Ammonia concentrations and fluxes over a forest in the midwestern USA |
| |
Institution: | 1. CORAL, Indian Institute of Technology Kharagpur, Kharagpur 721302, India;2. Agricultural and Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur 721302, India;3. Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India;4. LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France;5. Université libre de Bruxelles (ULB), Service de Chimie Quantique et Photophysique, Atmospheric Spectroscopy, Brussels, Belgium;6. ESSO-Indian Institute of Tropical Meteorology Pune, India |
| |
Abstract: | We present measurements of ammonia (NH3) over a deciduous forest in southern Indiana collected during four field campaigns; two in the spring during the transition to leaf-out and two during the winter. Above canopy NH3 concentrations measured continuously using two Wet Effluent Diffusion Denuders indicate mean concentrations of 0.6–1.2 μg m−3 during the spring and 0.3 μg m−3 during the winter. Measurements suggest that on average the forest act as a sink of NH3, with a representative daily deposition flux of 1.8 mg-NH3 m−2 during the spring. However, on some days during the spring inverted concentration gradients of NH3 were observed resulting in an apparent upward flux of nearly 0.2 mg-NH3 m−2 h−1. Analyses suggest that this apparent emission flux may be due to canopy emission but evaporation of ammonium nitrate particles may also be partly responsible for the observed inverted concentration gradients. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|