COMPREHENSIVE TRACE ELEMENT AND POLLUTION ANALYSIS OF ROAD SEDIMENT NEAR THE AES POWER PLANT, GUAYAMA, PUERTO RICO

Road sediments have the potential to accumulate heavy metals and other toxic materials from various sources, including vehicular emissions, tire and brake wear, degradation of pavement, and other anthropogenic sources. This study evaluates heavy metal contamination in road sediments collected near the AES coal-fired power plant in Guayama, Puerto Rico, by combining new transect road samples (n=15) with previously collected road sediment samples (n=10). Metal concentrations ranged from upper continental crust values to several orders of magnitude higher, indicating some level of pollution is observed. The metal concentrations in the combined dataset vary widely and include V (58.17 to 412.55 ppm), Cr (17.14 to 283.50 ppm), Co (9.45 to 46.76 ppm), Ni (7.60 to 191.28 ppm), Cu (15.73 to 167.68 ppm), Zn (13.22 to 189.78 ppm), and Pb (1.23 to 124.59 ppm). Strong correlations were observed between Ni and Cr (r² = 0.96, p = <0.001), moderate correlations were found between V and Cu (r² = 0.68, p <0.001), and a weak correlation was observed between zinc and copper (r² = 0.34, p = 0.002). X-ray diffraction (XRD) analysis of the samples revealed the dominance of quartz, calcite, feldspars, and minor pyroxene, suggesting some influence from mafic rock sources. Some samples contain amphiboles, talc, chlorite, and augite, indicating a complex mineral assemblage. Therefore, while there is no strong correlation between siderophile elements and Fe, the concentrations of Ni, Cr, and V in the samples are likely partly derived from natural mafic minerals. Zn and potentially associated Cu are likely anthropogenic pollutants, as Zn is not typically associated with mafic rock sources. Ongoing electron microscopy, geochemical analysis, and comparison to environmental background levels will provide further insight. These findings highlight contamination from industrial activities, specifically the AES power plant, and emphasize the need for continued investigation into the distribution and impact of heavy metals in road sediments. This research contributes valuable insights into environmental pollution, health risk assessment, and land management strategies, and supports future studies on road sediment contamination in Puerto Rico.