Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Impacts of Climate Change on the Timing of the Production Season of Maple Syrup in Eastern Canada

Maple syrup production is an important economic activity in north-eastern North-America. The beginning and length of the production season is linked to daily variation in temperature. There are increasing concerns about the potential impact of climatic change on this industry. Here, we used weekly data of syrup yield for the 1999–2011 period from 121 maple stands in 11 regions of Québec (Canada) to predict how the period of production may be impacted by climate warming. The date at which the production begins is highly variable between years with an average range of 36 days among the regions. However, the average start date for a given region, which ranged from Julian day 65 to 83, was highly predictable (r2 = 0.88) using the average temperature from January to April (TJ-A). A logistic model predicting the weekly presence or absence of production was also developed. Using the inputs of 77 future climate scenarios issued from global models, projections of future production timing were made based on average TJ-A and on the logistic model. The projections of both approaches were in very good agreement and suggest that the sap season will be displaced to occur 15–19 days earlier on average in the 2080–2100 period. The data also show that the displacement in time will not be accompanied by a greater between years variability in the beginning of the season. However, in the southern part of Québec, very short periods of syrup production due to unfavourable conditions in the spring will occur more frequently in the future although their absolute frequencies will remain low

J Soils Sediments

Purpose: Arsenic (As) is one of the most widespread toxic elements, affecting human health through consumption of contaminated water or food. This work studied the effects of ammonium sulphate (NH4)2SO4 on mobility, speciation, and toxicity of As in a soil polluted by the destruction of chemical ammunition. Methods: Effects of fertilization on mobility and speciation of As, abundance of active AsIII-oxidizing and AsV-reducing microorganisms, abundance of bacterial 16S rRNA genes, and aioA and arsB genes involved in As biotransformation were monitored during barley growth in polluted (P) and non-polluted (NP) soils in pots maintained in outdoor conditions, with either the usual dose of (NH4)2SO4, 10 × or 100 × this dose. As transfer to plants and phytotoxicity were evaluated through quantification and speciation of As in grains and lipid peroxidation in plant leaves. Results: As mobility was significantly reduced by the highest dose of (NH4)2SO4. Fertilization tended to increase the Omega-3 Index in barley with the P soil. Abundance of AsIII-oxidizing microorganisms was higher and plant biomass was lower in P than in NP soil. Neither pollution level nor fertilization dose affected As speciation in soils or gene abundance. The sum of the concentrations of extracted AsIII and AsV species in grains was in the range 0–150 µg kg−1 with NP soil and 2000–3500 µg kg−1 with P soil. Conclusions: Results underline the importance of developing surveys of As dynamics in agricultural contexts with diverse types of crops, with a focus on As speciation mechanisms, linked to soil microbial activities and plant physiology

Influence of environmental changes on the biogeochemistry of arsenic in a soil polluted by the destruction of chemical weapons: A mesocosm study

International audienceThermal destruction of chemical munitions from World War I led to the formation of a heavily contaminated residue that contains an unexpected mineral association in which a microbial As transformation has been observed. A mesocosm study was conducted to assess the impact of water saturation episodes and input of bioavailable organic matter (OM) on pollutant behavior in relation to biogeochemical parameters. Over a period of about eight (8) months, the contaminated soil was subjected to cycles of dry and wet periods corresponding to water table level variations. After the first four (4) months, fragmented litter from the nearby forest was placed on top of the soil. The mesocosm solid phase was sampled by three rounds of coring: at the beginning of the experiment, after four (4) months (before the addition of OM), and at the end of the experiment. Scanning electron microscopy coupled to energy dispersive X-ray spectroscopy observations showed that an amorphous phase, which was the primary carrier of As, Zn, and Cu, was unstable under water-saturated conditions and released a portion of the contaminants in solution. Precipitation of a lead arsenate chloride mineral, mimetite, in soils within the water saturated level caused the immobilization of As and Pb. Mimetite is a durable trap because of its large stability domain; however, this precipitation was limited by a low Pb concentration inducing that high amounts of As remained in solution. The addition of forest litter modified the quantities and qualities of soil OM. Microbial As transformation was affected by the addition of OM, which increased the concentration of both As(III)-oxidizing and As(V)-reducing microorganisms. The addition of OM negatively impacted the As(III) oxidizing rate, however As(III) oxidation was still the dominant reaction in accordance with the formation of arsenate-bearing minerals

Biogeochemical behaviour of geogenic As in a confined aquifer of the Sologne region, France

International audienceArsenic (As) is one of the main toxic elements of geogenic origin that impact groundwater quality and human health worldwide. In some groundwater wells of the Sologne region (Val de Loire, France), drilled in a confined aquifer, As concentrations exceed the European drinking water standard (10 μg L−1). The monitoring of one of these drinking water wells showed As concentrations in the range 20–25 μg L−1. The presence of dissolved iron (Fe), low oxygen concentration and traces of ammonium indicated reducing conditions. The δ34SSO4 was anticorrelated with sulphate concentration. Drilling allowed to collect detrital material corresponding to a Miocene floodplain and crevasse splay with preserved plant debris. The level that contained the highest total As concentration was a silty-sandy clay containing 26.9 mg kg−1 As. The influence of alternating redox conditions on the behaviour of As was studied by incubating this material with site groundwater, in biotic or inhibited bacterial activities conditions, without synthetic organic nutrient supply, in presence of H2 during the reducing periods. The development of both AsV-reducing and AsIII-oxidising microorganisms in biotic conditions was evidenced. At the end of the reducing periods, total As concentration strongly increased in biotic conditions. The microflora influenced As speciation, released Fe and consumed nitrate and sulphate in the water phase. Microbial communities observed in groundwater samples strongly differed from those obtained at the end of the incubation experiment, this result being potentially related to influence of the sediment compartment and to different physico-chemical conditions. However, both included major Operating Taxonomic Units (OTU) potentially involved in Fe and S biogeocycles. Methanogens emerged in the incubated sediment presenting the highest solubilised As and Fe. Results support the hypothesis of in-situ As mobilisation and speciation mediated by active biogeochemical processes

Biogeochemical origin of arsenic in groundwater from the loire valley miocene formation

Communication oraleInternational audienc

Biogeochemical origin of arsenic in groundwater from the loire valley miocene formation

Communication oraleInternational audienc

Influence of agricultural amendments on arsenic biogeochemistry and phytotoxicity in a soil polluted by the destruction of arsenic-containing shells

Agricultural soils can contain high arsenic (As) concentrations due to specific geological contexts or pollution. Agricultural practices, in particular fertilizer amendments, could influence As speciation and mobility, thus increasing its transfer to crops and its toxicity. In the present study, field-relevant amounts of fertilizers were applied to soils from a cultivated field that was a former ammunition-burning site. Potassium phosphate, ammonium sulfate and organic matter were applied to these soils in laboratory experiments to assess both their impact on As leaching and on As bioavailability to Lactuca sativa. Results indicate that none of the fertilizers significantly influences the speciation and quantity of mobile As, although trends showed an increase of mobility with KP and a decrease of mobility with ammonium sulfate. The most probable number of AsIII-oxidizing microbes and AsIII-oxidizing activity were strongly linked to As levels in water and soils. In the reference un-polluted soil, ammonium sulfate negatively affected AsIII-oxidizing activity. KP amendment induced a small increase of As content in plants, and the polluted soil amended with ammonium sulfate was significantly less phytotoxic than the un-amended soil. Results suggest that ammonium sulfate, the most frequently applied fertilizer on site, influences the interactions between As, microorganisms and plants.Evaluation et gestion des contaminations en arsenic dans les eaux et les sols agricole

Relationship between the Julian day of the start of the season production (left panel, A) as projected with the logistic model (x axis) and the T_J-A model (y axis) for the 2081–2100 period for each of the 77 simulation for the 11 regions (n = 847).

<p>The right panel (B) shows the distribution of the displacement (delta Julian day) of the 2081–2100 vs the 1971–2000 period.</p