Seasonal Changes In Water Quality Research Articles

Evaluation of the Aquatic Oligochatea Fauna and Seasonal Changes in Water Quality of the Büyükçekmece Dam Lake, which Provides Water to İstanbul

This study was conducted at 4 stations in Büyükçekmece Dam lake in 2020. In this study, water and Oligochaeta samples were collected seasonally. Parameters such as secchi disk depth, water temperature, dissolved oxygen, pH, electrical conductivity, salinity, total hardness, nitrite nitrogen, phosphate and nitrate nitrogen were measured. Water quality parameters were qualified by SKKY (2004) ve TSWQR (2021). Also, the study, Limnodrilus hoffmeisteri (Claparède, 1862) and Limnodrilus udekemianus (Claparède, 1862) species belonging to Oligochaeta were found in the dam lake. The number of individuals per m2 and % dominance ratios of species were also calculated. It is recommended that similar and more comprehensive studies be carried out periodically in the dam lake to monitor the water quality of the dam lake regularly and to determine the benthic macroinvertebrate fauna.

Assessing seasonal changes in water quality using various indices in Chenab River and its tributaries (J&K)

The present study involves the analysis of thirteen physiochemical parameters (pH, temperature, electrical conductivity, total dissolved solids, turbidity, alkalinity, hardness, calcium, magnesium, dissolved oxygen, biological oxygen demand, sulphate and nitrate) and five heavy metals (chromium, zinc, arsenic, lead and cadmium) from Chenab River and its tributaries (Neeru and Bichleri) at Ramban and Doda district, J&K. The analysis was done for two different seasons i.e. summer (June) and winter (December), 2022. The current investigation indicated that all the physiochemical parameters were in the permissible limit in both the seasons except few parameters (Ca, Mg, turbidity). In the analysis of heavy metals in both the seasons, it was found that there was no heavy metal contamination in all sampling sites except the Cr concentration which was found to be higher in all sites (except SXII) in summer season. The detailed analysis involved the calculation of various water quality indices which graded water quality under ‘good’ category as per WQI value whereas CPI and HPI value showed moderate to high pollution level in water during summer season. The study showed the seasonal variation in water quality parameters and thus encourage the need for regular monitoring of water quality to reduce pollution level.

Seasonal variation of the water quality in an intermittent river perennified by hydraulic work: a case study of the Terra Nova river basin, Northeast Brazil

The hydrographic basins inserted in the Brazilian semi-arid region tend to aridization and intermittency due to climatological and geological conditions, suffering great anthropic pressure and experiencing seasonal changes in water quality. The aim of this study was to analyze the seasonal variation of the water quality in an intermittent river perennified by hydraulic work: a case study of the Terra Nova river basin (TNRB), located in the state of Pernambuco, Brazil. Physical, chemical and biological parameters were analysed. Water samples were collected at eight sampling points in the TRNB, from 2009 to 2022, totaling 26 campaigns. The Water Quality Index (WQI) adapted by the Environmental Sanitation Technology Company of the State of São Paulo (CETESB) was applied. The results were evaluated spatially and temporally. It was observed that in most campaigns there was no water at the monitoring points, both in the rainy season (77.8%) and in the dry season (73.5%). During the sampling period the WQI ranged from Excellent (81) to Bad (24) in the TNRB. Point Q06 stood out from the others, presenting the only WQI classified as Excellent. With regard to seasonality, the dry season ranged from Excellent (81) to Bad (24), while in the rainy season it ranged from Good (78) to Bad (22). To improve water quality it is necessary to invest in basic sanitation in the TNRB municipalities, environmental recovery, environmental education and monitoring with the aim of mitigating conflicts and impacts.

Assessment of the correlation between the nutrient load from migratory bird excrement and water quality by principal component analysis in a freshwater habitat

Waterbirds depend on a dispersed network of wetlands for their annual life cycle during migration. Climate and land use changes raise new concerns about the sustainability of these habitat networks, as water scarcity triggers ecological and socioeconomic impacts threatening wetland availability and quality. During the migration period, birds can be present in large enough numbers to influence water quality themselves linking them and water management in efforts to conserve habitats for endangered populations. Despite this, the guidelines within laws do not properly account for the annual change of water quality due to natural factors such as the migration periods of birds. Principal component analysis and principal component regression was used to analyze the correlations between the presence of a multitude of migratory waterbird communities and water quality metrics based on a dataset collected over four years in the Dumbrăvița section of the Homoród stream in Transylvania. The results reveal a correlation between the presence and numbers of various bird species and the seasonal changes in water quality. Piscivorous birds tended to increase the phosphorus load, herbivorous waterbirds the nitrogen load, while benthivorous duck species influenced a variety of parameters. The established PCR water quality prediction model showed accurate prediction capabilities for the water quality index of the observed region. For the tested data set, the method provided an R2 value of 0.81 and a mean squared prediction error of 0.17.

Seasonal Water Quality Changes and the Eutrophication of Lake Yilong in Southwest China

To better understand the seasonal variation characteristics and trend of water quality in Lake Yilong, we monitored water quality parameters and measured nutrients, including the water temperature (WT), Chlorophyll-a (Chl-a), dissolved oxygen (DO) and pH from September 2016 to May 2020, total nitrogen (TN) and total phosphorus (TP) from October 2016 to August 2018. The results showed that the lake water was well mixed, resulting in no significant thermal stratification. The DO content was decreased in the northwest part of the lake during September and October, resulting in a hypoxic condition. It also varied at different locations of the lake and showed a high heterogeneity and seasonal variability. The Chl-a concentration in Lake Yilong demonstrated seasonal and spatial changes. It was maximum at the center and southwest area of the lake in January. However, in the northwest part of the lake, the maximum value appeared in September and October. The content of TN in the rainy season increased by 75% compared with that in dry season and TP content show a downward trend (from 0.11 mg/L to 0.05 mg/L). The comprehensive nutrition index evaluation shows that the water quality of Lake Yilong in 2016 was middle eutrophic (TLI = 60.56), and that in 2017 (TLI = 56.05) and 2018 (TLI = 56.38) was weak eutrophic, showing that the nutritional status has improved. TN remained at a high level (2.15 ± 0.48 mg/L), water quality needs further improvement. Based on our monitoring and analysis, it is recommended that human activities in the watershed of the lake should be constrained and managed carefully to maintain the water quality of the lake and adopt effective water quality protection and ecological restoration strategies and measures to promote continuous improvement of water quality, for a sustainable social development.

Hydrochemical appraisal of surface water from a subtropical urban river in southwestern Bangladesh using indices, GIS, and multivariate statistical analysis.

The Gorai River is a significant river in Bangladesh's southwestern region, where residents make great use of the water despite a lack of adequate and reliable information concerning water quality and pollution levels. Thus, the goal of this research was to examine the spatio-temporal variations in water quality and determine whether it was suitable for drinking, agriculture, industrial, or livestock purposes, as well as the influencing factors and potential sources of water pollution. Surface water samples were collected in wet and dry seasons from ten sampling sites, and twenty water quality parameters were evaluated. The results showed that some studied water quality parameters, e.g., temperature, electrical conductivity, alkalinity, and nitrate, exceeded the maximum allowable limit. Water quality index values exhibited that the water quality of all sampling sites was found to be poor to very poor during the wet season, while only St-4 and St-5 were found to be poor and the rest of the investigated sites were good category during the dry season. Based on sodium adsorption ratio, soluble sodium percentage, residual sodium carbonate, residual sodium bicarbonate, and permeability index values, it was depicted that river water was suitable for irrigation purposes, but when compared to Kelly's ratio (KR) and magnesium hazard ratio values, river water was found to be unfit for irrigation. Moreover, potential salinity (PS) and sodium-to-calcium activity ratio (SCAR) values allow the water as moderately suitable for use in irrigation purposes. Langelier saturation index (LSI) and aggressive index (AI) values revealed that the river water was under saturated to supersaturated and moderate to non-aggressive in nature. However, Ryznar stability index (RSI), Puckorius scaling index (PSI), and Larson-Skold index (LS) values describe whether the water was high or severely corrosive, signifying its inappropriateness for industrial consumption. Principal component analysis (PCA) analysis depicted that the fluctuations in water quality are mostly related to point and non-point contaminations, such as urban and industrial effluent discharged and agricultural runoff of fertilizers. Cluster analysis (CA) revealed relative geographical and seasonal changes in water quality, showing the impact of hydrological changes and contamination.

Water quality analysis using the CCME-WQI method with time series analysis in a water supply reservoir

Abstract The quality of the drinking water source reservoirs has always been a research hotspot. However, few have studies focused on the water quality of reservoirs over a relatively long period with time series analysis. In this paper, based on water quality and hydrological data from 2010 to 2020, considering 8 water quality parameters, CCME-WQI with time series analysis was used to explore the interannual and seasonal changes in water quality in the Weishui Reservoir. Furthermore, the main factors affecting water quality were discussed through correlation analysis. The ARIMA model is used to predict water quality in the future. The results show that the water quality was seriously polluted from 2012 to 2013. After 2018, the water quality gradually improved and stabilized. In addition, the water quality is affected by inflow, showing the characteristics of poor water quality in summer and winter. The key parameters affecting water quality are TN and TP, which are almost 2 times higher than the grade II standard of water quality standard. Through the ARIMA model, it is predicted that CCME-WQI is maintained at 80.46 indicating that the water quality will be stable in the future.

Spatiotemporal Evaluation of Water Quality and Hazardous Substances in Small Coastal Streams According to Watershed Characteristics

In this study, spatial and temporal changes of eight water quality indicators and 30 types of hazardous substances including volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, and inorganic matters for the small coastal streams along the West Coast of South Korea were investigated. In coastal streams with clear seasonal changes in water quality, larger watershed areas led to greater contamination by particulate matter (i.e., suspended solids, r = 0.89), and smaller watershed areas led to greater contamination by organic matter (i.e., BOD, r = −0.78). The concentration of VOCs and pesticides was higher in agricultural areas, and those of SVOCs and metals were often higher in urban areas. According to the principal component analysis (PCA), during the wet season, the fluctuation in the water quality of coastal streams was higher in urban areas than in agricultural areas. Furthermore, coastal streams in residential areas exhibited higher levels of SVOCs, and those in industrial areas exhibited higher levels of metallic substances. Based on these results, the spatial and temporal trends of water quality and hazardous substances were obtained according to watershed characteristics, thereby clarifying the pollution characteristics of small-scale coastal streams and the major influencing factors.

Integrated Approach to Quantify the Impact of Land Use and Land Cover Changes on Water Quality of Surma River, Sylhet, Bangladesh

This study aims to assess the impacts of land use and land cover (LULC) changes on the water quality of the Surma river in Bangladesh. For this, seasonal water quality changes were assessed in comparison to the LULC changes recorded from 2010 to 2019. Obtained results from this study indicated that pH, electrical conductivity (EC), and total dissolved solids (TDS) concentrations were higher during the dry season, while dissolved oxygen (DO), 5-day biological oxygen demand (BOD5), temperature, total suspended solids (TSS), and total solids (TS) concentrations also changed with the season. The analysis of LULC changes within 1000-m buffer zones around the sampling stations revealed that agricultural and vegetation classes decreased; while built-up, waterbody and barren lands increased. Correlation analyses showed that BOD5, temperature, EC, TDS, and TSS had a significant relationship (5% level) with LULC types. The regression result indicated that BOD5 was sensitive to changing waterbody (predictors, R2 = 0.645), temperature was sensitive to changing waterbodies and agricultural land (R2 = 0.889); and EC was sensitive to built-up, vegetation, and barren land (R2 = 0.833). Waterbody, built-up, and agricultural LULC were predictors for TDS (R2 = 0.993); and waterbody, built-up, and barren LULC were predictors for TSS (R2 = 0.922). Built-up areas and waterbodies appeared to have the strongest effect on different water quality parameters. Scientific finding from this study will be vital for decision makers in developing more robust land use management plan at the local level.

Assessment of the Seasonal Water Quality Changes in Semi-Urban Surface Tanks of Noyyal River Basin

Aims: The history of Noyyal river in Coimbatore is known for water quality and taste since the colonial period. The river water is used mainly for drinking, irrigation and industrial purposes to districts of Coimbatore, Tiruppur and Karur with many anaicuts and tanks. In the recent past due to urbanization and industrialization the river water has been polluted in the greater extend.
 Place and Duration of Study: The study was conducted to investigate the water quality status of five important upper reach semi-urban tanks of Noyyal river basin in the year 2020 -2021.
 Methodology: We have collected the sample season wise in the five tanks and analyzed for pH, EC, TDS, TSS, total hardness, alkalinity, chlorides and sulphates as well as heavy metals such as zinc, copper, cadmium and lead.
 Results: The results of our water quality analysis showed that most of the parameters are above the maximum permissible limits of CPCB standards for drinking water in India. The heavy metals concentrations were many folds higher than the CPCB permissible limits. The correlation analysis, Anova and PCA showed that the EC and TDS, alkalinity and sulphates, chlorides and sulphates and alkalinity and chlorides had higher correlation in the water quality analysis and they are interrelated to one another. In the monsoon season the pollution status is less and during summer season the pollution load is higher in the all tanks. During the monsoon season because of intensive water flow dilute the pollution load as well high rate of degradation due to high dissolved oxygen content of river water. Since, he Noyyal river is seasonal river, during summer, there would be very less or no flow of water into the tank increase the pollution load. The Narasampathy tank had comparatively less pollution than other tanks, since, it is the first tank in the upper reach of the Noyyal basin and has less inhabitants and industry.
 Conclusion: We concluded that the tanks are polluted due to urbanization and industrialization in and around the Noyyal basin and there is an urgent need to tackle this problem by making eco-friendly and economically viable treatment system to sustain the water quality.

Risk Assessment of Water Intakes in South-Eastern Poland in Relation to the WHO Requirements for Water Safety Plans

Since 2017, risk assessments for water intakes in Poland have provided the basis for decisions to establish indirect water protection zones. The preventive, risk-based approach and the related risk minimization measures are required under the provisions of the Drinking Water Directive (DWD) of the European Parliament and of the Council of 16 December 2020 on the quality of water intended for human consumption. This approach is in line with the World Health Organization (WHO) recommendations for water safety plans. The aim of this study was to present a methodology and to carry out a risk assessment of the threats to surface water intakes, which in Poland, should be completed by the end of 2022. Risk assessments were performed for four onshore-type surface water intakes located in south-eastern Poland. The results were presented in aggregate form, which enabled clear presentation and conclusions. It was found that the greatest risks are associated with seasonal changes in water quality (mainly high turbidity and water blooms), unregulated sewage management, the occurrence of floodwater flows and catastrophic events caused by the potential failure of wastewater treatment plants. Based on the results of the risk assessment, the need to establish new, or to adjust the existing, protection zones for the analyzed water intakes was identified.

Seasonal variation in water quality, plankton diversity and microbial load of tropical freshwater lakes in Nigeria

Seasonal changes significantly affect tropical ecosystems; hence, verification of how these changes affect water quality is important for waterbodies that serve as water and food sources, particular as such changes are often associated with shifts in plankton diversity and microbial loads. This study assessed the seasonal changes in water quality, plankton diversity and microbial load in four lakes serving as sources of drinking water. Temperature, hardness and phosphate concentration were elevated in the dry season, and pH, biochemical oxygen demand, transparency, turbidity, total dissolved solids, conductivity, alkalinity and nitrate concentrations were elevated in the wet season. A phytoplankton analysis revealed that Chlorophyta, Bacillariophyta, Cyanophyta and Dinophyta were most common, with the families Desmidiaceae, Microcystaceae and Euglenaceae (phylum Euglenophyta) displaying dominance. For zooplankton, Rotifera was most common, with Branchionidae dominating the lakes in both seasons. In the wet season, Chlorophyta, Cyanophyta, Bacillariophyta and Dinophyta dominated, with Aphanizomenonaceae and Microcystaceae the most diverse families. Disease-causing pathogens, Ascaridae, Trichuridae and Ancylostomatidae (phylum Nematoda), were detected during periods of high rainfall. The waters in the dry season had higher microbial loads than in the wet season, ranging from 1.50 to 233.50 CFU g−1 (p < 0.05). This demonstrates the seasonal variations in risk to users and underlies the importance of regular assessment of water quality particularly given the threat of seasonal changes elated to climate change.

Spatial and temporal distribution of carbon dioxide flux in Amagasaki Canal, Japan

ABSTRACT Recently, blue carbon – carbon captured by coastal ecosystems – has been gaining increased research attention for its potential to sequester anthropogenic CO2. The Amagasaki Canal, in the inner part of Osaka Bay, Japan, has high nutrient concentrations and phytoplankton abundance; primary production by phytoplankton is high in such hypertrophic environments. This could lead to the enhanced absorption of atmospheric CO2. This study investigated the temporal changes and spatial variability in water quality and CO2 flux in the Amagasaki Canal, and it analyzed factors affecting the partial pressure of CO2 (pCO2) in canal water using covariance structure analysis. The CO2 flux in the canal varied between −24.9 and 66.8 mmol-C/m2/d. There were seasonal changes in water quality, with a tendency of CO2 release during autumn and winter. In spring and summer, when phytoplankton were active and chlorophyll-a concentrations were high, concentrations of dissolved inorganic carbon were low and atmospheric CO2 was absorbed into the water. Covariance structure analysis indicated that biological processes indirectly influenced pCO2 via pH and dissolved oxygen concentrations, pointing to the contribution of the primary production rate as part of the biological processes.

Pollution in the interflow from a simple landfill in a mountainous and hilly area in Southwest China

Simple landfills lack pollution prevention measures and therefore continuously release pollutants into the surrounding environment. There are a large number of simple landfills in the mountainous and hilly areas in China, and the interflow accounts for a large proportion of runoff. However, the pollution in the interflow stemming from the simple landfill has not been extensively studied. Here, the pollution of the interflow caused by the simple landfill near the Yunxi Town Landfill in the mountainous and hilly region in Southwest China was studied. The composition and pollution release potential of aged refuse in the landfill were determined, and the water quality of interflow around the landfill was monitored for five months. Seasonal changes in water quality of the interflow were observed, and the concentration of pollutants in the interflow around the simple landfill greatly exceeded the water quality standard for the local water function zoning throughout the sampling period. Specifically, the chemical oxygen demand concentrations of the interflow were 247.90 ± 81.57 mg/L, and more than 50 types of refractory organics were detected, with as many as 10 types of polycyclic aromatic hydrocarbons and Environmental Protection Agency priority pollutants. The total nitrogen concentration of the interflow was 132.45 ± 108.68 mg/L; organic nitrogen (53.27%) was the main component, followed by nitrate nitrogen (32.28%) and nitrous nitrogen and ammonia nitrogen (14.45%). The results highlight the need for the remediation of interflow around simple landfills in mountainous and hilly areas. Generally, the basic data could be used to aid the development of remediation technology.

The relationship between the presence of Helicobacter pylori and the composition of ionic and organic microelements in drinking water from Cracow.

Although the natural niche for H. pylori (Hp) is the human stomach, for widespread infection to occur this microorganism may need to survive in the external environment. Molecular techniques such as polymerase (PCR) have revealed the presence of Hp DNA in water, indicating that this environment could act as a reservoir for this bacterium. The aim of this study was to analyse the occurrence of Hp in tap water from Cracow and to examine the relationship between 26 parameters and the presence of Hp DNA due to the lack of such information related to this issue in Poland. Additional aim of this study was to determine whether the correlation between Hp DNA detection and seasonal changes of water quality in 379 water samples collected from various water treatment plants (WTPs), could be found. Water samples were subjected to PCR for glmM and cagA genes. Ionic and organic composition of microelements were determined in accordance to Polish and ISO standards. The data obtained from tests show that 212 (55.96%) objects were Hp DNA (glmM) positive and among them 145 (68.40%) waters samples revealed expression of cagA. Linear Discriminant Analysis and Principal Component Analysis were used and provided that the selected variables (p < 0.05): colour, pH, conductivity at 25°C, chlorides, nitrites, nitrates, phosphates, chlorates, chlorites, sulphates, free chlorine, sodium, magnesium, potassium, calcium, organic carbon, trichloromethane, bromodichloromethane, dibromochloroethane, total iron, ammonium ion, and ƩTMHs distinguished the water samples that contain Hp DNA and do not contain Hp DNA. We conclude that the ionic and organic composition of microelements in water might influence the presence of Hp. Thus, determination of the selected microelements may indirectly indicate or sometimes predict the presence of Hp in drinking water.

Influence of water quality on the diversity of macroinvertebrates in the Mandakini River in India

Abstract This research work was carried out from July 2018 to June 2019. WQI method was utilized to examine the seasonal changes in water quality that can indicate the potential use of water in the future. Water samples were tested from three locations along the Mandakini River. Fourteen physical and chemical parameters were analyzed. All water quality parameters were inside the admissible furthest reaches of the WHO for drinking water except turbidity, especially in the monsoon season. Twelve taxa of macroinvertebrates (Philopotamus sp., Laptophlebia sp., Isoperla sp., Diploperla sp., Tabanus sp., Hydropsyche sp., Baetis sp., Glossosoma sp., Heptagenia sp., Ephemerella sp., Psephenus sp., and Protandrous sp.) were identified in the Mandakini River. The fundamental goal of this investigation was to evaluate the seasonal effects on benthic macroinvertebrate diversity from the physicochemical variables of the Mandakini River. The study also affirmed that tourist-generated waste disposal and poisonous and dangerous chemicals from farming are the key components liable for the deterioration of water quality during the monsoon season.

The performance of diatom indices in assessing temporal changes in water quality in a large lowland river ecosystem

AbstractBenthic diatoms are often included in bioassessment programs of river health as sensitive indicators of nutrient status and pollution. Many diatom‐based indices have been developed and are frequently used to infer conditions in water quality. However, concerns have been raised regarding the robustness of these indices in riverine systems that have natural variability in environmental conditions, including seasonal change of water quality parameters, especially in terms of physical and chemical characteristics of water, which also influence diatom community composition. Here, we used three diatom‐based indices (Diatom‐based eutrophication/pollution index, EPI‐D; Biological Diatom Index, IBD; Watanabe's Index, WAT), which have previously been validated as robust for water quality assessment in China, to explore their response to temporal changes in water quality and diatom community structure in a riverine network over time. Concentrations of total nitrogen (TN), nitrate nitrogen (NO3‐N), total phosphorus (TP), temperature (t), and turbidity in April 2010 were significantly higher than in November 2007. The 141 diatom taxa we found in April 2010 were fewer than the 194 taxa we found in November 2007. On both occasions, the three diatom indices responded to same water quality variables (phosphorus and chloride or nitrogen) as reported in previous studies. Of the three diatom indices tested, EPI‐D provided the most robust measure of natural seasonal changes in water quality and indicated the phosphorus and chloride. Our study confirms that these three diatom indices are effective for evaluating long‐term water quality in large rivers.

Small Floodplain Reservoirs in the Face of Climate Change—Sink or Source of Nutrients?

Despite various water protection measures, good water quality and reduction of nutrient loads seem very distant goals, largely due to limited knowledge of processes occurring in river valleys. Our study aimed at establishing the role of small floodplain reservoirs in the eutrophication processes, in the face of recent climate changes. The content of phosphorus and nitrogen compounds was determined in sediments and water of small floodplain reservoirs, (the Vistula River Valley, Poland) using spectrophotometric and Kjeldahl’s method. Nutrient loads in sediments were linked to the texture and total organic carbon content. Seasonal changes in water quality were strictly connected to changing weather conditions, flood and drought. The concentrations of PO43− and NO3− were found to rise after summer flooding. Increases in NH4+, total phosphorus (TP) and total nitrogen (TN) were correlated with the surface water area reduction in the reservoirs, which during the year of the study was on average 62%. Therefore, small floodplain reservoirs could be considered simultaneously as sinks and sources of nutrients. On the one hand, they accumulate P and N compounds carried by the river during the flood. On the other hand, climate change cause that small floodplain reservoirs may be responsible for enhanced biomass production.

Removal of arsenic(V) by nanofiltration: Impact of water salinity, pH and organic matter

Climate change will affect water quality through a change in salinity, pH and organic matter (OM) content due to seawater intrusion, temperature change and subsurface biological processes. Therefore, a systematic evaluation of the impact of water quality variations is of particular importance to maintain the performance of a treatment process designed for drinking water. In this work, nanofiltration (NF) was investigated for the treatment of arsenic (As) contaminated water with the emphasis on water chemistry. Water salinity variations had no impact on the high rejection of As(V) with the studied NF membranes (NF270, NF90). The pH affects speciation and this significantly influenced the rejection of As(V) with NF270 (10–86%). The predominant mechanism was charge exclusion, while no effect was observed with NF90 (85–94%) where size exclusion plays the major role in rejection. The presence of humic acid (HA) in water has enhanced the rejection As(V) overall (10–20%) depending on water chemistry (pH, salinity) and membrane type. This study showed that NF technology was effective for As(V) rejection from water where seasonal changes in water quality can occur.

Assessment of Seasonal Changes in Water Chemistry of the Ridracoli Water Reservoir (Italy): Implications for Water Management

The Ridracoli artificial basin is the main water reservoir of the Emilia-Romagna region (Northeast Italy). The reservoir was made by construction of a dam on the Bidente River in 1982. It is used as the main drinking water supply of the region and for hydropower production. The physical and chemical parameterseters (temperature, pH, electrical conductivity, and dissolved oxygen) of shallow water are continuously monitored whereas vertical depth profiles of water chemical data (major anions and cations, as well as heavy metals) are available on a bimonthly base. The dataset used in this research is related to the years 2015 and 2016. Data show that the reservoir is affected by an alternation of water stratification and mixing processes due to seasonal change in water temperature, density, and the reservoir water level. In late summer and winter months, the water column is stratified with anoxic conditions at the bottom. During the spring, on the other hand, when storage is at its maximum, water recirculation and mixing occur. The reservoir is characterized by a dynamic system in which precipitation, dissolution, and adsorption processes at the bottom affect water quality along the reservoir depth column. The temperature stratification and anoxic conditions at the reservoir bottom influence the concentration and mobility of some heavy metals (i.e., Fe and Mn) and, consequently, the quality of water that reaches the treatment and purification plant. This study is relevant for water resource management of the reservoir. Assessing the seasonal changes in water quality along the reservoir water column depth is fundamental to plan water treatment operations and optimize their costs. The reservoir assessment allows one to identify countermeasures to avoid or overcome the high concentrations of heavy metals and the stratification problem (i.e., artificial mixing of the water column, new water intakes at different depths operating at different times of the year, blowers, etc.).