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21.
22.
Using meteorological observer data to compare wind erosion during two great droughts in eastern Australia; the World War II Drought (1937–1946) and the Millennium Drought (2001–2010) 下载免费PDF全文
Tadhg O'Loingsigh Grant H. McTainsh Katherine Parsons Craig L. Strong Phil Shinkfield Nigel J. Tapper 《地球表面变化过程与地形》2015,40(1):123-130
Australian meteorological observers started using the World Meteorological Organization (WMO) weather coding system in the 1950s. This system is still in use around the world today. However, observing and recording the weather in an organized and systematic manner had been ongoing for over 100 years prior to the adoption of this coding system, and much like Australia, most countries will have historical meteorological records. In this paper we compare the wind erosion of two of the greatest droughts in Australian recorded history; the World War II (WWII) Drought (1937–1945) and the Millennium Drought (2001–2009). To do this we analysed previously unavailable meteorological observer records from the Australian Bureau of Meteorology (ABM). Wind erosion records, mostly in long‐hand written form, were translated to the modern WMO coding system for the WWII Drought and compared with the wind erosion of Australia's recently‐ended Millennium Drought, one of the longest and harshest on record. We quantify wind erosion using Dust Event Days (DED) and a modified version of a published Dust Storm Index (DSI) to show that wind erosion during the WWII Drought was up to 4.6 times higher than during the Millennium Drought. This study has international significance because it demonstrates a methodology for tracking changes in wind erosion over the past 75 years based on observer records available in every country with a history of organized weather observation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
23.
I. Leya H‐J. Lange M. LÜPke U. Neupert R. Daunke O. Fanenbruck R. Michel R. R
Sel B. Meltzow T. Schiekel F. Sudbrock U. Herpers D. Filges G. Bonani B. Dittrich‐Hannen M. Suter P. w. Kubik H‐a. Synal 《Meteoritics & planetary science》2000,35(2):287-318
Abstract— Thick spherical targets made of gabbro (R = 25 cm) and of steel (R = 10 cm) were irradiated isotropically with 1.6 GeV protons at the Saturne synchrotron at Laboratoire National Saturne (LNS)/CEN Saclay in order to simulate the interaction in space of galactic cosmic‐ray (GCR) protons with stony and iron meteoroids. Proton fluences of 1.32 × 1014 cm?2 and 2.45 × 1014 cm?2 were received by the gabbro and iron sphere, respectively, which corresponds to cosmic‐ray exposure ages of about 1.6 and 3.0 Ma. Both artificial meteoroids contained large numbers of high‐purity target foils of up to 28 elements at different depths. In these individual target foils, elementary production rates of radionuclides and rare gas isotopes were measured by x‐ and γ‐spectrometry, by low‐level counting, accelerator mass spectrometry (AMS), and by conventional rare gas mass spectrometry. Also samples of the gabbro itself were analyzed. Up to now, for each of the experiments, ~500 target‐product combinations were investigated of which the results for radionuclides are presented here. The experimental production rates show a wide range of depth profiles reflecting the differences between low‐, medium‐, and high‐energy products. The influence of the stony and iron matrices on the production of secondary particles and on particle transport, in general, and consequently on the production rates is clearly exhibited by the phenomenology of the production rates as well as by a detailed theoretical analysis. Theoretical production rates were calculated in an a priori way by folding depth‐dependent spectra of primary and secondary protons and secondary neutrons calculated by Monte Carlo techniques with the excitation functions of the underlying nuclear reactions. Discrepancies of up to a factor of 2 between the experimental and a priori calculated depth profiles are attributed to the poor quality of the mostly theoretical neutron excitation functions. Improved neutron excitation functions were obtained by least‐squares deconvolution techniques from experimental thick‐target production rates of up to five thick‐target experiments in which isotropic irradiations were performed. A posteriori calculations using the adjusted neutron cross sections describe the measured depth profiles of all these simulation experiments within 9%. The thus validated model calculations provide a basis for reliable physical model calculations of the production rates of cosmogenic nuclides in stony and iron meteorites as well as in lunar samples and terrestrial materials. 相似文献
24.
We present a high‐resolution record of lacustrine sedimentation spanning ca. 30 000 to 9000 cal. a BP from Onepoto maar, northern North Island, New Zealand. The multi‐proxy record of environmental change is constrained by tephrochronology and accelerator mass spectrometric 14C ages and provides evidence for episodes of rapid environmental change during the Last Glacial Coldest Period (LGCP) and Last Glacial–Interglacial Transition (LGIT) from northern New Zealand. The multi‐proxy palaeoenvironmental record from Onepoto indicates that the LGCP was cold, dry and windy in the Auckland region, with vegetation dominated by herb and grass in a beech forest mosaic between ca. 28 500 and 18 000 cal. a BP. The LGCP was accompanied by more frequent fires and influx of clastic sediment indicating increased erosion during the LGCP, with a mid‐LGCP interstadial identified between ca. 25 000 and 23 000 cal. a BP. Rapid climate amelioration at ca. 18 000 cal. a BP was accompanied by increased terrestrial biomass exemplified by the expansion of lowland podocarp forest, especially Dacrydium cupressinum. Increasing biomass production is reversed briefly by LGIT perturbations which are apparent in many of the proxies that span ca. 14 000–10 500 cal. a BP, suggesting generally increased wetness and higher in situ aquatic plant productivity with reduced terrestrial organic matter and terrigenous detrital influx. Furthermore, conditions at that time were probably warmer and frosts rare based on the increasing importance of Ascarina. The subsequent early Holocene is characterised by podocarp conifer forest and moist mild conditions. Postglacial sea‐level rise breached the crater rim and deposited 36 m of estuarine mud after ca. 9000 cal. a BP. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
25.
26.
Keith D. Suter 《Marine Policy》1983,7(3):213-215
Disarmament has again become a major public concern in many nations. The main manifestations of this development have been demonstrations and marches and mass media attention to the possible consequences of a nuclear war. Less publicized has been governmental work, including that at the United Nations, in negotiating disarmament treaties. 相似文献
27.
J. Rajesh Banu M.Sc M.Phil. Ph.D. S. Kaliappan B.E. M.E. Ph.D. D. Beck 《International Journal of Environmental Science and Technology》2006,3(1):69-77
Sago industry is one of the major small-scale sectors in India and over 800 units are located in the southern State of Tamilnadu. Processing of sago generates enormous quantities of high strength wastewater requiring systematic treatment prior to disposal. The present study is an attempt to treat the sago wastewater using Hybrid Upflow Anaerobic Sludge Blanket (HUASB) reactor, which offers the advantages of both fixed film and up flow anaerobic sludge blanket treatment. HUASB reactor with a volume of 5.6 L was operated at Organic Loading Rates varying from 10.7 to 24.7 kg COD/m3.day. After 130 days of startup, the reactor produced appreciable decrease in COD of wastewater and removed solids efficiently. The COD removal varied from 91–87%. While the removal of Total Solids was in the range of 61–57%, that of volatile solids varied from 70–67%. The ideal OLR for the reactor was 23.5 kg COD/m3.day. The findings of the study open up newer possibilities of design low cost and compact onsite treatment systems with very short retention periods. 相似文献
28.
M. A. Ashraf M.Phil M. J. Maah I. Yusoff Ph.D. 《International Journal of Environmental Science and Technology》2010,7(3):581-590
Unfertilizable fruiting buds of mango plant Mangifera Indica L, an agrowaste, is used as a biomass in this study. The efficacy of the biosorbent was tested for the removal of lead, copper, zinc and nickel metal ions using batch experiments in single and binary metal solution under controlled experimental conditions. It is found that metal sorption increases when the equilibrium metal concentration rises. At highest experimental solution concentration used (150 mg/L), the removal of metal ions were 82.76 % for lead, 76.60 % for copper, 63.35 % for zinc and 59.35 % for nickel while at lowest experimental solution concentration (25 mg/L), the removal of metal ions were 92.00% for lead, 86.84 % for copper, 83.96 % for zinc and 82.29 % for nickel. Biosorption equilibrium isotherms were plotted for metal uptake capacity (q) against residual metal concentrations (Cf) in solution. The q versus Cf sorption isotherm relationship was mathematically expressed by Langmuir and Freundlich models. The values of separation factor were between zero and one indicating favourable sorption for four tested metals on the biosorbent. The surface coverage values were approaching unity with increasing solution concentration indicating effectiveness of biosorbent under investigation. The non-living biomass of Mangifera indica L present comparable biosorption capacity for lead, copper, zinc and nickel metal ions with other types of biosorbent materials found in literature and is effective to remove metal ions from single metal solutions as well as in the presence of other co-ions with the main metal of solution. 相似文献
29.
D. Dhanasekaran Ph.D. N. Thajuddin Ph.D. M. Rashmi M.Sc. M.Phil. T. L. Deepika M.Sc. M. Gunasekaran Ph.D. 《International Journal of Environmental Science and Technology》2009,6(2):197-202
Biofouling is the undesirable accumulation of microorganisms, plants, algae and animals on submerged structures especially ship hulls. Biofouling also occurs on the surface of living marine organisms. It is also found on membrane systems such as membrane bioreactors and reverse osmosis spiral wound membranes. In the same manner, it is found in cooling water cycles of large industrial equipments and power stations. In the present study, totally 11 isolates were obtained from three ships from Royapuram harbour, Chennai, Tamil Nadu, India. Among the 11 isolates only DR4 showed maximum biofouling activity in the microtiter plate assay with a significant optical density of 0.596. Also an attempt was made to characterize the different biofouling bacterial isolates analyzing their morphological, biochemical and molecular characteristics. The results of the present study based on the above characteristics revealed that the isolate DR4 was similar to Bacillus sp. This study also highlights the need for a safe and natural antifouling agent to control the biofouling bacteria in the marine environment. 相似文献
30.
Sonia Tonarini William P. Leeman Phil T. Leat 《Earth and Planetary Science Letters》2011,301(1-2):275-284
The South Sandwich volcanic arc is sited on a young oceanic crust, erupts low-K tholeiitic rocks, is characterized by unexotic pelagic and volcanogenic sediments on the down-going slab, and simple tectonic setting, and is ideal for assessing element transport through subduction zones. As a means of quantifying processes attending transfer of subduction-related fluids from the slab to the mantle wedge, boron concentrations and isotopic compositions were determined for representative lavas from along the arc. The samples show variable fluid-mobile/fluid-immobile element ratios and high enrichments of B/Nb (2.7 to 55) and B/Zr (0.12 to 0.57), similar to those observed in western Pacific arcs. δ11B values are among the highest so far reported for mantle-derived lavas; these are highest in the central part of the arc (+ 15 to + 18‰) and decrease toward the southern and northern ends (+ 12 to + 14‰). δ11B is roughly positively correlated with B concentrations and with 87Sr/86Sr ratios, but poorly coupled with other fluid-mobile elements such as Rb, Ba, Sr and U. Peridotites dredged from the forearc trench also have high δ11B (ca. + 10‰) and elevated B contents (38–140 ppm). Incoming pelagic sediments sampled at ODP Site 701 display a wide range in δ11B (+ 5 to ? 13‰; average = ? 4.1‰), with negative values most common. The unusually high δ11B values inferred for the South Sandwich mantle wedge cannot easily be attributed to direct incorporation of subducting slab materials or fluids derived directly therefrom. Rather, the heavy B isotopic signature of the magma sources is more plausibly explained by ingress of fluids derived from subduction erosion of altered frontal arc mantle wedge materials similar to those in the Marianas forearc. We propose that multi-stage recycling of high-δ11B and high-B serpentinite (possibly embellished by arc crust and volcaniclastic sediments) can produce extremely 11B-rich fluids at slab depths beneath the volcanic arc. Infiltration of such fluids into the mantle wedge likely accounts for the unusual magma sources inferred for this arc. 相似文献