Global ETD Search
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Showing 1 to 14 of 14 for “"polymictic"”.
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Dynamics of internal nutrient loading in a eutrophic, polymictic lake (Lake Rotorua, New Zealand)
Lake Rotorua is a large (80 krn2), polymictic, eutrophic, shalJow (mean depth 10.8 m) lake in central North Island, New Zealand. Blooms of cyanobacteria and occasional anoxia of bottom waters are characteristic of the water quality in the lake during summer months (Dec-Mar.). This study examines …
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Provenance and tectonic significance of the Lower Paleozoic Douglas Conglomerate, northern Churchill Mountains, Antarctica
… in the Churchill Mountains of Antarctica is a polymictic, unconformity-bounded unit whose age is poorly constrained between Late Cambrian and Devonian. Its source areas were local, including outcrops of Cambrian Shackleton Limestone, the craton of Greater Antarctica, and perhaps, terranes that …
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Reservoir Characterization of the Clarksville Formation in Red River County, Texas
… Conglomerate 1 is a clast-supported polymictic conglomerate with granule- to cobble-sized clasts (2–95 mm) and calcite-dominated cementation, averaging 8.3% porosity and 18.0 mD permeability. Conglomerate 2 is a matrix-supported polymictic conglomerate with poorly sorted granule- to …
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Analyzing lakes in the time frequency domain
… serve as an indicator for mixing in a shallow, polymictic lake. The final study uses wavelet coherence as a diagnostic tool for limnology on a multivariate high-frequency data set recorded between the onset of ice cover and a cyanobacteria summer bloom in the year 2009 in a polymictic lake. …
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Hydroclimate variability in Central America during the Holocene inferred from lacustrine sediments in Lake Izabal, eastern Guatemala
… before present (cal yr BP), Lake Izabal became a polymictic lake, and precipitation in the region stabilized, remaining high until ~1,200 cal yr BP, with an abrupt decrease in precipitation thereafter. Our findings indicate that Lake Izabal is highly sensitive to changes in Caribbean sea level and …
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Stratigraphy and sedimentology, Cambrian Shady Dolomite, Virginia
… bioherms, limeclast grain-stone, monomictic and polymictic carbonate breccia and black laminated limestone and shale. Algal bioherms, limeclast grain-stones and carbonate breccias of southeastern belts suggest seaward, outer platform environments; black laminated limestone and shale units …
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A Field and Modeling Assessment of Methyl Mercury Accumulation in an Engineered Retention Pond
… (Hg) accumulation. However, small, shallow polymictic lakes can experience short-term stratification and mixing events that are largely unstudied in their abilities to affect Hg cycling and MeHg accumulation. Short-term stratification events and changing lake characteristics impact lake …
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REVISED STRATIGRAPHIC AND TECTONIC EVOLUTION OF THE SAN FRANCISCO RIDGE; AN EMERGING PUSH-UP STRUCTURE IN THE NORTHEAST DOMINICAN REPUBLIC
… mudstones with middle Miocene age and polymictic conglomerates with Pliocene-Pleistocene age that unconformably overlie the older and fined grained sedimentary units. The conglomerates are located in elevated areas of the San Francisco Ridge, especially in the northeast and northwest …
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Sedimentological constraints on Precambrian crustal evolution in northern New Mexico
… sequence, the Marquenas Quartzite, consists of polymictic meta conglomerates and texturally-immature meta sandstones deposited in a braided-alluvial environment. These terrigenous sediments were supplied from the south and pebble compositions indicate derivation from the underlying volcanogenic …
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Climate impact on phytoplankton blooms in shallow lakes
… chemical and biological variables of a shallow, polymictic lake in north-eastern Germany (Müggelsee), which was subject to a simultaneous change in climate and trophic state during the past three decades. Data analysis included constructing a dynamic simulation model, implementing a genetic …
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Characterization of novel pathways in the phosphorus cycle of lakes
… pathway supplying PO43- to plankton in shallow polymictic lakes. This represents the first study to identify this P pathway in lakes. The turnover time of the PO43- pool increased under UVR irradiance (i.e., uptake of P by plankton decreased), while the regeneration rate of dissolved P and …
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Modelling temporal dynamics of discharge and nutrient loading from a mixed land use catchment, and interactions with a eutrophic, temperate lake under climate change
… and longer periods of thermal stratification in polymictic lakes such as Rotorua, which would likely result in greater depletion of dissolved oxygen and possible anoxia of hypolimnetic waters. This overarching effect of climate change is likely to be through a physical response of the lake in the …
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Sediment-Pore Water Chemistry of Taupo Volcanic Zone Lakes and the Effect Trophic State has on Exchange with the Water Column
… (0.2 to 620 km2), mixing regime (monomictic and polymictic), and trophic status (oligotrophic to supertrophic). The purpose of this study is to develop an understanding of the sediment-pore water interactions over a range of trophic conditions and how the biogeochemical cycles influence the lake …