Organochlorine residues,eggshell thickness,and nest success in barn owls from the Chesapeake Bay     

Erwin E. Klaas  Stanley N. Wiemeyer  Harry M. Ohlendorf  Douglas M. Swineford 《Estuaries and Coasts》1978,1(1):46-53

Eggs of barn owls (Tyto alba) were collected from 18 nests in offshore duck blinds on the Maryland side of the lower Potomac River estuary in 1972 and 1973 and analyzed for organochlorine residues. DDE was found in 100% of the clutches, PCBs in 89%, and dieldrin in 78%. Eggshell thickness was inversely correlated with concentrations of DDE, DDD, and dieldrin residues. Six of the 18 clutches had mean DDE residues above 5 ppm, and eggshell thickness in these six clutches was significantly less (P<0.001) than in the other 12 clutches. The owls produced 1.7 young per active nest in 1973. This rate is slightly below the reproductive rate needed to maintain a stable population. An estimated 15% of the population carried concentrations of organochlorine residues that may have been detrimental to their reproduction. Passerine birds, taken extensively as food by a small proportion of the population, are believed to have been the source of elevated concentrations of organochlorines in these barn owls.  相似文献   

Severe storms and storm systems: Scientific background,methods, and critical questions     

Douglas K. Lilly 《Pure and Applied Geophysics》1975,113(1):713-734

The structure and dynamics of severe convective storms and their mesoscale environments is described on the basis of current literature. Numerical modeling of regional and cloud-scale meteorology is reviewed with respect to its contribution to the understanding of convective storm evolution. Observation techniques are surveyed briefly. Critical questions, principally on the triggering of convective storms, are listed and a U.S. national program (Project SESAME) aimed at answering them is briefly described.  相似文献   

Diversity of recent planktonic foraminifera in the southern Indian Ocean and Late Pleistocene paleotemperatures     

Douglas F. Williams  William C. Johnson 《Quaternary Research》1975,5(2):237-250

Planktonic foraminiferal assemblages have been examined in 25 trigger core top samples and 51 piston core top samples collected between latitudes 28° S and 55° S and longitudes 79° E and 120° E from the southern Indian Ocean during cruises of the U.S.N.S. Eltanin. Samples taken from water depths exceeding 4000 m and/or showing evidence of calcium carbonate dissolution were eliminated from further analysis. The final piston core data set consists of 34 samples; the trigger core data set containing 21 samples. A close relationship exists between changes in the planktonic foraminiferal assemblages in the surface sediments and surface water temperatures. Species diversity values were computed for each of the core top assemblages using the Shannon-Wiener Index and the Brillouin Index, each of which takes into consideration the number of species and the proportionment of individuals among the species. The Shannon and Brillouin diversity values for all samples are positively correlated (correlation coefficient (r) = +.999). Regression analysis of latitude versus Shannon diversity values in the trigger core samples clearly shows a decrease in diversity with increasing latitude (r = ?.979). Furthermore, a strong correlation (r = +.977) exists between decreasing species diversity (Shannon) and decreasing average summer-winter temperature of the overlying surface waters. A paleotemperature equation derived from the relationship of diversity in trigger core samples and surface water temperature was used to generate paleotemperature curves for five trigger cores and a 6 m piston core of Late Pleistocene age, located beneath the present position of the Subtropical Convergence. A 7–8° C temperature range is suggested between the interglacial and glacial episodes in this Late Pleistocene sequence, and probably reflects latitudinal shifts of the Subtropical Convergence and Australasian Front during the Late Pleistocene.  相似文献   

Recent crustal movements in the Sierra Nevada—Walker lane region of California—Nevada: Part i, rate and style of deformation     

David B. Slemmons  Douglas Van Wormer  Elaine J. Bell  Miles L. Silberman 《Tectonophysics》1979,52(1-4)

This review of geological, seismological, geochronological and paleobotanical data is made to compare historic and geologic rates and styles of deformation of the Sierra Nevada and western Basin and Range Provinces. The main uplift of this region began about 17 m.y. ago, with slow uplift of the central Sierra Nevada summit region at rates estimated at about 0.012 mm/yr and of western Basin and Range Province at about 0.01 mm/yr. Many Mesozoic faults of the Foothills fault system were reactivated with normal slip in mid-Tertiary time and have continued to be active with slow slip rates. Sparse data indicate acceleration of rates of uplift and faulting during the Late Cenozoic. The Basin and Range faulting appears to have extended westward during this period with a reduction in width of the Sierra Nevada.The eastern boundary zone of the Sierra Nevada has an irregular en-echelon pattern of normal and right-oblique faults. The area between the Sierra Nevada and the Walker Lane is a complex zone of irregular patterns of hörst and graben blocks and conjugate normal-to right- and left-slip faults of NW and NE trend, respectively. The Walker Lane has at least five main strands near Walker Lake, with total right-slip separation estimated at 48 km. The NE-trending left-slip faults are much shorter than the Walker Lane fault zone and have maximum separations of no more than a few kilometers. Examples include the 1948 and 1966 fault zone northeast of Truckee, California, the Olinghouse fault (Part III) and possibly the almost 200-km-long Carson Lineament.Historic geologic evidence of faulting, seismologic evidence for focal mechanisms, geodetic measurements and strain measurements confirm continued regional uplift and tilting of the Sierra Nevada, with minor internal local faulting and deformation, smaller uplift of the western Basin and Range Province, conjugate focal mechanisms for faults of diverse orientations and types, and a NS to NE—SW compression axis (σ₁) and an EW to NW—SE extension axis (σ₃).  相似文献   

Finite-element analysis of the transport of water and solutes in title-drained soils     

John F. Pickens  Robert W. Gillham  Douglas R. Cameron 《Journal of Hydrology》1979,40(3-4):243-264

The finite-element method based on a Galerkin technique was used to formulate the problem of simulating the two-dimensional (cross-sectional) transient movement of water and solute in saturated or partially saturated nonuniform porous media. The numerical model utilizes linear triangular elements. Nonreactive, as well as reactive solutes whose behaviour can be described by a distribution coefficient or first-order reaction term were considered. The flow portion of the model was tested by comparison of the model results with experimental and finite-difference results for transient flow in an unsaturated sand column and the solute transport portion of the model was tested by comparison with analytical solution results. The model was applied to a hypothetical case involving movement of water and solutes in tile-drained soils. The simulation results showed the development of distinct solute leaching patterns in the soil as drainage proceeded. Although applied to a tile drainage problem in this study, the model should be equally useful in the study of a wide range of two-dimensional water and solute migration problems.  相似文献   

The fluvial system | S.A. Schumm, 1977. Wiley,New York,N.Y., 337 pp. 150 figures, 11 tables, £ 16.50, U.S. $ 28.00     

Ian Douglas 《Earth》1979,14(3):298-299

  相似文献   

The age,origin, and volcanological significance of the Y-5 ash layer in the Mediterranean     

Robert Thunell  Alan Federman  Stephen Sparks  Douglas Williams 《Quaternary Research》1979,12(2):241-253

The Y-5 ash is the most widespread layer in deep-sea sediments from the eastern Mediterranean. This ash layer was previously correlated with the Citara-Serrara tuff on Ischia Island and dated at approximately 25,000 yr B.P. New data on the glass chemistry of the Y-5 ash and pyroclastic deposits from the Neopolitan volcanic province suggest that the layer is correlative with the large-volume Campanian ignimbrite and not with the deposit from Ischia Island. The volume of the Y-5 ash is approximately 65 km³ which is comparable in magnitude to the volume of the Campanian ignimbrite. An interpolated age of approximately 38,000 yr B.P. is estimated based on sedimentation rates derived from δ¹⁸O stratigraphy. There is a discrepancy between this estimate and previously reported radiocarbon ages which range from 24,000 to 35,000 yr B.P. We propose that the “Campanian tuff ash layer” should be adopted as the full stratigraphic name for the Y-5 ash. The deep-sea ash layer is divisible into two units in proximal localities, probably correlating with two major phases of the eruption: plinian and ignimbrite.  相似文献   

The Effect of Flyash Disposal on a Shallow Ground-Water System     

Douglas S. Cherkauer 《Ground water》1980,18(6):544-550

  相似文献   

Melanoidins—kerogen precursors and geochemical lipid sinks: a study using pyrolysis gas chromatography (PGC)     

S.R. Larter  A.G. Douglas 《Geochimica et cosmochimica acta》1980,44(12):2087-2095

Melanoidins, acidic polymeric products of amino acid/sugar condensation reactions, are shown to be capable of reacting with and binding functionalized lipid molecules. Pyrolysis gas chromatography is used to monitor the inclusion of lipids (alcohols and acids) into, and to monitor the changes in composition caused by artificial diagenesis of, the melanoidins. Artificial diagenesis of the lipidcontaining melanoidins produces a material resembling kerogen. The possible role of melanoidins in the formation of kerogens is discussed as are internal transformations within kerogens during diagenesis.  相似文献   

Book reviews     

C. F. D’Elia  Douglas E. Ritchie 《Estuaries and Coasts》1980,3(2):152-153

  相似文献