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Are flood-driven turbidity currents hotspots for priming 1 effect in lakes ? 2 3
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bouffard, D. Perga, M-E |
| Copyright Year | 2016 |
| Abstract | 11 In deep stratified lakes, such as Lake Geneva, flood-driven turbidity currents are thought to 12 contribute to the replenishment of deep oxygen by significant transport of river waters 13 saturated with oxygen into the hypolimnion. The overarching aim of this study was to test 14 directly this long-standing hypothesis. It combines direct observational data collected during 15 an extreme flooding event that occurred in May 2015 with dark bioassays designed to 16 evaluate the consequences of riverborne inputs on the hypolimnetic respiration. The 17 exceptional precipitations of May 2015 caused floods with annual return time for the Rhône 18 River, the dominant tributary of Lake Geneva, and with 50-year return time for the Dranse 19 River, the second most important tributary. Sediment loaded river flows generated turbidity 20 currents plunging into the lake hypolimnion. The observed river intrusions contributed to the 21 redistribution of dissolved oxygen, with no net gain, when occurring in the lowermost 22 hypolimnetic layer. In the uppermost hypolimnion above the last deep mixing event, the 23 intrusions coincided with a net oxygen deficit. Consistent with field observations, dark 24 bioassays showed that 1% to 50% substitution of riverine organic matter to deep (<200 m) 25 hypolimnetic water did not affect microbial respiration, while addition of 1 to 10% of riverine 26 water to the uppermost hypolimnetic waters resulted in a respiration overyielding, i.e. excess 27 respiration of both riverborne and lacustrine organic matter. The results of our study conflict 28 the hypothesis that flood-driven turbidity currents necessarily increase hypolimnetic oxygen 29 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.biogeosciences-discuss.net/bg-2015-645/bg-2015-645-manuscript-version2.pdf |
| Alternate Webpage(s) | https://www.biogeosciences-discuss.net/bg-2015-645/bg-2015-645.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
