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61.
Gorazd Žibret 《Environmental Geology》2008,56(1):189-196
The research shows that in the Celje area (Slovenia), the historical anthropogenical emissions are 1,712 tons of Zn and 9.1 tons
of Cd. For Zn, this value represents approximately 0.3% of the total Zn production in that area. Close to the former zinc
smelting plant, the “Zn precipitation” has been estimated to be up to 0.036 mm. The 100-year Zn production left behind a heavily
contaminated area with maximum concentrations of Zn of up to 5.6% in attic dust and 0.85% in the soil, and 456 mg/kg of Cd
in attic dust and 59.1 mg/kg in the soil. The calculation of historical emissions is based on the data of heavy metals concentration
in the attic dust at 98 sampling points and on the data from 19 measurement sites of the weight of total monthly air deposit.
The main idea behind determining past emissions is that when the weight of the deposited dust on a small area is multiplied
by the concentration of the element in that area, the mass of the polluter which has been transported to the place of interest
by air can be calculated. If we sum up all the weight over the whole geochemical anomaly, we get the quantity of historical
emissions. 相似文献
62.
Global Correlations of Ocean Ridge Basalt Chemistry with Axial Depth: a New Perspective 总被引:4,自引:0,他引:4
The petrological parameters Na8 and Fe8, which are Na2O andFeO contents in mid-ocean ridge basalt (MORB) melts correctedfor fractionation effects to MgO = 8 wt%, have been widely usedas indicators of the extent and pressure of mantle melting beneathocean ridges. We find that these parameters are unreliable.Fe8 is used to compute the mantle solidus depth (Po) and temperature(To), and it is the values and range of Fe8 that have led tothe notion that mantle potential temperature variation of TP= 250 K is required to explain the global ocean ridge systematics.This interpreted TP = 250 K range applies to ocean ridges awayfrom hotspots. We find no convincing evidencethat calculated values for Po, To, and TP using Fe8 have anysignificance. We correct for fractionation effect to Mg# = 0·72,which reveals mostly signals of mantle processes because meltswith Mg# = 0·72 are in equilibrium with mantle olivineof Fo89·6 (vs evolved olivine of Fo88·1–79·6in equilibrium with melts of Fe8). To reveal first-order MORBchemical systematics as a function of ridge axial depth, weaverage out possible effects of spreading rate variation, local-scalemantle source heterogeneity, melting region geometry variation,and dynamic topography on regional and segment scales by usingactual sample depths, regardless of geographical location, withineach of 22 ridge depth intervals of 250 m on a global scale.These depth-interval averages give Fe72 = 7·5–8·5,which would give TP = 41 K (vs 250 K based on Fe8) beneathglobal ocean ridges. The lack of Fe72–Si72 and Si72–ridgedepth correlations provides no evidence that MORB melts preservepressure signatures as a function of ridge axial depth. We thusfind no convincing evidence for TP > 50 K beneath globalocean ridges. The averages have also revealed significantcorrelations of MORB chemistry (e.g. Ti72, Al72, Fe72,Mg72, Ca72, Na72 and Ca72/Al72) with ridge axial depth. Thechemistry–depth correlation points to an intrinsic linkbetween the two. That is, the 5 km global ridge axial reliefand MORB chemistry both result from a common cause: subsolidusmantle compositional variation (vs TP), which determines themineralogy, lithology and density variations that (1) isostaticallycompensate the 5 km ocean ridge relief and (2) determine thefirst-order MORB compositional variation on a global scale.A progressively more enriched (or less depleted) fertileperidotite source (i.e. high Al2O3 and Na2O, and low CaO/Al2O3)beneath deep ridges ensures a greater amount of modal garnet(high Al2O3) and higher jadeite/diopside ratios in clinopyroxene(high Na2O and Al2O3, and lower CaO), making a denser mantle,and thus deeper ridges. The dense fertile mantle beneath deepridges retards the rate and restricts the amplitude of the upwelling,reduces the rate and extent of decompression melting, givesway to conductive cooling to a deep level, forces melting tostop at such a deep level, leads to a short melting column,and thus produces less melt and probably a thin magmatic crustrelative to the less dense (more refractory) fertile mantlebeneath shallow ridges. Compositions of primitive MORB meltsresult from the combination of two different, but geneticallyrelated processes: (1) mantle source inheritance and (2) meltingprocess enhancement. The subsolidus mantle compositional variationneeded to explain MORB chemistry and ridge axial depth variationrequires a deep isostatic compensation depth, probably in thetransition zone. Therefore, although ocean ridges are of shalloworigin, their working is largely controlled by deep processesas well as the effect of plate spreading rate variation at shallowlevels. KEY WORDS: mid-ocean ridges; mantle melting; magma differentiation; petrogenesis; MORB chemistry variation; ridge depth variation; global correlations; mantle compositional variation; mantle source density variation; mantle potential temperature variation; isostatic compensation 相似文献
63.
利用高精度多梯度热培养系统,对英国威尔士地区两类典型的北方泥炭沼泽中酚类物质和溶解有机碳释放的热敏感性进行了为期1年的调查研究.研究结果表明,雨养泥炭沼泽(Bog)酚类物质释放的热敏感性Q10(总酚)月变化为0.92~1.57,而矿养泥炭沼泽(Fen)的月变化范围为0.93~1.30.酚类释放的热敏感性与土壤温度大致呈正相关关系.此外,土壤温度与溶解有机碳释放的热敏感性Q10(DOC)也呈正相关关系.总体上,雨养泥炭沼泽的热敏感性比矿养泥炭沼泽略高.除温度外,水文条件和植被等多种环境因子对酚类物质和溶解有机碳释放的热敏感性也有较大影响.研究结果还表明酚碳热敏感性比值Q10o(总酚)/Q10(DOC)相对稳定,土壤温度的变化对其影响有限. 相似文献
64.
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67.
邹平王家庄铜矿床成矿地球化学及成因探讨 总被引:2,自引:0,他引:2
王家庄铜矿床的矿化脉石英中流体包裹体均一温度介于116 ~ 566 ℃之间,均值为 289 ℃;盐度介于7.2%~63.2% NaCleq,均值为21.1% NaCleq。流体的气相成分主要为H2O和CO2。在均一温度为240 ~ 440 ℃区间内,出现了富气相的两相水溶液包裹体、富液相的两相水溶液包裹体和含子晶的三相水溶液包裹体共存现象,以及加温后富气相包裹体均一到气相和同期富液相包裹体均一到液相的特征,表明成矿流体曾发生过沸腾作用;其中第一次发生于360 ~ 400 ℃,主要形成高温、高盐度含子晶的三相水溶液包裹体和高温、中盐度富液相的两相水溶液包裹体及高温、低盐度富气相的两相水溶液包裹体;第二次发生于240 ~ 320 ℃,主要形成高—中温、高盐度的含子晶的三相水溶液包裹体和高—中温、中盐度富液相的两相水溶液包裹体及高—中温、低盐度富气相的两相水溶液包裹体;之后主要形成富液相的两相水溶液包裹体,具有中低温和中盐度的特征。矿化脉石英中的δ18OH2O介于-1.14‰ ~ 1.79‰之间,均值为0.94‰;δD介于-63.70‰ ~ -56.50‰之间,均值为-59.8‰;说明王家庄铜矿床的成矿流体主要来源于岩浆,后期混入大气降水。矿石矿物的δ34S变化于-8.80‰ ~ -2.80‰之间,均值为-6.33‰。矿石矿物的n(206Pb)/n(204Pb)介于18.1684 ~ 18.3637之间,均值为18.2892;n(207Pb)/n(204Pb)介于155546 ~ 156342之间,均值为155777;n(208Pb)/n(204Pb)介于38.1286 ~ 38.4840之间,均值为38.2780。说明矿石具有贫重硫和富放射性成因铅的特征,硫、铅主要来源于深部,后期可能受到地壳物质或大气降水的混染。 相似文献
68.
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70.
气候变化对塔里木河来自天山的地表径流影响 总被引:21,自引:10,他引:11
塔里木河水资源主要来自天山南坡两条源流,选择西段阿克苏河和中段开都河-孔雀河作为研究区.1956-2003年研究河源山区气温呈持续升温且降水波动增加的趋势,其中1995-2003年升温强劲,升温速率高出48 a期间平均的3倍以上;降水自1986年后持续增加,20世纪90年代较80年代增幅达18%,并显示出河源山区湿岛向塔里木盆地扩展.因高山缺少气象观测,出山径流过程变化可以综合反映中高山带的气候变化.塔里木河来自天山的地表径流在1986-2003年间持续增长,以冰川融水补给为主的库玛拉克河,1994年以来年径流量增加已在前期平均值基础上提升了一个台阶;开都河以降水径流补给为主,1986-2002年出现了观测记录以来的丰水期,并使1986年后博斯腾湖水位快速上升,恢复到1958年记录的最高水位以上.两河年径流变化趋势基本相似,但也显示有西、中段的气候变化局部差异,出现丰枯水期的不一致;然而,在近16 a升温过程中,年径流增长幅度和快慢相近. 相似文献