Spectral fingerprinting: characterizing suspended sediment sources by the use of VNIR-SWIR spectral information

Purpose

Knowledge of sediment sources is a prerequisite for sustainable management practices and may furthermore improve our understanding of water and sediment fluxes. Investigations have shown that a number of characteristic soil properties can be used as “fingerprints” to trace back the sources of river sediments. Spectral properties have recently been successfully used as such characteristics in fingerprinting studies. Despite being less labour-intensive than geochemical analyses, for example, spectroscopy allows measurements of small amounts of sediment material (>60 mg), thus enabling inexpensive analyses even of intra-event variability. The focus of this study is on the examination of spectral properties of fluvial sediment samples to detect changes in source contributions, both between and within individual flood events.

Materials and methods

Sediment samples from the following three different origins were collected in the Isábena catchment (445 km²) in the central Spanish Pyrenees: (1) soil samples from the main potential source areas, (2) stored fine sediment from the channel bed once each season in 2011 and (3) suspended sediment samples during four flood events in autumn 2011 and spring 2012 at the catchment outlet as well as at several subcatchment outlets. All samples were dried and measured for spectral properties in the laboratory using an ASD spectroradiometer. Colour parameters and physically based features (e.g. organic carbon, iron oxide and clay content) were calculated from the spectra. Principal component analyses (PCA) were applied to all three types of samples to determine natural clustering of samples, and a mixing model was applied to determine source contributions.

Results and discussion

We found that fine sediment stored in the river bed seems to be mainly influenced by grain size and seasonal variability, while sampling location—and thus the effect of individual tributaries or subcatchments—seem to be of minor importance. Suspended sediment sources were found to vary between, as well as within, flood events; although badlands were always the major source. Forests and grasslands contributed little (<10 %), and other sources (not further determinable) contributed up to 40 %. The analyses further suggested that sediment sources differ among the subcatchments and that subcatchments comprising relatively large proportions of badlands contributed most to the four flood events analyzed.

Conclusions

Spectral fingerprints provide a rapid and cost-efficient alternative to conventional fingerprint properties. However, a combination of spectral and conventional fingerprint properties could potentially permit discrimination of a larger number of source types.     

The evolution of sediment source fingerprinting investigations in fluvial systems

Purpose

This contribution reviews the evolution of sediment source fingerprinting investigations since the beginning of such studies in the mid-1970s. Attention is directed to key advances and developments during this period, to the present status of source fingerprinting techniques and to the scope for future development.

Scope

An analysis of the number of papers reporting sediment source fingerprinting investigations or associated methodologies published annually since the mid-1970s to date indicates that the number of such papers has increased near exponentially. The key drivers behind the expansion of such work are examined and linked to both the progress of academic enquiry and the need to support the development of sediment management strategies aimed at countering environmental problems associated with fine sediment. Instead of providing a chronological review of the various advances and developments evidenced by the expanding literature, attention focuses on seven key areas of development which are seen as having together contributed to the current state of the art. These include the expanding range of fingerprint properties employed; the use of statistical tests to confirm the ability of particular fingerprint properties to discriminate between potential sources and to assist in the selection of the ‘best’ properties for inclusion in the final composite fingerprint; the use of numerical mixing models to obtain quantitative estimates of the relative contribution of different sources; recognition of the need to confirm the conservative behaviour of the sediment properties employed as fingerprints and to take account of contrasts in grain size composition and organic matter content between source material and target samples; extension of the approach to include a greater range of targets and potential sources; addition of a temporal dimension, in order to consider changes in sediment source through time; and recognition of the need to direct increased attention to the uncertainty associated with the results of such studies. At the present time, sediment source fingerprinting techniques can be seen as being in a transition from a scientific tool to an operational or management tool, but further development will be required before successful transition to the latter can be fully achieved.     

三江源区近数十年河流输沙及水沙关系变化

河川径流及泥沙在保障水资源、塑造河道形态、维持区域环境及生态系统等方面起着重要作用.为探讨三江源区河流输沙及水沙关系,基于三江源区9个水文站径流泥沙观测资料,采用Mann-Kendall趋势检验、Mann-Kendall突变检验方法分析输沙量、含沙量的变化趋势及突变特征,利用评级曲线法,分析水沙关系.结果表明:1)从输沙量来看,仅长江源区的新寨输沙量呈显著减少趋势,并在1998年发生突变;2)长江源区新寨含沙量显著减少,黄河源区的黄河沿、同仁及唐乃亥含沙量显著增加,其他水文站含沙量没有显著变化趋势,新寨和同仁含沙量分别在1999和1989年存在突变特征;3)直门达以上的长江源区及澜沧江源区水沙关系未发生明显变化,长江源区的新寨水文站控制区及黄河源区水沙关系发生变化;4)水流挟沙能力的变化表现出了明显的空间差异性,主要分为减弱、增强及稳定3种类型.河流输沙及水沙关系发生的变化,可能与气候变化和人类活动等有关,研究成果可为三江源区流域规划和生态保护,以及下游水库泥沙淤积研究等提供参考.     

Comparison of diffuse reflectance fourier transform mid-infrared and near-infrared spectroscopy with grating-based near-infrared for the determination of fatty acids in forages

Diffuse reflectance Fourier transform mid infrared (FTMIR) and near-infrared spectroscopy (FTNIR) were compared to scanning monochromator-grating-based near-infrared spectroscopy (SMNIR), for their ability to quantify fatty acids (FA) in forages. A total of 182 samples from thirteen different forage cultivars and three different harvest times were analyzed. Three calibration analyses were conducted for lauric (C12:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), and alpha-linolenic (C18:3) acids. When all samples were used in a one-out partial least squares (PLS) calibration, the average R (2) were FTNIR (0.95) > SMNIR (0.94) > FTMIR (0.91). Constituents C18:2 and C16:0 had among the highest R (2) regardless of the spectroscopic method used. The FTNIR did better for C12:0, C14:0, and C18:3. The SMNIR did better for C16:0, C16:1, C18:0, C18:1, and C18:2. A second set of calibrations developed with half of the samples as the calibration set and the rest as the validation set showed that all the methods produce acceptable calibrations, with calibration R (2) above 0.9 for most constituents. However, the SMNIR had a better average calibration relative error than the FTNIR, which was slightly better than the FTMIR. A third set of calibration equations developed using 100 random PLS runs with the 182 samples split randomly also shows that the three spectral methods are satisfactory for predicting FA. It is not clear whether any of the spectral methods is distinctly better than another. Calibration R (2) and validation R (2) were higher for most FA with the SMNIR than the FTMIR and FTNIR.     

Rare earth elements: a potential proxy for identifying the lacustrine sediment source and soil erosion intensity in karst areas

Purpose

The geochemistry of rare earth elements (REEs) taken from the sediments of a karst lake was analyzed to track the provenance of the sediments and the history of soil erosion in the Jiuzhaigou Nature Reserve (JNR) in Sichuan Province in southwest China.

Materials and methods

The REE concentrations of 177 samples including 150 lake sediments, 13 soils, 8 loess, 3 carbonate rocks, and 3 water were determined using a quadruple inductively coupled plasma mass spectrometer (Q-ICP-MS). The grain size distributions of 139 sediment samples were measured using a Malvern Master Size 2000 laser particle size analyzer. The carbonate contents of 159 sediment samples were determined using a gasometric method. The dried remains after reaction with HCl were defined as acid-insoluble residues. The mineral composition of the sediments was measured using a Philips X'Pert Pro X-ray diffractometer.

Results and discussion

The lake sediments in the JNR exhibit features similar to those of the neighboring soils, i.e., enriched REE content, a greater ratio of light REEs to heavy REEs, greater δCe values, and lower δEu values relative to those in the carbonate rocks. The REE signatures in the silt and sand fractions of the sediments are similar to those in the soils and carbonate rocks, respectively. The REE content, LREE/HREE, and δCe values in the sediments strongly negatively correlate with the carbonate content, indicating an intense carbonate effect on the REE geochemistry. The content of acid-insoluble residues is obviously positively correlated with ∑REEs in the sediments, and a negative relationship is observed between ∑REEs and the ratio of calcite to quartz in the sediments.

Conclusions

The sediments in the JNR originate from eroded soils and authigenic travertine deposits in the lakes. It is proposed that the increased ∑REEs in the sediments resulted from the elevated proportion of soil particles in lacustrine deposits was due to increasing soil erosion intensity. This hypothesis is evidenced by the coupling of ∑REEs with the intensity of soil erosion and anthropogenic activities in the JNR. In karst drainage, the total REE concentration might be a potentially powerful indicator for reconstructing the history of soil erosion.     

Feasibility study on the use of visible and near-infrared spectroscopy together with chemometrics to discriminate between commercial white wines of different varietal origins

The use of visible (vis) and near-infrared spectroscopy (NIR) was explored as a tool to discriminate between samples of Australian commercial white wines of different varietal origins (Chardonnay and Riesling). Discriminant models were developed using principal component analysis (PCA), principal component regression (PCR), and discriminant partial least-squares (DPLS) regression. The samples were randomly split into two sets, one used as a calibration set (n = 136) and the remaining samples as a validation set (n = 133). When used to predict the variety of the validation set samples, the DPLS models correctly classified 100% of Riesling and up to 96% of Chardonnay wines. These results showed that vis-NIR might be a suitable and alternative technology that can be easily implemented by the wine industry to discriminate Riesling and Chardonnay commercial wine varieties. However, the relatively limited number of samples and varieties involved in the present work suggests caution in extending the potential of such a technique to other wine varieties.     

Comparing local vs. global visible and near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) calibrations for the prediction of soil clay, organic C and inorganic C

Local, field-scale, VisNIR-DRS soil calibrations generally yield the most accurate predictions but require a substantial number of local calibration samples at every application site. Global to regional calibrations are more economically efficient, but don't provide sufficient accuracy for many applications. In this study, we quantified the value of augmenting a large global spectral library with relatively few local calibration samples for VisNIR-DRS predictions of soil clay content (clay), organic carbon content (SOC), and inorganic carbon content (IC). VisNIR models were constructed with boosted regression trees employing global, local + global, and local spectral data, using local samples from two low-relief, sedimentary bedrock controlled, semiarid grassland sites, and one granitic, montane, subalpine forest site, in Montana, USA. The local + global calibration yielded the most accurate SOC predictions for all three sites [Standard Error of Prediction (SEP) = 3.8, 6.7, and 26.2 g kg^− 1]. This was similarly true for clay (SEP = 95.3 and 102.5 g kg^− 1) and IC (SEP = 5.5 and 6.0 g kg^− 1) predictions at the two semiarid grassland sites. A purely local calibration produced the best validation results for soil clay content at the subalpine forest site (SEP = 49.2 g kg^− 1), which also had the largest number of local calibration samples (N = 210). Using only samples from calcareous soils in the global spectral library combined with local samples produced the best SOC and IC results at the more arid of the two semiarid sites. Global samples alone never achieved more accurate predictions than the best local + global calibrations. For the temperate soils used in this study, the augmentation of a large global spectral library with relatively few local samples generally improved the prediction of soil clay, SOC, and IC relative to global or local samples alone.     

Compositional dynamics of suspended sediment in the Rhine River: sources and controls

Journal of Soils and Sediments - Information on the geochemical composition of suspended sediments in rivers is crucial to identify sediment source type or area. In large river basins, however, the...     

Trace metal distribution in the bed,bank and suspended sediment of the Ravensbourne River and its implication for sediment monitoring in an urban river

Journal of Soils and Sediments - This study aims to identify a suitable sediment compartment for sediment quality monitoring by: (a) studying the concentration of trace metals (Cd, Cu, Ni, Pb and...     

Application of near-infrared reflectance spectroscopy to the evaluation of rutin and D-chiro-Inositol contents in tartary buckwheat

Tartary buckwheat [Fagopyrum tataricum (L.) Gaench] is rich in rutin and D- chiro-inositol (DCI), which have beneficial effects in the treatment of hemorrhagic diseases and insulin-resistant diseases, respectively. The current methods of extraction and detection of rutin and DCI are complex and time-consuming; a simple way of analyzing these compounds in the native matrix would be desirable. In this work, near-infrared reflectance spectroscopy (NIRS) was applied to determine the contents of rutin and DCI in tartary buckwheat. The spectral data were compared with those determined from high-performance liquid chromatography (HPLC) methods. Models for predicting rutin and DCI contents in buckwheat were developed using a partial least-squares algorithm. Cross-validation procedures indicated good correlations between HPLC data and NIRS predictions (R2 = 0.76 for rutin and R2 = 0.86 for DCI). The rutin content ranged from 0.998 to 1.75%, while the DCI content covered 0.179-0.200%. The results showed that NIRS, a well-established and widely applied technique, could be applied to determine rutin and DCI in tartary buckwheat rapidly and nondestructively.     

Monitoring and analysis of suspended sediment transport dynamics in the Carapelle torrent (Southern Italy)

In Northern Puglia watershed's high rates of suspended sediment loads occur along the hydrographic network during intense rainfall events. In order to monitor this phenomenon an automated station, equipped with a turbidity probe, has been set up in the Carapelle torrent.     

Distribution and fractionation of rare earth elements in suspended sediment of the Zhujiang River,Southwest China

Journal of Soils and Sediments - The geochemistry of rare earth elements (REEs, La to Lu) in suspended sediments (SS) is generally controlled by weathering processes and the water environment....     

Quantification of kavalactones and determination of kava (Piper methysticum) chemotypes using near-infrared reflectance spectroscopy for quality control in vanuatu

Kava ( Piper methysticum Forst f., Piperaceae) has anxiolytic properties and the ability to promote a state of relaxation without the loss of mental alertness. The rapid growth of the nutraceutical market between 1998 and 2000 has been stopped by a ban in Europe and Australia because of some suspicion of liver toxicity. It is now important to develop a fast, cheap, and reliable quality test to control kava exports. The aim of this study is to develop a calibration of the near-infrared reflectance spectroscopy (NIRS) using partial least-squares (PLS) regression. Two hundred thirty-six samples of kava roots, stumps, and basal stems were collected from the Vanuatu Agricultural Research and Technical Centre germplasm collection and from four villages. These samples, representing 45 different varieties, were analyzed using NIRS to record their absorption spectra between 400 and 2500 nm. A set of 101 selected samples was analyzed for their kavalactone content using HPLC. The results were used for PLS calibration of the NIRS. The NIRS prediction of the kavalactone content and the dry matter were in agreement with the HPLC results. There were good correlations between these two series of results, and coefficients ( R (2)) were all close to 1. The measurements were reproducible and had repeatability on par with the HPLC method. The NIRS system has been calibrated for the six major kavalactone content measurements, and it is suggested that this method could be used for quality control in Vanuatu.     

Determining the distributions of soil carbon and nitrogen in particle size fractions using near-infrared reflectance spectrum of bulk soil samples

This study aimed at assessing the potential of near-infrared reflectance spectroscopy (NIRS) for determining the distribution of soil organic matter (SOM) in particle size fractions, which has rarely been attempted. This was done on sandy soils from Burkina Faso (three sites) and Congo-Brazzaville (one site). Over the total sample set, NIRS accurately predicted carbon (C) and nitrogen (N) concentrations (g kg^?1 fraction) in the fraction <20 μm. When considering Burkina Faso only, predictions were improved in general; those of C and N amounts (g kg^?1 soil) became accurate for the fraction <20 μm but not for the coarser fractions, probably due to heterogeneous SOM repartition. However, most SOM being <20 μm in general, NIRS could be considered promising for determining SOM size distribution.     

Investigating the use of fallout and geogenic radionuclides as potential tracing properties to quantify the sources of suspended sediment in a mining catchment in New Caledonia,South Pacific

Journal of Soils and Sediments - New Caledonia, a French island located in the south-west Pacific Ocean, has vast nickel resources. Open-cast mining has strongly increased soil erosion and the...     

Variations in concentrations and bioavailability of heavy metals in rivers during sediment suspension-deposition event induced by dams: insights from sediment regulation of the Xiaolangdi Reservoir in the Yellow River

Journal of Soils and Sediments - The variations of concentrations, speciation, and bioavailability of heavy metals during large-scale sediment suspension-deposition events caused by dams in rivers...     

The source and diagenesis of sediment organic matter in the upper Pearl River Estuary as indicated by amino sugars

Purpose

The source and diagenesis of sediment organic matter (OM) based on amino sugar yields and compositions were investigated in sediment samples collected along a reach of the upper Pearl River Estuary in south China.

Materials and methods

Sediment samples were collected from the estuary. Three sediment size fractions—coarse particulate OM (CPOM), fine particulate OM (FPOM), and ultrafiltered dissolved OM (UDOM)—were analyzed for total hydrolysable amino sugars (THAS), total organic carbon (TOC), and total nitrogen (N).

Results and discussion

THAS contributed much more to sediment TOC and total N in UDOM than in CPOM and FPOM. Percentages of TOC as THAS increased with increasing sediment size. The low glucosamine/galactosamine ratios indicated a relatively large bacterial contribution to the sediment OM size fractions and the less reactive nature of sediment OM in the upper Pearl River Estuary. However, the depletion in muramic acid in the three sediment fractions, especially in UDOM, suggested that living bacteria or intact peptidoglycan units were not a major contributor to sediment OM.

Conclusions

The increases of TOC as THAS and C-normalized yields of THAS with the different sediment size fractions demonstrated that they could be used as diagenetic indicators.     

The development of rare earth element-labelled potassium-depleted clays for use as cohesive sediment tracers in aquatic environments

Purpose

Understanding the transport behaviour of fine cohesive sediment is fundamental to the sustainable management of aquatic environments. Sediment tracing techniques are widely used for measuring the transport pathways of sand-sized material in the field. However, the development of tracers, including geochemically labelled clays, for fine, cohesive sediment is more problematic. Such tracers should have chemical signatures that can be easily detected following significant dilution in the field and should remain constant for the duration of the tracer study.

Materials and methods

We have examined the potential of rare earth element (REE)-labelled phlogopite and hydrobiotite as cohesive sediment tracers. Clays were first treated with sodium tetraphenylborate to extract interlayer potassium and enhance their cation exchange capacity. Ho, La and Sm were then sorbed to the clays in batch experiments. Desorption of the chemical signature in both fresh and saline conditions was examined after 1 and 10 days.

Results and discussion

Potassium extraction enhanced REE sorption, resulting in REE concentrations in excess of 40,000 mg kg^?1 in the labelled clays, and these signatures should be easily detected following dilution in the aquatic environment. In both fresh and saline conditions, over 90% of the tracer signature was retained over a 1-day period. However, over longer time scales, there was considerable loss of the REE signature.

Conclusions

Over short time scales, there is considerable potential to use these materials as cohesive sediment tracers. Over longer time scales, although much of the label is lost, the tracers could still provide qualitative information identifying net sediment transport pathways.     

A comparison of measured catchment sediment yields with measured and predicted hillslope erosion rates in Europe

Purpose  

This study aims to understand better the relationship between measured soil loss rates due to sheet and rill erosion (SL), predicted SL rates and measured catchment sediment yields (SY) in Europe.     

A guidance for the assessment and evaluation of sediment quality a German Approach based on ecotoxicological and chemical measurements

The recommendations presented in this paper use an integrated hierarchical approach combining toxicological, chemical and ecological information to assess and evaluate the quality of sediments. For this reason, biological methods, in combination with the tools of chemical analysis, are given priority when examining the quality of the sediment to establish adverse effects. The trigger is the biotest, instead of chemical methods commonly used. The individual methods are presented for a German approach and can be adopted to other countries by applying ISO, OECD methods. Support is provided on how to best integrate data generated using different assessment tools. Keywords: Bioassays; biological and chemical analysis; ecotoxicology; integrated assessment; sediment assessment; sediment quality; stepwise strategy