Water Environment Research Articles

Pivotal Role of Multishelled Architecture in Nanoreactor with Spatial Confined Co3O4 for Peroxymonosulfate Activation and Contaminants Degradation

In recent years, cobalt‐based catalysts have been widely used in advanced oxidation technology to degrade pollutants in water environments. However, the reasons for the improved efficiency and performance of cobalt‐based catalysts with different shapes and structures on the activation of persulfate for contaminant degradation are still largely unknown. This study constructs different shapes and structures of cobalt‐based catalysts, namely, Co3O4 nanosphere, multishelled Co3O4 nanosphere (MSCONS), Co3O4 nanocube and multishelled Co3O4 nanocube, in combination with persulfate activation, on the degradation of tetracycline (TC) and bisphenol A (BPA), representative substances of antibiotics and endocrine disruptors in water environments. Batch experiments exhibit satisfactory TC (96.3%) and BPA (98.5%) degradation efficiency under MSCONS/peroxymonosulfate. Furthermore, MSCONS exhibits wide applicability under complex water matrix conditions. Consequently, an integration of density functional theory computations and intermediates analysis demonstrates that the synergy, rather than the isolated effects of radical and nonradical active species, broadens the degradation pathways of TC and BPA, thereby improving the removal efficiency. Overall, this study offers novel insights into the factors contributing to the enhanced performance of cobalt‐based catalysts with varying shapes and structures. Additionally, it proposes new research avenues for investigating the effects of shapes and structures on other transition metal‐based catalysts.

Cycloolefin Copolymers With a Multiply Rigid Structure for Protecting Triplet Exciton From Thermo- and Moisture-Quenching.

Polymeric room temperature phosphorescence (RTP) materials have been well developed and utilized in various fields. However, their fast thermo- and moisture-quenching behavior highly limit their applications in certain harsh environments. Therefore, the preparation of materials with thermo- and moisture-resistant phosphorescence is greatly attractive. Compared with common water-soluble polymers, cycloolefin copolymers (COC) show outstanding hydrophobicity and higher rigidity, even at elevated temperatures, being as a promising candidate to prepare phosphorescence materials with suppressed thermo- and moisture-quenching behavior. Herein, a type of COC bearing hydroxyl, ester, and adamantanyl side groups is synthesized. After dispersing various phosphors into this matrix, the resultant composites exhibit full-color RTP with lifetimes of 249-590 ms. Their luminescence does not show obvious quenching in water, acid, alkalinous, reductive, and oxidative environments. In the presence of both rigid COC matrix and rigid phosphors, the corresponding composite displays high-temperature phosphorescence performance. Even at 378 K, the composite can emit phosphorescence with a lifetime of 40-98 ms. The applications of these COC-based composites for imaging, information encryption, and anti-counterfeiting are thus explored.

Strength Properties and Water-Blocking Stability of Hydrophobically Modified Silty Clay

In this study, Qinghai silty clay was hydrophobically modified, and its engineering properties, including water-blocking performance, strength characteristics, and durability, were investigated under varying hydrophobic agent contents and compaction degrees. The findings reveal that: (a) The prepared hydrophobic soil exhibits excellent water repellency, significantly exceeding the threshold for extreme hydrophobicity. When the hydrophobic agent content reaches approximately 13%, the water droplet infiltration time peaks, and the moisture content after immersion remains at a relatively low level. (b) The hydrophobic soil barrier layer effectively blocks the upward migration of groundwater driven by capillary action. In the column test, after 15 days of capillary water action, the water content in the upper soil layer remains nearly unchanged, and the hydrophobic soil layer retains its dryness and excellent water-blocking performance. (c) Under optimal hydrophobic agent content, the unconfined compressive strength (UCS) of hydrophobic soil increases by approximately 48% to 68% compared to ordinary soil. Moreover, the strength improvement becomes more significant with higher compaction degrees. (d) Hydrophobic soil is most sensitive to alkaline environments, while its strength reduction rate in acidic and saline environments is slightly higher than in water environments. (e) It is recommended to maintain the hydrophobic agent content between 13% and 15.5% for Qinghai silty clay to achieve a balance between hydrophobicity, strength performance, and economic feasibility.

Research progress in the design and application of whole-cell biosensors for antibiotics

Antibiotics are chemicals with bactericidal or bacteriostatic activity produced by microorganisms and artificially synthesized. Since the discovery of penicillin by Alexander Fleming in 1928, antibiotics have been widely used in clinical treatments as well as in the animal husbandry and aquaculture, leading to antibiotic residues in soil, water, food and other environments. At the same time, antibiotic resistance is increasingly serious, which necessitates the discovery of novel antibiotics. In recent years, with the development of synthetic biology, researchers have developed a variety of whole-cell biosensors that can respond to antibiotics. These whole-cell biosensors use microbial cells to convert antibiotic signals into readable signals, which can not only perform dynamic detection of antibiotics simply, quickly, sensitively and accurately but also effectively discover novel antibiotics. This review comprehensively summarizes the reported whole-cell biosensors for antibiotics, classifies them into two types (specific and general), and elaborates on the design principles and applications of the two types of antibiotic biosensors. This review will provide reference for the construction and application of other whole-cell biosensors for antibiotics.

Low-Complexity 2D DOA Estimation via L-Shaped Array for Underwater Hexapod Robot

This paper takes underwater hexapod robot target grasping in an extremely shallow water environment as the research goal and carries out the research on a high-precision and low-complexity method of target positioning. We address the above problem of estimating the two-dimensional (2D) directions of arrival (DOAs) of targets, using an L-shaped ultrasonic array. Based on the above considerations, low-complexity 2D multiple signal classification (MUSIC) based on sparse signal recovery (SSR) is proposed to enhance the super-resolution capability and DOA estimation accuracy. In the first step, subspace dimension is determined based on space distance. Then, a mixed-norm method is exploited to construct the projection subspace and new noise subspace. Finally, the orthogonality between the noise and signal subspaces is used to estimate DOAs. Via a numerical simulations analysis, we illustrate that the proposed technique can enhance the accuracy of DOA estimation while also being robust against coherent sources and limited snapshots.

Assessment of flavivirus RNA stability and infectivity in various water environments

IntroductionFlaviviruses such as dengue virus (DENV), Zika virus (ZIKV), Japanese encephalitis virus (JEV), and Yellow fever virus (YFV) are mosquito-borne RNA viruses causing major public health threats in major parts of the world. While DENV and ZIKV have been detected in urine samples, data on the presence and stability of flaviviruses in the water environment are limited.MethodsIn this study, we determined the stability and infectivity of flavivirus in different water environments by utilizing RT-qPCR and plaque assay to explore the feasibility of environmental detection and surveillance of flaviviruses.ResultsViral RNA could be detected for up to 49-days, at 4 °C, 25 °C and 37 °C temperatures, and infectious particles could be detected for up to 7 days. While our findings showed that flaviviral RNA has higher stability and better detection rates at lower temperatures, the infectious capacity of flaviviruses was comparatively short at 7 days.ConclusionsOur results indicate that flaviviruses retains limited infectivity in general water environments and highlight the feasibility of detection and surveillance in various epidemiologic and environmental settings.

Immobilization of Peniophora incarnata F1 in PVA-SA-biochar matrix and its degradation performance and mechanism for erythromycin degradation.

Erythromycin is becoming one of the most common contaminants detected in surface water and wastewater, which poses a potential risk to ecological systems and human health. Until now, there is still no effective way to eliminate it. Herein, a novel and efficient erythromycin-degrading fungus Peniophora incarnata F1, capable of utilizing erythromycin as its sole source of carbon and energy, was isolated from contaminated sludge. Moreover, a fungal immobilization system was developed using polyvinyl alcohol (PVA), sodium alginate (SA) and rape straw biochar (RB) to enhance the removal ability of erythromycin. Under optimal conditions of 30°C and pH 6.0, the removal rate of erythromycin with PVA-SA-RB@F1 within 5d reached 89.90%, which is 31.43% higher than that of free strain F1 (58.47%). Furthermore, eight biodegradation products of erythromycin were identified, and five compounds were firstly reported. Based on these metabolites, we inferred erythromycin was transformed to simple products mainly by dehydration, desugar, dehydrogenation, ester bond hydrolysis and carbon chain cleavage reactions. Finally, PVA-SA-RB@F1 were applied to wastewater contained 10mg/L and 50mg/L erythromycin, with the removal rates of 100% and 64.97%, respectively. These results show that PVA-SA-RB@F1 can be used as an effective tool to remove erythromycin in water environment. Therefore, this study provides a feasible strategy for bioremediation of erythromycin polluted environment.

Research of Water Pollution Based on Vine Copula Function in the Min River Basin, China

At present, the protection of the ecological water environment in Min River Basin has achieved certain results, but certain problems remain that require strengthened ecological protection and environmental management. Understanding the connection between water quality factors and exploring the factors affecting water quality are of great significance in determining the pollution status of watershed water and promoting the comprehensive management of watershed water quality. In this study, water quality data collected from 20 monitoring stations were used to qualitatively and quantitatively evaluate the quality of waters in the watershed. Then, the joint distribution of water quality factors was constructed using the C-vine copula method, and the main influencing factors of water quality were explored using the D-vine copula structure. This approach facilitated the current study of the integrated status of water quality pollution. The results and conclusions of the current study are as follows: (1) A total of four tree structure levels were constructed using the model. The indicators with the strongest correlation with water quality were total phosphorus during the flood season and total nitrogen during the dry season. (2) After the introduction of condition variables, dissolved oxygen exhibited the strongest correlation with the rest of the variables during the flood season. Moreover, the permanganate index was most strongly correlated with the rest of the variables during the dry season. (3) Pollution discharges and industrial structure had a large impact on water quality. In particular, urban wastewater discharge, the share of primary industry, and per capita GDP were key drivers of water quality. Reducing urban wastewater discharge and optimizing industrial structure are beneficial for improving water quality. The research results have certain guiding significance for allowing Fujian to achieve water environment protection and sustainable development.

Design and Development of a Solar Panel Microcontroller Based Shallow Water Detection System with Radar

This study investigates the design and development of a microcontroller-based shallow water detection system, aimed at enhancing safety in areas prone to shallow water hazards. The project leverages advanced microcontroller technology, sensors, and real-time monitoring to identify and alertusers about the presence of shallow water levels in various environments. The system is designed with a focus on accuracy, reliability, and user-friendliness, ensuring that it meets the safety needs of diverse applications such as navigation,flood management, and recreational water activities.The shallow water detection system utilizes an ultrasonic sensor integrated with a microcontroller to measure water depth accurately. The collected data is processed and displayed on an LCD, providing real-time feedback on water levels. If the water depth falls below a predetermined threshold, the system triggers an alarm, alerting users to the potential risk. The device was tested with 30 participants, including boat operators, water safety personnel, and researchers, who evaluated the system's ease of use, functionality, and effectiveness.Results from the testing phase indicate that the system is highly effective in detecting shallow water levels, with a minimal margin of error. The alarm system successfully alerts users in real-time, minimizing risks such as damage to watercraft, accidents, or other hazards associated with shallow water environments. The system is portable, energy-efficient, and can be customized for specific applications, making it a versatile tool for both professional and recreational use.Based on the findings, the study concludes that this microcontroller-based shallow water detection system is well-suited for implementation in various settings, including marine navigation, irrigation management, and flood control. Its real-time monitoring and alert capabilities make it an invaluable tool for preventing accidents and ensuring safety. Future research could focus on integrating wireless communication and IoT functionalities to expand its applications and enable remote monitoring, enhancing its utility in larger-scale operations

Hydrophobic PU fabric with synergistic conductive networks for boosted high sensitivity, wide linear-range wearable strain sensor

Strain sensing fabrics are able to sense the deformation of the outside world, bringing more accurate and real-time monitoring and feedback to users. However, due to the lack of clear sensing mechanism for high sensitivity and high linearity carbon matrix composites, the preparation of high performance strain sensing fabric weaving is still a major challenge. Here, an elastic polyurethane (PU)-based conductive fabric (GCPU) with high sensitivity, high linearity and good hydrophobicity is prepared by a novel synergistic conductive network strategy. The GCPU fabric consists of graphene sheets (GS)/carbon nanotubes (CNTs) elastic conductive layer and a PU elastic substrate. GS and CNTs can be constructed into a synergistic conductive network, and the fabric is endowed with high conductivity (1.193 S m-1). Simulated equivalent circuits show that GS in the conductive network will break violently under applied strain, making the GCPU fabric extremely sensitive (gauge factor 102). CNTs are spatially distributed in GS lamellae, avoiding the phenomenon that the constructed synergistic conductive network is violently fractured under the applied strain, which leads to the decrease of linearity (0.996). Styrene-ethylene-butylene-styrene (SEBS) was used as a dispersant and binder to uniformly disperse and closely bond GS and CNTs into PU fabrics. In addition, the hydrophobicity of SEBS makes the GCPU fabric resistant to water environment (The contact angle is 123°). Due to the good mechanical stability of GCPU fabric, GCPU fabric has a wide strain range (0%-50%) and high cycle stability (over 1000 cycles). In practice, GCPU fabric can accurately simulate and detect the size and deformation motion of human body. Therefore, the successful construction of elastic fabrics with synergistic conductive networks provides a feasible path for the design and manufacture of wearable intelligent fabrics.

Cu/Cu2O/NH2-MIL-88B (Fe) heterojunction as the photocatalyst to remove hexavalent chromium heavy metal ions in water.

This work aimed at addressing the problem of hexavalent chromium pollution in the water environment, designing and preparing the Cu/Cu2O/NH2-MIL-88B (Fe) heterojunction material with NH2-MIL-88B (Fe) as the carrier, Cu/Cu2O was loaded on NH2-MIL-88B (Fe) by light-assisted reduction. The loading of Cu2O effectively improves the visible light absorption capacity of the composite material. The SPR effect of Cu improves the separation and transfer of photogenerated carriers in the composite material. Performance test results showed that under the condition of pH = 2, using ethanol as a sacrificial agent, Cu/Cu2O/NH2-MIL-88B (Fe) (15 wt%) had a photocatalytic adsorption reduction rate of Cr(vi) of 96.3% in 60 minutes of adsorption in the dark and 150 minutes of photocatalytic reduction, which was 1.39 times that of NH2-MIL-88B (Fe). In addition, the composite material had good stability and recyclability, and the reduction efficiency still reached 88.9% after three cycles.

Dynamic Outlier Slicing Allows Broader Exploration of Adaptive Divergence: A Comparison of Individual Genome and Pool-Seq Data Linked to Humic Adaptation in Perch.

How genetic variation contributes to adaptation at different environments is a central focus in evolutionary biology. However, most free-living species still lack a comprehensive understanding of the primary molecular mechanisms of adaptation. Here, we characterised the targets of selection associated with drastically different aquatic environments-humic and clear water-in the common freshwater fish, Eurasian perch (Perca fluviatilis). By using whole-genome sequencing (WGS) on a large population dataset (n = 42 populations) and analysing 873,788 SNPs, our primary aim was to uncover novel and confirm known footprints of selection. We compared individual and pooled WGS, and developed a novel approach, termed dynamic outlier slicing, to assess how the choice of outlier-calling stringency influences functional and Gene Ontology (GO) enrichment. By integrating genome-environment association (GEA) analysis with allele frequency-based approaches, we estimated composite selection signals (CSS) and identified 2679 outlier SNPs distributed across 324 genomic regions, involving 468 genes. Dynamic outlier slicing identified robust enrichment signals in five annotation categories (upstream, downstream, synonymous, 5'UTR and 3'UTR) highlighting the crucial role of regulatory elements in adaptive evolution. Furthermore, GO analyses revealed strong enrichment of molecular functions associated with gated channel activity, transmembrane transporter activity and ion channel activity, emphasising the importance of osmoregulation and ion balance maintenance. Our findings demonstrate that despite substantial random drift and divergence, WGS of high number of population pools enabled the identification of strong selection signals associated with adaptation to both humic and clear water environments, providing robust evidence of widespread adaptation. We anticipate that the dynamic outlier slicing method we developed will enable a more thorough exploration of adaptive divergence across a diverse range of species.

Size-specific mediation of the physiological responses and degradation ability of microalgae to sulfamerazine by microplastics.

Antibiotics and microplastics (MPs) are two classes of emerging contaminants that are commonly found in various water environments. However, how different sized MPs affect the toxicity and biodegradation of antibiotics remains poorly understood. We investigated the effects of polystyrene (PS) MPs with different particle sizes (100 nm and 30 μm) on the physiological responses and degradation behavior of Phaeodactylum tricornutum to sulfamerazine (SMR). Results showed that microalgae growth was inhibited by SMR, and MPs especially those of smaller size exacerbated the inhibitory effects of SMR on microalgae, including decreasing the content of chlorophyll a, carotenoids, malondiadehyde and superoxide dismutase activity. MPs exhibited low adsorption towards SMR, and MPs especially 30 μm MPs strengthened SMR photodegradation through leaching more organic chemicals. In comparison, 100 nm MPs obstructed the light, resulting in insignificant effects on photodegradation. Apart from photodegradation, SMR could be bioaccumulated and biodegraded by microalgae, and biodegradation was the main removal mechanism. The overall influence of MPs on SMR degradation by microalgae was a balance of the promotion on photodegradation and negative effects on microalgae growth, with the degradation efficiency and rate of SMR significantly lower in treatment of 100 nm MPs (0.0128 ± 0.0012 day-1, 30.13 ± 0.36 %) than treatments without MPs (0.0155 ± 0.0011 day-1, 32.90 ± 3.11 %) or with 30 μm MPs (0.0165 ± 0.0013 day-1, 34.46 ± 2.52 %). Overall, this study reveals the size-specific effects of MPs on the toxicity and degradation behavior of SMR, providing novel insights into the combined effects of SMR and MPs.

Keystone bacterial groups dominate Escherichia coli O157:H7 survival in long-term reclaimed water headwater stream.

Escherichia coli (E. coli) O157:H7 is a highly pathogenic zoonotic bacterium, with water serving as a key medium for its environmental transmission. However, the survival characteristics of E. coli O157:H7 in reclaimed water environments remain poorly understood, which has, to some extent, hindered the development of water reuse technologies. This study examined the survival dynamics of E. coli O157:H7 in a long-term reclaimed water headwater stream through inoculation experiments and identified its main drivers. The results showed that the survival time of E. coli O157:H7 was the longest in the headwater upstream (up to 62 days), gradually decreased as it flowed downstream. Among physicochemical factors, chloride ion, potential of hydrogen, and electrical conductivity were the main factors affecting the survival of E. coli O157:H7. The microbial diversity shown by the alpha diversity index had no significant impact on the E. coli O157:H7 survival. Meanwhile, certain keystone bacterial groups, such as Polynucleobacter, Roseomonas, and Luteolibacter, which are primarily involved in the decomposition of organic matter, suppressed E. coli O157:H7 survival in this stream, while Nitrospira, Dechloromonas, and Sphingomonas promoted the survival of E. coli O157:H7. Overall, the biotic factors have a more direct impact on the E. coli O157:H7 survival compared to abiotic factors in the reclaimed water-replenished stream and deserve more attention. Our research revealed higher biological risks in the upstream sections of the long-term reclaimed water headwater stream, which helped deepen our understanding of pathogen survival in water environments and enhancing our awareness of the biological safety of reclaimed water in ecological replenishment processes.

A Previously Unknown Building Structure in Ancient Olympia (Western Peloponnese, Greece) Revealed by Geoarchaeological Investigations and Its Interpretation as a Possible Harbor

The ancient site of Olympia is located on the northern fringe of the Basin of Makrisia at the confluence of the Kladeos and Alpheios rivers (western Peloponnese, Greece) and was used as a venue for the Panhellenic Games from Archaic times until the 4th century AD. Geophysical prospection (frequency domain electromagnetic induction and electrical resistivity tomography) was carried out as a basis for detailed geoarchaeological investigations. In doing so, we identified a previously unknown building structure adjacent to the Altis, the inner part of the sanctuary at Olympia. Situated south of the Southwest Thermae, this structure measures at least 100 m (WSW-ENE) by 80 m (NNW-SSE). Its external orientation is in line with the orientation of the Southwest Thermae and the Leonidaion. We retrieved sediment cores from 17 different locations in combination with high-resolution direct push sensing from inside the newly found structure. All cores revealed distinct units of organic-rich limnic sediments dominated by clay and fine silt. Geochemical and micropaleontological analyses of selected sediment samples indicate highly eutrophic conditions, as evidenced by elevated phosphorous concentrations and the dominance of the ostracod species Cyprideis torosa, which is able to live under low-oxygen conditions. Moreover, molecular biomarker analyses show a significant input of lipid fecal markers, implying strong anthropogenic pollution. Further, the limnic sediments include numerous charcoal remains and abundant diagnostic artifacts such as ceramic fragments and building material. Radiocarbon dating documents that these limnic conditions persisted within the building structure from at least the 5th century BC to the 6th century AD. The identified building structure lies in the immediate proximity to the Lake of Olympia, which was recently found to have existed from the mid-Holocene to the Medieval period. Its characteristic filling with fine-grained sediments and multiple indications for a strongly polluted and heavily used standing water environment let us hypothesize that it was possibly used as a harbor installation. A harbor at ancient Olympia could have been used to reach the sanctuary by boat and to transport goods of all kinds.

Global dissemination of Klebsiella pneumoniae in surface waters: Genomic insights into drug resistance, virulence, and clinical relevance.

The aquatic environment is a major pathway for the spread of antibiotic resistance (AR) among microorganisms. Among these, Klebsiella pneumoniae reveals high genome plasticity, adaptability, and the ability to colonize humans, animals, and the natural environment, awarding it a significant role in the spread of AR. This work presents an in-depth analysis of the whole sequences of 149 K. pneumoniae genomes isolated from surface waters available in databases. The sequences were obtained from 20 countries in five continents. The analyses showed a high genomic diversity of isolates, classifying them into 94 unique sequence types. The isolates carried numerous virulence and drug resistance determinants in their genomes, including genes for carbapenem and colistin resistance. The critical resistance genes were located on plasmids, indicating their high mobility and ease of access in water environments. Sublineage 258 members, in particular ST11, have been identified as important carriers of both important drug resistance determinants and key virulence factors, thus posing a substantial threat to human health. Our analysis revealed the direct transmission of drug-resistant and virulent clinical strains to the natural environment, highlighting the role of K. pneumoniae in the dissemination of drug resistance within the "One Health" framework. Surface waters represent an environment conducive to the spread and evolution of drug resistance, and K. pneumoniae plays a significant role in this process by providing clinically-significant antibiotic resistance genes to environmental recipients.

Efficient removal of cationic malachite green using co-pyrolyzed corn straw biochar-montmorillonite composites.

New efficient and sustainable methods for the removal of malachite green (MG) from environmental media are needed. In this study, corn straw was co-pyrolyzed with montmorillonite under a variety of conditions (400, 500, 600, and 700°C and 10-40wt% montmorillonite), without any use of toxic chemicals, to produce a series of biochar-clay composites. Characteristics of the composites that make them promising contaminant sorbents include a uniform lamellar-particle micromorphology, enhanced mesoporous structure and surface area (53.0m2g-1), and abundant and diverse oxygen/carbon-containing functional groups (i.e., O-H, C-O, C=C, and C-H). The composite produced at 600°C and 10wt% montmorillonite had the highest observed MG removal from aqueous solution (6572.1mgg-1, 99.6% removal rate). Adsorption of MG by the sorbent was attributed to multiple sorption mechanisms, including physical interaction, cation exchange, and π-π bonding interactions, and was modulated by intra-particle diffusion. This work highlights the potential of corn straw biochar-montmorillonite composites as a favorable adsorbent for environment remediation and water treatment.

Do you think medicines can be prescribed in a more eco-directed, greener way? A qualitative study based on public and prescriber focus groups on the impact of pharmaceuticals in Scotland’s water environment

ObjectivesThis qualitative study explored public and prescriber awareness of pharmaceutical pollution in the water environment and eco-directed sustainable prescribing (EDSP) as a mitigation strategy to reduce the environmental impact of...

The mechanism of microplastic fibers release in a front-loading washing machine

Microplastic fibers (with a diameter of less than 5 mm) generated by synthetic textiles during the washing machine laundering process are considered to be one of the primary sources of pollution in both water and land environments. This study aimed to investigate the impact of novel combinations of washing parameters on the release of microplastic fibers. A wall-mounted drum washing machine was chosen as the subject of research in order to comprehensively examine the influence of washing conditions on the release of microplastic fibers during the washing process. The results showed that the length of shedding microplastic fibers were between 300 and 400 µm. The diameter of the shedding microplastic fibers was 13 ± 1 µm. High amounts of water and high load can lead to an increase of fiber microplastic release. Abrasion between fabrics influenced the release of microplastic fibers according to the movement of the fabric, which could affect fiber directional migration conditions. The findings on microplastic fibers release will help in the development of better front-loading washers.

Spatial and temporal distribution characteristics and source apportionment of biogenic elements using APCS-MLR model in the main inlet tributary of Danjiangkou Reservoir.

Danjiangkou Reservoir has been widely concerned as the water source of the world's longest cross basin water transfer project. Biogenic elements are the foundation of material circulation and key factors affecting water quality. However, there is no comprehensive study on the biogenic elements in tributaries of Danjiangkou Reservoir, hindering a detailed understanding of geochemical cycling characteristics of biogenic elements in this region. Guanshan River, one of the main tributaries that directly enter the Danjiangkou Reservoir, was token as the research object. Spatiotemporal distribution characteristics of basic water quality parameters and biogenic elements were studied. Water quality was comprehensively evaluated through water quality index (WQI). Absolute principal component score-multiple linear regression (APCS-MLR) model was adopted to explore the main sources of biogenic elements. Results showed that, in terms of season, the concentrations of total nitrogen (TN), total phosphorus (TP), and dissolved organic carbon (DOC) were significantly higher in wet season than in dry season, while no significant differences were found for dissolved inorganic carbon (DIC) and dissolved silica (DSi). Spatially, the concentrations of dissolved carbon, DIC, TN, and TP in the middle and lower reaches were higher than that in the upstream. DOC concentration peaked in the middle reaches, while DSi showed higher concentrations in the upstream. WQI values indicated that the river water quality was between good and excellent, although the water quality in wet season was slightly worse than that in the dry season. PCA extracted five potential sources, which accounting for 84.12% of the total variance, including rock weathering, mixed source of sewage discharge and agricultural non-point source pollution, dissolved soil CO2, seasonal factor, and agricultural non-point source pollution. These sources contributed 38.96%, 12.33%, 13.54%, 23.95%, and 11.21% to river water quality parameters, respectively. Strengthening the monitoring of biogenic elements, controlling pollutant discharge, and exploring the relationship between biogenic elements and other pollutants are important for the water environment management in this basin.