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751.
Patterns of soil copper contamination have been examined in the vicinity of a copper rod rolling plant in Prescot, Merseyside, UK. The site, established in 1975, was found to possess clear patterns of soil copper contamination, with the highest levels of HNO3 and water-extractable fractions encountered in the factory grounds adjacent to the location of the furnace chimney. The majority of the copper had accumulated in the upper soil horizons. The site is surrounded by planted lawns, established at different times after the commissioning of the plant. The species composition of the extant grassland communities, found at sites with differing soil copper levels, was compared to the composition of the original seed mixtures sown at each of ten sites. These surveys clearly showed that different levels of soil copper contamination had produced significant changes in grassland composition with time. At the most polluted site, copper tolerant Agrostis capillaris clones were the main grasses present only two years after the area was sown with a four-species mixture of non-tolerant grass seed. Lolium perenne possessed extreme sensitivity to copper. A number of dicotyledonous species, normally considered sensitive to elevated copper levels, were found to be unaffected where such conditions had arisen after plants had established from seed.  相似文献   
752.
The phosphatic mineral, hydroxyapatite, and two ion exchange resins have been used as artificial sediment particles. The surface properties of these materials have been studied using the Langmuir adsorption isotherm to calculate the binding capacity (B(max)) and the adsorption constant (K(L)) for zinc and cadmium ions. Mussels (Mytilus edulis) were fed on the particles and their digestive glands were subsequently removed and subjected to cell fractionation. The supernatant fraction was used to determine cytosol metal levels as a measure of the materials absorbed from the ingested particles. The level of cytosol zinc and cadmium was correlated with the K(L) values of the artificial sediments. It is suggested that phagocytosis of sediment particles plays an important part in transferring pollutants into benthic organisms and that the efficiency of this process is related to the adsorption coefficient of the particle surfaces.  相似文献   
753.
Book reviews     
Rebuilding the City: Property‐led Urban Regeneration

P. Healey, S. Davoudi, M. O'Toole, S. Tavsanoglu & D. Usher (Eds)

London, E. & F. N. Spon, 1992, 312 pp., £30

Der Wert stadtnaher Wälder als Erholungsraum: Eine ökonomishce Analyse am Beispiel von Lugano (Value of Urban Forests as Recreational Areas: An Economic Analysis on the Case of Lugano)

Claudia Nielsen

Chur (Switzerland), Verlag Rüegger, 1992, 261 pp., SFr 48

Urban Planning under Thatcherism: The Challenge of the Market

A. Thornley

London, Routledge, 1991, 253 pp., £14.99

Sustainable Development and Urban Form, European Research in Regional Science 2

M. J. Breheny (Ed)

London, Pion, Limited, 1992, 292 pp., £28.00.

Tourism, Museums and the Local Economy: The Economic Impact of the North of England Open Air Musuem at Beamish

Peter Johnson & Barry Thomas

Cheltenham, Edward Elgar, 1992, 160 pp., £29.50  相似文献   

754.
Grafted Norway spruce trees were subjected to exposure beginning in April 1988, to one of four different air treatments in open-top chambers: Charcoal filtered air (CF), non-filtered air (NF), non-filtered air with the addition of O(3) during summer (NFO), and SO(2) plus NO(2) during winter (NFOSN). CF trees were considered as the reference group. No effects on growth parameters were observed. Samples of the two youngest needle year classes were taken late in November 1989 for enzyme determinations. The activity of ascorbic acid peroxidase (A-POD) increased the same level in all treatments, and activities of catalase and dehydroascorbic acid reductase (DHA-R) increased only in NF and NFO treatments. A higher level of activity in the NFOSN treatment was observed only for glucose-6-phosphate-dehydrogenase (Glc-6-P-DH) and non-specific peroxidase (POD). Isoelectric focusing of POD showed a changed pattern in the NFOSN treatment. Neither activity nor isoelectric focusing of superoxidase dismutase (SOD) was changed in any of the treatments.  相似文献   
755.
Endosulfan, one of the major pesticides used in cotton-growing, is of environmental concern because of its toxicity to fish and its apparent persistence in the environment. This study examines the distribution and degradation pathways for endosulfan in an aquatic system and the processes by which it is removed. In the alkaline waters of the cotton region, hydrolysis is the dominant degradation process. By this mechanism alone, the expected half-lives for the alpha- and beta-endosulfan isomers were found to be 3.6 days and 1.7 days, respectively. Partitioning studies showed, however, that the major proportion of endosulfan would associate with the sediments (log Koc(alpha) 3.6 and log Koc(beta) 4.3). Field studies confirmed the presence of high concentrations in sediments. Microcosm experiments showed that loss of endosulfan was slower than predicted from hydrolysis rates. Models are presented to explain how desorption from sediment limits the loss of endosulfan from a system.  相似文献   
756.
Forty pairs of mallards (Anas platyrhynchos) were fed 15 ppm selenium as selenomethionine for about 21 weeks during winter. Twenty pairs served as controls. At the end of 21 weeks, which coincided with the onset of the reproductive season, selenium treatment was ended. Four birds died while on selenium treatment. Treated females lost weight, and their egg-laying was delayed. Hatching success of some of the first eggs laid by selenium-treated females was lower than that of controls, and a few of these early eggs contained deformed embryos, but, after a period of about two weeks off the selenium-treated diet, reproductive success returned to a level comparable with that of controls. The return to normal reproductive success was the result of a corresponding decrease in selenium concentrations in eggs once selenium treatment ended.  相似文献   
757.
Slugs (Deroceras reticulatum and Arion subfuscus) were sampled from two distinct sites, an uncontaminated site at Dinas Powys and a Pb-contaminated, disusedmine site at Llantrisant. Batches of the slugs were exposed for ten days under laboratory conditions to an artificial diet consisting of a 5% (w/v) agar + 5% (w/v) sucrose matrix contaminated with different concentrations of Pb, as Pb (NO(3))(2). The food 'cubes' contained approximately 0, 10, 100, and 1000 microg Pb ml(-1). Tissue-Pb concentrations increased with increasing dietary-Pb concentration in both species. However, at the highest Pb exposure (1000 microg ml(-1)) the tissue-Pb concentrations in D. reticulatum and A. subfuscus sampled originally from the clean site were higher than those in their counterparts from the contaminated site, even though the Llantrisant slugs had significantly higher baseline Pb concentrations than the Dinas Powys slugs. It is suggested that these observations indicate metal tolerance phenotypically expressed as reduced accumulation in the populations with a history of Pb-exposure in their natural habitat. We discuss how biomonitoring may be affected by the way in which different slug populations deal with metals.  相似文献   
758.
Newark Bay, New Jersey, is particularly vulnerable to ecological damage from petroleum and chemical spills, as a result of the enclosed nature and shallow depth of the bay, the high frequency of shipping traffic, and the numerous chemical and petroleum transfer terminals located alongs its shores. To evaluate the potential impacts to the natural resources of this coastal estuarine ecosystem, chemical and petroleum accidents reported to the US Coast Guard (USCG) between 1982 and 1991 were compiled to determine the frequency and volume of these incidents in Newark Bay and in each of its major tributaries. Records obtained from the USCG National Response Center's computerized database indicated that more than 1453 accidental incidents, resulting in the release of more than 18 million US gallons of hazardous materials and petroleum products, occurred throughout Newark Bay during this period of time. The bulk of the materials released to the aquatic environment consisted of petroleum products, specifically No. 6 Fuel Oil (103 spills, 12 829 272 US gal) and gasoline (207 spills, 48 816 US gal). The majority of the reported incidents occurred in the Arthur Kill and its tributaries, as well as in the Kill Van Kull and the Passaic River. The results of this study indicated that the accidental discharge of petroleum and hazardous chemicals represents a significant source of chemical pollution in Newark Bay. Based on the frequency of spills and the volume of materials released to the aquatic environment, it is likely that these events are having a deleterious effect on the Newark Bay ecosystem.  相似文献   
759.
In the southern and southwestern coral reef lagoon of New Caledonia and the adjacent oceanic waters, 42 neuston samples were collected from the upper surface layer (0 to 10 cm) along nine transects from the coast to the coral barrier reef and the open ocean immediately beyond the reef, in March and April 1979. There was a progressive numerical decrease in zooplankton densities from the coast to the reef and from the reef to the open sea. Generally, 80 to 95% of the surface plankton consisted of holoplankton and 5 to 20% of meroplankton. Zooplankton was very abundant in littoral bays with a marked eutrophication. In a few samples collected in very shallow waters close to coral patches, cladocerans were numerous and constituted up to 75% of the total plankton, whilst in other samples collected above greater depths, copepods made up 60 to 85% of the total plankton. In the coral reef lagoon of south and southwest New Caledonia, typically hyponeustonic copepods (pontellids) often comprised 5% of the total copepod populations.  相似文献   
760.
Sediment-rejection rates of 22 Australian midshelf coral species were studied in situ between March and July 1988 at Lizard Island, Great Barrier Reef. Rejection rates of non-branching species were positively correlated with calice size and were faster for fine (63 to 250 m) than for coarse (500 to 1000 m) sediment at influxes of 200 mg/cm2. Increasing water turbulence was a more important influence on rejection rates for some species than for others. Most replicates of most species cleared all sediment in 2 d. Of those that did not, some Favia stelligera and Leptoria phrygia showed partial tissue death within 48 h, and Gardineroseris planulata showed partial tissue death within 6 d. Montipora aequituberculata, Porites lobata and P. lutea tolerated sediment for at least 6 d, and exhibited extensive tissue bleaching, but these tissues recovered after sediment removal. Sediment-rejection efficiency and sediment tolerance are not directly related, and wide interspecific differences may occur in both. These findings are correlated with differences in sediment-rejection mechanisms and with ecological distributions on the reef.  相似文献   
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