Greenhouse gases

Peat soils store a large fraction of the global soil carbon (C) pool and comprise 95% of wetland C stocks. They also have the capability to produce and release significant amounts of greenhouse gasses (CO2, CH4) into the atmosphere. Most studies of wetland soil C and gas flux dynamics have been done in expansive peatlands in northern boreal and subarctic biomes. However, wetlands in temperate and tropical climates are vastly understudied despite accounting for more than 20% of the global peatland C stock and storing large amounts of biogenic gasses Although studies investigating greenhouse gas dynamics from peatlands have increased during the last decade, the spatial and temporal distribution of these gases still remains highly uncertain, mainly due to the limitations in terms of spatial and temporal resolution and invasive nature of most methods traditionally used. This thesis combines a series of field and laboratory studies at several sites in the Greater Everglades as examples to show the potential of hydrogeophysical methods to better understand: 1) the belowground C distribution and overall contribution to the global C stocks of certain wetlands (Chapter 2); and 2) the spatial and temporal variability in both C accumulation and releases from peat soil monoliths from several wetland sites in the Greater Everglades (Chapter 3 and 4). To estimate belowground C in the field, I used a combination of indirect non-invasive geophysical methods (GPR), aerial imagery, and direct measurements (coring) to estimate the contribution of subtropical depressional wetlands to the total C stock of pine flatwoods landscape at the Disney Wilderness Preserve (DWP, Orlando, FL). Three-dimensional (3D) GPR surveys were used to define the thickness of stratigraphic layers from the wetland surface to the mineral soil interface within depressional wetlands. Depth-profile cores in conjunction with C core analysis were utilized to visually confirm depths of each interface and estimate changes in soil C content with depth and were ultimately used to estimate total peat volume and C stock for each depressional wetland. Aerial photographs were used to develop a relationship between surface area and total wetland C stock, that were applied to estimate total landscape C stock of all depressional wetlands throughout the entire preserve. Additionally, low-frequency GPR surveys were conducted to image the stratigraphy underneath the peat basin of depressional wetlands to depict lithological controls on the formational processes of depressional wetlands at the DWP. Spatial and temporal variability in biogenic greenhouse gas (i.e. methane and carbon dioxide) production and release were investigated at the laboratory scale. Two 38 liter (0.5 m x 0.23 m x 0.3 m) peat monoliths from two different wetland ecosystems in central Florida (sawgrass peatland and a wet prairie) were compared in order to understand whether changes in matrix properties influence gas dynamics in a controlled environment (i.e. constant temperature). Gas content variability (i.e. build-up and release) within the peat matrix was estimated using a series of high frequency (1.2 GHz) GPR transects along each sample about three times a week. An array of gas traps (eight per sample) fitted with time-lapse cameras were also used in order to constrain GPR measurements and capture gas releases at 15-minute intervals. Gas chromatography was performed on gas samples extracted from the traps to determine CH4 and CO2 content. Also, at the lab scale, temporal variability in biogenic gas accumulation and release was investigated in a large 0.073 m3 peat monolith from the Blue Cypress Preserve in central Florida. An autonomous rail system was constructed in order to estimate gas content variability (i.e. build-up and release) within the peat matrix using a series of continuous GPR transects along the sample. This system ran virtually nonstop using high frequency (1.2 GHz) antennas. GPR measurements were again constrained with an array of gas traps (6) fitted with time-lapse cameras and gas chromatography. The aim of this study is to better constrain temporal scale, and better understand the heterogeneous nature (both in time and space) of gas releases from peat soils.

Peatlands act as carbon sinks while representing major sources of biogenic gases
such as methane (CH4) and carbon dioxide (CO2), two potent greenhouse gases. Gas
production and release in these peats soils are also influenced by overall warm
temperatures and water table fluctuations due to the naturally shallow water table in the
Florida Everglades. Releases of biogenic gases from Florida Everglades peat soils are not
well understood and the temporal distribution and dynamics are uncertain. The general
objective of this work was geared towards a methodological approach which aimed to
examine the feasibility of capacitance moisture probes to investigate biogenic gas
dynamics in various Florida Everglades peat soils at high temporal resolution. This work
has implications for establishing capacitance moisture probes as a method to monitor gas
dynamics in peat soils at high temporal resolution and better understanding patterns of
gas build-up and release from peat soils in the Everglades.

Colleges and universities across the U.S. are working to reduce their environmental impact. Florida Atlantic University (FAU) has joined this nationwide collegiate effort through President Frank Brogan's recent signing of the American College and University Presidents Climate Commitment (ACUPCC). For my thesis, I estimate greenhouse gas emissions at FAU from 2005-2007 through collecting and analyzing data from different university departments and inputting this information into the Clean Air- Cool Planet Campus Carbon Calculator for further computations. This greenhouse gas emission inventory for FAU meets the ACUPCC requirements. Using this greenhouse gas emission baseline, a comprehensive plan can be produced to monitor progress toward creating a sustainable and climate neutral FAU.

This paper examines permit trading as an instrument for greenhouse gas emission abatement and suggests that a cap and trade scheme is the lowest-cost option for achieving this goal. The paper examines relevant examples of emission trading within the United States, including the Acid Rain Program contained within the 1990 Clean Air Act, the Regional Greenhouse Gas Initiative, and the Chicago Climate Exchange. I address the circumstances, constraints, and degree of success of such programs in relation to the Kyoto Protocol as well as other possible permit schemes at the national level within the United States. I contrast tradable permits with other forms of environmental abatement policy including command and control regulation and taxation. Finally, I analyze the effect of several variables including population and GDP on emissions growth and draws conclusions on what extent those variables play on shaping a domestic greenhouse gas trading program.