US EPA

Development and Validation of a Novel Technique to Measure Ambient Particle Properties: Bound Water, Mass Density, and Mean Diameter

EPA Grant Number: R825336
Title: Development and Validation of a Novel Technique to Measure Ambient Particle Properties: Bound Water, Mass Density, and Mean Diameter
Investigators: Koutrakis, Petros , Allen, George , Ferguson, Stephen T. , Wolfson, Mike
Current Investigators: Koutrakis, Petros
Institution: Harvard University
EPA Project Officer: Stelz, Bill
Project Period: December 1, 1996 through November 30, 1999 (Extended to March 31, 2001)
Project Amount: $380,111
RFA: Analytical and Monitoring Methods (1996) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Environmental Statistics , Water , Land and Waste Management , Air , Ecological Indicators/Assessment/Restoration

Description:

The objectives of this proposed research include development of a novel particle monitoring technique that measures particle mass, density, mean diameter, and bound water, based on a recently developed continuous particle mass monitor. In addition, a field study will be conducted to validate the performance of the new method in a typical urban environment and to investigate relationships between particle water content and particle size, particle composition, relative humidity and temperature. It is expected that the new method will be accurate, sensitive, relatively inexpensive and easy to use. Simultaneous measurement of the different particle parameters can be very useful in understanding the behavior of hygroscopic aerosols, including determination of important thermodynamic parameters such as molarity, water activity, activity coefficients, molar volumes, etc. In addition, laboratory and field studies will be conducted to validate the performance of the new technique and develop a better understanding of the hygroscopic properties of ambient particles. The recently developed particle mass monitor collects particles using a NucleporeTM filter, and the mass concentration is determined by measuring the pressure drop across the filter as a function of time. Laboratory and field tests showed excellent agreement between this method and gravimetric analysis. The new system will have two sets of two independent channels, for fine and coarse mass, respectively. For each size range there will be channels with and without diffusion dryers, to measure dried and undried particles, respectively. Each channel will have a series of three filter stages, each with a pressure transducer. The combined results from all channels will allow determination of particle mass concentration, average density, and mean diameter. Since hygroscopic ambient particles can be the media for a number of important homogeneous aqueous phase reactions, accurate measurement of particle-bound water is of paramount importance to the field of atmospheric chemistry. Moreover, particle water content affects particle-light interactions, and is therefore essential information for understanding and modeling visibility reduction.

Publications and Presentations:

Publications have been submitted on this project: View all 6 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 3 journal articles for this project

Supplemental Keywords:

monitoring, continuous, aerosols, water, measurement, atmospheric chemistry., RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Ecology, Environmental Chemistry, Chemistry, Monitoring/Modeling, Engineering, particle size, bound water, ambient particle properties, chemical characteristics, particulate, particles, urban environment, hydroscopic aerosols, air quality, atmospheric chemistry, validation, thermodynamics

Progress and Final Reports:

1997 Progress Report
1998 Progress Report
2000 Progress Report
Final Report