Vitrinite reflectance measurement — Some technique enhancements and relationships     

Ward E. Kilby 《International Journal of Coal Geology》1991,19(1-4)

  相似文献   

The longitudinal proper motion of sunspots and the solar rotation rate     

Fred Ward 《Pure and Applied Geophysics》1966,63(1):196-204

Summary The longitudinal proper motion of sunspot groups has been shown to be a function of their size and relative extension in longitude. Two theories are proposed to explain these effects, which theories assume that the wind circulation of the spots and the wind field surrounding the spots are intimately connected, and dynamically interact. The retardation in the motion of large spot groups is hypothesized to be due to the effect of the latitudinal variation of the Coriolis parameter (on a rotating spherical body) and an assumed vortical circulation around the spots. The more rapid longitudinal motion of extended spot groups is suggested to be the result of the preferential occurrence and development of such groups in regions of above-average horizontal wind and wind shear. If these theories are essentially correct, the real solar rotation rate—i.e., the longitude- and time-averaged fluid motion field—should be derived from the motions of small spot groups, and is 1% to 11/2% higher than the usually accepted rate whichNewton andNunn derived.  相似文献   

Effects of the 1995 and 1998 mass mortality events on the spawning biomass of sardine, Sardinops sagax, in South Australian waters     

Ward  T. M.; Hoedt  F.; McLeay  L.; Dimmlich  W. F.; Kinloch  M.; Jackson  G.; McGarvey  R.; Rogers  P. J.; Jones  K. 《ICES Journal of Marine Science》2001,58(4):865-875

  相似文献   

Spawning patterns of four species of predominantly temperate pelagic fishes in the sub-tropical waters of southern Queensland     

T. M. Ward  J. Staunton-Smith  S. Hoyle  I. A. Halliday 《Estuarine, Coastal and Shelf Science》2003,56(5-6):1125-1140

The diverse pelagic fish assemblage of sub-tropical southern Queensland includes fishes with predominantly temperate distributions, such as tailor Pomatomus saltatrix, sardine Sardinops sagax, round herring Etrumeus teres, and Australian anchovy Engraulis australis. The peak spawning seasons of P. saltatrix, S. sagax and E. teres occur during late winter and early spring (June–October). Eggs and larvae of these three species are widely distributed in shelf waters and comprise >50% of the ichthyoplankton assemblage during this period. Mean monthly sea surface temperatures (SSTs) during late winter and early spring range from 21 to 23 °C, and are thus similar to those recorded in southern Australia during summer and autumn, which is the spawning season of these three species in those temperate waters. E. australis eggs occur mainly in inshore waters, and comprise >50% of fish eggs collected during summer and autumn when mean monthly SSTs in southern Queensland exceed 27 °C. E. australis also spawns mainly during summer and autumn in temperate Australia. Hence, water temperature may be less important as a determinant of the spawning season of E. australis than it is for the other three species. The suitability of southern Queensland for spawning by predominantly temperate species during late winter and early spring may contribute to the high diversity of the region's pelagic fish assemblage. Adult P. saltatrix, S. sagax and E. teres appear to migrate northwards into southern Queensland during early winter to spawn, and larvae may be transported southwards into temperate waters by the East Australian Current. This dispersal-migration pattern is similar to those observed for several species, including P. saltatrix, in the western boundary current systems off the east coasts of North America and Africa. Hence, pelagic fishes in ecosystems off the east coast of three continents migrate into sub-tropical waters to spawn, and larvae are transported back into temperate nursery areas by the prevailing current.  相似文献   

Municipal wastewater contamination in the southern california bight: Part I—metal and organic contaminants in sediments and organisms     

David A Brown  Richard W Gossett  G Patrick Hershelman  Charles F Ward  Alvin M Westcott  Jeffrey N Cross 《Marine environmental research》1986,18(4)

Sediments and organisms were examined for concentrations of organic and metal contaminants from near the Los Angeles County (JWPCP) municipal outfall at Palos Verdes (PV) station 7-3, the Los Angeles City (Hyperion) municipal outfall at Santa Monica Bay (SMB) station 6-4 and reference station SMB 2–3 near Malibu Beach. Flows and mass emission rates of suspended solids, PCBs, Cd and Zn were similar at the two outfalls. Mass emission rate of copper was almost twice as high from Hyperion as from JWPCP, while mass emission rate of DDTs was an order or magnitude higher from JWPCP than from Hyperion.Surficial sediments at PV 7-3 were enriched in most contaminants relative to SMB 6-4 and relative to the mass emission rates of contaminants from the JGVPCP and Hyperion outfalls. Some of this enrichment could be accounted for by the greater accumulation of organic material, measured as total volatile solids, at PV 7-3 relative to SMB 6-4. Some might be accounted for by resurfacing of more contaminated historical deposits buried at PV 7-3. Some of the enrichment of DDTs relative to PCBs could be accounted for by the greater abundance of oxygenated metabolites of PCBs (PCBols) relative to DDTs (DDTols) in sediments.The degree of contamination of organisms by DDTs increased with proximity to PV 7-3 but contamination by PCBs was similar at PV 7-3 and SMB 6-4. DDT concentrations in fish livers ranged from 12 ± 4 ( ) mg/wet kg in longspine combfish from SMB 2–3 to 610 ± 105 (n = 5) mg/wet kg in Pacific sanddab from PV 7-3. DDT concentrations in fish gonads ranged from 0·003 ± 0·003 (n = 5) mg/wet kg in yellowchin sculpin from SMB 6-4 to 1.5 ± 6 (n = 3) mg/wet kg in Pacific sanddabs from PV 7-3. PCB concentrations in fish livers ranged from 1·2 ± 0·4 (n = 4) mg/wet kg in yellowchin sculpin from SMB 2–3 to 16 ± 3 (n = 6) in Pacific Sanddab from SMB 6-4. DDT and PCB concentrations in invertebrate hepatopancreas were only slightly lower than those in fish livers. DDTols and PCBoIs comprised an average of 91 % of the total of parent compounds and oxygenated metabolites in sediments and 66 % in livers and hepatopancreas. Trace metals were frequently decreased in livers and hepatopancreas from near outfalls even though they were highly elevated in sediments.Comparison of sediment and tissue chlorinated hydrocarbon data with that from Elliot and Commencement Bays, Puget Sound, indicated that none of the southern California coastal stations considered in this study were sufficiently lacking contamination to be considered as adequate control sites.  相似文献   

A fungal epizootic in mussels at a deep-sea hydrothermal vent   总被引：1，自引：0，他引：1  

Cindy Lee Van Dover  Megan E. Ward  Joseph L. Scott  Jamie Underdown  Brooke Anderson  Christina Gustafson  Matthew Whalen  & Ryan B. Carnegie 《Marine Ecology》2007,28(1):54-62

Mass mortalities due to disease are important determinants of population and community structure in marine ecosystems, but the speed at which an epizootic may sweep through a population, combined with rapid selection for disease‐resistant stocks, can mask the ecological impact of disease in all but the most closely monitored populations. We document an emergent epizootic event in the deep sea that is occurring in mussels (Bathymodiolus brevior) at the Mussel Hill hydrothermal vent in Fiji Basin and we identify the causal agent as a black yeast (order Chaetothyriales) that elicits a pronounced host immune response and is associated with tissue deterioration. The yeast was not observed in other invertebrate taxa (the gastropods Ifremeria nautilei, Alviniconcha aff. hessleri; the limpets Lepetodrilus schrolli, Symmetromphalus aff. hageni; the polychaetes Branchipolynoe pettiboneae, Amphisamytha cf. galapagensis) associated with the mussel bed, nor in mussels (Bathymodiolus brevior) collected from adjacent Lau Basin mussel beds. Massive mussel mortality resulting from the fungal infection is anticipated at the Mussel Hill site in Fiji Basin; we expect that epizootic outbreaks in dense invertebrate communities have the potential to be major determinants of community structure in deep‐sea chemosynthetic ecosystems. The possibility that submersible assets may serve as vectors for transport of the fungus warrants further attention.  相似文献   

Consolidation and erosion of deposited cohesive sediments in Northern Chesapeake Bay,USA     

Jeffrey Halka  William Panageotou  Lawrence Sanford 《Geo-Marine Letters》1991,11(3-4):174-178

Deposits of dredged cohesive sediments were monitored for changes in volume, bulk characteristics, and susceptibility to resuspension and erosion at disposal sites in Chesapeake Bay. There is a 23–48% volume reduction during the first six months, with correspondingly greater changes over longer time periods. A bulk density increase from 1.15 to 1.3 g/cm³ due to dewatering and compaction accounts for the majority of the volume change. Tidal current induced resuspension is a minor process. The observed suspended sediment load can be accounted for by erosion of only a fraction of a millimeter of sediment on each tidal cycle.  相似文献   

Inorganic and organic nitrogen cycling in the Southern California Bight     

D.A. Bronk  B.B. Ward   《Deep Sea Research Part I: Oceanographic Research Papers》2005,52(12):2285-2300

On the basis of mass balance calculations performed for nitrogen (N) uptake experiments in the Southern California Bight (SCB), it has been suggested that a significant portion of dissolved inorganic N (DIN) uptake results in the production of dissolved organic N (DON). To investigate this process, the fate of ammonium (NH₄⁺) and nitrate (NO₃⁻) uptake was quantified within the euphotic zone at three coastal stations in the SCB using ¹⁵N tracer techniques. Several trends in the fate of DIN and the production of DON were observed. First, production of particulate N (PN), from both NH₄⁺ and NO₃⁻, was quantitatively more important in near surface waters, while DON release dominated within the nitracline. Second, the percentage of gross N uptake released as DON was generally higher when NO₃⁻, rather than NH₄⁺, was the substrate. Third, the percentage of N released as DON was higher at night, relative to the day. Fourth, rates of DON release were significantly correlated to NH₄⁺ regeneration, suggesting that similar mechanisms are responsible for both processes—presumably grazing. The results of this study indicate that the DON pool is a sink for DIN uptake on the time scale of hours. One implication of this finding is that new production estimates based on ¹⁵NO₃⁻ uptake rates will likely underestimate particle flux out of the surface layer because the rate of NO₃⁻ uptake is underestimated due to loss of DO¹⁵N during the incubation. On time scales of months to years, however, the N that is taken up as NO₃⁻ and released as DON will likely contribute to export flux via incorporation of the dissolved phase during seasonal mixing into sinking particles or transport. The export of DON on these time scales argues for the use of gross uptake rates to calculate f-ratios.  相似文献   

Anak Krakatau — a colonization model within a colonization model?     

Prof. I. W. B. Thornton Dr.  S. A. Ward Dr.  R. A. Zann Dr.  T. R. New Dr. 《GeoJournal》1992,28(2):271-286

The ppaer re-examines three suggestions previously made concerning the colonization of the Krakatau islands since the extirpating 1883 eruption that involve the more recently emergent volcanic island Anak Krakatau, which itself suffered a devastating eruption in 1952. The suggestions re-addressed in the light of recent comments by other workers are:

(1)	Anak Krakatau offers, in general terms, an analogy of the early successional processes that occurred on the three older islands in the first decades after the 1883 extirpating eruption.
(2)	Anak Krakatau (with the Sertung spit) may have acted as an ecological refuge for open country species whose habitat on the three older islands declined as a result of vegetation succession.
(3)	Mainland open country species that did not colonize the archipelago when the appropriate vegetational successional stage occurred on the three older islands may now do so through a reopened early-successional window — Anak Krakatau (and the Sertung spit).

  相似文献   

Reply to discussion: History of coastal dunes at Triangle Cliff,Fraser Island,Queensland     

W. T. Ward  K. G. Grimes 《Australian Journal of Earth Sciences》2013,60(4):583-587

  相似文献