Future intensification of summer hypoxia in the tidal Garonne River (SW France) simulated by a coupled hydro sedimentary-biogeochemical model

Projections for the next 50 years predict a widespread distribution of hypoxic zones in the open and coastal ocean due to environmental and global changes. The Tidal Garonne River (SW France) has already experienced few episodic hypoxic events. However, predicted future climate and demographic changes suggest that summer hypoxia could become more severe and even permanent near the city of Bordeaux in the next few decades. A 3D model, which couples hydrodynamic, sediment transport, and biogeochemical processes, is applied to assess the impact of factors submitted to global and regional climate changes on oxygenation in the turbidity maximum zone (TMZ) of the Tidal Garonne River during low-discharge periods. The model simulates an intensification of summer hypoxia with an increase in temperature, a decrease in river flow or an increase in the local population, but not with sea level rise, which has a negligible impact on dissolved oxygen. Different scenarios were tested by combining these different factors according to the regional projections for 2050 and 2100. All the simulations showed a trend toward a spatial and temporal extension of summer hypoxia that needs to be considered by local water authorities to impose management strategies to protect the ecosystem.     

Invasion costs,impacts, and human agency: response to Sagoff 2020

Article impact statement: In an era of profound biodiversity crisis, invasion costs, invader impacts, and human agency should not be dismissed.     

Fast characterization of non domestic load in urban wastewater networks by UV spectrophotometry

Urban wastewater treatment plant efficiency, as well as biosolid quality, depends on urban wastewater quality, which can be affected by non domestic discharges (industrial, commercial etc.). The characterization of wastewater quality and non domestic discharge is complex, expensive and time consuming. However, these discharges must be controlled and reduced if possible. The development of a simple and fast methodology, namely based on alternative methods such as UV spectrophotometry, has been carried out and applied to different areas of a medium sized town of Southern Québec (Canada). Several autosamplers and on line/on site measurements have been used in critical control points of the network areas, for a dry weather campaign in four areas (industrial, commercial, hospital and university). The flow rate study, completed by the exploitation of conductivity measurements and the qualitative examination of UV spectra allows the discrimination of non domestic loads and their variability study from one point to another. The identification of critical discharges and organic shock loads has been possible with low investment, and mitigation actions have been proposed.     

Sampling and Analysis of Quaternary Ammonium Compounds (QACs) Traces in Indoor Atmosphere

Quaternary Ammonium Compounds (QACs) are widely found in disinfectants used in hospitals. Benzalkonium chloride (BAC) and didecyldimethylammonium chloride (DDAC) predominate in the disinfecting formulations. These compounds are strong irritants and can play a role in the induction of Occupational Asthma among the professionals of health and cleaning. In order to evaluate the potential health effect of these quaternary ammonium compounds to hospital employers, the development of an analytical method for their quantification in indoor air was developed. DDAC aerosols are trapped by adsorption on XAD-2 resin SKC tube. The air in hospital buildings was sampled using a constant debit Gillian pump at a flow of 1.0 l/min (+/-5%). Ion Chromatography (IC) was chosen for the analysis of DDAC especially for its high sensitivity and specificity. The Limit of Detection (LOD) by IC for DDAC is 0.56 mug/ml. Therefore the LOD of atmospheric DDAC is 28 microg/m(3) with an air volume of 100 l and a desorption volume of 5 ml. All DDAC air samples were lower than the LOD of the analytical method by IC. Under the standard conditions of use of the disinfecting solutions (Surfanios, Ampholysine Plus and Amphospray 41), the insignificant volatility of DDAC would not seem to be able to contaminate the indoor hospital atmosphere during the disinfection process. However, the DDAC can contaminate working atmospheres if it is put in suspension by aerosolisation.     

Determination of 14 amines in air samples using midget impingers sampling followed by analysis with ion chromatography in tandem with mass spectrometry

An Ion Chromatography-Mass Spectrometry (IC-MS) method was developed for the simultaneous quantification of 14 volatile amines in air. The method includes collection of compounds into two midget impingers in a row filled with 15 ml of ultrapure water. The analytical performances with mass spectrometry detection were compared to those obtained with classical conductivity detection. The use of mass spectrometry detection (in SIM mode) overcomes most of the coelutions encountered with conductivity detection. Although the linearity domain of calibrations is reduced for the MS detection as compared with the CD detection, the detection limits in MS detection are highly lowered allowing the quantification of amines at the levels of μg m(-3) in air with a good accuracy for most compounds (RSD of less than 10%). This method was successfully applied to the analysis of amines released from polyurethane foams. Seven amines were identified and some in high concentrations, like dimethylaminoethanol, NIAX and TEDA.     

Measurement of Odor Intensity by an Electronic Nose

ABSTRACT

The possibility of using electronic noses (ENs) to measure odor intensity was investigated in this study. Two commercially available ENs, an Aromascan A32S with conducting polymer sensors and an Alpha M.O.S. Fox 3000 with metal oxide sensors, as well as an experimental EN made of Taguchi-type tin oxide sensors, were used in the experiments. Odor intensity measurement by sensory analysis and EN sensor response were obtained for samples of odorous compounds (n-butanol, CH₃COCH₃, and C₂H₅SH) and for binary mixtures of odorous compounds (n-butanol and CH₃COCH₃). Linear regression analysis and artificial neural networks (ANN) were used to establish a relationship between odor intensity and EN sensor responses.

The results suggest that large differences in sensor response to samples of equivalent odor intensity exist and that sensitivity to odorous compounds varies according to the type of sensors. A linear relationship between odor intensity and averaged sensor response was found to be appropriate for the EN based on conducting polymer sensors with a correlation coefficient (r) of 0.94 between calculated and measured odor intensity. However, the linear regression approach was shown to be inadequate for both ENs, which included metal oxide-type sensors. Very strong correlation (r = 0.99) between measured odor intensity and calculated odor intensity using the ANN developed were obtained for both commercial ENs. A weaker correlation (r = 0.84) was found for the experimental instrument, suggesting an insufficient number of sensors and/or not enough diversity in sensor responses. The results demonstrated the ability of ENs to measure odor intensity associated with simple mixtures of odorous compounds and suggest that ANN are appropriate to model the relationship between odor intensity measurement and EN sensor response.     

中国碳排放态势与绿色经济展望

中国从2007年开始已成为世界温室气体排放第一大国,减排的国际压力越来越大。本文采用国际能源署公布的国别时间系列数据(1990-2007),系统分析了中国碳排放的现状、特点及历史变化;从经济发展、能源消费、经济全球化、社会转型等多方面解析了中国未来碳排放总量将会继续增长的基本态势。同时,从绿色技术、可再生能源的发展、生态城市建设等方面论述了中国未来必然成为世界绿色经济大国的可能性。最后,为了实现中国从排放大国走向绿色经济大国,提出了理论上需要深入研究的几个问题,即:碳排放速度与不同空间尺度问题,经济转型与反转型,碳排放的责任与国界。     

Emissions of gases and particles from biomass burning during the 20th century using satellite data and an historical reconstruction

A new dataset of emissions of trace gases and particles resulting from biomass burning has been developed for the historical and the recent period (1900–2005). The purpose of this work is to provide a consistent gridded emissions dataset of atmospheric chemical species from 1900 to 2005 for chemistry-climate simulations. The inventory is built in two steps. First, fire emissions are estimated for the recent period (1997–2005) using satellite products (GBA2000 burnt areas and ATSR fire hotspots); the temporal and spatial distribution of the CO₂ emissions for the 1997–2005 period is estimated through a calibration of ATSR fire hotspots. The historical inventory, covering the 1900–2000 period on a decadal basis, is derived from the historical reconstruction of burned areas from Mouillot and Field (2005). The historical emissions estimates are forced, for each main ecosystem, to agree with the recent inventory estimates, ensuring consistency between past and recent emissions.The methodology used for estimating the fire emissions is discussed, together with the time evolution of biomass burning emissions during the 20th century, first at the global scale and then for specific regions. The results are compared with the distributions provided by other inventories and results of inverse modeling studies.     

Nonparametric spatial regression of survival probability: visualization of population sinks in Eurasian woodcock

Both evolutionary ecologists and wildlife managers make inference based on how fitness and demography vary in space. Spatial variation in survival can be difficult to assess in the wild because (1) multisite study designs are not well suited to populations that are continuously distributed across a large area and (2) available statistical models accounting for detectability less than 1.0 do not easily cope with geographical coordinates. Here we use penalized splines within a Bayesian state-space modeling framework to estimate and visualize survival probability in two dimensions. The approach is flexible in that no parametric form for the relationship between survival and coordinates need be specified a priori. To illustrate our method, we study a game species, the Eurasian Woodcock Scolopax rusticola, based on band recovery data (5000 individuals) collected over a > 50 000-km2 area in west-central France with contrasted habitats and hunting pressures. We find that spatial variation in survival probability matches an index of hunting pressure and creates a mosaic of population sources and sinks. Such analyses could provide guidance concerning the spatial management of hunting intensity or could be used to identify pathways of spatial variation in fitness, for example, to study adaptation to changing landscape and climate.     

From dummies to animations: a review of computer-animated stimuli used in animal behavior studies

Traditionally, studies that explored animal communication have been directed towards the observation of natural interactions between individuals. Over the years, researchers have long championed the use of artificial stimuli in place of natural ones in behavioral experiments to precisely control what the observers get to see or experience. The employment of diverse techniques to stage animal interactions has provided an alternative to observations and intrusive experimental methods. Technological advances now allow researchers to develop realistic computer animations of social partners that mimic behaviors with a high degree of fidelity for morphological and behavioral characteristics of tutors. The increasing use of the computer-generated animations technique reveals a desire to deliver standardized visual stimuli and to limit the variable behavior of demonstrators across experimental sessions. In the following review, we provide an appraisal of the computer-generated animations efficiency to stage animal interactions, and consider experimental studies in which this technique has been employed to simulate social interactions. We also present alternative methods that are used for designing animation models. Our aim is to evaluate the merits of computer-generated animations and how this technique may be more appropriate for certain types of staged interactions when compared to other classically employed approaches. We advocate that computer-generated animations appear to be the most flexible technique to date, and offers better control of visual cues that are presented, thus allowing researchers to program a large variety of stimuli. Finally, we suggest improvements of this technique, and especially how it may be used to study signal design in multimodal systems.