Date of Award

Spring 2015

Degree Name

Bachelor of Science

Major

Environmental Science

First Advisor

Jonathan R. Gourley

Second Advisor

Christoph E. Geiss

Third Advisor

Robert A. Colter

Abstract

Clear-cutting has been practiced for centuries to provide timber for our societal needs. It is the most economically profitable method of timber harvesting but can create disturbances in the ecosystems when practiced irresponsibly. Clear-cutting vast parcels of land can have adverse effects on the quality of the soils, including erosion, loss of nutrients due to rapid runoff, and disruption of habitats and wildlife. Moreover, with large parcels of trees cut, soils are more exposed to direct airborne fallout and rapid runoff of trace metals such as mercury (Hg) into nearby fluvial systems. In the summer of 2013, soil samples were collected at three forested sites prior to clear-cutting in order to determine baseline concentrations of Hg and organic material. The three sites were Mill Stone (ME), Douglas Brook (NH), and Hogsback (NH). Samples at the Mill Stone site reported higher concentrations of Hg (μ=194, SE=7) from the O-horizon than did from the B-horizon (μ=93, SE=5); samples at the Douglas Brook site reported relatively high concentrations of Hg from the O-horizon (μ=209, SE=8) and from the B-horizon (μ=139, SE=6); samples at the Hogsback site reported the highest concentrations of Hg from the O-horizon (μ=250, SE=10) and from the B-horizon (μ=160, SE=14). The means from both horizons at all three sites exceeded the baseline concentration of 85 ppb in the United States and only the means from O-horizon at three sites were above the Threshold Effect Concentration (TEC) of 180 ppb, found in sediment from freshwater ecosystems. Positive correlations between Hg and organic material from the baseline data were observed. The sites will be revisited and samples collected in the next five years and those data will be compared with the baseline data from this study to observe and analyze the effects of clear-cutting on Hg, organic material, and the relationship between the two in the soils over time after the clear-cut.

Comments

Senior thesis completed at Trinity College for the degree of Bachelor of Science in Environmental Science.