Mall Orru | Tallinn University of Technology (original) (raw)

Papers by Mall Orru

Tallinna Tehnikaülikooli Raamatukogu digikogu, Tallinna Tehnikaülikooli digitaalraamatukogu.

Estonian Journal of Earth Sciences, 2008

Estonia is rich in peatlands, which cover 22.3% of its territory. About 1/4 of them are under pro... more Estonia is rich in peatlands, which cover 22.3% of its territory. About 1/4 of them are under protection, ~ 2% have been assigned for peat production, and ~ 1% is abandoned. Several peatlands are drained, which poses a challenge to their sustainability. The use of Estonian peat resources is regulated following the principles of sustainable management. During the inventory of Estonian peatlands (1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987) the properties (i.e. botanical composition) and quantity of peat were specified. In this paper an overview of these studies is given and new research fields focussing on chemical components of Estonian peat, i.e. trace elements, balneological characteristics, as well as the usability of the abandoned peatlands, are discussed.

Global and Planetary Change, 2006

This paper presents the results of the distribution of trace elements in Estonian mires. Sixty fo... more This paper presents the results of the distribution of trace elements in Estonian mires. Sixty four mires, representative of the different landscape units, were analyzed for the content of 16 trace elements (Cr, Mn, Ni, Cu, Zn, and Pb using AAS; Cd by GF-AAS; Hg by the cold vapour method; and V, Co, As, Sr, Mo, Th, and U by XRF) as well as other peat characteristics (peat type, degree of humification, pH and ash content). The results of the research show that concentrations of trace elements in peat are generally low: V 3.8 ± 0.6, Cr 3.1 ± 0.2, Mn 35.1 ± 2.7, Co 0.50 ± 0.05, Ni 3.7 ± 0.2, Cu 4.4 ± 0.3, Zn 10.0 ± 0.7, As 2.4 ± 0.3, Sr 21.9 ± 0.9, Mo 1.2 ± 0.2, Cd 0.12 ± 0.01, Hg 0.05 ± 0.01, Pb 3.3 ± 0.2, Th 0.47 ± 0.05, U 1.3 ± 0.2 μg g− 1 and S 0.25 ± 0.02%. Statistical analyses on these large database showed that Co has the highest positive correlations with many elements and ash content. As, Ni, Mo, ash content and pH are also significantly correlated. The lowest abundance of most trace elements was recorded in mires fed only by precipitation (ombrotrophic), and the highest in mires fed by groundwater and springs (minerotrophic), which are situated in the flood plains of river valleys. Concentrations usually differ between the superficial, middle and bottom peat layers, but the significance decreases depending on the type of mire in the following order: transitional mires – raised bogs – fens. Differences among mire types are highest for the superficial but not significant for the basal peat layers.The use of peat with high concentrations of trace elements in agriculture, horticulture, as fuel, for water purification etc., may pose a risk for humans: via the food chain, through inhalation, drinking water etc.

Tallinna Tehnikaülikooli Raamatukogu digikogu, Tallinna Tehnikaülikooli digitaalraamatukogu.

Estonian Journal of Earth Sciences, 2008

Estonia is rich in peatlands, which cover 22.3% of its territory. About 1/4 of them are under pro... more Estonia is rich in peatlands, which cover 22.3% of its territory. About 1/4 of them are under protection, ~ 2% have been assigned for peat production, and ~ 1% is abandoned. Several peatlands are drained, which poses a challenge to their sustainability. The use of Estonian peat resources is regulated following the principles of sustainable management. During the inventory of Estonian peatlands (1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987) the properties (i.e. botanical composition) and quantity of peat were specified. In this paper an overview of these studies is given and new research fields focussing on chemical components of Estonian peat, i.e. trace elements, balneological characteristics, as well as the usability of the abandoned peatlands, are discussed.

Global and Planetary Change, 2006

This paper presents the results of the distribution of trace elements in Estonian mires. Sixty fo... more This paper presents the results of the distribution of trace elements in Estonian mires. Sixty four mires, representative of the different landscape units, were analyzed for the content of 16 trace elements (Cr, Mn, Ni, Cu, Zn, and Pb using AAS; Cd by GF-AAS; Hg by the cold vapour method; and V, Co, As, Sr, Mo, Th, and U by XRF) as well as other peat characteristics (peat type, degree of humification, pH and ash content). The results of the research show that concentrations of trace elements in peat are generally low: V 3.8 ± 0.6, Cr 3.1 ± 0.2, Mn 35.1 ± 2.7, Co 0.50 ± 0.05, Ni 3.7 ± 0.2, Cu 4.4 ± 0.3, Zn 10.0 ± 0.7, As 2.4 ± 0.3, Sr 21.9 ± 0.9, Mo 1.2 ± 0.2, Cd 0.12 ± 0.01, Hg 0.05 ± 0.01, Pb 3.3 ± 0.2, Th 0.47 ± 0.05, U 1.3 ± 0.2 μg g− 1 and S 0.25 ± 0.02%. Statistical analyses on these large database showed that Co has the highest positive correlations with many elements and ash content. As, Ni, Mo, ash content and pH are also significantly correlated. The lowest abundance of most trace elements was recorded in mires fed only by precipitation (ombrotrophic), and the highest in mires fed by groundwater and springs (minerotrophic), which are situated in the flood plains of river valleys. Concentrations usually differ between the superficial, middle and bottom peat layers, but the significance decreases depending on the type of mire in the following order: transitional mires – raised bogs – fens. Differences among mire types are highest for the superficial but not significant for the basal peat layers.The use of peat with high concentrations of trace elements in agriculture, horticulture, as fuel, for water purification etc., may pose a risk for humans: via the food chain, through inhalation, drinking water etc.