... Soil color, texture, of a backfilled, low-relief, broad swale that was eroded into redoximorp... more ... Soil color, texture, of a backfilled, low-relief, broad swale that was eroded into redoximorphic features, and horizon boundaries were re-... mette Formation. crease in the mica component, which coincides with The third stratigraphic unit consists of olive brown ...
Soil Science Society of America Journal - SSSAJ, 2004
redoximorphic features is important for a clear under- standing of reductimorphic processes. The ... more redoximorphic features is important for a clear under- standing of reductimorphic processes. The Jackson-Frazier wetland is a rare, relatively undisturbed wet- The Jackson-Frazier wetland is a rare, relatively un- land in the Willamette Valley of Oregon that experiences repetitive disturbed wetland in the Willamette Valley of Oregon annual flooding and drying cycles. Redoximorphic features formed that experiences repetitive annual flooding and drying by these wetting and drying cycles have not been calibrated with cycles and serves as a model for natural wetland condi- saturation and reduction. Long-term measurements of soil saturation and soil redox potential (EH) were combined with measurements tions in the area. The development of hydric soils in of Fe and Mn concentrations to understand the formation of these the wetland is driven by the annual flooding, prolonged redoximorphic features in the wetland soils. The Jackson-Frazier wet- periods of soil saturation, abundant organic carbon, and land is underlain by three stratigraphic units that control its hydrology: mild temperatures that facilitate reductive dissolution Holocene alluvium (A and Bss horizons), Malpass clay (2Bt horizon), and segregation of Fe and Mn into redoximorphic con- and Irish Bend silts (3BC horizon). All three units are saturated for centrations and/or depletions (Somera, 1967; Cogger up to 9 mo each year, leading to EH values that fall below the Fe re- and Kennedy, 1992; Lovely, 1993; Miller et al., 1993; Ve- duction threshold. Extractable Fe and Mn in nodules, concretions, praskas, 1994). Three distinct stratigraphic units within and soft masses document substantial depletions from the matrix soil the Jackson-Frazier wetland all contain Fe-Mn concen- in all three units. In the 3BC, diffuse halos of Fe accumulation and trations in the form of macroscopic concretions and matrix chromas from two to four indicate a source of Fe that can be nodules (Stewart, 1997). Similar concentrations were reduced, translocated, and concentrated in nodular form. In the Bss identified as early as 1940 by Drosdoff and Nikiforoff and 3BC horizons, soft masses surrounding concentrations and higher ratios of oxalate to dithionite-citrate-bicarbonate Fe (FeOx/FeDCB )i n the (1940), and more recent work by Somera (1967) and larger concentrations suggest that nodules and concretions are cur- Seter and Baham (1994) has shown that the greatest rently forming by accretion of Fe. In the 2Bt, virtually all of the Fe amount of nodules occur in the wettest (poorly drained) and Mn is gone from the matrix, and concretion boundaries are sharp. soils of the hydrosequences they studied. These are not relict features, as the current conditions would favor We have previously described the hydrology of the continued formation had the supply of Fe and Mn not been exhausted. wetland in relation to its stratigraphy (D'Amore et al., 2000). In this paper we show how saturation and reduc- tion patterns influence the development of Fe-Mn con-
... Jason B. Fellman a , Corresponding Author Contact Information , E-mail The Corresponding Auth... more ... Jason B. Fellman a , Corresponding Author Contact Information , E-mail The Corresponding Author , Robert GM Spencer b , 1 , Peter J. Hernes b , Rick T. Edwards c , David V. D'Amore c and ... c Pacific Northwest Research Station, USDA Forest Service, Juneau, AK 99801, USA. ...
... Soil color, texture, of a backfilled, low-relief, broad swale that was eroded into redoximorp... more ... Soil color, texture, of a backfilled, low-relief, broad swale that was eroded into redoximorphic features, and horizon boundaries were re-... mette Formation. crease in the mica component, which coincides with The third stratigraphic unit consists of olive brown ...
Soil Science Society of America Journal - SSSAJ, 2004
redoximorphic features is important for a clear under- standing of reductimorphic processes. The ... more redoximorphic features is important for a clear under- standing of reductimorphic processes. The Jackson-Frazier wetland is a rare, relatively undisturbed wet- The Jackson-Frazier wetland is a rare, relatively un- land in the Willamette Valley of Oregon that experiences repetitive disturbed wetland in the Willamette Valley of Oregon annual flooding and drying cycles. Redoximorphic features formed that experiences repetitive annual flooding and drying by these wetting and drying cycles have not been calibrated with cycles and serves as a model for natural wetland condi- saturation and reduction. Long-term measurements of soil saturation and soil redox potential (EH) were combined with measurements tions in the area. The development of hydric soils in of Fe and Mn concentrations to understand the formation of these the wetland is driven by the annual flooding, prolonged redoximorphic features in the wetland soils. The Jackson-Frazier wet- periods of soil saturation, abundant organic carbon, and land is underlain by three stratigraphic units that control its hydrology: mild temperatures that facilitate reductive dissolution Holocene alluvium (A and Bss horizons), Malpass clay (2Bt horizon), and segregation of Fe and Mn into redoximorphic con- and Irish Bend silts (3BC horizon). All three units are saturated for centrations and/or depletions (Somera, 1967; Cogger up to 9 mo each year, leading to EH values that fall below the Fe re- and Kennedy, 1992; Lovely, 1993; Miller et al., 1993; Ve- duction threshold. Extractable Fe and Mn in nodules, concretions, praskas, 1994). Three distinct stratigraphic units within and soft masses document substantial depletions from the matrix soil the Jackson-Frazier wetland all contain Fe-Mn concen- in all three units. In the 3BC, diffuse halos of Fe accumulation and trations in the form of macroscopic concretions and matrix chromas from two to four indicate a source of Fe that can be nodules (Stewart, 1997). Similar concentrations were reduced, translocated, and concentrated in nodular form. In the Bss identified as early as 1940 by Drosdoff and Nikiforoff and 3BC horizons, soft masses surrounding concentrations and higher ratios of oxalate to dithionite-citrate-bicarbonate Fe (FeOx/FeDCB )i n the (1940), and more recent work by Somera (1967) and larger concentrations suggest that nodules and concretions are cur- Seter and Baham (1994) has shown that the greatest rently forming by accretion of Fe. In the 2Bt, virtually all of the Fe amount of nodules occur in the wettest (poorly drained) and Mn is gone from the matrix, and concretion boundaries are sharp. soils of the hydrosequences they studied. These are not relict features, as the current conditions would favor We have previously described the hydrology of the continued formation had the supply of Fe and Mn not been exhausted. wetland in relation to its stratigraphy (D'Amore et al., 2000). In this paper we show how saturation and reduc- tion patterns influence the development of Fe-Mn con-
... Jason B. Fellman a , Corresponding Author Contact Information , E-mail The Corresponding Auth... more ... Jason B. Fellman a , Corresponding Author Contact Information , E-mail The Corresponding Author , Robert GM Spencer b , 1 , Peter J. Hernes b , Rick T. Edwards c , David V. D'Amore c and ... c Pacific Northwest Research Station, USDA Forest Service, Juneau, AK 99801, USA. ...
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