Does the HGM Classification of Small, Non-Peat Forming Wetlands Distinguish Wetlands from Surface Water Geochemistry

We report the results of a detailed 12-month study of 23 freshwater wetlands and a larger synoptic characterization of 55 freshwater wetlands to test whether a hydrogeomorphic (HGM) classification into lotic (attached to streams) and terrene (groundwater fed) classes meaningfully descriminates wetland surface water chemical composition in the Catskill-Delaware watersheds (New York State) underlain by thin, largely siliceous mineral soils and bedrock.

Nonparametric one-way ANOVA (Kruskal-Wallis) tests on measurements of SC, Ca2+, Mg2+, Na+, DOC, TDN, TDS, Si, SO42- , pH, DO, K+, Cl-, NH4+, NO3-, TDP, and HCO3- showed statistically identical surface water chemistry of lotic and terrene wetlands.. Isotopic analyses of 2H and 18O for 30 synoptic wetland surface waters also failed to show differences for any of the HGM wetland classes. In as much as the chemistry of wetland waters reflect fundamental differences in wetland hydrology, we question the utility of HGM approaches to evaluate wetland functions in all but in a broad regional conceptual basis.