The Benefits of Cooperation Under Uncertainty: the Case of Climate Change

This article presents an analysis of the behaviour of countries defining their climate policies in an uncertain context. The analysis is made using the S-CWS model, a stochastic version of an integrated assessment growth model. The model includes a stochastic definition of the climate sensitivity parameter. We show that the impact of uncertainty on policy design critically depends on the shape of the damage function. We also examine the benefits of cooperation in the context of uncertainty: We highlight the existence of an additional benefit of cooperation, namely risk reduction.     

Do herbicide treatments reduce the sensitivity of mosquito larvae to insecticides?

Invasive mosquitoes are economic and sanitary concerns especially in Europe and America. Most work has emphasized the role of resistance [Berrada, S., Fournier, D., Cuany, A., Nguyen, T.X., 1994. Identification of resistance mechanisms in a selected laboratory strain of Cacopsylla pyri (Homoptera: Psyllidae): altered acetylcholinesterases and detoxifying oxidases. Pesticide Biochemistry and Physiology 48, 41-47; Hemingway, J., Hawkes, N.J., McCarroll, L., Ranson, H., 2004. The molecular basis of insecticide resistance in mosquitoes. Insect Biochemistry and Molecular Biology 34, 653-665] to insecticides. Compounds acting on larval sensitivity to insecticides are not well studied and their action remains poorly understood. Among several residual chemicals in ecosystems, particularly in wetlands, we identified a possible interaction of an herbicide on larval resistance to an insecticide. Our work contributes to the global control of mosquito populations by identifying possible pathways of resistance to insecticides of these vectors. Resistance or tolerance to insecticide treatments might contribute to successful invasion by mosquitoes. Here we report an ecotoxicological approach to test the hypothesis of an indirect effect of atrazine on mortality of an invasive vector. A brief contact (48h) between Aedes aegypti mosquito larvae and atrazine led to a modification of larval sensitivity to an insecticide: using atrazine as an inducer led to a decrease in the mortality of larvae treated with Bacillus thuringiensis var. israelensis (Bti).     

Norovirus and Other Human Enteric Viruses in Moroccan Shellfish

The aim of this study was to evaluate the presence of human enteric viruses in shellfish collected along the Mediterranean Sea and Atlantic Coast of Morocco. A total of 77 samples were collected from areas potentially contaminated by human sewage. Noroviruses were detected in 30 % of samples, with an equal representation of GI and GII strains, but were much more frequently found in cockles or clams than in oysters. The method used, including extraction efficiency controls, allowed the quantification of virus concentration. As in previous reports, results showed levels of contamination between 100 and 1,000 copies/g of digestive tissues. Sapoviruses were detected in 13 % of samples mainly in oyster and clam samples. Hepatitis A virus was detected in two samples, with concentrations around 100 RNA copies/g of digestive tissues. Only two samples were contaminated with enterovirus and none with norovirus GIV or Aichi virus. This study highlights the interest of studying shellfish samples from different countries and different production areas. A better knowledge of shellfish contamination helps us to understand virus levels in shellfish and to improve shellfish safety, thus protecting consumers.     

Late Devonian (Frasnian) phyllopod and phyllocarid crustacean shields from Belgium reinterpreted as ammonoid anaptychi

The taxonomic affinities of fossils from the Frasnian succession of Belgium previously described as phyllopod and phyllocarid crustacean shields are discussed. The rediscovery of the holotype of Ellipsocaris dewalquei, the type species of the genus Ellipsocaris Woodward in Dewalque, 1882, allows to end the discussion on the taxonomic assignation of the genus Ellipsocaris. It is removed from the phyllopod crustaceans as interpreted originally and considered here as an ammonoid anaptychus. Furthermore, it is considered to be a junior synonym of the genus Sidetes Giebel, 1847. Similarly, Van Straelen’s (1933) lower to middle Frasnian record Spathiocaris chagrinensis Ruedemann, 1916, is also an ammonoid anaptychus. Although ammonoids can be relatively frequent in some Frasnian horizons of Belgium, anaptychi remain particularly scarce and the attribution to the present material to peculiar ammonoid species is not possible.     

Human bioaccessibility of Cr, Cu, Ni, Pb and Zn in urban soils from the city of Torino, Italy

Several physiologically based extraction procedures have been proposed to estimate the fraction of the potentially toxic element content that would be bioaccessible in the human gastro-intestinal tract following accidental ingestion of soil. Many of these procedures are complex, they have been applied to a very limited range of soils, and most work has focussed on arsenic and lead. In the present study, a simplified, two-stage extraction, simulating the human stomach and intestine, was developed and applied to urban soil samples from ten public-access areas in the City of Torino, Italy. The human oral bioaccessibility of chromium, copper, nickel, lead and zinc was estimated. Lead and zinc bioaccessibilities were found to be higher in the stomach, but chromium was more bioaccessible in the intestine. Analyte concentrations were higher in roadside soils than in soils from parks. A higher proportion of the soil metal content was found in bioaccessible forms at roadsides than in parks. Comparison of the current findings with results of earlier work involving sequential extraction of the same soils indicated that the sequential procedure gave a relative, but not an absolute, indication of bioaccessibility. Calculations based on the bioaccessible analyte concentrations suggest that ingestion of only 2–3 g of some of the roadside soil samples from Torino could deliver the tolerable daily oral intake of chromium, nickel and lead to a 20-kg child. The developed procedure is useful for preliminary screening of soils and prediction of whether their bioaccessible metal contents are likely to pose a risk to human health.     

Development of an in vitro method to estimate lung bioaccessibility of metals from atmospheric particles

The research presented here was initiated to improve the current knowledge on easily released metals from atmospheric particles. The objectives of this paper were to develop an in vitro method to estimate lung bioaccessibility and to provide quantitative data on metals bioaccessibility. A large set of metals has been investigated (Ba, Cd, Ce, Co, Cu, La, Mn, Mo, Ni, Pb, Rb, Sb and Zn) using two distinct fluids (water and Gamble solution) on four reference materials representing different types of particle sources. Through this study, different parameters such as extraction-time, composition of the leaching solution and solid-to-liquid (S/L) ratios were investigated. The findings obtained for four SRMs suggest that the bioaccessibility is maximized after a 24 h extraction for a range of S/L ratios varying from 1/500 to 1/50,000. We clearly demonstrate that the higher bioaccessibility of metals is obtained with the Gamble solution. Moreover, our results imply that bioaccessibility is speciation and element dependent with percentages varying from 3.3% for Pb to 92.5% for Zn. An estimation of uncertainties of 11% to 30% was obtained for metals bioaccessibility in the four reference materials. In addition, the extraction procedure was validated by performing a mass balance on both soluble and insoluble fractions. This developed method may be used to evaluate the pulmonary bioaccessibility of trace elements present in the atmospheric particles without major artefacts.     

Effects of meteorological conditions and topography on the bioaccumulation of PAHs and metal elements by native lichen (Xanthoria parietina)

The bioaccumulation of PAHs and metal elements in the indigenous lichens Xanthoria parietina was monitored during two years at a quarterly frequency, in 3 sites of contrasted anthropic influence. The impact of the meteorological factors (temperature, relative humidity, rainfall, wind speed) was first estimated through principal component analysis, and then by stepwise multilinear regressions to include wind directions. The pollutants levels reflected the proximity of atmospheric emissions, in particular from a large industrial harbor. High humidity and mild temperatures, and in a lower extent low wind speed and rainfall, also favored higher concentration levels. The contributions of these meteorological aspects became minor when including wind direction, especially when approaching major emission sources. The bioaccumulation integration time towards meteorological variations was on a seasonal basis (1–2 months) but the wind direction and thus local emissions also relied on a longer time scale (12 months). This showed that the contribution of meteorological conditions may be prevalent in remote places, while secondary in polluted areas, and should be definitely taken into account regarding long-term lichen biomonitoring and inter-annual comparisons. In the same time, a quadruple sampling in each site revealed a high homogeneity among supporting tree species and topography. The resulting uncertainty, including sampling, preparation and analysis was below 30% when comfortable analytical conditions were achieved. Finally, the occurrence of unexpected events such as a major forest fire, permitted to evaluate that this type of short, although intense, events did not have a strong influence on PAH and metals bioaccumulation by lichen.     

Speciation of mercury in South African coals

Total mercury (Hg_TOT) concentrations were determined by inductively coupled plasma mass spectrometry (ICP MS) for South African Highveld coals. The distribution of Hg in coals was investigated using a four-stage sequential leaching protocol and isotope dilution/gas chromatography coupled to ICP MS (ID-GC-ICP MS). The results show that Hg_TOT ranged from 144 to 303?µg?kg^?1 with a mean of 199?±?26?µg?kg^?1, while Hg_TOT leached from coals using different solvents ranged between 103 and 310?µg?kg^?1 (mean: 218?±?60?µg?kg^?1). Hg leaching rates of 53–78% were achieved in crushed coals. Hg⁰, Hg²⁺, and CH₃Hg⁺ were identified in all coals. CH₃Hg⁺ in studied coals ranged between 0.1 and 0.4 (mean: 0.2) µg?kg^?1. GC ICP MS chromatograms also showed unknown Hg peaks which were identified as other organomercury species such as ethylmercury. Modes of occurrence of Hg in coals were variable with the organic-bound (37–40%) and the sulfide-bound (37–39%) being the dominant mercury forms. Increasing the HCl concentration in the used protocol increased the amount of Hg leached (16%) during this step.     

Use of a physiologically based extraction test to estimate the human bioaccessibility of potentially toxic elements in urban soils from the city of Glasgow,UK

A simple, two-stage, physiologically based extraction has been applied to assess the human bioaccessibility of potentially toxic elements (PTE) in 20 urban soils from a major UK city. Chromium and iron bioaccessibilities were found to be markedly higher in the intestinal phase, whilst lead and zinc bioaccessibilities were higher in the stomach. Copper and manganese bioaccessibilities were generally similar under both extraction conditions. Principal component analysis was used to study relationships amongst bioaccessible element concentrations and land use. Distinctions could be observed between the distributions of the urban metals—copper, lead and zinc—and metals predominantly of geogenic origin, such as iron. There was no clear delineation between roadside soils and soils obtained from public parks. Bioaccessible analyte concentrations were found to be correlated with pseudototal (aqua regia soluble) analyte concentrations for all elements except iron. Results of the BCR sequential extraction did not, in general, provide a good indication of human bioaccessibility. Comparison of bioaccessible PTE concentrations with toxicological data indicated that lead is the element of greatest concern in these soils but that levels are unlikely to pose a health risk to children with average soil intake.     

RASTER-BASED HYDROLOGIC MODELING OF SPATIALLY-VARIED SURFACE RUNOFF1

ABSTRACT: The proliferation of watershed databases in raster Geographic Information System (GIS) format and the availability of radar-estimated rainfall data foster rapid developments in raster-based surface runoff simulations. The two-dimensional physically-based rainfall-runoff model CASC2D simulates spatially-varied surface runoff while fully utilizing raster GIS and radar-rainfall data. The model uses the Green and Ampt infiltration method, and the diffusive wave formulation for overland and channel flow routing enables overbank flow storage and routing. CASC2D offers unique color capabilities to display the spatio-temporal variability of rainfall, cumulative infiltrated depth, and surface water depth as thunderstorms unfold. The model has been calibrated and independently verified to provide accurate simulations of catchment response to moving rainstorms on watersheds with spatially-varied infiltration. The model can accurately simulate surface runoff from flashfloods caused by intense thunderstorms moving across partial areas of a watershed.