Liming for the mitigation of acid rain effects in freshwaters: A review of recent results

Abstract

Acid rain has affected freshwater ecosystems for more than 50 years in much of northern Europe and North America. The acidification of waters, along with concurrent reduction in acid neutralization capacity, has caused deleterious changes to aquatic populations in much of these regions. To reverse some of the changes to aquatic ecosystems, a number of governmental and nongovernmental groups have applied lime and other neutralizing substances to streams, rivers, lakes, and catchments in the most affected or most ecologically valuable regions. We review the scientific literature published since the late 1980s on liming to provide an overview of successes and failures of various approaches. We discuss the rationale behind liming programs and why certain approaches may not be helpful in mitigating acidification effects under varying conditions. One of our main conclusions is that though water chemistry may be restored if only temporarily, aquatic communities probably will not return to their original states, though targeted fish species can be restored using active management approaches. The communities restored, however, are usually more unstable than those from undisturbed, or pre-acidification conditions. We also show that liming may have to be conducted for 50 to 60 years in some affected locations, which should affect the choice of approaches used in mitigation. Résumé :Les pluies acides affectent les écosystèmes d'eau douce du nord de l'Europe et de l'Amérique du Nord, depuis plus de 50 ans. Dans plusieurs de ces régions, l'acidification des eaux, ainsi que la réduction concurrente de la capacité de neutralisation des acides, a apporté des modifications néfastes dans les populations aquatiques. Afin de renverser certaines des modifications dans les systèmes aquatiques, un nombre de groupes gouvernementaux et non-gouvernementaux ont appliqué de la chaux, et autres substances neutralisantes, aux ruisseaux, aux rivières, aux lacs et aux bassins versants dans les régions les plus affectées, ou les plus importantes écologiquement. Les auteurs passent en revue la littérature scientifique depuis la fin des années 1980, sur le chaulage, afin de définir les succès et les échecs de différentes approches. Ils discutent la logique soutenant ces programmes et pourquoi certaines approches pourraient ne pas être utiles, pour mitiger les effets de l'acidification dans certaines conditions. Une des conclusions principales est que bien qu'on puisse corriger la chimie de l'eau, ne fusse que temporairement, les communautés aquatiques ne retourneront probablement pas à leur état d'origine, bien les espèces de poisson ciblées puissent être restaurées avec l'aide de techniques d'aménagement. Cependant, les communautés restaurées sont généralement moins stables que celles de milieux non-perturbés, ou celles de conditions antécédentes à l'acidification. Les auteurs montrent également que le chaulage a pu être pratiqué au cours des 50-60 dernières années dans certaines régions affectées, ce qui devrait influencer le choix des approches ...

Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

“…River A T originates from erosion and is correlated with bedrock composition (e.g., McGrath et al, 2016). Positive trends in river A T have been documented in North America and occur via a number of processes including (1) the interplay of rainfall and land use (Raymond and Cole, 2003), (2) anthropogenic limestone addition used to enhance agricultural soil pH (Oh and Raymond, 2006;Stets et al, 2014) and freshwater pH (Clair and Hindar, 2005), and (3) potentially indirect effects of anthropogenic CO 2 on groundwater CO 2 acidification and weathering (Macpherson et al, 2008). These and other processes were hypothesized to have driven A T changes in the Baltic Sea (Müller et al, 2016).…”

High elevation watersheds in the southern Appalachians: Indicators of sensitivity to acidic deposition and the potential for restoration through liming

“…The specific goals of liming streams or catchments are to increase stream ANC, pH and Ca while decreasing SO 4 and Al. Restoration practices include adding lime directly to stream water or treating the entire catchment with reported lime additions ranging from 5 to 30 Mg ha À1 (Clair and Hindar, 2005). Our estimated lime additions fall within this broad range, with 11.6-21.1 Mg ha À1 CaCO 3 required to increase the top 30 cm of soil to pH 5.5.…”

“…In an extensive literature review, Clair and Hindar (2005) examined liming experiments conducted from the 1980s to 2000, including various chemical compounds and methods of application. Overall, their review found that directly adding lime to the stream channel significantly improved the stream pH, chemistry, and suitability for fish populations.…”

“…A study by Long et al (2015) examined soil responses to a liming treatment Johnson et al (1995), but are within the range applied by others in the northeastern USA (Clair and Hindar, 2005;Long et al, 2015), suggesting that lime applications in these forests would result in long-term soil and stream responses.…”

Environmental water requirements: demand management in an era of water scarcity

“…Liming has been used for decades to counter impacts of acid rain in northern hemisphere countries like Sweden (Bengtsson et al 1980), although Clair and Hindar (2005) detail limitations to this remediation method. Stockner and MacIsaac (1996) observe benefits of a nutrient enrichment programme in British Columbia.…”