Document Type

Theses, Ph.D

Rights

Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence

Disciplines

1.5 EARTH AND RELATED ENVIRONMENTAL SCIENCES, Environmental sciences

Publication Details

This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy (Ph.D.)

Abstract

Blanket peatlands in Ireland are reservoirs of organic matter and have effects on carbon dioxide (CO2) flux regulation. Data on dissolved CO2 in Ireland is limited. In blanket peatlands, the drainage systems are well connected with pools, hummocks and lawns and this connectivity leads to significant variations in outflows of carbon. The excess carbon dioxide in blanket peatlands could originate from soil organic matter decomposition. Dissolved CO2 could be transported into pools via surface run-off and lateral throughflow. Peatland pools are typically supersaturated in CO2. As part of a project described in this thesis, the role of spatial and seasonal variables on carbon dynamics at Kippure blanket peatland was assessed. The methods deployed in here included a continuous in-situ monitoring of CO2 using NDIR (nondispersive infrared) sensors in peatland pools, hummocks and a lawn. The monitoring included meteorological parameters and routine hydrochemical sampling. Three stations were established. The study provided data to produce a conceptual model: ‘Kippure-PeatHydro-CO2’ of carbon dynamics. Results suggest that CO2 concentrations were greater in the waters from hummocks (3.74-292.12 mgl-1 [C]) and a lawn (1-6.52 mgl-1 [C]) compared to that occurring in pools (0.44-0.71 mgl-1 [C]). Higher temperatures, the presence of vascular plants, microbial activity, variable water tables and dissolved organic carbon breakdown were among factors correlated with higher levels of CO2 in hummocks and lawns. The lower values of CO2 observed in pools were correlated with a lower pH and the aromaticity of organic matter. In general, diurnal levels of CO2 were correlated with photosynthetic activity (during daytime) and respiration (during night-time). Fluxes of CO2 modelled in this study were greater in summer 0.28-0.51 gm-2 d -1 compared to winter estimates. These were correlated with wind driven turbulence of water. Under changing climate, fluvial exports of CO2 could increase. The ‘Kippure-PeatHydro-CO2’ model could be a valuable tool in simulating blanket peatland dynamics and in providing insight to the eco-hydrological fluxes of carbon under a changing climatic regime particularly in relation to precipitation and temperature. Such a tool will also greatly facilitate the development of appropriate land-use management strategies consistent with Ireland’s greenhouse gas emission regulation and water quality control.

DOI

https://doi.org/10.21427/40TM-HV65

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