Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1002/2017JC013008 |
| Title (Primary) | Coupling end-member mixing analysis and isotope mass balancing (222-Rn) for differentiation of fresh and re-circulated submarine groundwater discharge into Knysna Estuary, South Africa |
| Author | Petermann, E.; Knöller, K.; Rocha, C.; Scholten, J.; Stollberg, R.; Weiß, H.
; Schubert, M. |
| Source Titel | Journal of Geophysical Research-Oceans |
| Year | 2018 |
| Department | ENVINF; CATHYD |
| Volume | 123 |
| Page From | 952 |
| Page To | 970 |
| Language | englisch |
| Supplements | Supplement 1 Supplement 2 Supplement 3 Supplement 4 Supplement 5 Supplement 6 Supplement 7 Supplement 8 Supplement 9 Supplement 10 Supplement 11 Supplement 12 Supplement 13 Supplement 14 Supplement 15 Supplement 16 Supplement 17 Supplement 18 Supplement 19 Supplement 20 Supplement 21 Supplement 22 Supplement 23 Supplement 24 |
| Keywords | submarine groundwater discharge; end-member mixing analysis; radon; isotopes; Knysna; water balance |
| UFZ wide themes | RU5; |
| Abstract | Quantification of submarine groundwater discharge (SGD) is essential for evaluating the vulnerability of coastal water bodies to groundwater pollution and for understanding water body material cycles response due to potential discharge of nutrients, organic compounds or heavy-metals. Here, we present an environmental tracer based methodology for quantifying SGD into Knysna Estuary, South Africa. Both components of SGD, (1) fresh, terrestrial (FSGD) and (2) saline, re-circulated (RSGD) were differentiated. We conducted an end-member mixing analysis for radon (222Rn) and salinity time series of estuary water over two tidal cycles to determine fractions of seawater, riverwater, FSGD and RSGD. The mixing analysis was treated as a constrained optimization problem for finding the end-member mixing ratio that is producing the best fit to observations at every time-step. Results revealed highest FSGD and RSGD fractions in the estuary during peak low tide. Over a 24 h time-series the portions of FSGD and RSGD in the estuary water were 0.2% and 0.8% near the estuary mouth and the FSGD/RSGD ratio was 1:3.3. We determined a median FSGD of 41,000 m³ d−1 (1.4 m³ d−1 per m shoreline) and a median RSGD of 135,000 m³ d−1 (4.5 m³ d−1 per m shoreline) which suggests that SGD exceeds river discharge by a factor of 1.0 to 2.1. By comparison to other sources, this implies that SGD is responsible for 28 to 73% of total DIN fluxes into Knysna Estuary. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=19842 |
| Petermann, E., Knöller, K., Rocha, C., Scholten, J., Stollberg, R., Weiß, H., Schubert, M. (2018): Coupling end-member mixing analysis and isotope mass balancing (222-Rn) for differentiation of fresh and re-circulated submarine groundwater discharge into Knysna Estuary, South Africa J. Geophys. Res. 123 , 952 - 970 10.1002/2017JC013008 |
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