Romualda Bejger

Photosensitizing properties of water-extractable organic matter from soils

Water-extractable organic matter (WEOM) was extracted using pure water from two black soils and from the Elliott reference soil of the International Humic Substances Society (IHSS). WEOMs were characterized by chemical and spectroscopic methods. The apparent quantum yields of singlet oxygen, triplet excited states and hydroxyl radicals formation upon irradiation within the wavelength range 290-450 nm were determined using chemical probes and compared to those of standard Elliott humic substances. In general, the aromatic content, as measured by the SUVA value, was close in WEOMs and humic substances, while the E2/E3 was higher and the humification index lower in the former. Quantum yield values measured for WEOMs fell within the range of those found for basic medium extracted humic substances or were even higher in one case. Thus, water soluble aromatic moiety of the soil organic matter, especially those with low humification degree, is important for the photosensitizing properties. We also found that WEOMs sensitized the bisphenol A phototransformation with rates of the same order of magnitude for all the samples.

The impact of restoration processes on the selected soil properties and organic matter transformation of mountain fens under Caltho-Alnetum community in the Babiogórski National Park in Outer Flysch Carpathians, Poland

PurposeThe objective of this study was to determine the impact of restoration processes on the selected soil properties and organic matter transformation of mountain fens under the Caltho-Alnetum community in the Babiogórski National Park in Outer Flysch Carpathians.Materials and methodsRestoration processes were conducted on three degraded mountain fens in the Babiogórski National Park in Outer Flysch Carpathians, Poland. The degradation degree of soils was the criterion for the selection of habitats for further studies. To determine the influence of restoration processes on mountain fen soil properties and organic matter transformation, samples were collected in 2011 and 2013. The soil samples were assayed for pH, base cation concentration, hydrolytic acidity, organic carbon and total nitrogen content, total exchangeable base cation concentration, cation exchange capacity, and base saturation. Organic matter fractions were extracted by IHSS method. Quantitative and qualitative study of organic matter was based on fraction composition analysis and the ratio of humic acid carbon to fulvic acid carbon. The research results were statistically verified.Results and discussionBased on morphological and chemical properties, the studied mountain fen soils can be classified as Sapric Dranic Eutric Histosols and Sapric Dranic Dystric Histosols according to WRB guidelines (2015). Before restoration processes, the mountain fen soils subjected to a different water regime showed various contents of total nitrogen and organic carbon. The decreasing of the groundwater level was reflected in pH, calcium ion content, exchangeable base cation concentration, and base saturation. The increase of the groundwater level had influence on chemical properties of mountain fen soils such as pH, total exchangeable base cation concentration, hydrolytic acidity, cation exchange capacity, and base saturation. Three-year restoration processes did not cause significant changes in the composition of humic substance fractions.ConclusionsMountain fens under Caltho-Alnetum community are priority habitats in Babiogórski National Park in Outer Flysch Carpathians, Poland. These habitats responded to restoration processes in varying degrees depending on the extent of their degradation. The least degraded mountain fen was characterized by a short response time on the restoration processes. The reaction of higher degraded habitats was weaker.

Studying of the interaction between peat humic acids and metazachlor using spectroscopy methods

PurposeThe analysis covered the interaction of humic acids (HA) isolated from peats with the metazachlor using spectroscopic methods.Materials and methodsFive peatlands have been selected for the study in the southern and northern parts of Poland. Extraction of humic acids (HA1, HA2, HA3, HA4, and HA5) was performed using a procedure recommended by the International Humic Substances Society. Metazachlor 500 SC with metazachlor as a biologically active substance [2-chloro-N-(pyrazol-1-ylmethyl)acet-2′,6′-xylidide] has been used. HA have been assessed on the basis of their elemental composition. Spectroscopic techniques have been used to study the HA structure and their interaction with metazachlor including: UV-visible spectroscopy, dynamic light scattering, and delayed luminescence (DL)Results and discussionBased on their morphological and chemical properties, the studied peat soils can be classified as follows: (1) Eutric Murshic Sapric Histosols, (2) Eutric Sapric Histosols, (3) Eutric Hemic Histosols, (4) Eutric Fibric Histosols, and (5) Dystric Dranic Hemic Histosols according to the WRB guidelines (2015). Results showed that the largest particle size, measured by E4/6 coefficient, was found in HA2 sample, while the smallest in HA3 sample. The addition of metazachlor to HA solutions reduced the values of E4/6 coefficient by 33 to 72%, while the values of hydrodynamic diameter by 4 to 32%. No significant changes were found between E4/6 after adding of metazachlor to HA solutions. The largest changes in DL intensity, excited both by blue and red light after herbicide addition, were observed in HA2 sample, which is characterized by the largest particle size, the highest oxygen content and CQ value as well as the lowest “aromatization rate” value.ConclusionsThe particle sizes of HA molecules measured by E4/6 coefficient do not impact on the particle sizes of HA-herbicide systems measured by the same ratio. The delayed luminescence may become valuable, because it is simple, fast, and sensitive. Additionally, the results show minor errors comparing with chemical methods. This method may provide information about structure and nature of humic acids, as well as their photoreactivity. The using of delayed luminescence in studies of HA-pesticides interaction may enable us to better understand the luminescence properties of HA.