Environmental footprint of small-scale, historical mining and metallurgy in the Swedish boreal forest landscape: The Moshyttan blast furnace as microcosm

Abstract

The history of mining and smelting and the associated pollution have been documented using lake sediments for decades, but the broader ecological implications are not well studied. We analyzed sediment profiles covering the past ~10,000 years from three lakes associated with an iron blast furnace in central Sweden, as an example of the many small-scale furnaces with historical roots in the medieval period. With a focus on long-term lake-water quality, we analyzed multiple proxies including geochemistry, pollen and charcoal, diatom composition and inferred pH, biogenic silica (bSi), visible near-infrared spectroscopy (VNIRS)-inferred lake-water total organic carbon (LW-TOC), and VNIRS-inferred sediment chlorophyll (sed-Chl). All three lakes had stable conditions during the middle Holocene (~5000 BCE to 1110 CE) typical of oligo-dystrophic lakes: pH 5.4–5.6, LW-TOC 15–18 mg L−1. The most important diatom taxa include, for example, Aulacoseira scalaris, Brachysira neoexilis, and Frustulia saxonica. From ~1150 CE, decreases in LW-TOC, bSi, and sed-Chl in all three lakes coincide with a suite of proxies indicating disturbance associated with local, small-scale agriculture, and the more widespread use of the landscape in the past (e.g. forest grazing, charcoal production). Most important was a decline in LW-TOC by 30–50% in the three lakes prior to the 20th century. In addition, the one lake (Fickeln) downstream of the smelter and main areas of cultivation experienced a shift in diatom composition (mainly increasing Asterionella formosa) and a 0.6 pH increase coinciding with increasing cereal pollen and signs of blast furnace activity. The pH did not change in the other two lakes in response to disturbance; however, these lakes show a slight increase (0.3–0.5 pH units) because of modern liming. LW-TOC has returned to background levels in the downstream lake and remains lower in the other two.

Long‐term development and trajectories of inferred lake‐water organic carbon and pH in naturally acidic boreal lakes

“…Furthermore, in Dragsjön and Lång‐Älgsjön the early increase in lake‐water TOC coincides with the evidence of nearshore peatland development as an important driver of lake‐water TOC. The rapid increase in lake‐water TOC is also similar to other lakes that we have studied at Moshyttan in central Sweden, where concentrations plateaued at 14–17 mg L −1 after 3000–5300 yr (Myrstener et al 2019). Independent support for the early increase in lake‐water TOC in these lakes is found in the diatom record, where most of the acidophilic diatom taxa ( E. incisa and F. rhomboides agg.)…”

“…S6, S7). The stable pH, despite atmospheric acid deposition, is different from the southern lakes but not uncommon in other naturally acidic lakes in central Sweden (Norberg et al 2008; Myrstener et al 2019). The return of epipelic taxa can be interpreted as a deepening of the photic zone and increased habitat for epipelon, which coincides with the historically low concentrations of lake‐water TOC (presented in the following section).…”

Impacts of Large-Scale Open-Pit Coal Base on the Landscape Ecological Health of Semi-Arid Grasslands

“…The problem of landscape transformations due to human activities has been present in the literature for over a hundred years and has undergone successive stages of scientific diagnosis-from ascertaining the fact of transformations and their description, through classifying the forms and processes, to the quantitative and qualitative recognition of transformations [4]. Therefore, mining activities have caused a wide range of significant impacts on the landscapes not only in China [6,7], but also in Europe [4,[8][9][10][11][12], Asia [13][14][15][16], Americas [17][18][19], Africa [20,21], and Oceania [22,23]. It follows that large-scale coal exploitation activities, often lead to severe disturbances of regional landscape ecology.…”

The resolution of the transition conflict from tourism to mining in Pangkal Niur Village through the strengthening of social capital

“…Conventional open-pit mining tends to alter land topography and the balance of surface ecosystems, impacting soil productivity and environmental quality (Myrstener et al 2019, Feger & Mermet 2020, Huckleberry 2022). However, efforts can be made to mitigate the impacts of open-pit mining, such as block mining starting from the lowest slope and direct land reclamation or filling after mining is completed.…”