Volume Water Samples Research Articles

Assessing the Relationship Between Electrical Conductivity and Total Dissolved Solids of Different Water Resources in a Large-scale Irrigation Scheme in the Eastern Mediterranean Basin of Turkiye

Climate change and the growth of the population have led to changes in both the quantity and the quality of water resources. In Turkiye, a Mediterranean country, over 75% of its surface water is used for irrigation. Given the average annual precipitation (574 mm) of Turkiye, except for the Black Sea Region, all arable land in the country relies on irrigation to maintain sustainable food production. Agriculture constitutes 6% of Turkiye’s gross domestic product (GDP), with exports including crops such as cotton, corn, cereals, pulses, oilseeds, nuts, citrus orchards, and various fruits. As a result, the water provided for irrigation in any irrigation system must meet acceptable water quality standards to ensure sustainability of irrigation and food security. This study aims to a) investigate two essential irrigation water parameters: Electrical Conductivity (EC) and Total Dissolved Solids (TDS), and b) evaluate their empirical relationship using samples collected from various water sources within a large-scale irrigation district, covering an area of 9495 ha in the Eastern Mediterranean Region of Turkiye. Water samples were collected over one year, from October 2022 to September 2023. A total of thirteen locations were considered: a) Seven agricultural drainage channels, b) Four irrigation water sources (Seyhan River, Ceyhan River, one spring, and one groundwater well), c) Two outlets - the existing research catchment outlet and the other downstream. EC values of water samples were determined by using a benchtop type EC meter in the laboratory and TDS was determined by gravimetric method. Research results showed that there was a statistically significant correlation (r≥0.98) between EC and TDS across all water samples. The proportionality constant (K) ranged predominantly between 400-800 and was consistent with literature indicating the linear relationship between EC and TDS. Research findings suggest that the quality of different water supplies is suitable for the irrigation of all kinds of crops grown in the Lower Seyhan Plain of Turkiye. The overall characteristics of the average EC and TDS values throughout the year are reflected in the proposed equations for each water body. However, in future research, we suggest that the water sample volume should be at least 100 ml in order to provide more accurate results for water quality assessment.

Are you filtering enough? Unveiling the impact of water sample volumes on eukaryotic microbial community in freshwater lakes

The appropriate volume of filtered water samples is crucial for accurately reflecting microbial community characteristics. Previous research has shown that changes in water sample volumes significantly affect bacterial diversity and the relative abundance of dominant taxa in marine environments. However, the specific impact on freshwater microbial diversity and community structure, particularly for eukaryotic microorganisms, remains unclear. To address this gap, we collected water samples from eutrophic Lake Taihu and mesotrophic Lake Bosten. We filtered the samples through 0.2 μm filters using volumes ranging from 0.1 to 2 L for Lake Taihu and 0.1 to 3.2 L for Lake Bosten. Analysis of 18S rRNA gene amplicons revealed that variations in filtered water sample volume significantly affected the diversity, community structure, and composition of eukaryotic microorganisms. In light of these findings, we recommend using a filtered water sample volume of approximately 0.2 L for eutrophic aquatic ecosystems and 0.8 L for mesotrophic aquatic ecosystems in microbial analyses. These recommendations underscore the importance of selecting the appropriate filtered water sample volume to ensure representative and reliable results in the study of eukaryotic microorganisms in freshwater ecosystems.

Analisis Pemanfaatan Limbah Abu Kelapa Sawit Sebagai Adsorben dalam Menurunkan Logam Besi (Fe) pada Air Asam Tambang

The aim of this research is to analyze the comparative ability of boiler ash and incinerator ash in reducing Fe metal levels in Acid Mine Water, analyze the effect of mass variations and pH variations of the POFA adsorbent and analyze the adsorption ability. The flow in this research is adsorbent activation, taking Acid Mine Water samples, testing the initial conditions of Acid Mine Water samples which include pH and Fe testing and the AAT adsorption experimental stage, acid mine water sample volume 250 ml for each experiment, stirring speed 300 rpm and contact time. for 3 hours with adsorbent masses used of 2.5g, 5g and 10g, and pH variations of 5, 7 and 9, data analysis stage of adsorption capacity data. Based on research results, boiler ash is better at adsorbing Acid Mine Water, the greater the POFA adsorbent mass has the ability to reduce Fe metal because the removal percentage is greater. The best pH for adsorption treatment is pH 7, namely neutral pH, the most optimal mass of adsorbent used is 10g with a pH value of 7. The regression value on the Langmuir Isotherm is higher than the Regression value on the Freundlich Isotherm, so the Langmuir Isotherm is better for find out how much adsorbate mass can be adsorbed by the adsorbent.

Sorption of the Cu, Gd, V, Mn, and Fe elements by hydrogels with identification of their complexes in the solid phase of the polymer ligand using EPR

The search for new sorbents for the concentration of substances is among the important tasks of analytical chemistry regarding the monitoring of water bodies in modern times. It is necessary to regularly control water supply sources, and the quality of natural water is also an indicator of the health of ecosystems. The use of sorbents when collecting water for analysis simplifies the preparation of complex samples, allowing to use a solid concentrate to determine the absorbate and quickly record the results using multi-element in situ instrumental methods. We suggested using cross-linked polyacrylates (CLPs) based on polyacrylamide as a new type of sorbent for these purposes. Unlike traditional sorbents, hydrogels noticeably swell in water (рН 4-7), which allows conducting the sorption of elements not only on the surface but also inside CLP granules. Sorption is conducted in a static mode by placing a weighed portion of CLP in a certain volume of water sample and by further drying in air at 70-100°C. The purpose of this work was to obtain and study solid polymer concentrates of CLP using EPR spectroscopy in order to confirm the sorption of elements in CLP for the further development of methods for the preparation of samples of various water bodies. To do this, we obtained individual and binary polymer complexes of paramagnetic elements Cu(II), Gd(III), V(IV), Mn(II), and Fe(III) from model solutions of their salts (from 10-7 (INAA) to 10-3 (EPR) mol/dm3) and dried them To confirm the sorption and reliable binding of elements into polymer complexes, we used ESR spectroscopy at 293 K. The experimentally obtained new EPR spectra were compared with the theoretical ones. Complex EPR spectra were simulated using original software developed at the Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences. It was shown that upon drying CLPs completely disengaged from water molecules, while the sorption of metals depended on the рН and grew with an increase in the solution’s рН. In case of joint presence, metal ions formed more complex compounds as compared to individual sorption. The hyperfine structure constant (HSC) was calculated for the spectra of complexes with CLPs and g-factor was calculated for all samples. It was determined that in the course of the formation of metal complexes with CLPs, the nearest coordination sphere was greatly distorted, while the nature of the distortion of the ligand environment depended on the element. In case of the Cu(II) and V(IV) system, we observed additivity of the EPR spectra, but in case of Cu and Gd(III) it was not recorded. In any case, the formation of strong and stable polymer complexes was confirmed. Sorption concentration using CLPs was proposed as a method of sample preparation of natural and technogenic water systems by transferring the determined ions into a solid hydrogel concentrate in order to be further analysed using multi-element instrumental methods (for example, X-ray fluorescence analysis (XRF), instrumental neutron activation analysis (INAA), etc.).

An improved method for isotopic and quantitative analysis of dissolved organic carbon in natural water samples.

A wet chemical oxidation (WCO) method has been widely used to obtain the dissolved organic carbon (DOC) content and carbon isotope (δ13CDOC) ratios. However, it is sometimes difficult to get high precision results because not enough CO2 was oxidized from the natural water samples with low DOC concentrations. This improvement primarily aims to increase the water sample volume, improve the removal rate of dissolved inorganic carbon (DIC), and minimize the blank DOC from the standard solution. Following the improved procedure, the δ13C ratios of standardized DOC solutions were consistent with their actual values, and their differences were less than 0.2‰. The improved method demonstrated good accuracy and stability when applied to natural water samples with DOC concentrations ≥0.5 mg L-1, with the precisions of DOC concentrations and δ13C ratios were better than 0.07 mg L-1 and 0.1‰, respectively. More importantly, this method saved much pre-treatment time and realized batch processing of water samples to obtain their DOC contents and isotope ratios.

Unapređenje tehnološke opreme drona za uzorkovanje vode - projektovanje i modelovanje

One of the modern problems in the field of ecology is the creation of environmentally friendly equipment for monitoring the state of various reservoirs by taking water for further laboratory analysis. Water quality monitoring is needed to record changes in water quality over time, as well as to detect contamination from storm water runoff, which may contain microorganisms, minerals, debris, and fuel residues. One of the promising ways to solve this problem is using drones to collect hydro-chemical data on the spot and take water samples from freshwater environments. This approach makes it possible to perform the aspects of biological and physical-chemical water sampling that are necessary for implementing large-scale water sampling programs and makes these programs more efficient, safe, and economically profitable. However, in modern times, the use of drones for water quality monitoring is held back by a number of important limitations, namely the low level of objective sampling and the relatively small volume of water samples. The article proposes a fundamentally new design of the technological equipment of a drone for taking water samples, namely a new design of a bathometer - a device for taking water samples and installing them on the Cardan suspension. These structural differences ensure the orientation of the bathometer only under the influence of gravitational force, which in turn significantly increases the objectivity of water sampling. The article also provides kinematic and dynamic models of the bathometer's movement on the Cardan suspension rings. It presents the modeling results in the form of graphical and analytical dependencies of kinematic analysis, which constitutes the scientific aspect of the problem. The main motivation of the conducted research is the creation of environmentally friendly equipment in the form of an unmanned aerial vehicle, which is designed to increase the objectivity of water sampling.

Green and efficient preconcentration of calcium channel blocker drugs in water using effervescence powder in syringe-assisted deep eutectic solvent dispersive liquid-liquid microextraction

Efficient preconcentration techniques are crucial for the analysis of calcium channel blocker drugs such as amlodipine and nifedipine, commonly used for hypertension and heart diseases. This study optimized the preconcentration conditions using CO2 effervescence powder assisted deep eutectic solvent dispersive liquid-liquid microextraction (EP-DLLME). A central composite design with 30 experiments was employed to determine the effects of extraction solvent volume, effervescence powder mass, water sample volume, and pH water. The optimized conditions for EP-DLLME were determined as follows: 500-μL of extraction solvent, 25-mL of water sample, 5 mg of effervescence powder, and pH 8. High-performance liquid chromatography (HPLC) coupled with a diode array detector was utilized for subsequent analysis. The method exhibited good linearity (r2 = 0.996) and low limits of detection and quantification: 1.73 ng/mL and 5.76 ng/mL for amlodipine, and 0.37 ng/mL and 1.23 ng/mL for nifedipine, respectively. The extraction efficiency, evaluated at three concentration levels, resulted in recoveries ranging from 73 % to 98 %. Repeatability analysis showed satisfactory intra-day and inter-day relative standard deviation values: 3.65 % to 8.38 % for amlodipine and 1.9 % to 10.11 % for nifedipine in the intra-day analysis, and 2.46 % to 9.07 % for amlodipine and 2.92 % to 10.7 % for nifedipine in the inter-day analysis. Furthermore, the EP-DLLME method demonstrated environmental sustainability, achieving a total AGREEnness score of 0.68, emphasizing its environmentally friendly nature.

Rapid Isolation of Low-Level Carbapenem-Resistant E. coli from Water and Foods Using Glycan-Coated Magnetic Nanoparticles.

Carbapenem-resistant Enterobacterales (CRE) are one of the major global issues needing attention. Among them, carbapenemase-producing (CP) E. coli strains are commonly found in clinical and biological samples. Rapid and cost-effective detection of such strains is critical in minimizing their deleterious impact. While promising progress is being made in rapid detection platforms, separation and enrichment of bacteria are required to ensure the detection of low bacterial counts. The current separation methods, such as centrifugation, filtration, electrophoresis, and immunomagnetic separation, are often tedious, expensive, or ineffective for clinical and biological samples. Further, the extraction and concentration of antimicrobial-resistant bacteria (ARB) are not well documented. Thus, this study assessed the applicability of cost-effective glycan-coated magnetic nanoparticles (gMNPs) for simple and rapid extraction of CP E. coli. The study included two resistant (R)strains: Klebsiella pneumoniae carbapenemase (KPC)-producing E. coli (R: KPC) and New Delhi metallo-β-lactamase (NDM)-producing E. coli (R: NDM). A susceptible E. coli (S) strain was used as a control, a reference bacterium. The gMNPs successfully extracted and concentrated E. coli (R) and E. coli (S) at low concentrations from large volumes of buffer solution, water, and food samples. The gMNPs concentrated up to two and five times their initial concentration for E. coli (R) and E. coli (S) in the buffer solution, respectively. In water and food samples, the concentration of E. coli (S) and E. coli (R) were similar and ranged 1-3 times their initial inoculation. A variation in the concentration from different food samples was seen, displaying the impact of food microstructure and natural microflora. The cost-effective and rapid bacterial cell capture by gMNPs was achieved in 15 min, and its successful binding to the bacterial cells in the buffer solution and food matrices was also confirmed using Transmission Electron Microscopy (TEM). These results show promising applications of gMNPs to extract pathogens and ARB from biological samples.

Development and assessment of an onsite large volume solid phase extraction (LV-SPE) device for the determination of pharmaceuticals and personal care products (PPCPs) in water

It is essential to determine the occurrence of emerging organic contaminants (EOCs), such as pharmaceuticals and personal care products (PPCPs), in the ambient environment to address growing public concerns. However, such analysis is quite challenging due to the low trace level of such contaminants in water, which therefore requires several litres of water samples. In this study, a large volume solid phase extraction (LV-SPE) device was developed and evaluated for its performance in monitoring PPCPs as an example. Relatively good recoveries and reproducibility were obtained under specific operating conditions: a water sample volume of no more than 20 L, a flow rate not exceeding 120 mL/min, and a methanol elution volume of at least 30 mL. In addition, the results from the onsite enrichment approach using LV-SPE were compared with those from the conventional approach using a standard SPE device in the laboratory for real groundwater samples. Among the eight selected PPCPs (nalidixic acid, carbamazepine, bezafibrate, clofibric acid, sulfadiazine, sulfamethoxypyridazine, sulfamethazine and sulfamonomethoxine), LV-SPE approach detected more target compounds. While the detected concentrations were generally comparable, slightly higher concentrations were observed for carbamazepine, clofibric acid, sulfadiazine and sulfamethazine using the LV-SPE method. The developed LV-SPE device provides an alternative approach for trace analysis of PPCPs and may also be applicable for other emerging organic contaminants.

Microbial Detection and Quantification of Low-Biomass Water Samples Using an International Space Station Smart Sample Concentrator.

The pressing need to safeguard the health of astronauts aboard the International Space Station (ISS) necessitates constant and rigorous microbial monitoring. Recognizing the shortcomings of traditional culture-based methods, NASA is deliberating the incorporation of molecular-based techniques. The challenge, however, lies in developing and validating effective methods for concentrating samples to facilitate this transition. This study is dedicated to investigating the potential of an ISS Smart Sample Concentrator (iSSC) as an innovative concentration method. First, the iSSC system and its components were tested and optimized for microgravity, including various testing environments: a drop tower, parabolic flight, and the ISS itself. Upon confirming the system's compatibility with microgravity, we further evaluated its proficiency and reliability in concentrating large volumes (i.e., 1 L) of water samples inoculated with different microbes. The samples carried 102 to 105 colony-forming units (CFUs) of Sphingomonas paucimobilis, Ralstonia pickettii, or Cupriavidus basilensis per liter, aligning with NASA's acceptable limit of 5 × 104 CFU/L. The average retrieved volume post-concentration was ≈450 µL, yielding samples that were ≈2200 times more concentrated for subsequent quantitative PCR (qPCR) and CFU analysis. The average microbial percent recovery, as assessed with CFU counts, demonstrated consistency for C. basilensis and R. pickettii at around 50% and 45%, respectively. For S. paucimobilis, the efficiency oscillated between 40% and 80%. Interestingly, when we examined microbial recovery using qPCR, the results showed more variability across all tested species. The significance of these findings lies not merely in the successful validation of the iSSC but also in the system's proven consistency, as evidenced by its alignment with previous validation-phase results. In conclusion, conducted research underscored the potential of the iSSC in monitoring microbial contamination in potable water aboard the ISS, heralding a paradigm shift from culture-based to molecular-based monitoring methods.

Dead‐end hollow fiber ultrafiltration capture of environmental DNA for freshwater mussel (Unionidae) species detection with metabarcoding

AbstractInsufficient water sample volumes can be a limiting factor for detecting species with environmental DNA (eDNA) from aquatic habitats. We compared detections of freshwater mussel (Unionidae) communities using large water sample volumes and dead‐end hollow fiber ultrafiltration (D‐HFUF or DEUF) with traditional eDNA filtration methods that use relatively small water sample volumes. Unionid species were detected in approximately 50‐L D‐HFUF eDNA samples with two mitochondrial DNA metabarcoding markers (COI and ND1) and compared to species detection results from eDNA captured from commonly used 1‐L samples filtered with polyethersulfone (PES) filters at three lotic sites in Georgia and Missouri. Of the 431,560 COI and 1,035,472 ND1 reads from all environmental samples of both filter types that passed quality control, 95% (410,755 reads) of COI reads and 85% (883,472 reads) of ND1 reads were assigned to a unionid species. Nineteen different freshwater mussel species were detected across all D‐HFUF samples, and 11 species were detected across all PES samples. Reads assigned to the genus Elliptio could not be resolved beyond the genus level with either marker. From D‐HFUF samples, 15 and 16 mussel species were detected with the COI and ND1 markers, respectively. From PES samples, nine and seven species were detected with the COI and ND1 markers, respectively. More mussel species were detected at each site in D‐HFUF samples than in PES samples regardless of whether results from both markers were combined or evaluated separately. Our results demonstrate the merit of further exploration and optimization of D‐HFUF for capturing eDNA from high‐volume water samples to facilitate detection of unionids and likely other aquatic organisms.

Estimation of self-absorption correction coefficients for gross-alpha activity measurements

Optimizing the sample volume is an important consideration while preparing planchets for measuring gross-alpha activity in environmental water samples. A higher sample volume results in increased thickness, which has a significant impact on gross-alpha activity measurements due to self-absorption in the samples. Moreover, while evaporating water samples on planchets to dryness, necessary precautions must be taken to prevent the loss of sample mass due to excessive heating. The present study represents a preliminary effort to estimate self-absorption correction coefficients and the efficiency of the detector, corrected for self-absorption, for estimating gross-alpha activity. The self-absorption correction coefficient versus sample volume is determined by performing gross alpha counting of different volumes of IAEA reference water samples. This is achieved through planchet preparations using varying quantities of water samples (ranging from 1 ml to 5 ml in steps of 1 ml, and from 10 ml to 20 ml in steps of 5 ml). The study also examines the effect of sample volume on the detector's efficiency for gross-alpha activity measurements. Additionally, the study highlights the impact of different drying methods in planchet preparations on gross-alpha activity measurements. The study reveals that the self-absorption correction coefficient decreases with increasing sample volume, indicating that larger sample volumes require more corrections for efficiency. Furthermore, it is observed that the efficiency, corrected for self-absorption, decreases with an increase in sample volume, as expected.

Assessment of Biological Treatment for Ammonia Removal from Water Resources, Egypt

Egypt is depending entirely on the Nile water. The Rosetta branch of the river Nile serves as a vital freshwater source for domestic, agricultural, industrial, fisheries, and recreational purposes in several western Delta governorates of Egypt, with a daily flow averaging 21,500,000 m3/day. The branch faces significant challenges due to escalating ammonia concentrations stemming from agricultural drains along the river, industrial effluents from industrial activities, and fish farming cages. One particular issue arises during low-demand periods when the flow in the Rosetta branch diminishes. Annually, Egyptian authorities close water flows in a series of channels to facilitate maintenance, resulting in reduced water levels. This winter closure has impacted Kafr El Sheikh and El Beheira, located in northern Egypt, as the drainage of industrial wastes during this period has led to a high pollution load of ammonia and other pollutants. The elevated ammonium content has hindered coagulation, encouraged algal growth, and impeded the chlorine breakpoint during water chlorination processes. Laboratory experiments were conducted to investigate the ability of blue-green algae species (Anabaena sp., Scyndesmos sp., Chlorella sp.) and bacteria (Lactobacillus sp.) to uptake ammonia. This study revealed that single algal species achieved a maximum removal percentage of 30% for ammonia concentrations ranging from 5 to 7.5 mg/l, and mixed algal species attained removal percentages between 6% and 12% at constant retention times of 15 to 60 minutes. For single algal species, retention times exceeding 1 hour (2 and 5 hours) resulted in removal percentages ranging from 85% to 100%. For mixed algal species, removal percentages between 9% and 20% were observed for various retention times ranging from 15 minutes to 1 hour. When comparing the use of algal species mixtures, removal percentages of up to 30-50% were achieved. Additionally, the study found that the application of bacterial species (Lactobacillus sp.) to raw water samples with an average ammonia concentration of 7.8 mg/l resulted in a maximum removal percentage of 100% when using a bacterial content of 100-200 ml per 1-liter raw water sample volume, with varied retention times up to 2 hours.

Are Indicator Microorganisms Predictive of Pathogens in Water?

The microbiological quality assessment of drinking water (DW) and drinking water sources (DWSs) is based on the detection of indicator microorganisms (IMs). However, the relationship between IMs and pathogens has been questioned, as pathogens have been detected even in the absence of IMs, and vice versa. Therefore, the aim of this review was to evaluate the reliability of IMs by analysing the correlation between the presence of IMs and pathogens in water. This review focused on studies that reported statistical analyses of the relationship between traditional and alternative IMs and enteric pathogens in DWSs (groundwater, surface water, and rainwater) and in DW. Additionally, the main DW guidelines and regulations, along with a focus on the application of Quantitative Microbial Risk Assessment (QMRA), were also reported. The overall analysis of publications revealed a controversial correlation, characterised by high spatiotemporal variability, indicating the impossibility of identifying a reliable IM for any specific pathogen or water type. The association was also influenced by numerous factors, such as intrinsic characteristics of microorganisms, seasonal variations, sample number, water sample volume, and the detection method used. In conclusion, the detection of IMs should be considered complementary to, rather than a substitute for, the detection of pathogens.

Green Techniques for Detecting Microplastics in Marine with Emphasis on FTIR and NIR Spectroscopy—Short Review

The amount of microplastics (MPs) present in marine ecosystems are a growing concern, with potential impacts on human health because they are associated with an increase in the ecotoxicity of certain foods, such as fish. As a result, there has been a growing interest in developing effective methods for the analysis of MPs in marine waters. Traditional methods for MP analysis involve visual inspection and manual sorting, which can be time-consuming and subject to human error. However, novel methods have been developed that offer more efficient and accurate analyses. One such method is based on spectroscopy, such as Fourier transform infrared spectroscopy (FTIR). Another method involves the use of fluorescent dyes, which can selectively bind to microplastics and allow for their detection under UV light. Additionally, machine learning approaches have been developed to analyze large volumes of water samples for MP detection and classification. These methods involve the use of specialized algorithms that can identify and classify MPs based on their size, shape, and texture. Overall, these novel methods offer more efficient and accurate analyses of MPs in marine waters, which is essential for understanding the extent and impacts of MP pollution and for developing effective mitigation strategies. However, there is still a need for continued research and development to optimize these methods and improve their sensitivity and accuracy.

A surfactant-based quasi-hydrophobic deep eutectic solvent for dispersive liquid-liquid microextraction of gliflozins from environmental water samples using UHPLC/fluorescence detection

Despite the anticipated exceptional properties of deep eutectic solvents (DES) in microextraction techniques, their self-aggregation behaviour has only been sporadically studied in the previous literature. In the presented study, a novel surfactant-based quasi-hydrophobic deep eutectic solvent (DES) is synthesized and utilized in dispersive liquid-liquid microextraction (DLLME) of three gliflozins in environmental water samples as a proof-of-concept examples. The synthesized DES is composed of benzalkonium chloride (BZKCl) as a hydrogen bond acceptor and octanol (Oct) as a hydrogen bond donor. A full optimization of the extraction conditions was carried out including molar ratio and composition of DES, volume of DES, volume of water samples, extraction time and type of diluting solvent. Moreover, the extraction mechanism was thoroughly investigated, and it was established that the extraction of the target analytes is attributed to the analytes' incorporation into the micelles’ cores that facilitates mass transfer from the aqueous layer into DES layer. Furthermore, micelles formed by surfactant-based DES will provide adequate dispersion of extractant phase within water samples, which consequently improves the extraction efficiency. Micelles formation was confirmed by transmission electron microscopy (TEM). Furthermore, 1H NMR spectra verifies that the synthesized DES keeps its integrity even after extraction, which excludes any decomposition of DES after DLLME procedure. The extraction recovery is in an excellent agreement with the hydrophobicity of the investigated drugs, being the highest for the most hydrophobic one. The extracted analytes were separated by UHPLC coupled with fluorescence detection. Under the optimized experimental conditions, the method exhibits excellent linearity and a high detection sensitivity with a limit of detection of 0.5, 2.0 and 0.1 ng mL−1 for EMP (empagliflozin), DAP (dapagliflozin) and CAN (canagliflozin), respectively. The greenness of the developed microextraction approach was assessed by different greenness metrics such as Complex GAPI and AGREE tools. The developed method shows excellent greenness of synthetic procedure for preparation of DES, the environmentally benign nature of DLLME procedure as well as the greenness of the developed UHPLC approach.

Methodological considerations for aqueous environmental RNA collection, preservation, and extraction.

Environmental RNA (eRNA) analysis is expected to infer species' physiological information (health status, developmental stage, and environmental stress response) and their distribution and composition more correctly than environmental DNA (eDNA) analysis. With the prospect of such eRNA applications, there is an increasing need for technological development for efficient eRNA detection because of its physicochemical instability. The present study conducted a series of aquarium experiments using zebrafish (Danio rerio) and validated the methodologies for capture, preservation, and extraction of eRNA in a water sample. In the eRNA extraction experiment, an approximately 1.5-fold increase in lysis buffer volume resulted in a more than sixfold increase in target eRNA concentration. In the eRNA capture experiment, although GF/F and GF/A filters yielded similar eRNA concentrations, a GF/A filter may be capable of passing through more volume of water samples and consequently collecting more eRNA particles, given the time required for water filtration. In the eRNA preservation experiment, the use of RNA stabilization reagent (RNAlater) allowed for stably preserving target eRNA on a filter sample at -20 and even 4°C for 6days at least. Altogether, the findings enable the improvement of eRNA availability from the field and easily preserve eRNA samples without deep-freezing, which will contribute to the refinement of eRNA analysis for biological and physiological monitoring in aquatic ecosystems.

Microplastics pollution in the rivers of a metropolitan city and its estimated dependency on surrounding developed land

The spatial distribution and abundance of suspected microplastics (SMPs) in the surface water of a metropolitan city, as represented by four Hong Kong rivers, was studied during the dry season. Shing Mun River (SM), Lam Tsuen River (LT), and Tuen Mun River (TM) are located in urbanized areas, and SM and TM are tidal rivers. The fourth river, Silver River (SR) is situated in a rural area. TM had a significantly higher SMP abundance (53.80 ± 20.67 n/L) than the other rivers. The SMP abundance increased from upstream to downstream in non-tidal rivers (LT and SR), but not in tidal rivers (TM and SM), probably due to the tidal influence and a more homogeneous urban development along the tidal rivers. Inter-site differences in the SMP abundance were strongly correlated with the built area ratio (defined as the percentage of surrounding developed land area), human activities, and the nature of the river. About half (48.72 %) of the SMPs were <250 μm. Fibers and fragments were most abundant (>98 %), with most of them being transparent (58.54 %), black (14.68 %), or blue (12.12 %). Polyethylene terephthalate (26.96 %) and polyethylene (20.70 %) were the most common polymers. However, the MP abundance could be overestimated due to the presence of natural fibers. By contrast, an underestimation of the MP abundance could result from a smaller volume of water samples collected, due to a low filtration efficiency caused by high organic content and particle concentrations in the water. A more effective solid waste management strategy and upgrading of the sewage treatment facilities for removing microplastics are recommended to ameliorate the microplastic pollution in local rivers.

Reservoir characterization by push-pull tests employing kinetic interface sensitive tracers - a pore-scale study for understanding large-scale processes

The kinetic interface-sensitive (KIS) tracer experiment is a newly developed method to quantify the fluid-fluid interfacial area (FIFA) during drainage processes. The concentration breakthrough curves, obtained by measuring reaction product concentration in brine/water samples after breakthrough, are interpreted with a specialized numerical model to determine the FIFA. However, this method has its own limitations since the volume of the usable water sample (after breakthrough), based on which the analysis takes place, is often insufficient. This happens because this volume strongly depends on the aquifer material, i.e. sand type and system parameters. An alternative is to employ KIS tracers in a “push-pull” experimental set-up, i.e. primary drainage is followed by a consequent main imbibition process, with the flow direction being reversed. This study applies a pore-scale numerical model to study the KIS tracer reactive transport during a push-pull experiment in a 2D porous medium. The advective-dispersive-reactive transport during both primary drainage and main imbibition processes is discussed. The concentration breakthrough curves show a non-linear descending trend with time, until reaching a constant concentration at the steady state. By analyzing the spatial concentration distribution and the concentration breakthrough curve, the macro-scale KIS tracer reactive transport model can be interpreted for the push-pull process. Finally, the new method is applied in a column experiment, where the determined specific interfacial area is found to be close to literature data.

MICROPLASTICS IN NATURAL WATER: SOURCES AND DETERMINATION

The paper is devoted for origin of microplastics in aquatic environment and possible methods of characterization and analysis. According to US National Oceanic and Atmospheric Administration, microplastics are synthetic organic polymer particles with a size less than 5 mm. Microplastics pollution is a significant ecological problem in the world. A lot of surface waters are significantly polluted by various types of microplastics. These pollutants were found in rivers, lakes, oceans, sediments, wastewater, drinking water and bottled water. But in Ukraine microplastic problem of surface water do not meet the interest of scientists and ecological organizations. Disintegration of plastic waste is one of the main sources of microplastics in water. But there are a lot of other sources of primary and secondary microplastics, including components personal care products, industrial abrasives, abrasion from car tires, paint failure, industrial processes, textile washing, at-sea losses, etc. Microplastics can harm ecosystems and cause many health problems for different organisms, including problems with feeding and digestion, endocrine disruptions and changes in cellular functions. In general, health effects and environmental impacts are dependent on the size of the microplastic particles and chemical structure of these polymers. Thus, it is very important to understand chemical composition, physical forms, transport in environment and fragmentation of microplastics due to the need to predict possible exposure effects. There are a lot of methods for characterization and analysis of microplastics, but all of them have some disadvantages. Microplastics determination is often especially difficult for water with low microplastics content due to very large volumes of water samples and very small mass of separated plastics.