Adjacent River Research Articles

Riverine CH4 and CO2 emissions respond to associated agricultural land use and seasonality

ABSTRACT Recently, agricultural land use has significantly impacted carbon emissions and water quality in adjacent rivers. This study examined the influence of land-use types and seasonality on carbon emissions from agriculture-impacted rivers in Shanghai. Our results showed that the crop farming land-use-associated river (AR) had CH4 and CO2 fluxes 2.68 and 3.47 times higher, respectively, than those in the aquaculture land-use-AR and 2.86 and 2.81 times higher than in the livestock and poultry breeding land-use-AR. Statistical analyses revealed that total nitrogen, ammonia nitrogen, and humification index were significantly correlated with crop farming land-use-AR carbon emissions. Conversely, no clear correlation was found between chemical factors and carbon fluxes in the aquaculture land-use-AR and livestock and poultry breeding land-use-AR due to the complexity of pollution sources. Seasonality significantly influenced CH4 and CO2 fluxes from agriculture-impacted rivers, with carbon fluxes in summer being 3.5 and 2.5 times higher than in winter, respectively. Crop farming land-use-AR carbon fluxes exhibited the highest variability under seasonal influences. This study emphasizes the need for policies to mitigate agricultural land use impacts on river carbon emissions.

Mio‐Pliocene paleo‐course of Indus River in Upper Sutlej‐Zhada basin: Implication of tectonic uplift on river piracy and drainage reorganization in SW Tibet and NW Himalaya

AbstractWe analysed the elevated low‐relief relict landscapes in the transient Upper Satluj‐Zhada basin and the adjoining region in the tectonically active north‐western (NW) Himalaya–south‐western (SW) Tibetan orogen to understand the evolution of the regional landscape and drainage system under the influence of the Karakoram Fault‐Leo‐Pargil Horst system. This elevated low relief landscape represents the Mio‐Pliocene establishment of a new river network, which testimonies the present Sutlej River, which has been experiencing a transient surface uplift‐incision regime since (~4–1 Ma) with a local base level at the confluence of the Sutlej and Spiti River. The Miocene exhumation of the Ayilari Range and Leo‐Pargil Horst across the Karakoram fault (KF) system led to headward erosion, which abandoned the Paleo‐Sutlej‐Indus drainage system, which in turn caused drainage reversal along Qusum detachment (QD) and produced southward migration of the Paleo‐Sutlej River towards the mountain front. Our results indicate that the Upper Indus River has significantly lower χ‐ranges at higher elevations as compared with the adjacent Upper Sutlej River at lower elevations, which corresponds with a river piracy model that incorporates area gain‐loss feedback. The Upper Sutlej River in the Zhada basin is characterized by a comparable series of coplanar slope‐break knickpoints at ~4000–4500 m elevation, and their adjoining divides are in a state of disequilibrium as a consequence of the very high rapid incision across the Leo Pargil Horst, which drives the regional gradation process. The headward‐eroding Upper Indus River captured the proto‐Sutlej due to a base‐level change of >~1500 m, which significantly impacted the regional growth pattern and tectonics. The Mio‐Pliocene sedimentation pattern of the Upper Sutlej‐Zhada basin in the SW Tibet–NW Himalaya reflects this regional drainage capture, tectonic uplift and paleo‐drainage reorganization. The present finding has wider implications for the Mio‐Pliocene reorganization of drainage systems and the possible linkage of the Upper Indus River with the Paleo‐Sutlej over the Zhada basin.

Ecological Risk Assessment of Heavy Metals from Sewage Sludge, Wastewater, and Adjacent River of Thimphu Sewage Treatment Plant, Bhutan

Ecological Risk Assessment of Heavy Metals from Sewage Sludge, Wastewater, and Adjacent River of Thimphu Sewage Treatment Plant, Bhutan

Identification of high-performing soil groups in grazing lands using a multivariate analysis method

Understanding and quantifying the complex relationships between soil properties and vegetation health is important for sustainable land management and optimising agricultural productivity. This study tested a spatial data-driven framework to identify the soil groups associated with pasture health using publicly available gridded soil attribute layers from Soil and Landscape Grid of Australia (SLGA) over two adjacent southeast Australian river catchments. Principal component analysis (PCA) followed by isocluster unsupervised classification was applied to seventeen SLGA soil attribute layers to identify dominant soil patterns, which showed good spatial agreement with the Enhanced Vegetation Index (EVI) data derived from Landsat-8 imagery. The soil class demonstrating the highest EVI values (HVR class) and the lowest EVI values (LVR class) were determined. A comparison of these classes with soil types defined in the New South Wales Soil Landscape maps confirmed that the HVR class is predominated by agriculturally productive, basalt-derived 'Ant Hill' soils. The cation exchange capacity (CEC) ranging from ∼10 to 20 meq/100 g, clay content ranging from 20 % to 30 %, pHc (pH in calcium chloride solution) between 5 and 6, pHw (pH in water) between 5.5 and 6.5 and SOC between 2.5 % to 4 % were associated with higher EVI values in the HVR soil class within the study area. This study demonstrated an effective framework for identifying key soil attributes that affect agricultural productivity and pinpointing critical locations for grazing land productivity.

Schistura sonarengaensis, a new species of cave-dwelling loach (Teleostei: Nemacheilidae) from Meghalaya, northeast India.

A new species of nemacheilid loach, Schistura sonarengaensis sp. nov., is described from three cave-dwelling populations (Barak-Surma-Meghna drainage) in the South Garo Hills district of Meghalaya, India. The new species possesses prominent eyes but is easily distinguished from all the congeners of the genus Schistura from Barak-Surma-Meghna and adjacent rivers drainages of northeast Indian (except S. syngkai) in having 13-26 vertically elongated to circular mid-lateral black blotches (brownish in life) overlayered on a grayish-black mid-lateral stripe on a dull white or pale-beige (golden brown in life) body. However, it can be easily distinguished from S. syngkai in having a complete (vs. incomplete) lateral line with more 72-89 (vs. 19-42) lateral-line pored scales, greater pre-dorsal length (48.5-53.1 vs. 41.9-44.1 %SL), a wider body at dorsal-fin origin (11.3-16.7 vs. 9.4-10.3 %SL), greater dorsal (18.1-21.1 vs. 15.1-17.0 %SL) and lateral (20.9-24.1 vs. 17.4-18.9 %SL) head length, a wider head (14.5-18.5 vs. 11.6-13.3 %SL), and moderately forked (vs. emarginated) caudal fin. Further, molecular analysis confirms the distinctiveness of S. sonarengaensis sp. nov. from its congeners found in northeast India by significant divergences with uncorrected genetic distance ranging from 3.7% to 17.3% in the mitochondrial cytochrome c oxidase subunit I (COI) gene dataset. The phylogenetic position of the new species with its sister species was evaluated using maximum likelihood and Bayesian analysis. The species delimitation approaches assemble species by automatic partitioning (ASAP) and Poisson tree processes (PTP) utilized for testing species assignments consistently identified our test group as a distinct species from its sister species. Although the new species lacks typical morphological adaptations usually associated with a subterranean life, such as complete absence (or vestigial presence) of eyes and pigmentation, it exhibits a reduction of pigmentation when compared to the epigean congeners.

Influence of precipitation infiltration recharge on hydrological processes of the karst aquifer system and adjacent river

Understanding the hydrological processes of the karst aquifer system (KAS) and adjacent river can further accurately evaluate karst water storage. However, the mechanism of the KAS and adjacent river hydrological processes under precipitation infiltration recharge conditions, the micro-flow behavior of groundwater in the KAS, and changes in media saturation remain unclear. This study coupled the KAS and adjacent river through the Volume of Fluid (VOF), simulated the flow behavior of groundwater in different medium of the KAS and coupled the free flow process of the adjacent river by using the multiphase Darcy-Brinkman-Stokes (DBS) equation, applied the van Genuchten-Mualem and van Genuchten-modified Mualem equations to characterize the seepage processes in soil. The results indicate that the saturation of different porous media controlled by recharge intensity directly influences the flow behavior and flow paths of the porous media. The main groundwater flow path under low precipitation intensity (b=3) is primarily the lower porous medium, while under moderate precipitation intensity (3<b≤8), the main flow path of groundwater is the karst conduit. During heavy precipitation (8<b≤12), due to the limited capacity of karst conduit, they cannot bear the large amount of groundwater supplied from upper porous medium. The peak conduit saturation in laminar flow is 0.3 lower than that in turbulent flows. Under laminar flow conditions, the conduit drainage leads to a rapid decrease in saturation, making it easier for porous media to recharge to the conduit and discharge towards the adjacent river. The turbulent state conduit maintains a high saturation recession, but the discharge is consistently lower than laminar flow. The variation process line of average flow velocity and interfacial flow velocity are obtained using the DBS method and N-S simulation method respectively. There is a certain discrepancy between the simulation results of the two methods since the N-S simulation scheme dose not consider the water retention characteristics of the porous medium.

Decoding the resistome, virulome and mobilome of clinical versus aquatic Acinetobacter baumannii in southern Romania

Acinetobacter baumannii, a notorious opportunistic pathogen, presents a formidable challenge in both clinical and environmental fields due to its resilience and ability to acquire resistance. This study undertook a comprehensive analysis of 183 A. baumannii isolates collected between 2019 and 2022 from intra-hospital infections (IHI), hospital sewages (Hs), wastewater treatment plants (WWTP), and adjacent river waters from two Southern cities, focusing on their resistome, virulome, and mobilome through isolation on chromogenic media, identification by MALDI-TOF-MS and antibiotic susceptibility testing by disk diffusion) followed by genotypic characterization [Whole Genome Sequencing (WGS), 3rd generation sequencing through the MinION (ONT) platform, pangenome description, and respectively horizontal gene transfer through conjugation assays]. Our findings reveal significant genomic plasticity and the prevalence of high-risk international clones, underlining the potential of these isolates to act as reservoirs for antibiotic resistance genes (ARGs) that could be dynamically exchanged between clinical and environmental settings through mobile genetic elements (MGEs) such as the pMAL1 plasmids and the critical role of WWTPs in the persistence and spread of A. baumannii. Moreover, our study presents the first report of the co-occurrence of blaOXA-23 and blaOXA-72 in A. baumannii ST2 clone. Thus, our research underscores the necessity for integrated surveillance and targeted interventions across healthcare and environmental sectors to mitigate the risk posed by this adaptable pathogen.

A combined qualitative–quantitative method for adaptive configuration of urban flood mitigation measure

Inappropriately selecting flood mitigation measures can lead to ineffective governance and wastage of social resources. To address this issue, this research proposes a framework for adaptive configuration of urban flood mitigation measure. This framework aims to achieve a two-sided matching between the disaster reduction capacity of measures and the specific demands of the construction site. The framework was employed to the urban flood mitigation strategy in Longkungou drainage system, an optimal allocation scheme for addressing urban flood disasters under the design rainfall with 50-year return period was determined. The results revealed that green mitigation measures are primarily concentrated in the drainage system within the upstream catchment. Stormwater pumping stations are mainly situated at the drainage outlets and adjacent river channels in the study area. By reducing the water level in the river channel, these stations effectively prevent and manage flood volume resulting from river overflow. As a result of the flood mitigation strategy, the flood volume in the Longkungou drainage system was reduced by 591,186 m3, representing a peak total flood volume reduction rate of 42.44%. The severity of flood disasters in each sub-catchment has significantly diminished, indicating that the flood mitigation strategy has successfully achieved the desired improvement.

Environmental impact of the vibration generated by the underwater shaking table of the National Facility for Earthquake Engineering Simulation (NFEES)

Earthquake simulation shaking tables serve as the valuable tools for investigating the seismic performance of structures, yet they can generate excessive vibrations in surrounding environments during operation. The National Facility for Earthquake Engineering Simulation (NFEES) in China, which is currently in the commissioning phase, will be the world's largest earthquake simulation research facility. Its experimental center consists of a 16 m × 16 m shaking table and two 6 m × 6 m underwater shaking tables (one movable). This study aims to investigate the environmental impact of the vibration generated by the fixed underwater shaking table. Initially, the vibrations of the surrounding ground, shaking table foundations, and adjacent simulation center are tested using the sinusoidal full-load and full-acceleration excitations generated by the shaking table. Upon analyzing the test results, it is observed that the peak ground acceleration (PGA) in the short side direction of foundation attenuates rapidly for high-frequency loading, with a maximum acceleration attenuation up to 55.95 % at distances of 0 m–20 m. The maximum acceleration of the foundation occurs at the edge of the shaking table and significant differences in acceleration are observed at various points across the foundation. The VLZmax of the simulation center is 66.85 dB, which is lower than the limit requirements of the Chinese standard GB55016. Subsequently, an overall finite element model of the surrounding soil-shaking table foundations-adjacent simulation center is established. Following the validation of the numerical model, the vibration isolation efficiency of the adjacent river course and the foundation isolation joint that separates the large shaking table foundation from the underwater shaking table foundation are assessed. Compared to the test results, numerical results show relatively minor discrepancies in the peak acceleration of the ground and the foundation, with maximum errors of 24.59 % and 21.11 %, respectively. The river course and the foundation isolation joint demonstrate better vibration isolation performance for short-wavelength waves, with a maximum vibration isolation efficiency reaching 64.71 % and 63.56 %, respectively.

Flood Propagation Characteristics in a Plain Lake: The Role of Multiple River Interactions

Plain lakes play a crucial role in the hydrological cycle of a watershed, but their interactions with adjacent rivers and downstream water bodies can create complex river–lake relationships, often leading to frequent flooding disasters. Taking Poyang Lake as an example, this paper delves into its interaction with the Yangtze River, revealing the spatiotemporal patterns of flood propagation within the lake and its impact on surrounding flood control measures. The aim is to provide insights for flood management in similar environments worldwide. This study employs a comprehensive approach combining hydrological statistical analysis and two-dimensional hydrodynamic modeling, based on extensive hydrological, topographic, and socio-economic data. The results indicate that the annual maximum outflow from Poyang Lake is primarily controlled by floods within the watershed, while the highest annual lake water level is predominantly influenced by floods from the Yangtze River. The peak discharge typically reaches the lake outlet within 48 h, with the peak water level taking slightly longer at 54 h. However, water storage in the lake can shorten the time that it takes for the peak discharge to arrive. When converging with floods from the Yangtze River, the peak water level may be delayed by up to 10 days, due to the top-supporting interaction. Furthermore, floods from the “Five Rivers” propagate differently within the lake, affecting various lake regions to differing degrees. Notably, floods from the Fu River cause the most significant rise in the lake’s water level under the same flow rate. The top-supporting effect from the Yangtze River also significantly impacts the water surface slope of Poyang Lake. When the Yangtze River flood discharge significantly exceeds that of the “Five Rivers” (i.e., when the top-supporting intensity value, f, exceeds four), the lake surface becomes as flat as a reservoir. During major floods in the watershed, the water level difference in the lake can increase dramatically, potentially creating a “dynamic storage capacity” of up to 840 million cubic meters.

Effects of past riverine connectivity on the population structure and species distribution of ‘Geophagus’ brasiliensis (Cichlidae) complex in a Neotropical hotspot

Abstract Once fishes and rivers are intrinsically connected, historical events such as river captures and the reconfiguration of palaeodrainages affect population structure and species distribution. However, direct evidence of these events remains limited. We aimed to directly infer putative connections between adjacent river basins to understand genetic and geographical patterns in populations and species of the ‘Geophagus’ brasiliensis complex. For that, we analysed 174 sequences of the mitochondrial gene cytochrome c oxidase subunit I (COI) from five species along 35 sites within and near a coastal basin in northeastern Brazil. Based on haplotype network, palaeodrainage reconstruction, geological inferences of river captures and analyses of molecular variance (AMOVAs), we tested how the genetic structure could be associated with variable patterns of habitat connectivity through time. In general, high levels of genetic variation were identified, including shared haplotypes among drainages for most species. AMOVA suggested that drainage rearrangements between adjacent basins were the main drivers of genetic diversification in the ‘G.’ brasiliensis complex. Our study refuted dispersal routes via the continental shelf, whereas eight putative river captures suggested historical connections that enabled gene flow among drainages until recent interruption. These results provide novel insights on the role of riverscape evolution on the biogeography of neotropical ichthyofauna.

Flying by the river side: Survey of bat distributions and environmental contexts along a 1000‐mile river corridor, Green and Colorado Rivers, USA

AbstractAimEmerging research shows how bioindicators, specifically bats, can serve as a means for monitoring conservation and management of riparian corridors for multiple taxonomic groups. To track changes in the composition or abundance of bioindicator species, researchers must attain a baseline in species presence and relative activity. We examined the spatial and temporal patterns of bat community composition and activity along a 1000‐mile river corridor to determine species diversity trends by latitude and habitat.LocationColorado River Basin.MethodsHere we describe the results from an acoustic bat survey conducted opportunistically on the 2019 Sesquicentennial Colorado River Exploring Expedition. This broad, 1000‐mile survey provides a baseline for species distributions over a large geographic range.ResultsIn total, we collected 63 nights of acoustic data over 70 days and recorded over 59,000 files equating to 45,363 caLL files (≥2 pulses). 18,490 (41% of caLL files) were identified as species (n = 19 bat species). We applied non‐metric multidimensional scaling to characterize spatiotemporal patterns of activity between species, as well as compared bat activity among river features and local environmental conditions (i.e., temperature and time since sunset) using an information theoretic approach.ConclusionSpecies composition varied by physiographic region and adjacent river habitat, thus providing a quantifiable measure of determining habitat quality along this major river system and providing baseline information for using bats as bioindicators of habitat quality.

Correlated environmental DNA and electrofished estimates of relative biomass for golden perch, Macquaria ambigua

In response to the need to augment electrofishing surveys of golden perch, Macquaria ambigua (an important endemic freshwater fish in southeastern Australia), with other non-lethal survey methods, the utility of environmental DNA (eDNA) as an index of relative fish abundance/biomass was investigated. From three adjacent rivers, five sites in each were sampled for eDNA immediately before electrofishing during sequential years. Up to six individuals or 10 kg of electrofished golden perch (200–548 mm total length) were caught or observed site−1. Analyses of concurrent eDNA concentrations revealed no significant relationship with the relative abundance of golden perch, but there was with relative biomass—manifesting as increasing eDNA concentrations between 1.1 and approximately 5.5 kg biomass site−1, after which concentrations stabilized at greater biomasses. Future research warrants assessing the viability of sampling eDNA for spatio-temporally monitoring rivers where low biomasses of golden perch (1–5 kg site−1) are likely to occur.

Description of a new species of Aegla (Decapoda, Anomura) from the Paran 3 hydrographic basin, Brazil.

Freshwater crustaceans of the genus Aegla are endemic to southern South America, and present greater richness in the river basins of the state of Rio Grande do Sul, Brazil. However, recent studies have shown the enormous potential for discovering new species of Aegla in the state of Paran. In the last six year the number of species recorded has almost doubled, increasing from 9 to 16. In the present work, we expand the current knowledge about the diversity of Aegla in a set of poorly explored drainage basins in the western region of the state and describe a new species, Aegla urussanga n. sp., based on morphological and molecular evidence. A combination of morphological characters supports the new species: orbital spine absent, non-elevated epigastric prominences, robust protogastric lobes with scales, anterior dorsal margin of epimeron 2 armed and with pronounced concavity, sub-rectangular palmar crest of chelipeds, internal margin of the ventral face of the ischium of the cheliped with a proximal stout spine, a distal stout spine, and up to three tubercles with spiniform scales. The molecular data, based on partial COI sequences, also support the distinction of the new species from others that occur in adjacent river basins. The species with the smallest genetic distance from A. urussanga n. sp. is Aegla castro Schmitt, 1942 which occurs in the Iguau River basin. The new species occurs in distinct streams, probably interconnected in the past and currently isolated by the Itaipu reservoir and is the second species of Aegla described from the complex of drainage basins called Paran 3 basin.

Exploring The Synergies between Flood Risk and Urban Needs - Floodplain Development In Aceh River.

A Floodplain is an area next to a riverbed that is more or less frequently covered with water in times of high-water discharges from adjacent rivers. It usually has a high environmental value because of its heterogeneous habitats for wildlife species. However, the condition of rivers in each country could be unique and different, because of their history and location thus creating a different nuance. The object study of this research is a constructed floodway and flood plain in Krueng Aceh (Aceh River) owned and managed by the local government. Since the last big flood in 2000, this wide flat land remained dry in several areas and was used by some villagers to make a living. In 2020 it had cleared from several illegal land uses, resulted a grassland floodplain with low-intensity use which in theory is in a good direction. Meanwhile, in the perspective of urban needs, river development could also bring economic, social, and environmental benefits to community. The objective of this study is to investigate the concept of ecosystem services and human-landscape connectivity. The method used in this research is semi-qualitative research that combines theories and observation. In the context of ecosystem services identification through activities monitoring, it shows that cultural and provision services is the highest while regulating and supporting services still need further research. As for human-landscape connectivity, there are more ‘rooms’/spaces to develop align with the availability of cultural services.

Nonlinear multi independent variables in quantifying river bank erosion using Neural Network AutoRegressive eXogenous (NNARX) model

This study proposed a novel application of Neural Network AutoRegressive eXogenous (NNARX) model in predicting nonlinear behaviour of riverbank erosion rates which is difficult to be achieved with good accuracy using conventional approaches. This model can estimate complex river bank erosion rates with flow variations. The NNARX model analysed to a set of primary data, 60% (203 data for training) and 40% (135 data for testing), which were collected from Sg. Bernam, Malaysia. A set of nondimensional parameters, known as functional relationship, used as an input to the NNARX model has been established using the method of repeating variables. The One-Step-Ahead time series prediction plots are used to assess the accuracy of all developed models. Model no. 6 (5 independent variables with 10 hidden layers) gives good predictive performance, supported by the graphical analysis with discrepancy ratio of 94% and 90% for training and testing datasets. This finding is consistent with model accuracy result, where Model no. 6 achieved R2 of 0.932 and 0.788 for training and testing datasets, respectively. Result shows that bank erosion is maximized when the near-bank velocity between 0.2 and 0.5 m/s, and the riverbank erosion is between 1.5 and 1.8 m/year. On the other hand, higher velocities ranging from 0.8 to 1.3 m/s induces erosion at a rate between 0.1 and 0.4 m/year. Sensitivity analysis shows that the highest accuracy of 91% is given by the ratio of shear velocity to near-bank velocity followed by boundary shear stress to near-bank velocity ratio (88.5%) and critical shear stress to near-bank velocity ratio (88.2%). It is concluded that the developed model has accurately predicted non-linear behaviour of riverbank erosion rates with flow variations. The study's findings provide valuable insights in advanced simulations and predictions of channel migration, encompassing both lateral and vertical movements, the repercussions on the adjacent river corridor, assessing the extent of land degradation and in formulating plans for effective riverbank protection and management measures.

Identification of potential microbial risk factors associated with fecal indicator exceedances at recreational beaches

BackgroundFecal bacterial densities are proxy indicators of beach water quality, and beach posting decisions are made based on Beach Action Value (BAV) exceedances for a beach. However, these traditional beach monitoring methods do not reflect the full extent of microbial water quality changes associated with BAV exceedances at recreational beaches (including harmful cyanobacteria). This proof of concept study evaluates the potential of metagenomics for comprehensively assessing bacterial community changes associated with BAV exceedances compared to non-exceedances for two urban beaches and their adjacent river water sources.ResultsCompared to non-exceedance samples, BAV exceedance samples exhibited higher alpha diversity (diversity within the sample) that could be further differentiated into separate clusters (Beta-diversity). For Beach A, Cyanobacterial sequences (resolved as Microcystis and Pseudanabaena at genus level) were significantly more abundant in BAV non-exceedance samples. qPCR validation supported the Cyanobacterial abundance results from metagenomic analysis and also identified saxitoxin genes in 50% of the non-exceedance samples. Microcystis sp and saxitoxin gene sequences were more abundant on non-exceedance beach days (when fecal indicator data indicated the beach should be open for water recreational purposes). For BAV exceedance days, Fibrobacteres, Pseudomonas, Acinetobacter, and Clostridium sequences were significantly more abundant (and positively correlated with fecal indicator densities) for Beach A. For Beach B, Spirochaetes (resolved as Leptospira on genus level) Burkholderia and Vibrio sequences were significantly more abundant in BAV exceedance samples. Similar bacterial diversity and abundance trends were observed for river water sources compared to their associated beaches. Antibiotic Resistance Genes (ARGs) were also consistently detected at both beaches. However, we did not observe a significant difference or correlation in ARGs abundance between BAV exceedance and non-exceedance samples.ConclusionThis study provides a more comprehensive analysis of bacterial community changes associated with BAV exceedances for recreational freshwater beaches. While there were increases in bacterial diversity and some taxa of potential human health concern associated with increased fecal indicator densities and BAV exceedances (e.g. Pseudomonas), metagenomics analyses also identified other taxa of potential human health concern (e.g. Microcystis) associated with lower fecal indicator densities and BAV non-exceedances days. This study can help develop more targeted beach monitoring strategies and beach-specific risk management approaches.

The occurrence of Antibiotic-Resistant Escherichia coli in the Upper Citarum River and surrounding wastewater effluents

Wastewater has the potential to introduce antibiotic-resistant bacterial contamination into the adjacent river, posing environmental health risks to surrounding community. However, there is limited data on the bacterial resistance pattern in aquatic environments of developing countries. This study aimed to explore the hazard level of Antibiotic-Resistant Escherichia coli from effluents and river water based on the enumeration and resistance pattern towards thirteen antibiotics of varying potency. Escherichia coli enumeration was performed on samples collected from nine segments of the Upper Citarum River, and the effluents of two hospitals, six farms, five pharmaceutical companies, and two municipal treatment plants. Agar dilution on Chromocult® Coliform Agar ES was utilized to profile antibiotic susceptibility. The results show that Escherichia coli from farm wastewater has the highest average number (43.347 CFU/100mL) and the widest range of antibiotic resistance (up to eight type), followed by Escherichia coli from domestic, hospital and pharmaceutical effluent. Meropenem-resistant Escherichia coli is already detected in all effluent sources. Escherichia coli in the river water was resistant to thirteen types of antibiotics, and the load was increasing downstream. It is important to take immediate and effective measures to address bacterial resistance occurrence in the aquatic environments.

ИСТОРИЯ АРХЕОЛОГИЧЕСКОГО ИЗУЧЕНИЯ ГОРОДИЩА ГУНДЕЛЕН-2

The article is about the history of the archaeological examination of the Gundelen-2 site. The monument is situated on a high rocky ledge on the right bank of the Gundelen river, a tributary of the Baksan river, between the settlements of Zayukovo and Kendelen. The fortified hamlet is situ-ated in an important and strategically beneficial location, from which the entire adjacent river val-ley and the entrance to the Baksan canyon are easily seen. The town is located on a rocky ledge that runs north-south and is made of sandstone rocks, with steep cliffs on three sides: the southern, eastern, and western. On the northern side, where there is no natural protection, the settlement is protected by a number of fortifications - two ditches and a pair of ramparts. The size of the set-tlement in the widest place reaches 70 meters, and in length 220 m. The Gundelen-2 settlement is part of an archaeological monument complex that includes the Zayukovo-3 burial site and the Gundelen-2 rock catacomb burial ground (Fig. 1). The complex has been known since the 30s. XX century and has been visited numerous times by researchers over the subsequent decades, but serious study of the monuments did not begin until the 10s. XXI cen-tury.

Influence of inter-river water diversion on estuary pollution control: A case study of Liaodong Bay

Long-term mass transport processes in offshore seas are controlled by seasonal residual currents. The Euler residual mass transport velocity field was calculated form seasonal residual current patterns in shallow sea area, comparing with polluted water changes in typical years. The following conclusions were made: closed local large loops of the Euler residual mass transport led to polluted waters in the northeast Liaodong Bay, and the bay's optimal physical self-purification occurred in winter (Euler residual mass transport diffuses polluted water masses) and spring (overall self-purification capacity of the bay plays a role after winter). The central waters were clean while pollutants were discharged into near-shore waters, leading to perennial pollution in some near-shore waters. Pollution in Liaodong Bay could be alleviated or eliminated via diversion of water from the Daliaohe River (flowing into the northeast corner of Liaodong Bay and carrying > 65% of the total amount of pollutants discharged into the top of the bay) into the Liaohe River and Daling River. The percentage of inorganic nitrogen carried by 10% of the flux of the Daliaohe River was 5.70% of that discharged into Liaodong Bay. If 10% of the flux of the Daliaohe River was discharged into the Daling River, the annual total environmental carrying capacity of inorganic nitrogen increased 4.48%. Many bays in the world have adjacent river flows, such as Gulf of Mexico, Gulf of Guinea, and Bay of Bengal. Based on the Euler residual mass transport field, the water transfer between adjacent rivers could make better use of the Euler residual mass transport capacity to mitigate the water pollution of the estuaries.