Sediment/Pore Water Characterization
Principal Investigator: Dr. Larry Twidwell
ltwidwell@mtech.edu
This project was an attempt to develop a conceptual environmental
model of the Berkeley Pit lake by collecting and characterizing
water and sediment samples from differing depths of the pit lake.
Deep water-upper layer sediment samples were collected from 600
to 700 feet below the pit lake surface and subsurface sediment/pore
water samples were collected from 717 feet below the surface. The
sediment samples and pore water were characterized and speciated
and an attempt was made to model the system with hopes of understanding
reactions which control sediment formation. Several elements were
found at lower concentrations in pore water than in the deep water
three feet above the sediments. However, ferrous iron concentrations
were far higher in pore water than in the deep water. It is feasible
that potassium jarosite and/or schwertzmannite reacts with organic
carbon to form ferrous species and controls the ferrous concentration
in the pore water. The sediment samples were composed of detrital
(major components quartz, biotite, and muscovite) and precipitated
compounds (major components jarosite and gypsum). The higher concentrations
of the precipitated compounds near the core surface suggest that
the precipitated solids form in the water column and settle. The
detrital compounds are the common wall rock elements of the Berkeley
Pit.
Activity IV, Project 9
Final
Report
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