Water

Research

17 pages, 3203 KiB

Open AccessArticle

Sr Isotope, Major, and Trace Element Signatures in Karst Groundwaters

by Anamaria Iulia Török, Ana Moldovan, Claudiu Tănăselia, Eniko Kovacs, Ionuț Cornel Mirea, Oana Teodora Moldovan and Erika Andrea Levei

Water 2023, 15(7), 1431; https://0-doi-org.brum.beds.ac.uk/10.3390/w15071431 - 6 Apr 2023

Cited by 1 | Viewed by 1688

Abstract

Natural and anthropogenic factors highly influence the concentration of major (Na, Mg, K, Ca) and trace (Sr, Ba, Mn, Li) elements, anions (HCO₃⁻, NO₃⁻, SO₄²⁻, Cl⁻), and Sr isotopic signatures. The current [...] Read more.

Natural and anthropogenic factors highly influence the concentration of major (Na, Mg, K, Ca) and trace (Sr, Ba, Mn, Li) elements, anions (HCO₃⁻, NO₃⁻, SO₄²⁻, Cl⁻), and Sr isotopic signatures. The current study identified the Sr isotopic signature in groundwaters from the Southern Carpathians and Apuseni Mountains karst areas of Romania and its relation to the water’s chemistry. The Sr concentration ranged between 16.5 and 658 µg/L, but in most groundwaters, it was below 200 µg/L. A considerable spatial variation and a low temporal variation, with a slightly lower Sr concentration in the winter than in spring, were observed. The strong positive correlation of the Sr with Ca, Mg, K, and Na indicated the common source of these elements. The main source of the Sr in groundwaters was the dissolution of carbonates, especially calcite, and dolomite to a lesser extent. The ⁸⁷Sr/⁸⁶Sr isotopic ratio ranged between 0.7038 and 0.7158. Generally, waters with a high Sr concentration and moderate ⁸⁷Sr/⁸⁶Sr ratios indicated carbonate dissolution, whereas samples with low Sr concentrations and high ⁸⁷Sr/⁸⁶Sr ratios suggested the dissolution of silicates. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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19 pages, 4172 KiB

Open AccessArticle

Applying Electrical Resistivity Tomography and Biological Methods to Assess the Hyporheic Zone Water Exchanges in Two Mediterranean Stream Reaches

by Sanda Iepure, David Gomez-Ortiz, Javier Lillo, Rubén Rasines-Ladero and Tiziana Di Lorenzo

Water 2022, 14(21), 3396; https://0-doi-org.brum.beds.ac.uk/10.3390/w14213396 - 26 Oct 2022

Cited by 1 | Viewed by 2072

Abstract

The hyporheic zone (HZ) is a critical area of all river ecosystems. It is the area beneath the stream and adjacent to the stream, where the surface water and groundwater are mixed. The HZ extends both vertically and laterally depending on the sediment [...] Read more.

The hyporheic zone (HZ) is a critical area of all river ecosystems. It is the area beneath the stream and adjacent to the stream, where the surface water and groundwater are mixed. The HZ extends both vertically and laterally depending on the sediment configuration, namely their porosity and permeability. This influences the hyporheic communities’ structural pattern and their active dispersal among distinct rivers compartments and alluvial aquifers. It is still difficult to assess the spatial extent of the HZ and the distribution of the mixing zones. This study applies time-lapse images obtained using electrical resistivity tomography (ERT) of 20 m wide and 5 m deep alluvial streams, with regards to the structural pattern of hyporheic communities represented by cyclopoids and ostracods, in order to assess the extent of the HZ in the riverbed and the parafluvial sediment configurations. The ERT images obtained at the hyporheic Site 1 are characterized by alluvial deposits dominated by coarse and very coarse sands with resistivity values ranging from ~20 to 80 Ohm.m, indicating a permeable zone up to ~0.5 m thick and extending laterally for ca. 5 m from the channel and associated with the hyporheic zone. The sediment configurations, texture, and structure indicate an active surface–hyporheic water exchange and low water retention into the sediments. This is also indicated by the hyporheic copepods and ostracods communities’ structure formed by a mixture of non-stygobites (five species) and stygobites (two species). A low-resistivity (<70 Ohm.m) permeable zone located 2.3 m below the streambed and unconnected with the river channel was also detected and associated with the associated alluvial aquifer. In contrast, the resistivity image at Site 2 dominated by coarse, medium, and very fine sands, shows a low-permeability zone in the upper ~0.5 m of the profile, with a resistivity value ranging from ~45 to 80 Ohm.m, indicating a reduced HZ extension in both vertical and lateral dimensions. Here the sediment configurations indicate that the water retention and interaction with the sediment is higher, reflected by more diverse hyporheic communities and with highly abundant stygobite species. The two examples show that non-invasive ERT images and biological assessments provide complementary and valuable information about the characterization of the sub-channel architecture and its potential hydraulic connection to the floodplain aquifer. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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20 pages, 2751 KiB

Open AccessFeature PaperArticle

Potential for Natural Attenuation of Domestic and Agricultural Pollution in Karst Groundwater Environments

by Traian Brad, Mina Bizic, Danny Ionescu, Cecilia Maria Chiriac, Marius Kenesz, Carmen Roba, Artur Ionescu, Alexandru Fekete, Ionut Cornel Mirea and Oana Teodora Moldovan

Water 2022, 14(10), 1597; https://0-doi-org.brum.beds.ac.uk/10.3390/w14101597 - 16 May 2022

Cited by 12 | Viewed by 3356

Abstract

In karst areas, anthropogenic contaminants reach the subsurface with detrimental effects on the groundwater ecosystem and downstream springs, which often serve as drinking water sources for the local human communities. We analyzed the water chemistry and microbial community composition in upstream and downstream [...] Read more.

In karst areas, anthropogenic contaminants reach the subsurface with detrimental effects on the groundwater ecosystem and downstream springs, which often serve as drinking water sources for the local human communities. We analyzed the water chemistry and microbial community composition in upstream and downstream locations of five hydrokarst systems (HKS) during four seasons. Conductivity and nitrates were higher in the downstream springs than in the pre-karst waters, whereas the concentration of organic matter, considered here as a pollution indicator, was lower. The microbial community composition varied largely between upstream and downstream locations, with multiple species of potentially pathogenic bacteria decreasing in the HKS. Bacteria indicative of pollution decreased as well when passing through the HKS, but potential biodegraders increased. This suggests that the HKS can filter out part of the polluting organic matter and, with it, part of the associated microorganisms. Nevertheless, the water quality, including the presence of pathogens in downstream springs, must be further monitored to control whether the water is appropriate for consumption. In parallel, the human populations located upstream must be advised of the risks resulting from their daily activities, improper stocking of their various wastes and dumping of their refuse in surface streams. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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16 pages, 4836 KiB

Open AccessArticle

Challenges in Interpreting Geochemical Data: An Appraisal of Analytical Techniques Applied to a Karstic Lake Sediment Record

by Aritina Haliuc, Alicja Bonk, Jack Longman, Simon M. Hutchinson, Michal Zak and Daniel Veres

Water 2022, 14(5), 806; https://0-doi-org.brum.beds.ac.uk/10.3390/w14050806 - 4 Mar 2022

Viewed by 2831

Abstract

The paleoclimatic and paleoenvironmental changes inferred from shifts in lake sediment geochemistry require reliable, efficient and cost-effective methods of analysis. The available geochemical techniques, however, suggest that different analytical approaches can influence data interpretation. X-ray fluorescence core scanner analyses (XRF-CS), field portable X-ray [...] Read more.

The paleoclimatic and paleoenvironmental changes inferred from shifts in lake sediment geochemistry require reliable, efficient and cost-effective methods of analysis. The available geochemical techniques, however, suggest that different analytical approaches can influence data interpretation. X-ray fluorescence core scanner analyses (XRF-CS), field portable X-ray fluorescence (FPXRF) and inductively coupled plasma optical emission spectrometry (ICP-OES) were concurrently applied to provide a multi-method geochemical appraisal of a 6000-year-long karstic sediment record (Lake Ighiel, Romania). The comparison between techniques was based on a set of elements that are widely employed in environmental reconstructions (Ti, K, Fe, Ca). Descriptive and statistical approaches were used to assess the advantages and disadvantages of each method and assess their optimal use in karstic environments. Our data display similar downcore patterns, with strong to moderate correlations between the datasets. The discrepancies observed between method-specific downcore multi element behaviour are related to the preparation steps and sampling. To best capture the complexity of past environmental changes in karstic settings, a combination of quantitative and qualitative geochemical methods would be the most appropriate approach to reliable data acquisition and subsequent paleoenvironmental interpretation of lake sediment data. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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18 pages, 5577 KiB

Open AccessArticle

Linking Hydrogeology and Ecology in Karst Landscapes: The Response of Epigean and Obligate Groundwater Copepods (Crustacea: Copepoda)

by Mattia Di Cicco, Tiziana Di Lorenzo, Mattia Iannella, Ilaria Vaccarelli, Diana Maria Paola Galassi and Barbara Fiasca

Water 2021, 13(15), 2106; https://0-doi-org.brum.beds.ac.uk/10.3390/w13152106 - 31 Jul 2021

Cited by 7 | Viewed by 2611

Abstract

Groundwater invertebrate communities in karst landscapes are known to vary in response to multiple environmental factors. This study aims to explore the invertebrate assemblages’ composition of an Apennine karst system in Italy mainly described by the Rio Gamberale surface stream and the Stiffe [...] Read more.

Groundwater invertebrate communities in karst landscapes are known to vary in response to multiple environmental factors. This study aims to explore the invertebrate assemblages’ composition of an Apennine karst system in Italy mainly described by the Rio Gamberale surface stream and the Stiffe Cave. The stream sinks into the carbonate rock and predominantly feeds the saturated karst into the cave. For a minor portion, groundwater flows from the epikarst and the perched aquifer within it. The spatial distribution of the species belonging to the selected target group of the Crustacea Copepoda between the surface stream and the groundwater habitats inside the cave highlighted a different response of surface-water species and obligate groundwater dwellers to the hydrogeological traits of the karst unit. Our results suggest that fast endorheic infiltration routes promoted the drift of epigean species from the surface to groundwater via the sinking stream while most of the obligate groundwater dwellers come from the perched aquifer in the epikarst from diffuse infiltration pathways. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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19 pages, 2522 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Water Quality and Hydrogeochemical Characteristics of Some Karst Water Sources in Apuseni Mountains, Romania

by Maria-Alexandra Hoaghia, Ana Moldovan, Eniko Kovacs, Ionut Cornel Mirea, Marius Kenesz, Traian Brad, Oana Cadar, Valer Micle, Erika Andrea Levei and Oana Teodora Moldovan

Water 2021, 13(6), 857; https://0-doi-org.brum.beds.ac.uk/10.3390/w13060857 - 21 Mar 2021

Cited by 20 | Viewed by 4550

Abstract

Human activities and natural factors determine the hydrogeochemical characteristics of karst groundwaters and their use as drinking water. This study assesses the hydrogeochemical characteristics of 14 karst water sources in the Apuseni Mountains (NW Romania) and their potential use as drinking water sources. [...] Read more.

Human activities and natural factors determine the hydrogeochemical characteristics of karst groundwaters and their use as drinking water. This study assesses the hydrogeochemical characteristics of 14 karst water sources in the Apuseni Mountains (NW Romania) and their potential use as drinking water sources. As shown by the Durov and by the Piper diagrams, the chemical composition of the waters is typical of karst waters as it is dominated by HCO₃⁻ and Ca²⁺, having a circumneutral to alkaline pH and total dissolved solids ranging between 131 and 1092 mg L⁻¹. The relation between the major ions revealed that dissolution is the main process contributing to the water chemistry. Limestone and dolostone are the main Ca and Mg sources, while halite is the main Na and Cl source. The Gibbs diagram confirmed the rock dominance of the water chemistry. The groundwater quality index (GWQI) showed that the waters are of excellent quality, except for two waters that displayed medium and good quality status. The quality of the studied karst waters is influenced by the geological characteristics, mainly by the water–rock interaction and, to a more limited extent, by anthropogenic activities. The investigated karst waters could be exploited as drinking water resources in the study area. The results of the present study highlight the importance of karst waters in the context of good-quality water shortage but also the vulnerability of this resource to anthropogenic influences. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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22 pages, 4277 KiB

Open AccessEditor’s ChoiceArticle

Quality and Health Risk Assessment Associated with Water Consumption—A Case Study on Karstic Springs

by Ana Moldovan, Maria-Alexandra Hoaghia, Eniko Kovacs, Ionuț Cornel Mirea, Marius Kenesz, Răzvan Adrian Arghir, Alexandru Petculescu, Erika Andrea Levei and Oana Teodora Moldovan

Water 2020, 12(12), 3510; https://0-doi-org.brum.beds.ac.uk/10.3390/w12123510 - 14 Dec 2020

Cited by 33 | Viewed by 4275

Abstract

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used [...] Read more.

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used as drinking water source, according to their quality and seasonal variation. The physico-chemical parameters of waters were compared with the guideline values for drinking water established by the World Health Organization and the Directive 98/83/EC. The nitrate and Cr concentrations exceeded the guideline value in the springs from Southern Dobrogea, but met the quality criteria in those from Northern Dobrogea, thus, to be used as drinking water, the karstic springs located in Southern Dobrogea require treatment for nitrates removal. Heavy metals pollution indices showed low to medium cumulative heavy metal pollution in all springs, while the human health risk assessment by oral exposure indicated possible noncarcinogenic risks of nitrates, both for adults and children in springs from South Dobrogea. A rigorous monitoring of the water quality before human consumption is recommended for all four studied water sources. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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16 pages, 2116 KiB

Open AccessArticle

Testing Different Membrane Filters for 16S rRNA Gene-Based Metabarcoding in Karstic Springs

by Oana Teodora Moldovan, Andreea Baricz, Edina Szekeres, Marius Kenesz, Marial Alexandra Hoaghia, Erika Andrea Levei, Ionuț Cornel Mirea, Ruxandra Năstase-Bucur, Traian Brad, Iulia Chiciudean and Horia Leonard Banciu

Water 2020, 12(12), 3400; https://0-doi-org.brum.beds.ac.uk/10.3390/w12123400 - 3 Dec 2020

Cited by 7 | Viewed by 3919

Abstract

Introduction: Karstic springs are used worldwide by rural communities as sources of fresh water for humans and livestock. In Romania, one-third of the population has no direct access to a public water supply. The present study is part of a country-wide project to [...] Read more.

Introduction: Karstic springs are used worldwide by rural communities as sources of fresh water for humans and livestock. In Romania, one-third of the population has no direct access to a public water supply. The present study is part of a country-wide project to develop simple, quick and cheap methods for seasonal environmental and microbiological monitoring of karstic springs used as drinking water by rural populations. Critical steps for monitoring workflow consist of evaluating water quality and selecting suitable membrane filters to efficiently capture environmental DNA for further microbial diversity estimation using 16S rRNA gene-based metabarcoding. Methods: Several commercial membrane filters of different compositions and pore sizes were tested on the water sampled from three karstic springs in Romania, followed by water chemistry and whole community 16S rRNA gene-based metabarcoding analysis. Results: We found that different types of applied membrane filters provide varying recovery in diversity and abundance of both overall and pathogenic bacteria. Conclusions: The result of the experiment with different filters shows that mixed cellulose ester, cellulose acetate, and nitrate membranes of 0.20 and 0.22 µm are the best for amplicon-based metabarcoding monitoring of karst springs. Full article

(This article belongs to the Special Issue Research on Karst Eco-Hydrology and Sediment)

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