Vertical manganese migration in various soil types/subtypes

In this contribution the manganese content in selected soil types (Calcero-haplic chernozem, Calcaric Fluvisol, Mollic Fluvisol, Dystric regosol, Stagnic Glossisol, Luvic Stagnisol, Dystric Cambisol) and their reaction in relationship to the loading by manganese in model conditions are evaluated. In soil samples from 0.00 - 0.10, 0.20 - 0.30, and 0.35 - 0.45 m horizons the total manganese content after their draining, finishing, and decomposition by HF + HNO3 + HClO4 mixture and its fractions content in extract of 2M HNO3 (available forms), in extract of 0.05M EDTA (potentially mobile forms), and in extract of 0.01 M CaCl2 (exchangeable forms) using atomic absorption spectrophotometry method with PYE-Unicam-SP9 instrument were determined. The knock-down columns filled with soil samples in model kinetic conditions were used for observation of manganese sorption rate. The maximal water capacity of soils was determined and then solution of 2400 mg of manganese (MnSO4.H2O) per kilogram of soil was applicated in volume higher by 50 cubic cm than water capacity in particular soil types. The migration time of solution in the column depended on the soil type. The unsorbed manganese shares were determined in eluate. The manganese contents in extraction solutions 2M HNO3 0.05M EDTA, and 0.01M CaCl2 in the drained 0.15 m high soil columns after taking to 0.05 m pieces by atomic absorption spectrophotometry method with the instrument PYE-Unicam-SP9 were determined. According to the stated values, the content of total manganese ranged from 413.00 to 1049.00 mg per kilogram of soil. The sequence of soils based on this parameter is as follows: Luvic Stagnisols more than Calcaric Fluvisols more than Calcero-haplic Chernozem more than Mollic Fluvisols more than Stagnic Glossisols more than Dystric Regosols. The content of potentially mobilizable forms of manganese reached 68.00 - 404.30 mg per kg (what is 15.6 -73.9% of the total content). The sequence of soils according to the content of this fraction is: Mollic Fluvisols more than Calcero-haplic Chernozem more than Calcaric Fluvisols more than Stagnic Glossisols more than Luvic Stagnisols more than Dystric Regosols. The content of potentially mobilizable forms of manganese was 46.80 - 402.75 mg per kg (7.9 - 39.2%). Soil sequence: Luvic Stagnisols more than Stagnic Glossisols more than Calcero-haplic Chernozem more than Mollic Fluvisols more than Dystric Regosols more than Calcaric Fluvisols. The content of mobile forms of managanese had the values from 0.06 to 32.24 mg per kg (i.e. 0.01 - 4.54% of the total content of manganese). Soil sequence: Luvic Stagnisols more than Stagnic Glossisols more than Calcero-haplic Chernozem more than Mollic Fluvisols more than Dystric Regosols more than Calcaric Fluvisols. In kinetic conditions, the content of potentially mobilizable manganese ranged from 3.83 to 611.83 mg per kg (what represents 0.11 - 25.49% of the added amount), content of currently mobilizable manganese reached 3.50 up to 1233.92 mg per kg (i.e. 0.15 - 51.41%), and the content of mobile manganese had the values 0.88 -537.50 mg per kg (i.e. 0.04 - 22.40% of the added amount of manganese). The manganese compounds in majority of tested soils are bounded in lightly released forms in extracts 2M HNO3 and 0.05M EDTA. The manganese contents of potentially mobile forms in 2M HNO3 (Mollic Fluvisol, Calcero-haplic Chernozem, Calcaric Fluvisol, Luvic Stagnisol) and in 0.05M EDTA (Luvic Stagnisol, Stagnic Glossisol) were especially high. The soils had shown different properties, where manganese migration to the lower column layers were determined. The obtained results suggest a relatively high content of manganese mobile forms determined in 2M HNO3 and 0.05M EDTA (especially in acid soils) as well as migration of manganese into the lower layers of columns. Because this means a certain risk for the ecosystems, it is necessary to accept the standard for limit values of managanese in soils also in Slovakia. The accent is given to manganese dynamics in acid soils. The results of experiments confirmed the necessity to accept the hygienic limits for manganese soil content by legislation.