Fate Factors Research Articles

Metal toxicity characterization factors for marine ecosystems—considering the importance of the estuary for freshwater emissions

The study develops site-dependent characterization factors (CFs) for marine ecotoxicity of metals emitted to freshwater, taking their passage of the estuary into account. To serve life cycle assessment (LCA) studies where emission location is often unknown, site-generic marine CFs were developed for metal emissions to freshwater and coastal seawater, respectively. The new CFs were applied to calculate endpoint impact scores for the same amount of metal emission to each compartment, to compare the relative ecotoxicity damages in freshwater and marine ecosystems in LCA. Site-dependent marine CFs for emission to freshwater were calculated for 64 comparatively independent seas (large marine ecosystems, LMEs). The site-dependent CF was calculated as the product of fate factor (FF), bioavailability factor (BF), and effect factor (EF). USEtox modified with site-dependent parameters was extended with an estuary removal process to calculate FF. BF and EF were taken from Dong et al. Environ Sci Technol 50:269–278 (2016). Site-generic marine CFs were derived from site-dependent marine CFs. Different averaging principles were tested, and the approach representing estuary discharge rate was identified as the best one. Endpoint marine and freshwater metals CFs were developed to calculate endpoint ecotoxicity impact scores. Marine ecotoxicity CFs are 1.5 orders of magnitude lower for emission to freshwater than for emission to seawater for Cr, Cu, and Pb, due to notable removal fractions both in freshwater and estuary. For the other metals, the difference is less than half an order of magnitude, mainly due to removal in freshwater. The site-dependent CFs generally vary within two orders of magnitude around the site-generic CF. Compared to USES-LCA 2.0 CFs (egalitarian perspective), the new site-generic marine CFs for emission to seawater are 1–4 orders of magnitude lower except for Pb. The new site-generic marine CFs for emission to freshwater lie within two orders of magnitude difference from USES-LCA 2.0 CFs. The comparative contribution share analysis shows a poor agreement of metal toxicity ranking between both methods. Accounting for estuary removal particularly influences marine ecotoxicity CFs for emission to freshwater of metals that have a strong tendency to complex-bind to particles. It indicates the importance of including estuary in the characterization modelling when dealing with those metals. The resulting endpoint ecotoxicity impact scores are 1–3 orders of magnitude lower in seawater than in freshwater for most metals except Pb, illustrating the higher sensitivity of freshwater ecosystems to metal emissions, largely due to the higher species density there.

Motion Capture Depends Upon the Common Fate Factor Among Elements.

When observers move the head backwards and forwards while fixating on the center of the concentric circles that consist of oblique lines, they see illusory rotation of those circles. If several dots are superimposed on the proximity to the inner concentric circles, observers see the illusory rotation not only for the circles but also for the superimposed dots. This illusory rotation of the dots is based on motion capture. In this study, in order to understand the basis of the motion capture, we examined how motion signal with different directions (rotation, expansion/contraction, and horizontal translation) in terms of motion on a display, as well as illusory motion signal from the oblique components, affects the motion capture. If the stimulus presented rotation with expansion/contraction, or rotation with horizontal translation for the entire stimulus, then observers tended to perceive motion capture for the superimposed dots. However, if the stimulus presented only rotation of the circles, then observers tended to perceive induced motion for the superimposed dots. These results suggest that the existences of the common fate factor for the entire stimulus determine the means of allocating and integrating the motion signal in each element in the stimulus to generate motion capture.

Spatially explicit fate factors of waterborne nitrogen emissions at the global scale

Marine eutrophication impacts due to waterborne nitrogen (N) emissions may vary significantly with their type and location. The environmental fate of dissolved inorganic nitrogen (DIN) forms is essential to understand the impacts they may trigger in receiving coastal waters. Current life cycle impact assessment (LCIA) methods apply fate factors (FFs) with limited specificity of DIN emission routes, and often lack spatial differentiation and global applicability. This paper describes a newly developed method to estimate spatially explicit FFs for marine eutrophication at a global scale and river basin resolution. The FF modelling work includes DIN removal processes in both inland (soil and river) and marine compartments. Model input parameters are the removal coefficients extracted from the Global NEWS 2-DIN model and residence time of receiving coastal waters. The resulting FFs express the persistence of the fraction of the original DIN emission in the receiving coastal large marine ecosystems (LMEs). The method further discriminates three DIN emission routes, i.e., diffuse emission from soils, and direct point emissions to freshwater or marine water. Based on modelling of individual river basins, regionally aggregated FFs are calculated as emission-weighted averages. Among 5772 river basins of the world, the calculated FFs show 5 orders of magnitude variation for the soil-related emission route, 3 for the river-related, and 2 for emissions to marine water. Spatial aggregation of the FFs at the continental level decreases this variation to 1 order of magnitude or less for all routes. Coastal water residence time was found to show inconsistency and scarcity of literature sources. Improvement of data quality for this parameter is suggested. With the proposed method and factors, spatial information of DIN emissions can be used to improve the environmental relevance and the discriminatory power of the assessment of marine eutrophication impacts in a geographically differentiated characterization model at a global scale.

Arsenic mobilization in shallow aquifers due to CO2 and brine intrusion from storage reservoirs

We developed an integrated framework of combined batch experiments and reactive transport simulations to quantify water-rock-CO2 interactions and arsenic (As) mobilization responses to CO2 and/or saline water leakage into USDWs. Experimental and simulation results suggest that when CO2 is introduced, pH drops immediately that initiates release of As from clay minerals. Calcite dissolution can increase pH slightly and cause As re-adsorption. Thus, the mineralogy of the USDW is ultimately a determining factor of arsenic fate and transport. Salient results suggest that: (1) As desorption/adsorption from/onto clay minerals is the major reaction controlling its mobilization, and clay minerals could mitigate As mobilization with surface complexation reactions; (2) dissolution of available calcite plays a critical role in buffering pH; (3) high salinity in general hinders As release from minerals; and (4) the magnitude and quantitative uncertainty of As mobilization are predicated on the values of reaction rates and surface area of calcite, adsorption surface areas and equilibrium constants of clay minerals, and cation exchange capacity. Results of this study are intended to improve ability to quantify risks associated with potential leakage of reservoir fluids into shallow aquifers, in particular the possible environmental impacts of As mobilization at carbon sequestration sites.

Characterization of waterborne nitrogen emissions for marine eutrophication modelling in life cycle impact assessment at the damage level and global scale

Current life cycle impact assessment (LCIA) methods lack a consistent and globally applicable characterization model relating nitrogen (N, as dissolved inorganic nitrogen, DIN) enrichment of coastal waters to the marine eutrophication impacts at the endpoint level. This paper introduces a method to calculate spatially explicit characterization factors (CFs) at endpoint and damage to ecosystems levels, for waterborne nitrogen emissions, reflecting their hypoxia-related marine eutrophication impacts, modelled for 5772 river basins of the world. The proposed method combines environmental fate factors (FFs) integrating (i) DIN removal processes in soils and rivers, based on the NEWS 2-DIN model, and in coastal waters, based on water residence time; (ii) coastal ecosystem exposure (XF) to N enrichment, based on biological cycling processes; and (ii) effect factors (EFs) based on species sensitivity to hypoxia. Three emission routes are discriminated as N from soil and N in emissions to river and to coastal waters. Damage factors (DFs) are also estimated, based on endpoint metric conversion from potentially affected to potentially disappeared fractions of species (i.e. potentially affected fraction (PAF) to PDF m3 year kg N−1) and harmonization across coastal ecosystems based on spatially explicit density of demersal species, to further express CFs as species year per kilogram N−1. Endpoint CFs show 6 orders of magnitude (o.m.) spatial differentiation amongst the river basins for the soil emission route, 4 for the river and 2 for emissions to coastal waters. Damage CFs vary 7, 5 and 3 o.m. for the same routes. After aggregation at the level of continents, maximum CFs and DFs are consistently found in Europe, but the aggregation reduces spatial differentiation to 1 o.m. for each route in both factors. The FFNsoil and species density terms are responsible for most of the spatial differentiation of the damage model. Uncertainty is higher for the residence time term used in the FF model, due to scarcity and inconsistency of data sources, the assumptions of representativeness of DIN persistence and removal rates. Major contributions to the current state-of-the-art of marine eutrophication characterization modelling are (i) full pathway coverage, thus reaching damage level; (ii) significant increase in geographic coverage; (iii) mechanistic modelling of exposure and effect factors; and (iv) application of spatially explicit damage to ecosystems factors based on species densities. Application of the developed CFs in life cycle impact assessment is recommended at a river basin scale, provided that emission location is known.

Freshwater Sediment Characterization Factors of Copper Oxide Nanoparticles

Wide use of engineered nanoparticles (ENPs) is likely to result in the eventually accumulation of ENPs in sediment. The benthic organisms living in sediments may suffer relatively high toxic effects of ENPs. This study has selected copper oxide nanoparticles (nano-CuO) as a research object. To consider the impacts of spatial heterogeneity on ENPs toxicity, the characterization factor (CF) derived from life cycle assessment (LCA) methodology is used as an indicator in this study. A nano-specific fate model has been used to calculate the freshwater sediment fate factor (FF) of nano-CuO. A literature survey of the nano-CuO toxicology values has been performed to calculate the effect factor (EF). Seventeen freshwater sediment CFs of nano-CuO are proposed as recommended values for subcontinental regions. The region most likely to be affected by nano-CuO is northern Australia (CF of 21.01·103 CTUe, comparative toxic units) and the least likely is northern Europe and northern Canada (CF of 8.55·103 CTUe). These sediment CFs for nano-CuO could be used in the future when evaluating the ecosystem impacts of products containing nano-CuO by LCA method.

Illusory rotation and motion capture depend upon common fate factor among elements.

Illusory rotation and motion capture depend upon common fate factor among elements.

Fate and Characterization Factors of Nanoparticles in Seventeen Subcontinental Freshwaters: A Case Study on Copper Nanoparticles.

The lack of characterization factors (CFs) for engineered nanoparticles (ENPs) hampers the application of life cycle assessment (LCA) methodology in evaluating the potential environmental impacts of nanomaterials. Here, the framework of the USEtox model has been selected to solve this problem. On the basis of colloid science, a fate model for ENPs has been developed to calculate the freshwater fate factor (FF) of ENPs. We also give the recommendations for using the hydrological data from the USEtox model. The functionality of our fate model is proved by comparing our computed results with the reported scenarios in North America, Switzerland, and Europe. As a case study, a literature survey of the nano-Cu toxicology values has been performed to calculate the effect factor (EF). Seventeen freshwater CFs of nano-Cu are proposed as recommended values for subcontinental regions. Depending on the regions and the properties of the ENPs, the region most likely to be affected by nano-Cu is Africa (CF of 11.11 × 10(3) CTUe, comparative toxic units) and the least likely is north Australia (CF of 3.87 × 10(3) CTUe). Furthermore, from the sensitivity analysis of the fate model, 13 input parameters (such as depth of freshwater, radius of ENPs) show vastly different degrees of influence on the outcomes. The characterization of suspended particles in freshwater and the dissolution rate of ENPs are two significant factors.

Bioextraction potential of seaweed in Denmark — An instrument for circular nutrient management

The aim of the study is to assess the efficacy of seaweed for circular nutrient management to reduce eutrophication levels in the aquatic environment. We performed a comparative Life Cycle Assessment (LCA) of two reference waste management systems treating seaweed as biowaste, i.e. landfill disposal and combustion, and an alternative scenario using the seaweed Saccharina latissima as a resource for biobased fertilizer production. Life Cycle Impact Assessment (LCIA) methods were improved by using a cradle-to-cradle approach, quantifying fate factors for nitrogen and phosphorus loss from fertilized agriculture to the aquatic environment. We also differentiated between nitrogen- and phosphorus-limited marine water to improve the traditional freshwater impact category, making this indicator suitable for decision support in relation to coastal water management schemes. Offshore cultivation of Saccharina latissima with an average productivity of 150Mg/km2 in Danish waters in 2014 was applied to a cultivation scenario of 208km2. The bioresource scenario performs better than conventional biowaste management systems, delivering a net reduction in aquatic eutrophication levels of 32.29kgNeq. and 16.58kgPO43−eq. per Mg (dry weight) of seaweed, quantified by the ReCiPe and CML impact assessment methods, respectively. Seaweed cultivation, harvest and reuse of excess nutrients from the aquatic environment is a promising approach for sustainable resource cycling in a future regenerative economy that exploits manmade emissions as a resource for closed loop biobased production while significantly reducing eutrophication levels in 3 out of 7 Danish river basin districts. We obtained at least 10% bioextraction of phosphorus manmade emissions (10%, 89% and >100%) and contributed significantly to local nitrogen reduction goals according to the Water Framework Directive (23%, 78% and >100% of the target).

Spatial variability versus parameter uncertainty in freshwater fate and exposure factors of chemicals

We compared the influence of spatial variability in environmental characteristics and the uncertainty in measured substance properties of seven chemicals on freshwater fate factors (FFs), representing the residence time in the freshwater environment, and on exposure factors (XFs), representing the dissolved fraction of a chemical. The influence of spatial variability was quantified using the SimpleBox model in which Europe was divided in 100 × 100 km regions, nested in a regional (300 × 300 km) and supra-regional (500 × 500 km) scale. Uncertainty in substance properties was quantified by means of probabilistic modelling. Spatial variability and parameter uncertainty were expressed by the ratio k of the 95%ile and 5%ile of the FF and XF. Our analysis shows that spatial variability ranges in FFs of persistent chemicals that partition predominantly into one environmental compartment was up to 2 orders of magnitude larger compared to uncertainty. For the other (less persistent) chemicals, uncertainty in the FF was up to 1 order of magnitude larger than spatial variability. Variability and uncertainty in freshwater XFs of the seven chemicals was negligible (k < 1.5). We found that, depending on the chemical and emission scenario, accounting for region-specific environmental characteristics in multimedia fate modelling, as well as accounting for parameter uncertainty, can have a significant influence on freshwater fate factor predictions. Therefore, we conclude that it is important that fate factors should not only account for parameter uncertainty, but for spatial variability as well, as this further increases the reliability of ecotoxicological impacts in LCA.

Characterization factors for zinc terrestrial ecotoxicity including speciation

Ignoring metal speciation in the determination of characterization factors (CFs) in life cycle assessment (LCA) could significantly alter the validity of LCA results since toxicity is directly linked to bioavailability. Zinc terrestrial ecotoxicity CFs are obtained using modified USEtox fate factors, WHAM 6.0-derived bioavailable factors, and effect factors calculated using the assessment of mean impact (AMI) method with available terrestrial ecotoxicity data. Soil archetypes created using influent soil properties on Zn speciation (soil texture, pH, cation exchange capacity, organic matter and carbonate contents) are used to group soils of the world into a more manageable spatial resolution for LCA. An aggregated global CF value is obtained using population density as a Zn emission proxy. Results are presented in a world map to facilitate use. When using soluble Zn as the bioavailable fraction, CF values vary over 1.76 orders of magnitude, indicating that a single aggregated value could reasonably be used for the world. When using true solution Zn, CFs cover 14 orders of magnitude. To represent this variability, 518 archetypes and 13 groups of archetypes were created. Aggregated global default values are 4.58 potentially affected fraction of species (PAF) m3·day kg−1 for soluble Zn and 1.45 PAF m3·day kg−1 for true solution Zn. These values are respectively 28 and 88 times lower than the Zn terrestrial CF in IMPACT 2002 (128 PAF m3·day kg−1). The CFs obtained for Zn, except for soluble Zn, are at least 2 orders of magnitude lower than current CFs. However, they must be tested in case studies to measure the impact of including Zn speciation in the CF definition of terrestrial ecotoxicity.

Fate factors and emission flux estimates for emerging contaminants in surface waters

Pharmaceuticals, personal care products, hormones, and wastewater products are emerging environmental concerns for manifold reasons, including the potential of some compounds found in these products for endocrine disruption at a very low chronic exposure level. The environmental occurrences and sources of these contaminants in the water, soil, sediment and biota in European nations and the United States are well documented. This work reports a screening-level emission and fate assessment of thirty compounds, listed in the National Reconnaissance of the United States Geological Survey (USGS, 1999–2000) as the most frequently detected organic wastewater contaminants in U.S. streams and rivers. Estimations of the surface water fate factors were based on Level II and Level III multimedia fugacity models for a 1000 km 2 model environment, the size of a typical county in the eastern United States. The compounds are categorized into three groups based upon the sensitivity of their predicted surface water fate factors to uncertainties in their physicochemical property values and the landscape parameters. The environmental fate factors, mass distributions, and loss pathways of all of the compounds are strongly affected by their assumed modes of entry into the environment. It is observed that for thirteen of the thirty organic wastewater contaminants most commonly detected in surface waters, conventional treatment strategies may be ineffective for their removal from wastewater effluents. The surface water fate factors predicted by the fugacity models were used in conjunction with the surface water concentrations measured in the USGS reconnaissance to obtain emission flux estimates for the compounds into U.S. streams and rivers. These include estimated fluxes of 6.8 × 10 −5 to 0.30 kg/h km 2 for the biomarker coprostanol; 1.7 × 10 −5 to 6.5 × 10 −5 kg/h km 2 for the insect repellent N,N-diethyltoluamide; and 4.3 × 10 −6 to 3.1 × 10 −5 kg/h km 2 for the steroid estriol.

Cellular modulation by the elasticity of biomaterials.

The behaviors and functions of individual cells, fundamental to the complexity of multicellular organisms, are regulated by their integrated response to a variety of environmental cues such as soluble factors, extracellular matrix (ECM)-mediated signals, and cell-cell interactions. Among these cues, the biomechanical feature of the ECM, represented by its elasticity, has been increasingly recognized as a dominating factor of cell fate. This review article aims to provide an overview of the general principles and recent advances in the field of matrix elasticity-dependent regulation of cellular activities and functions, the underlying biomechanical and molecular mechanisms, as well as pathophysiological implications. A discussion is also provided as to how material design strategies can be used to control the local microenvironment of stem cells to direct their lineage commitment and functions toward tissue development and regeneration.

Protocol for Placental Precursors

The cells that give rise to the embryonic portion of the placenta, trophoblast stem cells, have been created from mouse fibroblasts, according to two new reports. The first differentiation event of the mammalian embryo separates the inner cell mass of the blastula—the embryo proper—from the outer layer of trophectoderm, which can give rise to trophoblast stem cells in culture. Studies of such stem cells have implicated a growing suite of transcription factors in trophoblast cell fate. In the new studies, combinations of these transcription factors were expressed ectopically in embryonic and adult mouse fibroblasts, generating a cocktail that could convert them into trophoblast stem cells. Caroline Kubaczka et al. [1] homed in on four of these factors (Tfap2c, Eomes, Gata3, and Ets2), and Hana Benchetrit et al. [2] used three (Tfap2c, Eomes, and Gata3), although a fourth factor—Myc—seemed to boost the efficiency of their protocol. Both groups converted embryonic and mouse fibroblasts into cells that expressed markers of trophoblast cells and had correct morphology; these stem cells could be maintained in culture for many generations after the initiating factors were withdrawn. Both groups analyzed, in detail, the stem cells derived from embryonic fibroblasts. These stem cells had gene expression profiles, and DNA methylation and other epigenetic characteristics—similar to trophoblast stem cells derived from blastocysts—could differentiate into trophoblast tissue and form placental tissue when implanted into blastocysts. The cellular conversions occurred in the absence of a common middle step: the generation of an induced pluripotent stem cell. The findings show that it is possible to convert, directly, a differentiated cell type (fibroblast) into another cell type (trophoblast stem cell), apparently without transiting through a pluripotent cell state. The research may also lead to protocols that generate human trophoblast stem cells—an elusive goal.

Subtracted Dynamic MR Perfusion Source Images (sMRP-SI) provide Collateral Blood Flow Assessment in MCA Occlusions and Predict Tissue Fate.

Collateral blood flow is accepted as a predictive factor of tissue fate in ischemic stroke. Thus, we aimed to evaluate a new method derived from MR perfusion source images to assess collateral flow in patients with ICA/MCA occlusions. A total of 132 patients of the prospective 1000+ study were examined. MR perfusion source images were assessed according to Δimg_n = img_n + 1 - img_n - 1 using the five-grade Higashida collateral flow rating system. Higashida scores were correlated to mismatch (MM) volume, mismatch ratio, day 6 FLAIR lesion volumes and day 90 mRS. Patients with Higashida scores 3 and 4 had significantly lower admission NIHSS, smaller FLAIR day 6 lesion volumes (p < 0.001) and higher rates of better long-term outcome (mRS 0-2, p = 0.002). There was a linear trend for the association of Higashida grade 1 (p = 0.002) and 2 (p = 0.001) with unfavourable outcome (day 90 mRS 3-6), but no significant association was found for MM volume, MM ratio and day 90 mRS. Inter-rater agreement was 0.58 (95% CI 0.43-0.73) on day 1, 0.70 (95% CI 0.58-0.81) on day 2. sMRP-SI Higashida score offers a non-invasive collateral vessel and tissue perfusion assessment of ischemic tissue. The predictive value of Higashida rating proved superior to MM with regard to day 90 mRS. • Assessment of collateral flow using subtracted dynamic MR perfusion source imaging (sMRP-SI). • sMRP-SI offers additional information about morphological characteristics of ischemic brain tissue. • sMRP-SI collateral flow assessment proves superior to mismatch volume. • Better collateral flow was significantly associated with better outcome (day 90 mRS).

Shox2 is required for the proper development of the facial motor nucleus and the establishment of the facial nerves.

BackgroundAxons from the visceral motor neurons (vMNs) project from nuclei in the hindbrain to innervate autonomic ganglia and branchial arch-derived muscles. Although much is known about the events that govern specification of somatic motor neurons, the genetic pathways responsible for the development of vMNs are less well characterized. We know that vMNs, like all motor neurons, depend on sonic hedgehog signaling for their generation. Similarly, the paired-like homeobox 2b (Phox2b) gene, which is expressed in both proliferating progenitors and post-mitotic motor neurons, is essential for the development of vMNs. Given that our previous study identified a novel role for the short stature homeobox 2 (Shox2) gene in the hindbrain, and since SHOX2 has been shown to regulate transcription of islet 1 (Isl1), an important regulator of vMN development, we sought to determine whether Shox2 is required for the proper development of the facial motor nucleus.ResultsUsing a Nestin-Cre driver, we show that elimination of Shox2 throughout the brain results in elevated cell death in the facial motor nucleus at embryonic day 12.5 (E12.5) and E14.5, which correlates with impaired axonal projection properties of vMNs. We also observed changes in the spatial expression of the vMN cell fate factors Isl1 and Phox2b, and concomitant defects in Shh and Ptch1 expression in Shox2 mutants. Furthermore, we demonstrate that elimination of Shox2 results in the loss of dorsomedial and ventromedial subnuclei by postnatal day 0 (P0), which may explain the changes in physical activity and impaired feeding/nursing behavior in Shox2 mutants.ConclusionsCombined, our data show that Shox2 is required for development of the facial motor nucleus and its associated facial (VII) nerves, and serves as a new molecular tool to probe the genetic programs of this understudied hindbrain region.Electronic supplementary materialThe online version of this article (doi:10.1186/s12868-015-0176-0) contains supplementary material, which is available to authorized users.

Environmental impacts of thermal emissions to freshwater: spatially explicit fate and effect modeling for life cycle assessment and water footprinting

Thermal emissions from electric power generation plants can lead to environmental impacts. However, such emissions have neither been comprehensively integrated in life cycle assessment (LCA), a method to quantify environmental impacts throughout the life cycle of a product, nor in water footprinting. This study presents a spatially explicit (0.5 arc degree resolution) fate and effect model for assessing the impact of thermal emissions from power production in the USA on freshwater ecosystems. We developed a two-step regionalized fate model to capture short-range and long-range thermal effects. Effect factors were derived as a function of ambient temperature and used in conjunction with the fate factor to calculate the impacts. The impacts are measured as the potentially disappeared fraction (PDF) of species in the affected freshwater ecosystem volume over time. The long-range freshwater ecosystem impacts are dependent on the distance to sea as well as the ambient temperature, while the short-range effects are mainly influenced by the induced temperature change at the point of mixing. Our analysis showed that 95 % of the modeled grid cells in the USA have an impact of 2.5 × 10−6 to 2.5 × 10−4 PDF m3 years per MJ emitted heat. For natural gas power production, thermal pollution can have a significant contribution to total freshwater ecosystem quality. This study shows that thermal effects can be calculated on a spatially explicit level based on background data. It reveals the variability within a large region of the world, covering various geographic regions, and therefore helps generalizing the results for other regions.

Chemical footprint method for improved communication of freshwater ecotoxicity impacts in the context of ecological limits.

The ecological footprint method has been successful in communicating environmental impacts of anthropogenic activities in the context of ecological limits. We introduce a chemical footprint method that expresses ecotoxicity impacts from anthropogenic chemical emissions as the dilution needed to avoid freshwater ecosystem damage. The indicator is based on USEtox characterization factors with a modified toxicity reference point. Chemical footprint results can be compared to the actual dilution capacity within the geographic vicinity receiving the emissions to estimate whether its ecological limit has been exceeded and hence whether emissions can be expected to be environmentally sustainable. The footprint method was illustrated using two case studies. The first was all inventoried emissions from European countries and selected metropolitan areas in 2004, which indicated that the dilution capacity was likely exceeded for most European countries and all landlocked metropolitan areas. The second case study indicated that peak application of pesticides alone was likely to exceed Denmark's freshwater dilution capacity in 1999-2011. The uncertainty assessment showed that better spatially differentiated fate factors would be useful and pointed out other major sources of uncertainty and some opportunities to reduce these.

Growth differentiation factor 11 is an encephalic regionalizing factor in neural differentiated mouse embryonic stem cells.

BackgroundThe central nervous system has a complex structural organization and consists of different subdomains along the antero-posterior axis. However, questions remain about the molecular mechanisms leading to the regionalization of this organ. We used a previously developed methodology to identify the novel patterning role of GDF11, a TGF-β signaling factor.FindingsUsing an assay based on neural differentiated mouse embryonic stem cells, GDF11 is shown to induce diencephalic (posterior forebrain), mesencephalic (midbrain) and metencephalic (anterior hindbrain) fates at the expense of telencephalic (anterior forebrain) specification. GDF11 has not previously been implicated in the early patterning of the nervous system. In addition, inhibition of the TGF-β type I receptors Alk4, Alk5 and Alk7 by the pharmacological inhibitor SB431542 caused a strong anteriorization of the cells.ConclusionsOur findings suggest that GDF11 is involved in the earliest steps of the brain patterning during neurogenesis in the vertebrate embryo and is shown to be a regionalizing factor of the regional fate in the developing brain. This regionalization is not a typical posteriorizing signal as seen with retinoic acid, FGF or BMP molecules. To our knowledge, this is the first time that GDF11 is implicated in the earliest steps of the patterning of the neural plate.

Characterization factors for terrestrial acidification at the global scale: A systematic analysis of spatial variability and uncertainty

Characterization factors (CFs) are used in life cycle assessment (LCA) to quantify the potential impact per unit of emission. CFs are obtained from a characterization model which assess the environmental mechanisms along the cause–effect chain linking an emission to its potential damage on a given area of protection, such as loss in ecosystem quality. Up to now, CFs for acidifying emissions did not cover the global scale and were only representative of their characterization model geographical scope. Consequently, current LCA practices implicitly assume that all emissions from a global supply chain occur within the continent referring to the characterization method geographical scope. This paper provides worldwide 2°×2.5° spatially-explicit CFs, representing the change in relative loss of terrestrial vascular plant species due to an emission change of nitrogen oxides (NOx), ammonia (NH3) and sulfur dioxide (SO2). We found that spatial variability in the CFs is much larger compared to statistical uncertainty (six orders of magnitude vs. two orders of magnitude). Spatial variability is mainly caused by the atmospheric fate factor and soil sensitivity factor, while the ecological effect factor is the dominant contributor to the statistical uncertainty. The CFs provided in our study allow the worldwide spatially explicit evaluation of life cycle impacts related to acidifying emissions. This opens the door to evaluate regional life cycle emissions of different products in a global economy.