Trace metals in nectar of important urban pollinator forage plants: A direct exposure risk to pollinators and nectar-feeding animals in cities

Pollinators are exposed to metals while foraging in the landscape and accumulate detectable concentrations of trace metals within their bodies, although major exposure routes remain unclear. As nectar is the main source of food for pollinators, we analyzed trace metal content within floral rewards to identify if nectar contained detectable metals and may serve as an oral exposure route. Nectar from flowering plant species growing within vacant lots in the city of Cleveland, OH, USA, was extracted using a centrifuge and tested for metals using ICP-MS. We collected volunteer flower species that are common pollinator forage plants. Nectar metal content varied by plant and metal species, but not by location. This work demonstrates the complexity of identifying metal exposure risk based on soil metal data alone, as oral metal exposure is dependent on plant species, metal species, and soil characteristics.