Modeling the impact of mining on water quality and ecosystem in the boreal Lake Sulkavanjärvi, Finland

Mining activities near a lake can significantly impact its water quality and ecosystem. These impacts often arise from the release of heavy metals, sediments, and nutrients into the lake via surface runoff or groundwater seepage. Elevated levels of these substances can disrupt natural equilibrium, leading to problems such as acidification, eutrophication, and contamination of aquatic habitats. This study applies the AQUATOX model to assess the effects of mining on the water quality and ecosystem of a boreal lake. The research was carried out in a small humic boreal lake Sulkavanjärvi in the central part of Finland (63°06′50′′N, 27°41′30′′E) (area 3.1 km², mean depth 3.7 m, max depth 17 m). It is located close to an open pit apatite (major source of phosphorus) mine from which surface runoff and groundwater discharge contamination is suspected. The model simulates key pollutants, including nutrients and sediments, while incorporating multiple trophic levels such as planktonic algae, invertebrates, and diverse fish species. The lake is covered by ice from November to April and ice cover condition was applied when the water temperature dropped below 3 °C. The water mass was allowed to stratify into epilimnion and hypolimnion at the 3 °C temperature difference. Modeled time series of food web compartment biomass were obtained and analyzed for the modeling period 01.01.2011 - 31.12.2021. The nutrient and oxygen dynamics were evaluated with an emphasis on forecasting the impact of various contamination scenarios on the local ecosystem.