Chemical properties of peat in three peatlands with balneological potential in Estonia
Key Findings
- Humic substance content up to 60% in Parika peatland — highest of three studied sites
- Parika peatland: humic acids 39.3%, hymatomelanic acids 19.3%, fulvic acids 1.3% of dry weight
- Degree of humification and peat type are the main factors influencing humic substance levels
- Forest(pine)–cottongrass peat composition yields highest humic substance concentrations
- Lipids strongly correlate with hymatomelanic acids (r=0.93), suggesting lipids are bound to HMA
- Fulvic acids correlate with trace metals Cd (r=0.91), Th (r=0.86), Zn (r=0.76) — FA acts as metal transport agent
- Humic acids show negative correlation with Th (r=−0.76), Sr (r=−0.82), Mn (r=−0.75)
- Total balneological peat resources in three peatlands: Kõverdama 226,000t, Parika 113,000t, Sangla 466,000t
- Estonian peat HS content exceeds Finnish values (20–40% HA, 4–12% FA)
Detailed chemical analysis of peat from three Estonian peatlands (Kõverdama, Parika, Sangla) selected for balneological potential. Extends the earlier Orru 2010 survey with full humic substance fractionation and trace element correlation analysis.
Method
Peat samples from middle layers (0.7–2.8 m depth) analyzed for humic acid, hymatomelanic acid, and fulvic acid content using alkaline extraction (0.2 M NaOH) followed by acid precipitation and ethanol separation. Lipids extracted with chloroform/ethanol (2:1). Trace elements from prior analyses by Geological Survey of Finland (ICP-MS, ICP-AES).
Key Data
| Peatland | Depth (m) | Humification | HA (%) | HMA (%) | FA (%) | Lipids (%) |
|---|---|---|---|---|---|---|
| Kõverdama | 1.30–2.80 | 40–45%, H7 | 17–24 | 9–13 | 2–3 | 2.5–4.4 |
| Parika | 0.70–1.75 | 50%, H8 | 39.3 | 19.3 | 1.3 | 7.3 |
| Sangla | 0.50–1.50 | 40–45%, H7 | 17–22 | 4–6 | 1.0–1.3 | 1.9–3.6 |
Significance
Establishes Parika peatland as the highest-quality Estonian source for balneological peat. The lipid–HMA correlation (r=0.93) suggests hymatomelanic acids serve as carriers for biologically active lipid components. The FA–metal correlations demonstrate fulvic acids’ role as transport agents for trace elements in peat systems.