Stream 2: Biogeochemical processes
- Nils Moosdorf1, Hannelore Waska2
- 1 Leibniz Center for Tropical Marine Ecology (ZMT), Bremen, Germany
- 2 ICBM University of Oldenburg, Germany
Submarine groundwater discharge (SGD) is an increasingly recognized transport pathway for solutes from land to sea. Sometimes, the term "submarine rivers" is used for locations of strong SGD. Just like rivers, waters and solutes of SDG pass through an estuary, termed the subterranean estuary.
Processes in the subterranean estuary are in some ways similar to surface estuaries: along a salinity gradient chemical reactions change the composition of the solutes, in particularly the available nutrients. However, while surface estuaries can extend over tenths of kilometers, the chemical gradients in subterranean estuaries are extraordinarily steep – the distance between fresh and seawater can be as little as some decimeters. In addition, the subterranean estuary is distinguished from the surface estuary by (i) longer residence times, (ii) a rich, exclusively microbial population, and (iii) a heterogeneous redox zonation. All these factors modulate the fluxes of nutrients, trace metals, and organic matter from land to sea. Because of our increasing recognition of the effects of submarine groundwater discharge on coastal marine ecosystems, it becomes obvious that the impacts of the subterranean estuary can be highly relevant to coastal ecosystems from local to regional scales. We welcome submissions presenting results from both theoretical and practical studies at all scales.