Whole-bird models for the magnetic cleansing of oiled feathers

Iron powder, a promising dry-cleansing agent for oiled feathers where both the contaminant and the cleansing agent may be harvested magnetically, has been tested on the plumage of whole-bird models. The breast and back plumage of Mallard Duck (Anas platyrhynchos) and Little Penguin (Eudyptula minor) carcasses were patch-contaminated with commercial-grade engine oil, three different crude oils, and an oil/seawater emulsion. The plumage was then subjected to a magnetic cleansing protocol. The contaminant removal was assessed gravimetrically and was found to reflect the outcomes for a previously reported in vitro study using feather clusters. Between 92-98% of the contaminants, and effectively all of the cleansing agent, were removed from the feathers.     

A one hundred and seventeen year coastal water temperature record from Woods Hole,Massachusetts

We have compiled what we believe is the longest coherent coastal sea surface temperature record in North America. Near-surface water temperature measurements have been made almost daily at Great Harbon, Woods Hole, Massachusetts, since 1886 with remarkably few gaps. The record shows that there was no significant trend in water temperature at this site for the first 60 yr of observation. There was some cooling during the 1960s that was followed by a significant warming from 1970–2002 at a rate of 0.04°C yr^?1. During the 1990s annual mean temperatures averaged approximately 1.2°C warmer than they had been on average between 1890 and 1970; winter (December, January, and February) temperatures were 1.7°C warmer and summer (June, July, and August) temperatures were 1.0°C warmer. There has not been a statistically significant decrease in the annual number of winter days below 1°C or an increase in the annual number of winter days above 5°C. The number of summer days each year with water temperature above 21°C has not increased significantly. The dates of first observations of 10°C and 20°C water in the spring have not changed sufficiently to be statistically significant. There is a weak positive correlation between annual and winter water temperature and the annual and winter North Atlantic Oscillation index, respectively, during the period of record.     

Inheritance of early Archaean Pb-isotope variability from long-lived Hadean protocrust

Comparison of initial Pb-isotope signatures of several early Archaean (3.65-3.82 Ga) lithologies (orthogneisses and metasediments) and minerals (feldspar and galena) documents the existence of substantial isotopic heterogeneity in the early Archaean, particularly in the ²⁰⁷Pb/²⁰⁴Pb ratio. The magnitude of isotopic variability at 3.82-3.65 Ga requires source separation between 4.3 and 4.1 Ga, depending on the extent of U/Pb fractionation possible in the early Earth. The isotopic heterogeneity could reflect the coexistence of enriched and depleted mantle domains or the separation of a terrestrial protocrust with a ²³⁸U/²⁰⁴Pb (µ) that was ca. 20-30% higher than coeval mantle. We prefer this latter explanation because the high-µ signature is most evident in metasediments (that formed at the Earth's surface). This interpretation is strengthened by the fact that no straightforward mantle model can be constructed for these high-µ lithologies without violating bulk silicate Earth constraints. The Pb-isotope evidence for a long-lived protocrust complements similar Hf-isotope data from the Earth's oldest zircons, which also require an origin from an enriched (low Lu/Hf) environment. A model is developed in which ́.8-Ga tonalite and monzodiorite gneiss precursors (for one of which we provide zircon U-Pb data) are not mantle-derived but formed by remelting or differentiation of ancient (ca. 4.3 Ga) basaltic crust which had evolved with a higher U/Pb ratio than coeval mantle in the absence of the subduction process. With the initiation of terrestrial subduction at, we propose, ca. 3.75 Ga, most of the ́.8-Ga basaltic shell (and its differentiation products) was recycled into the mantle, because of the lack of a stabilising mantle lithosphere. We argue that the key event for preservation of all ́.8-Ga terrestrial crust was the intrusion of voluminous granitoids immediately after establishment of global subduction because of complementary creation of a lithospheric keel. Furthermore, we argue that preservation of ́.8-Ga material (in situ rocks and zircons) globally is restricted to cratons with a high U/Pb source character (North Atlantic, Slave, Zimbabwe, Yilgarn, and Wyoming), and that the Pb-isotope systematics of these provinces are ultimately explained by reworking of material that was derived from ca. 4.3 Ga (i.e. Hadean) basaltic crust.     

Non-conservative P and N fluxes and net ecosystem production in San Quintin Bay,México

San Quintin Bay, Mexico, is a hypersaline coastal lagoon where the main external forcing of physical and biogeochemical processes is oceanic. Non-conservative fluxes of inorganic N (ΔDIN) and P (ΔDIP), and aspects of net ecosystem metabolism were studied in this lagoon during August 1995, August 1996, and February 1996, by following the LOICZ budgetary modeling approach. The whole-system water exchange time during summer (≈13 d) was shorter than in winter (≈26 d) as northwesterly winds enhancing mixing with the ocean are more intense during the spring-summer upwelling season. Whole-bay ΔDIP values of +0.2 to +0.3 mmol m^?2 d^?1 in August, and <+0.01 mmol m^?2 d^?1 in February indicate that the system is a net source of dissolved inorganic phosphorus (DIP). DIP fluxes from the Bay to the ocean during August are probably balanced by a net import of particulate organic matter between 1,000–1,300 × 10³ mol C d^?1, equivalent to a net ecosystem production (NEP) between ?24 and ?31 mmol C m^?2 d^?1. ΔDIN showed opposite trends in August 1995 and August 1996, with a net import of 13×10³ mol N d^?1 and a net export of 30× 10³ mol N d^?1, respectively. However, N fixation minus denitrification (“apparent denitrification”) estimates of ≈?4 mmol N m^?2 d^?1 in both periods indicate that San Quintin Bay is a net sink of nitrogen. Results from a 3-box model indicate that during summer Box C, adjacent to the ocean, contributed 70–80% of the excess DIP produced in the whole-system. This observation and high apparent denitrification values of ≈?7 mmol N m^?2 d^?1 at the entrance of the Bay, suggest that the net heterotrophic condition of San Quintin Bay in summer is largely determined by imports of labile phytoplanktonic carbon generated in the adjacent ocean during upwelling.A net flux of organic carbon of 30×10⁶ mol C yr^?1 was estimated from Box C, adjacent to the ocean, to Box B, locally known as Bahia Falsa, which is the area designated for oyster aquaculture in the lagoon. It is estimated that this net organic carbon supply is almost equivalent to the annual oyster food demand; our estimate is that oyster aquaculture in San Quintin Bay accounts for the vast majority of the net heterotrophy of Bahia Falsa.     

Deep-sea fan pinch-out geometries and their relationship to fan architecture,Tanqua Karoo basin (South Africa)

Exceptional exposures of Permian basin floor fans (fans 3, 4) and a slope fan (fan 5) in the Tanqua Karoo foreland basin of South Africa have enabled an investigation of the relation between the pinch-out geometries and fan architecture. The pinch-out geometry of fan 3 is characterized by the down dip transition from thin to medium bedded sheet deposits to pinch-out fingers, which are overlain by younger prograding sheet deposits. This geometry reflects the progradational stacking pattern of the fan. In contrast, the fan 4 pinch-out fingers consist of stacked channel fills in the same conduit. This pinch-out configuration relates to the dominant aggradational style observed on the mid and distal parts of fan 4. Fan 5 represents a slope fan comprising an axial channel conduit, which branches down slope into three distributary channels. The distal fan is characterized by larger channel fills, which may represent bypass channels to other basin floor fans. The very thick-bedded nature of the youngest channel fill unit suggests early bypass followed by retrogradation as indicated by the presence of thinner bedded heterolithic channel fill deposits along the axial conduit. Although some of the massive pinch-out channels exhibit basal scour, their depositional morphology suggests that they mainly originated due to the infill of subtle topographic depressions by low concentration turbidity currents. Instead of describing these features as channel fills, the use of the term pinch-out fingers is preferred.     

Upward-thickening patterns and lateral continuity of Permian sand-rich turbidite channel fills, Laingsburg Karoo, South Africa

Abstract Analysis of extensive exposures of the Permian Laingsburg Formation, Karoo basin, South Africa, have enabled a detailed reconstruction of the base of slope stratigraphy and palaeoenvironments in a deep-water system characterized by a very narrow grain-size range (fine sandstone). The deposits include an ≈ 4 km wide and 80 m thick channel complex, fringed by sandy sheet deposits that extend laterally for at least 6 km across depositional strike. Within the channel complex, individual channel fills are marked by shallow basal erosion surfaces draped by thin, parallel-stratified beds of very fine sandstone and siltstone, interpreted as flow tails to largely bypassing flows. These thin beds are overlain by 0·4 to 5 m thick beds of structureless, fine-grained sandstone that represent the majority of the channel fills. The basal packages may be partially to completely removed by localized scour in the axial zone of the channel complex but can be mapped laterally into overbank areas where they thicken and are dominated by rippled fine sandstones with intercalated siltstones. Axial confinement resulted from subtle topography on the basin floor, whereby the lower, dense parts of the initially erosive and bypassing flows were partially confined in the lows and the more dilute, slower moving upper parts of the flows deposited sheet-like successions across slightly elevated overbank areas. The narrow grain-size distribution prohibited the formation ofcoarse-grained residual bypass deposits during the initial phases of channel formation. With decreasing magnitude, later flows became more depositional, filling remaining axial depressions with thick-bedded structureless sandstone. The smaller volumes of late-stage sediment were more axially focused, producing local scour-and-fill features and starvation of the overbank areas. Resulting grain-size vertical profiles are complex. The basal flow tail packages and overlying massive deposits form a thickening and slightly coarsening-upward trend in the channel fills. The overbank deposits show a thinning- and fining-upward profile as a result of less bypass plus late-stage starvation of sand. Application of traditional deep-water facies models could therefore potentially lead to erroneous interpretations of the channel complex as a prograding lobe and the overbank sheets as channel-fills.     

Imaging and regional distribution of basalt flows in the Faeroe-Shetland Basin

We demonstrate that the use of long-offset seismic data allows wide-angle reflections and diving waves to be recorded, and that these can be used in conjunction with prestack depth migrations to constrain and to image the base of the basalt flows and the underlying structure in the Faeroe-Shetland Basin. Crustal velocity models are built first by inverting the traveltimes of the recorded reflections and diving waves using ray-tracing methods. Finer details of the velocity structure can then be refined by analysis of the amplitudes and waveforms of the arrivals. We show that prestack depth migration of selected wide-angle arrivals of known origin, such as the base-basalt reflection, using the crustal velocity model, allows us to build a composite image of the structure down to the pre-rift basement. This has the advantage that the wide-angle first-arriving energy must be primary, and not from one of the many multiples or mode-converted phases that plague near-offset seismic data. This allows us to ‘tag’ these primary arrivals with confidence and then to identify the same arrivals on higher-resolution prestack migrations that include data from all offsets. Examples are drawn from the Faeroe-Shetland Basin, with a series of regional maps of the entire area showing the basalt depths and the thickness of the basalt flows and underlying sediment down to the top of the pre-rift basement. The maps show how the basalts thin to the southeast away from their presumed source west of the present Faeroe Islands, and also show the extent to which the structure of the pre-rift basement controls the considerable variations in sediment thickness between the basement and the cap formed by the overlying basalt flows.     

Flow cytometry and conventional enumeration of microorganisms in ships' ballast water and marine samples

Conventional methods for bacteriological testing of water quality take long periods of time to complete. This makes them inappropriate for a shipping industry that is attempting to comply with the International Maritime Organization's anticipated regulations for ballast water discharge. Flow cytometry for the analysis of marine and ship's ballast water is a comparatively fast and accurate method. Compared to a 5% standard error for flow cytometry analysis the standard methods of culturing and epifluorescence analysis have errors of 2-58% and 10-30%, respectively. Also, unlike culturing methods, flow cytometry is capable of detecting both non-viable and viable but non-culturable microorganisms which can still pose health risks. The great variability in both cell concentrations and microbial content for the samples tested is an indication of the difficulties facing microbial monitoring programmes. The concentration of microorganisms in the ballast tank was generally lower than in local seawater. The proportion of aerobic, microaerophilic, and facultative anaerobic microorganisms present appeared to be influenced by conditions in the ballast tank. The gradual creation of anaerobic conditions in a ballast tank could lead to the accumulation of facultative anaerobic microorganisms, which might represent a potential source of pathogenic species.     

Ecological condition of US Mid-Atlantic estuaries, 1997-1998

The Mid-Atlantic Integrated Assessment (MAIA-Estuaries) evaluated ecological conditions in US Mid-Atlantic estuaries during the summers of 1997 and 1998. Over 800 probability-based stations were monitored in four main estuarine systems--Chesapeake Bay, the Delaware Estuary, Maryland and Virginian coastal bays, and the Albemarle-Pamlico Estuarine System. Twelve smaller estuaries within the four main systems were also assessed to establish variance at the local scale. A subset of the MAIA-Estuaries data is used here to estimate the extent of eutrophication, sediment contamination, and benthic degradation in mid-Atlantic estuaries. An Environmental Report Card and Index of Environmental Integrity summarize conditions in individual estuaries, the four estuarine systems, and the entire MAIA region. Roughly 20-50% of the region showed signs of eutrophication (high nutrients, excessive production of organic matter, poor water clarity, or depleted dissolved oxygen), 30% had contaminated sediments, and 37% had degraded benthic communities. Compared with the Environmental Monitoring and Assessment Program (EMAP)-Virginian Province study in 1990-1993, larger fractions of Chesapeake Bay (17%) and Delaware River (32%) had increased metals or organics in sediments.