Relevance of organic matter fractions as predictors of wastewater sludge mineralization in soil

Seventeen different wastewater sludges were characterized using both chemical and organic matter fractionation methods (water extraction, Van Soest method, and acid hydrolysis) and 6-mo incubation studies to assess their decomposition in soil. Simple correlation and multiple factor analysis (MFA) were then performed to establish relationships between composition and C and N mineralization of sludges. Carbon and N concentrations covered a wide range of values, but organic carbon (C(o)) to organic nitrogen (N(o)) ratios were relatively low (from 5 to 19). Carbon and N were mainly distributed in the most soluble fractions of the Van Soest method and in the water-insoluble fraction at 100 degrees C. Carbon mineralization varied from 180 to 661 g C kg(-1) organic C added during the 168-d incubation. The addition of sludges led to different inorganic N dynamics: from -3.3 to +120.0 g N kg(-1) sludge organic C mineralized after the 168-d incubation. Fractionation studies showed that the most discriminating method was acid hydrolysis. Carbon mineralization was linked with the proportion of sludge N and C present in the lignin-like fraction (r = -0.68 and -0.65, respectively). Significant relationships were established between N mineralization and N(o) to C(o) ratio (0.88 < r < 0.95) and the C(o) to N(o) ratio of sludges, the C to N ratio of the soluble fraction obtained by the Van Soest method, the water-soluble fraction at 100 degrees C, and the C and N present in the acid-hydrolyzable fraction. Finally, multiple factor analysis also enabled establishing a sludge typology using five clusters based on composition and mineralization characteristics.     

EFFECTS OF MULTI‐SCALE ENVIRONMENTAL CHARACTERISTICS ON AGRICULTURAL STREAM BIOTA IN EASTERN WISCONSIN1

ABSTRACT: The U.S. Geological Survey examined 25 agricultural streams in eastern Wisconsin the determine relations between fish, invertebrate, and algal metrics and multiple spatial scales of land cover, geologic setting, hydrologic, aquatic habitat, and water chemistry data. Spearman correlation and redundancy analyses were used to examine relations among biotic metrics and environmental characteristics. Riparian vegetation, geologic, and hydrologic conditions affected the response of biotic metrics to watershed agricultural land cover but the relations were aquatic assemblage dependent. It was difficult to separate the interrelated effects of geologic setting, watershed and buffer land cover, and base flow. Watershed and buffer land cover, geologic setting, reach riparian vegetation width, and stream size affected the fish IBI, invertebrate diversity, diatom IBI, and number of algal taxa; however, the invertebrate FBI, percentage of EPT, and the diatom pollution index were more influenced by nutrient concentrations and flow variability. Fish IBI scores seemed most sensitive to land cover in the entire stream network buffer, more so than watershed‐scale land cover and segment or reach riparian vegetation width. All but one stream with more than approximately 10 percent buffer agriculture had fish IBI scores of fair or poor. In general, the invertebrate and algal metrics used in this study were not as sensitive to land cover effects as fish metrics. Some of the reach‐scale characteristics, such as width/depth ratios, velocity, and bank stability, could be related to watershed influences of both land cover and geologic setting. The Wisconsin habitat index was related to watershed geologic setting, watershed and buffer land cover, riparian vegetation width, and base flow, and appeared to be a good indicator of stream quality Results from this study emphasize the value of using more than one or two biotic metrics to assess water quality and the importance of environmental characteristics at multiple scales.     

Cofoundress relatedness and group productivity in colonies of social <Emphasis Type="Italic">Dunatothrips</Emphasis> (Insecta: Thysanoptera) on Australian <Emphasis Type="Italic">Acacia</Emphasis>

Facultative joint colony founding by social insects provides opportunities to analyze the roles of genetic and ecological factors in the evolution of cooperation. Although cooperative nesting is observed in range of social insect taxa, the most detailed studies of this behavior have been conducted with Hymenoptera (ants, bees, and wasps). Here, we show that foundress associations in the haplodiploid social thrips Dunatothrips aneurae (Insecta: Thysanoptera) are most often comprised of close relatives (sisters), though groups with unrelated foundresses are also found. Associations among relatives appear to be facilitated by limited female dispersal, which results in viscous population structure. In addition, we found that per capita productivity declined with increasing group size, sex ratios were female-biased, and some female offspring apparently remained in their natal domicile for some time following eclosion. D. aneurae thus exhibits a suite of similarities with eusocial Hymenoptera, providing evidence for the convergent evolution of associated social and life-history traits in Hymenoptera and Thysanoptera.     

Metacommunity models predict the local-regional species richness relationship in a natural system

Many natural communities exhibit positive relationships between local and regional species richness (LSR-RSR relationships), which can be either linear or curvilinear. Previous models have shown that the form of this relationship depends on the relative rates of colonization and extinction and the sensitivity of these rates to competition. We use simple models to show that the LSR-RSR relationship also depends on the type of metacommunity structure (Levins-like or mainland-island), and our models generate a wider range of realistic forms than do most previous models. We parameterize and test our models with two independent data sets for Daphnia in rock pools on islands in Finland and Sweden. We find that the Levins-like model with competition correctly predicts the observed LSR-RSR relationship and provides the best fit to the average local species richness per island. Simulations show that our models are robust to relaxing our assumption of identical species properties. Our study is one of the first to make and successfully test quantitative predictions for how a widely studied community pattern, the LSR-RSR relationship, arises from metacommunity dynamics.     

Correlation and persistence of hunting and logging impacts on tropical rainforest mammals

Humans influence tropical rainforest animals directly via exploitation and indirectly via habitat disturbance. Bushmeat hunting and logging occur extensively in tropical forests and have large effects on particular species. But how they alter animal diversity across landscape scales and whether their impacts are correlated across species remain less known. We used spatially widespread measurements of mammal occurrence across Malaysian Borneo and recently developed multispecies hierarchical models to assess the species richness of medium‐ to large‐bodied terrestrial mammals while accounting for imperfect detection of all species. Hunting was associated with 31% lower species richness. Moreover, hunting remained high even where richness was very low, highlighting that hunting pressure persisted even in chronically overhunted areas. Newly logged sites had 11% lower species richness than unlogged sites, but sites logged >10 years previously had richness levels similar to those in old‐growth forest. Hunting was a more serious long‐term threat than logging for 91% of primate and ungulate species. Hunting and logging impacts across species were not correlated across taxa. Negative impacts of hunting were the greatest for common mammalian species, but commonness versus rarity was not related to species‐specific impacts of logging. Direct human impacts appeared highly persistent and lead to defaunation of certain areas. These impacts were particularly severe for species of ecological importance as seed dispersers and herbivores. Indirect impacts were also strong but appeared to attenuate more rapidly than previously thought. The lack of correlation between direct and indirect impacts across species highlights that multifaceted conservation strategies may be needed for mammal conservation in tropical rainforests, Earth's most biodiverse ecosystems. Correlación y Persistencia de los Impactos de la Caza y la Tala sobre los Mamíferos de los Bosques Tropicales     

Degradation of 17α-ethinylestradiol by ozonation--identification of the by-products and assessment of their estrogenicity and toxicity

The presence of the synthetic estrogen 17α-ethinylestradiol (EE2) in waters at low levels is a concern due to its ability to act as an endocrine disruptor. Ozone (O₃) is commonly used in water treatment and reacts with EE2 to form by-products having characteristics that are mostly unknown. The aim of this study was to identify the by-products of E2 and EE2 ozonation and determine their estrogenicity and toxicity relative to the parent compound. Ozonation by-products were identified via LC-MS analysis. The estrogenicity was measured using the YES assay, and toxicity was determined by monitoring effects on histology of fetal rat testes and testosterone secretion by these tissues. Two EE2 by-products were identified with open phenolic ring structures (masses 302 and 344 u). The Yeast Estrogen Screening (YES) assay showed a decreased but incomplete removal of estrogenicity after ozonation of EE2. Histological analysis of fetal testes revealed that neither E2 nor EE2, with or without ozonation, had any effect on seminiferous cord formation; however, a remarkable negative effect on testosterone secretion was observed, with EE2 by-products after ozonation showing the most rapid and extensive inhibition. These results show that the removal of EE2 via reaction with O₃ resulted in the formation of by-products that are less estrogenic (as demonstrated by the YES assay), but have a greater negative impact on testosterone secretion. Thus, the disappearance of the parent compound is not a sufficient endpoint, as the by-products created may be more toxic. Care should be taken when implementing oxidation applications such as ozone during waste water treatment.     

Evaluation of water quality in the Ouémé River (Bénin)

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.     

Remanufacturing

This paper presents a theoretical model of remanufacturing where a duopoly of original manufacturers produces a component of a final good. The specific component that needs to be replaced during the lifetime of the final good creates a secondary market where independent remanufacturers enter the competition. An environmental regulation imposing a minimum level of remanufacturability is also introduced. The main results establish that, while collusion of the firms on the level of remanufacturability increases both profit and consumer surplus, a social planner could use collusion as a substitute for an environmental regulation. However, if an environmental regulation is to be implemented, collusion should be repressed since competition supports the public intervention better. Under certain circumstances, the environmental regulation can increase both profit and consumer surplus. Part of this result supports the Porter Hypothesis, which stipulates that industries respecting environmental regulations can see their profits increase.     

MIE determination and thermal degradation study of PA12 polymer powder used for laser sintering

Pulverized materials such as metallic or polymer powders play a considerable role in many industrial processes. Their use requires the introduction of preventive safeguards to control the plant's safety.PA12 polymer powder processing by laser sintering is characteristic of this tendency. The present work concerns PA12 powder (bimodal particle size distribution: 10 μm and 55 μm) and relates to explosion sensitivity and the thermal degradation of this powder, which can occur during laser sintering. Minimum Ignition Energy is determined using a modified Hartmann tube combined with the Langlie method developed in the PRISME Laboratory. This study shows the influence of parameters such as distance between the electrodes, powder concentration and arc power on MIE values. Theses parameters vary in the range of 3–6 A for the current intensity of the spark and the electrode gap in the range of 2.5–4 mm. The MIE is obtained for a spark gap of 3 mm and current intensity of the 4 A spark in our device. It shows that the MIE is less than 40 mJ for concentrations approaching 1000 g/m³. At lower concentrations (under 150 g/m³) the MIE increases but discrepancies in measurements appear, probably because of the static electricity that creates strong irregularities in dust dispersion. The second part of this study concerns the thermal degradation of the PA12 which is performed by thermogravimetric experiments coupled with mass spectrometric (MS) analysis for gas investigation. The mass loss measurement combined with the gas analysis allows the principal stages of degradation to be determined so as to calculate the kinetics parameter PA12. Experiments have been performed for different heating rates between 1 and 30 K min^?1 and the reproducibility of experiments has been verified. The activation energy is determined using two methods: Freidman and KAS. For a reaction rate of between 0.2 and 0.6, the activation energy is nearly constant. The KAS method gives a value of E_a = 250 kJ mol^?1 and the Friedman method gives E_a = 300 kJ mol^?1. The gas analysis by MS shows that oxidation begins at over 350 °C and finishes at under 650 °C with the formation of CO₂ and H₂O. Other major peaks with an m/z ratio of 29, 28 and 30 are noticed in this range of temperature. They show the presence of intermediate species such as C₂H₆, NO or CH₂O. The presence of HCN is also detected (m/z ratio of 27).     

Crop Protection Between Sciences, Ethics and Societies: From Quick-Fix Ideal to Multiple Partial Solutions

Crop protection has a very long history during which new methods have been developed whilst, at the same time, the older ones have retained their usefulness in certain conditions. The diversity of agricultural land and production has meant that it was futile to search for a unique and definitive approach or technical solution and, instead, the central concept has always been one of integration, during all the period of pre-Green Revolution and again today within what we call a sustainable agriculture. On a global level, it would seem that the current situation does not fundamentally contradict this idea. Nevertheless, in recent years (since the Second World War), two important advances, presented as the definitive solutions to problems and potentially exceeding previously less effective ones, have led to this integrative approach being questioned. These are agrochemistry and agro-genetics. We will detail, here, the agro-environmental limits of these two “miracle solutions,” followed by a review from an ethical and an epistemological point of view. This enables us to demonstrate the relevance of integrated approaches in agriculture and leads to a definition of crop protection that forms part of a strong approach in sustainable development. By changing the semantics, the epistemic position and our vision of production, we arrive at the proposal of sustainable agriculture.