Magnetic, Geochemical and Mineralogical Charac teristics of Soils in Qiangtang Basin, Tibet, China: Implications for Prospective Oil and Gas Land     

Liu Qingsheng Department of Geophysics  China University of Geosciences  Wuhan  The State Key Laboratory of Oil/Gas Reservoir Geology  Exploitation of China  Institute of Chengdu Technology  Chengdu Wu Qifan Li Haixia Department o 《中国地质大学学报(英文版)》2001,12(2)

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Patterns and processes of mercury release from leaves of two dominant salt marsh macrophytes,Phragmites australis andSpartina alterniflora     

Lisamarie Windham  Judith S. Weis  Peddrick Weis 《Estuaries and Coasts》2001,24(6):787-795

The release of mercury (Hg) from leaf tissue was compared between two dominant salt marsh macrophytes,Spartina alterniflora andPhragmites australis. Rates of Hg release were measured for individual leaves from late May to late July, along with concentrations of Hg in leaf tissue, rates of sodium (Na) release, and rates of transpiration. Leaves ofS. alterniflora consistently releasd 2–3 times more Hg than leaves ofP. australis. Leaves ofS. alterniflora also contained greater concentrations of Hg during these months. In contrast toP. australis leaves, rates of Na release were high forS. alterniflora and were correlated with rate of Hg release. Transpiration rates averaged 2.2 times greater forPhragmites as compared toS. alterniflora, and were not correlated with the other variables at the leaf level for either species. Leaf Hg concentration was highly correlated with Hg release for both species, but the slope was significantly greater forS. alterniflora. Monthly differences were profound for all climate and physiological variables measured, with high measurements in May, and lower measurements in June and July. For both species, the highest Hg content was found in lower leaves in May, followed by upper leaves in May. Hg accumulation in leaf tissue and release from both species appear to be greatest in the spring, although differences between the species persist throughout these peak months of the growing season.  相似文献   

METEORS AND METEORITES IN THE ANCIENT NEAR EAST     

Judith Kingston Bjorkman 《Meteoritics & planetary science》1973,8(2):91-130

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Is the invasion of the common reed,Phragmites australis,into tidal marshes of the eastern US an ecological disaster?     

Weis JS  Weis P 《Marine pollution bulletin》2003,46(7):816-820

Studies of effects of the invasive brackish marsh plant Phragmites australis (common reed) on estuarine biota are reviewed. With few exceptions, most field studies indicate that these P. australis-dominated marshes have diverse and abundant benthic biota, and are utilized by nekton, comparable to Spartina alterniflora marshes. However, larval mummichogs, Fundulus heteroclitus, appear to be reduced in P. australis marshes compared with S. alterniflora marshes. Small epifauna living on plant stems also appear to be denser on S. alterniflora than P. australis stems. Other studies indicate that the detritus produced by decaying P. australis litter provides food value comparable to that of S. alterniflora and that its production enters estuarine food webs. Therefore, the general assumption that these marshes are ecologically "useless" is untrue. This information should be considered by marsh managers when making decisions about restoration projects.  相似文献   

Methane in an acidic bog lake: The influence of peat in the catchment on the biogeochemistry of methane   总被引：3，自引：0，他引：3  

Peter Casper  On Chim Chan  Andre L. S. Furtado  Donald D. Adams 《Aquatic Sciences - Research Across Boundaries》2003,65(1):36-46

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Application of multiple sublethal stress indicators to assess the health of fish in Pamlico Sound following extensive flooding   总被引：1，自引：0，他引：1  

S.?Marshall?AdamsEmail author  Mark?S.?Greeley  J.?McHugh?Law  Edward?J.?Noga  Judith?T.?Zelikoff 《Estuaries and Coasts》2003,26(5):1365-1382

Multiple indicators of sublethal stress (bioindicators) were used to assess the health and condition of two important estuarine fish species in the Pamlico Sound estuary following extensive flooding from three sequential hurricanes that occurred during early fall 1999. Bioindicators ranging from the biochemical to the reproductive and organism-level were used to assess the health of southern flounder and spot in Pamlico Sound compared to the health of these same species sampled from a relatively unaffected references site in lower Core Sound. Many of the physiological, reproductive, immunological, histopathological, and general condition indices suggested that both species, and particularly spot, in Pamlico Sound were sublethally stressed and in poorer condition than fish sampled from Core Sound. The major environmental stressors causing these sublethal stress responses in Pamlico Sound fish appears to be those related to episodic hypoxic exposure or a combination of effects associated with hypoxic conditions such as alterations in preferred habitat and food availability. Although fish populations in Pamlico Sound do not appear to be severely damaged or impaired at this time, organisms that are sublethally stressed can incur increased vulnerability to additional or future stressors such as modified physicochemical regimes, changes in food and habitat availability, and increases in infectious pathogens. Because of the low flushing rate (～1 yr) of Pamlico Sound, recovery rate may be exceptionally slow, prolonging any adverse effects of altered nutrient regimes (such as hypoxia) on the health and fitness of resident fish populations. Flooding from the 1999 hurricanes may have contributed to the short-term health and condition of finfish species in Pamlico Sound and also influenced longer-term recovery and ecological status of this system. Longer-term manifestation of effects from flooding may be of particular concern as the frequency of hurricanes is expected to increase over the next few years and the accelerated uses of the coastal zone places further stress on estuarine resources.  相似文献   

Mercury uptake by the estuarine species Palaemonetes pugio and Fundulus heteroclitus compared with their parasites,Probopyrus pandalicola and Eustrongylides sp     

Bergey L  Weis JS  Weis P 《Marine pollution bulletin》2002,44(10):1046-1050

When exposed to methylmercury in the laboratory, grass shrimp, Palaemonetes pugio, parasitized by the isopod Probopyrus pandalicola, accumulated lower concentrations of mercury than their unparasitized counterparts. The parasitic isopod accumulated far less mercury than the grass shrimp. When exposed to mercury in a contaminated field site, mummichogs, Fundulus heteroclitus, parasitized with the nematode Eustrongylides, similarly accumulated lower concentrations of mercury than unparasitized fish, and the parasite similarly accumulated less than the host. The lower uptake by the parasites compared to their hosts is counter to the general view of biomagnification of methylmercury, since parasites are a trophic level above their hosts. The mechanism whereby parasitized animals accumulate less toxicant than unparasitized ones is unknown, but may be partially due to lower metabolic rate.  相似文献   

Communicating academic geography—the continuing challenge     

Jon Shaw  Judith Matthews 《Area》1998,30(4):367-372

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Phthalate ester plasticizers,DDT, DDE and polychlorinated biphenyls in biota from the Gulf of Mexico     

C.S Giam  H.S Chan  G.S Neff 《Marine pollution bulletin》1978,9(9):249-251

The levels of phthalate ester plasticizers, DDT, DDE and polychlorinated biphenyls (PCBs) were determined in the tissues of 18 species of marine organisms from the northwestern Gulf of Mexico. Low levels of the most widely used phthalate, di-(2-ethylhexyl) phthalate, were found in the majority of the samples; no other phthalates were detected. DDT, DDE and PCBs were found in all samples, but at somewhat lower levels than those found in our 1971 survey. A decrease in p,p′-DDT/p,p′-DDE ratios relative to 1971 was also noted.  相似文献   

Effects of bottom sediments on the survival of Enterobacter aerogenes in seawater     

Kwong-Yu Chan  S.H. Wong  C.Y. Mak 《Marine pollution bulletin》1979,10(7):205-210

The survival of the coliform bacterium Enterobacter aerogenes in seawater was greatly affected by the underlying bottom sediments. The presence of sediments which contained higher concentrations of organic nutrients than the overlaying seawater prolonged the survival and even enabled growth of the bacterial cells. Results obtained from chemical analysis indicated that sediments of fine-grained, silt-clay type contained highest amounts of organic nutrients as compared with sediments with larger particle sizes such as silt and sand grains. Thus, nutrient contents of the sediments were found to be inversely proportional to sediment particle size. The degree of prolonged survival of E. aerogenes was also found to be inversely proportional to the size of the sediment particles presented. Release of the bound nutrients which became available to cells of E. aerogenes from sediments by action of waves and human activities can explain, at least in part, why high counts of coliform bacteria are obtained in coastal and beach waters.  相似文献