Reduced phosphorus retention by anoxic bottom sediments after the remediation of an industrial acidified lake area: Indications from P, Al, and Fe sediment fractions

Gertrud K Nürnberg; Rachele Fischer; Andrew M Paterson

doi:10.1016/j.scitotenv.2018.01.103

Reduced phosphorus retention by anoxic bottom sediments after the remediation of an industrial acidified lake area: Indications from P, Al, and Fe sediment fractions

Sci Total Environ. 2018 Jun 1:626:412-422. doi: 10.1016/j.scitotenv.2018.01.103. Epub 2018 Feb 19.

Authors

Gertrud K Nürnberg¹, Rachele Fischer², Andrew M Paterson³

Affiliations

¹ Freshwater Research, 3421 Hwy 117, Baysville, ON P0B 1A0, Canada. Electronic address: gkn@fwr.ca.
² Ontario Ministry of Natural Resources and Forestry, 300 Water Street, Peterborough, ON K9J 3C7, Canada.
³ Ontario Ministry of the Environment and Climate Change, Dorset Environmental Science Centre, Dorset, ON P0A 1E0, Canada.

PMID: 29358136
DOI: 10.1016/j.scitotenv.2018.01.103

Abstract

Formerly acidified lakes and watersheds can become more productive when recovering from acidity, especially when exposed to anthropogenic disturbance and increased nutrient loading. Occasional toxic cyanobacterial blooms and other signs of eutrophication have been observed for a decade in lakes located in the Sudbury, Ontario, mining area that was severely affected by acid deposition before the start of smelter emission reductions in the 1970s. Oligotrophic Long Lake and its upstream lakes have been exposed to waste water input and development impacts from the City of Greater Sudbury and likely have a legacy of nutrient enrichment in their sediment. Based on observations from other published studies, we hypothesized that P, which was previously adsorbed by metals liberated during acidification caused by the mining activities, is now being released from the sediment as internal P loading contributing to increased cyanobacteria biomass. Support for this hypothesis includes (1) lake observations of oxygen depletion and hypolimnetic anoxia and slightly elevated hypolimnetic total P concentration and (2) P, Al, and Fe fractionation of two sediment layers (0-5, 5-10 cm), showing elevated concentrations of TP and iron releasable P (BD-fraction), decreased concentrations in fractions associated with Al, and fraction ratios indicating decreased sediment adsorption capacity. The comparison with two moderately enriched lakes within 200 km distance, but never directly affected by mining operations, supports the increasing similarity of Long Lake surficial sediment adsorption capacity with that of unaffected lakes. There is cause for concern that increased eutrophication including the proliferation of cyanobacteria of formerly acidic lakes is wide-spread and occurs wherever recovery coincides with anthropogenic disturbances and physical changes related to climate change.

Keywords: Cyanobacteria; Eutrophication; Internal phosphorus load; Mining-affected, acidified lakes; Sediment P adsorption capacity.