Composition Of River Sediments Research Articles

Composition of river sediments from Kerala, southwest India: Inferences on lateritic weathering

Composition of river sediments from Kerala, southwest India: Inferences on lateritic weathering

Quantifying excess heavy metal concentrations in drainage basins using conservative mixing models

High concentrations of heavy metals and other pollutants in river sediments can have detrimental effects on the ecosystem and humans. The composition of river sediments throughout drainage basins therefore provides important information for environmental monitoring. An obvious first step for using river sediment compositions for monitoring is to quantify natural baseline concentrations. Once baselines have been quantified, it is straightforward to compare them to observations to identify excesses generated by, for example, anthropogenic inputs. In this study a new strategy for mapping element concentrations along rivers from discrete geochemical observations upstream is presented. We demonstrate our approach in a case study of the Clyde drainage basin in western Scotland, UK. First, continuous baselines are generated using simple forward models that conservatively mix source region concentrations along drainage networks. 1185 measurements of elemental concentrations from first-order streams are used to parameterise the source region. The calculated baselines are then compared to concentrations measured at 60 localities along the main channel of the Clyde river. For a range of major and trace elements (e.g., Mg, Sr, K, Mn), the downstream observations are in close agreement with baseline concentrations predicted by conservative mixing models. However, some heavy metal concentrations (Pb, Cu, Zn) tend to exceed predicted baseline concentrations. Therefore, the second part of our approach calculates element concentrations in source areas required to match the observed Pb, Cu and Zn concentrations measured along the river. An inverse approach is used to ‘unmix’ the observed concentrations utilising, again, a conservative mixing model. Model resolution is determined by the spatial distribution of the data. Resultant calculated natural baselines and heavy metal concentrations along the river can easily be compared to estimate excesses. We tentatively suggest that anthropogenic input to sediment composition along the river is equivalent to annual fluxes of 9.7, 1.5 and 5.7 t (106 g) of Pb, Cu and Zn, respectively.

IRRIGATSION KANALLARDA DARYO OQIZIQLARINING TARKIBIY QISMI TAHLILI

The article is devoted to the analysis of mechanical and chemical composition of river sediments in irrigation canals. Movement of river drains, which constitute an integral part of water resources, in the riverbed, hydraulic structures and on cultivated lands, forms a sort of a global cycle in nature. According to hydrological studies, only in the very bed of Amu Darya, it is possible to observe movement of a huge amount of runoff throughout the year. From the monitoring of irrigation channels used in Uzbekistan, it is known that for efficient and safe operation of many structures in an optimal mode, scientifically sound management and efficient use of river flows negatively affect the lack of methods and technologies, as well as effective solution of these issues does. Experiments conducted in natural field conditions helped to draw conclusions based on the study of mechanical and chemical compositions of river sediments along the length of canals.

A review of sediment provenance methods applied to the fluvial sediments in the East Sea based on clay mineralogy and Sr-Nd isotope

Studying sediment provenance in the marine environment particularly plays an important role in interpretation of paleoclimate, lithology of the source regions as well as tectonism controlling weathering, erosion, transportation, and deposition processes (source-to-sink analysis). However, defining sediment sources and controlling elements require quantitative data and micro-analysis as they are influenced significantly by many factors such as lithology, tectonics, and climate condition in the source regions as well as sea-level changes, oceanic circulation, and their differential setting in the sea. A number of methods are employed to elucidate sediment provenance, but not all of them are useful in the East Sea. In this study, clay mineralogy and Sr-Nd isotope of sediment cores and surrounding river sediments in this region from previous studies are reused to evaluate their effectiveness in determining sediment provenance. In comparison between sediment cores and river sediments indicates that clay mineral assemblages and Sr-Nd isotopic composition of river sediments frequently contain feature information of the source regions that are preserved in marine sediments well, implying they contain valuable information of sediment provenance. Thus, these methods have been widely utilized to identify sediment provenance in the East Sea. This study displays that sediment provenance methods based on clay mineralogy and Sr-Nd isotope are effective tools in elucidating sediment provenance in the East Sea.

Clay-cation composition of river sediments as evidence of wet versus dry paleoclimate

Cation compositions (XNa, XCa, XMg) of clays in a fluvial, Late Pleistocene, clay-rich siliciclastic sedimentary unit are shown to reflect the composition of surface water at the time of deposition, with clays deposited from surface water in a semi-arid climate (evaporation > precipitation) having an XNa >8%, compared with XNa < 8% for clays deposited under wetter conditions (evaporation < precipitation). This is a product of evaporation in the dry climate that results in an increase in Na relative to Ca and Mg in the surface water during deposition. This trend is shown in fluvial sediments from the Texas Gulf Coast where both the present-day climate, and the climate during Late Pleistocene deposition, have a gradient from wet humid subtropical (mild temperate) in the north, to dry semi-arid subtropical in the south where evaporation exceeds precipitation for much of the year. The possibility that the clay-cation compositions could have been altered by meteoric water recharge after deposition was considered by comparing the ratios of the conservative ion Cl against Na, which undergoes cation exchange. It was found that the Na-rich clays currently present in the dry environment are releasing Na into the groundwater where they are enriched in Na relative to Cl, which strongly supports the original deposition of Na-rich clays rather than Na-poor clays in the south. This trend was not present in the northern sediments with the wetter climate, which supports the original deposition of Na-poor clays. These results support that the Na content relative to Ca and Mg in clays deposited with siliciclastic sediments from surface water in a fluvial environment could possibly be used as paleoclimate proxies to predict wet versus dry climates.

Disentangle the hydrodynamic sorting and lithology effects on sediment weathering signals

River sediment can be used to quantitatively investigate the silicate weathering intensity only if the weathering signal preservation and propagation are well understood, and especially the effects of hydrodynamic sorting and provenance lithology can be disentangled properly. Rivers entering the East China Sea have different climatic and geological settings and sediment source-to-sink transport patterns, which allow us to quantify the link between the chemical composition of river sediments and controlling factors of silicate weathering, hydrodynamic sorting, source rock natures and sedimentary recycling. We examine the geochemical evolution of sediments from these fluvial networks in weathering diagrams of A-CN-K [Al2O3-(CaO⁎ + Na2O)-K2O, Nesbitt and Young, 1984] and MFW [Mafic-Felsic-Weathering, Ohta and Arai, 2007]. The seeming “weathering trends” in these weathering diagrams are greatly influenced by mineral sorting given that the river sediment transport, deposition and resuspension are mainly subject to hydrodynamic conditions. The MFW diagram can better distinguish the influence of felsic and mafic source rocks, on condition that the weathering contribution from recycled sedimentary and metamorphic rocks in the catchment is minor. Nevertheless, both the A-CN-K and MFW diagrams are insensitive to sedimentary recycling induced quartz addition. Here, we propose a diagram of A-CNK-Si to disentangle the major factors controlling the river sediment geochemistry like chemical weathering, hydrodynamic sorting and provenance inheritance. This novel approach can decode the silicate weathering signals preserved in sedimentary records after removing the mineral sorting and quartz dilution effects, which will allow us to better reconstruct the geochemical evolution of Earth's surface.

River Sediment Geochemistry as a Conservative Mixture of Source Regions: Observations and Predictions From the Cairngorms, UK

AbstractThe elemental composition of sediments in rivers is the product of physical and chemical erosion of rocks, which is then transported across drainage networks. A corollary is that fluvial sedimentary geochemistry can be used to understand geologic, climatic, and geomorphic processes. Here, we predict elemental compositions of river sediments using drainage networks extracted from digital elevation data and erosional models. The Geochemical Baseline Survey of the Environment was used to quantify substrate (i.e., source region) chemistry. Sedimentary compositions in rivers downstream are predicted by formally integrating eroding substrates with respect to distance downstream. Different erosional models, including the Stream Power model and uniform incision rates, are tested. Predictions are tested using a new suite of compositions obtained from fine grained (&lt;150 μm) sediments at 67 sites along the Spey, Dee, Don, Deveron, and Tay rivers, Cairngorms, UK. Results show that sedimentary geochemistry can be predicted using simple models that include the topography of drainage networks and substrate compositions as input. The concentration of numerous elements including Magnesium, Rubidium, Uranium, Potassium, Calcium, Strontium, and Beryllium can be accurately predicted using this simple approach. Predictions are insensitive to the choice of erosional model, which we suggest is a consequence of broadly homogeneous rates of erosion throughout the study area. Principal component analysis of the river geochemical data suggests that the composition of most Cairngorms river sediments can be explained by mafic/felsic provenance and conservative mixing downstream. These results suggest that the elemental composition of river sediments can be accurately predicted using simple erosional models and digital elevation data.

Provenance versus weathering control on sediment composition in tropical monsoonal climate (South China) - 2. Sand petrology and heavy minerals

Together with the companion article dedicated to sedimentary geochemistry and clay mineralogy, this study investigates the interplaying controls on the generation and composition of river sediments across South China. In the Pearl River and southern Yangtze catchments, dominantly sedimentary and basaltic rocks of the Yangtze block shed quartzo-lithic sedimentaclastic sand, whereas mostly granitic and sedimentary rocks of the Cathaysia block generate feldspatho-quartzose sand. Rivers of the Fujian and Zhejiang Provinces draining the SE Coast Magmatic Belt carry feldspatho-litho-quartzose volcaniclastic sand containing epidote with minor clinopyroxene and olivine locally. Within the Pearl River catchment, 35–40% of the sand is derived from the Yangtze block, and 60–65% from the Cathaysia block. Erosion rates are fairly evenly distributed across the basin, reaching higher values in the Hongshui headwaters where topographic relief is greater. South China hosts one of the largest and most spectacular karst areas on Earth, where two landscape types are characterized by different intensity of chemical dissolution. In fengcong (cone) karst, carbonate detritus attacked by carbonic and sulfuric acids is partly preserved, whereas carbonate grains are completely dissolved in fenglin (tower) karst developed in wetter regions to the east. The strong climatic gradient from the dry Tibetan plateau in the west to monsoon-drenched coastal areas is faithfully reflected in illite-rich vs. kaolinite-rich clay-mineral assemblages, but in sand the weathering effect is much harder to isolate from the dominant effects of source-rock lithology and recycling. The different durability of tectosilicates (quartz > microcline > orthoclase > plagioclase) and the degree of corrosion displayed by detrital minerals offer essential qualitative information but cannot represent robust proxies to quantify weathering intensity. The sand generation index SGI reveals whether lithologies are under- or over-represented in detrital assemblages and proved to be most useful to trace different weathering regimes across South China.

A regional soil and river sediment geochemical study in Baoshan area, Yunnan province, southwest China

This study aims to better understand, at a regional scale, the concentration and distribution of selected chemical elements in surface environments and the influence of natural factors (geological background, geomorphology) and anthropogenic factors (mining activities, land-use, agricultural fertilization) on their distribution in the Baoshan area, Yunnan province, southwest China. Mineral resources (such as copper, lead, zinc, mercury, gold, silver) and carbonate and basalt parent materials in this area often lead to elevated potentially toxic metals (PTMs), which are widely distributed where mining activities have rapidly developed since last 20–30 years. This study makes use of 1574 surface soil data and 425 deep soil data from the National Geochemistry Survey of Land Quality project (NGSLQ), and 1585 archived river sediment data which were collected and analyzed for the Regional Geochemistry-National Reconnaissance program (RGNR). These data, once log-ratio (clr) transformed have been studied by compositional data analysis (CoDA), principle components analysis (PCA) and spatial analysis. In the Baoshan area, the concentration of elements As, B, (Br), Co, Cr, Cu, Hg, (I), Mn, (N), Ni, Sb, (Sc), (Se), V, Fe2O3Total and (COrgonic) are enriched compared to the China Soil Geochemical Baselines program (CGB) and RGNR data sets; while elements Sr and Na2O are depleted compared to CGB and RGNR data sets. Influencing factors on surface soil, deep soil and river sediment composition of the study area are revealed. The distribution of most elements in surface soil, deep soil and river sediment are influenced by natural factors such that: Co, Cr, Cu, Ni, Sc, Ti, V, Fe2O3Total and MgO are controlled by the distribution of basic igneous rocks; Ca, Mg, Sr and pH are controlled by the distribution of carbonate rocks and basic igneous rocks; As, Hg, Sb, (Ag), Cd, Pb and Zn are controlled by mineralization; and other elements normally controlled by the distribution of clastic rocks and acid-intermediate rocks; while the organic matter such as Br, N, (P), S, COrgonic and CTotal in soil data set are controlled by geomorphic (altitude and temperature). Anthropogenic factors are also recognized in the soil data set. For example: high pH values in paddy land and grassland, and low pH values in forested land, garden plot and dry cultivated land; in agricultural area fertilization has caused enrichment of the nutrient elements (COrgonic, CTotal, N, P, etc.,) in surface soil; while in areas of mining, surface soils are contaminated by PTMs (incl. Hg, As, Sb, Cu, Pb, Zn and Cd).

Mineral Formation under the Influence of Mine Waters (The Kizel Coal Basin, Russia)

The development of coal deposits is accompanied by negative environmental changes. In the territory of the Kizel coal basin (Perm Region, Russia), the problem of contamination of water sources by acid mine waters and runoff from rock dumps is particularly acute. Mine waters are acidic (pH 2–3), with high mineralization (up to 25 g/L) and significant content of sulfate ions, iron, aluminum, manganese, toxic trace elements (As, Co, Ni, Pb and Zn). They are formed as a result of the interaction of underground waters from flooded mines of the Kizel basin with coal and rocks of dumps with high sulfur content (15%). Uncontrolled inflow of mine water into rivers (about 22 million m3 annually) leads to significant amounts of iron and aluminum hydroxide precipitation. These precipitations are in active interaction with river water, polluting the rivers tens of kilometers downstream and are entering the Kama reservoir. Studies of alluvial precipitation can be considered as a method of control and predictors of technogenic water pollution. The mineral composition of river sediments was studied with the application of different methods, including studies of sand-gravel and silty-clayey sediments. The sandy-gravel grains in the bottom load are mainly composed by natural minerals and are represented by a significant number of particles of coal dumps, slags and magnetic spherules. The silty-clayey material, mixed with natural minerals, contains a significant number of amorphous phases with a predominance of iron-rich substances, which may actively concentrate toxic elements. The presence of jarosite, goethite, basaluminite, lepidorocite and copiapite in silty-clayey sediments are indicators of the influence of mine waters.

Chemical composition of the Zeya River sediments in weathering trend of river sediments of Asia

The chemical composition of river sediments reflects bedrock geochemistry in the area of erosion and characterizes trend of weathering in the catchment area. The article presents data about chemical composition of Zeya River sediments. This river is one of the largest watercourses in the Amur River basin. The chemical composition of river sediments was analyzed by X-ray fluorescence spectrometry. Compared with the upper continental crust, the river sediments are depleted in almost all analyzed major elements. According to the analysis of major element the ratio, degree of weathering of river sediments in Middle Reach of the Zeya increases down the river. The chemical composition of studied river sediments is close to those in the rivers of northeastern China.

Transformation of the radionuclides composition of river sediments in the area of the exploited Lomonosov diamond deposit (NW Russia)

The article is devoted to the study of the activity of the natural radionuclides 40K, 232Th, 226Ra and technogenic 137Cs radionuclide in the river sediments of watercourses around the Lomonosov diamond deposit (northwestern Russia). This is the only large diamond mining and beneficiation complex in Europe. Samples of river sediments and surface waters were taken from the Zolotitsa River and its tributaries in the area of the diamond deposit. Samples of rocks were taken from quarries. Samples of kimberlites used for enrichment and rocks entering the dumps were selected. Measurements of the activity of radionuclides in bottom sediments and rocks were conducted using the low-background semiconductor gamma spectrometry method. For measurements, a detector from high-purity germanium was used. The study of uranium isotopes in bottom sediments and waters was conducted using the alpha spectrometry method. The average activity of 137Cs, 226Ra, 232Th and 40K were 5.4, 9.0, 11.2, 318.8 Bq·kg−1 respectively. The impact of the development of the field on the change in the radioecological state of the bottom sediments was evaluated. Several patterns of radionuclide accumulation have been found depending on the physicochemical parameters of river sediments. These patterns are due to the technogenic influence of the mining and beneficiation complex. The performed studies present the first evaluation of the impact of diamond mining on natural radionuclides' distribution and accumulation in the river sediments within the adjacent territories.

Dependence of Fractional Structure of River Sediments on Chemical Composition

The article investigates the mechanical and chemical composition of river sediments and analyzes studies on changes in the chemical composition of sediments by changing their mechanical composition. Given scientific investigations about efficient use of chemical compounds in sediments. The connections between mechanical and chemical composition of the sediments are based on correlation coefficients. The results are based on the fact that small fractional sediments less than 0.05 mm can be used effectively in agriculture.

Progressive Evolution of the Changjiang (Yangtze River) Sediment Weathering Intensity Since the Three Gorges Dam Operation

AbstractChemical composition of river sediments and dissolved load is classically used to infer controls on continental weathering and, therefore, exert an important role on the understanding of the global carbon and biogeochemical cycles. To date, most studied river basins are strongly impacted by dam constructions; however, the effects of dams on sediment chemical compositions are little known. The Three Gorges Dam is one of the largest dams in the world and began impounding water in 2003 in the Changjiang basin. In order to investigate the impact of this dam on downstream sediment chemistry, temporal variation of sediment weathering intensity is reported here based on analyzed and compiled data between 1997 and 2018. Downstream sediments collected before 2003 are characterized by weak weathering intensity, in agreement with the overwhelming flux and fast transfer of sediments derived from the mountainous upper watershed. After the Three Gorges Dam operation, strong midlower riverbed erosion changed the roles of the midlower reaches from important sinks to major sources of sediments delivered to the East China Sea. This resulted in a progressive change of the sediment chemistry because the eroded midlower riverbed sediments were more deeply weathered, as confirmed by 150‐year‐old sediment cored in the lower mainstream and by mass‐balance calculations. This more intensive weathering may be explained by warmer climate and longer water‐rock interaction time in the midlower basin. Thus, this study suggests the need to quantify potential bias in weathering intensity and controls caused by damming activity in large river systems.

The nature and history of the South Qilian orogenic belt: Constraints from compositions of rivers' sediments and their detrital zircon U–Pb geochronology, Lu‐Hf isotopic compositions

Detrital zircon U–Pb dating, Hf isotopic data, and Nd isotopic compositions of river sediments are used to constrain crustal evolution processes of their provenance in the South Qilian orogenic belt. The detrital zircons from the Yuka, Tataleng, and Bayinguole rivers range in age from Neoarchean (2,772 Ma) to Permian (261 Ma), with age peaks at ca. 2.4 Ga, ca. 1.95 Ga, and ca. 0.45 Ga. Hf isotopic compositions of Paleoproterozoic, Pan‐African, and Caledonian zircon age groups display a wide range of εHf(t) values, suggesting diverse sources of host magma of the zircon grains. The basement formation of the South Qilian orogenic belt from depleted mantle occurred at two stages; ca. 3.1–2.5 Ga and ca. 2.0–1.6 Ga. Meanwhile, the Nd model ages of silt‐mud from the region are between 1.98 Ga and 2.27 Ga with an average value of 2.12 Ga. Our study indicates that the Qilian oceanic plate formed between the Qaidam and Alxa blocks from late Neoproterozoic to Silurian. The South Qilian orogenic belt is a product of the Qilian Ocean closure and subsequent collision between the Qaidam Block and central Qilian belt during Ordovician–Silurian times. Combining regional tectonothermal events with new results of river sediments suggests that rifting from a continent and opening of the Qilian Ocean occurred at ca. 780–520 Ma, subduction of the oceanic crust at ca. 520–440 Ma, ocean closure and continental subduction at ca. 440–420 Ma, exhumation of subducted crust at ca. 420–400 Ma, and orogenic collapse and extension at ca. 400–360 Ma.

INTERRELATION OF CHEMICAL AND FRACTIONAL STRUCTURES OF RIVER SEDIMENTS

In this article, the mechanical and chemical compositions of river sediments are studied, the analysis of studies on the change in the chemical composition with a change in the mechanical composition of the sediments is presented. The possibility of effective use of sediments based on the interrelation of their mechanical and chemical compositions is substantiated.

Impact of Reclamation Development on Sedimentation and Current Pattern in East Coast Surabaya (Pamurbaya)

Reclamation is an effort to establish a new land area either in coastal areas or in the middle of the ocean. In Pamurbaya area a number of property projects both housing and apartments is still continuing. Environmental impacts of the coastal reclamation project is in the potential increase of flooding. The changes include the extent of the cluster, the composition of river sediments, the tidal pattern, the pattern of ocean currents along the coast and damaging the water system. This study examines changes in current patterns, morphology, and sedimentation rate due to the reclamation modeled using Delft3D software. The pattern of current flow after the reclamation has changed. Basic surface changes that occur before and after reclamation in each crossection is by difference, crossection 1 = +0.22 m, crossection 2 = -0.19 m, and crossection 3 = +0.11 m. The sign (+) shows the occurrence of sedimentation, while (-) is erosion. The condition after the reclamation in crossection 1 is sedimentation, crossection 2 is erosion, and crossection 3 is sedimentation. The difference in intensity is very small, therefore the erosion and sedimentation which took place after reclamation is not too significant.

Continental weathering and terrestrial (oxyhydr)oxide export: Comparing glacial and non-glacial catchments in Iceland

Glaciers enhance terrestrial erosion and sediment export to the ocean. Glaciers can also impact mineral specific weathering rates relative to analogous non-glacial terrains. In tandem these processes affect continent sediment export to the oceans over glacial-interglacial cycles. This study summarizes field data from glacial and non-glacial Icelandic river catchments to quantify the impact of weathering regime on iron and aluminium (oxyhydr)oxide mineral formation and flux rates. Aluminium and iron (oxyhydr)oxides are strong indicators of organic carbon preservation in soils and marine sediments. Tracing changes in (oxyhydr)oxide formation and deposition therefore provides a means of evaluating potential changes in organic carbon sequestration rates over glacial-interglacial cycles. Overall, there are several measurable chemical differences between the studied glacial and non-glacial catchments which reflect the key role of soil formation on terrestrial weathering. One of the noted chemical differences is that weathering in non-glacial catchments is characterized by higher apparent rates of iron and aluminium (oxyhydr)oxide formation relative to glacial catchments. However, the offset in (oxyhydr)oxide formation does not appear to be transferred into river sediment compositions, and physical weathering appears to be the dominant control of river sediment composition and export. Glacial rivers export far more total sediment to nearshore marine environments than analogous non-glacial rivers suggesting glacial weathering enhances carbon burial by increasing nearshore marine (oxyhydr)oxide accumulation.

Paired geochemical tracing and load monitoring analysis for identifying sediment sources in a large catchment draining into the Great Barrier Reef Lagoon

While sediment tracing has been typically applied to identify sediment sources that are difficult to measure by gauging (monitoring), it can also be useful in estimating relative sediment yields from gauged river catchments. The major and trace element composition of river sediments from eleven locations in the 130000km2 Burdekin River catchment, northeastern Australia was analysed to examine relative contributions from upstream source areas in the 2011/12 water year. Sediment tracing results are compared against estimates derived from sediment load monitoring at three locations. Comparisons show that there is good agreement between tracing results and monitoring data at one of the tributary confluences. At the second site, notable contrasts were found between the load estimates from the monitoring and tracing data. At this site a large impoundment occurs between the upstream sampling/gauging sites for source sediments and the downstream sampling/gauging sites for target sediments. The contrast is likely caused by temporal variations in particle size distributions of suspended sediment from each river and differential trapping efficiencies in the impoundment for sediment derived from the different tributaries. In the absence of the detailed particle size data and trapping efficiency estimates, sediment tracing provides the unique opportunity to elucidate source contributions of the finer fractions of suspended sediment. At a third site, where there were recognised measurement gaps in the monitoring data during large discharge events, the relative load estimates from the tracing data provided a means of constraining the recognized uncertainty of monitored load estimates. We conclude that sediment tracing can be used as a valuable adjunct to monitoring data particularly in remote, large and data-sparse catchments. Both tracing results and monitoring data show that the Upper Burdekin River and Bowen-Bogie Rivers were the dominant source of the <10μm sediments being delivered to the GBR lagoon from the Burdekin River catchment in the 2011/12 water year. More substantial contribution from the Belyando-Suttor Rivers indicated by the tracing results than the monitoring data is attributed to preferential delivery of the 1–10μm sediments through the impoundment and has uncovered a knowledge gap in sediment budgets in the catchment.

Which minerals control the Nd–Hf–Sr–Pb isotopic compositions of river sediments?

River sediments naturally sample and average large areas of eroded continental crust. They are ideal targets not only for provenance studies based on isotopic compositions, but also can be used to establish average continental crust isotopic values. In large fluvial systems, however, mineral sorting processes significantly modify the mineralogy, and thus the geochemistry of the transported sediments. We still do not know, in any quantitative way, to what extent mineral sorting affects and fractionates the isotopic compositions of river sediments. Here, we focus on this issue and try to decipher the role of each mineral species in the bulk isotopic compositions of bedloads and suspended loads sampled at the outflow of the Ganga River that drains the Himalayan mountain range.We analyzed Nd, Hf, Sr, and Pb isotopic compositions as well as trace element contents of a large number of pure mineral fractions (K-feldspar, plagioclase, muscovite, biotite, magnetite, zircon, titanite, apatite, monazite/allanite, amphibole, epidote, garnet, carbonate and clay) separated from bedload and bank sediments. We combine these data with mineral proportions typical of the Ganga sediments to perform Monte Carlo simulations that quantify the contributions of individual mineral species to the Nd, Hf, Sr, and Pb isotopic budgets of bedloads and suspended loads.The isotopic systematics of river sediments are buffered by very few minerals. Despite their extremely low proportions in sediments, zircon and monazite/allanite control Hf and Nd isotopes, respectively. Feldspars, epidote, and carbonate buffer the Sr isotopic budget while clay, feldspars, and heavy minerals dominate Pb isotopes. Hafnium, Sr, and Pb isotopic differences between bedloads and suspended loads are well explained by their different mineral compositions. This confirms that Hf, Sr and Pb isotopic compositions of sediments are strongly biased by mineral sorting processes during fluvial transport; hence they do not always constitute good proxies for provenance studies. In addition, we anticipate that fractionation of the isotopic systems continues at the river/ocean interface to deliver sediments to the deep ocean that are not necessarily similar to their crustal precursors, creating a systematic bias between the compositions of crustal sources and oceanic sediments.