Patterns of Pore Water Chemistry which produced non-uniform groundwater flow conditions. We conclude that on mesotidal high energy beaches, the rapidly changing beach morphology produces zones with different approximations to steady-state conditions. Therefore, we suggest that zone-specific endmember sampling is the optimal strategy to reduce uncertainties of SGD-driven constituent fluxes.

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Owing to advanced analytical procedures an increasing number of organic micropollutants have been identified within the aquatic environment. Results from field investigations evidenced the attenuation of various organic micropollutants to be impacted by the predominant hydrochemical conditions. In the course of this study, column experiments were performed to examine the influence of redox conditions and temperature on the attenuation of 20 wastewater derived organic micropollutants. For this purpose, the degradation behavior of these compounds were investigated under oxic, nitrate reducing, iron/manganese reducing and sulfidic conditions at 21 °C in sandy aquifer sediments. Redox dependent degradation was observed for the pharmaceutically active compounds atenolol, metoprolol, sotalol, iopromide, phenazone, propyphenazone, acesulfame and trimethoprim as well as for two phenazone type metabolites. In order to identify temperature dependencies, oxic columns were in addition operated at 6 °C, indicating the removal of several compounds to be influenced by the prevalent temperature.

Accurate SGD (submarine groundwater discharge) mass export calculations require detailed knowledge of the spatial and temporal variability in SGD rates. In coastal aquifers, SGD includes a terrestrial freshwater component as well as a saline component originating from circulating seawater. Representative field measurements of SGD rates are difficult to conduct, because SGD is often patchy, diffuse, and temporally variable, especially under tidal influence and high wave activity. In this study, a combination of lysimeters, seepage meters, temperature sensors, pore water radon, and numerical modeling was used to estimate the volumes of infiltrating seawater and exfiltrating groundwater in the intertidal zone of a mesotidal, high energy beach on Spiekeroog Island, northern Germany. Additionally, a 3D-laser scanner was used over short (days) and medium time scales (months) to determine changes in beach topography. The results showed net water infiltration above mean sea level (MSL) and net exfiltration below MSL. Water exchange rates fluctuated between 0.001 and 0.61 m day−1, showing similar ranges within the multiple method approaches. The beach topography was subject to strong fluctuation caused by waves, currents, wind driven erosion and sedimentation, even over short time scales. A comparison of extrapolated in- and exfiltrating water volumes along a beach transect from the mean high water to mean low water line at different times highlights the variability of total in or outflow. The results show that exchange rates depend on beach topography, which in turn changes significantly over time.

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