Quantification and Speciation of Trace Metals under Pollution Impact: Case Study of a Subarctic Lake

Abstract

Monitoring the quantity and quality of metals in lake water is a major part of assessing water toxicity. A fundamental aspect of geochemical monitoring studies is the evaluation of the equilibrium distribution of metal speciation in water and the influence of environmental conditions on this process. It is important to understand the difference between the behavior of nanoparticles, dissolved particles, colloid particles, and suspended particles. This study involved environmental aquatic chemistry research and the assessment of the geochemical processes of metal speciation in an arctic lake in the metallurgical waste zone and other areas where natural processes prevail. Consecutive and parallel membrane filtration methods were used to compare the results of water analysis in Imandra Lake. The membrane pore sizes were 8, 1.2, 0.45, and 0.2 µm. The following filtrate characteristics were used: microfiltration-based mechanical suspension and oxidized contaminants (>8, 1.2, 0.45, 0.2, 0.1 μm), and ultrafiltration-based colloids, bacteria, viruses, etc. (less than 0.1 μm). Industrial effluents led to the formation of higher concentrations of elements (Ni, Cu, and Pb) in their labile forms. In the wastewater-mixing zone, the concentrations of most elements were evenly distributed in depth. In more distant areas, we found a significant increase in the concentration of elements in the near-bottom horizon in comparison with the surface water (Fe by more than three times). The obtained results showed that numerous elements had diverse distributions by speciation in the points located closer to the source of wastewater. This indicated the significant influence of the adsorption process on the system balance of elements such as Fe, Cu, and rare earth elements. The impact of the regional geochemical and anthropogenic speciation and the possible influence of climatic factors on the distribution of speciation were determined.

Microbial Sulfate Reduction (MSR) as a Nature‐Based Solution (NBS) to Mine Drainage: Contrasting Spatiotemporal Conditions in Northern Europe

“…The Khibiny alkaline massif on the Kola Peninsula (Figure 1d) consists of igneous rocks with titanite and apatite‐nepheline deposits (Kogarko, 2018). The massif is surrounded by two larger lakes: the Umbozero Lake to the east and the Imandra Lake to the west with lake areas of 320 and 880 km 2 , respectively (Figure 1; Dauvalter & Kashulin, 2010; Dinu et al., 2020). The Khibiny mountain valleys (Figure 1e) are characterized by sandy till deposits and a forest‐tundra ecosystem, while the higher plateaus (with mountain peaks up to 1000 m above the Umbozero and Imandra Lakes) hold mostly weathered rocks and Arctic tundra (Pereverzev, 2010).…”