Hydrologic Linkages to Subsurface Carbon Sequestration in Florida Acknowledgments: Personnel who contributed to the Florida Soil Survey Program. UF Soil.
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Hydrologic Linkages to Subsurface Carbon
Sequestration in Florida
Acknowledgments:
Personnel who contributed to the Florida Soil Survey Program.
UF Soil and Water Science faculty and students.
Florida soil scientists.
Funding from USDA-NRCS and McIntire-Stennis
Publications related to topicHarris, W.G. 2001. Hydrologically-linked Spodosol formation in the Southeastern United States . p. 331-342. In J.L. Richardson and M.J. Vepraskas (eds.) Wetland soils: their genesis, hydrology, landscape, and separation into hydric and nonhydric soils. CRC Press, Boca Raton, FL.
Schaetzl, R., and W.G. Harris. 2011. Spodosols. p. 33-113 to 33-127. In: Handbook of Soil Science, 2nd ed. P.M. Huang, Y. Li and M.E. Sumner (eds.). CRC Press, New York.
Harris, W.G., and V.W. Carlisle. 1987. Clay mineralogical relationships in Florida Haplaquods. Soil Sci. Soc. Am. J. 51:481-484.
Harris, W.G., V.W. Carlisle, and K.C.J. Van Rees. 1987. Pedon zonation of hydroxy-interlayered minerals in Ultic Haplaquods. Soil Sci. Soc. Am. J. 51:1367-1372.
Harris, W.G., V.W. Carlisle, and S.L. Chesser. 1987. Clay mineralogy as related to morphology of Florida soils with sandy epipedons. Soil Sci. Soc. Am. J. 51:1673-1677.
Stone, E.L., W.G. Harris, R.B. Brown, and R.J. Kuehl. 1993. Carbon storage in Florida Spodosols. Soil Sci. Soc. Am. J. 57:179-182.
Harris, W.G., S.H. Crownover, and N.B. Comerford. 1995. Experimental formation of Aquod-like features in sandy coastal plain soils. Soil Sci. Soc. Am. J. 59:877-886.
Tan, Z., W.G. Harris, and R.S. Mansell. 1999. Watertable dynamics across an Aquod-Udult transition in Florida flatwoods. Soil Sci. 164:10-17.
Harris, W.G., and K.A. Hollien. 1999. Changes in quantity and composition of crystalline clay across E - Bh boundaries of Alaquods. Soil Sci. 164:602-608.Harris, W.G., and K.A. Hollien. 2000. Changes across artificial E - Bh boundaries generated under simulated fluctuating water tables. Soil Sci. Soc. Am. J. 64:967-973.
Harris, W.G., S.H. Crownover, and J. Hinchee. 2005. Problems arising from fixed-depth assessment of deeply-weathered sandy soils. Geoderma 126:161-165.
Harris, W.G., and C.A. Rischar. 2012. Factors related to Bh horizon depth for artificial and natural E- Bh sequences. Geoderma 189-190:502-507.
Other collaboratorsKafui Awuma, Scarlett Balboa, Chumki Banik, Rex Ellis, Sabine Grunwald, Wade Hurt, Brent Myers, Travis Richardson, Aja Stoppe
Coauthors
Color guide for doubt level
• Observations and data – require faith, but retain some doubt
• Ideas and inferences – require doubt, but retain some faith
Focus on one form of “deep C”
• Podzolization - pedogenic translocation & joint accumulation of C & metals:
– Eluviation – • loss
– Illuviation –• gain
• Podzolization => subsurface C sequestration
A
E
Bh
SHWT
Other pertinent terms
• Spodic* horizon – meets threshold podzolic C & metal accumulation
• Spodosol – soil order with Spodic horizon within 2-m depth
* Most Bh horizons in Florida meet Spodic criteria
Spodosol distribution worldwide
Commonly well drained
Mainly restricted toimperfectly-drained sites
What is the role of the water table in fostering Spodosol formation in Florida?
Randy Schaetzl
Dupont heavy mineral mine exposure – NE FloridaA huge C pool
>2m
Estimated 431 Tg C in Florida Bh horizons within 2 m
Deep, thick C pool mass not estimated
Potential C gain or loss tied to climate and sea level
How does this C accumulate?Earl Stone, Randy Brown, Ron Kuehl
Chelate-complex theory
Ex - Low molecular weight
Ex – Fulvic acid
Ex – Humic acid
Al & Fe
Negatively-charged OM
“Clouds” of hydrated counterions
Dispersion
Flocculation & immobilization
E
Bh
Complexation & mobilization
Line of Scrimmage
Soil Surface
Buchholtz
Eastside
Gainesville
P.K. Young
Oak Hall
C
Al
Theory – Gainesville style
Line of Scrimmage
Soil Surface
C
Al
Line of Scrimmage
Soil Surface
C
Al
Line of Scrimmage
Soil Surface
C & Al
Al
Line of Scrimmage
Soil Surface
C & Al
Al
Uuughh!
Soil Surface
E
A
Bh
… and so it is with Spodosols …- but clay moves too, not just metals?
C & Al
Al & C
Keith Hollien,Soil Survey Data
“Sandhills” – deep water table “Flatwoods” – shallow water table
Coated sand
Clean sand
Coatings
• About 2-8 % of soil mass• Similar proportions of silt & clay• Silt – mostly quartz• Clay – quartz, phyllosilicates, gibbsite, & oxides of Al & Fe• NOT predominantly “iron oxide coatings”, although …• Al- & Fe oxides serve as “cement”
Characteristics of Sand Grain Coatings
Shannon Chesser, Vic Carlisle
Sandhill summit
Edge of Spodosol
Oxalic acid stripped
sand
Oxalic acid had no effect
Landscape observations
“Toeslope”
Nick Comerford, Stan Crownover, Keith Hollien
Sandhill summit
Edge of Spodosol
Coated sand;
chroma ≥ 6
Coated sand;
chroma < 6
Landscape observations (cont.)
“Toeslope”
Inference: color gradient and acid vulnerability related to redox depletion of Fe
Sandhill summit
Higher “free” Fe
Lower “free” Fe
Landscape observations (cont.)
Hypothesis: Toeslope sand is predisposed to form Spodosol
“Toeslope”
Edge of Spodosol
Recipe for a Frankenstein “Spodosol”
• Predisposed coated sand
• Complexing organic acid
• Fluctuating water table (22 h & 2 h drained)
• A few weeks
• That’s it!
“E”
“Bh”
Metals & C depleted
Metals & C enriched
Notes:
• No “Spodosol” formed with free drainage
• Bh formation => less metals in leachate
• E thickness related to metal & clay content of original soil:
R² = 0.65
p < 0.001
0
2
4
6
8
10
12
14
16
18
20
0 10 20 30 40 50
Med
ian
"E
" T
hic
knes
s (c
m)
AAO Fe+Al (mM kg-1)
R² = 0.50
p = 0.007
0
2
4
6
8
10
12
14
16
18
20
0.0 1.0 2.0 3.0 4.0
Med
ian
"E"
Th
ickn
ess
(cm
)
Clay (%)
Chad Rischar
Right now, you’re probably asking yourself …
here & here?
… what happens between …
“Sandhills” “Flatwoods”AA
This happens
Kafui Awuma, Scarlett Balboa, Chumki Banik, Vic Carlisle, Rex Ellis, Wade Hurt, Travis Richardson, Zhengxi Tan, Bob Mansell
Sand grain coatings are again clues …
Ideas• Process requires a threshold duration of near-surface saturation
• Organic acids “chip away” at Al with each threshold event
• E & Bh expression increases with increasing frequency of threshold
• Self-defeating - proceeds to maximum expression
AA
Zhengxi Tan, Bob Mansell
Ideas (cont.)fr
equ
ency
of
thre
sho
ld
E thickness
Ideas (cont.)fr
equ
ency
of
thre
sho
ld
E thickness
Distance
Why is a fluctuating water table required? 1. Metal sources for Bh - metal oxides – stable on well-drained
landscapes
2. Redox partially depletes Fe on poorly drained uplands (“flatwoods”)
3. Al => less crystalline & more vulnerable to organic complexation
4. Al oxides destabilized upon reaching thresholds in frequency & duration of saturation whereby• Organic acid activities increase (e.g., microbial degradation rates ↓)• Vertical water flow decreases (favoring kinetics)
5. Al oxide dissolution releases all coating components
6. C moves Al, but Al eventually stops C within finer matrix of colloidal origin
Concluding Ideas
Concluding thought: What happens to C with climate change or artificial drainage?
Nick Comerford, Sabine Grunwald, Aja Stoppe, Brent Myers
In memory of two people who enriched my life
Dr. Earl StoneDr. Vic Carlisle
Thanks! Questions?
• Jeff Locuta’s image – Pedology 2012
Soil of a thousand faces …
Louis Mantini Oren Reedy?
Thanks!Questions?
Data that do NOT support presumptions of Bh being a “hardpan”
Means of selected data for Bh, Bh1, Bh2, and Bh3 horizons sampled during the Florida Soil Survey Program
SaturatedHydraulic
Conductivitycm/h
BulkDensityg/cm-3
OrganicCarbon
%Clay
%
Non-Ortstein(vfr or fr)
14.10n=440
1.50n=440
1.38n=466
3.50n=466
Ortstein(vfi or fi)
8.05n=43
1.51n=42
2.59n=43
5.71 n=43
Bh and Bt horizons as “hardpans”
Myakka Very friableMany fine & medium roots
Leon Firm to friableMany fine & medium roots
Immokalee Friable to looseCommon fine & medium roots
Wabasso friable
Common fine & medium roots
Bh horizon consistence & roots as described on OSDs of Alaquods of large extent
Data that do NOT support presumptions of Bh being a “hardpan”
Outline of talk• Introduction
– Pertinent terms– Perspective on deep organic C distribution– Environmental relevance of deep C– Extant theories that don’t address hydrology
• Florida observations• Experimental data• Field study data• Proposed mechanisms of hydrologic linkages
Drowned coastal Bh horizons ( Phillips & Ellis)
Evidence of sea level rise
Spodosol distribution Florida
Figure ???. Average C mineralized (g C per g SOC) over time for A- and Bh horizons from 155 Florida Spodosol Profiles.
Morphological & mineralogicalevidence of coating redistribution Clean
Coated
Coated
• Aquod to Psamment sequence moving up from the shore of a sandhill lake
• About a 10-m transect
… but why is a fluctuating water table required?
Florida Soil Survey Program data suggesting Bh is clay-enriched, too
Lake, etc. Candler, etc. St. Lucie, etc.
“Coated” “Uncoated” “Uncoated”
Has Fe & Al Has Fe & Al No Fe & AlSome P retention Some P retention No P retention
Grains un-strippedGrains un-stripped Grains stripped
Family “Coated” – “Uncoated” distinction
Coated vs. Clean Sand Grains (cont.)
Coated
Clean
Clean
Coated
Coated
Lakeland Myakka St. Lucie
… in Panhandle &N. Central Florida… no matter howdeep or thick
Coated = high HIVin clay
Clean = high quartz,
maybe smectitein clay
Sand
Sand
Layers1
2
3
Duette
St. Lucie
AA
CE
Bh
Bunk! That’s no Bh Oh, yeah!
Come over here and say
that!
Heavy mineral mining dredge macerates Bh …
Opening Pandora’s Box
… releasing C at large scale
• Varshovi & Sartain• McLean,Shober, & Ellis
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