Effects of chironomid density and dissolved oxygen on mercury efflux from profundal lake sediment. (2nd April 2016)

• Record Type: Journal Article
• Authors: Beutel, Marc W.; Cox, Suzanne E.; Gebremariam, Seyoum
• Is Part Of: Lake and reservoir management. Volume 32:Number 2(2016)
• Page Start: 158
• Page End: 167
• Publication Date: 2016-04-02
• Subjects: chironomid -- dissolved oxygen -- lake oxygenation -- methylmercury; Water quality management -- North America -- Periodicals; Lake restoration -- North America -- Periodicals; Lake restoration; Water quality management; North America; 628
• DOI: 10.1080/10402381.2016.1143065
• Languages: English
• ISSNs: 1040-2381

Abstract

ABSTRACT: Beutel MW, Cox SE, Gebremariam S. 2016. Effects of chironomid density and dissolved oxygen on mercury efflux from profundal lake sediment. Lake Reserv Manage. 32:158–167. Benthic macrofauna can dramatically affect the flux of dissolved compounds into and out of lake sediment. In this study, replicate experimental chambers containing profundal sediment from a relatively pristine lake were incubated under low (∼1000/m 2 ) and high (∼3800/m 2 ) chironomid densities and low (∼2.5 mg/L) and medium (∼5.0 mg/L) dissolved oxygen in chamber water. Dissolved methylmercury efflux rates were highest in high chironomid density/low oxygen chambers (0.35 ± 0.06 ng/m 2 /d, mean ± standard error, n = 4) and lowest in low density/medium oxygen chambers (0.06 ± 0.14 ng/m 2 /d). In contrast, dissolved total mercury efflux assessed at low dissolved oxygen (∼2.5 mg/L) was higher at low chironomid density (4.6 ± 0.7 ng/m 2 /d) relative to high chironomid density (2.5 ± 0.8 ng/m 2 /d, n = 4). Results indicate that oxygen addition, a common lake management practice, may enhance methylmercury efflux from profundal sediment as macrofauna recolonize previously anaerobic sediments. However, benthos-mediated methylmercury efflux rates are lower than hypolimnetic methylmercury accumulation rates under anaerobic conditions; therefore, relative to anaerobic conditions, oxygenation should lower net methylmercury accumulation rates in relatively pristine lakes.