新疆和田杜瓦地区晚二叠世孢粉组合

本文论及所研究的新疆塔里木盆地和田地区原来分别属于叶尔羌群(J_(1-2))和二叠—三叠系(杜瓦组上部)两个部分采集的孢粉化石.沉积物中含有多种对地层研究非常重要的生物化石,如介形虫、叶肢介、鱼及孢粉等.根据孢粉组合的研究,这些地层可视为上二叠统,其孢粉组合以裸子植物花粉占主导地位为特征,可与新疆吉木萨尔县大龙口晚二叠世晚期地层梧桐沟组对比,并相当于西欧的镁灰岩统和苏联的鞑靼阶.     

Organic petrology, mineralogy and depositional environment of the Kipra lignite seam, Maritza-West basin, Bulgaria

The aim of the present study is to provide additional information about the properties and depositional environment of the Kipra lignite seam, which was deposited during the regressive stage of development of the Maritza-West basin. Petrographical and mineralogical data, along with ash yields and sulphur contents of 24 samples from a seam profile, have been used to study the vertical variation of the depositional settings during peat accumulation and subsequent coalification.The Kipra lignite is characterized by high ash yields and sulphur contents. It formed in a rheotrophic, low-lying mire with alkaline pH value. Vegetation with low preservation potential dominated within the palaeomire. During peat formation, frequent changes of the water level controlled the depositional environment. During the deposition of units 1 and 2, high water energy caused the transportation of high amounts of inorganic material into the mire, resulting in the formation of weakly gelified mineral-rich lignite. The organic matter from units 3 and 4 is characterized by enhanced gelification, which probably reflects the decreasing energy of the system. Good positive correlation between sulphur contents and the GI values was established in units 4, indicating that the gelification of the tissues was probably mainly controlled by the bacterial activity. In contrast, the gelification of the samples from unit 3 of the Kipra seam was probably governed by the redox conditions. The organic matter deposited under relatively wet conditions, in which the thermal and oxidative destruction of the tissues, was limited.A variety of major, minor and accessory minerals are present in Maritza-West lignite. The mineral composition is dominated mainly by pyrite, gypsum and calcite, and to a lesser extent limonite, quartz, kaolinite, montmorillonite, illite, chlorite and plagioclase. Jarosite, hematite, halloysite, mica, K-feldspar, aragonite, siderite, and dolomite were also determined in very low concentrations. These minerals formed syngenetically and epigenetically. The syngenetic stage is characterized mainly by the formation of pyrite, carbonates, silicates and sulphates, whereas the Fe-oxyhydroxides, partially the carbonates and almost all silicates are of detrital origin. During the epigenetic stage, carbonates, sulphates, clay minerals, pyrite, and Fe-oxyhydroxides were formed. Alteration products like gypsum, jarosite, limonite, chlorite, kaolinite, illite, mica, and calcite were generated due to the transformation of detrital and authigenic minerals.     

滇西北丽江-大理地区第四纪断裂活动的方式、机制及其对环境的影响

滇西北地区早更新世时全面隆起,中更新世发生陆内裂谷作用,云南高原面解体,晚更新世是地堑系发育的全盛时期,全新世这一过程仍在进行。断块的差异隆升运动造成该区自北、西向南、东呈台阶状降低,形成了玉龙山等断块山。断裂活动控制了盆地、河流、湖泊、冰川、温泉及其沉积。青藏高原隆升产生向南偏东的推挤使川西-云南的断裂活动具相同的方式,断陷盆地发育主要受近南北向左行剪切-拉张活动控制。     

新疆巴里坤湖十五万年来古水文演化序列

通过巴里坤湖钻孔岩芯沉积相分析、年代学测定、粒度分析、碳酸盐及其稳定同位素测定、孢粉分析等综合研究,建立了巴里坤湖沉积岩芯剖面十五万年来的时间序列、湖水位变化的古水文演化序列,分辨出十五万年来经历的高湖面阶段和低湖面阶段。低湖面阶段对应于冰期阶段,在冰期时,降水主要积累于山地,进入湖泊的水量较少,湖水位降低;高湖面阶段对应于间冰期的到来,山地冰川融化,湖水位迅速上升,但很快达到新的平衡,水位保持稳定。     

International cooperation in water resources

Advancements in hydrology proceeded slowly until the late 1800's when new ventures created a surge of interest and accomplishment. Progress waned again until the middle 20th century when an International Hydrological Decade was conceived, eventually receiving wide multinational support from governmental agencies and nongovernmental institutions.Organized by UNESCO, the Decade program was launched January 1, 1965. Participation included 107 nations, six United Nations agencies, and more than a dozen international scientific organizations. The initial program emphasized scientific research, and international cooperation; the second half of the Decade, emphasized technical assistance and technology transfer, largerly through education, training and demonstration.The success of the Decade led to the establishment of the International Hydrological Program, again under the aegis of UNESCO, to continue the work of the Decade indefinitely. The five major program activities, now involving about 90 countries and several international organizations, include: the scientific program, the promotion of education and training, the enhancement of information exchange, support of technical assistance, and the enlargement of regional cooperation.A significant amount of activity related to hydrological data networks and forecasting is carried on in an Operational Hydrology Programme by the WMO, chiefly through its Commission for Hydrology.Other international governmental organizations with a strong interest in water include the UN, the UN Development Programme, the FAO, the WHO, the International Atomic Energy Agency, the UN Environment Programme, the International Standardization Organization, and developmental institutions such as the World Bank.The specialized interests of researchers outside of the governmental structure, are met through association in various scientific and technical organizations which are world wide in scope and membership.Notwithstanding a sometimes bewildering variety of organizations, there certainly exists, for any nation, group, or individual, a demonstrated mechanism for almost any conceivable form of international cooperation in hydrology and water resources.Dr. Heindl, L.A., formerly US Geological Survey, died on October 18, 1978 (see In Memoriam at the end of the paper) before he could finish the final version. His colleagues, James R. Jones, Robert M. Beall and Ennio V. Giusti, Office of International Hydrology, US Geological Survey, Reston, VA. 22092, USA, kindly prepared the paper for publication and wrote In Memoriam. Approved for publication by the Director, US Geological Survey.     

新疆西天山异剥钙榴岩地球化学特征及其对俯冲带流体的指示意义

新疆西天山长阿吾子异剥钙榴岩是目前首例发现的在俯冲带形成的原岩为榴辉岩的异剥钙榴岩,与其作用的流体为俯冲带流体。该异剥钙榴岩与大洋底变质作用形成的异剥钙榴岩相比,岩石学特征非常相似,但是元素迁移方面存在一定的差别。为了推断流体成分,我们使用了三种方法。一、测试了异剥钙榴岩化前后主要矿物相石榴石和辉石化学成分。二、在ACF图上,可以看出全岩成分从F端元向C端元演化,代表Fe减少,Ca增加的趋势,而且完全异剥钙榴岩成分落在了前人所做的异剥钙榴岩成分区间内。三、假设Al为不迁移元素,根据Grant的计算方法,做出主量元素、微量元素和REE的等浓度图。综合以上分析结果推断,俯冲带中流体的成分是复杂和变化的:部分异剥钙榴岩化阶段流体富集Ca、Si、Ti、Mn、Nb、Ta、Zr、Hf,贫乏Fe、Mg、Na、K、REE、Tb、Y,氧逸度升高,流体属于不饱和状态,因此导致不平衡结构发育;完全异剥钙榴岩阶段,流体富集Ca、Mg、LREE、Ni、Cr,贫乏Fe、Ti、Rb、Ba、MREE、HREE等元素,此时流体作用强烈,富水流体相的强烈淋滤作用,使得大部分元素发生了迁移。     

藏北阿木岗群、查桑群和鲁谷组放射虫的发现及有关问题讨论

通常人们一直认为阿木岗(戈木日)群是所谓“羌塘地块”的前寒武纪或前泥盆纪基底,曾发现古生物化石的“中泥盆统”查桑群和“下二叠统”鲁谷组等是其上的晚古生代盖层沉积。本次工作在阿木岗群和鲁谷组中分别发现中-晚三叠世放射虫化石组合;在查桑群中发现二叠纪中-晚期放射虫化石组合。结合野外实际考察和前人研究成果,本文就有关问题作了讨论。     

澄江生物群分子在贵州遵义牛蹄塘组发现

澄江生物群是认识寒武纪生命大爆发的重要窗口,它的分布范围一直仅限于滇东地区,员近在贵州遵义松林牛蹄塘组底部页岩中发现有Naronia,Archotuba Conoidalis,Isaxys,Perpicaris,Lingulepis,Tsunyidiscus,Scenella,水母状化石(medusiform fossil),海绵动物化石Leptomitus,类似半索动物秆壁虫Rhabdopleura化石,软舌螺类Hyolithids,宏观藻类和疑源类化石Zunyiphyton perelegans Yang et Zhao,1999,Yuknessia sp.,Longenema Ding,1996,Sphaerocongregus variabilis等。其中有一部分是属于澄江生物群分子,这是云南省外澄江生物群分子的新发现。由于生物群之下40m处还产大量海绵动物、高肌虫和藻类化石等组成的松林生物群,其上又有下寒武统明心寺组古杯动物群,因此,这一生物群的发现对研究早寒武世生物的演化也具有一定的科学意义,同时,对澄江生物群的古生态学研究也具有重要意义。     

Pollution of Osheepcheon Creek by abandoned coal mine drainage in Dogyae area,eastern part of Samcheok coal field,Kangwon-Do,Korea

Osheepcheon Creek running through the Dogyae area is being polluted by the influx of the abandoned coal mine drainage. Generally, the more polluted water has lower pH and Eh and higher conductivity values. The concentrations of Mg, Ca, Fe, SO₄, and some trace elements, such as Cd, Co, Cr, Mo, Ni, Pb, Rb, Sr, U and Zn, are tens to hundreds of times more concentrated in the abandoned coal mine drainage than in the unpolluted streamwater. However, most immobile toxic pollutants from the mine drainage are quickly removed from the streamwater by the precipitation of amorphous Fe hydroxide and sorption on the precipitated Fe hydroxide. The fast removal of the pollutants from the streamwater maintains the water quality of the creek as acceptable at most places along the stream path, except where the abandoned coal mine drainage flows in. However, the creek has the potential of deteriorating quickly if the mine drainage is allowed to be continuously combined with the streams. A function of pH, Eh, and conductivity has been developed with discriminant function analysis for the purpose of easy, fast, and inexpensive measurement of the degrees of pollution of the streams. The estimated pollution of the streams with the discriminant function are consistent with what the chemical compositions of the water samples indicate. The pollution map of the study area was constructed from the calculated scores with the discriminant function. The pollution map suggests that the pollutants mainly come from the west side of Osheepcheon Creek. Thus, the abandoned coal mine drainage from the west side has to be appropriately treated as soon as possible to prevent Osheepcheon Creek from being further polluted. Considering the topography, climate, and the amount of the mine drainage, an active treatment method is recommended.     

江西城门山矿田块状硫化物型矿体矿化分带特征

通过城门山矿田矿床地质、矿体走向及倾向上的厚度及品位变化情况总结其矿化特征,根据成矿温度及地球化学成矿条件研究该矿体矿化富集规律的控制因素,并从矿化特征方面佐证讨论该类矿床的成因及外围找矿方向。研究表明,矿体矿化沿水平及垂向上均具有分带特征,大致表现为沿热液中心向外为Mo、Cu、Zn、Pb、Ag、Au元素的分带,从地表向下为TFe、Au、Ag、Pb、Zn、Cu元素的分带。除此之外,矿化还具有差异特征,表现为走向上矿体两端发育的不一致性、倾向上的局部豆荚状发育特征。本次工作厘定的分带性及差异性分别佐证了矿床的热液成因与沉积成因,并预测外围具有较好的多金属找矿前景,且东段好于西段。      

秭归地区闪长岩岩体风化壳微量元素地球化学特征

通过对秭归地区闪长岩岩体风化壳中微量元素的分布规律研究,将该风化剖面中的微量元素划分为3类。第一类包括Sc、V、Cr、Co、Ni、Cu、Zn、Zr、Hf、Nb、Ta、U、Th、Mo、W,基本属于非活动性元素,在风化过程中得以有效保留,其中U、Cr、Cu等受氧化还原条件的影响,有时呈局部富集现象,规律性不明显。第二类以Ca、Rb、Cs、Sr、Ba、Pb、Ga、Gd、Tl为代表,随着风化作用的进行而逐步从风化壳中淋失,属活动性元素。第三类以稀土元素为代表,在风化壳内部发生局部的再分配,从剖面上层随风化溶液向下淋滤亏损,到剖面中下部沉淀富集,其中重稀土元素的淋失程度大于轻稀土元素。由于母岩中斜长石的风化淋滤,Eu在氧化环境下逐渐从正异常变为负异常。Ce在地表氧化条件下很容易生成四价氧化物（方铈石）,并在表层明显富集,剖面介质中氧化还原条件的变化导致Ce的波动变化。     

Arsenic and metal mobility from Au mine tailings in Rodalquilar (Almería,SE Spain)

In the old mining area of Rodalquilar, mine wastes, soil and sediments were characterized and the results revealed high concentration of Au, Ag, As, Bi, Cu, Fe, Mn, Pb, Se, Sb and Zn in tailings and sediments. The contaminant of greatest environmental concern is As. The mean concentration in the tailings was 679.9, and 345 mg/kg in the sediments of Playazo creek. The groundwater samples from the alluvial aquifer showed high concentration of Al, As, Cd, Fe, Hg, Mn, Ni, Pb, Se, Sb and Zn and very high concentration of chloride and sulfate, which were above the concentration defined in the European standards for drinking water. The presence of As in groundwater may be caused by the oxidation of arsenian pyrite, the possible As desorption from goethite and ferrihydrite and the jarosite dissolution. Groundwater concentrations of Cd, Fe, Mn, and possibly Cu, were associated with low values of Eh, indicating the possible dissolution of oxy-hydroxides of Fe and Mn. The mobility of metals in the column experiments show the release of Al, Fe, Mn, Cr, Cu, Ni, V and Zn in significant concentrations but below the detected values in groundwater. However, As, Cd, Sb, Se Pb and Au, are generally mobilized in concentrations above the detected values in groundwater. The possible mass transfer processes that could explain the presence of the contaminants in the aquifer and the leachates was simulated with the PHREEQC numerical code and revealed the possible dissolution of the following mineral phases: jarosite, natrojarosite, arsenian pyrite, alunite, chlorite, kaolinite and calcite.     

STRATIGRAPHIC AND CORRELATIVE SIGNIFICANCE OF TERRIGENOUS COMPONENTS OF SEDIMENTARY ROCKS

The widely applied method of stratigraphic division of sediments and their correlation on the base of terrigenous components developed by 11ling, Baturin and others, was based on the fact that the composition of the sedimentary terrigenous components depends upon the petrographic composition of the distributive province rocks. The author, using terrigenous components for stratigraphic purposes, has based his method of the influence of the ancient crusts of weathering upon their composition. Under the ancient kaolin-type weathering conditions the mineralogy of forming sediments was very uniform: among rock-building minerals prevailed quartz, kaolin, partly hydromicas. Among accessories the following stable minerals prevailed: ilmenite, leucoxene, chromite, zircon, rutile, disthen, staurolite, tourmaline, cassiterite, and also less widely spread minerals such as sillimanite, anatase, brucite, corundum, xenotime, columbite, monazite, topaz, spinel, andalusite, diamond, gold, platinum, osmiridium.

Unstable under the ancient kaolin weathering conditions were: garnets, pyroxenes, amphiboles, epidote, magnetite, apatite, sphene, serpentine, olivine, titano-magnetite. Their contents in the deposits, formed at the expense of the kaolin crust of weathering, were as a rule insignificant.

From the above it is clear that the ancient weathering could have affected the mineralogical composition of accessory minerals of deposits, even much stronger than the petrographical composition of the distributive province.

In the course of geological times the total balance of stable accessory minerals, able to undergo repeated weathering and erosion, has the tendency to grow in spite of their dilution in sediments during certain epochs.

The author tried to give a stratigraphic division of the Mesozoic and Cenozoic deposits in the South Urals from terrigenous components.

This method can find a wide application.

In the future it will be advisable to combine the above mentioned method with the method of Illing and Baturin and others, taking into account the petrographic influence of the rocks of the distributive province. — Auth. English Summ.     

青藏高原中新世构造岩相古地理

系统分析青藏高原新生代中新世50余个沉积盆地的类型、构造背景、岩石地层序列,对青藏高原中新世构造岩相古地理演化特征进行分析和探讨。中新世,青藏高原海相沉积已经全面退出,全部转为陆相沉积,约23Ma时高原及周边不整合面广布,标志高原整体隆升。塔里木、柴达木及西宁-兰州、羌塘、可可西里等地区主体表现为大面积的构造压陷湖盆沉积。约17.2Ma左右,阿尔金山显著隆升,使柴达木盆地西叉沟一带再无生物礁灰岩出现,且在盆地西部出现了短暂的沉积间断。这一时期,柴达木盆地西部开始进入湖退期,而东南部则快速湖进;同时,大约17.7Ma索尔库里山间盆地初始凹陷形成。另外,高原腹地五道梁-沱沱河盆地受南部唐古拉山的挤压抬升,在16Ma左右结束了五道梁组的沉积,在可可西里—唢呐湖一带则再次凹陷接受唢呐湖组沉积,形成高原腹地的大型压陷湖盆。13～10Ma期间,藏南南北向断陷盆地的形成,是高原隆升到足够高度开始垮塌的标志;约8Ma以来,高原东北部几乎所有湖盆均进入湖退期,普遍出现冲积扇、辫状河和水下扇砂砾岩堆积。     

吉林“珲春组”的地质时代

“珲春组”系分布于吉林省东部的珲春、延吉和龙井等地区不同盆地的一套煤系地层,这套地层被认为代表下第三系古新统至渐新统。据研究,各地区不同盆地的岩性及植物化石成分差别甚殊,依据各地区植物化石的组合特征确定珲春二道沟的地质年代属晚白垩世,为使用方便仍可延用珲春组组名;延吉清茶馆的植物化石归古新世,龙井三合的植物化石归渐新世,因其各自地质年代不同,建议这二地区可分别另建新地层组名。     

湖北宜昌黄花场中/下奥陶统界线附近几丁虫组合及其地层学意义

对宜昌黄花场大湾组下段牙形石 Oepikodus evae带至 Baltoniodus triangularis带系统采集与分析几丁虫样品 ,共发现几丁虫 6属 12种 ,其中包括 1个相似种、1个未定种 ,它们是 Conochitina raymondii,C.ordinaria,C.primitiva,C.langei,C.brevis,C.poumoti,C.decipiens,Belonechitina cf.micracantha,L agenochitina esthoni-ca,L.sp.,Eremochitina baculata和 Cyathochitina dispar等。根据上述几丁虫的地质和地理分布特征 ,自下而上可划分为 Conochitina langei带和 Eremochitina baculata带 ,讨论并指出了他们与相关笔石、牙形石生物带的关系     

The Relationship between Fractures and Tectonic Stress Field in the Extra Low-Permeability Sandstone Reservoir at the South of Western Sichuan Depression

The formation and distribution of fractures are controlled by paleotectonic stress field,and their preservative status and effects on development are dominated by the modern stress field. Since Triassic,it has experienced four tectonic movements and developed four sets of tectonic fractures in the extra low-permeability sandstone reservoir at the south of western Sichuan depression. The strikes of fractures are in the S-N,NE-SW,E-W,and NW-SE directions respectively. At the end of Triassic,under the horizontal compression tectonic stress field,for which the maximum principal stress direction was NW-SE,the fractures were well developed near the S-N faults and at the end of NE-SW faults,because of their stress concentration. At the end of Cretaceous,in the horizontal compression stress fields of the NE-SW direction,the stress was obviously lower near the NE-SW faults,thus,fractures mainly developed near the S-N faults. At the end of Neogene-Early Pleistocene,under the horizontal compression tectonic stress fields of E-W direction,stress concentrated near the NE-SW faults and fractures developed at these places,especially at the end of the NE-SE faults,the cross positions of NE-SW,and S-N faults. Therefore,fractures developed mostly near S-N faults and NE-SW faults. At the cross positions of the above two sets of faults,the degree of development of the fractures was the highest. Under the modern stress field of the NW-SE direction,the NW-SE fractures were mainly the seepage ones with tensional state,the best connectivity,the widest aperture,the highest permeability,and the minimum opening pressure.     

西秦岭北带泥盆纪Nereites遗迹相及其环境分析

西秦岭北带泥盆系舒家坝组下一中上部的巨厚陆源碎屑岩系中含有极丰富的遗迹化石,它们可为解释该组沉积环境提供重要信息:（1）由大量典型深水遗迹化石组成的Nereites遗迹相,可与世界各地浊积岩系和复理石相中的Nereites遗迹相进行对比,该遗迹相主要发育在浊流沉积区直至深海平原,其沉积水深最大可超过2000m;（2）舒家坝组的遗迹群落中,除大量属深水型分子外,还见有典型的浅水分子,两种水深性质不同的遗迹组合共生在一个沉积剖面,正是浊积岩系和复理石相才具有的独特分布特征;（3）根据沉积层序和遗迹组合的对比确认舒家坝组不存在风暴岩。     

广西隆安娅怀洞遗址出土动物遗存初步研究

娅怀洞遗址是广西近年又一项重要考古发现,是一处石器时代洞穴遗址,文化遗存分为4期,第一至第三期属于旧石器时代晚期,第四期属于新石器时代晚期.本文以该遗址出土动物遗存为研究对象,鉴定其种属、部位、死亡年龄和性别等信息,观察遗存保存状态和表面痕迹,对其进行尺寸和重量测量.在此基础上,对其进行可鉴定标本数、最小个体数和骨骼发现率的统计,并依据统计结果进行自然环境的复原、人类行为和生业经济的初步分析.遗址出土动物包括软体动物(瓣鳃纲和腹足纲)和脊椎动物(鱼纲、爬行动物纲、鸟纲和哺乳动物纲),计27科19种(属).分析结果显示:自旧石器时代晚期到新石器时代晚期,遗址出土的主要动物,都包括有扁蜷螺科、方形环棱螺、斜口环棱螺、梨形环棱螺、高大环口螺、塔锥短沟蜷、佛耳丽蚌、刻纹丽蚌、三型矛蚌、圆顶珠蚌、河蚬、鲤鱼、青鱼、鳖科、龟科、钝吻鳄科、鸭科、雉科、猕猴、猪獾、野猪、牛亚科、羊亚科和不同体型的鹿科动物等,这表明自旧石器时代晚期到新石器时代晚期,遗址附近的自然条件没有发生大的改变,一直都存在有茂密的森林和相对广阔的水域,各种动植物资源都非常丰富;动物构成始终以哺乳动物纲中的鹿科和猪科数量最多,说明自旧石器时代晚期到新石器时代晚期,先民一直以狩猎鹿科和猪科为代表的野生哺乳动物来获取主要的肉食资源,同时也采集野生植物、捕捞水生的螺类、鱼类和爬行类作为食物资源的补充;从保存数量最多的鹿科和猪科骨骼发现率来看,存在有部分长骨骨骼缺失的现象,说明遗址并非先民宰杀肢解动物的主要场所,遗址中的动物多为先民宰杀肢解后带来的;鹿科动物掌/跖骨及与之相连的腕跗部骨骼发现率普遍较高,且要明显高于同时期的猪科动物,可能与先民有意识选择鹿科动物该部位的骨骼来制作骨器的行为有关;大量出土螺类存在壳顶缺失的现象,这应该与先民对螺肉的取食有关,与娅怀洞遗址的年代相当的柳州白莲洞遗址也存在类似的现象.从旧石器时代晚期到新石器时代晚期的纵向演变来看,先民对哺乳动物的利用程度是在逐渐增加的,对鱼的利用程度是大幅度减少的,对腹足动物的利用也有一定程度的减少,遗址动物群构成的这种变化体现了新石器时代晚期先民生活方式和生业经济选择(定居和农业)的变化.     

松嫩平原沼泽湿地区多目标地球化学调查方法试验

沼泽湿地属于一种特殊的生态景观条件。为了选择适合沼泽湿地区的多目标地球化学调查采样介质,在松嫩平原西部扎龙保护区开展了方法试验,采样介质主要采取沼泽湿地区的表层腐殖泥和基底冲积土2种介质。通过对比试验,反映出沼泽湿地区表层的腐殖泥是代表该景观区多目标地球化学调查的最佳采样介质。腐殖泥样品中的OrgC、N、S、Se、Hg、TC、U、Br、Au、TFe2O3、Bi、Cr、Ag、Li、Y、Mo、Cu、Sb等元素含量均高于其基底沉积物样品。这与沼泽湿地区的生态环境特征相吻合,而腐殖泥下部的冲积成因的基底物质属于外来物质,不能反映目前沼泽湿地区的生态环境特征,由此确定沼泽湿地区多目标地球化学调查最佳采样介质为表层的腐殖泥。