Exposure factors for marine eutrophication impacts assessment based on a mechanistic biological model

Abstract

Document Version Peer reviewed version Link back to DTU Orbit Citation (APA):Cosme, N. M. D., Koski, M., & Hauschild, M. Z. (2015). Exposure factors for marine eutrophication impacts assessment based on a mechanistic biological model. Ecological Modelling, 317, 50-63. DOI: 10.1016/j.ecolmodel.2015.09.005 Cosme et al. / Ecological Modelling 317 (2015 AbstractEmissions of nitrogen (N) from anthropogenic sources enrich marine waters and promote planktonic growth. This newly synthesised organic carbon is eventually exported to benthic waters where aerobic respiration by heterotrophic bacteria results in the consumption of dissolved oxygen (DO). This pathway is typical of marine eutrophication. A model is proposed to mechanistically estimate the response of coastal marine ecosystems to N inputs. It addresses the biological processes of nutrient-limited primary production (PP), metazoan consumption, and bacterial degradation, in four distinct sinking routes from primary (cell aggregates) and secondary producers (faecal pellets, carcasses, and active vertical transport). Carbon export production (P E ) and ecosystems eXposure Factors (XF), which represents a nitrogen-to-oxygen 'conversion' potential, were estimated at a spatial resolution of 66 large marine ecosystem (LME), five climate zones, and site-generic. The XFs obtained range from 0.45 (Central Arctic Ocean) to 15.9 kgO 2 ·kgN -1 (Baltic Sea). While LME resolution is recommended, aggregated P E or XF per climate zone can be adopted, but not global aggregation due to high variability. The XF is essential to estimate a marine eutrophication impacts indicator in Life Cycle Impact Assessment (LCIA) of anthropogenic-N emissions. Every relevant process was modelled and the uncertainty of the driving parameters considered low suggesting valid applicability in characterisation modelling in LCIA.

Spatially differentiated midpoint indicator for marine eutrophication of waterborne emissions in Sweden

“…The combination of our nutrient limitation factor and equivalency ratio could be seen as an exposure factor (following the terminology of e.g. Cosme et al 2015), although it lacks a component to describe the recipients' degree of sensitivity, but rather assumes that all nutrients that reach a recipient sensitive to that nutrient will cause eutrophication.…”

“…impactworldplus.org) and LC-IMPACT (http://www.lcimpact.eu/)) are also currently underway. Parts of the marine eutrophication CFs for LC-IMPACT have been published, and they indicate considerable global variability in endpoint CFs (Cosme and Hauschild 2016;Cosme and Hauschild 2017;Cosme et al 2015). The recently published ReCiPe 2017 methodology does not provide a characterisation model for marine eutrophication, due to lack of endpoint model (Huijbregts et al 2016).…”

“…Spatial differentiation is therefore considered an important step to improve the LCA methodology (Hellweg and Milà i Canals 2014), and many recent publications explore different aspects of this topic (e.g. Anton et al 2014;Cosme et al 2015;Cosme and Hauschild 2017;Mutel et al 2012;Scherer and Pfister 2015).…”

Towards a meaningful assessment of marine ecological impacts in life cycle assessment (LCA)

“…The fate factor models the nitrogen load within a large marine ecosystem and is a function of the fraction of N emissions exported from a country to adjacent LME receiving cells and the N-loss rate in the receiving LME cell(s). Spatially-explicit exposure factors [kg O 2 kg N −1 ] provide a nitrogen to oxygen consumption conversion potential based on carbon flux processes (Ducklow et al, 2001) and bacterial degradation (Del Giorgio and Cole, 1998;Iversen and Ploug, 2010 Cosme et al, 2015;Cosme & Hauschild, submitted for publication) is a useful development for inclusion of impacts on the marine environment from eutrophication-induced hypoxia in LCA. Further research efforts should focus on incorporating spatial differentiation with respect to limiting nutrient (i.e.…”

“…The characterization factors [PAF m 3 year kg − 1 ] for marine eutrophication-induced hypoxia impacts due to nitrogen (N) emissions to water, air and agricultural soils, are spatially differentiated by country and LME unit. These endpoint characterization factors are constructed from fate (Cosme, in preparation), exposure (Cosme et al, 2015) and effect factors (Cosme & Hauschild, submitted for publication). The fate factor models the nitrogen load within a large marine ecosystem and is a function of the fraction of N emissions exported from a country to adjacent LME receiving cells and the N-loss rate in the receiving LME cell(s).…”