2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 5
Presentation Time: 8:00 AM-12:00 PM


GRAVES, Dustin M., TEDESCO, Lenore P. and HERNLY, F. Vincent, Geology, Indiana University ~ Purdue University at Indianapolis, 723 W. Michigan St., SL 118, Indianapolis, IN 46202, dmgraves@iupui.edu

Most of the fens that once occurred naturally in Indiana have been altered, depleted, or destroyed. The protection or restoration of these unique wetland habitats increases the aesthetics and diversity of our natural surroundings and improves water quality. The fact that most of Indiana's wetlands have been lost increases the need to protect and restore fens as unique habitats. Wetland mitigation regulators have emphasized the need for further research that aids in the identification of variables that could assist in wetland restoration success. A field investigation of naturally occurring fens in central Indiana aims to provide an association of fen water chemistry and evolution of fen water to stratigraphic position or surrounding land use. Each fen has water sourced from a glacial till contact and can be described as a slope wetland. Discrete measurement of temperature, specific conductivity, total dissolved solids, salinity, and pH are conducted during site visits using a YSI multi-parameter probe. Specific chemical constituents of shallow groundwater that sustain fens are measured using colorimetric methods (alk., NH3, Cl-, SO4, Si, PO42-, NO2, NO3) and ion chromatography (Ca2+, Mg2+, Na+, K+). The values of the aforementioned parameters in the shallow groundwater will be related to landform properties in an effort to generate descriptive hydrochemical data. Deployed YSI probes continuously measure water level, temperature, and conductivity while water samples are collected monthly. Five fen sites that are sourced from a similar stratigraphic and geomorphic setting have preliminarily shown similarities in groundwater chemistry, specifically the seep water that is intercepted at the surface and sustains the fen ecosystems. Although the fens are fairly homogenous, one of the five sites has shown nutrient enrichment of NO2 and NO3 (Holliday Park), while another site harbors elevated concentrations of Cl- in the groundwater (Mounds State Park). The values observed thus far suggest that surrounding land use has a notable signature in the groundwater that feeds these unique ecosystems. Continuation of groundwater monitoring should yield a graphic understanding of the chemistry of each fen and its related geologic or land use influence.