Extraction and Concentration of Freshwater - and Seawater - Derived Dissolved Organic Matter for Use in Aquatic Toxicology Studies

Dissolved organic matter (DOM) is defined as the organic matter that passes through a 0.45 µm-mesh filter. Recent studies have shown the DOM importance in mitigating trace metals and organic pollutants toxicity. In general, studies with DOM are performed using commercial organic matter. However, it has been demonstrated that this organic matter has little structural similarity with the aquatic humic acids. Furthermore, a natural DOM is composed by different fractions, which can exhibit different complexing properties with metals. Thus, it is important to evaluate the effect of different sources of natural DOM on pollutants toxicity. To use natural DOM in aquatic toxicity tests, it is necessary to extract and provide suitable storage for samples in the laboratory. The ideal process for DOM isolation from natural waters should be capable of rapidly and effectively extracting large quantities of DOM from water without fractionation, chemical alteration and/or other losses. Therefore, in the present paper we describe the methodological approaches currently in use in our laboratory for extraction and concentration of both freshwater and seawater-derived DOM using reverse osmosis (freshwater) and solid phase extraction (seawater).