张卫国
自然地理学、环境磁学、沉积物来源判别和追踪、古环境变化、环境污染、海岸带的陆海相互作用。
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- 姓名:张卫国
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学术头衔:
博士生导师, 教育部“新世纪优秀人才支持计划”入选者
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学科领域:
自然地理学(包括化学地理学、生态地理学、地貌学、冰)
- 研究兴趣:自然地理学、环境磁学、沉积物来源判别和追踪、古环境变化、环境污染、海岸带的陆海相互作用。
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张卫国, Weiguo Zhang a, *, Lizhong Yu a, Min Lu b, Xiangmin Zheng b, Junfeng Ji c, Limin Zhou b, Xiaoyong Wang b
Quaternary Science Reviews, 28 (2009) 345~353,-0001,():
-1年11月30日
The Xiashu Loess, in comparison to the well-studied loess sequences in the Chinese Loess Plateau (CLP), provides a good opportunity for studying East Asian monsoon variations from a southern China perspective. Here we present a study of the iron oxide mineralogy of the Xiashu Loess using integrated geochemical and diffuse reflectance spectroscopy (DRS) measurements as well as magnetic data. Our results show that the free iron oxide (Fed) to total iron (Fet) ratio (Fed/Fet), hematite (Hm) to goethite (Gt) ratio (Hm/Gt) and saturation isothermal remanent magnetization (SIRM) to magnetic susceptibility (c) ratio (SIRM/X) all indicate particularly strong summer monsoons during the formation of paleosols PS5 and PS4 (equivalent to Marine Isotope Stage 13 and 11, respectively). However, magnetic susceptibility and Fed/Fet are not consistently reliable indicators of summer monsoon intensity for the whole section. Our results indicate that a multi-proxy approach can give a more reliable summer monsoon intensity reconstruction. The summer monsoon shows a cooling trend and a declining of precipitation from 0.5to~0.3Ma, after which it becomes warmer and wetter towards the top of paleosol PS1 (equivalent to MIS5). However, PS1 was formed under a relatively cooler temperature and wetter soil conditions in comparison to PS5 and PS4. Such supra-orbital variations in the East Asian summer monsoon super-imposed on the effects of glacial-interglacial cycles in southern China are also reflected in the 0.4-0.5 Macycle of marine carbon isotopes in the global ocean, possibly indicating a strong link between terrestrial weathering and the global carbon cycle.
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张卫国, Weiguo Zhang a, Huan Feng b, *, Jinna Chang a, Jianguo Qu a, Hongxia Xie a, Lizhong Yu a
Environmental Pollution, 157 (2009), 1533~1543,-0001,():
-1年11月30日
Surface sediments (0-5cm) from 59 stations within the Yangtze River intertidal zone (YRIZ) were sampled for metal contamination analysis in April and August 2005. The concentrations ranged (in mg kg-1 dry weight): Al, 40,803-97,213; Fe, 20,538-49,627; Cd, 0.12-0.75; Cr, 36.9-173; Cu, 6.87-49.7; Mn, 413-1,112; Ni, 17.6-48.0; Pb, 18.3-44.1; and Zn, 47.6-154; respectively. Among the 59 sampling stations, enrichment factors (EF) indicate enrichment of Cd (52 stations), Cr (54 stations), Cu (5 stations), Ni (26 stations), Pb (5 stations) and Zn (5 stations). Geoaccumulation indexes (Igeo) also suggest individual metal contamination in localized areas. This study indicates that Cd, Cr and Nienrichment in the YRIZ sediment is widespread whereas Cu, Mn, Pb and Zn enrichment is localized or nonexistent. Factor and cluster analyses indicate that Cd is associated with total organic carbon whereas Cu, Cr, Ni, Pb and Zn have a close association with Mn.
Yangtze River estuary, Intertidal zone sediments, Heavy metals, Contamination, Sediment quality criteria
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张卫国, Xue-Feng Hu a, b, *, JiWei b, Liang-Feng Xu b, Gan-Lin Zhang a, Wei-Guo Zhang c
Palaeogeography, Palaeoclimatology, Palaeoecology, 279 (2009), 216~232,-0001,():
-1年11月30日
Magnetic susceptibility (χif) and other magnetic parameters of 11 typical profiles of Quaternary Red Clay (QRC) in subtropical China were measured. χlf curves of the QRC profiles show similar vertical variations: χlf of the uppermost yellow-brown earth (YBE) and uniform red clay (URC) of the profiles is high, mostly ranging from 50 to 150×10-8 m3 kg-1; that of the reticulate red clay (RRC) sharply decreases downwards. Especially in the Lower RRC (LRRC) with dense reticulate pattern, χif is often less than 10×10-8 m3 kg-1. Grain-size characteristics and geochemical properties of the QRC suggest that the sharp decrease of χif in the RRC is not related to sudden change of parent materials, but to the formation of the reticulate pattern. Further study indicates that pedogenic fine ferrimagnetic minerals (FM) (superparamagnetic particles (SP) and/or stable single domain (SSD)) are the main magnetic carriers of the QRC. The YBE and URC, with higher χif, show low coercivity and magnetic soft behavior; the RRC, especially the LRRC, with weak magnetism, shows high coercivity and magnetic hard behavior. The temperature-dependent susceptibility (TDS) of the QRC suggests that the dominant type of FM in the YBE and URC is pedogenic maghemite; the RRC, especially the LRRC, however, contains little maghemite but a trace amount of lithogenic multi-domain (MD) magnetite inherited from the parent rock. During post-depositional hydromorphic processes, pedogenic maghemite was more easily dissolved than hematite, which caused the sharp decrease of χif in the RRC. As χif of the QRC was mainly controlled by the intensity of hydromorphic processes, rather than the weathering degree, χif of the QRC in subtropical China cannot accurately indicate the paleoclimate during the Quaternary period, when the red clay was initially formed.
Quaternary Red Clay (, QRC), , Reticulate pattern, Magnetic susceptibility (, χif), , Ferrimagnetic minerals (, FM), , Paleoclimate
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张卫国, Xuerong Dai a, *, J.A. Dearing b, Lizhong Yu c, Weiguo Zhang c, Yuxin Shi a, Furui Zhang a, Chengjun Gu a, J.F. Boyle b, T.J. Coulthard d, G.C. Foster b
Geomorphology 106 (2009) 363~375,-0001,():
-1年11月30日
This paper describes 20th century climate and human impacts on terrestrial and fluvial systems in the Dabie Mountains, Anhui Province, China, based on analyses of four types of information. Analyses of particle size, mineral magnetism, organic carbon, nitrogen and phosphorus in a sediment core taken from the Longhekou reservoir, built in 1958 AD in the upper reaches of Hangbu River, provide an ~45 year record of fluvial responses, while monitored meteorological and hydrological data provide records of climate and river discharge. Census data compiled for the local Shucheng County provide records of population and land use, complemented with analyses of satellite images. The Xiaotian river delivers over 65% of the total water and silt to the reservoir. Analyses indicate that the fluvial regime tracks the monsoon climate over seasonal timescales, but human activities have a strongly mediating effect on sediment supply, sediment delivery and, to a lesser extent, runoff over longer timescales. Notable periods of human impact on erosion include the Great Leap Forward (1958-1960) and Great Cultural Revolution (1966-1976). A rising trend in precipitation and new land use changes at the present time may be leading to an enhanced flood risk.
Dabie Mountains, Erosion, Flooding, Monsoon, Human impacts, Climate change
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张卫国, DONG RUIBIN, ZHANG WEIGUO, LU SHENGGAO, YU LIZHONG and YU JINYAN
Pedosphere 13 (2): 103~110, 2003,-0001,():
-1年11月30日
Five soils derived from different parent materials were sampled from red so ll region of so uthern China and studied by magnetic methodology to understand to what extent iron reduction would afect so ll magnetic properties and how iron reduction would afect the magnetic minerals in soils. Reduction associated with organic matter decomposition strongly afected so il magnetic parameters at low pH. The losses of orlginal soil magnetic signals in terms of magnetic susceptibility (x), ‘Soft’isothermal remanent magnetization ('Soft' IRM), anhysteretic remanent magnetization (ARM)and saturation isothermal remanent magnetization (SIRM)at pH 4—6 during the two-month saturation treatment, were 66%~94%, 54%~90%, 64%~95%and 33%~83%, respectively. These changes were interpreted as a consequence of substantial dissolution of maghaemite and haematite in the soils. At pH 10, however, there was no significant magnetic changeobserved. M oreover, stable single domain soil maghaemite grains were also sensitive to red uction, which suggested that both pedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite, instead, was the most stable iron form under reducing conditions.
goethite, haematite, maghaemite, magnetic susceptibility, reduction
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张卫国, Weiguo Zhang a, *, Lizhong Yu a, Min Lu b, Xiangmin Zheng b, Yuxin Shi b
Earth and Planetary Science Letters 260 (2007) 86–97,-0001,():
-1年11月30日
Variations in the magnetic susceptibility of Chinese loess have been used to indicate pedogenic intensity and therefore past climate across the Chinese Loess Plateau (CLP). However, the relationship between climate and magnetic properties has not been fully resolved, and therefore a study of loess sections distributed over a wider climatic region is timely. In this study, we have investigated a 22.1 m loess section (named the Xiashu Loess) at Dagang, China, by integrating both rock magnetic and geochemical proxies. This loess profile is situated in a modern subtropical climate region with annual mean precipitation and temperature of 1100 mm and 15.4 °C, respectively, and therefore has experienced a stronger weathering intensity due to its lower latitude, higher temperature and rainfall. Geochemical and magnetic evidence indicate the same source area for the Xiashu Loess as for loess in northern China. The magnetic mineral assemblage of the Xiashu Loess is dominated by a higher concentration of superparamagnetic (SP)/single domain (SD) magnetite/maghemite grains in strongly weathered paleosols than in the loess layers, consistent with the production of fine-grained ferrimagnetic minerals during pedogenic processes. Nevertheless, compared to loess in the CLP, the Xiashu Loess shows: 1) reduced contrasts in magnetic susceptibility (χ), Hard Isothermal Remanent Magnetization (HIRM) and remanence of coercivity (Bcr) between loess and paleosols units, which indicates that the loess units have undergone stronger pedogenic alterations; 2) lower peak values of HIRM and χ in paleosols. In addition, the ratios SIRM/χ, χARM/SIRM (where SIRM and χARM are Saturation Isothermal Remanent Magnetization and the susceptibility of Anhysteretic Remanent Magnetization, respectively) and Bcr are found to be significantly correlated with the quotient (CaO*+Na2O+MgO)/TiO2, a geochemical indicator of pedogenic intensity. Overall, it seems that pedogenic processes in the Xiashu Loess lead to a relative increase in fine-grained ferrimagnetic SP/SD grains but depletion of anti-ferromagnetic minerals. Magnetic and geochemical proxies indicate strengthened East Asia summer monsoon during Marine Isotope Stages 13, 11 and 5, which is in good agreement with the records from the CLP and the South China Sea.
magnetic properties, geochemistry, pedogenic intensity, loess, Xiashu Loess, China
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张卫国, Weiguo Zhang a, *, Lizhong Yu a, Min Lu b, Simon M. Hutchinson c, Huan Feng d
Environmental Pollution 147 (2007) 238~244,-0001,():
-1年11月30日
In this study, mineral magnetic, particle size and geochemical analyses were conducted on intertidal sediments from the Yangtze Estuary to examine the feasibility of heavy metal concentrations normalization using magnetic techniques. Susceptibility of Anhysteretic Remanent Magnetization (χARM), the ratio of χARM to SIRM (Saturation Isothermal Remanent Magnetization) and susceptibility (χARM/SIRM and χARM/χ, respectively), and to a lesser degree, frequency dependent susceptibility (xfd), displayed significant correlations with the fine sediment fraction (<16µm). The strong relationships between χARM and heavy metals can be explained by the role of particle size and iron oxides in controlling metal concentrations. This study demonstrates that χARM can be used to normalize for particle size effects as efficiently as common reference elements such as Al. Furthermore, the rapid and non-destructive nature of mineral magnetic measurement technique means that χARM has a considerable application value in environmental quality monitoring and related studies.
Heavy metal, Particle size, Normalization, Magnetic method, Yangtze Estuary
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【期刊论文】Sedimentation rates in relation to sedimentary processes of the Yangtze Estuary, China
张卫国, Taoyuan Wei a, Zhongyuan Chen b, *, Lingyun Duan a, Jiawei Gu a, Yoshiki Saito c, Weiguo Zhang b, Yonghong Wang d, Yutaka Kanai e
Estuarine, Coastal and Shelf Science 71 (2007) 37~46,-0001,():
-1年11月30日
DEM, radioisotope measurement, deltaic depocenter, sedimentation rate, Yangtze Estuary
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张卫国, Huan Feng a, *, Xiaofei Han b, , Weiguo Zhang b, Lizhong Yu b
Marine Pollution Bulletin 49 (2004) 910–915,-0001,():
-1年11月30日
Three short sediment cores (<20cm) were collected in the high, middle and low tidal flats in the Yangtze River Estuary near the Southern (Nanqu) Sewage Outlet, one of the three largest sewage outlets in Shanghai, China. All samples were analyzed for Al, Cu, Pb, Zn, 210Pb and 7Be. The 210Pbxs profile shows a non-steady-state sedimentation pattern in the study area and 7Be is only found in the upper 1 cm layer of sediment in high and middle tidal flats. In this study, we found that Cu, Pb and Zn contaminants are present in the upper 20cm of the tidal flat sediment and, after normalizing with Al, the contamination is more striking in the upper~5cm sediment. Relationships between the metal (Cu, Pb and Zn) enrichment factor and 210Pbxs activity suggest that contamination increases with time. Factor analyses shows that differences in sediment grain size have insignificant effects on Cu and Pb concentrations, but have some influence on Zn concentration in the study area. This preliminary study shows that urbanization and recent coastal wetland reclamation have had an environmental impact on this area.
Yangtze River Estuary, Intertidal zone, Heavy metal, Sediment, ontamination, Natural radionuclides
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张卫国, DONG RUIBIN, ZHANG WEIGUO, LU SHENGGAO, YU LIZHONG and YU JINYAN
Pedosphere 13 (2): 103~110, 2003,-0001,():
-1年11月30日
Five soils derived from different parent materials were sampled from red so ll region of so uthern China and studied by magnetic methodology to understand to what extent iron reduction would afect so ll magnetic properties and how iron reduction would afect the magnetic minerals in soils. Reduction associated with organic matter decomposition strongly afected so il magnetic parameters at low pH. The losses of orlginal soil magnetic signals in terms of magnetic susceptibility (x), 'Soft' isothermal remanent magnetization ('Soft' IRM), anhysteretic remanent magnetization (ARM)and saturation isothermal remanent magnetization (SIRM)at pH 4—6 during the two-month saturation treatment, were 66%~94%, 54%~90%, 64%~95%and 33%~83%, respectively. These changes were interpreted as a consequence of substantial dissolutionof maghaemite and haematite in the soils. At pH 10, however, there was no significant magnetic change observed. M oreover, stable single domain soil maghaemite grains were also sensitive to red uction, which suggested that both pedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite, instead, was the most stable iron form under reducing conditions.
goethite, haematite, maghaemite, magnetic susceptibility, reduction
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