摘要：Human activity greatly influences nitrogen (N) pollution in urbanized and adjacent areas.
We comprehensively studied the N cycling in an urban–rural complex system, the Greater
Hangzhou Area (GHA) in southeastern China. Our results indicated that subsurface N
accumulation doubled, riverine N export tripled and atmospheric N pollutants
increased 2.5 times within the GHA from 1980–2004. Agriculture was the largest
N pollution source to air and water before 2000, whereas industry and human
living gradually became the primary N pollution sources with the socioeconomic
development. Based on the sensitivity analysis, we developed a scenario analysis to
quantify the effects of technology and policy on environmental N dynamics. The
fertilization reduction scenario suggested that the groundwater N pollution could
decrease by 17% with less than a 5% reduction in crop production; the N effluent
standard revision scenario led to a surface water N pollution reduction of 45%; the
constructed wetlands implementation scenario could reduce surface water pollution by
43%–64%. Lastly, the technological improvement scenario mitigated atmospheric N
pollution by 65%. Technologies play a key role in atmospheric N pollution control,
policies mainly contribute to groundwater N pollution control, while technology and
policy both work on surface water N mitigation within an urban–rural complex.
