Estimating variation and sources of dust in Puente Jobos, Puerto Rico using a PM10 sensor network.

The Puente Jobos community in southern Puerto Rico has multiple sources of inhalable particulate matter less than 10 μm in diameter (PM10), including a nearby coal-fired power plant, a well-traveled road in the center of town, sea spray, and long-range transport of Saharan dust. In this seven-month field study, we evaluated a PM10 optical particle counter (OPC) sensor network in combination with single site filter-based daily federal reference method (FRM) measurements of PM10 mass, black carbon, and trace elements. The OPC PM10 measurement was strongly correlated with the filter-based PM10 concentrations. Sensor performance was improved by using a locally developed correction relying on the sensor internal relative humidity measurement and the concentration in the smallest OPC size bin. PM10 concentrations were statistically significantly elevated in the southern part of the community, closer to coastal areas and the coal-fired power plant. Positive matrix factorization (PMF) was used to identify seven major sources including three associated with coal operations (ash - 9%, stack emissions with elevated sulfur - 9%, and other processes with elevated phosphorous - 17%), sea salt derived (37%), crustal derived (22%), diesel or oil combustion derived (6%), and demolition derived (<1.0%). This study demonstrated the utility of lower-cost OPCs to complement FRM measurements of PM10 composition to identify the sources and the spatial and temporal variation of PM10 in a community.