Chemical composition of groundwater in the zone of slow water exchange of the Upper Pontian aquifer, Northwestern Bulgaria

The Upper Pontian aquifer occupies the central part of the Lom Depression. The geological position determines its gradual dipping from the periphery to the central parts. It is one of the most water-abundant aquifers in Northwestern Bulgaria and is associated with the sands of the Archar Formation. The chemical composition of the waters is of interest and is important for the water supply in the area. The analysis of the data shows that there are regularities in the change of the water quality with aquifer depth. Significant differences in some of the hydrochemical parameters are found in the zone of slow water exchange and geological and hydrogeological explanations have been sought.

The effect of the drug “Amiksyn” on the immune status of carp

The productivity of pond fish, in particular carp, largely depends on the intensity of use of aquatic bioresources. The aim of the study was to investigate the effect of “Amiksyn” on the immunological parameters of carp fish, namely: the number of T- and B-lymphocytes, immunoglobulins, the level of circulating immune complexes, lysozyme, phagocytic activity and bactericidal activity of serum. 10 fish were selected for hematological and biochemical studies. The research was conducted in the aquarium of the Department of Aquatic Bioresources of Stepan Gzhytskyi NUVMB Lviv. Fish were kept in the pool for 21 days to adapt to the new conditions, and at the beginning of the series of experiments were placed in aquariums with a volume of 200 liters. Aeration and mechanical filtration of water were provided in the tanks. The temperature during the experiments fluctuated slightly and was 18 ± 1.5 °C. The main hydrochemical parameters corresponded to fish farming standards. In order to adjust the immune response, and thus prevent possible manifestations of fish damage by pathogens, we studied the possibility of using the immunostimulant “Amiksyn”, which was used for 5 – 10 – 15 – 20 days and then dosing 5 – 10 – 15 mg/kg body weight Pisces. The use of “Amiksyn” at a dose of 10 mg/kg of fish weight four times during the fifteen-day period with an interval of 5 days provided a decrease in the number of T-lymphocytes by 9.1 % and B-lymphocytes by 23.0 %; caused the activation of non-specific resistance indicators, namely lysozyme activity increased by 28.7 %, phagocytic activity of leukocytes increased by 14.0 % and bactericidal activity of serum increased by 19.0 %. Therefore, to adjust the immune system and stimulate the metabolic processes of fish in order to prevent the negative effects of various pathogens, the most optimal dose was 10 mg/kg of fish weight within 15 days of use.

CONTRIBUTION TO THE HYDROCHEMICAL KNOWLEDGE OF AQUIFERS IN THE DEPARTMENT OF TANDJILE-EAST, SOUTHERN CHAD

The province of Tandjile is one of the 23 provinces of the Republic of Chad. The drinking water supply rate in this region remains low. Part of the population obtains its water supply through open wells and / or surface water. Climatic and anthropogenic variations in recent years have shown how much groundwater can be influenced both in terms of its quality and its quantity to be used. The objective of this study is to provide knowledge on the state of the hydrodynamic and hydrochemical parameters of the aquifer of the department of Tandjile-Est to help decision-makers in their approach. This study is based mainly on existing data collected in Chadian institutions and literary journals. The analysis of these data showed that the lithology is represented by clayey, sandy, lateritic formations and clay-sandy mixtures. The aquifers are sandy and sandy-clayey. The groundwater temperature values are in equilibrium with those of the air, the pH shows values close to neutrality and the electrical conductivity below standards (Chad, WHO). The groundwater in the study area is not very mineralized and the concentrations of elements indicating contamination (nitrates, chloride, etc.) are clearly in traces. Chemical analyzes revealed two chemical facies: calcium and magnesium bicarbonate and sodium and / or potassium bicarbonate.

Hydrochemistry and environmental isotopes (18O, 2H, 3H, 3He/4He) of groundwater and floodwater in the great area of Hurghada, Eastern Desert of Egypt

Porous and fractured aquifers exist in the area of Hurghada, Eastern Desert of Egypt, whose recharge processes through the common flash floods are not identified. Hydrochemical parameters, stable isotopes 18O, 2H and tritium in floodwater and groundwater were applied in the area subject to study. Additionally, He isotopes were investigated in the deep wells in the faulted zone at the Abu Shaar Plateau. 3H activity in all sampled points lies below the detection limit excluding a recent recharge component in groundwater. However, the hydrochemical ratios and the stable isotope signature confirm that the shallow wells and springs (Red Sea Hills group) are being recharged from modern precipitation. The hydrochemical parameters of the deep wells at the Abu Shaar Plateau (coastal plain group) confirm another origin for the ions rather than the modern precipitation. Together with the 18O and 2H values, the Br/Cl ratio of this group confirms the absence of seawater intrusion component and the role of the fault as a hydraulic barrier. These 18O and 2H values deviate from the GMWL confirming an evaporation effect and colder infiltration conditions and reveal strongly a possible mixing with the Nubian Sandstone in the region. The 3He/4He ratio confirms a mantle contribution of 2% from the total He components.

Investigation of Hydrochemical Parameters of Water Resources in Kamarderaz Anticline Plunge in the Southwest of IRAN

Changes in the quality of karstic water resources affected by the proximity to sources of salinity such as evaporate formations and oil brine pose major challenges to such water resources, especially in Khuzestan province, Iran. The karstic water resources of the Kamarderaz anticline plunge in Izeh city in Khuzestan province have hampered water supply management in the region. To determine water quality and the causes of water salinity in the study area, the hydrochemical parameters of the existing water resources were accordingly evaluated. To conduct hydrochemical studies, 21 samples were collected from different water sources of Kamarderaz anticline plunge in 2017–2018. To analyze the garnered data, Piper and Durov diagrams, composite graphs, ion exchange graphs, ion correlation diagrams, salinity source diagrams and ion ratios were used. The results showed that SO42−, Cl−, and Ca2+ in the water resources of the study area were likely due to several sources including carbonate minerals, gypsum dissolution, anhydrite, halite as well as oil brine. Besides, Br/Cl, I/Cl ion ratios as well as Br-Cl and SO4-Cl diagrams revealed the mixing of karstic freshwater with oil brine in the region. The result of TOC analysis also showed that hydrocarbon materials were present in the well of Atabaki (WT). Moreover, elemental sulfur and sulfur isotope analysis showed that the process of thermochemical sulfate reduction or bacterial sulfate reduction in the presence of hydrocarbons produced H2S gas, and eventually penetrated the WT and WH1.

Assessment of River-Sea Interaction in the Danube Nearshore Area (Ukraine) by Bioindicators and Statistical Mapping

There is a lack of understanding of the main drivers that form the picture of biological communities of transitional waters in deltaic ecosystems under the influence of terrestrial sources. Analysis of hydrochemical parameters in relation to phytoplankton communities in the Ukrainian part of the Danube coastal zone (in August 2018) is the focus of current work. The goal was to identify patterns in the distribution of environmental parameters (salinity and nutrients) in the area of the shipping channel through the Bystry arm, as well as to assess the state of water quality. The ecological bioindicators approach using modern statistical methods, and ecological mapping shows sufficient achievements in interpreting the results. The indicators of salinity (mesohalobes) had better describe the character of the transportation of fresh riverine waters than salinity gradient. The composition of 35 indicator phytoplankton species corresponds to 3 and 4 water quality classes in the coastal zone. High N:P ratios showed an imbalance in the ecosystem as an indicator of production and destruction processes. Statistical maps of the indicator species distribution revealed the river current’s influence on the nearshore water mass. Ecological maps of surface and bottom variables show various environmental impacts resulting from dredging in the shipping channel and excavated soil dumping. Canonical correspondence analysis (CCA) and statistical maps revealed two pools of factors with oppositely directed effects on phytoplankton: salinity, on one hand, and nutrients, on the other. Miozoa and Chlorophyta have an opposite interaction with salinity and oxygen and can be ecosystem change indicators in further analysis

Stable isotopes as a tool for determining transformation and fate of sulphur in AMD affected water bodies in Meghalaya

<p>Meghalaya, also known as ‘abode of clouds’, is a state located in north-eastern part of India, blessed with abundance of water resources. In the last few decades, extensive coal mining in different parts of Meghalaya has caused detrimental changes in the environment, particularly the aquatic systems. Acid and metal loaded effluents (also known as acid mine drainage or AMD), resulting from the exposure of sulphide mineralization to oxidizing conditions from abandoned or active mining areas, are the principal environmental problems today. Sulphate (SO<sub>4</sub><sup>2-</sup>) is a major contaminant and attracts widespread attention as the dominant form of sulphur in coal mining affected aquatic systems. The increased presence of SO<sub>4</sub><sup>2- </sup>in ecosystems affected by mining activities has immense negative environmental and human health effects. Low pH and high heavy metal concentrations have been reported from streams flowing in and around the coal mining area in Meghalaya rendering the water quality to be very poor  and unfit for use as potable water.</p><p>Stable isotopes have emerged as a promising environmental tracer to understand different environmental functions and processes. Valuable information on the sources and processes can be obtained from the stable isotope ratios of chemical elements in environmental samples as the sources and processes influence history of the samples. Stable isotopes analysis combined with hydrochemical analysis enhances our understanding of transformation and environmental fate of different compounds in water bodies and can provide precise information about factors responsible for controlling water chemistry of different water bodies.</p><p>Stable isotopes of sulphur and oxygen combined with hydrochemical parameters were used as a tool for determining origin, transformation and fate of sulphur in AMD affected water bodies in Meghalaya.The study was conducted on two rivers affected by AMD, viz. Myntdu River and Lunar-Lukha River, flowing in the Jaintia Hills region of Meghalaya. The water samples collected are analysed for hydrochemical parameters and stable sulphur and oxygen isotopes (δ<sup>34</sup>S and δ<sup>18</sup>O in aqueous SO<sub>4</sub><sup>2-</sup>). The stable isotopes of sulphur and oxygen were also analysed in the coal samples from the nearby mining areas. The result provided an insight into the transformational processes of sulphur in these two AMD affected rivers and the environmental fate of sulphur.</p>

Macrophytes as a tool for assessing the trophic status of a river: a case study of the upper Oum Er Rbia Basin (Morocco)

Macrophytes are one of the main components of the aquatic ecosystem. They are used in several countries as metrics for the ecological assessment of hydrosystems. The objective of our study was to evaluate the suitability of the Macrophyte Biological Index for Rivers (IBMR) to determine a trophic level in the upper Oum Er Rbia basin (Morocco) and to understand physicochemical parameters of water that govern the distribution of macrophyte species. CCA analysis was used to relate the distribution of macrophytes to hydrochemical parameters of water. The CCA analysis shows that the distribution of macrophytes was more correlated with abiotic parameters (EC, WT and DO) than nutrient parameters (PO4-P, NO3-N, NO2-N, NH3-N and CODMn). The recorded values of IBMR in the upper Oum Er Rbia basin indicate that the trophic level of the studied rivers ranged from “moderate” to “very high”. Pearson's correlation coefficient showed that the IBMR is more correlated with the abiotic parameters such as WT and EC and does not show any significant correlation with the content of PO4-P and NH3-N in water, which makes the IBMR index unreliable for assessing the trophic status related to phosphate and ammonia concentrations in our lotic waters.

THE STRUCTURE OF THE VARIABILITY OF THE HYDROCHEMICAL COMPOSITION OF WATER IN LAKE-TYPE RESERVOIR

A qualitative and quantitative analysis of hydrochemical parameters of water is given in order to identify the factors that determine their spatial and temporal changes in a lake-type reservoir. Water samples were taken in 2019 and 2020 from the average level in spring (April), summer (July) and autumn (September) in the first week of the month in accordance with the requirements of GOST R 51592-2000 in three sections. The first target (1) is the shallow upper part (depth from 2 to 4 m); the second target (2) is the central part (depth from 5 to 7 m) and the third target (3) is the near – dam part (depth up to 12.2 m). Statistical analysis of the obtained data was performed using the unlimited Principal component analysis (PCA) technique and the limited redundancy analysis (RDA) technique. The effects were considered statistically significant at P<0.05, and useful for discussion-at P<0.10. It was found that, despite the flood increase in the level of chemical components in the water of the reservoir, most of them meet the requirements for fishing waters, with the exception of iron, copper, manganese, zinc, nickel and lead, which exceed the MPCVR from 1.1 to 45.0 times. The total variability of the hydrochemical composition of water in the reservoir, estimated by the PCA method, depends on the season of the year by 71.4 %. A similar result was obtained by the RDA method in a model with a single regressor. When all factors are taken into account in the RDA model, the variability of the water chemical composition is affected by the season of the year by 74.3 %, the year of research by 11.1 %, and the location of the target by 1.9 %. The primary indicators of water for the proportion of unexplained variability in both the PCA and RDA methods are manganese, bicarbonates, lead and aluminum, and pH.