دورية أكاديمية
Evidence for double diffusion in temperate meromictic lakes
| العنوان: | Evidence for double diffusion in temperate meromictic lakes |
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| المؤلفون: | C. von Rohden, B. Boehrer, J. Ilmberger |
| المصدر: | Hydrology and Earth System Sciences, Vol 14, Iss 4, Pp 667-674 (2010) |
| بيانات النشر: | Copernicus Publications, 2010. |
| سنة النشر: | 2010 |
| المجموعة: | LCC:Technology LCC:Environmental technology. Sanitary engineering LCC:Geography. Anthropology. Recreation LCC:Environmental sciences |
| مصطلحات موضوعية: | Technology, Environmental technology. Sanitary engineering, TD1-1066, Geography. Anthropology. Recreation, Environmental sciences, GE1-350 |
| الوصف: | We present CTD-measurements from two shallow meromictic mining lakes. The lakes, which differ in size and depth, show completely different seasonal mixing patterns in their mixolimnia. However, the measurements document the occurrence of similar seasonal convective mixing in discrete layers within their monimolimnia. This mixing is induced by double diffusion and can be identified by the characteristic step-like structure of the temperature and electrical conductivity profiles. The steps develop in the upper part of the monimolimnion, when in autumn cooling mixolimnion temperatures have dropped below temperatures of the underlying monimolimnion. The density gradient across the chemocline due to solutes overcompensates the destabilizing temperature gradient, and moreover, keeps the vertical transport close to molecular level. In conclusion, preconditions for double diffusive effects are given on a seasonal basis. At in general high local stabilities N2 in the monimolimnia of 10−4–10−2s−2, the stability ratio Rρ was in the range of 1–20. This quantitatively indicates that double diffusion can become visible. Between 1 and 6 sequent steps, with sizes between 1 dm and 1 m, were visually identified in the CTD-profiles. In the lower monimolimnion of the deeper lake, the steps systematically emerge at a time delay of more than half a year, which matches with the progression of the mixolimnetic temperature changes into the monimolimnion. In none of the lakes, the chemocline interface is degraded by these processes. However, double diffusive convection is essential for the redistribution of solutes in the inner parts of the monimolimnion at longer time scales, which is crucial for the assessment of the ecologic development of such lakes. |
| نوع الوثيقة: | article |
| وصف الملف: | electronic resource |
| اللغة: | English |
| تدمد: | 1027-5606 1607-7938 |
| Relation: | http://www.hydrol-earth-syst-sci.net/14/667/2010/hess-14-667-2010.pdf; https://doaj.org/toc/1027-5606; https://doaj.org/toc/1607-7938 |
| DOI: | 10.5194/hess-14-667-2010 |
| URL الوصول: | https://doaj.org/article/9ba573580ae4479ebd11f1e7f310d94f |
| رقم الأكسشن: | edsdoj.9ba573580ae4479ebd11f1e7f310d94f |
| قاعدة البيانات: | Directory of Open Access Journals |
Full Text Finder | تدمد: | 10275606 16077938 |
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| DOI: | 10.5194/hess-14-667-2010 |