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Through the practice of irrigation, surface water reservoirs (SWRs) contribute to the socio-economic development and food production activities of populations in Sub-Saharan Africa (SSA). However, they tend to dry up prematurely. One solution to circumvent these irrigation water shortages is to ensure their conjunctive use with groundwater. The objective of this study is to better understand the contribution of SWRs to groundwater recharge and to determine if groundwater may be considered as a complementary local resource for irrigation. The study was carried out on two watersheds in Burkina Faso, Kierma and Mogtedo. The spatiotemporal analysis of piezometric and SWRs level records coupled with physico-chemical analyses of water was used to characterize exchanges between SWRs and groundwater. The regional groundwater recharge at the scale of the watersheds was assessed. At the SWRs scale, a water balance methodology was developed and used to estimate focused recharge. The results show that SWRs interact almost continuously with groundwater and contribute focused recharge. The magnitude of this recharge is a function of the geological context and the sediment texture of the SWRs. It is estimated at 5 mm/day in Kierma and 4 mm/day in Mogtédo. These values are higher than the natural recharge estimated at 0.2 mm/day in Kierma and 0.1 mm/day in Mogtédo. Additionally, the values of hydraulic conductivity are between 0.01 and 2 m/day in Kierma and between 1 × 10−4 and 0.2 m/day in Mogtédo. These conductivities could allow pumping in large-diameter hand-dug wells with a significant yield between 0.5 and 120 m3/day in Kierma and between 0 and 10 m3/day in Mogtédo to palliate the early drying up of the SWRs.

The distinction between turbidites, contourites and hemipelagites in modern and ancient deep-water systems has long been a matter of controversy. This is partly because the processes themselves show a degree of overlap as part of a continuum, so that the deposit characteristics also overlap. In addition, the three facies types commonly occur within interbedded sequences of continental margin deposits. The nature of these end-member processes and their physical parameters are becoming much better known and are summarised here briefly. Good progress has also been made over the past decade in recognising differences between end-member facies in terms of their sedimentary structures, facies sequences, ichnofacies, sediment textures, composition and microfabric. These characteristics are summarised here in terms of standard facies models and the variations from these models that are typically encountered in natural systems. Nevertheless, it must be acknowledged that clear distinction is not always possible on the basis of sedimentary characteristics alone, and that uncertainties should be highlighted in any interpretation. A three-scale approach to distinction for all deep-water facies types should be attempted wherever possible, including large-scale (oceanographic and tectonic setting), regional-scale (architecture and association) and small-scale (sediment facies) observations.

Bulk (whole sample) magnetic properties of three‐hundred‐sixty‐two samples from five North Atlantic Ocean sediment cores are compared to the magnetic properties of five grain‐size fractions separated from the same samples. The relative abundance and magnetic properties of the size fractions are highly variable both within a core and among locations. Clay often dominates the sediment texture but contains low concentrations of magnetic minerals whose composition varies little from site‐to‐site. Silts are more magnetically variable, contain much higher ferrimagnetic mineral concentrations, are magnetically coarser than clays, and retain strong imprints of their geological source. The medium silt size fraction is a strong source discriminator, dictates bulk sediment magnetic property variations, and helps characterize a new magnetic source fingerprint for Laurentia. In contrast, bulk sediment magnetic properties are an average of the properties of the individual fractions weighted by the magnetic concentration of those fractions and their abundance. Bulk sample averaging is observed across magnetic methods, which mutes individual grain‐size property variations that convolve source signatures and transport driven texture variations. Grain‐size‐specific approaches can help to restrict textural variance to isolate source signatures, track sediment texture changes independently of magnetic variation and provenance changes, facilitate process‐based interpretations, and provide sedimentology‐based insights into these important paleo‐archives and their recorded paleo‐environmental changes.

This review evaluates research in the past 20 years focusing on groundwater nitrate removal in the riparian zones of agricultural watersheds. Studies have reported a large range in the magnitude of groundwater and nitrate fluxes to buffers in different hydrogeologic settings. An earlier focus on buffers with shallow subsurface flow has expanded to include sites with deep flow paths and groundwater-fed overland flow. Nitrate removal efficiency and the width required for removal have been linked to riparian sediment texture and depth to an impervious layer. Denitrification has been identified as the dominant mechanism of nitrate removal based on evidence that this process occurs at depth in many buffers which contain buried organic-rich deposits. Several studies have assessed the cumulative effect of riparian buffers on nitrate removal at the watershed scale. Despite considerable research progress areas of uncertainty still remain. Buffers with coarse-textured sediments located in landscapes with upslope sand aquifers have received most attention. In contrast, few sites have been analysed in weathered bedrock and glacial till landscapes. Many studies have reported nitrate removal efficiency based on nitrate concentrations rather than measuring groundwater fluxes which assess the magnitude of nitrate removal. More information is needed on interactions between riparian hydrological flow paths and biogeochemical processes. Further research is recommended on the effect of riparian zone nitrate removal at the watershed scale and long-term monitoring with respect to buffer restoration, the ability to sustain nitrate removal and responses to land use and climate change.

River corridors in coastal and fluvio‐deltaic plains (FDPs) experience tidal fluctuations and seasonal flooding which result in variable sediment transport regimes and a mix of sand, silt, and clay deposits in the channel and floodplain. In FDPs, river fluctuations influence the extent and dynamics of hyporheic zone mixing and groundwater flow relative to the river. We analyzed the combined effects of external forcing by tidal and seasonal flooding and internal controls by sediment texture on groundwater‐surface water (GW‐SW) interactions in the Meghna River in Bangladesh. We conducted numerical simulations to assess the relative importance and interaction of these factors on GW‐SW mixing. We assessed the influence of complex river stage fluctuations, capturing both semi‐diurnal and seasonal‐scale variations in the mid dry period, early wet period, and the early dry period following the wet season. Sensitivity analyses were conducted to assess the influence of sand, silt, and clay percentage and their predicted van Genuchten soil‐water retention parameters on mixing dynamics. The simulations reveal that mixing zone dynamics are highly sensitive to seasonal periods and soil texture. We found that vertical infiltration of river water was limited to <1 m depth in most scenarios and most promoted in the early wet period. In contrast, lateral infiltration was favored during the early dry period. Higher sand content promoted greater lateral and vertical infiltration, while relatively higher silt and clay contents contributed to thicker capillary fringes and greater water retention closer to the surface. Generally, GW‐SW mixing appears to be limited in low‐energy and tidally influenced fluvio‐deltaic settings.

We analyzed multiple variables in recent sediments from 18 tropical, karst lakes in “Lagunas de Montebello” National Park, a Mexican Protected Natural Area and Ramsar site, to explore relationships between sediment characteristics and lake attributes: topography/location (mountain, surface-water-dominated vs. plateau, groundwater-dominated), morphometry (shallow vs. deep), and human activities (urbanization/agriculture). The study lakes fell into two groups: (1) pristine, oligotrophic, mostly located in the SE mountain terrain, and (2) impacted, eutrophic, in the NW plateau region. Sediment samples were collected from the central, deepest zone of each lake and analyzed for texture (grain size), carbonate content, and organic C and N. Water variables were measured in the water column overlying the sediment collection sites. Specific conductance, chlorophyll a, and total particulate carbon were higher in impacted, eutrophic plateau lakes than in pristine mountain lakes. Sediments, although composed mostly of silts, differed in grain size. Pristine, oligotrophic mountain lakes possessed coarser sediments, with a higher concentration of most likely recalcitrant organic carbon, than impacted, eutrophic plateau lakes. Topography/location is the primary factor that contributes to sediment differences, whereas eutrophication, caused by deforestation and agricultural runoff, is the second most important agent modifying sediment characteristics. The only pristine plateau lake, San José, had water quality similar to pristine mountain lakes, but finer sediments with lower organic C, N, and C/N. Comparison of San José sediments with those of impacted eutrophic plateau lakes indicated eutrophication has led to coarser sediments, as well as enrichment in CO3, organic C and N. Eutrophication-related sediment characteristics are valuable variables that can be used in paleolimnological studies to identify the onset of lake eutrophication in tropical karst water bodies.

Globally, the concentration of heavy metals and sediment toxicity analysis are significant liabilities to aquatic environments. This scrutiny outlines the sediment textures, heavy metals and toxicity status associated with environmental pollution indices in the core sediment of the Cauvery and Vettar estuaries, East coast of India. The impact of rapid industrialization, urbanization, harbour activities and agricultural activities influences on the twain estuary is a significant concern to designate the environment. The contamination status of the sediments affects the potential biodiversity, ecological risks and human health. A total of two core sediments were recovered from the Cauvery and Vettar estuaries in March 2023 to decipher the environmental pollution status. Meticulous observation of the textural studies underscores the prevalence of sand content in Cauvery, and Vettar sediments consist of predominate clay content and minor silt contents. Furthermore, the organic matter is augmented in the Vettar River due to the higher input of waste disposal, seaweeds and algae due to the surrounding landmass. Twain core sediments argue that heavy metal concentration is decreasing in order as Fe > Zn > Ni > Pb > Cu > Cr by using portable X-ray fluorescence (pXRF) spectrometry. Remarkable results of environmental pollution indices such as I geo , E f , C f , C d and m C d state very highly polluted, extreme enrichments, high contamination and very high degree of contamination. Furthermore, the potential ecological risk indices such as PLI, SQG s, and PERI argue polluted, medium to high toxicity and moderate adverse ecological risk to the estuarine regions. Statistical analysis of the heavy metal affirms the enrichment of Fe metals may derive from lithogenic and/or anthropogenic influences, and the other studied metals such as Cu, Ni, Zn, Pb and Cr may be influenced by the anthropogenic activities in the aspect of point and non-point pollution sources. This could result from both estuaries undergoing higher pollution, in which the Vettar estuary is a considerable environmental risk zone compared to the Cauvery river due to the impact of industrial effluents and rapid urbanization activities. This finding underscores the urgent need for enhanced estuarine sediment quality study and comprehensive assessment of sediment toxicity, regulating the beneficial acumen for the government to follow the suitable remediation on the embellish policy of river and marine environments.

This study examines the sedimentary and microbial responses offshore the Marche Region (Italy) to the September 2022 flood, one of the most severe recent hydrological events, which delivered large amounts of sediment and anthropogenic contaminants to the Adriatic Sea. We employed a multidisciplinary approach integrating sedimentology, geochemistry, organic matter analysis, pollutant assessments (Polycyclic Aromatic Hydrocarbons, PAHs and Poly- and Perfluorinated alkyl substances, PFASs), and benthic microbial community structure. Sediments collected just five days after the event offshore river mouths reveal that flood deposits, ranging from fine sand to coarse silt, remained substantially confined to the nearshore zone, whereas finer clay particles were dispersed further offshore and down to the 15 m isobath. This distribution reflects intense riverine inputs and a brief windstorm-enhanced coastal circulation that generated patchy, temporary sediment accumulations mainly in the prodelta sector. Simultaneously, the flood forced a strong spatial heterogeneity in benthic bacterial communities, through the introduction of short-distance shifts in sediment texture and organic matter content. Freshwater taxa became prominent in prodelta deposits, highlighting riverine sedimentary imprints. Heavy metal concentrations remained below regulatory thresholds, whereas organic pollutants, heterogeneously distributed, reach peak concentrations offshore urban and industrial zones. PAH signatures indicate mixed pyrogenic and petrogenic sources, while next-generation PFASs (6:2 FTS) showed localized but severe contamination linked to upstream industrial activities. Despite the flood's magnitude onshore, its offshore sedimentary signatures resulted ephemeral and spatially limited. These findings underscore the ecological significance of episodic sediment and contaminant input, while highlighting the challenges in detecting such transient events in the marine stratigraphic record.

A total of 21 surface sediment samples collected from Arasalar River are subjected to sediment texture (sand-silt-clay ratio), trace elements, organic matter, and CaCO 3 studies to understand the accumulation dynamics of sediments. To assess the impact of metal pollution in estuarine sediments, the essential parameters should be done by checking the sediment characteristics, spatial distribution of heavy metal sources, sediment dynamics, and geochemical analysis. To evaluate the contamination level of metal pollution, a basic standard reference is required to decipher the values ranging from natural to anthropogenic contribution. From this research analysis, it is observed that the study area predominantly comprises silty sand and sand silty nature. The calcium carbonate content in the sediment is found to be proportional to the presence of shell fragments, whereas the organic matter (OM) is derived from riverine and coastal input which acts as a primary source. The obtained results confessed the average contents (mg/g) for the following selected eight elements in the order of Fe (35249–49068) > Mn (286–519) > Ni (107–279) > Cu (78.30–155.70) > Cr (50–99) > Zn (38.70–91.90) > Pb (39.90–62.40), and Co (12.6–29.1) by using an atomic absorption spectrophotometer (AAS) are utilized for this analysis. Multivariate analysis of heavy metals affirms geogenic sources (weathering of parent rocks) for Fe, Mn, Cr, Co, and Zn, whereas Cu, Ni, and Pb originated from anthropogenic activities (urban and industrial activities). The pollution load index, sediment pollution index, I geo index, and PERI are categorized as under polluted, low to moderate polluted, and low potential environmental risk variety. Constant inspection and guidance are needed to prevent effluences from various agriculture and industrial activities in the nearby regions. The findings from this research may support and help the government to follow the suitable remediation on the better management of river and coastal areas.

Globally, stream ecosystem health in mining regions, including the Central African Copperbelt (CACB), is threatened by increased aquatic metal pollution. Stream biomonitoring and bioassessment offers an eco-friendly nature-based approach to determine the aquatic ecological conditions and inform management interventions in mining landscapes. This study conducted monthly between May 2022 and April 2023, explored the taxonomic and functional responses of macroinvertebrates as bioindicators of the ecological condition of four streams in the north-western Zambian Copperbelt of the CACB. 252 sediment samples were collected and analysed for metals. 144 macroinvertebrate samples were collected to determine their taxonomic and functional traits. ANOVA (analysis-of-variance), SIMPER (similarity-percentage), ANOSIM (analysis-of-similarities), CCA (canonical correspondence analysis) and multidimensional biotic index analyses were conducted to correlate environmental and biotic variables. Metal concentrations (mg/kg) in sediments followed the order As (5.27) < Pb (5.75) < Zn (44.6) < Ni (89.3) < Cu (187.5). From ANOVA, the macroinvertebrate community was significantly dominated by Insecta families, mostly Diptera (23.3%) and Coleoptera (16.7%). Trophically, predators significantly dominated in the order Odonata (34.7%) > Hemiptera (31.8%) > Diptera (18.9%). SIMPER depicted a strong influence of Cu, EC, velocity, sediment texture and organic matter on macroinvertebrate diversity and spatial distribution. ANOSIM indicated the highest community dissimilarity at the most impacted stream (KYABR). Habitat assessment metrics, including ZISS-1, ASPT, and EPT/Chironomidae ratio, registered a “good ecological status” with the presence of pollution-sensitive taxa (Helodidae and Perlidae), in concordance with environmental variables, confirming the suitability of macroinvertebrates as proxy bioindicators of stream health in mining landscapes. The study confirms the potential of macroinvertebrates, as potential bioindicators of stream health in mining landscapes. Their diversity and distribution is strongly influenced by Cu, EC, velocity, and sediment characteristics while habitat assessment metrics indicate a \"good ecological status\" despite moderate metal contamination.