Physicochemical Properties Of Water Research Articles

Effects of heating on the antibacterial efficacy and physicochemical properties of plasma-activated water

Plasma-activated water (PAW), which is the water treated by cold plasma, represents a promising strategy for food decontamination. However, studies of the influences of heating on the antibacterial efficacy and physicochemical characteristics of PAW are limited. Therefore, the present work is aimed at determining the effect of heating on the bactericidal effects and physicochemical properties of PAW. PAW (1.0 mL) was heated in a water bath at 30–80°C for 10 min. After being cooled to room temperature, the antibacterial efficacy and physicochemical properties of PAW were measured. Heating at 40–80°C for 10 min caused a significant decrease in the antibac-terial activity of PAW against Listeria monocytogenes and Salmonella typhimurium. After heating at 40–80°C for 10 min, the pH value and oxidation reduction potential (ORP) of PAW remained stable, and the level of nitrate and electrical conductivity of PAW remarkably increased, while hydrogen peroxide and nitrite contents significantly decreased. The combination treatment of PAW and mild heating (40–60°C for 4 min) showed greater anti-bacterial effect on L. monocytogenes and S. typhimurium. After the combined treatment of PAW with mild heating at 60°C for 4 min, the populations of L. monocytogenes and S. typhimurium decreased by 7.83 log10 CFU/mL and 9.35 log10 CFU/mL, respectively, which were significantly higher than that caused by PAW at 25°C or mild heating at 60°C alone. In summary, the antibacterial activity of PAW is significantly affected by the treatment temperature. This work provides a basis for the practical application of PAW in the food industry.

A mechanistic study of low salinity water-based nanoparticle-polymer complex fluid for improved oil recovery in sandstone reservoirs

Low salinity water flooding has gained tremendous attention in these days due to its cost-effectiveness and environment-friendly nature. Fine tuning of physico-chemical properties of low saline water by addition of suitable chemicals and nanoparticle (NP) can increase the oil recovery significantly because of synergistic effects. In this study, an attempt has been made to explore the benefit of adding nanoparticle and polymer into low salinity water (LSW) for increased oil recovery. Two complex chemical slugs were prepared with formation water (FW) and LSW as base fluids consisting of different concentrations of polymer and NP. The target viscosity for maximum sweep efficiency was estimated through the total minimum relative mobility concept. The rheological studies of the complex chemical slugs revealed that the addition of NP into polymer solution increased the viscosity significantly because of formation of macromolecular structure. It has been observed that a lower concentration of polymer is required to reach the target viscosity in LSW than FW. The benefits of low salinity effects over high saline formation water are evidenced by the reduction of interfacial tension (IFT), which is further reduced by addition of NP. A low IFT is always desirable for enhanced oil recovery. Contact angle showed a decreasing trend with FW, LSW and Nano fluid solutions respectively but presence of polymer in the slugs shows reverse effect on contact angle. LSW showed higher recovery as compared to FW in secondary recovery stage due to different reported mechanisms. Injection of LSW based complex fluid showed incremental recovery of 13.3 % of OOIP as compared to LSW and 22.0 % of OOIP as compared to conventional FW flooding in secondary stage. Synergistic effect of NP and polymer to form a complex macromolecular structure through hydrogen bonding and low salinity effect led to the improved oil recovery.”

Physicochemical Properties of Plasma-Activated Water and Its Control Effects on the Quality of Strawberries

In this study, the effects of plasma-activated water (PAW), generated by dielectric barrier discharge cold plasma at the gas-liquid interface, on the quality of fresh strawberries during storage were investigated. The results showed that, with the prolongation of plasma treatment time, the pH of PAW declined dramatically and the electrical conductivity increased significantly. The active components, including NO2-, NO3-, H2O2, and O2-, accumulated gradually in PAW, whereas the concentration of O2- decreased gradually with the treatment time after 2 min. No significant changes were found in pH, firmness, color, total soluble solids, malondialdehyde, vitamin C, or antioxidant activity in the PAW-treated strawberries (p > 0.05). Furthermore, the PAW treatment delayed the quality deterioration of strawberries and extended their shelf life. Principal component analysis and hierarchical cluster analysis showed that the PAW 2 treatment group demonstrated the best prolonged freshness effect, with the highest firmness, total soluble solids, vitamin C, and DPPH radical scavenging activity, and the lowest malondialdehyde and ∆E* values, after 4 days of storage. It was concluded that PAW showed great potential for maintaining the quality of fresh fruits and extending their shelf life.

Quality of Water from Hand-Dug Wells in Nembe Town, Bayelsa State, Nigeria

This study examined the quality of water supply from hand-dug wells in Nembe town, Bayelsa State using sample survey design. Data was obtained from primary sources. To assess if the quality of groundwater supplied in Nembe town is safe for domestic and drinking purposes, the physico-chemical and microbial status of the groundwater were studied. Nembe town was stratified into ten neighbourhoods and a total of ten (10) hand dug well water samples was randomly collected from each of the sampled ten neighbourhoods and analyzed for twenty-one (21) paramaters in the month of November 2019. These samples were sent to the laboratory for physico-chemical and microbial analysis. The results of the study revealed that physico-chemical paramaters such as Total Dissolved Solids (TDS), Total Suspended Solids(TSS), Sulphate (So4-2), Bicarbonate (HCo3-), Calcium (Ca), Sodium (Na), Manganese (Mn), Electrical Conductivity (EC), Iron (Fe), Chloride (CL), Nitrate (NO), Salinity, Total Alkalinity (TA) and Magnesium (Mg) are all within the permissible level of WHO and NESREA drinking water standards. Groundwater in the area have turbidity and potassium levels higher than the WHO and NESREA maximum permissible limits for drinking water standard. All the sampled hand dug wells have pH value within the permissible limit of drinking water except one which had pH value of 6.48 and considered too acidic for human consumption. Based on hardness, 70% of the groundwater samples are slightly hard water to hard water in nature. The result of the microbial analysis showed the presence of total coliforms, Total bacteria counts and fungi in all the hand dug wells. The ANOVA statistical tool was employed in testing the stated hypothesis and the results show that there is no significant spatial variation in the physico-chemical properties of water in the study area and that there is a significant spatial variation in the microbial properties of water in the study area. The result of the study was conclusive evidence that all the hand dug wells studied are not safe for domestic purpose especially for drinking as they were affected by some physico-chemical and biological parameters. Hence the affected wells call for periodic monitoring and treatment to improve the quality of the water.

Integrated Science Teaching in Atmospheric Ice Nucleation Research: Immersion Freezing Experiments.

This paper introduces hands-on curricular modules integrated with research in atmospheric ice nucleation, which is an important phenomenon potentially influencing global climate change. The primary goal of this work is to promote meaningful laboratory exercises to enhance the competence of students in the fields of science, technology, engineering, and math (STEM) by applying an appropriate methodology to laboratory ice nucleation measurements. To achieve this goal, three laboratory modules were developed with 18 STEM interns and tested by 28 students in a classroom setting. Students were trained to experimentally simulate atmospheric ice nucleation and cloud droplet freezing. For practical training, this work utilized a simple freezing assay device called the West Texas Cryogenic Refrigerator Applied to Freezing Test (WT-CRAFT) system. More specifically, students were provided with hands-on lessons to calibrate WT-CRAFT with deionized water and apply analytical techniques to understand the physicochemical properties of bulk water and droplet freezing. All procedures to implement the developed modules were typewritten during this process, and shareable read-ahead exploration materials were developed and compiled as a curricular product. Additionally, students conducted complementary analyses to identify possible catalysts of heterogeneous freezing in the water. The water analyses included: pH, conductivity, surface tension, and electron microscopy-energy-dispersive X-ray spectroscopy. During the data and image analysis process, students learned how to analyze droplet freezing spectra as a function of temperature, screen and interpret the data, perform uncertainty analyses, and estimate ice nucleation efficiency using computer programs. Based on the formal program assessment of learning outcomes and direct (yet deidentified) student feedback, we broadly achieved our goals to (1) improve their problem-solving skills by combining multidisciplinary science and math skills and (2) disseminate data and results with variability and uncertainty. The developed modules can be applied at any institute to advance undergraduate and graduate curricula in environmental science.

Alteration of physicochemical properties of tap water passing through different intensities of magnetic field

AbstractThis study reports the effect of the magnetization process on the chemical and electrical properties of tap water (TW). Also, a step in the direction of gaining a better understanding of the influence of magnetizing technique on the physicochemical properties of water exposed to several intensities of magnetic field (MF). The TW sample used in this study passed through four intensities of the MF (2,000, 4,000, 6,000, and 8,000 G) under the same conditions of temperature and pressure. Magnetized water was tested and evaluated for physical and chemical qualities after being cycled through a magnetization device for 6 h. Following the increase in the intensities of the MF, the alteration in water properties has been depicted. The results showed increase in the pH value, electrical conductivity, and some of the chemical properties. The optimum change in the properties of water were obtained when the intensity of MF reached 8,000 G. However, to assess the obtained modification of water quality from the magnetization process, the results are compared with the guideline standards of the World Health Organization. To reduce the treatment costs and increase the long-term viability of the process, the study findings suggested a strategy of water magnetization as an effective treatment technology with reduction in energy and material usage (green technology).

Adsorption at Nanoconfined Solid-Water Interfaces.

Reactions at solid-water interfaces play a foundational role in water treatment systems, catalysis, and chemical separations, and in predicting chemical fate and transport in the environment. Over the last century, experimental measurements and computational models have made tremendous progress in capturing reactions at solid surfaces. The interfacial reactivity of a solid surface, however, can change dramatically and unexpectedly when it is confined to the nanoscale. Nanoconfinement can arise in different geometries such as pores/cages (3D confinement), channels (2D confinement), and slits (1D confinement). Therefore, measurements on unconfined surfaces, and molecular models parameterized based on these measurements, fail to capture chemical behaviors under nanoconfinement. This review evaluates recent experimental and theoretical advances, with a focus on adsorption at solid-water interfaces. We review how nanoconfinement alters the physico-chemical properties of water, and how the structure and dynamics of nanoconfined water dictate energetics, pathways, and products of adsorption in nanopores. Finally, the implications of these findings and future research directions are discussed.

Bagarius bagarius, and Eichhornia crassipes are suitable bioindicators of heavy metal pollution, toxicity, and risk assessment

Water quality index (WQI) of Narora channel and health of endemic fish Bagarius bagarius and plant Eichhornia crassipes, district Bulandshahar, Uttar Pradesh, India were studied. Among the physicochemical properties of water, pH, D.O, Cr, Fe, Ni, and Cd were above the recommended standards. These factors lead to high WQI (4124.83), indicating poor quality and not suitable for drinking and domestic usage. In fish tissues, the highest metal load was reported in the liver (58.29) and the lowest in the kidney (33.73). Heavy metals also cause a lowering of condition indices. As expected, decreased serum protein (− 63.41%) and liver glycogen (− 79.10%) were recorded in the exposed fish. However, blood glucose (47.22%) and serum glycogen (74.69%) showed elevation. In the plant, roots (21.50) contained the highest, and leaves (16.87) had the lowest heavy metal load. Bioaccumulation factor (BAF) > 1, indicates hyperaccumulation of all metals. E. crassipes roots showed the highest translocation factor (TF) > 1 for Ni (1.57) and Zn (1.30). The high mobility factor (MF) reflected the suitability of E. crassipes for phytoextraction of Mn, Cd, Zn, Fe, Ni, and Cu. Moreover, Bagarius sp. consumption could not pose any non-cancer risk. Although, lower cancer risk can be expected from Ni and Cr.

Bacterial community in African catfish (Clarias gariepinus) recirculating aquaculture systems under different stocking densities

Fish farming in Recirculating Aquaculture Systems (RAS) is a sustainable and efficient practice to produce fish. Knowledge of microbial communities, particularly harmful pathogens on fish, is required to better understand microbiological processes occurring at different RAS compartments and to optimize the overall RAS management. In this study, we assessed the influence of differentClarias gariepinusstocking densities in RAS on the water microbiome composition. Molecular targeting the V3-V4 16S rRNA hypervariable region was used to infer Amplicon Sequence Variants (ASV), identify microbes, and assess their abundance and diversity. We identified bacterial pathogens in the rearing environment associated with common fish farming practices. Our findings show that microbiomes differ across all systems (high, medium and low stocking densities) and within sampling points (water inflow, outflow and sedimentation tank). The medium-density system had the most fish biomass, resulting in high ASVs cumulative abundance. In water samples from high- and low-density systems, we discovered a wide range of phyla, withMycobacteriumsp. being the most common potentially pathogenic group. We discuss the effects of fish biomass and water physicochemical properties on the microbiome.

Are Intermittent Rivers in the Karst Mediterranean Region of the Balkans Suitable as Mayfly Habitats?

Intermittent rivers, common in dry parts of the world, such as the Mediterranean region, are hydrologically harsh habitats characterized by periodical flow cessation. Ephemeroptera are aquatic insects common in both lotic and lentic waterbodies, where they show a high sensitivity to anthropogenic modifications of their habitat. Therefore, they are widely used as bio-indicators of the freshwater’s health. However, mayfly assemblages and their ecological requirements in the karst Mediterranean intermittent habitats are still not sufficiently known. Thus, the work presented here includes an analysis of mayfly assemblages and their relationship with environmental variables in the lotic phase of four intermittent rivers in the karst Mediterranean region of Croatia. Considering that the studied intermittent rivers are hydrologically extreme environments, a total of 12 recorded mayfly species could be considered as rather high species richness. Nevertheless, species richness per river was quite low (between three and six), and was highly influenced by river morphology, physico-chemical water properties (especially conductivity, water velocity, and concentrations of dissolved oxygen), and anthropogenic pressures. Our results could contribute to the mayfly species protection in karst Mediterranean intermittent freshwater habitats in the Balkans, as well as to the development of conservation measures for those threatened habitats.

CONCENTRATION LEVELS OF PHYSICO-CHEMICAL PROFILES AND QUALITY ASSESSMENT OF GROUNDWATER: A CASE STUDY OF SOUTHERN IJAW, BAYELSA STATE, SOUTHERN NIGERIA

This study examined the concentration levels of physico-chemical profiles of groundwater quality of communities in Southern Ijaw Local Government Area of Bayelsa State, Nigeria. The seasonal variation of groundwater quality were evaluated. Fifteen (15) communities within the LGA were selected and groundwater from hand-dug well (HDW-15samples) and borehole (BH-15samples) was sourced during the wet season (July) and dry season (March) and analyzed for seasonal variations. The difference in the mean of the parameters investigated during the dry and wet season revealed the difference in concentration level as influenced by the season attributes. The HDW showed a very strong correlation in wet and dry season physicochemical properties as well as no significant difference in the physicochemical properties of groundwater at both seasons. Also, the results of borehole water sample showed a very strong correlation in wet and dry season physic-chemical properties with no significant difference in the physicochemical properties of water at both seasons. There are similarities in various natural and anthropogenic activities influencing the concentrations during both wet and dry seasons. The mean values of parameters such as pH, TDS, TSS, Bicarbonate, Cl, SO34, NO2, Ca, Mg, K and P are within the permissible limit of WHO and NSDWQ during both seasons except TC.

Longitudinal Changes in Diverse Assemblages of Water Mites (Hydrachnidia) along a Lowland River in Croatia

Water mites are the most diverse freshwater group of Acari and despite growing research interest in the ecology of this group, the environmental influences along longitudinal river gradients on their assemblages are still not fully understood. The objective of this study was to determine how physico-chemical water properties and hydromorphological alterations affect the composition and distribution of water mite assemblages along a longitudinal river gradient. Macroinvertebrate samples were collected from 20 study sites distributed longitudinally along the entire 106 km course of a lowland river (Bednja River) in the Pannonian Lowlands ecoregion of Croatia. At each site, 20 samples were collected with regard to microhabitat composition (+400 samples in total). In parallel with the sampling of macroinvertebrates at each site, the physico-chemical water properties were measured and the degree of hydromorphological alteration was assessed (European Standard EN 15843:2010). Both the number of taxa and water mite abundance were found to increase significantly with increasing distance from the source. However, the assemblages from the upper reaches and those from the lower reaches shared very few species, emphasizing the importance of species-level identification. Water mite species richness and diversity were not reduced with increased levels of variables associated with organic enrichment and eutrophication pressures. Similarly, hydromorphological alteration did not reduce either water mite abundance or species richness and was positively correlated with both. Furthermore, a correspondence analysis on water mite microhabitat preferences revealed that 32% of all species were positively associated with artificial microhabitats (technolithal). These positive associations may be the result of reduced competitive pressure from other larger invertebrates, as well as a possible preference for higher velocity, which usually occurs on smooth technolithal surfaces. A total of 22 different species of water mites were found during this study, 8 of which (or 36% of all species found) were recorded for the first time in Croatia.

Effects of Cassava Wastewater on Opa Stream in Ile-Ife, Nigeria

This study is aimed at determining the impacts of indiscriminate disposal of cassava wastewater into the nearby stream. The cassava wastewater quality was tested in accordance with the standard methods for the examination of water and wastewater for both physical and chemical parameters such as temperature, conductivity, hardness, pH and turbidity. The physicochemical properties of both water and cassava wastewater was conducted before and after the disposal of the cassava wastewater and the result of the experiments showed that the effluent is acidic with pH of 3.8 and of high conductivity of 40 µs/cm2. The cyanide content is also very high with 11.88 mg/kg as compared to 1.5-3.5 mg/kg recommended by WHO. The total solids, and total suspended solids are also in high range of 2000 mg/kg and 3000 mg/l respectively. Its hardness is 800 mg/l, chloride 2000 mg/l. The dissolved oxygen was not detected. The physicochemical properties of the after experienced significant difference (p<0.05).

Using machine learning models to assess the population dynamic of the freshwater invasive snail Physa acuta Draparnaud, 1805 (Gastropoda: Physidae) in a tropical urban polluted streams-system

The poor understanding of the spread conditions and the geographical patterns of the exotic freshwater snail Physa acuta in sub-Saharan Africa urban streams makes it difficult to design and implement sustainable management tools, especially in deteriorating global and local environments. This study aimed to determine the ecological preferences and the major environmental variables associated with P. acuta abundance, occurrence and distribution in Douala urban streams-system using modelling approaches based on discriminant factor analysis, canonical Spearman correlation and random forest tree models. We inductively define four clusters for snail’s distribution along a geographical and upstream–downstream pollution gradient. Snail’s specimens were collected monthly over a 13-month period in two forest and ten urban sites using a long-handled net (30x30cm side, 400-µm mesh). Meanwhile, measurements of the physicochemical properties of water and streambed sediment were taken. In addition, ten metal contents were determined in P. acuta tissues to assess its ability of bioaccumulation of heavy metals. Results revealed that urban streams of Douala are adversely impaired, especially downstream of industrial effluents. Discriminant factor analysis and random forest regression trees model showed that dissolved oxygen, biochemical oxygen demand, alkalinity, salinity, pH, water depth, wetted width, zinc, iron, cadmium, encumbrance rate of the sediment and sediment types (high sandy mud, sandy mud and muddy sand) were the major environmental variables responsible for structuring P. acuta distribution. Abundances decline drastically following pollution gradient, with great decrease observed in juvenile size classes. High contents of metals were detected in P. acuta tissues, especially downstream of industrial effluents. This study highlights that P. acuta spread in Douala urban-streams system is structured by key environmental variables related to an upstream–downstream pollution gradient. Therefore management plans should emphasize on proper disposal ways of industrial wastes, and stakeholders should take responsible actions in water pollution control and implement the polluter-payer principle.

Bacterial microbiome and physicochemical properties of irrigation water and soil in Chonto type tomato from Boyaca, Colombia

Tomato cultivation ranks fourth in vegetable production in Boyaca. The largest production of Chonto tomato in greenhouses is supplied by the Alto Chicamocha irrigation and drainage district since it is the main agricultural production unit for the department. To investigate the physicochemical conditions of the soil and irrigation water in the crop and bacterial communities associated with the greenhouse Chonto tomato crop, a total of 15 crops of 50×50 m located within the irrigation and drainage district of Alto Chicamocha were analyzed. Soil and irrigation water samples were analyzed and the bacteriome associated with the crop rhizosphere was characterized. From the physicochemical results obtained, we observed a significant relationship between crop attributes, the physicochemical properties of soil, and irrigation water in the different study zones. On the other hand, in the bacterial composition associated with the crop (soil and irrigation water), a relationship was found between the genera Sphingomonas spp. and Sphingobium spp. with crop quality for the different crops evaluated.

Heavy Metal Concentration, Physicochemical and Biological Properties of Water Collected from Different Schools Along Airport Road, Abuja

Fifteen water samples from Well and Boreholes were collected from different schools located in some communities along Air Port road, Abuja and were analyzed for heavy metals concentration, Physicochemical and biological properties using standard methods. The result of the heavy metal concentrations shows; Cd in mg/l (0.0883-0.1113), Fe in mg/l (0.0300-0.2298), Zn(0.0000-0.8888), Mn in mg/l (0.0497-0.4598), Cu in mg/l (0.000-1.6427) and Pb in mg/l (0.0000 -1.5453). The physicochemical properties showed; Colour-Colourless, Odour- objectionable, Temperature oC (21-31), Alkalinity in mg/ml(1.5-7.3), Acidity in mg/ml(0.8-2.2), Hardness in mg/ml ( 1.2-3.6), Appearance ( Some are clear and some are not clear), pH (5.91-7.56), TDS in mg/l (80-2080), Turbidity in NTU (0.2-3.1) Conductivity in mg/l(123-9385) NH3 in mg/l(0.014-0.077), SO42- in mg/l(25.87-186.2) and F– in mg/l (0-0.38). The microbiological results shows that TBC ranges between 30-TNTC, TCC ranges between Nil-30 and E coli is Nil in all the samples. Total Dissolved Solid was found to be above the SON limits. Concentration of Fe, Cd and Pb were also above SON limits. Total Coliform Counts and Total Bacteria counts were also above the recommended limits by SON. Considering the high level of some of the physicochemical and microbiological parameters and the high concentration of Pb and Cd, the water is presumed unfit for drinking, cooking and pharmaceutical uses.

ОЦІНКА КОНКУРЕНТОСПРОМОЖНОСТІ ЗАКЛАДІВ РЕКРЕАЦІЇ ЧЕРКАСЬКОЇ ОБЛАСТІ

Purpose. The purpose of the article is the analysis of the recreational potential of the Cherkasy region, the characteristics of the activities of institutions that specialize in medical and health tourism, and the determination of their spatial structure. Methods. General scientific methods, namely analysis, synthesis and generalization, were used for the research. The sources of information for the research are the scientific works of specialists whose research is related to medical and health tourism, as well as data on recreational facilities of the Cherkasy region, posted on the Internet. Results. Prerequisites for development and natural healing factors underlying the operation of recreation facilities in Cherkasy region have been established. Medical and health facilities of Cherkasy Region are mainly represented by sanatoriums, preventive sanatoriums and recreation centers. It was found that sanatoriums and health facilities are located unevenly on the territory of the region and are concentrated mainly near the coast of the Kremenchug Reservoir. The existing material and technical base of medical and health facilities of the Cherkasy region was studied and the idea of their range of services was expanded. Scientific novelty. The activities of the most famous medical and health facilities of the Cherkasy region were analyzed. The spatial structure was clarified and the main physico-chemical and therapeutic properties of mineral waters used by recreation facilities for the treatment and prevention of various diseases were revealed. Proposals have been made to expand the range of services of institutions. The practical significance. The results of the research highlighted in the article can be used by employees of recreation facilities of Cherkasy region and other medical and health centers of Ukraine, as well as within the educational process by students of specialties 242 "Tourism", 014.07 "Secondary education (Geography)" and others in order to expand their understanding about the resource and recreational potential of the Cherkasy region.

Phytoremediation of xenobiotics – A green approach for the treatment of domestic wastewater

Remediation of xenobiotics from wastewater is highly essential due to its harmful impacts. Several chemical and physical processes are used to recover xenobiotics from wastewater, including ion exchange, reverse osmosis, electrodialysis, and ultrafiltration. However, the biological method of employing microalgae, has aroused the scientific community’s interest due to its cheap operating costs and effectiveness in absorbing and/or removing organic and elemental contaminants from wastewater. Chlorella vulgaris was used as a biological absorbent, in the remediation of domestic wastewater (DWW). The results of this work indicated that C. vulgaris, effectively eliminated pollutants and improved the physicochemical characteristics of wastewater such as pH, DO, alkalinity. Simultaneously, it also decreased BOD, COD, suspended solids, heavy metals (HMs) such as iron (Fe), zinc (Zn), cadmium (Cd), mercury (Hg), copper (Cu), lead (Pb) and nutrient load (phosphate and nitrate) of DWW. Effective remediation of the pollutants was attained within 4h of C. vulgaris cultivation. The removal of toxic compounds such as 4-methoxy carbonyl benzo hydrazide, benzamine 4,4’ methylene bis, acetamide, and N-(2-methyl phenyl), was confirmed with GC-MS analysis. The removal of polysulfides and aliphatic bromo compounds was evident from the FTIR studies. Pearson’s correlation analysis showed a positive correlation between physicochemical variables and algal biomass. Hence, the current study recommends biological wastewater treatment,by utilizing C. vulgaris as an effective and eco-friendly option, for removing pollutants and restoring the physicochemical properties of water.

How accurate is the remote sensing based estimate of water physico-chemical parameters in the Danube Delta (Romania)?

The current paper estimated the physico-chemical properties of water in the Danube Delta (Romania), based on Sentinel 2 remote sensing data. Eleven sites from the Danube Delta were sampled in spring and autumn for three years (2018-2020) and 21 water physico-chemical parameters were measured in laboratory. Several families of machine learning algorithms, translated into hundreds of models with different parameterizations for each machine learning algorithm, based on remote sensing data input from Sentinel 2 spectral bands, were employed to find the best models that predicted the values measured in laboratory. This was a novel approach, reflected in the types of selected models that minimised the values of performance metrics for the tested parameters. For alkalinity, calcium, chloride, carbon dioxide, hardness, potassium, sodium, ammonium, dissolved oxygen, sulphates, and suspended matter the results were promising, with an overall percentage bias of the estimates of +/- 10% from the observed values. For copper, magnesium, nitrites, nitrates, turbidity and zinc the estimates were fairly accurate, with percentage biases in the interval +/- 10% - 20%, whereas for detergents, led, and phosphates the percentage bias was higher than 20%. Overall, the results of the current study showed fairly good estimates between remote sensing based estimates and laboratory measured values for most water physico-chemical parameters.

Heavy Metals Concentration in Some Selected Dumpsites and Groundwater in Calabar, Cross River State, Nigeria

Heavy metals concentration in soil from dumpsites and borehole water in Calabar, Nigeria was analysed. Four dumpsites: Lemna (008°21'55.912"E and 05°2'08.725"N), Nassarawa (008°21'35.168"E and 05°4'51.544"N), University of Calabar female hostel (008°20'57.937"E and 04°56'16.612"N) and Goldie market (008°20'29.34"E and 04°56'29.198"N) were selected as sampling locations while a plot of land (008°21'43.9"E and 040'58.04 227"N) was selected as a control which were labeled S1, S2, S3, S4 and PC respectively. Soil and water samples were collected for a period of twelve months following a standard procedure and analysed for heavy metals using atomic absorption spectrophotometer (AAS) while physicochemical properties of water were analysed using their respective meters. The results obtained showed that in dumpsites soil: Cadmium was the highest occurring metal with a mean concentration of 1.457±0.493 mg/kg in S4 while As in S1 was the lowest occurring metal with a concentration of 0.001 ± 0.000 mg/kg and Hg was below detection limit in all sampling locations. In water: Chromium was the highest occurring metal with a concentration of 0.006 ± 0.001 mg/l and the lowest was Cobalt and Lead with concentrations of 0.001 ± 0.000 in about all the sampling locations while Arsenic and Mercury were below detection limit in all the sampling locations. Cd, Pb and Cr in S4 soil, Cd and Cr in S4 water and TDS, electrical conductivity and hardness of water from all dumpsites were above the WHO limit while strong positive correlation was found between some heavy metals concentration in soil and water.