排序方式: 共有38条查询结果,搜索用时 15 毫秒
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ICES baseline survey of trace metals in European shelf waters 总被引:1,自引:0,他引:1
Balls P.; Cofino W.; Schmidt D.; Topping G.; Wilson S.; Yeats P. 《ICES Journal of Marine Science》1993,50(4):435-444
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J.M. Bewers P.A. Yeats S. Westerlund B. Magnusson D. Schmidt H. Zehle S.S. Berman A. Mykytiuk J.C. Duinker R.F. Nolting R.G. Smith H.L. Windom 《Marine pollution bulletin》1985,16(7):277-281
Filtration systems, used for the preparation of coastal seawater samples for trace analysis, have been intercompared to determine the extent of contamination arising during the filtration process. The results show that all the systems intercompared are able to provide uncontaminated filtrates for copper, nickel, cobalt and manganese and, with two exceptions, for cadmium and iron, at levels that would be encountered in uncontaminated coastal waters. 相似文献
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A study of dissolved chromium in the St. Lawrence estuary and Gulf of St. Lawrence has been carried out. A chromium concentration of 0·7 μg l?1 was found in the St. Lawrence River. In the turbidity maximum of the upper estuary, chromium is removed from solution onto fine-grained resuspended sediments and internally produced organic-rich floccules. A simple flux calculation shows that these processes remove ~50% of the total dissolved chromium input of the river. At salinities greater than 5‰ dissolved chromium mixes conservatively. 相似文献
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Precipitation of heavy metals in produced water: influence on contaminant transport and toxicity 总被引:1,自引:0,他引:1
Azetsu-Scott K Yeats P Wohlgeschaffen G Dalziel J Niven S Lee K 《Marine environmental research》2007,63(2):146-167
Produced water undergoes changes in its physical chemistry including precipitation of heavy metals after being discharged and mixed with ambient seawater. Potential impacts of the precipitation of heavy metals on their transport and toxicity were studied using samples from offshore oil production sites on the Scotian Shelf off eastern Canada. Concentrations of aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel and zinc were measured in total, particulate and dissolved fractions together with Microtox tests for assessment of toxicity. Heavy metals in produced water were transformed from dissolved to particulate phase in a period of hours under oxygenated conditions, and aggregated to larger particles that settle rapidly (>100 m/day) over a few days. In addition, there was production of buoyant particles comprised of heavy metal precipitates sequestered onto oil droplets that were transported to the surface. The particulate fraction was generally more toxic than the dissolved fraction. This was evident at the mixing interface between produced water and seawater where elevated particulate and toxicity levels were observed. Laboratory studies suggest an increase in the toxicity of discharged produced water over time. Time-series experiments showed a sustained toxic response for more than a week following the oxidation of freshly discharged produced water that initially elicited little or no toxic response in the Microtox test. Chemical processes identified in this study, namely precipitation of heavy metals and consequent settling and rising fluxes of particles, will influence the toxicity, the fate and the transport of potential contaminants in the produced water. Therefore, these processes need to be considered in assessment of the environmental impact associated with offshore oil and gas operations. 相似文献
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Annemarie Christophersen Nicola Litchfield Kelvin Berryman Richard Thomas Roberto Basili Laura Wallace William Ries Gavin P. Hayes Kathleen M. Haller Toshikazu Yoshioka Richard D. Koehler Dan Clark Monica Wolfson-Schwehr Margaret S. Boettcher Pilar Villamor Nick Horspool Teraphan Ornthammarath Ramon Zuñiga Robert M. Langridge Mark W. Stirling Tatiana Goded Carlos Costa Robert Yeats 《Natural Hazards》2015,79(1):111-135
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Christopher J. Yeats Ernst A. Kohler Neal J. McNaughton Luke J. Tkatchyk 《Mineralium Deposita》2001,36(2):125-136
The 7 million oz. Jundee–Nimary lode-gold deposit occurs in the northern portion of the Yandal greenstone belt in the northeastern
part of the Archean Yilgarn Craton of Western Australia. Gold mineralization at Jundee–Nimary is similar in structural style,
mineralogy, geochemistry and relative timing with respect to deformation and metamorphism, to other Western Australian Archean
greenstone-hosted gold deposits, but is unusual in the fact that mineralized structures are crosscut by structurally late
intermediate to felsic dykes. Within the Deakin South open cut, gold mineralization is hosted in brittle–ductile shear zones
primarily developed within the dacitic Mitchell Porphyry. The Moore Porphyry, a broad dyke of porphyritic granodiorite, intrudes
the Mitchell Porphyry, crosscutting and post-dating gold mineralization. Analytically indistinguishable SHRIMP U–Pb zircon
ages of 2678 ± 5 Ma for the Mitchell Porphyry and 2669 ± 7 Ma for the Moore Porphyry require that gold mineralization at Jundee–Nimary
occurred at ca. 2680–2660 Ma, approximately 40 million years earlier than the majority of published robust ages for gold mineralization
in the Yilgarn Craton, which mostly overlap at ca. 2640–2630 Ma. The close spatial and temporal relationship between gold
mineralization and felsic to intermediate magmatism at Jundee–Nimary also raises the possibility of a genetic link between
hydrothermal and igneous activity. However, additional work is required to establish a firm connection. Current research on
lode-gold mineralization in Archean, Paleozoic and Phanerozoic terranes suggests a model which postulates that these deposits
formed during transpressional to compressional deformation in accretionary and collisional orogens and that their formation
is intimately related to orogenic processes. Consequently, mineralization and regional metamorphism are expected to be diachronous,
as terranes are accreted and the front of orogenesis migrates. Consideration of the new data presented in this paper in conjunction
with previously published dates supports the hypothesis that gold mineralization, along with regional metamorphism, was generally
diachronous from northeast to southwest across the Yilgarn Craton, over a period of approximately 40 million years from ca.
2680–2660 Ma to ca. 2640–2630 Ma. This is directly analogous to the accepted model for the timing of orogenic lode-gold mineralization
in other provinces and therefore provides further support for a unified model for this style of deposit through geological
time.
Received: 17 March 2000 / Accepted: 8 September 2000 相似文献