Inter-annual variability in larval supply to populations of three invertebrate taxa in the northern California Current

We investigated sources of inter-annual variability in larval supply to crab and sea urchin populations at Bodega Head and Point Reyes in northern California. During the spring and summer upwelling seasons of the years 1992 through 1997 we monitored the weekly settlement rates of nine species of crabs and two species of sea urchins. As observed in previous studies, daily values of alongshore windstress, temperature and salinity provided evidence for the poleward flow of relatively warm, low salinity water from south of Point Reyes, an apparent retention zone, during upwelling relaxation events. In years dominated by these events (1992, 1993, 1995 and 1996) we observed that alongshore windstress, temperature and salinity were coherent and temperature was significantly correlated with cancrid crab settlement. During these years the magnitude of cancrid crab settlement and the fraction of cancrid crabs relative to other crab species settling were high. Over four years of concurrent sampling there was consistently greater cancrid crab settlement at the Point Reyes site, within the retention zone, than at Bodega Head. Settlement of non-cancrid crabs (porcellanids, grapsids, pagurids and majids) was not as closely linked to intra-annual patterns of upwelling and relaxation, possibly due to the shorter seasonal availability of larvae allowing for the influence of fewer relaxation events. Settlement of this group among years was positively correlated with environmental indicators of strong seasonal upwelling; high salinity, Bakun upwelling index and low temperature. Sea urchin settlement events were observed in June and July of 1992, 1994 and 1997 during warming periods when salinity and temperature were increasing and alongshore windstress was low. Across the six years of the study, we found that cancrid crab larvae had a more even seasonal availability than larvae of non-cancrid species, which settled in greatest numbers during the early portion of the upwelling season. Sea urchins settled in greatest numbers during the later part of the upwelling season. Together these patterns demonstrate the taxon-specific way that inter-annual variability in larval supply is forced by the coincidence of larval availability with favorable physical transport mechanisms.     

A Laboratory and Theoretical Study on the Uptake of SO2 Gas by Large and Small Water Drops Containing Heavy Metal Ions

Laboratory experiments have been carried out to investigate the uptake of sulfur dioxide by water drops containing heavy metal ions where the metal ions serve as catalysts to oxidise the taken up S(IV) into S(VI). During the gas uptake the drops were freely suspended at their terminal velocity in the airstream of the Mainz vertical wind tunnel. Two series of experiments were carried out, one with large millimeter size water drops containing manganese or iron ions, and the other with small water drops containing manganese ions and having radii in hundreds of micron size range. The experimental results were compared against model computations using the Kronig–Brink model and the fully mixed model, modified for the case that heavy metal ions present in the liquid phase act as catalysts for the oxidising process. The results of the model calculations show that there are only small differences between the predicted gas uptake according to the two models. In addition it was found that the experimental obtained results from the uptake of SO₂ by water drops containing heavy metal ions for both, large and small water drops did agree with the model results.     

Modes of occurrence of mercury and other trace elements in coals from the warrior field, Black Warrior Basin, Northwestern Alabama

The mineralogic residence and abundance of trace metals is an important environmental issue. Data from the USGS coal quality database show that potentially toxic elements, including Hg, As, Mo, Se, Cu, and Tl are enriched in a subset of coal samples in the Black Warrior Basin of Alabama, USA. Although the coal as-mined typically is low in these elements, localized enrichments occur in high-pyrite coals and near faults. Microscopic analyses demonstrate that the residence of these elements is dominantly in a late-stage pyrite associated with structurally disrupted coal. Further, our data suggest addition of Hg to the coal matrix as well. The source of these trace elements was hydrothermal fluids driven into the Black Warrior Basin by Alleghanian age tectonism.     

A discussion of the solution for the motion of Pluto

In a previous paper, a semi-analytical solution for the long-term motion of Pluto was presented. The present paper contains: (1) a comparison of the present solution with the solution by Williams and Benson; (2) a discussion of the effect of the near resonance between Pluto and Uranus; and, (3) a calculation of the librational period of the eccentricity, inclination and perihelion.The semi-analytical solution is shown to agree very closely with the long-term solution for Pluto obtained by Williams and Benson using numerical integration of the averaged equations of motion. A small difference between the two solutions is attributed to neglecting the eccentricity and inclination of Neptune in the semi-analytical solution.     

Paleomagnetic results from the Late Carboniferous/Early Permian Casper Formation: implications for northern Appalachian tectonics

Paleomagnetic samples were collected from 190 m of the Late Carboniferous/Early Permian Casper Formation in southeastern Wyoming. A total of 549 samples was drilled near the vicinity of Horse Creek Station at an average stratigraphic interval of 33 cm. All samples were reversely magnetized. Rock magnetic analyses indicate that the primary carrier of remanence in the formation is hematite. A selection criterion applied to the partial demagnetized data restricted the sample population to 233, resulting in a paleomagnetic North Pole located at 47.4°N, 127.4°E (δ_p=0.7;δ_m=1.4). The Casper pole agrees well with other Late Carboniferous/Early Permian poles for cratonic North America. The tight clustering of these paleomagnetic poles suggests that little apparent polar motion with respect to North America occurred during this time. Comparing the stable North American poles with paleomagnetic poles from Late Carboniferous/Early Permian strata of the New England-Canadian Maritime region (Acadia) indicates that this region did not reach its present position relative to North America until at least the Early Permian.     

Atmospheric tracer monitoring and surface plume development at the ZERT pilot test in Bozeman,Montana, USA

A controlled release of CO₂ was conducted at a field site in Bozeman, Montana, USA in July of 2008 in a multi-laboratory study of near surface transport and detection technologies. The development of a subsurface CO₂ plume near the middle packer section of the horizontal release was studied using soil-gas and surface flux measurements of CO₂. A perfluorocarbon tracer was added to the CO₂ released from this section of the horizontal well, and the development of atmospheric plumes of the tracer was studied under various meteorological conditions using horizontal and vertical grids of monitors containing sorbent material to collect the tracer. This study demonstrated the feasibility of using remote sensing for the ultra low level detection of atmospheric plumes of tracers as means to monitor the near surface leakage of sequestered CO₂.     

On the long-term motion of Pluto

A modified periodic orbit of the third kind is introduced that is closely related to periodic orbits of the third kind as defined by Poincaré. It is shown that Pluto librates about the periodic orbit with apparent stability. This further explains the librational motion of the resonant argument of Pluto and the avoidance of a Pluto-Neptune close approach as found by Cohen and Hubbard and the long-term motion of Pluto and the librational motion of the perihelion as found by Williams and Benson. With libration about a periodic orbit, the numerical solution of Williams and Benson can be extrapolated to longer times in the past and future.     

Extent and magnitude of copper contamination in marinas of the San Diego region, California, USA

Marinas are areas of special water quality concern because of the potential for pollutant accumulation within their protected waters. Perhaps the largest contaminant source to marinas is antifouling paints that leach copper to prevent the growth of encrusting organisms on vessel bottoms. Very little monitoring of marinas is typically conducted despite the potential environmental risk, particularly in the San Diego region of California, USA where as many as 17,000 recreational vessels are berthed. The objective of this study was twofold: (1) determine the extent and magnitude of dissolved copper concentrations in marinas throughout the San Diego region, and (2) determine if elevated copper concentrations in marinas of the San Diego region are resulting in adverse biological impacts. A probabilistic study design was used to sample water column copper concentrations and toxicity (using Mytilus galloprovincialis) at 30 stations. Results indicated that exceedence of state water quality objectives was widespread (86% of marina area), but that toxicity was much less prevalent (21% of marina area). Toxicity identification evaluations (TIEs) conducted at the most toxic sites indicated that toxicity was largely due to trace metals, most likely copper. Toxicity was reduced using TIE treatments that chelated trace metals such as cation exchange column, ethylenediaminetetraacetic acid (EDTA), and sodium thiosulfate (STS). Moreover, increasing dissolved copper concentrations correlated with increasing toxicity and these copper concentrations were high enough to account for virtually all of the observed toxicity.