南方地区土壤重金属污染的磁响应特征——以金华地区为例

为了明确在运用环境磁学方法进行重金属污染评价时其所适用的土壤类型和磁学参数,对金华地区农田表层土壤进行了系统的环境磁学调查,分析南方地区土壤重金属污染的磁响应特征.结果表明：1)盆地内污染土壤的磁性突出表现为高磁化率值、高硬剩磁值及低的非磁滞剩磁磁化率与磁化率比值,与我国北方重污染土壤的磁性特征基本一致;2)水稻土表现为低磁化率值和极高的非磁滞剩磁磁化率与磁化率比值,与污染土壤磁学特征差别大,十分适合于使用环境磁学方法快速监测土壤重金属污染;3)山地丘陵土壤表现出较高的磁化率值和硬剩磁值,以及低的非磁滞剩磁磁化率与磁化率比值,与盆地内污染土壤的磁性较为相似.综上,在该地区运用环境磁学方法进行土壤污染监测时,土壤类型的磁背景差异不可忽视,应根据土壤类型差异慎重选取评价参数.     

徐州城市表层土壤中硫与磁学参数的关系及其环境意义

比较系统地采集了徐州城市表层土壤样品20件,测定和计算了土壤样品中元素S和Fe的含量以及5个磁学参数(即质量磁化率(χ)、非磁滞剩余磁化率(χARM)、软等温剩磁(SOFT)、饱和等温剩磁(SIRM),以及频率磁化率(χFD)的数值。结果表明,与本区土壤中S的背景值相比,徐州城市表层土壤样品中富集较高浓度的S,且S的含量与磁学参数(质量磁化率、非磁滞剩余磁化率、软等温剩磁、饱和等温剩磁)的数值呈显著正相关,与频率磁化率的数值呈弱的负相关。徐州城市表层土壤中磁性矿物与表层土壤中S以及大气环境的SO2有相同的人为发生源,因此可以在一定程度上利用磁学测量技术初步评估该区域过去大气中SO2污染强度。     

基于粒级分离的长江口及邻近陆架沉积物磁性特征及其环境意义

在粒级分离的基础上,对长江河口及邻近陆架22个表层沉积物进行了磁学表征,探讨了磁性特征对物源、输运、沉积动力等环境信息的指示意义.研究结果表明,长江入海泥沙、残留砂及废黄河物质是长江口外水下三角洲及邻近陆架沉积物磁性特征的主要物源影响因素,但3者的空间分布不同.沉积物磁化率(x)、饱和等温剩磁(SIRM)、硬剩磁(HI...     

中国黄土沉积物的磁性增强机制进展

中国黄土沉积物很好地记录了第四纪以来丰富的地磁场和古气候信息,岩石磁学、环境磁学在第四纪古环境研究中扮演着及其重要的角色.通过回顾近年来中国黄土沉积物研究取得的一系列成果,总结黄土沉积物磁性增强的主导机制,并提出黄土研究中今后应注意的问题,如成土作用、埋藏、浅育化作用等对剩磁记录的影响和磁学信息的分离等.     

滇池东部第四系浅层湖滨相沉积物磁学特征及其环境意义

为了探究昆明盆地第四纪以来的总体气候特征及滇池湖泊的演化规律。本文综合环境磁学、TOC、pH等指标,对滇池东岸DC1钻孔岩芯沉积物进行了系统研究,测试了包括质量磁化率（χ）、非磁滞剩磁（ARM）、饱和等温剩磁（SIRM）、低频磁化率（χlf）、高频磁化率（χhf）、软剩磁（IRM-300mT）、pH值及总有机碳（TOC）。结果显示：DC1沉积物磁性特征由亚铁磁性矿物主导,反铁磁性的赤铁矿在0.3-3.6 m与14.7-15.6 m两个区段含量相对较高,结合赤铁矿的形成环境,反映了这两个区段对应的沉积环境为湖退时期;另外,结合TOC与磁化率在不同深度上的关系,表明TOC的高值与细颗粒的磁性矿物溶解有关。结合TOC在各区段的含量特征表明整个21 m沉积过程所对应的气候类型以温暖气候为主。     

西藏申扎地区晚古生代地层岩石磁学研究

目的研究西藏申扎地区晚古生代地层载磁矿物特征,为构造磁学等提供依据。方法运用饱和等温剩磁(SIRM),三轴等温剩磁(SIRM)热退磁,磁化率-温度(χ-T)曲线和NRM热退磁实验等方法进行综合分析。结果中—上二叠统样品中含较多针铁矿、赤铁矿;下二叠统和石炭系样品中以磁铁矿为主;泥盆系样品中富集铁硫化物。结论该套沉积地层中具有不同磁学特征的磁性矿物共生组合,可能导致岩石剩磁获得过程相对复杂;剖面上磁性矿物组合的变化,蕴含着沉积环境演化的信息。     

土壤频率磁化率与矿物粒度的关系及其环境意义

对土壤频率磁化率(xfd)与磁性矿物颗粒大小的关系及其环境意义进行了讨论．频率磁化率主要反映超顺磁性(SP)—稳定单畴(SSD)过渡态磁性颗粒的数量,对风化成土过程中形成的土壤成因磁性矿物具有指示作用．结果表明热带亚热带土壤表现为随风化成土作用的进行SP和SSD颗粒逐渐增多,其xfd和非滞后剩磁(ARM)逐渐增大,导致土壤磁化率增大．统计分析证明,土壤磁化率与xfd和ARM呈极显著正相关．土壤的xfd与游离氧化铁含量呈极显著正相关,与DCB处理的磁化率损失量呈极显著指数正相关,认为DCB处理的磁化率损失量与xfd有相同的环境意义．根据DCB处理的磁化率损失量分析可将xfd 10％作为土壤中存在相当数量SP颗粒的指标．对xfd在环境变迁、古气候演变、土壤性态、土壤侵蚀和环境污染方面的应用及其潜力进行了探讨。     

磁性参数的环境指示意义

介绍了岩石磁学研究中常用的能够指示环境变迁和气候变化的几种磁性参数及其组合。研究表明：磁化率是气候变化的代用指标之一，其值的高低反映气候的暖冷和沉积颗粒的细粗，用参数HSIRM，Bcr,HSIRM/k可以识别磁性矿物类型，较多磁铁矿的存在指示暖湿的沉积环境，反映沉积物颗粒细；而较多赤铁矿的存在则指示干冷的沉积环境，反映沉积物颗粒粗。HARM，Ber,HSIRM/k，S比(HSIRM-100mT/HSIRM)在环境监测中有重要的意义。     

新疆博乐黄土岩石磁学特征及环境意义

对位于亚洲内陆干旱区的新疆博乐黄土进行了系统的岩石磁学和粒度测量.结果表明:博乐黄土中的主要载磁矿物为磁铁矿、磁赤铁矿,含有少量针铁矿和赤铁矿.亚铁磁性矿物主要以多畴、假单畴颗粒为主,反映了这一地区极弱的成土作用.磁化率与粒度呈现良好正相关关系,与黄土高原的情况相反,说明干旱地区的黄土磁学性质主要受原生磁性矿物控制,磁化率可作为搬运风力和源区变化的代用指标.黄土磁化率在不同地区具有不同的环境意义,在将之作为古气候代用指标时需要非常谨慎.     

西菲律宾海沉积物的岩石磁学性质及其古环境意义

对位于西菲律宾海黑潮源区的Ph05重力柱样沉积物进行了详细的岩石磁学测量,包括磁化率、非磁滞剩磁、等温剩磁,以及典型样品的磁化强度随温度变化特征和磁滞参数等.结果表明主要载磁矿物为低矫顽力的磁铁矿,含有少量高矫顽力磁性矿物.磁性矿物的含量变化不大,磁性颗粒以准单畴为主.磁性矿物主要为碎屑成因而非生物成因,磁性矿物的粒度敏感地记录了近250 ka来的气候变化并表现出冰期-间冰期旋回,即在冰期时磁性矿物的粒度变粗,而在间冰期磁性矿物的粒度变细.XARM/X参数与氧同位素曲线及温跃层深度等的变化具有对应性,这种对应性表明磁性矿物粒度参数可以反映上部水体的变化,从而为反演黑潮演化提供了新的手段.     

Rock-magnetic investigation of Siberia loess and its implication

Multiple-rock magnetic investigations conducted on the loess-paleosol sequences at Kurtak in Southwestern Siberia reveal that the mass-normalized low-field magnetic susceptibility profiles reflect changes in lithology between relatively unweathered primary loess of glacial periods and the interglacial paleosols. Maxima in susceptibility values correspond with the least-weathered loess horizons, and minima with the humic horizons of soils. Frequency-dependent susceptibility of the loess-paleosol sequences at Kurtak is very low and practically uniform, indicating the dominance of non-SP ferrimagnetic minerals and negligible pedogenesis. The history of temperature-dependence of susceptibility (TDS) and stepwise acquisition of the isothermal remanent magnetization (SIRM) have confirmed that magnetite is predominant magnetic mineral, and only few maghemite and probably hematite are present within the studied section. Anisotropy of the magnetic susceptibility (AMS) can be used to monitor tilt and disturbance of the sedimentary layers, and also to provide information about the paleo-transport direction for Siberia loess.     

Mineral magnetism of quaternary red earth in Eastern China and Its paleoenvironmental significance

Mineral magnetic measurements have been made on Quaternary Red Earth profiles from Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons have been identified on the basis of magnetic susceptibility, anhysteretic remanent magnetization, saturation isothermal remanent magnetization and magnetization parameters measurements. Magnetic measurements revealed that there were great variations in ferrimagnetic mineral concentration, mineralogy assemblages and grain size in Quaternary Red Earth profiles, suggesting that these variations reflect pedogenic processes fluctuation and environmental changes. The preliminary results indicate that mineral magnetic measurement of Quaternary Red Earth is useful for studying the Quaternary environmental changes recorded in paleosols.     

Paleoclimatic significance of mineral magnetic properties of loess sediments in northeastern Qinghai-Tibetan Plateau

Loess deposit in the northeastern Qinghai-Tibetan Plateau offers an excellent record of climate and environment changes in this region.We have conducted multiparameter mineral magnetic analyses of smaples of loess deposits from the Dongchuan,Lalakou and Panzishan sections.The methods used include magnetic susceptibility,fre-quency-dependent suceptibility,temperature-dependent susceptibility,isothermal remanent magnetization acquisibility.Maghemite and hematite is also present in the loess layers and paleosol horizons.The higher concentration of maghemite in paleosols suggests that the formation of maghemite occurred during in situ pedogenesis,which plays an important role in the enhancement of the magnetic susceptibitily.Similar to that in the Chinese Loess Plateau lying to the east of the Liupan Mountains,magnetic granulometry in the studied loess and paleosols is predominantly pseudo-single-domain(PSD). However,the mean grain-size of the ferrimagnetic minerals in loess is evidently coarser (larger PSD and multiomain-like) than in paleosols (mainly PSD).The magnetic susceptibility of loess and paleosols is positively correlated with the content of ultrafine magnet-ite/maghemite grains,and hence with the intensity of in situ pedogenesis.Therefore,the enhanced magnetic susceptibility in the studied loess-paleosol sequences can be interpreted as being due to climatically induced in situ pedogenesis.     

Magnetism parameters characteristics of drilling deposits in Jianghan Plain and indication for forming of the Yangtze River Three Gorges

The forming time of the Yangtze River Three Gorges is considered as one of keys in the research on the Yangtze River, also is one of the most disputed hotspots. In order to solve the difficult problem, the authors adopt the internationally recognized thoughts and methods of substance tracing from source to sink. The lithologic characteristics, magnetic parameters and magnetic mineral characteristics of deposits in 2 bores are analyzed, which are both sampled from the sedimentary center of the Jianghan Plain. The results are as follows： At about 110 m depth of the core, the contents of coarse materials and stable magnetic mineral both increase significantly. Meanwhile, the magnetic susceptibility of sediment, saturation isothermal remanent magnetization and magnetic susceptibility values of anhysteretic remanent magnetism increase suddenly, which all reflect that at about 110 m depth, the important adjustment has appeared in water system of the Jianghan Plain, and the sedimentary environment and material composition have changed greatly. And it may be the horizon where the Yangtze River Three Gorges formed, its forming time reflected by the paleomagnetic dating is between 1.17 and 1.12Ma B.P.     

Magnetic properties of street dust and topsoil in Beijing and its environmental implications

Environmental magnetic measurements were carried out on the sanrhples of street dust and topsoil, which were collected along the roadway in the urban and suburb of Beijing, including magnetic susceptibility （X）, anhysteretic remanent magnetization （ARM）, isothermal remanent magnetization （IRM） of all samples and temperature-dependence of magnetic susceptibilities and magnetic hysteresis parameters of representative samples. Obvious differences exist between the samples of street dust and those of topsoil. Compared with topsoil samples, the concentration of magnetic particles and high-coercivity components in street dust samples are higher, and the magnetic grains are coarser. Both dust and topsoil samples are dominated by ferrimagnetic minerals, and iron particles are only detected in some dust samples. These results suggest that street dust samples reflect the characteris- tic of particles produced by industrial and traffic activities, and the magnetic property of topsoil sam- ples represents the characteristic of particles from both anthropogenic and natural sources. The distribution of magnetic parameters is influenced by the environment where the samples are collected, like industry, traffic density and other road conditions. Hard isothermal remanent magnetization （HIRM） may be used as an indicator of particles produced by traffic activity. Dust storm samples collected on 17 and 18 April, 2006 have different magnetic properties from street dust and natural particles, like loess and paleosol, which indicate that the dust storm might be mixed with anthropogenic particulates during transport and falling.     

Magnetic response to atmospheric heavy metal pollution recorded by dust-loaded leaves in Shougang industrial area,western Beijing

Fifty-five evergreen tree＇s leaves growing less than one year were collected from Shougang industrial area in western suburb of Beijing, including steel plants and its ambient residential areas, recreational parks and farmlands. Rock magnetic properties and heavy metal contents were studied. The results show that the magnetic properties of leaf samples are predominated by Iow-coercivity magnetite, and both the concentration and grain size of magnetite particles gradually decreased with the distance from the main pollution source increases. Moreover, there is a significant linear relationship between magnetic parameters （the low-field magnetic susceptibility, saturation isothermal remanent magnetization and anhysteretic remanent magnetization） and heavy metals contents （Fe, Pb, V, Cr and Zn） （0.73≤ R≤ 0.88）. Hence, the magnetic parameters of leaves can serve as a proxy for quick detecting of the recent atmospheric metallic pollution.     

Magnetic granulometry of recent sediments from the Huguang Maar and its implication for provenience

To understand the origin and its climatic implications of the Huguang Maar sediments, we conducted laser grain size analysis and rock mangtic measurement for the recent deposits from the Huguang Maar and for the volcanic rocks of the caldera for comparison. The grain size distributions are dominated by clayey silts for both the bulk sediments and magnetic separates. Acquisition of isothermal remanent magnetization (IRM) and thermal demagnetization of IRM suggest (titano) magnetite as the dominating magnetic mineral in the sediments; high coercivity minerals are not detected. Therefore, the ratio of the susceptibility of anhysteretic remanent magnetization (k _ARM) to the weak field magnetic susceptibility (k), k _ARM/k can be used to estimate the grain size of magnetite. The sediments and volcanic rocks yield values of 13.7 and 11.8 for the k _ARM/_k, respectively, corresponding to grain size values of ～0.03 µm and ～0.05 µm. The magnetic granulometry of lake sediments is distinctive from one of the Chinese loess, in which published data suggest a value of 6.0 for k _ARM/_k, and grain size of ～0.1 µm, but is akin to the nearby volcanic rocks. Although a Loess Plateau source of the lake sediments cannot be fully ruled out, the catchment is most probably the main source. We explain the slightly finer magnetite grain size in sediments than in the volcanic rocks as being disintegrated of particles during erosion and transportation. We conclude that there is no evidence for aeolian input of the Loess Plateau dusts into the Huguang Maar, and the relationship between magnetic parameters of the lake sediments and winter monsoon intensity is probably more complicated than previously thought.     

Rock magnetic studies on the hominoid-bearing sediments at Zhupeng, Yuanmou Basin, southwestern China and its paleoclimatic significance

It has been proposed that paleoclimatic changes and tectonic events strongly affect hominoid evolution. The Zhupeng section at Yuanmou Basin, southwestern China, with the hominoid-bearing fluvial-lacustrine sediments, is an ideal natural laboratory to test this hypothesis. This study provided an integrated magnetic study, including low-frequency susceptibility, the anisotropy of magnetic susceptibility, temperature-dependent susceptibility, hysteresis loops, isothermal remanent magnetization, and anhysteretic remanent magnetization, on samples from the Baozidongqing section at Zhupeng. Results show that the dominant mag- netic carrier is hematite, with minor amount of magnetite. Both the composition and concentration of magnetic miner- als strongly correlate with the lithostratigraphy. At least eight short-term events defined by higher concentrations of magnetite were identified. These short events reflect that the subtropical dry-hot climate is similar to today＇s climate. Basing on the lithostratigraphic and rock magnetic results, we suggest that Yuanmou Basin was in a steady deposition environment from about 11 to 7 Ma, which is characterized by alternating of long-term torrid-humid climate and short-term dry-hot climate. Our study provides invaluable environment information for understanding the climate shift and the relationship between paleoenvironment and hominoid evolution in southwestern China during late Miocene.     

Magnetic records of Core MD77-181 in the Bay of Bengal and their paleoenvironmental implications

Located in the low latitude region of the northeastern Indian Ocean, the Bay of Bengal represents one of the largest marginal seas in the world. The Bengal Fan hosts erosional products mostly from Himalayas and is under the influence of the Indian monsoon system. The Bengal Fan has thus been one of the ideal places for studying the uplift of the Tibet Plateau and the history of the Indian monsoon[1―8]. The intensity of the Indian monsoon is controlled by secular variations in insola- ti…     

原油与油田水的磁化率

用Gouy法测定了原油和油田水的磁化率,证实它们都是抗磁性物质。原油和油田水类型不同,磁化率也不同。在原油中,含蜡油的磁化率小于稠油。含蜡油的磁化率与凝固点有关,凝固点越高,磁化率越小;稠油的磁化率与粘度有关,粘度越高,磁化率越大。在油田水中,地面水的磁化率小于回注污水和油井水的磁化率。测定结果表明,磁处理效果与磁介质的磁化率有关。磁化率绝对值越大,磁处理效果越好。