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Burullus lagoon is part of Egypt's protected area network. The lagoon serves as a reservoir for drainage water discharged from agricultural areas, and the lake's sediments provide a unique opportunity to record environmental behavior and reconstruct of the heavy metal contamination history. In the present study, the sediment chronology, sedimentation rates, and metal accumulation fluxes were estimated in four sediment cores using 210Pb dating models to evaluate how human activities have affected the coastal environment. Using the radioisotopes 210Pb and 137Cs, radiometric dating was carried out using gamma-ray spectrometry. At the Egypt Second Research Reactor (ETRR-2), the element concentrations were determined using the instrumented neutron activation analysis (INAA- k0 method). Our findings show that the constant rate of supply (CRS), which has been verified with the peak of artificial radionuclide 137Cs, is the best model performed for the chronology of Burullus Lagoon. The average sedimentation rate, according to 210Pb dating models, is 0.85 cm/year. The large variation in sedimentation rates, especially after the 1990s, is consistent with an increase in the anthropogenic flux of heavy metals. This may be led into a significant environmental problem such as reducing the size of the lake and degrading the quality the water in Burullus Lagoon. Enrichment factor (EF) of the studied elements displayed the following order: Cl > Ca > Na > Br > Zn > Ta > Ti > V > Cr > Sc > Mg > Mn > Fe > Hf which is higher than unity. Furthermore, the Nemerow pollution index (PI Nemerow) revealed that pollution was increasing in the direction of the drains and slightly polluted. Consequently, pollutant indices showed that urbanization and industrial development may have increased the depositional fluxes of the metals in sediments over time. [ABSTRACT FROM AUTHOR]

Argentina is a Latin American country which encounters soil degradation problems. The most productive regions have implemented conservative land practices (no-till). However, agricultural frontier has been displaced to marginal lands with arid and semiarid climates, with the consequent disappearance in many areas of native forest and land degradation. In this work, the fallout of gamma-emitting radionuclides, 137Cs and 7Be, was jointly used to assess changes in soil erosion in a recently converted semiarid ecosystem into agricultural land. 137Cs was utilized to estimate the erosion over the past 60 years, whereas 7Be was employed to estimate the erosion after the conversion of the area to cultivated land and soil tillage. For 137Cs the Proportional Model (PM), the Mass Balance Model II (MBMII) and the MODERN model were used, for 7Be the Profile Distribution Model (PDM) and the MODERN model were used. 137Cs indicates mean erosional rates of 8.2, 10.5 and 6.5 Mg ha−1 a−1, using MBMII, PM and MODERN, respectively, and that a soil layer between 0.5 and 0.8 mm was annually lost by erosion. By applying a 7Be tracer, we measured erosion rates of 2.4 and 3.3 Mg ha−1 (with PDM and Modern, respectively), indicating the loss of the upper 0.2 mm of soil. This erosion can be attributed to a few heavy rainfalls that occurred within the past 90 days. The results suggest that current land management practices have led to an increase in soil erosion. This could be attributed to the fact that the soil remains bare after crop harvest, which may compromise its conservation and future productivity. [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]

The aim of this work is to assess the impact of no-till based cropping system on soil erosion using two indicators. The experiment plot was under no-tillage (NT) for four years, adjacent to a plot under conventional tillage (CT) with same other management practices. The two used indicators are Le Bissonnais soil aggregates’ stability test and the activities of the fallout radionuclides (FRN) 7Be and 137Cs. For each radionuclide, the reference sites were identified and sampled using grid sampling approach and the study sites (the two plots) were sampled by applying a one-dimensional point transect sampling. Five samples were collected from each study site with 10m incre-ment. The results showed that the mean weighted diameter (MWD) was of 2.2 for the NT plot and 2.0 for the CT plot, this indicates a lower soil detachability under the no-till system. For the FRN results, the 7Be activity showed that the NT plot retained 79% of the reference site activity and the CT plot retained 54%. The 137Cs activity tests showed also that the NT plot retained more of reference site activity. The mass balance conversion models application to the FRN results showed that the no-till system generated 10% less soil erosion rate than the con-ventional tillage. The results showed that in spite of needing more than 4 years implementation for statistical significance, no-till helps reducing water erosion in the hilly agricultural lands of Northern Morocco.

ABSTRACTSoil erosion is a major global environmental problem. The objective of this paper is to review conventional and non-conventional-artificial radionuclide techniques for soil erosion assessment using secondary data. Data gathered reveal that accurate assessment of soil erosion rates is a pre-requirement for environmental planning and soil conservation strategies. Nevertheless, estimating rates of soil erosion is still challenging despite availability of numerous assessing methods. Many assessing methods were developed at localized scales therefore limited applications in other areas. This review compared effectiveness of different soil erosion assessing methods in different areas. Generally, soil erosion can be assessed by conventional methods and non-conventional methods e.g use of artificial fallout Radionuclide (FRNs). FRNs quantifie relatively long-term (>30 years) soil erosion and deposition, however, not suitable for short-term and individual soil erosion events. Conventional methods are associated with point data, do not provide information on spatial distribution, labor-intensive and require long monitoring periods. Assessing soil erosion method should be site-specific rather than generalizing. Therefore, there is no one take for all methods in assessing soil erosion but choice of a method to use should depend on prevailing climatic conditions, resources available and time period (short or long term) of erosion data required.

Soil mobilization has been investigated by means of fallout radionuclides (FRN) in a first‐order catchment of the Eastern Alps. Caesium‐137, 210Pbxs. (210Pb excess or unsupported fraction), and 241Am have been measured in soil samples collected from a pasture at about 2150 m above sea level. Combining pedological and radioactivity data, including mineral‐related radionuclides (primordial 40K and nuclides belonging to the 232Th and 238U decay chains), the distribution of FRNs, their spatial variability, vertical distribution, and relationships with pedological and topographical variables were assessed. Because of low activity concentration, it was not possible to use artificial long‐lived 241Am as a soil tracer, but preliminary results are encouraging. Inventories of 210Pbxs. and 137Cs have been converted into soil mobilization rates applying the MODERN model. Despite the gentle steepness and the absence of evident signs of erosion, the slopes of the considered catchment are affected by erosion at a rate up to 6 t ha−1 yr−1, likely related to grazing. A comparison between 210Pbxs. and 137Cs has revealed that at this site 137Cs, the most used FRN for estimating soil redistribution, is not suitable for this purpose, probably due to its irregular spatial distribution on snow‐covered ground after the Chernobyl accident. Conversely, 210Pbxs., owing to its continuous input, has provided reliable estimates of soil redistribution rates, in accordance with local morphology. The latter has in fact been related to morphometric variables in a regression model to provide an overview of soil erosion/sedimentation across the entire catchment, confirming that 210Pbxs. is a viable alternative to trace soil erosion and deposition where the Chernobyl fallout occurred on snow‐covered ground. [ABSTRACT FROM AUTHOR]

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]

Floodplain wetlands in agricultural river basins provide critical ecosystem services such as nutrient retention, flood mitigation, carbon sequestration and ecological habitats and are a key component of a nature‐based solution approach to restoration. In the context of the global challenge to reducing impact increasingly intensive food production on downstream ecosystems, restoration of wetlands in river floodplains offers a practical means for downstream retention and mitigation of P flux from upstream agricultural land. Data on short term, flood event related, accretion rates are, however, difficult to acquire via conventional monitoring yet such information is essential for restoration planning and scenario testing. Here, we evaluate a promising approach that applies naturally‐occurring short‐lived fallout radionuclide (FRN) 7Be as a tracer to quantify sediment and, by association, particulate phosphorus retention rates in restored floodplain wetlands. Following a series of major inundation events, a restored floodplain unit was sampled to determine 7Be inventories of the floodplain relative to an undisturbed reference site. This was undertaken in conjunction with direct measurement of sedimentation as an independent check of FRN results. Accretion rates up to 27 kg m−2 were recorded using 7Be for recent deposition events compared to a longer term annual average rate of ca. 6 kg m−2 derived from 137Cs measurements. While accretion rates varied spatially and temporally, there was excellent coherence between FRN‐based measurements and direct measurements once rigorous correction for particle size effects on tracer properties had been undertaken. The study demonstrates the important contribution that FRN technology can make to support wetland management and restoration initiatives and the essential need for a systems thinking approach across the soil‐sediment continuum. Such decision support tools will become increasingly important in the 21st century with growing anthropogenic pressure on aquatic ecosystems related to upstream food production, and implementation of more nature‐based solutions such as restored wetlands to counteract these pressures. [ABSTRACT FROM AUTHOR]

Research into sediment provenance identification in Antarctica is emerging as a relevant field of study, providing a unique insight into understanding geomorphological processes in extreme climatic environments. This study focusses on the mechanisms of sediment redistribution in the catchment of the Korabelny Stream, located at the western end of the Bellingshausen Ice Dome on King George Island (Shetland Islands). The catchment area of the stream covers 2.83 km2, with 1.17 km2 under the glacier. Two main sediment sources have been identified: a) the glacierized part, extending along the glacier edge and represented by a complex of moraine deposits lacking protective vegetation cover, along with part of the catchment under the glacier; b) the periglacial part, occupying territory with permafrost and a thin loose cover unevenly protected by early successional vegetation. We combine a tracer-based fingerprinting technique, sediment delivery estimates based on sediment flow connectivity index and geomorphological mapping to quantify the sources contribution to sediment yield. The proportional contribution of the glacierized part was 60–66 % of the total sediment yield based on two independent methods, suggesting the reliability of the results. It is noteworthy that sediment transport from the glacierized part exceeds that from the periglacial part. However, a significant portion of the sediment is redeposited in temporary reservoirs formed along the glacier edge and Lake Mesyats, located in the central part of the Korabelny Stream catchment. The main factor determining sediment yield in the catchment is the water reserves in snow at the beginning of the ablation season. In years when water reserves in snow significantly exceed long-term average values, such as observed in the austral summer of 2014–2015 when study was conducted, sediment yield was low. This is attributed to the faster melting of ice on the glacier compared to snow, due to differences in albedo. • First time, assessed sediment sources in small Maritime Antarctica catchment. • Two independent methods used to determine proglacial and periglacial contributions. • Proglacial part contributes significantly more to sediment runoff. • The higher snow water reserves at ablation start the lower proglacial sediment runoff. [ABSTRACT FROM AUTHOR]

Land-use and climate changes are the most environmental issues in the Hircanian Forest, Northern Iran. Valasht Lake is a mountainous basin desirable for studying sedimentation rates as off-site impacts of environmental changes. The research objective was to quantify the historical trend of sedimentation rate in response to anthropogenic and climate factors influencing the catchment of Valasht Lake. The sediment chronology performed using fallout radioisotopes (226Ra, 137Cs, and 210Pb) and the Constant Rate of Supply Model. The off-site impacts of the whole complies of land use changes including deforestation and climate change resulted in sediment flux into the Valasht Lake with a mean rate of 0.94 kg m−2 y−1, since 1864. The studied sediment profile shows three different sedimentation periods manifested by three specific sediment layers with a mean sedimentation rate of 0.25 ± 0.05 (1984–1964), 0.76 ± 0.17 (1964–2006), and 2.28 ± 0.7 (after 2006) kg m−2 yr−1. During the forming of layers, the annual sediment yield has been 50, 152, and 456 tonnes, which infers land degradation and an increase in flash flood frequency. The 210Pb dating method revealed extreme events of sediment deliveries, especially in 1963, 1983, 2002, 2007, and 2011–2019 years. Organic-rich mud deposits (TOC, 17.9 ± 4%) accumulated during the last period since 2006. It can be attributed to the increasing trend of burning the forest clear-cuts and ash flux into the lake. Integrated watershed management practices and desirable land-use planning are recommended to preserve the natural resources of Valasht Lake and its catchment. [ABSTRACT FROM AUTHOR]

Cryoconite has been demonstrated to be an efficient accumulator of some classes of contaminants on glaciers in both mountain and polar environments, however the accumulation of contaminants in cryoconite in Iceland has received very little attention to date. To understand the spatial variability of natural and anthropogenic fallout radionuclides and metals on glaciers in Iceland, we present the first study of this region including both cryoconite from three glaciers: Virkisjökull; Skaftafellsjökull; and Falljökull, together with moss balls ('glacier mice') from Falljökull. The cryoconite samples and glacier mice were analysed using XRF spectrometry to assess their elemental composition and gamma spectrometry to identify, and quantify, fallout radionuclides, primarily 7 Be, 137 Cs, 241 Am, excess 210 Pb, and 40 K. The results revealed that the cryoconite samples had similar compositions, influenced by local geology and natural sources of volcanic ash and dust. Higher concentrations of radionuclides and heavy metals were found in both cryoconite and glacier mice compared to control samples comprising nearby proglacial sediments. In comparison to other glaciers in the Northern Hemisphere, however, cryoconite from Icelandic glaciers contains some of the lowest activity concentrations of key radionuclides. Consequently, cryoconite deposits that are released and diluted during the melt and retreat of Icelandic glaciers are unlikely to be of environmental concern following transport to proglacial areas., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Caroline Clason reports financial support was provided by Quaternary Research Association., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Input of organic matter into stream channels is the primary energy source for headwater ecosystems and ultimately carbon to the oceans and hence is an important component of the global carbon cycle. Here, we quantify organic‐rich fine sediment mobilization, transport, and storage in a Strahler fourth‐order stream during individual intermediate‐sized storm events. By combining measurements of fallout radionuclides (FRNs) 7Be and 210Pb and stable water isotopes with a conceptual model of suspended load trapping by channel margins, we find that the channel bed was consistently a source of suspended load to the channel margins. Relative to storage on the channel margins, suspended load export increased through the spring and summer, perhaps related to the in‐channel decomposition of organic debris as indicated by its FRN exposure age and changing bulk δ13C composition. Trapping of suspended load by riparian margins limits sediment transport distances, which, given sufficient discharge to fully suspend the load, is nearly independent of stream discharge for sub‐bankfull discharges. Limited data indicate that the fractional size of the channel margins where trapping occurs decreases with increasing watershed area. Increasing transport length and decreasing fractional margin area with increasing watershed area results in a systematic downstream decoupling of the channel from local terrestrial organic matter exchange. These findings provide a framework for understanding suspended load dynamics in formerly glaciated regions where sediment production and fluxes are generally low and thus the annual input of organic debris is a major component of suspended load budget. Plain Language Summary: The decomposition of organic‐rich debris (leaves, twigs, etc.) within stream channels serves as an important organic carbon source to stream margins or banks. During moderate storm events, we observed that the channel bed was consistently a source of organic‐rich suspended load that is then trapped by the channel margins. Through spring and summer less of the suspended load is trapped by the margins, increasing the fraction of the suspended load exported. This decreased trapping and increased export may be related to changes in the character of the suspended load due to the in‐channel decomposition of organic debris. Trapping of suspended load by channel margins limits the transport distance of suspended load, systematically decoupling the channel from the channel margins with increasing watershed size. These findings provide a framework for understanding suspended load transport in formerly glaciated regions where the annual input of organic debris is a significant component of suspended load budget. Key Points: We observe seasonal variations in the ratio of suspended load exported from the watershed versus stored in channel marginsGreater fractional area of deposition along margins of headwaters facilitates trapping of suspended load that limits suspended load exportIncreasing transport length with increasing watershed area systematically decouples the channel from terrestrial organic exchange [ABSTRACT FROM AUTHOR]

Argentina is a Latin American country which encounters soil degradation problems. The most productive regions have implemented conservative land practices (no-till). However, agricultural frontier has been displaced to marginal lands with arid and semiarid climates, with the consequent disappearance in many areas of native forest and land degradation. In this work, the fallout of gamma-emitting radionuclides, 137 Cs and 7 Be, was jointly used to assess changes in soil erosion in a recently converted semiarid ecosystem into agricultural land. 137 Cs was utilized to estimate the erosion over the past 60 years, whereas 7 Be was employed to estimate the erosion after the conversion of the area to cultivated land and soil tillage. For 137 Cs the Proportional Model (PM), the Mass Balance Model II (MBMII) and the MODERN model were used, for 7 Be the Profile Distribution Model (PDM) and the MODERN model were used. 137 Cs indicates mean erosional rates of 8.2, 10.5 and 6.5 Mg ha -1 a -1 , using MBMII, PM and MODERN, respectively, and that a soil layer between 0.5 and 0.8 mm was annually lost by erosion. By applying a 7 Be tracer, we measured erosion rates of 2.4 and 3.3 Mg ha -1 (with PDM and Modern, respectively), indicating the loss of the upper 0.2 mm of soil. This erosion can be attributed to a few heavy rainfalls that occurred within the past 90 days. The results suggest that current land management practices have led to an increase in soil erosion. This could be attributed to the fact that the soil remains bare after crop harvest, which may compromise its conservation and future productivity.

Land degradation resulting from soil erosion is a global concern, with the greatest risk in developing countries where food and land resources can be limited. The use of fallout radionuclides (FRNs) is a proven method for determining short and medium-term rates of soil erosion, to help improve our understanding of soil erosion processes. There has been limited use of these methods in tropical Africa due to the analytical challenges associated with 137Cs, where inventories are an order of magnitude lower than in the Europe. This research aimed to demonstrate the usability of 239+240Pu as a soil erosion tracer in western Kenya compared to conventional isotopes 210Pb ex and 137Cs through the determination of FRN depth profiles at reference sites. Across six reference sites 239+240Pu showed the greatest potential, with the lowest coefficient of variation and the greatest peak-to-detection limit ratio of 640 compared to 5 and 1 for 210Pb ex and 137Cs respectively. Additionally, 239+240Pu was the only radionuclide to meet the 'allowable error' threshold, demonstrating applicability to large scale studies in Western Kenya where the selection of suitable reference sites presents a significant challenge. The depth profile of 239+240Pu followed a polynomial function, with the maximum areal activities found between depths 3 and 12 cm, where thereafter areal activities decreased exponentially. As a result, 239+240Pu is presented as a robust tracer to evaluate soil erosion patterns and amounts in western Kenya, providing a powerful tool to inform and validate mitigation strategies with improved understanding of land degradation. • Applicability to large scale studies where selecting reference sites is a challenge. • Determination of Pu is possible to greater depth using ICP-MS/MS analysis. • Improved coefficient of variation at reference sites for Pu compared to Pb and Cs. • The allowable error criteria for reference sites was only met for Pu isotopes. [ABSTRACT FROM AUTHOR]

High mountainous areas are geomorphologically active environments which are strongly shaped by redistribution of sediments and soils. With the projected climate warming in the twenty‐first century and the continued retreat of glaciers, the area of newly exposed, highly erodible sediments and soils will increase. This presents a need to better understand and quantify erosion processes in young mountainous soils, as an increase in erodibility could threaten human infrastructure (i.e. hydroelectric power, tourist installations and settlements). While soil development is increasingly well understood and quantified, a coupling to soil erosion rates is still missing. The aim of this study was, therefore, to assess how soil erosion rates change with surface age. We investigated two moraine chronosequences in the Swiss Alps: one in the siliceous periglacial area of Steingletscher (Sustenpass), with soils ranging from 30 a to 10 ka, and the other in the calcareous periglacial area of Griessgletscher (Klausenpass) with surfaces ranging from age of 110 a to 13.5 ka. We quantified the erosion rates using the 239+240Pu fallout radionuclides and compared them to physical and chemical soil properties and the vegetation coverage. We found no significant differences between the two parent materials. At both chronosequences, the erosion rates were highest in the young soils (on average 5−10 t ha‐1 a‐1 soil loss). Erosion rates decreased markedly after 3−5 ka of soil development (on average 1−2.5 t ha‐1 a‐1 soil loss) to reach a more or less stable situation after 10−14 ka (on average 0.3–2 t ha‐1 a‐1). Climate change not only causes glacier retreat, but also increased sediment dynamics. Depending on the relief and vegetational development, it takes up to at least 10 ka to reach soil stability. The establishment of a closed vegetation cover with dense root networks seems to be the controlling factor in the reduction of soil erodibility. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Concurrent with the Chernobyl accident along the explosions caused by nuclear tests and advances in nuclear sciences, researchers around the world have been trying to examine the potential of fallout radionuclides for accurate estimation of soil erosion and redistribution. The inadequacy of the existence of radionuclides and the complexity of factors affecting the amount of these elements in soil are among the important limiting factors in usage of radionuclide materials in soil erosion studies. As the most widely used radionuclides in soil erosion studies, 137Cs and 210Pb come from two different origins of anthropogenic and geogenic, respectively. Since the 137Cs and 210Pbexcess reach the soil surface mainly through precipitation, the climate and latitude play important roles on the existence of radionuclides in the soil. Due to the location of the point sources of 137Cs, the coordinates of the site under consideration and the wind regimes can also be very important to affect the precipitation and consequently, the inventories of 137Cs. Awareness of the range of possible changes of 137Cs and 210Pbexcess in undisturbed soil is an important step to improve and validate soil erosion estimation results. Accordingly, the present research reviews the data of the mean annual precipitation and inventory of 137Cs and 210Pbexcess in undisturbed soil and presents some regression equations for different climates and latitudinal zones of the world. Based on the results, the inventory of 137Cs in undisturbed soil can be estimated statistically acceptable only in two latitudinal zones of 16°–25° N and 26°–35° N. While due to the small amount of data and the impossibility of data separation for different zones and climates, the inventory of 210Pbexcess can be estimated statistically acceptable given all the data without considering the latitudinal zones. The estimations of the inventories of 137Cs and 210Pbexcess in undisturbed soil is statistically acceptable in two temperate and continental climates and only temperate climate, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The need for further research to investigate the possibility of using 7Be as a soil erosion tracer under a range of climatic conditions, specifically in arid and semi-arid agro-environments, has been emphasised in the literature. In this context, this paper reports research conducted in two semi-arid areas located in Western Iran and Southern Italy in order to assess the potential of using 7Be measurements for estimating soil erosion over short timescales. Materials and methods: The two study sites differ in terms of land use. More specifically, the area in Western Iran, under cultivation, is cropped mostly under wheat, barley and pea rotation. The area in Southern Italy has never been cultivated, has few eucalyptus trees, resulting from re-afforestation conducted in 1966 and retains a sparse grass cover. Soil sampling required two field campaigns undertaken in April 2011 and April 2016 in Western Iran and Southern Italy, respectively. Results and discussion: In Western Iran, the 7Be reference inventory was estimated at 326 ± 40 Bq m−2 and the corresponding value of the shape factor was equal to 3.57 kg m−2. The soil loss was calculated to be 6.8 Mg ha−1, resulting in a Sediment Delivery Ratio (SDR) of ca. 80%. In Southern Italy, the 7Be reference inventory was equal to 180 ± 20 Bq m−2, emphasising a lower penetration of 7Be into the soil that is documented by a lower value of the shape factor (2.45 kg m−2). The overall results provided a net soil loss of ca. 20.7 Mg ha−1. In this case, no deposition was documented and a SDR value of ca. 100% was calculated. Conclusion: The magnitude of soil erosion reflects, for both sites, the steep topography, the different management system and the heavy rainfall occurring during a period that coincides with the absence of vegetative cover. The results obtained in this study are in line with similar studies carried out in other countries and suggest that, in cultivated areas, care must be taken when traditional cultivation systems are applied; in re-afforested areas, the presence of a uniform vegetative cover is crucial in protecting soil from erosion. However, there still is a need for further work to assess the feasibility of using 7Be in different areas and under different land uses or vegetation covers. Also, further refining of the conversion model, which is based here on the simple exponential function, are still possible. [ABSTRACT FROM AUTHOR]

Soil erosion causes worldwide land degradation. Long-term monitoring of soil erosion is costly and labor-intensive. Multiple models using 137Cs fallout are developed to retrospectively estimate average soil erosion rates since 1954. However, these models have not been rigorously validated due to the lack of compatible long-term measured soil loss data, and thus their usefulness has been seriously questioned. Compared with 62 years of rare soil loss data measured in two small watersheds of <0.78 ha during 1954 and 2015, all theoretical models (Eqs. (5)–(13)) resulted in overestimations of mean net soil erosion rates by at least 400%. A key assumption of the homogeneous 137Cs transfer from rainwater to the soil profile during fallout is invalid, and a critical process of the enhanced 137Cs loss and redistribution during transfer is overlooked. Based on two independent studies, the enhanced 137Cs uptake by suspended sediment during transfer was responsible for about 8 times more enriched 137Cs loss in sediment, to which 137Cs inventory and erosion estimation are extremely sensitive. More experiments are needed to investigate whether this enhanced loss ratio varies with soil texture, rainfall intensity, and slope steepness. A new mass balance model is developed to include the dynamic uptake of 137Cs by suspended sediment in surface runoff and losses of 137Cs in both runoff solution and uptake by plants. The new model greatly improves mean net soil erosion estimation with a mean relative error of 33%, which is comparable with those of the empirical models (Eqs. (2)–(4)). The finding of enhanced radionuclide loss with suspended sediment during transfer is, in theory, valid for other continuous fallout radionuclides such as 210Pb and 7Be, which have been widely used in soil erosion estimation. Taking into account the enhanced radionuclide loss by suspended sediment during fallout will substantially lower the soil loss estimation for all fallout radionuclides. • Central assumption of homogeneous 137Cs transfer from rainwater to soil is false. • Enriched 137Cs loss and redistribution by suspended sediment occur during transfer. • All existing theoretical models overestimate soil loss rates due to false assumptions. • A new model including the enhanced 137Cs loss greatly improves soil loss estimates. • Enhanced loss by suspended sediment is applicable to all fallout radionuclides. [ABSTRACT FROM AUTHOR]

Atmospheric deposition on glaciers is a major source of legacy fallout radionuclides (FRNs) accumulating in cryoconite, a dark granular material with surface properties that efficiently bind FRN contaminants (specifically 137Cs; 210Pb; 241Am). Cryoconite-bound FRNs in glaciers can be released when they interact with and are transported by glacial meltwater, resulting in the discharge of amassed particulate contaminants into aquatic and terrestrial environments downstream. The environmental consequences of FRN release from the cryosphere are poorly understood, including impacts of cryoconite-sourced FRNs for alpine food chains. Consequently, there is limited understanding of potential health risks to humans and animals associated with the consumption of radiologically-contaminated meltwater. To assess the chemical availability of cryoconite-adsorbed FRNs we used a three-stage sequential chemical extraction method, applied to cryoconite samples from glaciers in Sweden and Iceland, with original FRN activity concentrations up to 3300 Bq kg−1 for 137Cs, 10,950 Bq kg−1 for unsupported 210Pb (210Pb un) and 24.1 Bq kg−1 for 241Am, and orders of magnitude above regional backgrounds. Our results demonstrate that FRNs attached to cryoconite are solubilized to different degrees, resulting in a stage-wise release of 210Pb un involving significant stepwise solubilization, while 137Cs and 241Am tend to be retained more in the particulate phase. This work provides an insight into the vulnerability of pristine glacial environments to the mobilization of FRN-contaminated particles released during glacier melting, and their potential impact on glacial-dependent ecology. • Fallout radionuclides are commonly found at high concentrations in cryoconite on glaciers. • Sequential chemical extractions were performed on cryoconite to assess fallout radionuclide mobility. • FRNs are attached to cryoconite on differing adsorption sites, giving rise to variable responses. [ABSTRACT FROM AUTHOR]

Due to changing climate and irregular weather patterns, event-based soil loss and sediment yield have become important issues in the agricultural areas. Several mathematical models and prediction methodologies have been used to estimate event-based soil loss and soil redistribution based on soil types, land management, hydrology and local topography. The use of short-lived beryllium-7 as a means of estimating event-based soil erosion/deposition rates has become an alternative to the traditional soil loss measurement methods. A new erosion model taking into account the movement of 7Be in soils has been presented recently. In order to direct the attention to the potential offered by this technique (measurements and mathematical model), a two-year study was performed at the erosion plots in Müncheberg, Germany, and twelve individual erosion rates were estimated. This paper presents a systematic comparison of the non-steady state 7Be model with the process-based erosion model EROSION-3D and measured data. The results demonstrate a close consistency between the erosion rates estimated by erosion models and the estimates provided by the 7Be model and can therefore be seen as a promising contribution to validating the use of this radionuclide to document short-term soil redistribution within the plot and deposited sediment at the bottom of the plot.

The accumulation of fallout radionuclides (FRNs) from nuclear weapons testing and nuclear accidents has been evaluated for over half a century in natural environments; however, until recently their distribution and abundance within glaciers have been poorly understood. Following a series of individual studies of FRNs, specifically 137 Cs, 241 Am and 210 Pb, deposited on the surface of glaciers, we now understand that cryoconite, a material commonly found in the supraglacial environment, is a highly efficient accumulator of FRNs, both artificial and natural. However, the variability of FRN activity concentrations in cryoconite across the global cryosphere has never been assessed. This study thus aims to both synthesize current knowledge on FRNs in cryoconite and assess the controls on variability of activity concentrations. We present a global database of new and previously published data based on gamma spectrometry of cryoconite and proglacial sediments, and assess the extent to which a suite of environmental and physical factors can explain spatial variability in FRN activity concentrations in cryoconite. We show that FRNs are not only found in cryoconite on glaciers within close proximity to specific sources of radioactivity, but across the global cryosphere, and at activity concentrations up to three orders of magnitude higher than those found in soils and sediments in the surrounding environment. We also show that the organic content of cryoconite exerts a strong control on accumulation of FRNs, and that activity concentrations in cryoconite are some of the highest ever described in environmental matrices outside of nuclear exclusion zones, occasionally in excess of 10,000 Bq kg -1 . These findings highlight a need for significant improvements in the understanding of the fate of legacy contaminants within glaciated catchments. Future interdisciplinary research is required on the mechanisms governing their accumulation, storage, and mobility, and their potential to create time-dependent impacts on downstream water quality and ecosystem sustainability., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Caroline Clason reports financial support was provided by INTERACT. Caroline Clason reports financial support was provided by Quaternary Research Association. Ewa Poniecka reports financial support was provided by Natural Environment Research Council. Ewa Poniecka reports travel was provided by National Science Foundation. Philip Owens reports financial support was provided by Natural Sciences and Engineering Research Council of Canada. Philip Owens reports financial support was provided by Forest Renewal British Columbia. Edyta Lokas reports financial support was provided by National Science Centre Poland., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

The use of atmospheric fallout radionuclides as sediment tracers can provide valuable information on sediment transport processes within watersheds. Research was conducted in cropland and mixed land use subwatersheds of the Pleasant Valley watershed (50 km2) in south-central Wisconsin to identify sources of suspended sediment using cesium-137 (137Cs) and excess lead-210 (210Pbxs). In the cropland-dominated subwatershed, contributions to suspended sediment from in-stream and agricultural sources ranged from 36% to 81% and from 19% to 64%, respectively. In the mixed land use subwatershed, contributions to suspended sediment from in-stream and agricultural sources ranged from 68% to 100% and from 0% to 32%, respectively. The relative contribution to suspended sediment from agricultural sources was greater in the cropland subwatershed compared to the mixed land use subwatershed. The phosphorus (P) concentration in suspended sediment and fine sediment deposited on the streambed varied from 601 to 1545 mg kg-1, and cropland areas were the dominant sources of P-enriched sediment in streams. The legacy P and sediment in this watershed can result in a lag time between implementation of best management practices and attainment of desired water quality improvement. Depending on the fingerprinting properties considered (metals vs. fallout radionuclides) and suspended sediment source considerations, the source apportionment results may vary. [ABSTRACT FROM AUTHOR]

Knowledge of spatial structures of the radionuclides 137 Cs and unsupported 210 Pb ( 210 Pb ex ) is vital for developing sound sampling designs that are crucial for deriving quantitative soil erosion estimates. The objectives are to characterize spatial structures of 137 Cs and 210 Pb ex inventories at small spatial scales under different land uses, and to quantify the effects of core sizes on (1) estimated sample means and variances of the 137 Cs and 210 Pb ex inventories and (2) sample numbers required for estimating the mean inventories at a given confidence level. Three different core sizes were used to take soil samples along three 10-m transects at 0.25-m or 0.5-m intervals for each land use. Land uses included cropland, grassland, forestland, and rangeland. 330 samples were analyzed for 137 Cs and 210 Pb ex inventories. Semivariograms were obtained by plotting empirical semivariances with sample separation distances. The spatial correlation distances ranged from 0.2 to 0.75 m for most cases. The semivariances at the separation distances of >0.75 m were close to the variances of the fields for all four land uses, indicating that the spatial distributions of 137 Cs and 210 Pb ex were nearly stationary and had little spatial dependence at scales between 0.75 and 5 m. The overall results suggested that samples taken at a separation distance of >0.75 m would be largely independent and could be composited to form a representative sample for the sampling location for most cases. Given the large spatial variability at such a small scale, quantitative soil erosion rates cannot be estimated for a single soil core, because remarkably different soil erosion rates can be estimated for soil cores taken within a meter. Core size variation between 38 mm and 86 mm has no apparent effect on estimating sample means and sample standard deviations of 137 Cs and 210 Pb ex inventories, except for gravely soils. In general, 15–30 samples are needed to estimate 137 Cs reference inventory on reference sites, but may be more for gravely soils. More samples are required for forest and cultivated sites than for uncultivated grassland sites. On measuring sites, it is strongly recommended that 5–15 samples be taken for a grid point and measured individually if feasible or as a combined sample to allow reliable estimation of the mean 137 Cs inventory for the location for most soils and land uses. If samples are taken for each of uniformly eroded land form units, the same number of individual samples as on the reference site are recommended. This work will be useful to improving sampling designs and consequently the accuracy of soil erosion estimation of the 137 Cs technique. [ABSTRACT FROM AUTHOR]

Landscapes and soils evolve in non‐linear ways over millennia. Current knowledge is incomplete as only average denudation (or erosion) rates are normally estimated, neglecting the temporal discontinuities of these processes. The determination of regressive and progressive phases of soil evolution is important to our understanding of how soils and landscapes respond to environmental changes. The Sila Massif (Italy) provides a well‐defined geomorphological and geological setting to unravel temporal variations in soil redistribution rates. We used a combination of in situ cosmogenic radionuclide measurements (10Be) along tor (residual rock) height profiles, coupled with fallout radionuclides (239+240Pu) in soils, to model soil denudation rates over the last 100 ka. We measured rates prior to the Last Glacial Maximum (LGM) of ≤30 t km−2 yr−1 (~0.036 mm yr−1). Following the LGM, during the transition from the Pleistocene to the Holocene, these rates increased to ~150–200 t km−2 yr−1 and appeared to be above soil production rates, causing regressive soil evolution. For the last ~50 years, we even describe erosion rates of ≥1,000 t km−2 yr−1 (~1.23 mm yr−1) and consider human impact as the decisive factor for this development. Consequently, the natural soil production rates cannot cope with the current erosion rates. Thus, a distinct regressive phase of soil formation exists, which will give rise to shallowing of soils over time. Overall, our multimethod approach traced denudation and erosion histories over geologic and human timescales and made a new archive to soil science and geomorphology accessible. [ABSTRACT FROM AUTHOR]

Cryoconite is a specific type of material found on the surface of glaciers and icesheets. Samples of cryoconite were collected from the Orwell Glacier and its moraines, together with suspended sediment from the proglacial stream on Signy Island, part of the South Orkney Islands, Antarctica. The activity concentrations of certain fallout radionuclides were determined in the cryoconite, moraine and suspended sediment, in addition to particle size composition and %C and %N. For cryoconite samples (n = 5), mean activity concentrations (±1SD) of 137Cs, 210Pb un and 241Am were 13.2 ± 20.9, 66.1 ± 94.0 and 0.32 ± 0.64 Bq kg−1, respectively. Equivalent values for the moraine samples (n = 7) were 2.56 ± 2.75, 14.78 ± 12.44 and <1.0 Bq kg−1, respectively. For the composite suspended sediment sample, collected over 3 weeks in the ablation season, the values (± counting uncertainty) for 137Cs, 210Pb un and 241Am were 2.64 ± 0.88, 49.2 ± 11.9 and <1.0 Bq kg−1, respectively. Thus, fallout radionuclide activity concentrations were elevated in cryoconite relative to moraine and suspended sediment. In the case of 40K, the highest value was for the suspended sediment (1423 ± 166 Bq kg−1). The fallout radionuclides in cryoconite were 1–2 orders of magnitude greater than values in soils collected from other locations in Antarctica. This work further demonstrates that cryoconite likely scavenges fallout radionuclides (dissolved and particulate) in glacial meltwater. In the case of 40K, the greater value in suspended sediment implies a subglacial source. These results are amongst the relatively few that demonstrate the presence of fallout radionuclides in cryoconites at remote locations in the Southern Hemisphere. This work adds to the growing contention that elevated activities of fallout radionuclides, and other contaminants, in cryoconites are a global phenomenon and may be a risk to downstream terrestrial and aquatic ecosystems. • Few studies have measured fallout radionuclides (FRN) in Antarctic glacial sediment. • FRN concentrations in cryoconite were elevated compared to proglacial sediment. • Cryoconite scavenges FRN from passing meltwater. • Increased glacial melt may release FRN to downstream environments. [ABSTRACT FROM AUTHOR]

Over the past decades, the 137Cs approach has been successfully applied in Iran for estimating soil erosion and sedimentation rates. By the progressive reduction in 137Cs activity due to radioactive decay, however, it is essential to investigate the use of an alternative environmental radionuclide with a constant deposition through time, such as Lead-210. In this study, soil samples were collected within seven hectares cultivated field to determine the magnitude and spatial pattern of soil redistribution budgets. The net erosion rates for 137Cs and 210Pbex techniques were estimated to be 4.6 and 12.3t ha-1 yr-1 respectively and the sediment delivery ratio reached 52 and 60 percent respectively using mass balance model 2. Totally, soil erosion and deposition mean estimated from the 210Pbex measurements were much higher than those of 137Cs, since in the case of 137Cs, the results provided an estimate of the mean erosion rate over a period from 1963 to the time of sampling, whereas for the 210Pbextechnique, the estimates reflect a longer time period. The changes in the land management and rainfall characteristics that have occurred during the past century in the area under the study have had important influence on the soil redistribution estimates by the 210Pbex. This study has demonstrated the potential of using 210Pbex measurements to estimate soil erosion and deposition in semiarid regions.

Fine sediment transport in rivers is exacerbated during flood events. These particles may convey various contaminants (i.e. metals, pathogens, industrial chemicals, etc.), and significantly impact water quality. The exceptional June 2016 flood of the Seine River (catchment area: 65 000 km 2 , France), potentially mobilized and deposited contaminated materials throughout the Paris region. Flood sediment deposits (n = 29) were collected along the Seine River and its main tributaries upstream (Yonne, Loing and Marne Rivers) and downstream of Paris (Oise and Eure Rivers). Fallout radionuclides ( 137 Cs, 7 Be) were measured to characterize the sources of the material transiting the river, while trace elements (e.g. Cr, Ni, Zn, Cu, As, Cd, Sb, Pb, Tl, Ag) and stable lead isotopes ( 206 Pb/ 207 Pb) were analyzed to quantify the contamination of sediment transported during the flood. In upper sections of the Seine River, sediment mainly originated from the remobilization of particles with a well-balanced contribution of surface and subsurface sources. In the upstream tributaries, sediment almost exclusively originated from the remobilization of subsurface particles. In Paris and downstream of Paris, recently eroded particles and surface sources dominated, suggesting particles were mainly supplied by urban runoff and the erosion of agricultural soils. The highest metal concentrations and Enrichment Factors (EF) were found in the sediment collected in the Loing, Orge and Yvette upstream tributaries. Although these inputs were diluted in the Seine River, an increase in elemental concentrations was observed, progressing downstream through Paris. However, EFs in sediment collected along the Seine River were lower or in the same range of values sampled over the last several decades, reflecting the progressive decontamination of the urbanized Seine River basin. [ABSTRACT FROM AUTHOR]

Abstract: The International Atomic Energy Agency (IAEA), through the Joint Division with the Food and Agriculture Organization (FAO) of the United Nations, assists its Member States in applying nuclear techniques to alleviate challenges in food safety, food security and sustainable agricultural development. The Soil and Water Management & Crop Nutrition (SWMCN) Subprogramme, within the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, has made significant contributions to the development of isotopic techniques for the assessment of soil degradation and the development of efficient soil and land conservation approaches. These techniques include fallout radionuclides such as 137Cs, 210Pbex, 7Be, and 239+240Pu as well as 13C stable isotope and compound‐specific stable isotope analyses. These methodologies were developed and/or refined through the work of researchers from developed and developing countries who were selected to work within the frame of IAEA's Coordinated Research Projects (CRPs). Internal research activities implemented in the Joint FAO/IAEA's SWMCN Laboratory in Seibersdorf supported the work accomplished in the CRPs. The methodologies thus developed have been subsequently disseminated to developing countries by IAEA's Technical Cooperation Programme to assist Member States to adopt climate‐smart agriculture and reduce soil degradation that poses a threat to food security and the environment. This review paper provides an overview of the activities conducted in the frame of CRPs for combating soil erosion over the last 20 years and highlights the major achievements. Examples of the success and the impact obtained in Morocco, Madagascar, and Vietnam in using these isotopic techniques are presented. [ABSTRACT FROM AUTHOR]

This study describes the impact of dam construction at Sun Moon Lake, Taiwan, on lacustrine sedimentation. Analyses of the physical properties of sediment cores show that the surface sediment has two layers: the post-dam layer consisting of high-density, organic-poor sediment, and the underlying pre-dam layer consisting of organic-rich sediment. After correction for decay since initial deposition, the estimated concentration of excess 210Pb in the pre-dam layer was much higher than that in the present surface layer. These results indicate that the dam construction had a large impact on supply of 210Pb and the sedimentation environment in this lake. [ABSTRACT FROM AUTHOR]

Soil erosion is one of the main soil degradation phenomena that threaten sustainable use of soil productivity thus affecting food security. In addition, it leads to reservoir storage capacity loss because of sedimentation. This not only affects water quantity but also water quality. Worldwide, annual loss in reservoir storage capacity due to sedimentation is 0.5 to 1%. Similarly, about 27% of land in Africa is largely degraded by erosion. As a result, there is need to minimize soil erosion and deposition through site specific estimation of soil erosion and deposition rates in the reservoirs. To achieve this, Fallout RadioNuclides (FRNs) are some of the methods in use. The most common radionuclides include; 137Cs, 210Pb and 7Be. Only few countries in Africa have exploited these FRNs. In these countries, 137Cs has been largely exploited but in some regions, it has been reported to be below minimum detection limit. Using 137Cs and 210Pb, maximum reference inventory in Africa is found to be 1450 and 2602 Bq/m², respectively. However, there is minimal application of 7Be within the continent. Also, very little has been done in Africa to assess chronology and sedimentation rates of reservoirs using FRNs measured from sediment cores. In conclusion, a gap still exists on FRNs application in Africa in assessing soil erosion, deposition and reservoir sedimentation. [ABSTRACT FROM AUTHOR]

Purpose: First flushes can be crucial to sediment transport in fluvial systems of drylands, as temporary streams are a characteristic feature of Mediterranean basins. After a wildfire, storm flows may enhance runoff delivery to channels, so increasing the first-flush effect. Cs and Pb were used as tracers for recognizing the first post-fire flush effect on the source ascription of bed sediments temporarily stored in a Mediterranean temporary stream severely affected by a wildfire. Materials and methods: Thirty sediment source samples were collected along one of the tributaries of a catchment (4.8 km) located in Mallorca during a field campaign some weeks after the wildfire. The sample collection took into account effects of the wildfire and distinguished between soil surface and channel bank. To measure the source contribution temporarily stored with the bed sediment, five sediment samples-deposited during the first storm, occurring 3 months after the wildfire-were collected from the bed of the main channel. The Cs and Pb concentrations were measured by gamma spectrometry. Then, a linear mixing model was used to establish the contribution of each source type to the bed sediments along the main stream. Results and discussion: First post-fire flush effect was generated by a torrential event with a suspended sediment concentration peak of 33,618 mg L, although transmission losses under a very low runoff coefficient (1%) promoted sediment deposition. Significant differences were observed in fallout radionuclide concentrations between burned surface soil and burned channel bank samples ( p < 0.05), as well as between burned and unburned sources in the downstream part of the catchment ( p < 0.01). The radioactivity concentrations in bed sediment samples were statistically similar ( p > 0.05). Source ascription in bed sediments upstream shows that 67% was generated from burned hillslopes, reaching 75% in the downstream part, because downstream propagation of the sediment derived from the burned area. Conclusions: Bed sediments were mostly generated on burned surface soils because of the fire's effect on soil and sediment availability, high-intensity rainfall, and the limited contribution of channel banks, because these are fixed by dry-stone walls. This hydro-sedimentary response indicates an association between these factors driving erosion and sediment delivery, generating effective slope-to-channel sediment connectivity. The integration of the short-term response with the medium- and long-term analysis will allow for the analysis of the evolution of catchment sediment sources in future studies, determining if fire modifies the catchment sensitivity to that specific disturbance. [ABSTRACT FROM AUTHOR]

Soil erosion and associated sediment accumulation could be a serious problem, especially in agricultural loess areas. Polish loess areas have been used for agriculture since the beginning of the Neolithic era and are particularly vulnerable to soil erosion that began during that period due to deforestation for agricultural purposes. Mechanical denudation increased in the Middle Ages and was intensive for a period of up to 200 years. The main problem in interpreting the effects of agricultural use on the environment is the precise determination of the age of the sediments corresponding to the phases of increased anthropogenic soil erosion. The answer to the question of the intensity of soil erosion and land use change during periods of prehistoric and historic settlements is a key environmental problem in the archaeology and paleogeography of the Holocene. In this work, to study soil erosion and accumulation and to determine the age of colluvial sediments and the rate of soil erosion, we have used optically stimulated luminescence (OSL) in conjunction with fallout radionuclides 137Cs and 210Pbex which are often used to study soil erosion. Their use overcomes many of the limitations associated with traditional methods. We present a study of the intensity of soil erosion and sediment accumulation during the last 100 years. For this purpose, 30 field soil cores were collected from an agricultural field. This was supplemented by 10 soil cores from undisturbed sites to obtain reference values of the radionuclide fallout. In addition to these soil cores, three soil cores from the top, middle, and base of the soil were collected for OSL dating. In addition, five sediment traps were located on the slope to collect moving sediments and investigate the fractionation of fallout radionuclides, as well as residual luminescence. For detailed sediment characterisation, detailed soil physicochemical properties, i.e., pH, OM, N-tot, Fedith, Feox, and grain size, were studied. The results obtained from the isotope and luminescence analysis confirmed that the soil cover in this area has strongly eroded. The intensity of modern soil erosion is high and clearly increased after World War II. This is probably related to the establishment of a state-owned farm in this area. It is also visible that the OSL ages of the mobilised sediments are almost independent of the distance travelled on the slope. Almost all previous luminescence signals from sediment samples are bleached before the quartz grains start to be transported down the slope and are bleached again before burial at the deposition site. [ABSTRACT FROM AUTHOR]

The application of fallout radionuclides in soil erosion investigations and related sediment budget studies has provided a widely used tool for improving understanding of soil erosion and sediment transfer processes. However, most studies using fallout radionuclides undertaken to date have focussed on small areas. This focus on small areas reflects both the issues addressed and practical constraints associated with sample collection and analysis. Increasing acceptance of the important role of fine sediment in degrading aquatic habitats and in the transfer and fate of nutrients and contaminants within terrestrial and fluvial systems has emphasised the need to consider larger areas and the catchment or regional scale. The need to upscale existing approaches to the use of fallout radionuclides to larger areas represents an important challenge. This contribution provides a brief review of existing and potential approaches to upscaling the use of fallout radionuclides and presents two examples where such approaches have been successfully applied. These involve a national scale assessment of soil erosion rates in England and Wales based on 137Cs measurements and an investigation of the sediment budgets of three small/intermediate-size catchments in southern Italy.

As soil erosion is the major threat to one of the most essential resources of humankind, methods to quantify soil redistribution are crucial for agro-environmental assessment as well as for optimisation of soil conservation practices. The use of fallout radionuclides (FRN) as soil redistribution tracers is, next to modelling, currently the most promising approach for assessing soil erosion. This review aims to evaluate the suitability of Plutonium (Pu) in general and the 239 + 240 Pu isotopes in particular as soil redistribution tracers. It provides information on its origin, distribution and behaviour in soils and in the environment. Analytical methods, their recent advances as well as limitations, are discussed. To establish the current state of knowledge and to deepen our understanding, particular attention is given to the main existing achievements and findings based on using 239 + 240 Pu as soil erosion tracer in agroecosystems. We further discuss similarities and differences to other more mature FRN techniques such as the 137 Cs based approach which has been until now the most widely used method. We conclude that 239 + 240 Pu has the potential to become the next generation of soil redistribution tracer compared to the more mature FRN techniques mostly due to (i) its long half-life guaranteeing its long-term availability in the environment, (ii) its analytical advantage in terms of measurement precision and measurement time and (iii) its greater homogeneity at reference sites due to its main origin from past atmospheric nuclear weapon tests. In identifying some key future research opportunities and needs, we hope to refine the efficiency of this promising agro-environmental tracer for effective soil redistribution studies under future climate and land use change. [ABSTRACT FROM AUTHOR]

The activity concentrations of terrestrial and fallout radionuclides are investigated in soil and sediments from highway stormwater retention ponds. The increased activity of K, U and Th in sediment respect to soil samples (approximately 20% higher) is found to be correlated with the erosion of clay minerals. Therefore, it can be a useful fingerprint to assess the highway bank stability in long-term measurements. Fallout radionuclides, especially Be gives a clear indication of the well operation of the drainage system and the retention ponds, with activity concentrations in sediment samples up to 131.4 ± 7.8 Bq kg. Finally, these results are used to assess the potential external exposure to gamma radiation of the general population and worker due to maintenance operations. [ABSTRACT FROM AUTHOR]

Due to changing climate and irregular weather patterns, event-based soil loss and sediment yield have become important issues in the agricultural areas. Several mathematical models and prediction methodologies have been used to estimate event-based soil loss and soil redistribution based on soil types, land management, hydrology and local topography. The use of short-lived beryllium-7 as a means of estimating event-based soil erosion/deposition rates has become an alternative to the traditional soil loss measurement methods. A new erosion model taking into account the movement of 7Be in soils has been presented recently. In order to direct the attention to the potential offered by this technique (measurements and mathematical model), a two-year study was performed at the erosion plots in Müncheberg, Germany, and twelve individual erosion rates were estimated. This paper presents a systematic comparison of the non-steady state 7Be model with the process-based erosion model EROSION-3D and measured data. The results demonstrate a close consistency between the erosion rates estimated by erosion models and the estimates provided by the 7Be model and can therefore be seen as a promising contribution to validating the use of this radionuclide to document short-term soil redistribution within the plot and deposited sediment at the bottom of the plot. [ABSTRACT FROM AUTHOR]