Dry deposition of reduced and reactive nitrogen: A surrogate surfaces approach.

摘要

Nitrogen deposition constitutes an important component of acidic deposition to terrestrial surfaces. However, deposition flux and ambient concentration measurement methods and are still under development. A new sampler using water as a surrogate surface was developed in the Department of Environmental Engineering at Illinois Institute of Technology. This study investigated nitrate and ammonia dry deposition to the water surface sampler, a Nylasorb filter, a citric acid impregnated filter, and a greased strip on the dry deposition plate.; The nitrogen containing species that may be responsible for nitrate dry deposition to the WSS include nitrogen monoxide (NO), nitrogen dioxide (NO{dollar}sb2{dollar}), peroxyacetyl nitrate (PAN), nitrous acid (HNO{dollar}sb2{dollar}), nitric acid (HNO{dollar}sb3{dollar}), and particulate nitrate. The experimental measurements showed that HNO{dollar}sb3{dollar} and particulate nitrate are the major nitrate contributors to the WSS. Ammonia sources to the water surface are ammonia gas (NH{dollar}sb3{dollar}) and ammonium (NH{dollar}sb4sp+{dollar}). The experimental results showed that these two species are the sole sources to ammonium deposition.; Comparison between the measured deposition velocity of SO{dollar}sb2{dollar}, and HNO{dollar}sb3{dollar}, shows that their dry deposition velocities are statistically the same at the 95% confidence level and NH{dollar}sb3{dollar} deposition velocity and the water evaporation rate are also the same. It was also shown that the air side MTC of two different compounds were correlated to the square root of the inverse of the molecular weight for compounds.; The measured MTC was tested by the application of two models, the resistance model and the water evaporation model. The resistance model prediction of the MTC was very close to the measured value but the evaporation model prediction was not. This result is compatible with the finding of Yi, (1997) who used the same WSS for measurements of SO{dollar}sb2.{dollar}; The experimental data collected in this research project was used to develop an empirical model to measure the MTC that is {dollar}rm {lcub}klover D{rcub}{dollar} = 0.0426{dollar}rm ({lcub}lvrhoover mu{rcub})sp{lcub}0.8{rcub}({lcub}muover rho {lcub}rm D{rcub}{rcub})sp{lcub}0.33{rcub}{dollar}; This model was statistically tested to verify that the measured MTC and the model prediction was statistically the same mean at the 95% confidence level. This indicates that the model can be used to predict the MTC of chemicals that have only air side resistance.