Nutrients in Sediment and Overlying Water in the Homa Lagoon of İzmir Bay (Aegean Sea, Turkey)

Benthic fluxes of biogenic compounds play a critical role in the biogeochemistry of shallow aquatic ecosystems. Measuring these fluxes at the lagoon scale is challenging due to heterogeneous sediment structures and the combination of diffusion and advective transport processes at the sediment-water interface. In this study, monthly nutrient flux experiments were conducted in the sediment of İzmir Bay Homa Lagoon (Aegean Sea, Turkey). The flux of reactive silicate (RSi) ranged from 14.6 to 255.24 μgatSi/m²/hour, while the ammonium (NH4+) flux varied between 3.59 and 95.8 μgatN/m²/hour. The nitrite (NO2-) flux ranged from 0.93 to 13.99 μgatN/m²/hour, and the nitrate (NO3-) flux varied from 27.76 to 300 μgatN/m²/hour. The flux of reactive phosphorus (RP) ranged from 0.74 to 5.80 μgatP/m²/hour. The research indicated that the RSi flux peaked during the summer months, while the NO3- flux occurred in both winter and summer, transferring nutrients from sediment to water and vice versa. It was determined that the NO2- flux significantly transferred to the sediment, except during the summer months. The RP flux flowed from sediment to water during the summer, while it was bound to the sediment during mid-winter and autumn. The NH4+ flux showed transitions from sediment to water in winter and from water to sediment in summer. In conclusion, the fluxes of NO3-, NH4+, and RP indicate that these components are sediment-derived.