Abstract
Acid mine drainage represents an extreme environment with high concentrations of potentially toxic elements and low pH values. These aquatic habitats are characterised by harsh conditions for biota, being dominated by acidophilic organisms. The study site, São Domingos mine, located in one of the largest metallogenetic provinces in the world, the Iberian Pyrite Belt, was closed without preventive measures. To identify the algae species and understand the relationships with abiotic parameters of the ecosystem, water and biological material were collected and analysed. Digital terrain models were obtained with an unmanned aerial vehicle for geomorphological and hydrologic characterisation of the mine degraded landscape. The results show two types of algal colours that seem to represent different degrees of photosynthetic activity. Optical and scanning electron microscopy revealed 14 taxa at the genus level, divided into eight classes. The genus Mougeotia is the most abundant multicellular algae. With respect to unicellular algae, diatoms are ubiquitous and abundant. Abiotic analyses expose typical features of acid mine drainage and support an inverse relationship between chemical contamination and biological diversity. Factorial correspondence analysis indicates three groups of attributes and samples by their relationship with specific toxic elements. This analysis also suggests a close association between Spirogyra and Pb, together composing a structurally simple ecosystem. The highest contamination in the river system is related to the hydrologic patterns obtained from photogrammetric products, such as the digital surface model and flow map accumulation, indicating the input of leachates from the section having the finest sulfide-rich wastes. Information about the algae community and their association with flow patterns of toxic elements is a relevant tool from a biomonitoring perspective.
Highlights
The area is morphologically dominated by a V-shaped valley, more or less open, which talweg constitutes the bottom of the São Domingos stream
The mining waste deposits with contaminants, resulting from mining activity, are predominantly on the east side of the stream. These deposits are exposed to precipitation and can be mobilized by surface run-off in the direction of the talweg, which means that the flow is mainly in the direction of the riverbed of São Domingos stream
Algae senescence was detected by the brown-purplish colour, indicative of photosynthetic pigments loss, as well as of all the cellular organelles
Summary
The affected systems show high concentrations of potentially toxic elements (PTE), low pH and presence of iron colloids, causing water turbidity and nutrient deficiency These characteristics contribute to stress conditions that affect biota by inducing a reduction in biodiversity [3]. These environments are dominated mostly by prokaryotes and eukaryotes that are acidophilic and acid-tolerant, composing a structurally simple ecosystem [4]. These organisms play important roles in safeguarding primary production and can be divided into two groups: chemoautotrophic (mainly bacteria) and photoautotrophic (such as acidophilic algae).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
