Ecotoxicological biotests were applied in order to evaluate their suitability as early warning systems in the continuous monitoring of lowland shallow dam reservoirs located in Central Europe. The following biotests were used: Daphtoxkit F™magna, Algaltoxkit F™, Ostracodtoxkit F, Phytotoxkit and MARA Test. The experiment was conducted from July 2010 to December 2012 in Goczalkowice Reservoir (the Vistula River, Poland), serving as a model. For the analysis, 41 out of 52 measured water indices were used to assess its toxicity to living organisms. The results of biotests were correlated with 41 hydrochemical indices of water quality. The pattern of relationships among the result of biotest and hydrochemical indices as well as Factor Analysis (FA) and Primary Component Analysis (PCA) revealed that: i) signs of ecotoxicity detected with biotests were associated with either low fl ow periods or spring surface runoff of water; ii) single events of increased ecotoxicity in the depression areas behind saddle dam pump stations appearedafter high fl ow periods; iii) elevated toxicity was accompanied by high concentrations of dissolved and suspended substances; iv) FA and PCA demonstrated correlations among the results of biotests and damming parameters, water conductivity, alkali and transitory metal metals (Ca, Fe, Cu, Zn), and several forms of nitrogen phosphorous and carbon compounds concentration. The relationships suggest that batteries of biotests may serve as a cost-eff ective tool for continuous monitoring of water quality in dam reservoirs and can detect eff ects of extreme hydrologic events, local toxic discharges, and signs of the trophic status of the reservoirs

The population of vendace ( Coregonus albula L., 1758) in many European lakes, especially in Central Europe, have declined recently as a result of lake eutrophication. The aim of the study was to (i) determine many years’ changes in the volume of vendace catches and specific physicochemical parameters of water, (ii) determine correlations between particular physicochemical parameters, and (iii) indicate hydrochemical parameters which show the greatest impact on the volume of vendace catches on the example of Lake Ińsko located in the European Central Plains Ecoregion. Principal Component Analysis (PCA) was applied to indicate the most important hydrochemical variables impact on vendace fisheries. Among them, after redundancy analysis, 6 were taken into account (total nitrogen, N-NO3, N-NO2, total phosphorus, oxygen concentration, temperature). Time series analysis revealed an increasing trend in nutrients concentration in lake. Analyses showed that fish catches were mostly negatively connected to nitrogen and phosphorus concentration. Trend analysis, based on the above-mentioned parameters, can provide prediction of vendace catches for further years with the predictability at the level of around 60% accuracy. The results of this study are very crucial to the vendace fisheries and for formulating fisheries management policies in the future in the changing hydrochemical condition of lakes.

The objective of this paper is to study the hydrochemical characteristics of Lake Dayet Erroumi (Khemisset, Morocco). Three sampling campaigns were carried out in April, July and November 2019. The temperature, pH and electrical conduct-ivity were measured in situ using Hanna Instruments HI 98280. Concentrations of calcium, magnesium, carbonate, bicar-bonate and chloride were analysed by the volumetric method. The atomic absorption technique was used to determine sodium, potassium, nitrate and sulphate. The physico-chemical analysis of the water indicates that the pH is basic. The nitrate and sulphate concentrations show that the water is of good quality according to Moroccan surface water guidelines. Furthermore, the hydrochemical facies of water is of the sodium-chloride type according to the Piper diagram. The value of the electrical conductivity indicates that the lake water has high salinity. The high mineralization of water is explained by the leaching from evaporitic rocks in the region. The principal component analysis shows that the spatial and temporal variation in salinity constitutes the major phenomenon of the hydrochemical characteristics of this lake. Salinity varies inversely with the pH value. The salinity of the water is controlled by abiotic factors (rain and evaporation). However, other parameters (pH, nitrate, carbonate and bicarbonate) depend on biotic factors. Evaporation plays a crucial role in the seasonal variation of the water chemical composition. During wet seasons, the mineralization of water decreases due to dilution by rainwater and the water level of the lake rises (high water period). During dry seasons, lake water evaporates and consequently the mineralization of the water increases, which explains the increase in salinity during the low water period.

There are several springs with the large discharge around the Watuputih Karst Hills area that playing a crucial role in supplying water for both domestic and irrigation needs. The springs are located in the fault and fold zones of the Rembang anticlinorium system. This study was designed to determine the characteristics of karst aquifers from one year of monthly spatio-temporal data on discharge parameters and physico-chemical properties (temperature, pH, EC, Ca2+, Mg2+, HCO3–) of the four major springs, namely Brubulan Tahunan, Sumbersemen, Brubulan Pesucen, and Sendang Sayuran. It used sta-tistical calculations to characterize spring discharge and hydrochemical variations, as well as bivariate correlation analysis and flow-duration curve (FDC). The variability index (Iv), variability (V), and spring coefficient of variation parameters (SCVP) classified Brubulan Tahunan and Sumbersemen as springs producing stable, fairly constant discharge with low variations but characterized Brubulan Pesucen as having unstable, varying discharge with moderate variations. The results showed gently sloping hydrograph, low variations in discharge and hydrochemical properties, a relatively prolonged re-sponse of discharge and CO2-H2O-CaCO3 interaction to rainfall, and slope changes in the FDC. In other terms, although the springs are controlled by faults and folds, they have diffuse groundwater storage system in the form of densely fractured and porous media. These findings also indicate a less developed interconnected conduit, although Brubulan Pesucen is relatively more developed than Sumbersemen and Brubulan Tahunan. The geological structure and hydraulic gradient formed between the groundwater recharge and discharge areas are proven to control the amount of spring discharge actively.

Analysis of groundwater quality in the alluvial aquifer of the lower Soummam Valley, North-East of Algeria, was realised through the application of multivariate statistical methods: hierarchical cluster analysis (HCA) in Q and R modes, factorial correspondence analysis (FCA), and principal component analysis (PCA), to hydrochemical data from 51 groundwater samples, collected from 17 boreholes during periods of June, September 2016 and March 2017. The objectives of this approach are to characterise the water quality and to know the factors which govern its evolution by processes controlling its chemical composition. The Piper diagram shows two hydrochemical facies: calcium chloride and sodium bicarbonate. Statistical techniques HCA, PCA, and FCA reveal two groups of waters: the first (EC, Ca2+, Mg2+, Cl–, SO42– and NO3–) of evaporitic origin linked to the dissolution processes of limestone rocks, leaching of saliferous soils and anthropogenic processes, namely contamination wastewater and agricultural activity, as well marine intrusion; and the second group (Na+, K+, and HCO3–) of carbonated origin influenced by the dissolution of carbonate formations and the exchange of bases. The thermodynamic study has shown that all groundwater is undersaturated with respect to evaporitic minerals. On the other hand, it is supersaturated with respect to carbonate minerals, except for water from boreholes F9, F14, and F16, which possibly comes down to the lack of dissolution and arrival of these minerals. The results of this study clearly demonstrate the utility of multivariate statistical methods in the analysis of groundwater quality.

Groundwater hydrochemistry of Algerian Sahara (Southwest, Algeria) was used to assess groundwater quality to de-termine its suitability for drinking and agricultural purposes. A total of 26 groundwater samples were analysed for 14 para-meters. Standards laboratory methods were used to determine physicochemical groundwater properties. This study shows that these pH, electric conductivity, total hardness, bicarbonate, and phosphate were within WHO limits. The concentration of magnesium ranging from 30.49 to 120 mg∙dm–3 with an average value of 67.21 mg∙dm–3. 38.56% of the water points analysed have a concentration lower than the value set by the WHO at 75.00 mg∙dm–3. It also showed that 70% of the points studied have potassium concentrations that exceed World Health Organization standards. Groundwater of Algerian Sahara is low in nitrogen (NO3–) and the higher concentration may result in various health risks. The result for this study showed that the water was to be found suitable for drinking purposes except for few samples. Piper diagram indicates that groundwater in Adrar belongs to chlorinated-sulphated, sodium and magnesium facies. The groundwater samples of Adrar present high salinity and low alkalinity fall into the field of C3S1 and C3S2. Based on the RSC values, all samples had values less than 1.25 and were good for irrigation.