Effects of a small-scale, abandoned gold mine on the geochemistry of fine stream-bed and floodplain sediments in the Horsefly River watershed, British Columbia, Canada

Abstract

Mining is known to be a major source of metal contamination for fluvial systems worldwide. Monitoring and understanding the effects on downstream water and sediment quality is essential for its management and to mitigate against detrimental environmental impacts. This study aimed to examine the effects of the small-scale, abandoned, hydraulic Black Creek gold mine on the geochemical content of fine (<63 mm) stream bed and floodplain sediment in the Horsefly watershed (British Columbia, Canada), which is a part of the Quesnel River basin. Concentrations of As, Cd, Se and Zn were determined by aqua regia digestion and the modified BCR (European Community Bureau of Reference) sequential extraction procedure followed by inductively coupled plasma-optical emission spectroscopy or inductively coupled plasma-mass spectrometry. Age-depth models for the floodplain cores were constructed using excess Pb-210 and Cs-137 activity concentration profiles. The results show that the mine caused local As contamination of the Horsefly River floodplain sediment during the first years of operation, but at present the contamination is mainly contained in the Black Creek. Present-day and recent concentrations of Cd, Se and Zn in the Horsefly River are elevated and this is probably derived from other upstream mining activities. The spatial and temporal changes in heavymetal concentrations suggest a slight, but not particularly widespread, mining effect on the finesediment geochemistry in the Horsefly River system.

The challenges and opportunities of addressing particle size effects in sediment source fingerprinting: A review

“…Other ratios may indeed be effective, such as the Ca/Al ratio (Chen et al, 2014), along with particle size sensitive elements such as Ti (Bábek et al, 2015), or even simply clay content (Szava-Kovats, 2008). For example, studies reconstructing the evolution of metal enrichment ratios in sediment have also normalized elemental concentrations to Sc, Al, Si, Li or Th to minimize particle size impacts when examining contamination trends (Ayrault et al, 2010;Clark et al, 2014;Grosbois et al, 2012;Kersten and Smedes, 2002;Le Cloarec et al, 2011). Indeed, there are multiple approaches from the sediment provenance field (Armstrong-Altrin et al, 2015;Bábek et al, 2015;Owens et al, 2016;Singh et al, 2005) that present significant opportunities for enhancing the sediment source fingerprinting technique (e.g.…”

Spatial and trophic biomonitoring of trace metals in aquatic environments following the Mt. Polley Mine tailings spill

“…Water quality in the Quesnel River Catchment has historically been good. Localized industrial activity has taken place since approximately 1850, with numerous abandoned mines in the region (Clark et al, 2014). Forestry has occurred since the late 1900s, but predominantly in the western side of the catchment near the town of Quesnel (Smith and Owens, 2014).…”