Assessment of factors limiting algal growth in acidic pit lakes—a case study from Western Australia, Australia

Abstract

Open-cut mining operations can form pit lakes on mine closure. These new water bodies typically have low nutrient concentrations and may have acidic and metal-contaminated waters from acid mine drainage (AMD) causing low algal biomass and algal biodiversity. A preliminary study was carried out on an acidic coal pit lake, Lake Kepwari, in Western Australia to determine which factors limited algal biomass. Water quality was monitored to obtain baseline data. pH ranged between 3.7 and 4.1, and solute concentrations were slightly elevated to levels of brackish water. Concentrations of N were highly relative to natural lakes, although concentrations of FRP (<0.01 mg/L) and C (total C 0.7-3.7 and DOC 0.7-3.5 mg/L) were very low, and as a result, algal growth was also extremely low. Microcosm experiment was conducted to test the hypothesis that nutrient enrichment will be able to stimulate algal growth regardless of water quality. Microcosms of Lake Kepwari water were amended with N, P and C nutrients with and without sediment. Nutrient amendments under microcosm conditions could not show any significant phytoplankton growth but was able to promote benthic algal growth. P amendments without sediment showed a statistically higher mean algal biomass concentration than controls or microcosms amended with phosphorus but with sediment did. Results indicated that algal biomass in acidic pit lake (Lake Kepwari) may be limited primarily by low nutrient concentrations (especially phosphorus) and not by low pH or elevated metal concentrations. Furthermore, sediment processes may also reduce the nutrient availability.

The Use of Digital Terrain Models to Estimate the Pace of Filling the Pit of a Central European Granite Quarry with Water

“…The potential use of water from pit lakes or quarry lakes depends on its quality and amount [11,19,23,36,37,47,[54][55][56][57]. These values are influenced by the size of the excavation pit, hydrogeological conditions, the geological structure of the mine and its surroundings, as well as the size and management of its own (direct) catchment [3,23,25,36,37,40,44,54,[58][59][60][61].…”

“…After discontinuation of dewatering, the pits fill with groundwater, rainfall, and surface runoff to form emerging pit lakes or quarry lakes [3,23,24,27,31,32,37,41,42,62,63], which may have different depths [3,23,24,30,31,36,50,57,58,61,[64][65][66][67], surface area [3,23,24,32,36,37,50,57,58,66,67] and cubic capacities [23,36,50,67,68], depending on the type of the excavated material and mining technology used [23,30,36,37,56,61,65]. Depending on the geomorphological parameters of an open-excavation pit, hydrogeological conditions, the geological structure of the mine and its surroundi...…”

Estimating Water Retention in Post-mining Excavations Using LiDAR ALS Data for the Strzelin Quarry, in Lower Silesia

“…This process may last for months, years, or even decades and its pace depends on the size of the excavation, the hydrogeological conditions, and the geological structure of the mine and its surroundings (Kumar et al 2016;Schultze et al 2010). Sometimes, water from rivers or streams is used to quickly flood the mine (Schultze et al 2010;Singleton et al 2013).…”

“…The lakes thus created can have different depths, surface areas and volume, depending on the excavated raw material and the mining technology (Clews et al 2014;Kumar et al 2016;McCullough and Lund 2006;Molenda 2006;Schultze et al 2010;Singleton et al 2013). The methods of determining the geomorphological parameters of the excavation depend on its accessibility and on the depth of the water reservoir (if it exists).…”

“…The potential use of mine and quarry lake water depends on both water quantity and quality (Axler et al 1996;Clews et al 2014;Doupé and Lymbery 2005;Kumar et al 2016;McCullough 2008;McCullough and Lund 2006;Schultze et al 2010).…”