Composition and temporal variation of atmospheric nitrogen wet deposition in Jinyun Mountain,southwestern China.

and rainfall intensity have little impact on N concentration.Field observation of nitrogen wet deposition in Jinyun Mountain, the natural conservation station of southwestern China, was fixed collected by APS-2A precipitation-dust automatic acquisition instrument from May to October 2012, based on which the composition, monthly and seasonal variation of nitrogen wet deposition were analyzed. Results showed that: 1) the concentration of NH+ 4 -N was higher than that of NO- 3 -N and DON (dissolved organic nitrogen), indicating that emission load of NH3 within this area was generally high; 2) the major form of atmospheric reactive nitrogen in Jinyun Mountain area was reduced nitrogen NH+ 4 -N, which primarily came from agricultural productivity; 3 ) the average concentrations of NO3-N, NH+ 4 -N and DON in precipitation were (0.441 ±0.304), (0.821 ±0.80) and (0.203 ±0.211) mg/ L during the monitoring period, respectively, of which the above three nitrogen forms ranked in NH+ 4 -N NO- 3 -N DON; 4) the highest concentrations of NO- 3 -N, NH+ 4 -N and DON all occurred in May, and the average values were (0.642 ±0.292), (1.273 ±0.739) and (0.329 0.231) kg/ hm2, accounted for 29.76%, 56.27% and 13.98% of the total nitrogen wet deposition, respectively; 5) nitrogen concentration was weakly correlated with rainfall and rainfall intensity, while the total nitrogen wet deposition presented an obvious linear correlation with the precipitation amount (P 0.01), which demonstrates that nitrogen wet deposition is mainly affected by rainfall, but rainfall