that the effects of fishing on the trophic structure of fish communities can be much more complex than previously assumed. This is a consequence of sampled communities not reflecting all the pathways of energy transfer in a marine ecosystem and of the absence of historical data on temporal and spatial changes in the trophic level of individuals. For the North Sea fish community, changes in size structure due to the differential effects of fishing on species and populations with different life histories are a stronger and more universal indicator of fishing effects than changes in mean trophic level.     

Antenatal diagnosis of a congenital nasolacrimal duct cyst by ultrasonography: A case report

With proximal and distal obstruction to the lacrimal drainage system, mucus accumulates forming a cyst. In order to diagnose a nasolacrimal duct cyst antenatally, the sonographer must image the region adjacent to the orbits.     

Diets of four decapod crustaceans (Linuparus trigonus,Metanephrops andamanicus,M. australiensis and M. boschmai) from the continental shelf around Australia

Linuparus trigonus (Palinuridae) was collected from northeast Australia at depths of 220 to 300 m in the austral summer of 1985–1986 and its diet was analysed for diel feeding-periodicity and composition. The sex and size of the lobsters and the depth at which they were caught were recorded. About 35% of the foreguts were less than 10% full. L. trigonus appears to be a predator of slow-moving or nearsessile benthic invertebrates; its diet is mainly bivalves, gastropods, ophiuroids, crustaceans, polychaetes, and foraminiferans. Most dietary items differed significantly between the size classes of lobster. The frequency of crustacean remains increased with depth and more gastropods were consumed by lobsters caught at 260 m than at other depths. No significant periodicity in feeding was found for L. trigonus. The foreguts of three Metanephrops spp. (Nephropidae) collected from north-west Australia in August 1983 (M. andamanicus) and January/February 1984 (M. australiensis and M. boschmai) were nearly empty, and nearly half were less than 10% full. Fish, crustaceans and squids were the most common food items eaten. The main food items varied between the species: M. andamanicus ate nearly equal amounts of fish and crustaceans; M. australiensis ate chiefly crustaceans; M. boschmai mainly ate fish and seldom fed on squid. Metanephrops spp. appear to feed by attacking mobile animals and tearing off appendages or by scavenging.