Mammals as biological monitors of environmental metal levels

Wild mammals can be valuable biological monitors of environmental gradients of metal concentrations. The choice of a particular species for a biological monitor must be based upon the circumstances of each study including species availability, the metals to be examined, area, and the study objectives and priorities. Ideally, a biological monitoring study should be designed to obtain and make use of the optimum amount of available information by complementing existing environmental studies, or through the simultaneous collection of other environmental data.     

Levels of lead, cadmium and other elements in mink and otter from Ontario, Canada

Concentrations of Pb, Cd, Cu, Ni, Fe, Zn, Mn, Ca, P, Mg and S were measured in tissues of mink (Mustela vision) and river otter (Lutra canadensis) from five areas of Ontario, Canada. Bone Pb levels in both species were lowest in animals from the collection site most remote from industrial activity and atmospheric deposition of pollutants. Mean liver and kidney Cd levels were also different between collection sites and may reflect natural and/or anthropogenic sources. Copper levels in liver, but not kidney, were elevated in mink and otter from the heavily Cu-contaminated Sudbury region. However, tissue levels did not reflect environmental loading of other metals, such as Fe, Ni and Zn, in the Sudbury area. This may be a function of effective homeostatic regulation in mammals, or low potential for biomagnification of these elements.     

Willow ptarmigan (Lagopus lagopus) as a biomonitor of environmental metal levels in Norway

The purpose of this study was to examine the potential of a native wild bird, Lagopus lagopus, as a monitor of environmental metal levels, in particular with respect to the influence of atmospheric deposition of metals from long-range transport. Specimens of willow ptarmigan were collected from ten different locations in Norway. The concentrations of cadmium, zinc and copper were determined in kidneys of birds from all sites. Mean cadmium levels in adult ptarmigan kidney ranged from 6.6 to 48.5 microg g(-1) (wet weight), with individual concentrations up to 71.0 microg g(-1). These are among the highest cadmium levels reported in wild birds. The kidneys of adult birds contained 3-10 times higher cadmium levels than kidneys from juvenile birds in the same collection area, and most of the high cadmium levels probably reflect natural exposure, rather than atmospheric pollution. Concentrations of elements in kidney tissues were highly correlated with each other.     

The effect of acidification on the accumulation and toxicity of metals to freshwater invertebrates

This paper reviews the literature to determine if lowered water pH (a) affects metal bioaccumulation in freshwater invertebrates, (b) enhances the toxicity of a given metal, and (c) increases waterborne metal concentrations to levels toxic to invertebrates. The elements considered are mercury, lead, cadmium and aluminum. The available evidence suggests that of these elements only mercury is biomagnified in aquatic foodchains. The bioaccumulation of all these elements is influenced by water pH, but data concerning invertebrates is meagre for mercury and lead. The effect of pH on mercury and lead toxicity to invertebrates is unclear and may be largely species specific. Cadmium toxicity is reduced by lower pH, while aluminum toxicity to invertebrates is markedly higher due to changes in aluminum speciation at low pH.     

A simple and sensitive bioassay for the detection of toxic materials using a unicellular green alga

A simple assay for phytotoxicity, using small scale cultures of Chlorella vulgaris, is described. Growth after 3 days' incubation in 0.5 cm(3) medium is assessed by DMSO-acetone extraction and chlorophyll determination. The method is sensitive enough to detect phytotoxicity in small samples of material and this is illustrated by the inhibitory effects of microgram additions of copper, cadmium and zinc.