Abstract
Riverine nitrogen (N) export is a crucial process that links upstream and downstream ecosystems and coastal zones. However, the driving forces of riverine N export that is closely related to water N pollution are still not well understood. In this study, we used a mass balance approach to quantify the sources of N discharge and analyzed the effect of land use composition on riverine N export, taking Zhejiang Province, China as a case study. We found that the total reactive N discharge to rivers in Zhejiang increased from 0.22 to 0.26 Tg yr-1 from 2000 to 2015. At the watershed scale, our estimate of N export agrees well with the monitored riverine N concentration in the eight major watersheds in Zhejiang. Direct discharge of domestic wastewater and effluents from wastewater treatment plants are dominant sources of riverine N export, followed by agricultural non-point sources. Although riverine N export increases with the increasing proportion of urban and agricultural land uses, we did not find any relationship between land use change and changes in riverine N export. This suggests that the dominant factor affecting riverine N export should be human activities (e.g. wastewater discharge and fertilization level), while land use only mediates riverine N export.
Original language | English |
---|---|
Article number | 094018 |
Journal | Environmental Research Letters |
Volume | 12 |
Issue number | 9 |
DOIs | |
Publication status | Published - 18 Sept 2017 |
Funding
This work was supported by National Science Foundation of Zhejiang Province (LR15G030001), National Natural Science Foundation of China (41773068) and the Open Fund of Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture, China (1610132016005).
Funders | Funder number |
---|---|
Key Laboratory of Nonpoint Source Pollution Control | |
Ministry of Agriculture, China | 1610132016005 |
National Science Foundation of Zhejiang Province | LR15G030001 |
National Natural Science Foundation of China | 41773068 |
Keywords
- buffer zone
- human activities
- land use change
- mass balance
- scale effect
- source apportionment