Browsing by Author "Caetano, Miguel"
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- Large spill of mining wastes in Portelo stream: impacts on ecosystem integrity and on angling potentialPublication . Geraldes, Ana Maria; Ramalhosa, Elsa; Caetano, Miguel; Teixeira, AmílcarStreams located at Montesinho Natural Park (NE Portugal) have high potential for brown trout (Salmo trutta) angling. However, in this territory there are several abandoned mine sites. Therefore, the continuous drainage of fine grained tailings can be particularly problematic due to arsenic, copper, aluminium and zinc. However, until now no significant disturbance was detected in water quality and in biota. Nevertheless, there has never been such a large spill of mining wastes as that occurred in January 2010. As a consequence of intense precipitation, several millions of cubic meters of wastes were spilled into Portelo stream. The large amount of wastes covered the riverbed with a layer of mud reaching more than half a meter in areas close to the mine. Both riparian and agricultural areas were also affected by the sediments from mine. Wastes were spilled downstream by several strong rain events. Thus, the objective of the present research was to evaluate the impact of this event on ecosystem integrity and ultimately on angling potential. To achieve the proposed objective the water from four sampling points along the affected stream was sampled for the following metals- AI, Mn, Co, Cu, Ni, Cd and As. Concomitantly, macroinvertebrate and fish assemblages were also assessed. Temporal differences between stations were not detected. On contrary spatial differences were found. As expected, the stations located near the 1nine showed the highest levels of contamination and disturbance. Consequently, in these stations no macroinvertebrates and fish were found during the period of study.
- Large spill of mining wastes in Portelo stream: impacts on ecosystem integrity and on angling potentialPublication . Geraldes, Ana Maria; Ramalhosa, Elsa; Caetano, Miguel; Teixeira, AmílcarStreams located at Montesinho Natural Park (NE Portugal) have high potential for brown trout (Salmo trutta) angling . However, in this territory there are severa! abandoned mine sites. Therefore, the continuous drainage of fine grained tailings can be particularly problematic due to arsenic, copper, aluminium and zinc. However, until now no significant disturbance was detected in water quality and in biota. Nevertheless, there has never been such a large spill of mining wastes as that occurred in January 201 O. As a consequence of intense precipitation, severa! millions of cubic meters of wastes were spilled into Portelo stream. The large amount of wastes covered the riverbed with a layer of mud reaching more than half a meter in areas close to the mine. Both riparian and agricultura! areas were also affected by the sediments from mine. Wastes were spilled downstream by severa! strong rain events. Thus, the objective of the present research was to evaluate the impact of this event on ecosystem integrity and ultimately on angling potential. To achieve the proposed objective the water from four sampling points along the affected stream was sampled for the following metais - AI , Mn, Co, Cu , Ni, Cd and As. Concomitantly, macroinvertebrate and fish assemblages were also assessed. Temporal differences between stations were not detected. On contrary spatial differences were found. As expected, the stations located near the mine showed the highest leveis of contamination and disturbance. Consequently, in these stations no macroinvertebrates and fish were found during the period of study.
- Mining wastes spill into a mountain stream (Douro basin, NE Portugal): Impact on water quality and macroinvertebrate assemblages.Publication . Geraldes, Ana Maria; Parada, Maria João; Ramalhosa, Elsa; Fernandes, Conceição; Caetano, Miguel; Teixeira, AmílcarA large spill of mining wastes into Portelo Stream a tributary of Sabor River (Douro Basin; NE Portugal) occurred in January 2010. In order to access the impact of this event, the aim of the present research was to evaluate the amplitude of the initial effects of the spill on the aquatic ecosystem, as well as, the recovery of the aquatic ecosystem after the mining spill. Water and macroinvertebrates were sampled monthly from January to July 2010, 2011 and 2012. Samplings were carried out in eight locations (P1 to P8) distributed along 20 km. Concentrations of Al, Mn, Co, Cu, Ni, Cd and As were measured in the dissolved fraction (<0.45 μm) of the water samples. Sampling stations located closer to the spill point (Portelo Stream) presented a low pH (≈ 4) and a potential toxicity due to the high Cu concentrations. The stations located at 15 km or more from the discharge point seemed not to have been significantly impacted by the mining spill. In terms of abundance and diversity of macroinvertebrate assemblages, a slow and progressive recovery was detected, with a gradual colonization by different taxa in disturbed areas, after their disappearance in January 2010. It should be emphasized the presence of organisms belonging to faunistic groups relatively sensitive to disturbance, like different insects of Trichoptera and Ephemerotera orders, in the sites closer to the mine, three years after the disaster.
- Mobility of contaminants in relation to dredging operations in a mesotidal estuary (Tagus Estuary, Portugal)Publication . Vale, Carlos; Ferreira, Ana M.; Micaelo, Cristina; Caetano, Miguel; Pereira, Eduarda; Madureira, Maria J.; Ramalhosa, ElsaDuring the construction of a New Bridge over the Tagus estuary 2.5 million tons of sediments were dredged, part of this quantity being contaminated material. The extension and intensity of the water turbidity associated with dredging operating varied with the tidal conditions but the resuspended material collected near the bucket dredger did not present a concentration increment in metals and PCB, when compared to the estuarine suspended sediments. The calculated distribution coefficients suggest that some contaminants in solids near the dredger were not in equilibrium with the water. A 24-hour laboratory experiment demonstrated the complexity and quickness of anoxic sediments oxidation. In such a short period of time metals in the solids change their fractionation. A second laboratory simulation showed that mussels accumulate metals and PCB congeners when placed in turbid aerated water.
- Recente colapso das escombreiras das minas do Portelo (NE Portugal) e impactos potenciais nos ecossistemas aquáticosPublication . Geraldes, Ana Maria; Ramalhosa, Elsa; Caetano, Miguel; Teixeira, AmílcarEm Janeiro de 2010 uma grande parte dos materiais armazenados nas escombreiras da mina do Portelo foi arrastada para a ribeira do Portelo. O objectivo do presente estudo foi avaliar o processo de recuperação da ribeira afectada por este acontecimento. Amostras de água e de macroinvertebrados foram recolhidas mensalmente entre Janeiro e Julho de 201 o em 4locais de amostragem: um local não influenciado pela entrada de inertes (controlo) e os outros 3 localizados a 250m, a 5 e a 15 km da mina. Foram determinados diversos parâmetros físicos-químicos, tais como o pH, a condutividade, o oxigénio dissolvido, a matéria particulada em suspensão e diversos metais por ICP-MS e amostradas as comunidades de macroinvertebrados. As águas recolhidas nos 2 pontos mais próximos da mina apresentavam valores de pH baixos (= 4) e toxicidade potencial devido às elevadas concentrações de Cu. Nestes locais os macroinvertebrados estavam ausentes. No ponto mais afastado da mina não foram detectados sinais de perturbação. Uma vez que não foram implementadas medidas de mitigação é possível que continuem a ocorrer entradas de água da mina e de sedimentos na ribeira do Portelo de forma contínua, podendo acentuar-se nos períodos em que ocorram fortes chuvadas. O presente trabalho pretende alertar para o facto deste tipo de contaminação poder ter impactos não só nos sistemas aquáticos do Parque Natural de Montesinho, mas também noutros ecossistemas com elevado valor ambiental e económico.