Concentrations of Metals in Water, Sediment, Biofilm, Benthic Macroinvertebrates, and Fish in the Boulder River Watershed, Montana, and the Role of Colloids in Metal Uptake

Abstract

To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S. EPA acute and chronic criteria for protection of aquatic life. Concentrations of As, Cd, Cu, Pb, and Zn in sediment were sufficient in the tributaries to cause invertebrate toxicity. The concentrations of As, Cu, Cd, Pb, and Zn in invertebrates from lower Cataract Creek (63, 339, 59, 34, and 2,410 microg/g dry wt, respectively) were greater than the concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648 microg/g, respectively), that were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of those invertebrates. Colloids and biofilm seem to play a critical role in the pathway of metals into the food chain and concentrations of As, Cu, Pb, and Zn in these two components are significantly correlated. We suggest that transfer of metals associated with Fe colloids to biological components of biofilm is an important pathway where metals associated with abiotic components are first available to biotic components. The significant correlations suggest that Cd, Cu, and Zn may move independently to biota (biofilm, invertebrates, or fish tissues) from water and sediment. The possibility exists that Cd, Cu, and Zn concentrations increase in fish tissues as a result of direct contact with water and sediment and indirect exposure through the food chain. However, uptake through the food chain to fish may be more important for As. Although As concentrations in colloids and biofilm were significantly correlated with As water concentrations, As concentrations in fish tissues were not correlated with water. The pathway for Pb into biological components seems to begin with sediment because concentrations of Pb in water were not significantly correlated with any other component and because concentrations of Pb in the water were often below detection limits.

Liver, gills, and skin histopathology and heavy metal content of the Danube sterlet (Acipenser ruthenus Linnaeus, 1758)

“…Fish are exposed to heavy metals both directly from water and sediment and indirectly through the food chain, especially Cu, Cd, and Zn [19]. Heavy metal bioaccumulation affects the structure and function of fish vital organs.…”

Seasonal variations of metal concentrations in periphyton and taxonomic composition of the algal community at a Yenisei River littoral site

“…In contrast, previous studies have reported significant correlations between Cu and Zn concentrations in water and biofilms in polluted stream ecosystems of Montana, where concentrations of the heavy metals were significantly higher than those in the , right set of canonical variables) and taxonomic composition of algal community (% of a given group in total biomass of epilithic microalgae, right set of canonical variables). See Table 2 Yenisei River [4]. Using pooled data from unpolluted and polluted sites, a significant correlation was found between Cu and Zn contents in water and in periphyton in the Birs River, but there were no such correlations for the Thur River with only background levels of metals [3].…”

“…However, the content of a metal in water, especially in rivers with a high flow velocity, may reflect only short-term events and does not necessarily mean that biota and sediments are polluted with the metal [1,2]. Thus, periphyton (benthic algal assemblages, also referred to as biofilms) is often used to monitor chronic metal pollution in rivers, since periphytic organisms can accumulate metals from ambient water and sediments in their biomass [3][4][5].…”

A long-term survey of heavy metals and specific organic compounds in biofilms, sediments, and surface water in a heavily affected river in the Czech Republic

“…Bottom sediments have similar properties as biofilms regarding the cycling and fate of pollutants in the aquatic environment: they have the ability to bind different substances, can act as a feeding source for macroinvertebrates or fish, can act as secondary sources of pollution during floods as well as low-water periods, and are a more or less temporal sink for pollutants (e.g., Baudo et al 1990;Lotufo 1998;Gewurtz et al 2000;Baborowski et al 2004;Stachel et al 2004;Umlauf et al 2005). Pollutants accumulated in both biofilms and sediments can be considered bioavailable (e.g., Landrum and Robbins 1990;Farag et al 2007).…”