Magnetic Properties Of Surface Sediments Research Articles

Modern sedimentation in lakes Chukcha and Bezymyanka, Okhotsk coast

Lakes Chukcha (59°31’56” N; 147° 23’07” E) and Bezymyanka (59°29’56” N; 147°21’02” E) located in the Kava-Taui depression, in the norther cost of Sea of Okhotsk. The thickness of the sediments, rock magnetic properties, sedimentation rates in both lakes are different. The surface bottom sediments of Chukcha lake are heterogeneous in grain composition. The rock magnetic properties of surface sediments are controlled by the grain size. The shallow water sandy sediments show the low of MS, Jrs, Js, and high values of Jp while silt have opposite characteristics. Magnetic minerals from silt are single domain with low content of paramagnetic component. The magnetic properties of fine-grained sediments may be associated with the authigenic (hemogenic) iron sulfides and oxides.

Magnetic susceptibilities of surface sediments from estuary rivers in volcanic regions.

Estuaries have very complex mechanisms because they are influenced by seawater intrusion, which causes enrichment of contaminants in the maximum turbidity area. Magnetic susceptibility measurements have been used for monitoring a wide variety of environments. However, there have been few studies of the magnetic properties of surface sediments from estuaries in volcanic environments in the tropics. This study investigates the magnetic properties and their correlations with the geochemistry of surface sediments in estuaries in volcanic areas and was conducted in the Krueng Aceh River, Indonesia. Measurements consist of magnetic susceptibility measurements, chemical analysis, and mineralogical analysis. Measurements of magnetic susceptibilities were performed using a Bartington MS2 instrument with an MS2B sensor using frequencies of 460 and 46kHz. X-ray fluorescence (XRF) and energy-dispersive spectroscopy (EDS) were used to identify elements in the sediments. Scanning electron microscopy (SEM) analysis was used to analyze sediment grains. X-ray diffraction (XRD) analysis was used to determine mineral contents. For the first time, χLF/χFD ratios were found to be an obvious parameter for identifying areas of sediment traps and metal enrichment in the estuary turbidity maxima (ETM) zone. The magnetic properties carried by volcanic rock minerals consist of pigeonite and enstatite. These two minerals have not been previously considered as carriers of sediments with magnetic properties when monitoring heavy metal enrichment in urban rivers. These results provide an extension of the use of magnetic susceptibility measurements in environmental studies, particularly in estuary river environments in volcanic areas such as the Krueng Aceh River, Indonesia.

Magnetic properties of surface sediments from Liuxi River, southern China and their environmental significance

Magnetic properties of surface sediments from Liuxi River, southern China and their environmental significance

Magnetic properties of the surface sediments from the Huguangyan Maar Lake in tropical Southern China and the sediment source identification

ABSTRACTDeciphering the source(s) of sediment deposited in Hugunagyan Lake in South China using magnetic properties will advance our understanding of the evolution of East Asian monsoon systems. However, the source of magnetic minerals in the surface sediments of this lake is unknown, still needing further exploration. Due to simple hydrological systems, the Hugunagyan Lake provides a unique record for investigating the magnetic property of sediments and surface processes. In this study, based on the magnetic properties of 43 surface sediment, 12 surface soil, and 7 volcanic rock samples from the catchment, we demonstrate that the magnetic minerals in sediments were dominated by fine super paramagnetic magnetic particles, with coexistence of pseudo‐single‐domain states minerals. There are no signatures showing the presence of biogenic and authigenic magnetite. The magnetic properties of surface sediments display significant differences between the potential sources of aeolian dust from the loess in North China and modern surface soils in Central Asia, suggesting that the magnetic minerals mainly originate from the weathered materials in the catchment, and there are no further signals of winter monsoon‐driven aeolian dust input.

Magnetic properties of surface sediments in Schirmacher Oasis, East Antarctica: spatial distribution and controlling factors

PurposeWe investigated the magnetic properties (abundance, grain size, and mineralogy) of iron oxides present in Lake L-55 sediments, Schirmacher Oasis, East Antarctica, with an aim to understand their spatial distribution and the underlying mechanisms that control their formation and distribution.MethodsTwenty-five surficial sediments retrieved from different parts of Lake L-55 were subjected to the entire range of environmental magnetic (magnetic susceptibility, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM)) measurements (at different field strengths). Inter-parametric ratios (χARM/SIRM, χARM/χlf, χARM/χfd, IRM20 mT/SIRM, IRM20 mT/ARM, S-ratio, L-ratio) provided insights into the magnetic properties (abundance, grain size, and mineralogy of iron oxides). Scanning electron microscopic-energy dispersive X-ray spectroscopic (SEM-EDS) analysis was performed on magnetic extracts from a few sediments. Besides, organic matter (%) was also calculated for the sediment samples. Principal component analysis was performed to gain information on the presence of different components and their relative dominance.ResultsThe iron oxides are strongly magnetic (high values of concentration-dependent parameters). The principal iron oxide is magnetite (S-ratio > 0.90) which is coarse-grained (multi-domain (MD) and stable single-domain (SSD) grains), and there is no influence of authigenic greigite, bacterial magnetite, and anthropogenic magnetite. The mineralogy is confirmed by SEM-EDS data. The iron oxides are of different grain sizes, and their contribution is in the order of MD > SSD > SP as shown by the principal component analysis. Pedogenic iron oxide minerals seem to be present in the samples whose formation is due to the oxidation of magnetite into hematite. However, they are of SSD size and not SP, suggesting that the intensity of pedogenesis is not sufficient to form SP grains.ConclusionThe iron oxide minerals are mainly terrigenous, and the biogenic activity within the lake is not sufficient to modify the ferrimagnetic minerals. Spatial distribution patterns suggest the non-uniform distribution of magnetite/titanomagnetite of varying sizes in the lake basin which is transported by both melt water streams and winds.

Distribution of magnetic properties of surface sediment and its implications on sediment provenance and transport in Pearl River Estuary

This study examines the magnetic properties of surface sediments and their implications on sediment provenance and transport in the Lingding Bay (LDB), which is the largest bay of Pearl River Estuary in China. The concentration of magnetic and high-coercivity minerals exhibits a low–high–low distribution pattern in the north–middle–south direction. The western LDB is mainly covered by finer magnetic mineral particles, whereas the eastern LDB is dominated by coarser particles. Three surface sediment provenances (i.e., three groups) are identified according to magnetic properties and particle size. Groups I and III have terrestrial sources from the East River and West/North River, respectively, whereas Group II is from a marine source in the adjacent sea. The distribution of these three sediment provenances and their magnetic properties indicate that surface sediments are transported towards the southern direction with a sediment sink that occurs in the outer LDB, as further confirmed by the grain size trend analysis results. The main sediment depocenter moves southward because of human interventions. The results further suggest that the ratio of saturation isothermal remanent magnetization to magnetic susceptibility (SIRM/χ) may be used as an indicator for distinguishing marine and terrestrial provenances, and the S ratio (S_100) may be employed as an indicator of sediment transport. Our findings demonstrate that sediment magnetic diagnosis provides an efficient approach to trace sediment provenance and transport and thereafter monitors the sediment process impacted by human intervention in estuaries worldwide.

Heavy metal contents and magnetic properties of surface sediments in volcanic and tropical environment from Brantas River, Jawa Timur Province, Indonesia

Brantas River is a largest urban river supplying raw water and drainage in Jawa Timur Province, Indonesia. Dense population along the river is a threat of pollution due to anthropogenic pollutants. In this study, we characterize the magnetic properties and heavy metal contents of surface sediments in various locations along the Brantas River. This study aims to enhance our understanding of the relationship between magnetic parameters and heavy metal contents in surface sediments from river. Surface sediment samples were taken and measured by a series of magnetic measurements, mineralogical analysis and heavy metal contents. The results show that magnetic minerals in surface sediments of Brantas River are dominated by PSD magnetite mineral. This relatively coarser grain size can be caused by magnetic particles produced by erosion around the river. Surface sediments have very high mass-specific magnetic susceptibility varying from 844.0 to 7231.4 × 10−8 m3kg−1 (on average of 3022.9 × 10−8 m3kg−1) because influenced by the surrounding volcanic environment. Magnetic susceptibility can identify and classify enrichment of heavy metals. Based on the Pearson correlation analysis, magnetic susceptibility has strong positive correlation with the heavy metal contents of ferromagnetic elements such as Fe and Co so that it can potentially be used as an indicator of pollution of both these heavy metals in the Brantas River. This present work shows the novelty of the relationship between magnetic susceptibility and heavy metal contents in surface sediments from river in volcanic and tropical environment.

Magnetic properties of surface sediments as proxies of recent anthropogenic pollution in the Anllóns riverbed (NW Spain)

A study of surface sediments from the Anllons riverbed (northwestern Spain) was conducted to assess the use of their magnetic properties as proxies of recent trace element contamination (i.e., As, Zn, Pb, Cr, Ni and Cu). Thermomagnetic curves, hysteresis parameters, specific magnetic susceptibility χ, frequency-dependent magnetic susceptibility κ FD%, magnetic remanence and saturation isothermal remanent magnetization ratios (i.e., S and SIRM/χ) reveal the presence of mostly fine-grained magnetite and maghemite in these samples. The Tomlinson Pollution Load Index (PLI), as well as the magnetic parameters χ, κ FD%, SIRM/χ and S-ratios, vary more or less in agreement to each other when they are sequentially arranged throughout a 30-km-long transect that goes from the town of Carballo to the river mouth in Ponteceso. From that profile, it is possible to identify an anomaly of χ that lies between two small peaks of the PLI and seems to define a contaminated area probably linked to a diffuse low-impact source of pollution. There is also a conspicuous peak of the PLI that is likely associated to a nearby gold mine. The variations of the κ FD%’s along the transect are the ones that best reflect the changes in the PLI values, regardless of the level of contamination. This result suggests that adsorption is the main mechanism of trace elements removal by Fe oxides in these samples. Direct signal analyses, used to decompose the isothermal remanent magnetization curves, reveal the presence of four magnetic fractions, with varying relative concentrations all over the profile, namely single-domain magnetite, close to the superparamagnetic threshold (SD/SP) and/or maghemite ( $$\log B_{1/2}$$ ca 1.2), single-domain magnetite ( $$\log B_{1/2}$$ ca 2), hematite ( $$\log B_{1/2}$$ ca 2.5) and goethite ( $$\log B_{1/2}$$ ca 3.5). Integrating all the available information, it was sketched out a likely sequence of events that included magnetic minerals neoformation in parent soils, their subsequent chemical transformations and the contamination episodes that affected the region.

Magnetic properties of surface sediments from the Pearl River Estuary and its adjacent waters: Implication for provenance

Environmental magnetism has been widely used as a rapid, cost-effective, and non-destructive method in various fields including sediment source identification. Nineteen surface sediments from ten transects in the Pearl River Estuary (PRE) and its adjacent seas were studied for magnetic measurements. Combined with mineral analysis for representative samples, magnetic implications for provenance are discussed. The results indicate that concentration-dependent magnetic parameters decrease gradually and change sharply between the PRE and its adjacent waters. The magnetic mineral assemblage is basically consistent at all sites, i.e. consisting of magnetite and hematite. However, the grain size of magnetite particles is clearly different probably due to different material sources. Magnetic parameters allow separating the sediments from the PRE and its adjacent seas into three groups, more distinctively than deduced from clay mineral analysis. These new findings indicate that magnetic properties of surface sediments bring complementary information of material source as well as marine geology.

Regional variations in magnetic properties of surface sediments in the Qaidam Basin and their paleoenvironmental implications

The Qaidam Basin is the largest intermontane basin on the northeastern edge of the Tibetan Plateau. At present, systematic rock magnetic studies of surface sediments in this basin are scarce because of the vast area and poor accessibility. In this paper, multi-parameter rock magnetic investigations of surface sediments from a wide area in the Qaidam Basin have been conducted. We find that pseudo-single domain and multidomain ferrimagnetic minerals (i.e. magnetite and maghemite) dominate the magnetic properties of surface sediments in the basin. Surface sediments from the western part of the basin exhibit the lowest magnetic concentration values χ, χARM and SIRM. In contrast, samples from the upwind sides of the basin and the eastern margin of the basin show the highest magnetic concentration values. The spatial distribution of magnetic parameters in the Qaidam Basin suggest that wind environments and the supply of clastic sediments possibly provide the main control on the regional variations of magnetic parameters. Our results also provide new insights into the mechanisms of magnetic variations of late Pliocene lacustrine sediments in the western Qaidam Basin.

A new dimension to sediment magnetism: Charting the spatial variability of magnetic properties across lake basins

We have investigated the variability of the magnetic properties of surface sediments across eight Minnesota lake basins. The measured magnetic properties are controlled by the competing fluxes of allochthonous and autochthonous magnetic particles, and differ according to location in the basin. Shoreline sediments are dominated by detrital magnetic particles, whereas littoral and profundal sediments are characterized by a combination of bacterial magnetosomes and detrital particles. The position of the oxic–anoxic interface, which may occur in the water or within the sediment column, controls the depth at which living magnetotactic bacteria occur, and determines the degree of preservation of their magnetosome chains in the surface sediment. The preservation potential of undisturbed chains is higher for bacterial magnetite formed at the top of the sediment column in the littoral area than for magnetosomes originating in the water column in the profundal area. Bacterial magnetite in the profundal facies will contain a higher proportion of chains collapsed during settlement through the water column to the lake bottom. This process increases the fraction of interacting magnetosomes, which in turn artificially lowers the ARM ratio (χARM/IRM), which ceases to be a reliable grain size indicator in the profundal environment. Our results indicate that a holistic approach to interpreting limnologically-derived paleoecological data should be employed. Specifically, a thorough understanding of evolving and interrelated factors such as basin morphology and limnologic conditions is crucial for a more confident interpretation of the sedimentary record in terms of environmental conditions at the time of sediment deposition.

Mineral magnetic properties of surface sediments at Bei’anhe, Beijing, and its environmental significance

A multiparameter investigation of surface sediments from the Bei’anhe section (Beijing) has been conducted using environmental magnetic approaches. The studied sedimentary sequence consists of pluvial and lacustrine silts and clay of the Holocene age. Magnetite, hematite and pyrrhotite were identified as the dominant magnetic minerals. The mineral magnetic characteristics are considered to reflect the Holocene paleoenvironmental processes of the studied area, which are different from the mineral magnetic properties of typical polluted sections reported in the Beijing area. The low-field magnetic susceptibility and saturated isothermal remanence magnetization of the section decrease gradually with increasing depth. This indicates that the concentration of magnetic minerals in the strata decreases down the section. Values of interparametric ratios, such as ARM/SIRM, χ ARM/χ and SIRM/χ, gradually increase with increasing depth, which indicates a down-section decreasing trend in the magnetic grain size of the sediments. Pyrrhotite occurs below the depth of 22 cm, suggesting the existence of redox interface. The magnetic variations of the Bei’anhe surface sediments might be controlled by two geological processes: reductive diagenesis and pedogenesis. Our findings may have provided a reference point for magnetic investigation of polluted surface sediments in the Beijing area.

Rock magnetic properties of the fine-grained sediment on the outer shelf of the East China Sea: implication for provenance

The rock magnetic properties of surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea, an area surrounded by sands, were investigated with a view to providing information on the sediment provenance. Multiple magnetic parameters such as magnetic susceptibility, anhysteretic remanent magnetization, saturation remanent magnetization (SIRM), coercivities of SIRM, and S ratios (relative abundance of low-coercivity magnetic minerals) were measured for all 179 surface samples, and partial representative samples were examined for their magnetic hysteresis parameters, temperature dependence of magnetic susceptibility and X-ray diffraction spectra. Our research indicates that the magnetic mineralogy is dominated by magnetite with a small amount of hematite and is primarily of a pseudo-single-domain to multidomain nature with a detrital origin. The magnetic concentration in the study area generally decreases to the east or southeast accompanied by magnetic particle fining to the east or northeast. The geographic pattern of magnetic properties is most reasonably explained by a major source of sediment jointly from the erosion of the old Huanghe River deposit and the discharge of the Changjiang River. The rock magnetic data facilitate understanding of the transport mechanism of fine-grained sediments in the outer shelf of the East China Sea.

Mineral magnetic and textural interpretations of sedimentation in the Skagerrak, eastern North Sea

The mineral magnetic properties of surface sediments in the northern Skagerrak show systematic trends which allow the identification of sediment provinces and the interpretation of transport pathways. This application is especially valuable considering the importance and difficulty of environmental analyses involving fine grained deposits. Magnetic susceptibility (χ) and saturation isothermal remanent magnetisation (SIRM) have different geographic patterns, but their individual trends are consistent in the Skagerrak muds (clay content 25–60%). Over the entire studied area the χ values correlate positively with general trends in particle size, whereas SIRM does not show particle size dependency. The present study confirms that the majority of sediments accumulating in the northern Skagerrak are supplied from the south. The mineral magnetic parameters facilitate detailed tracking of the counterclockwise transport of sediments around and into the Norwegian Trench.