The distribution, enrichment and source of potential harmful elements in surface sediments of Bohai Bay, North China

A geochemical study of Bohai Bay surface sediments was carried out to analyze the potential harmful element (PHE: Ge, Mo, In, Sn, Sb,Te, Tl, Bi and V) concentrations, transportation and deposition, enrichment factors and sources. Germanium, Mo, In, Sn, Sb, Te, Tl, Bi and V concentrations in the surface sediments were: 1.43-1.71, 0.52-1.43, 0.04-0.12, 2.77-4.14, 1.14-2.29, 0.027-0.085, 0.506-0.770, 0.27-0.63 and 70.35-115.90 mu g/g, respectively. The distributions of total PHE concentrations, together with sequential extraction analyses, showed that the PHEs were mainly due to natural inputs from the continental weathering delivered to the bay by rivers and atmospheric transportation and deposition. However, high Mo, Sb, Te, Bi and V occurred in non-residual fractions, suggesting some anthropogenic inputs in addition to the natural inputs. Besides sources, the distributions of PHEs were influenced by the coupling of physical, chemical and biological processes. Enrichment factor (EF) was computed for each site for each element in order to assess the polluting elements and the degree of pollution at each site. Results revealed that the EFs were generally lower than 1.0, particularly for Ge, Mo, In, Sn, Tl and V; however, the EFs were higher (>1.5), particularly for Sb, Te and Bi, revealing moderate contamination. (C) 2010 Elsevier B.V. All rights reserved.

Grey interrelation analysis to assess the influence of elements on the galvanic efficiency of Al sacrificial anode

Grey interrelation analysis method was used to study the correlation of Al-anode elements and its galvanic efficiency at 20 degreesC, 40 degreesC and 60 degreesC. Twenty-eight kinds of Al-anodes were made for experiments by the method given by Chinese National Standard GB4948-85 [1] and the correlation degree of elements added in the anodes were calculated. The results showed that the order of elements affecting galvanic efficiency at different temperature is basically the same, and the correlation degree can reflect the variation of Al-anode galvanic efficiency when changing temperature. It is suggested that the elements being added in Al-anode are Zn, In, Ga, Mg.

Effect of alloy elements on the anti-corrosion properties of low alloy steel

Effect of alloy elements on corrosion of low alloy steel was studied under simulated offshore conditions. The results showed that the elements Cu, P, Mo, W, V had evident effect on corrosion resistance in the atmosphere zone; Cu, P, V, Mo in the splash zone and Cr, Al, Mo in the submerged zone.

Alloy elements' effect on anti-corrosion performance of low alloy steels in different sea zones

The corrosion rate of low alloy steel in different sea zones has close correlation with the content of the alloy element. From the field data of steel corrosion rates in atmospheric zone, splash zone and immersion zone, regression analysis was used to study the correlation between the corrosion rate of steels and the amount of added alloy elements. Three regression equations were obtained in different sea zones. Based on the equations, the anti-corrosion performance of the alloy elements can be deduced which can be used to screen out low alloy steel with good anti-corrosion performance. (C) 2007 Elsevier B.V. All rights reserved.

Influence of lanthanum on the accumulation of trace elements in chloroplasts of cucumber seedling leaves

Influence of La3+ on the accumulation of trace elements (Se-75, Co-56, Rb-83, V-48, (95)mTc, and Ga-67) in chloroplasts of cucumber seedling leaves was studied by a radioactive multitracer technique. At the same time, chloroplast contents of different concentrations of La3+ treatment were calculated. It was observed that chloroplast contents peaked at 0.02 mM La3+ treatment and that the uptake and distribution of these trace elements in chloroplasts of cucumber seedling leaves are different under different La3+, treatments. With the increase of lanthanum concentrations from 0.002 to 2 mM, the uptake percentages of Se-75, Co-56, and Rb-83 presented an obvious increase and then sharply decreased in contrast to the nonlanthanum treatment, whereas there appeared a sharp decrease and then restored control level in the uptake of V-48. The other two trace elements, namely Tc-95m and Ga-67, were accumulated only in the presence of 0.02 mM La3+. The results indicate that lanthanum treatments to growing the cucumber lead to the change of trace element uptake in the chloroplasts of leaves, which suggest that lanthanum might influence the accumulation of trace elements in chloroplasts of cucumber seedling leaves by regulation of various ion transport mechanisms, thus affecting the photosystem of leaves.

Effects of hypoxia on contents of essential elements in pika and rat heart

The effects of hypoxia on the levels of essential macroelements and trace elements (K, Na, Ca, Mg, Cu, Zn, Fe, and Mn) in the heart muscles of Wistar rats and plateau pikas (Ochotona curzoniae) were studied by atomic absorption spectrometry. Unlike the rat, the plateau pika is tolerant to hypoxia. The levels of K, Na, and the trace element Mn were not significantly changed in rat or pika hearts after exposure to hypoxia for 1, 10, or 25 d at simulated altitudes of 5000 and 7000 m. Other minerals (Ca, Mg, Cu, Zn, and Fe) were significantly affected by hypoxia and the levels followed different time-courses under different hypoxic regimes in these two animals. There were marked differences between the rat and pika in myocardial accumulation of essential elements such as Ca, which was increased to high levels in the rat but not affected in the pika. The results suggest that hypoxia affects animal physiological mechanisms by regulating the levels of essential elements.

Influence of lanthanum on the uptake of trace elements in cucumber plant

The effects of La3+ on the uptake of trace elements (Se, Co, V, and Tc) in cucumber plants were studied by a radioactive multitracer technique. It was observed that the uptake and distribution of these trace elements in roots, stems, and leaves are different under different La3+, treatments. Furthermore, in the control, the plant accumulates Se-75, Co-56, and V-48 all in the order roots>leaves>stems, whereas Tc-95m was in the order leaves>stems>roots. The accumulations of Se-75 and Tc-95m in plants treated with different La3+ concentration were in the same order as those in the control, but the uptakes percentages of other kinds of element changed differently. The results indicate that lanthanum treatments to a growing cucumber lead to the change of uptake of trace elements, which suggest that a rare earth element is directly or indirectly involved in the ion transport of the plant and affects plant growth by regulating the uptake and distribution of elements that influence the plant cell physiology and biochemistry.

Uptake and distribution of trace elements in growing cucumber

Multitracer technique was used to study the uptake and distribution of some relatively long half-life radionuclides Be, Na, Mn, Co, Sc to growing cucumber (Cucumis Sativus L.) with two different treatments. In Hoagland solution, only Mn-54 and Co-60 accumulated in the every part of plants. Mn-54, Co-60 and other radionuclides were absorbed in distilled water. The results indicate that there were major differences in the accumulation of trace elements between the two different treatments.

边坡工程的极限分析上限法

Theory of limit analysis include upper bound theorem and lower bound theorem. To deal with slope stability analysis by limit analysis is to approximate the real solution from upper limit and lower limit. The most used method of limit analysis is upper bound theorem, therefore it is often applied to slope engineering in many cases. Although upper bound approach of limit analysis can keep away from vague constitutive relation and complex stress analyses, it also can obtain rigorous result. Assuming the critical surface is circular slip surface, two kinematically admissible velocity fields for perpendicular slice method and radial slice method can be established according to the limit analysis of upper bound theorem. By means of virtual work rate equation and strength reduction method, the upper-bound solution of limit analysis for homogeneous soil slope can be obtained. A log-spiral rotational failure mechanism for homogeneous slope is discussed from two different conditions which represent the position of shear crack passing the toe and below the toe. In the dissertition, the author also establishes a rotational failure mechanics with combination of different logarithmic spiral arcs. Furthermore, the calculation formula of upper bound solution for inhomogeneous soil slope stability problem can be deduced based on the upper bound approach of rigid elements. Through calculating the external work rate caused by soil nail, anti-slide pile, geotechnological grid and retaining wall, the upper bound solution of safety factor of soil nail structure slope, slip resistance of anti-slide pile, critical height of reinforced soil slope and active earth pressure of retaining wall can be obtained by upper bound limit analysis method. Taking accumulated body slope as subject investigated, with study on the limit analysis method to calculate slope safety factor, the kinematically admissible velocity fields of perpendicular slice method for slope with broken slip surface is proposed. Through calculating not only the energy dissipation rate produced in the broken slip surfaces and the vertical velocity discontinuity, but also the work rate produced by self-weight and external load, the upper bound solution of slope with broken slip surface is deduced. As a case study, the slope stability of the Sanmashan landslide in the area of the Three Gorges reservoir is analyzed. Based on the theory of limit analysis, the upper bound solution for rock slope with planar failure surface is obtained. By means of virtual work-rate equation, energy dissipation caused by dislocation of thin-layer and terrane can be calculated; furthermore, the formulas of safety factor for upper bound approach of limit analysis can be deduced. In the end, a new computational model of stability analysis for anchored rock slope is presented after taking into consideration the supporting effect of rock-bolts, the action of seismic force and fissure water pressure. By using the model, not only the external woke-rate done by self-weight, seismic force, fissure water pressure and anchorage force but also the internal energy dissipation produced in the slip surface and structural planes can be totally calculated. According to the condition of virtual work rate equation in limit state, the formula of safety factor for upper bound limit analysis can be deduced.