The nature of heavy metal contamination in organic lake sediments near the Buchans massive sulphide base metal mines, Central Newfoundland

• Main Author: Haring, Peter G.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2002
• Subjects: Indian; Organic Lake; Newfoundland
• Online Access: https://research.library.mun.ca/6550/; https://research.library.mun.ca/6550/1/PeterGHaring.pdf; https://research.library.mun.ca/6550/3/PeterGHaring.pdf

The Buchans mine closed in 1984 after 57 years of operation. Several orebodies, including Luck Strike, Oriental, Old Buchans, Rothermere and MacLean, produced 16,196,876 tonnes of ore with an average grade of 14.51% Zn, 7.56% Pb, 1.33% Cu, 126 grams/tonne Ag and 1.37 grams/tonne Au. Copper (chalcopyrite), lead (galena) and Zinc (sphalerite) concentrates were shipped from the port of Botwood The baritic, polymetallic orebodies were Canada’s highest grade volcanogenic massive sulphide deposits. -- To determine the impact that mining activities in and around the Buchans community had on the watersheds of the area, six lake sediment cores were collected. Four of these were taken in Red Indian Lake and two were taken in Buchans Lake, also named Sandy Lake. All cores were extracted with a K.B. Gravity lake Sediment Corer and due to the water depth in Red Indian Lake, a Deep Water operating Kit had to be used as an attachment. -- To determine the availability of the heavy metals to the environment that might be caused by subtle changes of pH or Eh, this study utilized a four step sequential extraction procedure. The four discrete operationally defined fractions that were measured were as follows: (I) Exhangeable/Carbonate, (II) Fe/Mn Oxide, (III) Organic/Sulphide, and (IV) Silicate. -- Each core was sectioned into two centimeter intervals and total concentrations were measured on 29 elements, including Cu, Pb and Zn, on all dry sediment intervals by inductively coupled plasma-optical emission spectroscopy (ICP-OES) using HCl/HF/HClO₄ digestion. Furthermore, select base metals (Cu, Pb and Zn) were analysed on the ‘wet’ and ‘dry’ samples extracted from lake sediment core RIL2B using the four step sequential extraction procedure to determine the degree to which the various metals reported to the different phase fractions. -- The total element analysis on all cores showed significant enhancement in base metals in the upper sediment intervals, particularly in Red Indian Lake, where the concentrations of copper, lead and ...