PurposeWeighting in LCA is important as it supports decision-making by prioritising and determining which impact categories are more important. However, the lack of weighting factors in developing countries forces LCA practitioners to adopt weighting values developed for other countries, leading to a less transparent decision-making process. One transparent and easily reproducible distance-to-target (DtT) weighting method that can be applied in Nigeria is the Swiss-developed ecological scarcity method. This method is based on the ratio of the current environmental situation of a country, region or product to the desired policy targets. The purpose of this study was to apply the ESM to develop weighting factors and eco-factors for Nigeria.MethodsThe normalization and current flows data for emissions and resource use in 2010 (base year) were collected from official data sources, and the critical flows were extracted from corresponding policy targets of the Government of Nigeria in 2030 (target year). The ESM was then applied to the aggregated data to derive Nigeria-specific weighting factors and eco-factors as the quantitative indicators for the emissions and resources.Results and discussionWeighting and eco-factors for emissions and resources were developed for 25 environmental issues in Nigeria. NOx, total petroleum hydrocarbon and land use weigh heavily. Except for carcinogenic substances in the air, emissions to water resulted in high eco-factors: TPH, phenol, total nitrogen, nitrate, ammonia and heavy metals (human and ecotoxicity). Policymakers in Nigeria need to set quantitative emission reduction targets for substances and such as carcinogenic substances in the air, oil spills and metal mineral resources.ConclusionsThe ESM was used to develop Nigeria's eco-factors as quantitative indicators for emissions or resource use using the normalization and current flows in 2010 obtained from government data sources as base year data. The critical flows were extracted from the policy targets of the government of Nigeria, with 2030 as the target year. The eco-factors can support environmental sustainability decision-making in Nigeria. Future methodological development should apply updated policy targets and more data to calculate eco-factors for missing substances such as waste (radioactive and non-radioactive), heavy metal emissions to air and soil, emissions to groundwater, photochemical ozone creation substances and phosphorous in surface water and soil.

Increased anthropogenic activities over the last decades have led to a gradual increase in chromium (Cr) content in the soil, which, due to its high mobility in soil, makes Cr accumulation in plants a serious threat to the health of animals and humans. The present study investigated the ameliorative effect of foliar-applied Si nanoparticles (SiF) and soil-applied SiNPs enriched biochar (SiBc) on the growth of wheat in Cr-polluted soil (CPS). Two levels of CPS were prepared, including 12.5 % and 25 % by adding Cr-polluted wastewater in the soil as soil 1 (S1) and soil 2 (S2), respectively for the pot experiment with a duration of 40 days. Cr stress significantly reduced wheat growth, however, combined application of SiF and SiBc improved root and shoot biomass production under Cr stress by (i) reducing Cr accumulation, (ii) increasing activities of antioxidant enzymes (ascorbate peroxidase and catalase), and (iii) increasing protein and total phenolic contents in both root and shoot respectively. Nonetheless, separate applications of SiF and SiBc effectively reduced Cr toxicity in shoot and root respectively, indicating a tissue-specific regulation of wheat growth under Cr. Later, the Langmuir and Freundlich adsorption isotherm analysis showed a maximum soil Cr adsorption capacity similar to Q((max)) of 40.6 mg g(-1) and 59 mg g(-1) at S1 and S2 respectively, while the life cycle impact assessment showed scores of -1 mg kg(-1) and -211 mg kg(-1) for Cr in agricultural soil and - 0.184 and - 38.7 for human health at S1 and S2 respectively in response to combined SiF + SiBC application, thus indicating the environment implication of Si nanoparticles and its biochar in ameliorating Cr toxicity in different environmental perspectives.

PurposeThe local dimension of toxicity effect on humans and ecosystem from chemical emissions into rural environments is currently not considered in impact characterization models underlying the Life Cycle Assessment (LCA) methodology. The aim of the present study was to understand the relevance of considering a local exposure environment for the magnitude of damage related to human toxicity and ecotoxicity impacts associated with chemical emissions into a local environment.MethodUnit and realistic European emission scenarios were considered in a proposed multimedia nested box model, based on an existing framework modified with the inclusion of a local scale, and tested for ten chemicals in an illustrative case study.ResultsA substantial damage increase in terms of characterization factors in the proposed model was found for human health, mainly for local freshwater emissions (up to three orders of magnitude compared to emissions into continental freshwater for naphthalene) and soil emissions (up to two orders of magnitude, in particular for emissions into natural soil for 1,2-dichloroethane).ConclusionsBased on our results, we suggest to use the proposed framework in LCA applications, when more specific information about the local emission environment is known. With respect to considering the local-scale, however, spatialized models might be preferable over nested box models to properly capture local phenomena in rather highly densely populated areas.