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1.
中国海洋有机地球化学研究的若干进展   总被引：5，自引：0，他引：5  
在过去的近二十年中,中国海洋有机地球化学在中国边缘海及一些大河口体系中进行了研究,获得了诸多成果,如：中国边缘海的物质输入特点是陆源输入的影响由北至南减弱而海  相似文献   

2.
A total of about 1100 well-distributed samples of suspended matter in surface waters off the length of eastern Asia are available. From these samples, 180 were selected for detailed examination of the non-combustible fraction using optical and electron microscopy along with computer methods of particle measurement and counting. The results showed that, generally, all major components of the suspended matter are most abundant in the nearshore belt (combustible fraction, mineral grains of silt size, skeletal debris, and clay minerals), the result of mechanical transport of detrital sediment and chemical transport of nutrients from the land. Mineral grains of silt size average about 2%, skeletal debris plus clay minerals—23%, and combustible organic matter—75% of total sample weights, but the last two categories vary over a wide range depending upon geographical positions of the samples. Most evident is an oceanward decrease in percentage and concentration of the total noncombustible fraction and an oceanward increase in median diameter of the mineral grains.  相似文献   

3.
Components of suspended matter in surface waters between western Africa and the Mid-Atlantic Ridge were removed by filtration and measured by scanning electron and optical microscopy. Skeletal debris from diatoms, dinoflagellates, and other plankton are most concentrated in Antarctic surface water and in regions of coastal upwelling. Detrital mineral grains are most concentrated in nearshore regions, from discharge of major rivers, erosion of sea cliffs, and deposition from offshore winds. Farther offshore are high concentrations of mineral grains brought by trade winds from deserts in both northern and southern Africa. The winds also bring freshwater diatoms and woody tissue. The remaining component on the filters is marine organic matter, mostly in thin films. These films trap skeletal debris and mineral grains. Presumably, animals that graze upon the films further concentrate the grains into faecal pellets whose rapid settling carries the grains into deeper waters and to the bottom. The films were found in all other areas of the world ocean from which surface samples were spot-checked: off eastern Asia, off eastern North America, and the central Pacific. Thus they appear to be a major factor in marine sedimentation. In areas of upwelling off western Africa, the total suspended matter in surface waters averages about 0.1 mg/1 of filtrate, about five times that present in the open ocean. It consists of about 70% organic matter, 29.6% skeletal debris, and 0.4% mineral grains, in contrast with concentrations in the open ocean of 90%, 8% and 2%, respectively.  相似文献   

4.
Rivers transport huge quantities of terrigenous material mobilized in their drainage areas and represented by rock fragments and grains of quartz, feldspars, and other weathering-resistant minerals. Large volumes of fine clay particles and organic components in the form of suspended matter and dissolved salts are also transported from the land to seas and oceans. This material is deposited in river deltas located on shelves and submarine fans, which are formed on the continental slope and at its foothill. Thick lenses of deltaic and submarine fan sediments turn gradually into oil-and gas-bearing basins, the largest among which is the Gulf of Guinea basin.  相似文献   

5.
《Applied Geochemistry》2004,19(7):1111-1121
The quality, quantity, and origin of suspended organic matter were studied in the highly agricultural Upper Scioto River in Central Ohio. Late summer baseflow conditions were compared to late autumn high flow conditions. Variables examined in the suspended matter were the total suspended solids concentration, semi-quantitative concentrations of lignin, carbohydrate concentrations, total organic C, total and organic P, and δ-13C. Also examined were ratios of C to N, organic C to organic P ratios and fluxes of total organic C. The primary hypothesis of this research was that the quality (or biodegradability) and quantity of organic matter in the Upper Scioto River would increase during autumn stormflow conditions due to inputs of fresh terrestrial organic matter. The autumn suspended matter was also expected to reflect C4 plant contributions from corn organic matter. Results show that the quality and quantity of organic matter were greater during summer, as reflected in low molar ratios (178:1) of organic C to organic P, and higher organic C content of the suspended matter in summer. Summer suspended matter was 3.6% organic C and autumn suspended matter was 2.3% organic C. Carbon to N molar ratios in both seasons were very close to the Redfield ratio (6.6:1 in summer and 6.7:1 in autumn). Total suspended matter and total organic C concentrations were lower in autumn (8.7 mg/l−1 TOC and 17.7 mg/l−1 TSS) than in summer (17.5 mg/l−1 TOC and 39.0 mg/l−1 TSS), but the fluxes were greater in autumn due to greater stream flow. Stable isotope analyses suggested a phytoplankton or C3 plant source (most likely corn) for summer organic C (mean δ13C of −24.8‰) and a phytoplankton or C4 plant source for autumn organic matter (δ13C=−21.5‰).  相似文献   

6.
With the purpose of tracing the variations of the organic matter sources of sediments, a sample column (25.96 m in size) from the Hemudu Area of Hangzhou Bay was put through AMS14C dating and biogeochemical analysis. TOC and TN presented similar variation trends, suggesting the same and stable sources of organic matter; the bad correlation between the grain size and TOC content indicated that the organic matter occurrence was neither controlled by the grain size nor the surface absorption of the fine particles, but it may has something to do with the complicated sedimentary hydrodynamic force, the input of organic matter and microbial action. Judging on the basis of C/N ratio and δ13CTOC, the organic carbon in sediments was a mixture of terrigenous and marine organic carbon, testifying to the land-sea interaction characteristic of the study area. The indexes experienced abrupt changes at about 6.5 ka BP, when the lighter terrigenous organic carbon made an increased proportion to the heavier marine organic carbon. The phenomenon reflected the enclosure of the lagoon and the reduced exchange interactions with the seawater of open seas.  相似文献   

7.
Aggregation of particulate organic matter (POM) and mineral grains may result in physical protection of organic matter (OM). To test this, phytoplankton cells of the dinoflagellate Scrippsiella trochoidea were inoculated with a natural bacterial assemblage and incubated with or without the clay montmorillonite. Within 5 h, aggregation of phytoplankton OM and clay resulted in transfer of the majority (∼80%) of OM into the >1.6 g cm−3 density fraction. Degradation of particulate organic carbon (POC), particulate nitrogen (PN), dissolved organic carbon (DOC), and dissolved and particulate total hydrolyzable amino acids (THAA), were modeled with a multi-G approach. Quantity of resistant OM was between two and four times larger during clay incubation relative to clay-free incubation. The two incubations did not exhibit significant differences in degradation state of particulate amino acids nor were there indications of preferential sorption of basic amino acids. The results suggest that a considerable fraction of phytoplankton OM can become resistant, at least on a timescale of weeks, mostly due to aggregation of POM and clay mineral grains.  相似文献   

8.
The estuarine mixing of dissolved Fe, Cu, Ni, Si and surface-active organic matter has been investigated in the Taieri Estuary, New Zealand, simultaneously with measurements of the electrokinetic charge on colloidal particles. Dissolved Fe showed almost quantitative removal from solution characteristic of the coagulation of iron-containing colloids by seawater electrolytes. Surface active organic matter behaved conservatively, indicating that a relatively constant fraction of estuarine organic matter is surface active, but that organic species associated with iron during removal are a minor fraction. Results for Cu, Ni and Si were scattered but offered no evidence for gross removal during estuarine mixing. The negative charge on suspended colloids was not reversed by adsorption of seawater cations, but remained uniformly negative throughout the salinity range, decreasing sharply in magnitude during the first few %. salinity.  相似文献   

9.
Complex biogeochemical studies including the determination of isotopic composition of Corg in both suspended particulate matter and surface horizon (0–1 cm) of sediments (more than 260 determinations of δ13C-Corg) were carried out for five Arctic shelf seas: White, Barents, Kara, East Siberian, and Chukchi. The aim of this study is to elucidate causes that change the isotopic composition of particulate organic carbon at the water-sediment boundary. It is shown that the isotopic composition of Corg in sediments from seas with a high river runoff (White, Kara, and East Siberian) does not inherit the isotopic composition of Corg in particles precipitating from the water column, but is enriched in heavy 13C. Seas with a low river runoff (Barents and Chukchi) show insignificant difference between the value of δ13C-Corg in both suspended load and sediment because of a low content of the isotopically light allochthonous organic matter (OM) in particulates. Complex biogeochemical studies with radioisotope tracers (14CO2, 35S, and 14CH4) revealed the existence of specific microbial filter formed from heterotrophic and autotrophic organisms at the water-sediment boundary. This filter prevents the mass influx of products of OM decomposition into water column, as well as reduces the influx of a part of OM contained in the suspended particulate matter from water into sediment.  相似文献   

10.
Allochthonous inputs of suspended particulate matter from freshwater environments to estuaries influence nutrient cycling and ecosystem metabolism. Contributions of different biogeochemical reactions to phosphorus dynamics in Tomales Bay, California, were determined by measuring dissolved inorganic phosphorus exchange between water and suspended particulate matter in response to changes in salinity, pH, and sediment redox. In serum bottle incubations of suspended particulate matter collected from the major tributary to the bay, dissolved inorganic phosphorus release increased with salinity during the initial 8 h; between 1–3 d, however, rates of release were similar among treatments of 0 psu, 16 psu, 24 psu, and 32 psu. Release was variable over the pH range 4–8.5, but dissolved inorganic phosphorus releases from sediments incubated for 24 h at the pH of fresh water (7.3) and seawater (8.1) were similarly small. Under oxidizing conditions, dissolved inorganic phosphorus release was small or dissolved inorganic phosphorus was taken up by particulate matter with total P content <50 μmoles P g?1; release was greater from suspended particulate matter with total phosphorus content >50 μmoles P g?1. In contrast, under reducing conditions maintained by addition of free sulfide (HS?), dissolved inorganic phosphorus was released from particles at all concentrations of total phosphorus in suspended particulate matter, presumably from the reduction of iron oxides. Since extrapolated dissolved inorganic phosphorus release from this abiotic source can account for only 12.5% of the total dissolved inorganic phosphorus flux from Tomales Bay sediments, we conclude most release from particles is due to organic matter oxidation that occurs after estuarine deposition. The abiotic, sedimentary flux of dissolved inorganic phosphorus, however, could contribute up to 30% of the observed net export of dissolved inorganic phosphorus from the entire estuary.  相似文献   

11.
It is shown that terrigenous apatite in soil, weathering crusts, and low peat bogs of humid zones is transformed into hydrogenous forms and solutions. In arid environments, apatite is transported to terminal discharge basins and transformed within diagenetic mud. Continental blocks are the main source of phosphorus in epicontinental and marginal seas. It originates from two sources (continents and seawater) in oceans. The role of biogenic factor in phosphorus geochemistry is significant, variable, and manifested at different stages of phoshogenesis.  相似文献   

12.
Two types of sedimentary basins are proposed: sedimentation basins and rock formation basins (rock basins). Such an approach reflects a complete cycle of the sedimentary process ranging from the stage of material mobilization and transport to the stage of accumulation of sediments, their transformation into sedimentary rocks, and formation of associated mineral deposits. Sedimentation basins are divided into lakes, intracontinental and marginal seas, and oceans, where phase differentiation of matter proceeds in different manners. It is shown that eupelagic and miopelagic clays, analogues of which are missing from Paleozoic sequences, represent the main indicator of recent sedimentation in the Word Ocean. It is stated that each sedimentation basin is characterized by a specific association of sedimentary mineral deposits.  相似文献   

13.
Over the past decade, sinking particulate organic matter (POM) samples from depth profiles in the equatorial Pacific have been analyzed by multiple techniques to evaluate the organic matter preservation mechanisms most dominant in the oceanic water column. How the samples were analyzed strongly influenced which organic matter preservation scheme appeared to dominate. Bulk functional group analysis by solid-state 13C-NMR showed that organic matter composition varied very little in light of the extreme degree of remineralization (>98%) that occurred with water column depth. This indicates preservation by a physical mechanism, such as sorption to mineral grains or protection within a mineral aggregate. However, detailed lipid studies of the characterizable fraction showed that selective preservation was important, with lipid structure being correlated with preservation over depth. However, the characterizable fraction decreases greatly with depth. Therefore, in this paper, direct temperature-resolved mass spectrometry (DT-MS), was used to further characterize POM, with the assumption that this approach could “see” a substantial proportion of the “uncharacterized” organic matter. DT-MS, which provides compositional information at an intermediate level between the detailed wet chemical studies and one-dimensional solid-state C13-NMR, also indicates an intermediate view between the mechanistic extremes of selective preservation and physical protection.  相似文献   

14.
Groundwater chemistry in a coastal region (Kunsan, Korea) having complex contaminant sources was investigated. Water analysis data for 197 groundwater samples collected from the uniformly distributed sixty-six wells were used. Chemical analysis results indicate that groundwaters show wide concentration ranges in major inorganic ions, reflecting complex hydrochemical processes. Due to the complexity of groundwater chemistry, the samples were classified into four groups based on Cl and NO3 concentrations and the processes controlling water chemistry were evaluated based on the reaction stoichiometry. The results explained the importance of mineral weathering, anthropogenic activities (nitrification and oxidation of organic matters), and Cl-salt inputs (seawater, deicer, NaCl, etc.) on groundwater chemistry. It was revealed that mineral dissolution is the major process controlling the water chemistry of the low Cl and NO3 group (Group 1). Groundwaters high in NO3 (Groups 2 and 4) are acidic in nature, and their chemistry is largely influenced by nitrification, oxidation of organic matters and mineral dissolution. In the case of chloride rich waters (Group 3), groundwater chemistry is highly influenced by mineral weathering and seawater intrusion associated with cation-exchange reactions.  相似文献   

15.
Water samples were collected for 23 different stations along a cross section profile of an estuary extending over to adjacent sea. The collected water samples were filtered and analyzed for major?Cminor ions and strontium isotope using the standard procedure to understand the geochemical behaviors of major and minor elements. The normalized values indicated that all riverine elements were entering to adjacent coastal sea with some significant variations at the estuary. The seawater dilution and regression lines explain about the overall patterns for seven elements. Removal processes were detected on calcium, magnesium, strontium and sulfate in the estuarine region. No significant mineral precipitation observed to release magnesium with respect to calcium. Minor variations of strontium and sulfate ions could be attributed to the presence of organic matter in the study area. Comparing seven elements with total suspended matters revealed that the total suspended matters played crucial role in either adsorption or absorption of all the elements in estuary before it reaches to coastal sea. Mixing patterns of strontium isotope showed minimal non-conservative with an evidence of active geochemical process in the estuary.  相似文献   

16.
The distribution of dissolved and particle-bound phosphorus (P) was investigated in the Elbe estuary during March 1995. The forms of particulate P were studied with a sequential extraction technique. Organic P dominated particle-bound P in the outer reaches of the estuary (52%), decreased to a minimum of 21% in the turbidity zone, and increased to 33% further upstream. Fe-bound P was the second most important P species in the outer reaches (27%) and dominated in the turbidity zone (up to 57%) and upstream of the turbidity zone (up to 48%). The P:Fe ratio increased with decreasing salinity, from 0.11 in the outer reaches to about 0.22 at zero salinity. Dissolved inorganic P release from reverine suspended matter was about two to three times larger than release, from marine suspended matter and was dominated by release of Fe-bound P. Dissolved inorganic P release from marine and from riverine organic matter were of equal importance. Because marine suspended matter dominates in the estuary, this suggests riverine organic matter is remineralized much faster than marine organic matter. This is in line with the refractory nature of marine organic matter (no phytoplankton bloom) and the easily degradable character of the riverine suspended matter (phytoplankton bloom) in the Elbe estuary during March 1995.  相似文献   

17.
天然气水合物与全球变化研究   总被引：24，自引：4，他引：24  
天然气水合物含碳量超过全球所有其他来源有机碳的总和,是地圈浅部的极重要碳库。自然界中温压条件的微小变化都会引起天然气水合物的形成或分解,从而吸收或释放甲烷,对全球碳循环和温室效应产生重要影响。天然气水合物对全球气候变化、冰期和间冰期的交替的反馈在极地和中低纬度不同,在中低纬度
也有两种相反的过程,因而对其总效应的方向和强度尚需详细研究和估计。我国许多海区有天然气水合物存在的条件,在南海已有报道;可通过地震剖面的重新判读及数值模拟估计天然气水合物的储藏量和它对海平面变化的反馈,以提供边缘海这类研究的范例。  相似文献   

18.
Long-chain alkyl diols contain an alkyl chain with alcohol groups at C1 and at the middle position of carbon chain, which exist widely in seas, rivers and lakes. It has been proven that these compounds are relatively resistant to degradation and have an extended occurrence in the geological record. In addition, they are relatively easy to identify. Therefore, long-chain alkyl diols can be used as potential biomarkers to trace the past change in paleoenvironment and paleoclimate. Although the sources of long-chain alkyl diols are still uncertain, the studies indicate that 1, 13 and 1, 15-diols are mainly produced by eustigmatophytes, while 14-diols are mainly from diatom Proboscia. So far, some proxies based on long-chain alkyl diols have been established to indicate the change in diatom productivity, upwelling intensity, salinity, sea surface temperature, riverine organic matter input and surface seawater nutrient concentration, which are significant for paleoenvironmental reconstruction. Current research and application of long-chain alkyl diols proxies were summarized, which would be helpful for further studying the source of long-chain alkyl diols and the application of relevant proxies in China’s marginal sea.  相似文献   

19.
In order to evaluate the shale microscopic pore characteristics more economically and effectively in limited circumstances, the pore characteristics of Longmaxi Formation in Pengshui area, Sichuan Basin, were qualitatively observed and analyzed with Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) with argon ion polishing method at the same time. Pore quantitative information were extracted from shale SEM and FESEM images with the help of a professional image analysis software IamgeJ2x, and combined with statistical methods, the whole pore size distribution as well as shale pore fractal dimension and the relevance between fractal dimension and organic matter content, mineral composition and pore adsorption capacity and the corresponding pore structure characteristics of Longmaxi Formation in Pengshui area were analyzed. The study shows that under SEM, there are mostly micro pores of Longmaxi Formation in Pengshui area. The main pore types include intergranular pore, clay mineral layer pore, intragranular pore and micro cracks, etc. Through argon ion polishing FESEM, there mainly develop nanoscale pores. The main pore types contain organic pore, inorganic mineral pore (pyrite intergranular pore, intragranular pore, clay mineral layer pore and intergranular pore, etc.) and micro cracks. The use of both of the two methords is more advantageous to qualitatively analyze shale pore. The whole pore size distribution of shale pore has four main peaks and the main distribution range is 3~10 nm, 10~40 nm, 100~400 nm, 1~4 μm, respectively. The shape factor of shale organic matter pore is distributed between 0.9~1 and inorganic mineral pore is distributed between 0.5~0.7. It shows that the organic matter pore is circular, nearly circular and inorganic mineral pore shape is triangle, polygon, slit shape and so on. The inorganic mineral pore shape is relativly complex because of the different pore causes. The shale pore of Longmaxi Formation in Pengshui area conforms to the fractal features, and the organic pore fractal dimension is smaller than that of inorganic mineral pore, showing that the organic matter pore structure is relatively simple. There is a certain relevance between fractal dimension and organic matter content, mineral composition, porosity, and adsorbed gas content. With the increase of the organic matter content, the shale pore fractal dimension increase, the pore structure characteristics become complicated. With the shale pore fractal dimension increasing, the biggest gas adsorption quantity increases and the ability of pore adsorption strengthens.  相似文献   

20.
长链烷基二醇类化合物(Long-chain alkyl diols)是指在碳链的1号位置和链中位置连接有羟基基团的类脂化合物,普遍存在于海洋、河流和湖泊环境中。由于这类化合物分布广泛、性质稳定不易降解、且检测手段较为简单,因此具有作为生物标志物的潜力,在生物地球化学领域引起了广泛的研究和关注。关于其生物来源尚未有定论,但是研究发现1,13-diols和1,15-diols可能主要来自真眼点藻,而14-diols主要来自硅藻Proboscia。目前根据长链烷基二醇建立的指标包括:硅藻生产力、上升流强度、盐度、温度、河流输入和表层海水营养盐浓度等,对古环境气候的重建有着重要的意义。归纳总结了目前长链烷基二醇指标的研究和应用进展,这有助于未来我国边缘海长链烷基二醇来源以及二醇指标的深入研究。  相似文献   

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