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1.
The extent and mechanisms of adsorption of marine pore water organic matter to montmorillonite were studied in a series of batch and sequential adsorption experiments. Pore water natural organic matter (pNOM) and easily extracted natural organic matter (eNOM) were collected from Liberty Bay (Puget Sound, WA, USA) sediments. The pNOM and eNOM were each divided into two size fractions using a 1000 D ultrafilter. Batch adsorption isotherms were approximately linear, and the >1000 D fractions of both pNOM and eNOM had larger partition coefficients (Kd) than the <1000 D fractions. A two-component fit of the sequential adsorption data indicated that pNOM and eNOM contained a similar amount of NOM (30%) that was not surface reactive toward montmorillonite. After correcting the batch adsorption Kds for the non-reactive components, the Kds estimated by batch and sequential adsorption were identical (2.7 l/kg for >1000 D pNOM and eNOM, and 1.6 l/kg for <1000 D pNOM and eNOM). Mechanisms of adsorption were investigated by systematically changing conditions (pH, temperature and ionic composition) of >1000 D fractions during batch isotherm experiments. Adsorption of NOM was found to decrease with increased temperature, suggesting that hydrophobic effects were not the dominant adsorption mechanisms in this system. Ion exchange was also not an important adsorption mechanism because adsorption increased with ionic strength. The observed enhancement in adsorption with ionic strength indicated that van der Waals interactions were important in the adsorption of NOM. Ligand exchange was found to be a significant mechanism since the presence of SO42− in solution reduced the amount of NOM adsorbed. Ca2+ enhanced adsorption slightly more than Na+, suggesting that cation bridging was involved. The relative contributions of van der Waals interactions, ligand exchange and cation bridging were estimated to be approximately 60%, 35% and 5%, respectively, for adsorption of NOM in a CaCl2 solution. 相似文献
2.
于１９８８年对云南星云湖盆地区进行调查，运用Ｘ射线衍射，差热分析，红外光谱分析和扫描电镜方法，对该盆地的第四系泥岩和现代沉积环境的泥质沉积物的４９个样品进行研究。发现，现代环境中粘土矿物分布规律明显，且与第四系沉积物有对比性，从而推断盆地沉积环境分布和演化与泥质沉积物的微量元素聚类分析结果相吻合。 相似文献
3.
The clay minerals in the 18 core samples collected from the northern, equatorial and southeastern Indian Ocean are illite, chlorite, montmorillonite and kaolinite. In the fraction finer than 2 in the surface layer (top to 5 cm deep) of each core, the relative abundance of clay minerals varies widely from area to area. Kaolinite possesses the maximum proportion of the clay mineral composition and chlorite has the minimum proportion.Kaolinite is particularly dominant in sediments near off the northwestern coast of Australia. In the factions finer and coarser than 2 of the surface layer, montmorillonite and kaolinite tend to be abundant in the fraction finer than 2, and chlorite and illite tend to be abundant in the fraction coarser than 2. In some cores, kaolinite-rich layers in sediments which are considered to have been transported by turbidity currents from the Bay of Bengal are found. Turbidity currents appear partly a role in transport of sediments to the equatorial Indian Ocean.As to the relation between the vertical change of clay mineral composition and geochronological data, montmorillonite and kaolinite tend to be more abundant in interglacial ages than in glacial ages, while illite and chlorite tend to exhibit opposite trend.Muscovite and biotite highly concentrated in the cores Ka-9 and Ka-15 collected from the equatorial Indian Ocean seem to originate from granite or gneiss of Ceylon and/or India. 相似文献
4.
The extent and kinetics of Np(V)O2+ adsorption from dilute aqueous solutions and seawater onto a variety of synthetic and natural solids were determined at 25°C and 1 atm total pressure. Extensive and complex adsorption reactions were found, contrary to speculations in the literature that NpO2+ should behave as a simple monovalent ion with a low affinity for surfaces. When normalized to adsorption per unit solid surface area, the ranking for the synthetic solids was aragonite ? calcite > goethite ? MnO2 ≈ clays. Natural materials generally followed the same behavior patterns as their synthetic counterparts. The dissolved/adsorbed ratio was found to be constant over a wide range (10?13–10?7M) of NpO2+ concentrations. At higher concentrations the extent of adsorption decreased until a solubility limit was reached at approximately 10?5 M.Solution composition had the most significant influence for NpO2+ adsorption on goethite, where much more extensive adsorption occurs in dilute solutions than in seawater. When seawater is added to a dilute solution, extensive desorption of NpO2+ from goethite occurs. Tests conducted on NpO2+ adsorbed on carbonates indicated that it remained in the V oxidation state.There is a growing consensus that Pu dissolved in natural waters also occurs dominantly in the V oxidation state as PuO2+ ion. Consequently, these results for NpO2+ may serve as a guide for Pu behavior when also in the V oxidation state. The fact that most adsorbed Pu is found in the III or IV oxidation states indicates that reduction of Pu may occur subsequent to adsorption in the V oxidation state. 相似文献
5.
The results of a 57Fe Mössbauer spectroscopic and X-ray diffraction study of four pelagic clay sediments from the Southwestern Pacific Basin collected at increasing distances from New Zealand, on a New Zealand—Rarotonga transect, are presented. These show that, with increasing distance from New Zealand, the Fe3+/Fe2+ ratio of the sediment increases as a result of the increasing contribution of the X-ray amorphous secondary hydrous iron oxides, notably ferrihydrite, due to the longer sedimentation periods and consequent greater degree of oxidation of the sediments. This increase in the Fe3+/Fe2+ ratio is correlated with the change in colour of the sediments from pale yellowish to dusky brown, as well as a number of other sediment parameters. Apart from a slight increase in the relative abundance of montmorillonite with increasing distance from New Zealand, the abundances of the other clay minerals, illite and kaolinite, and of chlorite in the sediments are approximately equal. Quartz and feldspar with minor augite are the dominant detrital minerals. Calcite is present in minor amounts in some of the sediments. 相似文献
6.
《Marine Chemistry》2001,74(4):227-243
The distribution of trace metals in sediments and their exchange between sediments and overlying water is governed by multiple processes including molecular diffusion, bioturbation (porewater advection, porewater mixing, and particle mixing), chemical reactions and adsorption–desorption. To understand these processes and their relative contributions, a one-dimensional model was built, which includes bioturbation and adsorption–desorption processes, to describe the transport of 224Ra. Because 224Ra is adsorbed on MnO2, 224Ra may serve as a proxy for trace metal transport. Three sites were sampled and both dissolved and adsorbed 224Ra were analyzed and modeled to understand the transport and exchange processes. It was found that particle transport of adsorbed 224Ra followed by desorption at the sediment/water interface typically represents the dominant flux. We have further been able to define conditions where the porewater transport for adsorption reactive metals like 224Ra (and other metals) may be out of the sediments whereas the active scavenging of 224Ra from the water column at the sediment water interface via adsorption reactions can result in a flux of 224Ra into the sediment. These processes are both predicted by the model and observed in sediment samples. 相似文献
7.
Saburo Aoki 《Journal of Oceanography》1976,32(4):169-174
The 25 sediment samples collected from the Gulf of Thailand and the South China Sea were analyzed for clay mineral investigation. Results showed the presence of 35% montmorillonite, 13% chlorite, 30% illite, and 22% kaolinite in sediments of the Gulf and also 16% montmorillonite, 21% chlorite, 41% illite, and 22% kaolinite in sediments of the South China Sea. The relatively high concentration of montmorillonite in sediments of the Gulf as compared with that in sediments of the South China Sea may suggest that montmorillonite in these area has been largely derived from soil formation of the bordering land areas of the Gulf, particularly from the northern part of Malay Peninsula. On the contrary, the content of illite in sediments of the South China Sea is higher than that in the Gulf. This mineral appears to have been supplied from Borneo as well as the Mekong Delta. However, chlorite which shows a similar distribution to that of illite in sediments of the Gulf and the South China Sea has not indicated Borneo Isl. as a principal source area for chlorite. Greater resemblance in amount of kaolinite in both sediments of the Gulf and the South China Sea is due to the prevailing distribution of kaolinite as low latitude clay mineral on the bordering land areas. The distribution of clay minerals in sediments of the study area appears to be closely related to the soil formation and geology of the adjacent land areas.This work was carried out at Geological and Mineralogical Institute, Tokyo University of Education. 相似文献
8.
The distribution of trace metals in sediments and their exchange between sediments and overlying water is governed by multiple processes including molecular diffusion, bioturbation (porewater advection, porewater mixing, and particle mixing), chemical reactions and adsorption–desorption. To understand these processes and their relative contributions, a one-dimensional model was built, which includes bioturbation and adsorption–desorption processes, to describe the transport of 224Ra. Because 224Ra is adsorbed on MnO2, 224Ra may serve as a proxy for trace metal transport. Three sites were sampled and both dissolved and adsorbed 224Ra were analyzed and modeled to understand the transport and exchange processes. It was found that particle transport of adsorbed 224Ra followed by desorption at the sediment/water interface typically represents the dominant flux. We have further been able to define conditions where the porewater transport for adsorption reactive metals like 224Ra (and other metals) may be out of the sediments whereas the active scavenging of 224Ra from the water column at the sediment water interface via adsorption reactions can result in a flux of 224Ra into the sediment. These processes are both predicted by the model and observed in sediment samples. 相似文献
9.
海水中酚类有机物在粘土或沉积物上吸附特性的模拟研究 总被引：9，自引：0，他引：9
研究了海水中７种酚类有机污染物在粘土矿物及海洋沉积物上的吸附特征;发现了酚在粘土或沉积物上的吸附平衡常数与其水溶解度之间的线性自由能关系,。 相似文献
10.
High quartz and low calcium carbonate percentages in the surface sediments of the Bay of Bengal adjacent to the Indian subcontinent result from the massive influx of terrigenous clastics. Fine-fraction (<2 ) mineralogy and heavy minerals in (turbidite) sands suggest that sediments of the western Bengal Fan (high in smectite, sillimanite, garnet) have been derived from peninsular Indian rivers; sediments of the rest of the fan (high in illite, hornblende, epidote) are derived from Himalayan rivers. The sediments on the Ninety East Ridge and in the deep southerly areas beyond the reach of fan deposition result from thein situ alteration of volcanics. 相似文献
11.
J. N. Smith K. M. Ellis K. Naes S. Dahle D. Matishov 《Deep Sea Research Part II: Topical Studies in Oceanography》1995,42(6)
Radionuclide measurements have been conducted on sediment cores collected in 1992 in the south-eastern region of the Barents Sea, known as the Pechora Sea. Cesium-137 and 239,24OPu activities in surface sediments are generally less than 30 Bq/kg, with the highest levels being measured in sediments off the southwestern coastline of the island of Novaya Zemlya. High correlations between both 137Cs and 239,24OPu and the concentration of fine (< 63 μm) particles in surface sediments indicate that much of the variance in radionuclide concentrations throughout the Pechora Sea can be explained by particle size fractionation. However, elevated activities of 137Cs (138 Bq/kg), 60Co (92 Bq/kg), 241Am (433 Bq/kg), and especially 239,24OPu (8.47 × 103 Bq/kg) were measured in one surface sediment sample from the fjord of Chernaya Bay on the southern coast of Novaya Zemlya. The source of radioactive contamination is two underwater nuclear tests conducted in Chernaya Bay in 1955 and 1957.The 238Pu/239,240Vu activity ratio of 0.0245 in Chernaya Bay is equivalent to values measured in global fallout. The 240Pu/239Pu atom ratio (0.0304), measured by mass spectrometry, is much lower than values (0.18) typical of global fallout, but is consistent with ratios measured for fallout from the early (1951–1955) series of weapons tests at the Nevada Test Site. The timing of the Chernaya Bay source term, estimated from the 241Am/241Pu ratio, is consistent with the timing of the 1955 and 1957 underwater nuclear tests. Relatively low initial yields of 241Pu (241Pu/239Pu atom RATIO = 0.00 123) in these tests have resulted in relatively low 241Am/239,240Pu activity ratios (0.05) in recent sediments in Chernaya Bay.Radionuclide tracer profiles in cores from the Pechora Sea can be simulated using a two-layer biodiffusion model with rapid, near-homogeneous mixing in the surface mixed layer and reduced mixing in the deep layer. Lead-210 profiles are consistent with a wide range of sedimentation and mixing rates in the deep sediment layer. However, the 137Cs and 239,240Pu results further constrain the model parameters and indicate that the downward transport of radionuclides in the sediments is governed primarily by sediment mixing, with sediment burial playing a secondary role. 相似文献
12.
Further studies on the transport in sea water and accumulation in marine sediment of the radionuclides, released from a nuclear power plant, on Urazoko Bay, Fukui Prefecture were reported.The partition of radionuclides among the particle size fractions of a sediment sample indicated that the accumulation of60Co,137Cs and54Mn in the sediment were dominated substantially by the sorption on the particle surface in sea water, and the patterns of their sorption were considerably similar to each other.In regard to the60Co contamination of marine sediments in an area of about 13 km2 around the nuclear power plant, 60% of the60Co contamination were retained in Urazoko Bay, which occupies only 7% of the bottom surface of the region.It is clear that a part of60Co accumulated in the sediment of Urazoko Bay gradually moved to the outerward. 相似文献
13.
Selenium in sediments, pore waters and benthic infauna of Lake Macquarie, New South Wales, Australia 总被引：1，自引：0，他引：1
G. M. Peters W. A. Maher F. Krikowa A. C. Roach H. K. Jeswani J. P. Barford V. G. Gomes D. D. Reible 《Marine environmental research》1999,47(5):2518
Measurements of selenium in sediments and benthic infauna of Lake Macquarie, an estuary on the east coast of Australia, indicate that sediments are a significant source of selenium in the lake's food web. Analysis of surficial sediment samples indicated higher selenium concentrations near what are believed to be the main industrial sources of selenium to the lake: a smelter and a power station. Sediment cores taken from sediments in Mannering Bay, near a power station at Vales Point, contained an average of 12 times more selenium in surficial sections than sediment cores from Nord's Wharf, a part of the lake remote from direct inputs of selenium. The highest selenium concentration found in Mannering Bay sediments (17.2 μg/g) was 69 times the apparent background concentration at Nord's Wharf (0.25 μg/g). Pore water concentrations in Mannering Bay were also high, up to 5 μg/l compared to those at Nord's Wharf which were below detection limits (0.2 μg/l). Selenium concentrations in muscle tissues of three benthic-feeding fish species (Mugil cephalus, Platycephalus fuscus, Acanthopagrus australis) were significantly correlated (p<0.05) with surficial sediment selenium concentration. Selenium concentrations in polychaetes and molluscs of Mannering Bay were up to 58 times higher than those from Nord's Wharf. Two benthic organisms, the eunicid polychaete Marphysa sanguinea and the bivalve mollusc Spisula trigonella, were maintained at different densities in selenium-spiked sediments. Both animals accumulated selenium from the spiked sediment, confirming that bioaccumulation from contaminated sediments occurs. Collectively, these data suggest that benthic food webs are important sources of selenium to the fish of Lake Macquarie. 相似文献
14.
Akira Kurata 《Journal of Oceanography》1974,30(4):199-202
Cobalt contained in the sediments from Maizuru Bay and Wakasa Bay was determined by the atomic absorption method. Cobalt content in the surface layer of the bottom sediments averaged 15.2 and 6.7g/g dry matter in Maizuru Bay and in Wakasa Bay, respectively. The vertical distribution of cobalt was almost uniform in the column of bottom sediments. Geographically, the cobalt content in sediments tended to be inverse proportion to the distance from the coast in Wakasa Bay. Considering the distribution of cobalt, it is reasonably concluded that cobalt is not a limiting factor to the production of vitamin B12 by microorganisms in these regions. 相似文献
15.
Stress proteins (heat shock proteins, hsps) form part of the cellular protein repair system, and are induced by a wide variety of Stressors. To determine their suitability as tools for assessing sublethal sediment toxicity, we measured levels of members of the stress protein families hsp60 and hsp70 in benthic estuarine amphipods (Ampelisca abdita) exposed to sediments from 23 different sampling sites in San Francisco Bay for 10 d. Concentrations of sediment-associated xenobiotics were determined. Per cent survival was recorded and surviving animals were analysed for stress proteins using western blotting techniques. An inverse correlation (r2 = 0.44) was seen between amphipod survival and hsp64 levels, and hsp64 levels were positively correlated with concentrations of total polycyclic aromatic hydrocarbons (PAHs) (r2 = 0.5). Principal component analysis revealed that amphipod mortality was linked to a combination of several PAHs (phenanthrene, fluoranthene, pyrene, benzo(a)pyrene) and di-n-butylphthalate at southern San Francisco Bay sites. At northern San Francisco Bay sites, negative correlations were found between hsp64 levels and organotin compounds (MBT, DBT, TBT), and between hsp71 levels and the PAHs, benzo (b,k)fluoranthene and benzo(G,H,I)perylene, suggesting an inhibitory effect of these compounds on stress protein expression. 相似文献
16.
In this study, 32 experimental measurements on the isothermal adsorption of methane for 18 shale samples from China's three largest continental oil basins—Songliao, Bohai Bay, and Ordos basins—were used to construct comprehensive polynomial simulation and prediction models for Langmuir volume and Langmuir pressure. The models were based on shale properties (total organic carbon (TOC) content, amount of residual hydrocarbon S1, and mineral composition of rocks) and adsorption condition (temperature) using a weighted sum of multiple variables. The influences of various factors were quantitatively characterized, and the prediction accuracy was verified. Langmuir volume is mainly affected by temperature, shale TOC content, amount of residual hydrocarbon, and clay mineral content; Langmuir pressure is mainly affected by clay, carbonate, feldspar and illite content (because shale pore size can be affected by shale mineral composition). Based on the resource potential and the producibility of shale gas, the area suitable for shale gas exploration and development should have high abundance of organic matter (TOC and residual hydrocarbon S1), low clay mineral content and feldspar content, high conversion rate of montmorillonite to illite (strong diagenesis), and high carbonate content. The comprehensive polynomial prediction model can effectively simulate and predict Langmuir volume and Langmuir pressure, thereby reducing the amount of work necessary for evaluation of shale gas resource potential and economic feasibility. 相似文献
17.
为了研究海洋沉积物对0#柴油配制的石油溶液的吸附解吸规律,采集了厦门湾15个站点的沉积物作为研究对象,分析了沉积物的主要理化特征之后,在实验室条件下,以SS5号站点沉积物为代表,模拟沉积物对石油的吸附-解吸过程,测定了沉积物对石油吸附、解吸的动力学曲线和吸附等温线.研究结果表明：沉积物对石油的吸附的平衡时间为0.76 h,解吸的平衡时间为7.8 h,沉积物对石油的吸附速率高于解吸速率,并且石油被沉积物吸附以后不会完全解吸出来.沉积物对石油的吸附等温线具有线性规律,接近理想吸附.研究还表明：沉积物对石油的吸附量与石油的浓度,沉积物粒径等因素有关. 相似文献
18.
沉积物中磷的存在形态及其生物可利用性研究 总被引：12，自引：0，他引：12
用MgCl2,NaOH和HCl对大亚湾的大鹏澳、南海的珠江口、厦门湾的胡里山沉积物进行了逐级提取和总磷分析,并以这3种沉积物为惟一磷源培养小球藻和球等鞭金藻,估算了藻类对沉积物中磷的可利用量.结果表明,3种沉积物总磷含量分别为449.3,650.1和643.9mg/kg;MgCl2和NaOH提取的生物可利用的非磷灰石无机磷分别为168.8,146.6和118.1mg/kg.非磷灰石无机磷占总磷的18.3%～32.6%.3种提取剂对3种沉积物提取的磷是HCl提取相最大,NaOH提取相次之,MgCl2提取相最小.小球藻和球等鞭金藻在3种沉积物中的最大相对生长率为4.3%～26.9%,两种藻在3种沉积物中的生长与非磷灰石无机磷和藻类可利用的颗粒磷量相对应.颗粒磷占非磷灰石无机磷的42.4%～78.2%,占沉积物中总无机磷的21.1%～27.1%,占总磷的11.8%～20.3%. 相似文献
19.
226Ra and 228Ra have non-conservative excess concentrations in the mixing zones of the Pee Dee River-Winyah Bay estuary, the Yangtze River estuary, and the Delaware Bay estuary. Laboratory experiments, using Pee Dee River sediment, indicate desorption of 226Ra to increase with increasing salinities up to 20‰. In Winyah Bay desorption from river-borne sediments could contribute almost all of the increases for both isotopes. Desorption adds only a portion of the excess 228Ra measured in the Yangtse River and adjacent Shelf waters and Delaware Bay. In the Yangtze River the mixing zone extends over a considerable portion of the Continental Shelf where 228Ra is added to the water column by diffusion from bottom sediments, while 226Ra concentrations decrease from dilution. Diffusion of 228Ra from bottom sediments in Delaware Bay primarily occurs in the upper part of the bay (< 22‰ water) where fine grained sediments predominate. A diffusive flux for 228Ra of 0·33 dpm cm?2 year was determined for Delaware Bay. 相似文献
20.
226Ra and 228Ra have non-conservative excess concentrations in the mixing zones of the Pee Dee River-Winyah Bay estuary, the Yangtze River estuary, and the Delaware Bay estuary. Laboratory experiments, using Pee Dee River sediment, indicate desorption of 226Ra to increase with increasing salinities up to 20‰. In Winyah Bay desorption from river-borne sediments could contribute almost all of the increases for both isotopes. Desorption adds only a portion of the excess 228Ra measured in the Yangtse River and adjacent Shelf waters and Delaware Bay. In the Yangtze River the mixing zone extends over a considerable portion of the Continental Shelf where 228Ra is added to the water column by diffusion from bottom sediments, while 226Ra concentrations decrease from dilution. Diffusion of 228Ra from bottom sediments in Delaware Bay primarily occurs in the upper part of the bay (< 22‰ water) where fine grained sediments predominate. A diffusive flux for 228Ra of 0·33 dpm cm−2 year was determined for Delaware Bay. 相似文献