Proposed Local Ecological Impact Categories and Indicators for Life Cycle Assessment of Aquaculture

In this study we discuss impact categories and indicators to incorporate local ecological impacts into life cycle assessment (LCA) for aquaculture. We focus on the production stages of salmon farming—freshwater hatcheries used to produce smolts and marine grow‐out sites using open netpens. Specifically, we propose two impact categories: impacts of nutrient release and impacts on biodiversity. Proposed indicators for impacts of nutrient release are (1) the area altered by farm waste, (2) changes in nutrient concentration in the water column, (3) the percent of carrying capacity reached, (4) the percent of total anthropogenic nutrient release, and (5) release of wastes into freshwater. Proposed indicators for impacts on biodiversity are (1) the number of escaped salmon, (2) the number of reported disease outbreaks, (3) parasite abundance on farms, and (4) the percent reduction in wild salmon survival. For each proposed indicator, an example of how the indicator could be estimated is given and the strengths and weaknesses of that indicator are discussed. We propose that including local environmental impacts as well as global‐scale ones in LCA allows us to better identify potential trade‐offs, where actions that are beneficial at one scale are harmful at another, and synchronicities, where actions have desirable or undesirable effects at both spatial scales. We also discuss the potential applicability of meta‐analytic statistical techniques to LCA.     

Impact categories for life cycle assessment research of seafood production systems: Review and prospectus

Goal, Scope and Background In face of continued declines in global fisheries landings and concurrent rapid aquaculture development, the sustainability of seafood production is of increasing concern. Life Cycle Assessment (LCA) offers a convenient means of quantifying the impacts associated with many of the energetic and material inputs and outputs in these industries. However, the relevant but limited suite of impact categories currently used in most LCA research fails to capture a number of important environmental and social burdens unique to fisheries and aquaculture. This article reviews the impact categories used in published LCA research of seafood production to date, reports on a number of methodological innovations, and discusses the challenges to and opportunities for further impact category developments. Main Features The range of environmental and socio-economic impacts associated with fisheries and aquaculture production are introduced, and both the commonly used and innovative impact categories employed in published LCA research of seafood production are discussed. Methodological innovations reported in agricultural LCAs are also reviewed for possible applications to seafood LCA research. Challenges and options for including additional environmental and socioeconomic impact categories are explored. Results A review of published LCA research in fisheries and aquaculture indicates the frequent use of traditional environmental impact categories as well as a number of interesting departures from the standard suite of categories employed in LCA studies in other sectors. Notable examples include the modeling of benthic impacts, by-catch, emissions from anti-fouling paints, and the use of Net Primary Productivity appropriation to characterize biotic resource use. Socio-economic impacts have not been quantified, nor does a generally accepted methodology for their consideration exist. However, a number of potential frameworks for the integration of such impacts into LCA have been proposed. Discussion LCA analyses of fisheries and aquaculture call attention to an important range of environmental interactions that are usually not considered in discussions of sustainability in the seafood sector. These include energy use, biotic resource use, and the toxicity of anti-fouling paints. However, certain important impacts are also currently overlooked in such research. While prospects clearly exist for improving and expanding on recent additions to environmental impact categories, the nature of the LCA framework may preclude treatment of some of these impacts. Socio-economic impact categories have only been described in a qualitative manner. Despite a number of challenges, significant opportunities exist to quantify several important socio-economic impacts. Conclusion The limited but increasing volume of LCA research of industrial fisheries and aquaculture indicates a growing interest in the use of LCA methodology to understand and improve the sustainability performance of seafood production systems. Recent impact category innovations, and the potential for further impact category developments that account for several of the unique interactions characteristic of fisheries and aquaculture will significantly improve the usefulness of LCA in this context, although quantitative analysis of certain types of impacts may remain beyond the scope of the LCA framework. The desirability of incorporating socio-economic impacts is clear, but such integration will require considerable methodological development. Recommendations and Perspectives While the quantity of published LCA research for seafood production systems is clearly increasing, the influence this research will have on the ground remains to be seen. In part, this will depend on the ability of LCA researchers to advance methodological innovations that enable consideration of a broader range of impacts specific to seafood production. It will also depend on the ability of researchers to communicate with a broader audience than the currently narrow LCA community.     

Water Resources in Life-Cycle Impact Assessment: Considerations in Choosing Category Indicators

Water is one of many resources, wastes, and pollutants considered in life-cycle assessment (LCA). The widely used indicator for water resources, the total input of water used, is not adequate to assess water resources from a sustainability perspective. More detailed indicators are proposed for water resources in two areas essential to water sustainability: water quantity and water quality. The governing principles for a consideration of water quantity are that (1) the water sources or LCA inputs are renewable and sustainable and (2) the volume of water released or LCA outputs are returned to humans or ecosystems for further use downstream. The governing principle for a consideration of water quality is that the utility of the returned water is not impaired for either humans or ecosystems downstream. Water quantity indicators are defined for water use, consumption, and depletion to reveal the sustainable or nonsustainable nature of the sources. A flexible set of water quality indicators for various factors that may impair water quality are then discussed, including the LCA study choices, technical challenges, and trade-offs involved with such indicators. Indicator selection from this set involves the underlying concern or endpoint represented by the indicator and the level and accuracy of decision-making information that the indicator must provide. With significant differences in emissions among systems studied using LCA and different purposes of the LCA studies themselves, a single, default set of water quality indicators applicable to all systems studied with LCA is problematic. The proposed water quantity and quality indicators for LCA studies are also intended to be compatible with environmental management and reporting systems so that data needs are not duplicated and interpretation for one does not contradict or sow confusion for the other.     

National inventories of land occupation and transformation flows in the world for land use impact assessment

Purpose

Land use can cause significant impacts on ecosystems and natural resources. To assess these impacts using life cycle assessment (LCA) and ensure adequate decision-making, comprehensive national inventories of land occupation and transformation flows are required. Here, we aim at developing globally differentiated inventories of land use flows that can be used for primary use in life cycle impact assessment or national land planning.

Methods

Using publicly available data and inventory techniques, national inventories for several land use classes were developed. All land use classes were covered with the highest retrievable level of disaggregation within urban, forestry, agriculture and other land use classes, thus differentiating 21 land use classes. For illustrating the application of this newly developed inventory, two different application settings relevant to life cycle impact assessment were considered: the calculation of global normalisation references for 11 land use impact indicators related to soil quality assessment (adopting the methods recommended by the EU Commission) and the determination of generic globally applicable characterisation factors (CFs) resulting from aggregation of country-level CFs for situations for use when land use location is unknown.

Results and discussion

We built national inventories of 21 land occupation and 17 land transformation flows for 225 countries in the world for the reference year 2010. Cross-comparisons with existing inventories of narrower scopes attested its consistency. Detailed analyses of the calculated global normalisation references for the 11 land use impact categories showed different patterns across the land use impact indicators for each country, thus raising attention on key land use impacts specific to each country. Furthermore, the upscaling of country-level CFs to global generic CFs using the land use inventory revealed discrepancies with other alternative approaches using land use data at different resolutions.

Conclusions

In this study, we made a first attempt at developing national inventories of land use flows with sufficient disaggregation level to enable the calculation of normalisation references and differentiated impacts. However, the findings also demonstrated the need to refine the consistency of the inventory, particularly in the combination of land cover and land use data, which should be harmonised in future studies, and to expand it with differentiated coverage of more land use flows relevant to impact assessment.

     

Review of impact categories and environmental indicators for life cycle assessment of geotechnical systems

Life cycle assessment (LCA) has only had limited application in the geotechnical engineering discipline, though it has been widely applied to civil engineering systems such as pavements and roadways. A review of previous geotechnical LCAs showed that most studies have tracked a small set of impact categories, such as energy and global warming potential. Accordingly, currently reported environmental indicators may not effectively or fully capture important environmental impacts and tradeoffs associated with geotechnical systems, including those associated with land and soil resources. This research reviewed previous studies, methods, and models for assessment of land use and soil‐related impacts to understand their applicability to geotechnical LCA. The results of this review show that critical gaps remain in current knowledge and practice. In particular, further development or refinement of environmental indicators, impact categories, and cause–effect pathways is needed as they pertain to geotechnical applications—specifically those related to soil quality, soil functions, and the ecosystem services soils provide. In addition, many existing methods emerge from research on land use and land use change related to other disciplines (e.g., agriculture). For applicability to geotechnical projects, the resolution of many of these methods and resulting indicators need to be downscaled from the landscape/macro scale to the project scale. In the near term, practitioners of geotechnical LCA should begin tracking changes to soil properties and report impacts to land and soil resources qualitatively.     

Application of the impact pathway analysis in the context of LCA

Current LCA practice is mass oriented, i.e. is focused on the amount of chemicals released, disregarding place and time of release. Life cycle impact assessment aims at evaluating potential impacts, and a variety of weighting schemes is discussed to he used for ranking and aggregation of impacts. To establish a closer link between the quantity of a burden released and a decision making context, we propose to follow a detailed impact pathway analysis to estimate actual impacts for some priority impact categories, and use measured individuals’ preferences for impact valuation. Results from a case study illustrate the relevance of site specific impact assessment in the context of LCA.     

The environmental consequences of a change in Australian cotton lint production

Purpose

Changes in the production of Australian cotton lint are expected to have a direct environmental impact, as well as indirect impacts related to co-product substitution and induced changes in crop production. The environmental consequences of a 50% expansion or contraction in production were compared to Australian cotton production’s current environmental footprint. Both were then assessed to investigate whether current impacts are suitable for predicting the environmental impact of a change in demand for cotton lint.

Methods

A consequential life cycle assessment (LCA) model of Australian cotton lint production (cradle-to-gin gate) was developed using plausible scenarios regarding domestic regions and technologies affected by changes in supply, with both expansion (additional cotton) and contraction (less cotton) being modelled. Modelling accounted for direct impacts from cotton production and indirect impacts associated with changes to cotton production, including co-product substitution and changes to related crops at regional and global scales. Impact categories assessed included climate change, fossil energy demand, freshwater consumption, water stress, marine and freshwater eutrophication, land occupation and land-use change.

Results and discussion

For both the expansion and contraction scenarios, the changes to climate change impacts (including iLUC) and water impacts were less than would be assumed from current production as determined using attributional LCA. However, the opposite was true for all other impact categories, indicating trade-offs across the impact categories. Climate change impacts under both scenarios were relatively minor because these were largely offset by iLUC. Similarly, under the contraction scenario, water impacts were dominated by indirect impacts associated with regional crops. A sensitivity analysis showed that the results were sufficiently robust to indicate the quantum of changes that could be expected.

Conclusions

A complex array of changes in technologies, production regions and related crops were required to model the environmental impacts of a gross change in cotton production. Australian cotton lint production provides an example of legislation constraining the direct water impacts of production, leading to a contrast between impacts estimated by attributional and consequential LCA. This model demonstrated that indirect products and processes are important contributors to the environmental impacts of Australian cotton lint.

     

Life cycle assessment framework in agriculture on the farm level

Life Cycle Assessment (LCA) is a method that can be used to assess the environmental impact of agriculture, but impact categories and the functional unit of classical LCA’s must be adapted to the specific agricultural production process. Serving as an example, the framework of a LCA of 18 grassland dairy farms covering three farming intensity levels and carried out in the Allgäu region in southern Germany is presented. By focussing on the chosen impact categories and the respective, suitable functional units, the specific needs and backgrounds of conducting an agricultural LCA are discussed in general.     

Significance of the use of non-renewable fossil CED as proxy indicator for screening LCA in the beverage packaging sector

Purpose

This study discusses the significance of the use of non-renewable fossil cumulative energy demand (CED) as proxy indicator in the beverage packaging sector, in order to detect those situations in which companies can benefit from the use of proxy indicators before a full life cycle assessment (LCA) application. Starting from a case study of two milk containers, the objectives of this paper are to assess if the use of this inventory indicator can be a suitable proxy indicator both (1) to decide which is the packaging alternative with the lowest environmental impact and (2) to identify the most impacting process units of the two products under study.

Method

The analysis was made according to ISO14040-44. The goal of the comparative LCA was to evaluate and to compare the potential environmental impacts from cradle to grave of a laminated carton container and a HDPE bottle. The results of the comparative LCA obtained with the non-renewable CED indicator are compared with a selection of impact categories: climate change, particulate matter formation, terrestrial acidification, fossil depletion, photochemical oxidant formation. A further analysis is made for the two products under study in order to determine which are the environmental hot spots in terms of life cycle stages, by the means of a contribution analysis.

Results and discussion

From the comparative LCA, the use of non-renewable CED revealed to be useful for a screening as the results given by the non-renewable CED indicator are confirmed by all the impact categories considered, even if underestimated. If the aim of the LCA study was to define which is the packaging solution with a lower environmental impact, the choice of this inventory indicator could have led to the same decision as if a comprehensive LCIA method was used. The contribution analysis, focusing on the identification of environmental hot spots in the packaging value chain, revealed that the choice of an inventory indicator as non-renewable CED can lead to misleading results, if compared with another impact category, such as climate change.

Conclusions

As in the future development of beverage packaging system, LCA will be necessarily integrated in the design process, it is important to define other ways of simplifying its application and spread its use among companies. The LCI indicator non-renewable fossil CED can effectively be used in order to obtain a preliminary estimation of the life cycle environmental impacts of two or more competing products in the beverage packaging sector.     

Global characterisation factors to assess land use impacts on biotic production

Purpose

The inclusion of land-use activities in life cycle assessment (LCA) has been subject to much debate in the LCA community. Despite the recent methodological developments in this area, the impacts of land occupation and transformation on its long-term ability to produce biomass (referred to here as biotic production potential [BPP]) — an important endpoint for the Area of Protection (AoP) Natural Resources — have been largely excluded from LCAs partly due to the lack of life cycle impact assessment methods.

Materials and methods

Several possible methods/indicators for BPP associated with biomass, carbon balance, soil erosion, salinisation, energy, soil biota and soil organic matter (SOM) were evaluated. The latter indicator was considered the most appropriate for LCA, and characterisation factors for eight land use types at the climate region level were developed.

Results and discussion

Most of the indicators assessed address land-use impacts satisfactorily for land uses that include biotic production of some kind (agriculture or silviculture). However, some fail to address potentially important land use impacts from other life cycle stages, such as those arising from transport. It is shown that the change in soil organic carbon (SOC) can be used as an indicator for impacts on BPP, because SOC relates to a range of soil properties responsible for soil resilience and fertility.

Conclusions

The characterisation factors developed suggest that the proposed approach to characterize land use impacts on BBP, despite its limitations, is both possible and robust. The availability of land-use-specific and biogeographically differentiated data on SOC makes BPP impact assessments operational. The characterisation factors provided allow for the assessment of land-use impacts on BPP, regardless of where they occur thus enabling more complete LCAs of products and services. Existing databases on every country’s terrestrial carbon stocks and land use enable the operability of this method. Furthermore, BPP impacts will be better assessed by this approach as increasingly spatially specific data are available for all geographical regions of the world at a large scale. The characterisation factors developed are applied to the case studies (Part D of this special issue), which show the practical issues related to their implementation.     

Environmental impacts of European trade: interpreting results of process-based LCA and environmentally extended input–output analysis towards hotspot identification

Purpose

Trade is increasingly considered a significant contributor to environmental impacts. The assessment of the impacts of trade is usually performed via environmentally extended input–output analysis (EEIOA). However, process-based life cycle assessment (LCA) applied to traded goods allows increasing the granularity of the analysis and may be essential to unveil specific impacts due to traded products.

Methods

This study assesses the environmental impacts of the European trade, considering two modelling approaches: respectively EEIOA, using EXIOBASE 3 as supporting database, and process-based LCA. The interpretation of the results is pivotal to improve the robustness of the assessment and the identification of hotspots. The hotspot identification focuses on temporal trends and on the contribution of products and substances to the overall impacts. The inventories of elementary flows associated with EU trade, for the period 2000–2010, have been characterized considering 14 impact categories according to the Environmental Footprint (EF2017) Life Cycle Impact Assessment method.

Results and discussion

The two modelling approaches converge in highlighting that in the period 2000–2010: (i) EU was a net importer of environmental impacts; (ii) impacts of EU trade and EU trade balance (impacts of imports minus impacts of exports) were increasing over time, regarding most impact categories under study; and (iii) similar manufactured products were the main contributors to the impacts of exports from EU, regarding most impact categories. However, some results are discrepant: (i) larger impacts are obtained from IO analysis than from process-based LCA, regarding most impact categories, (ii) a different set of most contributing products is identified by the two approaches in the case of imports, and (iii) large differences in the contributions of substances are observed regarding resource use, toxicity, and ecotoxicity indicators.

Conclusions

The interpretation step is crucial to unveil the main hotspots, encompassing a comparison of the differences between the two methodologies, the assumptions, the data coverage and sources, the completeness of inventory as basis for impact assessment. The main driver for the observed divergences is identified to be the differences in the impact intensities of goods, both induced by inherent properties of the IO and life cycle inventory databases and by some of this study’s modelling choices. The combination of IO analysis and process-based LCA in a hybrid framework, as performed in other studies but generally not at the macro-scale of the full trade of a country or region, appears a potential important perspective to refine such an assessment in the future.

     

The environmental impacts of operating an Antarctic research station

We present a life cycle assessment (LCA) of the operation of Casey Station in Antarctica. The LCA included quantifying material and energy flows, modeling of elementary flows, and subsequent environmental impacts. Environmental impacts were dominated by emissions associated with freight operations and electricity cogeneration. A participatory design approach was used to identify options to reduce environmental impacts, which included improving freight efficiency, reducing the temperature setpoint of the living quarters, and installing alternative energy systems. These options were then assessed using LCA, and have the potential to reduce environmental impacts by between 2% and 19.1%, depending on the environmental indicator.     

45th Discussion forum on LCA—environmentally extended input–output analysis and LCA, September 15, 2011, Berne, Switzerland

The discussion forum on life cycle assessment (LCA) on September 15, 2011, aimed at summarizing recent environmentally extended input?Coutput analysis (EE-IOA) and the combination with LCA for the computation of environmental impact of imports. Input?Coutput tables (IOT) represent the financial flows in a country or economic regions. Extending IOT with information on emissions and resource uses allows for the analysis of environmental impacts due to production and consumption activities in a country. This instrument is called EE-IOA. It enables the analysis of total environmental impacts of countries or economic regions. The combination with trade statistics and LCA was presented as an alternative to multiregional input?Coutput models for determining environmental impacts of imports over the whole life cycle. The 45th LCA forum gathered several international speakers who provided a broad and qualified view on the topic. The theoretical background, results for different countries and regions, uncertainties, and possible improvement options for EE-IOA were discussed. The following main conclusions were drawn at the end of the discussion forum: EE-IOA is a useful instrument for analyzing the total environmental impacts of countries and the main drivers of environmental impacts. As a next important step, the participants would like to see an increase in user friendliness of EE-IOA combined with LCA, e.g., by harmonizing data, data formats, and classifications.     

Assessing freshwater use impacts in LCA: Part I—inventory modelling and characterisation factors for the main impact pathways

Background, aim and scope

Freshwater is a basic resource for humans; however, its link to human health is seldom related to lack of physical access to sufficient freshwater, but rather to poor distribution and access to safe water supplies. On the other hand, freshwater availability for aquatic ecosystems is often reduced due to competition with human uses, potentially leading to impacts on ecosystem quality. This paper summarises how this specific resource use can be dealt with in life cycle analysis (LCA).

Main features

The main quantifiable impact pathways linking freshwater use to the available supply are identified, leading to definition of the flows requiring quantification in the life cycle inventory (LCI).

Results

The LCI needs to distinguish between and quantify evaporative and non-evaporative uses of ‘blue’ and ‘green’ water, along with land use changes leading to changes in the availability of freshwater. Suitable indicators are suggested for the two main impact pathways [namely freshwater ecosystem impact (FEI) and freshwater depletion (FD)], and operational characterisation factors are provided for a range of countries and situations. For FEI, indicators relating current freshwater use to the available freshwater resources (with and without specific consideration of water ecosystem requirements) are suggested. For FD, the parameters required for evaluation of the commonly used abiotic depletion potentials are explored.

Discussion

An important value judgement when dealing with water use impacts is the omission or consideration of non-evaporative uses of water as impacting ecosystems. We suggest considering only evaporative uses as a default procedure, although more precautionary approaches (e.g. an ‘Egalitarian’ approach) may also include non-evaporative uses. Variation in seasonal river flows is not captured in the approach suggested for FEI, even though abstractions during droughts may have dramatic consequences for ecosystems; this has been considered beyond the scope of LCA.

Conclusions

The approach suggested here improves the representation of impacts associated with freshwater use in LCA. The information required by the approach is generally available to LCA practitioners

Recommendations and perspectives

The widespread use of the approach suggested here will require some development (and consensus) by LCI database developers. Linking the suggested midpoint indicators for FEI to a damage approach will require further analysis of the relationship between FEI indicators and ecosystem health.     

Principles for life cycle inventories of land use on a global scale

Purpose

To assess the diverse environmental impacts of land use, a standardization of quantifying land use elementary flows is needed in life cycle assessment (LCA). The purpose of this paper is to propose how to standardize the land use classification and how to regionalize land use elementary flows.

Materials and methods

In life cycle inventories, land occupation and transformation are elementary flows providing relevant information on the type and location of land use for land use impact assessment. To find a suitable land use classification system for LCA, existing global land cover classification systems and global approaches to define biogeographical regions are reviewed.

Results and discussion

A new multi-level classification of land use is presented. It consists of four levels of detail ranging from very general global land cover classes to more refined categories and very specific categories indicating land use intensities. Regionalization is built on five levels, first distinguishing between terrestrial, freshwater, and marine biomes and further specifying climatic regions, specific biomes, ecoregions and finally indicating the exact geo-referenced information of land use. Current land use inventories and impact assessment methods do not always match and hinder a comprehensive assessment of land use impact. A standardized definition of land use types and geographic location helps to overcome this gap and provides the opportunity to test the optimal resolution of land cover types and regionalization for each impact pathway.

Conclusions and recommendation

The presented approach provides the necessary flexibility to providers of inventories and developers of impact assessment methods. To simplify inventories and impact assessment methods of land use, we need to find archetypical situations across impact pathways, land use types and regions, and aggregate inventory entries and methods accordingly.

     

Is land use impact assessment in LCA applicable for forest biomass value chains? Findings from comparison of use of Scandinavian wood,agro-biomass and peat for energy

Purpose

A framework for the inclusion of land use impact assessment and a set of land use impact indicators has been recently proposed for life cycle assessment (LCA) and no case studies are available for forest biomass. The proposed methodology is tested for Scandinavian managed forestry; a comparative case study is made for energy from wood, agro-biomass and peat; and sensitivity to forest management options is analysed.

Methods

The functional unit of this comparative case study is 1 GJ of energy in solid fuels. The land use impact assessment framework of the United Nations Environment Programme and the Society of Environmental Toxicology and Chemistry (UNEP-SETAC) is followed and its application for wood biomass is critically analysed. Applied midpoint indicators include ecological footprint and human appropriation of net primary production, global warming potential indicator for biomass (GWP_bio-100) and impact indicators proposed by UNEP-SETAC on ecosystem services and biodiversity. Options for forest biomass land inventory modelling are discussed. The system boundary covers only the biomass acquisition phase. Management scenarios are formulated for forest and barley biomass, and a sensitivity analysis focuses on impacts of land transformations for agro-biomass.

Results and discussion

Meaningful differences were found in between solid biofuels from distinct land use classes. The impact indicator results were sensitive to land occupation and transformation and differed significantly from inventory results. Current impact assessment method is not sensitive to land management scenarios because the published characterisation factors are still too coarse and indicate differences only between land use types. All indicators on ecosystem services and biodiversity were sensitive to the assumptions related with land transformation. The land occupation (m²a) approach in inventory was found challenging for Scandinavian wood, due to long rotation periods and variable intensities of harvests. Some suggestions of UNEP-SETAC were challenged for the sake of practicality and relevance for decision support.

Conclusions

Land use impact assessment framework for LCA and life cycle impact assessment (LCIA) indicators could be applied in a comparison of solid bioenergy sources. Although forest bioenergy has higher land occupation than agro-bioenergy, LCIA indicator results are of similar magnitude or even lower for forest bioenergy. Previous literature indicates that environmental impacts of land use are significant, but it remains questionable if these are captured with satisfactory reliability with the applied LCA methodology, especially for forest biomass. Short and long time perspectives of land use impacts should be studied in LCA with characterisation factors for all relevant timeframes, not only 500 years, with a forward-looking perspective. Characterisation factors need to be modelled further for different (forest) land management intensities and for peat excavation.     

Development of a soil compaction indicator in life cycle assessment

Purpose

Integrating soil quality impacts in life cycle assessment (LCA) requires a global approach to assess impacts on soil quality that can be adapted to individual soil and climate contexts. We have developed a framework for quantifying indicators of impact on soil quality, valid for all soil and climate conditions, and considering both on-site and off-site agricultural soils. Herein, we present one of the framework’s impact indicators, which has not yet been quantified in detail in LCA studies: soil compaction.

Material and methods

The method includes guidelines and tools for estimating midpoint compaction impacts in topsoil and subsoil as a loss of soil pore volume (in cubic metre per functional unit). The life cycle inventory (LCI) and life cycle impact assessment are based on simulation modelling, using models simple enough for use by non-experts, general enough to be parameterised with available data at a global scale and already validated. Data must be as site specific and accurate as possible, but if measured data are missing, the method has a standardised framework of rules and recommendations for estimating or finding them. The main model used, COMPSOIL, predicts compaction due to agricultural traffic. Results are illustrated using a case study involving several crops in different soil and climate conditions: a representative pig feed produced in Brittany, France.

Results and discussion

Predicted compaction impacts result from the combination of site-specific soil, climate and management characteristics. The data necessary to the LCI are readily available from free soil and climate databases and research online. Results are consistent with compaction observed in the field. Within a soil type, predictions are most sensitive to initial bulk density and soil water content.

Conclusions

The method lays the foundation for possible improvement by refining estimates of initial soil conditions or adding models that are simple and robust enough to increase the method’s capacity and accuracy. The soil compaction indicator can be used in LCAs of bio-based materials and of waste management stages that consider composting. The framework includes other operational indicators (i.e. water erosion, soil organic matter change) to assess impact on soil quality. They complement other impact categories, providing increased ability to identify “impact swapping”.