Otolith increment age estimates for a deepwater species, Allocyttus verrucosus, were validated by comparison with the results from 210Pb:226Ra radiometric analysis. Transverse sectioning and subsequent grinding of otoliths to a thickness of 0.2 mm revealed increments which provided age estimates for a range of fish sizes. Age estimates ranged from 7 yr for an immature fish of 15.2 cm total length (TL) to 130 yr for a female fish of 36.5 cm TL. Age at maturity was estimated as 28 yr for females and 24 yr for males. In comparison, radiometric analysis of whole otoliths, using a single linear otolith-mass growth-rate model suggested maximum ages of 130 to 170 yr for fish of 34 to 35 cm TL. Radiometric ages were also recalculated using a two-phase otolith-mass growth-rate model in which the growth rate was assumed to slow after maturity to 90% of the pre-maturity rate. This reduced the maximum age to 132±15 yr for a mean fish length of 34.5 cm. Age at maturity for females was estimated at 34 yr. The similarity between age estimates from otolith-increment counts and radiometric analysis strongly supports the accuracy of results from both methods, and encourages further use of such comparisons as an alternative to traditional validation techniques. 相似文献
Ranunculus spp. are the dominant plants of lowland chalk stream habitats in England. The spatial variability of sediment characteristics
(silt–clay, organic matter, total phosphorus and total nitrogen content) within stands of Ranunculus spp. was investigated in 12 rivers in lowland England. Variability was found to be high and there were no discernible differences
between samples taken from within Ranunculus and a limited number of samples from bare substrate. For two of these rivers, comparisons were also made between reaches
upstream and downstream of waste water treatment works outfalls in terms of the characteristics of the sediments within Ranunculus stands. In one river a clear increase in sediment nutrient, fine and organic material content was observed downstream but
in the other there was no consistent difference. Temporal variability was considered for two rivers in the Frome catchment,
Dorset, by analysing the monthly variability in sediment organic matter and silt–clay content beneath Ranunculus stands over an annual cycle of growth and die-back. Whilst a clear pattern of fine and organic material retention consistent
with seasonal plant growth patterns was evident at one site, the three sites displayed different temporal patterns. This inconsistency
is believed to reflect differences in sediment supply at the three sites. 相似文献
Tenant participation in council housing management; Housing Development.
Directorate Occasional Paper 2/77, DoE London, 1977.
Getting tenants involved: a handbook on systems of tenant participation in housing management; DoE London, 1977.
La politica dei servizi tra razionalizzazione e rinnovamento
Alberto L'Abate (1978)
Marsilio Editori, Padova, pp. 316
Handbook for Environmental Planning: the social consequences of environmental change.
J. McEnvoy & T. Dietz (1977)
New York, J. Wiley, pp. 323. Price £15.50
Planning and Urbanism in China
Progress in Planning Vol. 8, Part 2, Fo. 1 N. Jeffrey and M. Caldwell, pp. 97–182, 1977
Pergamen, £4.00
The European Community's Regional Fund
Ross B. Talbot
Progress in Planning, Vol. 8, Part 3, pp. 183–281
Pergamon Press, 1977
Providing the Posh Words
W. Hampton, DoE
1978. £1.50. 60pp.
Four Titles on Conservation
A Critical Bibliography of Building Conservation. John F. Smith. Mansell, London 1978. 207 pages including index. Hard back, £12.90.
Conservation and Planning. Alan Doby. Hutchinson — The Built Environment. 1978. 173 pages. Some illustrations. Paper back, £3.25.
A Study in Conservation. Winston Barnett and Cyril Winskell. Oriel Press, 1977. 45 pages, in English, French and German. Illustrated. Paper back, £3.75.
Interpreting the Conserved Environment. Working Paper No. 29. Brian Goodey. Oxford Polytechnic Department of Town and Country Planning, 1977. 65 pages. Paper back, not priced.
An extracellular fraction from the lignin degrading white-rot fungus, Coriolus versicolor, can biosolubilize leonardite and pretreated lignites in vitro. Leonardite is often found as an overburden to lignite deposits, and is related to humic acid, and is more oxidized than lignites. Extracts from certain fungi such as C. versicolor solubilize leonardite. The biosolubilization activity is at least in part enzymatic in nature. A protein which is at least partly responsible for the solubilization effect has been substantially purified and concentrated by ultrafiltration and ion-exchange chromatography from the broth of an agitated submerged culture of C. versicolor grown in a defined medium. An in vitro coal biosolubilization assay was used to establish the effects of various physical and chemical factors affecting enzyme activity, including temperature and the salt and buffer composition of the reaction mixture. Some initial studies on the mechanism of the enzymatic leonardite biosolubilization reaction are described. 相似文献
ABSTRACT: Nine surface water‐quality variables were analyzed for trend at 180 Virginia locations over the 1978 to 1995 period. Median values and seasonal Kendall's tau, a trend indicator statistic, were generated for dissolved oxygen saturation (DO), biochemical oxygen demand (BOD), pH (PH), total residue (TR), nonfilterable residue (NFR), nitrate‐nitrite nitrogen (NN), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and fecal coliform (FC) at each location. Each location was assigned to one of four physiographic regions, and mean state and regional medians and taus were calculated. Widespread BOD and NFR improvements were detected and FC improvements occurred in the state's western regions. TR and TKN exhibited predominantly increasing trends at locations throughout the state. BOD, TKN, NFR, and TR medians were higher at coastal locations than in other regions. NN, TKN, and TR exhibited predominantly increasing trends in regions with high median concentrations, while declining trends predominated in regions with relatively high BOD, FC, and NFR medians. Appalachian locations exhibited the greatest regional water‐quality improvements for BOD, FC, NFR, and TKN. Factors responsible for regional differences appear to include geology, land use, and landscape features; these factors vary regionally. 相似文献
Micro-zooplankton populations in the upper 100 m were sampled from 5 marine environments in the northeast Pacific Ocean extending from slope waters off San Diego to an oceanic site near Isla Guadalupe, and their abundance related to that of the larger zooplankton, phytoplankton (as estimated from chlorophyll a), and detritus. The micro-zooplankton and other components of the seston were subdivided into 3 fractions on the basis of size in the deck-mounted collecting unit of a seawater pumping system. Through the euphotic zone at each site, the Protozoa, of which ciliates were the dominant forms, accounted for 95% or more of the total micro-zooplankton numbers. Their biomass, as volume, was estimated to be 13 to 28% of that of the total micro-zooplankton. The standing stock of micro-zooplankton over the euphotic zone at the various sites, in terms of dry weight, was estimated to be 14 to 34% (average 23%) of that of the phytoplankton crop. Micro-zooplankton volumes in the upper 100 m were 21 to 26% of those for the larger zooplankton sampled over the same depth. 相似文献