Results of research of six large karstic springs with a discharge rate of 10-100 l/s obtainedfrom a series of 12 measurements in 2021-2022 are the basis for a comparison of the chemical composition in the past and present. The studied springs drain Triassic limestones and dolomites in the southern part of Major Groundwater Basin No. 333 in the Opole region. After 40 years, there is a significant decrease in discharge rates in five out of all selected springs, and frequent dying out of outflows in three cases. A significant increase in the content of nitrogen compounds, espe¬cially nitrates, has been measured. Statistical factor analysis allowed distinguishing two groups of factors responsible for changes in the main ions in groundwater. Restoring high groundwater quality is an urgent task for the administration of this region, which requires a comprehensive approach.
The study of the physical and chemical parameters of groundwater is one of many elements enabling complete recognition of engineering geology conditions that are used in the designing process of building construction. The degree of groundwater aggressiveness is determined, based on the groundwater components likely to cause foundation corrosion (pH, SO42-2+, NH4+, aggressive CO2) and carried out in accordance with the Polish standard PN-EN 206+A2:2021-08. A series of spatial and statistical analyses of archival data from 40 selected engineering geology documentations from the years 2010-2013 were performed to investigate the potential variability in the degree of aggressiveness of shallow groundwater in Wrocław city. Groundwater from 50 individual research points was analysed. Groundwater components: of pH and contents of aggressive carbon dioxide and sulfate ions have a significant influence on the degree of groundwater aggressiveness. Magnesium and ammonium ions are statistically unimportant. Groundwater aggressiveness environments are spatially variable and are demonstrated not only in the study area, but also within a single investment. More than one analysis is necessary to be performed to evaluate groundwater aggressiveness. This conclusion is also confirmed by the current study conducted in 2021.
Seen in the light of increasing anthropogenic impacts on the environment and a growing demand for potable water, pollution of groundwater is a very important issue, especially in large city areas. The present research includes analyses ofthe chemical composition at 109 measuring points in the Wrocław area, and of the spatial distribution of groundwater components with regard to land use, geological structure and hydrogeological conditions. Based on spatial analyses, it has been noted that changes depend mainly on land use and the kind of activity carried out in close proximity of water intake. Shallow groundwater in Wrocław is characterised by a great variability of main components. Factor analysis has made it possible to distinguish these components and determine the degree of their influence on the chemical composition of shallow groundwater in the entire study area. The current research demonstrates the high sensitivity of aquifers to pollution and emphasises the role of human activity in levels of groundwater pollution in urban areas.
Evaluation of the chemical aggressiveness of shallow ground - water for the area of Wrocław was performed in accordance with the Polish Standard (PN-EN 206+A1:2016-12). This standard requires determination of pH and concentration of ammonium, magnesium, sulphate and aggressive carbon dioxide in water. The research was carried out on 96 groundwater samples collected in the period March-May 2021 from Holocene, Pleistocene and Neogene deposits. The results show that 58% of shallow groundwater in Wrocław was aggressive towards concrete and steel. The slight (XA1), moderate (XA2) and high (XA3) aggressiveness was characteristic for 32%, 23% and 3% of the analysed waters, respectively. The significant classification factors were the concentrations of aggressive carbon dioxide, sulphate ions and, less significant, pH. The presence of magnesium and ammonium ions in groundwater did not have any classification significance because of low concentrations. The occurrence of aggressive groundwater is associated with the environment of river sediments, mainly of Holocene and Pleistocene age. Groundwater beneath till and clay formations, mainly of Pleistocene age, and of anthropogenic banks and dumps shows significantly lower aggressiveness. Aggressiveness of groundwater sampled from the aquifer covered by Neogene clay deposit is not demonstrated. The aggressiveness of Wrocław groundwater shows a mosaic space character resulting from the geological structure of the city's subsurface formations and is probably also related to the form of land development. The most aggressive ones were associated with green, agricultural and liquidated municipal waste dump areas.
Głównym celem przedstawionej pracy jest porównanie metod polowych oznaczania współczynnika filtracji w świetle potencjalnych błędów związanych z przeszacowaniem wartości współczynnika filtracji utworów przypowierzchniowych w strefie saturacji. Są one głównie wynikiem błędnych założeń o przeprowadzeniu pomiarów w warunkach pełnego nasycenia (strefie saturacji). Przedstawiono wyniki oznaczeń zrealizowanych w serii stacjonarnych oznaczeń współczynnika filtracji metodą Porcheta oraz infiltrometru dwupierścieniowego w dłuższym horyzoncie czasowym w wybranych miejscach na obszarze Wrocławia, uwzględniających zmienność sumy opadów, ale i wykształcenie litologiczne gruntów. Wykorzystując powszechnie stosowane metody oraz narzędzia analizy i interpretacji danych, przetestowano schematy postępowania pozwalające ograniczyć błędy estymacji współczynnika filtracji.
EN
The main purpose of the article is to compare the field method of the estimation of hydraulic conductivity of near-surface soils on the background of potential errors related to the determination of field-saturated hydraulic conductivity (Kfs). The overestimation of Kfs value is mainly a result of wrong assumptions about measurements under full-saturation conditions (saturation zone). The article presents results of experiment carried out in a series of stationary measurements of hydraulic conductivity using selected field methods in a longer time period in selected places in the city of Wrocław, taking into account variability of precipitation and lithology of soils. Using commonly applied methods and tools of data analysis and interpretation, the schemes of procedure were tested to reduce errors of fieldsaturated hydraulic conductivity estimation.
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