Harris,S.H. and Smith,R.L.(2009): In situ measurements of microbially-catalyzed nitrification and nitrate reduction rates in an ephemeral drainage channel receiving water from coalbed natural gas discharge, Powder River Basin, Wyoming, USA. Chemical Geology, 267, 77-84.

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wAbstract
@Nitrification and nitrate reduction were examined in an ephemeral drainage channel receiving discharge from coalbed natural gas (CBNG) production wells in the Powder River Basin, Wyoming, CBNG co-produced water typically contains dissolved inorganic nitrogen (DIN), primarily as ammonium. In this study, a substantial portion of discharged ammonium was oxidized within 50 m of downstream transport, but speciation was markedly influenced by diel fluctuations in dissolved oxygen („300ƒสM). After 300 m of transport, 60“ of the initial DIN load had been removed. The effect of benthic nitrogen-cycling processes on stream water chemistry was assessed at 2 locations within the stream channel using acrylic chambers to conduct short-term (2-6 h), in-stream incubations. The highest ambient DIN removal rates (2103 ƒสmol N m-2 h-1) were found at a location where ammonium concentrations „350ƒสM. This occurred during light incubation when oxygen concentrations were highest. Nitrification was occurring at the site, however, net accumulation of nitrate and nitrite accounted for ƒ12“ of the ammonium consumed, indicating that other ammonium-consuming processes were also occurring. In dark incubations, nitrite and nitrate consumption were dominant processes, while ammonium was produced rather than consumed. At a downstream location nitrification was not a factor and changes in DIN removal rates were controlled by nitrate reduction, diel fluctuations in oxygen concentration, and availability of electron donor. This study indicates that short-term adaptation of stream channel processes can be effective for removing CBNG DIN loads given sufficient travel distances, but the long-term potential for nitrogen remobilization and nitrogen saturation remain to be determined.

Keywords: Coal bed natural gas; Powder River Basin; Nitrification; Nitrate reduction; Ammonium; In situ ratex

1. Introduction
2. Site description
3. Materials and methods
@3.1. Water sample collection
@3.2. In situ incubations
@3.3. Chemical analyses
4. Results and discussion
@4.1. Channel water chemistry
@4.2. In situ incubations at the nitrification site
@4.3. In situ incubations at the nitrate reduction site
5. Implications and conclusions
Acknowledgements
References


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