Towards the development of a salinity impact category for South African life cycle assessments: Part 3 - Salinity potentials

Abstract

In Part 2 of this series of papers, a conceptual characterisation model was proposed for the inclusion of salinity impacts into environmental life cycle assessments. In this, the final part of the series, the results of a detailed characterisation model are presented. The methodologies used to define the "unit South African catchment" are discussed, as are the methods used to predict salt concentrations in the various compartments, from which fate factors are derived. The effect factors used in the study are presented, and in combination with the fate factors, salinity potentials are derived for emissions into the various initial release compartments. The total salinity potentials for emissions into the various initial release compartments are as follows: Initial release compartment Total salinity potential (kg TDS equ./kg) Atmosphere 0.013 Surface water 0.165 Natural surfaces 0.031 Agricultural surfaces 1.000 An additional impact category for salinity effects is therefore proposed, and the derived salinity potentials (also known as characterisation factors or equivalency factors) can be used in the classification and characterisation steps of conducting an environmental life cycle assessment to calculate the score for the impact category. The salinity potentials are only relevant to South African conditions, and their use in LCA in other countries may not be applicable. When applying the salinity potentials, the LCA practitioner should take care to prevent double accounting for certain impacts. Currently, this is simple because no equivalency factors exist for common ions, or for total dissolved salts as a lumped parameter.