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961.
Paoletti E Manning WJ Spaziani F Tagliaferro F 《Environmental pollution (Barking, Essex : 1987)》2007,145(3):869-873
Adult ash trees (Fraxinus excelsior L.), known to be sensitive or insensitive to ozone, determined by presence or absence of foliar symptoms in previous years, were treated with ethylenediurea (EDU) at 450 ppm by gravitational trunk infusion on six occasions at 21-day intervals in summer 2005 at Turin, Italy. At the end of the season, foliar ozone injury on EDU-treated trees was not complete, but was greatly and significantly reduced when compared to results from trees infused with water. Significant symptom reduction occurred at any crown level in the treated trees suggesting that EDU protected whole crowns. Gravitational infusion of EDU resulted in protection from ozone injury for ozone-sensitive ash trees. The amount of EDU needed to provide protection is assumed to be in the range 13-26 mg m(-2) leaf. 相似文献
962.
Deng DM Shu WS Zhang J Zou HL Lin Z Ye ZH Wong MH 《Environmental pollution (Barking, Essex : 1987)》2007,147(2):381-386
To investigate the variation of Zn and Cd accumulation and tolerance of Sedum alfredii (a newly reported Zn/Cd hyperaccumulator), field surveys and hydroponic experiments were conducted among three populations of this species: two originating from old Pb/Zn mines in Zhejiang (ZJ) and Hunan (HN) Provinces and one from a "clean" site in Guangdong (GD) Province, China. Under field conditions, up to 12,524 and 12,253 mg kg(-1) Zn, and 1400 and 97 mg kg(-1) Cd in shoots of ZJ and HN plants were recorded respectively. Under hydroponic conditions, ZJ and HN plants accumulated significantly higher Zn and Cd in their leaves and stems, and possessed significantly higher Zn and Cd tolerance than GD plants. Among the two contaminated populations, ZJ plants showed higher Cd tolerance and accumulation (in leaves) than HN plants. The present results indicate that significant differences in Zn and Cd accumulation and tolerance exist in populations of S. alfredii. 相似文献
963.
Kröger R Holland MM Moore MT Cooper CM 《Environmental pollution (Barking, Essex : 1987)》2007,146(1):114-119
The beneficial uptake of nutrients by wetland plants is countered to some extent by nutrient release back into the aquatic environment due to vegetative die-back. This current study examined whether Leersia oryzoides, a common wetland plant, exhibits luxury uptake of nutrients from simulated farm runoff. The study also tested whether with subsequent decomposition, these nutrients are released back into the water column. When exposed to elevated (>2mg/L N and P) runoff, L. oryzoides assimilated significantly higher concentrations of nitrogen (p<0.001) and phosphorus (p<0.001) in above-ground biomass as compared to non-enriched treatments (<0.05 mg/L N and P). Subsequently, senescence of enriched above-ground biomass yielded significantly higher concentrations of phosphorus (2.19+/-0.84 mg P/L). Using L. oryzoides as our model, this study demonstrates nitrogen and phosphorus sequestration during the growing season and release of phosphorus in the winter. 相似文献
964.
Ramalina maciformis and Ramalina lacera were exposed to different solutions and UV-B to seek for alterations in the PSII photosynthetic quantum yield (F(v)/F(m)), in response to chemicals and radiation. For R. maciformis, significant alterations of the F(v)/F(m) ratio occurred only in response to different bisulphite solutions. The F(v)/F(m) ratio decreased most in R. maciformis and R. lacera following exposure to 5 and 1 mM bisulphite, respectively. Significant differences in F(v)/F(m) ratios were observed for R. lacera in response to different solutions and light at different wavelengths, this being synergistic. The PSII system was unaffected by simulated acid rain in both lichens. R. maciformis, in particular, may survive limited acid rain exposure owing to high Ca oxalate accumulation. The F(v)/F(m) ratio decreased most in R. lacera following short-term exposures to CuSO(4), suggesting that this species is more sensitive to Cu ions under acidic conditions. 相似文献
965.
Otnyukova T 《Environmental pollution (Barking, Essex : 1987)》2007,146(2):359-365
Thallus morphology and element concentrations (S, Al, Fe, Sr, Mn, Ni, Zn, Cu, Pb, As, F, and Cl) were compared in samples of the fruticose lichen genus Usnea at two heights of the Abies sibirica canopy in the East Sayan Mountains (Krasnoyarsk District, Russia) sampled from three stations at 15, 25 and 35 km from Krasnoyark. Usnea species with an abnormal morphology dominated on branches in the upper canopy, 15-22 m above ground level, and normal thalli on lower tree branches, 2-5 m above ground. Abnormal thalli at the tree-top level contained higher Al, Fe, Zn, F, Sr and Pb concentrations compared with normal thalli growing below, confirming a dust impact. No such clear trend was observed between sampling stations. Crown canopy architecture, surface microtopography and the balance between the processes of deposition and the movement and loss of particles play a major role in particle interception and in pollutant delivery to Usnea. 相似文献
966.
Although Cu is phytotoxic at Cu(2+) activities as low as 1-2 microM, the effect of Cu(2+) on the nodulation of legumes has received little attention. The effect of Cu(2+) on nodulation of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) was examined in a dilute solution culture system utilising a cation exchange resin to buffer solution Cu(2+). The nodulation process was more sensitive to increasing Cu(2+) activities than both shoot and root growth; whilst a Cu(2+) activity of 1.0 microM corresponded to a 10% reduction in the relative yield of the shoots and roots, a Cu(2+) activity of 0.2 microM corresponded to a 10% reduction in nodulation. This reduction in nodulation with increasing Cu(2+) activity was associated with an inhibition of root hair formation in treatments containing > or =0.77 microM Cu(2+), rather than to a reduction in the size of the Rhizobium population. 相似文献
967.
Essential and non-essential element concentrations in two sleeper shark species collected in arctic waters 总被引:1,自引:0,他引:1
McMeans BC Borgå K Bechtol WR Higginbotham D Fisk AT 《Environmental pollution (Barking, Essex : 1987)》2007,148(1):281-290
A number of elements/metals have increased in arctic biota and are of concern due to their potential toxicity. Most studies on elements in the Arctic have focused on marine mammals and seabirds, but concentrations in the Greenland shark (Somniosus microcephalus) and Pacific sleeper shark (Somniosus pacificus), the only two shark species known to regularly inhabit arctic waters, have never been reported. To address this data gap, concentrations and patterns of 25 elements were analyzed in liver of Greenland sharks collected about Cumberland Sound (n=24) and Pacific sleeper sharks collected about Prince William Sound (n=14). Several non-essential elements differed between species/locations, which could suggest geographical exposure differences or ecological (e.g., diet) differences between the species. Certain essential elements also differed between the two sleeper sharks, which may indicate different physiological requirements between these closely related shark species, although information on such relationships are lacking for sharks and fish. 相似文献
968.
Allen YT Thain JE Haworth S Barry J 《Environmental pollution (Barking, Essex : 1987)》2007,146(1):92-99
Short-term whole sediment tests using the amphipod Corophium volutator and the polychaete Arenicola marina are now routinely used in Europe to assess the acute toxicity of marine sediments. However, there is still a need to develop longer-term assays which measure effects on sublethal endpoints that are more relevant to predicting impacts at the population level. The effect of increasing exposure times and measuring additional endpoints such as growth, on the sensitivity of these assays was investigated. The test compound used was the chemotherapeutant Ivermectin (IVM), used in aquaculture to treat sea lice infestations. IVM was found to be acutely toxic to both test organisms. Extending the lugworm test to 100 days increased sensitivity of survival by a factor of three; a significant reduction in casting rate was observed at concentrations an order of magnitude lower. This assay shows potential for detecting the sublethal effects of low concentrations of sediment contaminants. Increasing the exposure time did not seem to affect the sensitivity of the amphipod, but further method development is required. 相似文献
969.
Differential responses of the freshwater wetland species Juncus effusus L. and Caltha palustris L. to iron supply in sulfidic environments 总被引:1,自引:0,他引:1
Van der Welle ME Niggebrugge K Lamers LP Roelofs JG 《Environmental pollution (Barking, Essex : 1987)》2007,147(1):222-230
Sulfur pollution can lead to serious problems in freshwater wetlands, including phosphorus eutrophication and sulfide toxicity. We tested the effects of anaerobic iron-rich groundwater discharge in fens, simulated by iron injection, on two characteristic species (Juncus effusus and Caltha palustris) in a sulfidic environment. Biomass production of C. palustris roots showed an optimum response to the combined addition of iron and sulfide, with highest values at intermediate concentrations of both substances. Iron deficiency apparently occurred at low iron concentrations, while at high iron concentrations, growth was decreased. For J. effusus, in contrast, no toxic effects were found of both iron and sulfide. This could be explained by larger radial oxygen loss (ROL) of J. effusus and could not be explained by differences in phosphorous concentrations. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in sulfidic environments. 相似文献
970.
Dietz R Rigét FF Sonne C Letcher RJ Backus S Born EW Kirkegaard M Muir DC 《Environmental pollution (Barking, Essex : 1987)》2007,146(1):166-173
Polybrominated diphenyl ethers (PBDEs) were analysed in adipose tissue from 92 East Greenland polar bears (Ursus maritimus) sampled during 1999-2001. Mean SigmaPBDE concentrations were 70 ng/g lipid weight (lw) (range: 22-192 ng/g lw) and showed no relationship with age or sex. Of the 32 analysed PBDE congeners; BDE47, BDE153, BDE99 and BDE100 dominated, and comprised 99.6% of the SigmaPBDE concentration. The SigmaPBDE concentration had a highly significant correlation with SigmaPCB, SigmaCHL, dieldrin, HCB and SigmaHCH concentrations. We found a seasonal pattern of median SigmaPBDE concentration with 1.2 to 1.8 times higher concentrations in March to July than the rest of the year. The seasonal variation also provides a clue to the seasonal exposure, bio-availability, toxic exposure and degradation. We suggest that future geographical PBDE data comparisons may not need corrections for sex or age, but such data sets should be corrected for seasonal variability, using the presented correctional trigonometric regression. 相似文献