نتایج جستجو برای: carbonate sediment
تعداد نتایج: 61087 فیلتر نتایج به سال:
On continental margins, oxidation of methane-rich fluids from the sediment often leads to formation of authigenic carbonate pavements on the seafloor. The biogeochemical processes involved during this carbonate precipitation are increasingly understood, but little is known about the duration or mode of carbonate crust formation. Here, we report uranium and thorium concentrations and isotope com...
Background and Objective: Corrosion and precipitation are important indicators of water quality assessment. The aim of this study was to analyze water stability water in Semnan distribution networks. Materials and Methods: To achieve the purpose, samples were taken from 5 points (3 points of storage tanks and 2 distribution network points) and analyzed for physical-chemical analysis. The conce...
In situ microbial reduction of soluble U(VI) to sparingly soluble U(IV) was evaluated at the site of the former S-3 Ponds in Area 3 of the U.S. Department of Energy Natural and Accelerated Bioremediation Research Field Research Center, Oak Ridge, TN. After establishing conditions favorable for bioremediation (Wu, et al. Environ. Sci. Technol. 2006, 40, 3988-3995), intermittent additions of etha...
[1] Dissolution of fossil fuel CO2 in seawater results in decreasing carbonate ion concentration and lowering of seawater pH with likely negative impacts for many marine organisms. We project detectable changes in carbonate dissolution and evaluate their potential to mitigate atmospheric CO2 and ocean acidification with a global biogeochemistry model HAMOCC forced by different CO2 emission scen...
Formation and Distribution of Beachrock Beachrock is defined by Scoffin and Stoddart (1987, 401) as "the consolidated deposit that results from lithification by calcium carbonate of sediment in the intertidal and spray zones of mainly tropical coasts." Beachrock units form under a thin cover of sediment and generally overlie unconsolidated sand, although they may rest on any type of foundation....
Introduction The impacts of watershed deforestation on lacustrine environments can dramatically affect the productivity of the littoral zone and strongly influence sedimentation rates. Many watersheds flowing into Lake Tanganyika (3°18’8°47’S, 29°05’ 31°18’E) from northern Kigoma region, Tanzania are currently experiencing the effects of deforestation to accommodate high human population densit...
[1] An additional Heinrich ice-rafting event is identified between Heinrich events 5 and 6 in eight cores from the Labrador Sea and the northwest Atlantic Ocean. It is characterized by sediment rich in detrital carbonate (40% CaCO3) with high concentration of floating dropstones, high coarse-fraction (% > 150 mm) content, and has a sharp contact with the underlying but grades into the overlying...
Twelve cores from the protected reef-Xat of Molokai revealed that carbonate sediment accumulation, ranging from 3 mm year to less than 1 mm year, ended on average 2,500 years ago. Modern sediment is present as a mobile surface veneer but is not trapped within the reef framework. This Wnding is consistent with the arrest of deposition at the end of the mid-Holocene highstand, known locally as th...
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