Christoph von Rohden

TL;DR: In this paper, the authors employed tracers (3H-3He, noble gases, stable isotopes 18O and 2H) to study groundwater recharge and residence times in the strongly exploited North China Plain aquifer system in the area of Shijiazhuang, the capital of the Hebei province.

TL;DR: In this paper, the authors used the noble gas paleothermometer (NGT) to determine absolute paleotemperature records from radiocarbon dated groundwater, which can directly relate to stable isotope ratios from the same groundwater archive.

Abstract: Lakes turn meromictic, when mixing and deep recirculation are insufficient to homogenize the water body and remove chemical gradients. A deepwater layer “the monimolimnion ” is excluded from the deep recirculation and hence develops a pronounced different chemical milieu. It persists through all seasons due to its high density. A limited number of processes are known to accomplish such a density increase of the deep water to create meromixis , such as salty inflows and partial deepwater renewal . However, also geochemical processes, such as decomposition of organic material, iron oxidation, and redissolution and calcite precipitation, can be responsible for meromixis. Other than the overlying water layer “the mixolimnion, ” the monimolimnion does not get into direct contact with the atmosphere and hence is not directly supplied with oxygen. Other substances can be enriched by precipitation and flocculation from the mixolimnion until the solubility product is reached or gas pressure grows beyond absolute pressure. As a consequence, the composition of solutes deviates clearly from usual water composition, and quantitative approaches for density must implement appropriate numerical approaches. The permanent density stratification limits the vertical transport of water and solutes. In several lakes, double-diffusive convection has been reported to significantly enhance the vertical solute transport.

TL;DR: A tracer experiment with sulfurhexafluoride (SF6) in the monimolimnion of the meromictic mining lake Merseburg-Ost 1b was described in this article.

TL;DR: In this article, the authors present observations of a circulation pattern that has not been documented in the limnological literature before, where surface cooling drives a vertical circulation of the upper water layer (mixolimnion), the deeper water layer is not included because of its higher salt concentration.