Zone Of River Research Articles

Effect of intermittent water flow on biodegradation of organic micropollutants in the hyporheic zone.

Water scarcity in the Mediterranean area has increased the number of intermittent rivers. Recently, hyporheic zones (HZ) of intermittent rivers have gained attention since a substantial part of the stream's natural purification capacity is located within these zones. Thus, understanding the flow dynamics in HZs is crucial for gaining insights into the degradation of organic micropollutants. A lab-scale study using column experiments was conducted in an attempt to elucidate the environmental processes accounting for the biodegradation capacity of the HZ under flow intermittency. A mixture of six compounds including pesticides (chloranthraniliprole, fluopyram and trifloxystrobin) and pharmaceuticals (venlafaxine, amisulpride and paroxetine) spiked at 1μg/L level was used for degradation kinetic studies and at 1mg/L for transformation products identification using suspect/non-target liquid chromatography high-resolution mass spectrometry approaches. The experiments lasted 60 days, divided into two 14-day phases: one before and one after a 5-week desiccation period. Bacterial community was charaterized by high-throughput DNA sequencing. The results suggested that intermittent flows stimulated the biodegradation of three compounds namely fluopyram, trifloxystrobin and venlafaxine, showing a large range of biodegradation profiles in batch water/sediment testing system according to OECD 308 tests. Biodegradation rate enhancement was ascribed to the occurrence of additional transformation routes after the desiccation period of river sediment, with the formation of new transformation products reported for the first time in the present work. 16S rDNA sequencing revealed that the desiccation period favored the growth of nitrifying and denitrifying bacteria which could partially explain the emergence of the new transformation pathways and most specifically those leading to N-oxide derivatives. Identification of transformation products also revealed that reductive transformation routes were relevant for this study, being dehydrogenation, dehalogenation, ether bond cleavage and sulfone reduction into sulphide important reactions. These results suggest that the intermittent flow conditions can influence the HZ biodegradation capacity.

Оценка воздействия стока некоторых рек Сочинского Причерноморья на прибрежную морскую среду в зонах их плюмов

The paper assesses the impact of water quality of some rivers located within the Black Sea coastal zone in the Sochi area on the ecological security and status of the Black Sea coastal line. The relevance of the study is determined by the lack of a unified methodological approach to establishing parameters for assessing the ecological condition of water bodies within the Black Sea coastal area. The study is the first to consider a unified river-sea system in the context of integrated monitoring of natural water quality. The research is based on biological methods (biotesting, bioindication) to evaluate the state of biological communities and processes in combination with the analysis of geological aspects. This allows a detailed study of the influence of various factors on the marine environment ecological safety. It was revealed that the marine environment has the highest levels of toxicity in the inflow zones of small rivers, which are subject to significant complex impacts from municipal solid waste landfills and industrial enterprises located in their catchment areas. In the marine plumes of rivers classified as medium, which are important for water management, recreation and fisheries in the region, seawater has a lower toxic effect as a result of significant dilution. Thus, small rivers inflows can cause similar negative impacts on the quality of the marine environment and the status of coastal biocenoses as runoff from larger watercourses. The study results can contribute to the development of new approaches for the assessment and monitoring of the environmental security of the coastal marine environment, based on the concept of the ecological system integrity in the context of interdependencies associated with the pollutants and nutrients transfer between qualitatively different environments and associated with them river and cjastal marine hydrobiocenoses.

Temporal and Spatial Distribution Characteristics of Fish Resources in a Typical River–Lake Confluence Ecosystem During the Initial Period of Fishing Ban

This study provides a comprehensive analysis of the spatio-temporal dynamics of fish resources in the confluence waters of Poyang Lake and the Yangtze River, focusing on the initial phase of a 10-year fishing ban implemented in January 2020. Through hydroacoustic surveys conducted during both high-water (September 2020) and low-water (January 2021) periods, we identified significant variations in fish density and individual size across different sections. During the high water level period, fish concentrations were primarily observed in the confluence area between the Yangtze River and Poyang Lake, exhibiting higher densities compared to other regions. Conversely, fish congregated in the deep-water zones of the main river during the low water level period. The fish population was dominated by small to medium-sized individuals, with mean body lengths of 12.47 cm and 12.62 cm during the high and low water level periods, respectively. Notably, 42 and 33 fish species were recorded during the high-water and low-water surveys, respectively, emphasizing the region’s rich biodiversity. Importantly, the study demonstrates that the fishing ban has resulted in substantial increases in both fish density and mean body length, underscoring its effectiveness in fostering fish population recovery. These findings provide critical baseline data to inform scientific conservation and management strategies in this ecologically sensitive river–lake ecosystem.

Key changes across valley floors in mountain areas affected by different levels of human impact: a case study of the Ochotnica river catchment in the Polish Carpathians

The goal of this paper was to present knowledge on changes in the morphodynamic structure of the Ochotnica River (Polish Carpathians) and transformations within its active river zone since the end of the 19th century. The study used a set of archival and contemporary cartographic materials and the results of three-fold field mapping of the morphodynamic structure of the riverbed. Direct and indirect human interference with the natural environment of the catchment and the fluvial system was taken into account in the analysis. Analysis of changes in the morphodynamic structure of the Ochotnica and its active river zone since the end of the 19th century indicated significant changes in the development trend of the riverbed. The contemporary structure of the Ochotnica is more complex than in the 1980s. There has been a fragmentation of the riverbed into sections with different morphodynamic sections. The proportion of erosive sections has increased, which explains the reduced in the width of the active river zone of the Ochotnica. The average width of the active river zone of the river between 1861 and 2022 has changed from 80 m to 18 m. Human impact has been identified as the main reason for the changes in the morphodynamic structure of the riverbed and its active river zone. Currently, only the unregulated sect ion is characterised by free lateral migration of the riverbed and the widest active river zone (∼ 28 m).

The Puzzle of Silesia’s Pre-Roman Iron Age: The Settlement at Graniczna Street in Wrocław

In the autumn of 2014, rescue excavations were carried out at 4A Graniczna Street in Muchobór Wielki, Wrocław. The 2-hectare excavation area yielded remains of a multi-phase settlement, including a stage from the pre-Roman Iron Age. The excavated finds primarily consisted of pottery vessel fragments, alongside a well-preserved middle La Tène Mötschwil-type brooch, daub, and animal bones. Among the identified features were pits, postholes, pit houses, and the remains of a ground-level post building with a well. However, while the structure dates to the Iron Age, its exact chronology remains a subject of debate. The discovery of this late pre-Roman Iron Age settlement in the Ślęza river zone provides further evidence that the area featured a network of settlements dating to the earliest phases of the late pre-Roman period. These settlements bridge the chronological gap between the decline of the Lower Silesian La Tène culture settlement and the earliest discoveries associated with the classical Przeworsk style.

Critically analyzing nature-based solutions: A political ecology framework of planning for the Yamuna River floodplains, Delhi

ABSTRACT “Novel” nature-based solutions, implemented through urban spatial plans and rezoning policies, paint an apolitical picture of the rejuvenation of the floodplains of Delhi. This paper uncovers the socio-ecological injustice rooted in these decisions that lead to the eviction of small-scale farms. This is discussed through the political ecology framework and examined as an approach of bourgeois environmentalism. The spatial policies in the Draft Master Plan for Delhi 2041 are traced through previous master plans, specifically for Zone O (river zone) of the National Capital Territory of Delhi. This allows for the unpacking of a larger urban socio-ecological imaginary being produced. In this paper, we find that, first, the river zone plan erases the marginalized, and, second, it potentially makes the way clear for the ecologically sensitive floodplains to be used for developing recreational activities targeting the elite. Therefore, like previous plans, this plan leads to the marginalization of both the river and the marginalized by ontologically separating them.

Impact of Landscape Patterns on Water Quality in Urbanized Rivers at Characteristic Scale: A Case of Pearl River Delta, China.

The impacts of landscape patterns on river water quality are commonly acknowledged, but understanding the complex processes by which landscape patterns affect water quality is still limited, especially in densely populated urban areas. Exploring the mechanisms through which landscape characteristics influence water quality changes in urbanized rivers will benefit regional water resource protection and landscape-scale resource development and utilization. Utilizing daily water quality monitoring data from rivers in the urbanized area of the Pearl River Delta in 2020, our research employed canonical analysis and partial least squares structural equation modeling (PLS-SEM) to explore the processes and mechanisms of the influence of urbanized river landscape patterns on surface water quality. The results indicated that total nitrogen (TN) was the critical indicator limiting the water quality of rivers in the Pearl River Delta. The landscape composition and configuration indexes exhibited non-linear variations with scale, and the landscape fragmentation was higher closer to the river. Landscape patterns had the most significant influence on water quality under the characteristic scale of a 5.50 km circular buffer zone, and landscape composition dominated the change of water quality of urbanized rivers, among which 30.64% of the percentage patch area of construction (C_PLAND) contributed 46.40% to the explanation rate of water quality change, which was the key landscape index affecting water quality. Moreover, landscape patterns had a higher interpretive rate of 39.29% on water quality in the wet season compared to 36.62% in the dry season. Landscape composition had an indirect negative impact on water quality, with a value of 0.47, by affecting the processes of runoff and nutrient migration driven by human activities, while landscape configuration had an indirect negative impact on water quality, with a value of 0.11. Our research quantified the impacts of landscape patterns driven by human activities on surface water quality and proposed management measures to optimize the allocation of landscape resources in riparian zones of urbanized rivers. The results provide a scientific basis for water quality management and protection in urbanized rivers.

Spatial and temporal dynamics of sewage sludge phosphorus recovery potential in the cities of Yangtze River Zone in China: Implications for regional recycling policies

Sewage sludge phosphorus (P) recovery presents opportunities to sustainably recycle P from cities to agriculture and alleviate global P scarcity. However, limited research explores sustainable recovery targets considering spatial-temporal variations in sludge generation and implications based on city-level local P demand. This study analyzed sludge production form 2009–2021 across 130 cities in China's Yangtze River Zone, which increased by almost 35 % from 2009 to 2021. Per capita gross domestic product (GDP), influent chemical oxygen demand (COD), and per capita drainage infrastructure were identified as the main significant influencing factors. City-level analysis revealed pronounced spatial-temporal disparities, with yearly sludge generation spanning five orders of magnitude (62–5.4 × 105 t/a). An indicator, “Potential of P recovery to local P demand”, was defined, indicating the average city-level P recycle contribution increased from 5.3 % to 18.9 % from 2009–2021. A novel frame paradigm classified cities into six types based on the local P supply-demand characteristics, prioritizing sludge P recovery and implementing strategic management. City-specific dynamics and possibilities of broader “city clusters” to match supply and demand should be considered for policy implement. Recovering P from livestock manure and kitchen waste alongside sludge can further strengthen urban P cycles. This study provides novel city-scale analysis and strategic considerations for regional sludge P recycling policies in China and beyond.

Tracing fluorescent dissolved organic matter (fDOM) characteristics and water quality parameters: Insights from an urban industrial river to marine zone.

This study aims to identify continuous water quality changes and identify fluorescence properties from urban rivers to marine zones. Various types of natural and anthropogenic sources derived dissolved organic matter (DOM) have been identified in this study. These include soil-derived DOM, plant remnants, and soluble particles produced when organic material partially decomposes and is released by microorganisms, such as bacteria, algae, and plants. DOM was characterized using a three-dimensional excitation-emission matrix (3DEEM), parallel factor analysis (PARAFAC), and water quality parameters from the Buriganga River, Dhaka to Patenga Seaport, Chittagong, along with the Shitalakshya River, a small portion of the Padma River, and the Meghna River. To better understand the data analysis, the study area was divided into three central regions: urban industrial rivers, industrial estuarine rivers, and marine zones. In the urban industrial river, 3DEEM and PARAFAC identified five fluorophores (peaks: A, C, M, T, and Tuv) with five components: detergent-like, fulvic-like, tryptophan or protein-like, fulvic-like (C-type), and protein-like, which might originate from the industrial activities and sewage pollution. In the industrial estuarine river zone, three fluorophores have been identified (peaks: A, C, Tuv) with two known components, namely, fulvic acid (A-type) and fulvic acid (C-type), with an unknown photoproduct at Ex/Em = 295/368 (peak Tuv). Components in the industrial river zone may originate from terrestrial sources, indicating vegetation along the river. In the marine zone, four fluorophores have been identified (peaks: Tuv, A, T, C) with two components, that is, protein- or tryptophan-like and humic acid-like from coral origin. The intensities of both fulvic-like and protein-like substances were high in urban industrial river water owing to industrial activity and sewage pollution. SUVA254 suggests high aromaticity in all three regions, whereas the optical properties suggest that terrestrial and microbial components are present in the urban industrial and estuarine rivers. This further indicates that urban industrial river water quality is highly polluted. The lowest degradation potential index (DPI) in the marine zone might result from the presence of the highest number of dissolved solids in the water, and the highest DPI of industrial estuarine rivers explains the comparatively high presence of terrestrial-derived humic (A)- and humic (C)-like components in the ratio to the unknown photoproduct of mid-wavelength. PRACTITIONER POINTS: This study's uniqueness is a 220-km cruise from an urban river to a coastal seaport to analyze fluorescence properties. The study found that most water parameters were within the DoE standards, except for DO, which was consistently low. 3DEEM-PARAFAC identified five fluorophores linked to detergent, fulvic, and protein-like substances from sewage and industrial sources. Our study concludes that microbial and terrestrial sources dominate dissolved organic matter in urban, estuarine, and marine regions.

Application of Methodology for Defining the Adjoining Lands and Flooding River Strips in Bulgaria in a GIS Environment Upon Bridge Facility Designing

The "Methodology for defining the adjoining lands and flooding rivers stripes in Bulgaria” (MALFARS) has been developed in 2012 based on the requirements of the EU Water Framework Directive 2000/60. In this article we investigated another aspect of MALFARS application. We have reviewed the possibilities for methodology application upon designing of bridge facilities within the researched river section. The study presents the application of the Methodology for the designing of a bridge facility over the Dzherman River upon the maximum dimensional water quantities calculated for the studied section of the river. We have used GIS instruments to analyze and evaluate the results obtained for the parameters of the maximum runoff and the conductivity of the river section. The results present the defined flooding zones of the adjoining river areas/stripes, good conductivity of the road facility, hydraulic and geometric characteristics of the runoff in the investigated river section in cases of high water levels

SEASONAL DYNAMICS OF CHEMICAL AND MICROBIOLOGICAL CHARACTERISTICS OF BOTTOM SEDIMENTS IN THE SEA ESTUARY OF A SMALL RIVER IN THE SEVASTOPOL REGION (BY THE EXAMPLE OF THE CHERNAYA RIVER, CRIMEA)

The annual dynamics of (1) chloroform-extractable substances (CES) and petroleum hydrocarbons (PH) in riverside fluvial sediments, in the bottom sediments of the mixing zone of river and sea waters, and in the bottom sediments of the marine area, and (2) the abundance of hydrocarbon-oxidizing (HOB) and heterotrophic (HB) bacterial groups in the bottom sediments of the marine area and riverside sediments is analysed. The maximal content of CES was found in the marine area (450±17.5 mg/100 g), and the minimal one - in the river part (127.6±10.9 mg/100 g), in the mixing zone of river and sea waters - 370±37.9 mg/100 g. The average concentrations of PH are distributed similarly to the concentrations of CES: the maximal values (127.5±10.9 mg/100 g) are detected in marine ground, the values for the sediments of the mixing zone are slightly lower (103.1±9.4 mg/100 g), and the minimal values (54.8±23.9 mg/100 g) are detected in river sediments. The physicochemical characteristics of bottom and coastal sediments are presented. The abundance of HB in the bottom sediments of the marine area varied from 7.5•103 to 2.5•106 cells/g, respectively, and from 9.5•103 to 9.5•108 cells/g in the river area. There was no seasonal variability in the abundance of HB at both areas. Hydrocarbon-oxidizing bacteria were registered in 100 % of the samples of bottom and riverside sediments of the designated water areas. The abundance of HOB varied from 25 to 2.5•104 cells/g in the marine zone and from 25 to 4.5•103 cells/g in the river zone. The maximal values of HOB abundance in the riverside sediments were recorded during the flood period (February-April).

Zooplankton functional diversity as a bioindicator of freshwater ecosystem health across land use gradient

Zooplankton are critical indicators of pressures impacting freshwater ecosystems. We analyzed the response of zooplankton communities across different sub-catchment types—headwaters, natural, urban, urban-agricultural, and agricultural—within the Łyna river–lake system in Northern Poland. Using taxonomic groups and functional traits (body size, feeding strategies), we applied Partial Least Squares Regression (PLS-R) to elucidate the relationships between environmental conditions, land use, and zooplankton metacommunity structure. Two-Way Cluster Analysis (TWCA) identified local subsets with characteristic patterns, while Indicator Species Analysis (ISA) determined area-specific taxa. The natural river zone exhibited significant habitat heterogeneity and feeding niches, whereas urban areas created functional homogenization of zooplankton, dominated by small, broad-diet microphages. Agricultural areas promoted diversity among large filter feeders (Crustacea), active suctors (Rotifera), and amoebae (Protozoa). However, intensified agricultural activities, substantially diminished the zooplankton population, biomass, taxonomic richness, and overall ecosystem functionality. The impact of land cover change is more pronounced at small-scale sub-catchments than at the catchment level as a whole. Therefore, assessing these impacts requires detailed spatial and temporal analysis at the sub-catchment level to identify the most affected areas. This study introduces a new sub-catchment-based perspective on ecosystem health assessment and underscores the zooplankton's role as robust indicators of ecological change.

Evolution of riparian vegetation in response to anthropogenic effects: The Taleqan River, Iran

AbstractDuring the last decades, human interventions, such as dam construction and land‐use change, have caused changes in geomorphic patterns and riparian zones in many rivers in Iran. This study aimed to assess the spatio‐temporal evolution of riparian vegetation and the spatial area of biogeomorphic feedback windows (BFWs) located in the riparian Salicaceae vegetation patches and their traits responding to human interventions in the Taleqan River during 1990–2022. The river was divided into five reaches using the geomorphic unit system (GUS) method, and the river sensitivity index (SI), location of BFWs, vegetation typology and main cover typology were investigated in the reaches using aerial photographs and satellite images from 1990 to 2022. For this purpose, the main cover typology was classified into grassland, woody vegetation, bank‐attached bars, islands, vegetated islands, river channels and urban areas. The stem diameter and density, degradation level and longitudinal/latitudinal alluvial bars in each of the BFWs were investigated using the field survey. Based on the findings, the lowest values of the SI (braiding index [BI], channel activity [CA] and channel width [CW]) and the highest expansion of BFWs were observed in the upstream reaches of the Taleqan River. Human disturbances in these reaches were less than in the reaches downstream, allowing the expansion of vegetation habitats. The vegetation patches were unstable and scattered in the midstream and downstream, and the width decrease of the river channel was created by land‐use change and channelization. A significant direct relationship was observed between BFW establishment, stem diameter and density, and vegetation height. The BFWs create an opportunity for engineer vegetation to prevent erosion and expand new habitats by creating biogeomorphic accumulation landforms and trapping alluvial bars on the lee side of engineer woody vegetation. This study highlights the interactions between riparian areas and hydrogeomorphic processes within riparian corridors exposed to human disturbances to help better define a comprehensive plan for river management.

Flow structures in large-scale bank erosion zone of Lower Yangtze River

The bank erosion process in the densely populated Lower Yangtze River can pose a great threat to riparian residents and industries. It is characterized by rapid development within a few hours, a large-scale soil collapse of 106 m3, and an arc shape. During its development, flow field inside the bank erosion area continuously evolves and interacts with the bank soil. However, the mechanisms behind the bank erosion process are still unclear. Therefore, laboratory experiments were conducted to investigate flow structures and turbulences inside bank erosion areas. A pulsed particle image velocimeter was employed to obtain high-quality velocity data inside the bank erosion zone. Results show that the bank erosion zone can be divided into a backflow zone, a mixing zone, and a mainstream zone, according to variations in flow structure; in the mixing zone, water flow is highly turbulent, and the mixing width gradually increases downstream because of the shear effects between the mainstream and backflow; the backflow zone can be subdivided into a central zone and a peripheral zone, based on the pattern of velocity changes along the radial axis from the backflow center to its periphery. A formula for calculating the flow velocity within the backflow zone was proposed, and we found that the velocity gradient in the peripheral zone was approximately four times higher than that in the central zone. This indicated that shear stress exerted by the flow near the backflow boundary was significantly intensified.

Zooplankton community heterogeneity and trophic interactions in response to environmental drivers in a mesotidal estuary on the Brazilian equatorial margin—Lençóis Maranhenses National Park

Abstract This study emphasises the importance of environmental filters in the dynamics of the zooplankton community and the ecological relationships with phytoplankton in three zones of a tropical mesotidal estuary. Thus, sampling was carried out in six different locations strategically positioned along the Preguiças River estuary, with the following objectives: to characterise the abundance of zooplankton and, through this, determine changes in the community's α‐ and β‐diversity indices depending on variables environmental; to define environmental filters that affect the indicator species of ecosystem zones; and to identify the interaction between phytoplankton and zooplankton along the estuarine gradient. The zooplankton community contained 80 species, including 14 phyla, with Arthropoda being the most diverse, followed by Ciliophora and Mollusca. The class Copepoda stood out, with Paracalanus crassirostris, Pseudodiaptomus gracilis, and Oithona nana dominating the community. In total, 21 species were selected as indicators, including Temora turbinata in the coastal zone, Rhizodomus tagatzi in the mixing zone, and Moina micrura in the tidal river zone. The environmental heterogeneity showed significant spatial differences, with variations governed mainly by salinity, temperature, and suspended organic matter, which acted as the principal environmental filters. The coastal zone and mixing zone species demonstrated direct ecological relationships with the blooms of the diatoms Skeletonema costatum and Asterionellopsis glacialis, in which the abundance of zooplankton was favoured by their occurrence, denoting top‐down control of the trophic network. For the partitioning of β diversity, the turnover component was responsible for the diversity value due to environmental heterogeneity, which distinguished communities across zones. Our findings represent the first comprehensive investigation into the relationship between environmental heterogeneity and zooplankton within this tropical ecosystem, subject to mesotides. These discoveries are pivotal in identifying environments highly susceptible to degradation (low β diversity) and those acting as dispersal centres (high β diversity), thereby facilitating targeted conservation efforts and more efficient management of estuarine systems. Therefore, our results provide a crucial basis for the sustainable management of similar coastal ecosystems in different parts of the world.

HYDROLOGICAL AND HYDROCHEMICAL ASSESSMENT OF WATER STATUS OF THE SOUTHERN BUG RIVER WITHIN THE BOUNDARIES OF VINNICHCHINA

It is highlighted that in modern conditions, the surface waters of land are subject to significant anthropogenic influence, as a result of which their natural state is significantly changed and the possibility of using certain water bodies for economic and drinking needs is significantly limited. Since the drinking water supply of Ukraine is carried out mainly at the expense of surface water, objective information about the condition of water bodies, established on the basis of hygienic and ecological criteria, becomes extremely important and relevant. It was established that the influence of the economic and household activities of the village of Kolyukhiv, Vinnytsia region, on the pollution of the South Bug River within its borders is determined by the influx of nitrogenous substances, which lead to an increase in the concentration of ammonium nitrogen, nitrites and nitrates. The source of nitrogen input to the river water is surface runoff washing and the development of soil erosion processes from the adjacent shorelines, which are used for homestead farming and gardening. As a result of the research, it was found that in a sample of water taken from the South Bug River within the village of Kolyukhiv, Vinnytsia region, 1 km upstream in the forest plantation zone, the hydrogen pH is 7.8, the ammonium nitrogen content is 0.3 mg/l nitrite concentration – 2.7 mg/l, nitrate content – 39.6 mg/l, calcium content – 86.0 mg/l, chloride – 147.4 mg/l, and in the selected water sample 1 km downstream in the zone of intensive farming (homesteads), the hydrogen pH was 8.4, the content of ammonium nitrogen was 0.8 mg/l, the concentration of nitrites was 3.7 mg/l, the concentration of nitrates was 69.3 mg/l, the content calcium – 96.6 mg/l, chlorides – 164.2 mg/l. The main way to limit the flow of nitrogenous substances into the river is to observe sanitary protection zones along the river's perimeter. The sanitary and protective zone of the South Bug River should be 100 m, and in fact it is 10 m within the village. Therefore, the main measure is the expansion of the sanitary and protective zone to 100 m and its observance, which will allow reducing the content of ammonium nitrogen in the river water by 62% , nitrates – by 27%, nitrites – by 48%.

Epiphytic Algae on Dominant Macrophytes in Lotic Ecosystems in the Eastern Flanks of Mount Cameroon

Aims: This study was designed to assess quantitative estimates of epiphyte biomass and diversity on the dominant macrophytes in two rivers in the Eastern flanks of Mount Cameroon. Place and Duration of Study: Two sets of water samples were collected at the top 10cm of the rivers for nutrient and chlorophyll a determination. A single preliminary collection of algal epiphytes from partially submerged aquatic macrophytes was carried out from the littoral zone of Ndongo and Limbe rivers, between May and June 2023. Methodology: The sedimentation technique was employed in the study. Three slides were prepared for each aquatic macrophyte sample for microscopic analysis. Identification was done by comparative morphology using relevant journals and textbooks. Results: All variables related to water clarity (TSS, Phytoplankton Chl a, HC) assessed during the study were similar in both rivers. Water clarity based on HC values was below 6 mg/l implying both rivers were clear during the study period. Epiphytic algae identified were recorded from 4 main divisions, namely Bacillariophyta, Chlorophyta, Cyanophyta and Euglenophyta. The highest algal diversity in Ndongo was recorded from Commelina benghalensis (H=3.45) with 41 algal species identified. Justicia in Ndongo river had the lowest algal species richness (24) with an algal diversity of 2.91. Nymphaea had the highest algal diversity (H=3.36) and algal species richness (36) in Limbe river. Algal species richness was the same in the two other plant hosts Commelina benghalensis and Colocasia esculentus (29 species per host). The highest algal chlorophyll a was recorded on Nymphaea (621mg/g dry weight) and Commelina benghalensis (644mg/g) in Limbe and Ndongo respectively. Lowest epiphyte Chlorophyll a was recorded in Justicia secunda in Ndongo (607 mg/g). Conclusion: All macrophytes studied harbored a large algal flora demonstrating their diverse ecological roles carried out in these rivers. Nymphaea lotus and Commelina benghalensis in Limbe and Ndongo rivers had the highest epiphytic algal biomass.

Attenuation of water contamination in the Paraopeba River after the collapse of B1 tailings dam: Natural wash-off and dredging contributions

Following the B1 dam collapse at Córrego do Feijão Mine, actions were taken to address environmental damage and enhance the quality of water in the Paraopeba River. Natural processes in the river involve gradual reduction of contamination through dispersion and downstream transportation of tailings—a slow, nature-driven process. Dredging, a human intervention, aimed to expedite recovery. Hence, this study aimed to explore dredging's role in reducing contamination in the impacted Paraopeba River zone. Analysis revealed a direct link between dredging and post-collapse turbidity, though recent trends suggest a lessening impact on pre-collapse conditions.Distinct seasonal variations were observed in iron and manganese concentrations, peaking during wet seasons and displaying notable upstream-downstream disparities. An analysis of ratios (downstream/upstream) was conducted to understand and even predict the return to pre-collapse conditions. Wet season averages for iron and manganese decreased by around 90 % over time, with standard deviations reducing by about 48 % and 58 %, respectively. In the dry season, the averages decreased by over 100 %, indicating water quality improvements surpassing pre-collapse levels. Standard deviations also decreased significantly, by approximately 67 % and 79 %, respectively.Employing an exponential decay model revealed that the contribution of dredging in the dry period is negligible, but in the wet period the contribution can be estimated at 28.6 % in the case of iron and 25 % in the case of manganese. While the models performed well based on extensive data, some limitations occur in estimating dredging contribution rates. The model's sensitivity might overlook influential factors, underscoring the importance of considering sediment nature and dredged area extent in understanding water quality dynamics. Despite these potential limitations, this investigation provides crucial insights into the intricate relationship between dredging and water quality in the Paraopeba River. These findings pave the way for future studies aimed at deeper exploration and more accurate assessments of this association.

A Quantitative Provenance Analysis (QPA) Approach to Quantify Controls on Sediment Generation and Sediment Flux in the Upper Reaches of the Magdalena River (Colombia): 2. Lithological Control on Contribution to Silt‐ to Clay‐Sized Fractions

AbstractThe composition of 27 fluvial silt and clay sediments was used in this study to identify and quantify the processes in the upper valley of the Magdalena river in South Colombia. The combination of seismic activity, intense precipitation, and landsliding resulted in limited chemical weathering and a very efficient transfer of weathered products to the transfer zone of both tributary rivers and the main trunk. Inputs from plutonic, high‐grade metamorphic, volcanic, and low‐ to medium‐grade metamorphic lithologies vary in coarse silt‐sized versus fine silt‐ and clay‐sized sediments, reflecting inherited textural parameters and mineralogy. Plutonic and high‐grade metamorphic rocks mostly produce sand‐sized sediments, up to two times more than coase silt and up to 10 times more than fine silt to clay. The prevalence of siltstone in the area enhances the contribution of sedimentary rocks to fine silt and clay (up to 50% higher than to sand). Volcanic rocks mainly produce coarse silt (up to 2.5 times more than sand). Low‐grade metamorphic detritus is enriched in silt and clay (up to 5–7 times). These findings highlight the critical role of lithology in regulating sediment generation. The study's approach can establish or modify factors modeling lithological control on suspended sediment flux, such as in the BQART equation.

Analysis of activity rhythm and behavior pattern for plateau pika in degraded alpine meadow

This paper proposes a behavior observation method for plateau pika (Ochotona curzoniae) in degraded alpine meadow in the Source Zone of the Yellow River (SZYR) on the Qinghai–Tibet Plateau based on continuous monitoring videos to observe its activity rhythm. The video surveillance cameras are installed facing toward degraded alpine meadow in the SZYR and run from March 2021 to February 2022 to record time allocation of plateau pika behavior (i.e., digging, foraging, guarding, moving and other behaviors) and its daily, monthly, and seasonal activity rhythm. The results indicate that: (1) The most active ground activity time is between 10:00 and 16:00, meanwhile it is inactive at night, which proves it plateau pika is diurnal animals. (2) Digging and foraging are frequently occurring behaviors among its daily activities, which occurs from 9:00 to 12:00 and 16:00. (3) Compare to other season, winter sees relatively frequent occurrences of digging and foraging according to the seasonal analysis results. (4) From annual perspective, digging and foraging accounted for 66.13% of plateau pika activity, while guarding accounted for 13.35%, moving accounted for 11.64%, and other behaviors accounted for 8.88%. There is a significant difference in the frequency of each behavior between the two groups (P < 0.05). The behavior observation method using video surveillance camera contributes to behavioral ecology information of plateau pika.