Małgorzata Włodarczyk

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.

Changes in the concentration of selected metals in sediments of the River Chotla in northwest Poland in its section affected by various anthropogenic factors

Abstract The purpose of the paper was to assess the changes in the concentration of selected metals in the bottom sediment and interstitial water of the River Chotla in northwest Poland. The research was conducted on the river section flowing through Zaspy Małe and a salmonid fish breeding farm. Samples of water and bottom sediment were taken in four control and measurement points, located above and below the village and on a backwater above the trouteries and below the fish breeding ponds. The pH and the concentration of the metals potassium, iron, calcium, manganese and zinc were determined in the water and sediment samples. The lowest concentrations of the metals were found in the samples collected above and below Zaspy Małe, while the highest concentrations of metals in the water and sediment were found in the samples taken in the backwater, above the fish breeding ponds. Exceptions were calcium and potassium, with the highest concentrations of metals in the water being found in the samples taken below the fish breeding ponds. The content of metals in sediments of the analysed section of the River Chotla was mainly determined by the content of organic matter, which varied as it is dependent on water accumulation processes and the operation of nearby fishery facilities. The slightly alkaline pH facilitated long-lasting accumulation of metals in sediments.