Sorption of basic and acid dyes from aqueous solutions onto oxihumolite

Naturally occurring kind of weathered and oxidised young brown coal called oxihumolite was used for an adsorptive removal of basic (Methylene Blue, Malachite Green) as well as acid (Egacid Orange, Midlon Black) dyes from waters. It was shown that both kinds of dyes can be sorbed onto oxihumolite. The maximum sorption capacities determined from the parameters of Langmuir isotherms ranged from 0.070 mmol g-1 (for Midlon Black) to 0.278 mmol g-1 (for Malachite Green) and did not differ significantly for basic and acid dyes. The dye sorption (except of Midlon Black) increased in the presence of inorganic salt. Non-ionic surfactants, and surfactants bearing the same charge as the dye exhibited only a minor effect on the dye sorption, whereas oppositely charged surfactants enhanced the dye sorption to a certain extent. The pH value of the aqueous phase exhibited rather pronounced effect on the sorption of acid dyes causing a suppression of the sorption with increasing pH. The sorption of basic dyes, on the other hand, remained almost unchanged in the examined pH range. Oxihumolite is recommended for the treatment of acid wastewaters because of its limited stability in alkaline aqueous solutions.     

The Food Debate: Ethical versus Substantial Equivalence

Substantial equivalence (SE) has beenintroduced to assess novel foods, includinggenetically modified (GM) food, by means ofcomparison with traditional food. Besides anumber of objections concerning its scientificvalidity for risk assessment, the maindifficulty with SE is that it implies that foodcan be qualified on a purely substantial basis.SE embodies the assumption that only reductivescientific arguments are legitimate fordecision-making in public policy due to theemphasis on legal issues. However, the surge ofthe food debate clearly shows that thistechnocratic model is not accepted anymore.Food is more than physico-chemical substanceand encompasses values such as quality andethics. These values are legitimate in theirown right and require that new democraticprocesses are set up for transverse,transdisciplinary assessment in partnershipwith society. The notion of equivalence canprovide a reference scale in which to examinethe various legitimate factors involved:substance (SE), quality (QualitativeEquivalence: QE), and ethics (EthicalEquivalence: EE). QE requires that newqualitative methods of evaluation that are notbased on reductive principles are developed. EEcan provide a basis for the development of anEthical Assurance as a counterpart of QualityAssurance in the food sector. In France, asecond circle of expertise is being set up toaddress the social issues in food public policybeside classical risk assessment by the firstcircle of expertise. Since ethics is likely tobecome an organizing principle of the secondcircle, the equivalence ethical framework canprove instrumental in this context.     

Forest dynamics modelling under natural fire cycles: A tool to define natural mosaic diversity for forest management

In natural boreal forests, disturbances such as fire and variation in surficial deposits create a mosaic of forest stands with different species composition and age. At the landscape level, this variety of stands can be considered as the natural mosaic diversity. In this paper, we describe a model that can be used to estimate the natural diversity level of landscapes. We sampled 624 stands for tree species composition and surficial deposits in eight stand-age classes corresponding to eight fire episodes in the region of Lake Duparquet, Abitibi, Québec at the southern fringe of the Boreal Forest. For six surficial deposit types, stand composition data were used to define equations for vegetation changes with time for a chronosequence of 230 years for four forest types. Using Van Wagner's (1978) model of age class distribution of stands, the proportion of each forest type for several lengths of fire cycle were defined. Finally, for real landscapes (ecological districts) of the ecological region of the Basses-Terres d'Amos, the proportion of forest types were weighted by the proportion of each surficial deposit type using ecological map information. Examples of the possible uses of the model for management purposes, such as biodiversity conservation and comparisons of different landscapes in terms of diversity and sensitivity to fire regime changes, are discussed.     

Monitoring the Conservation of Grassland Habitats, Prairie Ecozone, Canada

The Prairie Ecozone contains 5% of Canada's land area and represents 16% of the Great Plains of North America. Current estimates indicate that 25–30% of original Canadian grassland habitats remain, largely concentrated in southeastern Alberta and southwestern Saskatchewan with fragments distributed throughout southern Manitoba. The size, distribution and condition of native grasslands serve as valuable indicators of the ecological integrity and the sustainability of those landscape types. With so little native grasslands remaining, areas that conserve grasslands serve as core sites for indicators such as gaps in ecosystem and wildlife habitat protection, i.e. which ecosystems are well-represented, poorly represented or have no representation. Such gap analyses helps to determine where protection efforts need to be placed in the future. Overall, about 3.5% of the Prairie Ecozone of Canada is under some form of conservation area status. This paper reports, relative to the ecoregions and political jurisdictions of the Prairie Ecozone, on the amount and distribution of various types of conservation areas and native grasslands. Relationships between the occurrence of conservation areas and grasslands are presented. Implications for conservation area planning and management are discussed within regional, national and international contexts. The issue of which characteristics of conservation areas should be assessed and monitored to address conservation objectives for sustainability is also discussed.     

Population growth in snow geese: a modeling approach integrating demographic and survey information

There are few analytic tools available to formally integrate information coming from population surveys and demographic studies. The Kalman filter is a procedure that facilitates such integration. Based on a state-space model, we can obtain a likelihood function for the survey data using a Kalman filter, which we may then combine with a likelihood for the demographic data. In this paper, we used this combined approach to analyze the population dynamics of a hunted species, the Greater Snow Goose (Chen caerulescens atlantica), and to examine the extent to which it can improve previous demographic population models. The state equation of the state-space model was a matrix population model with fecundity and regression parameters relating adult survival and harvest rate estimated in a previous capture-recapture study. The observation equation combined the output from this model with estimates from an annual spring photographic survey of the population. The maximum likelihood estimates of the regression parameters from the combined analysis differed little from the values of the original capture-recapture analysis, though their precision improved. The model output was found to be insensitive to a wide range of coefficient of variation (CV) in fecundity parameters. We found a close match between the surveyed and smoothed population size estimates generated by the Kalman filter over an 18-year period, and the estimated CV of the survey (0.078-0.150) was quite compatible with its assumed value (approximately 0.10). When we used the updated parameter values to predict future population size, the model underestimated the surveyed population size by 18% over a three-year period. However, this could be explained by a concurrent change in the survey method. We conclude that the Kalman filter is a promising approach to forecast population change because it incorporates survey information in a formal way compared with ad hoc approaches that either neglect this information or require some parameter or model tuning.     

Mycobacteriosis-associated mortality in wild striped bass (Morone saxatilis) from Chesapeake Bay, U.S.A

The striped bass (Morone saxatilis) is an economically and ecologically important finfish species along the Atlantic seaboard of the United States. Recent stock assessments in Chesapeake Bay (U.S.A.) indicate that non-fishing mortality in striped bass has increased since 1999, concomitant with very high (>50%) prevalence of visceral and dermal disease caused by Mycobacterium spp. Current fishery assessment models do not differentiate between disease and other components of non-fishing mortality (e.g., senescence, predation); therefore, disease impact on the striped bass population has not been established. Specific measurement of mortality associated with mycobacteriosis in wild striped bass is complicated because the disease is chronic and mortality is cryptic. Epidemiological models have been developed to estimate disease-associated mortality from cross-sectional prevalence data and have recently been generalized to represent disease processes more realistically. Here, we used this generalized approach to demonstrate disease-associated mortality in striped bass from Chesapeake Bay. To our knowledge this is the first demonstration of cryptic mortality associated with a chronic infectious disease in a wild finfish. This finding has direct implications for management and stock assessment of striped bass, as it demonstrates population-level negative impacts of a chronic disease. Additionally, this research provides a framework by which disease-associated mortality may be specifically addressed within fisheries models for resource management.     

Computational fluid dynamics modelling of flow and particulate contaminants sedimentation in an urban stormwater detention and settling basin

Sedimentation is a common but complex phenomenon in the urban drainage system. The settling mechanisms involved in detention basins are still not well understood. The lack of knowledge on sediment transport and settling processes in actual detention basins is still an obstacle to the optimization of the design and the management of the stormwater detention basins. In order to well understand the sedimentation processes, in this paper, a new boundary condition as an attempt to represent the sedimentation processes based on particle tracking approach is presented. The proposed boundary condition is based on the assumption that the flow turbulent kinetic energy near the bottom plays an important role on the sedimentation processes. The simulated results show that the proposed boundary condition appears as a potential capability to identify the preferential sediment zones and to predict the trapping efficiency of the basin during storm events.     

Proposal to optimize ecotoxicological evaluation of wastewater treated by conventional biological and ozonation processes

A mixture of urban and hospital effluents (50 % v/v) was evaluated for ecotoxicity with an advanced bioassay battery. Mixed effluents were tested before any treatment, after biological treatment alone, and after biological treatment followed by a tertiary ozonation (15 mg O₃/L). Laying a high value on the continuance of organisms’ fitness, essential to preserve a healthy receiving ecosystem, the main objective of this study was to combine normalized bioassays with newly developed in vivo and in vitro tests in order to assess alteration of embryo development, growth and reproduction, as well as genotoxic effects in aquatic organisms exposed to complex wastewater effluents. Comparison of the bioassays sensitivity was considered. Contrary to the lack of toxicity observed with normalized ecotoxicity tests, endpoints measured on zebrafish embryos such as developmental abnormalities and genotoxicity demonstrated a residual toxicity in wastewater both after a biological treatment followed or not by a tertiary O₃ treatment. However, the ozonation step allowed to alleviate the residual endocrine disrupting potential measure in the biologically treated effluent. This study shows that normalized bioassays are not sensitive enough for the ecotoxicological evaluation of wastewaters and that there is a great need for the development of suitable sensitive bioassays in order to characterize properly the possible residual toxicity of treated effluents.     

Use of agro-industrial organic sludge amendment to remediate degraded soil: chemical and eco(geno)toxicological differences between fresh and stabilized sludge and establishment of application rates

Soil degraded by coal mining activities can be remediated by amendment with agro-industrial organic sludge. However, the environmental impacts associated with this management practice must be properly addressed. In this context, the objective of this study was to evaluate the eco(geno)toxicity of a fresh and a stabilized sludge before use in a laboratory soil remediation test. Chemical analysis of the complex mixtures (degraded soil, fresh sludge, and stabilized sludge) was carried out, as well as a battery of eco(geno)toxicity tests on microbiological enzymes (fluorescein hydrolysis), earthworms, and higher plants (including Vicia faba genotoxicity test), according to published methodologies. The results of these tests showed that fresh sludge was more toxic than sludge stabilized over 6 months toward earthworms and higher plants (lettuce, corn, and wild cabbage), while phyto(geno)toxicity tests with V. faba indicated the same genotoxicity levels for the two types of sludge. In the soil remediation simulation using different mixtures of degraded soil and stabilized sludge, the proportions of 50:50 % (dry weight basis) provided the lowest phyto(geno)toxicity effects and this mixture can be used for the revegetation of the contaminated site.