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It is generally accepted that seawaters near the ocean surface are supersaturated with calcite and that increasing atmospheric CO2 will not overcome this condition until late in the 21st century. These expectations are based on comparisons of the ion activity products (IAPs) of various seawaters to the solubility product (K) of seawater saturated with pure calcite at 1 atm and a given temperature. It has been shown in recent papers, however, that calcites in contact with natural seawater in the surface oceans are not pure, but are magnesian calcite compositions. As a result, the presently accepted values of the solubility product of calcite in seawater cannot be used to obtain a correct, or even a reasonable estimate of the saturation state of sea water relative to either pure or magnesian calcite. Data are presented demonstrating that use of the currently accepted solubility product of calcite in seawater to determine seawater's relative calcite saturation leads to gross overestimates of its extent. 相似文献
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TENG Jiwen LI Songying JIA Mingkui LIAN Jie LIU Honglei LIU Guodong WANG Wei Volker SCH?PE FENG Lei YAO Xiaoshuai WANG Kang YAN Yafen ZHANG Wanpeng 《《地质学报》英文版》2020,94(1):10-26
In order to effectively detect potential geology anomalous bodies in coal bearing formation, such as coal seam thickness variation, small faults, goafs and collapse columns, and provide scientific guidance for safe and efficient mining, the SUMMIT-II EX explosion-proof seismic slot wave instrument, produced by German DMT Company, was used to detect the underground channel wave with the help of transmission method, reflection method and transflective method. Region area detection experiment in mining face had been carried out thanks to the advantage of channel wave, such as its great dispersion, abundant geology information, strong anti-interference ability and long-distance detecting. The experimental results showed that: (1) Coal seam thickness variation in extremely unstable coal seam has been quantitatively interpreted with an accuracy of more than 80% generally; (2) The faults, goafs and collapse columns could be detected and predicted accurately; (3) Experimental detection of gas enrichment areas, stress concentration regions and water inrush risk zone has been collated; (4) A research system of disaster-causing geology anomalous body detection by in-seam seismic survey has been built, valuable and innovative achievements have been got. Series of innovation obtained for the first time in this study indicated that it was more effective to detect disaster-causing potential geology anomalies by in-seam seismic survey than by ground seismic survey. It had significant scientific value and application prospect under complex coal seam conditions. 相似文献
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The apparent solubility product (K'sp) of aragonite in a variety of seawater compositions has been determined at pressures from 0 to 1019 atm and a nomogram developed to allow the determination of the K'sp when the apparent ion product (AIP) at one atmosphere and the collection depth of a water sample are known.This nomogram provides a basis from which the onset of aragonite dissolution can be determined for conditions representative of aragonite sedimentation through the changing water masses of the open ocean. 相似文献
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A dialysis technique has been developed from which whole sediment diffusion coefficients that include the effect of microbially-mediated reactions can be determined in situ. Application of the technique shows that the diffusion of both dissolved sulphate and total dissolved CO2 (transported primarily as bicarbonate) is related to the changing porosity of a fine-grained marine sediment. Added to this, the transport of dissolved sulphate is significantly affected by the microbial reduction of the pool available for diffusion. In contrast, the diffusion of a far larger pool of total dissolved CO2 is not noticeably affected by microbial activity. 相似文献
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Marija PE?I? Sla?ana POPOVI? Vesna MILUTINOVI? Gordana SUBAKOV SIMI? Ivana TRBOJEVI? Dragana PREDOJEVI? 《海洋湖沼学报(英文)》2021,(3):928-945
Phosphorus overenrichment of shallow ponds prevailing in wetlands leads to their eutrophication causing the collapse of those vulnerable habitats. The potential... 相似文献
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Weather manifests in spatiotemporally coherent structures. Weather forecasts hence are affected by both positional and structural or amplitude errors. This has been long recognized by practicing forecasters(cf., e.g.,Tropical Cyclone track and intensity errors). Despite the emergence in recent decades of various objective methods for the diagnosis of positional forecast errors, most routine verification or statistical post-processing methods implicitly assume that forecasts have no positional error.The Forecast Error Decomposition(FED) method proposed in this study uses the Field Alignment technique which aligns a gridded forecast with its verifying analysis field. The total error is then partitioned into three orthogonal components:(a) large scale positional,(b) large scale structural, and(c) small scale error variance.The use of FED is demonstrated over a month-long MSLP data set. As expected, positional errors are often characterized by dipole patterns related to the displacement of features, while structural errors appear with single extrema, indicative of magnitude problems. The most important result of this study is that over the test period, more than 50% of the total mean sea level pressure forecast error variance is associated with large scale positional error. The importance of positional error in forecasts of other variables and over different time periods remain to be explored. 相似文献
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Benham Rise is a large igneous province that has been accreted to the eastern seaboard of northern Lu-zon since Early Miocene. It started forming during the Eocene at a hotspot/mantle plume in the vicinity of the Central basin Spreading Center in the West Philippine Basin (CBSC) of the Philippine Sea Plate. Seafloor spreading from the CBSC and Parece Vela pushed Benham Rise towards Luzon. Eventually Benham Rise jammed against Luzon at the end of the Oligocene, with consequences that impacted on the geology of the Philippines which have been similarly noted in colli-sions of large igneous provinces in other areas. These are manifested as follows: 相似文献
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An in-situ dialysis technique has been developed to examine chemical and bacterial rates of manganese binding and oxidation under diffusion-limited conditions in sediments. With this method, the microbial and abiotic components of manganese binding were delineated quantitatively in laboratory sediments spiked with manganese oxidizing bacteria. The abiotic removal of manganese by the same sediments has also been determined independently to define the relative importance of adsorption, ion exchange and autocatalytic oxidation in the removal of Mn2+ from solution. Independent measurements of both bacterial and abiotic manganese binding were in good agreement with the diffusion-controlled rate data, validating the use of this dialysis technique as a means of examining manganese oxidation in-situ. 相似文献