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431.
The effects of Sphagnum and urban runoff on the bioavailability of metals were tested by adding PbCl2 and ZnCl2 to laboratory microcosms constructed of peat substrate with or without live Sphagnum spp. and planted with Acer rubrum L. seedlings or Vaccinium macrocarpon Ait. shoots. We hypothesized that Sphagnum would increase bioavailability through its acidifying action, while urban runoff would decrease availability through increases in alkalinity. Metals were more available to the test plants treated with acidic swampwater than with alkaline runoff. Sphagnum moss caused increases in tissue concentrations in V. macrocarpon, but not in A. rubrum. The latter species took up more metals when grown on substrate from sites receiving runoff, whereas the former took up more metals from substrate from undisturbed sites, despite the lower substrate metal concentrations. Differences in uptake by the two species may reflect differences in their ability to root in the Sphagnum mat. The results demonstrate that Sphagnum spp. exerts strong species-specific effects on the uptake of metals by vascular plants, and that plant species native to acidic wetlands vary widely in their response to metals in the substrate.  相似文献   
432.
Effects of increased ozone (O3) and carbon dioxide (CO2) on polyamine levels were determined in soybean (Glycine max L. Merr. cv. Clark) grown in open-top field chambers. The chamber treatments consisted of three O3 regimes equal to charcoal filtered (CF), non-filtered (NF), and non-filtered plus 40 nl litre(-1) O3 and CO2 treatments equal to 350, 400 and 500 microl litre(-1) for a total of nine treatments. Leaf samples were taken at three different times during the growing season. Examination of growth and physiological characteristics, such as photosynthesis, stomatal resistance, and shoot weight, revealed that increasing CO2 ameliorated the deleterious effects of increased O3. Results from the initial harvest, at the pre-flowering growth stage (23 days of treatment), showed that increasing O3 at ambient CO2 caused increases in putrescine (Put) and spermidine (Spd) of up to six-fold. These effects were lessened with increased CO2. Elevated CO2 increased polyamines in plants treated with CF air, but had no effect in the presence of ambient or enhanced O3 levels. Leaves harvested during peak flowering (37 days of treatment) showed O3-induced increases in Put and Spd at ambient CO2 concentrations. However, increased CO2 levels inhibited this response by blocking the O3-induced polyamine increase. Leaves harvested during the pod fill stage (57 days of treatment) showed no significant O3 or CO2 effects on polyamine levels. Our results demonstrate that current ambient O3 levels induce the accumulation of Put and Spd early in the growing season and that further increases in O3 could result in even greater polyamine increases. These results are consistent with a possible antiozonant function for polyamines. The ability of increased CO2 to protect soybeans from O3 damage, however, does not appear to involve polyamine accumulation.  相似文献   
433.
The many abandoned base metal mines of the mid-Wales ore field are sources of extensive pollution. Some of the mineralised veins contain large amounts of pyrite and marcasite and oxidative weathering of these produces sulphuric acid resulting in very acidic mine drainage waters. In addition, the spoil tips associated with these mines can contain abundant iron sulphides. Drainage waters from these sources have pH values as low as 2.6 and are heavily contaminated with metals such as Al, Zn, Cd and Ni.Two of the main rivers of the area, the Rheidol and Ystwyth, intercept heavily contaminated acidic drainage which has a marked effect on water quality. The Rheidol contains over 100 g L–1 Zn for 16 km downstream of the acid water influx. This level is over three times the recommended EEC limit for Zn in salmonoid waters of low hardness.  相似文献   
434.
Summary Genetic parentage of 135 nestlings from 27 broods of polygynous and monogamous pied flycatchers Ficedula hypoleuca was analyzed by means of multilocus DNA fingerprinting. The minisatellite probe alpha-globin 3HVR detected approximately 12 scorable bands per fingerprint, and the proportion of bands shared between presumably unrelated adults averaged 0.22+0.08 SD. The fingerprints of 125 of the 135 nestlings made a complete match to those of their putative parents. In 4 nestlings a single mismatched band occurred, but since band sharing with both putative parents was high, the single mismatches were assumed to be caused by mutation. The 6 remaining nestlings had 5 or more mismatched bands each, low band-sharing proportions with their putative father and high band-sharing proportions with their putative mother. We thus conclude that they were all sired through extra-pair copulations (EPCs). Hence, only 4% of nestlings were sired through EPCs, and none resulted from intraspecific brood parasitism. One of the cuckolding males was identified, explaining all 5 mismatched bands in the nestling's fingerprint. Three of the illegitimate nestlings were from primary nests of polygynous males; 3 were from nests of monogamous males. The fact that many males in this study started to advertise for a second female in a distant territory several days before their first mate began egglaying, and still managed to secure almost exclusive paternity in their first brood, suggests that male polyterritoriality is not costly in terms of lost paternity. Common anti-cuckoddry tactics performed by male birds, like high rate of within-pair copulation and continuous mate-guarding thoughout the female's fertilizable period, do not seem to be important in pied flycatchers.Offprint requests to: J.T. Lifjeld  相似文献   
435.
Summary We tested the hypothesis that song attracts females and repels males in the European starling. We broadcast recorded song from speakers attached to nestboxes, while paired boxes with silent speakers served as controls. As predicted, females were attracted to the song boxes. Contrary to prediction, males were also attracted to the `song' boxes. Singing by male starlings may be costly because it attracts competitors for limited nesting sites, but the cost cannot be avoided due to the need to attract a mate. In a second experiment simple song (composed of 20 different phrase types) and complex song (40 phrase types) were played simultaneously. More males were captured at boxes where simple song was played. Song complexity may function as an indicator of male quality and be used by male starlings to assess potential competitors.  相似文献   
436.
Lead and zinc effects on Bufo arenarum larval survival were studied in single and combined treatments. On a weight basis, lead is about twice as toxic as zinc. The antagonism or synergism between these heavy metals is dose-dependent.  相似文献   
437.
This paper provides a summary of the results of an 18-month study conducted by Clean Sites, Inc. of Alexandria, Virginia. The study was designed to take a critical look at the way remedies are selected for abandoned hazardous waste sites that are cleaned up under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) and to develop recommendations for improving that process. The recommendations were released in an October 1990 report entitled "Improving Remedy Selection: An Explicit and Interactive Process for the Superfund Program." Through a cooperative agreement with the U.S. Environmental Protection Agency, Clean Sites is working to test these recommendations. At two actual Superfund sites, Clean Sites will assist EPA in performing the remedy selection in accordance with the process Clean Sites has developed.  相似文献   
438.
There has been an increasing awareness of potential impacts of herbicide drift on to vegetation in nature reserves and field margin habitats adjacent to treated areas. Previous work using single species bioassays has suggested that the effects of a single drift event are confined close to the sprayer (< 10 m). In the present study eight native dicotyledonous species, with and without a perennial grass (Lolium perenne), were grown in standardized microcosms in order to study (1) the effects of herbicide drift where plants were exposed to competition, and (2) the effects of a second spray application. The microcosms were arranged downwind (0-8 m) of a standard agricultural sprayer applying mecoprop at recommended rates. The effects of the herbicide drift on foliar symptoms of plant damage and end-of-season yield were assessed in each of two years. The main conclusions were that (1) growth of Stachys sylvatica and Lolium perenne (where sown) was enhanced near the sprayer and, (2) six other species (Digitalis purpurea, Galium mollugo, Hypericum hirsutum, Lychnis flos-cuculi, Primula veris and Ranunculus acris) showed some evidence of reduction in either performance (assessed non-destructively after a single exposure) or yield after two exposures. Three species (Lychnis flos-cuculi, Primula veris and Ranunculus acris) showed a reduction in flowering performance. Thus, mecoprop drift affected the aesthetic appearance, possibly the fecundity of some species and the balance between species in these microcosm experiments. The implications of these results for the persistence of attractive plant communities in sensitive areas are discussed.  相似文献   
439.
Taylor AJ 《Disasters》1990,14(4):291-300
Two three-dimensional conceptual models are presented that should help those concerned with disasters and disaster victims to integrate the numerous studies on the topic. The first, concerning disasters, involves matters ecological, technological and social scientific. It covers the elements earth, air, fire, water/liquid, and people. It includes the time dimensions of preparedness, response, recovery and mitigation. The second introduces a six-fold classification of victims, together with dimensions to cover the methods and kinds of delivery of different interventions that might be made available to help them. The suggestion is that, were the appropriately noted victim model placed within the larger disaster model according to the types of disaster study being examined, there might be useful academic, political, and professional implications.  相似文献   
440.
本文研究了钴(Ⅱ)催化过氧化氢氧化苯基荧光酮的褪色反应,测定了反应级数和表观活化能,建立了测定痕量地的新方法。25℃时本法检出限为29×10-13g/ml,线性范围为0.04~2ng/10ml,催化反应表观活化能为56.15KJ/mol。该方法己用于维生素B12、人发和茶叶中痕量钴的测定.结果满意,相对标准偏差为2.4~3.4%。  相似文献   
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