新疆孔雀河北岸湖相沉积物稀土元素丰度特征及其古气候意义

通过对罗布泊LX02剖面孔沉积物稀土元素丰度、分布模式及稀土总量的分析,结合沉积物中烧矢量和粒度参数的变化特征,探讨了稀土元素纵向变化与气候环境之间的关系。结果表明:罗布泊沉积物中稀土元素丰度值较高,平均值为140.0402μg/g,总体上以较湿润的环境为主导,化学风化作用较强。同时,沉积物中轻重稀土元素比值约为9.5,轻稀土含量明显高于重稀土含量,为明显的右倾斜型,Eu为中度负异常,Ce绝大部分为微弱的负异常的稀土配分模式。稀土元素含量与粒度和烧矢量之间存在较好的相关性,分析表明,沉积物中∑REE高值段指示暖湿气候环境,∑REE低值段代表冷干气候环境。根据稀土元素分布与沉积环境的关系,重建了72.4～51.0ka BP期间罗布泊地区经历了4次较大的冷干-暖湿-冷干-暖湿的气候演化过程,从而得出在干旱半干旱地区的罗布泊沉积物中稀土元素对古气候变化具有良好的指示作用。     

罗布泊风积物与冲洪积物磁性变化特征的对比研究

文中对新疆罗布泊北部21个风积物样品和56个冲洪积物样品进行了磁性特征和粒度的分析,初步探讨了罗布泊风积物与冲洪积物磁性变化的差异性。结果表明:1)风积物与冲洪积样品中对磁化率起主要贡献的是磁铁矿和磁赤铁矿;2)风积物的磁化率与百分比频率磁化率呈负相关,与粗粒(>63μm)组分呈正相关,与细粒(<5μm)组分呈负相关关系,说明风积物磁化率与非成土风积粗粒组分密切相关;3)冲洪积物1.25m～1.90m之间的磁化率和百分比频率磁化率呈正相关关系,和SIRM/χ呈反相关关系,和粒度呈反相关关系,揭示了后期的化学风化可能主导着磁化率的变化。     

塔里木东北缘第四纪地质环境演化研究

罗布泊地区是我国西北干旱区环境研究的热点,在罗布泊干湖周边,保留有丰富的地质环境信息。为此,在罗布泊西北缘,针对区域地层构造分布特征、构造活动事件序列、湖泊沉积物及堆积土层中的环境信息进行分析,定量/半定量地重建了第四纪环境和气候变化,解析了未来可能再度出现的地质环境和气候变化的可能性。研究表明:本区第四纪以来主要有767~531 ka、255~158 ka和43~34 ka 3次较大规模构造活动,影响了罗布泊干湖近代的地形地貌分布特征,也影响湖面变化;研究区所处基岩剥蚀台地,地貌由剥蚀准平原化向平原化演化,通过基岩剥蚀"夷平"雏形时间和周边石质文物估算,剥蚀率为0.09~1.2 mm·ka~(-1)。总体上,该区域的干旱化趋势仍会持续。     

新疆天山天池景区土壤磁学特征及其环境意义

以新疆天山天池景区为研究区,运用环境磁学方法,对景区内81个表土(0~10 cm)样品的磁学参数进行系统测定,分析土壤磁学特征及其环境指示意义。结果表明:(1)天池景区土壤磁性矿物含量适中;以亚铁磁性矿物(磁铁矿)为主导,同时伴有少量不完全反铁磁性矿物;土壤磁性矿物颗粒以稳定单畴(SSD)粗颗粒和超顺磁性(SP)颗粒混合组成,同时含有少量的多畴(MD)粗颗粒。(2)研究区表土磁性增强主要受自然成土过程和旅游活动影响;旅游活动区土壤亚铁磁性矿物含量高于未干扰区,土壤颗粒以较粗的SSD颗粒为主,SP颗粒含量相对少,表明旅游活动对景区土壤产生了一定影响,而未干扰区土壤磁性受自然成土过程影响较大。(3)磁性参数空间分布表明,土壤亚铁磁性矿物含量沿景区交通线、环湖的北部、西北部和西南部呈现相对高值,说明景区土壤主要受到旅游交通和专门服务设施活动的干扰。综合来看,土壤磁学方法能够初步圈定旅游干扰对景区土壤污染的程度及范围,可为天池景区土壤环境污染监测及决策部门进行旅游环境管理提供参考依据。     

大气降尘磁学特征对城市污染源的指示

本文应用环境磁学方法研究了兰州市区大气自然降尘的磁学特征。结果表明:兰州市大气降尘中磁性矿物含量较高,主要含有磁铁矿和磁赤铁矿,并伴有少量赤铁矿,磁性矿物颗粒较粗,为准单畴颗粒;兰州市自然粉尘背景值较高,但市区污染物仍以人为源为主,尤其在冬季采暖期间最为显著,且在春、夏季节,兰州市的污染仍以人为源为主,与通常认为兰州市污染冬季以燃煤为主,春、夏季以粉尘为主的模式有较大差异。     

新疆塔克尔莫乎尔沙漠表层沉积物磁化率特征及环境意义

以新疆塔克尔莫乎尔沙漠发育典型的固定半固定沙丘为研究对象,分析了其磁化率变化特征,结果表明:1)研究区表层沉积物低频质量磁化率(χ_lf)和高频质量磁化率(χ_hf)变化趋势相近,χ_lf值总体上略高于χ_hf值。χ_lf与χ_hf含量最大为抛物线型沙丘,其次为灌丛沙堆,相反,χ_fd最高的为灌丛沙堆,其次是抛物线型沙丘。2)频率磁化率(χ_fd)的变化范围为0.02～2.65%,均值为0.76%,表明研究区表层风沙沉积物磁性矿物以多畴MD为主,含有极少量的SP颗粒。3)研究区水分条件相对较好,气候偏湿,表层沉积物磁性矿物来源具有多源性。     

敦煌雅丹沉积物中重矿物特征及其物源指示意义

重矿物是判断物源的重要标志。文中对甘肃敦煌雅丹砂质沉积物中重矿物的种类、形态和组合特征进行了分析,进而对沉积物的物源进行了探讨。通过研究,共鉴定出21种重矿物,可分为2类组合:一是磁铁矿-角闪石-锆石-磷灰石组合、二是石榴子石-绿帘石-绿泥石-矽线石组合;根据重矿物类型和组合特征推测研究区沉积物的母岩应以岩浆岩及变质岩为主;重矿物指示研究区砂质沉积物属近源快速堆积的产物,物源应来自北山构造隆起区。     

胶莱平原县域表土有机碳空间变异特征研究及自相关分析

土壤有机碳是土地质量的重要指标，其含量多少直接影响土地生产力。胶莱平原是山东半岛重要的粮食产地，对其土壤有机碳空间变异的研究可以为区域农田土壤养分评估以及土地可持续利用管理提供参考。文中以胶莱平原典型县域腹地安丘市为研究区，综合运用变异函数和空间自相关分析方法，从土壤有机碳空间变异性、自相关性等角度揭示土壤有机碳的空间分布特征。结果表明，安丘市土壤有机碳含量均值为7.42g·kg^-1,处于中等水平；变异系数为37.47%,属于中等程度变异。土壤有机碳空间分布整体呈现西低东高的趋势，空间自相关分析显示该区域土壤有机碳空间分布具有聚集性，并非呈现随机分布特点。土壤有机碳在该地理空间上具有正相关性，以高值聚类和低值聚类为主，分别分布在东部冲积平原地带和西南山区。土壤有机碳与环境因子的灰色关联分析表明，土壤质地和人类活动是影响高值聚类区形成的主导因素，较低的NDVI是影响西南山区低值聚类的主导因素。研究结果为胶莱平原土壤资源管理和双碳战略实施提供重要的技术参考。     

河北邯郸HZ-S孔第四纪沉积物粒度特征分析

对河北邯郸HZ-S孔第四纪沉积物样品采用MS-2000型激光粒度分析仪进行测试和系统的粒度分析,研究结果表明:沉积物总体形成于水动力平稳低能的河湖相沉积环境。与典型的古洪水平流沉积物粒度特征进行对比,显示具有古洪水平流沉积特征。物质来源主要是以洪水为介质动力的河流冲积物(或洪积物),沉积物组成总体以粉砂为主,主要由悬移质构成,沉积物分选较好,粒度分布多为单峰型。其次是以地表径流为介质动力的陆源碎屑物质,由于短距离搬运,造成沉积物分选较差,跃移组分较多,粒度分布多为双峰型。纵向上沉积物平均粒径与<32μm细颗粒级百分含量呈同步正相变化,其大小主要受<4μm的粘土含量变化所控制。     

甘肃北山沙枣园地区土壤表层盐分特征研究

以我国高放废物处置库预选场址之一的甘肃北山沙枣园地区为地质背景,旨在探索极旱荒漠地区土壤盐分特征研究方法与理论,从而为高放废物处置库选址和场址性能评价服务.文中采用地质统计学和聚类分析方法研究了沙枣园预选场址土壤表层盐分特征.结果表明:研究区土壤阴离子聚积以SO42-、Cl-为主,阳离子聚积以K++Na+、Ca2+为主;土壤盐分总量空间分布特征为岩体周边第四纪沉积物中大于岩体内沟谷沉积物中;区内土壤盐分的变异主要取决于Ca2+、Cl-、SO42-这3种盐分离子;土壤盐分积累主要以CaSO4、NaCl、KCl形式存在;该区土壤盐分空间相关性强,各盐分离子空间自相关变化尺度相似,变程大都集中在4500～7000m.     

A study on historical location and evolution of Lop Nor in China with maps and DEM

Lop Sea, located at the east end of the Tarim Basin, Northwest China, dried up permanently, which is the terminal lake of the Tarim River. Lop Sea was considered as the lake basin of Lop Nor since Quaternary. However, the possibility that Lop Nor was away from the Lop Sea in historical time is crucial to be discussed to interpret the proxy records in sediment profiles. To obtain a general view of the evolution of Lop Nor and Lop Sea in a historical period, several approaches were adopted in this paper. First, the Qianlong Thirteen-Row Atlas, an ancient imperial atlas of the Qing Dynasty, which was completed around 1760, indicated that the Tarim River formed a relatively large lake at its modern upstream region. Second, a Digital Elevation Model(DEM) with a 10-m spatial resolution and a relative precision of 0.42 m was derived from TanDEM-X/Terra SAR-X satellite image pairs using the interferometry method, which was verified using ICESat-GLAS laser footprints and a local DEM acquired by a drone. Finally, based on the spatial analysis of historical documents, expedition reports, sediment profiles and archaeological evidence, it can be deduced that the lacustrine deposition was discontinued in the Lop Sea. Six episodes in the evolutionary history of the drainage system in eastern Tarim Basin were summarized. The proved depositional condition variations could be used for future interpretation of proxy records in sediment. The high-accurate DEM provided a reference for the location of further fieldwork in the Lop Sea. The method proposed in this paper may be efficient for the research of inland lakes or rivers in global arid regions.     

罗布泊红柳沙包记录的极端气候事件及影响因素

罗布泊地区的红柳沙包,具有清晰的沉积纹层,与树木年轮一样,具有准确的计年和储存环境信息的功能。通过对罗布泊典型红柳沙包中沙层沉积厚度、落叶阳离子含量、C/N、δ¹³C、δD、δ¹⁸O等序列中记录的环境代用指标极端值与极端气候事件的相关性分析发现,环境代用指标极端值与极端气候事件之间有很好的对应关系。依此分析了近160 a罗布泊地区极端气候事件的发生规律和影响因素。     

Fluvial sediments in the Alagxa Plateau as a dust source: iron mineralogical and geochemical evidence

The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRM_(AF100 mT)(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests that the fluvial sediments are the source of a large amount of silty material which could be transported to the CLP. Therefore, we conclude that the fluvial sediment in the Alagxa Plateau is an important source of eolian silt, which is deposited in downwind region, and that this source has been previously underestimated.     

近百年来罗布泊最后干涸时间的评述

罗布泊的干涸是中亚干旱地区环境变化的一个重要事件,现有研究对1921年覆水以来最后一次干涸发生的时间存在广泛争议。通过相关概念的明确和研究对象时空范围的限定,基于文献对比分析和遥感图像的重新判读,逐一分析了现有研究成果的异同;并分析了1930年代以来湖面的盈亏情况以及补给水源的变化过程。结果表明：罗布泊最后一次覆水于1962年,干涸可能发生在该年冬季,最迟不晚于次年夏季;在极度干旱的气候背景下,20世纪30年代以来的湖水存在剧烈的盈亏变化;而农业耗水规模的扩大和筑坝拦水,直接促成了最后一次干涸的发生。     

Identifying the influence of urbanization on soil organic matter content and p H from soil magnetic characteristics

Soil magnetic characteristics are correlated with soil p H and organic matter content. Analyzing soil magnetic characteristics, organic matter content and p H can indirectly evaluate soil pollution caused by human activities. This study analyzed the soil magnetic characteristics, organic matter content and p H in surface soil samples from different land use types in Shihezi city, a newly and rapidly developing oasis city in Xinjiang of China. The aims of this study were to explore the possible relationships among the soil magnetic parameters and thereby improve the understanding of influence of urbanization on soil properties. Eighty surface soil samples at the depth of 0–10 cm were collected from 29 July to 4 August 2013. The results showed that the magnetic minerals in surface soil were dominated by ferromagnetic minerals. Spatially, the magnetic susceptibility(χLF), anhysteretic remanent magnetization susceptibility(χARM), saturation isothermal remanent magnetization(SIRM) and "soft" isothermal remanent magnetization(SOFT) were found to be most dominant in the new northern urban area B(N-B), followed by built-up areas(U), suburban agricultural land(F), and then the new northern urban area A(N-A). The values of χLF, χARM, SIRM and SOFT were higher in the areas with high intensities of human activities and around the main roads. Meanwhile, the property "hard" isothermal remanent magnetization(HIRM) followed the order of UN-BFN-A. Built-up areas had an average p H value of 7.93, which was much higher than that in the new northern urban areas as well as in suburban agricultural land, due to the increased urban pollutant emissions. The average value of soil organic matter content in the whole study area was 34.69 g/kg, and the values in the new northern urban areas were much higher than those in the suburban agricultural land and built-up areas. For suburban agricultural land, soil organic matter content was significantly negatively correlated with χLF, and had no correlation with other magnetic parameters, since the soil was frequently ploughed. In the new northern urban areas(N-A and N-B), there were significant positive correlations of soil organic matter contents with χARM, SIRM, SOFT and HIRM, because natural grasslands were not frequently turned over. For the built-up areas, soil organic matter contents were significantly positively correlated with χLF, χARM, SIRM and SOFT, but not significantly correlated with frequency-dependent susceptibility(χFD, expressed as a percentage) and HIRM, because the soil was not frequently turned over or influenced by human activities. The results showed that soil magnetic characteristics are related to the soil turnover time.     

Growth and sustainability of Suaeda salsa in the Lop Nur,China

Extremely saline soils are very harsh environments for the growth and survival of most plant species, however, halophytes can grow well. The underlying mechanism of halophyte to resist high saline is not well understood by us. This study was conducted at the potash mine near the Lop Nur, China, where the effects of the halophyte Suaeda salsa L. on the saline-alkaline soils and its growth and sustainability were investigated. Four plots(in which the salt encrustation layers were removed), with different soil treatments were evaluated:(1) undisturbed soil, with no additional treatment(T1);(2) the slag soil zone, in which a 40-cm layer of slag was placed on the undisturbed soil surface(T2);(3) slag+sandy soil, in which a 20-cm layer of slag was placed in the lower layer and 20 cm of sandy soil, taken from an area about 70 km away from Lop Nur potash mine, where Tamarix species were growing, was placed in the upper layer(T3); and(4) a 40-cm sandy soil layer taken from the area where Tamarix species were growing was placed on undisturbed soil(T4). Soil nutrient contents increased in the four treatments, but salt content only decreased in the T1 treatment. Salt content in the T4 treatment increased over the two-year period, which may be partly attributed to salt deposition from wind-blown dust within the mine and salt accumulation within the surface soil(0–20 cm) in response to high evaporative demands. The S. salsa plants exhibited greater improvements in growth under the T4 treatment than under the T1, T2, and T3 treatments, which demonstrated that low levels of salinity are beneficial for the growth of this species. The T1 treatment was sustainable because of its low cost and superior soil improvement characteristics. Therefore, S. salsa plants not only reduced soil salinity and increased soil nutrient levels, but also ameliorated the plant growth environment, which would be beneficial for both the ecological restoration of the Lop Nur area and similar areas throughout the world.     

Magnetic property of loess strata recorded by Kansu profile in Tianshan Mountains

Kansu (KS) profile is located in the east of Yili basin, western Xinjiang, where typical loess sediments are distributed. The magnetic parameters (such as IRM, SIRM SOFT, and M) and grain size in the KS profile were analyzed in the study. The results showed that the magnetic property of KS loess is dominated by ferrimagnetic minerals, such as magnetite and maghemite. Antiferromagnetic and superparamagnetic minerals also exist in the profile, but had less impact on magnetic susceptibility. Compared with the typical loess sediments of the central Loess Plateau in China, the strata of Kansu profile contained more magnetic minerals and hard magnetic minerals. The analysis of grain size for magnetic minerals indicated that the properties of loess and paleosol were respectively dominated by PSD/MD and coarse SSD magnetite. The research found that the contents of magnetic minerals in loess and paleosol sequences in Kansu profile were similar, but the proportion of fine grained magnetite and soft magnetic minerals were varying, which implies a positive relationship between the value of magnetic susceptibility and intensity of pedogenesis.     

Relationship between thermal anomalies in Tibetan Plateau and summer dust storm frequency over Tarim Basin,China

The dust storm is the most important and frequent meteorological disaster over Tarim Basin,which causes huge damages on local social economics.How to predict the springtime and summertime dust storm occurrence has become a hot issue for meteorologists.This paper employed the data of dust storm frequency and 10-m wind velocity at 35 stations over Tarim Basin and the reanalysis data from the National Center for Environmental Prediction and the National Center for Atmospheric Research(NCEP/NCAR) during 1961-2007 to study the relationship between dust storm frequency(DSF) in summer over Tarim Basin and the thermal anomalies in Tibetan Plateau in May by using the statistical methods,such as Empirical Orthogonal Function(EOF),correlation and binomial moving average.The results show when negative anomalies in Tibetan Plateau and positive anomalies in its southern region are present along 30°N(the second mode of surface temperature anomalies by EOF decomposition) in May,the time coefficient(PC2) plays an important role in summer DSF variation and has a close relation with the summer DSF at both inter-annual and decadal time scales.When negative anomalies in Tibetan Plateau and positive anomalies are present in its southern region(PC2 in positive phase),there is an anomalous anticyclone in North China,which weakens the northwest wind and is not beneficial for cold air moving from high latitude to the Tarim Basin,and the circulation pattern is hard to result in dust storm weather.Furthermore,the sea level pressure(SLP) increased over Tarim Basin and the direction of SLP gradient reversed,which resulted in the 10-m wind velocity slowing down,so the DSF decreased.From above all,it can be conclude that the thermal anomalies in Tibetan Plateau in May has important effects on the summertime dust storm frequency over Tarim Basin and the PC2 can be used as a prediction factor for the summertime dust storm occurrence.     

新疆沙漠空间分布格局与类型结构

在对新疆沙漠区域环境特点分析的基础上,基于新疆1[JP18]∶[JP]1 000 000数字地貌图和TM影像数据及Google Earth等资料,利用GIS技术,编制了新疆沙漠分片图与沙漠类型分布图,对新疆沙漠空间分布与类型结构进行了分析。结果表明：① 新疆共有577块沙漠,可以划分为35片区。按照区域可分为塔里木盆地沙漠区、准噶尔盆地沙漠区、阿尔泰山沙漠区、准噶尔西部山沙漠区、昆仑山-阿尔金山沙漠区、天山沙漠区6个区;② 新疆沙漠面积达428 977.14 km²,占新疆总面积的26.12%;沙漠分布广泛,平原、丘陵和山地均有分布,但各区域的沙漠面积相差悬殊;沙漠在空间上呈聚集分布,主要分布在塔里木盆地和准噶尔盆地;沙漠景观破碎化程度具有很大空间差异性,在塔里木盆地和准噶尔盆地中面积较大沙漠的破碎化程度低,而在山地与两大盆地的过渡地带面积较小的沙漠破碎化程度较高。③ 新疆沙漠具有独特的地貌类型、稳定性和类型丰富度等类型结构,地貌类型以沙丘和沙垄为主,沙漠植被覆盖度差,以流动性沙丘和流动性沙垄为主,多数沙漠的类型丰富度贫乏,只有少数沙漠类型数量可以达到中等乃至极丰富。