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Microplastic contamination of lakes and rivers is an emerging environmental issue. Sources, environmental fate, in-situ behaviour, concentration and harmful impacts of microplastics on aquatic life are the focus of this review paper. Present review summarises the current state of information about microplastics in riverine ecosystems around the world. The tiny plastic particles can serve as substrate as well as transporters of a variety of toxicants, including recalcitrant chemical compounds from miscellaneous sources having potential to seriously harm people's health. Further, intake and entanglement of microplastics can inflict a number of adverse bio-physico-chemical impacts on people and other living creatures. Secondary microplastics are produced by the disintegration of bigger size primary plastic particles and ultimately end up in the terrestrial and aquatic habitats. Comprehensive information on microplastic pollution in fresh water ecosystems is still limited on a single platform. This review critically addresses the microplastic pollution in rivers, sources, and its impact around the world. Further, possible replacements for plastics like modified starch, cellulose, esters of cellulose, polylactic acid etc. derived from biomass and microorganisms are also examined. [ABSTRACT FROM AUTHOR]

Climate change and the reliance on carbon-intensive fuels have made electromobility necessary to reduce greenhouse gas (GHG) emissions in transport. This study analyses the potential environmental impact of a shallow-draught vessel operating within a section of Colombia’s Atrato River basin by estimating CO₂-equivalent emissions across various technological alternatives (conventional, hybrid, and electric) using a life cycle analysis. Data on engine performance, fuel type, and operating conditions were gathered. A battery propulsion system was modelled using both ‘conventional’ and renewable energy sources. The analysis focused on four impact categories: global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), and photochemical ozone creation potential (POCP). Results indicated significant reductions with renewable energy: 92.6% in GWP, 94.2% in AP, 82.4% in EP, and 93.7% in POCP. The selection of energy sources for electricity generation is crucial in assessing the viability of battery technology for sustainable shipping. [ABSTRACT FROM AUTHOR]

Recently, the impact of climate change has led to an increase in the scale and frequency of extreme rainfall and flash floods. Due to this, the occurrence of floods and various river disasters has increased, necessitating the acquisition of technologies to prevent river disasters. Owing to the nature of rivers, areas with poor accessibility exist, and obtaining information over a wide area can be time-consuming. Artificial intelligence technology, which has the potential to overcome these limits, has not been broadly adopted for river detection. Therefore, the current study conducted a performance analysis of artificial intelligence for automatic river path setting via the YOLOv8 model, which is widely applied in various fields. Through the augmentation feature in the Roboflow platform, many river images were employed to train and analyze the river spatial information of each applied image. The overall results revealed that the models with augmentation performed better than the basic models without augmentation. In particular, the flip and crop and shear model showed the highest performance with a score of 0.058. When applied to rivers, the Wosucheon stream showed the highest average confidence across all models, with a value of 0.842. Additionally, the max confidence for each river was extracted, and it was found that models including crop exhibited higher reliability. The results show that the augmentation models better generalize new data and can improve performance in real-world environments. Additionally, the RivDet artificial intelligence model for automatic river path configuration developed in the current study is expected to solve various problems, such as automatic flow rate estimation for river disaster prevention, setting early flood warnings, and calculating the range of flood inundation damage. [ABSTRACT FROM AUTHOR]

This article introduces a methodology utilizing the Analytical Hierarchy Process (AHP) integrated with a Geographic Information System (GIS) to classify sub-basins within a large river basin in terms of pollution levels.The research uses data from the Haraz River basin, located in northern Iran near the Caspian Sea. The river basin under investigation comprises seven sub-basins. The primary pollution sources in this region include domestic wastewater from urban areas, effluents from fish farms, discharge from sand and gravel mines, sewage from restaurants and tourism centers, as well as land use (agriculture, forests, and rangelands). In addition to these pollution-related factors, other criteria such as basin area, river length, road network length, and slope were also considered.Using scores assigned by experts and leveraging the Expert Choice software, all sub-basins, and factors contributing to river pollution were identified. According to the findings, urban domestic wastewater was the most significant contributor to pollution in the study Basin, accounting for 42.2% of the total pollution. The sub-basins were classified according to their final weighted scores, identifying those with the highest and lowest pollution levels.The studied approach offers substantial advantages in terms of time, cost, and resource efficiency. [ABSTRACT FROM AUTHOR]

The condition of the aquatic environment, particularly in protected areas of high ecological value such as the Narew River, requires detailed monitoring to identify and minimise the impact of anthropogenic factors on the ecosystem. This study focused on the content of heavy metals in bottom sediments and macrophytes of the Narew River, emphasising the influence of human activities and natural factors on this ecologically valuable ecosystem. Pb, Cr, Zn, Cd, Fe, and Mn concentrations were analysed in sediment samples, and ten macrophyte species were collected at 11 sampling points along the river. A geochemical index (Igeo) and multivariate statistical analyses were employed to identify sources of contamination. The digested samples (sediments and plants) were analysed for Pb, Cr, Cu, Zn, Ni, Cd, Fe, and Mn using flame atomic absorption spectrometry (AAS) on an ICE 3500 Thermo Scientific spectrometer, with a measurement error below 5%, validated against certified reference materials. The study results indicated that most metals, including Ni, Cr, Co, Fe, and Mn, predominantly originate from natural geological processes. In contrast, Zn, Cd, Cu, and Pb were identified as being enriched due to anthropogenic activities. An analysis of macrophytes revealed varied patterns of metal accumulation, which correspond to the bioavailability of metals and their environmental concentrations. Comprehensive statistical analyses provided insights into the predominant sources of metal contamination, closely associated with industrial emissions, agricultural runoff, and transportation activities. The integration of sediment and macrophyte monitoring allowed for a thorough evaluation of the Narew River ecosystem, facilitating the identification of key pollution sources. These findings highlight the critical need for measures to mitigate anthropogenic contributions of heavy metals—particularly from industrial, agricultural, and transportation sectors—to safeguard the Narew River's unique ecological and natural heritage. [ABSTRACT FROM AUTHOR]

Marine tourism is authorized in Jakarta Bay's Angke Kapuk mangrove forest. Maritime vessel activities, maintenance, and land reclamation can pollute nearby aquatic environments and sedimentary deposits. This study examines lead (Pb), a heavy metal, in water and sediment samples to measure contamination. Lead pollution in aquatic habitats can harm aquatic organisms and humans through bioaccumulation in the food chain. The sampling was done twice in August 2023, seven days apart. This technique was done at three stations with different activities. Microwave Plasma-Atomic Emission Spectroscopy (MP-AES) was used to measure lead amounts in the samples. The water sample analysis showed 0.0022-0.0092 mg/L, matching Indonesian Government Regulation No. 22 of 2021 standards. Conversely, sediment samples showed 0.067-0.200 mg/kg, which is below the quality criteria set by ANZECC&ARMCANZ in 2000 for Australia and New Zealand and CCME in 2001 for Canada. Despite low pollution according to recognized criteria, heavy metals in ecotourism zones require government and public attention. Additional information, in-depth research on water contamination, and heightened awareness of the impacts of heavy metals may be necessary. [ABSTRACT FROM AUTHOR]

A survey was conducted in 12 areas viz., Naini, Arail, Shringverpur, Jhusi, Baluva Ghat, Daraganj, Jamunipur, Phaphamau, Mankameshwar, Chhatnag, Mecferson Lake and Sangam Ghat near the river Ganga and Yamuna at Prayagraj, U.P. in the year 2024. Sixty soil samples were collected during the month of January, March, May, July and September, respectively. Six genera of plant-parasitic nematodes viz., Meloidogyne sp. Pratylenchus sp., Rotylenchus sp, Tylenchulus sp., Helicotylenchus sp. and Heterodera sp. were found in 12 above mentioned areas. Meloidogyne sp. Heterodera sp., Rotylenchus sp., and Pratylenchus sp. were predominant followed by Tylenchulus sp. and Helicotylenchus sp. Maximum number of Meloidogyne sp., Heterodera sp., Rotylenchus and Pratylenchus sp. were found in the sample collected during the month of January followed by September, March, July and May, respectively, in the area Naini, Arail, Shringverpur, Jhusi followed by Balua Ghat, Daraganj, Jamunipur, Phaphamau, Mankameshwar, Chhatnag, Macpherson Lake area and Sangam Ghat area, respectively. Minimum number of Tylenchulus and Helicotylenchus sp. were found in Naini, Arail and Jhusi areas in the samples collected during January and September months. [ABSTRACT FROM AUTHOR]

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The high levels of nitrate (NO3−) in the surface water have contributed to eutrophication and other eco-environmental damages worldwide. Although the excessive NO3− concentrations in rivers were often attributed to anthropogenic activities, some undisturbed or slightly disturbed rivers also had high NO3− levels. This study utilized multi-pronged approaches (i.e., river natural abundance isotopes, 15N-labeling techniques, and qPCR) to provide a comprehensive explanation of the reason for the high NO3− levels in a river draining forest-dominated terrene. The river natural abundance isotopes (δ15N/δ18O-NO3−) indicated that the soil source (i.e., soil organic nitrogen-SON and chemical fertilizer-CF) were the primary contributors to the NO3−, and the NO3− removal was probably prevalent in the basin scale. The 15N-labeling techniques quantitatively showed that denitrification and anammox were stronger than nitrification in the soils and sediments. Structural equation models suggested that nitrification in the soils was regulated by NH4+-N contents, which, in turn, were closely related to fertilization in spring. Denitrification and anammox were largely controlled by elevation and functional gene abundances (i.e., nirK and hzsB, respectively). The hydrological isotopes (i.e., δD/δ18O-H2O) indicated that the transport of NO3− from soil to the river was related to the intensity of runoff leaching to the soil, In contrast, the riverine NH4+ was largely from point sources; thus, increasing runoff led to a dilution effect. This study clearly showed that soil biogeochemistry and hydrological condition of a river basin jointly shaped the high NO3− levels in the almost undisturbed river. [ABSTRACT FROM AUTHOR]

The state of Michigan is 253,800 km2 in size with abundant freshwater habitats, including lakes, streams, ponds, and rivers that are ideal for freshwater red algae from the order Batrachospermales. In addition, there are numerous herbarium records, but approximately 60% are more than 20 years old. Recent collections have been from a small geographic area and only a handful of specimens have associated DNA sequences that are often needed for accurate species identification. We surveyed broadly in the Upper and Lower Peninsula, revisiting previously sampled sites and exploring new localities. Freshwater red algae were collected from 19 sites that varied from small streams, rivers, and lake inlet/outlets with a corresponding range in water temperature, pH, and conductivity. Four genera were collected, Batrachospermum, Paludicola, Sheathia, and Virescentia, with species identifications verified with rbcL gene sequencing. The genus Sheathia was the most abundant (15 sites) and represented by two species, S. grandis and S. involuta. At seven sites, we found Batrachospermum gelatinosum, whereas Paludicola communis and Virescentia viride-americana were each collected once. Although these four genera have been previously known from the state, this study provided the first rbcL sequence for B. gelatinosum and P. communis in Michigan. At one location, we confirmed the presence of Virescentia viride-americana 30 years after it had first been collected, and likewise, we confirmed B. gelatinosum at another site 27 years later. Sheathia grandis was recently described from only two locations in nearby states. This study was the first report in Michigan and added considerably to the number of known locations. This research has yielded new records, species identification with DNA sequence, and expanded habitat information. [ABSTRACT FROM AUTHOR]

Globally scarce and ecologically valuable, the lowland chalk streams of southern and eastern England experience extensive eutrophication pressures arising from intensive agriculture. Mitigation measures are required to restore natural chalk stream functioning and the reintroduction of the Eurasian beaver (Castor fiber) could provide a solution. Here, we investigated the impact upon chalk stream hydrochemistry of the reintroduction of beavers to a 6-ha enclosure on the headwaters of the River Glaven, Norfolk. Over a two-year period (March 2022 – May 2024), 190 river water samples were collected across control and impact sites displaying minor-to-major hydrological disturbance from beaver activity, with samples analysed for nitrate (NO3), phosphate (PO4), and dissolved organic carbon (DOC). Results revealed significant reductions in nutrient concentrations downstream of the beaver enclosure (NO3 = -43%; PO4 = -51%), as well as significantly lower concentrations relative to the agricultural control site (NO3 = -64%; PO4 = -86%). Conversely, DOC concentrations were significantly higher downstream of the enclosure (+ 94%) and compared to the control (+ 272%). Greater reductions in nitrate and phosphate during the summer (NO3 = -47%; PO4 = -61%) compared to winter (NO3 = -37%; PO4 = -38%) indicated biological assimilation within the beaver wetland as a likely causal mechanism, whilst lower dissolved oxygen concentrations within the beaver ponds indicated a role for denitrification in nitrate removal. Overall, these results demonstrate that beaver wetlands can significantly mitigate eutrophication risk in agriculturally impacted chalk streams and provides further evidence in support of their wider reintroduction to English catchments. [ABSTRACT FROM AUTHOR]

Dispersal behaviour of fish expanding their range is an important component of invasion success and can evolve along dispersal pathways. Understanding the movement biology of invasive species during the spread phase of a new invasion is important for developing targeted management strategies. This study determined the extent and movement patterns of two tilapia species, Oreochromis mossambicus and Pelmatolapia mariae, in the Mitchell River catchment, northern Australia, during the spread phase of the invasion. Tilapia were only found in three locations within one sub-catchment of the Mitchell River. Strontium isotopes of tilapia otoliths revealed different movement patterns among these three locations, with active dispersal to one of the locations from both other locations. Movements made by P. mariae mostly occurred within the first two years of life. These movement patterns demonstrate active habitat seeking behaviour, mostly by juveniles, that lead to the successful establishment of tilapia at new locations within a catchment following introduction. The movement patterns revealed in this study were used to recommend priority management actions to limit the risk of tilapia spreading to vulnerable floodplain habitats and other river systems in the Gulf of Carpentaria. These include monitoring within the sub-catchment containing established tilapia and control measures applied to the established local populations to limit population growth, limiting the risk of downstream spread by reducing dispersal probability. [ABSTRACT FROM AUTHOR]