Sediment source fingerprinting: benchmarking recent outputs, remaining challenges and emerging themes

Abstract: Purpose: This review of sediment source fingerprinting assesses the current state-of-the-art, remaining challenges and emerging themes. It combines inputs from international scientists either with track records in the approach or with expertise relevant to progressing the science. Methods: Web of Science and Google Scholar were used to review published papers spanning the period 2013–2019, inclusive, to confirm publication trends in quantities of papers by study area country and the types of tracers used. The most recent (2018–2019, inclusive) papers were also benchmarked using a methodological decision-tree published in 2017. Scope: Areas requiring further research and international consensus on methodological detail are reviewed, and these comprise spatial variability in tracers and corresponding sampling implications for end-members, temporal variability in tracers and sampling implications for end-members and target sediment, tracer conservation and knowledge-based pre-selection, the physico-chemical basis for source discrimination and dissemination of fingerprinting results to stakeholders. Emerging themes are also discussed: novel tracers, concentration-dependence for biomarkers, combining sediment fingerprinting and age-dating, applications to sediment-bound pollutants, incorporation of supportive spatial information to augment discrimination and modelling, aeolian sediment source fingerprinting, integration with process-based models and development of open-access software tools for data processing. Conclusions: The popularity of sediment source fingerprinting continues on an upward trend globally, but with this growth comes issues surrounding lack of standardisation and procedural diversity. Nonetheless, the last 2 years have also evidenced growing uptake of critical requirements for robust applications and this review is intended to signpost investigators, both old and new, towards these benchmarks and remaining research challenges for, and emerging options for different applications of, the fingerprinting approach

A novel traction-separation law for the prediction of the mixed mode response of ductile adhesive joints

AbstractA new traction–separation law that represents the constitutive relation of a ductile adhesive material in Mode I and Mode II is developed and introduced in interface elements for the finite element analysis of adhesive joints, within the framework of Cohesive Zone Modeling (CZM) techniques. The proposed law is based on the embedded process zone approach and is formulated to address the mixed-mode loading and fracture of adhesively bonded joints. This law is first used for the description of the pure Mode I (opening) and pure Mode II (sliding) loading and fracture and then it is integrated into a developed mixed-mode model in order to account for the dependence of the separate pure mode laws. The traction increasing part of the law is described by an exponential function, whereas the softening part is described by a linear decrease. Prediction of damage initiation is established through the nominal quadratic stress criterion, whereas the damage propagation is established through the linear energetic criterion. Experimental results from steel-to-steel single lap and Double Strap Joint configurations have been utilized for the validation of the proposed law and mixed-mode model. Comparisons are also provided from finite element analyses with the already known trapezoidal law and with the PRP (Park–Paulino–Roesler) model. The proposed law adequately captures the elastoplastic behaviour of the tested adhesive joints, in terms of their global response. Additionally, the strength of the tested joints is predicted with great accuracy