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The relative abundance of the C 32 1,15 long-chain alkyl diol (LCD) is an emerging proxy for the input of riverine aquatic particulate organic carbon (POC) into coastal oceans. This compound has the potential to complement other established proxies reflecting riverine terrestrial POC input and allows for a more nuanced assessment of riverine POC export to coastal seas. The current understanding of this proxy is, however, limited. In this study, we compare different indices for riverine sediment input to coastal marine waters (i.e. C 32 1,15-LCD, BIT index and Fe/Ca ratio) in a source-to-sink assessment in the Amazon River drainage system and the northeast South American continental margin, and we test their down-core applicability in a marine gravity core containing late Pleistocene fluvial Amazonian sediments. We show that the relative abundance of the C 32 1,15-LCD is highest in water bodies with low flow velocity and low turbidity such as the downstream portion of lowland tributaries and floodplain lakes. Relative C 32 1,15-LCD abundance is lowest in Andean white water tributaries where autotrophic productivity is hindered by high turbidity and high flow velocity. We also find that suspended particulate matter from all major tributaries during the extreme 2015 dry season has a similar LCD distribution to that of floodplain lakes. This indicates that the chemical composition of the tributaries is less relevant for the LCD distribution than their physical properties such as flow velocity and turbidity. Results from marine surface sediments offshore the Amazon River estuary show significant positive correlations between all three studied proxies. In contrast, we find that the relative C 32 1,15-LCD abundance in the down-core record is anti-correlated to the BIT index and Fe/Ca ratio. While BIT index and Fe/Ca ratio show high (low) values during Heinrich stadials (Dansgaard-Oeschger interstadials), the C 32 1,15-LCD proxy shows the opposite signal. BIT values are also higher during Marine Isotope Stage (MIS) 2 than during MIS 3, in contrast to trends in the C 32 1,15-LCD proxy. We posit that this pattern arises from a reduction in relative C 32 1,15-LCD abundance and total LCD productivity in the Amazon River during MIS 2 when less-humid conditions and lower sea level led to reduced area of floodplains. During Heinrich stadials, Andean sediment input increased and led to higher turbidity that resulted in lower C 32 1,15-LCD production. Our study shows that major changes in water discharge, sediment transport and river morphology can lead to discrepancies between the BIT index and the relative abundance of the C 32 1,15-LCD. Thus, we suggest that Amazonian aquatic and terrestrial POC pools had contrasting responses to changes related to both climate (e.g. increased Andean precipitation) and river morphology (e.g. steeper along-channel slope due to falling and low stand sea level). [ABSTRACT FROM AUTHOR]

After the implementation of the Water Framework Directive 2000/60, biotic indices became an important tool aiming at assessing the water quality of all water bodies, such as lakes, transitional, coastal and groundwater, and the restoration of their ecological integrity. Due to the fact that fish is one of the most important taxa for the assessment of the river quality in the present study an attempt was made to develop and apply a Fish-based River Integrity Index (FRII) for the assessment of the Greek riverine systems, which may also be applied for the assessment of other Balkan or Mediterranean rivers. Due to the high importance of the Balkan's Peninsula fish fauna in terms of endemicity, the assessment of the riverine systems is considered as sine qua non. The proposed index consists of multiple metrics, which attempt to describe the biological and demographical traits of the fish fauna. More specific the FRII is composed by seven metrics, of which three metrics were describing "Fish fauna composition and abundance", three were describing the Reproduction strategies of the species, while the remaining one metric related to the "Habitat preferences". [ABSTRACT FROM AUTHOR]

Highlights • Metagenome metabolic networks provide information of complex ecological processes. • Metabolic potential of a microbiome is not the same as active metabolic functions. • Contamination has distanced Bogotá River's metabolic state from unpolluted systems. • Active reaction modules place Bogotá River closer to produced water. Abstract The microbiomes of contaminated water bodies have altered microbial communities and functional capacity. Metagenomic data provides information on the microbiome at taxonomic and functional level. However, metagenomes from different environmental samples have shown that differences in taxonomy don't always reflect changes in metabolic functions. Here, curated metagenome level network reconstructions for the highly contaminated Bogotá River and five additional samples were constructed and compared through topological analysis and flux balance analysis, using a constraint-based optimization method. Active metabolic fluxes change depending on simulated conditions evidencing a distance between potential and active functions. Higher microbial diversity was found to have little effect on potential functions but a positive effect on metabolic network robustness. A high degree of contamination in the Bogotá River has altered the microbiome's metabolic functions making the system distant from a natural state. The microbiome of the Bogotá River was found to be functionally similar to the microbiome of Produced Water. Metabolic network reconstructions increase the information obtainable from metagenomic data and allow modelling of complex ecosystems. [ABSTRACT FROM AUTHOR]

• Hydrological modelling is a fast and reliable tool that aids in watershed processes. • SWAT is very efficient in predicting water quality parameters under different land uses. • BMPs in agricultural watersheds can assists in achieving reductions in pollutant export. Continued re-eutrophication of Lake Erie has led to the updated 2012 Great Lakes Water Quality Agreement (fully enacted in 2016) that established new binational phosphorus load reduction of 40% from 2008 baseline loading rates. Nonpoint source pollution is the leading cause of water impairment in agricultural watersheds; however, the water quality can be improved by implementing various BMPs for control of erosion and nutrient loss from watersheds. The Grand River watershed (GRW) occupies about 6800 km2 and is an important agricultural area in Southern Ontario. Changes in land use over the past century in the GRW have led to altered hydrology and greater export of sediment and nutrient loads into Lake Erie. The objective of this study was to investigate the impact of various BMPs in reducing sediment and phosphorus loading rates on various spatial and temporal scales in the watershed using SWAT for the years 2001–2010. The baseline sediment and P loading at Dunnville, prior to the Grand River's discharge to Lake Erie, were predicted to be 2 × 105 tonnes y−1 and 2 × 105 kg y−1, respectively. Different source, transport and water body treatment BMPs were simulated. With respect to reducing sediment and P loading into Lake Erie, implementing wide buffer strips resulted in a decrease of 23% and 50%, respectively. Stabilizing channel banks resulted in reduced sediment and P loading of 38% and 36%, while grassed waterways resulted in reductions of 15% and 17%, respectively. [ABSTRACT FROM AUTHOR]

Highlights • Runoff forcing impact is examined in ocean simulations over the Western Mediterranean. • A validation is done using sea surface observations collected during HyMeX SOP1. • River plumes extend is increased using runoff observations over climatological data. • The use of runoff observations change the sea surface salinity and temperature. • A vertical distribution of runoff modifies the stratification close to river mouths. Abstract The Western Mediterranean Sea is often affected by heavy precipitation which frequently generates floods or even flash floods. These events generally produce brief but major freshwater inputs in the ocean. In order to evaluate the sensitivity to the representation of river freshwater input, three different runoff forcing dataset are used to drive the NEMO ocean model: a monthly climatology, an observational dataset with a daily or a hourly frequency. The sensitivity is investigated over the first Special Observation Period (SOP1) of the HyMeX program that took place in autumn 2012, in two configurations of NEMO: the first is WMED36 over the Western Mediterranean Sea at 1/36°-resolution and the second is a new configuration covering the North-Western Mediterranean Sea with a 1/72°-resolution named NWMED72. With NWMED72, the impact of the representation of the river freshwater flux, i.e. moving from a surface flux to a vertical distribution of the flux, is also evaluated. The results show that the ocean stratification is significantly modified locally in simulations where runoff observations are used compared to those using the climatology. The sea surface salinity is modified as well as the mixed layer which is thinner as bounded by a well marked halocline. The sea surface temperature is also impacted by the change in runoff frequency. Moreover, the current intensity in river plume during flood is increased. Vertical profiles of salinity and temperature and thus the mixed layer depth are changed when the runoff forcing is distributed over a depth. Those changes are limited and very local but the realism of the river runoff input is improved. [ABSTRACT FROM AUTHOR]

Even though the drylands of Central and Eastern Asia are among the most continental regions of the world, they are also home to some of the largest rivers and lakes in the world. Because of a low population density, many of these water bodies have remained in relatively pristine condition until the mid-20th century, when urbanization, intensive agriculture and mining activities began to leave massive footprints on the regional environment. In more recent decades, water bodies in the region have been massively modified by both water withdrawals and pollutant influxes. At the example of the Lake Baikal, Aral Sea, and Tarim River basins, this paper provides an overview of the impacts of human activities on the large rivers and receiving (terminal) lakes in Central and Eastern Asian drylands. Finally, recent measures to at least partially restore their aquatic ecosystems are analyzed. [ABSTRACT FROM AUTHOR]

• We reveal a median-to-excellent performance of S-3A water levels in the Songhua River Basin in China. • We develop an update for rivers of the AMPD-PF retracker (Automatic Multiscale-based Peak Detection retracker using Physically-based model Fitting). • Sand bars and islands, and cultivated land type significantly influences the data accuracy. • A near-parallel orientation of the river with respect to the satellite ground track often leads to poorer performance at virtual stations. Satellite radar altimetry is an important tool for monitoring water levels of inland water bodies, particularly in poorly gauged or ungauged areas. This study reveals for the first time the performance of water levels derived from Sentinel-3A altimetry in the Songhua River Basin in northeast China. This study compares water levels derived via different retrackers (SAMOSA+, OCOG, Ocean, MWaPP, and NPPR) from altimetry in virtual stations (VSs) to water levels measured by gauges. To improve the influence of sandbars or islands and surrounding land cover, a modified retracker called AMPD-PF (Automatic Multiscale-based Peak Detection retracker using Physically-based model Fitting) is implemented here, by combing the physical modeling of SAR altimeter waveform with a shortest-path algorithm to find the best possible sub-waveform representing the signal of water bodies. The accuracy assessment is based on comparing water level anomalies from 26 VSs and those from the nearest adjacent gauges with an average distance of 8.98 km in the Songhua River Basin from 2016 to 2019. The median of the root-mean-square error (RMSE) differences at the virtual stations ranges from 0.46 to 0.82 m, and the median of the Nash-Sutcliffe efficiency (NSE) among different retracker varies from 0.49 to 0.85 among different retracker. The performance of Sentinel-3A altimetry in the Songhua River Basin is not poor. Results also show a highest accuracy of water levels from AMPD-PF, especially for the non-flood season (January to June and October to December). In addition, we find that, especially for the virtual stations unaffected by the sand bars and islands, AMPD-PF give the best performance with a median RMSE value of 0.33 m and a median NSE value of 0.86. Factor analysis indicates that the variations of these metrics can not be directly related to the river width but might be related to the cultivated land types and the presence of sand bars and islands in the vicinity of rivers over the Songhua River Basin. Moreover, it is confirmed that a near-parallel orientation of the river with respect to the satellite ground track often leads to poorer performance at virtual stations. This suggests that if one is aiming at calibrating a hydrodynamic or hydrological model by combining altimetry, the VSs with the near-parallel orientation are not necessary to be considered when the percentage of the non-parallel crossings of all crossings is big enough. [ABSTRACT FROM AUTHOR]

Freshwater acidification continues to be a major problem affecting large areas of Europe, and while there is evidence for chemical recovery, similar evidence for biological recovery of freshwaters is sparse. The need for a methodology to identify waterbodies impacted acidification and to assess the extent of biological recovery is relevant to the EU Water Framework Directive, which requires methods to quantify differences in biology between impacted and unimpacted or reference sites. This study presents a new WFD-compliant metric based on diatoms (Diatom Acidification Metric: DAM) for assessing the acidification status of rivers. A database of 558 benthic diatom samples and associated water chemistry data was assembled. Diatom taxa were assigned to one of 5 indicator classes on the basis of their pH optimum, assessed using Gaussian logistic regression, and these indicator values used to calculate a DAM score for each site using weighted averaging. Reference sites were selected on the basis of their acid neutralising capacity (ANC) and calcium concentration, and a regression model developed to predict expected DAM for each site using pH and total organic carbon (TOC) concentration. Site-specific DAM scores were used to calculate ecological quality ratios ranging from ≥ 1, where the diatom assemblage showed no impact, to (theoretically) 0, when the diatom assemblage was indicative of major anthropogenic activities. The boundary between ‘high’ and ‘good’ status was defined as the 25th percentile of Ecological Quality Ratios (EQRs) of all reference sites. The boundary between ‘good’ and ‘moderate’ status was set at the point at which nutrient-sensitive and nutrient-tolerant taxa were present in equal relative abundance. The methodology was evaluated using long-term data from 11 sites from the UK Uplands Waters Monitoring Network and is shown to perform well in discriminating naturally acid from acidified sites. [ABSTRACT FROM AUTHOR]

Contemporary bioassessment methods for water bodies require the description of “reference conditions” representing an absence or only “very minor” presence of human impacts on hydromorphological, physical and chemical properties. However, minimally disturbed reference sites are lacking in many European regions and other parts of the world because of pervasive anthropogenic influences. Here we describe the use of environmental filters modelling, incorporating boosted trees (BT), to derive reference data for abiotic variables and biological communities (diatoms and macroinvertebrates) for rivers in a highly disturbed region (Portuguese central-western lowland area), where minimally disturbed reference sites are non-existent. We also revise quality class boundaries for diatom and macroinvertebrate bioassessment in this region, and develop a new multimetric diatoms index (MDI). The new index includes not only the ‘ Indice de Polluosensibilité Spécifique’ (IPS) based on species’ sensitivity to organic pollution and nutrients, but also the numbers of total and sensitive taxa. Our approach predicted significantly different communities under reference conditions from those observed, with a higher median reference number of taxa per site than the observed number (69 against 27 for diatoms; 53 against 22 for macroinvertebrates). In addition, the predicted communities for both biological groups were more similar among sites than the observed communities. Adjustment of index calculation and quality class boundaries to incorporate the new reference data resulted in more stringent site assessments that were better correlated with human pressures than assessments with previous methods. This study brings new insight to solve the problem of an absence of minimally disturbed reference sites. [ABSTRACT FROM AUTHOR]

Development of river waterfront is reflected on the natural resources of cities with particular characteristics and it is one of the most important factors that influence on the growth and image of cities. Guidelines presented in this study are based on the idea that human citizens of Podgorica and its visitors can experience the continuity of movement, poor motorized traffic along the river course Morača and Ribnica, as well as connecting parts of the city over them. This role of urban rivers have a significant impact on urbanization and modernization. [ABSTRACT FROM AUTHOR]

The research reported in this paper employs flume experiments to investigate the potential effects of living vegetation and large wood on river morphology, specifically aiming to explore how different wood input and vegetation scenarios impact channel patterns and dynamics. We used a mobile bed laboratory flume, divided into three parallel channels (1.7 m wide, 10 m long) and filled with uniform sand to reproduce braided networks subject to a series of cycles of flooding, wood input, and vegetation growth. Temporal evolution of river configuration (in terms of the braiding index), vegetation establishment and erosion, and wood deposition amount and pattern was recorded in a series of vertical images. The experiments reproduced many forms and processes that have been observed in the field, from scattered logs in unvegetated, dynamic braided channels to large wood jams associated with river bars and bends in vegetated, stable, single-thread rivers. Results showed that the inclusion of vegetation in the experiments changes wood dynamics, in terms of the quantity that is stored and the depositional patterns that develop. Vegetated banks increased channel stability, reducing lateral erosion and the number of active channels. This promoted the formation of stable wood jams, where logs accumulated continuously at the same locations during subsequent floods, reinforcing their effect on river morphology. The feasibility of studying these processes in a controlled environment opens new possibilities for disentangling the complex linkages in the biogeomorphological evolution of the fluvial system and thus for promoting improved scientific understanding. [ABSTRACT FROM AUTHOR]

Logjams significantly influence watershed hydrology, flow regime, channel morphology and stability, and processes in lowland rivers. Consequently, logjams play a major role in the existence and conservation of the riparian and aquatic ecosystems along major waterways. In this paper, we attempt to detect and quantify logjams in river channels using LiDAR technology in conjunction with traditional fieldwork. To the best of our knowledge, LiDAR-based analysis has not been used to characterize logjams in streams. Overall, when applied in a lowland river environment, LiDAR-based analysis demonstrates a comprehensive solution for detecting logjams in relation to the fieldwork, with a low rate of omission. A filtered approach predicted the presence of 95% of fieldwork-reported logjams (a 5% rate of omission), but also identified six logjams not identified in the field (a 10% rate of commission). A nonfiltered approach identified 87% of field-reported logjams, producing a 13% rate of omission and a 6.7% rate of commission. Dimension measurements were more consistent in the filtered LiDAR approach, showing 53%, 34%, and 90% of R 2 improvements for the length, width, and height, respectively, over the unfiltered LiDAR values. As vegetation cover hindered accurate delineation of logjam boundaries by LiDAR, field and LiDAR measurements of nonvegetation-obstructed logjams were more highly correlated than the field and LiDAR measurements of partially and completely vegetation-obstructed logjams. [ABSTRACT FROM AUTHOR]

The Iberian Chain (central–eastern Spain) is characterized by a dome-shaped topography with poorly incised and relatively flat landscape in its interior at an elevation of ~ 1300 m. A recent regional tectonic event started during or after the Late Pliocene, inducing deep valley incision on the flanks of the Iberian Chain. The rate and timing of this deformation, as well as the magnitude of the uplift-induced erosion processes, still lack a quantitative validation. We used 3D (SIGNUM) and 1-D (river profile) numerical models to investigate the landscape evolution of the Iberian Chain from the Late Pliocene to the present and to study the response of topography and rivers to tectonically induced base level lowering. Our model results are supported by geological, geomorphological and geochronological data. The results of the SIGNUM experiments show that the Iberian Chain topography has experienced regional uplift since ca. 3 Ma with rates between 0.25 and 0.55 mm y − 1 . In response to this uplift, rivers have incised at an average long-term incision rate of about 0.22 mm y − 1 and have progressively captured drainage areas from the chain interior. To further validate the results of landscape evolution modeling, we use a 1-D river incision model to explore the incision history of several rivers draining the Iberian Chain. The results constrain the range of values of bedrock erodibility from 5.8 × 10 − 5 to 5.0 × 10 − 4 m 0.4 y − 1 and predict long-term incision rates similar to those from the SIGNUM experiments. [ABSTRACT FROM AUTHOR]

The Pleistocene opening of the endorheic Duero River drainage basin (northwestern Spain and central Portugal) has led to river incision, creation of steep valley sides, and development of large (> 0.1 km 2 ) and episodically active rotational and roto-translational landslides along river reaches where a weak geological lithology has been exposed by river erosion. These landslides occur in the central part of the Duero basin despite low precipitation, weak contemporary seismicity, and low regional relief. These landslides occurred as a result of the downcutting of the Duero River and its tributaries through a sequence of Miocene basin-fill sediments. In the last few thousand years the incision reached a series of high-plasticity, low-strength clay layers within the sedimentary sequence. Owing to this mechanism, these landslides occurred in a specific area at a specific period of time. All of the large landslides are located at the outside of meander bends, suggesting that river lateral erosion facilitated slip failures. Recent anthropogenic activities to control river flows and to stabilize river banks have decreased the possibility of future landslides in this area. [ABSTRACT FROM AUTHOR]

In-channel wood is a fundamental component of the riverine system. Its nature, abundance, and distribution as well as the role of wood in trapping sediment have been reported by many authors. However, a lack of knowledge still exists on how the geomorphic effects, quantity, and characteristics of in-channel wood may be altered by different human pressures. For this reason, in-channel wood was surveyed in the Brenta, Piave, and Tagliamento gravel-bed rivers (northeastern Italy), which are altered by different degrees of human pressures. Both single pieces of wood (> 0.1 m diameter, and/or > 1 m long) and accumulations of large wood were measured on cross sectional transects within the active channels. Overall, 3430 (8.4, 13.9 and 10.7 elements/ha in the Brenta, Piave, and Tagliamento rivers, respectively) of isolated pieces and 591 (9.8, 15.0, and 11.0 wood accumulations/ha in the Brenta, Piave, and Tagliamento rivers, respectively) accumulations were surveyed in the study sites. In the Brenta and Piave rivers, which feature the greater human pressures, logs appear in a worse state of conservation. In the less disturbed Tagliamento River, the logs appear to be smaller and in a better state of conservation with higher capacity for resprouting. In addition, higher geomorphic interactions were found between wood and sediments in the Tagliamento River. Because of its ability to create geomorphic effects, in-channel wood represents an important source of complexity that can increase habitat diversity in river systems. A better knowledge of the role of human disturbances on the characteristics and abundance of large wood in river systems could help in developing better river management and the practical application of river ecology. [ABSTRACT FROM AUTHOR]

Studies on aquatic biodiversity in different waterbody types have attracted significant attention worldwide to achieve the goal of freshwater conservation. Different freshwater habitats can help maintain regional biodiversity by directly supporting aquatic plants and forming networks to promote aquatic dispersal across regions. However, few studies have conducted large-scale comparisons of macrophyte diversity among different waterbody types in China due to a lack of a national macrophyte dataset. Here, we compared species richness, species composition, beta diversity, and its components among ponds, ditches, disturbed ponds, lakes, rivers, and reservoirs in southern China. We found that macrophyte species composition overlapped in the different waterbody types, indicating similar regional species pools. Species composition was best explained by temperature, elevation, and flow velocity. For species richness, ponds supported the highest number of species, followed by lakes, ditches, rivers, and reservoirs, with disturbed ponds showing the lowest diversity. For beta diversity, the relatively low turnover and high nestedness in the lakes indicated high dispersal of macrophyte species throughout these water bodies or suggested that human disturbance in lakes may lead to a more uniform chemical environment and thus regional macrophyte community. This study emphasized the importance of maintaining the diversity of different waterbody types in the landscape and determining the most threatened freshwater habitats. Moreover, small water bodies (e.g., ponds) contribute more to the regional macrophyte species pool than permanent water bodies (e.g., lakes) due to their relatively high biodiversity value. Their stable hydrological environment may help maintain rare and uncommon species that do not appear in other waterbody types. • Composition was best explained by temperature, elevation and flow velocity. • Pond support the highest species richness, followed by lake, ditch, river and reservoir, with disturbed pond the least. • ponds tend to have high turnover and low nestedness while lakes hold opposite trend. • Turnover responses strongly to depth in deep rivers, which should be protected. [ABSTRACT FROM AUTHOR]

Abstract: Cut-off meanders, backwater ponds, and blocked valley coves are all common features along the tidal reaches of lowland rivers. While significant progress has been made to understand sediment dynamics in similar off-river environments above the head of tides, less is known about the processes driving transport and sedimentation within these systems when tidally influenced. To provide insight we combine sedimentological observations with flux analyses for a series of tidal off-river waterbodies along the Lower Connecticut River spanning the river''s entire 100km tidal reach. Sedimentation rates exhibit a clear seaward increase with growing tidal influence, and are an order of magnitude higher than accumulation rates obtained previously from neighboring marsh and subtidal environments. A simplified mass balance can relate time-series measurements of water level and suspended sediment concentration to observed trends in sedimentation, and support flood-dominated asymmetry in tidal sediment flux (i.e. tidal pumping) as the primary mechanism for enhanced trapping. Relatively steady rates of deposition are observed in off-river waterbodies over the last century, with little evidence of deposition dominated by extreme events. Suspended sediment concentrations rise significantly in the main tidal river with increasing river discharge, while tidal range is damped with rising freshwater flow. The net result is an optimal freshwater discharge for maximizing the tidal pumping of sediment from the main river into tidal off-river waterbodies, with more routine discharge events largely responsible for driving long-term trends in deposition. A sudden shift in lithology towards more inorganic, fluvial derived sediment is commonly observed towards the end of the 19th century, along with over an order of magnitude increase in the rate of deposition. The timing of the onset of rapid infilling occurs contemporaneous with the documented creation and/or deepening of tidal tie-channels, followed shortly after by a rapid rise in heavy metal concentrations related to industrial activity along the river. Results point to the creation and routine maintenance of tidal inlets increasing the connectivity of off-river waterbodies to the main tidal river in recent centuries, and enhanced sediment trapping along the floodplain at the most favorable time for capturing legacy contaminants introduced during the industrial era. [Copyright &y& Elsevier]

Abstract: In order to assess ecological values of Lower Rhine and Meuse floodplain habitats we studied the spatial and seasonal variation in diversity, species assemblages and feeding traits of caddisfly larvae in water bodies over the lateral connectivity gradient: eupotamon: main and secondary channels; parapotamon: channels connected permanently with the main channel only at their downstream ends; plesiopotamon: disconnected channels close to the main channel; paleopotamon: abandoned meanders at a greater distance from the main channel. Spatial variety was studied by analyzing the summer species composition in 70 Lower Rhine and Meuse water bodies which were categorized in connectivity habitats, whereas seasonal variety was studied in Lower Rhine water bodies along a connectivity gradient by monthly sampling over a whole year. Physico-chemical data and environmental parameters were recorded for each water body during sampling. Diversity and species assemblages of caddisfly larvae varied in relation to connectivity, macrophyte diversity and abundance and stream velocity. A comparison with historical records and species lists from less disturbed rivers showed that diversity in the main channel was very low. Caddisfly larvae species assemblages varied over the connectivity gradient. Lotic habitats (eupotamon) were separated from the lentic ones, and the well vegetated paleopotamon from the sparsely vegetated parapotamon and pleisopotamon habitats, indicating the overall importance of vegetation and current velocity for the species assemblages. Hydropsychidae have been found in the eupotamon exclusively, whereas Limnephilidae, Hydroptilidae and Polycentropodidae have been found predominantly in the paleopotamon water bodies. Leptoceridae were found in all floodplain water body categories. A similar pattern of distribution of families along the lateral connectivity gradient was found in more natural rivers. Caddisfly larvae species feeding traits showed a clear differentiation over the lateral connectivity gradient with filter-feeders and scrapers most important in the eupotamon and parapotamon, and shredders, piercers and predators most dominant in the paleopotamon habitats, indicating the importance of nutritional resources in relation to hydrological connectivity for the structure and functioning of caddisfly larvae species assemblages. The analysis of the species feeding traits allows generalizations towards the entire aquatic community and general prognoses for other floodplain ecosystems. [Copyright &y& Elsevier]

Abstract: One objective of the European Union (EU)''s Water Framework Directive (WFD: Directive 2000/60/EC) is for all European surface waters to achieve ‘good status’ by 2015. In support of this objective, the EU has facilitated an intercalibration exercise to ensure harmonized definitions of the status of water bodies, reflecting the deviation of their properties (mainly biotic assemblages) from a minimally disturbed state, termed the “reference condition”. One of the major challenges of the WFD has been to find common approaches for defining reference conditions and to define the level of anthropogenic intervention allowed in reference sites. In this paper we describe how river reference sites were selected in the Central-Baltic region of Europe. A list of pressure criteria was provided and 14 Member States (MSs) categorized each criterion according to the method (i.e. measured, field inspection, etc.) used for reference site screening. Additionally, reference land-use and water-chemistry thresholds were agreed among countries in order to base reference site selection on objective criteria. For land-use criteria, a reference threshold and a rejection threshold were established. Sites with all criteria below the reference threshold were considered to be reference sites; sites having most criteria below the reference threshold and only some parameters between the reference and rejection threshold were “possible reference sites”. These sites were retained only after carefully checking the cumulative effects of the pressures using local expertise, and a posteriori water-chemistry evaluation was necessary. In general, the most widespread method for defining a reference site was the measurement of pressures, followed by field inspections and expert judgment. However, some major pressures (e.g. hydromorphological alteration) were evaluated in a number of different ways (e.g. measured, field inspection, expert judgment). Our meta-analyses reveal a need to reinforce standardization in the application of pressure criteria by Member States. The pressure criteria identified in this exercise should be refined and tested with biological data to help in the further validation of minimally disturbed sites (i.e. the WFD “reference condition”) and to provide a firm foundation for ecological status assessment. This in turn would ensure that there is pan-European comparability when evaluating the achievement of environmental objectives. [Copyright &y& Elsevier]

Abstract: The polycyclic synthetic musks (PCMs) such as galaxolide (HHCB), tonalide (AHTN) and celestolide (ABDI) are important ingredients in fragrances for consumer products because of their typical musky scent. In EU, PCMs are classified as HPVC (High Production Volume Chemicals). Furthermore, it has been recognized that these substances are only partially degraded in domestic sewers. For both reasons these chemicals are considered ubiquitous contaminants of aquatic systems. Monitoring data are available for the Northern region of the EU, but it is not known whether they are also representative for the Southern EU countries. The lack of data upon the environmental exposure in Southern EU can be significant, since use patterns and volumes differ from country to country. This is particularly true for Italy that has the largest detergent consumption per capita in EU. Due to this, the objective of the present study was to investigate the occurrence of selected PCMs in the Molgora River (Lombardia region, Italy). To our knowledge it represents the first overview of PCM occurrence in the Italian water bodies. Water samples were collected seasonally in seven sampling stations located before and after the 3 sewage treatment plants present along the river, which serve about 300,000 inhabitants. The spatial and temporal profiles of contamination are described. A comparison of the results with existing monitoring data of other European regions indicated a significant higher level of PCM pollution of the Molgora River and the need to extend the monitoring campaigns to other Italian water bodies, in order to achieve a better knowledge of the levels of PCM contamination in this country. [Copyright &y& Elsevier]

Abstract: Large-scale restoration of streams and rivers is a mandatory prerequisite for the implementation of the European Water Framework Directive (WFD) to reach good ecological status of water bodies. This contribution analyzes the success of the largest river restoration in Germany at the Upper Main. Sections with a length of more than 18km were restored between 1990 and 2008, including re-connection of former oxbow-lakes, multiple-channelling, and establishment of wide riparian buffer zones. Measuring the success of restoration by means of a multimetric assessment system, we found a clear success of restoration indicated by the status of hydromorphology and by the biological parameters, including macroinvertebrates, fishes, and macrophytes. Unlike non-restored reaches, the restored reaches attained a good ecological status. As such, the restoration of the Upper Main is shown to be a pilot project for the implementation of the WFD on a large scale. [Copyright &y& Elsevier]

Abstract: We developed an index (MESH –Macroinvertebrates in Estonia: Score of Hydromorphology) to assess hydromorphological quality of Estonian surface waters based on macroinvertebrate taxonomic composition. The MESH is an average score based on the affinities of selected indicator taxa to flow velocity and bottom type. As both parameters were highly correlated (r =0.65) indicator response to both parameters were combined. The list of MESH indicators includes 394 freshwater macroinvertebrate taxa derived from 3282 samples collected from rivers and lakes during 1985–2009. The indicators were selected out of 690 taxa, by applying the information-theoretical Kullback–Leibler divergence. The individual scores of macroinvertebrates range from 0 to 3, the higher scores indicating faster flow and/or solid bottom substrate. For standing waters, flow velocity was always considered zero. Among the reference waterbodies, mean MESH was the highest for small streams followed by middle streams, large streams, and lakes. In lakes with medium water hardness (the prevailing type in Estonia), the MESH decreased gradually from stony to muddy bottom. The highest MESH values for standing waters were observed in the stony surf zone of very large lakes (area>100km2). The lowest values occurred for small lakes with exceptional hydrochemical characteristics (soft- and darkwater, and calcareous types). Similarly, MESH indicated stream degradation by damming. Mean MESH in reservoirs with a muddy bottom was significantly lower than in reservoirs with a hard bottom, or in unregulated stream sections. [Copyright &y& Elsevier]

Abstract: Perfluorinated compounds (PFCs) were measured in 10 Washington State rivers and 4 wastewater treatment plants (WWTPs) under periods of low and high flows to investigate the relative importance of point and non-point sources to rivers. PFCs were detected in all samples with summed values ranging from 1.11 to 74.9ng/L in surface waters and 62.3–418ng/L in WWTP effluent. Concentrations in 6 of the 10 rivers exhibited a positive relationship with flow, indicating runoff as a contributing source, with PFC loads greatest at all 10 waterbodies during high flows. Perfluoroheptanoic acid:perfluorooctanoic acid homologue ratios suggest atmospheric contributions to the waterbodies are important throughout the year. Principal component analysis (PCA) indicated distinct homologue profiles for high flow, low flow, and effluent samples. The PCA demonstrates that during the spring when flows and loads are at their greatest; WWTP discharges are not the primary sources of PFCs to the river systems. Taken together, the evidence provided signifies non-point inputs are a major pathway for PFCs to surface waters in Washington State. [Copyright &y& Elsevier]

Abstract: The objective of this study was to determine the mean concentration (per litre) of Cryptosporidium oocysts and Giardia cysts in recreational river areas (n = 28), drinking water treatments plants (DWTPs; n = 52) and wastewater treatment plants (WWTPs; n = 50) in Galicia (NW Spain). Water samples from rivers and from the influent (50–100 l) and the treated effluent (100 l) of the water plants were filtered using Filta-Max filters (IDEXX Laboratories, Inc., Westbrook, ME, USA). A total of 232 samples were processed and the (oo)cysts were concentrated, clarified by IMS and then detected by IFAT. The viability was determined by applying fluorogenic vital dye (PI). In the recreational areas, infective forms of Cryptosporidium and Giardia were detected in 16 (57.1%; 1–60 oocysts per litre) and 17 (60.7%; 1–160 cysts per litre) samples, respectively. In the water flowing into the water treatment plants, oocysts were detected in 21 DWTPs (40.4%; 1–13 oocysts per litre) and cysts were observed in 22 DWTPs (42.3%; 1–7 cysts per litre). In the effluents from the treatment plants, Cryptosporidium oocysts and Giardia cysts were identified in 17 DWTPs (32.7%; 1–4 oocysts per litre) and in 19 DWTPs (36.5%; 1–5 cysts per litre), respectively. The highest concentrations of (oo)cysts were found in the WWTPs; specifically, oocysts were detected in 29 (58.0%; 1–80 oocysts per litre) and cysts in 49 (98.0%; 2–14.400 cysts per litre) WWTP effluents. Cryptosporidium and Giardia were detected in 32 (64.0%; 1–120 oocysts per litre) and 48 (96.0%; 2–6.000 cysts per litre) WWTP effluents, respectively. The percentage viability of the (oo)cysts ranged between 90.0% and 95.0%. In all samples analysed. Moreover, it was found that the effluents from coastal WWTPs were discharged directly into the sea, while inland WWTPs were discharged directly into rivers. The concentrations of both enteropathogens detected in effluents from WWTPs therefore represent a significant risk to human and animal health. These results demonstrate the wide distribution of Cryptosporidium and Giardia in the environment, the ineffectiveness of treatments in DWTPs and WWTPs in reducing/inactivating both protozoa and the need to monitor the presence, viability and infectivity of Cryptosporidium and Giardia in water bodies. In conclusion, the findings suggest the need for better monitoring of water quality and identification of sources of contamination. [Copyright &y& Elsevier]

Abstract: High acidity caused by geochemical processes and intensive land use of acid sulphate (AS) soils have continuously degraded the status of water bodies in Western Finland. Despite this, research on the long-term pattern and dynamics of acidification in rivers affected by acid sulphate soils is scarce. This study examined changes in alkalinity and pH value during the period 1913–2007 in nine large Finnish rivers discharging into the Gulf of Bothnia. In addition, patterns of CODMn and colour were analysed during the period 1961–2007. Relationships between pH, alkalinity, CODMn and colour and climate variables were also studied. In four rivers with no AS soil impact (Kokemäenjoki, Kemijoki, Iijoki and Oulujoki), critically low pH levels did not occur during the study period, whereas three rivers exposed to minor or moderate levels of runoff from AS soils (Lestijoki, Kalajoki, and Siikajoki) had all periods with critically low pH and alkalinity. The most severe acidity problems occurred in the rivers Kyrönjoki and Lapuanjoki, with extensive drainage of AS soils being the main reason for the low pH status. Maximum discharge was clearly related to the acidity status of many rivers during the autumn–winter runoff period, when a significant negative linear correlation was found between maximum discharge and minimum pH in the rivers affected by AS soils. There was also a more distinct relationship between maximum chemical oxygen demand (CODMn) and minimum pH in autumn runoff than in spring. CODMn levels significantly increased with increasing discharge in the rivers with no or minor AS soil impact. Climate change is predicted to increase river flow in general and winter discharge in particular, and therefore the acidity problems in affected rivers may increase in a future climate. [ABSTRACT FROM AUTHOR]

Abstract: A total of 346 sets of bed-load data obtained from the Kinta River, Pari River, Kerayong River and Langat River were analyzed using four common bed-load equations. These assessments, based on the median sediment size (d 50), show that the existing equations were unable to predict the measured bed load accurately. All existing equations over-predicted the measured values, and none of the existing bed-load equations gave satisfactory performance when tested on local river data. Therefore, the present study applies a new soft computing technique, i.e. an adaptive neuro-fuzzy inference system (ANFIS), to better predict measured bed-load data. Validation of the developed network (ANFIS) was performed using a new set of bed-load data collected at Kulim River. The results show that the recommended network can more accurately predict the measured bed-load data when compared to an equation based on a regression method. [Copyright &y& Elsevier]

• We implemented an algorithm to mine data from the French River monitoring database. • Patterns produced were successions of chemical events preceding a biological index. • Events were 14 pressure categories and 5 indices in the 5 statuses from high to bad. • Patterns on 2 years could hold up 20 events before a biological status, often worse. • Bad indices were preceded either by chronic multi-pressures or a single bad event. We have implemented a specific data mining process to explore the relationship between biological indices and physico-chemical pressures in rivers. Data were collected in the framework of the French National monitoring network set up to assess the ecological status of rivers under the European Water Framework Directive (WFD). Chemical parameters and biological indices were collected regularly from 1.781 locations in metropolitan France from 2007 to 2013. The sequential pattern mining process generates closed partially ordered patterns representing a succession of physico-chemical events that precede a given biological index in a given status, validated using a subset of data. This paper focuses on the patterns and their occurrence. We showed that biological statuses depend on these temporal successions of alterations and not only on the last alterations. The physico-chemical statuses of water bodies usually appeared to be higher than their biological statuses, suggesting synergism between toxicants and/or an additive impact of other stressors related to hydromorphology or hydrology. Patterns found in the highest biological status for the biological indices based on macroinvertebrates, diatoms, macrophytes or fish, were characterised by the constancy of a high physico-chemical status over time. By contrast, before indices based on macroinvertebrates and macrophytes, two types of patterns were observed for bad biological status: (1) a chronic multi-pressure pattern, in which pressure categories such as nitrates, pesticides and other organic hydrocarbons, in moderate, poor or bad status, repeated themselves several times over time, or (2) a single occurrence of a degraded pressure category, such as one moderate nitrogen, excluding nitrate, or one poor oxidizable organic matter, among other pressure categories in good status. Extracting such patterns is a promising solution both to disentangle the effects of the different stressors on water quality, and to identify the key temporal sequences among them in a context of multi-stress conditions, which is a challenge currently facing the WFD. [ABSTRACT FROM AUTHOR]

Abstract: Concentrations and fluxes of unresolved complex mixture of hydrocarbons (UCM) and polycyclic aromatic hydrocarbons (PAHs) were analyzed for two 210Pb dated sediment cores from the Pearl River Estuary (PRE) and the adjacent northern South China Sea (NSCS). Compound-specific stable carbon isotopic compositions of individual n-alkanes were also measured for identification of the hydrocarbon sources. The historical records of PAHs in the NSCS reflected the economic development in the Pearl River Delta during the 20th century. PAHs in the NSCS predominantly derive from combustion of coal and biomass, whereas PAHs in the PRE are a mixture of petrogenic and pyrogenic in origins. The isotopic profiles reveal that the petrogenic hydrocarbons in the PRE originate predominantly from local spillage/leakage of lube oil and crude oils. The accumulation rates of pyrogenic PAHs have significantly increased, whereas UCM accumulation has slightly declined in the NSCS in the recent three decades. [Copyright &y& Elsevier]

Abstract: Concentrations, spatial distribution and sources of 17 polycyclic aromatic hydrocarbons (PAHs) and methylnaphthalene were investigated in surface sediments of rivers and an estuary in Shanghai, China. Total PAH concentrations, excluding perylene, ranged from 107 to 1707ng/g-dw. Sedimentary PAH concentrations of the Huangpu River were higher than those of the Yangtze Estuary. The concentration of the Suzhou River was close to the average concentration of the Huangpu River. PAHs source analysis suggested that, in the Yangtze Estuary, PAHs at locations far away from cities were mainly from petrogenic sources. At other locations, both petrogenic and pyrogenic inputs were significant. In the Huangpu and Suzhou Rivers, pyrogenic input outweighed other sources. The pyrogenic PAHs in the upper reaches of the Huangpu River were mainly from the incomplete combustion of grass, wood and coal, and those in the middle and lower reaches were from vehicle and vessel exhaust. [Copyright &y& Elsevier]

Abstract: Land use and in-stream transformation exert great influence on concentrations and loads of phosphorus (P) in rivers. We aimed to display differences in the courses of total P (TP) and soluble reactive P (SRP) concentrations and loads in six medium-sized to large rivers in the central region of Germany, and to identify the reasons for different long-term trends. Therefore, we applied multivariate statistics to 10-year-time series (1994–2003) of TP, SRP, discharge (Q), water temperature (T), pH, dissolved organic carbon (DOC), total organic carbon (TOC), dissolved oxygen (DO), total iron (Fe), and total manganese (Mn). Statistical results were related to land use in the catchments of the rivers. TP concentrations ranged between 0.02 and 0.78mgl−1, and SRP concentrations ranged between 0.01 and 0.44mgl−1. Q correlated negatively with TP and SRP concentrations over the entire year. Furthermore, Fe correlated significantly and positively to TP and SRP and therefore, ferric hydroxides likely were the major P sorption sites. DOC showed significant positive correlation to SRP particularly in spring, indicating manure exposure in early spring as a major source of both, DOC and SRP. Significant negative correlations between DO and SRP in summer hint at internal P loading in rivers or in flushed lakes. Different forms of land use were the reasons of enhanced or retarded recovering from previous increases in P concentrations. High portions of arable land within some of the catchments impeded the process of decreases since 1996 because of remaining high-diffuse emissions from fertilized soils. Agricultural practices, exposing fertilizer to soils within the river catchments and high Q in early spring caused high TP and SRP loads to downstream systems, and evoked risks for downstream river reaches. [Copyright &y& Elsevier]

Abstract: River meanders are natural features on the surface of Earth that present some degree of regularity of form. They range from being highly dynamic to being stable under present conditions. Conventional theory is that meanders develop to an equilibrium form which is related to discharge and sediment load. Other research has demonstrated that many highly active meanders exhibit a continuous evolution over time and a non-linearity in rate of development. Ideas of autogenesis and of self-organised criticality as being an explanation of some meander changes have been proposed. In this paper data from rivers around the world are examined for further evidence of autogenic, self-organised or non-linear behaviour through analysis of change in sinuosity over time for reaches and change in individual bend form, particularly bend curvature and bend elongation. Some examples do exhibit trends of increasing sinuosity over time and a few show limits from which large decreases occur. Several case studies show non-linearity of behaviour and increasing complexity of form. Other case studies, however, do not exhibit such trends. Phase space plots are used to help uncover emergent behaviour but show a variety of patterns. The example of a reach in which multiple cut-offs occurred is analysed for mechanisms of self-organisation of the planform and in the pool-riffle pattern. Riffles are more closely spaced and also more transient in the more rapidly changing and higher sinuosity parts of the channel. Hypothetical trajectories of different meander behaviour, including for bedrock meanders, are plotted but the challenge remains to uncover the conditions for occurrence and for divergence of tendencies to stability and instability. Identification of attractors and phase space of behaviour of different meandering systems offer the potential for application to sustainable channel management. [Copyright &y& Elsevier]

Abstract: Processing of organic matter in tidal estuaries modifies its transfer from the river to the sea. We examined the distribution and the elemental and isotopic composition of organic matter in nine tidal estuaries along the Atlantic coast of Europe (Elbe, Ems, Thames, Rhine, Scheldt, Loire, Gironde, Douro and Sado). Short-residence time estuaries such as the Douro and Rhine estuaries have low suspended matter (SPM) contents with variable organic carbon (OC) concentrations, but rather uniform δ 15N values and C/N ratios. Carbon isotope ratios vary from −20 to −22‰ in the marine end-member to −26 to −30‰ in the river end-member with conservative mixing in between. Tidal-dominated estuaries have high SPM contents, rather uniform OC contents and C/N ratios, and uniform and intermediate δ 13C values (−24 to −26‰). Organic matter in these intermediate to long residence time estuaries is extensively modified such that δ 15N values may show enrichments up to 20‰ due to (heterotrophic) processing. Pools of dissolved and particulate organic matter appear to be involved in dynamic exchange reactions with their partitioning mainly governed by SPM concentration. The interaction of tidally induced cycles of deposition and erosion with this repartitioning of organic matter between dissolved and particulate pools due to changes in SPM concentration can be viewed as a chemical reactor with optimal solid–liquid exchange. As a consequence, riverine organic matter is extensively modified in tidal estuaries before it is transferred to the sea. [Copyright &y& Elsevier]

Abstract: Organic carbon and total nitrogen as well as stable carbon (δ 13Corg) and nitrogen (δ 15N) isotopic ratios were determined on suspended matter, settling particles and bottom sediments collected from the Changjiang (Yangtze River) Estuary during the summer flood period in 2001. From the results, three sources of suspended matter, riverine, deltaic (salt marshes) and marine (East China Sea — ECS) were distinguished. The resuspended particulate organic matter contents in the water column increased with the amount of total suspended matter (TSM) indicating the role of dispersive and/or turbulent mixing and its control over the high TSM concentration in the Changjiang Estuary. This and an active resuspension/deposition in the estuary determine the nature of organic matter in suspended materials reaching the East China Sea. [Copyright &y& Elsevier]

The Bagmati River in Kathmandu Valley (Nepal) receives seven major polluted tributaries. Discharges of wastewaters containing degradable organics and nutrients have resulted in decrease in DO concentrations along its course. A one-dimensional stream water quality model QUAL2Kw was calibrated and confirmed using the data in 2000. The model represented the field data quite well with some exceptions. The sensitivity analysis showed the model was highly sensitive for water depth and moderate to point sources flow, TN, CBOD and nitrification rate. The model was applied to simulate various water quality management strategies during critical period to maintain the targeted water quality criteria (minimum DO at or above 4mg/L; maximum CBOD, TN, TP and temperature at or below 3, 2. 5 and 0. 1mg/L and 20°C, respectively, and pH range 6. 5–8. 5) considering: (i) pollution loads modification (ii) flow augmentation and (iii) local oxygenation. Except for CBOD, all the stated quality limits were achieved with 30mg/L CBOD, 5mg/L TN, 0. 25mg/L TP limits at point sources and with flow augmentation of 1m3/s and local oxygenations at three critical locations. The simulated maximum CBOD was 8. 5mg/L. It was considered reasonable for the developing country, Nepal, as the European water quality with maximum CBDO of 3mg/L is difficult to achieve. The results showed the local oxygenation is effective to maintain minimum DO concentrations in the river. The combination of wastewater modification, flow augmentation and local oxygenation is suitable to maintain the acceptable limits of water quality criteria. [Copyright &y& Elsevier]

The ecological consequences of river inflows, usually carrying large amounts of nutrients, will be different depending on whether it penetrates to the hypolimnion, inserts in the metalimnion or remains on the surface. For plunging rivers, the intrusion depth is controlled by the river-reservoir density difference prior to the plunge point together with mixing processes between ambient and inflowing water, which occur both in the region of the plunge and after the flow has assumed the form of a density current. In contrast with the processes of entrainment into density currents, which have been extensively studied, entrainment and mixing within the plunge zone has received less attention in the physical limnology literature. The existing literature fails to identify adequate parameterizations of this phenomenon, while exhibiting a large variability in the initial mixing rate, measured both in the laboratory and in the field. This work examines the consequences (in terms of uncertainty) that our lack of knowledge of parameters describing river-reservoir mixing in 1-D transport models has on the estimates of river nutrient loads into the euphotic zone of a reservoir, where nutrients are readily available for phytoplankton growth. [Copyright &y& Elsevier]

Abstract: The Cambrian Araba Formation exposed in Gabal El Zeit and in the Sinai Peninsula unconformably overlies Precambrian basement rocks, and is in turn overlain unconformably by the Ordovician Naqus formation. The Araba Formation has been subdivided into three informal lithologic units: lower, middle and upper, from field observations. Seven sedimentary facies assignable to three facies associations (fluvial, tidal and coastal to open marine) are recognized within the Araba Formation. The lower unit comprises two main facies: matrix-supported conglomerate (facies-A) in the south (Gabal Araba and Wadi Feiran) and interbeds of granulestone and sandstone (facies-B) in the north (Gabal Dhalal and Taba) deposited in fluvial conditions. The middle unit includes four facies: cross-bedded sandstone (facies-C), thin laminated sandstone (facies-D), burrowed-massive sandstone (facies-E) and rhythmically bedded sandstone–mudstone (facies-F) deposited mainly under tidal conditions in the coastal zone. The upper unit consists mainly of interbeds of burrowed mudstone-siltstone, with Skolithos, probably deposited in open marine environment. The sequence records the southward transgression of the Tethys Ocean over a horst and graben system developed in the late Precambrian on the northern margin of the Arabo-Nubian continent. [Copyright &y& Elsevier]

Abstract: The year-to-year variations in the water exchange ratio and the tidal amplitude in Ariake Bay, Japan, were investigated using observed river discharge, salinity and tide gauge data. The water exchange ratio between Ariake Bay and the open ocean has increased from the early to the late 1990s due to the intensification of the estuarine circulation in the bay. The intensification of the estuarine circulation in Ariake Bay has resulted from a decrease in the tidal amplitude there. [Copyright &y& Elsevier]

Abstract: The Arabian-Nubian-Shield (ANS) is composed of a number of island arcs together with fragments of oceanic lithospere and minor continental terranes. The terranes collided with each other until c. 600 Ma ago. Subsequently, they were accreted onto West Gondwana, west of the present River Nile. Apart from widespread ophiolite nappe emplacement, collisional deformation and related lithospheric thickening appear to be relatively weak. Early post-collisional structures comprise not only extensional features such as fault-bounded (molasse) basins and metamorphic core complexes, but also major wrench fault systems, and thrusts and folds. The Hammamat Group was deposited in fault-bounded basins, which formed due to N-S to NW-SE directed extension. Hammamat Group sediments were intruded by late orogenic granites, dated as c. 595 Ma old. A NNW-SSE-oriented compression prevailed after the deposition of the Hammamat Sediments. This is documented by the presence of NW-verging folds and SE-dipping thrusts that were refolded and thrusted in the same direction. Restoration of a NNW-SSE- oriented balanced section across Wadi Queih indicates more than 25% of shortening. Transpressional wrenching related to the Najd Fault System followed this stage. The wrenching produced NW-SE sinistral faults associated with positive flower structures that comprise NE-verging folds and SW-dipping thrusts. Section restoration across these late structures indicates 15 17% shortening in the NE-SW direction. At a regional scale, the two post-Hammamat compressional phases produced an interference pattern with domes and basins. It can be shown that the Najd Fault System splays into a horsetail structure in the Wadi Queih area and loses displacement towards N and NW. The present study shows a distinct space and time relationship between deposition of Hammamat Group/late-Pan-African clastic sediments and late stages of Najd Fault wrench faulting: Hammamat deposition is followed by two episodes of compression, with the second episode being related to Najd Fault transpression. Therefore, the Hammamat sediments do not represent the latest tectonic feature of the Pan-African orogeny in the ANS. The latest orogenic episodes were the two successive phases of compression and transpression, respectively. It is speculated that extension during (Hammamat) basin formation was sufficiently effective to reduce the thickness of the orogenic lithosphere until it became gravitationally stable, and incapable of further gravitational deformation. [Copyright &y& Elsevier]

Abstract: The Water Framework Directive requires a river classification based on environmental variables (a typology) to be created as a structure for reporting ecological status. A single permutation procedure, utilising the same variables repeatedly but with different categorical divisions, enabled both the choice of variables and the boundary divisions for these variables to be optimised simultaneously in the development of the typology. This, in addition to a data set which appropriately combined different biological elements, enabled a typology to be developed which was far more effective than a System A, CCA-derived or expert opinion-based typology in segregating communities. This optimal typology could be used to improve the performance of ecological quality assessment methods. [Copyright &y& Elsevier]

Abstract: New field observations and sedimentological analyses of the dinosaur-bearing Upper Cretaceous Iren Dabasu Formation in the Iren Nor region of Inner Mongolia (People''s Republic of China) have led to a better understanding of its palaeoenvironment. The fluvial deposits represent a braided river that, due to the large amount of fines, does not fit the classical model for braided rivers. The study area is divided into two parts: in the northern part, sediments of the main channel belt of the ancient braided river system are exposed along a dry river valley on the northern edge of the Iren Nor salt lake, while in the southern part, comprising all other studied exposures, different facies of the ancient floodplain are represented, including minor channels, temporary ponds, and palaeosols. The difference between the northern and southern parts is also reflected in the fossil content; only the southern exposures have yielded dinosaur remains. The ancient braided river had a broad, vegetated floodplain populated by a diverse dinosaur fauna. Four species of charophytes are described and illustrated from the Iren Nor site, together with eight species of ostracods, one of which (Cypridea irennorensis sp. nov.) is new. Contrary to the vertebrate data, both groups of microfossils indicate a latest Cretaceous age (Campanian–Maastrichtian) for the Iren Dabasu Formation, and suggest a possible correlation with the Nemegt Formation, which would allow the age estimation to be refined to latest Campanian–Early Maastrichtian. [Copyright &y& Elsevier]

Abstract: A bed with several serpulid build-ups is described from a Holocene outcrop at Quequén Grande River, Argentina. The tubes were dated at 6360±80 years BP. The morphology and size parameters of the serpulids were compared to different species of serpulids from the literature and tubes of Ficopomatus enigmaticus, Hydroides dianthus and Hydroides plateni from Argentinean waters. In spite of the fact that today only F. enigmaticus constructs build-ups in Argentine brackish environments, the fossil tubes could not be assigned to this species, but instead, they show close similarities to those of the two species of Hydroides. The sequence is interpreted as having originated from a brackish environment. At present, neither the endemic H. plateni nor any other species of Hydroides construct build-ups in brackish waters of southern South America. This suggests, that suitable environments to construct aggregates were more widespread than today or that the invasion of F. enigmaticus replaced Hydroides; alternatively various causes may have acted jointly. [Copyright &y& Elsevier]

Abstract: The geographical setting of the Jiulong River estuary determines that the estuary receives wastes from both riverine input and adjacent urban sewage. However, the dominant nitrogen (N) source remains unclear. A nutrient mass-balance model and a preliminary LOICZ (Land–Ocean Interactions in the Coastal Zone) biogeochemical model were linked to evaluate agricultural N contributions from the Jiulong River catchment to the estuary and coastal water. Results showed that agricultural N surplus was the largest N source in the catchment, contributing 60.87% of the total Nitrogen (N) and 68.63% of the dissolved inorganic nitrogen (DIN). Household wastes and other sources followed. Riverine DIN fluxes were about 20.3% of exportable DIN and 14.4% of exportable total N, but approximately 9.7% of DIN inputs, and 7.3% of total N inputs to the Jiulong River catchment. The model system clearly showed that agricultural and anthropogenic activities in the catchment were the major N sources of the estuary and coastal water, and riverine N fluxes from these sources substantially impacted the estuary and coastal water quality and biogeochemical processes. [Copyright &y& Elsevier]

Abstract: Environmental monitoring by means of biomarker parameters assessed in different species is a useful tool. It has the advantage of providing a quantitative response as well as valuable information of ecological relevance on the chronic adverse effects caused by water pollution. The aim of this study was to assess the response of biochemical and physiological parameters of Cnesterodon decemmaculatus, a native teleost, simultaneously caught in two sites of Reconquista river, a highly polluted peri-urban river. This study compared the measured parameters with that of specimens of the same species captured in an unpolluted body water, and correlated the detected changes with the physicochemical profile of the water at each site. A comparison was made of selected parameters of gill, brain and liver and of somatic indices of fish collected from polluted and reference sites. The main parameters whose changes allowed to discriminate between sampling sites were gill (Na+,K+)-ATPase, brain acetylcholinesterase (AChE) and liver aminotransaminases activities; tissues’ protein content and liver somatic index (LSI) were also sensitive biomarkers in brain and liver, respectively. The results showed that the response of the measured biomarkers allowed for the differentiation of sampling sites according to their water quality and confirmed that Cnesterodon decemmaculatus may be a useful test organism for the biomonitoring of freshwater environments. In addition, the simultaneous measurement of the physicochemical parameters of the water samples showed a good correspondence between the biomarkers responses and the environmental chemical stress conditions. [Copyright &y& Elsevier]

Caddisflies are a well represented group with high species diversity in Mediterranean climate rivers. Although they are widely used in water quality assessment, little is known of the ecological profiles of families or species. We present a simple score for ecological profiles which measures intolerance to water quality. The ecological profiles of caddisflies are diverse and the degree of tolerance at the family level is related to species diversity and the tolerance of individual species to water quality. Comparisons with the scores used in the biotic index IBMWP show general agreement between the degree of intolerance of a family and its score in the IBMWP, with few exceptions. Studies on tolerance are required to elucidate the autecology of taxa, and to develop biological indices, especially in areas with high species diversity. [Copyright &y& Elsevier]

A systematic survey of dissolved uranium activity was carried out in the Seine and the Marne over one year. A small watershed, the Grand Morin, included in the Seine one, was also investigated from stream to medium-sized rivers. The Melarchez stream exhibits low but variable dissolved 238U levels (3.3±2.0 mBq l-1). Thereafter, uranium activities show a rapid increase to reach, from the Grand Morin River, a rather constant range (8–11 mBq l-1). On the Marne before the confluence with the Seine, dissolved 238U is nearly invariable (9.1±0.8 mBq l-1), for flow rates comprised between 60 and 423 m3 s-1. Dissolved 238U in the Seine corresponds to almost triple the global mean riverine uranium concentration. In the estuary of the Seine, uranium shows a gradual increase, resulting from conservative mixing of river with sea waters. [Copyright &y& Elsevier]

• Bacterioplankton structures differed between the Weihe River and its tributaries. • Geographical and environmental factors had different influences in two habitats. • Chlorophyll a emerged as the major determinant in the turbid Weihe River. The Weihe River is the largest tributary of the typically sediment-laden Yellow River in China. Assuming that high sediment concentrations may increase the turbidity of water bodies, and therefore affect riverine ecosystem, in which the bacterioplankton are crucial components and serve as important indicators of environmental and ecological status through their structure and response to the environment change, it is essential to deep understanding the bacterioplankton structure and influencing factors in turbid and clear river ecosystems. Here, high-throughput sequencing was used to analyze the differences in bacterioplankton structure and major determinants in the typically turbid Weihe River and its clear tributaries from the northern foot of the Qinling Mountains from October to November 2017 and April to May 2018. The results demonstrated that bacterioplankton communities shared similar dominant subcommunities in the Weihe River mainstem and its tributaries, mainly consisting of Proteobacteria and Bacteroidetes phyla and Flavobacterium and Acinetobacter genera. The Faith phylogenetic diversity (PD) index was significantly higher in the turbid mainstem than in the tributaries and was related to turbidity (Turb). Variation partitioning analysis (VPA) showed that geographical distance exhibited notable influences on the community composition in the mainstem; however, the communities in the tributaries had a much stronger response to local environmental factors. Bacteria exhibited a significant distance-decay relationship in the mainstem, whereas geographical distance was not correlated with community dissimilarities in the tributaries. Chlorophyll a emerged as the major determinant of the bacterioplankton structure in the turbid Weihe River, indicating the importance of phytoplankton-bacterioplankton relationships in the turbid river system. These results provide important insights into future research on microbial ecology, environmental monitoring and classified management in diverse river systems. [ABSTRACT FROM AUTHOR]

This work shows the potential of using photochemical modelling to assess the river-water ability to photodegrade agrochemicals on a geographic and temporal scale. The case of flowing water requires different data treatment compared to more stationary water bodies (e.g. , lakes), but it could allow for the identification of particularly vulnerable environments. Five pesticides were considered here, and the photodegradation rate followed the order bentazon > isoproturon > dimethomorph ∼ chlortoluron > atrazine. The modelled photodegradation kinetics was particularly fast in the river Po, which receives significant input of agricultural nitrate from groundwater and features higher steady-state [•OH] than most other rivers in the region. The fact that the Po eventually collects all river waters in Piedmont is positive, from the point of view of comprehensive photodegradation of pesticides. However, this paradoxical situation of agricultural pollution (nitrate) helping fight pollution from the same source (pesticides) has two important limitations: (i) when compared to the parent compounds, some intermediates deriving from •OH reactions are either more harmful (N-formyl derivatives of phenylureas), or about as harmful (desethyl atrazine); (ii) banned atrazine is no longer sprayed over fields during the plant growth season, but it reaches surface waters from legacy groundwater inputs. The latter are operational also during winter, when photochemistry is least active. Therefore, photochemistry might not ensure considerable attenuation of atrazine during wintertime. Overall, bentazon would be the safest among the studied pesticides because of fast degradation by direct photolysis, and of low ecotoxicological impact of its phototransformation intermediates. Image 1 • Bentazon photodegradation was the fastest among the studied pesticides. • Photodegradation of atrazine was the slowest among the studied pesticides. • The river Po showed higher concentrations of.•OH and CO 3 •− than the other rivers. • The Po collects all Piedmontese river waters, ensuring effective photodegradation. • There could be issues related to potential toxicity of.•OH reaction intermediates. [ABSTRACT FROM AUTHOR]

Spectrally-based retrieval of bathymetry is challenging in inland/coastal waters due to variations in factors other than water depth across a water body, including bottom type, optically significant constituents, water surface roughness, and others. Optimal band ratio analysis (OBRA) is the most widely used method to deal with these confounding effects to retrieve water depth. OBRA identifies the pair of bands that provides the highest accuracy among all possible pairs when using a log-transformed band ratio model. However, this approach fits a single ratio model to all training samples without fully accounting for the heterogeneity of the aforementioned complicating factors. To deal with this problem, we introduce a novel method called Sample-specific Multiple bAnd Ratio Technique for Satellite-Derived Bathymetry (SMART-SDB). The proposed SMART-SDB technique partitions the feature space of the spectral data and creates for every subspace a different band ratio model that performs better than the other models within that subspace. Bathymetry is then predicted based on the closest model/s in the feature space by performing a sample-specific k-nearest neighbor (K −NN) analysis. The depth estimates provided by the neighboring models are averaged with weights proportional to their inverse distance in the feature space. The proposed method can be used in both inland and coastal waters. Here, we thoroughly examine its effectiveness in the challenging and heterogenous environments of fluvial systems using a wide range of spectral data including radiative transfer simulations, an airborne hyperspectral image of the Snake River (USA), and a WorldView-3 satellite image of the Sarca River (Italy). The results of this study indicate a significant improvement in depth retrieval for estimations based on the SMART-SDB method relative to standard OBRA, either when a single model or multiple models are employed. • Partition-specific band ratios for improving bathymetry modeling. • Use of sample-specific multiple ratio models for depth estimation. • Proposed SMART-SDB outperformed the standard ratio model. [ABSTRACT FROM AUTHOR]

• Predictable river algal blooms by antecedent environmental conditions using GBM. • Nutrients are above eutrophication thresholds and not limiting factors in Han River. • Algal blooms in the Han River are significantly modulated by hydrologic conditions. River algal blooms have become a challenging environmental problem worldwide due to strong interference of human activities and megaprojects (e.g., big dams and large-scale water transfer projects). Previous studies on algal blooms were mainly focused on relatively static water bodies (i.e., lakes and reservoirs), but less on the large rivers. As the largest tributary of the Yangtze River of China and the main freshwater source of the South-to-North Water Diversion Project (SNWDP), the Han River has experienced frequent algal blooms in recent decades. Here we investigated the algal blooms during a decade (2003–2014) in the Han River by two gradient boosting machine (GBM) models with k -fold cross validation, which used explanatory variables from current 10-day (GBMc model) or previous 10-day period (GBMp model). Our results advocate the use of GBMp due to its higher accuracy (median Kappa = 0.9) and practical predictability (using antecedent observations) compared to GBMc. We also revealed that the algal blooms in the Han River were significantly modulated by antecedent water levels in the Han River and the Yangtze River and water level variation in the Han River, whereas the nutrient concentrations in the Han River were usually above thresholds and not limiting algal blooms. This machine-learning-based study potentially provides scientific guidance for preemptive warning and risk management of river algal blooms through comprehensive regulation of water levels during the dry season by making use of water conservancy measures in large rivers. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Precise delineation of river networks is important for accurate hydrological and flood modelling. Whilst remote sensing (RS) has showed great potential in monitoring hydrological changes over space and time, the existing RS-based methods extract river networks based on local morphologies and seldom take into account the overall hydrological connectivity of the rivers. The existing methods also commonly neglect the effect of seasonal variation of water surfaces and the existence of temporary water bodies, which deteriorate the precision of positioning river networks. To address these challenges, a new two-stage method is developed to E xtract spatiotemporal variation of water surfaces based on M ulti-temporal remote sensing I magery and D elineate connected river networks with improved accuracy (EMID method for short) using a path tracking technique. The EMID method delineates connected river networks using (a) multi-temporal imagery and a Random Forest model to synoptically map the location and extent of water surfaces under different hydrological conditions, and (b) an optimization algorithm to find the best river paths based on water-occurrence frequency. Four drainage basins with various river morphologies are considered to validate EMID. Comparing with alternative methods, the EMID method consistently produces river network results with improved accuracy in terms of stream location, river coverage and network connectivity. Unlabelled Image • A new two-stage RS-based method is proposed to extract connected rivers. • The new method performs well in maintaining river positional accuracy. • The method effectively reduces temporary water's interference. [ABSTRACT FROM AUTHOR]