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Sediment source fingerprinting has been progressively developed and refined over the past 40 years or more and now represents a widely used and valuable technique, with important practical applications. However, relatively little attention has been given to the target samples and the extent to which they are able to provide meaningful information on short- or longer-term relative source contributions for a given study catchment. A key issue here is the inherent short- and longer-term temporal variability of source contributions and the extent to which such variability is taken into account by the target samples. The objective of this study was to investigate the temporal variation of source contributions from the Qiaozi West catchment, a small (1.09 km 2 ) gully catchment located within the Loess Plateau of China. The target samples represented a suite of 214 spot suspended sediment samples collected during eight representative wet season rainfall events occurring over two years. A suite of geochemical properties was used as fingerprints and standard source apportionment calculations indicated that the gully walls contributed the most sediment (load-weighted mean 54.5%) and, together with cropland (load-weighted mean 37.3%), and gully slopes (load-weighed mean 6.6%) were the main sediment sources. The 214 individual target samples indicated that the contribution of cropland sources varied between 8.3% and 60.4%, gully walls between 22.9% and 85.8% and gully slopes between 1.1% and 30.7%, representing ranges of 52.1%, 62.9% and 29.6% respectively. In order to explore whether the temporal variability of source contributions demonstrated by the study catchment should be seen as typical, equivalent information was abstracted from 14 published studies for other catchments of varying size and located in different environments worldwide. This information demonstrated similar temporal variability of the relative contributions of the major sources, which were typically characterized by ranges of the order of 30-70%. The temporal variability associated with the estimates of relative source contributions provided by target samples has important implications for the uncertainty associated with such estimates derived using source fingerprinting techniques based on a limited number of target samples. Further attention needs to be directed to the design of sampling programmes used to collect such samples and to taking account of such uncertainty in source apportionment calculations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Recent advances in sediment source tracing or fingerprinting procedures have focussed primarily on the use of novel sediment properties that are either easier to measure or provide improved source discrimination, or on improved procedures for representing and estimating the uncertainty associated with the final source apportionment results. Spatial variability of source properties has long been recognised as a potential problem for the approach, but there have been few attempts to explore the nature and magnitude of such variability and its wider implications for source fingerprinting investigations. This contribution addresses this issue with particular reference to surficial sediment sources. It reports the results of an investigation aimed at documenting the magnitude and nature of the spatial variability of the geochemical properties of surface soils within a single 7 ha cultivated field and exploring the implications of the findings for sediment source fingerprinting procedures. Samples of surface soil were collected from 52 points located within the field. Particular attention is directed to the extent of the spatial variability of 53 geochemical properties of the surface soil which could potentially be used as fingerprints, the importance of the influence of soil redistribution rate on the properties of the surface soil, provision of guidelines for selecting sampling points and the degree of correlation between different soil properties and its implications for the numerical procedures employed in sediment source fingerprinting studies. A novel aspect of the study is that caesium-137 ( 137 Cs) measurements were used to provide information on the magnitude and spatial pattern of the soil redistribution rate within the field, so that the influence of soil redistribution rate in causing systematic spatial variability of fingerprint properties could be further explored., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

There is increasing awareness of the damage caused to valuable and often unique sensitive habitats by people pressure as degradation causes a loss of plant species, disturbance to wildlife, on-site and off-site impacts of soil movement and loss, and visual destruction of pristine environments. This research developed a new perspective on the problem of recreational induced environmental degradation by assessing the physical aspects of soil erosion using the fallout radionuclide caesium-137 ((137)Cs). Temporal sampling problems have not successfully been overcome by traditional research methods monitoring footpath erosion and, to date, the (137)Cs technique has not been used to estimate longer-term soil erosion in regard to sensitive recreational habitats. The research was based on-sites within Dartmoor National Park (DNP) and the South West Coast Path (SWCP) in south-west England. (137)Cs inventories were reduced on the paths relative to the reference inventory (control), indicating loss of soil from the path areas. The Profile Distribution Model estimated longer-term erosion rates (ca. 40 years) based on the (137)Cs data and showed that the combined mean soil loss for all the sites on 'paths' was 1.41 kg m(-2) yr(-1) whereas the combined 'off path' soil loss was 0.79 kg m(-2) yr(-1), where natural (non-recreational) soil redistribution processes occur. Recreational pressure was shown to increase erosion in the long-term, as greater soil erosion occurred on the paths, especially where there was higher visitor pressure., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

The low productivity of salmonids in many river systems across the UK is testament to their intolerance of water quality perturbations including those associated with excessive sedimentation. Catchment and fishery managers concerned with combating such issues require reliable information on the key sources of the sediment problem to target management and on the efficacy of the mitigation options being implemented. In recognition of the latter requirement, a pre- and post-remediation sediment sourcing survey was used to examine the potential for using sediment tracing to assemble preliminary information on the efficacy of riparian fencing schemes for reducing sediment contributions from eroding channel banks to salmonid spawning gravels in the Rivers Camel, Fal, Lynher, Plym, Tamar and Tavy in the south west of the UK. Respective estimates of the overall mean proportion (+/-95% confidence limits) of the interstitial sediment input to salmonid spawning gravels originating from eroding channel banks during the pre- (1999-2000) and post-remediation (2008-2009) study periods were computed at 97+/-1% vs. 69+/-1%, 94+/-1% vs. 91+/-1%, 12+/-1% vs. 10+/-1%, 92+/-1% vs. 34+/-1%, 31+/-1% vs. 16+/-1% and 90+/-1% vs. 66+/-1%. Whilst the study demonstrates the potential utility of the fingerprinting approach for helping to assemble important information on the efficacy of bank fencing as a sediment source control measure at catchment scale, a number of limitations of the work and some suggestions for improving experimental design are discussed. Equivalent data are urgently required for many sediment mitigation options to help inform the development of water quality policy packages designed to protect aquatic ecosystems., ((c) 2010 Elsevier Ltd. All rights reserved.)