Bioaccumulation of metals by algae from acid mine drainage: a case study of Frongoch Mine (UK)

Abstract

In Frongoch Mine (UK), it is unclear the distribution of metals on indigenous algae and whether these species of algae can accumulate metals. This study aimed to investigate the role of indigenous algae for metal removal from acid mine drainage and understand if metals can be adsorbed on the surface of algae or/and bioaccumulated in algae. A sequential extraction procedure was applied for algae samples collected from acid mine drainage (AMD) water to identify the forms in which metals are found in algae. Concentrations of Fe, Pb, Zn, Cu and Cd were evaluated in the algae and AMD samples were collected in June and October 2019. AMDs samples had a pH value ranging between 3.5 and 6.9 and high concentrations of Zn (351 mg/L) and Pb (4.22 mg/L) that exceeded the water quality standards (Water Framework Directive, 2015). Algae Ulothrix sp. and Oedogonium sp. were the two main species in the Frongoch AMDs. The concentrations of metals in algae ranged from 0.007 to 51 mg/g, and the bioconcentration factor of metals decreased in the following order: Fe > > Pb > > Cu > Cd > Zn. It was found that Zn, Cu and Cd were adsorbed onto the surface of and bioaccumulated in the algae, while Pb and Fe were mainly bioaccumulated in the algae. Indigenous algae can be considered as a biogeochemical barrier where metals are accumulating and can be used in bioremediation methods. Also, indigenous algae could be used as a bioindicator to assess water pollution at Frongoch Mine and other similar metal mines.

Reclamation Potential of Onsite Wastewater Post-Treatment with Microalgae: Chemical Elements Perspective

“…was demonstrated in the studies by Say et al, 1977, Say andWhitton 1981;Takamura et al, 1989;Stevens et al, 2001;Skowro ńsky et al, 2002;Gaysina et al, 2009 [61-66]. Although there is lack of data on the species used in our study, it is generally known that algae can hyper-accumulate different metals, including the non-nutrient Pb and Cd, but also the nutritional Cu, Zn, and Fe, with the highest accumulation ratio of Fe, followed by Pb, Cu, Cd, and Zn [67][68][69][70][71][72]. An important statement was made after the experiments conducted by Oberholster et al, 2014, who demonstrated that certain algal species have preferences in elemental bioaccumulation since the accumulated amount of selected metals in the biomass was not strongly dependent on their concentration in the wastewater.…”

Algae, biochar and bacteria for acid mine drainage (AMD) remediation: A review

“…In addition, cell walls, nuclei, mitochondria, chloroplasts, and some other parts of the cell may be reinforced by the membrane, which works as a barrier in adapted cells (Chen et al, 2012;Sandau et al, 1996;Tam et al, 1998). In these two stages, some of the metals are bound to the surface, and others may be accumulated within cell due to metals' type and algae growth preference (Du et al, 2022). Surface adsorption is essential since it represents the largest portion of the absorption process (Chojnacka et al, 2005).…”

“…Surface adsorption is essential since it represents the largest portion of the absorption process (Chojnacka et al, 2005). Still, the relative importance of surface adsorption may vary depending on the metals and algae (Du et al, 2022). Nevertheless, the complexity of the algae surface makes it possible for various mechanisms to operate simultaneously (Monteiro et al, 2012).…”

“…For example, the types of algae and metal may both affect the results. Also, seasonal parameters, such as precipitation and runoff, may cause the initial metal ion concentration and temperature to vary with time in AMD sites (Du et al, 2022). Therefore, a clear relationship between temperature and metal removal efficiency should be investigated for different combinations of metals and algal species, especially in practical AMD conditions.…”

“…The authors have not found any study that has applied algae, bacteria, and biochar as a consortium to remediate and recover metals from AMD. In a natural AMD environment, bacteria and algae can be present as a consortium (Bernardez and de Andrade Lima, 2015;Du et al, 2022). In addition, based on the discussion above, one novel aspect of our exploratory approach is to use biochar as a porous support medium for the growth of the algal-bacteria consortium (Fig.…”