Multicompartment Depletion Factors for Water Consumption on a Global Scale.

Balancing human communities' and ecosystems' need for freshwater is one of the major challenges of the 21st century as population growth and improved living conditions put increasing pressure on freshwater resources. While frameworks to assess the environmental impacts of freshwater consumption have been proposed at the regional scale, an operational method to evaluate the consequences of consumption on different compartments of the water system and account for their interdependence is missing at the global scale. Here, we develop depletion factors that simultaneously quantify the effects of water consumption on streamflow, groundwater storage, soil moisture, and evapotranspiration globally. We estimate freshwater availability and water consumption using the output of a global-scale surface water-groundwater model for the period 1960-2000. The resulting depletion factors are provided for 8,664 river basins, representing 93% of the landmass with significant water consumption, i.e., excluding Greenland, Antarctica, deserts, and permanently frozen areas. Our findings show that water consumption leads to the largest water loss in rivers, followed by aquifers and soil, while simultaneously increasing evapotranspiration. Depletion factors vary regionally with ranges of up to four orders of magnitude depending on the annual consumption level, the type of water used, aridity, and water transfers between compartments. Our depletion factors provide valuable insights into the intertwined effects of surface and groundwater consumption on several hydrological variables over a specified period. The developed depletion factors can be integrated into sustainability assessment tools to quantify the ecological impacts of water consumption and help guide sustainable water management strategies, while accounting for the performance limitations of the underlying model.

Ecotoxicity characterization of chemicals: Global recommendations and implementation in USEtox.

Chemicals emitted to the environment affect ecosystem health from local to global scale, and reducing chemical impacts has become an important element of European and global sustainability efforts. The present work advances ecotoxicity characterization of chemicals in life cycle impact assessment by proposing recommendations resulting from international expert workshops and work conducted under the umbrella of the UNEP-SETAC Life Cycle Initiative in the GLAM project (Global guidance on environmental life cycle impact assessment indicators). We include specific recommendations for broadening the assessment scope through proposing to introduce additional environmental compartments beyond freshwater and related ecotoxicity indicators, as well as for adapting the ecotoxicity effect modelling approach to better reflect environmentally relevant exposure levels and including to a larger extent chronic test data. As result, we (1) propose a consistent mathematical framework for calculating freshwater ecotoxicity characterization factors and their underlying fate, exposure and effect parameters; (2) implement the framework into the USEtox scientific consensus model; (3) calculate characterization factors for chemicals reported in an inventory of a life cycle assessment case study on rice production and consumption; and (4) investigate the influence of effect data selection criteria on resulting indicator scores. Our results highlight the need for careful interpretation of life cycle assessment impact scores in light of robustness of underlying species sensitivity distributions. Next steps are to apply the recommended characterization framework in additional case studies, and to adapt it to soil, sediment and the marine environment. Our framework is applicable for evaluating chemicals in life cycle assessment, chemical and environmental footprinting, chemical substitution, risk screening, chemical prioritization, and comparison with environmental sustainability targets.

Multiple Climate Tipping Points Metrics for Improved Sustainability Assessment of Products and Services.

Mounting evidence indicates that climate tipping points can have large, potentially irreversible, impacts on the earth system and human societies. Yet, climate change metrics applied in current sustainability assessment methods generally do not consider these tipping points, with the use of arbitrarily determined time horizons and assumptions that the climate impact of a product or service is independent of emission timing. Here, we propose a new method for calculating climate tipping characterization factors for greenhouse gases (carbon dioxide, methane, and nitrous oxide) at midpoint. It covers 13 projected tipping points, incorporates the effect that the crossing of a given tipping point has on accelerating the crossing of other tipping points, and addresses uncertainties in the temperature thresholds that trigger the tipping points. To demonstrate the added value of the new metric, we apply it to emissions stemming from end-of-life of plastic polymers and compare them with commonly used metrics. This highlights the need to consider climate tipping in sustainability assessment of products and services.

Globally differentiated effect factors for characterising terrestrial acidification in life cycle impact assessment.

To assess terrestrial ecosystems damages from acidification, life cycle impact assessment (LCIA) can be applied using characterisation factors, which integrate the quantification of adverse effects via effect factors (EFs), linking decreasing soil pH to declines in species richness. With a species coverage of 0.6%, the currently-existing EFs defined for 14 biomes carry important uncertainties and lack the appropriate spatial resolution to capture the effects of terrestrial acidification. In our study, we thus used georeferenced observational data with 113 million data points to develop a comprehensive, global inventory covering 189,185 vascular plant species, which is nearly 100 times more species than existing inventories used in LCIA (raising the species coverage to 49%). EFs were then calculated for 825 ecoregions. Great spatial variability is observed between ecoregions within a same biome spanning up to 3 orders of magnitude, and EFs developed at biome level tend to underestimate acidification effects. We find up to 2 orders of magnitude differences between our EFs and the ones currently recommended for use in LCIA. These results call for updating current LCIA practice to assess acidification impacts with our more differentiated and environmentally representative EFs and to implement our approach to other site-dependent environmental impacts where large georeferenced datasets exist.

Influence of metal speciation on soil ecotoxicity impacts in life cycle assessment.

It is unknown whether metallic elements remain important contributors to terrestrial ecotoxicity impact scores in life cycle assessment (LCA) when solid- and liquid-phase speciation are considered in environmental fate, exposure and effects. Here, a new speciation-based method for calculating comparative toxicity potentials (CTP) of 23 metallic elements in soils was compared with two other widely used methods which do not consider speciation (i.e., IMPACT, 2002+ and ReCiPe 2008) for nearly 13,000 life cycles of unit processes taken from different sectors. Differences in impact scores between method were driven either by differences in characterization models (ReCiPe 2008) or both by differences in characterization models and substance coverage (IMPACT, 2002+). Strong correlations (r > 0.98) and seemingly constant shifts in impact scores were found for those processes where one or few substances (usually metals) contributed most to total impact and there were large differences in CTPs between methods for these substances. Weaker correlations but often better agreement in impact scores were found for those processes where organic substances were dominant contributors to total impact. Our results suggest that metals are expected to remain important contributors to soil ecotoxicity impacts in LCA when speciation is considered.

Building national emission inventories for the energy sector: Implications for life cycle assessment and nations environmental footprinting.

Environmentally-extended multi-region input-output (EE-MRIO) models allow calculating environmental impacts of goods and services in a supply-chain perspective. However, current EE-MRIO databases only have limited coverage of toxic pollutant emissions. This limited coverage is caused by the fact that public emission databases currently provide a rather modest pollutant coverage, are restricted to a limited number of countries, and lack differentiation in terms of sectors. This therefore calls for alternative data sources and inventorying techniques. Using the production of heat and electricity as a case study, we investigate the usability of available process-based inventories like the ecoinvent database from the field of Life Cycle Assessment (LCA) to build national emission inventories of pollutants. We thus develop the ecoinvent-based National Energy-related Emission (ENEE) inventory, comprising a total of 231 airborne emissions and 87 waterborne emissions of pollutants from heat and electricity power plants in 140 countries over the period 1995-2014. Using the improved data sets, we demonstrate that extending the coverage of pollutants beyond the few commonly-reported ones, like greenhouse gases, has a significant influence on the quantification of other important environmental impacts such as ionizing radiation and impacts of toxic substances to freshwater ecosystems. The ENEE inventory is an important first step towards building comprehensive inventories of pollutant emissions from power and heat generation, thus enabling more complete assessments of the energy sector. It also exemplifies the gains that can be made when introducing process-based data to complement public national and sectoral data for life cycle assessments and nations environmental footprinting.

Delta Life Cycle Assessment of Regenerative Agriculture in a Sheep Farming System.

Regenerative agriculture is being used by a small number of innovative farmers in Australia and elsewhere, using a range of holistic methods that work with the land and climate, such as short duration time of controlled grazing with long rest periods for the paddock and higher proportions of aboveground biomass, to improve soil health and farm profitability. This paper uses a delta life cycle assessment, focusing only on the differences between regenerative and conventional production systems to assess the potential impact of regenerative agriculture on a full range of midpoint impact categories and end-point areas of protection for an extensive sheep system in Australia. We assess the potential improvement to the water, carbon, and biodiversity footprints of sheep production, and find that regenerative agriculture has the potential to improve environmental performance compared with current industrial agricultural practices. In particular, there seems to be considerable potential to offset a significant proportion of the on-farm climate change impacts through a combination of biosequestration in soils and aboveground biomass and using harvested biomass to offset fossil fuel use. The assessment highlights the need for additional data to confirm the findings and the potential contribution that regenerative agriculture can make to sustainability of ruminant livestock production. Integr Environ Assess Manag 2020;16:282-290. © 2019 SETAC.

How to bring absolute sustainability into decision-making: An industry case study using a Planetary Boundary-based methodology.

The Planetary Boundaries concept has emerged as a framework for articulating environmental limits, gaining traction as a basis for considering sustainability in business settings, government policy and international guidelines. There is emerging interest in using the Planetary Boundaries concept as part of life cycle assessment (LCA) for gauging absolute environmental sustainability. We tested the applicability of a novel Planetary Boundaries-based life cycle impact assessment methodology on a hypothetical laundry washing case study at the EU level. We express the impacts corresponding to the control variables of the individual Planetary Boundaries together with a measure of their respective uncertainties. We tested four sharing principles for assigning a share of the safe operating space (SoSOS) to laundry washing and assessed if the impacts were within the assigned SoSOS. The choice of sharing principle had the greatest influence on the outcome. We therefore highlight the need for more research on the development and choice of sharing principles. Although further work is required to operationalize Planetary Boundaries in LCA, this study shows the potential to relate impacts of human activities to environmental boundaries using LCA, offering company and policy decision-makers information needed to promote environmental sustainability.

Improving substance information in USEtox® , part 2: Data for estimating fate and ecosystem exposure factors.

The scientific consensus model USEtox® has been developed since 2003 under the auspices of the United Nations Environment Programme-Society of Environmental Toxicology and Chemistry Life Cycle Initiative as a harmonized approach for characterizing human and freshwater toxicity in life cycle assessment and other comparative assessment frameworks. Using physicochemical substance properties, USEtox quantifies potential human toxicity and freshwater ecotoxicity impacts by combining environmental fate, exposure, and toxicity effects information, considering multimedia fate and multipathway exposure processes. The main source to obtain substance properties for USEtox 1.01 and 2.0 is the Estimation Program Interface (EPI Suite™) from the US Environmental Protection Agency. However, since the development of the original USEtox substance databases, new chemical regulations have been enforced in Europe, such as the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) and the Plant Protection Products regulations. These regulations require that a chemical risk assessment for humans and the environment is performed before a chemical is placed on the European market. Consequently, additional physicochemical property data and new toxicological endpoints are now available for thousands of chemical substances. The aim of the present study was to explore the extent to which the new available data can be used as input for USEtox-especially for application in environmental footprint studies-and to discuss how this would influence the quantification of fate and exposure factors. Initial results show that the choice of data source and the parameters selected can greatly influence fate and exposure factors, leading to potentially different rankings and relative contributions of substances to overall human toxicity and ecotoxicity impacts. Moreover, it is crucial to discuss the relevance of the exposure factor for freshwater ecotoxicity impacts, particularly for persistent highly adsorbing and bioaccumulating substances. Environ Toxicol Chem 2017;36:3463-3470. © 2017 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Contributions of Local Farming to Urban Sustainability in the Northeast United States.

Food consumption is an important contributor to a city's environmental impacts (carbon emissions, land occupation, water use, etc.) Urban farming (UF) has been advocated as a means to increase urban sustainability by reducing food-related transport and tapping into local resources. Taking Boston as an illustrative Northeast U.S. city, we developed a novel method to estimate sub-urban, food-borne carbon and land footprints using multiregion-input-output modeling and nutritional surveys. Computer simulations utilizing primary data explored UF's ability to reduce these footprints using select farming technologies, building on previous city-scale UF assessments which have hitherto been dependent on proxy data for UF. We found that UF generated meagre food-related carbon footprint reductions (1.1-2.9% of baseline 2211 kg CO2 equivalents/capita/annum) and land occupation increases (<1% of baseline 9000 m2 land occupation/capita/annum) under optimal production scenarios, informing future evidence-based urban design and policy crafting in the region. Notwithstanding UF's marginal environmental gains, UF could help Boston meet national nutritional guidelines for vegetable intake, generate an estimated $160 million U.S. in revenue to growers and act as a pedagogical and community building tool, though these benefits would hinge on large-scale UF proliferation, likely undergirded by environmental remediation of marginal lands in the city.

Improving substance information in USEtox® , part 1: Discussion on data and approaches for estimating freshwater ecotoxicity effect factors.

The scientific consensus model USEtox® is recommended by the European Commission as the reference model to characterize life cycle chemical emissions in terms of their potential human toxicity and freshwater aquatic ecotoxicity impacts in the context of the International Reference Life Cycle Data System Handbook and the Environmental Footprint pilot phase looking at products (PEF) and organizations (OEF). Consequently, this model has been systematically used within the PEF/OEF pilot phase by 25 European Union industry sectors, which manufacture a wide variety of consumer products. This testing phase has raised some questions regarding the derivation of and the data used for the chemical-specific freshwater ecotoxicity effect factor in USEtox. For calculating the potential freshwater aquatic ecotoxicity impacts, USEtox bases the effect factor on the chronic hazard concentration (HC50) value for a chemical calculated as the arithmetic mean of all logarithmized geometric means of species-specific chronic median lethal (or effect) concentrations (L[E]C50). We investigated the dependency of the USEtox effect factor on the selection of ecotoxicological data source and toxicological endpoints, and we found that both influence the ecotoxicity ranking of chemicals and may hence influence the conclusions of a PEF/OEF study. We furthermore compared the average measure (HC50) with other types of ecotoxicity effect indicators, such as the lowest species EC50 or no-observable-effect concentration, frequently used in regulatory risk assessment, and demonstrated how they may also influence the ecotoxicity ranking of chemicals. We acknowledge that these indicators represent different aspects of a chemical's ecotoxicity potential and discuss their pros and cons for a comparative chemical assessment as performed in life cycle assessment and in particular within the PEF/OEF context. Environ Toxicol Chem 2017;36:3450-3462. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Assessment of Metal Toxicity in Marine Ecosystems: Comparative Toxicity Potentials for Nine Cationic Metals in Coastal Seawater.

This study is a first attempt to develop globally applicable and spatially differentiated marine comparative toxicity potentials (CTPs) or ecotoxicity characterization factors for metals in coastal seawater for use in life cycle assessment. The toxicity potentials are based exclusively on marine ecotoxicity data and take account of metal speciation and bioavailability. CTPs were developed for nine cationic metals (Cd, Cr(III), Co, Cu(II), Fe(III), Mn, Ni, Pb, and Zn) in 64 large marine ecosystems (LMEs) covering all coastal waters in the world. The results showed that the CTP of a specific metal varies 3-4 orders of magnitude across LMEs, largely due to different seawater residence times. Therefore, the highest toxicity potential for metals was found in the LMEs with the longest seawater residence times. Across metals, the highest CTPs were observed for Cd, Pb, and Zn. At the concentration levels occurring in coastal seawaters, Fe acts not as a toxic agent but as an essential nutrient and thus has CTPs of zero.

Assessing comparative terrestrial ecotoxicity of Cd, Co, Cu, Ni, Pb, and Zn: The influence of aging and emission source.

Metal exposure to terrestrial organisms is influenced by the reactivity of the solid-phase metal pool. This reactivity is thought to depend on the type of emission source, on aging mechanisms that are active in the soil, and on ambient conditions. Our work shows, that when controlling for soil pH or soil organic carbon, emission source occasionally has an effect on reactivity of Cd, Co, Cu, Ni, Pb and Zn emitted from various anthropogenic sources followed by aging in the soil from a few years to two centuries. The uncertainties in estimating the age prevent definitive conclusions about the influence of aging time on the reactivity of metals from anthropogenic sources in soils. Thus, for calculating comparative toxicity potentials of man-made metal contaminations in soils, we recommend using time-horizon independent accessibility factors derived from source-specific reactive fractions.

Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils.

Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC50(Cu(2+)), i.e., the negative logarithm of the EC50(Cu(2+)) activity to plant growth. The determined pEC50(Cu(2+)) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87% of the pEC50(Cu(2+)) variation according to the simple equation: pEC50(Cu(2+)) = 0.98 × pH + 345 × [DOC] - 0.27. Other soil characteristics, including the base cation concentrations (Na(+), K(+), Ca(2+), Mg(2+)), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu(2+)). Consequently, Cu toxicity, expressed as the negative log of the Cu(2+) activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.

Development of Comparative Toxicity Potentials of 14 cationic metals in freshwater.

Site-dependent and site-generic Comparative Toxicity Potentials (CTPs) (also known as Characterization Factors (CFs)) were calculated for 14 cationic metals (Al(III), Ba, Be, Cd, Co, Cr(III), Cs, Cu(II), Fe(II), Fe(III), Mn(II), Ni, Pb, Sr and Zn), to be applied in Life Cycle Impact Assessment. CTPs were calculated for 7 EU-archetypes, taking bioavailability and speciation pattern into account. The resulting site-dependent CTPs showed up to 2.4-6.5 orders of magnitude variation across archetypes for those metals that form stable hydroxyl compounds in slightly alkaline waters (Al(III), Be, Cr(III), Cu(II) and Fe(III)), emphasizing the importance of using site-dependent CTPs for these metals where possible. For the other metals, CTPs stayed within around 0.9 orders of magnitude, making spatial differentiation less important. In acidic waters (pH<6.4), Al(III) and Cu(II) had the highest CTPs, while Cd ranked highest in other waters. Based on the site-dependent CTPs, site-generic CTPs were developed applying different averaging principle. Emission weighted average of 7 EU-archetype CTPs was recommended as site-generic CTP for use in LCA studies, where receiving location is unclear. Compared to previous studies by Gandhi et al. (2010, 2011a), new site-dependent CTPs were similar or slightly higher for Cd, Co, Ni, Pb and Zn, but 1-2 orders of magnitude higher for Cu. Compared to the default site-generic CTPs in the frequently used characterization models USES-LCA and USEtox, new site-generic CTPs were mostly higher or similar, within up to ∼2 orders of magnitude difference.

Elucidating differences in metal absorption efficiencies between terrestrial soft-bodied and aquatic species.

It is unknown whether metal absorption efficiencies in terrestrial soft-bodied species can be predicted with the same metal properties as for aquatic species. Here, we developed models for metal absorption efficiency from the dissolved phase for terrestrial worms and several aquatic species, based on 23 metal physicochemical properties. For the worms, the absorption efficiency was successfully related to 7 properties, and is best predicted with the ionic potential. Different properties (8 in total) were found to be statistically significant in regressions predicting metal absorption in aquatic species, with the covalent index being the best predictor. It is hypothesized that metal absorption by soft-bodied species in soil systems is influenced by the rate of metal supply to the membrane, while in aquatic systems accumulation is solely determined by metal affinity to membrane bound transport proteins. Our results imply that developing predictive terrestrial bioaccumulation and toxicity models for metals must consider metal interactions with soil solids. This may include desorption of a cation bound to soil solids through ion exchange, or metal release from soil surfaces involving breaking of metal-oxygen bonds.

Review of LCA studies of solid waste management systems--part II: methodological guidance for a better practice.

Life cycle assessment (LCA) is increasingly used in waste management to identify strategies that prevent or minimise negative impacts on ecosystems, human health or natural resources. However, the quality of the provided support to decision- and policy-makers is strongly dependent on a proper conduct of the LCA. How has LCA been applied until now? Are there any inconsistencies in the past practice? To answer these questions, we draw on a critical review of 222 published LCA studies of solid waste management systems. We analyse the past practice against the ISO standard requirements and the ILCD Handbook guidelines for each major step within the goal definition, scope definition, inventory analysis, impact assessment, and interpretation phases of the methodology. Results show that malpractices exist in several aspects of the LCA with large differences across studies. Examples are a frequent neglect of the goal definition, a frequent lack of transparency and precision in the definition of the scope of the study, e.g. an unclear delimitation of the system boundaries, a truncated impact coverage, difficulties in capturing influential local specificities such as representative waste compositions into the inventory, and a frequent lack of essential sensitivity and uncertainty analyses. Many of these aspects are important for the reliability of the results. For each of them, we therefore provide detailed recommendations to practitioners of waste management LCAs.

Review of LCA studies of solid waste management systems--part I: lessons learned and perspectives.

The continuously increasing solid waste generation worldwide calls for management strategies that integrate concerns for environmental sustainability. By quantifying environmental impacts of systems, life cycle assessment (LCA) is a tool, which can contribute to answer that call. But how, where and to which extent has it been applied to solid waste management systems (SWMSs) until now, and which lessons can be learnt from the findings of these LCA applications? To address these questions, we performed a critical review of 222 published LCA studies of SWMS. We first analysed the geographic distribution and found that the published studies have primarily been concentrated in Europe with little application in developing countries. In terms of technological coverage, they have largely overlooked application of LCA to waste prevention activities and to relevant waste types apart from household waste, e.g. construction and demolition waste. Waste management practitioners are thus encouraged to abridge these gaps in future applications of LCA. In addition to this contextual analysis, we also evaluated the findings of selected studies of good quality and found that there is little agreement in the conclusions among them. The strong dependence of each SWMS on local conditions, such as waste composition or energy system, prevents a meaningful generalisation of the LCA results as we find it in the waste hierarchy. We therefore recommend stakeholders in solid waste management to regard LCA as a tool, which, by its ability of capturing the local specific conditions in the modelling of environmental impacts and benefits of a SWMS, allows identifying critical problems and proposing improvement options adapted to the local specificities.