Mercury pollution in Ria de Aveiro (Portugal): a review of the system assessment

Abstract

The Ria de Aveiro (Portugal) is a coast al lagoon adjacent to the Atlantic Ocean and it has an inner bay (Laranjo bay) that received a highly contaminated effluent discharged by a mercury cell chlor-alkali plant from the 1950s until 1994. The aim of this study is to review in a holistic way several research studies that have been carried out in the Ria de Aveiro, in order to evaluate the remobilization of the mercury accumulated within the system and the recovery of the lagoon. The spatial distribution of the total mercury in the surrounding terrestrial environment has also been considered. Results indicate that the main mercury contamination problems in the Ria de Aveiro are confined to the Laranjo bay. Mercury export to the coastal waters and its impact on the nearshore compartments (water column, sediment and biota) are low. No direct effects of the mercury from nearby industrial activities were detected in Aveiro's urban soils, although historical mercury contamination is still affecting soil quality in the immediate vicinity of the chlor-alkali plant, located in Estarreja. Moreover, macrophyte harvesting for human direct or indirect use and the consumption of mussels, crabs and the sea bass from the Laranjo bay may constitute a health risk. Further studies focusing on developing skills for the restoration of the ecosystem are presently underway.

Impact of mercury contamination on the population dynamics of Peringia ulvae (Gastropoda): Implications on metal transfer through the trophic web

“…In fact, P. ulvae is the responsible for the mean annual incorporation of approximately 15 g of mercury in an area of 0.6 Km 2 . This value may seem negligible when comparing with the large amount of mercury accumulated in the Laranjo Bay sediments (z30 tons; Pereira et al, 2009). However, if we consider the other species that are directly associated to this gastropod, this value can have a strong relevance in terms of mercury biomagnification.…”

Ecological strategy for soil contaminated with mercury

“…chlor-alkali production processes) as well as in other countries (Zagury et al 2006;Dufault et al 2009;Esbrí et al 2014) have been using mercury and its compounds in manufacturing processes, which resulted in high concentrations of mercury in nearby soils. This poses potential health and environmental risk over a much wider area Pereira et al 2009). The most popular remediation technologies for mercury contaminated soils are: liquid extraction, thermal treatment, electrolytic methods, mercury flotation or immobilisation and solidification/stabilisation (S/S).…”

Coastal Lagoons in Europe: Integrated Water Resource Strategies

“…The mesohaline-oligohaline muddy-sandy habitats were classified as 'Good-Moderate EcoQS', while the oligohaline-limnetic muddy-sand habitats were evaluated as 'Moderate' to 'Bad EcoQS'. In addition, Nunes et al (2008) performed a more detailed study restricted to the historical contamination in the 2 km 2 Laranjo basin area close to Estarreja (Figure 17.5), concluding that macrobenthic community structure changed significantly along the mercury gradient (for a more detailed information regarding the Hg historical contamination see Pereira et al (2009)). Results showed that the increase of mercury contamination was associated with reduced total abundance, lower species diversity dominance of taxa tolerant to mercury (Nunes et al 2008).…”