Artikkelit jotka sisältää sanan 'subsidence'

Bjørn Kløve. Effect of peat harvesting on peat hydraulic properties and runoff generation.
Avainsanat: peatlands; Drainage; runoff generation; hydrological pathways; hydraulic conductivity; shear strength; soil loss; subsidence; peak runoff
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Peat hydraulic conductivity, shear strength, plant composition and runoff at seven peat harvesting sites in Central Finland were measured. A large variation in hydraulic conductivity (10–8–10–6 m s–1 ), peat shear strength (302–413 kPa), and peak runoff (97–898 l s–1 km–2 ) was observed between different harvesting sites. The hydraulic conductivity showed a clear correlation with peat shear strength (r = –0.89), which has not been previously observed. The correlation between hydraulic conductivity and degree of humification was weak (r = 0.60). Soil lowering decreased the hydraulic conductivity and the peat shear strength. These reductions, with reduced drainage depths, increased peak flow and changed runoff generation patterns by increasing the possibility of Horton and saturation excess overland flow.
  • Kløve, Jordforsk, Norwegian Centre for Soil and Environmental Research, 1432 Ås, Norway Sähköposti: ei.tietoa@nn.oo (sähköposti)
Theodore Karyotis, Athanasios Haroulis, Evagelia Vavoulidou, Pericles Papadopoulos. Soil properties and distribution of heavy metals and boron within three Greek Histosols.
Avainsanat: heavy metals; boron; histosols; sequential extraction; soil subsidence
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Three Greek soil profiles originating mostly from lacustrine deposits in the district of Filippoi (Northern Greece), were studied. These soils have been formed both from organic and inorganic materials that were deposited by precipitation and developed through the action of aquatic organisms. According to Soil Taxonomy (1992), they are classified as Histosols and belong to the suborder of Saprists. The pH of the soil horizons ranged among soil horizons from 6.2 to 7.8. The total soil nitrogen content ranged between 7.5 and 17.0 g kg–1 and the soil organic matter was between 108.7 and 206.4 g kg–1 . Calcium carbonate was detected into ten horizons and ranged between 1.4 and 27.8%, whilst it was not found in five of the examined soil layers. This is suggested to reflect the presence or absence of aquatic organisms, the shells of which contain CaCO3 and enrich soil by means of weathering. Heavy metals extracted by 4 M HNO3 were in the following order Fe>Mn>Zn>Pb>Ni>Cu>Cd, and their average concentrations were 7190, 294, 72.3, 58.2, 33.3, 17.3 and 5.1 µg g–1 , respectively. The distribution of trace elements greatly differs amongst the examined samples and the range of the pseudototal form of Fe was 1873–18550 µg g–1 , of Mn 54.7–585, of Cu 4.5–40, of Zn 22.0–185, of Pb 20.5–143, of Ni 15–64.7 and Cd 3.3–6.9 µg g–1 . The sequentially extracted by Na2 -EDTA, HNO3 and NaOH were found to be the prevailing metal forms. Iron deficiency symptoms have been observed in certain crops, and manganese deficiency was also detected in some maize crops cultivated in slightly alkaline soils. Furthermore, the plant available boron concentration was determined, as deficiency symptoms were observed in some districts cultivated with sugar beets. The distribution was generally not influenced by soil properties, although a weak relationship between organic carbon and boron was found. Measures such as rational water management, tillage practices, and fertilization could be applied towards minimization of soil degradation, micronutrient disorders and optimization of crop productivity.
  • Karyotis, National Agricultural Research Foundation, Institute for Soil Mapping and Classification, 1 Theophrastou Str., 41335 Larissa, Greece Sähköposti: ei.tietoa@nn.oo (sähköposti)
  • Haroulis, Sähköposti: ei.tietoa@nn.oo
  • Vavoulidou, Sähköposti: ei.tietoa@nn.oo
  • Papadopoulos, Sähköposti: ei.tietoa@nn.oo

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