Metal Distribution in Clark Fork River Sediments

Abstract

Accurate sampling of pore waters and sediments in gravel river beds is problematic because cobbles preclude most coring techniques, while the angularity of sand grains destroys the membranes of standard pore water samplers. In the Clark Fork River, the recipient of over 100 years of mining activity, a modified single tube core-freezing device was used to profile bed sediment (approximately 65% cobbles and 35% gravel substrate), and a novel pore water sampler was developed to collect interstitial water. In the sediment, the <63 microm fraction comprised <4 wt % yet contained approximately an order of magnitude higher metal concentrations compared to the 63 microm-2 mm fraction (constituting approximately 20% of the mass). However, on a mass basis the sand fraction contained 60% of the metals, compared to 40% in the clay/silt fraction in the gravels, while in point bars the distribution was approximately 50:50. The metals occur predominantly in sulfides frequently armored with an oxide rim and other sparingly soluble phases that may explain the low pore water metal concentrations. These data demonstrate that consideration of multiple particle size cutoffs is necessary to accurately characterize fluvial bed sediment metal conditions and that the form of the metal is important in understanding metal solubility in the benthos.

Temporal bacterial diversity associated with metal-contaminated river sediments

“…Located at this confluence is the Anaconda Smelter where, for over a century, waste from smelting activity has been deposited either directly into the river or washed in as part of tailings run off following heavy rainfall. Flooding has distributed high concentrations of metal ions, including Ag, As, Cu, Cd, Pb and Zn across the flood plain (Moore et al 1991;Brick and Moore 1996), resulting in a perpetual metal-contamination from rain induced suspension of smelter tailings and leaching from the flood plain (Davis and Atkins 2001;Cain et al 2004). Deposition directly into the river has lead to a Northward gradient in metal concentrations both downstream and upstream of the focal point at the Smelter.…”

The effect of phytostabilization on Zn speciation in a dredged contaminated sediment using scanning electron microscopy, X-ray fluorescence, EXAFS spectroscopy, and principal components analysis

“…In France, due to the absence of regulations, dredged sediments are usually deposited on nearby soils, and as a result of anthropogenic activities including mining, industry and agriculture, often contain high amounts of metals. When the sediments are buried the mobility and toxicity of metals are low because the metals are generally present as sparingly soluble sulfides Davis and Atkins, 2001;Isaure et al, 2002;Osan et al, 2002;Maes et al, 2003;Motelica Heino et al, 2003;Neuhausler et al, 2003). In contrast, exposure of the sediments to the atmosphere can result in the oxidation of sulfides and release of metal contaminants to aquifers and streams (Kersten and Förstner, 1986;Zhuang et al, 1994;Cauwenberg and Maes, 1997;Carroll et al, 1998;Cauwenberg et al, 1998;O'Day et al, 2000;Fajtl et al, 2002;Isaure et al, 2002).…”

Urban Rivers as Pollutant Sinks and Sources: a Public Health Concern for Recreational River Users?

“…However, despite the fact that urban river sediment quality has been the subject of considerable research (supported by an extensive body of literature referring to the role of sediments in capturing, transporting and storing pollutants (e.g. Davis and Atkins 2001;Caille et al 2003;Filgueiras et al 2004), the widely documented presence of highly contaminated sediments in urban rivers has only relatively recently begun to be recognised as a possible public health concern or management issue within the urban river restoration debate (e.g. CROCUS 2007), but such aspects have yet to been translated into best practice guidance documents.…”