Nitrate uptake rate in anoxic profundal sediments from a eutrophic reservoir

Abstract

There is renewed interest in the use of nitrate to treat the profundal zone of lakes to inhibit anaerobic biogeochemical processes that result in the degradation of bottom water quality (e.g., sediment phosphorus release, mercury methylation). In this study we used experimental sediment-water interface chambers to quantify the rate of sediment nitrate uptake (SNU) in profundal sediments from Lake Perris, a eutrophic raw water reservoir in Southern California. Deoxygenated chamber water was spiked with nitrate, and nitrate concentration was monitored over time under quiescent conditions, followed by mixed conditions with average water velocities of 1 cm/s. Key findings included: (1) SNU decreased with decreasing nitrate concentration, (2) SNU was higher under mixed versus quiescent conditions by nearly 50%, and (3) nitrate uptake as a function of nitrate concentration followed a conventional sediment oxygen demand model in which nitrate uptake was proportional to the square root of nitrate concentration. The probable mechanism for elevated SNU under mixed conditions was an increased diffusional concentration gradient combined with a decrease in the diffusional boundary layer at the sediment-water interface, both of which enhanced the flux of nitrate from overlaying water into sediment. Managers planning to implement lake nitrate addition should account for induced nitrate demand when determining dosing rates. For example, based on our modeling efforts from this data set, SNU in Lake Perris could range by an order of magnitude, from around 12 mg N/m 2 /d under quiescent, low nitrate conditions (0.1 mg N/l) to around 120 mg N/m 2 /d under mixed, high nitrate conditions (5 mg N/l).

Effect of dissolved oxygen on nitrogen and phosphorus fluxes from lake sediments and their thresholds based on incubation using a simple and stable dissolved oxygen control method

“…Under anoxic conditions, the fluxes of NH 4 + , DIN, TDN, and SRP and the negative flux of NO 2 À + NO 3 À were larger than those under oxic conditions. In numerous studies comparing nutrient fluxes between oxic and anoxic environments, fluxes of NH 4 + and SRP and the negative flux of NO 2 À + NO 3 À increase under anoxic conditions (Moore et al 1992;Liikanen et al 2002;Haggard et al 2005;Beutel et al 2008), and the results of the present study are consistent with those findings.…”

“…This finding indicates that the NO 2 À + NO 3 À consumption potential increases rapidly when the DO concentration is below 3 mgO 2 L À1 in our study area. Denitrification, which is considered to be the main driver of NO 3 À flux and NO 2 À + NO 3 À consumption in lake sediments under anoxic conditions, is affected by the NO 3 À concentration (Mengis et al 1997;Beutel et al 2008;Kreiling et al 2011). The results of the present study are similar to those of previous investigations.…”

Summer nitrate uptake and denitrification in an upper Mississippi River backwater lake: the role of rooted aquatic vegetation

“…Plants tend to assimilate more nutrients than needed when excess is available (Cronk and Fennessy 2001), and uptake by the sediment microbial community escalates at higher NO 3 -concentrations (Beutel et al 2008). However, epiphyton uptake did not rise with increasing NO 3 -.…”

Nutrient and heavy metal storage and mobility within sediments in Kouris Reservoir, Cyprus

“…Hypolimnion aeration or oxygenation, and sediment and/or water treatment with aluminium sulphate, are common strategies used to combat phosphorus releases from the lake bottom sediments (Beutel et al . ).…”

“…After the onset of thermal stratification, the conditions in the hypolimnion gradually become anaerobic, providing the chemically reducing environment for the phosphorus to be released from the sediment back into the water column, thereby enhancing the growth of microbial communities (Qiu et al 2017). Hypolimnion aeration or oxygenation, and sediment and/or water treatment with aluminium sulphate, are common strategies used to combat phosphorus releases from the lake bottom sediments (Beutel et al 2008).…”