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电子探针分析与系列矿物研究 总被引:2,自引:0,他引:2
本文论述以电子探针为主要测试手段对下述几种系列矿物的研究成果:(1)铂族元素系列矿物的研究(包括Ru-Os-Fe金属互化物矿物系列和RuAs_2-OsAs_2二元固溶体矿物系);(2)Au-Cu系列矿物的研究;(3)黝铜矿族矿物的研究。 相似文献
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O'Leary BC Smart JC Neale FC Hawkins JP Newman S Milman AC Roberts CM 《Marine pollution bulletin》2011,62(12):2642-2648
We analysed the extent to which European politicians have adhered to scientific recommendations on annual total allowable catches (TACs) from 1987 to 2011, covering most of the period of the Common Fisheries Policy (CFP). For the 11 stocks examined, TACs were set higher than scientific recommendations in 68% of decisions. Politically-adjusted TACs averaged 33% above scientifically recommended levels. There was no evidence that the 2002 reform of the CFP improved decision-making, as was claimed at the time. We modelled the effects of such politically-driven decision-making on stock sustainability. Our results suggest that political adjustment of scientific recommendations dramatically increases the probability of a stock collapsing within 40 years.In 2012 European fisheries policy will undergo a once-a-decade reform. Ten years ago radical reforms were promised but the changes failed to improve sustainability. It is likely that the 2012 reform will be similarly ineffective unless decision-making is changed so that catch allocations are based on science rather than politics. 相似文献
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In examining ship-mediated biological invasions, most research and treatment development has focused on ballast water. Another vector that has gained attention recently is vessels arriving in a "no ballast on board" (NOBOB) condition. Such ships retain relatively small, unpumpable volumes of water and sediment in their ballast tanks. Nonetheless, these unpumpable portions can represent great ecological risk. This scenario is relevant in the Great Lakes, which have experienced a dramatic series of introductions, despite most vessels arriving there as NOBOBs since 1994. We examined shipping patterns of NOBOBs arriving to lower Chesapeake Bay to begin evaluating their risk of biopollution. Only 14% of ships arrive as NOBOBs, and of those, 17% depart to another port in the upper bay. Most NOBOBs arrive from or leave for other US ports; proximate trans-Atlantic crossings are few. Given the nature of their operations, we conclude NOBOBs may represent a risk for aquatic nuisance species invasions to Chesapeake Bay. 相似文献
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Kunito T Nakamura S Ikemoto T Anan Y Kubota R Tanabe S Rosas FC Fillmann G Readman JW 《Marine pollution bulletin》2004,49(7-8):574-587
Concentrations of trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, T-Hg, Org-Hg, Tl and Pb) were determined in liver samples of estuarine dolphin (Sotalia guianensis; n = 20), Franciscana dolphin (Pontoporia blainvillei; n = 23), Atlantic spotted dolphin (Stenella frontalis; n = 2), common dolphin (Delphinus capensis; n = 1) and striped dolphin (Stenella coeruleoalba; n = 1) incidentally caught along the coast of Sao Paulo State and Parana State, Brazil, from 1997 to 1999. The hepatic concentrations of trace elements in the Brazilian cetaceans were comparable to the data available in literature on marine mammals from Northern Hemisphere. Concentrations of V, Se, Mo, Cd, T-Hg and Org-Hg increased with increasing age in liver of both estuarine and Franciscana dolphins. Very high concentrations of Cu (range, 262-1970 microg/g dry wt.) and Zn (range, 242-369 microg/g dry wt.) were observed in liver of sucklings of estuarine dolphin. Hepatic concentrations of V, Se, T-Hg, Org-Hg and Pb were significantly higher in estuarine dolphin, whereas Franciscana dolphin showed higher concentrations of Mn, Co, As and Rb. Ratio of Org-Hg to T-Hg in liver was significantly higher in Franciscana dolphin than estuarine dolphin, suggesting that demethylation ability of methyl Hg might be lower in liver of Franciscana than estuarine dolphins. High hepatic concentrations of Ag were found in some specimens of Franciscana dolphin (maximum, 20 microg/g dry wt.), and 17% of Franciscana showed higher concentrations of Ag than Hg. These samples with high Ag concentration also exhibited elevated hepatic Se concentration, implying that Ag might be detoxified by Se in the liver. Higher correlation coefficient between (Hg+0.5 Ag) and Se than between Hg and Se and the large distribution of Ag in non-soluble fraction in nuclear and mitochondrial fraction of the liver also suggests that Ag might be detoxified by Se via formation of Ag2Se in the liver of Franciscana dolphin. 相似文献
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Sabino R Veríssimo C Cunha MA Wergikoski B Ferreira FC Rodrigues R Parada H Falcão L Rosado L Pinheiro C Paixão E Brandão J 《Marine pollution bulletin》2011,62(7):1506-1511
Whilst the potential impact on beach users from microorganisms in water has received considerable attention, there has been relatively little investigation into microbial contaminants in sand. Thirty three beaches across Portugal were analyzed during a five year period (2006-2010) to determine the presence of yeasts, pathogenic fungi, dermatophytes, total coliforms, Escherichia coli and intestinal enterococci in sand.Our results showed that 60.4% of the samples were positive for fungi and that 25.2% were positive for the bacterial parameters. The most frequent fungal species found were Candida sp. and Aspergillus sp., whereas intestinal enterococci were the most frequently isolated bacteria. Positive associations were detected among analyzed parameters and country-regions but none among those parameters and sampling period.Regarding threshold values, we propose 15 cfu/g for yeasts, 17 cfu/g for potential pathogenic fungi, 8 cfu/g for dermatophytes. Eighty four cfu/g for coliforms, 250 cfu/g for E. coli, and 100 cfu/g for intestinal enterococci. 相似文献
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Polybrominated diphenyl ethers and polychlorinated biphenyls in sediments of southwest Taiwan: regional characteristics and potential sources 总被引:1,自引:0,他引:1
Very little information is available on the contamination of coastal sediments of Taiwan by PBDEs and PCBs. In this study, we determined the concentrations of 19 PBDE and 209 PCB congeners in 57 surface sediment samples to identify the possible sources of PBDEs and PCBs. The total PBDE and PCB concentrations ranged from below detection limit to 7.73 ng/g and 0.88-7.13 ng/g, respectively; these values are within the ranges observed for most coastal sediments worldwide. The PBDE congeners were dominated by BDE-209 (50.7-99.7%), with minor contributions from penta- and octa-BDEs. The signatures of PCB congeners suggested that PCB residues in Kaohsiung coast may be the legacy of past use or the result of ongoing inputs from the maintenance, repair and salvage of old ships. Principal component analysis of the congener-specific composition of PBDEs and PCBs revealed distinct regional patterns that are related to the use of commercial products. 相似文献
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Okafor FC 《Applied geography (Sevenoaks, England)》1987,7(3):243-256
This paper measures farmland size per capita, fallow index and fragmentation index as indices of land resource depletion and population pressure in the heavily populated southeastern Awka-Nnewi of Nigeria. Population density in the area ranges from 574-2403 persons per square km, increasing annually at 3%. The soils are porous, sandy, with extensive gully erosion. Land is subdivided in each generation such that each male child receives a parcel of his father's land. There are other pressures on land parcels, notably for residential use. Soils have become depleted from intense cropping such that yams can no longer be grown and people subsist on cassava. Data were collected from 290 households in 36 towns and villages. The 3 variables were defined mathematically, and tabulated for each village. Then a correlation matrix was computed between the independent and dependent variables. All 3 variables, land per capita, fallow and land depletion, were significantly inversely correlated with population density (p.01), the fragmentation index to the greatest degree. All dependent variables were significantly and positively correlated. Scatter diagrams suggested that the worst hit areas were the central towns, and the least affected areas were the peripheral zones along the rivers and floodplains. Although federal regulations have been passed to make land redistribution easier, local custom makes it unlikely that people will resettle voluntarily to outlying areas because of traditions of land ownership. Similarly, government measures to encourage conservation and recovery of eroded land have not been successful, and food shortages are beginning to occur. 相似文献