Future Direction of Study

How is lignin transported or retained in soil? What are the main forms of degradation forcomplex organic compounds like lignin in the soil? These questions will be answered by

combining soil column and batch sorption studies with the profile work demonstrated above. Itis known that sorptive processes remove acids before aldehydes, and cinnamyl and syringylbefore vannillyl phenols (Robinson & Hernes, unpublished) – future studies aim to refine theeffects of these processes on the composition of the dissolved phase. The composition of

phenols in groundwater, particularly the •13C, should vary reflecting the types of crops (C3 orC4) at the surface or in the cattle feed. Future studies will help refine this effect in groundwater.

Works CitedHarter, T., Davis, H., Mathews, M.C., Meyer, R.D, 2002. Shallow groundwater quality on dairy farms with irrigated forage crops. Journal of Contaminant Hydrology, v. 55 p. 287-315. Kolodziej, E.P., Harter, T., Sedlak, D.L. (in press). Dairy wastewater, aquaculture, and spawning fish as sources of steroid hormones in the aquatic environment. Environmental Science and Technology.Hedges, J.I., Parker, P.L.., 1976. Land-derived organic matter in surface sediments from the Gulf of Mexico. Geochimica et Cosmochimica Acta, v. 40 p. 1019-1029. Hernes, P.J., Benner, R., 2003. Photochemical and microbial degradation of dissolved lignin phenols: Implications for the fate of terrigenous dissolved organic matter in marine environments. Journal of Geophysical Research – Oceans, v. 108 (C9) Article No. 3291. Hedges, J.I., Mann, D.C., 1979. The characterization of plant tissues by their lignin oxidation products. Geochimica et Cosmochimica Acta, v. 43 p. 1803-1807. Hedges,J.I., Ertel, J.R., 1982. Characterization of lignin by gas capillary chromatography of cupric oxide oxidation products. Analytical Chemistry, v. 54 no. 2 p. 174-178. Hedges, J. I., Blanchette, R.A., Weliky, K., Devol, A.H., 1988. Effects of fungal degradation on the CuO oxidation products of lignin: A controlled laboratory study. Geochimica et Cosmochimica Acta, v. 52 p. 2717–2726. Opsahl, S., Benner, R., 1997. Distribution and cycling of terrigenous dissolved organic matter in the ocean. Nature, v. 386 p. 480– 482. Opsahl, S., Benner, R., 1998. Photochemical reactivity of dissolved lignin in river and ocean waters. Limnology and Oceanography, v. 43 p. 1297– 1304. Meyers, P.A., Ishiwatari, R., 1993. Lacustrine organic geochemistry – an overview of indicators of organic matter and digenesis in lake sediments. Organic Geochemistry, v. 20 no. 7 p. 867-900.

Lignin in the Groundwater

In the literature, the average carbon-normalized yield of lignin phenols (•g/100mg OC => •) in rivers is 1,500•; inoceans, 7•; in woody tissues 15,000•; and in leaves and needles 5,340 •. Groundwater in this site ranges from 90-

530•, with total phenols ranging from 10-430 ppb (rivers range from 10-50ppb in the literature, while oceans aresignificantly lower).

As cattle digestive processes preferentially degrade organic compounds other than lignin, lignin becomes concentrated inthe liquid manure directly impacting corral areas and collected in settling ponds. In effect, lignins concentration is high in

the regional groundwater compared to locations where leaching is the dominant process contributing lignin togroundwater.

Dissolved Lignin

Organic Carbon Trends &Background

Background levels in the areaare 0-6ppm. Dissolved OC

ranges from 6-75ppm in thegroundwater – this is

comparable to riverine levels inliterature. DOC is present at

levels >400ppm in the settlingponds.

Most wells appear to haveincreased OC content over time.As expected, wells near ponds

and corrals have the highest OCcontent.

Tile drains, which incorporategroundwater over ~1 sq. mile,are higher in OC than manured

field wells.

Dissolved Organic Carbon (DOC)

Dissolved Organic Carbon Content by Location Over 4 Time Steps

0.1

1

10

100

20 5 6 8 12 15 1 11 13 14 7 19 10 9 21 16

Well Number Corresponding to Map

Org

anic

Car

bon

Con

tent

, m

g/L

May-03

Mar-05

Jun-05Sep-05

Averages by well type over 5 time steps

0.1

1

10

100

ControlWell

ManuredField Well

Corral Well Pond Well Tile Drain

Org

anic

Car

bon

mg/

L

May-03Mar-05Jun-05Sep-05

Averages by well type over 4 time steps

9/4/20056/7/20053/7-8/2005

5/29/03

0.1

1

10

100O

rgan

ic C

arbo

n m

g/L

CorralManured FieldPondTile DrainControl Well

Corral Buildings

Ponds

Orchards

Dry Manure Fields

Liquid ManureFields

No Manure Fields

RegionalGroundwater FlowDirection

Canal

5

9

6

7

1

15

14

11

13

10

12

8

Corral Well

Pond Well

Tile Drain

Manured FieldWell

CorralsThe Goal• Test a carbon biomarker for its applicability in groundwater

• Increase understanding of subsurface movement of dissolved lignin, an importantgeochemical tracer

Large dairy operations in California’s low-relief basins generate a great deal of liquidmanure. Reapplication of manure to forage crops is common. The potential impact of this

practice on shallow groundwater quality in the area has been studied with respect tonitrates, steroids, and salinity (Harter et. al., 2002, Kolodziej et. al. (in press)). This studyaims to quantify, characterize, and trace DOC through various operations and into the

groundwater, with an eye on transformations and sequestration occurring in thesubsurface.

Why Lignin?

• Lignin is a geochemically invaluable tracer due to fourimportant qualities:

1) it is quantitatively significant in vascular plant organicmatter (OM) and a unique marker for vascular plant OM in

aquatic systems,

2) lignin is inherently degradation resistant and thereforelikely to persist on longer time scales,

3) compositional characteristics can be linked to importantsource information, and

4) lignin composition also can record diagenetic processing.

Previous Studies

Previous studies on the same dairy have foundelevated levels of nitrogen and electrical

conductivity (EC) (Harter et. al., 2002). Nitrogenlevels were consistent across the site. EC was

elevated in corral and pond areas, indicating theleaching of salts. A second study found that the

level of steroid hormones in groundwater affectedby dairy wastewater was elevated, but significantlyreduced from their levels within the waste ponds

(Kolodziej et. al., 2004).

The Site

• Shallow water table (10-30 feet)

• Each well reflects a small specific area

•Well waters reflect specific land uses

The site selected for this study is typical of dairiesin the San Joaquin Valley of California. The dairy

has several land uses, including the corrals wherecattle are present, settling ponds for liquid manurestorage, and fields where forage crops are grownyear-round. All of these site types were sampled.

The surrounding region is similar, with someorchards. The water table is shallow, twenty-fivefeet or less beneath the surface in mid-summer.Groundwater is pumped to maintain the watertable beneath the area and removed to canals.

The Plan

•Gather groundwater samplesthat represent multiple land

uses

• Analyze the phenoliccomposition of lignin present in

groundwater

• Correlate the phenolicsignature of groundwater to land

uses

Methods

Sampling: Samples are taken from 1-2” monitoring wells across the site and immediatelyfiltered at 0.45 •m to remove particulate organic matter and microorganisms Duplicates are

taken at each well for the following analyses.

DOC analysis: Dissolved organic carbon is analyzed by combustion on a Shimadzu TOC-Vsh.

Lignin analysis: Aqueous samples are dried, ground to homogenous texture, reconstitutedin pH ~2 solution and filtered twice through a C-18 cartridge. Organic matter retained on thecartridge is eluted with methanol, dried, and lignin is deconstructed to component phenolsby CuO oxidation and derivitization (Hedges & Ertel, 1982). Concentration of the phenols is

determined by gas chromatography (GC).

Structures of the 8 component phenols as derived from cupric oxideoxidation.

Adapted from Meyers & Ishiwatari, 1993.

Patterns in lignin

The composition of the lignin in these samples(graphs at far left) reflects the source

composition of angiosperms and nonwoodygymnosperms (compare to graphs at left).

Acid to aldehyde ratios of vannillyl andsyringyl phenols reflect the degree of ligninoxidation. These ratios have been shown to

increase with oxidation and microbialdegradation (Hedges et al., 1988; Hernes &

Benner 2003, Opsahl & Benner, 1997, 1998).

The data at right suggest that lignin in thecorral wells is more highly degraded than in

the manured wells, and that pond wellscontain the least degraded lignin in the

dissolved fraction. This suggests that thecontribution of fresh organic matter from cropsis an important factor in the fields, and that the

degradation of lignin occurs more quicklyduring transport through the oxic vadose zone

(beneath corrals) than in the transition fromholding ponds to groundwater (presumably a

more anoxic transition).

G: Gymnosperm Woodsg: Nonwoody Gymnosperm

A: Angiosperm Woodsa: Nonwoody Angiosperm

Gymnosperms are nonflowering plants, includingconifers. Angiosperms are flowering plants including

hardwood trees, herbs, and grasses.Adapted from Hedges & Mann, 1979.

Acid (Ad) to Aldehyde (Al) ratios of Vanillyl vs. Syringyl Phenols

Data collected March 2005

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5(Ad/Al)s

(Ad/

Al)v

Corral Wells

Manured Field Wells

Pond Wells

Increase d oxidation and microbial degradation increases ra tios

Syringyl vs. Cinnamyl Phenols Data Collected March 2005

0

1

2

3

4

5

6

7

8

-0.1 0.4 0.9 1.4 1.9 2.4 2.9

Cinnamyl Phenols (ug/100mg OC)

Syri

ngyl

Phe

nols

(ug/

100m

g O

C)

Corral Wells

Manured FieldWellsPond Wells

Syringyl/Vanillyl vs. Cinnamyl/Vanillyl

Data Collected March 2005

0

0.5

1

1.5

2

2.5

3

0 1 2 3 4C/V

S/V

Corral Wells

Manured FieldWells

Pond Wells

Cinnamyl vs. Vannilyl Phenols Data Collected March 2005

-0.1

0.4

0.9

1.4

1.9

2.4

2.9

0 5 10 15

Vannil yl Phenols (ug/100mg OC)

Cin

nam

l Phe

nols

(ug/

100m

g O

C)

Corral Wells

ManuredField WellsPond Wells

Syringyl vs. Vannilyl Phenols Data Collected March 2005

0

1

2

3

4

5

6

7

8

0 5 10 15

Vanni lyl Phenol s (ug/10 0mg OC)

Syri

ngyl

Phe

nols

(ug/

100m

g O

C)

Corral Wells

ManuredField WellsPond Wells

Tracing Dissolved Organic Carbon in Groundwater Using LigninJill C. Schlanser, Peter J. Hernes, Thomas Harter at The University of California, Davis

Interpreting Origins of a Sample From Lignin