共查询到20条相似文献，搜索用时 125 毫秒
1.
《矿物岩石》2016,(4)
以煤油介质,利用筛分法对青海西台吉乃尔盐湖盐田蒸发光卤石原矿进行粒度分级,通过X射线衍射方法确定各粒级颗粒矿物组成,运用扫描电镜表征细粒盐类晶体微观形貌特征,结合化学分析结果,揭示原矿粒度分布规律和矿物组成变化特征。结果表明:光卤石原矿粒度分布属于中细较粗粒级,大于1mm粒径的矿物比例不超过50%,而小于0.5mm粒径的矿物不足10%;各粒径矿物组分有变化,光卤石主要集中在较细粒级范围(0~1mm),泻利盐在各个粒级范围内均有出现,粒度越大,泻利盐的含量越大,氯化钠主要富集在中粒级范围(1mm~3mm),水氯镁石在各粒径均有分布,无明显变化。小于0.45mm粒径矿物SEM和能谱分析结果表明:光卤石表面圆润,存在脱水的可能性;石盐和泻利盐、光卤石和泻利盐团聚在一起,形成胶结状聚集体。光卤石原矿的粒度分布特征和矿物微结构特征影响分解转化过程体系的水平衡和溶液相平衡,对氯化钾收率产生影响。 相似文献
2.
3.
长春市城区近地表灰尘粒度特征及其环境意义 总被引：1，自引：0，他引：1
为剖析长春市城区近地表灰尘粒度特征,分别沿南北和东西轴线采集了34件城市近地表灰尘样品,采用激光粒度仪对样品进行了粒度测试分析。结果表明：长春市近地表灰尘颗粒物平均中值粒径和算术平均粒径分别为21.58 μm和24.24 μm,分选极差;以粗粉粒（10.00～80.00 μm）为主,平均约占71.28%,黏粒组（<5.00 μm）和细粉粒组（5.00～10.00 μm）分别约占14.75%和13.05%。频率曲线呈正偏双峰型分布,峰态中等偏窄,与现代尘暴和城市街道灰尘分布特征相一致,反映出其起源的多元性和相对稳定性,表明近地表灰尘沉积仍是风积作用的继续。近地表灰尘颗粒物粒径均小于100.00 μm,极易在外动力条件下再次扬起并悬浮搬运,PM10和PM2.5所占比例分别为27.76%和7.32%,其生态环境效应不应被忽视。粒径分布无显著空间变化,但城市中心区域粒径变化范围小,这可能说明城市边缘区域较中心区域近地表灰尘的起源更具多源性和复杂性。 相似文献
4.
成都市近地表大气尘的矿物学特征及其环境指示意义 总被引：9，自引：0，他引：9
通过对成都市近地表大气尘X射线衍射、电镜扫描分析等研究显示:其主要由石英、长石、伊利石、绿泥石、方解石、石膏等矿物组成;就其形状看有致密的不规则粒状、片状单矿物、不规则粒状聚合体、浑圆形球状飘珠、聚合体放大观察可见片状的粘土矿物和细小的粒状单矿物,偶见藻类;矿物形貌特征及矿物组成空间分布特征的研究显示:球形状飘珠及伊利石、绿泥石、石膏的空间分布特征与工业布局和表层土壤的pH值密切相关,成都市近地表大气尘主要为地表扬尘和工业烟尘的混合物;与土壤的矿物组成比较可见,近地表大气尘重金属污染除土壤贡献外,还有其他污染贡献;石膏在本次研究中平均含量高达8.2%,推测可能成为成都市往年燃煤量大而无明显酸雨现象的原因之一。 相似文献
5.
江苏典型地区河流沉积物重金属元素分布特征及其污染来源 总被引：3，自引：0，他引：3
通过对河流沉积物等地表沉积物中重金属元素分布等环境地球化学调查数据的统计分析,总结了江苏典型地区河流沉积物中重金属元素的分布特点与规律:江苏局部地区河流沉积物中,Cd、Pb、Zn、Cr、Cu、Ni、Hg等相对富集趋势明显,Cd最大富集倍数 100;不同河流沉积物的重金属元素分布存在差异,与其污染来源密切相关;工业排放是导致河流重金属污染的主要原因,使用含Cd的颜料作为调色剂导致部分河流出现严重Cd污染;与土壤等其他地表沉积物相比,河流沉积物中重金属元素的分布更不均衡。查明河流沉积物的重金属元素分布可为相关农产品安全性预测、确定重金属污染来源、追踪涉重产业的发展历程、防治局部耕地重金属污染等提供科学依据。 相似文献
6.
7.
地表松散沉积物中不同粒级的颗粒蕴含着不同的信息,这种差异与其物质来源、搬运和沉积过程中的分选作用以及沉积后的风化作用等有关。因此,可根据沉积物中不同粒级颗粒地球化学特征与矿物组成的差异,进行沉积物物源追踪或沉积环境重建。选择青藏高原在气候和地貌方面具有典型意义的柴达木盆地、错那湖、雅鲁藏布江流域作为研究区,分别采集了这几个地区的沙丘沙、黄土、湖积物、冲积物、洪积物、残坡积物等地表松散沉积物样品,用干筛法将沉积物样品分为两个部分,粗颗粒部分粒径范围为≥75~500 μm,细颗粒部分粒径<75 μm。对上述粗、细颗粒分别进行稀土与微量元素、Sr-Nd同位素、轻矿物组成的实验室分析测试,并对沉积物中粗、细颗粒的测试结果采用古典多维尺度方法进行相似性分析。结果表明：青藏高原松散沉积物中粗、细颗粒在轻矿物组成、微量和稀土元素含量、稀土特征、元素参数等方面存在差异;细颗粒部分蕴含了更多的环境信息,富含容易受化学风化影响的黏土矿物以及硬度较小、容易被磨蚀的方解石等矿物。在物源示踪中不同气候区的沉积物细颗粒不宜进行直接比较,应根据样品的粒度分布情况优先选择合适的粗颗粒组分进行物源示踪。 相似文献
8.
《地学前缘》2017,(3):341-349
对取自西菲律宾海西部的GX149柱状样沉积物进行详细的环境磁学研究,揭示其蕴含的环境意义和物源信息。岩石磁学结果表明,GX149柱状样沉积物中携磁矿物以低矫顽力磁铁矿为主;反映磁性颗粒粒径的King图与Day图显示沉积物中磁性矿物以准单畴(PSD)为主。剖面上磁学参数变化明显,以磁性矿物粒径参数(χARM/χ)作为替代指标反演古气候变化结果显示:冷期沉积物中磁性矿物含量相对更高,粒径更粗,高矫顽力矿物含量增加;而暖期沉积物中磁性矿物含量相对较低,粒径更细,高矫顽力矿物含量降低。干燥、寒冷、风大的冷期气候下,东亚季风携带的粉尘输入增加导致沉积物中高矫顽力矿物含量增多;而温暖湿润的暖期,沉积物中风成粉尘输入减少,高矫顽力矿物含量降低。GX149柱状样沉积物与西菲律宾海其他区域以及南海沉积物相似的磁学特征,相同的冰期-间冰期旋回趋势说明沉积物磁学特征对气候变化的响应在东亚地区具有共性。 相似文献
9.
西北地区干枯湖床沉积粒度组成与东亚沙尘天气 总被引：23，自引：4，他引：19
调查了准噶尔盆地玛纳斯湖、阿拉善高原居延泽及民勤盆地猪野泽等北方众多的现代干枯湖泊,重点分析了干枯湖床沉积物粒度组成。干枯的玛纳斯湖、古居延泽以及民勤盆地古猪野泽沉积物粒度分析结果表明,干枯湖床的地表湖相沉积物粒径小于10μm的颗粒占60%以上,干涸湖床上沙质草原地表也含有大量小于10μm的粘土颗粒,含量接近50%;而弃荒土地地表细颗粒物质散失迅速,民勤盆地弃荒土地地表粘土含量仅存不到13.9%。中国西北地区活动沙丘粒度组成小于63μm粒径的颗粒很少,小于10μm的颗粒微乎其微。因此西北沙漠地区活动沙丘沙对华北或华东地区影响相对较小。认为沙尘暴、扬沙或浮尘天气虽然多发生于中国西部沙漠、阿拉善高原沙区、河西走廊北部沙区以及蒙古东部、中部地区,但由于粗颗粒沙扬起高度与搬运距离有限,真正影响整个华北、华东地区的沙尘物质是小于63μm的粉砂级别的颗粒,特别是小于10μm的粉尘。认为影响东亚地区的粉尘天气物源不仅是中国西部的内陆沙漠、沙地,更重要的是干枯的湖泊、弃耕的荒地与裸露的沙砾草场。 相似文献
10.
11.
兰州市宛川河中段表层沉积物中重金属元素迁移富集特征 总被引：3，自引：0，他引：3
通过对兰州市宛川河中段双店子河段表层沉积物元素分析,结合有机质含量和粒度测试,运用聚类分析和相关分析的方法,研究了重金属元素在河流表层沉积环境中的分布及迁移富集等地球化学行为与特征。结果表明Zn元素在研究河段有轻度污染;相关分析表明重金属元素含量与沉积物粒度之间无显著相关性,重金属元素主要是在固-液平衡体系中、通过多相化学反应形成沉淀。污染源分析表明,造纸污水的排放是造成研究区域中上游河段有机质含量较高的主要原因,大分子有机物质的存在不仅改变了此段河流沉积物粒度的变化,且有机质对重金属元素的富集有一定减缓作用。 相似文献
12.
【研究目的】白洋淀为雄安新区核心生态功能区,为支撑白洋淀湿地生态修复与保护,系统开展了全淀区表层沉积物环境质量调查。【研究方法】在白洋淀湿地采集表层沉积物样品484组,查明了白洋淀表层沉积物重金属地球化学特征,并采用地累积指数法、潜在生态风险指数法等多种方法开展了重金属生态风险评价。【研究结果】白洋淀表层沉积物重金属含量普遍偏高于河北省表层土壤重金属含量背景值,府河入淀口及白沟引河入淀口为重金属元素主要富集区,入淀河流输入为白洋淀重金属主要来源;环境地球化学综合评价结果为清洁无污染等级分布面积144.54 km2,占表层沉积物分布总面积的96.68%;各重金属污染程度由重到轻排序为Cd＞Cu＞Hg＞Pb＞Zn＞Ni＞Cr＞As,Cd元素污染程度等级以中度和偏中度为主,Cu元素以轻度和清洁为主,其他元素以清洁无污染为主;重金属潜在生态风险以轻度和中度为主,河流入淀口所在淀区重金属潜在生态风险高于其他淀区,潜在生态风险由高到低排序为南刘庄＞烧车淀＞小白洋淀＞王家寨＞藻苲淀＞捞王淀＞池鱼淀＞泛鱼淀。【结论】白洋淀表层沉积物环境质量总体较好,南刘庄等局部淀区存在重金属污染潜在生态风险,以Cd元素污染最为突出。创新点：采用地累积指数法、潜在生态风险指数法等多种方法,系统评价白洋淀湿地表层沉积物重金属污染程度和生态风险;重金属地球化学特征分析与主成分分析法相结合,揭示表层沉积物重金属污染主要来源为河流输入。 相似文献
13.
Heavy metal contamination and their distribution in different size fractions of the surficial sediment of Haihe River, China 总被引：3，自引：0，他引：3
Heavy metal contamination and their distribution in different size fractions of the surficial sediment in Haihe River, China have been investigated. These results reveal that the heavy metal contamination of Haihe River is closely related to the contaminating sources along the river and has the order: Cd > Cu > Pb > Cr. The contents of these heavy metals in the sediment of Haihe River are at least two times higher than their background values and the highest contaminating metal, Cd, is 15.5 times higher than its background value and determined in the urban area of Tianjin city. The surficial sediments of Haihe River, with 70% particles smaller than 20 μm, belong to sandy clay containing about 28% clay and 42% silt. Electron micrographs and x-ray analysis show that the concentrations of heavy metals depend on the particle size of sediments. The highest concentrations for most metals exist in fine-grained sediments, which are mainly composed of silicates, oxides, and hydroxides of Si, Fe, and Al. In contrast, lower levels of heavy metals are usually found in the coarse sandy sediments, which are composed of quartz, feldspar, and other rocky substances. Based on the results in the present study of the surficial sediments of Haihe River, the contents of Cr, Cu, Pd, and Cd in finer sediments are 2.4, 3.9, 2.8, and 3.6 times higher than those in coarse sandy sediments, respectively. Obviously, because of rapid industrial development in this area during the last few decades, the surficial sediments of Haihe River, especially those finer fractions, have been seriously contaminated by heavy metals. 相似文献
14.
Spatial distribution of heavy metals in surficial sediments from Guanabara Bay: Rio de Janeiro, Brazil 总被引：1，自引：0，他引：1
José Antônio Baptista Neto Franz Xaver Gingele Thomas Leipe Isa Brehme 《Environmental Geology》2006,49(7):1051-1063
Ninety-two surface sediment samples were collected in Guanabara Bay, one of the most prominent urban bays in SE Brazil, to
investigate the spatial distribution of anthropogenic pollutants. The concentrations of heavy metals, organic carbon and particle
size were examined in all samples. Large spatial variations of heavy metals and particle size were observed. The highest concentrations
of heavy metals were found in the muddy sediments from the north western region of the bay near the main outlets of the most
polluted rivers, municipal waste drainage systems and one of the major oil refineries. Another anomalous concentration of
metals was found adjacent to Rio de Janeiro Harbour. The heavy metal concentrations decrease to the northeast, due to intact
rivers and the mangrove systems in this area, and to the south where the sand fraction and open-marine processes dominate.
The geochemical normalization of metal data to Li or Al has also demonstrated that the anthropogenic input of heavy metals
have altered the natural sediment heavy metal distribution. 相似文献
15.
Spatial variations in grain size distribution and selected metal contents in the Xiamen Bay,China 总被引：1，自引：0，他引：1
Guihai Li Zhimin Cao Dongzhao Lan Jiang Xu Shanshan Wang Weihan Yin 《Environmental Geology》2007,52(8):1559-1567
The present work attempts to describe the spatial distribution of heavy metals in the surficial sediments of the Xiamen Bay
influencing by the characters of the sediments. In this paper, the distribution of trace metals, as well as the main properties
(i.e. grain size, TOC, AVS) based on surface sediments collected at 40 stations across the Xiamen Bay was done. The relation
of the sediment properties to heavy metal concentrations was evaluated with Pearson’s correlation analysis. According to the
grain size distribution, cluster analysis is used to classify the sampling stations into groups regarding the depositional
environment. Basing on the data, the hydrodynamic feature and the contamination of surface sediment by selected metals were
discussed. The results show that the distribution of various types of sediments and the variations of their concentrations
of heavy metals are controlled largely by the hydrodynamic conditions. As for the surface sediments, Xiamen West Harbour shows
a serious situation with Arsenic, Pb and Zn. 相似文献
16.
Sediment particle size distribution and its environmental significance in Lake Erhai, Yunnan Province 总被引：1，自引：0，他引：1
A closed or semi-closed plateau lake, whose sediment records can provide us with plenty of fine and high resolution information,
is a sensitive indicator of climatic and environmental changes. During the reconstruction of various short-time-scale climatic
and environmental changes, the geochemical records in plateau-lake sediments are superior to other natural files. Based on
fine dissection of the vertical profile of sediment particle sizes, this paper reveals the quasi-periodical changes of sediment
particle sizes, which indicates the quasi-periodical fluctuations of the regional climate. A synthetic analysis of multiple
indexes shows that sediment particle size is a more sensitive and more effective index of climatic and environmental changes
than other geochemical indexes. High content of >20μm sediment particles and low content of 2–10μm sediment particles indicate a warm-dry climate and conversely a cold-humid climate, and their ratio can be used as an effective
index of climatic changes. The basic climate succession in the region of Lake Erhai is characterized as being alternatively
warm-dry and cold-humid and it has been developing into a warm-dry climate as a whole. There exist at least 2 time-scale quasi-periodical
fluctuations of the regional climate in Lake Erhai. At present, the region of Lake Erhai is at the end of the warm-dry period
and at the beginning of a cold-humid period, so the temperature will go down and the water level will rise.
This project was supported by the National Natural Science Foundation of China (Nos. 49894170, 49773207). 相似文献
17.
沉积物中的重金属元素经自然作用下可以活动态进行迁移,具有潜在生物可利用性及潜在的区域生态风险。利用近红外光谱(NIRS)技术开展不同基体类型样品响应机理研究,可为评估重金属活动态提供无损、快速的分析方法,为生态风险研究提供依据。天津七里海泻湖湿地沉积物具有低有机质-高黏土含量的特征,本文基于近红外光谱分析技术,建立了沉积物中Co、Ni、Cu、Zn、Cd、Pb重金属活动态组分含量近红外光谱-偏最小二乘回归预测模型。实验结果表明:样品在7290～6390cm~(-1)和4683～4000cm~(-1)波段存在的双羟基O—H伸缩振动、AlAl—OH及Al(Mg)—OH弯曲振动特征吸收,间接指示了重金属元素活动态含量。光谱预测结果显示,近百年来七里海沉积物中Co、Ni、Cu、Zn、Cd、Pb活动态组分的变化特征对应了当地1934—1948年、1956—1963年、1976年至今三次较明显的升温过程,也对应了1980年七里海水库建设等大型人为扰动。本研究样品中Co、Ni、Cu、Zn、Cd、Pb总量及活动态均低于国家标准中规定的生态风险阈值,七里海内村镇及周边农田来自湿地释放的重金属生态风险极低。 相似文献
18.
The influence of hydrodynamics on the chemical composition of sediments is based on the uneven distribution of element abundances in different size fractions. In this study, 72 size‐fractional sediments from the Huanghe (Yellow River) and Changjiang (Yangtze River) riverbeds were measured with XRD, SEM, ICP‐AES and ICP‐MS. The analysis results show that the mineral and chemical characteristics change with grain size in the Huanghe and Changjiang sediments. According to the principal components analysis, three independent geochemical factors were found. The first factor elements, Zr, Hf, Th, U, Y, La and TiO2 are influenced by the existence of heavy minerals. The second factor elements, Al2O3, alkalis, alkaline earth (excluding Ca and Sr) and most of the transitional metals are dominated by clay minerals. The third factor group includes Ca and Sr, which were controlled by calcium‐bearing mineral contents and chemical weathering intensities. The various grain size distributions greatly affect the mineralogical and chemical compositions of bulk sediments. Compared to other size fractions, the 5–6PHI size fractions of the Huanghe and Changjiang sediments have special mineralogical and chemical compositions, and intermediate volume percentages. Weight or volume percentage of each size fraction may be more suitable than mean grain‐size of the bulk sediment to elucidate the grain size effects. Chemical Index of Alteration (CIA) values increase steeply with decreasing grain size, while Weathering Index of Parker (WIP) values are relatively stable. Because of the big influence of the abundance of clay minerals on CIA values, it is questionable to use CIA as a proxy of weathering intensity. Considering the clay mineral effects, stability in values and heterogeneous material properties, WIP has the potential to indicate the chemical weathering intensity of sediments. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
19.
To assess the risk of release and percentage of heavy metals in river sediment, nine stations were set up to sample surface sediments from three important rivers situated southwest of the Caspian Sea (the Shafaroud, Karaganroud, and Choubar Rivers). Chemical analyses were conducted on sediment with particle sizes of >38, 63–38, 63–125, 125–250, 250–500 and 500–1000 µm using metal fractionation to determine the degree of risk release and the heavy metal pollution. Common risk indices were used including the cumulative indices of pollution intensity assessment and risk release standards (the modified pollution degree and ecological risk). Generally, when sediment sizes are decreased, the concentration of heavy metals is both larger and greater than the mean concentration of global sediments and earth crust. However, in this research, the concentration of all the metals did not necessarily increase with a decrease in the size of particles. In fact, concentration of cobalt, vanadium, cadmium, and chromium was greater in sediment particle sizes over 63 μm. The results of chemical fractionation analyses indicated that the release risk of metals has two initial phases for: (1) exchangeable bond (F1) and (2) carbonated bond (F2). When compared with other metals, nickel had the greatest tendency to bond within the loose exchangeable phase (F1) across all the stations. Furthermore, with changes in the size of particles, the percentage of heavy metal changes across different bond phases, but will be the greatest in the loose exchangeable phase (F1). This was observed with cobalt, nickel, and chromium at particle sizes larger than 63 μm. The results of ecological risk and modified pollution degree indices indicated that the highest level of pollution was related to sediments with sizes between 63 and 250 μm. Eventually, in order to assess the risk extent of metals present in sediment, a cumulative index referred to as the modified risk assessment code was utilized. It suggested that the greatest risk of toxicity in some stations has been related to particles larger than 63 μm. 相似文献
20.
It is generally agreed that particle size distributions of sediments tend ideally to approximate the form of the lognormal probability law, but there is no single widely accepted explanation of how sedimentary processes generate the form of this law. Conceptually, and in its simplest form, sediment genesis involves the transformation of a parent rock mass into a particulate end product by processes that include size reduction and selection during weathering, transportation, and deposition. The many variables that operate simultaneously during this transformation can be shown to produce a distribution of particle sizes that approaches asymptotically the lognormal form when the effect of the variables is multiplicative. This was first shown by Kolmogorov (1941). Currently available models combine breakage and selection in differing degrees, but are similar in treating the processes as having multiplicative effects on particle sizes. The present paper, based on careful specification of the initial state, the nth breakage rule and the nth selection rule, leads to two stochastic models for particle breakage, and for both models the probability distributions of particle sizes are obtained. No attempt is made to apply these models to real world sedimentary processes, although this topic is touched upon in the closing remarks. 相似文献