Interactions between peat and salt-contaminated runoff in Alton Bog, Maine, USA

• Published in: Journal of hydrology (Amsterdam) Vol. 182; no. 1; pp. 83 - 104
• Main Authors: Pugh, Alexander L., Norton, Stephen A., Schauffler, Molly, Jacobson, George L., Kahl, Jeffrey S., Brutsaert, Willem F., Mason, Charles F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1996
• Subjects: base saturation; bogs; calcium; cation exchange capacity; chlorides; de-icing salt; fens; Freshwater; groundwater; groundwater contamination; groundwater flow; high water tables; inorganic ions; Ion exchange; Ions; magnesium; overland flow; Peat; Q1; road salt; roads; roadside soils; Runoff; saturated hydraulic conductivity; sodium; sodium chloride; surface water; water quality; weathering; Maine
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/0022-1694(95)02934-6

Year round, concentrations of base cations (Ca, Mg, Na, and K) and Cl
− in surface and groundwater decline exponentially away from Interstate 95, a four-lane asphalt highway which bisects Alton Bog, a poor fen in Penobscot County, Maine, USA. The increased concentrations close to the highway are caused primarily by runoff of road-salt and weathering products of road-bed fill. Concentration ratios, constant with time, between base cations and H
+ at individual sites suggest that cation exchange reactions between peat and water achieve a state of equilibrium. These ratios change systematically with increasing distance from the highway, indicating systematic changes in the character of the peat exchange surfaces. The major change is a decrease in the occupancy of exchange sites by Na away from the road. These relationships and inferred processes have been duplicated with laboratory experiments. Base saturation of the peat, dominated by Ca, decreases with distance from the highway. Thus, in the short term, peat-water equilibration exerts strong controls on the water chemistry, particularly ion ratios. Long term exposure to elevated concentrations of Ca, Mg, and NaCl in the shallow ground waters has altered the peat chemistry. Availability of plant nutrients (Ca, Mg, and K) has been generally increased by the weathering of road-bed fill and equilibration of the NaCl salt with the peat.