A Statistical and Theoretical Investigation of the Chemistry of the Formation of Atmospheric Particles in Beltsville, Maryland via Observations of Physical Properties

Ion and trace gas measurements were performed with a newly developed Monitoring Instruments for Aerosols and Gases (MARGA) instrument. The MARGA gas measurements were successfully compared to similar instruments. A Laser Particle Counter (LPC) and Thermo Environmental Instrument Company (TECO) analyzers were used to obtain in-situ number density distribution and trace gas concentrations, respectively. Their ambient measurements showed that sulfuric acid and sulfate aerosols dominate the new particle formation events.;In addition, statistical analytics show that the major determining factors that influenced the new particle formation (NPF) were wind speed and the amount of surface area available from preexisting aerosol particles. NPF occurred during the nights with low wind speed, and RH levels greater than 65%. The observed ratio ammonium to sulfate was 1:1, which suggest that sulfuric acid with ammonia partial neutralizes and ammonium bisulfate is the dominant species in the clusters. Other variables that influenced particle formation include emissions from nearby highway traffic and solar radiation.;This study has also shown that the chemistry of new particle formation or production and subsequent growth are affected by three major components regional transport chemistry, local transformation chemistry, and rate of local pollution emissions. In addition, we find that the influence of these chemical processes can change based on diurnal cycles. This work may provide additional insights into the compounds and environmental conditions participating both in the initial formation and in subsequent growth of atmospheric aerosol particles. The results show the NPF is associated with Sulfur dioxide oxidation, condensation of volatile gases, and hygroscopic reactions, which are inhibited by the liquid aerosol surface area such that NPF competes with the liquid aerosol surface reactions. The principal components and correlation statistical analysis coefficients may provide inputs for simplified model parameterization, which can be used as a part of a larger atmospheric model to predict NPF and the concentration of climatically active particles.