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Figure 4. Relationship between DOC concentration and absorbance at 280 nm (A209 nm) it porewaters from GB30. Dotted lines indicate 99% confidence intervals.

Figure 4 Relationship between DOC concentration and absorbance at 280 nm (A209 nm) it porewaters from GB30. Dotted lines indicate 99% confidence intervals.

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Sediment cores were collected from Lake Michigan’s Green Bay at Station 30 (44°55’62”’N, 87°27'96”W), northwest of Sturgeon Bay, WI, USA (Figure 1), at a depth of 27 m using a gravity corer designed to collect three cores simulta- neously. Upon retrieval of the coring device, the core liners (67 mm i.d.) were removed and sealed at both ends. Within 4 h of collection, the sediment cores were transferred to a whole-core squeezer with a hydraulic extruder. The squeezer design, similar to the one developed by Jahnke (1988), incorporates a fixed top piston and a movable bottom piston. The squeezer was constructed from acrylic tubing (67 mm i.d.) and has sampling ports at various positions Figure 1. Location of Green Bay Station 30.
Sediment cores were collected from Lake Michigan’s Green Bay at Station 30 (44°55’62”’N, 87°27'96”W), northwest of Sturgeon Bay, WI, USA (Figure 1), at a depth of 27 m using a gravity corer designed to collect three cores simulta- neously. Upon retrieval of the coring device, the core liners (67 mm i.d.) were removed and sealed at both ends. Within 4 h of collection, the sediment cores were transferred to a whole-core squeezer with a hydraulic extruder. The squeezer design, similar to the one developed by Jahnke (1988), incorporates a fixed top piston and a movable bottom piston. The squeezer was constructed from acrylic tubing (67 mm i.d.) and has sampling ports at various positions Figure 1. Location of Green Bay Station 30.
Figure 2. Profiles of dissolved Fe" and DOC in porewater as a function of sediment depth. The vertical profile of porewater dissolved Fe"! (Figure 2) exhibited increasing Fe" concentrations from 3.6 uM near the sediment-water interface to 163 uM
Figure 2. Profiles of dissolved Fe" and DOC in porewater as a function of sediment depth. The vertical profile of porewater dissolved Fe"! (Figure 2) exhibited increasing Fe" concentrations from 3.6 uM near the sediment-water interface to 163 uM
Figure 3. Profiles of porewater absorbance at 280 nm (A209 pm) and molar absorptivity at 280 nm (€2g0 nm) as a function of sediment depth.
Figure 3. Profiles of porewater absorbance at 280 nm (A209 pm) and molar absorptivity at 280 nm (€2g0 nm) as a function of sediment depth.
Figure 5. HPSEC chromatograms of porewaters collected at depths of 1, 11, and 30 cm in core GB30.
Figure 5. HPSEC chromatograms of porewaters collected at depths of 1, 11, and 30 cm in core GB30.
Figure 6. Profiles of porewater DOC molecular weight and polydispersity as a function of sedi- ment depth.
Figure 6. Profiles of porewater DOC molecular weight and polydispersity as a function of sedi- ment depth.
Figure 7. Relationship between weight-average molecular weight and molar absorptivity at 280 nm (€2g0 nm). Solid line indicates regression of data from Chin et al. (1994). Dotted lines indicate 99% confidence intervals.
Figure 7. Relationship between weight-average molecular weight and molar absorptivity at 280 nm (€2g0 nm). Solid line indicates regression of data from Chin et al. (1994). Dotted lines indicate 99% confidence intervals.
Related topics:
GeochemistryChemistryBiogeochemistryEnvironmental ChemistryDissolved Organic CarbonSediment-Water InterfaceBiogeochemical Cycle
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