The speciation and physico-chemical forms of metals in surface waters and sediments

Abstract

Surface waters can be contaminated in many ways, e.g., by solutions and suspended matter. Moreover, insoluble substances in colloidal form, in suspension or adsorbed on solid bodies can dissolve in response to changing physical and chemical conditions and become a secondary source of surface water pollution, thereby endangering wildlife. In addition, if we take into account varying rates of flow, contaminants can be transported over considerable distances. Hydrological processes, which determine factors, such as the rate of sedimentation, also influence the quality of surface waters; bottom sediments can contain large quantities of accumulated organic and inorganic compounds, including heavy metals. The physical and chemical properties of aquatic ecosystems are characterized by a number of interdependent parameters. Hence, factors such as temperature, oxygen content and pH of a water body can alter the solubility of the salts present in it, the forms of occurrence of particular species, as well as their bioavailability and toxicity. Thus it is necessary to determine the various species of metals present in the different compartments of the aquatic ecosystem.

Chironomids (Diptera) and their salivary gland chromosomes as indicators of trace-metal genotoxicity

“…In Cr-treated larvae, aberrations were found in 15% of the cells while in control larvae their frequency was 2% (Michailova et al 2001a Figure 4. ), In treated larvae, no differences in S values were observed among the three Cr concentrations possibly because Cr ions do not last so long in the dissolved states in which they can be bioaccumulated (Namieśnik & Rabajczyk 2010). Therefore no difference could be seen among the negative effects of the three tested Cr concentrations.…”

“…Although the concentration and the action of trace-metal ions are related, trace-metal ions in natural environments are potentially bound to different ligands, including precipitated compounds. Therefore their bioavailability and their positive or negative effect on living organisms can change from one station to another (Namieśnik & Rabajczyk 2010).…”

Metal partitioning and availability in estuarine surface sediments: Changes promoted by feeding activity of Scrobicularia plana and Liza ramada

“…Nonetheless, these methods are generally used to determine the bioavailability and toxicity of metals, by obtaining what is likely to be released in solution under different environmental conditions (Tessier et al, 1979). Methods may include more or less manipulative and time consuming consecutive steps, but generally sequential extractions with increasingly strong reagents under specific conditions are used to extract metals, and are then used as a proxy for metal associations with various geochemical, albeit operational, fractions (Namieśnik and Rabajczyk, 2010).…”

“…The increase in the concentration of exchangeable metals may be related to the increment in the acidity of the gut environment. The pH in the digestive diverticula of this species may be as low as 5.6 (Payne and Thorpe, 1993), which could be enough to destroy some carbonates and this way contribute to change the original partitioning of metals in the sediment, releasing metals that may become more easily extractable (Namieśnik and Rabajczyk, 2010). The simultaneous increase in the carbonates-bound fraction points to some other undetermined alteration in the sediment when passing through the gut of the clam, which may have led to the release of metals and subsequent remobilization into this fraction.…”

Variability in different antimony, arsenic and chromium species in waters and bottom sediments of three water reservoirs in Upper Silesia (Poland): a comparative study

“…Bottom sediments are an integral part of water ecosystems. They play a crucial role in the biochemical element cycles [6]. The quality of water and bottom sediments is affected by the direct human activity and effects of the climate changes.…”