You are here:
Developing spatially-explicit midpoint characterization factors for eutrophication potential
Citation:
Niblick, B., A. Henderson, H. Golden, AND J. Bare. Developing spatially-explicit midpoint characterization factors for eutrophication potential. American Center for Life Cycle Assessment (ACLCA) 2020, NA (virtual), N/A, September 22 - 24, 2020.
Impact/Purpose:
Excess nutrients from soil runoff and the atmosphere can lead to water quality challenges, such as harmful algal blooms (HABs) and depletion of oxygen, known as hypoxia. Life cycle assessment (LCA) measures some of these environmental impacts through the impact category "eutrophication potential". This work builds on a previous review by the authors of eutrophication models in LCA and calculates regionalized characterization factors to advance the scientific accuracy and effectiveness of this impact category. Once validated, these new characterization factors will be integrated into the next version of EPA's life cycle impact assessment model, TRACI (the Tool for Reduction and Assessment of Chemicals and other environmental Impacts).
Description:
Eutrophication is a global environmental issue that affects freshwater and marine ecosystems, as well as human health, recreation, and economies. Increased cycling of nutrients, especially nitrogen (N) and phosphorus (P), can lead to the rapid growth of algae, causing harmful algal blooms (HABs) and decreased levels of dissolved oxygen, known as hypoxia. Most life cycle impact assessment (LCIA) methods include a metric to measure eutrophication potential, however these methods typically use simplified nutrient fate-and-transport models and lack the spatial precision needed to operationalize eutrophication characterization factors on a refined global scale (Morelli et al., 2018). Often, a single characterization factor is used to represent an entire region or country that actually has multiple varied conditions. This single-factor approach to characterizing potential impacts limits the effectiveness of supporting complex eutrophication-related decisions. Given this gap in research and practice, and building on the recommendations from Morelli et al (2018), we calculated spatialized characterization factors for eutrophication potential using a three-step process. Depending on whether the desired fate factors are for freshwater or marine eutrophication and to which environmental compartment (soil, air, or water) the source and receptor vectors pertain, the calculations involve a combination of: 1) adopting fate factors, 2) conducting geospatial redistribution, and 3) coupling fate factors. Portraying the calculation results with mapping software reveals how the characterization factors for freshwater and marine eutrophication vary across geographic space and proximity to bodies of water, in addition to other variables. This work represents a first effort to spatially differentiate eutrophication characterization factors to improve the scientific robustness of the impact category. We focus on the United States as the geographic area and the Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) as the impact assessment method (Bare et al., 2003) as we present these developments for LCIA research and public use.