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161.
Huy Tran Hong Phat Bui Dai Thi Cao Minh Van Viet Pham 《Environmental Chemistry Letters》2019,17(1):527-531
Environmental Chemistry Letters - Tin oxide nanoparticles (SnO2 NPs) with a diameter less than 10 nm are usually used in waste water treatment via the photocatalytic reaction. However,... 相似文献
162.
C. Van Dover 《Marine Biology》2002,141(4):761-772
Exploration of hydrothermal vent systems in locations remote from well-studied sites allows ecologists to determine the degree of site-specific variation in trophic relationships among communities. A preliminary outline of the trophic structure of the Kairei hydrothermal vent community on the Central Indian Ridge (25°19.23′S; 70°02.42′E) is provided here, based on analysis of collections from an April 2001 expedition. Invertebrate biomass at Kairei is dominated by organic carbon with a δ13C isotopic value of about –13‰, due to the abundance of primary consumers (shrimp: Rimicaris aff. exoculata) and secondary consumers (anemones: Marianactis n. sp.) with this isotopic composition. Filamentous thiotrophic episymbionts on shrimp have been interpreted to be the major diet items of the shrimp and hence are the dominant primary producers within the community. Free-living autotrophic microorganisms are implicated as the dietary base for other invertebrate species. Four trophic groups are identified within the Kairei invertebrates based on carbon- and nitrogen-isotope ratios, but these groups do not always define discrete trophic levels. Ontogenetic shifts in diet are documented for R. aff. exoculata and brachyuran crabs (Austinograea n. sp.). Diets of symbiont-bearing mussels (Bathymodiolus aff. brevior) and two species of gastropods are isotopically constant throughout the range of sizes analyzed. There is a consistent but unexplained pattern of increasing nitrogen isotopic composition with increasing carbon isotopic composition in vent communities from geographically disjunct oceanic regions. Given the assumptions associated with interpretations of isotopic data, there remains a missing pool of carbon (presumably unsampled bacterial biomass) that contributes to the maintenance of the 13C- and 15N-enriched primary consumers in these ecosystems. 相似文献
163.
Large-Scale Conversion of Forest to Agriculture in the Boreal Plains of Saskatchewan 总被引:1,自引:0,他引:1
Keith A. Hobson †‡ Erin M. Bayne † Steve L. Van Wilgenburg 《Conservation biology》2002,16(6):1530-1541
164.
László Z. Garamszegi Thorsten J. S. Balsby Ben D. Bell Marta Borowiec Bruce E. Byers Tudor Draganoiu Marcel Eens Wolfgang Forstmeier Paolo Galeotti Diego Gil Leen Gorissen Poul Hansen Helene M. Lampe Stefan Leitner Jan Lontkowski Laurent Nagle Erwin Nemeth Rianne Pinxten Jean-Marc Rossi Nicola Saino Aurélie Tanvez Russell Titus János Török Els Van Duyse Anders P. Møller 《Behavioral ecology and sociobiology》2005,57(4):305-317
Repertoire size, the number of unique song or syllable types in the repertoire, is a widely used measure of song complexity in birds, but it is difficult to calculate this exactly in species with large repertoires. A new method of repertoire size estimation applies species richness estimation procedures from community ecology, but such capture-recapture approaches have not been much tested. Here, we establish standardized sampling schemes and estimation procedures using capture-recapture models for syllable repertoires from 18 bird species, and suggest how these may be used to tackle problems of repertoire estimation. Different models, with different assumptions regarding the heterogeneity of the use of syllable types, performed best for different species with different song organizations. For most species, models assuming heterogeneous probability of occurrence of syllables (so-called detection probability) were selected due to the presence of both rare and frequent syllables. Capture-recapture estimates of syllable repertoire size from our small sample did not differ significantly from previous estimates using larger samples of count data. However, the enumeration of syllables in 15 songs yielded significantly lower estimates than previous reports. Hence, heterogeneity in detection probability of syllables should be addressed when estimating repertoire size. This is neglected using simple enumeration procedures, but is taken into account when repertoire size is estimated by appropriate capture-recapture models adjusted for species-specific song organization characteristics. We suggest that such approaches, in combination with standardized sampling, should be applied in species with potentially large repertoire size. On the other hand, in species with small repertoire size and homogenous syllable usage, enumerations may be satisfactory. Although researchers often use repertoire size as a measure of song complexity, listeners to songs are unlikely to count entire repertoires and they may rely on other cues, such as syllable detection probability.Communicated by A. Cockburn 相似文献
165.
Arsenic in groundwaters of the Lower Mekong 总被引:1,自引:0,他引:1
Stanger G Truong TV Ngoc KS Luyen TV Thanh TT 《Environmental geochemistry and health》2005,27(4):341-357
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible
arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to
provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general
natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at
typical concentrations of between 8 and 16 ppm; (dry weight). Industrial and agricultural arsenic is localised and relatively
unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 μg L−1, although scattered anomalous areas of 10 to 30 μg L−1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 μg L−1, are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water
level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters
result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under
reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper
aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards,
and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture.
An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction
in the future, will require continuing caution in water resources development throughout the region. 相似文献
166.
Statistical modeling of seasonal and environmental influences on the population dynamics of an estuarine fish community 总被引:1,自引:0,他引:1
A statistical modeling study was performed on the population fluctuations of the 15 commonest fish species frequenting the tidal Scheldt estuary in Belgium. These included marine juvenile and seasonal visitors, estuarine residents and diadromous fish species that were recorded on the filter screens of a power plant cooling-water intake between September 1991 and April 2001. The species population abundance was regressed against a candidate set of 6 environmental variables and 13 instrumental variables, accounting for seasonality and long-term trends present in the data. Population abundances of the different species were, in general, best described by seasonal variables. Seasonal components contributed, on average, up to 63.8% of the variance explained by the models. Ten species were found to show a slightly negative, though significant, trend over the period of the survey. Most models also included at least one environmental variable, and 25.4% of the explained variance could be attributed to environmental fluctuations. Of all physico-chemical variables, dissolved oxygen was the most important predictor of fish abundance, suggesting that the estuary suffered from poor water quality during the survey. Temperature, salinity, freshwater flow, suspended solids and chlorophyll a concentrations were minor determinants of fish abundance.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
167.
Glenn T. Crossin Scott G. Hinch Steven J. Cooke David W. Welch Sonia D. Batten David A. Patterson Glen Van Der Kraak J. Mark Shrimpton Anthony P. Farrell 《Marine Biology》2007,152(4):905-918
Adult sockeye salmon (Oncorhynchus nerka, N = 179) from six Fraser River populations (British Columbia) were intercepted in continental shelf waters ∼215 km from the
Fraser River mouth, gastrically implanted with acoustic transmitters, non-lethally biopsied for blood biochemistry, gill Na+,K+-ATPase activity and somatic energy density and then released. Migration behaviour and travel times to the river mouth and
into the river were monitored by underwater telemetry receivers positioned at the river mouth and in the river. Post-release
survival of salmon was excellent, with 84% (N = 150) of fish reaching the furthest receiving station ∼85 km upriver. Fish from Late-summer run populations (Adams and Weaver
Creek) averaged a migration rate of ∼20 km day−1 through the marine area and held at the river mouth and adjacent areas for 7–9 days before entering the river. Summer-run
populations (Birkenhead, Chilko, Horsefly and Stellako) had a migration rate ∼33 km day−1 and held for only 1–3 days. Once in river, similar patterns were observed: Late-run populations migrated at ∼28 km day−1 and Summer-run populations at ∼40 km day−1. From point of release to the river mouth, males migrated faster than females, but once in river migration rates did not
differ between sexes. Among all females, a correlation was discovered between levels of circulating testosterone and river
entry timing. This correlation was not observed among males. Plasma K+, Cl−, glucose, lactate and osmolality were also correlated with entry timing in both sexes. 相似文献
168.
Traditional approaches for biomass assessment of estuarine macrophytes over vast areas are time consuming. A methodology for quick and accurate biomass estimation of macrophytes, growing at intertidal mudflats, has been developed and verified. Using a calculated relation between biomass and colour densities on the aerial photographs, biomass of macrophytes over a large area (ca 900 ha) could be assessed with an accuracy of about 10%. Biomass estimates could be partitioned over seagrasses, various green algae and brown algae.Communication No. 330 Delta Institute for Hydrobiological Research, Yerseke, The Netherlands 相似文献
169.
The acetylene blockage technique was evaluated for measurement of denitrification in salt-marsh sediments (near Halifax, Nova Scotia, Canada). N2O in the gas phase of closed Spartina alterniflora marsh-sediment systems was analyzed with use of a thermal conductivity gas chromatograph sensitive to approximately 0.1 nmoles ml-1 gas. No N2O was detected for unfertilized sediment samples taken through the growing season and incubated in sealed buckets with 10% C2H2. For sediment samples amended with nitrate and for enrichments, initial rates of N2O evolution were higher in the presence of 10% C2H2 than in the absence of C2H2, but after longterm incubation N2O was consumed in some samples containing C2H2 as well as in samples without C2H2. In addition, total gaseous nitrogen (N2 and N2O) production in the absence of C2H2 was higher than in the presence of C2H2. Acetylene appears to be an inconsistent inhibitor of N2O reduction in salt-marsh sediments. The usefulness of the acetylene-denitrification technique in this habitat is, therefore, questionable. 相似文献
170.
An important topic in the registration of pesticides and the interpretation of monitoring data is the estimation of the consequences of a certain concentration of a pesticide for the ecology of aquatic ecosystems. Solving these problems requires predictions of the expected response of the ecosystem to chemical stress. Up until now, a dominant approach to come up with such a prediction is the use of simulation models or safety factors. The disadvantage of the use of safety factors is a crude method that does not provide any insight into the concentration–response relationships at the ecosystem level. On the other hand, simulation models also have serious drawbacks like that they are often very complex, lack transparency, their implementation is expensive and there may be a compilation of errors, due to uncertainties in parameters and processes. In this paper, we present the expert model prediction of the ecological risks of pesticides (PERPEST) that overcomes these problems. It predicts the effects of a given concentration of a pesticide based on the outcome of already performed experiments using experimental ecosystems. This has the great advantage that the outcome is more realistic. The paper especially discusses how this model can be used to translate measured and predicted concentrations of pesticides into ecological risks, by taking data on measured and predicted concentrations of atrazine as an example. It is argued that this model can be of great use to evaluate the outcome of chemical monitoring programmes (e.g. performed in the light of the Water Framework Directive) and can even be used to evaluate the effects of mixtures. 相似文献