The role of surface water and mine groundwater in the chemical stratification of an acidic pit lake (Iberian Pyrite Belt, Spain)

Changes in stratification and iron redox cycle of an acidic pit lake in relation with climatic factors and physical processes

“…According to previous information, the pit lake showed chemical stratification and two main layers: a thin mixolimnion (between 1 and 2 m depth), which was less dense than a thicker monimolimnion (chemically homogeneous layer from 3 to 34 m depth) Sánchez España et al, 2009;Santofimia and López-Pamo, 2010). Thus, the pit lake was classified as meromictic.…”

“…Due to the manner in which chemical stratification is generated (as in the case of saline lakes with inflow of freshwater runoff) this process can be classified as a kind of ectogenic meromixis (e.g. Hakala, 2004;Boehrer and Schultze, 2008, and references therein), as has been described for salt lakes (Bunn and Edward, 1984;Fisher and Lawrence, 2006;Jellison et al, 1998) and pit lakes (Santofimia and López-Pamo, 2010).…”

Consequences and opportunities from river breach and decant of an acidic mine pit lake

“…DO decreasing down through the CRSB likely due to biochemical oxygen demand by decaying organic matter from flood-mobilised allochthonous vegetation (Vannote et al, 1980). Elevated EC over summer months commensurate with declining lake water level indicate that groundwater inflows may have been unable to maintain lake water level during this time as had been found elsewhere (Santofimia and López-Pamo, 2013) either due to naturally declining groundwater level over summer or low rates of hydraulic conductance into the lake.…”

Quantitative analysis of biogeochemically controlled density stratification in an iron-meromictic lake

“…Meromictic lakes have been identified in many mining regions on earth where stratification limits the vertical transport of undesirable substances (e.g. Spain: Lake San Telmo, Cánovas et al, 2012, and Lake Conception, Santofimia and López-Pamo, 2013; Germany: Lake Wallendorfer See and Lake Rassnitzer See, Boehrer et al, 2014;Lake Moritzteich, von Rohden et al, 2009). In some cases, stratification has even been implemented to restrict the vertical transport (Island Copper Mine pit lake in Canada; Wilton et al, 1998;Stevens and Lawrence, 1998).…”

“…von or by increased surface runoff, whereas increased groundwater inflow and higher surface evaporation as well as diffusive processes are able to cause an upward movement of the chemocline (e.g. Santofimia and López-Pamo, 2013). Additionally, chemical reactions are able to sustain meromixis in lakes (Boehrer and Schultze, 2008).…”