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41.
Chambers PA McGoldrick DJ Brua RB Vis C Culp JM Benoy GA 《Journal of environmental quality》2012,41(1):7-20
Inputs of nutrients (P and N) to freshwaters can cause excessive aquatic plant growth, depletion of oxygen, and deleterious changes in diversity of aquatic fauna. As part of a "National Agri-Environmental Standards Initiative," the Government of Canada committed to developing environmental thresholds for nutrients to protect ecological condition of agricultural streams. Analysis of data from >200 long-term monitoring stations across Canada and detailed ecological study at ~70 sites showed that agricultural land cover was associated with increased nutrient concentrations in streams and this, in turn, was associated with increased sestonic and benthic algal abundance, loss of sensitive benthic macroinvertebrate taxa, and an increase in benthic diatom taxa indicative of eutrophication. Chemical thresholds for N and P were defined by applying five approaches, employing either a predetermined percentile to a water chemistry data set or a relationship between water chemistry and land cover, to identify boundaries between minimally disturbed and impaired conditions. Comparison of these chemical thresholds with biological thresholds (derived from stressor-response relationships) produced an approach for rationalizing these two types of thresholds and deriving nutrient criteria. The resulting criteria were 0.01 to 0.03 mg L(-1) total P and 0.87-1.2 mg L(-1) total N for the Atlantic Maritime, 0.02 mg L(-1) total P and 0.21 mg L(-1) total N for the Montane Cordillera, ~0.03 mg L(-1) total P and ~1.1 mg L(-1) total N for the Mixedwood Plains, and ~0.10 mg L(-1) total P and 0.39-0.98 mg L(-1) total N for the interior prairies of Canada. Adoption of these criteria should result in greater likelihood of good ecological condition with respect to benthic algal abundance, diatom composition, and macroinvertebrate composition. 相似文献
42.
Landslide Susceptibility Assessment and Validation in the Framework of Municipal Planning in Portugal: The Case of Loures Municipality 总被引:4,自引:0,他引:4
The legislation that demands the evaluation of landslide susceptibility in Portugal at the municipal level is the National Ecological Reserve (NER). A methodology for the evaluation of landslide susceptibility to be used in municipal planning is applied in Loures Municipality (169.3?km2) located north of Lisbon (Portugal). A landslide inventory was made for the whole area interpreting orthophoto maps and aerial photographs and using standard geomorphologic techniques in field work. It consists of 686 polygons, each polygon representing a rotational, a deep translational or a shallow translational slide, and is integrated into a GIS database. Landslide susceptibility is evaluated using algorithms based on statistical/probabilistic analysis (Information Value Method) over unique-condition terrain units in a raster basis. Three susceptibility models are elaborated independently according to the type of slide (rotational, deep translational, shallow translational). The landslide susceptibility maps are prepared by sorting all pixels according to the pixel susceptibility value in descending order. The robustness and accuracy of the landslide susceptibility models are evaluated by prediction-rate curves, which are used for the quantitative interpretation of the landslide susceptibility maps. Unstable slopes that have to be included into the National Ecological Reserve are extracted from the three susceptibility maps following the general rules to draw the NER that state that the area to be included in the NER should guarantee the inclusion of at least 70?% of the landslides identified in the landslide inventory. The obtained results allow us to conclude that 70?% of the future landslides should occur in these areas, classified as most susceptible to landslides corresponding to 20.3?% of the total area of Municipality. Thus, the consideration of these 20.3?% as regards prevention and protection of landslide risk could potentially reduce damage resulting from 70?% of future landslides in the Loures Municipality. 相似文献
43.
H. E. Markus Meier Helén C. Andersson Berit Arheimer Chantal Donnelly Kari Eilola Bo G. Gustafsson Lech Kotwicki Tina-Simone Neset Susa Niiranen Joanna Piwowarczyk Oleg P. Savchuk Frederik Schenk Jan Marcin Węsławski Eduardo Zorita 《Ambio》2014,43(1):37-48
We present a multi-model ensemble study for the Baltic Sea, and investigate the combined impact of changing climate, external nutrient supply, and fisheries on the marine ecosystem. The applied regional climate system model contains state-of-the-art component models for the atmosphere, sea ice, ocean, land surface, terrestrial and marine biogeochemistry, and marine food-web. Time-dependent scenario simulations for the period 1960–2100 are performed and uncertainties of future projections are estimated. In addition, reconstructions since 1850 are carried out to evaluate the models sensitivity to external stressors on long time scales. Information from scenario simulations are used to support decision-makers and stakeholders and to raise awareness of climate change, environmental problems, and possible abatement strategies among the general public using geovisualization. It is concluded that the study results are relevant for the Baltic Sea Action Plan of the Helsinki Commission. 相似文献
44.
Chantal Hamel 《Agriculture, ecosystems & environment》1996,60(2-3)
The arbuscular mycorrhizal symbiosis is recognized for its multiple positive effects on plant growth and for its important contribution towards the maintenance of soil quality. In spite of these benefits to agriculture, at present, the realization of the full potential of this symbiosis has not yet been reached. The understanding of interactions existing among crops, fungal partners and environmental conditions must improve to allow for the efficient management of the mycorrhizal symbiosis through selected agronomic practices and inoculation of cultivated crops. 相似文献
45.
E.?Vulliet C.?Emmelin J.-M.?ChovelonEmail author C.?Guillard J.-M.?Herrmann 《Environmental Chemistry Letters》2003,1(1):62-67
The photocatalytic degradation of a sulfonylurea herbicide, cinosulfuron, has been studied in TiO2 aqueous suspensions. A first order kinetic law was found. The influence of the initial concentration of cinosulfuron and
of the initial radiant flux on the kinetics were evaluated. The identification of the intermediate products was based on high
performance liquid chromatography coupled with mass spectrometry analyses (HPLC-MS). The mineralization of cinosulfuron was
traced using ion chromatography and total organic carbon (TOC) measurements. These results indicate that the photocatalytic
degradation of cinosulfuron leads to CO2, NO3
− and SO4
2− as final products, and in addition cyanuric acid (C3H3O3N3), confirming previous results on triazinic ring-containing compounds.
Electronic Publication 相似文献
46.
Saturated and unsaturated hydrocarbons in marine benthic algae 总被引:2,自引:0,他引:2
Saturated and olefinic hydrocarbons were determined in 24 species of green, brown and red benthic marine algae from the Cape Cod area (Massachusetts, USA). Among the saturated hydrocarbons, n-pentadecane predominates in the brown and n-heptadecane in the red algae. A C17 alkyleyclopropane has been identified tentatively in Ulvalactuca and Enteromorpha compressa, two species of green algae. Mono-and diolefinic C15 and C17 hydrocarbons are common. The structures of several new C17, C19 and C21 mono-to hexaolefins have been elucidated by gas chromatography, mass spectrometry and ozonolysis. In fruiting Ascophyllum nodosum, the polyunsaturated hydrocarbons carbons occur exclusively in the reproductive structures. The rest of the plant contains n-alkanes from C15 to C21. A link between the reproductive chemistry of benthic and planktonic algae and their olefin content is suggested. An intriguing speculation is based on Paffenhöfer's (1970) observation that the sex ratio of laboratory reared Calanus helgolandicus depends upon the species of algae fed to the nauplii. The percentage of males produced correlates with our analyses of heneicosahexaene in the algal food. Our analyses of the hydrocarbons in benthic marine algae from coastal environments should aid studies of the coastal food web and should enable us to distinguish between hydrocarbon pollutants and the natural hydrocarbon background in inshore waters.Contribution No. 2582 of the Woods Hole Oceanographic Institution; and Contribution No. 227, Systematics-Ecology Program. 相似文献
47.
An olefinic hydrocarbon (all-cis-3,6,9,12,15,18-heneicosahexaene, HEH)_was islated from marine planktonic plants and animals. Its structure was established by ultraviolet, infrared and mass spectrometry in combination with chemical techniques. The olefin occurs in many species of marine planktonic algae and is probably derived from the corresponding docosahexaenoic acid. Rhincalanus nasutus accumulates HEH nonselectively from its algal food together with the triglyceride lipids. Other, related copepods contain little or no HEH even when grown in cultures of algae that provide R. nasutus with that olefin. The presence of HEH in marine vertebrates suggests that, within the animal lipids, hydrocarbons are remarkably stable. This work has practical implications for studies of the marine food web and of marine pollution with persistent chemicals.Contribution No. 2485 of the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA. 相似文献
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