River Water Research Articles

Plastic Debris in the Aquatic Environment: An Emerging Substratum for Antimicrobial Resistant (AMR) Biofilms.

Plastic pollution has quadrupled over the past years and has become a global concern due to its direct impact on life forms. The present study analysed whether the plastic debris in aquatic environments could act as the substratum for the antimicrobial-resistant (AMR) bacteria to form biofilm for survival. We have collected various plastic debris (n = 32) from six sites of the Periyar River, the drinking water source for the entire city and one of the most polluted rivers in Kerala (India). The chemical composition of plastics was screened via FTIR analysis and found that they comprised two types, viz., polyethylene and polypropylene. Bacteria isolated from the samples were screened for the AMR characteristics towards eight different classes of antibiotics. All isolates showed 100% resistance towards colistin and obtained the MAR index value of 0.1-0.4 range. Six representative bacterial isolates with high multiple antibiotic resistance (MAR) index were selected and identified by 16sRNA sequencing as Lysinibacillus mangiferihumi, Bacillus pumilus, Bacillus safensis, Bacillus cereus, Bacillus altitudins and Bacillus pumilus. In vitro biofilm formation was experimented on the purchased plastic samples in artificial media and river water using two selected strains, Bacillus pumilus and Bacillus cereus. Significant variations were observed in biofilm growth in different media (P < 0.05) regardless of plastic types (P > 0.05). The extracellular polymeric substances (EPS) and the characteristic holes on the surface morphology were visualized in SEM analysis, thus indicating the conditioning of the plastics by the isolates for biofilm formation.

Water Quality Assessment and its Impact on Shrimp in the Rupnarayan River: A Comparative Study from February to May of 2022-2024

The Rupnarayan River is the heart of the Purba Medinipur district of West Bengal, as it is the habitat of a large number of aquatic species and the main drinking, agricultural, irrigation, and cultivation resource. We collected river water samples from the Kolaghat, Alinan, Siuri and Deemari villages near Tamluk in the Purba Medinipur district. Then, we assessed different water quality parameters, such as temperature, turbidity, pH, DO, BOD, salinity, alkalinity, and hardness. We studied the premonsoon phase (Feb-May) and assessed the impact of these parameters on the production of shrimp species. We identified M. rosenbergi, M. brevicornis, M. monoceros, and Penaeus vannamei as shrimp species. We also compared the data from 2022 to 2024 (Feb-May) and observed yields of 40%, 60%, and 30% in 2022, 2023 and 2024, respectively.

Ecological compensation mechanism controlled by both river ecological water demand and regional water rights

River ecological protection and rational utilization of water resources provide an important support for the sustainable development for human beings and nature. In view of the lack of ecological compensation research on river ecological water demand and socio-economic water demand, a mechanism and methodology for ecological compensation based on the synergistic control of river ecological water demand and river water rights allocation is proposed. The variable monthly flow method and the improved dynamic calculation method are applied to obtain the river basic and suitable ecological water demands as the river protection threshold. A two-layer decision model for water rights allocation is established, which realizes the cascading allocation of initial water rights from city to counties to sectors, and the socio-economic water usage threshold for each level is obtained based on the model. Developing compensation discrimination guidelines under the dual-threshold synergistic control and using the unilateral water resources value by sub-sector as the compensation standard, realize the quantification and sharing of compensation funds. The Nanyang section of the Bai River basin in China is used as an example. The ecological compensation value for wet year (2011), normal year (2012), and dry years (2014–2013) are 0, 15.09 × 108 and 12.04 × 108 (average value for dry years) RMB. The adoption of suitable ecological water demand thresholds in 2012 increases the ecological protection requirements thus leading to an internal compensation situation between Nanyang County and Xinye County. From 2014 to 2016, river runoff continued to be low, and excessive water intake from upstream lead to a chain of compensation situations in the midstream and downstream. It is essential to establish a basin and regionally nested ecological compensation mechanism. The research results are conducive to improving the eco-compensation theory and provide scientific references for water resources management and high-quality development in the basin.

Lacustrine groundwater discharge-derived carbon and nitrogen to regulate biogeochemical processes as revealed by stable isotope signals in a large shallow eutrophic lake

Eutrophic shallow lakes are hotspots of carbon (C) and nitrogen (N) accumulation and transformation, and are increasingly recognized as important sources of greenhouse gases (GHGs: CO2, CH4 and N2O). Lacustrine groundwater discharge (LGD) is a crucial component of the water budget and terrestrial material delivery for lakes, but its interplays with intrinsic CN biogeochemical processes remain less tackled. In this study, C and N ingredients and multiple stable isotopes (δ2H, δ18O, δ13C, and δ15N) were measured seasonally in groundwater, river water and lake water of a large eutrophic shallow lake in eastern China. The results revealed that groundwater is enriched with various forms of C and N that have similar sources and pathways as surface water in the lake and rivers. The isotope balance model also indicated that LGD derived C and N contribute significantly to lake inventories in addition to river runoff. These allochthonous C and N provide extra substrates for related biogeochemical processes, such as algae proliferation, organic matter degradation, methanogenesis and denitrification. Simultaneously, the excess oxygen consumption leads to depletion and hypoxia in the lake, further facilitating the processes of methanogenesis and denitrification. LGD functions not only as an external source of C and N that directly increases GHG saturations, but also as a mediator of internal CN pathways, which significantly affect hypoxia formation, GHG productions and emissions in the eutrophic lake. This study highlights the unrevealed potential regulation of LGD on biogeochemical processes in the eutrophic lake, and underscores the need for its consideration in environmental and ecological studies of lakes both regionally and globally.

Purification of mercury in Ciujung River water, Banten province, Indonesia by adsorption method using Fe3O4 nanoparticles

The Ciujung River, one of the main rivers in Banten province, Indonesia, plays an important role in agriculture and sanitation. However, the increasing use of heavy metals, especially mercury, by industries along the Ciujung River has caused significant environmental pollution. This issue requires considerable attention to ensure that environmental problems can be resolved immediately. This study evaluated the feasibility of Fe3O4 as a potential material to adsorb mercury in Ciujung River water originating from industrial waste. The adsorption efficiency was assessed by examining the effects of pH, adsorbent weight, and contact time. In addition, the adsorption capacity of Fe3O4 was analyzed using adsorption kinetics and isothermal models. The findings of the study showed that the adsorption process of Hg(II) using Fe3O4 followed pseudo-first-order kinetics with an R2 value of 0.998. Furthermore, the research data correlated well with the Freundlich isotherm. After Hg(II) was treated with Fe3O4 for a contact time of 90 min, its concentration in pure water samples was reduced, with an adsorption capacity of 263.04 mg/g. The study also evaluated the reusability and stability of Fe3O4 to reduce Hg(II) in Ciujung River water samples. Fe3O4 achieved a maximum adsorption capacity of 218.17 mg/g and was able to selectively absorb Hg(II) even in the presence of other heavy metals, with a desorption rate of 99.39 %. The desorption rate remained high after the fifth cycle, with a value of 87.65 %. These results indicate that Fe3O4 has strong potential as an adsorbent for treating industrial wastewater from the Ciujung River.

Resource recovery of water treatment plant sludge and river sediment as phosphorus removal material: feasibility and mechanisms

ABSTRACT Excessive phosphorus is a critical contributor to eutrophication, necessitating the use of substantial amounts of phosphorus removal materials. To address the challenge of managing water treatment plant sludge and river sediment while also supplying mass-produced phosphorus-removing materials for projects targeting phosphorus removal in water bodies, this paper attempted to study the feasibility of preparing phosphorus removal materials by mixing and calcining water treatment plant sludge and river sediment (C-WTPS/RS). The study examined the transformation of phosphorus forms in C-WTPS/RS before and after adsorption. Furthermore, X-ray fluorescence spectrometer, zeta potential, scanning electron microscope, Brunauer–Emmett–Teller equation, Barrett–Joyner–Halenda model, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were employed to elucidate the phosphorus removal mechanisms. The results showed that C-WTPS/RS was effective in removing phosphorus from water and preventing the release of phosphorus from the sediment. Additionally, C-WTPS/RS had a low risk of releasing phosphorus and metals within the pH range of natural water bodies. These proved that it is feasible to remove phosphorus by C-WTPS/RS. After adsorption, the increased phosphorus in C-WTPS/RS was mainly dominated by the non-apatite inorganic phosphorus within inorganic phosphorus. The main phosphorus removal mechanisms of C-WTPS/RS were physical adsorption, electrostatic adsorption, chemical precipitation, and ligand exchange.

Mechanochemically synthesized flower-like bismuth oxyhalides: An electrochemical platform for diclofenac detection

The emerging drug diclofenac (DICF) has been found to penetrates aquatic systems at alarming concentrations and poses serious and irreversible ecotoxicological threats around the world. In this work, we present the solid-state mechanochemical synthesis of 3D flower-like bismuth oxyhalides (BiOX, where X = Cl, Br, and I) as electrode materials for electrochemical detection of DICF. The characteristics of the flower-like BiOX are systematically investigated using spectroscopic and microscopic techniques. The BiOI-modified glassy carbon electrode (GCE) exhibits superior electrochemical performance for DICF detection compared to the pristine GCE, BiOCl/GCE, and BiOBr/GCE. The 3D flower-like architecture of BiOI facilitates favorable electrocatalytic activities due to its abundant electroactive sites, good conductivity, large surface area, and fast ion diffusion. Notably, the BiOI/GCE displays wide linear ranges (0.5–11.3 & 11.3−76), a low limit of detection (0.11 μM), high sensitivity (1.33 μA μM–1 cm–2), excellent repeatability (2.91 %), good reproducibility (2.88 %), and anti-interfering ability (<±5 %). To validate the practicality of the fabricated BiOI/GCE, the quantitative detection of DICF in human urine and river water is demonstrated and achieves acceptable recovery values. This study introduces an innovative approach to design and produce electrode materials with distinct properties, enabling enhanced electrocatalysis for various electrochemical sensing applications.

Investigation of the Effects of Erzurum Province Wastewater Treatment Plant on the Karasu River Water Quality

This study was carried out to investigate the effects of the wastewater treatment plant located in the Aziziye District of Erzurum Province on the Karasu River. For this purpose, water samples were taken from 3 stations for a year between 2022-2023. The mean water temperature was measured in situ during sampling as 13.8 ˚C, the mean pH value was 7.7, the mean electrical conductivity was 403 µs/cm, and the mean dissolved oxygen value was 6 mg/l. The mean total suspended solid (TSS) amount was determined as 46.7 mg/l, the mean chemical oxygen demand (COD) concentration was 28.9 mg/l, the mean biological oxygen demand (BOD) concentration was 18.5 mg/l, the mean total nitrogen (TN) concentration was 4.47 mg/l, the mean nitrate (NO3) concentration was 5.35 mg/l, the mean nitrate nitrogen (NO3-N) concentration was 1.21 mg/l, the mean total hardness (TH) was 155 mg/l, the mean ammonium (NH4) concentration was 2.75 mg/l, and the mean ammonium nitrogen (NH4-N) concentration was 2.16 mg/L. As a result, it was determined that the Wastewater Treatment Plant positively affected some water quality parameter values of the Karasu River.

Low oxygen adsorption energy barrier architectures to facilitate microenvironmental photocatalytic disinfection in Wei River

Photocatalytic disinfection is an eco-friendly strategy that uses solar energy to purify bacteria-contaminated water. However, improvements in photocatalysts tend to focus on thermodynamics while neglecting kinetic interactions that involve oxygen. Here, we propose the MOF-on-MOF heterojunction NR-HKUST-1@Cu/ZIF-8 (NH@CZ) for kinetic photocatalytic disinfection; the heterojunction reduced bacterial load by nearly 8-log within 20 min. The NH@CZ structure exhibits a high specific surface area with Cu2O8 and CuN4 sites that provide substantial oxygen storage capacity and binding sites. In vitro experiments demonstrated the effective delivery of oxygen to photocatalytic reactions via NH@CZ, leading to enhanced superoxide radical (·O2-) generation. Experimental analysis and theoretical calculations confirm that the formation of heterojunctions in NH@CZ provides an efficient pathway for oxygen reduction by reducing the energy barrier associated with oxygen adsorption. Mechanistic studies show that reactive oxygen species (ROS) disrupt bacterial cell membranes, resulting in the release of cellular contents (e.g., potassium ions and macromolecular proteins) and subsequent cell death. Furthermore, the oxygen-carrying NH@CZ killed all microorganisms in Wei River water samples within 45 min. The MOF-on-MOF heterojunction offers a promising pathway to enhance ROS generation and provides valuable insights into advances in water disinfection technology.

A new perspective on contaminants as "activators": Aromatic amine groups promoted degradation of tetracycline by ferrate(VI)

Occasionally, our group found that the degradation of tetracycline by ferrate(VI) could be promoted by four co-exist contaminants, containing aromatic amines (ofloxacin, diatrizoic acid, sulfadiazine and alachlor). This study investigated the promotion of aromatic amine groups on tetracycline degradation by ferrate(VI) by using aniline as a model compound. The results implied that the presence of aniline increased the degradation rate of tetracycline by 2.76 times, and the enhancement was weakened gradually with the decrease of pH from 10 to 7.5. The generation of Fe(IV) and·OH by the reaction between ferrate(VI) and aniline was proposed to enhance the degradation of tetracycline, supported by quenching experiments, electron paramagnetic resonance (EPR) and theoretical calculations. A positive correlation was found between the rate constant of tetracycline degradation and the electron-donating ability of the substituted amines (quantified by the Hammett substituent constants). In addition, the degradation of tetracycline was remarkably inhibited by HA and some inorganic ions such as NO3-, SO42-, Cl-, Ca2+, and Mg2+, and the inhibition also happened in the Songhua River water and the secondary effluent. The present study provided an insight into the complex oxidation process for the degradation of micropollutants containing aromatic amine by ferrate in water treatment.

Assessment of poly(diallyl dimethyl ammonium chloride) and lime for surface water treatment (pond, river, and canal water): seasonal variations and correlation analyses.

The present study deals with the assessment of different physicochemical parameters (pH, electrical conductivity (E.C.), turbidity, total dissolved solids (TDS), and dissolved oxygen) in different surface water such as pond, river, and canal water in four different seasons, viz. March, June, September, and December 2023. The research endeavors to assess the impact of a cationic polyelectrolyte, specifically poly(diallyl dimethyl ammonium chloride) (PDADMAC), utilized as a coagulation aid in conjunction with lime for water treatment. Employing a conventional jar test apparatus, turbidity removal from diverse water samples is examined. Furthermore, the samples undergo characterization utilizing X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The study also conducts correlation analyses on various parameters such as electrical conductivity (EC), pH, total dissolved solids (TDS), turbidity of raw water, polyelectrolyte dosage, and percentage of turbidity removal across different water sources. Utilizing the Statistical Package for Social Science (SPSS) software, these analyses aim to establish robust relationships among initial turbidity, temperature, percentage of turbidity removal, dosage of coagulant aid, electrical conductivity, and total dissolved solids (TDS) in pond water, river water, and canal water. A strong positive correlation could be found between the percentage of turbidity removal and the value of initial turbidity of all surface water. However, a negative correlation could be observed between the polyelectrolyte dosage and raw water's turbidity. By elucidating these correlations, the study contributes to a deeper understanding of the effectiveness of PDADMAC and lime in water treatment processes across diverse environmental conditions. This research enhances our comprehension of surface water treatment methodologies and provides valuable insights for optimizing water treatment strategies to address the challenges posed by varying water sources and seasonal fluctuations.

Two-dimensional distribution of arsenic species in the riparian zone regulated by As-Fe co-transformation under varying river water proportions and bicarbonate concentrations

Arsenic (As) contamination of groundwater is a major issue in global environmental health. In the riparian zone, mixing river water and groundwater with different substances is proposed to affect arsenic transformation and distribution. However, the distribution of arsenic species in the riparian zone and its co-transformation with iron under varying river water proportions and bicarbonate (HCO3–) concentrations remain unclear. The two-dimensional distributions of arsenic species, including exchangeable (Ex-As), carbonates-bounded (Carb-As), FeMn(hydr)oxide-bounded (Ox-As), organic-bounded (Om-As) and residual arsenic (Res-As), were investigated in three typical profiles of the riparian zone near the lower reaches of the Hanjiang River, China. The apparent enrichment of arsenic in the pore water, either As(III) and As(V), and in the sediment, mainly Carb-As and Ox-As, were observed in the profiles. The correlation analysis showed that the distributions of arsenic species in the riparian zone were primarily related to dissolved or total organic matter (DOC or TOC), Fe, HCO3–, dissolved oxygen (DO) and oxidation–reduction potential (Eh). Further batch experiments mixing simulated river water and groundwater with different proportions and HCO3– concentrations demonstrated that the forming of the arsenic-rich area in the riparian sediment was derived from the oxidation of Fe(II) and As(III) from groundwater, controlled by the varying DO from river water and HCO3– from organics degradation. These results provide more knowledge of the transforming process of arsenic in the riparian zone and a better understanding of the role of the riparian zone in arsenic restraint.

Enhancing Fenton-like reaction mediating performance of covalent organic frameworks through porosity modification

Covalent organic framework (COF) catalytic photocatalysts mediating Fenton-like reactions have been applied to the treatment of organic dyes in printing and dyeing wastewater. However, the photocatalytic performance of original COF is often unsatisfactory. This study investigated the impact of porosity modification strategies on the performance of COF photocatalysts in mediating the removal of organic dyes via Fenton-like reaction. Porosity modification was achieved by increasing the concentration of acetic acid (HAc) catalyst during COF preparation. The modified TAPB-DMTA COF (12M COF) exhibited excellent adsorption and photocatalytic properties. The Fenton-like reaction mediated by 12M COF photocatalysis removed nearly 96% of malachite green (MG) within 20 min, with a rate constant of 0.091 min−1, which was 2.9 and 6.5 times higher than that of g-C3N4 and original COF under the same reaction conditions, respectively. Additionally, the modulation mechanism of porosity modification on COF photocatalysis was explored. The conduction band (CB) of COF was reduced from −0.14 eV to −0.38 eV after porosity modification, facilitating the generation of longer-lived O2•- in the reaction system, which was conducive to efficient MG removal. Anti-interference experiments showed that the photocatalytic Fenton-like reaction system based on 12 M COF was less affected by common anions, cations and dissolved organics, while maintaining a high MG removal rate in tap water, mid-water, secondary clarifier effluent and river water. In summary, porosity modification was an effective strategy to improve the catalytic performance of original COFs. This study presented an efficient metal-free photocatalyst modification strategy for the Fenton-like reaction while avoiding the production of toxic by-products during dye degradation.

Nitrogen fate in riparian zones: Insights from experiments and analysis of sediment porosity and surface water-groundwater exchange

Riparian zones play a vital role in the river ecosystem. Solutes in vertical riparian zones are transported being by alternating hydraulic gradients between river water and groundwater, due to natural or human activities. This study investigates the impacts of porous sediments and alternating rate of surface water-groundwater on nitrogen removal in the riparian zone through experiments based on the field sampled. The experimental results, combined with dimensionless numbers (Péclet and Damköhler) and Partial Least Squares-Path Modeling, analyze the nitrogen fate responding to hydrodynamics changes. The results show that increased sediment porosity contributes to the ammonium removal, particularly when the oxygen content of river water is low, with the removal rate up to 72.57%. High ammonium content and dissolved organic carbon (DOC) in rural rivers lead to a constant low-oxygen condition (4 mg/L) during surface water-groundwater alternation, and promote denitrification. This threatens groundwater with ammonium pollution and causes accumulation at the top of vertical riparian zones during upwelling, potentially causing secondary river pollution. However, increasing the alternating rate hinders the nitrate denitrification and drastically changes in the redox environment of the riparian zone, despite contributing to ammonium removal. Rapid oxygen consumption during aerobic metabolism and nitrification in groundwater-surface water exchange created favorable conditions for denitrification. Floodplains sediment porosity is unfavorable for nitrification. This study improves understanding of coupled hydrologic and solute processes in vertical riparian zones, informing strategies for optimizing nitrogen attenuation and riparian zone construction.

Comprehensive monitoring of contamination and ecological-health risk assessment of potentially harmful elements in surface water of Maroon-Jarahi sub-basin of the Persian Gulf, Iran.

The increase in heavy metal concentration in water bodies due to rapid industrial and socio-economic development significantly threatens ecological and human health. This study evaluated metal pollution and related risks to ecology and human health in the Maroon-Jarahi river sub-basin in the Persian Gulf and Oman Sea basin, southwest Iran, using various indicators. A total of 70 water samples were taken from the sampling sites in the Maroon, Allah, and Jarahi sub-basins and analyzed for nine heavy metals. According to the results, the mean concentration of metals in the sampling locations across the entire sub-basin of Maroon-Jarahi was observed as follows Iron (528.22µg/L), zinc (292.62µg/L), manganese (56.47µg/L), copper (36.23µg/L), chromium (11.78µg/L), arsenic (7.09µg/L), lead (3.43µg/L), nickel (3.23µg/L), and cadmium (1.38µg/L). Most of the metals were detected at the highest concentration in the sub-basin of the Jarahi River. The Water Quality Index (WQI) index in the basin varied from 18.74 to 22.88, indicating well to excellent quality. However, the investigation of the pollution status at the monitoring stations, based on the classification of Degree of Contamination (CD) and Heavy Metal Pollution Index (HPI) indices, revealed that they are in the category of relatively high pollution (16 < CD < 32) to very high (32 ≤ CD), and in the low pollution category (HPI < 15) to high pollution (HPI < 30), respectively. According to the three sub-basins, the highest amount of WQI, HPI, and Cd was observed in the stations located in the sub-basins of the Jarahi River. The calculation of Heavy Metal Evaluation Index (HEI) also indicated that only 10% of the monitoring stations are in moderate pollution (10 < HEI < 20), while in other monitoring stations the HEI level is less than 10. The Potential ecological risk factors ( ) of an individual metal was obtained as follows: Cd (173.70) > As (131.99) > Zn (57.52) > Cu (55.39) > Ni (48.98) > Cr (21.57) > Pb (0.71), revealing that Cd and As are the main elements responsible for creating ecological risk in the studied area. The Maroon-Jarahi watershed included areas with ecological risks that ranged from low (PERI ≤ 150) to very high (PERI ≥ 600). HI and ILCR health indicators indicated that consumption and long-term contact with river water in the study area can cause potential risks to human health, especially children. Moreover, the findings, the highest level of pollution and health risk for both children and adults, considering both exposure routes, occurred in the Jarahi River sub-basin, suggesting that those who live in the vicinity of the Jarahi River are likely to face more adverse health effects. In addition, the findings of the evaluation of the relationship between land use patterns and water quality in the studied basin showed that agricultural lands acts as a main source of pollutants, but forest lands play an important role in the deposition of pollutants and the protection of water quality at the basin scale. In general, the results of pollution indicators, risk assessment, and statistical techniques suggest that the lower sub-basin, the Jarahi area, and the Shadegan wetland are the most polluted areas in the investigated sub-basin due to excessive discharge of agricultural runoff, industrialization, and rapid urbanization. Thus, special measures should be considered to reduce the risks of HMs pollution in the sub-basin of the Maroon-Jarahi watershed, especially its downstream and the impact of agricultural land use on water quality should be taken into consideration in basin management plans.

From flood to turbidity current: combined models to simulate continent to ocean sediment transport in the Var system, France

Turbidity currents are a form of gravity-driven flow that occurs in subaqueous environments. These currents contain a low volumetric percentage of particles but are very important in transporting them from coastal to deep-marine environments. In the Var sediment routing system, southeastern France, there is a sedimentary record of turbidity currents formed by submarine landslides and flooding of the Var River. In 2006, there was continuous monitoring of the marine section that recorded four turbidity currents. To explore the connectivity between the terrestrial source and marine basin we linked two reduced complexity models of sediment transport and landscape change. The aim of the paper is to combine two models, one dedicated to the prediction of river water and sediment run-off, and the second dedicated to the transport, erosion, and sedimentation by a turbidity current. The landscape evolution model CAESAR-Lisflood was used to model discharge and sediment yield. The behaviour of turbidity currents was modelled with the cellular automata model CATS. From calibration of the two models against observations of discharge and suspended sediment in the Var River system, we find that in 2006, two rainfall events would have led to hyperpycnal turbidity currents. These two events match well with two of the four-recorded events. Focusing on the largest event we find that the source pulse of sediment from the terrestrial environment is short-lived, less than half a day, but contains a significant quantity of fine particles. The event transferred on the order of 105 m3 of suspended sediment from source to sink. This study demonstrates that hyperpycnal turbidity currents can be generated with concentrations as low as 2-6 kg/m3 at the Var River mouth far below the theoretical 40 kg/m3 threshold, suggesting active convective sedimentation in the surface plume and sea-water dilution at the flooding river mouth. A substantial amount of sediment (35% of the input volume) is directly transferred towards the deepest part of the system during a short-living hyperpycnal turbidity current. However, a considerable (65%) part remains in the surface as a hypopycnal plume feeding the hemipelagic sedimentation.

Detection of PCBs and OCPs in the Irtysh River Water (GC-MS/MS) and ecological risk assessment

This study optimized a gas chromatography-tandem triple quadrupole mass spectrometry (GC-MS/MS) method for the determination of 21 persistent organic pollutants (POPs) in Irtysh River water, including 14 organochlorines (OCPs) and 7 polychlorinated biphenyls (PCBs). Factors such as column temperature ramping, selection of qualitative and quantitative ion pairs and collision energy were considered to achieve perfect separation and accurate quantification of all 21 target compounds. The limits of detection (LOD) for PCBs and OCPs ranged from 0.21 to 1.18 ng/L. Applying this method to detect POPs in the Irtysh River revealed concentrations of OCPs ranging from ND to 20.2 ng/L and PCBs from ND to 0.411 ng/L. Source analysis indicated that POPs in the Irtysh River mainly originate from historical industrial and agricultural activities, particularly the deliberate use of pesticides. To ensure ecological safety and human health, expanding the range of target analytes and monitoring periods is necessary. This study provides:•Qualitative and quantitative analysis methods for 7 PCBs and 14 OCPs.•Recoveries achieved ranged between 74.6 to 109 % with RSD less than 15 %.•Analysis of sources, transport pathways, accumulation status, and ecological risks of PCBs and OCPs in the Irtysh River.

Linking recharge water sources to groundwater composition in the Hindon subbasin of the Ganges River, India

Groundwater resources of the densely populated Indo-Gangetic Basin are under increasing pressure, not only from extensive groundwater abstraction, but also from contamination. In this study we aim to better understand how different recharge sources affect the hydrochemical and isotope composition of groundwater. We used the Hindon subbasin in Northern India as a case study. Recharge water sources and groundwater were analysed for hydrochemical variables and stable isotopes along a 50 km transect between the Yamuna and Ganges rivers. Groundwater samples were statistically clustered based on hydrochemical variables, and the spatial variation of the groundwater clusters was compared with recharge sources.Groundwater quality could be linked to both recharge from irrigation canal water as well as recharge from polluted river water of the Hindon and its tributaries. We could not directly link groundwater outside these related zones to their recharge source. However, we suspect that shallow polluted groundwater (< 40 m depth) is affected by recharge from agricultural areas and infiltration of municipal wastewater, whereas deeper unpolluted groundwater (40–80 m depth) originates from recharge by rain and river water under more pristine conditions. Our findings show that human activities significantly impact the quality of groundwater, as we found vertical recharge of clean irrigation canal water and polluted municipal, agricultural and river surface water (up to 40 m depth). At one location, groundwater at 75 m depth shows increased Cl, NO3 and SO4 concentrations, suggesting accelerated downward displacement of polluted shallow groundwater by pumping. Limited horizontal displacement was found. We present a conceptual model demonstrating the evolution from a previously unpolluted groundwater system discharging to the river, to a contemporary system with infiltration dominance of polluted river, municipal and agricultural water and local clean irrigation canal water. This model may be relevant for large parts of the Indo-Gangetic Basin.

Efficiency of Enterobacter asburiae and Vermicompost on the Peanut Growth and Yield

The combined use of endophytic nitrogen-fixing bacteria (ENFB) and organic manures is a trend in sustainable agricultural production. To investigate the effect of Enterobacter asburiae (E asburiae) and vermicompost (VCT) on farmland nutrients, yield, quality, and reduce arsenic uptake of peanuts. Three factors, which were: (i) E asburiae (inoculum and no inoculum); (ii) irrigation water (River and underground water); (iii) VCT (0.00 and 10.0 t ha-1), were designed by eight treatments (Trt) and four replications. E asburiae inoculation combined with 10 t VCT ha-1 application and river water (RW) irrigation that both raised soil nutrient properties and traits of peanut agronomy and yield traits, raised significantly fresh seed yield and reduced arsenic (As) absorption of peanut stems and seeds. fresh seed yield of peanut in treatments of E asburiae inoculation, RW irrigation and 10.0 t VCT ha-1, which were higher than non E asburiae inoculation, deep well water (DWW) irrigation and no VCT application, were 24.3, 26.9 and 15.4%, respectively. The peanut As contents in Trt of E asburiae inoculation, RWI and 10.0 t VCT ha-1 were lower than 7.78, 45.3 and 1.92% in stems and 13.2, 78.3 and 9.82% in seeds, respectively, compared to non-E asburiae inoculation, DWW irrigation and no VCT application. E asburiae was found out one potential species to promote soil nutrients, the peanut growth, yield, quality and As resistance, which will be used like biological fertilizers in the future

Chemical weathering processes in the Chinese Loess Plateau

Covered by erodible loess and affected by significant seasonal climate variations, chemical weathering in the Chinese Loess Plateau (abbreviated as CLP) has important effects on the hydrochemistry of the Yellow River and the global carbon cycle. However, chemical weathering processes in the CLP are still unclear. Based on 296 river water samples in the CLP in the different seasons, hydrochemistry, weathering processes, and their controlling factors were revealed. River waters in the CLP exhibited slightly alkalinity (pH = 8.4 ± 0.5) with much high total dissolved solids (TDS) values (691 ± 813 mg/L). The water types of river water in the CLP were primarily O42− − Cl− − Na+, HCO3− − Ca2+ − Mg2+, and SO42− − Cl− − Ca2+ − Mg2+. According to the forward model, evaporite dissolution has the largest contribution (55.0 % ± 0.2 %) to riverine solutes in the CLP, then followed by carbonate weathering (36.0 % ± 0.2 %) and silicate weathering (6.0 % ± 0.1 %). For spatio-temporal variations, the contribution of evaporite dissolution in the CLP decreased from northwest to southeast with higher proportion in the dry season, carbonate weathering increased from northwest to southeast with a higher proportion in the wet season, and silicate weathering showed minor spatio-temporal variations. Ca2+ and Mg2+ were affected by carbonate precipitation and/or incongruent calcite dissolution, and about 50 % samples exhibited cation exchange reactions. The physical erosion rate in the CLP, which was 372 ± 293 t·km−2·yr−1, varied greatly and was greater than that of the other worldwide rivers. Chemical weathering rates in the CLP showed an increasing trend southward. During the wet season, high runoff led to the release of evaporite and carbonate from loess, while the interfacial reaction kinetic limited the increase of the silicate weathering rates. The CO2 consumption budget by carbonate weathering (6.1 × 1010 mol/yr) and silicate weathering (1.6 × 1010 mol/yr) in the CLP accounted for 0.29 % and 0.08 % of the global carbon cycle, respectively. Meanwhile, the weathering proportion by sulfuric acids was relatively high with a CO2 release flux of 6.5 × 109 mol/yr. By compiling the data, we propose that the interfacial reaction kinetic and runoff controls CO2 consumption rate by silicate and carbonate weathering, respectively. These results contribute to the understanding of modern weathering processes of loess in the CLP, thus helping to deduce the environmental and climatic evolution of the basin.