Geospatial patterns and geochemical fingerprints reveal anthropogenic enrichment of phosphorus from mining in the Uinta Mountains, Utah, USA

Phosphorus (P) is a non-renewable resource essential to all life, yet anthropogenic influences have drastically altered its natural biogeochemical cycle. Phosphate rock mining is a major human perturbation of the P cycle that can emit P-rich fugitive dust to surrounding landscapes. For example, dust collected near a phosphorus mine in northeastern Utah, USA, had phosphorus concentrations more than four times higher than those of other regional samples. This observation suggests that mining emissions may enhance soil P loading through dust deposition; however, the abundance and spatial extent of mine-attributable P enrichment in surrounding soils remain unquantified. Here, we combine geospatial and geochemical analyses to show that fugitive dust emissions from phosphate rock mining enrich surrounding soils with P up to 8 km from the mine (enrichment factor > 1.5), with the most significant enrichment occurring within the first 4 km (enrichment factor > 2). On average, surface P concentrations were enriched by 25% within 8 km of the mine. Observed P enrichment was positively correlated with the presence of fluorapatite in the soil, the primary P-bearing mineral extracted from the mine. Measurements of labile-P within 1 km of the mine indicate possible localized increases in bioavailable P in P-enriched soils. These results provide the first quantitative evidence that fugitive dust emissions from phosphate rock mining measurably increase soil P levels in subalpine ecosystems, with implications for long-term P cycling and watershed nutrient loading.