Use of diatom assemblages as biomonitor of the impact of treated uranium mining effluent discharge on a stream: case study of the Ritord watershed (Center-West France)

Abstract

The rehabilitation of French former uranium mining sites has not prevented the contamination of the surrounding aquatic ecosystems with metal elements. This study assesses the impact of the discharge of treated uranium mining effluents on periphytic diatom communities to evaluate their potential of bioindication. A 7-month survey was conducted on the Ritord watercourse to measure the environmental conditions of microalgae, the non-taxonomic attributes of periphyton (photosynthesis and biomass) and to determine the specific composition of diatom assemblages grown on artificial substrates. The environmental conditions were altered by the mine waters, that contaminate the watercourse with uranium and with chemicals used in the pit-water treatment plants (BaCl2 and Al2(SO4)3). The biomass and photosynthetic activity of periphyton seemed not to respond to the stress induced by the treated mining effluents whereas the altered environmental conditions clearly impacted the composition of diatom communities. Downstream the discharges, the communities tended to be characterized by indicator species belonging to the genera Fragilaria, Eunotia and Brachysira and were highly similar to assemblages at acid mine drainage sites. The species Eunotia pectinalis var. undulata, Psammothidium rechtensis, Gomphonema lagenula and Pinnularia major were found to be sensitive to uranium effluents whereas Neidium alpinum and several species of Gomphonema tolerated this contamination. The relevance of diatoms as ecological indicator was illustrated through the changes in structure of communities induced by the discharge of uranium mining effluents and creates prospects for development of a bioindicator tool for this kind of impairment of water quality.

In situ effects of metal contamination from former uranium mining sites on the health of the three-spined stickleback (Gasterosteus aculeatus, L.)

“…The high levels of uranium and manganese (and aluminum for the Pontabrier Pond) found in the Pontabrier and Saint-Pierre Ponds are characteristic of contamination from uranium mining and processing. These five metals (uranium, aluminum, manganese, iron and barium) were frequently found at significant concentrations in other ecotoxicological studies dealing with uranium mines (Cazala et al 2008;Gagnaire et al 2015;Herlory et al 2013;Marques et al 2013;Pereira et al 2008).…”

“…For example, barium chloride and sulfate can be used to bind and precipitate radium (a decay product from uranium) from uranium mining effluents (Hudcova et al 2013). Aluminum sulfate also can be used to precipitate iron and to increase uranium mobility (Cazala et al 2008;Herlory et al 2013). These chemicals pollute water used to fill underground and opencast mines.…”

Herbicide toxicity on river biofilms assessed by pulse amplitude modulated (PAM) fluorometry

“…To our knowledge, only Luís et al (2013) and Herlory et al (2013) have assessed effects of toxicants on biofilms using the RLC approach. Luís et al (2013) used this method in a field study in an area strongly affected by acid mine drainage.…”

“…A convenient alternative is the establishment of so-called fluorescence rapid light curves (RLCs), which can be completed within 2 min (Schreiber et al, 1997;White and Critchley, 1999). This approach has been commonly used on various photosynthetic organisms, including microalgal biofilms (Kromkamp et al, 1998;Roberts et al, 2004;Serôdio et al, 2005), but reports of the use of RLCs to highlight toxicant effects are scarce (Luís et al, 2013;Herlory et al, 2013). Nevertheless it offers promising perspectives particularly when working with toxicants with less specific modes of action than PSII inhibitors.…”

Substratum‐Associated Microbiota

“…A review of the current state of knowledge of remediation methods for arsenic contamination of groundwaters and surface waters highlighted recent advances particularly around strategies of bioremediation (Bahar et al, 2013). (Herlory et al, 2013). Mkandawire (2013) used a biogeochemical perspective to review the risks and bioremediation approaches to uranium contamination, especially over the traditional approaches of abandoned uranium mining and processing sites.…”