Urban metal sinks or biogeochemical hot spots?: potential for interactions

Hotspots of biogeochemical activity allow balancing of otherwise puzzling material budgets in urban systems. Therefore, these hotspots are of great interest as they might be strategically used to manage persistent urban nutrient loadings. However, the landscape position of these hotspots leads to the predictable accumulation of urban contaminants, particularly metals. For example, in Baltimore, riparian soil calcium concentrations are greater than upland soil concentrations , though both increase with urbanization. Despite the spatial coherence, the implications of metal enrichment for ecological and biogeochemical function remains under characterized. Here, we synthesize results from Baltimore with available literature to explore potential interactions and the implications for urban landscape biogeochemistry.