River Samples Research Articles

Assessment of bioactive chemicals in wastewater effluents and surface waters using in vitro bioassays in the Nakdong River basin, Korea

Organic micropollutants present in effluents of wastewater treatment plants (WWTPs) can negatively affect the quality of receiving waters or drinking water sources. The present work monitored the concentration of bioactive chemicals using a battery of in vitro bioassays in 14 WWTP effluents, 2 effluent-dominant streams, and 5 river waters in the Nakdong River basin, Korea, for a two-year period. The WWTP effluents showed AR/ERα/TRβ (androgen/estrogen/thyroid hormone) activities at a few to tens ng/L, PAH/PPARγ/p53 (polycyclic-aromatic-hydrocarbon/lipid metabolism/genotoxicity) activities at hundreds ng/L, and PXR/Nrf2 (xenobiotic metabolism/oxidative stress) activities at tens to hundreds μg/L as bioanalytical equivalent concentrations. The concentration level and type of bioactivities were statistically not affected by the source, season, or treatment processes of WWTPs for most endpoints. The effluent-dominant streams showed similar levels of AR/ERα/PAH/PXR/Nrf2 activities compared to the upstream WWTP effluents. The river waters showed lower levels of AR/ERα activities (by factors of 6 or 7) but had only slightly lower PAH/PXR/Nrf2 activities (within factors of 2) than the WWTP effluents when compared based on median concentration. Cytotoxicity was below the quantification limit (0.3 μg/L) in most effluent and river samples. For ERα/PAH/PXR/Nrf2, the median bioactivity levels of the river waters were higher than at least one of the effect-based trigger (EBT) values proposed in the literature. Further monitoring work and reliable/realistic EBT derivation are needed to determine possible ecological risks posed by the observed bioactivities.

Selective determination of 2-aminobenzothiazole in environmental water and organic extracts from fish and dust samples

In the present study, a homemade mixed-mode ion-exchange sorbent based on silica with embedded graphene microparticles is applied for the selective extraction of 2-aminobenzothiazole (NH2BT) followed by determination through liquid chromatography coupled to high-resolution mass spectrometry. The sorbent was evaluated for the solid-phase extraction of NH2BT from environmental water samples (river, effluent wastewater, and influent wastewater), and NH2BT was strongly retained through the selective cation-exchange interactions. Therefore, the inclusion of a clean-up step of 7 mL of methanol provided good selectivity for the extraction of NH2BT. The apparent recoveries obtained for environmental water samples ranged from 62 to 69% and the matrix effect from −1 to −14%. The sorbent was also evaluated in the clean-up step of the organic extract for the extraction of NH2BT from organic extracts of indoor dust samples (10 mL of ethyl acetate from pressurized liquid extraction) and fish (10 mL of acetonitrile from QuEChERS extraction). The organic extracts were acidified (adding a 0.1% of formic acid) to promote the cation-exchange interactions between the sorbent and the analyte. The apparent recoveries for fish samples ranged from 22 to 36% depending on the species. In the case of indoor dust samples, the recovery was 41%. It should be highlighted the low matrix effect encountered in such complex samples, with values ranging from −7 to 5% for fish and dust samples. Finally, various samples were analyzed. The concentration in river samples ranged from 31 to 136 ng/L; in effluent wastewater samples, from 55 to 191 ng/L; in influent wastewater samples, from 131 to 549 ng/L; in fish samples, from 14 to 57 ng/g dried weight; and in indoor dust samples, from <MQL to 114 ng/g.

Contributions of 238U, 232Th, and 40K to the radiogenic heat production in selected river sediment samples of South Africa

In this study, 16 sediment samples were collected from Bree, Klein-Brak, Bakens and uMngeni rivers of South Africa and were prepared, analysed and evaluated for the activity concentration of 238U, 232Th and 40K concerning its radiogenic heat production using a high-purity germanium detector. The results show that 238U is the prevalent radionuclide in radiogenic heat production, with 232Th and 40K emerging as trace elements. The mean activity concentrations are 28.97%, 63.69% and 7.34% for uranium, thorium and potassium, respectively, from all sampling locations. This shows that a high radioactive concentration of a specific radionuclide does not necessarily imply its increased contribution to radiogenic heat production. The radionuclide contributions to radiogenic heat production at all sampled locations are 59.39%, 35.11% and 5.50% for uranium, thorium and potassium, respectively. The mean radiogenic heat production rate in the study area ranged from 0.0180 μW m − 3 in sediment samples from the Bree River in Western Cape to 0.0072 μW m − 3 in sediment samples of uMgeni River in KwaZulu-Natal. All values obtained for this study are five times lower than the average continental radiogenic heat production of 1 μW m − 3 . This study provides insight into the radiogenic heat production rate due to the presence of radionuclides in all river samples.

A novel reaction-based ratiometric fluorescent probe with large Stokes shift for the detection of Hg2+ in river sample

Based on Hg2+-promoted desulfurization-hydrolysis of the diphenylphosphinothioate moiety, a novel ratiometric fluorescent probe 1 for Hg2+ using hemicyanine as the fluorophore was designed and synthesized. In sensing of Hg2+, the maximum fluorescence emission and absorption peaks of 1 shifted from 450 nm to 504 nm and from 351 nm to 376 nm, respectively, accompanied by color change from colorless to green under illumination with a 365 nm UV lamp. 1 not only exhibited remarkable change in the ratios of both absorbance (A376 nm/A351 nm) and fluorescence intensity (F504 nm/F450 nm), but also had large Stokes shift, fast response, excellent sensitivity, and high selectivity for Hg2+. Furthermore, 1 was successfully applied for Hg2+ detection in river water sample.

Cold atmospheric plasma: a sustainable approach to inactivating viruses, bacteria, and protozoa with remediation of organic pollutants in river water and wastewater

Innovative technologies are needed to enhance access to clean water and avoid waterborne diseases. We investigated the performance of cold atmospheric plasma (CAP), a clean and sustainable approach for microbial inactivation and total organic carbon (TOC) degradation in environmental water. Water matrices played a crucial role in the performance of CAP efficacy; for example, complete removal of ɸX174 from dH2O required 1 min of treatment, while ɸX174 reductions of ~ 2log10 and 4log10 were obtained after 10 min of CAP exposure in river water and wastewater samples, respectively. Similarly, after 10 min of CAP treatment, bacterial concentrations decreased by 3 log10 and 4 log10, in river and wastewater samples, respectively. In contrast, after 30 s of contact time, a 4 log10 reduction of bacteria was accomplished in dH2O. Complete removal of Acanthamoeba from dH2O was found after 30 min of CAP treatment, whereas it was not removed from surface water or wastewater at the same exposure time. Additionally, the approach successfully reduced TOC, and the degradation kinetics of TOC were represented by pseudo-first-order. CAP showed higher rates of TOC degradation in the final effluent of the wastewater treatment plant compared to surface water. The difference in CAP performance between river water and wastewater could be attributed to the bulk structure of humic acids in river water compared to small organic byproducts in the final effluent of WWTP. Overall, the findings reported here support the idea that CAP holds promise as a sustainable solution for controlling pathogens, removing organic water pollution, and integrating with traditional purification processes. Low-cost systems may advance CAP technology and increase its widespread use.

Intelligent laser-induced graphene sensor for multiplex probing catechol isomers

Herein, we unveil the intelligent detection of multiple catechol isomers in complex environments utilizing both laser-induced graphene (LIG) and artificial neural network (ANN). The large scale-up manufacturing of LIG-based sensors (LIGS) with three-electrode configuration on polyimide (PI) is achieved by direct laser-writing and screen-printing technologies. Our LIGS shows excellent electrochemical performance toward catechol isomers, i.e., hydroquinone (1,4-dihydroxybenzene, HQ), catechol (1,2-dihydroxybenzene, CT), and resorcinol (1,3-dihydroxybenzene, RC), with a low limit of detection (LOD) (CC, 0.079 µmol/L; HQ, 0.093 µmol/L; RC, 1.18 µmol/L). Moreover, the ANN model is developed for machine-intelligent to predict concentrations of catechol isomers under an interfering environment via a single LIGS. Using six unique parameters extracted from the differential pulse voltammetry (DPV) response, the machine learning-based regression provides a coefficient of correlation with 0.998 and is able to correctly predict the total and individual concentrations in complex river samples. Hence, this work provides a guide for the preparation and application of LIGS via facile and cost-efficient mass production and the development of an intelligent sensing platform based on the ANN model.

Assessment for the data processing performance of non-target screening analysis based on high-resolution mass spectrometry

Non-target screening (NTS) based on high-resolution mass spectrometry (HRMS) is considered one of the most comprehensive approaches for the characterization of contaminants of emerging concern (CECs) in a complex sample. This study evaluated the performance of NTS in aquatic environments (including peak picking, database matching, product identification, semi-quantification, etc.) based on a self-developed data processing method using 38 glucocorticoids as testing compounds. Data-dependent acquisition (DDA) and data-independent acquisition (DIA) modes were used for obtaining the MS2 information for in-house or online database matching. Results indicate that DDA and DIA mode have their own advantages and can complement each other. The quantification method based on LC-HRMS has shown the potential to provide a fast and acceptable result for testing compounds. Finally, a matrix spike analysis was carried out on 66 CECs across different usage categories in wastewater, surface water, and seawater matrix samples, together with a case study performed for characterizing the whole contaminants in a Pearl River sample, to better illustrate the application potential of NTS workflow and the credibility of NTS outcomes. This study provides a foundation for novel applications of HRMS data by NTS workflow to identify and quantify CECs in complex systems.

Bacterial Population Changes during the Degradation Process of a Lactate (LA)-Enriched Biodegradable Polymer in River Water: LA-Cluster Preferable Bacterial Consortium.

The lactate-based polyester poly[lactate (LA)-co-3-hydroxybutyrate (3HB)], termed LAHB, is a highly transparent and flexible bio-based polymeric material. There are many unknowns regarding its degradation process in riverine environments, especially the changes in bacterial flora that might result from its degradation and the identities of any LAHB-degrading bacteria. LAHB were immersed in the river water samples (A and B), and LAHB degradation was observed in terms of the weight change of the polymer and the microscopic changes on the polymer surfaces. A metagenomic analysis of microorganisms was conducted to determine the effect of LAHB degradation on the aquatic environment. The bacterial flora obtained from beta diversity analysis differed between the two river samples. The river A water sample showed the simultaneous degradation of LA and 3HB even though the copolymer was LA-enriched, suggesting preferable hydrolysis of the LA-enriched segments. In contrast, only 3HB degraded for the LAHB in the river B water sample. The linear discriminant analysis effect size (LEfSe) analysis revealed 14 bacteria that were significantly increased in the river A water sample during LAHB degradation, suggesting that these bacteria preferentially degraded and assimilated LA-clustering polymers. Our metagenomic analysis provides useful insights into the dynamic changes in microbial communities and LA-clustering polymer-degrading bacteria.

Molecularly imprinted polymer based on magnetic porous cellulose for specific adsorption of tetracyclines: Preparation, characterization, property evaluation, and application

A magnetic porous cellulose molecularly imprinted polymer (MPCMIP) based on tetracyclines was prepared with Fe3O4 as the magnetic core and porous cellulose as the carrier. The appearance, characteristic chemical bonds, crystal structure, thermal stability, and magnetism of MPCMIP were systematically characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometry. The adsorption performance of MPCMIP to tetracycline, demeclocycline, and minocycline were comprehensively investigated by static adsorption, dynamic adsorption, and adsorption experiments under different temperature and pH conditions. MPCMIP performed good adsorption performance and fast adsorption rate for tetracyclines, and adsorption quantity and efficiency of MPCMIP were four times and twice that of traditional molecularly imprinted polymer (MIP), respectively. It can be seen that the introduction of magnetic porous cellulose effectively improved the adsorption performance of the MIP. Moreover, MPCMIP showed good adsorption stability under different temperature. The adsorption properties of MPCMIP under neutral and alkaline conditions were better than those under acidic conditions. Selective experiment was conducted with the amoxicillin and levofloxacin as the coexisting interfering compounds for the three tetracyclines. The results showed that MPCMIP possessed good imprinting effect with the impact factor values for tetracycline, demeclocycline, and minocycline of 1.49, 1.66, and 3.14, respectively. Compared with interfering compounds, MPCMIP showed excellent selectivity to tetracyclines with the selectivity factor up to 36.9. Moreover, MPCMIP exhibited better selectivity towards tetracyclines than traditional MIP according to the higher imprinting and selectivity factors of MPCMIP. The simulation of hydrogen bonding interaction and electrostatic potential analysis determined that MPCMIP mainly adsorbed TCs through the hydrogen bonding and electrostatic interactions. The results of adsorption/desorption cycling experiments indicated that MPCMIP had good reusability with 95.5% of adsorption performance after four cycles. Finally, MPCMIP combined with high-performance liquid chromatography were triumphantly used to adsorb and detect the tetracycline, demeclocycline, and minocycline in river, beef, and milk samples. Furthermore, the MPCMIP method exhibited higher sensitivity, accuracy, and selectivity than the traditional method.

Kajian Status Mutu Air Sungai Akibat Buangan Air Lindi TPA Piyungan di Kabupaten Bantul

This research was conducted along a tributary that empties into the Opak River in Piyungan District. This study aimed to examine the characteristics of leachate from the Piyungan landfill, river water quality, and the status of river water quality due to the discharge of leachate from the Piyungan landfill. The research method used is a survey method with sampling and field observations. Purposive sampling is used to take river sample points. There are five sample points taken with 15 test parameters used to analyze river water quality, including COD, BOD, TSS, TDS, Zinc (Zn), Iron (Fe), Chromium, Copper (Cu), Lead (Pb), Mercury (Hg), pH, temperature, turbidity, color, and total coliform. River water quality status is obtained by calculating the Pollution Index (IP) of class II quality standard, Governor of DIY Regulation Number 20 of 2008, without the total coliform parameter. Based on the analysis results, the characteristics of the leachate water of the Piyungan TPA have concentrations of BOD, COD, TSS, TDS, and Iron (Fe), which exceed the quality standards of Yogyakarta Special Region Regulation Number 7 of 2016. River water quality shows that parameters BOD, COD, TSS, TDS, Zinc (Zn), Iron (Fe), turbidity, color, and total coliform exceed class II water quality standards regulation of the Governor of the Special Region of Yogyakarta Number 20 of 2008. The highest pollution load in rivers is Total Coliform, BOD, and COD. The status of river water quality from all sample point locations has the status of heavily polluted water (Point S1), moderately polluted (Point S2, S3, S4), and lightly polluted (Point S5). Thus, river water quality around the Piyungan landfill has decreased due to the discharge of leachate from the Piyungan landfill and community activities around the river.

Triplex DNA Helix Sensor Based on Reduced Graphene Oxide and Electrodeposited Gold Nanoparticles for Sensitive Lead(II) Detection.

A triplex DNA electrochemical sensor based on reduced graphene oxide (rGO) and electrodeposited gold nanoparticles (EAu) was simply fabricated for Pb2+ detection. The glass carbon electrode (GCE) sequentially electrodeposited with rGO and EAu was further modified with a triplex DNA helix that consisted of a guanine (G)-rich circle and a stem of triplex helix based on T-A•T base triplets. With the existence of Pb2+, the DNA configuration which was formed via the Watson-Crick and Hoogsteen base pairings was split and transformed into a G-quadruplex. An adequate electrochemical response signal was provided by the signal indicator methylene blue (MB). The proposed sensor demonstrated a linear relationship between the differential pulse voltammetry (DPV) peak currents and the logarithm of Pb2+ concentrations from 0.01 to 100.00 μM with a detection limit of 0.36 nM. The proposed sensor was also tested with tap water, river and medical wastewater samples with qualified recovery and accuracy and represented a promising method for Pb2+ detection.

Salting-out assisted liquid–liquid extraction combined with LC–MS/MS for the simultaneous determination of seven organic UV filters in environmental water samples: method development and application

Organic UV filters (OUVFs), the active ingredient in sunscreens, are of environmental concern due to reported ecotoxicological effects in aquatic biota. Determining the environmental concentrations of these chemicals is essential for understanding their fate and potential environmental risk. Salting‐out assisted liquid–liquid extraction (SALLE) coupled with liquid-chromatography tandem mass spectrometry (LC–MS/MS) was developed for simultaneous extraction, separation, and quantification of seven OUVFs (2,4-dihydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 4-methylbenzylidene camphor, butyl-methoxy-dibenzoyl methane, octocrylene, octyl methoxycinnamate, and oxybenzone). Method detection limits (MDLs) ranged from 11 to 45 ng/L and practical quantification limits (PQLs) from 33 to 135 ng/L. Method trueness, evaluated in terms of recovery, was 69–127%. Inter-day and intra-day variability was < 6% RSD. The coefficients of determination were > 0.97. The method was applied to river and seawater samples collected at 19 sites in and near Port Phillip Bay, Australia, and temporal variation in OUVF concentrations was studied at two sites. Concentrations of OUVF were detected at 10 sites; concentrations of individual OUVFs were 51–7968 ng/L, and the maximum total OUVF concentration detected at a site was 8431 ng/L. Recreational activity and water residence time at the site contributed to OUVF’s environmental presence and persistence. The benefits of the SALLE-LC–MS/MS method include its simple operation, good selectivity, precision over a wide linear range, and that obtained extracts can be directly injected into the LC–MS/MS, overall making it an attractive method for the determination of these OUVFs in environmental water matrices. To our knowledge, this is the first report of the occurrence of OUVFs in Port Phillip Bay, Australia.

Microalgal diversity assessment of Laguna Lake (Philippines) tributaries using Next-Generation Sequencing for water quality

Abstract. Santos JA, Mejia JA, Galarion MAJ, Vital P. 2023. Microalgal diversity assessment of Laguna Lake (Philippines) tributaries using Next-Generation Sequencing for water quality. Biodiversitas 24: 4636-4644. The species composition and density of microalgae have been successfully used as bioindicators of water quality as they respond quickly to any change in the water chemistry brought about by pollution. Laguna Lake in the Philippines, one of the country's most important hotspots for aquaculture, continues to be threatened by eutrophication, yet its microalgal profile has been understudied. The presence of microalgae, especially those identified to become causative agents of harmful algal blooms in lakes, can cause corresponding health effects in humans and the environment. This study determined microalgal diversity in samples from tributaries of Laguna Lake, Philippines, through 18S rRNA metagenomic sequencing or Next-Generation Sequencing (NGS). Out of the five sampling sites, only two sites passed the NGS quality control pipeline. Chlorella M.Beijerinck, dominated the eukaryotic microbial population in the Alabang-Cupang River sample, which is 95% of the total population. While in the Biñan River sample, relevant species found were Cyclotella scaldensis Muylaert &amp; Sabbe, Teleaulax acuta (Butcher) Hill, Cryptomonas curvata Ehrenb., and Peridiniopsis penardii (Lemmerm.) Bourr. This is the first study to use NGS to detect microalgae in Laguna Lake and warrants further elucidation of the microalgal population through increased sampling efforts in other recreational and livelihood hotspots. Furthermore, the study results open the importance of implementing new schemes for water quality assessments focused on molecular-based approaches.

Isolation and Growth Optimization of Mercury-Resistant Bacteria Isolated from River Ravi

Mercury (Hg) is one of the most toxic heavy metals found on earth and has been reported as a contaminant from industrial and agricultural activities. Its release in the environment has led to extreme toxicity to all life forms. Various strategies like physico-chemical techniques have been proposed for Hg removal; bioremediation has proved to be most promising among all. This study focuses on the isolation of Hg resistant bacteria from Ravi River samples. Several biochemical tests were performed like gram staining, catalase, oxidase, sugar fermentation, antibiotic resistance, and motility test. Minimum inhibitory concentration (MIC) displayed that among all the isolates, Hg4 was able to resist up to 2500 ppm Hg followed by Hg6 and Hg7 which showed resistance till 2000 ppm Hg. These isolates were subjected to mercury reduction assay. Results revealed that Hg4, Hg6, and Hg7 bioremediated 59.82%, 40.82%, and 65.00% of mercury (Hg) respectively after 24 hours. In future, these isolates can be used for the bioremediation of Hg from contaminated sites which will help in creating a healthy environment.

Synthesis of magnetic chitosan beads and its cross-linked derivatives for sorption of zinc ions from water samples of Yamuna and Hindon rivers in North India

Synthesis of magnetic chitosan beads and its cross-linked derivatives for sorption of zinc ions from water samples of Yamuna and Hindon rivers in North India

Gauging the learning environment at Damascus University Pharmacy School in Syria using the DREEM questionnaire: A cross-sectional study.

Introduction: This study was undertaken to provide the first record of evaluation of the educational environment of the Bachelor of Pharmacy program at Damascus University (DU), Syria using the internationally adopted Dundee Ready Education Environment Measure (DREEM) tool and compare it with other pharmacy schools around the world. Methods: A cross-sectional study was conducted at DU Pharmacy School in 2022. The validated DREEM 50-item inventory was added to Google Forms and used to collect data electronically. River sampling and snowball sampling methods were used. Data was collected during the second term between April 2022 and June 2022. Students from all years were included. Results: A total of 269 students completed the questionnaire; that is about 6.7% of the total population. The Cronbach's alpha of the DREEM questionnaire was 0.94. The total DREEM score was 89.8±32.1/200. Senior students scored significantly less on the DREEM scale than their younger counterparts. DU Pharmacy School scored significantly less on the total DREEM score than its other counterparts around the world with a large effect size (d>0.80). All subscales scored below 50% and the lowest scoring subscales were students' perception of learning (SPL=41.8%) and students' perception of the social environment (SSP=42.5%). Conclusions: The findings implied that the educational environment is in need of major improvement, especially in areas related to teaching and learning practices and the general social environment; failure to address the current issues in the learning environment might hinder learning and clinical practice of the future generation of pharmacists. This study provides a quality improvement map which could be used preciously address the areas that need most attention at DU Pharmacy School.

Spatial and seasonal controls on dissolved organic matter composition in shallow aquifers under the rapidly developing city of Patna, India

The distribution and composition of dissolved organic matter (DOM) affects numerous (bio)geochemical processes in environmental matrices including groundwater. This study reports the spatial and seasonal controls on the distribution of groundwater DOM under the rapidly developing city of Patna, Bihar (India). Major DOM constituents were determined from river and groundwater samples taken in both pre- and post-monsoon seasons in 2019, using excitation-emission matrix (EEM) fluorescence spectroscopy. We compared aqueous fluorescent DOM (fDOM) composition to satellite-derived land use data across the field area, testing the hypothesis that the composition of groundwater DOM, and particularly the components associated with surface-derived ingress, may be controlled, in part, by land use. In the pre-monsoon season, the prominence of tryptophan-like components likely generated from recent biological activity overwhelmed the humic-like and tyrosine-like fluorescence signals. Evidence from fluorescence data suggest groundwater in the post-monsoon season is composed of predominantly i) plant-derived matter and ii) anthropogenically influenced DOM (e.g. tryptophan-like components). Organic tracers, as well as Eh and Cl−, suggest monsoonal events mobilise surface-derived material from the unsaturated zone, causing dissolved organic carbon (DOC) of more microbial nature to infiltrate to >100 m depth. A correlation between higher protein:humic-like fluorescence and lower vegetation index (NDVI), determined from satellite-based land use data, in the post-monsoon season, indicates the ingression of wastewater-derived OM in groundwater under the urban area. Attenuated protein:humic-like fluorescence in groundwater close to the river points towards the mixing of groundwater and river water. This ingress of surface-derived OM is plausibly exacerbated by intensive groundwater pumping under these areas. Our approach to link the composition of aqueous organics with land use could easily be adapted for similar hydrogeochemical settings to determine the factors controlling groundwater DOM composition in various contexts.

Groundwater sulfate in the Pearl River Delta driven by urbanization: Spatial distribution, sources and factors

Groundwater sulfate contamination becomes a big concern in urbanized areas where urbanization expansion continues. This study investigates the spatial distribution of sulfate in shallow groundwater of the Pearl River Delta (PRD) where urbanization has lasted for more than 40 years, and discusses sources and factors for groundwater sulfate contamination in various aquifers and areas with different land-use types by using hydrochemistry and principal component analysis. A total of 330 groundwater samples, 19 river samples, and 9 landfill leachate samples were collected from the PRD. The results show that groundwater SO42− concentration in the PRD is up to 857.57 mg/L, and the SO42−-rich (>150 mg/L) groundwater accounts for 7.27%. SO42−-rich groundwater in the coastal alluvial aquifers is 3.8 times that in the alluvial-proluvial aquifers, while fissured and karst aquifers are absence of SO42−-rich groundwater. In coastal alluvial aquifers, SO42−-rich groundwater in urbanized areas is 8.5 times that in peri-urban areas. By contrast, in alluvial-proluvial aquifers, SO42-rich groundwater just occurs in urbanized areas rather than other areas. Exogenous input driven by urbanization is the primary factor for SO42−-rich groundwater in the PRD. The occurrence of SO42−-rich groundwater in urbanized and peri-urban areas of the PRD is mainly attributed to the industrial wastewater infiltration and acid precipitation. Lateral flow from rivers is another prominent source for SO42-rich groundwater in the PRD. As a consequence, in order to reduce the emergence of SO42−-rich groundwater in areas of accelerated urban expansion such as the PRD, strengthening the treatment and supervision of wastewater from township enterprises and waste gas from industrial enterprises is recommended.

Geochemical and H–O–Sr–B isotope signatures of Yangyi geothermal fields: implications for the evolution of thermal fluids in fracture-controlled type geothermal system, Tibet, China

High-temperature hydrothermal systems are mainly distributed in the north–south graben systems of southern Tibet as an important part of the Mediterranean–Tethys Himalayan geothermal belt in mainland China. As the largest unit capacity and second stable operating geothermal power station in China, Yangyi is the fracture-controlled type geothermal field in the center of Yadong–Gulu Graben. In this paper, hydrogeological and hydrochemical characteristics, isotope composition (δD and δ18O, 87Sr/86Sr and δ11B) of borehole water, hot springs, and surface river samples were analyzed. From the conservative elements (such as Cl− and Li+) and δD and δ18O values, the geothermal water of the Yangyi high-temperature geothermal field is estimated to be of meteoric origin with the contributions of chemical components of the magmatic fluid, which is provided by partially molten granite as a shallow magmatic heat source. According to logging data, the geothermal gradient and terrestrial heat flow value of the Yangyi high-temperature geothermal field are 6.48 ℃/100 m and 158.37 mW m−2, respectively. Combining the hydrothermal tracer experiment, 87Sr/86Sr and δ11B ratios obtained with gradually decreasing reservoir temperatures from the Bujiemu stream geothermal zone to Qialagai stream geothermal zone, we suggested the deep geothermal waters were mixed with local cold groundwater and then flow northeastward, forming the shallow reservoir within the crushed zone and intersect spot of faults in the Himalayan granitoid. Furthermore, in the process of ascent, the geothermal water is enriched in K+, Na+, and HCO3− during the interaction with underlying Himalayan granitoid and pyroclastic rocks that occur as wall rocks. The detailed description and extensive discussion are of great significance for the further exploitation and utilization of north–south trending geothermal belts in Tibet.

Application of a homemade silica-based mixed-mode ion-exchange sorbent for the determination of drugs in environmental water samples

Two homemade silica-based mixed-mode ion-exchange sorbents with strong moieties were compared for the solid-phase extraction (SPE) of a group of pharmaceuticals, drugs of abuse and metabolites. The difference between sorbents was the presence of graphene microparticles embedded in the network and the best results were obtained with the sorbent that did not contain graphene. The optimum SPE protocol of the non-graphene sorbent was: loading pH at 3, different loading volumes depending on the type of sample, 2 mL of MeOH as washing solvent. The optimized method was validated for the analysis of water samples of environmental interest (river water, effluent wastewater and influent wastewater). Apparent recoveries ranged from 22 to 68%, matrix effect values were lower than ±20 for most compounds, and method detection limits ranged from 1 to 28 ng/L and method quantification limits from 2 to 56 ng/L. Precision was obtained as percentual relative standard deviation (RSD%, n=4) and the repeatability and reproducibility between days were always lower than 18%. The sorbent was used to determine the analytes in environmental water samples, where most compounds were found in the range from 2 to 180 ng/L in river samples, from 3 to 2547 ng/L in effluent wastewater samples and from 24 to 8086 ng/L in influent wastewater samples.