{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T04:19:05Z","timestamp":1789964345053,"version":"4.0.1"},"reference-count":32,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2011,9,1]],"date-time":"2011-09-01T00:00:00Z","timestamp":1314835200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["acsess.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J of Env Quality"],"published-print":{"date-parts":[[2011,9]]},"abstract":"<jats:p>Organic carbon bioreactors provide low\u2010cost, passive treatment of a variety of environmental contaminants but can have undesirable side effects in some cases. This study examines the production of methyl mercury (MeHg) in a streambed bioreactor consisting of 40 m<jats:sup>3<\/jats:sup> of wood chips and designed to treat nitrate (NO<jats:sub>3<\/jats:sub><jats:sup>\u2212<\/jats:sup>) in an agricultural drainage ditch in southern Ontario (Avon site). The reactor provides 30 to 100% removal of NO<jats:sub>3<\/jats:sub><jats:sup>\u2212<\/jats:sup>\u2013N concentrations of 0.6 to 4.4 mg L<jats:sup>\u22121<\/jats:sup>, but sulfate (SO<jats:sub>4<\/jats:sub><jats:sup>2\u2212<\/jats:sup>) reducing conditions develop when NO<jats:sub>3<\/jats:sub><jats:sup>\u2212<\/jats:sup> removal is complete. Sulfate reducing conditions are known to stimulation the production of MeHg in natural wetlands. Over one seasonal cycle, effluent MeHg ranged from 0.01 to 0.76 ng L<jats:sup>\u22121<\/jats:sup> and total Hg ranged from 1.3 to 3.4 ng L<jats:sup>\u22121<\/jats:sup>. During all sampling events when reducing conditions were only sufficient to promote NO<jats:sub>3<\/jats:sub><jats:sup>\u2212<\/jats:sup> reduction (or denitrification) (<jats:italic>n<\/jats:italic> = 5, late fall 2009, winter 2010), MeHg concentrations decreased in the reactor and it was a net sink for MeHg (mean flux of \u22125.1 \u03bcg m<jats:sup>\u22122<\/jats:sup> yr<jats:sup>\u22121<\/jats:sup>). During all sampling events when SO<jats:sub>4<\/jats:sub><jats:sup>2\u2212<\/jats:sup> reducing conditions were present (<jats:italic>n<\/jats:italic> = 6, early fall 2009, spring 2010), MeHg concentrations increased in the reactor and it was a strong source of MeHg to the stream (mean flux of 15.2 \u03bcg m<jats:sup>\u22122<\/jats:sup> yr<jats:sup>\u22121<\/jats:sup>). Total Hg was consistently removed in the reactor (10 of 11 sampling events) and was correlated to the total suspended sediment load (<jats:italic>r<\/jats:italic><jats:sup>2<\/jats:sup> = 0.69), which was removed in the reactor by physical filtration. This study shows that organic carbon bioreactors can be a strong source of MeHg production when SO<jats:sub>4<\/jats:sub><jats:sup>2\u2212<\/jats:sup> reducing conditions develop; however, maintaining NO<jats:sub>3<\/jats:sub><jats:sup>\u2212<\/jats:sup>\u2013N concentrations &gt; 0.5 mg L<jats:sup>\u22121<\/jats:sup> suppresses the production of MeHg.<\/jats:p>","DOI":"10.2134\/jeq2011.0072","type":"journal-article","created":{"date-parts":[[2011,8,25]],"date-time":"2011-08-25T12:44:37Z","timestamp":1314276277000},"page":"1586-1592","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":57,"title":["Nitrate Controls Methyl Mercury Production in a Streambed Bioreactor"],"prefix":"10.1002","volume":"40","author":[{"given":"Rita","family":"Shih","sequence":"first","affiliation":[{"name":"Dep. of Earth and Environmental Sciences Univ. of Waterloo 200 University Ave. W. Waterloo ON N2L 3G1 Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William D.","family":"Robertson","sequence":"additional","affiliation":[{"name":"Dep. of Earth and Environmental Sciences Univ. of Waterloo 200 University Ave. W. Waterloo ON N2L 3G1 Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sherry L.","family":"Schiff","sequence":"additional","affiliation":[{"name":"Dep. of Earth and Environmental Sciences Univ. of Waterloo 200 University Ave. W. Waterloo ON N2L 3G1 Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David L.","family":"Rudolph","sequence":"additional","affiliation":[{"name":"Dep. of Earth and Environmental Sciences Univ. of Waterloo 200 University Ave. W. 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