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A colorimetric method for the determination of phosphorus in batches of geochemical survey samples is described. The powdered material is digested with a nitric-perchloric acid mixture, excess of acid is evaporated off and the residue is leached with water. Aliquots of the leachate are treated with vanadomolybdate reagent and the yellow phosphorus complex is extracted into isobutyl methyl ketone. The colour in the organic phase, which is stable for many days, is matched against a series of similarly prepared standards. Iron, other coloured ions, and titanium do not interfere. Standard deviations of ±0.02% about a mean value of 0.20% P2 O5 and ±0.4% about a mean of 11.6% P2 O5 were obtained. At least 40 powdered samples may be analysed per working day per person. 相似文献
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Green-lipped mussels (Perna canaliculus) formed extensive reefs on soft sediments in sheltered embayments around northern New Zealand until overfishing and/or increased sediment input caused their virtual disappearance by 1980. To determine the role of mussel reefs as habitat for other animals, we located remnant soft-sediment reefs in five locations and compared the density, biomass, productivity and composition of mobile macroinvertebrate communities, and the density of small fishes associated with mussels, with fauna in the surrounding soft sediments. The mussel reefs had a distinct assemblage of macroinvertebrates, which had 3.5 times the density, 3.4 times the biomass and 3.5 times the productivity of surrounding areas. The density of small fishes was 13.7 times higher than in surrounding areas. These results show that soft-sediment mussel reefs support an abundant and productive fauna, highlighting the probable large loss of productivity associated with the historical decline in mussel habitat and the consequent desirability of restoration efforts. 相似文献
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Prediction of hydrocarbon recovery from turbidite sandstones with linked-debrite facies: Numerical flow-simulation studies 总被引：1，自引：1，他引：0
Lawrence A. Amy Simon A. Peachey Andy A. Gardiner Peter J. Talling 《Marine and Petroleum Geology》2009,26(10):2032
A series of two-dimensional numerical flow simulations were carried out to investigate the production characteristics of a sheet sandstone bed with a linked-debrite interval. A deterministic geological model was used based on a two-dimensional representation of a bed from the Marnoso Arenacea Formation. The model was 60 km long and 1 m thick and contained three zones, arranged in a vertical facies arrangement typical of many linked-debrite beds: i) a lower, coarse-to-medium grained, clean turbidite sandstone interval; ii) a middle, muddy sandstone, debrite interval; iii) an upper, fine-grained, clean, laminated sandstone interval. Simulation involved only a 3-km long sector of the model, with one injector well and one production well, placed 1-km apart in the middle of the sector model. The simulated sector was moved progressively down the length of the bed, in 1-km steps, sampling different parts of the bed with different facies proportions. The petrophysical properties of the debrite interval were varied to produce different porosity–permeability cases. All other modelling parameters, including the upper and lower interval petrophysics, were kept constant. Results indicate that, in most cases, key production parameters such as cumulative oil production with time and water cut are proportional to the volume of movable oil between the wells. This relationship does not hold, however, for cases with relatively low values of debrite porosity (≤0.15) and permeability (kh ≤ 100 mD) where the debrite interval accounts for more than 20% of the interwell volume. In these models, production efficiency declines systematically with reducing reservoir quality and increasing debrite percentage, resulting in relatively low oil production and early water breakthrough. 相似文献
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内蒙古鸡冠山斑岩钼矿床成矿时代和成矿流体研究 总被引：19，自引：6，他引：13
内蒙古鸡冠山钼矿床是西拉沐伦钼成矿带上的典型斑岩矿床。矿床产于火山侵入杂岩中,矿化类型以细脉浸染状矿化为主。对矿床5件辉钼矿样品进行了铼-锇同位素分析,获得了151.1±1.3Ma的等时线年龄,表明成矿作用发生在晚侏罗世。成矿作用可划分为三个阶段:早阶段为石英-黄铁矿阶段,发育乳白色石英和粗粒浸染状黄铁矿;中阶段包括早期石英-多金属硫化物亚阶段和晚期石英-萤石-金属硫化物亚阶段;晚阶段为石英-碳酸盐细脉,穿切早、中阶段脉体和矿物组合。鸡冠山钼矿床流体包裹体岩相学研究表明,与成矿有关的包裹体主要有六种类型:富液相、富气相、含子晶多相、含CO2三相、纯CO2及纯液相包裹体。其中,早阶段以富气和富CO2包裹体为主,中阶段多种包裹体共存,晚阶段则主要为富液包裹体。冷热台显微测温和激光拉曼显微探针(LRM)成分分析结果表明,早阶段石英中原生包裹体的均一温度480℃,盐度最高66.75%NaCleqv,包裹体气相成分富含水和CO2,液相成分则以水为主,子晶矿物有石盐、黄铜矿以及指示氧化条件的赤铁矿等,同时也说明成矿流体是富含成矿金属元素的。中阶段早期石英中的流体包裹体均一温度为320～480℃,晚期石英和萤石中的流体包裹体的均一温度为180～320℃。中阶段流体盐度介于4.65%～56.76%NaCleqv。中阶段包裹体含石盐、方解石、黄铜矿、赤铁矿等子矿物,富气相、富液相与含子晶多相包裹体共存,且具有相近的均一温度,而盐度相差悬殊,指示流体发生了沸腾。晚阶段流体的温度降低至100～180℃,盐度则低于10.86%NaCleqv,流体包裹体成分主要为水。鸡冠山钼矿成矿流体演化从早至晚为:从早阶段高温、高盐度、高氧逸度、富CO2、富成矿物质以岩浆热液为主成矿流体,演化至晚期低温、低盐度、无子晶、贫CO2、以大气降水为主的流体。沸腾作用是鸡冠山钼矿形成的重要机制。 相似文献
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D. Peachey 《Journal of Geochemical Exploration》1976,5(1-2)
Soil samples collected in the course of geochemical surveys for a variety of purposes are frequently analyzed for trace metals by atomic absorption spectrophotometry following sample dissolution with a mixture of HNO3 and HClO4.If samples are ignited prior to dissolution low values for Cu may be obtained. This is attributed to dehydration of secondary iron oxide phases and consequent change in bonding of Cu. This problem is overcome by treating ignited samples with HCl prior to digestion with HNO3 and HClO4. 相似文献
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A Payo-Payo A Sanz-Aguilar D Gaglio RB Sherley TR Cook R Altwegg 《African Journal of Marine Science》2018,40(1):43-50
The nominate race of the greater crested tern Thalasseus bergii breeds only along the coast of the Benguela region (west coast) of southern Africa, where its population is increasing, in contrast to other species of breeding seabirds in the region which similarly depend on forage fish. Although this population’s trends are well known, its demographic parameters remain obscure. We used multi-event capture–recapture–recovery modelling to provide the first estimates of survival. The survival rate of birds older than two years was 0.93 (0.91–0.95); second-year survival was 0.93 (0.90–0.95) and first-year survival was 0.80 (0.73–0.85). A resighting of a 34-year-old bird is a new longevity record for the species. Population growth rates projected with a Leslie matrix model that included our survival estimates were very similar to estimates from annual counts of the breeding population (7–8% y?1), suggesting that these survival estimates adequately describe the species’ demography. High survival rates have likely contributed to the species’ recent population increase in the region. 相似文献
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A study of radiosonde observations for temperature at 850 hPa over Delhi for a period of 35 years was conducted. The influence of atmospheric oscillations and geophysical events like El Niño‐Southern Oscillation (ENSO) on tropospheric temperature variability showed indicative trends for changing urban climate in Delhi. The inter‐annual variation in surface temperature and its relationship with land use changes and land cover changes (LULCC) was also examined. LULCC and urban expansion into peripheral areas of Delhi (towards the West, North, North‐West and South) at the cost of agricultural and wasteland was found to be extensive. The upper range of the surface temperature has shifted by ~6°C. The post‐monsoon and winter months from November to February have experienced a considerable increase in the average temperature in the period examined. The monsoon months from June to September have undergone cooling of ~0.5°C–1°C at 850 hPa. An inverse relationship exists between the Southern Oscillation Index (SOI) and the monthly averaged temperature. The temperature of the atmosphere over Delhi at 850 hPa has increased only marginally (~ 0.3°C) for the time period 1980–2015. Bi‐modal peaks were the most peculiar features observed in mean monthly temperature variation during 2000–2009. 相似文献
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A leaching technique was investigated for the dissolution of sulphide and other mineral phases in geochemical exploration samples. Samples were leached with a mixture of H2O1 and ascorbic acid at room temperature and the insoluble residues were leached a second time with a warm solution of ammonium acetate. Sample solutions were analysed by atomic absorption spectrophotometry. Results obtained provide useful information for assessing the significance of anomalous geochemical exploration data. 相似文献
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Peachey RB 《Marine pollution bulletin》2003,46(11):1365-1371
A review of the levels of polycyclic aromatic hydrocarbons (PAH) and tributyltin (TBT) in sediments from Mobile Bay, Alabama, shows that overall levels of PAH decrease from the upper bay (RI) to the lower bay (RIV). Analysis of PAH ratios indicate that pyrogenic sources such as fossil fuel combustion are dominant. There are so few data on TBT in sediments that spatial trends cannot be identified.Levels of PAHs in oyster tissues decrease from the upper bay (RI) to the lower bay (RIII). Although there is no significant temporal trend for PAH levels in bivalves for the US; in the bay, levels in Region II (RII) have decreased significantly and are currently below the national median. There is no trend in Region III (RIII), where levels remain below RII and the national median. RI and RIV had too few data for trend analysis.Mean levels of TBT in oyster tissues decrease from the upper bay (RI) to the lower bay (RIII). Temporal trend analysis indicates a significant decreasing trend for TBT in the US but no significant trend was detected for RII and RIII in Mobile Bay. TBT levels in RII are consistently higher than levels in the US and RIII, which are similar. Data from RI are too limited for analysis and there are no data for RIV. 相似文献
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