Quantitative sediment source ascription using magnetic measurements in a reservoir-catchment system near Nijar, S.E. Spain (original) (raw)
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Geochemistry, Geophysics, Geosystems, 2009
1] This study presents an innovative application of well-established environmental magnetic proxy parameters on fluvial sediments, with the aim to trace geological and human-induced processes in the complex Seine river drainage system in northern France. We seek to identify environmental fingerprints of mechanical and chemical weathering processes, the regional distribution of the suspended material, and changes in the balance of natural input versus anthropogenic pollution. In order to reach these goals, we applied a combination of rock magnetic and advanced scanning electron microscopic techniques on a large number of sediment trap samples. Generally, we observe an increase in magnetic concentration coupled with a coarsening in magnetic grain size downstream of the Seine river system. Furthermore, the dominant magnetomineralogy changes from high-coercivity minerals upstream in more rural areas to magnetitedominated assemblages downstream. Each river (segment) shows its specific trend line depending on regional initial input, weathering conditions, drainage area, and potential pollution sources. One major outcome of this study is the observed significant correlation between anthropogenic antimony-rich iron oxide particles and the magnetic concentration. This shows the potential of magnetic remanence measurements as proxy parameters for specific heavy metal pollution concentrations. Hence, the environmental magnetic study presented herein serves to identify major trends as well as local particularities and leads to quantitative analyses of the contributions of individual tributaries in the Seine river system.
Geo-Eco-Marina, 2015
In the framework of the Danube Delta geosystem spatial evolution study, new results achieved for sediment cores − this time collected from the Matiţa − Merhei Depression lakes − are added up to the data which were previously published with regard to the Meşteru − Fortuna Depression. Actually, it is the second part of the series of papers dedicated to the magneto − lithological investigation of sediment columns, taken out from various aquatic environments, in both the Fluvial and Marine Delta Plains. Vertical profiles of magnetic susceptibility (MS) and contents of siliciclastic/minerogenic/detrital fraction (SIL), total organic matter (TOM) and carbonate (CAR) are carried out for 9 cores (not longer than 55.5 cm), collected from four lakes (Babina, Matiţa, Polideanca and Bogdaproste), a swamp (Polideanca − Lopatna) and a canal (Lopatna − Polideanca). These records are based on MS (k) measurements (with a Kappabridge KLY-2), and respectively, on lithological component contents analyses (by the "Loss on Ignition"/LOI method), performed on sediment samples obtained by core slicing, at 1-3 cm intervals. MS, SIL, TOM and CAR maps are carried out for surficial sediments, as well, in order to describe the magneto-lithological background which characterizes each of the lakes from where the short sediment cores were extracted. The MS calibration of the lake sediments (core and grab samples) is carried out by using a k scale with 5 classes. The correlation coefficient (r) is calculated for all 6 possible pairs of above specified parameters (SIL vs. k, TOM vs. k, CAR vs. k, SIL vs. TOM, SIL vs. CAR and TOM vs. CAR). To evaluate the correlation size, a scale with 6 steps is used. Positive/direct and negative/reversed correlations have always been obtained for SIL vs. k, and TOM vs. k, respectively. Therefore, new proofs are added to assign the magnetic parameter proxy quality as environmental and sedimentological fingerprinting tool. Another important result of the present study is the detection of some marine clays located very close below the water/sediment interface, intercepted, particularly, at the lower/basal part of two cores from the Babina Lake, two from Matiţa Lake, and another one from the Lopatna − Polideanca Canal. These marine deposits (with macroscopically identified specific fauna) are characterized by clearly different magnetic and lithological signatures (high MS values and SIL contents, low TOM contents), as compared with the fingerprints recovered from the overlying muds (sampled at the upper part of the cores). The presence of a marine episode revealed by some of the sediment cores collected from lakes of the Matiţa − Merhei Depression, which is a part of the Fluvial Delta Plain, is very interesting and can represent a contribution to the better knowledge of the deltaic system temporal and spatial evolution.
Fingerprinting sediment sources in the outlet reservoir of a hilly cultivated catchment in Tunisia
Journal of Soils and Sediments, 2013
Purpose Approximately 74 % of agricultural soils in Tunisia are affected by water erosion, leading to the siltation of numerous human-made reservoirs and therefore a loss of water storage capacity. The objective of this study was to propose a methodology for estimating the relative contributions of gully/channel bank erosion and surface topsoil erosion to the sediment accumulated in small reservoirs.
The Holocene, 2008
Robust identification of catchment suspended sediment sources is a prerequisite both for understanding sediment delivery processes and targeting of effective mitigation measures. Fine sediment delivery can pose universal management problems, especially with regard to nutrient run-off and lake siltation. Here, 19 suspended sediment samplers were located within the three main tributary inflows to Lake Bassenthwaite, a key but vulnerable site of special scientific interest, with water quality problems linked to accelerated delivery of fine sediment. Magnetic properties of contemporary suspended sediments, collected on a monthly basis, were measured on a particle size-specific basis and compared with the lake sediment core-tops. Ferrimagnetic grain size and magnetic `hardness' vary significantly between the suspended sediments collected from the different tributaries, with the 8—31 µm and 31—63 µm clastic grain fractions displaying greatest magnetic contrasts. Postdepositional forma...
A multivariate mixing model for identifying sediment source from magnetic measurements
Quaternary Research, 1989
A sequential method for quantitative identification of sediment source components, based on magnetic measurements, has been developed and tested for sediments from the Rhode River, Maryland. Simulated mixing tests and multiple regression were employed to establish numerical relationships between source component proportions and the magnetic measurements of mixtures. On the basis of these multivariate mixing models, source components of three estuarine sediment cores were estimated by linear programming. The results strongly support the previous studies on this catchment which indicated a dramatic change in sediment source some 150 to 200 yr ago. Quantitative calculations are more useful and informative than purely qualitative descriptions.
Environmental Geology, 2004
Anthropogenic influence, mainly due to urban and industrial activities, may affect fluvial environments and soils, via atmospheric contamination and liquid and solid waste.Continuing previous works on stream sediments and soils, the Gran La Plata area was chosen. In this area, located in the Northeast of Buenos Aires Province (Argentina), several streams and soils were sampled. The streams have similar characteristics, although some of them have a higher input of pollutants (fluvial effluents, fly ashes, solid wastes, etc.). The studied soils have different pedological development.Magnetic and chemical studies were carried out in the laboratory. Analyses of the results indicated that the behavior of magnetic parameters can be related to the variations of heavy metal contents in stream sediments but there is not a good correlation in soils. The comparison between both environments (stream-sediment and soils) reveals a different impact of pollutants. Magnetite, especially PSD grains, seems to be the main carrier for both environments.