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991.
The paper explores application of the engineered increase in soil permeability, achieved using reaction of guanidinium solutions with smectite soils, to geotechnical problems. The comparison between the finite element analysis of the enhanced permeability model for axisymmetric conditions and a simplified analytical solution demonstrates the importance of accounting for diffusive and dispersive fluxes. In order to illustrate possible practical application of the proposed soil improvement technique, two geotechnical examples have been numerically explored: improving performance of a ground water well and the stabilization of a slope by chemically enhanced drainage. For the well application, it has been demonstrated that for a relatively small degree of treatment, the power consumption can be reduced to a half, compared with the non‐treated soil. For the slope stability application, the water table downstream of the drain can be significantly lowered using moderate pump/collector pressures at the centre of the drain, causing a higher increase in the factor of safety for a larger area subjected to the chemically enhanced drainage. The particularly promising result is that in both applications the largest gain in the well/drain efficiency has been observed for smaller chemically enhanced areas, where a short duration of treatment and small amounts of chemicals decrease the power consumption and increase the safety factor at the highest rate. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
992.
The ‘dissolved’ iron (that passed through a 0·4-μm filter) varied nonconservatively with salinity in the Connecticut River estuary. However, the total iron appeared to be conservative. Measurements of Fe(II) and Fe(III) showed that oxidation of Fe(II) was not a factor in the decrease of ‘dissolved’ iron in the low salinity region. A solubility model and analyses based on different pore-size filters indicated that a substantial amount of the ‘dissolved’ iron in the low salinity region was colloidal iron. The coagulation of fine colloidal particles led to the non-conservative behavior of ‘dissolved’ iron during estuarine mixing, but it did not necessarily lead to removal of total iron from the waters. Particulate iron was 80–90% of the total iron and it covaried with the total suspended matter during mixing and sediment resuspension. The residence time of water in the Connecticut River estuary was too short to allow removal of iron from the water column within the estuary. 相似文献
993.
本法以硫酸、硝酸和高氯酸为氧化剂,加热氧化破坏试样中存在的品质和非晶质炭。一般10g试样需用8—10ml H_2SO_4、0.2ml HNO_3和1ml高氯酸。将试样与混合酸共热20min,即可达到破坏试样中炭的目的。然后用王水分解样品,聚醚型聚氨酯泡沫塑料富集,硫脲解脱,原子吸收测定金。 相似文献
994.
李悦 《中国海洋湖沼学报》1994,12(3):236-245
The removal processes of major seawater chemical constituents in the Bohai Sea include seawater ex-change between the Bohai Sea and the Northern Yellow Sea,cation exchange,interstitial water burialand spray,formation of illite,sepiolite,sulfate and sulfur,and carbonates.The mass balance calculationbased on these processes is very applicable to the Bohai Sea. 相似文献
995.
Abstract Mineral assemblages in different samples of amphibolite facies pelitic schists collected from two separate outcrops in the Moosilauke area, NH, record differences in the chemical potential of water during metamorphism. Mineralogical, petrological, and field relations indicate that mineral assemblages at both outcrops equilibrated at 520°C and 3.5–4.0 kbar. Thermodynamic analysis of the mineral assemblages demonstrates that maximum chemical potential differences at each outcrop were of the order of 150 calories, over distances of 10–20 m.
The differences in the chemical potential of water recorded in both bed-to-bed and outcrop-to-outcrop relations are consistent with the following conclusions: (1) mineral assemblages on a specific outcrop did not equilibrate with an external reservoir of fluid of fixed composition, (2) the relatively small magnitude of the chemical potential differences suggests little or no infiltration of externally derived fluid, (3) these differences on the outcrop scale are probably related to initial compositional variations and the buffer capacity of the mineral assemblage, and (4) the different values of the chemical potential of water exhibited by the various mineral assemblages permits an understanding of the effects of variable μH2 O for amphibolite facies pelitic schists. 相似文献
The differences in the chemical potential of water recorded in both bed-to-bed and outcrop-to-outcrop relations are consistent with the following conclusions: (1) mineral assemblages on a specific outcrop did not equilibrate with an external reservoir of fluid of fixed composition, (2) the relatively small magnitude of the chemical potential differences suggests little or no infiltration of externally derived fluid, (3) these differences on the outcrop scale are probably related to initial compositional variations and the buffer capacity of the mineral assemblage, and (4) the different values of the chemical potential of water exhibited by the various mineral assemblages permits an understanding of the effects of variable μ
996.
997.
Geochemical studies on the intensity of chemical weathering in Luochuan loess-paleosol sequence, China 总被引:4,自引:0,他引:4
Major and trace element analyses of the Luochuan loess-paleosol sequence in China were performed in order to understand the
cheniical weathering processes occurring on the I.oess Plateau during the last 600 ka. Results reveal that most elements in
the loess remain immobile durlng chemical weathering. The typical stable elements are Al, K, Ti, Rb and REE, while the main
mobile elements are Ca, Sr, P, Mg and Na. 120ess and paleosol experience the incipient stage of chemical weathering characterized
by acid leaching and carbonate dissolution. Alteration of silicates in the sequence seems to be limited. Features of less
chemical weathering of the loess and paleosol could he indicators for the dry-cold clinlate dominated on the Loess Plateau
during the Quaternary.
Project supported hy thc Nzitional Natural Science Foundation of China 相似文献
998.
Precipitation Chemistry in the Sahelian Savanna of Niger, Africa 总被引:1,自引:0,他引:1
Within the framework of the IDAF (IGAC DEBITS AFRICA) network, we present in this paper data on precipitation and aerosol chemistry in the semiarid savanna of the Sahelian region of Niger. An automatic wet-only precipitation collector was operated at the Banizoumbou station during the entire 1996 rainy season (June to September 1996). Inorganic (Na+, NH
4
+
, K+, Mg2+, Ca2+, Cl-, NO
3
-
, SO
4
2-
) and organic contents of the precipitation (HCOOH, CH3COOH, C2H5COOH) were determined by Ion Chromatography (IC) in 29 rainfall events. Once per week, bulk particle samples were collected on the same site, and soluble water material was determined by IC. We examined the influence of atmospheric gas and particle sources on the precipitation and aerosol chemical contents. We established the influence of marine, terrigenous, and biogenic sources in the Sahelian region. The terrigenous signature is dominant and related to Sahelian soil erosion, with a high calcium content in precipitation (31.2 eq L-1) and in aerosols (1.8 g m-3). Two other signatures of atmospheric sources are highlighted by the relatively high nitrogenous (ammonium and nitrate) and organic contents (formate, acetate) in the precipitation. Ammonium (12.9 eq L-1) and nitrate (12.3 eq L-1) contents confirm respectively the biogenic source of ammonia released by domestic animal excreta in Niger and the natural emissions from semiarid savannas soils, perturbed by wild or domestic animal grazing. In spite of a high potential acidity given by nitrate, formate and acetate; a weak acidity (H+ (2.1 eq L-1) is calculated from the mean pH of 5.67 measured. A statistical analysis of the aerosol chemical composition clearly indicates that nitrates are strongly correlated at the 1% level with terrigenous ions, i.e., Ca2+ and Mg2+ (0.95 < r < 1). We observed a similar relationship between all the terrigenous ions and nitrate in the precipitation. In the Sahelian region, alkaline soil dust representative of the terrigenous contribution interact, with gaseous nitrogenous and carbonaceous compounds, leading to the neutralization of acid gases and subsequent weak acidity in precipitation. Finally, taking into account the main chemical characteristics of Banizoumbou precipitations and aerosols, which demonstrate the importance of heterogeneous and multiphase chemical processes, we propose a conceptual model of the atmospheric chemistry in the Sahelian region. 相似文献
999.
1000.
非金属矿物的化学分离与测定:Ⅱ.粘土矿物 总被引:4,自引:0,他引:4
对高岭石、滑石、海泡石、蒙脱石等粘土矿物的化学分离与测定进行了评述,引用文献21篇。 相似文献