Spatial variations of environmental tracer distributions in water from a mangrove ecosystem: the case of Babitonga Bay (Santa Catarina, Brazil).

The hydrologic complex of Babitonga Bay (Brazil) forms a vast environmental complex, where agriculture, shellfish farming, and industries coexist with a unique natural area of Atlantic rain forest. The origin of different continental hydrological components, the environmental transition between saline and fresh waters, and the influence of the seasonality on Babitonga Bay waters are evaluated using isotopes and chemistry. The end of the dry season is marked by a fast response of continental water to the first rainfall, while in the Bay this change is delayed in time. At the end of the rainy season waters show a more homogeneous isotopic composition, suggesting the harmonisation of hydrological and hydrogeological systems. Moreover, δ13C and δ15N of DIC and POM allows for the definition of the biogeochemical processes originating and transporting chemical compounds in the coastal and transition areas and for the determination of three distinct end-members: terrestrial, marine and urban.