不同岩性盐湖沉积物中挥发性有机质的特征

通过不同岩性盐湖沉积物中C/N值,确定其有机质的来源均为藻类,然后采用气相色谱—离子迁移谱(GC-IMS)联用技术对不同岩性盐湖沉积物中的挥发性有机质进行了研究。结果显示,不同岩性沉积物的挥发性有机质虽然来源相同,但是其种类和含量存在显著差异。在砂岩沉积物中,检测出16种挥发性有机质,而石盐中共检测出30种挥发性有机质。砂岩样品中未检测出酯类化合物,而检测出的醛类、酮类、醇类以及呋喃类化合物的含量均比石盐中的含量要小,硫化物的含量与石盐中的含量差距较小,但砂岩中酸类物质的含量比石盐中高。这可能是由于在不同沉积时期,湖泊中生产有机质的藻类物质种类和含量不同,以及在早期成岩过程中沉积环境对有机质的保存和降解不同所造成的。     

青海可可西里东部盐湖水化学及沉积特征初步研究

2008 a夏对可可西里地区东部4个新发现的盐湖,进行了卤水水化学组分、矿物组成及其石盐元素含量分析。结果表明,该区水体卤水矿化度高,湖表卤水富硼锂等组分。通过对化学组分及水化学特征系数的研究,卤水的水化学类型主要为硫酸镁亚型和硫酸钠亚型。卤水pH值随着矿化度的增加而降低。Na+、Cl-含量与总矿化度呈正相关,SO42-"与矿化度呈负相关。Li与Mg物源、迁移规律近似。本区盐类沉积物以石盐为主,石盐中Si、Al、Fe、Sr含量低,其间相关性好,物质来源可能为周围岩石风化。布查盐湖盐类沉积存在少量硬石膏、半水石膏和铁白云石,表明布查盐湖的盐类物质来源很可能与地下热水作用有关。     

南极南设得兰群岛附近海域表层沉积物中有色溶解有机物的分布特征及来源分析

在南极南设得兰群岛附近海域采集了6个表层沉积物样品,测定了提取液中溶解有机物(DOM)的有机碳含量、紫外-可见吸收光谱和三维荧光光谱,并对有色溶解有机物(CDOM)的分子量信息及各荧光组分的成分和来源进行了分析。结果表明,南设得兰群岛附近海域表层沉积物中DOM提取液的溶解有机碳(DOC)及沉积物有机碳(SOC)的含量呈现由近岸向开阔海域递减的趋势,紫外-可见吸收光谱中的吸收系数(a)也表现出了相似的性质,光谱斜率比(SR)表明近岸沉积物CDOM老化程度较强。通过对三维荧光光谱的分析可知,南设得兰群岛附近海域表层沉积物中的CDOM包含3种荧光组分,即类色氨酸、海洋类腐殖质和陆源类腐殖质,表现出较强的自生源特征,整个研究海域CDOM来源以内源为主,受陆生植物和土壤有机质的外源输入影响较小。通过CDOM各参数的相关性分析发现,沉积物DOM提取液的DOC含量与SOC含量以及吸收系数和腐殖化指数(HIX)等参数相互之间都呈显著正相关,相关系数(r)均在0.88以上,显著性水平P0.01。     

三江平原泥炭沼泽沉积物中营养物质的分布规律

采用冬季采样，现场分层的方法，系统地研究了三江平原沼泽中河床一河漫滩型泥炭地和谷底洼地型泥炭沉积中总氮、总磷和有机质等营养物质的分布特征。结果表明，在不同沉积层中，总磷明显在草根层富集，总氮和有机质在泥炭上层含量最高，其他营养物质含量随着深度的增加而逐渐降低。河床一河漫滩型和谷底洼地型泥炭沉积物中总氮和总磷含量随着泥炭粒级的减小而明显增加。河流型泥炭沉积物不同机械组分中总氮的变化幅度远远大于谷底洼地型，两种类型泥炭地不同机械组分中总磷含量的变化差异幅度不大。有机质含量随着泥炭粒级的减小而明显减少。河床一河漫滩型泥炭地和谷底洼地型泥炭地中总氮含量与有机质含量呈显著的正相关，相关系数分别为0.953和0.944，泥炭中的氮主要以有机氮形态存在，而总磷含量与有机质含量的关系不显著。     

达里诺尔湖沉积物粒度及营养盐垂直分布特征变化

通过对达里湖湖中心柱状沉积岩芯总氮(TN)、总磷(TP)、有机质(OM)和粒度指标的测试与分析,探讨其垂向分布特征及影响因素。结果表明,营养盐TN、TP和OM的含量分别为2.12~3.71 g/kg、0.48~0.74 g/kg和4.71%~7.97%,平均值分别为2.98 g/kg、0.64 g/kg和6.29%。1832~1941年,TN、TP和OM含量较为稳定且含量较低;1941~1965年,TN和TP含量不同程度上先增加后减小,OM含量呈减小趋势;1965~2011年,TN、TP和OM含量整体上表现为增加趋势。沉积物中C/N值显示有机质及营养盐的主要来源为浮游动植物,沉积物粒级组成以粘土为主。沉积物中OM与TN和TP极显著相关,说明沉积物中氮主要以有机氮的形式存在,有机质与磷的生物地球化学循环也有相当紧密的关联;TN与TP表现出极显著相关性,说明沉积物氮、磷在沉积行为上有一定的相似性。沉积物中TN、TP和有机质与粒径小于4μm的颗粒正相关,与其它粒径的颗粒负相关。     

盐湖卤水及其沉积物中微量元素的初步研究

用中子活化分析测定盐湖卤水及其沉积物中的微量元素仍是首次．从其测定结果来看，一般盐湖卤水中的微量元素均高于南极海水和大洋水，并随着卤水的浓度增高而增加着．其盐沉积物中的微量元素均高于其卤水，主要是由于粘土的吸附作用所致．     

西藏扎布耶盐湖太阳池中富锂混盐的矿物学与地球化学特征及意义

扎布耶盐湖是全球最独特的自然结晶扎布耶石(Li2CO3)的盐湖。该盐湖正在开发利用中,2020年产富锂混盐4500吨。实验所采取的样品是通过“盐梯度太阳池”技术结晶出来的10件富锂混盐。通过对采集的样品进行X射线衍射、扫描电镜、电感耦合等离子质谱法、离子色谱法和滴定法的测试,得到了矿物组成的成分和化学元素组成含量数据,扎布耶盐湖太阳池富锂混盐中的物相组成有扎布耶石、钾石盐、石盐、氯碳钠镁石、天然碱、钾芒硝、菱锰矿、石英这8种,其中菱锰矿是首次从富锂混盐中发现的矿物,扎布耶石的含量为24.10%-88.27%,平均为62.89%,是该盐湖中含量最高的矿物。测试的样品中Li含量4.56%-16.70%,平均为11.90%；K+含量为0.14%-10.17%,平均为2.42%； KCl的含量为0.26%-20.44%,平均为4.63%(工业品位1%)。该混盐的结构和构造的形成受温度和水流的影响,温度越高碳酸锂的结晶速率越快,碳酸锂的晶核生长速率和晶粒大小与温度呈正相关。扎布耶盐湖二期工程预计年产20000吨碳酸锂,其中利用膜法生产12000吨；利用太阳池技术生产8000吨,预计年产出12700吨的富锂混盐,可以产出约600吨氯化钾,建议进行综合利用。     

察尔汗盐湖线形沙丘沙物质来源及输移路径

采用地球化学元素方法,探讨了察尔汗盐湖北岸线形沙丘的沙物质来源,并对区域物质输移路径进行了讨论。结果表明：戈壁、雅丹廊道流沙和线形沙丘的常量元素均以SiO₂、Al₂O₃和CaO为主,微量元素均以Cl、Ba、Sr和Co含量较高;线形沙丘与戈壁表层沉积物的常量与微量元素的UCC标准化值分布模式均较一致,且与距盐湖较近的雅丹廊道流沙也存在一定程度的相似性;沉积物的化学风化程度较弱,均处于早期的脱Na、Ca阶段,且在A-CN-K三角图中均位于大陆风化趋势线的反向延长线上,可能代表河流溶质的风化趋势。因此,戈壁表层沉积物和雅丹廊道流沙在线形沙丘形成过程中均可提供沙物质来源,且前者提供的沙物质应该更多。柴达木盆地可能为其下风向黄土的物质源区之一,但是提供的粉尘颗粒有限。     

盐湖沉积物的穆斯堡尔效应研究

对青海柴达木盆地察尔汗、昆特依盐湖以及新疆罗布泊盐湖一系列沉积物样品进行了穆斯堡尔效应的研究。对全部样品做了常温下的穆斯堡尔谱学测量,并对部分样品做了低温下的测量。从穆斯堡尔谱的解析结果可知,盐湖沉积物黏土矿中含二价铁的主要矿物是绿泥石,在察尔汗盐湖样品中有少量菱铁矿;三价铁存在于多种矿物和非晶态的氢氧化物中;某些样品中含有少量的赤铁矿,它在常温下即出现磁有序。不同盐湖的沉积物样品和同一盐湖不同深度样品的含铁矿物组成及相对含量不同,Fe2+/Fe3+的比值也不同。这些结果可以反映出盐湖沉积过程中地球化学和环境及气候的变化。     

粒度在沉积物物源判别中的运用

自然界中沉积物的组成和成因具有多样性。应用粒度方法可以区分、提取和判别沉积物中的各个组分。粒度方法主要有频率曲线和累积曲线分布法、数学函数组分提取法(包括Weibull分布函数拟合法、端元模型分析法、标准偏差法、粒度分维法等)和粒度参数判别公式法。综合应用上述方法可有效地判别出单一沉积物的物质来源或者复杂沉积物中的各个组分,而这些方法被前人广泛地应用于湖泊研究中,提取了过去的环境变化信息,也指导了作者在盐湖沉积中的研究工作。     

Lacustrine Sedimentary Organic Matter Records of Late Quaternary Paleoclimates

Identification of the sources of organic matter in sedimentary records provides important paleolimnologic information. As the types and abundances of plant life in and around lakes change, the composition and amount of organic matter delivered to lake sediments changes. Despite the extensive early diagenetic losses of organic matter in general and of some of its important biomarker compounds in particular, bulk identifiers of organic matter sources appear to undergo minimal alteration after sedimentation. Age-related changes in the elemental, isotopic, and petrographic compositions of bulk sedimentary organic matter therefore preserve evidence of past environmental changes.We review different bulk organic matter proxies of climate change in tropical and temperate sedimentary records ranging in age from 10-500 ka. Times of wetter climate result in enhanced algal productivity in lakes as a consequence of greater wash-in of soil nutrients, and these periods are recorded as elevated Rock-Eval hydrogen indices, lowered organic C/N ratios, less negative organic 13C values, and increased organic carbon mass accumulation rates. Lowering of lake water levels, which typically depresses algal productivity, can also cause an apparent increase in organic carbon mass accumulation rates through suspension of sediments from lake margins and redeposition in deeper basins. Alternations between C3 and C4 watershed plants accompany climate changes such as glacial/interglacial transitions and wet/dry cycles, and these changes in land-plant types are evident in 13C values of organic matter in lake sediments. Changes in climate-driven hydrologic balances of lakes are recorded in D values of sedimentary organic matter. Visual microscopic examination of organic matter detritus is particularly useful in identifying changes in bulk organic matter delivery to lake sediments and therefore is important as an indicator of climate changes.     

扎龙湿地克钦湖表层沉积物中有机质、全氮和全磷含量分布特征

为了了解扎龙湿地克钦湖沉积物中营养物质的分布状况,在扎龙湿地克钦湖设置了21个采样点,于2016年7月9日,采集了0~5 cm深度的沉积物样品,测定了表层沉积物样品中有机质、全氮和全磷含量;利用克里金插值法,绘制表层沉积物有机质、全氮和全磷含量的空间分布图,并分析了其空间分布特征及影响因素。研究结果表明,克钦湖0~5 cm深度沉积物中有机质和全磷含量整体上由东北向西南逐渐减小,北湖区表层沉积物中的有机质和全磷含量都大于南湖区;克钦湖中西部表层沉积物中的全氮含量较大,东南部的较小,南、北湖区表层沉积物中全氮含量平均值较接近;克钦湖表层沉积物整体呈弱碱性,北湖区表层沉积物组成以粉砂土为主,南湖区表层沉积物组成以砂土为主;表层沉积物中有机质、全氮和全磷含量与研究区的地势、植物群落分布和周边人类活动有关,粉砂土含量和pH是影响表层沉积物中有机质、全氮和全磷含量分布的主要指标。     

艾比湖干涸湖底不同景观类型下富盐沉积物盐分积聚特征

以艾比湖东南部历史时期干涸湖底为研究区,对6种不同景观类型下富盐沉积物进行采样分析。运用经典统计研究了干涸湖底各景观类型下富盐沉积物盐分含量及盐分积聚特征。结果表明:不同景观类型的沉积物可溶性盐分含量差异显著。从平均值角度看,各景观类型表层沉积物中0～30 cm层的盐分含量占0～60 cm层盐分含量的70％,即沉积物盐分垂直分布呈强表聚性。各景观类型的沉积物盐分含量均属于中等变异强度（30%相似文献   

Delivery and deposition of organic matter in surface sediments of Lagoa do Caçó (Brazil)

Elemental and isotopic compositions of organic matter in surficial sediments from five transects across Lagoa do Caçó (Brazil) were analyzed to identify the depth-related processes that affect the production and deposition of sedimentary organic matter in this shallow tropical lake. Each of four transverse transects began at a margin dominated by aquatic macrophytes (Eleocharis), crossed the central deep part of the lake, and terminated in the opposite, macrophyte-dominated margin. In each transect, TOC concentrations, C/N ratios, and δ¹³C values decreased between 0 and 4 m, whereas δ¹⁵N values increased. The variables remained stable in sediment from 4 m water depth to the center of the lake at 10 m. The depth-related patterns reflect differences in both the delivery and the deposition of organic matter in the lake. Organic matter is produced in abundance in the marginal area by emersed and submerged macrophyte vegetation that diminishes with depth and disappears at 4 meters. After the disappearance of macrophytes, organic matter is produced at low rates principally by open-lake phytoplankton. Drawdown of dissolved oxygen is high in the lake margins, but it is low in the oligotrophic open waters of the lake. Preservation of organic matter is consequently better in sediments of the lake margins than in deep waters. The depth-related pattern of organic matter delivery and deposition in the sediments of Lagoa do Caçó, in which water levels are sensitive to groundwater fluctuations, shows that the elemental and isotopic compositions of sediment organic matter can provide a record of changes in the paleohydrology of this and other similar shallow lake systems.     

北极新奥尔松地区湖泊沉积物色素含量变化及环境意义

大量的古气候资料和现代器测数据表明,最近100年来北极气候经历了明显的变暖过程,这必然会对脆弱的极地湖泊生态系统产生影响。以北极新奥尔松地区的湖泊沉积柱样为研究对象,对其中4种色素(叶绿素及其衍生物CD、总胡萝卜素TC、蓝藻叶黄素Myx和颤藻黄素Osc)进行了分析,结合其他物化指标如碳酸钙含量、TOC等,从历史演化的角度重点探讨了新奥尔松地区最近100年以来湖泊初级生产力演化过程。结果表明,在相对寒冷的小冰期,气候对湖泊中藻类的生长不利,湖泊生产力下降,沉积物中色素含量出现低值,生物硅含量降低;表层5cm(对应约1890AD)沉积物中有机质含量显著升高,各色素含量均明显增加,表明小冰期后气温上升,导致湖泊藻类生长迅速,湖泊生产力大大提高,但此时生物硅仍保持在相对较低的水平,这可能与其他藻类的竞争生长有关。最近100年,沉积物中Osc/Myx比值不断降低,表明该湖泊中蓝藻含量不断上升,暗示北极地区人类活动的增强可能导致湖泊营养水平增加。     

生物硅在东南极湖泊古初级生产力研究中的应用

本文对南极中山站区的莫愁湖和大明湖沉积物中生物硅、有机质等环境指标进行了分析,并在对比研究的基础上,探讨了生物硅在重建东南极湖泊沉积生态环境记录研究中的应用.研究结果表明,大量保存较好的硅藻出现在东南极淡水湖泊沉积物中,生物硅含量在深度剖面上表现出显著波动,与有机质等生物地球化学指标具有一致的垂向变化趋势,表明它们具有...     

Within-lake variability of subfossil chironomid assemblages in shallow Norwegian lakes

Subfossil chironomids in the surface sediments of five small and shallow Norwegian lakes were studied to determine the within-lake variability of fossil assemblages, changes in chironomid assemblages with respect to water depth, and the representativeness of single samples for the entire chironomid fauna of a lake. In each of the lakes studied, six short sediment cores in the deepest part of the lake basin and two littoral to deep-water transects of seven cores each were obtained using a gravity corer, and chironomid assemblages in the uppermost centimetre of sediment were analysed. In three of the five lakes, chironomid concentrations were highest in the deepest parts of the lake basins. In the remaining two lakes, concentrations were either very variable or, in a lake with clear indications of anoxia in the bottom waters, highest at intermediate water depth. Chironomid assemblages tended to be dominated by the same taxa within a lake basin. However, in each of the lakes studied there was a clear and statistically significant shift in chironomid assemblages with respect to water depth. The organic content of the sediments was statistically significant in explaining the variance in the chironomid assemblages only in lakes where organic matter content was closely related to water depth. Only a few chironomid taxa were restricted to the shallowest parts of the lake basins, whereas a number of chironomids were found exclusively in deep-water sediments. Chironomid head capsules of running water taxa and simuliid remains were generally found in sediments close to lake tributaries and in the deepest parts of the lake basins. Although any individual sample contained only a part of the total subfossil chironomid fauna (21–63% of the total taxa per lake), chironomids dominant in any section of the study lakes were found in most of the transect and mid-lake samples.     

Porewater geochemistry and solute flux from bottom sediments,Devils Lake,North Dakota

Sediment cores were collected for pore-water analysis from the eastern end of Devils Lake, located in northeastern North Dakota, to determine diagenetic reactions occurring in surficial bottom sediments and to evaluate the impact of these reactions on chemical concentrations in the overlying lake water. Sediment pore waters are enriched in major ions and nutrients relative to lake water. The principal sources of major ions to pore water are saline sediments located in the upper 1 m of bottom sediment. The principal source of titration alkalinity and nutrients to pore water is microbial decomposition of sedimentary organic matter by sulfate reduction. Sediment pore waters in the eastern part of Devils Lake have higher major-ion concentrations and solute-flux rates than the sediment pore waters in the central part of the lake. In contrast, sediment pore waters in the central part of Devils Lake have significantly higher nutrient concentrations and solute-flux rates. Major-ion concentrations and solute-flux rates in sediment pore water increase from west to east. These trends indicate that bottom-sediment diagenetic processes are, in part, responsible for the observed concentration gradient in the lake. The higher nutrient concentrations and the higher nutrient diffusional-flux rates in Main Bay are the result of more labile sedimentary organic matter and the occurrence of sulfate reduction. Environmentally-reactive trace-metal concentrations (Cu, Pb, Zn, and Fe) in bottom sediments decrease from west to east with distance from the surface-water sources and with increasing surface-water salinity.