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881.
882.
Michael Schagerl Ina Bloch David G. Angeler Christian Fesl 《Environmental monitoring and assessment》2010,165(1-4):283-293
Artificially created ponds in urban areas may be important biodiversity refugia and may provide recreational services for populations. In order to obtain information on the seasonal development of the environmental conditions, water quality was determined in ten clay-pit ponds situated in the Austrian capital, Vienna. These ponds show high electrical conductivity (up to 3,000 μS cm???1), indicating elevated levels of salinity, which can be attributed to the geological setting of the underground. Furthermore, the ponds experience a gradient from low to high human pressure resulting from recreational activities (swimming, fishing, urbanisation of the pond boundaries). Results obtained from multivariate statistics methods suggest that ponds were mainly structured by salinity and by algal biomass, which can be attributed to resource supply related with eutrophication. According to their water chemistry, the ponds were classified as meso- to hypereutrophic. Stoichiometric N/P ratios suggest that phytoplankton productivity in hypereutrophic ponds is nitrogen limited, whilst algae in ponds with lower trophic levels experience growth imitation by phosphorus depletion. We eventually related environmental conditions to algal species occurrences and developed a model for algal assemblages indicating the particular trophic state at different seasons. 相似文献
883.
Christian A. Vossler James Espey W. Douglass Shaw 《Journal of the American Water Resources Association》1998,34(5):1213-1220
ABSTRACT: In this paper we examine the possible reasons why individuals who live in homes facing a flat monthly rate for water accept or reject an offer to have water metering devices installed at no cost to them. A logit model is used to model the discrete choice of acceptance. Since the demand for metering is directly tied to water demand, we estimate demand models for unmetered households in the Reno/Sparks metropolitan area using contingent data obtained by presenting households with hypothetical prices they might encounter under a metering system. Conditional logit and demand models are then used to examine the potential for metering to promote water conservation in the arid Reno/Sparks, Nevada metropolitan area. 相似文献
884.
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886.
Oxidative stress—an imbalance between reactive pro- and neutralising antioxidants—damages cell structures and impairs fitness-relevant traits such as longevity and reproduction. Theory predicts that feeding on diets with high antioxidant content such as fruits should reduce oxidative stress; however, there is no support of this idea in free-ranging mammals. Bats cover a large variety of ecological niches, and therefore, we asked if measures of oxidative stress are lower in species with fruit diets. We measured reactive oxygen metabolites (ROM) representing total pro-oxidants produced and antioxidants in the plasma of 33 Neotropical bat species. Species with a fruit diet showed the lowest level of ROM and the highest concentration of antioxidants, followed by omnivorous and animalivorous species. Potentially, frugivorous species ingest more antioxidants with food and thus are able to neutralise more pro-oxidants than species not feeding on fruits, resulting in an overall lower level of oxidative stress. We therefore showed for the first time that measures of oxidative stress vary according to diets in free-ranging mammals. 相似文献
887.
Laturnus Frank von Arnold Karin Grn Christian 《Environmental science and pollution research international》2007,14(1):53-60
Goal, Scope and Background Sewage sludge produced in wastewater treatment contains large amounts of organic matter and nutrients and could, therefore,
be suitable as fertiliser. However, with the sludge, besides heavy metals and pathogenic bacteria, a variety of organic contaminants
can be added to agricultural fields. Whether the organic contaminants from the sludge can have adverse effects on human health
and wildlife if these compounds enter the food chain or groundwater still remains a point of controversial discussion.
Main Features This paper presents an overview on the present situation in Europe and a summary of some recent results on the possible uptake
of organic contaminants by crops after addition to agricultural fields by sewage sludge.
Results Greenhouse experiments and field trials were performed to study the degradation and uptake of organic micro-contaminants in
sludge-amended agricultural soil in crops, such as barley and carrots grown in agricultural soil amended with anaerobically-treated
sewage sludge from a wastewater treatment plant, but studies hitherto have revealed no immediate risks. Common sludge contaminants
such as linear alkylbenzene sulphonates (LAS), nonylphenol ethoxylates (NPE), polycyclic aromatic hydrocarbons (PAH), bis(diethylhexyl)
phthalate (DEHP), showed neither accumulation in soil nor uptake in plants.
Discussion It is assumed that the annual amount of sewage sludge produced in Europe will increase in the future, mainly due to larger
amounts of high quality drinking water needed by an increasing population and due to increasing demands for cleaner sewage
water. Application of sewage sludge to agricultural soils is sustainable and economical due to nutrient cycling and disposal
of sewage sludge. However, this solution also involves risks with respect to the occurrence of organic contaminants and other
potentially harmful contents such as pathogens and heavy metals present in the sludge. There have been concerns that organic
contaminants may accumulate in the soil, be taken up by plants and thereby transferred to humans via the food chain. Results
obtained so far revealed, however, no immediate risk of accumulation of common organic sludge contaminants in soil or uptake
in plants when applying sewage sludge to agricultural soil. With very high dosages of sewage sludge, there may be a risk for
accumulation of very apolar contaminants, such as DEHP, to the soil.
Conclusions Any conclusions on the safe use of sewage sludge in agriculture have to be drawn carefully, as the studies performed until
now have been limited. Further studies are required, and before final statements can be drawn, it is imminent to study a larger
variety of common crops and the effect sewage sludge application may have on a possible accumulation of organic contaminants
in the crops. Furthermore, a larger variety of organic contaminants need to be studied and special focus should be given to
contaminants newly introduced into the environment. Besides investigating possible plant uptake of organic contaminants, the
fate of these compounds in soil after sludge application need to be monitored too. Here, special attention has to begiven
to studies on degradation and the formation of degradation products, to weathering and to leaching effects on groundwater,
to the application of different crops on the same field (crop rotation), to the use of full-width tillage and strip tillage,
and to long term application of sewage sludge on the soil.
Recommendations and Perspectives There are environmental, political as well as economical incentives to increase the agricultural application of sludge. However,
such usage should be performed with care as there are also ways in which sludge fertilisation could harm the environment and
human health. Recently, a new European COST Action (859) has been established covering the field of food safety and improved
food quality. Part of the Action is dealing with the application of sewage sludge in agriculture. Before any political and
economical measures can be taken, the pros and cons have to be sufficiently investigated on a scientific level first.
ESS-Submission Editor: Prof. Elena Maestri (elena.maestri@unipr.it) 相似文献
888.
889.
Christian Sens Petra Scheidemann Andreas Klunk Dietrich Werner 《Environmental science and pollution research international》1998,5(4):202-208
14C-TNT was used to quantify the uptake rate and metabolic turnover of TNT inPhaseolus vulgaris. Seventeen plants were analysed by a special cell fractionation method with polar and nonpolar solvents and enzymes. We obtained
three cytoplasmic fractions and five cell wall derived fractions. The recovery rate was 72% as measured by liquid scintillation
counting.14C partitioned almost in equal amounts with approximately 50% in the cytoplasm and in the cell wall. The majority of the TNT-metabolites
are present in the cytoplasm as was shown by GC/ ECD and thin layer chromatography. The14C in the cell wall is bound probably resulting in long-term immobilisation of these metabolites. We conclude that plants may
also be a model for nitroaromatic turnover and immobilisation in soil components. 相似文献
890.
A two-dimensional simulation model of phosphorus uptake including crop growth and P-response 总被引:2,自引:0,他引:2
Alain Mollier Peter De Willigen Marius Heinen Christian Morel Andr Schneider Sylvain Pellerin 《Ecological modelling》2008,210(4):453-464
Modelling nutrient uptake by crops implies considering and integrating the processes controlling the soil nutrient supply, the uptake by the root system and relationships between the crop growth response and the amount of nutrient absorbed. We developed a model that integrates both dynamics of maize growth and phosphorus (P) uptake. The crop part of the model was derived from Monteith's model. A complete regulation of P-uptake by the roots according to crop P-demand and soil P-supply was assumed. The soil P-supply to the roots was calculated using a diffusion equation and assuming that roots behave as zero-sinks. The actual P-uptake and crop growth were calculated at each time step by comparing phosphate and carbohydrate supply–demand ratios. Model calculations for P-uptake and crop growth were compared to field measurements on a long term P-fertilization trial. Three P-fertilization regimes (no P-fertilization, 42.8 kg P ha−1 year−1 and 94.3 kg P ha−1 year−1) have led to a range of P-supply. Our model correctly simulated both the crop development and growth for all P-treatments. P-uptake was correctly predicted for the two non-limiting P-treatments. Nevertheless, for the limiting P-treatment, P-uptake was correctly predicted during the early period of growth but it was underestimated at the last sampling date (61 day after sowing). Several arguments for under-prediction were considered. However, most of them cannot explain the observed magnitude in discrepancy. The most likely reason might be the fact that biomass allocation between shoot and root must be modelled more precisely. Despite this mismatch, the model appears to provide realistic simulations of the soil–plant dynamic of P in field conditions. 相似文献