Sources, transport and deposition of iron in the global atmosphere

International audienceAtmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and the subsequent deposition to the oceans have been accounted for in only few ocean biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960–2007 were estimated to be 5.3 Tg yr−1 (90% confidence of 2.3 to 12.1). Of these emissions, 1, 27 and 72% were emitted in particles 10 μm (PM> 10), respectively, compared to a total Fe emission from mineral dust of 41.0 Tg yr−1 in a log-normal distribution with a mass median diameter of 2.5 μm and a geometric standard deviation of 2. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 since 2000 due to an increase in Fe emission from motor vehicles (from 0.008 to 0.0103 Tg yr−1 in 2000 and 2007, respectively). These emissions have been introduced in a global 3-D transport model run at a spatial resolution of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations as monthly means were compared with the monthly (57 sites) or daily (768 sites) measured concentrations at a total of 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the surface was within a factor of 2 at most sampling stations, and the deviation was within a factor of 1.5 at sampling stations dominated by combustion sources. We analysed the relative contribution of combustion sources to total Fe concentrations over different regions of the world. The new mineralogical database led to a modest improvement in the simulation relative to station data even in dust-dominated regions, but could provide useful information on the chemical forms of Fe in dust for coupling with ocean biota models. We estimated a total Fe deposition sink of 8.4 Tg yr−1 over global oceans, 7% of which originated from the combustion sources. Our central estimates of Fe emissions from fossil fuel combustion (mainly from coal) are generally higher than those in previous studies, although they are within the uncertainty range of our estimates. In particular, the higher than previously estimated Fe emission from coal combustion implies a larger atmospheric anthropogenic input of soluble Fe to the northern Atlantic and northern Pacific Oceans, which is expected to enhance the biological carbon pump in those regions

Actual performance of mechanical ventilators in ICU: a multicentric quality control study.

Even if the performance of a given ventilator has been evaluated in the laboratory under very well controlled conditions, inappropriate maintenance and lack of long-term stability and accuracy of the ventilator sensors may lead to ventilation errors in actual clinical practice. The aim of this study was to evaluate the actual performances of ventilators during clinical routines. A resistance (7.69 cmH(2)O/L/s) - elastance (100 mL/cmH(2)O) test lung equipped with pressure, flow, and oxygen concentration sensors was connected to the Y-piece of all the mechanical ventilators available for patients in four intensive care units (ICUs; n = 66). Ventilators were set to volume-controlled ventilation with tidal volume = 600 mL, respiratory rate = 20 breaths/minute, positive end-expiratory pressure (PEEP) = 8 cmH(2)O, and oxygen fraction = 0.5. The signals from the sensors were recorded to compute the ventilation parameters. The average ± standard deviation and range (min-max) of the ventilatory parameters were the following: inspired tidal volume = 607 ± 36 (530-723) mL, expired tidal volume = 608 ± 36 (530-728) mL, peak pressure = 20.8 ± 2.3 (17.2-25.9) cmH(2)O, respiratory rate = 20.09 ± 0.35 (19.5-21.6) breaths/minute, PEEP = 8.43 ± 0.57 (7.26-10.8) cmH(2)O, oxygen fraction = 0.49 ± 0.014 (0.41-0.53). The more error-prone parameters were the ones related to the measure of flow. In several cases, the actual delivered mechanical ventilation was considerably different from the set one, suggesting the need for improving quality control procedures for these machines

Global patterns of phosphatase activity in natural soils

Soil phosphatase levels strongly control the biotic pathways of phosphorus (P), an essential element for life, which is often limiting in terrestrial ecosystems. We investigated the influence of climatic and soil traits on phosphatase activity in terrestrial systems using metadata analysis from published studies. This is the first analysis of global measurements of phosphatase in natural soils. Our results suggest that organic P (Porg), rather than available P, is the most important P fraction in predicting phosphatase activity. Structural equation modeling using soil total nitrogen (TN), mean annual precipitation, mean annual temperature, thermal amplitude and total soil carbon as most available predictor variables explained up to 50% of the spatial variance in phosphatase activity. In this analysis, Porg could not be tested and among the rest of available variables, TN was the most important factor explaining the observed spatial gradients in phosphatase activity. On the other hand, phosphatase activity was also found to be associated with climatic conditions and soil type across different biomes worldwide. The close association among different predictors like Porg, TN and precipitation suggest that P recycling is driven by a broad scale pattern of ecosystem productivity capacity

Estimating the health and economic burden of shipping related air pollution in the Iberian Peninsula

Air pollution is the leading cause of the global burden of disease from the environment, entailing substantial economic consequences. International shipping is a significant source of NOx, SO2, CO and PM, which can cause known negative health impacts. Thus, this study aimed to estimate the health impacts and the associated external costs of ship-related air pollution in the Iberian Peninsula for 2015. Moreover, the impact of CAP2020 regulations on 2015 emissions was studied. Log-linear functions based on WHO-HRAPIE relative risks for PM2.5 and NO2 all-cause mortality and morbidity health end-points, and integrated exposure-response functions for PM2.5 cause-specific mortality, were used to calculate the excess burden of disease. The number of deaths and years of life lost (YLL) due to NO2 ship-related emissions was similar to those of PM2.5 ship-related emissions. Estimated all-cause premature deaths attributable to PM2.5 ship-related emissions represented an average increase of 7.7% for the Iberian Peninsula when compared to the scenario without shipping contribution. Costs of around 9 100 million euro yr-1 (for value of statistical life approach - VSL) and 1 825 million euro yr(-1) (for value of life year approach - VOLY) were estimated for PM and NO2 all-cause burden of disease. For PM2.5 cause-specific mortality, a cost of around 3 475 million euro yr(-1) (for VSL approach) and 851 million euro yr(-1) (for VOLY approach) were estimated. Costs due to PM and NO2 all-cause burden represented around 0.72% and 0.15% of the Iberian Peninsula gross domestic product in 2015, respectively for VSL and VOLY approaches. For PM2.5 cause-specific mortality, costs represented around 0.28% and 0.06%, respectively, for VSL and VOLY approaches. If CAP2020 regulations had been applied in 2015, around 50% and 30% respectively of PM2.5 and NO2 ship-related mortality would been avoided. These results show that air pollution from ships has a considerable impact on health and associated costs affecting the Iberian Peninsula.This work was financially supported by: project UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy - LEPABE-funded by national funds through the FCT/MCTES (PIDDAC) and project EMISSHIP PTDC/CTAAMB/32201/2017, funded by FEDER funds through COMPETE2020 - Programa Oper-acional Competitividade e Internacionalizacao (POCI) and by national funds (PIDDAC) through FCT/MCTES. Rafael A.O. Nunes thanks the individual research grant SFRH/BD/146159/2019, funded by the Por-tuguese Foundation for Science and Technology (FCT) . Sofia I.V. Sousathanks the Portuguese Foundation for Science and Technology (FCT) for the financial support of her work contract through the Scientific Employment Stimulus-Individual Call CEECIND/02477/2017. Dr Jalkanen would like to acknowledge the financial support from the European Union's Horizon2020 research and innovation programme under grant agreement #874990 (EMERGE project) . This work reflects only the authors' view and INEA is not responsible for any use that may be made of the information it contains

How nitrogen and phosphorus availability change water use efficiency in a Mediterranean savanna ecosystem

Nutrient availability, especially of nitrogen (N) and phosphorus (P), is of major importance for every organism and at a larger scale for ecosystem functioning and productivity. Changes in nutrient availability and potential stoichiometric imbalance due to anthropogenic nitrogen deposition might lead to nutrient deficiency or alter ecosystem functioning in various ways. In this study, we present 6 years (2014–2020) of flux-, plant-, and remote sensing data from a large-scale nutrient manipulation experiment conducted in a Mediterranean savanna-type ecosystem with an emphasis on the effects of N and P treatments on ecosystem-scale water-use efficiency (WUE) and related mechanisms. Two plots were fertilized with N (NT, 16.9 Ha) and N + P (NPT, 21.5 Ha), and a third unfertilized plot served as a control (CT). Fertilization had a strong impact on leaf nutrient stoichiometry only within the herbaceous layer with increased leaf N in both fertilized treatments and increased leaf P in NPT. Following fertilization, WUE in NT and NPT increased during the peak of growing season. While gross primary productivity similarly increased in NT and NPT, transpiration and surface conductance increased more in NT than in NPT. The results show that the NPT plot with higher nutrient availability, but more balanced N:P leaf stoichiometry had the highest WUE. On average, higher N availability resulted in a 40% increased leaf area index (LAI) in both fertilized treatments in the spring. Increased LAI reduced aerodynamic conductance and thus evaporation at both fertilized plots in the spring. Despite reduced evaporation, annual evapotranspiration increased by 10% (48.6 ± 28.3 kg H2O m−2), in the NT plot, while NPT remained similar to CT (−1%, −6.7 ± 12.2 kgH2O m−2). Potential causes for increased transpiration at NT could be increased root biomass and thus higher water uptake or rhizosphere priming to increase P-mobilization through microbes. The annual net ecosystem exchange shifted from a carbon source in CT (75.0 ± 20.6 gC m−2) to carbon-neutral in both fertilized treatments [−7.0 ± 18.5 gC m−2 (NT) 0.4 ± 22.6 gC m−2 (NPT)]. Our results show, that the N:P stoichiometric imbalance, resulting from N addition (without P), increases the WUE less than the addition of N + P, due to the strong increase in transpiration at NT, which indicates the importance of a balanced N and P content for WUE

Similar local, but different systemic, metabolomic responses of closely related pine subspecies to folivory by caterpillars of the processionary moth

ABSTRACT Plants respond locally and systemically to herbivore attack. Most of the research conducted on plant-herbivore relationships at element and molecular levels have focused on the elemental composition or/and certain molecular compounds or specific families of defence metabolites showing that herbivores tend to select plant individuals or species with higher nutrient concentrations and avoid those with higher levels of defence compounds. We performed stoichiometric and metabolomics, both local and systemic, analyses in two subspecies of Pinus sylvestris under attack from caterpillars of the pine processionary moth, an important pest in the Mediterranean Basin. Both pine subspecies responded locally to folivory mainly by increasing relative concentrations of terpenes and some phenolics. Systemic responses differed between pine subspecies, and most of the metabolites presented intermediate concentrations between those of the affected parts and unattacked trees. Our results support the hypothesis that foliar nutrient concentrations are not a key factor for plant selection by adult female processionary moths for oviposition, since folivory was not associated with any of the elements analysed. Phenolic compounds generally did not increase in the attacked trees, questioning the suggestion of induction of phenolics following folivory attack and the anti-feeding properties of phenolics. Herbivory attack produced a general systemic shift in pines, in both primary and secondary metabolism, which was less intense and chemically different from the local responses. Local pine responses were similar between pine subspecies, while systemic responses were more distant

Similar local, but different systemic, metabolomic responses of closely related pine subspecies to folivory by caterpillars of the processionary moth

ABSTRACT Plants respond locally and systemically to herbivore attack. Most of the research conducted on plant-herbivore relationships at element and molecular levels have focused on the elemental composition or/and certain molecular compounds or specific families of defence metabolites showing that herbivores tend to select plant individuals or species with higher nutrient concentrations and avoid those with higher levels of defence compounds. We performed stoichiometric and metabolomics, both local and systemic, analyses in two subspecies of Pinus sylvestris under attack from caterpillars of the pine processionary moth, an important pest in the Mediterranean Basin. Both pine subspecies responded locally to folivory mainly by increasing relative concentrations of terpenes and some phenolics. Systemic responses differed between pine subspecies, and most of the metabolites presented intermediate concentrations between those of the affected parts and unattacked trees. Our results support the hypothesis that foliar nutrient concentrations are not a key factor for plant selection by adult female processionary moths for oviposition, since folivory was not associated with any of the elements analysed. Phenolic compounds generally did not increase in the attacked trees, questioning the suggestion of induction of phenolics following folivory attack and the anti-feeding properties of phenolics. Herbivory attack produced a general systemic shift in pines, in both primary and secondary metabolism, which was less intense and chemically different from the local responses. Local pine responses were similar between pine subspecies, while systemic responses were more distant

Dendritic cells delivered inside human carcinomas are sequestered by interleukin-8

In the course of a clinical trial consisting of intratumoral injections of dendritic cells (DCs) transfected to produce interleukin-12, the use of (111)In-labeled tracing doses of DCs showed that most DCs remained inside tumor tissue, instead of migrating out. In search for factors that could explain this retention, it was found that tumors from patients suffering hepatocellular carcinoma, colorectal or pancreatic cancer were producing IL-8 and that this chemokine attracted monocyte-derived dendritic cells that uniformly express both IL-8 receptors CXCR1 and CXCR2. Accordingly, neutralizing antihuman IL-8 monoclonal antibodies blocked the chemotactic attraction of DCs by recombinant IL-8, as well as by the serum of the patients or culture supernatants of human colorectal carcinomas. In addition, tissue culture supernatants of colon carcinoma cells inhibited DC migration induced by MIP-3beta in an IL-8-dependent fashion. IL-8 production in malignant tissue and the responsiveness of DCs to IL-8 are a likely explanation of the clinical images, which suggest retention of DCs inside human malignant lesions. Impairment of DC migration toward lymphoid tissue could be involved in cancer immune evasion