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The total amount of Hg discharged into Clear Lake over the past 15,000 years is estimated to be at least 2,400 metric tons." [57] [58] [59] The EPA-funded research by UC Davis found that total levels of mercury (TotHg) in the lake sediments has "not declined significantly a decade after" the remediation work in 1992 at Sulphur Bank Mine. [60]
The sediment samples taken from Clear Lake was found to have a high amount of mercury concentration, which was believed to have come about from opening of geothermal fissures during seismic activity, which released a mass of stored mercury rich elements into the lake. [10] A sample core study of the lakebed sediments determined the amount of ...
This allows researchers to assess key differences in the limnological conditions of the lake from which the core is taken. Lake-sediment cores, in particular, facilitate a more comprehensive analysis of an area because of the continual accumulation of sediment as well as other organic matter such as pollen and charcoal.
Clear Lake (Pomo: Lypoyomi) [2] [3] is a natural freshwater lake in Lake County in the U.S. state of California, north of Napa County and San Francisco. It is the largest natural freshwater lake wholly within the state, with 68 square miles (180 km 2 ) of surface area.
The Index to Marine & Lacustrine Geological Samples is a collaboration between multiple institutions and agencies that operate geological sample repositories. The purpose of the database is to help researchers locate sea floor and lakebed cores, grabs, dredges, and drill samples in their collections.
Specific techniques used to make inferences on ancient climate conditions are the use of lake sediment cores and speleothems. These utilize an analysis of sediment layers and rock growth formations respectively, amongst element-dating methods utilizing oxygen, carbon and uranium.
Rock core samples, the product of a diamond rig. A pied butcherbird perches nearby. A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The hole made for the ...
Lacustrine deposits have gained more attention recently due to containing valuable source rocks of oil, coal, and uranium. Lacustrine deposits generally provide productive mining conditions but can prove challenging when underground mines are attempted due to the poor shear strength of clays and silts as well as the amount of moisture often locked in the layers due to a low permeability ...