Redox dynamics of a tidally-influenced wetland on the San Jacinto River

LaRiviere, D.; Autenrieth, Robin L.; Bonner, James S.

doi:10.1007/bf02803382

Cited by 10 publications

(2 citation statements)

References 30 publications

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“…Our goals were to determine the importance of microbial processes in contributing to N retention and loss in salt marshes and to determine the potential effects of plant community composition on those processes. Because redox conditions are likely to be a key control on N cycling in wetlands that regularly experience redox fluctuations associated with the tides (LaRiviere et al 2004), we conducted incubations under both aerobic and anaerobic conditions to explore the redox sensitivity of the N cycling pathways.…”

Section: Introductionmentioning

confidence: 99%

Microbially mediated nitrogen retention and loss in a salt marsh soil

2015

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Abstract. Salt marshes currently play an important role as filters for upslope nitrogen (N) inputs. This could change in the future with sea level rise, warming and eutrophication, which are expected to favor monocultures over diverse plant communities. We explored patterns in gross N cycling, dissimilatory nitrate (NO 3 À ) reduction to ammonium (NH 4 þ ) (DNRA), and denitrification in a salt marsh soil under two typical redox conditions (aerobic and anaerobic), and in soils under plant communities manipulated to simulate potential future composition (forb and graminoid monocultures). Natural salt marsh soils exhibited high potential gross N mineralization rates, averaging 50.4 6 5.7 lg N g À1 d À1 under aerobic conditions; rates declined to 23.6 6 3.4 lg N g À1 d À1 under an N 2 headspace. Microbial NH 4 þ uptake and gross nitrification together accounted for only 14 % of gross N mineralization. Nitrogen retention via DNRA and microbial uptake greatly exceeded N losses via denitrification. Gross nitrification rates were greater in the forb and graminoid monocultures than in the control. This effect may be mediated by the lower plant biomass in the monocultures than in the control, which may have reduced competition between plants and nitrifiers for NH 4 þ . Soil NO 3 À concentrations and net nitrous oxide (N 2 O) fluxes were greatest for the forb monoculture, likely due to higher soil oxygen (O 2 ) concentrations in these plots. Our results suggest that salt marsh soils with a diverse plant community have high potential rates of N mineralization and microbial N retention, and the establishment of forb monocultures could lead to greater ecosystem N losses.

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Section: Introductionmentioning

confidence: 99%

Microbially mediated nitrogen retention and loss in a salt marsh soil

2015

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“…Notably, the frequency of 1−2 cycles of redox fluctuations per day induced by tidal hydrology is of great importance interrupting the ripening processes and controlling the activation efficiency. In this regard, zones with high frequency redox fluctuations (e.g., intertidal surface soils, 48 rhizosphere soils, 49 hyporheic and riparian soil-water interfaces, 50 surface soils of rain forests 51 ) could act as hot spots for RAMP formation that can induce massive ROS production, which can accelerate carbon mineralization and pollutant transformation at these localized soil interfaces where oxygen fluctuates.…”

Section: ■ Environmental Implicationsmentioning

confidence: 99%

Redox Oscillations Activate Thermodynamically Stable Iron Minerals for Enhanced Reactive Oxygen Species Production

Zhao

Tan

et al. 2023

Environ. Sci. Technol.

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Reactive oxygen species (ROS) play key roles in driving biogeochemical processes. Recent studies have revealed nonphotochemical electron transfer from redox-active substances (e.g., iron minerals) to oxygen as a new route for ROS production. Yet, naturally occurring iron minerals mainly exist in thermodynamically stable forms, restraining their potential for driving ROS production. Here, we report that tide-induced redox oscillations can activate thermodynamically stable iron minerals for enhanced ROS production. • OH production in intertidal soils (15.8 ± 0.5 μmol/m 2 ) was found to be 5.9-fold more efficient than those in supratidal soils. Moreover, incubation of supratidal soils under tidal redox fluctuations dramatically enhanced • OH production by 4.3fold. The tidal hydrology triggered redox alternation between biotic reduction and abiotic oxidation and could accelerate the production of reactive ferrous ions and amorphous ferric oxyhydroxides, making thermodynamically stable iron minerals into redoxactive metastable iron phases (RAMPs) with reduced crystallinity and promoting surface electrochemical activities. Those RAMPs displayed enhanced redox activity for ROS production. Investigations of nationwide coastal soils verified that tide-induced redox oscillations could ubiquitously activate soils for enhanced ROS production. Our study demonstrates the effective formation of RAMPs from redox oscillations by hydrological perturbations, which provides new insights into natural ROS sources.

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