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   

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).

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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

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Verification of a coupled climate-hydrological model against Holocene palaeohydrological records     

Philip J. Ward  Jeroen C.J.H. Aerts  Hans de Moel  Hans Renssen 《Global and Planetary Change》2007,57(3-4):283-300

We have coupled a climate model (ECBilt-CLIO-VECODE) and a hydrological model (STREAM) offline to simulate palaeodischarge of nineteen rivers (Amazon, Congo, Danube, Ganges, Krishna, Lena, Mackenzie, Mekong, Meuse, Mississippi, Murray–Darling, Nile, Oder, Rhine, Sacramento–San Joaquin, Syr Darya, Volga, Volta, Zambezi) for three time-slices: Early Holocene (9000–8650 BP), Mid-Holocene (6200–5850 BP) and Recent (1750–2000 AD). To evaluate the model's skill in retrodicting broad changes in mean palaeodischarge we have compared the model results with palaeodischarge estimates from multi-proxy records. We have compared the general trends inferred from the proxy data with statistical differences in modelled discharge between the three periods, thereby developing a technique to assess the level of agreement between the model and proxy data. The quality of the proxy data for each basin has been classed as good, reasonable or low. Of the model runs for which the proxy data were good or reasonable, 72% were in good agreement with the proxy data, and 92% were in at least reasonable agreement. We conclude that the coupled climate-hydrological model performs well in simulating mean discharge in the time-slices studied. The discharge trends inferred from the proxy and model data closely follow latitudinal and seasonal variations in insolation over the Holocene. For a number of basins for which agreement was not good we have identified specific mechanisms which could be responsible for the discrepancy, primarily the absence of the Laurentide ice sheet in our model. In order to use the model in an operational sense within water management studies it would be useful to use a higher spatial resolution and a daily time-step.  相似文献   

Request for clarification in the paper: stability analysis of GPS carrier tracking loops by phase margin approach     

Troy D. Fuchser  Phillip W. Ward 《GPS Solutions》2013,17(3):433-438

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Implementing Digital Imaging for Improved Understanding of Microfine Cement Grout Permeation and Filtration     

El Mohtar  Chadi  Jaffal  Hamza  Miller  Anna Kate  Ward  Katie 《Geotechnical and Geological Engineering》2022,40(9):4473-4485

Geotechnical and Geological Engineering - Permeation grouting is a ground improvement method commonly used for strengthening and/or reducing permeability of soils with minimal disturbance to the...  相似文献   

Characterizing and predicting essential habitat features for juvenile coastal sharks          下载免费PDF全文

Christine A. Ward‐Paige  Gregory L. Britten  Dana M. Bethea  John K. Carlson 《Marine Ecology》2015,36(3):419-431

The successful management of shark populations requires juvenile recruitment success. Thus, conservation initiatives now strive to include the protection of areas used by pre‐adult sharks in order to promote juvenile survivorship. Many shark species use inshore areas for early life stages; however, species often segregate within sites to reduce competition. Using a fisheries‐independent gillnet survey from the Northern Gulf of Mexico (2000–2010) we describe distribution patterns and preferred habitat features of the juveniles of six shark species. Our results suggest that multiple shark species concurrently use the area for early life stages and although they overlap, they exhibit distinct habitat preferences characterized by physical variables. Habitat suitability models suggest that temperature, depth, and salinity are the important factors driving juvenile shark occurrence. Within each site, across the sampled range of physical characteristics, blacktip shark (Carcharhinus limbatus) preferred higher temperature (>30 °C) and mid‐depth (~5.5 m); bonnethead shark (Sphyrna tiburo) preferred higher temperature (>30 °C) and mid‐salinity (30–35 PSU), finetooth shark (Carcharhinus isodon) preferred low salinity (<20 PSU) with mid‐depth (~4 m), scalloped hammerhead shark (Sphyrna lewini) preferred high temperature (>30 °C) and salinity (>35 PSU), Atlantic sharpnose shark (Rhizoprionodon terraenovae) preferred high temperature (>30 °C) and deep water (>6 m), and spinner shark (Carcharhinus brevipinna) preferred deep water (>8 m) and high temperature (>30 °C). The other investigated factors, including year, month, latitude, longitude, bottom type, inlet distance, coastline and human coast were not influential for any species. Combining habitat preferences with the sampled environmental characteristics, we predicted habitat suitability throughout the four sites for which physical characteristics were sampled. Habitat suitability surfaces highlight the differences in habitat use between and within sites. This work provides important insight into the habitat ecology of juvenile shark populations, which can be used to better manage these species and protect critical habitat.  相似文献   

GAUGE: the GrAnd Unification and Gravity Explorer     

G. Amelino-Camelia  K. Aplin  M. Arndt  J. D. Barrow  R. J. Bingham  C. Borde  P. Bouyer  M. Caldwell  A. M. Cruise  T. Damour  P. D’Arrigo  H. Dittus  W. Ertmer  B. Foulon  P. Gill  G. D. Hammond  J. Hough  C. Jentsch  U. Johann  P. Jetzer  H. Klein  A. Lambrecht  B. Lamine  C. Lämmerzahl  N. Lockerbie  F. Loeffler  J. T. Mendonca  J. Mester  W.-T. Ni  C. Pegrum  A. Peters  E. Rasel  S. Reynaud  D. Shaul  T. J. Sumner  S. Theil  C. Torrie  P. Touboul  C. Trenkel  S. Vitale  W. Vodel  C. Wang  H. Ward  A. Woodgate 《Experimental Astronomy》2009,23(2):549-572

The GAUGE (GrAnd Unification and Gravity Explorer) mission proposes to use a drag-free spacecraft platform onto which a number of experiments are attached. They are designed to address a number of key issues at the interface between gravity and unification with the other forces of nature. The equivalence principle is to be probed with both a high-precision test using classical macroscopic test bodies, and, to lower precision, using microscopic test bodies via cold-atom interferometry. These two equivalence principle tests will explore string-dilaton theories and the effect of space–time fluctuations respectively. The macroscopic test bodies will also be used for intermediate-range inverse-square law and an axion-like spin-coupling search. The microscopic test bodies offer the prospect of extending the range of tests to also include short-range inverse-square law and spin-coupling measurements as well as looking for evidence of quantum decoherence due to space–time fluctuations at the Planck scale.  相似文献