Toxicity of acid mine pit lake water remediated with limestone and phosphorus

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

“…Although upstream Zn and Al concentrations were already elevated in the Collie River, downstream sites showed Al, Mn and Zn concentrations likely elevated by the lake Kepwari breach and decant. Although there are no 80% ecosystem protection guidelines for Al where pH <6.5, Al concentrations at the majority of sites were potentially toxic, due to increased monovalent Al concentrations at these lower pH values (Neil et al, 2009). However, the regular exceedance of water quality guidelines also by the reference South Branch site indicates that Collie River background concentrations were already elevated for many of these water quality parameters.…”

“…Increased algal biomass would largely be a response to elevated DOC and P concentrations following by CRSB inflow (Beulker et al, 2003;Tittel and Kamjunke, 2004). Indeed, phytoplankton appear to be more restricted by these macronutrient concentrations than by mineral acidity (Neil et al, 2009;McCullough and Horwitz, 2010).…”

“…Although metal concentrations were reduced overall river flow-through, there also appeared to be significant loss of calcium from the lake. However, the increased risk of metal toxicity at lower calcium concentrations (Markich and Jeffree, 1994) is likely offset by lower metal concentrations overall (Neil et al, 2009). Elevated ORP at sites closest to the breach likely reflects river water input diluting and neutralising acid lake water (Schultze et al, 2002).…”

“…Although Lake Kepwari was proposed as a recreation resource for primary water contact activities such as swimming and water skiing (Evans and Ashton, 2000), low pH and high metal concentrations currently restrict authorised use of the lake for these purposes (Neil et al, 2009). …”

Impacto da Mineração de Areia sobre a Química das Águas Subterrâneas, Distrito Areeiro da Piranema, Municípios de Itaguaí e Seropédica, Rio de Janeiro

“…A acidifi cação das águas que preenchem as cavas de mineração tem se tornado motivo de preocupação após o descomissionamento das minas. A exposição dos sedimentos, durante o processo de mineração de areia, na presença de água, oxida minerais de sulfeto, reduzindo o pH e disponibilizando contaminantes tóxicos a biota aquática (Lopes et al 1999, McCullough & Lund 2006, Modis et al 1998, Bachmann et al 2001, Ramstedt et al 2003, Denimal et al 2005, Pellicori et al 2005, Sheoran and Sheoran 2006, Neil et al 2009 Devido a sua posição litorânea, a topografi a exerce uma forte infl uência na delimitação de áreas mais chuvosas e menos chuvosas na área de estudo. Os ventos são do quadrante Sul, de onde são provenientes os principais sistemas produtores de chuva na região, ou seja, os sistemas frontais (Nimer 1977).…”