Browsing by Author "Winton, RS"

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Open Access
A cost-effective method for reducing soil disturbance-induced errors in static chamber measurement of wetland methane emissions
(Wetlands Ecology and Management, 2016-08-01) Winton, RS; Richardson, CJ
© 2015, Springer Science+Business Media Dordrecht. Static chambers used for sampling methane (CH 4 ) in wetlands are highly sensitive to soil disturbance. Temporary compression around chambers during sampling can inflate the initial chamber CH 4 headspace concentration and/or lead to generation of non-linear, unreliable flux estimates that must be discarded. In this study, we tested an often-used rubber gasket (RG)-sealed static chamber against a water-filled gutter (WFG) seal design that could be set up and sampled from a distance of 2 m with a newly designed remote rod sampling system to reduce soil disturbance. Compared to conventional RG design, our remotely sampled static chambers reduced the chance of detecting inflated initial CH 4 concentrations ( > 3.6 ppm) from 66 to 6 % and nearly doubled the proportion of robust linear regressions (r 2 > 0.9) from 45 to 86 %. Importantly, the remote rod sampling system allows for more accurate and reliable CH 4 sampling without costly boardwalk construction. This paper presents results demonstrating that the remote rod sampling system combined with WFG static chambers improves CH 4 data reliability by reducing initial gas measurement variability due to chamber disturbance when tested on a mineral soil-restored wetland in Charles City County, Virginia, USA.
Open Access
Erratum to: The Effects of Organic Matter Amendments on Greenhouse Gas Emissions from a Mitigation Wetland in Virginia’s Coastal Plain [Wetlands, DOI 10.1007/s13157-015-0674-y]
(Wetlands, 2015-10-14) Winton, RS; Richardson, CJ
Open Access
The Effects of Organic Matter Amendments on Greenhouse Gas Emissions from a Mitigation Wetland in Virginia’s Coastal Plain
(Wetlands, 2015-10-14) Winton, RS; Richardson, CJ
© 2015, Society of Wetland Scientists. There is concern that widespread restoration and/or creation of freshwater wetlands may present a radiative forcing hazard because of the potential for methane (CH 4 ) emissions. Yet data on greenhouse gas (GHG) emissions from restored wetlands are sparse and there has been little investigation into the GHG effects of amending wetland soils with organic matter (OM), a practice used to improve function of mitigation wetlands in the Eastern United States. In this study we measure GHG emissions across an OM gradient at the Charles City Wetland (CCW) in Charles City County, Virginia. We found soils heavily loaded with OM emit significantly more CO 2 than those that have received little or no OM. CH 4 emissions from CCW are low compared to reference wetlands and show no relationship with the loading rate of added OM or total soil carbon. We conclude that adding moderate amounts ( < ~150 kg m −2 ) of OM to the CCW does not greatly increase GHG emissions, while the addition of high amounts of OM produces additional CO 2 , but not CH 4 . CH 4 flux is highest under flooded conditions during warmer months but it still a modest contribution to global warming potential compared to soil CO 2 flux.
Open Access
Waterfowl Impoundments as Sources of Nitrogen Pollution
(Water, Air, and Soil Pollution, 2016-10-01) Winton, RS; Moorman, M; Richardson, CJ
© 2016, Springer International Publishing Switzerland. Hydrologically controlled moist-soil impoundment wetlands provide critical habitat for high densities of migratory bird populations. Nutrients exported from heavily used impoundments by prescribed seasonal drawdown of surface water may contribute to the eutrophication of aquatic ecosystems. To investigate the relative importance of nutrient export from managed impoundment habitats, we conducted a field study at Mattamuskeet National Wildlife Refuge in North Carolina, USA, which contains 1545 ha of impoundments that drain into hypereutrophic Lake Mattamuskeet. We found that prescribed hydrologic drawdowns of an impoundment exported roughly the same amount of nitrogen (N) as adjacent fertilized agricultural fields on a per-area basis and contributed approximately one fifth of total N load to Lake Mattamuskeet. The prescribed drawdown regime, designed to maximize waterfowl production in impoundments, may be exacerbating the degradation of habitat quality in the downstream lake as an unintended consequence. Few studies of wetland N dynamics have targeted impoundments managed to provide wildlife habitat, but a similar phenomenon may occur in some of the 36,000 ha of similarly managed moist-soil impoundments on National Wildlife Refuges in the southeastern USA, especially those hosting dense concentrations of waterfowl. We suggest an earlier seasonal drawdown could potentially mitigate impoundment N pollution and estimate it could reduce N export from our study impoundment by more than 70 %.