Evaluation of the DGT passive samplers for integrating fluctuating concentrations of pharmaceuticals in surface water.

Diffusive gradients in thin films (DGTs) have been well-documented for the measurement of a broad range of organic pollutants in surface water. However, the performance has been challenged by the inherent periodic concentration fluctuations for most organic pollutants. Therefore, there is an urgent need to assess the true time-weighted average (TWA) concentration based on fluctuating concentration profiles. The study aimed to evaluate the responsiveness of DGT and accuracy of TWA concentrations, considering various concentration fluctuating scenarios of 20 pharmaceuticals in surface water. The reliability and accuracy of the TWA concentrations measured by the DGT were assessed by comparison with the sum of cumulative mass of DGT exposed at different stages over the deployment period. The results showed that peak concentration duration (1-5 days), peak concentration fluctuation intensity (6-20 times), and occurrence time of peak concentration fluctuation (early, middle, and late stages) have minimal effect on DGT's response to most target pharmaceutical concentration fluctuations (0.8 < CDGT/CTWA < 1.2). While the downward-bent accumulations of a few pharmaceuticals on DGT occur as the sampling time increases, which could be accounted for by capacity effects during a long-time sampling period. Additionally, the DGT device had good sampling performance in recording short fluctuating concentrations from a pulse event returning to background concentrations with variable intensity and duration. This study revealed a satisfactory capacity for the evaluation of the TWA concentration of pharmaceuticals integrated over the period of different pulse deployment for DGT, suggesting that this passive sampler is ideally suited as a monitoring tool for field application. This study represents the first trial for evaluating DGT sampling performance for pharmaceuticals with multiple concentration fluctuating scenarios over time, which would be valuable for assessing the pollution status in future monitoring campaign.

PFAS Contamination in Europe: Generating Knowledge and Mapping Known and Likely Contamination with "Expert-Reviewed" Journalism.

While the extent of environmental contamination by per- and polyfluoroalkyl substances (PFAS) has mobilized considerable efforts around the globe in recent years, publicly available data on PFAS in Europe were very limited. In an unprecedented experiment of "expert-reviewed journalism" involving 29 journalists and seven scientific advisers, a cross-border collaborative project, the "Forever Pollution Project" (FPP), drew on both scientific methods and investigative journalism techniques such as open-source intelligence (OSINT) and freedom of information (FOI) requests to map contamination across Europe, making public data that previously had existed as "unseen science". The FPP identified 22,934 known contamination sites, including 20 PFAS manufacturing facilities, and 21,426 "presumptive contamination sites", including 13,745 sites presumably contaminated with fluorinated aqueous film-forming foam (AFFF) discharge, 2911 industrial facilities, and 4752 sites related to PFAS-containing waste. Additionally, the FPP identified 231 "known PFAS users", a new category for sites with an intermediate level of evidence of PFAS use and considered likely to be contamination sources. However, the true extent of contamination in Europe remains significantly underestimated due to a lack of comprehensive geolocation, sampling, and publicly available data. This model of knowledge production and dissemination offers lessons for researchers, policymakers, and journalists about cross-field collaborations and data transparency.

Integrated management of groundwater quantity, physicochemical properties, and microbial quality in West Nile delta using a new MATLAB code and geographic information system mapping.

Groundwater is an excellent alternative to freshwater for drinking, irrigation, and developing arid regions. Agricultural, commercial, industrial, residential, and municipal activities may affect groundwater quantity and quality. Therefore, we aimed to use advanced methods/techniques to monitor the piezometric levels and collect groundwater samples to test their physicochemical and biological characteristics. Our results using software programs showed two main types of groundwater: the most prevalent was the Na-Cl type, which accounts for 94% of the groundwater samples, whereas the Mg-Cl type was found in 6% of samples only. In general, the hydraulic gradient values, ranging from medium to low, could be attributed to the slow movement of groundwater. Salinity distribution in groundwater maps varied between 238 and 1350 mg L-1. Although lower salinity values were observed in northwestern wells, higher values were recorded in southern ones. The collected seventeen water samples exhibited brackish characteristics and were subjected to microbial growth monitoring. Sample WD12 had the lowest total bacterial count (TBC) of 4.8 ± 0.9 colony forming unit (CFU mg L-1), while WD14 had the highest TBC (7.5 ± 0.5 CFU mg L-1). None of the tested water samples, however, contained pathogenic microorganisms. In conclusion, the current simulation models for groundwater drawdown of the Quaternary aquifer system predict a considerable drawdown of water levels over the next 10, 20, and 30 years with the continuous development of the region.

Spatiotemporal variations, health risk assessment, and sources of potentially toxic elements in potamic water of the Anday Stream Basin (Türkiye), Black Sea Region.

Monitoring and protecting freshwater habitats are paramount for a sustainable water management perspective. This study investigated potentially toxic elements (PTEs) in the potamic water of the Anday Stream Basin (Türkiye), Black Sea Region, for a hydrological year (from May 2020 to April 2021). Among PTEs, the highest average values were recorded for sodium (Na) at 41.3 mg/L and the lowest for mercury (Hg) at 0.009 µg/L and noted under quality guidelines. The stream was found to be at the level of "Low Heavy Metal Pollution" and "Low Contamination" based on the ecotoxicological risk indices. The highest calculated hazard quotient (HQ) value of 1.21E-02 for Cd was noted in the children via the dermal pathway and the lowest of 6.91E-06 for Fe in adults via the ingestion pathway. Results revealed a higher hazard index (HI) value of 1.50E-02 for Cd to children and the lowest of 1.98E-05 for Fe to adults. As a result of applying agricultural risk indices, the stream showed sodium adsorption ratio values less than 6 and was found to be "Excellent" for agriculture. However, the sodium percentage values were less than 20 and found "Permissible" and the magnesium hazard > 50 and noted as "Unsuitable" for agriculture. Statistical analysis revealed that natural factors mainly attributed to PTE contamination of the Anday Stream Basin.

Centurial deposition records of polychlorinated biphenyls and organochlorine pesticides in sediment cores from a plateau deep-water lake of China: Significance of anthropogenic impacts, transformation signals and ecological risks revealed by full congener analysis.

Lake Fuxian, the largest deep freshwater lake in China, has been suffering from increasing ecological and environmental issues along with the rapid urbanization and industrialization in the past 40 years. To better understand the historical pollution of persistent organic pollutants (POPs) in Lake Fuxian, comprehensive analyses of 209 polychlorinated biphenyl (PCB) congeners and 20 organochlorine pesticides (OCPs) were conducted in two intact sediment cores (Core V1 and Core V2). The total mass concentrations of PCBs ranged from 7.60 to 31.47 ng/g (dry weight basis) and 5.55 to 28.90 ng/g during the period of 1908-2019 in Core V1 and 1924-2019 in Core V2, respectively. PCBs exhibited a consecutive increasing trend from 1940s to 2019 in Core V1. The temporal trend of PCBs in Core V2 basically matched to the history of PCB usage and prohibition in China (increasing from 1940s to mid-1960s, a remarkable drop in mid-1970s, and then increasing until 2019). Moreover, low-chlorinated PCBs were dominant among PCB homologues. Mono-CBs, di-CBs, tri-CBs and tetra-CBs accounted for 86.71 %-98.57 % in sediment segments. The PCB sources included unintentional emission and atmospheric deposition, as well as biological transformation. The total mass concentrations of OCPs ranged from 0.74 to 3.82 ng/g in Core V1 and 0.35 to 2.23 ng/g in Core V2, respectively. Similar trend was observed in the two sediment cores with peaks in the early 1990s. The predominant OCPs were γ-hexachlorohexane (γ-HCHs), dieldrin and p,p'-DDD. The ecological risks posed by PCBs and p-p'-DDD in Lake Fuxian were relatively low. In contrast, dieldrin might pose a potential threat to exposed organisms and apparently adverse ecological effects were caused by γ-HCH. This study will provide important baseline information on historical POPs contamination of Lake Fuxian.

Organohalogen compounds in a hotspot for chemical pollution: Assessment in free-ranging Atlantic spotted dolphins (Stenella frontalis).

The assessment of chemical pollution in free-ranging living mammals is viable using remote biopsies and portrays a comprehensive scenario of environmental health. The Southwestern Atlantic Ocean holds incredible biodiversity, but it is under the constant and invisible threat of persistent organic pollutants (POPs) of anthropogenic origin, such as pesticides, brominated flame retardants, and industrial-use compounds (e.g., PCBs). Thus, this study aimed to assess the bioaccumulation of POPs (PCBs, DDTs, HCB, mirex and PBDEs) and natural organobromine compounds (MeO-BDEs) using gas-chromatography coupled to mass spectrometry in biopsy samples of Atlantic spotted dolphins (Stenella frontalis, n = 20) that inhabit and forage both inside and in adjacent areas to degraded (Guanabara Bay) and conserved (Ilha Grande Bay) coastal bays in the Southeastern Brazil. Among the studied compounds, PCBs were predominant in the contamination profile with median concentration of 97.0 µg.g-1 lipid weight (lw), followed by the sum of the p,p' isomers of DDT, DDD, and DDE of 11.0 µg.g-1 lw, the brominated flame retardants PBDEs of 1.6 µg.g-1 lw, and the other organochlorine pesticides mirex of 0.78 µg.g-1 lw, and HCB of 0.049 µg.g-1 lw. The MeO-BDEs were detected with a median concentration of 22.8 µg.g-1 lw. 85 % of the Atlantic spotted dolphins analyzed in this study presented PCB concentration that exceeded even the less conservative threshold limits for adverse health effects (41 µg.g-1 lw). This study shows that despite the conservation status of preserved bays, cetacean species foraging in these locations are still under increased threat. Hence chemical pollution demands local and global efforts to be mitigated.

Effects of dissolved oxygen changes in the benthic environment on phosphorus flux at the sediment-water interface in a coastal brackish lake.

In semi-enclosed coastal brackish lakes, changes in dissolved oxygen in the bottom layer due to salinity stratification can affect the flux of phosphorus (P) at the sediment-water interface, resulting in short- and long-term water quality fluctuations in the water column. In this study, the physicochemical properties of the water layers and sediments at five sites in Saemangeum Lake were analyzed in spring and autumn for four years, and phosphorus release experiments from sediments were conducted for 20 days under oxic and anoxic conditions during the same period. Sediment total phosphorus (T-P) decreased in autumn compared to spring due to mineralization of organic bound phosphorus, which was the most dominant P fraction. This may be related to the increase in the ratio of PO4-P to T-P in bottom waters in autumn, when hypoxia was frequently observed. The difference in P fluxes between oxic and anoxic conditions indicated that during autumn, as compared to spring, the release of phosphorus could have a more immediate impact on the water column during the formation of hypoxia/anoxia. The main factors influencing changes in P fluxes from sediments were identified through redundancy analysis. Additionally, based on the results of multiple regression analysis, sediment TOC, sediment non-apatite phosphorus, porewater pH, and porewater PO4-P were determined to be the most significant factors affecting P fluxes from sediments, depending on the season or redox conditions. Recently, the increased influx of seawater into Saemangeum Lake has been shown to contribute to water quality improvements in the water column due to a strong dilution effect. However, the sediment environment has shifted towards a more reduced state, leading to increased P release under anoxic conditions. Therefore, for future water quality management within the lake, it is necessary to consistently address the recurring hypoxia and continuously monitor phosphorus dynamics.

Analysis of the chemical characteristics and causes of high total hardness of groundwater in Jianghan Plain, China.

Familiarity with the chemical characteristics of regional groundwater can provide important guidance and reference for the development of regional groundwater exploitation. Jianghan Plain has been reported to have high groundwater total hardness (TH), resulting in the inability of local groundwater to be directly used as drinking water. In order to explore the causes of high TH, the paper analyzed the hydrochemical characteristics of shallow groundwater in Jianghan Plain combined with software of SPSS, JMP, and PHEEQC. The results showed that the cations in the groundwater in the area were mainly Ca2+, while the anions were mainly HCO3-. 20% of groundwater exceed the China national guideline for TH (i.e., 450 mg/L). The groundwater chemistry in the study area was controlled by three main factors of dissolution of carbonate rocks, human activities, and redox conditions, among which the interaction between water and rock had the greatest impact. The water carbonate rock interaction within Jianghan Plain was affected by various factors such as water flow and aquifers and showed a gradually weakening trend from west to east. This work not only strengthened the understanding of the causes of the high TH of groundwater in the region, but also provided reference value for regional groundwater environmental management.

Assessing the spatial distribution of elemental concentrations in surface sediments of Lake Victoria, Kenya: implications for ecological health and management.

Lacustrine sediment quality indicates the effects of both natural and anthropogenic activities on the ecosystem and communities. Despite its ecological importance, myriad complexities, and potential contaminant sources, the spatial distribution of surficial sediments in Lake Victoria's Winam Gulf has never been comprehensively documented. The purpose of this study was to assess the spatial distribution, pathways, and ecological risk of metal elements in the lake using a sediment matrix. Sediment samples were collected throughout the gulf in November 2022. The concentrations of Al, As, Cd, Co, Cr, Cu, Fe, K, Mn, Mo, Ni, P, Pb, Sb, Sn, Ti, Tl, U, and Zn were compared to different contamination metrics and ecological risk assessment indices. The average concentrations were in the following decreasing order: Zn > > > Cr > > Cu > Ni > Pb > Co > As > Cd with mean (± SD) of 185 ± 45 mg kg-1, 56 ± 15 mg kg-1, 45 ± 16 mg kg-1, 37 ± 11 mg kg-1, 24 ± 5 mg kg-1, 20 ± 7 mg kg-1, 3.9 ± 1.3 mg kg-1, 0.30 ± 0.09 mg kg-1, respectively, with strong indications of anthropogenic sources. Average concentrations were in the following decreasing order: Zn > > > Cr, Cu, Ni, Pb, Co, As, and Cd levels (mean ± SD) were 185 ± 45 mg kg-1, 56 ± 15 mg kg-1, 45 ± 16 mg kg-1, 37 ± 11 mg kg-1, 24 ± 5 mg kg-1, 20 ± 7 mg kg-1, 3.9 ± 1.3 mg kg-1 and 0.30 ± 0.09 mg kg-1 with strong indications of anthropogenic sources. The geo-accumulation index (Igeo) and enrichment factor categorisation schemes, respectively, classified these as uncontaminated (level 0) and depletion to minimal enrichment (level 1), while the ecological risk analysis classified them as "low risk". The mouth of the Nyando River, as well as Kisumu, Kendu, and Homa bays, were the most element-enriched and should be prioritised for focused monitoring and remediation. As a result, targeted land management of urban, industrial, transportation, and agricultural areas offers the opportunity to reduce sediment inputs into the lake ecosystem.

Health risk and pollution associated with trace metals in the waters of the Ebolowa municipal lake basin (Central Africa): evidence from hydrochemistry, quality indices, and statistical analyses.

The aim of this study was to investigate the status of trace metals (As, Cr, Cu, Ni, Pb, Fe, and Zn) and health and carcinogenic risk associated then in the Ebolowa Municipal Lake (EML) basin. To this end, 21 water samples were collected from the EML and its two tributaries, Mfoumou and Bengo'o, and analyzed by Quantofix method (nanocolors and visiocolor ECO) by using the MACHEREY-NAGEL photometer. The data were processed using multivariate statistics. The results showed that all the physicochemical parameters (pH, EC, and TDS), with the exception of TDS, comply with were within WHO limits. The distribution of trace metals at the three sites investigated was as follows: Zn (80-400 ± 1.58 µg/L) > Cu (50-150 ± 9.38 µg/L) > Fe (10-40 ± 0.71 µg/L) > Pb (1-20 ± 3.02 µg/L) > As (1-9 ± 0.44 µg/L) > Ni (1-9 ± 1.48 µg/L). However, the highest values were observed in the EML and the Mfoumou River, where Pb pollution was noted. Statistical analysis showed that anthropogenic inputs increase the presence of Cr, Cu, Pb, and Zn. Trace Metal Pollution Index values were below 15 at all sites, illustrating low levels of pollution. The trace metal evaluation index values for the Bengo'o stream are pure (mean = 0.6), slightly affected in the Mfoumou stream (mean = 2.0), and moderately affected in the EML (mean = 2.2). The toxicity load index values illustrate that the waters studied are toxic. The non-carcinogenic (HI) and carcinogenic (CR) health risk index values suggest a risk linked to oral ingestion in the LME and Mfoumou watercourses. The latter appears to be the main source of allochthonous pollutant input to the EML.

Assessing pesticide residues occurrence and risks in water systems: A Pan-European and Argentina perspective.

Freshwater ecosystems face a particularly high risk of biodiversity loss compared to marine and terrestrial systems. The use of pesticides in agricultural fields is recognized as a relevant stressor for freshwater environments, exerting a negative impact worldwide on the overall status and health of the freshwater communities. In the present work, part of the Horizon 2020 funded SPRINT project, the occurrence of 193 pesticide residues was investigated in 64 small water bodies of distinct typology (creeks, streams, channels, ditches, rivers, lakes, ponds and reservoirs), located in regions with high agricultural activity in 10 European countries and in Argentina. Mixtures of pesticide residues were detected in all water bodies (20, median; 8-40 min-max). Total pesticide levels found ranged between 6.89 and 5860 ng/L, highlighting herbicides as the dominant type of pesticides. Glyphosate was the compound with the highest median concentration followed by 2,4-D and MCPA, and in a lower degree by dimethomorph, fluopicolide, prothioconazole and metolachlor(-S). Argentina was the site with the highest total pesticide concentration in water bodies followed by The Netherlands, Portugal and France. One or more pesticides exceeded the threshold values established in the European Water Framework Directive for surface water in 9 out of 11 case study sites (CSS), and the total pesticide concentration surpassed the reference value of 500 ng/L in 8 CSS. Although only 5 % (bifenthrin, dieldrin, fipronil sulfone, permethrin, and terbutryn) of the individual pesticides denoted high risk (RQ > 1), the ratios estimated for pesticide mixtures suggested potential environmental risk in the aquatic compartment studied.

Microplastics in packaged water, community stored water, groundwater, and surface water in rivers of Tamil Nadu after the COVID-19 pandemic outbreak.

The increased load of plastic in waste streams after the COVID-19 pandemic outbreak has increased the possibility of microplastics (MPs) contamination channelling through the rivers and infiltrating the aquatic ecosystems. MPs in packaged water, community-stored water, groundwater, and surface water of Kaveri River (KR), Thamirabarani River (TR), Adyar River (AR), and Cooum River (CR) in Tamil Nadu were therefore investigated about 2 years after the COVID-19 pandemic outbreak. Using µFTIR and µRaman spectroscopy, polyamide, polypropylene, polyethylene, ethylene vinyl alcohol copolymer resin, and polyvinyl chloride were identified as the primary polymer types. The average number of MPs was 2.15 ± 1.9 MP/L, 1.1 ± 0.99 MP/L, 5.25 ± 1.15 MP/L, and 4 ± 2.65 MP/L in KR, TR, AR, and CR, respectively, and 1.75 ± 1.26 MP/L in groundwater, and 2.33 ± 1.52 MP/L in community stored water. Only LDPE was detected in recycled plastic-made drinking water bottles. More than 50% of MPs were found to be of size less than 1 mm, with fibrous MPs being the prevalent type, and a notable prevalence of blue-coloured microplastics in all the sample types. The Pollution Load Index (PLI) was >1 in all the rivers. Toxicity rating based on the polymer risk index (PORI) categorized AR and TR at medium risk (category II), compared to KR and CR at considerable risk (category III). Overall pollution risk index (PRI) followed a decreasing trend with CR > AR > KR > TR of considerable to low-risk category. Ecological risk assessment indicates a negligible risk to freshwater biota, except for four sites in the middle and lower stretches of Adyar River (AR - 2, AR - 4) and upper and lower stretches of Cooum River (CR - 1, CR - 3), located adjacent to direct sewer outlets, and one location in the lower stretch of Kaveri River (KR - 9), known for fishing and tourist activities.

The impact of the COVID-19 pandemic on the seawater quality of Ha Long Bay, Vietnam.

Ha Long Bay is a UNESCO World Heritage Site in Vietnam with unique natural scenery. Development and socio-economic activity impact its water quality. In the context of the Vietnam National Standards, historical follow-up data taken over a five-year period (2016 to 2020), for twenty-eight widely dispersed sampling sites, has been used to carry out a temporal assessment of seawater quality utilizing a Water Quality Index (WQI) method. The analysis shows that the seawater quality is generally acceptable over this period. However, the calculated WQI values for the "pandemic year" of 2020 compared to the data for 2016 to 2019, demonstrate a significantly lesser impact for the bay overall and, more specifically, for seventeen individual sites. Ten sites remain unaffected, and one site shows a significantly higher impact. This study demonstrates how the occurrence of the pandemic in 2020 may be exploited for the interrogation of anthropogenic impacts around the bay.

Assessment of the accumulation level and ecological risk of heavy metals in surface sediments of Bong Mieu River, Quang Nam Province, Vietnam.

This study assessed the accumulation levels and ecological risks associated with seven heavy metals (As, Pb, Cd, Hg, Cu, Cr, Zn) in the surface sediments of the Bong Mieu River in Quang Nam Province, Vietnam. The sampling encompassed 10 locations (S1-S10), considering areas both impacted and less impacted by gold mining activities. The findings revealed elevated levels of heavy metal pollution and associated ecological risks attributable to gold mining. Heavy metal content varied within specific ranges: As (70.6-341.2 mg/kg), Pb (216.3-504.1 mg/kg), Hg (0.138-0.252 mg/kg), Cd (0.91-1.51mg/kg), Cu (18.3-45.5 mg/kg), Cr (10.5-19.1 mg/kg), and Zn (49.3-84.1 mg/kg). Among these elements, Hg, Cu, Cr, Zn, and Cd adhered to the acceptable limits of VNTR 43:2017/MONRE (VNTR 43:2017/MONRE: National Technical Regulation/Ministry of Natural Resources and Environment of Vietnam). However, As and Pb content at all locations exceeded these limits significantly, with As being 4.1-20 times higher and Pb 2.3-5.5 times higher. The pollution of Pb and As was attributed to waste discharge from gold mining activities, which carry substantial amounts of these metals in various forms. The Igeo indicated heavy pollution of As and Pb in the sediments. Ecological risk factors were ranked as follows: E r i (As) > E r i (Pb) > E r i (Hg) > E r i (Cd) > E r i (Cu) > E r i (Cr) > E r i (Zn). The potential ecological risk (RI) due to combined heavy metal impact varied across locations, with S2 > S8 > S9 > S6 > S7 > S10 > S1 > S3 > S4 > S5, exhibiting low to moderate risk (RI values ranging from 73.4 to 252.8). The study area demonstrated high contamination levels for As and Pb, coupled with low to moderate potential ecological risks.

Standardization of monitoring data reassesses spatial distribution of aquatic microplastics concentrations worldwide.

Microplastics are found in continental and oceanic waters worldwide, but their spatial distribution shows an intricate pattern. Their driving factors remain difficult to identify and widely discussed due to insufficient and unstandardized monitoring data. Here, based on in situ experiments and hundreds of river samples from the Qinghai-Tibet Plateau, we formulate a model to standardize aquatic microplastic measurements. The model was applied to existing data on a global scale. These data are standardized to a 20 µm mesh size, resulting in a new spatial distribution of aquatic microplastic densities, with average concentrations of 554.93 ± 1352.42 items/m3 in Europe, 2558.90 ± 4799.62 in North America and 1741.94 ± 3225.09 in Asia. Excessive contaminations (microplastic concentration > 104 items/m3) are in the Yangtze River, the Charleston Harbor Estuary, the Bodega Bay and the Winyah Bay. We show that, based on these standardized concentrations, new driving factors could be used to predict the global or regional microplastic distribution in continental waters, such as the Human Development Index with a correlation of 75.86% on a global scale, the nighttime lights with a correlation of 37.26 ± 0.30% in Europe and 39.02 ± 0.54% in Asia, and the Mismanagement Plastic Waste with a correlation of 61.21 ± 19.86% in North America. Mapping standardized concentrations of aquatic microplastics enables a better comparison of contamination levels between regions and reveals more accurate hotspots to better adapt remediation efforts and future plastic pollution scenarios.

Occurrence of microplastics in fish gastrointestinal tracts belongs to different feeding habits from the Bangladesh coast of the Bay of Bengal.

The Bay of Bengal (BoB) is home to a range of commercially important species with different food habits and feeding features. Microplastic (MP) contamination in the fish of BoB, like in many other marine environments, is a significant environmental concern. The study aimed to investigate the presence of microplastics (MPs) in the gastrointestinal tracts (GITs) of selected commercial marine fishes from the Bangladesh coast of the BoB. Six fish species (Escualosa thoracata, Tenualosa ilisha, Johnius belangerii, Trichiurus lepturus, Planiliza parsia, and Mystus gulio) were investigated (n = 120) following hydrogen peroxide digestion, and floatation (saline solution) protocols. After analyses, a total number of 696 MPs (dimension 0.3 to 5 mm) were identified. Moreover, the highest occurrence of MPs in fish GITs was found in planktivorous fish (average of 7.7 items/individual), followed by omnivorous (average of 5.2 items/individual), and carnivorous fish (average of 4.6 items/individual) (p < 0.001). However, planktivorous E. thoracata showed the highest number of MPs per g of GIT (average of 30.99 items/g GIT), whereas T. ilisha showed the lowest count (average of 0.77 items/g GIT). Different types of MPs (fibers (19 to 76%), fragments (6 to 61%), films (8 to 35%), microbeads (0 to 5%), and foams (0 to 2%)) were also observed. In terms of the color of MPs, the transparent, black, green, and blue types were the most common. Polymers were found as polyethylene (35 to 43%), polyethylene terephthalate (28 to 35%), polyamide (20 to 31%), and polystyrene (0 to 7%). The study provides a significant incidence of MPs in fish from the Bangladesh part of the BoB, which is very concerning. Therefore, long-term research is indispensable to ascertain the variables affecting the presence of MPs in fish, their origins, and their potential effects on the BoB fisheries. Stringent policies on plastic use and disposal should be strongly urged in this coastal region.

Tolerance of the Australian halophyte, beaded samphire, Sarcocornia quinqueflora, to Pb and Zn under glasshouse conditions: Evaluating metal uptake and partitioning, photosynthetic performance, biomass, and growth.

Saltmarsh sediments are susceptible to accumulation of excessive concentrations of anthropogenically elevated metals such as lead (Pb) and zinc (Zn). The resident salt tolerant plants of saltmarsh ecosystems form the basal underpinning of these ecosystems. As such, metal-associated adverse impacts on their physiology can have detrimental flow-on effects at individual, population, and community levels. The present study assessed the accumulation and partitioning of ecologically relevant concentrations of Pb, Zn, and their combination in a dominant Australian saltmarsh species, Sarcocornia quinqueflora. Plants were hydroponically maintained under glasshouse conditions for 16 weeks exposure to either Pb (20 µg l-1), Zn (100 µg l-1), or their mixture. We evaluated the chronic toxicological effects of single and mixed metal treatments with reference to metal uptake and partitioning, photosynthetic performance, photosynthetic pigment concentration, biomass and growth. Lead was more toxic than Zn, and Zn appeared to have an antagonistic effect on the toxicological effects of Pb in S.quinqueflora in terms of metal uptake, photosynthetic performance, photosynthetic pigment concentrations, and growth. Indeed, the tolerance index was 55 % in plants treated with Pb compared to 77 % in Zn treated plants and 73 % in Pb+Zn treated plants. Finally, Sarcocornia quinqueflora primarily accumulated both Pb and Zn in roots at concentrations exceeding unity whilst translocation of these metals to above ground tissues was restricted regardless of treatment. This suggests that S. quinqueflora may be suitable for phytostabilisation of Zn, and of Pb particularly in the presence of Zn.

Natural pyrite-stimulative periodate activation: efficiency and mechanism study.

Natural pyrite (NP) is an alternative catalyst for wastewater purification via advanced oxidation processes (AOPs). However, the activation performance and mechanism of periodate (PI) by NP have not yet been revealed. Herein, this work examines the activation performance of NP towards PI and its application in the degradation of antibiotic wastewater. Interestingly, 95.69% of chlortetracycline (CTC) was degraded by NP within 20 min via PI activation. Besides, NP shows effective degradation of various pollutants such as rhodamine B (65.81%), sulfamethoxazole (89.04%), and sodium butylxanthate (99.77%) within 20 min. The active species quenching experiment suggested that the active species ∙ OH , IO 3 ∙ , 1O2 and the active complex of PI bonded with NP surface participated in CTC degradation. In addition, Fe(II) on NP surface is the main active site for PI activation, while Sn2- species accelerates the reduction of Fe(III) to Fe(II) and promotes sustained PI activation. This work provides new ideas for the application of NP in environmental pollution control.

Freshwater macroinvertebrates along the Nigeria-Cameroon border enhance the conservation value of the lower Guinea forest biodiversity hotspot.

In Nigeria and tropical Africa, the bias towards the protection of natural sites on account of terrestrial biodiversity or their resultant ecosystem services has led to a considerably low number of freshwater conservation studies in the region. To close this gap, six lotic freshwater systems in three different natural sites (Obudu Mountains, Agbokim Waterfalls, and Cross River National Park) along the Cameroon border of Nigeria were evaluated for the biodiversity of macroinvertebrates and some aspects of water quality in December 2021 and March 2022. Among other macroinvertebrate-related indices, the community conservation index (CCI), which considers the presence of threatened, rare, and notable species, was used for the conservation evaluation of the freshwater systems. The Ephemeroptera-Plecoptera-Trichoptera (EPT) species were notably rich at the sites, with over 12 species each at the Afundu Stream, Kwa River, Cataract Stream, and Agbokim River. All of the sites had a very high conservation value, according to the CCI, which was greater than 20. Some Obudu sites (Grotto and Becheve streams), despite having fewer EPT taxa, had higher CCI than the Kwa or Agbokim River. This was due to the presence of the endangered damselflies (Africocypha centripunctata and Allocnemis vicki) at the Obudu sites and a rare mayfly species in Nigeria (Tricorythus tinctus), which was reported at Agbokim and Kwa Rivers. The presence of a notable damselfly genus (Pentaphlebia) at the Afundu stream of the Obudu Mountains also raises some hope that the critically endangered damselfly (Pentaphlebia gamblesi), whose adult was last seen in 1973, could still be alive at the site. Canonical Correspondence Analysis revealed that the proportion of scrapers had a strong association with high BOD and EC in Agbokim River, while the Becheve and Grotto streams which had high vegetal cover was positively associated with shredders. Also, increasing DO in Afundu Stream, Kwa River and Cataract Stream was positively associated with EPT richness. This study revealed that more freshwater ecological studies need to be conducted at isolated natural sites and protected areas in Africa. Findings from such studies have implications for preserving freshwater ecosystems of high conservation value from the various threats that characterize the Anthropocene.

Algae development in rivers with artificially constructed weirs: Dominant influence of discharge over temperature.

Algal blooms contribute to water quality degradation, unpleasant odors, taste issues, and the presence of harmful substances in artificially constructed weirs. Mitigating these adverse effects through effective algal bloom management requires identifying the contributing factors and predicting algal concentrations. This study focused on the upstream region of the Seungchon Weir in Korea, which is characterized by elevated levels of total nitrogen and phosphorus due to a significant influx of water from a sewage treatment plant. We employed four distinct machine learning models to predict chlorophyll-a (Chl-a) concentrations and identified the influential variables linked to local algal bloom events. The gradient boosting model enabled an in-depth exploration of the intricate relationships between algal occurrence and water quality parameters, enabling accurate identification of the causal factors. The models identified the discharge flow rate (D-Flow) and water temperature as the primary determinants of Chl-a levels, with feature importance values of 0.236 and 0.212, respectively. Enhanced model precision was achieved by utilizing daily average D-Flow values, with model accuracy and significance of the D-Flow amplifying as the temporal span of daily averaging increased. Elevated Chl-a concentrations correlated with diminished D-Flow and temperature, highlighting the pivotal role of D-Flow in regulating Chl-a concentration. This trend can be attributed to the constrained discharge of the Seungchon Weir during winter. Calculating the requisite D-Flow to maintain a desirable Chl-a concentration of up to 20 mg/m3 across varying temperatures revealed an escalating demand for D-Flow with rising temperatures. Specific D-Flow ranges, corresponding to each season and temperature condition, were identified as particularly influential on Chl-a concentration. Thus, optimizing Chl-a reduction can be achieved by strategically increasing D-Flow within these specified ranges for each season and temperature variation. This study highlights the importance of maintaining sufficient D-Flow levels to mitigate algal proliferation within river systems featuring weirs.