Environmental assessment of abandoned mine tailings in Adak, Vasterbotten district (northern Sweden)

• Sulfide-rich mine tailings in Adak that are exposed to weathering cause acid mine drainage characterized by low PH (2-4) and high SO4 (UP to 800 mg L-1). Surface water, sediment and soil samples collected in this study contain higher concentrations of As, Cu, Fe and Zn, compared to the target and/or intervention limits set by international regulatory agencies. In particular, high As concentrations in water (up to 2900 mu g L- 1) and sediment (up to 900 mg kg(-1)) are of concern. There is large variability in trace element concentrations, implying that both physical (grain size) and chemical factors (pH, secondary phases as sulfides, Al-oxides or clay minerals) play an important role in their distribution. The low PH keeps the trace elements dissolved, and they are transported farther downstream. Trace element partition coefficients are low (log K-d = 0.3-4.3), and saturation indices calculated with PHREEQC are < 0 for common oxide and sulfidic minerals. The sediment and soil samples indicate an enhanced pollution index (up to 17), and high enrichment factors for trace elements (As up to 38,300; Zn up to 800). Finally, leaves collected from different plant types indicate bioaccumulation of several elements (As, Al, Cu, Fe and Zn). However, some of the plants growing in this area (e.g., Salix, Equisetum) are generally resistant to metal toxicity, and hence, liming and phytoremediation could be considered as potential on-site remediation methods.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Kemiska processer (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Chemical Process Engineering (hsv//eng)

Nyckelord

trace-elements

mineralized spodosol

metals

sulfur

water

sediments

cu

geochemistry

reduction

arsenate

Publikations- och innehållstyp

ref (ämneskategori)

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