The activity of NaCl in seawater of 10–40‰ salinity and 5–25°C at 1 atmosphere

The activity of NaCl in artificial seawater was measured potentiometrically with Na⁺- and Cl^? -sensitive electrodes. The salinity of the solutions, examined at 25°C, ranged from 10–40‰ salinity. The change in the activity from 5–25°C was measured at 35‰ salinity.The molal mean activity coefficient of NaCl in 35‰ seawater at 25°C is 0.667. The relative partial molal enthalpy of NaCl in 35‰ seawater is ?130 ±50 cal mol^?1. This value is in good agreement with the value measured in pure 0.72 M NaCl.The results were compared with activity coefficients predicted by a specific interaction model and by an ion association model. Good agreement was found in both cases.     

Photospheric magnetic field rotation: Rigid and differential

An autocorrelation of the direction of the large-scale photospheric magnetic field observed during 1959–1967 has yielded evidence that the field structure at some heliographic latitudes can display both differential rotation and rigid rotation properties.     

The determination of the derivatives in Brown's lunar theory

The fundamental matrix solutionT for the variational equations of a Hamiltonian system is symplectic. We use this fact to completeT when it is only partially known. We discuss three cases. The last one gives an easy proof for the method invented by Brown in his lunar theory.Paper presented at the 1981 Oberwolfach Conference on Mathematical Methods in Celestial Mechanics.Dedicated to Victor Szebehely.     

Integrated fluxes for emission lines in the ultraviolet spectra of several planetary nebulae

The IUE satellite observatory has been used to obtain absolutely-calibrated emission line fluxes for diagnostic lines of multiply-ionized C, N, O, Si, Ne, and Ar which occur in the ultraviolet spectral region of planetary nebulae. These data, when combined with data from the blue, visual, and near infrared, will provide improved estimates of ionic concentrations, plasma temperatures and densities, and elemental abundances.     

Spatial variation in delaware bay (U.S.A.) marsh creek fish assemblages

Delaware Bay is one of the largest estuaries on the U.S. eastern seaboard and is flanked by some of the most extensive salt marshes found in the northeastern U.S. While physicochemical and biotic gradients are known to occur along the long axis of the bay, no studies to date have investigated how the fish assemblage found in salt marsh creeks vary along this axis. The marshes of the lower portion of the bay, with higher salinity, are dominated bySpartina spp., while the marshes of the upper portion, with lower salinity, are currently composed primarily of common reed,Phragmites australis, S. alterniflora, or combinations of both. Extensive daytime sampling (n=815 tows) during May–November 1996 was conducted with otter trawls (4.9 m, 6 mm mesh) in six intertidal and subtidal marsh creek systems (upper and lower portions of each creek) where creek channel depths ranged from 1.4–2.8 m at high tide. The fish taxa of the marsh creeks was composed of 40 species that were dominated by demersal and pelagic forms including sciaenids (5 species), percichthyids (2), and clupeids (7), many of which are transients that spawn outside the bay but the early life history stages are abundant within the bay. The most abundant species wereMorone americana (24.3% of the total catch),Cynoscion regalis (15.4%),Micropogonias undulatus (15.3%),Anchoa mitchilli (12.0%), andTrinectes maculatus (10.8%). Non-metric Multi-Dimensional Scaling ordination of catch per unit effort (CPUE) data indicated two fish assemblages that were largely independent of the two major vegetation types, but generally corresponded with spatial variation in salinity. This relationship was more complex because some of the species for which we could discriminate different age classes by size had different patterns of distribution along the salinity gradient.     

Low abundance of the dinoflagellates,Pfiesteria piscicida, P. shumwayae, andCryptoperidiniopsis spp., in South Carolina tidal creeks and open estuaries

The toxicPfiesteria complex are a group of dinoflagellates that have received considerable attention in recent years as causative factors in fish kill or lesion events in North Carolina estuaries and in the Pocomoke River of Chesapeake Bay. In response to the potentialPfiesteria threat, the South Carolina Task Group on Harmful Algae was formed in late 1997 and implemented programs to monitor harmful algal blooms and respond to fish kills or lesion events with particular emphasis on the Bushy Park (Cooper River, Charleston) region, a site of annually recurrent menhaden lesion events.Pfiesteria piscicida, Pfiesteria shumwayae, andCryptoperidiniopsis spp. were documented in South Carolina estuaries. Routine monitoring and fish kill or lesion event sampling consistently indicated low abundances compared to estimates from similar programs in North Carolina and Maryland that sampled areas with a history ofPfiesteria toxic activity. The finding thatPfiesteria-like organism (PLO) abundances were always low in samples collected during menhaden lesion events in Bushy Park suggested other causes for lesion progression, althoughPfiesteria spp. could not be ruled out as a factor in lesion initiation. Based on the previously demonstrated positive relationship between PLO abundance, chlorophylla, and inorganic nutrient concentrations (in laboratory experiments and North Carolina field observations), we hypothesized that the relatively low abundance ofPfiesteria spp. and other PLO (e.g.,Cryptoperidiniopsis) in South Carolina estuaries is related to the relatively low supply of phytoplankton prey, as supported by interstate comparisons in chlorophylla concentrations. Nitrate concentrations were generally much lower in South Carolina estuaries. Estuarine eutrophication may be an important consideration in explaining interstate differences in susceptibility toPfiesteria-related toxic events.     

White K-mica evolution from phengite to muscovite in shales and shale matrix melange,Diablo Range,California

 Eleven samples from high-pressure/low-temperature (HP/LT) shales and shale-matrix melange from four areas in the Diablo Range were studied using electron microprobe (EMP), transmission electron microscopy (TEM), and analytical electron microscopy (AEM) to provide information about white K-mica evolution and about the controls on illite “crystallinity” (IC) in these areas. The data indicate that: (1) compositional gradients from phengitic to muscovitic compositions occur along the long axis, perpendicular to c*, of white K-mica crystals; (2) compositional gradients parallel to c* were not observed, and thus coherent scattering domains along c* are homogeneous; (3) white K-mica crystals with compositions close to muscovite generally contain fewer planar defects and have larger defect-free distances than those with more phengitic compositions; (4) muscovitic white K-mica is less common than phengitic white K-mica. In the literature, grain growth has often been described to occur by the process of Ostwald ripening. Ostwald ripening is defined as an isochemical process and involves the reduction of surface free energy due to simultaneous dissolution and growth by transferring material from smaller particles to larger ones. However, in the present case: (1) coherent scattering domain boundaries often are created by intragranular faults such as dislocations, intergrown smectite layers (and other polysomatic defects), or incoherent layer rotations, which interrupt the 1.0 nm periodicity; (2) recrystallization from phengite to muscovite involves chemical changes. This implies that crystal growth can not be described by the term Ostwald ripening. Therefore, grain growth of white K-mica from the Diablo Range is described as a function of several processes that result in (1) reduction of surface free energy; (2) reduction of strain energy; (3) minimization of the Gibbs free energy due to change in composition. During growth of muscovitic white K-mica, planar defects become less abundant, and the defect-free distance (=coherent scattering domain size parallel to c*) increases. Strain energy decreases. Log-normal frequency distributions of coherent white K-mica scattering domains were found for three samples. The mode of these data coincides with the number of unit cells parallel to c* as calculated from the Scherrer equation. Thus, IC values from shales and shale matrix melange from the Diablo Range are the result of a physical mixture of numerous small phengitic coherent scattering domains and smaller numbers of slightly larger muscovitic coherent scattering domains. This implies that IC from the Diablo Range does not directly reflect maximum temperatures achieved by these rocks. It follows that IC data from terranes with a metamorphic evolution similar to that of the Diablo Range must be interpreted with caution. Received: 23 August 1995 / Accepted: 30 November 1995     

Effects of dithiocarbamate and 8-hydroxyquinoline additions on algal uptake of ambient copper and nickel in South San Francisco Bay water

The addition of synthetic organic ligands such as diethyldithiocarbamate (DDC) and 8-hydroxyquinoline (Ox) to the dissolved fraction (<0.2 μm) of South San Francisco Bay water facilitated the transport of ambient Cu and Ni into phytoplankton cells. The uptake mechanism is diffusion of the lipophilic organic Cu(DDC)₂ ⁰ and Cu(Ox)₂ ⁰ complexes (and corresponding Ni complexes) across the plasma membrane. Short-term uptake experiments were carried out using a coastal diatom,Thalassiosira weissflogii, and resulted in rapid uptake rates and high cellular concentrations of the metal relative to the bay water control. Steady-state conditions between the solution and cellular Cu concentrations occurred within 10 min for a 4 μM addition of DDC and after 3 h for a 100 μM addition of Ox. Steady-state cellular Cu concentrations were over 10 times and 6 times greater, for DDC and Ox treatments, than in the bay water controls. Steady-state cellular Ni concentrations were attained within 10 min for both ligand additions and were more than 6 times and 2 times greater than in the absence of the added ligands. Using this bioassay, we were also able to gain insight into the character of the background organic Cu complexes in South Bay. Our results suggest that the natural organic Cu complexes are relatively hydrophilic in character and do not appear to be directly assimilated across the plasmalemma.