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Beavers modify riverine systems by building dams that alter downstream fluxes of water and sediment. Where beavers have been lost and stream channels degraded, beaver dam analogs (BDAs) are being used to mimic the effects of beaver engineering. Central to the success of these structures in accelerating stream recovery is creating similar ecosystem responses as beaver dams including sediment retention. Unknown is the relative importance of beaver actions versus erosion in the catchment in generating the retained sediment. This study tested the viability of sediment fingerprinting to determine the source of sediment retained by beaver dams and BDAs in a watershed in Alberta, Canada. Concentrations of 29 elements were measured as potential tracers from known sediment sources: upland, terrace, stream bank, and beaver canal. Virtual mixture tests, used to compare the computed source estimates with known source mixtures, revealed that sediment fingerprinting is a robust method for identifying sources of sediment retained by beaver ponds and BDAs. The un‐mixing model results indicate that on average 56% of the sediment retained by the beaver dams originated from terraces, 23% from uplands, and 13% from beaver canals. About 89% of sediment retained by the BDAs originated from eroding stream banks. We conclude that the geomorphic effects of beavers and their dams are more diverse, resulting in more diverse sources of sediment retained by their dams. This differentiates beaver dams from BDAs. The study has implications for informing management practices that involve beavers and beaver mimicry. Plain Language Summary: Growing recognition of the importance of beaver dams in maintaining naturally functioning streams and floodplains has spurred the use of beaver mimicry structures to accelerate stream recovery where stream channels have cut downward because beavers are absent. Despite the importance of sediment trapping in determining the success of beaver mimicry structures in raising the stream bed, the source of the trapped sediment is poorly known and seldom analyzed. This study investigated whether sediment fingerprinting, a well‐known method for assessing sources of lake, estuary and floodplain sediment deposits, could reliably establish the sources of sediment retained by beaver dams and beaver mimicry structures. We tested this method in a watershed in the Canadian Rocky Mountains and found that it effectively differentiated between the sources of sediment trapped by beaver dams and beaver mimicry structures. Sediment trapped by the mimicry structures originated mainly from stream banks flooded by the structures, whereas beaver dams trapped sediment originating from a combination of riparian areas, canals dug by beavers and hillslopes. Beaver mimicry structures did not replicate the sediment trapping processes of beaver dams because the beavers were important in actively mobilizing the sediment that became trapped by their dams. Key Points: Sediment fingerprinting can effectively establish the source of sediment retained by beaver dams and beaver dam analogs (BDAs)Sediment retained by beaver dams originates from different and more diverse sources than sediment retained by BDAsBDA sediment composition does not replicate that of beaver dams as beavers contribute sediment via canal building and terrace inundation [ABSTRACT FROM AUTHOR]

Sediment fingerprinting is increasingly being used to provide information that can help guide management decisions at the watershed scale. The objectives of this study were to investigate the implications of different sediment fingerprinting sampling designs on characterizing sediment dynamics in the Beheshtabad Watershed in Chaharmahal va Bakhtiari Province, western Iran. First, nitrogen, organic carbon, phosphorus, potassium, calcium, sodium, zinc, manganese, iron, and lime fingerprints were used to discriminate among four potential sediment sources including agricultural topsoil, rangeland, as well as rainfed and urban lands. Then, the suspended sediment was collected from drainage areas at five sites. Nested and local-location fingerprinting sampling designs were employed to evaluate the influence of geomorphic connectivity and land use on apportionment results by using the same source and sediment data set. By averaging all locations using the nested method, agricultural land with an average of 69% had the highest contribution to sedimentation followed by rainfed land with an average of 19.9%, rangeland with an average of 6.8%, and urban lands with an average of 5.99%. Compared to the mean of the total method samples, the local method showed greater soil loss from agricultural lands and lower soil loss from rangeland and rainfed lands. Generally, surface soil in sediments came from agricultural land use. According to the results, total nitrogen, phosphorus, organic carbon, and calcium were the optimum tracers that correctly distinguished source samples. Overall, each of the two fingerprinting sampling designs provided the same information. Thus, the fingerprinting method can determine the sources of sediments. Given the importance of the fingerprinting method, future studies can focus on determining the appropriate combination of tracers and the effect of sediment sampling time. [ABSTRACT FROM AUTHOR]

Purpose: Over the last 60 years, intensification of soil cultivation led to an acceleration of soil erosion and sediment delivery to river systems. In Martinique, this acceleration has led to the remobilization of a toxic insecticide (i.e. chlordecone) used in the 1970s-1990s to control banana weevil. A previous study attributed this accelerated remobilization to the application of glyphosate in plantations from the 1990s onwards. To further unambiguously confirm this link, the identification of soil erosion sources supplied to coastal sediment is essential. Methods: Accordingly, sediment fingerprinting tools were adapted and applied to a coastal sediment core collected in the Galion Bay. Potential source samples (n=37) were collected across the drainage area. Along with the coastal sediment core layers, these samples were analysed for potential tracing properties. The optimal suite of tracers was then selected and introduced into an un-mixing model to quantify their contributions to coastal sediment. Results: Results showed that subsoil (i.e. soil layer < 30 cm depth) and banana plantation soil surface supply the major sources of sediment (49-78% and 12-36%, respectively) to the Galion Bay and that their contributions increased since 2000, in line with chlordecone and glyphosate fluxes. Conclusion: This evolution may be attributed to the higher sensitivity of banana plantations to erosion that may have been enhanced by the glyphosate application leaving the soil uncovered with vegetation and to the contamination of both topsoil and deep soil layers ( < 30 cm) layers with chlordecone due to its vertical transfer along the soil profile and its redistribution across hillslopes. [ABSTRACT FROM AUTHOR]

Purpose: Identification of hotspots of accelerated erosion of soil and organic carbon (OC) is critical to the targeting of soil conservation and sediment management measures. The erosion risk map (ERM) developed by Lilly and Baggaley (Soil erosion risk map of Scotland, 2018) for Scotland estimates erosion risk for the specific soil conditions in the region. However, the ERM provides no soil erosion rates. Erosion rates can be estimated by empirical models such as the Revised Universal Soil Loss Equation (RUSLE). Yet, RUSLE was not developed specifically for the soil conditions in Scotland. Therefore, we evaluated the performance of these two erosion models to determine whether RUSLE erosion rate estimates could be used to quantify the amount of soil eroded from high-risk areas identified in the ERM. Methods: The study was conducted in the catchment of Loch Davan, Aberdeenshire, Scotland. Organic carbon loss models were constructed to compare land use specific OC yields based on RUSLE and ERM using OC fingerprinting as a benchmark. The estimated soil erosion rates in this study were also compared with recently published estimates in Scotland (Rickson et al. in Developing a method to estimate the costs of soil erosion in high-risk Scottish catchments, 2019). Results: The region-specific ERM most closely approximated the relative land use OC yields in streambed sediment however, the results of RUSLE were very similar, suggesting that, in this catchment, RUSLE erosion rate estimates could be used to quantify the amount of soil eroded from the high-risk areas identified by ERM. The RUSLE estimates of soil erosion for this catchment were comparable to the soil erosion rates per land use estimated by Rickson et al. (Developing a method to estimate the costs of soil erosion in high-risk Scottish catchments, 2019) in Scottish soils except in the case of pasture/grassland likely due to the pastures in this catchment being grass ley where periods of surface vegetation cover/root network absence are likely to have generated higher rates of erosion. Conclusion: Selection of suitable erosion risk models can be improved by the combined use of two sediment origin techniques—erosion risk modelling and OC sediment fingerprinting. These methods could, ultimately, support the development of targeted sediment management strategies to maintain healthy soils within the EU and beyond. [ABSTRACT FROM AUTHOR]

ABSTRACT Agriculture intensification in Southern Brazil’s subtropical regions combined with the frequent occurrence of erosive rainfall has rendered the area a global water erosion hotspot. In this scenario, understanding and regulating erosion processes at the river catchment scale is critical for mitigating soil and water resource degradation. Traditional methods for tracing sediment sources are expensive and time-consuming and justify the development of alternative approaches. Therefore, in this study, we employed diffuse reflectance spectroscopy analyses in the ultraviolet-visible (UV-VIS), near-infrared (NIR), and mid-infrared (MIR) ranges, combined with multivariate models and spectral pre-processing techniques to estimate sediment source contributions in a homogeneous subtropical catchment (Conceição River, 804 km²). Soil samples (n = 181) were collected to characterize the four potential sediment sources, including: cropland (n = 78), stream bank (n = 36), unpaved road (n = 40) and pasture (n = 27). Moreover, 44 sediment samples were collected, including suspended sediment (n = 8), fine sediment deposited on the riverbed (n = 15), and suspended sediment samples collected in the water column during storm events (n = 21). Vector machine (SVM) model outperformed the others, with better accuracy and reliability. While UV-VIS spectra proved less effective due to soil homogeneity across the catchment, NIR and MIR spectra provided valuable information for discriminating sediment sources. Furthermore, reducing the number of potential sources (from four to three or two) improved model predictions, especially when distinguishing between surface sources (cropland and pasture) and subsurface sources (unpaved roads and stream banks). The study’s findings shed light on the power of efficient and cost-effective alternative methods for assessing sediment sources, which are vital for promoting effective erosion control and sustainable land management in similar regions.

Purpose: The characterization of soil properties is an important part of many different types of agri-environmental research including inventory, comparison, and manipulation studies. Sediment source fingerprinting is a method that is increasingly being used to link sediment sources to downstream sediment. Characterization of sediment sources is a key part of this method as it serves as the base to identify and quantify soil properties (fingerprints) that can discriminate between sources. There is currently not a standard approach to characterizing sources and the different approaches to sampling have not been well assessed. Methods: Grid (n = 49), transect (n = 14), and likely to erode (n = 8) sampling designs were used to characterize the geochemical, colour, grain size distribution, and soil organic matter content at two sites under contrasting land uses (agricultural and forested). The impact of the three sampling designs on characterization of fingerprint properties, the relationship between particle size and organic matter content on fingerprint properties, fingerprint selection, source discrimination, and mixing apportionment results were evaluated using a range of methods including 21 virtual mixtures. Results: The likely to erode design resulted in a unique fingerprint signature compared to the other two sampling designs. The correlation between particle size and organic matter varied between fingerprint, source, and sampling design. While the number and composition of the fingerprints selected varied between sampling designs there was a strong (100%) discrimination between sources regardless of the sampling approach. The maximum absolute difference between the virtual mixtures and the modeled proportions was 7.7%, 7.8%, and 8.9% for the grid, transect, and likely to erode sampling designs, respectively. Conclusions: The likely to erode sampling design was not representative of the upslope areas as characterized by the grid and transect methods. Despite these differences the final apportionment results using virtual mixtures were qualitatively similar between the three sampling designs. Continued work at the watershed scale is needed to fully evaluate the importance of source sampling design on the sediment source fingerprinting approach. [ABSTRACT FROM AUTHOR]

Rainfall and land-use interactions drive temporal shifts in suspended sediment sources, yet the magnitude of such changes remains poorly understood due to the lack of land-use specific source tracers. We investigated α,ω-dicarboxylic fatty acid root-specific biomarkers, as diagnostic tracers for apportioning sources of time-integrated suspended sediment samples collected from a grassland dominated agricultural catchment in the southwest of England during the wet winter period. Applying fatty acids-specific stable carbon isotope analysis and a Bayesian isotope mixing model, we show that stream banks contributed most of the sediment in the early winter, i.e. October–December, while winter cereal-dominated arable land contributed more than half of the sediment during the late winter, i.e. January–March. The dominant sediment source shifted in conjunction with a period of prolonged consecutive rainfall days in the later period suggesting that intervention required to mitigate soil erosion and sediment delivery should adapt to changing rainfall patterns. Our novel findings demonstrate that isotopic signatures of α,ω-dicarboxylic fatty acids are promising tracers for understanding the resistance of agricultural soils to water erosion and quantifying the interactive effects of extreme rainfall and land use on catchment sediment source dynamics. [ABSTRACT FROM AUTHOR]

Objective: We described source and phosphorus (P) retention potential of soft, fine-grained, streambed sediment and associated phosphorus (sed-P) during summer low-flow conditions. Combining in-channel, sed-P storage with relative age provided context on relevance to western Lake Erie Basin management goals. Methods: In 2019, rapid geomorphic assessment (30 reaches) compared streambed-sediment storage (S) to streambank erosion (E), providing annual sediment budgets (S:E). Streambed sediment (13 reaches) was fingerprinted and analyzed for sed-P. The P saturation ratio (PSR; four reaches) quantified potential sorption/desorption of dissolved P (DP) between the water column and streambed sediment. Analyses were supplemented with data from 2017 and 2021. The ratio of two fallout radionuclides, beryllium-7 (54-day half-life) and excess lead-210 (22.3 years), apportioned "new" sediment based on time since rainfall contact. Results: Streambed sediment was mostly streambank (54–96%) for contributing areas > 2.7 km2; for upstream reaches, a larger percentage was apportioned as upland (cropland, pasture, forest, and road), with < 30% streambank. Streambank erosion correlated with contributing area; however, soil type (ecoregion), stream characteristics, and land use combined to drive streambed-sediment storage. Individual-reach S:E (accumulation of 0.01–35 years of streambank erosion) differentiated erosional and depositional in-channel environments. Most reaches indicated that 17–57% of sediment had recent contact with rainfall. Streambed-sediment PSR indicated a low potential for further sorption of DP from the water column; one reach was a P source when sampled. Conclusion: Sed-P was higher in streambed sediment than in source samples, which varied by land use and ecoregion. This indicates homogenization resulting from in-stream sorption of DP during sediment transport that occurs over multiple events. [ABSTRACT FROM AUTHOR]

ABSTRACT Identifying sediment sources is fundamental for protecting and improving soil and water quality. Conventional fingerprinting studies have often collected sediments at the overall watershed outlet only, resulting in an important spatial scale dependency. This study aimed to identify and to assess the delivery patterns of sediment sources within three priority sub-catchments (Sapocaji, Piedade and Minas) located in the downstream portion of the Ipojuca River watershed in Brazil. This research would build on understanding sediment sources in the studied watershed by elucidating source type contributions on a sub-catchment basis. Both bed and suspended sediment samples were collected in these sub-catchments, and two types of sources were sampled: surface and subsurface sources. A total of 21 geochemical tracers were measured. The tracers were evaluated for their conservation and discriminatory ability (Kruskal-Wallis test and linear discriminant analysis), and the best set of tracers was selected for source apportionment modeling using MixSIAR. Surface (i.e., sugarcane croplands) sources contributed the highest to suspended sediments in the Piedade and Minas sub-catchments. There was a difference in the quality of riverbank management, which helped explain contrasts in the importance of this source. Overall, sub-catchment-specific sediment control management measures, such as the revegetation of riparian forests, need to be implemented, mainly in the Sapocaji sub-catchment. These results underscore the importance of connectivity for surface source contributions.

Study region: The Daliang Mountain region, characterized by its widespread debris flow-pone catchments, is the primary sediment source area for the upper reaches of the Yangtze River, and has experienced intensive human activity over the past half-century. Study focus: Here, we combined lake deposits with sediment source areas to quantify the sediment source and corresponding sediment yield (SY) in response to recent human impacts in a typical debris flow-prone catchment located in the Daliang Mountain region, Southwest China. The fingerprinting techniques, incorporating geochemical elements and their specific ratios, were used to characterize the sediment provenances and corresponding SY. New hydrological insight for the region: The results indicated that gully erosion was the major sediment provenance (90.10 %) in the catchment, followed by cultivated land (6.76 %) and forested land (3.14 %) for the studied period. The temporal variations of SY showed two distinctive erosional stages in response to different human activities over the past 70 years, namely 1950−2004 and 2004−2020. Greater SY values, dominated by gully erosion, occurred from 1950 to 2004, implying that both critical national activities and revegetation projects have limited effects on surface sediment generation. In contrast, gully activity and resulting SY have sharply decreased since 2004 following the implementation of check dams. These comparisons indicate a central role of the check dam in reducing gully activity. The findings have important implications for policymakers to optimize the spatial layout of future soil conservation strategies in the region.

Purpose: This research aimed to determine if a severe wildfire caused changes in the source of sediment being delivered to downstream aquatic systems and evaluate the use of polycyclic aromatic hydrocarbons (PAHs) and color properties as tracers. Methods: Sediment samples were collected from 2018 to 2021 in three tributaries impacted by the 2018 Shovel Lake wildfire and from two sites on the mainstem of the Nechako River, British Columbia. Source samples were collected from burned and unburned soils as well as from channel banks and road-deposited sediment. Samples were analyzed for color properties and for the 16 US Environmental Protection Agency priority PAHs. After statistical tests to determine the conservatism and ability to discriminate between sources by the tracers, the MixSIAR unmixing model was used, and its outputs were tested using virtual mixtures. Result: In the tributaries, burned topsoil was an important contributor to sediment (up to 50%). The mainstem Nechako River was not influenced as significantly by the fires as the greatest contributor was banks (up to 89%). The color properties provided more realistic results than those based on PAHs. Conclusion: In smaller watersheds, the wildfire had a noticeable impact on sediment sources, though the impacts of the fire seemed to be diluted in the distal mainstem Nechako River. Color tracers behaved conservatively and discriminated between contrasting sources. Due to their low cost and reliability, they should be considered more widely. While PAHs did not work in this study, there are reasons to believe they could be a useful tracer, but more needs to be understood about their behavior and degradation over time. [ABSTRACT FROM AUTHOR]

Understanding spatio-temporal suspended sediment dynamics is more important in large watersheds due to the decisive role of local source apportionment in sediment transport and yield. The Talar River with a large mountainous watershed in northern Iran, which plays a vital role in water supply for agriculture and drinking, recently has faced quality degradation. The current study explores the relative contribution of suspended sediment sources using geochemical tracers and fingerprinting techniques in high and low flow periods along this river. Soil samples were collected from four major land uses including rangeland, forest, rainfed agriculture, and irrigated agriculture, as well as riverbanks and riparian zones along the main river. Furthermore, suspended sediment was sampled at four sampling points along the main river in two seasons. Land use apportionment in suspended sediment yield was calculated using an unmixing model included in a newly developed package (FingerPro) in high flow and low flow, separately. The fingerprinting results showed a highly spatio-temporal dynamic for sediment source contribution along the main river in high and low flow periods. Natural land uses (forest and rangeland) in upstream reaches and agricultural land uses and riverbank sources in downstream reaches showed higher contributions to suspended sediment yield. The mean contribution of various land uses for both high and low flow periods indicated substantial contributions from forest (34%–41%) and riverbanks (31%–33%). The significant difference in sediment geochemical properties for the two flow seasons highlights the important role of the prevailing climatic-hydrologic condition on river sediment. Moreover, this issue indicates that sediment source contributions and transfer mechanisms are highly dynamic in Talar River watershed. The current study outcomes provide essential knowledge to create a robust strategy for mitigation of river sediment pollution. [Display omitted] • Geochemical properties of suspended sediments changed in high and low flow period. • Forest and river bank were the main sources of suspended sediment in both periods. • Contribution of irrigated and rainfed agriculture increased in downstream. • Spatio-temporal dynamic of suspended sediment sources evaluated using fingerPro. [ABSTRACT FROM AUTHOR]

Pristine tropical river systems are coming under increasing pressure from the development of economic resources such as forestry and mining for valuable elements. The Lebir catchment, north eastern Malaysia, is now under development as a result of unregulated tree felling and mining for essential and rare metals. Two sediment cores, one in the upstream reaches and the other from the downstream reaches, were taken from flood prone area of the Lebir River, Malaysia, and analysed for their elemental composition by XRF, specifically Al, Si, Fe, Ca, K, Mg, Mn, V, Cu, Ni, Pb, Cr, Zn, As, Th and U. Activities of fallout radionuclides, 137Cs and 210Pb were also determined to from a geochronological context. The elemental concentrations in the soils were assessed in terms of their enrichment factor and Si, Ca, K, Mg, Mn, V, Cu, Ni and Zn were found not to be enriched, whereas As, Th and U had elevated enrichment factors. The Th and U were particularly enriched in the downstream core indicating inputs from a tributary that drains a catchment with known deposits of Th and possibly U. The results suggest that the growth in economic development is fostering the transport of contaminants by the major rivers which, in turn, is contaminating the riverine floodplains. This points to the need for a more integrated and holistic approach to river basin management to maintain the environmental quality of these fragile aquatic systems. [ABSTRACT FROM AUTHOR]

Identification of sediment resources and their associated pollutants and contribution separation of land uses / land cover in sediment production is a valuable tool in spatial prioritization of soil conservation practices at watersheds. The present study was conducted with aim of bed sediment Fingerprinting using the geochemical method in Vaz watershed in Mazandaran Province. Thirty soil samples from different land covers were collected as sediment sources, and a sample of bed sediment at the basin outlet was measured. The geochemical characteristics including 59 elements were measured using ICP-OES. Then, using the combination of range tests, Kruskal-Valis and DFA test in FingerPro package at R software, 15 elements including K, Li, P, V, Cr, Fe, Cu, Ga, Ge, Rb, Sb, Ba, Nd, Ta, and W were selected as the optimal tracers. The results with a goodness index of fit of 78.31 showed that the contributions of agricultural, rangeland, forest, and stream bank lands in the bed sediment yield were with rates of 2.77, 3.61, 12.14, and 73.84 %, respectively. Finally, the relative contribution of each source in sediment yield for each hectare was calculated and the results showed that stream bank and rangeland with the relative contribution of 0.43 and 0.0008 percent for each hectare have the highest and lowest participation in sediment yield, respectively.

Sediment fingerprints have been widely used in source identification studies. Optical features have become a powerful substitute for traditional fingerprints in recent years due to their fast measurement and low analysis costs. However, the accuracy of optical fingerprinting methods has received little attention. Here, artificial mixing and indoor scouring experiments were carried out to compare and assess the accuracy of optical fingerprinting results using three spectroscopic ranges [visible (VIS), near‐infrared (NIR), and mid‐infrared (MIR) spectroscopy] in multivariate models and using 19 colour parameters [such as red (R), green (G) and blue (B) in an RGB system; virtual component X (X), brightness (Y) and virtual component Z (Z) in a CIE XYZ system and so on] coupled with the conventional method. Furthermore, we examined how sediment sorting (particle sorting and organic matter enrichment) affects the accuracy of source apportionments. The results showed that VIS, NIR and MIR spectroscopic tracers presented high accuracy in scouring and artificial mixtures, with mean absolute error (MAE) values of 4.98% and 5.91%. In contrast, the colour parameters had weak performances in two experiments (MAE = 16.83% and 15.05%). Additionally, similar fingerprinting results of the scouring mixtures (MAE = 7.95%) and artificial mixtures (MAE = 8.20%) indicated that slight particle sorting and organic matter enrichment have little effect on the accuracy of optical fingerprinting results. Our study shows that sediment fingerprinting based on optical features, especially three spectroscopic ranges, has good applicability in sediment source identification. [ABSTRACT FROM AUTHOR]

Wildfires are a natural landscape disturbance in many climates and forest types, but the cumulative impact of human-caused climate change, historical fire management and suppression, and changing species diversity in forests has led to an increase in the size and (or) severity of wildfires in certain regions across the globe. There are a significant number of research studies on the effects of wildfire on human health, forest ecology, hydrology, and the physical, chemical, and biological properties of soils. However, research on the impact of wildfire on watersheds including toxicity in aquatic organisms, water chemistry, and fluvial sediment quality is less extensive, focusing primarily on water quality indicators such as nutrients and sediment flux. Recent research has shown that wildfires contribute to the environment significant amounts of polycyclic aromatic hydrocarbons (PAHs), which are compounds produced during the incomplete combustion of organic material, and are known to be toxic and mutagenic compounds. The primary objective of this paper is to review the recent literature that pertains to the contamination of surface waters and sediments and source apportionment of wildfire-derived PAHs to determine where research gaps remain. Additional objectives are to assess the use of molecular ratios to apportion PAH sources and, finally, to create a roadmap for future studies in designing and conducting research that seeks to determine sources of wildfire-derived PAHs in water and sediment. [ABSTRACT FROM AUTHOR]

Purpose: Lake Victoria has been increasingly silting over the past decades, impacting water quality and loss of biodiversity. Sediment control strategies require information on the relative and absolute contributions of sediment from different sources. However, to date, there is no continuous monitoring of sediment flux or water quality in any of the tributaries, prohibiting an assessment of the scale of the problem. The aim of this study was to trace the dominant sources of riverine sediment using geochemical fingerprinting, thereby generating a knowledge base for improving land management and reducing sediment yields in Simiyu River catchment, one of the main contributing rivers to Lake Victoria. Materials and methods: Geochemical tracer concentrations were analyzed in transported sediment from the main river and two tributaries (riverbed sediments) and from soils in five dominant land use types (agricultural land, bush land, forest land, channel banks, and main river banks). Dominant sources to the Simiyu main river sediment were attributed using the Bayesian MixSIAR model. Results and discussion: The mixing model outputs showed that the Simiyu tributary was the dominant source of sediment to the Simiyu main river with 63.2%, while the Duma tributary accounted for 36.8%. Cultivated land was shown to be the main land use source of riverine sediment, accounting for 80.0% and 86.4% in Simiyu and Duma sub-tributaries, respectively, followed by channel banks with 9.0% in both sub-tributaries. Direct unmixing of the Simiyu main river sediment to the land use sources yielded 64.7% contribution of cultivated land and 26.5% of channel banks. Conclusion: The demonstrated application of sediment source tracing provides an important pathway for quantifying the dominant sources of sediment in the rivers flowing towards Lake Victoria. Eroded soil from agricultural areas is the biggest contributor to transported sediment in the Simiyu River. This information is vital for the design of catchment wide management plans that should focus on reducing soil erosion and sediment delivery from farming areas to the river networks, ultimately supporting both food security and water quality in the Lake Victoria Basin. [ABSTRACT FROM AUTHOR]

Study region: In this study, we compiled and analyzed the results of previous sediment fingerprinting research that examined the riverbank as one of the sediment sources, representing 118 catchments across the globe, most of which were located in the UK (n = 84), the USA (n = 14), and Brazil (n = 10). Gathered studies included catchments ranging from 0.31 to 15,000 km2 and which were predominately agricultural. Study focus: It is essential to understand how riverbanks contribute to total sediment load at the catchment scale if we wish to develop better strategies for managing soil loss. Therefore, the main objective of this study was to assess different fingerprinting tracers quantitatively and analyze the influence of catchment size on riverbank erosion. New hydrological insights: We found that radionuclide tracers show the most consistent relative sources contributions. The share of riverbanks to total sediment loss was in the range of 1–25%. At the same time, the relative contributions of riverbanks and surface sources for many catchments exceeded 25% and 90%, respectively. This variability emphasizes the number of factors affecting riverbank erosion. However, despite this, there was a clear shift in contributions from surface sources to riverbanks with increasing catchment size. We suggest that, in nested catchments, there is a need for long-term longitudinal monitoring of sediment loads, including downstream changes of riverbank erosion.

Stream bank erosion has been anecdotally identified as an important source of sediment in New Zealand catchments, however, there have been few attempts to quantify its contribution. Here we use a radionuclide-based sediment tracing approach to determine the relative contribution of stream bank- and hillslope-derived sediment within three catchments in the upper North Island of New Zealand. Both lithogenic (radium-226 and radium-228) and fallout radionuclides (caesium-137 and excess lead-210) were used to differentiate sediment derived from stream bank and hillslope sources. The relative contribution of stream banks and hillslopes to fluvially transported suspended sediment were predicted using a mixing model approach. Our results indicate that both fallout and lithogenic radionuclides provide good source differentiation. We demonstrate that stream bank erosion can contribute very high proportions of sediment within New Zealand catchments. We used independent assessments of bank erosion from each of the study catchments to support the sediment source fingerprinting results. Further work is required to determine the spatial and temporal variability of the contribution of sediment from stream banks. Information on the importance of different sediment sources is needed to target limited catchment rehabilitation resources where they will have the most impact. [ABSTRACT FROM AUTHOR]

Like many impaired Great Lakes tributaries, Apple Creek, Wisconsin (119 km2) has Total Maximum Daily Load (TMDL) targets for reducing suspended sediment and total phosphorus by 51.2 % and 64.2 %, respectively. From August 2017 - October 2018, a stream sediment budget and fingerprinting integrated study was conducted to quantify upland and stream corridor sources of suspended sediment and sediment-bound phosphorus. Phosphorus concentrations varied among source groups and fluvial sediments, with higher concentrations among suspended sediment and cropland soils. Eroding streambanks identified in the stream corridor sediment budget accounted for 100 % of the TMDL Soil and Water Assessment Tool (SWAT) suspended sediment load but only 20 % of the total phosphorus load. Fine-grained streambed sediment equated to approximately-three years of modeled suspended sediment load but only one third of total phosphorus load. The two primary sources of fine-grained streambed sediment were streambanks and cropland, with relative streambank contributions increasing with downstream direction and watershed area. The relative proportion of suspended sediment varied by season and streamflow; however, cropland and streambank erosion accounted for 54 % and 23 % of the suspended sediment when weighted by of the proportion for representative streamflow. Urban land was a source in the upper watershed, but the signature was sequestered by a mid-watershed detention basin. Contributions from construction sites were higher in the fall 2018, likely corresponding to increased activity following a wet spring. These integrated techniques helped describe sources, transport, and sinks of fluvial sediment and phosphorus throughout the watershed at a range of spatial and temporal scales. [ABSTRACT FROM AUTHOR]

• Compound specific stable isotopes successfully discriminated across land use types. • Multiple statistical analyses showed significant overlap among agricultural sources. • The primary source of sediment in Murray Creek is agriculture, followed by banks. • Reducing field and bank erosion is paramount for aquatic ecosystem health. Agricultural fields are a known contributor of sediment to streams and rivers, but determining specific sources of sediment in agricultural watersheds characterized primarily by C3 plants has proven difficult with traditional sediment fingerprinting methods. This study aimed to use compound-specific stable isotopes of long-chain fatty acids (LCFAs) to determine the sediment contribution from multiple sources – cropped, grazed, forage, riparian zones, banks, and forested soils – to Murray Creek, a tributary to the Nechako River in British Columbia, Canada. Source and sediment samples were collected in 2019 and analysed for LCFA concentrations and δ13C FA values (C20:0-C30:0, C32:0). Statistical analyses were undertaken to determine the discrimination capabilities of the LCFAs. Results showed that discrimination was poor across the agricultural land uses, though forested samples were clearly identified. For mixing in Murray Creek, just three sources – agriculture (including riparian areas), forested, and banks – were used. The results found agriculture and banks to be the primary sources of sediment. This is important because Murray Creek delivers sediment to important fish spawning habitat, which has been identified as one of multiple causes of fish population declines. The difficulty in discriminating between the agricultural land use types reflects multiple confounding factors including the multi-use nature of agricultural land in Murray Creek (i.e., land can be used as harvested forage and unmanaged grazing in the same year), the similarities in isotopic signatures across C3 plants, and the temporal insensitivity of the analysis, which may pick up the vegetation signatures of previous years. While the LCFAs were not able to identify specific fields of importance in the timeframe of this study, this technique would be valuable if the sources were more unique, if more samples of each source were taken for better characterization, and if previous land use in the agricultural fields was incorporated. [ABSTRACT FROM AUTHOR]

• Crop-specific sediment sources are unknown in temperate loess soil areas. • CSSIs of δ13C of fatty acids were used to distinguish C3 vs. C4 plant sources. • C3 and C4 plants contributed 9% and 63% respectively at the catchment outlet. • The riverbank contributed relatively less to the surface sediment sources. • Riverbank source contribution to total soil loss increases with catchment size. Identifying crop-specific sediment sources is important, and conventional fingerprinting methods do not do so sufficiently, which limits their usefulness. The application of compound-specific stable isotopes (CSSIs) enables crop-specific sediment sources to be identified. To this end, this study applied the CSSI method to the intensively farmed loess soil Geesgraben catchment (75 km2), in Central Germany. We used this catchment because the importance of different surface and subsurface sediment sources is unknown in temperate loess soil areas. The study also compared radionuclide and spectral fingerprinting methods, as well as spatiotemporal contribution of sediment sources. Specifically, the CSSI method, based on measuring δ13C signatures of fatty acids, was applied to distinguish C3 and C4 plants, and riverbank sediment sources, which were identified using a multivariate mixing model. At the midstream site, the riverbanks contributed a mean of 12 % of the sediment, while the C3 and C4 plants each contributed 44 %. At the downstream site, according to the CSSI method, the riverbanks contributed 28 %, while the C3 and C4 plants contributed 9 % and 63 %, respectively. In comparison, according to the radionuclide and spectral methods, the downstream riverbanks contributed 41 % and 10 %, respectively; generally, this shows relatively lower contribution to the surface sediment contribution. The riverbanks contribution increased with catchment size, due to downstream changes caused by the deposition of surface sediments. Thus, results showed that CSSIs of δ13C of fatty acids can distinguish C3 vs. C4 plants and surface vs. riverbank sources at the catchment scale. However, radionuclides remain useful in heterogeneous catchments because they are not influenced by soil type or lithology. This information is crucial for implementing agricultural practices that can decrease sediment loads to river ecosystems. [ABSTRACT FROM AUTHOR]

• High frequency (5-minute interval) sediment fingerprinting is presented. • Fingerprints were measured in situ using UV–Vis spectrophotometer sensors. • Validation of source contributions was based on the sediment budget. • Results for 7 monitored periods showed a mean deviation of 9.4% from this budget. • Short term changes in sediment source contributions were mostly well identified. Sediment fingerprinting is a commonly applied approach to quantify catchment suspended sediment (SS) source contributions. However, due to the high workloads and costs involved in SS sampling and laboratory analyses, traditional procedures often result in a limited number of samples and sampling campaigns, which can hamper the capacity to capture the intra- and inter-storm variations in SS source activation and deactivation. A better understanding of the temporal dynamics in source contributions is needed, however, to improve the understanding of dynamic sediment generation and delivery processes for selecting management practices. In recognition of the extant need to improve high-frequency source estimates and to permit long duration measurement campaigns, the work reported herein presents a sediment fingerprinting procedure using UV–Vis absorbance spectra measured in situ with submersible spectrophotometer probes to estimate spatial SS source contributions based on a confluence-based monitoring strategy. The high-frequency (5-minute intervals) measurements were used to fingerprint SS sources during seven selected periods with varying hydrological conditions. Source apportionment estimates (MixSIAR model) were validated using an independent sediment budget. The results showed a mean deviation of 9.4 ± 6.0 %, compared with the sediment budget, for the seven periods combined (n = 7,282 time steps). The most accurate results (mean absolute error of 5.3 ± 4.3 %) were obtained for the period covering the July 2021 flood event in central Europe (return period for the monitored catchment > 20 years). Overall, modelled variations in SS source contributions mostly followed the sediment budget dynamics. This novel work highlights the potential for using spectrophotometer absorbance data for high-frequency and long-term sediment fingerprinting purposes. We argue that the presented method can lead to new opportunities to improve our understanding of SS sources and their dynamics. [ABSTRACT FROM AUTHOR]

Determination of the role of each lithological unit in sediment production is an important priority of watershed management. The geochemical method provides the means to determine the origin of sediments in the Gheshlagh Dam, Sanandaj. Various lithological units were studied as sources of sediment deposited behind sediment-retaining structures. A total of 33 samples of sediment and sediment sources were collected and examined in the laboratory after sieving through a 62-micron sieve and identifying by instrument an ICP Initially, 9 sources of potassium, calcium, phosphorus, carbon, magnesium, chromium, sodium, cobalt, and nitrogen were used to determine the optimal composition of the tracers. Using the 2-stage analysis of variance and detection function, 3 elements, namely: cobalt, chromium, and calcium were selected as suitable tracers and entered the equation stepwise to determine the sources of sediment. The results indicated that the andesite lithological units with interlayers of shale (An / Sh) and microfossilized limestone (Lim) with 56.91 and 30.54%, respectively, had the highest share in the sediment production in the study area.

Applications of sediment source fingerprinting studies are growing globally despite the high costs and workloads associated with the analyses of conventional fingerprint properties on target sediment samples collected using traditional methods. To this end, there is a need to test new fingerprint properties that can overcome these challenges. Sediment particle size could potentially contribute here since it is relatively easy to measure but, until now, has rarely been deployed as a fingerprint itself. Instead, particle size has been used to ensure that source and target sediment samples are more directly comparable on the basis of the fingerprints used. Accordingly, this work examined whether particle size distributions (PSDs) could be used as a reliable fingerprint for apportioning sediment sources, in combination with a grain size un‐mixing model. Application of PSDs as a fingerprint was tested at two scales: (i) in a laboratory setting where soil samples with known PSDs were used to generate artificial mixtures to evaluate un‐mixing model results, and (ii) a catchment setting comparing PSDs in a confluence‐based approach to test if downstream target sediment PSDs could be un‐mixed into the contributions of sediment coming from an upstream and a tributary sampling site. Laboratory results showed that the known proportions of the two, three and four soil samples in the artificial mixtures were predicted accurately using the AnalySize grain size un‐mixing model, giving average absolute errors of 9%, 8% and 6%, respectively. Catchment results showed variable performances when comparing un‐mixing results with sediment budget estimations, with the best results obtained at higher discharge values during storm runoff events. Overall, our results suggest the potential of using PSDs for estimating contributions of sediment sources delivering SS with distinct PSDs when sources are located at short distance to the downstream sampling site. [ABSTRACT FROM AUTHOR]

The Burntwood River (BR) and Upper Nelson River (UNR) are regulated rivers in the subarctic region of Canada. They merge at Split Lake and then discharge into Hudson Bay via the Lower Nelson River (LNR). The BR water discharge was increased eight‐fold by a cross‐watershed diversion in 1976. The UNR drains the 11th largest lake in the world, Lake Winnipeg, which itself receives discharge from a large North American Interior Plains watershed. Sediment loads and the source fingerprinting approach in these rivers were used to: (a) identify the sediment sources; (b) examine the impact of climate change and flow regulation on the BR and UNR sediment loads; and (c) assess the influence of Split Lake on downstream delivery of sediment into the LNR. Lake Winnipeg effectively decouples the UNR from the sediment sources in its prairie watershed. Fluvial riverbank and reservoir shoreline erosion in the UNR increased in the late 1990s, in response to a multi‐decadal increase in discharge forced by climate change in the Lake Winnipeg watershed. The BR sediment load was increased seven‐fold by diversion. Since diversion, flow regulation near the licenced limit has muted the response to variability in local precipitation and runoff; however, erosion processes independent from discharge (bank failures and subaerial processes) add variability in the sediment load record. Based on sediment budgeting, Split Lake conveys almost 80% of the BR and UNR sediment load into the LNR. The greater sediment load in the UNR (~1100 Gg year−1, compared to ~530 Gg year−1 from the BR) reveals that the UNR is the primary sediment source into the LNR, so that downstream sediment transport dynamics are more sensitive to the environmental changes in the UNR than to disturbances in the BR. Whether this may change in the future depends on changes in climate and engineering responses to increasing demand for hydroelectric power. [ABSTRACT FROM AUTHOR]

Purpose: Identifying best practices for sediment fingerprinting or tracing is important to allow the quantification of sediment contributions from catchment sources. Although sediment fingerprinting has been applied with reasonable success, the deployment of this method remains associated with many issues and limitations. Methods: Seminars and debates were organised during a 4-day Thematic School in October 2021 to come up with concrete suggestions to improve the design and implementation of tracing methods. Results: First, we suggest a better use of geomorphological information to improve study design. Researchers are invited to scrutinise all the knowledge available on the catchment of interest, and to obtain multiple lines of evidence regarding sediment source contributions. Second, we think that scientific knowledge could be improved with local knowledge and we propose a scale of participation describing different levels of involvement of locals in research. Third, we recommend the use of state-of-the-art sediment tracing protocols to conduct sampling, deal with particle size, and examine data before modelling and accounting for the hydro-meteorological context under investigation. Fourth, we promote best practices in modelling, including the importance of running multiple models, selecting appropriate tracers, and reporting on model errors and uncertainty. Fifth, we suggest best practices to share tracing data and samples, which will increase the visibility of the fingerprinting technique in geoscience. Sixth, we suggest that a better formulation of hypotheses could improve our knowledge about erosion and sediment transport processes in a more unified way. Conclusion: With the suggested improvements, sediment fingerprinting, which is interdisciplinary in nature, could play a major role to meet the current and future challenges associated with global change. [ABSTRACT FROM AUTHOR]

• Sediment sources prediction accuracy is high for no particle sorting. • Particle sorting caused low conservatism and prediction accuracy of five tracers. • Adding SOM correction factor could negatively affect model results. • Reliable result if source and sediment have consistent and narrow particle sizes. Sediment fingerprinting has proven highly efficient and rapid in identifying the sources and hotspots of sediment, thereby facilitating the targeted implementation of control measures. However, the unpredictable effect of particle sorting during sediment transport on source identification has increased the uncertainty associated with this method. Here, laboratory sieving experiments were carried out to simulate particle sorting during sediment transport. The conservatism of the five widely used tracers (geochemical elements, mid-infrared, near-infrared, visible, and color properties) and the accuracy of sediment source fingerprinting were investigated in the process of sorting. The results highlight that selected tracers exhibited high source contribution prediction accuracy (mean MAE 6.6 %) without particle sorting, with the exception of the color tracer. In contrast, the predictive ability of all tracers significantly reduced (mean MAE 16.2 %) in simulated particle sorting groups (especially for 125–31 μm) due to the enrichment of fine particles. Moreover, the correction factor failed to improve the accuracy of source contribution prediction in this study. The uncertainty caused by particle sorting can be effectively resolved by narrowing the source and sediment particle sizes to <63 μm (for all five tracers) or <31 μm (except for color tracer). This study contributes a deeper understanding of the role of particle size in sediment source fingerprinting, providing valuable insights to guide future tracer selection and associated particle size criteria. [ABSTRACT FROM AUTHOR]

Purpose: Understanding fluxes of soil organic carbon (OC) from the terrestrial to aquatic environments is crucial to evaluate their importance within the global carbon cycle. Sediment fingerprinting (SF) is increasingly used to identify land use-specific sources of OC, and, while this approach estimates the relative contribution of different sources to OC load in waterways, the high degree of spatial heterogeneity in many river catchments makes it challenging to precisely align the source apportionment results to the landscape. In this study, we integrate OC SF source apportionment with a carbon loss model (CLM) with the aim of: (i) reducing ambiguity in apportioning OC fluxes when the same land use exists in multiple locations within a catchment; and (ii) identifying factors affecting OC delivery to streams, e.g., buffer zones. Methods: Two main approaches were used in this study: (i) identification of the sources of freshwater bed sediment OC using n-alkane biomarkers and a Bayesian-based unmixing model; and (ii) modelling and analysis of spatial data to construct a CLM using a combination of soil OC content modelling, RUSLE soil erosion modelling and a connectivity index. The study was carried out using existing OC and n-alkane biomarker data from a mixed land use UK catchment. Results: Sediment fingerprinting revealed that woodland was the dominant source of the OC found in the streambed fine sediment, contributing between 81 and 85% at each streambed site. In contrast, CLM predicted that arable land was likely the dominant source of OC, with negligible inputs from woodland. The areas of the greatest OC loss in the CLM were predicted to be from arable land on steeper slopes surrounding the stream channels. Results suggest extensive riparian woodland disconnected upslope eroded soil OC and, concomitantly, provided an input of woodland-derived OC to the streams. It is likely the woodland contribution to streambed OC is derived from litter and leaves rather than soil erosion. Conclusion: This study demonstrates how location-specific OC sources and delivery processes can be better determined using sediment fingerprinting in combination with CLM, rather than using sediment fingerprinting alone. It highlights that, although wooded riparian buffer strips may reduce the impact of upslope, eroded soil OC on waterways, they could themselves be a source of OC to stream sediments through more direct input (e.g., organic litter or leaf debris). Characterising this direct woodland OC as a separate source within future fingerprinting studies would allow the contributions from any eroded woodland soil OC to be better estimated. [ABSTRACT FROM AUTHOR]

Soil erosion is especially severe in areas affected by intermittent heavy rainfalls after dry periods, and human practices such as deforestation. Mediterranean mountain environments underwent conversion of rangelands into croplands during the previous centuries to increase agricultural production but this process was reversed after land abandonment in the middle of the twentieth century allowing the natural revegetation. To understand the effect of the past practices and the current agricultural management, we have combined the strength of empirical data and spatially distributed modelling in a medium‐sized catchment representative of agroforestry landscapes of NE Spain. We developed an ensemble technique composed of 137Cs‐derived soil redistribution rates as specific point values and as grid‐based setup calibration for the WaTEM/SEDEM. Thus, we overcame the point specific limitation of the 137Cs measurement and the need for calibration of spatially distributed models that allow a spatial interpretation of soil redistribution in the catchment. We implemented an automated routine model tool to increase the calculation speed and calibrate the model thus, allowing estimates of the main model parameters for simulating a variety of temporal scenarios. With this method a good fit between modelled and measured soil redistribution rates (R2 = 0.82) was obtained (Nash–Sutcliffe efficiency: 0.79). Estimates were also consistent with the previous apportions of sediment provenance obtained by the fingerprinting technique. An increase of 300% in sediment export was predicted for the past scenario when most of the catchment was cultivated, while a reduction of 40% occurred in the future scenario of land abandonment. A high influence of input resolution was found, wherein model efficiency was reduced when pixel‐size was increased. Our study demonstrates that spatially distributed models combined with 137Cs‐derived rates provide a powerful tool to understand the driving factors of erosion and delineate the hotspot areas that could suffer high erosion if submitted to certain management practices. [ABSTRACT FROM AUTHOR]

Purpose: Evaluating sediment fingerprinting source apportionments with artificial mixtures is crucial for supporting decision-making and advancing modeling approaches. However, artificial mixtures are rarely incorporated into fingerprinting research and guidelines for model testing are currently lacking. Here, we demonstrate how to test source apportionments using laboratory and virtual mixtures by comparing the results from Bayesian and bootstrapped modeling approaches. Materials and methods: Laboratory and virtual mixtures (n = 79) with known source proportions were created with soil samples from two catchments in Fukushima Prefecture, Japan. Soil samples were sieved at 63 µm and analyzed for colorimetric and geochemical parameters. The MixSIAR Bayesian framework and a bootstrapped mixing model (BMM) were used to estimate source contributions to the artificial mixtures. In addition, we proposed and demonstrated the use of multiple evaluation metrics to report on model uncertainty, residual errors, performance, and contingency criteria. Results and discussion: Overall, there were negligible differences between source apportionments for the laboratory and virtual mixtures, for both models. The comparison between MixSIAR and BMM illustrated a trade-off between accuracy and precision in the model results. The more certain MixSIAR solutions encompassed a lesser proportion of known source values, whereas the BMM apportionments were markedly less precise. Although model performance declined for mixtures with a single source contributing greater than 0.75 of the material, both models represented the general trends in the mixtures and identified their major sources. Conclusions: Virtual mixtures are as robust as laboratory mixtures for assessing fingerprinting mixing models if analytical errors are negligible. We therefore recommend to always include virtual mixtures as part of the model testing process. Additionally, we highlight the value of using evaluation metrics that consider the accuracy and precision of model results, and the importance of reporting uncertainty when modeling source apportionments. [ABSTRACT FROM AUTHOR]

Purpose: Erosion and its spatial distribution in three agricultural headwater catchments were assessed in the border of the volcanic plateau in Southern Brazil. We analyzed terrain, hydrological processes, and land use influence to provide a comprehensive assessment of the catchments' sensitivity to erosion. Methods: Topographic attributes were acquired from a digital elevation map, WaterSed model was parameterized to simulate runoff, diffuse erosion, and sediment yield, and sediment source contributions were estimated using sediment fingerprinting based on near-infrared spectroscopy. Results: According to the modeled results, areas covered by crop fields, grasslands, and those adjacent to the drainage network are the most sensitive to erosion. Short distances from the source to the river network and the occurrence of high magnitude rainfall events (80 mm) promoted increases in connectivity for runoff/sediment transfer. Erosion simulations show that areas of low infiltration, such as unpaved roads, were important runoff generators during lower volume rainfall events (25 mm). Sediment fingerprinting provided satisfactory results to quantify the contributions of unpaved roads to sediment (~ 39%). Topsoil and stream channels were also significant sediment sources for the set of analyzed samples, corresponding to average contributions of 38 and 23%, respectively. Conclusion: Areas sharing geomorphological similarities did not lead to similar sediment contributions. Vegetation cover controlled erosion in topographically sensitive areas. Unpaved roads provide a significant sediment source, followed by topsoil and stream channels. The complementary results provide useful insights to better coordinate planning environmental conservation strategies in these fragile landscapes. [ABSTRACT FROM AUTHOR]

This study seeks to identify sediment sources, quantify erosion rates, and assess water quality status via sediment fingerprinting, the Modified Laser Erosion Bridge (MLEB) method, and various pollution indices (PIs), respectively, in the humid tropics (Malaysia). Geochemical elements were used as tracers in sediment fingerprinting. Erosion rates were measured at 3,241 points that encompass high conservation value forests (HCVFs); logged forests (LFs); mature oil palm (MOP); and mature rubber (MR) plantations. Annual erosion rates were 63.26–84.44, 42.38, 43.76–84.40, and 5.92–59.32 t ha−1 yr−1 in the HCVF, LF, MOP, and MR, respectively. Via sediment fingerprinting, logging and agricultural plantations were identified as the major contributors of the sediment. PIs also indicated the highest level of pollution in those catchments. This study highlighted three main messages: (i) the feasibility and applicability of the multiproxy sediment fingerprinting approach in identifying disaster-prone areas; (ii) the MLEB as a reliable and accurate method for monitoring erosion rates within forested and cultivated landscapes; and (iii) the adaptation of PIs in providing information regarding the status of river water quality without additional laboratory analyses. The combination of these approaches aids in identifying high-risk and disaster-prone areas for the prioritisation of preventive measures in the tropics. HIGHLIGHTS Sediment fingerprinting identified modifies landscapes and a major contributor of sediment in the tropics.; High erosion found in various tropical catchments such as in forests, rubber, and oil palm plantations.; Sediment pollution indices are useful and practical in indicating the health of a catchment system.;

The Fukushima nuclear accident in March 2011 generated a 3000 km$^{2}$ plume of soils heavily contaminated with $^{137}$Cs. Decontamination was completed early in 2019. Typhoon Hagibis was the first extreme event that occurred in the region after decontamination. Its impact on sediment sources and sediment $^{137}$Cs contamination was investigated through the application of a sediment fingerprinting procedure using spectrocolorimetry and geochemical properties. Sediment deposits ($n=24$) were collected in the Mano and Niida River catchments after the 2019 typhoons, and their signature was compared to that of potential sources (e.g., cropland, forests, and subsurface; $n=57$). Results demonstrate the dominance of cropland as the main source of sediment (mean: 54%) followed by forests (41%) with much lower contributions of subsurface material (5%). Overall, $^{137}$Cs concentrations in sediment were on average 84%–93% lower than the levels recorded after the accident in 2011, which demonstrates the effectiveness of cropland decontamination.

Sediment management is currently limited by uncertainties in the applicability of existing radionuclide tracers and the effects of urbanization. Here, we use plutonium isotopes (239+240Pu) from weapons‐testing fallout to trace sediment transport across five watersheds in an urbanizing landscape in Kansas, USA. Historic flooding in the region provided an opportunity to assess extreme connectivity of sediment sources. 239+240Pu activity of transported sediment decreased as catchments urbanized, indicating a greater contribution from subsurface bank sediment; Bayesian modeling predicted 50% (8%–80%) bank sourcing in the most rural watershed, which rose to 93% (73%–100%) in the most urban catchment. 239+240Pu activity provides explanatory information on the superposition of sediment sources, which is beyond that given by traditional organic and geochemical tracers that primarily infer vegetative and geologic sourcing, respectively. Our study demonstrates the utility of 239+240Pu as a sediment tracer for managing erosion under anthropogenic change. Plain Language Summary: Sediment is one of the most common contaminants in rivers around the globe. The susceptibility of soil to erosion increases as humans convert natural landscapes into rural and urban systems. Uncertainties remain regarding how urbanization alters sediment pathways and what tools are appropriate for quantifying this alteration. Radioactive isotopes, generated from nuclear weapons testing in the 1950s, have proven useful in this regard, although the most prominent tracer, for example, cesium, is losing some utility due to a short half‐life and extensive radioactive decay. We suggest that plutonium isotopes, which have longer half‐lives, are a viable option for tracing sediment in modern landscapes. Plutonium results suggest that in rural basins the source of sediment transitions from upland soil during low‐flows to bank material at high‐flows. On the other hand, urban streams always deliver bank sediment, regardless of storm intensity. Our study demonstrates the utility of plutonium as an alternate sediment tracer and highlights how urbanization changes the pathways and mechanisms of fluvial sediment transport. Key Points: 239+240Pu activity is a robust tracer for describing sediment sources and fluvial mixtures in a rapidly urbanizing landscapeFrequentist and Bayesian models were consistent in estimating increased bank erosion with increasing urban land useSediment sourcing is dependent on discharge in rural watersheds whereas it is independent of discharge in urban watersheds [ABSTRACT FROM AUTHOR]

Purpose: This study tests the feasibility of using a submersible spectrophotometer as a novel method to trace and apportion suspended sediment sources in situ and at high temporal frequency. Methods: Laboratory experiments were designed to identify how absorbance at different wavelengths can be used to un-mix artificial mixtures of soil samples (i.e. sediment sources). The experiment consists of a tank containing 40 L of water, to which the soil samples and soil mixtures of known proportions were added in suspension. Absorbance measurements made using the submersible spectrophotometer were used to elucidate: (i) the effects of concentrations on absorbance, (ii) the relationship between absorbance and particle size and (iii) the linear additivity of absorbance as a prerequisite for un-mixing. Results: The observed relationships between soil sample concentrations and absorbance in the ultraviolet visible (UV–VIS) wavelength range (200–730 nm) indicated that differences in absorbance patterns are caused by soil-specific properties and particle size. Absorbance was found to be linearly additive and could be used to predict the known soil sample proportions in mixtures using the MixSIAR Bayesian tracer mixing model. Model results indicate that dominant contributions to mixtures containing two and three soil samples could be predicted well, whilst accuracy for four-soil sample mixtures was lower (with respective mean absolute errors of 15.4%, 12.9% and 17.0%). Conclusion: The results demonstrate the potential for using in situ submersible spectrophotometer sensors to trace suspended sediment sources at high temporal frequency. [ABSTRACT FROM AUTHOR]

Soil resources in parts of Tanzania are rapidly being depleted by increased rates of soil erosion and downstream sediment transport, threatening ecosystem health, water and livelihood security in the region. However, incomplete understanding to what effect the dynamics of soil erosion and sediment transport are responding to land‐use changes and climatic variability are hindering the actions needed to future‐proof Tanzanian land‐use practices. Complementary environmental diagnostic tools were applied to reconstruct the rates and sources of sedimentation over time in three Tanzanian river systems that have experienced changing land use and climatic conditions. Detailed historical analysis of sediment deposits revealed drastic changes in sediment yield and source contributions. Quantitative sedimentation reconstruction using radionuclide dating showed a 20‐fold increase in sediment yield over the past 120 years. The observed dramatic increase in sediment yield is most likely driven by increasing land‐use pressures. Deforestation, cropland expansion and increasing grazing pressures resulted into accelerating rates of sheet erosion. A regime shift after years of progressive soil degradation and convergence of surface flows resulted into a highly incised landscape, where high amounts of eroded soil from throughout the catchment are rapidly transported downstream by strongly connected ephemeral drainage networks. By integrating complementary spatial and temporal evidence bases, this study demonstrated links between land‐use change, increased soil erosion and downstream sedimentation. Such evidence can guide stakeholders and policy makers in the design of targeted management interventions to safeguard future soil health and water quality. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the relative contribution of sub-basin resources to sediment production by using magnetic susceptibility data as the tracer in Chehelgazi catchment, Sanandaj. For this purpose, 20 samples of the output 5 sub-basins were measured by harvesting and magnetic susceptibility. Kruskal-Wallis test results showed that in all three trackings, frequency high, low and dependent, at least two sources had the ability to differentiate. In the second step, the three tracers were tested on the discriminant analysis by the sub-basin source and two tracers with different power splitters showed the high frequency of 88% and the frequency dependence of 12%; power splitters both tracers together in the sub-basin splitters was 90%, so they were selected as the optimal combination; therefore, they have the capability to determine the relative contribution model of sediment. The results of Bayesian uncertainty model also indicated Todarsamadi sub-basin with 44.4% of the largest contribution and Doveyseh, Chatan and Cherendo sub-basins with 35.5, 7.9 and 4.5, respectively, and Madian Dol sub-basin with 4/4 percent had the lowest contribution to sediment production. Based on the available results, Todarsamadi and Doveyseh sub-basins had the highest amount of sediment production; so these results could be used in soil conservation and management planning.

Phytoliths are plant microfossils commonly used as qualitative archive markers in archaeological and paleoecological studies. Their potential uniqueness to the vegetation cover, robustness to weathering, and lack of chemical alteration along the transport paths make them potentially suitable tracers for quantitative erosion studies. In this pilot study, we explore the potential of phytoliths in a sediment fingerprinting study in the Ceguera catchment (28 km2) in NE Spain. The phytolith concentrations and morphologies of four land cover classes (agricultural land, badland, forest, and shrubland) were analysed, and their contributions to four natural sediment mixture samples along the river course were modelled. Phytolith concentrations allowed us to discriminate sources sufficiently, albeit with limited sample size. The performance of the phytoliths as tracer was tested by reproducing the sources of artificial sediment mixture samples with satisfactory recall ratio. Results identified badlands to be the main contributor, with 84–96% of the sediment load to the sinks, followed by shrublands (median 5%) and agricultural lands (median 2%). These major findings can be reproduced by other conventional erosion studies from this area, indicating that phytoliths are suited to quantifying erosion patterns in mesoscale catchments. [ABSTRACT FROM AUTHOR]

Purpose: Wildfires can have major impacts on water scarcity and water quality linked to off-site transfer of polluting ash and nutrients. Understanding sediment sources in burnt landscapes can help to develop mitigation strategies, especially in catchments planted with introduced species that are prone to fire. We investigated sediment sources activated by post-fire rainfall in a small-forested catchment that was impacted by a severe wildfire. The aim was to use environmental radionuclides and elemental geochemistry as tracers to apportion sediment sources within burnt plantation systems. Methods: Surficial (0–2 cm) topsoil (n = 9), sub-surficial (2–4 cm) topsoil (i.e. below the burnt layer; n = 8) samples from burnt hillslopes and forest roads (n = 5) and stream banks (n = 5) soil samples were taken in the Quivolgo catchment, El Maule region, Chile. Sediment samples (n = 9) were collected from behind a v-notched weir on three dates after the fire: May 2017, July 2017 and October 2017. Soil and sediment samples were analysed by gamma spectrometry and wavelength-dispersive X-ray fluorescence (WD-XRF) used to obtain tracer properties. These were evaluated visually and statistically to identify potential non-conservative tracers. Sediment apportionment was undertaken using the MixSIAR mixing model. Results: The tracer selection procedure resulted in ten tracers being used for sediment apportionment. Tracer suitability was based on (i) weak and non-significant linear relationship between tracer concentrations and specific surface area (SSA) and soil organic matter (SOM), and (ii) conservative behaviour supported by the inclusion of sediment samples within source convex hull. Sediments from sub-surface layer (2–4 cm) were the dominant source during the first two periods contributing 55 ± 11 and 78 ± 10% respectively, whereas road contribution was only important in the last period (71 ± 14%). Apportionment showed a shift in sediment source (i.e. from forest roads to hillslopes) compared to a previous study in the same catchment before wildfire. The main driver of erosion was attributed to overland flow convergence and consequent rill erosion across burnt hillslopes. Conclusion: The study demonstrated combined use of environmental radionuclides with elemental geochemistry for sediment apportionment within burnt forest plantations and highlighted a switch in predominant source (e.g. sub-surface burnt soil) activated by post-fire rainfall events. The findings in this research will help forest companies to develop strategies to reduce off-site impacts of sediment release after wildfire in forest plantations. [ABSTRACT FROM AUTHOR]

Understanding the origins of sediment transport in river systems is crucial for effective watershed management, especially after catastrophic events. This information is essential for the development of integrated strategies that guarantee water security in river basins. The present study aimed to investigate the rupture of the B1 tailings dam of the Córrego do Feijão mine, which drastically affected the Brumadinho region (Minas Gerais, Brazil). To address this issue, a confluence-based sediment fingerprinting approach was developed through the SedSAT model. Uncertainty was assessed through Monte Carlo simulations and Mean Absolute Error (MAE). Estimates of the overall average contributions of each tributary were quantified for each station and annually during the period 2019–2021. It was observed that the sampling point PT-09, closest to the dam breach, contributed to almost 80% of the Paraopeba River in 2019. Despite the dredging efforts, this percentage increased to 90% in 2020 due to the need to restore the highly degraded area. Additionally, the main tributaries contributing to sediment increase in the river are Manso River "TT-03" (almost 36%), associated with an area with a high percentage of urban land use, and Cedro stream "TT-07" (almost 71%), whose geology promotes erosion, leading to higher sediment concentration. Uncertainties arise from the limited number of available tracers, variations caused by dredging activities, and reduced data in 2020 due to the pandemic. Parameters such as land use, riparian vegetation degradation, downstream basin geology, and increased precipitation are key factors for successfully assessing tributary contributions to the Paraopeba River. The obtained results are promising for a preliminary analysis, allowing the quantification of key areas due to higher erosion and studying how this disaster affected the watershed. This information is crucial for improving decision-making, environmental governance, and the development of mitigating measures to ensure water security. This study is pioneering in evaluating this methodology in watersheds affected by environmental disasters, where restoration efforts are ongoing. [Display omitted] • The confluence-based sedimentary footprint developed after the dam breach. • The dilution factor of the tributaries is key to the dilution of sediments. • The River stands out due to its anthropogenic input. • The Cedar Stream has contributions due to its geology. • The drains carried out confirm the effectiveness of pollution control. [ABSTRACT FROM AUTHOR]

The 20 km2 Galabre catchment belongs to the French network of critical zone observatories (OZCAR; Gaillardet et al., Vadose Zone Journal, 2018, 17(1), 1–24). It is representative of the sedimentary lithology and meteorological forcing found in Mediterranean and mountainous areas. Due to the presence of highly erodible and sloping badlands on various lithologies, the site was instrumented in 2007 to understand the dynamics of suspended sediments (SS) in such areas. Two meteorological stations including measurements of air temperature, wind speed and direction, air moisture, rainfall intensity, raindrop size and velocity distribution were installed both in the upper and lower part of the catchment. At the catchment outlet, a gauging station records the water level, temperature and turbidity (10 min time‐step). Stream water samples are collected automatically to estimate SS concentration‐turbidity relationships, allowing quantification of SS fluxes with known uncertainty. The sediment samples are further characterized by measuring their particle size distributions and by applying a low‐cost sediment fingerprinting approach using spectrocolorimetric tracers. Thus, the contributions of badlands located on different lithologies to total SS flux are quantified at a high temporal resolution, providing the opportunity to better analyse the links between meteorological forcing variability and watershed hydrosedimentary response. The set of measurements was extended to the dissolved phase in 2017. Both stream water electrical conductivity and major ion concentrations are measured each week and every 3 h during storm events. This extension of measurements to the dissolved phase will allow progress in understanding both the origin of the water during the events and the partitioning between particulate and dissolved fluxes of solutes in the critical zone. All data sets are available at https://doi.osug.fr/public/DRAIXBLEONE_GAL/index.html. [ABSTRACT FROM AUTHOR]

This study seeks to identify sediment sources, quantify erosion rates, and assess water quality status via sediment fingerprinting, the Modified Laser Erosion Bridge (MLEB) method, and various pollution indices (PIs), respectively, in the humid tropics (Malaysia). Geochemical elements were used as tracers in sediment fingerprinting. Erosion rates were measured at 3,241 points that encompass high conservation value forests (HCVFs); logged forests (LFs); mature oil palm (MOP); and mature rubber (MR) plantations. Annual erosion rates were 63.26-84.44, 42.38, 43.76-84.40, and 5.92-59.32 t ha-1 yr-1 in the HCVF, LF, MOP, and MR, respectively. Via sediment fingerprinting, logging and agricultural plantations were identified as the major contributors of the sediment. PIs also indicated the highest level of pollution in those catchments. This study highlighted three main messages: (i) the feasibility and applicability of the multiproxy sediment fingerprinting approach in identifying disaster-prone areas; (ii) the MLEB as a reliable and accurate method for monitoring erosion rates within forested and cultivated landscapes; and (iii) the adaptation of PIs in providing information regarding the status of river water quality without additional laboratory analyses. The combination of these approaches aids in identifying high-risk and disaster-prone areas for the prioritisation of preventive measures in the tropics. [ABSTRACT FROM AUTHOR]

Sediment fingerprinting techniques are increasingly utilized across the globe to identify and quantify sources of sediment in catchments to assist adequate management and rehabilitation strategies. The technique generally includes classifying source groups, sampling sediment sources and sink zones, analysing tracers and applying statistical analyses to discriminate and quantify the contribution from sources. Although sediment fingerprinting has been used in southern African catchments, a contextual review of studies for the region does not exist. An overview is given of the basic methodological steps, including the tracers utilized in southern Africa, the history and main findings of the studies and recommendations for further research. There are many regions in southern Africa where this technique can still be implemented, especially erosion hotspots of Lesotho and Swaziland. Similar to regions elsewhere, the technique has not been standardized due to variability of erosion processes and causal factors in different environments. Several studies state that soil is the dominant erosion factor in South Africa, especially in catchments that consist of duplex and dispersive soils that are highly erodible. It is recommended that a tracer or set of tracers be found for these problem soils. Sediment fingerprinting has the potential to discriminate soils as potential sediment sources. [ABSTRACT FROM AUTHOR]