نتایج جستجو برای: sedimentary phosphate
تعداد نتایج: 115052 فیلتر نتایج به سال:
Mathematical models of compaction in sedimentary basins typically assume a relationship between effective pressure p• and porosity •, which is of a non-linear type; that is, p• = p•(d). However, at depths greater than a kilometer, pressure solution becomes important and this relationship approaches a viscous one. We derive a mathematical model for viscous compaction in sedimentary basins and sh...
[1] A high-resolution stratigraphic image of a flume-generated deposit was scaled up to sedimentary basin dimensions where a natural log hydraulic conductivity (ln(K)) was assigned to each pixel on the basis of gray scale and conductivity end-members. The synthetic ln(K) map has mean, variance, and frequency distributions that are comparable to a natural alluvial fan deposit. A geostatistical a...
Groundwater and sediment samples (~1 m depth) at sites representative of different groundwater pathways were collected to determine the aqueous speciation of sulfur and the fractionation of sulfur isotopes in aqueous and solid phases. In addition, selected sediment samples at 5 depths (from oxic to anoxic layers) were collected to investigate the processes controlling sulfur biogeochemistry in ...
Current paradigms of reservoir ontogeny suggest that water-level fluctuations may increase sedimentary nutrient release, causing long-term eutrophication of water bodies formed by dryland flooding. Less is known of the changes in nutrient status following conversion of natural lakes into reservoirs. Here, we use historical hydrological and limnological data and paleolimnological records of sedi...
7.02.3 ORGANIC MATTER DECOMPOSITION IN SEDIMENTS 40 7.02.3.1 Electron Acceptors for Sedimentary Organic Matter Oxidation 43 7.02.3.2 The Stoichiometry of Oxic Sedimentary Organic Matter Decomposition 45 7.02.3.3 The Depth Distribution of Organic Matter Oxidation in the Sediment Column 48 7.02.3.4 The Response Time for Organic Matter Oxidation 51 7.02.3.5 The Burial of Organic Matter in Marine S...
The Tian Shan range offers a natural laboratory to study orogenic processes. Most of the previous studies focused on either the Paleozoic evolution of the range or its Cenozoic intracontinental evolution linked with the India-Asia collision. In this study, detailed field investigations on the relationship between sedimentary cover and basement constrain the Mesozoic evolution of the northern Ti...
Sediment quality guidelines and toxic equivalent factors have been used for assessment of the toxicity of sedimentary long-range atmospherically transported polycyclic aromatic hydrocarbons (PAHs) to the organisms living in high mountain European lakes. This method has provided indices that are consistent with experimental studies evaluating in situ sedimentary estrogenic activity or physiologi...
A first evaluation of the sedimentary changes, including accumulation of inorganic and organic carbon on the upper slope off Southeastern Brazil under different climatic conditions, based on the analysis of a sedimentary core, is here presented. Results indicate that sedimentation rate as well sedimentary characteristics, including the nature of the organic carbon deposited during the LGM (Last...
Abst rac t -Sedimentary denitrification acts to remove nitrogen from both the sediments and water column in continental shelf ecosystems, so that in enclosed shelf areas where water residence times are long (about a year in the Gulf of Maine), significant rates of sedimentary denitrification might lower inorganic nitrogen concentrations. We examined this using a basin-wide suite of hydrographic...
Introduction Evolutionists and creationists have different views on the origin of sedimentary rock strata. Evolutionists, who uphold the uniformitarian doctrine of 19th century geologists, suppose that most sedimentary strata were deposited slowly over millions of years as the Earth evolved gradually to its present configuration. Creationists who uphold the catastrophist doctrine of Scripture p...
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