No abstract

Life-cycle assessment (LCA) is the method of inventorying, assessing, and interpreting environmental interventions caused by products and product systems through their life cycle. The ecotoxicity of metals has proven a challenge for LCA given metal characteristics such as reversibility of removal processes, speciation, and the effect on bioavailability and ecotoxic effect assessment. Our review focuses on the first part of the ecotoxic impact chain for metals, i.e., the release of metals from solid deposits. According to the principle of temporal justice, sustainability assessment tools such as LCA should accountfor emissions regardless of temporal location distribution. This is in LCA commonly interpreted as leaching until depletion of metals bound in solid wastes under the presumption that infinite time implies infinite weathering. This approach is risk conservative for metals and it hampers the use of LCA to assess remediation projects for soils and sediments contaminated by inorganic substances. We discuss metal significance and inventory issues in LCA, and review existing and proposed approachesto make LCA applicable to metal long-term emission.

In support of continuous environmental improvement in the mining industry, it is important to systematically assess the environmental impacts of mining and mineral processing operations from a life cycle perspective. Although life cycle assessment (LCA) is widely used as an environmental systems analysis tool, the application of LCA in the mining industry is still in progress. This paper carried out a cradle-to-gate LCA of an underground copper ore mine planned in Northern Norway. Based on the ReCiPe midpoint (hierarchist) life cycle impact assessment method, results of the study showed that on-site electricity use, diesel for mining trucks and blasting dominated contributions across six, four and four, respectively, of the eighteen categories assessed, and metals leaching from tailings were the primary contributors to the human toxicity and marine ecotoxicity impacts. Compared to the baseline, results of the energy-oriented scenario analysis indicated that electrification of diesel-driven mining trucks would be more environmentally beneficial as long as across impact categories. While electrodialytic tailings remediation could extract up to 64% of copper in tailings prior to disposal and significantly reduce 2 the human toxicity impact of tailings, the marine ecotoxicity impact of tailings after electrodialysis changed inconsistently across the ReCiPe hierarchist and egalitarian perspectives. It is recommended to further assess the trade-off between the benefits of electrodialytic tailings remediation (extracting more copper) and the potential impacts of deposited tailings after electrodialysis from a multi-criteria decision-analysis perspective. In a generic context, this study provides an insight in further promoting LCA as an environmental decision-support tool, especially for comparing available cleaner production options, improving the overall environmental performance of a mine, and facilitating better communication with stakeholders.

Recirculating aquaculture systems (RAS) are an alternative technology to tackle the major environmental challenges associated with conventional cage culture systems. In order to systematically assess the environmental performance of RAS farming, it is important to take the whole life cycle into account so as to avoid ad hoc and suboptimal environmental measures. So far, the application of life cycle assessment (LCA) in aquaculture, especially to indoor RAS, is still in progress. This study reports on an LCA of Atlantic salmon harvested at an indoor RAS farm in northern China. Results showed that 1 tonne live‐weight salmon production required 7,509 kWh farm‐level electricity and generated 16.7 tonnes of CO2 equivalent (eq), 106 kg of SO2 eq, 2.4 kg of P eq, and 108 kg of N eq (cradle‐to‐farm gate). In particular, farm‐level electricity use and feed product were identified as primary contributors to eight of nine impact categories assessed (54–95% in total), except the potential marine eutrophication (MEU) impact (dominated by the grow‐out effluents). Among feed ingredients (on a dry‐weight basis), chicken meal (5%) and krill meal (8%) dominated six and three, respectively, of the nine impact categories. Suggested environmental improvement measures for this indoor RAS farm included optimization of stocking density, feeding management, grow‐out effluent treatment, substitution of feed ingredients, and selection of electricity generation sources. In a generic context, this study can contribute to a better understanding of the life cycle environmental impacts of land‐based salmon RAS operations, as well as science‐based communication among stakeholders on more eco‐friendly farmed salmon.