Sources of dissolved inorganic nitrogen in a coastal lagoon adjacent to a major metropolitan area, Miami Florida (USA).

Highlights: [•] A range of biota (algae and sea grasses) shows enriched δ15N close to the coast. [•] Enriched signals are evident in the particulate and sedimentary organic material. [•] δ15N signals are correlated with high inputs of dissolved inorganic matter. [•] The enriched values support the presence of a sewage related component. [•] The δ15N could arise from the local landfill, injected wastewater, or septic systems. [Copyright &y& Elsevier]