Paleolimnological Fingerprinting of the Impact of Acid Mine Drainage After 50 Years of Chronic Pollution in a Southern Finnish Lake

Abstract

Acid mine drainage (AMD) is acknowledged to have long-lasting impacts on aquatic environments. Hence, mines have also been detected to pose problems years after closure due to the leaching of toxic drainage initiated by sulfide oxidation. To assess the effects of chronic but relatively low volume acid mine drainage derived from the Haveri copper-gold mine operating between 1938 and 1960 on a freshwater bay in southern Finland, we compared cladoceran assemblages from the pre-mining period with contemporary populations using paleolimnological approaches and multiple sediment cores. The cladoceran community of the pre-mining era differed significantly from the contemporary community of the lake (ANOSIM R = 0.91; p = 0.0001), but closely resembled the contemporary community of a nearby non-polluted reference site. Our results suggest that the differences in species compositions between pre-mining and contemporary samples are most likely caused by eutrophication and not by the AMD impact. Because AMD at our study site is most intense during the spring snowmelt period, cladocerans may avoid seasonal pollution peaks through winter dormancy. Possible pollution peaks resulting from heavy rains during the summer may have negative impacts on the cladoceran community, but such short-term impacts are probably rapidly counteracted by immigration from cleaner areas of the lake.

An overview of Cladoceran studies conducted in mine water impacted lakes

“…Polyphemus pediculus, Eubosmina coregoni, Daphnia sp., Alonella excisa, A. quandranqularis, Alonopsis elongata and Disparalona rostrata were negatively affected. In addition, the cladoceran community in the shallow embayment of the same lake is unharmed by low volume but continuous high-Cu low pH effluent (since 1970s) because the pollution is most intense during early spring, when the cladoceran communities are mostly absent (Leppänen et al 2017a). The lucky mismatch is further reflected in increased abundance of B. longirostris, which is especially sensitive to copper pollution but thrives in eutrophicated systems, such as Lake Kirkkojärvi.…”

Mining pollution triggered a regime shift in the cladoceran community of Lake Kirkkojärvi, southern Finland

“…In addition, according to the OIVA database (Finnish Environmental Institute), lakewater iron (Fe) and manganese (Mn) concentrations increased from the 1960s to the 1970s. The tailings dump is still leaking acid and metal-contaminated leachate into the bayhead of Lake Kirkkojärvi, but the current toxic impact is practically non-existent (Leppänen et al 2017).…”

“…The human population of Viljakkala was highest during the 1950s, corresponding to the time at which there was an increase in the use of artificial agricultural fertilizers and a concurrent impact in the trophic status of freshwater ecosystems in general (Räsänen et al 2006). Minor phosphorus enrichment was also detected in neighboring Lake Viljakkalanselkä (Kihlman and Kauppila 2010), but the modern cladoceran community there resembles the community structure of ZIII (Leppänen et al 2017).…”