Permanganate oxidation of polycyclic aromatic compounds (PAHs and polar PACs): column experiments with DNAPL at residual saturation

Environmental Science and Pollution Research - Permanganate is an oxidant usually applied for in situ soil remediation due to its persistence underground. It has already shown great efficiency for...     

Elaboration of a Bio-Colored Material Based on Natural Dye and Polybutylene Succinate: Comparative Study with Colored Polylactic Acid

Journal of Polymers and the Environment - In the context of sustainable development and natural products valorization, new ecological materials enter a logic aimed at removing the causes of...     

New insight on population genetic connectivity of widespread amphidromous prawn Macrobrachium lar (Fabricius, 1798) (Crustacea: Decapoda: Palaemonidae)

Due to the sparse and unstable nature of insular freshwater habitats, marine larval dispersal of amphidromous species is considered a critical element of population persistence. We assessed population genetic structure of freshwater prawn Macrobrachium lar across its range that encompasses two biogeographic barriers: the vast open ocean separating Western and Central Pacific regions and the Indo-Malay archipelago separating Indian and Pacific oceans. A total of 173 samples collected from 21 islands throughout the Indo-Pacific were sequenced at 16S and 28S rDNA. We observed distinct genetic isolation of populations located at the eastern and southwestern edge of the species range but no evidence of an effect of the Indo-Pacific barrier. Differentiation patterns are consistent with a stepping-stone model of dispersal. Genetic differences of Central Pacific populations may reflect founder events associated with colonization of isolated islands, or be a signature of a past bottleneck after population depletion caused by drastic climatic events.     

Ecology of juvenile hawksbills (Eretmochelys imbricata) at Buck Island Reef National Monument, US Virgin Islands

Surveys of juvenile hawksbills around Buck Island Reef National Monument, US Virgin Islands from 1994 to 1999 revealed distributional patterns and resulted in a total of 75 individual hawksbill captures from all years; turtles ranged from 23.2 to 77.7 cm curved carapace length (CCL; mean 42.1 ± 12.3 cm SD). Juveniles concentrated where Zoanthid cover was highest. Length of time between recaptures, or presumed minimum site residency, ranged from 59 to 1,396 days (mean 620.8 ± 402.4 days SD). Growth rates for 23 juveniles ranged from 0.0 to 9.5 cm year^?1 (mean 4.1 ± 2.4 cm year^?1SD). Annual mean growth rates were non-monotonic, with the largest mean growth rate occurring in the 30–39 cm CCL size class. Gastric lavages indicated that Zoanthids were the primary food source for hawksbills. These results contribute to our understanding of juvenile hawksbill ecology and serve as a baseline for future studies or inventories of hawksbills in the Caribbean.     

Testing hypotheses in evolutionary ecology with imperfect detection: capture-recapture structural equation modeling

Studying evolutionary mechanisms in natural populations often requires testing multifactorial scenarios of causality involving direct and indirect relationships among individual and environmental variables. It is also essential to account for the imperfect detection of individuals to provide unbiased demographic parameter estimates. To cope with these issues, we developed a new approach combining structural equation models with capture-recapture models (CR-SEM) that allows the investigation of competing hypotheses about individual and environmental variability observed in demographic parameters. We employ Markov chain Monte Carlo sampling in a Bayesian framework to (1) estimate model parameters, (2) implement a model selection procedure to evaluate competing hypotheses about causal mechanisms, and (3) assess the fit of models to data using posterior predictive checks. We illustrate the value of our approach using two case studies on wild bird populations. We first show that CR-SEM can be useful to quantify the action of selection on a set of phenotypic traits with an analysis of selection gradients on morphological traits in Common Blackbirds (Turdus merula). In a second case study on Blue Tits (Cyanistes caeruleus), we illustrate the use of CR-SEM to study evolutionary trade-offs in the wild, while accounting for varying environmental conditions.     

Meta-ecosystem engineering: nutrient fluxes reveal intraspecific and interspecific feedbacks in fragmented mussel beds

Ecologists still have to elucidate the complex feedback interactions operating among biodiversity and ecosystem processes in engineered systems. To address this, a field experiment was conducted to mimic natural mussel bed meta-ecosystems (Mytilus spp.) of the lower St. Lawrence Estuary (Quebec, Canada) and partition the effects of their biotic and abiotic properties and spatial structure on ecosystem processes and community dynamics of associated macro-invertebrates. We found positive intraspecific feedbacks between mussels and their recruits, and negative interspecific feedbacks between mussels and their associated ecosystem. These feedbacks were associated with mussel bed ecosystem processes (fluxes of ammonium and oxygen). In addition, we showed that proximity between mussel patches increased within-patch nutrient fluxes. Our study revealed the potential for meta-ecosystem engineering to drive feedback interactions between community and ecosystem functioning in marine fragmented systems. It also shows the relevance of meta-ecosystem theories as a conceptual framework to elucidate biotic and abiotic processes controlling ecosystem and community structure. Such framework could contribute to ecosystem-based management of spatially structured systems such as reserve networks and fragmented ecosystems.     

Carbon leakage and capacity-based allocations: Is the EU right?

Competitiveness and carbon leakage are major concerns for the design of CO₂ emissions permits markets. In the absence of a global carbon tax and of border carbon adjustments, output-based allocation is a third-best solution and is actually implemented (Australia, California, New Zealand). The EU has followed a different route; free allowances are allocated to existing or new capacities in proportion to a benchmark, independent of actual production. This paper compares these two schemes in a formal setting and shows that the optimal one is in fact a combination of both schemes, or output-based allocation alone if uncertainty is limited. A key assumption of our analysis is that the short-term import pressure depends both on the existing capacities and the level of demand, which is typical in capital intensive and internationally traded sectors. A calibration of the model is used to discuss the EU scheme for the cement sector in the third phase of the EU-ETS (2013–2020). This allows for a quantification of various policies in terms of welfare, investment, production, company profits, public revenues and leakage.     

Prediction of pollutant dispersion in turbulent two-phase flows

With a growing awareness of water pollution problems, in recent years there has been a considerable increased effort in developing and applying numerical models to predict accurately the contaminant distributions, particularly in free surface flows. This numerical study presents a predictive hydrodynamic model in order to explore the dispersion phenomenon of a pollutant injected from time-dependent sources in a turbulent free surface flow. More precisely, we study the impact of pulsation on the dispersion of an injected material. The air/water interface was modeled with the volume of fluid method and sharpness of the free surface was assured by means of Geo-Reconstruct scheme. The numerical results showed that the pulsation played a dominant role at the early stage of the pollutant transport. It was also observed that the pulsation affected the distribution of the injected material especially near the front and that a major swirling action was developed compared to the constant-rate-injection case.     

Will Evolving Climate Conditions Increase the Risk of Floods of the Large U.S.‐Canada Transboundary Richelieu River Basin?

In spring 2011, an unprecedented flood hit the complex eastern United States (U.S.)–Canada transboundary Lake Champlain–Richelieu River (LCRR) Basin, destructing properties and inducing negative impacts on agriculture and fish habitats. The damages, covered by the Governments of Canada and the U.S., were estimated to C$90M. This natural disaster motivated the study of mitigation measures to prevent such disasters from reoccurring. When evaluating flood risks, long‐term evolving climate change should be taken into account to adopt mitigation measures that will remain relevant in the future. To assess the impacts of climate change on flood risks of the LCRR basin, three bias‐corrected multi‐resolution ensembles of climate projections for two greenhouse gas concentration scenarios were used to force a state‐of‐the‐art, high‐resolution, distributed hydrological model. The analysis of the hydrological simulations indicates that the 20‐year return period flood (corresponding to a medium flood) should decrease between 8% and 35% for the end of the 21st Century (2070–2099) time horizon and for the high‐emission scenario representative concentration pathway (RCP) 8.5. The reduction in flood risks is explained by a decrease in snow accumulation and an increase in evapotranspiration expected with the future warming of the region. Nevertheless, due to the large climate inter‐annual variability, short‐term flood probabilities should remain similar to those experienced in the recent past.     

Modelling radiative balance in a row-crop canopy: Row-soil surface net radiation partition

Row crops like vineyards undergo various and significant manipulations of training system and cultural practices, which strongly influence the quality of products. Variations of water vapour fluxes from the soil surface and the leaves in the row volume are closely linked to the ratio of energy available to each compartment. A physically realistic model of available energy partition between the rows and the soil surface is therefore a key factor towards optimization of such systems, and must be included in canopy models. A number of available models were not directly validated. The purpose of the study was therefore to design a model of net radiation partition and check it directly.The model of net radiation partition between rows (Rnv), considered as a whole, and intervening soil surface (Rns) of a row-crop canopy was developed from physically realistic yet simple assumptions:

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global solar (short wave) radiation partition was calculated by a previously validated geometric model;

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long-wave radiative fluxes between the soil surface, the rows and the atmosphere were calculated from the corresponding view factors, which only depended on canopy geometry;

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atmospheric radiation was estimated by a simple empirical relation based on air temperature as the only input variable;

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air temperature in the vicinity of leaves replaced leaf surface temperatures as a more convenient input variable, with little loss of information.

The input variables were incoming direct and diffuse solar radiation, soil surface mean temperature and air temperature near the leaves. The main parameters were soil and leaf albedos, row porosity and dimensions.A direct validation of the model was attempted by measuring net radiation above the canopy and at five positions above the soil surface in a vineyard of the Bordeaux area. The reliability of soil surface net radiation measurements was estimated by thorough error propagation analysis. When found significant, errors were corrected and finally soil surface net radiation data were corrected only for delay in direct downward solar radiation striking net radiometers, because canopy was discontinuous and height of net radiometers was not negligible compared to canopy height.In these conditions, model calculations were in agreement with measurements, although the model slightly underestimated Rns and therefore overestimated Rnv. As the mean error was about 20 W m⁻², and therefore compatible with instrument accuracy, the results were considered satisfactory.This available energy partition model is able to estimate radiative balance in various canopy systems and in various thermal environment conditions, leading to easier simulations of energy balance and water fluxes. It could therefore be a useful tool for optimizing row-crop canopies, taking fully into account any kind of present or future thermal environment.