We examined trends in the movement and source of water in a headwater wetland in North Shropshire, UK. Six piezometer nests along two transects were monitored over an 18 month period, and flownets were derived to estimate the rate and direction of water movement through the wetland and the interaction between precipitation and groundwater discharge. Individual water sources are identified using stable isotopes and seasonal differences in the composition of wetland soil-water are described. Variations in dissolved inorganic and organic carbon (DIC and DOC) were measured in water samples collected from discrete points in the wetland and the adjacent river and were interpreted using the hydrological data. The results suggest that end-members for DOC and DIC can be identified across the range of sampling sites: a groundwater spring (GS) had the lowest DOC and high DIC (DOC = 5.6 +/- 4.5 mg/l; DIC = 36.7 +/- 4.6 mg/l); a shallow well (WS) had the highest DOC and DIC (DOC = 32.5 +/- 18.7 mg/l; DIC = 61.9 +/- 18.9 mg/l); while surface-water (WSW) had the lowest DIC (20.6 +/- 12.1 mg/l). Water fluxes between the wetland and river are estimated using the Dupuit-Forcheimer approximation to highlight the degree to which some headwater wetlands may act as a carbon source to ecosystems downstream. These wetlands are potentially a significant pool of C but are particularly sensitive to future changes in groundwater levels.
|Publication status||Published - 1 Jan 2006|
- flux estimates
- delta D
- delta O-18