Nitrous Oxide (N2O) emissions from human waste in 1970-2050
Strokal, M. ; Kroeze, C. - \ 2014
Current Opinion in Environmental Sustainability 9-10 (2014). - ISSN 1877-3435 - p. 108 - 121.
water treatment-plant - coastal waters - climate-change - future-trends - sewage-sludge - anthropogenic nitrogen - reactive nitrogen - nutrient export - surface-water - united-states
Nitrous oxide (N2O) is an important contributor to climate change. Human waste is an important source of N2O emissions in several world regions, and its share in global emissions may increase in the future. In this paper we, therefore, address N2O emission from human waste: collected (from treatment and from sewage discharges) and uncollected waste. We review existing literature on emissions and emission factors, and present region-specific estimates of N2O emissions and their past and future trends. We show that human waste may became an important source of N2O emissions in the coming years as a result of increasing urbanization. About two-thirds of the global emissions are from uncollected waste, and about half from South Asia. We argue that more research is needed to improve emission factors.
Short and long-term impacts of nitrogen deposition on carbon sequestration by forest ecosystems
Vries, W. de; Du, E. ; Butterbach-Bahl, K. - \ 2014
Current Opinion in Environmental Sustainability 9-10 (2014). - ISSN 1877-3435 - p. 90 - 104.
dissolved inorganic nitrogen - warm-temperate forest - elevated n inputs - terrestrial ecosystems - european forests - climate-change - boreal forest - anthropogenic nitrogen - microbial biomass - tropical forests
The carbon to nitrogen response of forest ecosystems depends on the possible occurrence of nitrogen limitation versus possible co-limitations by other drivers, such as low temperature or availability of phosphorus. A combination of nitrogen retention estimates and stoichiometric scaling is used to illustrate the most likely carbon–nitrogen responses for needle-leaved and broadleaved forests to atmospheric nitrogen deposition. Results are evaluated against field observations and nitrogen addition experiments. The likely change in carbon to nitrogen response with nitrogen deposition level is hypothesized, distinguishing three threshold values that mark the forest carbon responses. We estimated that at global scale nitrogen deposition currently increases the forest carbon sink by 276–448 Tg C yr1, with approximately 60% retained in tree wood and 40% in soil. Furthermore, the long-term carbon response to nitrogen, accounting for nitrogen saturation over time is hypothesized. In this context, the role of global scale coupled carbon–nitrogen models is also evaluated in view of current knowledge affecting carbon–nitrogen responses, including interactions with other drivers.
Future Trends in Nutrient Export to the Coastal Waters of South America: Implications for Occurrence of Eutrophication
Struijk, F. ; Kroeze, C. - \ 2010
Global Biogeochemical Cycles 24 (2010). - ISSN 0886-6236 - 14 p.
anthropogenic nitrogen - marine ecosystems - global system - algal blooms - rivers - pollution - inputs - ocean - sea
We analyze future trends in nutrient export to the coastal waters of South America, with a special focus on the causes of nutrient export and their potential effects. Nutrient Export from Watersheds (NEWS) model results for South America are presented, including trends in human activities and the associated river export of nutrients for the period 1970–2050. For 25 areas in coastal waters of South America where eutrophication or hypoxia has been observed, we investigate how these relate to NEWS model output. For selected watersheds we discuss the causes of increased nutrient loadings of rivers and future trends as projected by the NEWS models