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71.
PROBLEM: Road accident outcomes are traditionally analyzed at state or road network level due to a lack of aggregated data and suitable analytical methods. The aim of this paper is to demonstrate usefulness of a simple spatiotemporal modeling of road accident outcomes at small-scale geographical level. METHOD: Small-area spatiotemporal Bayesian models commonly used in epidemiological studies reveal the existence of spatial correlation in accident data and provide a mechanism to quantify its effect. The models were run for Belgium data for the period 2000-2005. Two different scale levels and two different exposure variables were considered under Bayesian hierarchical models of annual accident and fatal injury counts. The use of the conditional autoregressive (CAR) formulation of area specific relative risk and trend terms leads to more distinctive patterns of risk and its evolution. The Pearson correlation tests for relative risk rates and temporal trends allows researchers to determine the development of risk disparities in time. RESULTS: Analysis of spatial effects allowed the identification of clusters with similar risk outcomes pointing toward spatial structure in road accident outcomes and their background mechanisms. From the analysis of temporal trends, different developments in road accident and fatality rates in the three federated regions of Belgium came into light. Increasing spatial disparities in terms of fatal injury risk and decreasing spatial disparities in terms of accident risk with time were further identified. IMPACT ON INDUSTRY: The application of a space-time model to accident and fatal injury counts at a small-scale level in Belgium allowed identification of several areas with outstandingly high accident (injury) records. This could allow more efficient redistribution of resources and more efficient road safety management in Belgium. 相似文献
72.
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
73.
Pascaline Le Gouar Alexandre Robert Jean-Pierre Choisy Sylvain Henriquet Philippe Lecuyer Christian Tessier Fran?ois Sarrazin 《Ecological applications》2008,18(4):859-872
The success of reintroduction programs greatly depends on the amount of mortality and dispersal of the released individuals. Although local environmental pressures are likely to play an important role in these processes, they have rarely been investigated because of the lack of spatial replicates of reintroduction. In the present study, we analyzed a 25-year data set encompassing 272 individuals released in five reintroduction programs of Griffon Vultures (Gyps fulvus) in France to examine the respective roles of survival and dispersal in program successes and failures. We use recent developments in multi-strata capture-recapture models to take into account tag loss in survival estimates and to consider and estimate dispersal among release areas. We also examined the effects of sex, age, time, area, and release status on survival, and we tested whether dispersal patterns among release areas were consistent with habitat selection theories. Results indicated that the survival of released adults was reduced during the first year after release, with no difference between sexes. Taking into account local observations only, we found that early survival rates varied across sites. However when we distinguished dispersal from mortality, early survival rates became equal across release sites. It thus appears that among reintroduction programs difference in failure and success was due to differential dispersal among release sites. We revealed asymmetrical patterns of dispersal due to conspecific attraction: dispersers selected the closest and the largest population. We showed that mortality can be homogeneous from one program to another while, on the contrary, dispersal is highly dependent on the matrix of established populations. Dispersal behavior is thus of major interest for metapopulation restoration and should be taken into account in planning reintroduction designs. 相似文献
74.
Skraber Sylvain Gantzer Christophe Helmi Karim Hoffmann Lucien Cauchie Henry-Michel 《Food and environmental virology》2009,1(2):66-76
A filtration system, based on tangential flow filtration (TFF) followed by ultracentrifugation was developed in order to concentrate
simultaneously viruses and parasites from large volumes of water. For TFF, no pre-treatment of the membrane is performed but
a post-rinsing step using high pH-beef extract-based eluant. Applying our protocol to 20 l of surface waters spiked with vaccinal
poliovirus-1, ϕX174 and MS2 bacteriophages resulted in an averaged viral recovery of 75% by TFF and 91% by ultracentrifugation
(total viral recovery of 70%). Our protocol was further applied to 31 environmental samples including surface, ground and
drinking waters from the Grand Duchy of Luxembourg in order to assess the occurrence of protozoan parasites (Cryptosporidium parvum and Giardia lamblia (oo)cysts), pathogenic viruses (enterovirus, norovirus and adenovirus) and infectious bacteriophages (somatic coliphages
and F-specific phages) in these samples. High viral recovery rates of > 70% were confirmed concentrating environmental strains
of somatic and F-specific coliphages from non-spiked surface waters. Parasites and enteric viruses were detected in 86 and
40% of the surface waters used for drinking water production, respectively. Infectious bacteriophages were isolated from all
surface waters and in two out of seven (29%) groundwaters revealing a susceptibility of the corresponding wells to viral pollution.
TFF-based method proved to be efficient for surveying the occurrence of non-bacterial pathogens such as enteric viruses and
protozoan parasites in large volumes of environmental waters. 相似文献
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76.
Bouchet S Tessier E Monperrus M Bridou R Clavier J Thouzeau G Amouroux D 《Journal of environmental monitoring : JEM》2011,13(5):1351-1359
The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment-water, sediment-atmosphere and water-atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment-water and the sediment-atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water-atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment-water interface ranged from -5.0 to 5.1 ng m(-2) h(-1) and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment-atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between -78 and 40 ng m(-2) h(-1) and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m(-2) h(-1). The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in such tidal environments exhibiting background contamination level. 相似文献
77.
Sylvain Gambert 《Local Environment》2013,18(5):467-480
The paper explores the role local governments and territorial proximity play in the efficiency of collaborative environmental governance. It develops the hypothesis that the representatives of local authorities involved in partnerships possess resources to diminish the pitfalls of sustainable governance, facilitate coordination, and contribute to the success of shared policy-making. Four French and English partnerships are presented. They include a diversity of stakeholders such as fisheries, ports, farmers, yachting associations, environmental NGOs, or local authorities. Thereby, the paper develops whether and under which conditions local governments play a positive or negative role, as well as comparing territorial levels of implementation and the effects of geographical proximity. It is shown that collaboration at the regional level prevents the integration of decision-making in organisational networks, the inclusion of citizens, and the development of social responsibility for stakeholders – the partnership acting as a formalisation of pre-existing lobbying. Locally, governments assume inter-organisational leadership and do contribute to the institutionalisation of the new forums. Yet, local successes of partnerships answer logics of social, rather than environmental, regulation. The local attenuation of usage conflicts does not necessarily reduce the negative effects of those usages on the environment. By stressing a collaborative definition of environmental problems, the partnerships tend to sideline substantial policy changes, and possibly conflict with the goals and long-term temporality of sustainable governance. 相似文献
78.
Lori H. Schwacke Tiago A. Marques Len Thomas Cormac G. Booth Brian C. Balmer Ashley Barratclough Kathleen Colegrove Sylvain De Guise Lance P. Garrison Forrest M. Gomez Jeanine S. Morey Keith D. Mullin Brian M. Quigley Patricia E. Rosel Teresa K. Rowles Ryan Takeshita Forrest I. Townsend Todd R. Speakman Randall S. Wells Eric S. Zolman Cynthia R. Smith 《Conservation biology》2022,36(4):e13878
The 2010 Deepwater Horizon (DWH) oil spill exposed common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, Louisiana to heavy oiling that caused increased mortality and chronic disease and impaired reproduction in surviving dolphins. We conducted photographic surveys and veterinary assessments in the decade following the spill. We assigned a prognostic score (good, fair, guarded, poor, or grave) for each dolphin to provide a single integrated indicator of overall health, and we examined temporal trends in prognostic scores. We used expert elicitation to quantify the implications of trends for the proportion of the dolphins that would recover within their lifetime. We integrated expert elicitation, along with other new information, in a population dynamics model to predict the effects of observed health trends on demography. We compared the resulting population trajectory with that predicted under baseline (no spill) conditions. Disease conditions persisted and have recently worsened in dolphins that were presumably exposed to DWH oil: 78% of those assessed in 2018 had a guarded, poor, or grave prognosis. Dolphins born after the spill were in better health. We estimated that the population declined by 45% (95% CI 14–74) relative to baseline and will take 35 years (95% CI 18–67) to recover to 95% of baseline numbers. The sum of annual differences between baseline and injured population sizes (i.e., the lost cetacean years) was 30,993 (95% CI 6607–94,148). The population is currently at a minimum point in its recovery trajectory and is vulnerable to emerging threats, including planned ecosystem restoration efforts that are likely to be detrimental to the dolphins’ survival. Our modeling framework demonstrates an approach for integrating different sources and types of data, highlights the utility of expert elicitation for indeterminable input parameters, and emphasizes the importance of considering and monitoring long-term health of long-lived species subject to environmental disasters. Article impact statement: Oil spills can have long-term consequences for the health of long-lived species; thus, effective restoration and monitoring are needed. 相似文献
79.
Höhener Patrick Guers Delphine Malleret Laure Boukaroum Ouassim Martin-Laurent Fabrice Masbou Jérémy Payraudeau Sylvain Imfeld Gwenaël 《Environmental Chemistry Letters》2022,20(6):3927-3942
Environmental Chemistry Letters - The transfer of pesticides from agricultural soils to food and drinking water is a major health issue. There are actually few robust methods to identify,... 相似文献