Location: Soil, Water & Air Resources Research2012 Annual Report
1a. Objectives (from AD-416):
1. Improve methods for the quantification of emissions from individual agricultural sources and whole agricultural facilities or management operations. 2. Develop methods to predict emissions and their dispersion from individual sources and whole facilities or management operations. 3. Validate the prediction tools for a variety of agricultural sources.
1b. Approach (from AD-416):
In a previous project a prototype lidar system for measuring particulate matter emissions was developed and evaluated. This system will be refined to improve the portability, usability and reliability for routine measurements across a wide variety of agricultural systems. Evaluation of the system will include comparisons against in situ samples of particulates to increase the reliability of the method using accepted EPA verification methodologies. Comparisons will be used to provide detailed specifications of the performance capabilities of the unit. Evaluation of the emissions measurement capabilities will be conducted under laboratory and field conditions. Integration of the particulate and gaseous units with ancillary micrometeorology will be coordinated with ARS scientists during field measurements. The development of new systems for the measurement of gaseous emissions from agricultural sources will include identification of the most critical gases of interest to agriculture, characterization of system capabilities, and performance compared to accepted standards. A project review will be conducted during the first year.
3. Progress Report:
Particulate matter (PM) emissions from agricultural operations are an important issue for air quality and human health and a topic of interest to government regulators. PM emission rates from a dairy in the San Joaquin Valley of California were investigated on a facility with 1,885 total animals - 950 milking cows housed in free-stall pens with open lot exercise areas and 935 dry cows, steers, bulls, and heifers housed in open lots. Point sensors, including filter-based aerodynamic mass samplers and optical particle counters (OPC), were deployed at select points around the facility to measure optical and aerodynamic particulate concentrations. Simultaneously, vertical PM concentration profiles were measured both upwind and downwind of the facility using lidar. The lidar was calibrated to provide mass concentration information using the OPCs and filter measurements. Emission rates were estimated over this period using both an inverse modeling technique coupled with the filter-based measurements and a mass balance technique applied to lidar data. Mean emission rates calculated using inverse modeling (± 95% confidence interval) were 2.8 (± 2.3), 17.4 (± 10.2), and 53.8 (± 22.2) g/d/AU for PM2.5, PM10, and total particulates, respectively. Mean emissions rates based on lidar data were 1.3 (± 0.2), 15.1 (± 2.2), and 46.4 (± 7.0) g/d/AU for PM2.5, PM10, and TSP, respectively. The PM10 findings are roughly twice as high as those reported from other dairy studies with different climatic conditions and/or housing types, but of similar magnitude as those from a study with similar conditions, housing, and emission rate calculation technique.