Spatial and temporal dynamics of water isotopes in the riverine-marine
mixing zone along the German Baltic Sea coast
Abstract
River estuaries are characterized by mixing processes between marine
water masses and freshwater inflows depleted in heavier stable isotopes.
Therefore, they often show a linear correlation between salinity and
water isotopes (δ 18O and δ 2H
values). In this study we evaluated spatial and seasonal isotope
dynamics along three estuarine lagoon transects, located at the northern
German Baltic Sea coast. The data show strong seasonality of isotope
values, even at locations located furthest from the river mouths. They
further reveal a positive and linear salinity-isotope correlation in
spring, but hyperbolic and partially reverse correlations in summers. We
conclude, that additional physical processes such as evaporation from
the shallow lagoons, partially overprint the two-phase mixing
correlation during summers. Understanding those water isotope and
salinity dynamics are crucial in context of ecological studies. For
example, when interpreting oxygen and hydrogen isotope data in aquatic
organisms, that depend on ambient estuarine waters.