Multi‐scale analysis of electrical conductivity of peatlands for the assessment of peat properties

Abstract

Peatlands store large amounts of carbon. This storage function has been reduced through intensive drainage, which leads to the decomposition of peat, resulting in a loss of carbon. Measurements of the real ( ′ ) and imaginary part ( ′′ ) of electrical conductivity can deliver information on peat properties, such as the pore fluid conductivity ( w ), cation exchange capacity (CEC), bulk density ( b ), water content (WC) and soil organic matter (SOM) content. These properties change with the peat's degree of decomposition (DD). To explore the relationships between the peat properties, ′ , ′′ and DD, we focused on three different types of survey and scales. First, point measurements were made with a conductivity probe at various locations over a large area of northeast Germany to determine the degree of correlation between ′ and DD. Second, nine of these locations were selected for sampling to determine which of the properties w , CEC, b , WC and SOM predominantly influence ′ and ′′ . This multisite dataset includes the entire range of DD and was analysed in the laboratory. Third, one site was selected for a survey of ′ including sampling, to identify which properties mainly control ′ in a single-site approach. Statistical analysis revealed that for the multisite laboratory dataset, w has the strongest effect on ′ , followed by CEC, whereas ′′ is mainly determined by CEC. In a single-site approach, WC followed by CEC had a dominant effect on ′ . No clear correlation could be observed between (i) DD and peat properties and (ii) DD and ′ or ′′ . This is because of the complex changes in properties with increasing DD.

Relationship between electrical conductivity and water content of peat and gyttja: implications for electrical surveys of drained peatlands

“…Levels of electrical conductivity strongly vary between locations due to site‐specific loads of solutes in the groundwater (Walter et al . ; Walter et al . ).…”

“…; Walter et al . , ) more rapidly and at various spatial scales. When using ERT on peatlands, the electrical conductivity (reciprocal of resistivity) is closely related to the water content (Comas and Slater ; Ponziani et al .…”

“…; Walter et al . , ) and peat properties (Comas and Slater ; Kettridge et al . ; Ponziani, Slob and Ngan‐Tillard ; Comas et al .…”

“…; Walter et al . , , ), although saturated and unsaturated conditions have to be clearly distinguished. In natural peatlands with water saturated conditions, electrolytic conduction via the pore fluid is the major pathway for the electrical current (Comas and Slater ; Walter et al .…”

“…In natural peatlands with water saturated conditions, electrolytic conduction via the pore fluid is the major pathway for the electrical current (Comas and Slater ; Walter et al . ; Walter et al . ).…”