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31.
硒碲胁迫对两种螺旋藻生长的影响 总被引:8,自引:3,他引:8
研究了硒(Na2SeO 3)和碲(Na2TeO 3)胁迫对钝顶螺旋藻(Spirulinaplatensis)和极大螺旋藻(Spirulinamaximum)生长的影响。结果表明 ,两种藻对硒、碲表现出不同的耐性。对于S.platensis,CSe≤200mg/L促进生长 ,CTe<100mg/L影响不大 ,CTe≥100mg/L抑制生长 ,CSe≥800mg/L或CTe=400mg/L藻死亡 ;而对于S.maximum ,CSe=25mg/L时促进生长 ,CTe≤25mg/L无影响 ,CTe≥50mg/L明显抑制生长 ,CSe≥800mg/L或CTe≥600mg/L则死亡。而在培养周期内分次添加硒、碲 ,当累计达到CSe(CTe)=800mg/L,两种藻仍能正常生长。表明硒、碲添加方式不同 ,产生明显不同的效应。 相似文献
32.
Waste red mud and natural pumice/volcanic slag particles were surface modified and their selenium adsorption from waters was investigated. Acid activation/heat treatment of original red mud (ORM) particles significantly increased their micropore and external surface area and cumulative volume of pores. Iron oxide coating of pumice/slags and acid activation of ORM decreased their pHpzc values and increased surface acidity. Selenite/selenate adsorption on iron oxide surfaces and acid activated red mud (AARM) was very fast with approximately first‐order adsorption kinetics. Iron oxide coating of pumice/slag and acid activation of ORM particles significantly enhanced their selenite and selenate uptakes. Maximum Se adsorption capacities as high as 6.3 (mg Se/g adsorbent) were obtained by AARM. The extent of selenate uptakes by the surface modified particles was generally lower than those of selenite. Due to competition among Se species and other background water matrix for iron oxide adsorption sites, reduced selenite/selenate uptakes were found in natural water compared to single solute tests. Higher Se uptakes by iron oxide surfaces were found at pH 7.5 compared to pH 8.9, due to increased electrostatic repulsion among iron oxides and Se species at higher pH. The most effective adsorbents among the tested 17 different particles for Se uptake were AARM and iron oxide coated pumice. Se concentrations less than drinking water standards (5–10 µg/L) can be achieved by these particles. These low‐cost, natural, or recyclable waste particles appear to be promising adsorbents for Se removal after their surface modification. 相似文献
33.
Ultrasound extraction was used to compare the accelerated release rates of selenium and arsenic from three rocks (BT700, BT
571 and BT 60) that are associated with mountaintop mining and valley fill coal mining practiced in southern parts of West
Virginia, USA. The concentrations of arsenic released from rocks were found to be three orders of magnitude higher than that
of selenium. The accelerated leaching rate constants were ten times higher for arsenic compared to selenium. Se (IV) was found
to be stable under ultrasound extraction conditions used whereas As (III) was quickly oxidized to As (V). BT700 was found
to have more Se (IV) compared to BT571 while BT60 did not have any significant Se (IV) concentrations. Such compositional
and kinetic information becomes important when determining suitable mining waste treatment protocols that have to be undertaken
to different types of overburden before it is dumped in valleys. 相似文献
34.
随着城市化进程和经济全球化,中国城市的同质化问题凸显,这将削弱城市竞争力,滞缓城市发展。从现象学出发,以诺伯格·舒尔茨提出的场所精神为核心,探讨城市发展遇到的问题与解决方法。以重庆、贵阳的几个网红节点空间为例,从历史文化传承,环境利用,空间、建筑、景观设计等方面,分析其形成的内在原因和特征。自然环境、地域文化与建筑环境的共同作用是网红节点的形成基础。规划设计中:应更多关注人的体验,回归城市设计的根本,使节点空间更好地发挥辐射作用;将人的意识作用于城市空间,城市空间反作用于人的行为;同时,在节点空间营造上应注重场所感,突出城市文脉特征。 相似文献
35.
In this study, an attempt has been made to assess aqueous speciation of selenium and solubility product constants of common selenides at elevated temperatures (up to 300 °C) by using various extrapolation methods. This study predicts that reduced selenium species are dominant species in many geological processes even under relatively oxidized conditions such as those dictated by the magnetite–hematite buffer. On the basis of extrapolated equilibrium constants and solubility product constants for common Se-bearing mineral phases, critical ∑Se/∑S ratios (molal ratios) in mineralizing fluids are proposed for independent selenium mineralization. The minimum ∑Se/∑S ratios in mineralizing fluids for independent selenium mineralization should be at least 10−6, 10−5 and 10−4 at 100, 200 and 300 °C, respectively. For giant independent selenium deposits such as the La'erma and Qiongmo Au–Se deposits in the western Qingling mountains, and Yutangba Se deposits in Hubei Province, China, the mineralizing fluids have reached much higher ∑Se/∑S ratios ranging from 10−1 to 10−3 at 200 °C. This study also suggests that the equilibrium assemblage of pyrite–ferroselite among the common ore minerals requires the highest ∑Se/∑S ratios in mineralizing fluids, followed in decreasing order by the assemblages of stibnite–antimonselite, galena–clausthalite, cinnabar–tiemannite, and acanthite/argentite–naumannite. The assemblage of pyrite–ferroselite can also be formed under relatively oxidizing conditions where [∑H2Se]/[∑H2S] ratios can be high enough for the formation of independent ferroselite. 相似文献
36.
Selenium fractionation and speciation in rocks, soils, waters and plants in polluted surface mine environment 总被引:1,自引:0,他引:1
A fractionation and speciation was performed to determine the distribution of selenium (Se) species in major components of quartzite surface mine environment (rocks, mine tailings, soils, stream sediments, surface waters and plants) in obov, Slovakia. A three-step sequential extraction procedure was utilised for the fractionation of Se in mine tailings and soils. The first extractant in order to evaluate the soluble and ligand exchangeable fraction of Se (0.1 mol/l K2HPO4 + KH2PO4 at pH 7.0) solubilized up to 15% of total Se content. The second step (0.1 mol/l K2S2O8 at 90°C) which extracted Se associated or occluded with organic matter released 13 – 45% of total selenium. The decomposition of the residue (HNO3 + H2SO4 1+1) was used to solubilize the remaining 35–88% of total Se as the final step. The recovery of the procedure was between 97 and 106%. Selenate predominated in natural river and lake waters about pH 7.0 (>95%) but in acid mine leakings up to 40% of selenite was found. In the plants (birch leaves, grass leaves and roots) collected from the area acidified by mine leakings no significant accumulation of selenium was observed. The correlation between total Se and S in the rocks from the mine gives an evidence of the common origin of these elements in the studied area. 相似文献
37.
Coalbed methane producibility from the Mannville coals in Alberta, Canada: A comparison of two areas 总被引:2,自引:1,他引:1
T. Gentzis F. Goodarzi F.K. Cheung F. Laggoun-Dfarge 《International Journal of Coal Geology》2008,74(3-4):237-249
Selenium concentrations were measured in five rock cores from a mine in Boone County, West Virginia to determine their relationship to sulfur, rock type and stratigraphic location. The samples spanned the Winifrede and Coalburg coal beds of the Middle Pennsylvania upper Kanawha Formation and included coals and clastic lithologies. The coals generally contained the highest concentrations of Se and the sandstones the lowest. No correlation was observed between total Se and sulfur concentrations for either the entire data set or for individual lithologies. Better correlations were identified for log concentrations between total Se and total organic carbon. Principal component analysis identified a strong sulfur–acid component, interpreted to be due to sulfide mineral presence, which correlates well with S but not with Se. Coal sample chemistry is more likely to load onto this component while clastic rock chemistry is more likely to load onto the second, non-sulfur component. Se concentrations load onto both components indicating they are not controlled by a single overriding chemistry. Selective extractions indicate that Se is distributed between both sulfide and organically-bound fractions, as defined by the test. Overall, the lack of correlation between Se and S, the distribution of Se among extracted fractions, and the loading of Se onto both sulfur and non-sulfur components support that the Se in these rock layers is distributed in more than one chemically-bound form. Non-coal rock units with the highest concentrations of Se were found adjacent to coal beds, suggesting that redistribution of Se may have occurred post-deposition. The acidic domed swamps that formed these coals were low in sulfur and a reasonable chemical setting to accumulate Se if it were introduced. The preservation of Se in the domed swamp peat coupled with post-depositional redistribution may partly explain the data presented. 相似文献
38.
The purpose of this study is to investigate the enrichment level and dispersion patterns of Se and associated elements in rocks, soils and crops which were collected in the Dukpyung and the Chubu areas covered with black shales of the Okchon Group in Korea. Rock and soil samples were analyzed for Se including multiple elements by ICP, ICP-MS and INAA, and crop samples by INAA. Soil pH and loss-on-ignition (LOI) were also measured. 相似文献
39.
Xiu-jin Liu Ke Yang Fei Guo Shi-qi Tang Ying-han Liu Li Zhang Hang-xin Cheng Fei Liu 《China Geology》2022,5(1):1-11
To illuminate the migration and transformation of selenium(Se)in the igneous rock-soil-rice system,285 pairs of rhizosphere soil and rice samples were collected from the granitoid and basalt areas in Hainan Province,South China.The contents of Se in soils derived from granitoid and basalt are,respectively,0.19±0.12 mg/kg and 0.34±0.39 mg/kg,which are much higher than Se contents in granitoid and basalt.Selenium shows remarkable enrichment from granitoid and basalt to soils.The mobile fraction of Se in soils derived from granitoid is 0.0100±0.0034 mg/kg,which is significantly higher than that of basalt(0.0058±0.0039 mg/kg).Although soil derived from basalt shows higher Se contents,Se contents in rice samples,mobile fractions of Se in soils,and biological concentration factor(BCF)is similar or even lower than that from granitoid.Basalt consist of calcic plagioclase and pyroxene,and are much richer in Fe,Al,and Ca than granitoid.Correspondingly,the basalt-derived soils have higher goethite,hematite,kaolinite,cation exchange capacity(CEC)content,and higher p H than the granitoid-derived soils,which result in higher adsorption capacity for Se and relatively lower Se bioavailability.Soils derived from granitoid and basalt in tropical regions are beneficial to produce Se-rich rice. 相似文献
40.
Ley-Quiñónez C Zavala-Norzagaray AA Espinosa-Carreón TL Peckham H Marquez-Herrera C Campos-Villegas L Aguirre AA 《Marine pollution bulletin》2011,62(9):1979-1983
Environmental pollution due to heavy metals is having an increased impact on marine wildlife accentuated by anthropogenic changes in the planet including overfishing, agricultural runoff and marine emerging infectious diseases. Sea turtles are considered sentinels of ecological health in marine ecosystems. The objective of this study was to determine baseline concentrations of zinc, cadmium, copper, nickel, selenium, manganese, mercury and lead in blood of 22 clinically healthy, loggerhead turtles (Caretta caretta), captured for several reasons in Puerto López Mateos, Baja California Sur, Mexico. Zinc was the most prevalent metal in blood (41.89 μg g−1), followed by Selenium (10.92 μg g−1). The mean concentration of toxic metal Cadmium was 6.12 μg g−1 and 1.01 μg g−1 respectively. Mean concentrations of metals followed this pattern: Zn > Se > Ni > Cu > Mn > Cd > Pb and Hg. We can conclude that blood is an excellent tissue to measure in relatively non-invasive way baseline values of heavy metals in Caretta caretta. 相似文献