Magnetic mineralogy of a weathered tropical basalt, Hainan Island, South China

Ouyang, Tingping; Tang, Zhihua; Zhao, Xiang; Tian, Chong‐Bin; Ma, Jianqi; Wei, Gangjian; Huang, Ningsheng; Li, Mingkun; Bian, Yong

doi:10.1016/j.pepi.2015.01.001

Cited by 20 publications

(10 citation statements)

References 77 publications

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“…3). The second component (C2) with B 1/2 of several hundreds mT is likely related to hematite 42,43 . The low-coercivity component (C1) probably reflects the fraction of magnetite and maghemite as the existence of these phases is suggested by the shape of the κ-T curves.…”

Section: Resultsmentioning

confidence: 99%

Magnetic response of Arsenic pollution in a slag covered soil profile close to an abandoned tungsten mine, southern China

Ouyang

Appel

et al. 2020

Sci Rep

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previous studies indicated serious soil arsenic (As) pollution of large spatial extent related to tungsten mining. We performed systematic analyses of magnetic parameters and As contents of a slag covered soil profile close to the abandoned tungsten mine in southern China, in order to discuss the feasibility of using sensitive, non-destructive, and cost-effective magnetic methods for monitoring the soil arsenic content in such arsenic pollution areas. The results indicate that arsenic sulfide entered from slags into the underlying soil and changed to iron arsenate and moveable arsenic ion. The arsenic ions were transported from the upper to the lower part of the soil profile, leading to more serious arsenic pollution at lower levels of the section. Pedogenesis and oxidation of the entered iron and arsenic sulfide resulted in coexistence of magnetite/maghemite and hematite, with different contributions at depths of 125-195 cm, 60-125 cm, and 0-60 cm. The arsenic content is significant positively correlated with the hematite concentration given by the magnetic parameter HIRM and negatively correlated with the S −300 ratio that measures the relative contributions of magnetite(+maghemite) and hematite. the S −300 ratio is effective for semi-quantification of soil arsenic content, and may be also used for soil arsenic pollution assessment and monitoring in similar settings of tungsten mining.Soil environment has been becoming one of the hottest issues of environmental science as well as environmental protection agency. As well known, mine utilization usually seriously affects the surrounding soil environment. Particularly, exploitation of metallic ore always leads to heavy metal pollution 1-3 . Serious heavy metal pollution frequently appeared worldwide 4-7 . Previous studies indicated that both surface and deep soils within and around metallic mine area such as the Lianhuashan abandoned tungsten mine at south China are being experienced serious arsenic pollution 8,9 . According to the "Law of the People's Republic of China on the prevention and control of soil pollution", soils within and around thus mine area are the key monitoring objects of heavy metal pollution. Therefore, rapid monitoring and identification of heavy metal pollution in soil within and around mining areas are a necessary prerequisite for mine environmental impact assessment and repair of mining damages. Rapid and effective methods are urgently needed for heavy metal content monitoring and pollution assessment.Environmental magnetic methods have several advantages such as rapidness, sensitiveness, nondestructiveness, and cost-effectiveness 10,11 . Magnetic approaches were widely applied for soil heavy metal content monitoring and pollution assessment during the last decades 12-15 . Many studies indicated significant positive correlations between soil magnetic parameters (e.g., magnetic susceptibility, MS) and heavy metal contents. Thus, in some studies, MS was regarded as an effective indicator for heavy metal contamination in soil [16][17][18] . H...

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Section: Resultsmentioning

confidence: 99%

Magnetic response of Arsenic pollution in a slag covered soil profile close to an abandoned tungsten mine, southern China

Ouyang

Appel

et al. 2020

Sci Rep

Self Cite

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“…The coercive force of ~100 nm sized Mgt increases from 25 to 50 mT with a 10% increase in Ti content [ Dunlop and Özdemir , ], which can explain the high B cr of PSD TM observed in this study. Ouyang et al [] also identified a component with B 1/2 of 101 mT as titanium‐poor TM in samples from the bottom of a weathered basalt profile in the same area. Moreover, the T C of TM decreases as the concentration of Ti increases and drops to 565°C with a 10% increase in Ti content [ Dunlop and Özdemir , ; Jiang et al , ; O'Reilly , ].…”

Section: Resultsmentioning

confidence: 99%

“…Component 3 with a B 1/2 of ~200 mT in samples from the SMZ (CM‐22.6, CM‐23.0, and CM‐23.5) is fine‐grained pedogenic Hm (Table ). Ouyang et al [] suggested that a component with B 1/2 of ~200 mT was pedogenic Hm in a profile of weathered basalt. This component is also present in red clay [ Nie et al , ] and loess [ Hu et al , ] on the CLP.…”

Section: Resultsmentioning

confidence: 99%

“…For sample CM‐44.7, the Mgt is probably titanium‐poor. Basalts from northern Hainan Island generally contain primary (titano‐)magnetite [ Ho et al , ; Ma et al , ; Ouyang et al , ]. The T C of TM decreases as the concentration of Ti increases and drops to 565°C with an increase in Ti content of 10% [ Dunlop and Özdemir , ; Jiang et al , ; O'Reilly , ].…”

Section: Resultsmentioning

confidence: 99%

“…For example, Van Dam et al [] documented that magnetic properties of basaltic substrate soils in tropical Hawaii generally increase with increasing soil development. However, Ouyang et al [] studied a 4.5 m long weathered basalt section from a location with a MAP of ~1500 mm/yr and suggested that the coarse (pseudo‐single domain; PSD) magnetic particles in the parent basalt were transformed into SD particles in the middle of the section and superparamagnetic (SP) and SD particles in the upper part. Although fine magnetic particles were formed, the topsoil had a lower χ than the parent basalt.…”

Section: Introductionmentioning

confidence: 99%

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Magnetism of a red soil core derived from basalt, northern Hainan Island, China: Volcanic ash versus pedogenesis

Liu

Wei

et al. 2017

JGR Solid Earth

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Similar to loess‐paleosol sequences in northwestern China, terrestrial sedimentary sequences (red soils) in southern China also provide sensitive Quaternary records of subtropical/tropical paleoclimate and paleoenvironment. Compared with red clay sequences originated from eolian dust, red soils derived from bedrock have received little attention. In this study, a long core of red soil derived from weathered basalt in northern Hainan Island, China, was systematically investigated by using detailed magnetic measurements and rare earth element analyses. The results show that an extremely strong magnetic zone with a maximum magnetic susceptibility (>10 × 10−5 m3 kg−1) is interbedded in the middle of the core profile. This layer contains a significant amount of superparamagnetic magnetite/maghemite particles that primarily originated from volcanic ash, with secondary contributions from pedogenesis. The former has an average grain size of ~19 nm with a normal distribution of volume, and the latter has a much wider grain size distribution. The presence of volcanic ash within the red soil indicates that these Quaternary basalts were not formed by continuous volcanic eruptions. Moreover, the magnetic enhancement patterns differ between the upper and lower zones. The upper zone is more magnetically enhanced and experienced higher precipitation and temperature than the lower zone. Discrimination of superparamagnetic particles originating from pedogenic processes and volcanic ash thus provides a sound theoretical base for accurate interpretation of magnetism in red soils in this region.

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Relationship between magnetic properties and weathering in red soil profiles developed on weakly magnetic parent rock in the tropical and subtropical region of Yunnan, China

Li,

Zhang,

et al. 2024

Acta Geophys.

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Magnetic studies of loess-paleosol sequences have shown that the magnetic properties of loess and its parent material is sensitive to weathering degree. However, the relationship between magnetic properties and weathering processes in red soils of southern China remains unclear due to the diversity of parent rocks and the in uence of climate. This study focused on red soils developed on weakly magnetic sandstone, in tropical and subtropical regions of Yunnan, China. The principal element content, magnetic susceptibility, temperature-dependent susceptibility curve( -T curves), hysteresis loop and Isothermal Remanent Magnetization (IRM) of the samples were determined, the weathering characteristics and magnetic properties of pro le samples were analyzed, and their relationship was examined, as well as the impact of climate change on ne-grained ferrimagnetic minerals and magnetic properties. The results revealed that red soils developed on weakly magnetic sandstone exhibited signi cant correlations between three magnetic indices, low-frequency magnetic susceptibility (χ lf ), frequency-dependent susceptibility (χ fd ),(χ post−pre + χ d )/ χ para , and the silica-sesquioxide ratio (SAF), indicating that these indices can be used to assess soil weathering. Additionally, this study proposed a new index based on the 1 < Log10B h < 1.5 mT component obtained from decomposition of the IRM curve, which can also be used to assess soil weathering. The enhancement of magnetic properties in red soils along a single pro le was found to be related to the increase in the content of negrained ferrimagnetic com-ponents controlled by weathering. Comparing the two climatic regions, it was found that in Yunnan, China, as the climate changes from subtropical humid to tropical humid, the weathering of the red soil pro les becomes stronger, and the ne-grained ferrimagnetic components increase, indirectly enhancing the magnetic properties of red soils.

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Magnetic mineralogy of a weathered tropical basalt, Hainan Island, South China

Cited by 20 publications

References 77 publications

Magnetic response of Arsenic pollution in a slag covered soil profile close to an abandoned tungsten mine, southern China

Magnetic response of Arsenic pollution in a slag covered soil profile close to an abandoned tungsten mine, southern China

Magnetism of a red soil core derived from basalt, northern Hainan Island, China: Volcanic ash versus pedogenesis

Relationship between magnetic properties and weathering in red soil profiles developed on weakly magnetic parent rock in the tropical and subtropical region of Yunnan, China

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