Using X-ray Fluorescence to Detect Automobile Heavy Metal Pollution in Los Angeles Soils with Copper and Palladium as Indicators

This project evaluates the effectiveness of using portable X-ray Fluorescence (XRF) to detect soil composition matrices that show patterns of anthropogenic influence. We explore 26 areas within Los Angeles County, California, that have various amounts of traffic; classifying each locale as Urban or Recreational. The main elements of interest are copper and palladium. These indicators are largely theorized to originate from brake pad wear-and-tear and vehicle emissions. Wildfires and the degradation of city related infrastructures provide additional context to the concentrations of copper that are found within each area. In all samples, copper was reliably detected with an average concentration of 29.35 ± 24.74 parts per million (ppm). Elevated copper levels were notably associated with areas of high traffic density. This supports its use as an elemental marker for vehicle brake-pad pollution. Palladium, by contrast, was detected at an average of 19.54 ± 9.63 ppm across the region. However, higher relative measurement uncertainty and a lack of clear spatial variability suggest that these measurements may be affected by instrumental noise or soil matrix interference. Furthermore, the difference between concentrations found here and previous studies from around the world makes palladium less reliable for environmental assessment. Overall, these findings support the use of portable x-ray fluorescence for rapid screening of copper for tracking automobile activity; while highlighting limitations in its ability to accurately quantify trace levels of palladium.