Photodegradation of methylmercury in stream ecosystems

Martin Tsz Ki Tsui, Joel D. Blum, Jacques C Finlay, Steven J. Balogh, Sae Yun Kwon, Yabing H. Nollet

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Photodegradation is an important sink for highly toxic methylmercury (MeHg) in aquatic ecosystems. Lakes have been extensively studied for MeHg photodegradation, but much less is known about streams, mainly because of the heterogeneity in sunlight availability along stream reaches and because there has been a lack of tools with which to integrate this longitudinal variability. We utilize odd-mass anomalies of stable Hg isotopes (i.e., Δ199Hg) as a proxy for estimating the relative extent of MeHg photodegradation in streams. In a northern California stream network, levels of MeHg in water and biota increased with increasing stream size in headwater and intermediate streams (drainage areas ranging from 0.6 to 150 km2), but MeHg levels decreased substantially in larger streams (drainage areas up to 1212 km2). In smaller streams, the increase of MeHg levels is attributed to increasing in situ MeHg production and is accompanied by only a small increase in Δ199Hg, indicating that the rate of MeHg photodegradation is low relative to the rate of in situ MeHg production. In larger streams, decreasing MeHg levels coincided with significant increases in Δ199Hg of MeHg (an average increase of 1.5% 6 0.5%, n 5 4), indicating that increasing MeHg photodegradation reduced MeHg levels in these wider, more open channels. Our findings clearly indicate that increasing sunlight availability in stream channels substantially increases MeHg photodegradation, which can reduce MeHg contamination in stream food webs.

Original languageEnglish (US)
Pages (from-to)13-22
Number of pages10
JournalLimnology and Oceanography
Volume58
Issue number1
DOIs
StatePublished - Jan 1 2013

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methylmercury compounds
photolysis
methylmercury
photodegradation
ecosystems
ecosystem
drainage
solar radiation
stream channel
stream channels
headwater
aquatic ecosystem
food webs
food web
biota
isotopes
stable isotope
anomaly
lakes

Cite this

Tsui, M. T. K., Blum, J. D., Finlay, J. C., Balogh, S. J., Kwon, S. Y., & Nollet, Y. H. (2013). Photodegradation of methylmercury in stream ecosystems. Limnology and Oceanography, 58(1), 13-22. https://doi.org/10.4319/lo.2013.58.1.0013

Photodegradation of methylmercury in stream ecosystems. / Tsui, Martin Tsz Ki; Blum, Joel D.; Finlay, Jacques C; Balogh, Steven J.; Kwon, Sae Yun; Nollet, Yabing H.

In: Limnology and Oceanography, Vol. 58, No. 1, 01.01.2013, p. 13-22.

Research output: Contribution to journalArticle

Tsui, MTK, Blum, JD, Finlay, JC, Balogh, SJ, Kwon, SY & Nollet, YH 2013, 'Photodegradation of methylmercury in stream ecosystems', Limnology and Oceanography, vol. 58, no. 1, pp. 13-22. https://doi.org/10.4319/lo.2013.58.1.0013
Tsui, Martin Tsz Ki ; Blum, Joel D. ; Finlay, Jacques C ; Balogh, Steven J. ; Kwon, Sae Yun ; Nollet, Yabing H. / Photodegradation of methylmercury in stream ecosystems. In: Limnology and Oceanography. 2013 ; Vol. 58, No. 1. pp. 13-22.
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