Showing papers in "Environmental Monitoring and Assessment in 1996"

Control of rumen methanogenesis.

Abstract: During the last decades, considerable research on methane production in the rumen and its inhibition has been carried out. Initially, as methane production represents a significant loss of gross energy in the feed (2–15%), the ultimate goal of such intervention in rumen fermentation was an increase in feed efficiency. A second reason favouring research on methane inhibition is its role in the global warming phenomenon and in the destruction of the ozone layer. In this review, the authors describe briefly several interventions for reducing methane emission by ruminants. The objective can be reached by intervention at the dietary level by ration manipulation (composition, feeding level) or by the use of additives or supplements. Examples of additives are polyhalogenated compounds, ionophores and other antibiotics. Supplementation of the ration with lipids also lowered methanogenesis. More biotechnological interventions, e.g., defaunation, probiotics and introduction of reductive acetogenesis in the rumen, are also mentioned. It can be concluded that drastic inhibition of methane production is not unequivocally successful as a result of several factors, such as: instantaneous inhibition often followed by restoration of methanogenesis due to adaptation of the microbes or degradation of the additive, toxicity for the host animal, negative effects on overall digestion and productive performance. Therefore, methanogenesis and its inhibition cannot be considered as a separate part of rumen fermentation and its consequences on the animal should be taken into account.

Sampling to differentiate between pulse and press perturbations.

Abstract: There is great inconsistency in the use of the terms ‘pulse’ and ‘press’ when describing types of perturbations. This is due primarily to a failure to distinguish between the cause and the effect of the perturbation in question. The cause and effect may be either short- or long-term and clearly one may be short-term and the other long-term. Distinction between these two types of disturbance is crucial for management to prevent further impact. Thus, it is important to describe separately these two aspects of a perturbation. Here, we define a protocol for sampling perturbations which enables the cause and effect to be distinguished between short- or long-term. Existing (i.e., already established) assemblages and newly-established assemblages are sampled and compared among disturbed and control locations. Existing assemblages may have been affected by past (pulse) disturbances and/or ongoing (press) disturbances, whereas the establishment of new assemblages can only be influenced by ongoing disturbances. We describe the procedures for assessing impacts of estuarine marinas as an illustration of the issues to be considered in any habitat. Settlement plates and defaunated sediment are suggested for sampling the establishment of new assemblages in aquatic environments.

Investigation of the use of honey bees and honey bee products to assess heavy metals contamination.

Abstract: Experiment was carried out using 12 colonies of honey bees bred in hives located near an extraurban crossroad. We analyzed the Pb, Cd and Zn deposited on the bee's surfaces and the heavy metal accumulation in the foragers, dead bees, honey products and some environmental markers during nine weeks of the experiment. Results showed a large amount of Zn and Cd on the bee's surface as a consequence of atmospheric fallout, whereas Pb seems to be either water-extractable and/or likely accumulated in the body of the insect. Dead bees expelled from the hives displayed a progressive accumulation of all heavy metals during the experimental period. Royal jelly and honey contained large amounts of heavy metals. In particular, we found a linear relationship between Cd in the honey and that found in flowers of Trifolium pratense L. Results obtained suggested that honey bee products and the examined environmental markers may be considered useful parameters to assess the presence of environmental contaminants, whereas the measurements of heavy metals in the dead bees may be considered a suitable tool also to verify a possible dynamics of accumulation of pollutants.

Estimates of animal methane emissions.

Abstract: The enteric methane emissions into the atmospheric annually from domestic animals total about 77 Tg. Another 10 to 14 Tg are likely released from animal manure disposal systems. About 95% of global animal enteric methane is from ruminants, a consequence of their large populations, body size and appetites combined with the extensive degree of anaerobic microbial fermentation occurring in their gut. Accurate methane estimates are particularly sensitive to cattle and buffalo census numbers and estimated diet consumption. Since consumption is largely unknown and must be predicted, accuracy is limited often by the information required, i.e., distribution of animals by class, weight and productivity. Fraction of the diet lost as enteric methane mostly falls into the range of 5.5–6.5% of gross energy intake for the world's cattle, sheep and goats. Manure methane emissions are heavily influenced by fraction of disposal by anaerobic lagoon. Non-ruminants, i.e., swine, become major contributors to these emissions.

Fluxes and pools of methane in wetland rice soils with varying organic inputs

Abstract: Measurements of methane emission rates and concentrations in the soil were made during four growing seasons at the International Rice Research Institute in the Philippines, on plots receiving different levels of organic input. Fluxes were measured using the automated closed chambers system (total emission) and small chambers installed between plants (water surface flux). Concentrations of methane in the soil were measured by collecting soil cores including the gas phase (soil-entrapped methane) and by sampling soil solution in situ (dissolved methane). There was much variability between seasons, but total fluxes from plots receiving high organic inputs (16-24 g CH4 m(-2)) always exceeded those from the low input plots (3-9 g CH4 m(-2)). The fraction of the total emission emerging from the surface water (presumably dominated by ebullition) was greater during the first part of the season, and greater from the high organic input plots (35-62%) than from the low input plots (15-23%). Concentrations of dissolved and entrapped methane in the low organic input plots increased gradually throughout the season; in the high input plots there was an early-season peak which was also seen in emissions. On both treatments, periods of high methane concentrations in the soil coincided with high rates of water surface flux whereas low concentrations of methane were generally associated with low flux rates.

Methane emissions from natural wetlands.

Abstract: Methane is considered one of the most important greenhouse gases in the atmosphere. Because of the strict anaerobic conditions required by CH4-generating microorganisms, natural wetland ecosystems are one of the main sources of biogenic CH4. The total natural wetland area is estimated to be 5.3 to 5.7 × 1012 m2, making up less than 5% of the Earth's land surface. However, natural wetland plays a disproportionately large role in CH4 emissions. Wetlands are likely the largest natural sources of CH4 to the atmosphere, accounting for about 20% of the current global annual emission. Out of the total amount of CH4 emitted, northern wetlands contribute 34%, temperate wetlands 5%, and tropical systems about 60%.

Forest dynamics modelling under natural fire cycles: A tool to define natural mosaic diversity for forest management.

Abstract: In natural boreal forests, disturbances such as fire and variation in surficial deposits create a mosaic of forest stands with different species composition and age. At the landscape level, this variety of stands can be considered as the natural mosaic diversity. In this paper, we describe a model that can be used to estimate the natural diversity level of landscapes. We sampled 624 stands for tree species composition and surficial deposits in eight stand-age classes corresponding to eight fire episodes in the region of Lake Duparquet, Abitibi, Quebec at the southern fringe of the Boreal Forest. For six surficial deposit types, stand composition data were used to define equations for vegetation changes with time for a chronosequence of 230 years for four forest types. Using Van Wagner’s (1978) model of age class distribution of stands, the proportion of each forest type for several lengths of fire cycle were defined. Finally, for real landscapes (ecological districts) of the ecological region of the “Basses-Terres d’Amos”, the proportion of forest types were weighted by the proportion of each surficial deposit type using ecological map information. Examples of the possible uses of the model for management purposes, such as biodiversity conservation and comparisons of different landscapes in terms of diversity and sensitivity to fire regime changes, are discussed.

Copper mine tailing disposal in northern Chile rocky shores: Enteromorpha compressa (Chlorophyta) as a sentinel species

Abstract: The study assesses the ecological impact caused by the El Salvador untreated (1975-1990) and treated (1991-1994) copper mine tailings on rocky intertidal communities in and around the dumping site at Caleta Palito, northern Chile. Ecological changes are monitored for 16 years in polluted and unpolluted sites within a geographical area of 90 km. Copper concentration levels in water and the intertidal Chlorophyta E. compressa are presented. The results confirm a notorious reduction in the number of species and significant differences between polluted and unpolluted intertidal communities. At polluted sites, following the initiation of the disposal, all species of invertebrates and algae disappeared and primary space (rock) was partially or completely dominated by E. compressa along more than a decade. Its persistence in these sites supports the view that this taxon is a sentinel species resisting high levels of copper pollution. During the past four years, following the steps given to treat the tailings, at polluted sites there are preliminary indications showing increases in the number of species of algae and invertebrate. The need for future monitoring to elucidate ecosystem restoration processes is discussed.

The rumen and hindgut as source of ruminant methanogenesis.

Abstract: The advantage of ruminants is their ability to convert fibrous biomass to high quality protein for human nutrition purposes. Rumen fermentation, however, is always associated with the formation of methane - a very effective greenhouse gas. Hindgut fermentation differs from rumen fermentation by a substantially lower methane production and the presence of reductive acetogenesis or dissimilatory sulfate reduction. Sulfate reduction and methanogenesis seem to be mutually exclusive, while methanogenesis and reductive acetogenesis may occur simultaneously in the hindgut. Although acetogenic bacteria have been isolated from the bovine rumen, methanogenesis prevails in the forestomachs. The substitution of acetate for methane as a hydrogen sink in the rumen should increase energy yield for the animal and decrease methane emissions into the environment. Differences in the major hydrogen sinks in both microbial ecosystems are discussed and mainly related to differences in substrate availability and to the absence of protozoa in the hindgut.

Methanogenesis in monogastric animals

Abstract: Studies of methanogenic bacteria present in monogastric animals are still scarce. Methanogens have been isolated from faeces of rat, horse, pig, monkey, baboon, rhinoceros, hippopotamus, giant panda, goose, turkey and chicken. The predominant methanogen in all except the chicken and turkey is species of Methanobrevibacterium. The chicken and turkey harbour species of Methanogenium. In pig the population of methanogenic bacteria is more than 30 times as dense in the distal colon as in the caecum. This finding is in agreement with the finding that the rate of methane production is much higher in the colon than in the ceacum. The amount of methane excreted clearly seems to depend on the amount of non-starch polysaccharide intake. The directly measured methane production rate in pigs is from 3.3 to 3.8 times lower than the amount expected from stoichiometric estimates. These data, together with data showing that only small net amounts of hydrogen and small amounts of methane are produced in the ceacum and proximal colon where the microbial activity is high, clearly indicate that hydrogen sinks other than methane production are involved in hydrogen removal in the hindgut of pigs and probably also in other monogastric animals. Methane production by monogastric animals is lower than methane production by ruminants. However, methane production by large herbivorous monogastric animals such as horses, mules and asses is substantial (up to 80 l per animal per day). Methane production by rodents and avians is low. In general, methane production by wild animals is lower than methane production by domestic animals. It is concluded that the contribution of monogastric animals to the global methane emission is negligible, as it only represent about 5% of the total methane emission by domestic and wild animals of 80 Tg per year.

Assessing the toxic threat of selenium to fish and aquatic birds

Abstract: A procedure is given for evaluating the toxic threat of selenium to fish and wildlife. Toxic threat is expressed as hazard, and is based on the potential for food-chain bioaccumulation and reproductive impairment in fish and aquatic birds, which are the most sensitive biological responses for estimating ecosystem-level impacts of selenium contamination. Five degrees of hazard are possible depending on the expected environmental concentrations of selenium, exposure of fish and aquatic birds to toxic concentrations, and resultant potential for reproductive impairment. The degree of hazard is given a numerical score: 5 = high hazard, 4 = moderate hazard, 3 = low hazard, 2 = minimal hazard, and 1 = no identifiable hazard. A separate hazard score is given to each of five ecosystem components; water, sediments, benthic macroinvertebrates, fish eggs, and aquatic bird eggs. A final hazard characterization is determined by adding individual scores and comparing the total to the following evaluation criteria: 5 = no hazard, 6-8 = minimal hazard, 9-11 = low hazard, 12-15 = moderate hazard, 16-25 = high hazard. An example is given to illustrate how the procedure is applied to selenium data from a typical contaminant monitoring program.

The ITE Land classification: Providing an environmental stratification of Great Britain.

Abstract: The surface of Great Britain (GB) varies continuously in land cover from one area to another. The objective of any environmentally based land classification is to produce classes that match the patterns that are present by helping to define clear boundaries. The more appropriate the analysis and data used, the better the classes will fit the natural patterns. The observation of inter-correlations between ecological factors is the basis for interpreting ecological patterns in the field, and the Institute of Terrestrial Ecology (ITE) Land Classification formalises such subjective ideas. The data inevitably comprise a large number of factors in order to describe the environment adequately. Single factors, such as altitude, would only be useful on a national basis if they were the only dominant causative agent of ecological variation.

Copper-algae interactions: Inheritance or adaptation?

Abstract: This study evaluated the responses of wild, adult plants of Enteromorpha compressa, and their progeny, to various copper concentrations. Experiments were designed to test the hypotheses that: 1) individuals of E. compressa from Caleta Palito, a copper-enriched coastal locality, tolerate higher copper concentrations than those from a place with no history of copper pollution and 2) such copper tolerance is under genetic control and therefore, was an inherited character. Our results indicate that algae which inhabit a copper-enriched environment tolerate higher concentrations of copper than those from waters with low copper concentrations. On the other hand, our results suggest that generalizations regarding heritability of the tolerance to copper do not apply to the Chilean E. compressa, as no differences in growth or rhizoid production were found between the progeny from Caleta Palito and Caleta Zenteno. These findings are an indication that heritability and adaptation may represent alternative strategies used by different populations of the same algal species to tolerate copper.

Environmental impact of biomethanogenesis.

Abstract: The environmental impact of biomethanogenesis is related to its ecological role, accumulation and effect as a greenhouse gas, and application in anaerobic digestion for conversion of biomass and wastes to methane and compost. Biological formation of methane is the process by which bacteria decompose organic matter using carbon dioxide as an electron acceptor in the absence of dioxygen or other electron acceptors. This microbial activity is responsible for carbon recycling in anaerobic environments, including wetlands, rice fields, intestines of animals sediments, and manures. The mixed consortium of microorganisms involved includes a unique group of bacteria, the methanogens, which may be considered to be in a separate kingdom based on genetic and phylogenetic variance from all other life forms. Because methane is a significant and increasing greenhouse gas, its source fluxes and their potential reduction are of concern. Biomethanogenesis may be harnessed for reduction of wastes and conversion of renewable resources to significant quantities of substitute natural gas which could mitigate carbon dioxide and other pollutants related to use of fossil fuels.

A national framework for monitoring and reporting on environmental sustainability in Canada.

Abstract: In 1991, a collaborative project to revise the terrestrial component of a national ecological framework was undertaken with a wide range of stakeholders. This spatial framework consists of multiple, nested levels of ecological generalization with linkages to existing federal and provincial scientific databases. The broadest level of generalization is the ecozone. Macroclimate, major vegetation types and subcontinental scale physiographic formations constitute the definitive components of these major ecosystems. Ecozones are subdivided into approximately 200 ecoregions which are based on properties like regional physiography, surficial geology, climate, vegetation, soil, water and fauna. The ecozone and ecoregion levels of the framework have been depicted on a national map coverage at 1:7 500 000 scale. Ecoregions have been subdivided into ecodistricts based primarily on landform, parent material, topography, soils, waterbodies and vegetation at a scale (1:2 000 000) useful for environmental resource management, monitoring and modelling activities. Nested within the ecodistricts are the polygons that make up the Soil Landscapes of Canada series of 1:1 000 000 scale soil maps. The framework is supported by an ARC-INFO GIS at Agriculture Canada. The data model allows linkage to associated databases on climate, land use and socio-economic attributes.

Butyltin contamination of sediments and benthic fish from the East, Gulf and Pacific coasts of the United States.

Abstract: Butyltin concentrations were determined in sediments, tissues and stomach contents of fish collected in 41 embayments on the East, Gulf and Pacific coasts of the U.S.A. between 1986 and 1991 as part of the National Oceanic and Atmospheric Administration's (NOAA) National Benthic Surveillance Project (NBSP). A total of 99 sediments, 108 fish liver samples from 11 fish species, and 10 composites of fish stomach contents were analyzed for tetrabutylin, tributylin, dibutylin and monobutylin. Tributyltin (TBT) was detected (i.e. > 10 ng/g) in 38 of the sediments samples analyzed and was generally the predominant bulytin present; concentrations of total butyltins ranged from 15 to 1600 ng/g wet weight. The highest concentrations were found in sediments from urban sites, especially sites on the West coast. Many of the fish liver and stomach contents samples also contained butyltins. Tributyltin represented 83 (7.1)% [mean (SEM); n=15], 64 (6.6)% (n=12) and 36 (7.8)% (n=12) of the total butyltins in livers from white croaker, winter flounder and Atlantic croaker, respectively, suggesting possible species differences in biotransformation of TBT. The concentrations of butyltins in stomach contents indicated that diet can be a significant route of exposure of fish to butyltins. Between 1986 and 1991 butyltin concentrations in sediments and fish generally appeared to be declining; however, no statistically significant temporal trends were observed at individual sites or for the sites overall.

Organochlorine insecticide residues in agricultural soils of the indo-gangetic plain.

Abstract: Multiple residues of organochlorine insecticides were monitored in the agricultural fields near Farrukhabad in the vicinity of the River Ganga in northern India for one year (1991–1992). Almost all soil samples were found to be contaminated with residues of hexachlorocylohexane (HCH) and dichlorodiphenyl-trichloroethane (DDT). Residues of aldrin and endosulfan were also detected in a large number of samples. Heptachlor residues were scarcely detected. Alpha-HCH, pp′-DDT and alpha-endosulfan were found to dominate over the other isomers/metabolites of HCH, DDT and endosulfan, respectively. The average concentration of dieldrin was more than that of aldrin. The concentrations of residues progressively increased up to a depth of 1 m.

Land Classification and Ecosystem Classification

Abstract: Earth, the ecosphere, is a unified functional ecosystem. Ecological land classification (ELC) and regionalization divides and categorizes this unity into similar and dissimilar pieces-sectoral ecosystems - at various scales, in the interests of admiration and understanding. The recognition of land/water ecosystems in a hierarchy of sizes provides a rational base for the many-scaled problems of protection and careful exploitation in the fields of agriculture, forestry, wildlife and recreation. In forested terrain the protection of biodiversity, old growth forests, watersheds and wildlife habitat depends on spatial-temporal planning of forestry operations to maintain a preferred mosaic structure of local ecosystems within each ecological region. Without ecological understanding and a good ELC, this is impossible. Conceiving the world as comprising nested land/water ecosystems that are the source of life, elevates the role of Earth-as-context, an antidote to destructive anthropocentrism.

Persistent organochlorine residues in fish and water birds from the Biobio river, Chile

Abstract: Concentrations of polychlorinated biphenyls (PCBs), DDT and its metabolites, HCH isomers and hexachlorobenzene (HCB) were determined in fish and birds from different locations in the Biobio river basin (central Chile). Samples collected near the mouth of the river contained high concentrations of PCBs, reflecting the massive use of these xenobiotics in the urban and industrial areas of Concepcion and Talcauano. Samples collected in the central part of the basin contained very high concentrations of lindane that coincide with the widespread use of lindane-based pesticides (purified γ-HCH) in this area. DDT was distributed homogeneously throughout the basin, except at Laguna Icalma, the source of the river in the Andes. Most PCB residues in fish and birds consisted of congeners between penta- and hepta-chlorobiphenyls. In fish, the predominant congeners were the pentachlorobiphenyl 23'44'5 (IUPAC number 118) and the hexachlorobiphenyl 22'344'55' (PCB-153); in birds 22'44'55' (PCB-180) prevailed.

Genetic and evolutionary constraints for the symbiosis between animals and methanogenic bacteria.

Abstract: It has been assumed that the feeding habits of animals predispose the composition of the microbial biota living in their intestinal tracts. Here we show that in arthropods and vertebrates the presence of methanogenic bacteria requires a quality of the host that is under phylogenetic rather than dietary constraint: competence for intestinal methanogenic bacteria is a primitive-shared character among reptiles, birds, and mammals, and a shared-derived trait of millipedes, termites, cockroaches and scarab beetles. The presence of methanogenic bacteria seems to be a prerequisite for the evolution of anatomic specializations of the intestinal tract such as hindguts, caeca or rumina, and it is likely that it also has consequences for the reproductive strategies of the animals. Methanogenic animals contribute to atmospheric methane by their breath and faeces. Because the status as either methane-producer or non-producer is shared by most species belonging to a higher taxonomic unit, it is possible to calculate methane emissions that are characteristic for whole taxa. In combination with ecological field data on the biomass it is possible to arive at estimates concerning the global contributions by animals. The demonstration of a genetic basis for the symbiosis between methanogens and animals will allow new approaches for the reduction of methane emission by domestic animals.

Heavy metal concentrations in litteral sediments from the Beagle Channel, Tierra del Fuego, Argentina.

Abstract: For the first time the concentration of trace metals (Fe, Pb, Cu, Zn, Cd and total Hg) of sediments from the coastal zone of the Beagle Channel (Tierra del Fuego, in Southern Argentina) were measured. Atomic absorption spectrophotometry was utilized in order to determine the metal contents. The level of metals as observed in the sediments was recognized as the natural background, even though the use of normalization of lead, copper, and zinc to iron allowed the identification of the main sources of metal pollution for this environment. In order to develop future environmental monitoring programmes for the area of Ushuaia city and the Beagle Channel, the present results need to be considered.

Structural characteristics of post-wildfire and clearcut landscapes

Abstract: A continuing discussion in the field of ecology and forest management concerns the implications of clearcutting as a functional replacement for wildfire in disturbance-driven ecosystems. At the landscape level, spatial pattern has been shown to influence many ecologically important processes. Satellite imagery allows the evaluation of structural patterns created by alternative forest management activities at broad scales. In Northwestern Ontario, both clearcutting and wildfire have occurred over large contiguous areas. Spatial characteristics including composition, patch size, patch shape, and interspersion were calculated from classified Landsat Thematic Mapper (TM) data at two thematic scales and used to compare post-wildfire and clearcut landscapes. Patches in the clearcut landscape were found to be larger in size, and had a more irregular shape than those in the wildfire landscape. Differences in landscape structure were much more pronounced at broad scales than at fine thematic scales.

Quantitative assessment of eutrophication: A scoring system for characterising water quality in coastal marine ecosystems

Abstract: A scoring system based on nutrient concentrations was developed to assess coastal water quality according to the trophic level Three nutrient data sets from eutrophic, mesotrophic and oligotrophic waters were used as the reference information for setting up a semi quantitative water quality scale (from 0 to 5) to express different nutrient loadings The validity and sensitivity of the method was applied to a number of stations spaced out along the coastal area of Rhodes (Greece) A score for each nutrient/sampling site was calculated and the scorecard formed, was the data matrix used for numerical classification of the stations The results showed (a) good discrimination between cutrophic, mesotrophic and oligotrophic waters (b) nitrate among the nutrients showed the maximum sensitivity in characterising pollution levels The reference data sets used for assessing eutrophication levels ensured the objectivity of the method The proposed method is described step-by-step and it is suggested that the method can be further adapted to describe other forms of pollution becoming a useful quantitative technique in coastal management practices

Temporal and spatial variability in water quality of wetlands in the Minneapolis/St. Paul, MN metropolitan area: Implications for monitoring strategies and designs

Abstract: Temporal and spatial variability in wetland water-quality variables were examined for twenty-one wetlands in the Minneapolis/St. Paul metropolitan area and eighteen wetlands in adjacent Wright County. Wetland water quality was significantly affected by contact with the sediment (surface water vs. groundwater), season, degree of hydrologic isolation, wetland class, and predominant land-use in the surrounding watershed (p edaphic factors>detritivory>land-use factors>biotic-redox or other multiple factors. For two wetlands sampled intensively, soluble reactive phosphate and total dissolved phosphorus were the most spatially variable (c.v.=76–249%), while temperature, color, dissolved organic carbon, and DO were least variable (c.v.=6–43%). Geostatistical analyses demonstrated that the average distance across which water-quality variables were spatially correlated (variogram range) was 61–112% of the mean radius of each wetland. Within the shallower of the two wetlands, nitrogen speciation was explained as a function of dissolved oxygen, while deeper marsh water-quality variables were explained as a function of water depth or distance from the wetland edge. Compositing water-quality samples produced unbiased estimates of individual sample means for all water quality variables examined except for ammonium.

Impacts of logging and wildfire on an upland black spruce community in northwestern Ontario.

Abstract: Plant species composition and community structure were compared among four sites in an upland black spruce community in northwestern Ontario. One site had remained undisturbed since the 1930s and three had been disturbed by either logging, fire, or both logging and fire. Canonical correspondence ordination analyses indicated that herbaceous species composition and abundance differed among the disturbance types while differences in the shrub and tree strata were less pronounced. In the herb stratum Pleurozium schreberi, Ptilium crista-castrensis and Dicranurn polysetum were in greatest abundance on the undisturbed forest site, while the wildfire and burned cutover sites were dominated by Epilobium angustifolium and Polytrichum juniperinum. The unburned harvested site was dominated by Epilobium angustifolium, Cornus canadensis and Pleurozium schreberi. Species richness was lower on the undisturbed site than on any of the disturbed sites while species diversity (H’) and evenness (Hill’s E5) were higher on the unburned harvested site than on the other sites. Results suggest that herb re-establishment is different among harvested and burned sites in upland black spruce communities and we hypothesize that differences in the characteristics of the disturbance were responsible, in particular, the impact of burning on nutrient availability. These differences need to be taken into account in determining the effects of these disturbances on biodiversity and long-term ecosystem management.

Fractionation of heavy metals and phosphorus in suspended sediments of the Yamuna river, India.

Abstract: The Yamuna river is the largest tributary of the Ganges river system. It originates in the Himalayas and flows through a varied geological terrain encompassing a large basin area. Metals Fe, Mn, Pb, Zn, Cu in different chemical fractions of suspended sediments such as exchangeable, carbonates, Fe−Mn oxides, organics and residual fractions were studied. Phosphorus associated with different chemical forms are discussed. The metals are mostly associated with residual fractions in the sediments followed by organics, Fe−Mn oxides, exhangeable and carbonates. Intensive use of chemical fertilizers and pesticides in agriculture in the basin affects the high inorganic phosphorus content in sediments.

Introduction-global to local: Ecological Land Classification.

Abstract: Ecological Land Classification (ELC) is a scientific endeavour which attempts to organize, stratify and evaluate ecosystems (and complexes of ecosystems) for the purposes of land resource management. Since ecosystems themselves are not easily defined in practical terms, ELC is likewise not a trivial concept. Nonetheless, ELC is a prerequisite for ecosystem management and the conservation of biological diversity simply because ecosystems must be described, characterized and spatially-located before they can be managed. Regarding the current status and future direction of ELC, mainly in relation to forest management: 1) approaches to ELC construction and utilization have shifted considerably over the past 2 decades; 2) there appears to be a current consensus regarding basic approaches to ELC; 3) spatial scale is a critical variable that must be addressed by ELCs; 4) ELCs must strive to more directly address management objectives; 5) natural ecosystem functions need to be better integrated within ELC frameworks; and, 6) the need for quality, georeferenced ELC-related data will continue to grow.

Factors controlling the accumulation of metals within fluvial systems.

Abstract: The magnitude and distribution of European Community (EC) regulated List I and List II metals and metalloids have been investigated in two lowland river systems in East Anglia, U.K. A combination of sediment and water quality data identified municipal sewage treatment work discharges as the main metal input sources to the river systems and identified two main areas of metal contamination: the Pix Brook, downstream of Letchworth STW on the River Ivel, and a 14 km enrichment zone adjacent to Whitlingham STW on the River Yare. The basement geology, flow dynamics, distance from point sources and sediment type were identified as important controls upon the magnitude and spatial distribution of metal contaminants.

Heavy metal and selenium levels in birds at Agassiz National Wildlife Refuge, Minnesota: Food chain differences.

Abstract: The levels of heavy metals and selenium in the eggs and in breast feathers of adult doublecrested cormorant (Phalacrocorax auritus), black-crowned night heron (Nycticorax nycticorax), and franklin's gull (Larus pipixcan) nesting at Agassiz National Wildlife Refuge in Marshall County, northwestern Minnesota were examined. Also examined were metal levels in the feathers of fledgling night herons and gulls, in the feathers of adult and fledgling American bittern (Botaurus lentiginosus), in eggs of American coot (Fulica americana) and eared grebe (Podiceps caspicus), and in feathers of adult Canada geese (Branta canadensis). These species represent different levels on the food chain from primarily vegetation-eating species (geese, coot) to species that eat primarily fish (cormorant). A clear, positive relationship between level on the food chain and levels of heavy metals occurred only for mercury in feathers and eggs. Otherwise, eared grebes had the highest levels of all other metals in their eggs compared to the other species. No clear food chain pattern existed for feathers for the other metals. For eggs at Agassiz: 1) lead, selenium, and manganese levels were similar to those reported in the literature, 2) mercury levels were slightly higher for cormorants and night herons, 3) all species had higher chromium and cadmium levels than generally reported, and 4) eared grebes had significantly higher levels of cadmium than reported for any species from elsewhere. For adult feathers: 1) gulls had higher levels of lead than the other species, 2) cadmium levels were elevated in gulls and adult herons and cormorants, 3) mercury levels showed an increase with position on the food chain, 4) selenium and chromium levels of all birds at Agassiz were generally low and 5) manganese levels in adults were generally higher than in the literature for other species. Adults had significantly higher mercury levels than fledgling gulls, night herons, and bitterns.

Classification of local- and landscape-scale ecological types in the southern Appalachian Mountains

Abstract: Five local ecological types based on vegetative communities and two landscape types based on groups of communities, were identified by integrating landform, soil, and vegetation components using multivariate techniques. Elevation and several topographic and soil variables were highly correlated with types of both scales. Landscape ecological types based only on landform and soil variables without vegetation did not correspond with types developed using vegetation. Models developed from these relationships could allow classification and mapping of extensive areas using geographic information systems.