Wyniki wyszukiwania - Biblioteka Nauki

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Dissolved organic matter transformation in the hyporheic zone of a small lowland river

100%

Zieliński P. , Jekatierynczuk-Rudczyk E.

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tom Vol. 39, No.2

97-103

EN

The objective of this study was to examine dissolved organic carbon (DOC) concentration and specific ultraviolet absorbance (SUVA) changes in porewaters that occur over a small scale (cm) in the hyporheic zone (HZ) of a lowland stream in the Knyszynska Forest in northeast Poland. Hyporheic zone porewaters were sampled at different depths of 10, 30, 50, 70 cm at two study sites with different sediment material. The results showed significant differences in DOC concentrations between the upper and lower stream HZ. The current results indicate that small lowland sediments provide both a source and a sink of DOC for stream water, depending on the river course. The higher DOC level observed in the hyporheic zone suggests that porewater can be an autonomic site of biogeochemical changes of dissolved organic matter, which is very clear in the SUVA fluctuations.

2

Hydrochemical aspects of water exchange through the bottom of headwater stream in suburban zone on the example of the Malina watercourse in Zgierz (Central Poland)

100%

Ziułkiewicz M. , Grulke R.

Geology, Geophysics and Environment

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2024

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tom Vol. 50, no. 3

231--251

EN

Among the many factors determining the quality of river waters, the influence of the hyporheic zone (HZ) is gaining in importance. Watercourses that exist in the higher parts of catchments are relatively steep and shallow, and the topography of their valleys activate hyporheic flow. The main goal of this work is to assess the impact of the HZ on the hydrochemical state of the head watercourse of the Malina in the suburbs of the city of Zgierz with the focus on biogenic compounds. The riverbed of this stream was researched across two distinct stretches: erosive and accumulative, which differ in the conditions for the hyporheic zone’s interaction with the riverbed. The nutrients are delivered to the stream mainly in the erosive stretch and are related to the inflow of nutrient-rich groundwater from the urbanised catchment. The pollutants transported down by the stream are then delivered to the HZ in the accumulative stretch, where nitrates are denitrified and phosphates are deposited with the suspension. Ammonium nitrogen, in turn, is introduced into the stream from the HZ as a result of either the process of ammonification of organic matter deposited in sediments or inflow with polluted groundwater. The results indicate that the winter season is the most important period in shaping the interaction of river waters with the underlying hyporheic zone, in which the causal side of the relationship should be associated with the subchannel environment, and the effects are recorded in the river waters.

3

Spatial distribution of the water exchange through river cross-section – measurements and the numerical model

86%

Grodzka-Łukaszewska M. , Pawlak Z. , Sinicyn G. , Grodzka-Łukaszewska M. , Pawlak Z. , Sinicyn G.

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tom 47

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nr 1

4

Zmienność współczynnika filtracji w strefie hyporeicznej w świetle badań laboratoryjnych

86%

Marciniak M. , Szczucińska A. , Kaczmarek M.

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tom Vol. 65, nr 11/1

1115--1120

EN

The interaction between surface water and groundwater throughout the hyporheic zone determines the diurnal water level fluctuations in springs, streams and lakes. The previous studies have listed evapotranspiration, variability of hydraulic conductivity in the hyporheic zone, melting andfreeze-thawing processes, thermal expansion and water viscosity among the factors responsible for the water level diurnal fluctuations. The aim of the research was to investigate the variability of hydraulic conductivity in the hyporheic zone and its impact on the diurnal fluctuations of the water level. Experimental series were performed in laboratory conditions using seepage columns. Four types of sand sediments, with a hydraulic conductivity ranging from 6x10-6 to 5x10-4 m/s, were tested. The obtained values of hydraulic conductivity appeared to depend on the sand grain size, temperature, the direction of the hydraulic gradient, and the fluidization of the sediment (flowing sand). In all tests, higher hydraulic conductivity values were observed when water was set to flow in the direction opposite to gravity (flow up) rather than downward (flow down). In the sediments, which have not reached the state of fluidization, with an increase of the hydraulic gradient, values of hydraulic conductivity were two times higher during flow up than in the case of flow down. In the case of sediments being fluidized, the obtained values of hydraulic conductivity were roughly 3 times higher. The initiation of the fluidization process has been observed at the hydraulic gradient close to one. The results of laboratory experiments allow for a better understanding of the factors that have impact on diurnal fluctuations of the water level, especially when seepage of groundwater is present. Fluidization of the hyporheic zone after precipitation or thawing events may inhibit diurnal fluctuations.

5

Minerały autigeniczne i osady w strefie hyporeicznej aluwiów Białej Przemszy zanieczyszczonej przez górnictwo rud metali

72%

Ciszewski D. , Kucha H. , Skwarczek M.

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tom Vol. 65, nr 10/1

650--660

EN

Sediments and waters of the hyporheic zone have been investigated in the middle reach of the Biala Przemsza River (southern Poland). The river is polluted with mine waters dischargedfrom lead-zinc ore mines, and ground waters sampled from piezometers in a sand bar are polluted to a similar degree down to a depth of at least 3 m. Very high content of heavy metals in the upper 1 m-thick strata of the bar indicates that their accumulation follows start-up of the lead-zinc mining in the mid-20th century. Common authigenic pyrite, gypsum and other less widespread heavy metal minerals are observed in the sediments of both the mining- and pre-mining times. It is related to the intense infiltration of sulphate-rich waters into the sand bar and microbially controlled anoxic conditions, which favour pyrite formation.

6

Strefa hyporeiczna: znaczenie i zarządzanie

58%

Ciszewski D.

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2017

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tom Nr 10

318--324

PL

Wymiana wód rzecznych i gruntowych w aluwiach piaszczystych i żwirowych tworzy ekoton nazywany strefą hyporeiczną. Jej znaczenie jest znacznie większe niż wynikałoby ze stosunkowo małych rozmiarów ograniczonych morfologią dna doliny i jej spadkiem oraz miąższością, a także granulometrią aluwiów. Strefa ta stanowi miejsce bytowania wielu organizmów oraz ich refugium w czasie wezbrań. Jest miejscem intensywnej bakteryjnej transformacji zanieczyszczeń płynących rzeką. W obszarach użytkowanych przez człowieka strefa ta jest jednak znacząco zmieniona wskutek regulacji rzek, działalności górnictwa, rolnictwa, rozbudowy miast oraz działalności przemysłowej. Przykładem jest silnie zanieczyszczona rzeka – Przemsza, w której została ona ograniczona wskutek regulacji do pojedynczych niewielkich łach piaszczystych stanowiących miejsce intensywnej bakteryjnej transformacji związków azotu, żelaza i siarczanów. Efektem działalności bakterii jest redukcja ilości tych związków w wodzie rzecznej. Brak świadomości znaczenia tej strefy aż do niedawna przyczyniał się do nieuwzględniania jej w zarządzaniu rzekami. Współcześnie coraz częściej podejmuje się działania zmierzające do jej utrzymania lub odtworzenia; również projekty regulacji nie powinny ograniczać możliwości napływu wód rzecznych w aluwia.

EN

Hyporheic zone is a dynamic ecotone created by active exchange of river and ground waters in sandy and gravelly alluvia. Its importance is much higher than its relatively small dimensions would suggest, limited by the valley bottom morphology and gradient, as well as the thickness and the grain size of the alluvia. The hyporheic zone is a habitat of many organisms and their refuge during floods. It is a place where intensive bacteria transformation of contaminants flowing down the river occurs. In intensively anthropologically changed areas this zone is heavily affected as a result of channelization, mining, agriculture, urbanization and industrial activity. The Przemsza River is an example of a strongly contaminated river with the hyporheic zone confined to small sand bars sparsely dispersed over the riverbed, where intensive bacterial transformation of nitrates, iron compounds and sulphates takes place. Bacterial activity contributes to reduction of these compounds in the river water. Lack of awareness of the role of this zone has until recently been the reason for neglecting it in the river management policy. At present, the activities oriented towards maintenance and rehabilitation of this zone are the more and more frequent, and the river channelization project should not hinder the possibility of the river water inflow into the alluvia.

7

Dissolved organic matter transformation in the hyporheic zone of a small lowland river

58%

Zielinski P. , Jekatierynczuk-Rudczyk E.

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nr 2