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1.
Mercury distribution was examined in the sediments of Lake Baikal that were sampled within the scope of the Baikal Drilling International Project in 1996–1999. The Hg concentrations in the ancient sediments are close to those in the modern sediments with the exception of a few peak values, whose ages coincide with those of active volcanism in adjacent areas. Mercury was demonstrated to be contained in the sediments in the adsorbed Hg0 mode, predominantly in relation with organic matter. When the organic matter of the bottom sediments is decomposed in the course of lithification, Hg is retained in the sediments adsorbed on the residual organic matter, and the concentration of this element corresponds to its initial content in the bottom sediments during their accumulation. Mercury concentrations in lithologically distinct bottom sediments of Lake Baikal and its sediments as a whole depend on the climate. Sediments that were formed during warm periods of time contain more Hg than those produced during cold periods or glaciation. Periodical variations in the Hg concentrations in the bottom sediments of Lake Baikal reflect the variations in the contents of this element in the Earth’s atmosphere in the Late Cenozoic, which were, in turn, controlled by the climatic variations on the planet and, thus, can be used for detailed reconstructions of variations in the average global temperature near the planet’s surface.  相似文献   

2.
武汉市墨水湖沉积物重金属污染特征与防治对策   总被引：8，自引：2，他引：8  
苏春利  王焰新 《矿物岩石》2006,26(2):111-116
武汉市墨水湖重金属污染严重,其污染特征在我国城市湖泊中具代表性。在对墨水湖不同湖区沉积物中重金属污染物空间分布特征进行分析的基础上,应用地积累指数法探讨不同重金属元素含量随深度变化的规律和原因,并对墨水湖沉积物中重金属的污染程度进行评价表明:墨水湖沉积物中重金属元素锌和汞污染最为严重,污染程度由高到低依次为:Zn>Hg>Cu>C r>Pb>A s;从整个湖区来看,分布有排污口的周边湖区污染严重,湖心污染程度较低;沉积物中主要重金属元素含量随深度增加而降低,其变化规律主要受污染状况的影响,沉积物颗粒粒径的变化和早期成岩作用的影响不大。为了改善墨水湖水质条件和重金属污染严重的现状,必须在截污、疏浚和引水工程等基本治理措施保护下,重建和恢复沉水植物系统,才能从根本上改善湖泊水质。  相似文献   

3.
应用部分非磁滞剩磁(pARM)谱,对山西宁武天池干海湖泊沉积物携带的磁信息研究表明,粗磁铁矿颗粒(MD)是主要载磁矿物颗粒,其pARM谱在低矫顽力区间(AF20 mT)达到最高值;而细磁铁矿颗粒(PSD-SD)为次要载磁颗粒,其pARM谱在高矫顽力区间(AF20 mT)稍有突起。但是,剖面三个层位具有不同特征,上层(大约7.3~4.0 ka)的粗磁性矿物颗粒含量最高,下层(大约12.0~13.0 ka)次之,而中层(大约12.0~7.3 ka)相对最低;中层的细磁性颗粒含量最高,下层和上层的细磁性颗粒含量次之。pARM谱分析结果与磁滞曲线测量获得的磁畴结果一致。在较高的交变磁场区间获得的pARM可以有效地压抑粗磁颗粒的信息,进而使细磁颗粒的信号增强。应用pARM谱分析,能有效判别样品中磁性矿物的磁畴状态,有助于沉积物的古气候、岩石磁学和古地磁学研究。  相似文献   

4.
The distribution and source of organic matter in reservoir sediments   总被引：2，自引：0，他引：2  
The bottom sediments of two reservoirs, one with significant river sediment input and one without, were analyzed for organic matter content. Lake Texoma sediments average 1.0% organic carbon, of which 0.26% organic carbon is deposited by the river sediments of the Red and Washita River deltas. In Fort Gibson reservoir, where there is minimal river sediment input, the organic carbon averages 1.2% and is deposited with a strong correlation to water depth (+0.9). There is a significant difference between the C/N ratio of Lake Texoma sediments (11.5) and Fort Gibson sediments (9.6). The higher C/N ratio is suggested to be a result of the larger input of terrestrial plant debris (with a high original C/N ratio) by the rivers draining into Lake Texoma and the relatively high resistance of the lignin material in the plant debris to decomposition in the reservoir sediments.  相似文献   

5.
武汉东湖现代沉积物磁组构特征及意义   总被引：3，自引：0，他引：3  
李晓  龙昱  申燕萍 《世界地质》2002,21(3):223-227
采自武汉东湖现代沉积物的0．86m长的样品被用于研究湖泊现代沉积物的磁性各向异性，研究发现，东湖的现代沉积可划分为3个阶段，不同阶段的沉积特征与磁学性质反映了不同的沉积环境物源差异，通过分析样品沉积特征，磁化率K值特征并结合磁性矿物在各层面间的差别，从而分析得出磁化率K值可作为地层划分的有效辅助手段，磁铁矿广泛存在于所有砂质及泥质沉积物中，是引起东湖现代沉积物磁化率变化的主导性物质。  相似文献   

6.
Lake Shala, the deepest lake in the internal Galla lakes basin of the Ethiopian Rift, fills a depression in Pleistocene volcanic rocks. Its sodium-bicarbonate (-chloride) water (salinity 16 g/l) is remarkably low in earth alkalines and sulphate. Stratification is indicated by different ion concentrations in the surface and bottom waters and by a thermocline in a water depth of 50–70 m. Hot soda springs emerging on the shores of Lakes Shala and Langano are believed to be derived from a hot saline underground reservoir recharged by meteoric waters. The ion composition of the hot spring waters is uniform and matches that in the Galla Lakes except for total salinities. Anomalous heavy metal concentrations are lacking in lake and hot spring waters. Sediments of Lake Shala belong to an extremely fine-grained group of deposits. They are poorly sorted and the lateral distribution of the grain sizes does not follow the normal scheme for aquatic depositional environments. A belt, 50–100 m below lake level containing the finest-grained sediments, separates the shallow periphery of the lake bottom from the deep center, both characterized by coarser-grained deposits. The sediments consist of a large portion of glassy components. A poorly cristallized smectite is most abundant in the clay mineral group. The components of the sand fraction are quartz, feldspar, glass particles and occasionally calcite. Nickel, cobalt and lead are depleted in the Lake Shala sediments compared with the averages of shales. Iron, manganese and zinc are relatively high. Silver, cadmium and some of the rare earth elements are enriched by factors of > 5.  相似文献   

7.
Regularities of the formation of bottom sediments down to a depth of 1.2 m, as well as factors governing the composition of sediments, waters, and soils in the catchment area of the lake, are discussed. It has been established that the chemical composition of lacustrine sediments is closely associated with the composition of soils in the ambient watersheds, and the soils, in turn, are associated with the composition of the soil-forming rocks. The available data suggest an extremely irregular contamination of the lake system by technogenic radionuclides within the water area. Maximum radiocesium contamination of lacustrine bottom sediments is 350 mCi/km2 (recalculated to year 2000). Concentrations of elements (Cu, Zn, Cr, Ni, Co, Mg, Be, Sb, Mn, and others) in bottom sediments, water, and soils in catchment areas of Lake Kolyvan do not exceed the background values (except for the Hg content in bottom sediments), suggesting that the area under consideration is not contaminated by inorganic technogenic components.  相似文献   

8.
青海巴颜喀拉山北麓古高位湖相沉积的分布与特征   总被引：3，自引：0，他引：3  
巴颜喀拉山北麓地区古湖岸线分布广泛,湖相沉积与湖成地貌发育。目前,在扎陵湖和鄂陵湖沿岸可清晰地划分出4级湖岸阶地、多级湖相沉积和古高位湖相沉积。古高位湖相沉积出露的最高海拔为4615m,分别高出现代扎陵湖水面328m、鄂陵湖水面346m;在扎陵湖和鄂陵湖谷地分布着多级湖岸堆积阶地或基座阶地、多级湖相沉积和古高位湖相沉积;在小野马岭、大野马岭、扎陵湖北等地的基岩山丘上,也发育有多级湖相沉积和古高位湖相沉积,其古高位湖相沉积高出现代扎陵湖和鄂陵湖湖面50～350m。巴颜喀拉山北麓古高位湖相沉积的形成时代可能为中更新世。  相似文献   

9.
The Nansi Lake has been seriously affected by long-term intensive industrial and urban activities. The objectives of this study were to determine the content, distribution, and ecological risk of arsenic and investigate the geochemical relationships between arsenic forms and sediment mineral phases of the Nansi Lake. Twenty samples of surface sediments were collected and analyzed for arsenic contents and chemical forms. Results indicated that total content of arsenic in the sediment samples averaged 13.45?mg/kg and ranged from 8.27 to 21.75?mg/kg. The arsenic was mostly associated with iron oxides (67.3%), followed by the association with the residual fraction (19.2%). In addition, total content of arsenic was positively correlated with the organic matter and iron contents in the sediment. The molar ratios of iron oxide bound arsenic content to iron content are lower than the maximal molar ratios of arsenic to iron for natural hematite, magnetite, and goethite. The total content of arsenic in the sediment samples was usually higher than threshold effect concentration of 9.79?mg/kg, but lower than probable effect concentration of 33.0?mg/kg for arsenic in freshwater sediments. Adverse effects or toxicity to the aquatic organisms, caused by arsenic in the sediments of the Nansi Lake, will likely occur at these levels of arsenic contamination.  相似文献   

10.
Mercury contribution to an adirondack lake   总被引：1，自引：0，他引：1  
Elevated copper, lead, and zinc concentrations in the upper 10 to 20 cm of sediment sampled from Cranberry Lake, a large Adirondack lake, are attributed to atmospheric contributions. Pb-210 and pollen core data, however, suggest Cranberry Lake also received mercury discharges during the turn of the century when the area was the center of extensive lumbering and related activities. Elevated mercury concentrations in Cranberry Lake smallmouth bass derived from remobilization from mercury-contaminated bottom sediments which increased the bioavailability to Cranberry Lake organisms. Mercury remobilization and accumulation by fish are promoted by fluctuating pH values resulting from acid precipilation.  相似文献   

11.
The paper presents the results of a comprehensive investigation into the recent sediments of Proval Bay. This bay formed during catastrophicflooding of a big block of land as a result of an earthquake in 1862. Comparison of the sketch map of the bay for 1862 with its modern mapshows that the boundary of the Selenga River delta has shifted considerably eastward. The sediments of Proval Bay are sands, silty pelite,and pelitic silt. Terrigenous material is predominant and consists of mineral grains and land plant remains, admixed with diatom frustules andsponge spicules. In the southwestern part of the bay, turbidites and a soil layer have been found. The latter was buried when the water levelin Lake Baikal rose after the construction of the Irkutsk dam in 1959–1964. In the northeastern part of the bay, a peatlike layer has beenfound in the bottom sediment core. It formed in Lake Beloe, which existed in the Tsagan steppe before the 1862 earthquake. According todiatom analysis, this lake was shallow and eutrophic. The sedimentation rates in different parts of Proval Bay differ greatly and directly dependon proximity to the Selenga River. Variations in the geochemical indicators which reflect the ratio of organic to clastic components in thebottom sediments of the bay are controlled by temperature and water level variations in Lake Baikal.  相似文献   

12.
The minor-element composition of bottom sediments from the littoral zone of the northern part of Lake Ladoga was studied. Close relationships between the anomalous Cd concentrations in lake sediments and Quaternary glacial formations on the territory of Karelia were shown. A negative correlation of Cd with other heavy metals and a positive correlation with Zr were observed. Most likely, Cd is an impurity in zircons from sandy and sandy loam sedimentary formations on the northern coastal area of Lake Ladoga.  相似文献   

13.
太湖北部底泥中氮、磷的空间变化和环境意义   总被引：34，自引：5，他引：34  
以太湖底泥为研究对象，通过分析不同形态N，P的含量，揭示太湖北部底泥N，P的区域和垂向变化特征，探讨了主要营养元素的环境意义。太湖北部底泥N，P的高值区分布在五里湖，梅梁湾北部和竺山湖北部，有效氮的分布与总氮的分布一致。相关分析表明，有效磷与无机磷具有很好的正相关性，N，P的含量还与粘土矿物的含量成正比。柱状样的N，P垂直变化显示，数千年人类的活动并未明显影响底泥中N，P的含量，而在近代则明显增加。底泥中大量的N，P主要来自生活污水，其次是农田肥料和围网养殖。  相似文献   

14.
Chemical, radioisotopic, and palynological studies of the bottom sediments of mesotrophic Lake Arakhlei have been carried out for paleoclimatic reconstructions and estimation of the sedimentation rate.  相似文献   

15.
Doklady Earth Sciences - We estimated the age and sedimentation rate of bottom sediments in Cheko Lake located in southern Evenkia, in the territory of Tunguska Nature Reserve, near the supposed...  相似文献   

16.
The results of studying the structure and mineral composition of the Upper Holocene bottom sediments of Lake Onega are presented. It is established that there are two types of columns of bottom sediments, for which stratification of layers and formation of Fe–Mn crusts are determined by the diagenesis processes occurring under physicochemical conditions of sediment accumulation according to two scenarios. The distribution spectra of rare-earth elements (REEs) are different in the indicated types of columns, which is apparently attributed to the differences in the oxidation–reduction conditions at the water–sediment interface during the formation of REEs and possibly to the influence of hydrothermal processes.  相似文献   

17.
青海湖底沉积物的矿物物相及有机质保存研究   总被引：2，自引：0，他引：2  
盐湖沉积环境是烃源岩发育的重要地质环境。本文以青海湖湖底沉积物为例，根据有机质与粘土矿物含最及矿物表面积的关系，分析了矿物学因素对盐湖相富有机质沉积物中有机质保存的影响。研究发现：湖底沉积物中有机质丰富，为上层水中的浮游生物和南河流携带束的陆地高等植物两种来源。矿物物相分析发现沉积物中粘土矿物含量达到32．4％，以伊利石为主。沉积物经密度分离后测试发现，有机碳含量与粘土矿物含量及矿物表面积之间具有很好的正相关性，说明粘土矿物吸附是青海湖底沉积物中有机质的主要赋存形式。  相似文献   

18.
Magnetic measurements have been performed on volcanic catchment rocks, present-day soils, and cored sediments from Lake Massoko, an oligotrophic maar-lake from SW Tanzania. Magnetic concentration proxies, low- and high- temperature experiments, and hysteresis behavior, suggest significant contributions of Ti-magnetite and SP/SD (oxidized) magnetite in tuff-ring material transformed by pedogenesis (modern soil, littoral sand). In contrast, the basalt is characterized by relatively low concentrations of PSD-SD magnetite.Three depth/time intervals present magnetic signatures similar to the modern soils and littoral sands, at ~43-38 kyr, ~12-1.3 kyr, and 400-300yr BP (the uppermost 30 cm). They likely correspond to humid (high-lake stand) periods, with increased pedogenic processes and runoff. Other sediments have magnetic signatures closer to the catchment basalt, possibly indicating arid/low-stand periods with increased detrital inputs from the basaltic crater wall. Sediments deposited during the Last Glacial Maximum (~38-12kyr) present high Jrs/Js-high Hcr/Hc intervals, indicating an additional high coercivity component of unknown origin.  相似文献   

19.
Doklady Earth Sciences - The metal composition of water and bottom sediments of the southern tributaries of Lake Baikal has been studied, and the water migration coefficients have been calculated....  相似文献   

20.
Doklady Earth Sciences - The results of this study on carbonate-containing bottom sediments of the shallow brackish Lake Itkul, West Siberia, are presented. The study methods applied included X-ray...  相似文献   

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