Date of Award
Master of Science in Geology
Jon C. Boothroyd
All freshwater wetlands of Block Island, Rhode Island larger than 0.05 ha were delineated from 1:12,000-scale panchromatic aerial photographs and classified on the basis of dominant vegetation life-form, soils and water regime. The 216 wetlands cover 121.23 ha of the 2809.71 ha island and range in size from 0.05 to 7.89 ha. Thirteen wetland subclasses are present. Nonvegetated open water, robust deep marsh, robust shallow marsh and bushy shrub swamp are the four most extensive wetland subclasses and comprise 75% of the total wetland area.
The energy resource of post-glacial peat deposits in seven of the larger (0.9-7.89 ha) and most accessible wetlands was determined from 56 stratigraphically continuous cores and peat isopach maps. Maximum peat depths in these wetlands ranged from 3 to 12 m. Three peat types were found: moss, reed-sedge, and sedimentary peat. No relationship was found between wetland subclasses and the quality, thickness or type of subsurface peat.
Moisture-free (MF) proximate, ultimate, and calorific analyses from every investigated wetland indicate moss peat yields 8400-9560 BTU/lb and contains 9-19% ash. Reed-sedge has 17-34% ash and yields 6500-8500 BTU/lb, while sedimentary peat contains 36%-54% ash and yields 4700-6400 BTU/lb. An inverse relationship (99.5 significance level) exists between BTU/lb (MF) and ash and is defined by the equation: BTU/lb = -106.76 (% ash) + 10370.21.
The seven wetlands contains 92,250 tonnes of peat (35% moisture). Fuel-grade peat (>8000 BTU/lb MF,
Peters, Colen R., "Peat Resources of Selected Wetlands on Block Island, Rhode Island" (1981). Open Access Master's Theses. Paper 2054.
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