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Changes of urban nitrogen metabolism in the Beijing megacity of China, 2000–2016.
- Source :
-
Science of the Total Environment . May2019, Vol. 666, p1048-1057. 10p. - Publication Year :
- 2019
-
Abstract
- Abstract Rapid growth in metropolitan areas is associated with high nitrogen (N) flows and subsequent environmental and human health consequences. Many studies on the contemporary aspects of urban N metabolism have conducted in recent years, but comprehensive analysis from life cycle perspective is limited. In this study, a detailed quantitative framework for a coupled human-natural N flow model, comprising a full cycle analysis based on the substance flow analysis approach to cover and integrate all specific N flows and stocks associated with N production, consumption and emission, was developed to study the temporal changing patterns of N metabolism in Beijing megacity during 2000–2016. The results show that total N inputs continuously increased from 413.3 to 529.5 Gg N during the study period, primarily attributing to fossil fuel combustion (53%), fertilizer/feed import (19%), and food import (15%). Agriculture subsystem contains the largest N internal flows, and a decreasing trend is exhibited by a widening gap between local production and household consumption, reflecting Beijing's increasing dependence on the external environment. Moreover, N outputs (394.9 Gg in 2016) contribute to upstream air emissions, landfills accumulation and downstream wastewater discharges. Furthermore, driving force analysis demonstrates that population growth has the largest positive effect on N inputs, and a decoupling of N input with GDP growth is identified. Overall, N flows exhibit an inefficient and unsustainable trend, and possible options for optimizing more sustainable situations while simultaneously minimizing negative consequences are discussed. This study provides decision-makers with an integrated view of N management at the city scale. Graphical abstract Unlabelled Image Highlights • An analytical framework for coupled human-natural N flow model is established. • The whole N production-consumption-emission processes were identified. • Population and economic growth are key factors driving the increasing N inputs. • The disparity between local production and household consumption widens. • A considerable N emission to air and accumulated in landfills were observed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00489697
- Volume :
- 666
- Database :
- Academic Search Index
- Journal :
- Science of the Total Environment
- Publication Type :
- Academic Journal
- Accession number :
- 135688313
- Full Text :
- https://doi.org/10.1016/j.scitotenv.2019.02.315