Integrated environmental assessment of freshwater sediments: a chemical and ecotoxicological approach at the Alqueva reservoir

Abstract

In order to study the pollution of an aquatic ecosystem, it is necessary to analyze not only the levels of chemical pollutants in water, but also those accumulated in the sediment matrix, as well as to assess its ecotoxicological status. The Alqueva reservoir, the largest artificial lake in Europe, was chosen as case study as it constitutes the most important water supply source in southern Portugal. It is located in the Guadiana River Basin, in a semi-arid region with high levels of water scarcity and where agriculture is one of the main activities. The evaluation of sediments comprised: (1) physical and chemical analysis (grain size, pH, organic matter, nitrogen, phosphorus); (2) potentially toxic trace elements (Cu, As, Pb, Cr, Cd, Zn and Ni); and (3) ecotoxicological evaluation with Vibrio fischeri, Thamnocephalus platyurus, Daphnia magna, and Heterocypris incongruens. Total trace element concentrations indicated that As, Cd, and Pb surpassed the Canadian levels for the protection of aquatic life, in most of Alqueva's sites. The results of the toxicity assessment showed that some locations induced acute and chronic toxicity in the species used. Further, the H. incongruens was the most sensitive species as far as the contamination found in the sediment is concerned, followed by the bacteria V. fischeri. This integrative approach, together with the water column quality assessment, allowed a comprehensive evaluation of the environmental quality of this strongly modified water body and will allow the implementation of remediation strategies to obtain a good ecological potential as proposed in the Water Framework Directive.

Assessment of trace element pollution and its environmental risk to freshwater sediments influenced by anthropogenic contributions: The case study of Alqueva reservoir (Guadiana Basin)

“…Nevertheless, the pollution indicators point to this element as the most associated to anthropogenic contamination in the reservoir, and with concentrations much higher than the background regional value for the Guadiana Basin, being considered, in the present study and in all others developed in the Guadiana Basin, an important stressor for the ecosystem (Delgado et al, 2010Mil-Homens et al, 2014). Further, the ecotoxicity assays developed in the sediments of the reservoir, showed a significant correlation between the acute toxic effects observed and the presence of Cd, mainly for samples of Lucefécit and Álamos (Palma et al, 2014b). In general, the Alqueva reservoir would be ranked as an area with moderate toxicological risk for most of the trace elements, except for Cd.…”

“…Presently, the mining activity is limited to a small number of active mines (Neves Corvo and Aljustrel), but the environmental impact of the AMD still exists, due to the some abandoned mines which need to be rehabilitated (Matos e Martins, 2006), and several authors have reported AMD as an important anthropogenic source of trace elements in the Guadiana Basin (Fernández-Caliani et al, 2009;Guillén et al, 2011;Nieto et al, 2007). On the other hand, the intensive agricultural activity and the discharge of untreated or inefficiently treated domestic wastewater may constitute other sources of metals in this water body (Palma et al, 2014a(Palma et al, , 2010Silva et al 2011). Previous studies developed at the Alqueva reservoir have characterized the textural structure and organic content of the sediments, the levels of nutrients, the total contents of As, Cd, Cr, Cu, Ni, Pb, Zn, Fe and Mn; and some ecotoxicological effects (Palma et al, 2014a(Palma et al, , 2014b. Currently, it is important to understand, which amounts of trace elements are arising from anthropogenic sources, as well as their mobility and bioavailability in the sediments, and try to correlate these results with the toxicological risk for the reservoir and for the populations.…”

Effects-based spatial assessment of contaminated estuarine sediments from Bear Creek, Baltimore Harbor, MD, USA

“…As such, sediments in regions with prolonged histories of industrial activity are often laden to significant depths with complex mixtures of legacy contaminants, including trace metals and persistent organic pollutants (POPs), which can be disturbed and reintroduced to surface waters, allowing for exposure, uptake, and accumulation in resident biota (Garcia et al 2011; Palma et al 2014). To address the complexity in assessing contaminated sediment risks, researchers have relied on integrated “weight-of-evidence” approaches that pair chemical analysis with laboratory and field-based biological effects data (Burton 2002).…”

History and sensitivity comparison of two standard whole-sediment toxicity tests with crustaceans: the amphipodHyalella aztecaand the ostracodHeterocypris incongruensmicrobiotest

“…Since the commercial availability of the Ostracodtoxkit, a substantial number of studies were carried out with the standard ostracod toxicity test in different laboratories of several countries, on a variety of sediments. Findings of several of these studies have been published in the scientific literature (Latif and Licek, 2004;Dirven-van Breemen et al, 2006;Drobniewska et al, 2007;Mankiewicz-Boczek et al, 2008;Watanabe et al, 2008;Wang et al, 2009;García-Lorenzo et al, 2009;Coccia et al, 2009;Silva et al, 2011;Kudlak et al, 2011;Nalecz-Jawecki et al, 2011;Steliga, 2011;Sheahan and Fisher, 2012;Huerta Buitrago et al, 2013;Watanabe et al, 2013;Ruiz et al, 2013;Khanal et al, 2014;Sevilla et al, 2014;Palma et al, 2014). Titles, abstracts, and posters of other studies presented at international symposia on ecotoxicology can be found on the website www.microbiotests.be (Nalecz-Jawecki et al, 2009;Gonçalves et al, 2012).…”