The Olive Tree, Vol. 9 Number 1, 2001

The Summer 2001 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 9 Number 2 , 2001

The Winter 2001 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 8 Number 1, 2000

The Summer 2000 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 8 Number 2, 2000

The Winter 2000 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 7 Number 1, 1999

The Summer 1999 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 7 Number 2, 1999

The Winter 1999 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

Craig Brook; two fishermen bringing in their nets

Archival Collection

Eastport Crabs: Bob Humphries with crabs

http://digitalcommons.library.umaine.edu/defht_images/1002/thumbnail.jpg

The Olive Tree, Vol. 6 Number 1, 1998

The Spring 1998 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 5 Number 1, 1997

The Winter 1997 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 4 Number 1, 1996

The Winter 1996 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 3 Number 1, 1995

The Winter/Spring issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

The Olive Tree, Vol. 1 Number 1, 1992

The Summer 1992 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

Investigating Peatland Stratigraphy and Hydrogeology Using Integrated Electrical Geophysics

Hydrology has been suggested as the mechanism controlling vegetation and related surficial pore-water chemistry in large peatlands. Peatland hydrology influences the carbon dynamics within these large carbon reservoirs and will influence their response to global warming. A geophysical survey was completed in Caribou Bog, a large peatland in Maine, to evaluate peatland stratigraphy and hydrology. Geophysical measurements were integrated with direct measurements of peat stratigraphy from probing, fluid chemistry, and vegetation patterns in the peatland. Consistent with previous field studies, ground-penetrating radar (GPR) was an excellent method for delineating peatland stratigraphy. Prominent reflectors from the peat-lake sediment and lake sediment-mineral soil contacts were precisely recorded up to 8 m deep. Two-dimensional resistivity and induced polarization imaging were used to investigate stratigraphy beneath the mineral soil, beyond the range of GPR. We observe that the peat is chargeable, and that IP imaging is an alternative method for defining peat thickness. The chargeability of peat is attributed to the high surface-charge density on partially decomposed organic matter. The electrical conductivity imaging resolved glaciomarine sediment thickness (a confining layer) and its variability across the basin. Comparison of the bulk conductivity images with peatland vegetation revealed a correlation between confining layer thickness and dominant vegetation type, suggesting that stratigraphy exerts a control on hydrogeology and vegetation distribution within this peatland. Terrain conductivity measured with a Geonics EM31 meter correlated with confining glaciomarine sediment thickness and was an effective method for estimating variability in glaciomarine sediment thickness over approximately 18 km(2). Our understanding of the hydrogeology, stratigraphy, and controls on vegetation growth in this peatland was much enhanced from the geophysical study.

Long-Term and Seasonal Variations in CO2: Linkages to Catchment Alkalinity Generation

As atmospheric emissions of S have declined in the Northern Hemisphere, there has been an expectation of increased pH and alkalinity in streams believed to have been acidified by excess S and N. Many streams and lakes have not recovered. Evidence from East Bear Brook in Maine, USA and modelling with the groundwater acid-base model MAGIC (Cosby et al. 1985a,b) indicate that seasonal and yearly variations in soil PCO2 are adequate to enhance or even reverse acid-base (alkalinity) changes anticipated from modest decreases of SO4 in surface waters. Alkalinity is generated in the soil by exchange of H+ from dissociation of H2CO3, which in turn is derived from the dissolving of soil CO2. The variation in soil PCO2 produces an alkalinity variation of up to 15 mu eq L-1 in stream water. Detecting and relating increases in alkalinity to decreases in stream SO4 are significantly more difficult in the short term because of this effect. For example, modelled alkalinity recovery at Bear Brook due to a decline of 20 mu eq SO4 L-1 in soil solution is compensated by a decline from 0.4 to 0.2% for soil air PCO2. This compensation ability decays over time as base saturation declines. Variable PCO2 has less effect in more acidic soils. Short-term decreases of PCO2 below the long-term average value produce short-term decreases in alkalinity, whereas short-term increases in PCO2 produce shortterm alkalization. Trend analysis for detecting recovery of streams and lakes from acidification after reduced atmospheric emissions will require a longer monitoring period for statistical significance than previously appreciated.