Composite Fingerprints Research Articles

Total Polyphenol Content in Food Samples and Nutraceuticals: Antioxidant Indices versus High Performance Liquid Chromatography.

Total polyphenol content and antioxidant capacity were estimated in various food and nutraceutical samples, including cranberries, raspberries, artichokes, grapevines, green tea, coffee, turmeric, and other medicinal plant extracts. Samples were analyzed by using two antioxidant assays—ferric reducing antioxidant power (FRAP) and Folin–Ciocalteu (FC)—and a reversed-phase high-performance liquid chromatography (HPLC), with a focus on providing compositional fingerprints dealing with polyphenolic compounds. A preliminary data exploration via principal component analysis (PCA) revealed that HPLC fingerprints were suitable chemical descriptors to classify the analyzed samples according to their nature. Moreover, chromatographic data were correlated with antioxidant data using partial least squares (PLS) regression. Regression models have shown good prediction capacities in estimating the antioxidant activity from chromatographic data, with determination coefficients (R2) of 0.971 and 0.983 for FRAP and FC assays, respectively.

Efficient neutralization of core ionized species in an aqueous environment.

Core ionization dynamics of argon-water heteroclusters ArM[H2O]N are investigated using a site and process selective experimental scheme combining 3 keV electron irradiation with Auger electron-ion-ion multi-coincidence detection. The formation of Ar 2p-1 vacancies followed by non-radiative decay to intermediate one-site doubly ionized states Ar2+(3p-2)-ArM-1[H2O]N and subsequent redistribution of charge to the cluster environment are monitored. At low argon concentrations the emission of an [H2O]n'H+/[H2O]n''H+ ion pair is the dominant outcome, implying on high efficiency of charge transfer to the water network. Increasing the condensation fraction of argon in the mixed clusters and/or to pure argon clusters is reflected as a growing yield of Arm'+/Arm''+ ion pairs, providing a fingerprint of the precursor heterocluster beam composition. The coincident Auger electron spectra, resolved with better than 1 eV resolution, show only subtle differences and thereby reflect the local nature of the initial Auger decay step. The results lead to better understanding of inner shell ionization processes in heterogeneous clusters and in aqueous environments in general.

Chemical composition of essential oils from the leaves of Mosiera bullata (Britton & P.Wilson), an unexplored Cuban endemic species

ABSTRACT Mosiera Small is a genus of Myrtaceae family with about forty species identified, including the Cuban endemic plant Mosiera bullata (Britton & P.Wilson) Bisse subsp. bullata. Mosiera species have been little investigated, and this is the first study analysing the composition of Mosiera bullata. Fresh leaf samples of M. bullata were collected from different locations near Santa Clara city, Cuba, and their essential oil was extracted. Using GC/MS, nineteen components (89.68% of the oil) were identified. The major compounds were found to be 1,8-cineole and eugenol, and a GC/FID method was analytically validated for their quantification. Chromatograms (GC/FID) of the sixteen samples studied were proposed as a fingerprint of the volatile composition of M. bullata leaves. Chemometric methods assured the reliability of the chromatographic fingerprinting. Therefore, in the present work is suggested, for the first time, a reliable and consistent chemical profile of M. bullata essential oil.

The efficiency of elemental geochemistry and weathering indices as tracers in aeolian sediment provenance fingerprinting

Confirmation of cost-effective and reliable tracers for aeolian sediment (sand dune) source fingerprinting warrants further research. Accordingly, the main objective of the work reported in this paper was to investigate the efficiency of weathering indices in aeolian sediment fingerprinting using a case study of a fragile arid region in Qom Province, Iran. Eight geochemical elements (Al, Ca, Fe, K, Na, Mg, Si, Ti) and 17 associated weathering indices were measured in 34 aeolian source samples and 10 sand dune target sediment samples in three absolute particulate size fractions. For each fraction, three final composite fingerprints (i.e., geochemical elements only, weathering indices only and a combination of the two) for discerning and ascribing the aeolian sediment sources were selected. The Modified MixSIR Bayesian un-mixing model was used to apportion aeolian source contributions using the final composite fingerprints. Regardless of the composite fingerprint used, all results across the different size fractions suggested that the south-eastern alluvial fan is the dominant (average contribution 50.6%, SD 19.0%) source of the sand dune samples, with the western alluvial fan being the second most important (average contribution 38.4%, SD 20.4%) source. Comparisons of the posterior distributions for the predicted source proportions generated using the nine composite fingerprints (three kinds of composite fingerprints*three particle size fractions) showed that the composite fingerprints combining the geochemical elements and weathering indices generated the most powerful source material discrimination. Our results demonstrate the use of weathering indices alongside more conventional elemental geochemistry tracers for investigations into sand dune sediment provenance.

Pilot‐scale manufacturing of phase‐pure and highly crystalline hydroxyapatite: Lessons learned and process protocols

AbstractThe recognition of hydroxyapatite (HAp) as the major bone mineral triggered significant research in bone tissue engineering applications. Although laboratory‐scale development involves the synthesis of HAp in different routes, scalability with uncompromised quality remains a major challenge. This article reports a large‐scale wet precipitation‐based synthesis of phase‐pure HAp using indigenously customized stirred tank reactors. The different synthesis parameters, like pH, reaction time, stirring rate, precursor addition, were tailored, together with the post‐synthesis mechano‐chemical treatment (aging induced Ostwald ripening) and calcinations, as the technology is matured to manufacture HAp powders in large volume. At least three batches of HAp were produced in the pilot‐scale reactor with reproducible values of phase purity, compositional fingerprint, particle size distribution, flowability, etc. The post‐calcination bluish tint was strategically addressed by adopting a proprietary calcination protocol. This batch process can produce around 200 kg/month of phase‐pure and highly crystalline (91–94%) HAp using stirred tank reactors of different working volumes. Extensive scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses reveal the particle size of as‐synthesized HAp powders with hexagonal crystal structure in the range of 20.47 ± 4.95 nm , while individual crystallite size in range of 22.3 ± 3.2 nm (XRD based Debye‐Scherrer analysis). TEM‐based SADP analysis confirms the highly crystalline hexagonal structure of as‐synthesized HAp. The spray‐dried powders with spherical shape having narrow size distribution (35–40 μm) could also be manufactured in large batches. The spray‐dried HAp powders could be coated on clinically used stainless steel femoral stem implants using atmospheric plasma spray coating technique.

Gully is the dominant sediment source of snowmelt erosion in the black soil region – A case study

Limited research is available on sediment provenance of snowmelt erosion. In this study, a Bayesian mixing model-based fingerprint tracing technique was used to estimate the relative sediment source contributions for snowmelt erosion in the black soil region of Northeast China, which experiences severe snowmelt erosion. Relative sediment contributions were estimated under two source classification schemes (Scheme 1: cultivated land, forest, and gully; Scheme 2: Scheme 1 + unpaved road) using the geochemical tracers. Kruskal–Wallis test and discriminant function analysis revealed different optimum composite fingerprints for Scheme 1 (Br, Cu, Fe2O3, CaO, and K2O) and Scheme 2 (Cr, Ba, Fe2O3, CaO, and K2O). Cultivated land, forest, and gully accounted for 52.1%, 1.4%, and 46.5%, respectively, of sediment contributions with a goodness of fit (GOF)= 0.89 and the mean absolute fit (MAF)= 0.62 in Scheme 1. However, gully-derived sediment from snowmelt erosion dominated the sediment contribution (66.1%) while cultivated land, forest, and unpaved track contributed 18.4%, 13.5%, and 2.0% (GOF=0.97, MAF=0.85), respectively, in Scheme 2. However, common tracer properties (Fe2O3, CaO, and K2O) as composite fingerprints contributed 13.5%, 13.4%, and 73.1% (GOF = 0.97, MAF = 0.86) of sediment from cultivated land, forest, and gully, respectively, for Scheme 1 while cultivated land, forest, gully, and unpaved road contributed 15.9%, 12.0%, 69.8%, and 2.4%, respectively (GOF=0.98, MAF=0.89), for Scheme 2. Our results demonstrated that the gully, owing to snowmelt erosion, is the dominant sediment source and more attention should be paid to prevent and control gully erosion in the black soil region of Northeast China during spring thawing period.

Development of a printed quality control test strip for the analysis and imaging of fingermark composition

In the last decade, there have been many scientific developments regarding the use of mass spectrometry to analyse the composition of fingermarks. In this context, the development of a dedicated quality control test strip would benefit the forensic community by providing a way to assess the reproducibility of the measures as well as to perform inter-laboratory comparisons. To accomplish this goal, the use of a chemical printer offers the possibility of combining a visual template with artificial fingerprint secretions. The design of the quality control test strip as well as the preliminary assessment of its performance with fingermark detection reagents and matrix-assisted laser desorption-ionisation combined with mass spectrometry imaging (MALDI-MSI) are presented in this paper. The chosen template combines two geometric patterns intended to help assess the chemical analysis (full square) and imaging (lined square) capabilities of the instrument. The artificial secretion is composed of two distinct solutions: artificial sweat and artificial sebum. The printing reproducibility and chemical homogeneity of the quality control test strips were assessed in two ways: (1) using MALDI-MSI, the printed pattern was analysed and the m/z values compared to the reference list based on the artificial secretion composition, and (2) using two common fingermark detection techniques, the printed pattern was processed using an amino acid reagent (ninhydrin) and a lipid stain (Oil Red O). Overall, the results highlight the potential of a printed quality control test strip for the assessment of the quality of fingermark detection techniques as well as the possibility of performing quality monitoring of mass-spectrometry-based techniques over time.

Comparative FT-IR Prospecting for Cellulose in Stems of Some Fiber Plants: Flax, Velvet Leaf, Hemp and Jute

Plant fibers are sustainable sources of materials for many industries, and can be obtained from a variety of plants. Cellulose is the main constituent of plant-based fibers, and its properties give the characteristics of the fibers obtained. Detailed characterization of cellulosic fibers is often performed after lengthy extraction procedures, while fast screening might bring the benefit of quick qualitative assessment of unprocessed stems. The aim of this research was to define some marker spectral regions that could serve for fast, preliminary qualitative characterization of unprocessed stems from some textile plants through a practical and minimally invasive method without lengthy extraction procedures. This could serve as a screening method for sorting raw materials by providing an accurate overall fingerprint of chemical composition. For this purpose, we conducted comparative Fourier Transform Infrared Spectroscopy (FT-IR) prospecting for quality markers in stems of flax (Linum usitatissimum L.), velvet leaf (Abutilon theophrasti Medik.), hemp (Cannabis sativa L.) and jute (Corchorus olitorius L.). Analysis confirmed the presence of major components in the stems of the studied plants. Fingerprint regions for cellulose signals were attributed to bands at 1420–1428 cm−1 assigned to the crystalline region and 896–898 cm−1 assigned to the amorphous region of cellulose. The optimization of characterization methods for raw materials is important and can find immediate practical applications.

Low-polymerization compositional fingerprinting for characterization of Schisandra polysaccharides by hydrophilic interaction liquid chromatography-electrospray mass spectrometry

A hydrophilic interaction liquid chromatography-negative electrospray-mass spectrometry (HILIC-ESI−-MS) coupled with microwave assisted mild acid (MAMA) depolymerization is proposed here for unusual discrimination and characterization of plant polysaccharides: a case study of fruit polysaccharides in Schisandra chinensis and S. sphenanthera (SCP and SSP). The optimized MAMA hydrolysis procedure was proposed for sample preparations of low-polymerization saccharides (Mw < 5000 Da) released in SCP and SSP. In addition, HILIC-MS/MS was employed for elucidation of isomeric glycosidic linkages in terms of 18O labelling. The MAMA hydrolysates showed that the amount of neutral →(4Hex1)n→ moiety is confirmed to be more bigger than that of acidic →(4HexA1)n → in SCP, whereas the amount of acidic →(4HexA1)n→ moiety seems to be more bigger than that of neutral →(4Hex1)n→ in SSP. The resulting low-polymerization compositional fingerprinting (LCF) showed the performance on rapid visualization of SCP and SSP by HILIC-MIM-MS. Principal components analysis (PCA) and hierarchical cluster analysis (HCA) further unveils several key Q-markers (e.g., m/z 503, 369, 665, 827, 989, 1151 and 735) for rapid discrimination of SCP and SSP. This practical study showed that the LCF with PCA and HCA could effectively reflect structural differences and could rapidly achieve discrimination of SCP and SSP.

An exploratory study on the use of different composite magnetic and colour fingerprints in aeolian sediment provenance fingerprinting

There is an urgent need for reliable and cost-effective sediment source tracing techniques for apportioning aeolian sediment (sand dune) sources for guiding the selection of best management practices for wind erosion control. Accordingly, the main aim of this study was to quantify the contributions of aeolian sources to sand dune target sediment samples collected in a case study in central Iran using a source fingerprinting procedure based on low-cost fingerprints comprising colour and magnetic tracers. Colour (RGB), magnetic susceptibility (χlf and χhf) and 13 colour and magnetic indices were measured on 54 aeolian sediment source samples and ten aeolian target sediment samples. Three different composite fingerprints for discriminating and apportioning the aeolian sediment sources were selected based on a combination of statistical tests comprising the Kruskal–Wallis H test (KW-H), discriminant function analysis (DFA), principal component & classification analysis (PCCA), and a general classification & regression tree (GC&RT) model. The Modified MixSIR Bayesian un-mixing model was used to apportion aeolian source contributions using the final composite fingerprints. The composite signatures all suggested that the salt flat plain was the dominant (average 63%, and standard deviation, SD, 5.9%) source of the aeolian target sediment samples, whilst agricultural land was second (average 63%, SD 5.6%,) most important. The root mean square difference between the apportionment results based on the three composite fingerprints ranged from 0.2% to 8.3%. Pairwise comparisons of the posterior distributions for the predicted source proportions generated using the three composite signatures showed that eight of 12 pairwise comparisons were not significantly different. Virtual mixture accuracy tests of the fingerprinting models using the three composite signatures suggested errors ranging between 2.2%−20.6% (with a mean of 9.9%), 1.4%−17.0% (mean value 8.3%), and 0.03%−1.0% (mean value 0.8%). The results support the use of low-cost colour and magnetic tracers by investigations into aeolian sediment provenance.

Using different size fractions to source fingerprint fine-grained channel bed sediment in a large drainage basin in Iran

Sediment fingerprinting in data sparse regions, such as the mountainous areas of Iran, is more suited to a confluence-based sample design wherein tributary sub-basins are characterised by sediment samples using different size fractions. Our objective was therefore to fingerprint spatial source contributions to the < 37 and 37–63 µm fractions of fine-grained channel bed sediment samples collected in a large erodible mountainous river basin in Iran based on a number of statistical and machine learning approaches. Geochemical elements were measured in channel bed surface drape sediments from seven sub-basins and in delivered sediments from the basin outlet. A Bayesian mass balance model (modified MixSIR) was applied to apportion sub-basin spatial sources with four composite signatures selected using the different statistical approaches. For the < 37 and 37–63 µm fractions, the signatures all indicated that sub-basins 3 (Andajroud; 46.7%) and 7 (Ninehroud; 36.8%) were the dominant spatial sources of the fine-grained bed drape sediment samples, respectively, identifying the most active erosional zones spatially. The statistical error between known and predicted spatial source contributions using virtual mixture tests for both size fractions demonstrated the importance of using multiple different composite fingerprints to decrease the model prediction uncertainties. Despite the difficult terrain in such data sparse areas, the source fingerprinting approach provides a basis for assembling new evidence which, in turn, is of interest to scientists and managers alike.

Source apportionment of heavy metals in sediments and soils in an interconnected river-soil system based on a composite fingerprint screening approach

Heavy metal pollution has been a global concern and key points of environmental pollution prevention and control due to the growing problems of urbanization and industrialization. Rapidly and correctly apportioning sources of heavy metal is still a great challenge because of the stability of source fingerprint and complex interaction of multiple contaminants and sources. In this study, we perform a combination of optimization of pollution source fingerprint and source apportionment through jointly utilizing two machine classification and screening methods for characterizing the pollution sources of heavy metal in the sediments of an urban river and its surrounding soils. Dominance-based rough set model (DRS), content optimization tools, and multivariate curve resolution-alternating least squares model (MCR-WALS) were employed to screen representative pollution source samples, optimize pollution source fingerprint, and apportion the potential sources of heavy metals, respectively. Further, Support vector machine (SVM) was adopted to correspondence analysis results and pollution fingerprint based on the factor characteristics for achieving source apportionment accurately. Results showed that the pollution source pollution source fingerprints optimized by DRS and optimization tools are more representative and stable, and the results obtained by SVM and MCR-WALS are more accurate comparing with traditional methods. As whole, source apportionment suggested that printing and dyeing, chemical, electroplating, metal processing were the main origins of heavy metals in this area and the proportions of them in sediment and soil pollution sources were 67.05% and 28.43%, respectively. Besides, coal combustion was also the main sources of heavy metal pollution in soils, accounting about 34.16%. Results of the study can advance our knowledge to better understand the characterization of heavy metal pollution in the peri-urban ecosystem and to design effective targeted strategies for reducing heavy metal pollution diffusion.

Fingerprinting sediment sources of the Shouchang River in the Southeastern China

Identification of sediment sources within catchments is crucial for river and catchment management. A multivariate mixing model in conjunction with two sets of statistically verified composite fingerprints was employed to identify the main sediment source areas at five locations along the main channel of the Shouchang River, southeastern China. The fingerprint composite fingerprints derived from the principle component analysis (PCA) and discriminant function analysis (DFA) combination can better apportion the five types of potential sediment sources. This combination demonstrated that over 33.0% sediment at each location came from river bed, with the largest contribution of 42.9%. The contributions from construction lands ranged from 16.0 to 26.8%. Sediment contributions from forest lands ranged from 7.8 to 22.1%. A large portion of sediment came from paddy fields, varying from 8.7 to 31.4% at the five locations. The sediment from dry land was the smallest, with the largest contribution of 18.4%, and the least contribution of 4%. Similar findings were also identified using the composite fingerprints derived from KW-H and DFA combination. Land use, topography, precipitation, and human activities were responsible for the sediment source apportionments and their variations at the five sediment sampling sites. This study implies that the available sediment from road and bridge built as well as plant production should well be supervised, laws should be made to inhibit in-stream sand mining activity, and the connectivity between paddy fields and channels should be reduced.

Quantifying the temporal variation of the contribution of fine sediment sources to sediment yields from Chilean forested catchments during harvesting operations

Fingerprinting techniques were incorporated into a paired catchment investigation in southern Chile to quantify the contribution of three fine sediment sources (catchment surfaces, forest roads and stream channels) to catchment suspended sediment yields during forest harvesting and replanting operations. Optimum composite fingerprints for use in sediment source discrimination and apportionment comprised 137Cs and 210Pbex for the control catchment (LUC) throughout the study and for the treatment catchment (LUT) during the pre-harvest period, and 137Cs and soil organic matter during harvest and post-harvest periods for LUT. Prior to harvesting, the dominant sediment source to the sediment load in both catchments was the stream channel and remained relatively constant throughout the study for LUC. For the entire study period the total suspended sediment yield from LUT (3,160 kg ha-1) approximately doubled that from LUC (1,650 kg ha-1). Most of this difference is accounted for by the increase in sediment output during the rainy months following clearcutting. The disturbance associated with forest operations in LUT caused the contributions to the load from the catchment slopes and forest roads to increase markedly (total contributions 835 and 795 kg ha-1, respectively). However, the total contribution from the stream channel for LUT during the study period (1,530 kg ha-1) remained similar to that from LUC. The results of the investigation demonstrated that any attempt to reduce sediment loading from forest harvesting would require adopting best management practices to reduce sediment mobilization from catchment surfaces and forest roads.

Sediment sources, soil loss rates and sediment yields in a Karst plateau catchment in Southwest China

Intensive agricultural activities have accelerated soil erosion and rocky desertification in karst regions of southwest China. Knowledge of sediment sources and soil erosion rates can be used to target soil conservation measures and to improve calibration and validation of process-based soil erosion and sediment delivery models for scenario analyses. Due to the complexity of karst environments, however, catchment scale information on these components of sediment budgets has rarely been assembled, meaning there continues to be an evidence gap. Within this context, this study selected Chenqi catchment, given its appropriate research infrastructure, to investigate sediment sources and soil loss rates in a typical karst agroforestry landscape. We estimated the relative contributions from three sources: surface soil, subsurface soil and clastic rock, using a composite fingerprinting procedure combining 137Cs and magnetic susceptibility and a frequentist un-mixing model with Monte Carlo uncertainty analysis. Suspended sediment samples were taken at an hourly interval during seven rainfall events in 2017–2018 to characterize and quantify the sediment exported in both surface and underground drainage. The overall average median contributions (with 5th-95th percentile uncertainty ranges) from the sources to the suspended sediment samples from the surface drainage outlet were in the order: 62% (0−99%) subsurface soils, 25% (0−91%) surface soils and 13% (0−45%) clastic rock. For the sediment samples collected from the underground drainage catchment outlet, the corresponding estimates were in the order: 68% (0−97%) subsurface soils, 25% (0−53%) clastic rock and 7% (0−44%) surface soils. Plot scale soil loss rates were highest on cropland (0.70 Mg km−2) and pasture land (0.48 Mg km−2). The average (2017 and 2018) annual suspended sediment load exported through the surface outlet was 4.64 Mg km−2 compared with 1.20 Mg km−2 through the underground outlet. The broader implications of this study are that subsurface and clastic rock sources represent a significant component of the catchment sediment budget, meaning erosion control measures targeting hillslope surface soils alone may have limited impact on suspended sediment export at landscape scale.

Identification of sediment sources and exploration of scale effects in the black soil region of Northeast China

Sediment provenance plays an important role in describing soil erosion characteristics and assessing the benefits of soil and water conservation measures. To further understand the transfer of sediment, a Bayesian mixing model-based fingerprint tracing technique was used in this study to quantify the relative contributions of sediment sources to the bottom of the gullies. Two catchments, the Hebei catchment with an area of 27.6 km2 and its sub-catchment with an area of 3.5 km2, located in the black soil region of Northeast China, were selected to identify sediments from cultivated topsoil, uncultivated topsoil, and gully soil. Seventy soil samples were collected from each catchment to characterize the sediment sources. Five sediment samples deposited in gully bottoms were collected from each catchment. Although a composite sampling method was applied, the spatial variability in the fingerprints between the Hebei catchment and its sub-catchment showed significant (p < 0.01) differences. The different optimum composite fingerprints obtained for the two catchments were: Ba, Ga, Br, Ce, and P for the Hebei catchment and Ba, Ga, Br, and As for its sub-catchment. In both catchments, over 95% of the sediment deposited in the gully bottoms was from cultivated topsoil and gully soil. However, the relative sediment contribution of cultivated topsoil and gully soil were significantly (p < 0.01) different between the two catchments. Notably, 42.0% and 47.8% of sediments were from cultivated topsoil while 55.3% and 49.6% of sediments were from gully soil (mean absolute fit > 0.95) in the Hebei catchment and its sub-catchment, respectively. Most of the sediment from the gully (>60%) was deposited in the upper segment of the gully bottom while the sediment from cultivated topsoil gradually increased in the lower segment.

Revealing soil erosion characteristics using deposited sediment sources in a complex small catchment in the wind-water erosion crisscross region of the Chinese Loess Plateau

Sediment sources in catchments under the control of check dams in the wind-water erosion crisscross region are more complicated compared to other regions on the Chinese Loess Plateau. This is due to their general complexity, which mainly results from variation in soil, landform, vegetation, and erosion agents. Accordingly, we used the composite fingerprinting approach to trace sediment sources in a typical small catchment in this region. The aim was to reveal the erosion characteristics of the catchment throughout the trapping history of the check dam. Sediment sources were classified into three-source (paleosol, loess and sand) and four-source (paleosol-gully, loess-gully, slope bare of sand and slope covered by sand) groups on the basis of soil and landform types, respectively. Sediment sources throughout the whole trapping history of the check dam (1978–2010) could be classified into three stages according to variation in sedimentation rate. Results showed that depositional sediment in the check dam was primarily from gullies (averaging 80.1%), especially the paleosol-gully (>54.1%). The large contribution of gullies indicated that the main erosion agents were streamflow from rainstorm events and gravity. Coal mining also had a significant impact on contribution of sediment sources, especially for slopes. Since 1987, mining began to change the structure of hills in this region, leading to slope fissures, collapse, and landslides at junctions where gullies meet slopes, which increased the risk of slope erosion. This has caused an increase in sediment from slopes bare of sand distributed under condition of continues implementation of soil conservation measures, which converted sloping cropland into grassland or forest. Further studies are necessary to gain better insight into sediment transport and deposition within such complex environments, as well as to distinguish between the effects of multiple erosion agents.

Source fingerprinting loess deposits in Central Asia using elemental geochemistry with Bayesian and GLUE models

The provenance of loess deposits in Central Asia is largely unexplored. Accordingly, the goals of this research were to test and compare the performance of two different models (generalized likelihood uncertainty estimation - GLUE and a Bayesian model) for quantifying the uncertainty in source apportionment estimated for 46 target loess samples collected in the Ili basin, in eastern Central Asia. Model performance was evaluated using goodness-of-fit (GOF), mean absolute fit (MAF) and virtual mixtures (VM) in combination with root mean square error (RMSE) and mean absolute error (MAE). Our dataset comprised 132 surficial samples collected from three potential sources comprising river alluvium (n = 29), sand dunes (n = 35) and topsoils (n = 68). All samples were analysed for elemental geochemistry. Six geochemical properties (Co, Er, Y, Ga, Dy and Pb) were selected in a composite fingerprint which classified 83% of the samples from the three source categories correctly. Based on both models, source contributions to the loess samples were in the following order: topsoils > river alluvium > sand dunes. Based on the GOF and MAF tests, both models were accurate in predicting measured tracer concentrations in the loess samples. The Bayesian model was slightly more accurate (mean RMSE 1.6%, mean MAE 1.8%) than the GLUE (mean RMSE 5.0%, mean MAE 4.7%) model in predicting known source contributions. Overall, our results provide confirmation that application of source fingerprinting with elemental geochemistry and uncertainty modelling techniques is useful for identifying the provenance of loess sediments in arid and desert environments.

Evaluation of the use of chemical pads to mimic latent fingermarks for research purposes

Fingermark detection is in constant evolution, with new techniques being developed and existing ones being continuously optimised. Recently, researchers have begun to express interest in artificial fingermark secretions to overcome the issues arising from the variability of fingermark composition. Some of these artificial secretions have started to appear on the market in the form of pads that can be used to deposit fingermarks with a known and controlled composition. This study aimed at assessing the reliability of three commercially-available pads by comparing the results to those obtained by real fingermarks, using six detection techniques (1,2-indanedione/zinc, ninhydrin, cyanoacrylate followed by rhodamine 6G staining, gold/zinc vacuum metal deposition, and physical developer) on five substrate types (copy and recycled paper, acetate, glass, and glossy paper). The results showed that the artificial fingermarks deposited with these pads reacted in an unreliable way, notably when treated with complex detection techniques such as Physical Developer. Further, the high concentration of some of the target compounds found in the artificial secretion led to an over performance of some detection techniques, which could mislead the operator to overestimating the efficiency of a given method. The resulting artificial fingermarks are considered too dissimilar to real fingermarks to be used as quality control standards and better simulants need to be found for a more efficient and realistic control of the variability.

Using composite fingerprints to quantify the potential dust source contributions in northwest China

Dust storms have a profound impact on the atmospheric environment, global climate change, and human health, so it is of great importance to strengthen related research. The main areas of occurrence and frequency of dust storms in northwestern China were distinguished by measuring the concentration of geochemical elements in the topsoil and atmospheric dust samples, combined with the HYSPLIT backward trajectory model, MODIS true-color satellite images, and PM10 real-time monitoring data. On this basis, the composite fingerprints method was used to establish an end-member model between the concentration of dust storm samples and topsoil samples, and then to trace the sand and dust sources in northwest China and quantify their source contributions. The results showed that the main potential source areas causing sandstorms were located in the Kumtag Desert, Hexi area, and the Gobi Desert in the central and western parts of Inner Mongolia. Overall, the contributions from natural sources were greater than those from anthropogenic sources, especially at Alxa League. In addition to natural sources, anthropogenic dust sources contributed highly to dust storms, with a contribution rate of approximately 40% in cities. The main dust source in Zhangye City was from agriculture areas. The contribution of the potential dust sources in the west of the study area showed a decreasing trend from west to east because of the distance effect. Because of the influence of the prevailing westerly winds in the east, the sources of dust were relatively extensive. The Badain Jaran Desert and Tengger Desert were not the main dust sources in the study area because of artificial sand control measures and the low amounts of fine-grained components in sandy deserts. These methods and results are of great importance for sustainable development in northwest China.