In PNAS (1), we highlight changes in the balance of oxidized and reduced nitrogen contributions to US reactive nitrogen (N) deposition. Successful reductions in nitrogen oxides (NOx) emissions combined with modest growth in ammonia emissions have now tipped the balance in most regions toward deposition of reduced N species, ammonia and ammonium. Liu et al. (2) respond, making two main points. F...

Gaseous and size-segregated particulate PBDEs (specifically BDE-47, -99, -183, -207, and -209) in the air were measured in urban Guangzhou at 100 and 150 m above the ground in daytime and at night in August and December 2010, to assess dry deposition of these contaminants accurately with regards to influences of meteorological factors but without confounding surface effects. Particulate PBDEs w...

We investigated the suitability of integrating deterministic models to estimate the relative contributions of atmospheric dry and wet deposition onto an urban surface and the subsequent amounts removed by stormwater runoff. The CIT airshed model and the United States Environmental Protection Agency Storm Water Management Model (SWMM) were linked in order to simulate the fate and transport of ni...

The legacy of long-term mining activities in Wanshan mercury (Hg) mining area (WMMA), Guizhou, China including a series of environmental issues related to Hg pollution. The spatial distribution of gaseous elemental mercury (Hg0) concentrations in ambient air were monitored using a mobile RA-915 Zeeman Mercury Analyzer during daytime and night time in May 2010. The data imply that calcines and m...

Five regional scale models with a horizontal domain covering the European continent and its surrounding seas, two hemispheric and one global scale model participated in the atmospheric Hg modelling intercomparison study. The models were compared between each other and with available measurements from 11 monitoring stations of the EMEP measurement network. Because only a very limited number of l...

A parameterization scheme for calculating gaseous dry deposition velocities in air-quality models is revised based on recent study results on non-stomatal uptake of O3 and SO2 over 5 different vegetation types. Non-stomatal resistance, which includes in-canopy aerodynamic, soil and cuticle resistances, for SO2 and O3 is parameterized as a function of friction velocity, relative humidity, leaf a...

Wet and dry mercury (Hg) deposition were calculated to Lake Michigan using a hybrid receptor modeling framework. The model utilized mercury monitoring data collected during the Lake Michigan Mass Balance Study and the Atmospheric Exchange Over Lakes and Oceans Studytogether with high-resolution over-water meteorological date provided by the National Oceanic and Atmospheric Administration (July,...

This paper describes the development of a simple quasi-2D Eulerian atmospheric dispersion model that accounts for dry deposition of fugitive dust onto vegetation and buildings. The focus of this work is on the effects of atmospheric surface layer parameterizations on deposition in the “impact zone” near unpaved roads where horizontal advection of a dust cloud through roughness is important. A w...

The effect of dry and wet deposition of semivolatile organic compounds (SVOCs) in the gas phase on the concentrations of secondary organic aerosol (SOA) is reassessed using recently derived water solubility information. The water solubility of SVOCs was implemented as a function of their volatility distribution within the WRFChem regional chemistry transport model, and simulations were carried ...

Wet and dry depositions of aerosols in WRF-Chem are revisited updated based on recent observational findings. Traditionally, in-cloud scavenging was thought to play a more dominant role aerosol wet removal than below-cloud scavenging. However, field measurements indicated considerable contribution 50%–60% total deposition. In contrast, the simulated previous version too large, exhibiting 88%–95...