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91.
Influences of Spatial Scale and Soil Permeability on Relationships Between Land Cover and Baseflow Stream Nutrient Concentrations 总被引:1,自引:0,他引:1
F. Bernard Daniel Michael B. Griffith Michael E. Troyer 《Environmental management》2010,45(2):336-350
The Little Miami River (LMR) basin, dominated by agriculture, contains two geologically-distinct regions; a glaciated northern
till plain with soils three times more permeable than a southern, pre-Wisconsinan drift plain. The influences of two landscape
measures, percent row crop cover (%RCC, computed at three spatial scales), and soil permeability (PERM), on baseflow nutrient
concentrations were modeled using linear regressions. Quarterly water samples collected for four years were analyzed for nitrate-N
(NN), Kjeldahl-N (KN), total-N (TN), and total-P (TP). In till plain streams (n = 17), NN concentrations were 8.5-times greater than drift plain streams (n = 18), but KN and TP were 20–40% lower at comparable %RCC. These differences resulted in TN/TP molar ratios >80 in till plain
streams, but <6 in drift plain streams. For till plain steams regression models based on %RCC accounted for 79% of the variance
in NN concentrations but only 27% in drift plain streams. However, regressions on %RCC accounted for 68–75% of the KN and
TP concentration variance in the drift plain streams but essentially none in the till plain. Catchment PERM influenced the
regional NN/KN ratios which were 10-fold higher in the drift plain streams. For both till and drift streams the catchment
scale %RCC gave the best predictions of NN, a water soluble anion, but the smaller spatial scales produced better models for
insoluble nutrient species (e.g., KN and TP). Published literature on Ohio streams indicates that these inter-regional differences
in nutrient ratios have potential implications for aquatic biota in the receiving streams. 相似文献
92.
93.
Mathilde Lefebvre Fabienne Dufernez Ange-Line Bruel Marie Gonzales Bernard Aral Judith Saint-Onge Nadège Gigot Julie Desir Caroline Daelemans Frédérique Jossic Sébastien Schmitt Raphaele Mangione Fanny Pelluard Catherine Vincent-Delorme Jean-Marc Labaune Nicole Bigi Dominique D'Olne Anne-Lise Delezoide Annick Toutain Sophie Blesson Valérie Cormier-Daire Julien Thevenon Salima El Chehadeh Alice Masurel-Paulet Nicole Joyé Claude Vibert-Guigue Luc Rigonnot Thierry Rousseau Pierre Vabres Philippe Hervé Antonin Lamazière Jean-Baptiste Rivière Laurence Faivre Nicole Laurent Christel Thauvin-Robinet 《黑龙江环境通报》2015,35(7):675-684
94.
In this paper, the occupational accidents and their effects on people are modeled. The basis of energy flow/barrier analysis is used to define an accident as the impact of a hazardous agent on a target, as a result of failure of control and protective barriers. This definition is enhanced to include serial and parallel barriers and to distinguish energy barriers from target barriers. The barrier attributes are defined and used to create a quantitative scenario-building model. The probability and severity of various accidents are estimated, by studying barrier reliability and efficiency. This approach is used to develop and simulate accident scenarios and to calculate their consequences. This model can be used in complex systems for analyzing the risk and estimating the importance of barriers. 相似文献
95.
M. V. Senat J. P. Bernard A. Delezoide P. Saugier-Veber Y. Hillion J. Roume Y. Ville 《黑龙江环境通报》2001,21(13):1129-1132
Hydrocephalus-stenosis of the acqueduct of Sylvius sequence (HSAS) is characterized by hydrocephalus, macrocephaly, adducted thumbs, spasticity, agenesis of the corpus callosum and mental retardation. X-linked hydrocephalus is known to be due to mutations in the gene coding for the neural cell adhesion molecule L1 (L1-CAM) and diagnosis is made by identification of a mutation in the L1-CAM gene. Prenatal diagnosis of HSAS is usually suggested on ultrasound examination showing hydrocephalus in a male fetus associated with bilateral adducted thumbs. Mutation screening of the L1-CAM gene is indicated when neuropathological examination shows hypoplasia of the corticospinal tract associated with aqueductal stenosis. We report here two cases of HSAS diagnosed within the same family by ultrasound examination in the first trimester of pregnancy when bilateral adducted thumbs were the only early ultrasound marker. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
96.
Ning Liu Jatin Kal Shirong Liu Vanessa Haver Bernard Dell Keith R.J. Smettem Richard J. Harper 《环境科学学报(英文版)》2020,32(4):262-274
Increasing atmospheric CO2 is both leading to climate change and providing a potential fertilisation effect on plant growth. However, southern Australia has also experienced a significant decline in rainfall over the last 30 years, resulting in increased vegetative water stress. To better understand the dynamics and responses of Australian forest ecosystems to drought and elevated CO2, the magnitude and trend in water use efficiency (WUE) of forests, and their response to drought and elevated CO2 from 1982 to 2014 were analysed, using the best available model estimates constrained by observed fluxes from simulations with fixed and time-varying CO2. The ratio of gross primary productivity (GPP) to evapotranspiration (ET) (WUEe) was used to identify the ecosystem scale WUE, while the ratio of GPP to transpiration (Tr) (WUEc) was used as a measure of canopy scale WUE. WUE increased significantly in northern Australia (p < 0.001) for woody savannas (WSA), whereas there was a slight decline in the WUE of evergreen broadleaf forests (EBF) in the southeast and southwest of Australia. The lag of WUEc to drought was consistent and relatively short and stable between biomes (≤3 months), but notably varied for WUEe, with a long time-lag (mean of 10 months). The dissimilar responses of WUEe and WUEc to climate change for different geographical areas result from the different proportion of Tr in ET. CO2 fertilization and a wetter climate enhanced WUE in northern Australia, whereas drought offset the CO2 fertilization effect in southern Australia. 相似文献
97.
98.
99.
Mathieu B. Hounsou Bernard Ahamide Euloge K. Agbossou Thomas Gaiser 《The Environmentalist》2011,31(4):407-415
Water is an essential element for humankind, animals, and plants. It is also an important element of the aquatic environment
(the natural habitat of multiple species), where its quality plays a determining role in their protection and conservation.
Unfortunately, the water quality of natural environments has worsened in the last decades. In sub-Saharan Africa and particularly
in Bénin, in contrast to river discharges, monitoring the quality of surface water is a very rare activity. Thus, knowledge
about physical and chemical properties as a basis for evaluation of the state of the environment and protection measures needed
is almost absent. This article presents the results of the first structured, regular monitoring campaign on surface waters
in the whole basin of the Ouémé River in Bénin Republic. With 510 km, the Ouémé River’s water quality fluctuates from upstream
(Taneka Koko mountains in the north) to downstream (gauging station Bonou in the south) sources. This is due to soil erosion,
lack of water treatment plants, and the use of significant quantities of fertilizer in the cotton zone. The present research
was initiated to study the resource degradation of this area through chemical and physical water analysis. The monitoring
of water quality has been followed for 5 years on twenty physicochemical parameters, from samples taken at four gauging stations
on the main channel of the Ouémé River. Means and standard deviations of water analysis results were compared to both the
recommendations of the World Health Organization (WHO) and the Maximum Permissible Concentrations (MPC) for drinking water
(WHO 1987). Thus, high values were observed for physical parameters, i.e., color and turbidity had peaks of 697.5 uC and 129 FTU at
Bétérou station in the wet season, although certain parameters, such as total hardness, present low values compared to the
recommended standards. Moreover, excluding the concentrations of NO2
− and NH4
+ with values above the MPC, nutrient concentrations posed no direct risk for human consumption. However, together with phosphate
concentrations (which are up to ten times higher than permissible ecological thresholds), they can cause eutrophication of
the aquatic ecosystem. Due to the current flow regime, which has very low discharge rates in the dry season and torrential
rainfall and high sediment loads in the wet season, the risk of eutrophication, i.e., excessive concentrations of ammonium
and phosphates, is present throughout the year. Accumulation of ammonium and the distribution of nitrate and nitrites in the
river water suggest that nitrification is impeded due to a lack of oxygen in both dry and wet seasons. Finally, the investigations
show that the risk of water pollution exists and it is necessary to take measures of sanitation and water treatment to prevent
the further degradation of water along the Ouémé River. 相似文献
100.
Exploratory study of suspended sediment concentrations downstream of harvested peat bogs 总被引:1,自引:0,他引:1
Pavey B Saint-Hilaire A Courtenay S Ouarda T Bobée B 《Environmental monitoring and assessment》2007,135(1-3):369-382
Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage
water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were
found in the drainage water at one particular site during the 2001–2002 spring seasons in New Brunswick (Canada). The main
objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with
those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment
concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick
during the ice free seasons of 2003–2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended
daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested
sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest
SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused
by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline
should be reviewed. 相似文献