Tidal variations in groundwater storage and associated discharge from an intertidal coastal aquifer

Riedel, Thomas; Lettmann, Karsten; Beck, Mélanie; Brumsack, Hans‐Jürgen

doi:10.1029/2009jc005544

Cited by 34 publications

(53 citation statements)

References 49 publications

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“…Beck et al, 2008;Billerbeck et al, 2006;Grunwald et al, 2010;Marchant et al, 2014;Moore et al, 2011;Riedel et al, 2011;Røy et al, 2008;Santos et al, 2015). Pore water discharge rates calculated for nearby sandy Wadden Sea sediments vary depending on the method applied and the sediment depth considered Moore et al, 2011;Riedel et al, 2010), among which the method most comparable to the model approach applied in our study resulted in lower flux rates (0.97 m −3 per tide and meter of shoreline, which equals~2 m −3 per day and meter of shoreline; Riedel et al, 2010) compared to our study. Due to the high nutrient enrichment in the tidal flat pore waters compared to Spiekeroog beach sediments (Reckhardt et al, 2015), the nutrient efflux from these sediments can, however, be higher compared to the beach site.…”

Section: Pore Water Discharge Influences Phytobenthos and Nearshore Wcontrasting

confidence: 47%

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

et al. 2017

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This study addresses key processes in high-energy beach systems using an interdisciplinary approach. We assess spatial variations in subsurface pore water residence times, salinity, organic matter (OM) availability, and redox conditions and their effects on nutrient cycles as well as on microbial community patterns and microphytobenthos growth. At the study site on Spiekeroog Island, southern North Sea, beach hydrology is characterized by the classical zonation with an upper saline plume (USP), a saltwater wedge, and a freshwater discharge tube in between. Sediment and pore water samples were taken along a cross-shore transect from the dunes to the low-water line reaching sediment depths down to 5 m below sediment surface. Spatial variations in pore water residence time, salinity, and organic matter availability lead to steep redox and nutrient gradients. Vertical and horizontal differences in the microbial community indicate the influence of these gradients and salinity on the community structure. shoreline. We propose that this nutrient efflux triggers growth of microphytobenthos on sediment surfaces of the discharge zone. A first comparison of nutrient discharge rates of the beach site with a nearby sandy backbarrier tidal flat margin indicates that the beach system might be of less importance in supplying recycled nutrients to nearshore waters than the backbarrier tidal flat area.

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Section: Pore Water Discharge Influences Phytobenthos and Nearshore Wcontrasting

confidence: 47%

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

et al. 2017

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“…In conjunction with high sediment accumulation rates, such events eventually have created similar subsurface zones of high remineralization activity. If the less likely but still conceivable second scenario of aquifer flow holds true, our results would similarly apply to other sites and many other coastal systems (Cooper Jr., 1959;Valiela et al, 1978;Johannes, 1980;Riedel et al, 2010). Akamatsua et al (2009) give an example of how subsurface advection beneath a mangrove forest generates a maximum in organic carbon at depth of 1 m.…”

Section: Discussionmentioning

confidence: 99%

Organic matter accumulation and degradation in subsurface coastal sediments: a model-based comparison of rapid sedimentation and aquifer transport

Holstein

Wirtz²

2010

Biogeosciences

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Abstract. The redox succession in shallow marine sediments generally exhibits a predictable pattern. Pore water profiles from a back barrier tidal flat in the German Wadden Sea depart from the expected redox zoning. Instead, a sulfate minimum zone associated with a sulfate-methane-sulfate double interface and a distinct ammonium peak at 1.5 m below sea floor (mbsf) is displayed. Such evidence for significant degradation of organic matter (OM) in subsurface layers is challenging our understanding of tidal flat biogeochemistry as little is known about processes that relocate reactive OM into layers far distant from the sediment-water interface. The objectives of our model study were to identify possible mechanisms for the rapid transport of organic matter to subsurface layers that cause the reversed redox succession and to constrain several important biogeochemical control parameters. We compared two scenarios for OM transfer: rapid sedimentation and burial of OM as well as lateral advection of suspended POM. Using a diagenetic model, uncertain process parameters, in particular those connected to OM degradation and (vertical or lateral) transport, are systematically calibrated using field data.We found that both scenarios, advection and sedimentation, had solutions consistent with the observed pore water profiles. For this specific site, however, advective transport of particulate material had to be rejected since the reconstructed boundary conditions were rather improbable. In the alternative deposition set-up, model simulations suggested the deposition of the source OM about 60 yrs before cores Correspondence to: J. M. Holstein (j.holstein@icbm.de) were taken. A mean sedimentation rate of approximately 2 cmyr −1 indicates substantial changes in near coast tidal flat morphology, since sea level rise is at a much lower pace. High sedimentation rates most probably reflect the progradation of flats within the study area. These or similar morphodynamic features also occur in other coastal areas so that inverted redox succession by horizontal or vertical transport may be more common than previously thought. Consequently, regional values for OM remineralization rates may be higher than predicted from surface biogeochemistry.

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“…In addition, flux 463 overestimation due to advection-driven fluxes is also not likely considering the relatively poor 464 sorting of our stations, in spite of their high sand content, meaning that the sediment was well-465 compacted (Leote and Epping 2015). However, the contribution from submarine groundwater 466 discharge is unknown for this area but has been reported for other regions of the Wadden Sea 467 (e.g., East Frisian Wadden Sea) as having an impact on some nutrient concentrations in the 468 water column (Riedel et al 2010;Moore et al 2011). Even though we have no data to assess its 469 contribution, we expect it to be low when compared to the East Frisian Wadden Sea, 470 considering the smaller intertidal area of the Marsdiep Basin and the low hydraulic gradient 471 generated by the land adjacent to the Marsdiep Basin (Moore et al 2011;Compton et al 2013).…”

Section: Sources Of P To the Western Wadden Sea 439mentioning

confidence: 99%

Nutrients in the Western Wadden Sea: Freshwater Input Versus Internal Recycling

Leote

Mulder

Philippart

et al. 2015

Estuaries and Coasts

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10At present, phosphorus (P) is seen as the main limiting nutrient for phytoplankton growth in the 11 western Wadden Sea. Six cruises were performed for water sampling at selected stations 12 covering a full tidal cycle for later determination of dissolved and particulate nutrient 13 concentrations. The major P sources were identified on a seasonal basis, by comparing the 14 contribution of freshwater discharge and sediment release, calculated in a previous study, to the 15 concentrations in the water column. A close relationship was found between the pelagic 16 concentrations of dissolved inorganic nutrients and chlorophyll a, with a concomitant decrease 17 in nutrients and increase in chlorophyll. This was observed in early spring and was followed by a 18 later increase in the nutrient concentrations in spring-summer. The low concentrations found for 19 the freshwater and seawater end-members for this period ruled out their importance as nutrient 20 sources, suggesting that this increase resulted mainly from internal recycling in the Wadden 21Sea. Even though P limitation was observed during most the year, a potential seasonal change 22 in the limiting nutrient, from P to silica, was observed. The comparison between P supply to the 23 Wadden Sea by freshwater discharge and sediment release showed a much higher contribution 24 of the latter, especially in April-November. To our knowledge, this is the first study clearly 25 presenting internal recycling as the main nutrient source to the western Wadden Sea in spring-26 autumn, instead of freshwater discharge or the North Sea. 27 28

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Tidal variations in groundwater storage and associated discharge from an intertidal coastal aquifer

Cited by 34 publications

References 49 publications

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

Organic matter accumulation and degradation in subsurface coastal sediments: a model-based comparison of rapid sedimentation and aquifer transport

Nutrients in the Western Wadden Sea: Freshwater Input Versus Internal Recycling

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