Environmental impact of mining activities in the Lousal area (Portugal): Chemical and diatom characterization of metal-contaminated stream sediments and surface water of Corona stream

• Published in: The Science of the total environment Vol. 409; no. 20; pp. 4312 - 4325
• Main Authors: Luís, Ana Teresa, Teixeira, Paula, Almeida, Salomé Fernandes Pinheiro, Matos, João Xavier, da Silva, Eduardo Ferreira
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15-09-2011; Elsevier
• Subjects: Achnanthidium minutissimum; acid mine drainage; Acid mine drainage (AMD); Animal, plant and microbial ecology; Applied ecology; aquatic organisms; Bacillariophyceae; Biological and medical sciences; Brachysira vitrea; Cadmium; Copper; Data Interpretation, Statistical; Diatoms; Diatoms - drug effects; Diatoms - ultrastructure; Ecotoxicology, biological effects of pollution; effluents; environmental factors; environmental impact; Environmental Monitoring - methods; Environmental Monitoring - statistics & numerical data; Fragilaria; Fresh Water - chemistry; Fresh water environment; freshwater; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; heavy metals; infrastructure; Lead (metal); Lousal mining area; Metals, Heavy - analysis; Metals, Heavy - toxicity; Microscopy, Electron, Scanning; Mines; Mining; Mining - standards; Nitzschia; Nitzschia hantzschiana; Pinnularia; Pinnularia acoricola; Portugal; Seasons; Sediment/water interaction; Sediments; Streams; surface water; Teratologies; Vitrea; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - toxicity; Zinc; Portugal; Europe; Lousal mining area; Acid mine drainage (AMD); Diatoms; Teratologies; Sediment/water interaction; Sediment water interaction; Algae; Metal; Sediments; Freshwater environment; Mining; Heterokontophyta; Bacillariophyta; Environment impact; Stream; Water pollution; Acid mine drainage
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2011.06.052

Lousal mine is a typical “abandoned mine” with all sorts of problems as consequence of the cessation of the mining activity and lack of infrastructure maintenance. The mine is closed at present, but the heavy metal enriched tailings remain at the surface in oxidizing conditions. Surface water and stream sediments revealed much higher concentrations than the local geochemical background values, which the “Contaminated Sediment Standing Team” classifies as very toxic. High concentrations of Cu, Pb, Zn, As, Cd and Hg occurred within the stream sediments downstream of the tailings sites (up to: 817
mg
kg
−1 As, 6.7
mg
kg
−1 Cd, 1568
mg
kg
−1 Cu, 1059
mg
kg
−1 Pb, 82.4
mg
kg
−1 Sb, 4373
mg
kg
−1 Zn). The AMD waters showed values of pH ranging from 1.9 to 2.9 and concentrations of 9249 to 20,700
mg
L
−1 SO
4
−2, 959 to 4830
mg
L
−1 Fe and 136 to 624
mg
L
−1 Al. Meanwhile, the acid effluents and mixed stream waters also carried high contents of SO
4
2−, Fe, Al, Cu, Pb, Zn, Cd, and As, generally exceeding the Fresh Water Aquatic Life Acute Criteria. Negative impacts in the diatom communities growing at different sites along a strong metal pollution gradient were shown through Canonical Correspondence Analysis: in the sites influenced by Acid Mine Drainage (AMD), the dominant taxon was
Achnanthidium minutissimum. However,
Pinnularia acoricola was the dominant species when the environmental conditions were extremely adverse: very low pH and high metal concentrations (sites 2 and 3). Teratological forms of
Achnanthidium minutissimum (Kützing) Czarnecki,
Brachysira vitrea (Grunow) Ross in Hartley,
Fragilaria rumpens (Kützing) G. W. F. Carlson and
Nitzschia hantzschiana Rabenhorst were found. A morphometric study of
B. vitrea showed that a decrease in size was evident at the most contaminated sites. These results are evidence of metal and acidic pollution.
► We have performed the geochemical characterization of the Lousal area. ► We evaluate the extent of pollution in sediments and stream waters and related toxicity. ► We investigate the geochemical characteristics of the AMD discharged from the abandoned mine adits and tailing piles. ► We compare the diatom communities along a strong metal pollution gradient. ► We evidence the presence of teratological forms and the decrease in individual cell size due to metal pollution and low pH.