Cladocera as sentinels of aquatic mine pollution

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Title: Cladocera as sentinels of aquatic mine pollution
Author: Leppänen, Jaakko
Contributor: University of Helsinki, Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme
Doctoral Programme in Interdisciplinary Environmental Sciences
Publisher: Helsingin yliopisto
Date: 2019-04-05
Belongs to series: URN:ISSN:2342-5431
Thesis level: Doctoral dissertation (article-based)
Abstract: The mining industry has a critical role in modern societies. However, the environmental harm induced by mining activities may be drastic. One of the most important aspects of mining pollution is water contamination due to accidental or controlled waste water release, or due to harmful leachate originating from waste areas. Whereas the water quality in receiving water systems is usually monitored, the ecological impacts of mine waters are assessed more rarely. One of the challenges when ecological impacts are studied is the lack of long-term data regarding the pre-mining conditions. Palaeolimnological methods allow the reconstruction of historical conditions of water bodies. Sedimentary geochemistry and subfossil remains of biological communities (e.g. cladoceran crustacea, diatom algae) can be used to assess the natural pre-disturbance variability, the impact of the disturbance and the post-disturbance dynamics. In this thesis, mining pollution is assessed within three projects, conducted on two boreal lakes in Finland. In Lake Kirkkojärvi, the impact of historical mining activity, namely, the direct release of mineral tailings was studied from a sediment core covering also the pre-mining environmental conditions. The impacts of the mine pollutants were reflected in cladoceran communities as declining species richness and diversity. The lake Kirkkojärvi bay was studied by using a palaeolimnological top-bottom approach. The bay has been receiving acid mine drainage for nearly 50 years. However, the cladoceran community change in the bay does not reflect any changes in acidity or metal pollution. In Lake Kivijärvi the Na2SO4- and metal-contaminated mine water has had a clear impact on cladoceran and diatom communities as both groups exhibit changes due to mining pollution. Based on the results, the most important contaminants in the studied systems are saline effluents and mineral tailings. Cladocera hold great potential in palaeolimnological mining pollution studies due to their sensitivity to changes in the water quality and due to their central location in food-webs. However, more research is still needed: Most importantly, some taxonomic issues must be clarified and in-situ toxicity studies should be conducted in order to find the most sensitive indicator species for different types of pollution. The results of this work present important information regarding pollution impact assessment. In particular, this study highlights the utility of Cladocera as early warning indicators, while supporting the use of multiple sediment proxies in palaeolimnological pollution research in order to provide information about the timing, direction, and magnitude of ecosystem impacts caused by pollution events. This is of essence for environmental management as globally the exploitation of poor-grade large mine deposits will drastically increase in the near future. Only by providing such crucial information on the short- and long-term impacts of mining on aquatic ecosystems and their resilience, a technologically, socially and environmentally sustainable management of mines can be guaranteed in the future.Väitöskirja käsittelee kaivosten jätevesien vaikutuksia järvien eläinplanktoniin (vesikirput; Cladocera). Väitöskirjan artikkeleissa tutkitaan rikastushiekan/jäteaineksen ja happaman kaivosvaluman vaikutuksia vesikirppuyhteisöön ajallisesti ja paikallisesti Pirkanmaalla. Lisäksi tutkitaan suolaantuneen kaivosveden vaikutuksia vesikirppu – ja piileväyhteisöihin Kainuussa. Tulokset osoittavat, että happamuus tai raskasmetallit eivät tutkituissa kohteissa todennäköisesti ole niitä tekijöitä, jotka ovat vaikuttaneet vesikirppuyhteisöihin eniten. Perustuen lajien ekologisiin preferensseihin, tärkeimmät haitta-aineet olivat rikastushiekka ja suolaantuminen. Väitöskirjan tulokset vahvistavat paleolimnologisten menetelmien soveltuvuuden modernissa saastumistutkimuksessa ja osoittavat että ei-myrkyllisten jätekomponenttien merkitys voi kaivosten vesistövaikutuksissa olla huomattava.
Subject: Ympäristötieteet
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