Nitrogen (N-2) is a key nutrient for ecosystem functioning and one of the main limiting factors for its productivity. However, its excessive input, particularly due to anthropogenic activities, can cause adverse consequences, such as soil acidification, eutrophication and reduced biodiversity. High nitrogen concentrations in surface waters are often associated with agricultural and urban sources of pollution. In this study, surface water samples from the Varazdin and Krapina-Zagorje Counties in the period from November 2022 to April 2023 were analysed. The results showed that total nitrogen values were in accordance with regulations at 14 locations, with concentrations in excess of 2.40 mg/L N at the remaining locations, which indicates a possible anthropogenic impact.
The Krapina River, located in the Hrvatsko Zagorje region, is exposed to anthropogenic pollution due to discharges of untreated urban and hospital wastewater. The aim of this research was to determine the bacteriological quality of water and surface sediments by analysing the presence of indicators of faecal pollution. Sampling was carried out from the river source and the sources of two tributaries, as well as downstream after the confluence of the Krapinica River. Intestinal enterococci and faecal coliforms were already recorded at the sources of the river and its tributaries, with their concentrations significantly increasing downstream due to the inflows of urban and hospital wastewater. The concentrations of indicator bacteria in the sediment were higher than in the corresponding free water. Based on the concentration of bacteria indicating faecal pollution, the Krapina River does not meet the criteria for bathing and recreation. Wastewater treatment prior to its discharges into the river is crucial for reducing anthropogenic impact on the ecosystem, while systematic water and sediment quality monitoring can contribute to the adoption of effective river protection measures.
This research studies the reuse of 50 % concentrate from reverse osmosis (RO), obtained from textile wastewater (TWW) as an alternative source in the irrigation of basil (Ocimum basilicum). In order to maximally reuse water and retain nutrients, a hybrid ultrafiltration system and RO were used.The basil irrigated with a RO concentrate had the largest share of dry matter (14.96 %) and nutrient intake, particularly of P2O5 (1.37 %), K2O (4.39 %) and Cu (8.58 mg/kg). Although the TWW contained more Mn, Ca and Mg, it resulted in a lower biomass, probably due to ionic imbalance or stress caused by microelements.The water used from the water supply system lead to the lowest growth and nutrient intake. These results indicate that the 50 % RO concentrate, which is often considered waste, can be safely reused for irrigation in agriculture, thus supporting the objectives of circular economy by reducing the consumption of drinking water.
Like many other cities in the world, the City of Zagreb faces increasingly destructive urban flash floods. The aim of this paper is a more accurate determination of their characteristics to enable more effective protection measures against them. Zo this end, a detailed analysis of two flash floods that occurred on 3/4 July 1989 and 24/25 July 2020 was used. The formation of flash floods in Zagreb is specific, since they are partly a result of torrential flooding by mountain streams flowing down from Mt. Medvednica into the urban area. Based on a small number of available data, an attempt was made to define the effectiveness of the retention storage built on the & Ccaron;rnomerec watercourse in mitigating floods downstream of the dam. It was determined that flash floods in Zagreb mostly occur in the warm period of the year, from June to August, during the night, from 9 pm to 1 am.
Karst aquifers, vulnerable to salinization and overexploitation, experience unfavorable trends due to climate change, with significant socio-economic and environmental consequences. A thorough understanding of the structure of a karst aquifer and its functioning is crucial for its effective protection. The most effective strategy to reduce the unpredictability associated with this hydrological 'black box'is to conduct research and measurements directly in the system and notjust at its inputs and outputs. This study presents the results of hydrological monitoring of a cave stream in the U & ccaron;ka Cave System, which has been a reliable source of water for over 40 years. In addition, speleological explorations have mapped the underground hydrological network and also revealed a significant extension of the cave, providing opportunities for improved management of existing and potential discovery of new water resources.
