Serpentine geology links to water quality and heavy metals in sediments of a stream system in central Queensland,Australia     

Leo J. Duivenvoorden  David T. Roberts  Gail M. Tucker 《Environmental Earth Sciences》2017,76(8):320

Serpentinite soils, common throughout the world, are characterized by low calcium-to-magnesium ratios, low nutrient levels and elevated levels of heavy metals. Yet the water quality and heavy metal concentrations in sediments of streams draining serpentine geology have been little studied. The aim of this work was to collect baseline data on the water quality (for both wet and dry seasons) and metals in sediments at 11 sites on the Marlborough Creek system, which drains serpentine soils in coastal central Queensland, Australia. Water quality of the system was characterized by extremely hard waters (555–698 mg/L as CaCO₃), high dissolved salts (684–1285 mg/L), pH (8.3–9.1) and dissolved oxygen (often >110% saturation). Cationic dominance was Mg > Na > Ca > K and for anions HCO₃ > Cl > SO₄. Al, Cu and Zn in stream waters were naturally high and exceeded Australian and New Zealand Environment and Conservation Council guidelines. Conductivity displayed the highest seasonal variability, decreasing significantly after wet season flows. There was little seasonal variation in pH, which often exceeded regional guidelines. Stream sediments were enriched with concentrations of Ni, Cr, Co and Zn up to 35, 21, 10 and 2 times the world average for shallow sediments, respectively. Concentrations for Ni and Cr were up to 60 and 16 times those of the relevant Interim Sediment Quality Guidelines Low Trigger Values, respectively. The distinctive nature of the water and sediment data suggests that it would be appropriate to establish more localized water quality and sediment guidelines for the creek system for the water quality parameters conductivity, Cu and Zn (and possibly Cr and Cd also), and for sediment concentrations of Cd, Cr and Ni.  相似文献   

Fluid geochemistry of the Mondragone hydrothermal systems (southern Italy): water and gas compositions vs. geostructural setting     

Cuoco  Emilio  Minissale  Angelo  Di Leo  Antonella “Magda”  Tamburrino  Stella  Iorio  Marina  Tedesco  Dario 《International Journal of Earth Sciences》2017,106(7):2429-2444

International Journal of Earth Sciences - The geochemistry of natural thermal fluids discharging in the Mondragone Plain has been investigated. Thermal spring emergences are located along the...  相似文献   

Competitive Adjustment and Advancement in Global Commodity Chains: I. Firm Strategies and Trajectories in the East Asian Apparel Industry     

Leo van Grunsven  Floor Smakman 《Singapore journal of tropical geography》2001,22(2):173-188

Globalisation discourses increasingly depart from a network‐centred view of the world, and focus on the possibilities of leveraging economic globalisation – through incorporation in international production networks and global commodity chains (GCCs)– as a strategy for less developed countries (LDCs) to industrialise and advance their position in the world economy. This article goes beyond the question of incorporation and addresses the issue of sustaining positions, upgrading to more rewarding roles, and advancing to less dependent positions within production networks and GCCs. Drawing on experiences in the East Asian apparel industry, we present a framework for analysing such processes at both the firm and industry levels. We demonstrate that the East Asian experience provides a rather positive picture, despite a decline in the region's share of world trade. The present paper is a preliminary contribution; further research, using the framework presented, would enhance insights into competitive adjustment and advancement in GCCs, specifically, the forces underlying success or failure.  相似文献   

Book reviews     

Andrea Borgia  Douglas R. Schmitt  Manfred Koch  Leo A. Maslov  Konrad Bajer  Jacek Leliwa-Kopystyński  Lech Stefaníak 《Pure and Applied Geophysics》1992,138(2):335-352

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Metals in plants and waters in the Okefenokee swamp and their relationship to constituents found in coal     

Daniel J. Casagrande  Leo D. Erchull 《Geochimica et cosmochimica acta》1977,41(9):1391-1394

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Geochemistry, strontium isotope data, and potassium-argon ages of the andesite-rhyolite association in the Padang area, West Sumatra     

Gerhard W. Leo  Carl E. Hedge  Richard F. Marvin 《Journal of Volcanology and Geothermal Research》1980,7(1-2)

Quaternary volcanoes in the Padang area on the west coast of Sumatra have produced two-pyroxene, calc-alkaline andesite and volumetrically subordinate rhyolitic and andesitic ash-flow tuffs. A sequence of andesite (pre-caldera), rhyolitic tuff and andesitic tuff, in decreasing order of age, is related to Maninjau caldera. Andesite compositions range from 55.0 to 61.2% SiO₂ and from 1.13 to 2.05% K₂O. Six K-Ar whole-rock age determinations on andesites show a range of 0.27 ± 0.12 to 0.83 ± 0.42 m.y.; a single determination on the rhyolitic ashflow tuff gave 0.28 ± 0.12 m.y.Eight ⁵⁷Sr/²⁶Sr ratios on andesites and rhyolite tuff west of the Semangko fault zone are in the range 0.7056 – 0.7066. These ratios are higher than those elsewhere in the Sunda arc but are comparable to the Taupo volcanic zone of New Zealand and calc-alkaline volcanics of continental margins. An ⁸⁷Sr/⁸⁶Sr ratio of 0.7048 on G. Sirabungan east of the Semangko fault is similar to an earlier determination on nearby G. Marapi (0.7047), and agrees with ⁸⁷Sr/⁸⁶Sr ratios in the rest of the Sunda arc. The reason for this distribution of ⁸⁷Sr/⁸⁶Sr ratios is unknown.The high ⁸⁷Sr/⁸⁶Sr ratios are tentatively regarded to reflect a crustal source for the andesites, while moderately fractionated REE patterns with pronounced negative Eu anomalies suggest a residue enriched in plagioclase with hornblende and/or pyroxenes. Generation of associated andesite and rhyolite could have been caused by hydrous fractional melting of andesite or volcanogenic sediments under adiabatic decompression.  相似文献   

Isotopic anomalies in meteorites and their origins—V. Search for fission fragment recoils in Allende sulfides     

Roy S. Lewis  Jan Hertogen  Leo Alaerts  Edward Anders 《Geochimica et cosmochimica acta》1979,43(11):1743-1752

Three troilite- and pentlandite-rich samples from the Allende C3 chondrite were analyzed for Xe (and in one case Ne and Ar) by mass spectrometry, in 13–22 temperature steps. All samples released a small ‘CCFXe’ component (enriched in the heavy isotopes Xe^{134, 136}) at the relatively low temperature of 700–800°C, ahead of adsorbed atmospheric Xe (~900°C), radiogenic Xe¹²⁹ (1000°C), and primordial Xe (1250°C). Though such a labile component suggests implanted fission recoils, the simultaneous release of Ne, Ar, and Xe^{124, 126} shows that it instead comes from carbon and perhaps chromite, two major host phases of CCFXe. Apparently small amounts of these phases are occluded in sulfides, and decompose by chemical reaction upon heating. Thus the experiment fails to resolve the nature of CCFXe.A marked enrichment of Xe¹²⁴, without corresponding enrichments in Xe¹²⁶ or Xe^131–136, was observed in the 550–650° and 1400–1500° fractions. Though requiring confirmation, it supports earlier evidence for the complexity and variability of the light xenon component, contrary to claims that it is an integral part of CCFXe.  相似文献   

A carbonaceous inclusion from the Krymka LL-chondrite: noble gases and trace elements     

Roy S. Lewis  Leo Alaerts  Jan Hertogen  Marie-Josée Janssens  Herbert Palme  Edward Anders 《Geochimica et cosmochimica acta》1979,43(6):897-903

A black inclusion from the Krymka LL3 chondrite was analyzed for 20 trace elements and five noble gases, by radiochemical neutron activation and mass spectrometry. The trace element pattern somewhat resembles that of C1 or C2 chondrites, but with several unique features. Elements of nebular condensation T ? 1000 K (U, Re, Os, Ir, Ni, Pd, Au, Sb and Ge) are essentially undepleted, as in C1 chondrites, but $\text{Re}\text{Ir}$ is 1.49 × higher than the characteristic Cl value. Among elements condensing below 1000 K, Cs, Se, Te, and In are depleted to approximately C2 levels (~0.6 × C1), whereas Ag, Bi, Tl are enriched to ~ 1.6 × C1. Such enrichments are thought to be characteristic of late nebular condensates.The noble-gas pattern also is unique. Gas contents are higher than in C1s, by factors of 2.6 to 19 for Ne through Xe. The $\text{Ar}{}^{36}\text{Xe}{}^{132}$ ratio of 500 is higher than mean values for C1s or C2s (109 or 89) and exceeds even the highest value seen in C3Os, 420, whereas the $\text{He}{}^4\text{Ne}{}^{20}$ ratio of 62 is much lower than the values for C1s and C2s (200–370). The $\text{Xe}{}^{129}\text{Xe}{}^{132}$ and $\text{Xe}{}^{136}\text{Xe}{}^{\mathrm{l32}}$ ratios of 1.040 and 0.320 resemble those of C1 chondrites, and seem to imply typical proportions of radiogenic Xe¹²⁹ and ‘fissiogenic’ xenon.It appears that the inclusion represents a new primitive meteorite type, similar to C-chondrites, but probably a late condensate from a region of higher nebular pressure.  相似文献   

Net radiation,sensible and latent heat flux densities on slopes computed by the energy balance method   总被引：3，自引：0，他引：3  

Leo Fritschen  Ping Qian 《Boundary-Layer Meteorology》1990,53(1-2):163-171

Energy balance components obtained over five grass-covered sloping surfaces near Manhattan, KS, using the Bowen ratio energy balance technique with the instruments mounted horizontally were compared with calculated values when the instruments were mounted parallel to the surfaces. Hourly values of the components changed when the instruments were parallel to the surfaces. The changes were larger at low solar angles (spring and fall) and on steeper slopes. An area average of daylight totals, assuming that all aspects were equally represented, changed only 0.1% on June 6 and 2.3% on October 11. The calculations, extended to steeper slopes, indicated small changes in the daylight totals for slopes of less than 10 deg.Supported in part by a grant from NASA NAG 5-901.  相似文献   

我国城市分类和城市发展问题的初步研究   总被引：4，自引：0，他引：4  

方磊  刘宏 《地理学报》1988,(1)

本文认为适合当前中国城市发展的城市分类为:250万人口以上为特大城市,100—250万人口为大城市,30—100万人口为中等城市,10—30万人口为小城市,10万人口以下为小城镇。基于这个分类,中国城市发展应走多元化道路,城市系统和农村集镇系统将互相配合,共同发展,城市化进程还将具有阶段性和地域差异的特性。  相似文献