The Taiwanese Nitrogen Footprint: Trends and Comparisons with Other Regions

Abstract

Excess emissions of reactive nitrogen (Nr; all N species except N₂) have been known to cause many environmental and human health issues. Recently, the nitrogen (N) footprint indicator has been developed and used to specify the influence of the human use of Nr on the environment. This paper addresses the questions of (1) What is the total per-capita N footprint (NFP) of food, transportation, goods & services, and housing in Taiwan, and how has it changed over ten years? (2) What are the potential factors that influence the NFP? and (3) What is the difference between the Taiwanese N footprint and those of other countries? The results show that Taiwan's virtual nitrogen factors (VNFs; Nr losses to the environment during food production, processing, and transportation per N consumed) are similar to Japanese VNFs (without accounting for trade), possibly due to comparable dietary and farming technologies. The 10-year average of Taiwan's food production and food consumption N footprints were 21 kg N capita^-1 yr^-1, respectively. Furthermore, the food N footprints for crop and animal products were 12.0 and 20.3 kg N capita^-1 yr^-1, respectively. The 10-year average of the total NFP is 34.2 kg N capita^-1 yr^-1.  The Taiwan N footprint was highly dependent on food production processes per unit of Nr consumed. The Taiwan NFP has decreased by 6% over ten years, likely as a result of promoting a pollution prevention policy and a reasonable fertilizer application policy. Additionally, a correlation coefficient and multiple regression have been applied to test the relationship of NFP with social-economy variables. The results show significantly related crop production NFP with fertilizer being used positively.  Therefore, good agricultural and environmental policies can help with preventing the N threat to the environment. In addition, a comparison of NFP results in seven countries located on four continents  (Asia, North America, Europe, and Australia) revealed that the factors of nutrient N use, sewage denitrification rate, food waste from consumer levels, dietary habits, and socio-economic indicators influence the calculated NFPs. In future studies, it will be important to combine this NFP estimate for Taiwan with other social, economic, and environmental indicators to develop an integrated assessment of nitrogen threats and benefits in Taiwan.

Keywords: Virtual Nitrogen Factor, Nitrogen Footprint, GDP, Nitrogen Policy