Development of damage function of acidification for terrestrial ecosystems based on the effect of aluminum toxicity on net primary production

Abstract

tor, NPP, also has an advantage in its mass unit that is directly summable through the entire impact categories. Expansion of endpoints, such as in aquatic ecosystems, material degradation, human health, and biodiversity aspects of terrestrial ecosystems, is an important subject for future work. Further, uncertain analy- ses for major parameters will provide helpful information on the reliability of damage function. Abbreviations: ADF-Atmospheric Deposition Factor; AP-Acidi- fication Potential; CI-Category Indicator; DF-Damage Factor; DI-Damage Indicator; EF-Effect Factor; LCA-Life Cycle Assess- ment; LCIA-Life Cycle Impact Assessment; LIME-Life-cycle Impact assessment Method based on Endpoint modeling; NDVI- Normalized Difference Vegetation Index; NNR-Non-Neutrali- zation Ratio; NPP-Net Primary Productivity; NSS-Non-Sea Salt; SRR-Source-Receptor Relationship Abstract Background. Acidification is one of the important impact cat- egories for life cycle impact assessment. Although its charac- terization has progressed during this decade through the em- ployment of midpoint approaches, only limited studies of endpoint approaches have been performed. Objective. This study aimed at developing damage function of acidification for terrestrial ecosystems in Japan. Damage func- tion expresses a quantitative relationship between the inventory and endpoint damage. Methods. The geographical boundary was limited in Japan both for emission and impact. In this study, sulfur dioxide (SO2), ni- trogen monoxide (NO), nitrogen dioxide (NO2) (NO and NO2 collectively mean NO x ), hydrogen chloride (HCl), and ammo- nia (NH3) were considered as major causative substances of acidi- fication. Net primary production (NPP) of existing vegetation was adopted as an impact indicator of terrestrial ecosystems. The aluminum toxicity was adopted as the major factor of ef- fect on terrestrial ecosystems due to acidification. The leachate concentration of monomeric inorganic aluminum ions was se- lected to express the plant toxicity of aluminum. Results and Discussion. The results of damage function gave utilizable factors both for a midpoint approach and an endpoint approach; Atmospheric Deposition Factor (ADF) and Damage Factor (DF) applicable to the former and the latter, respectively. The ADF indicates an increase of H+ deposition per unit area to an additional emission of causative substance. The additional emission corresponds to some alternatives in industry, not the baseline emission. The DF indicates the total NPP damage in all of Japan due to the additional emission of causative substances. The derived NPP damage is on the order of one millionth of the NPP itself. HCl and NH3 showed larger ADFs and DFs than that of SO2 and NOx. The reason was ascribed to the relatively large source-receptor relationships (SRR) of HCl and NH 3 . However, since the method applied to determine the SRR of HCl and NH3 has larger uncertainties than that of SO2 and NOx, attention is needed to handle the difference. Conclusion. The damage function easily defines the concrete NPP damage due to an additional emission. The impact indica-