High concentrations and dry deposition of reactive nitrogen species at two sites in the North China Plain.

Atmospheric concentrations of major reactive nitrogen (N(r)) species were quantified using passive samplers, denuders, and particulate samplers at Dongbeiwang and Quzhou, North China Plain (NCP) in a two-year study. Average concentrations of NH(3), NO(2), HNO(3), pNH(4)(+) and pNO(3)(-) were 12.0, 12.9, 0.6, 10.3, and 4.7 microg N m(-3) across the two sites, showing different seasonal patterns of these N(r) species. For example, the highest NH(3) concentration occurred in summer while NO(2) concentrations were greater in winter, both of which reflected impacts of N fertilization (summer) and coal-fueled home heating (winter). Based on measured N(r) concentrations and their deposition velocities taken from the literature, annual N dry deposition was up to 55 kg N ha(-1). Such high concentrations and deposition rates of N(r) species in the NCP indicate very serious air pollution from anthropogenic sources and significant atmospheric N input to crops.