Biota communities influence on nutrients circulation in hyporheic zone—a case study in urban spring niches in Bialystok (NE Poland)

Hyporheic zone (HZ) is an interstitial part of groundwater. Complex physical, chemical and biological processes in HZ impact water quality. We hypothesized that groundwater upwelling improves surface water with biogenic compounds in lowland spring niches, and it depends on among others biota communities. The research was conducted in two spring niches in suburbs of Białystok. Interstitial samples were collected with mini-piezometers. In the field, the physical parameters of water were examined, and the micro and macro elements were determined in the laboratory. The analysis of biota included: vascular plants and bryophytes, diatoms, macroinvertebrates and bacteria. The springs studied differed in their richness of organisms, which is associated with varying degrees of abiotic conditions and human transformation. In spring niche with high degree of naturalness were twice less nitrate ions in the surface water than in interstitial water, which indicates the assimilation of nitrate ions by plants growing on the bottom of the niche. Hydrophilic vegetation performs a stabilizing function by assimilating nitrogen compounds and contributing to a variation in nutrients concentration. Groundwater upwelling enrich surface water with DOC and TON. In spring niche No.1 with patches of vegetation, the largest number of macrozoobenthos was recorded. While, the heterogeneous bottom of spring niche No.2 affected the diversity of habitats, and greater biodiversity of benthic fauna. In interstitial waters, there were about twice as few bacteria as in spring waters. Psychrophilic bacteria were present in interstitial waters that influence natural hyporheic processes including circulation of organic matter in the microbiological loop and self-purification of water.

Assessment of Ground Regeneration around Borehole Heat Exchangers between Heating Seasons in Cold Climates: A Case Study in Bialystok (NE, Poland)

Based on the experimental studies, the process of ground regeneration around the borehole loaded with brine-water heat pumps working exclusively for heating purposes in the period of four consecutive heating seasons in a cold climate was presented. The research was conducted in north-eastern Poland. The aim of the work is to verify the phenomenon of thermal ground regeneration in the period between heating seasons on the basis of the recorded data and to check whether the ground is able to regenerate itself and at what rate. It was noticed that the ground does not fully regenerate, especially during heating seasons with lower temperatures. In the analyzed period, from 22 September 2016 to 12 October 2020, the ground probably cooled irreversibly by 1.5 °C. In order to illustrate and evaluate the speed of changes in the ground, the one’s profile with an undisturbed temperature field was presented for each month of the year. The presented results can be a very important source of information for the analysis of geothermal conditions occurring in the ground. They can be used to verify mathematical models and conduct long-term simulations that allow us to see the complexity of the processes taking place in the ground.

First Record of Slime Molds in Biebrza National Park (NE Poland)

This paper provides the first recorded data of slime molds in Biebrza National Park (NE Poland). In total, 16 species of myxomycetes belonging to nine genera were observed.