The small-scale outflow structure of embedded sources in taurus

High resolution interferometric COJ=1–0 observations of the outflows from two young embedded sources, TMC1 and TMC1A, show the high-velocity gas to have a conical structure, with a constant opening angle of 45° extending to within 1000 AU of the central stars. The correspondence of near-infrared reflection nebulosity atK band with blueshifted CO emission in both objects suggests the lobes are partially evacuated, as do position-velocity diagrams from single-dish COJ=2–1 data. We suggest that the outflows are driven by jets which impart momentum to the ambient medium through shocks, rather than through the entrainment of molecular material along the edges of the jet.The NRAO is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation     

Joesmithite,a plumbous amphibole revisited and comments on bond valences

Summary Joesmithite is a complex clinoamphibole which contains at least 14 components in its formula. Its ideal formula would be PbCa₂ Mg₃ Fe ₂ ³⁺ (Si₆Be₂O₂₂) (OH)₂. It is monoclinic holosymmetric, an ordered derivative of theC2/m clinoamphiboles,a = 9.915(2),b = 17.951(4),c = 5.243(1)Å, = 105.95(2)°, Z = 2, space groupP2/a, D(obs) = 3.83(1), D(cal) = 3.91 g cm^-3. R = 0.056 for 2299 independent F₀.The cells of joesmithite and pargasitic amphibole were compared according to differences, , in their structure cells. The same procedure was applied to the margarosanite, PbCa₂Si₃O₉ and walstromite, BaCa₂Si₃O₉ pairs. In both pairs, the anion positions differed by 0.2 Å at most, but the Pb/A, Pb/Ba differences ranged from 0.4 to 0.6 Å. The lone pair Pb²⁺ cation responds according to the bond valence sums of its coordinating anions compared with its closed core counterpart.It appears that when the bond valence sums for the coordinating anions are different, Pb²⁺ moves toward the most underbonded anion. If the anion bond valence sums are equal for all vertices of the coordinating polyhedron (as in wulfenite, Pb²⁺Mo⁶⁺O₄), then Pb²⁺ does not shift.

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Joesmithit, Neubearbeitung eines bleihältigen Amphibols und Kommentar zu den Bindungsstärken

Zusammenfassung Joesmithit ist ein komplex zusammengesetzter Klinoamphibol, der rumindest 14 Komponenten in seiner Formel aufweist. Die idealisierte Formel lautet PbCa₂Mg₃Fe ₂ ³⁺ (Si₆Be₂O₂₂)(OH)₂. Er ist monoklin holoedrisch und von den geordnetenC2/m-Klinopyroxenen abgeleitet,a = 9,915(2),b = 17,951(4),c = 5,243(1) Å,ß = 105,95(2)°, Z = 2, RaumgruppeP2/a, D(beob) = 3,83(1), D(ber) = 3,91 g cm^-3. R = 0,056 für 2299 unabhängige F₀.Die Elementarzellen von Joesmithit und einem pargasitischen Amphibol wurden in Bezug auf deren Struktur verglichen, ebenso jene von Margarosanit, PbCa₂Si₃O₉, und Walstromit, BaCa₂Si₃O₉, In beiden Paaren differieren die Positionen der Anionen um maximal 0,2 Å, die Unterschiede Pb/A = (Na, K, ) und Pb/Ba betragen 0,4 und 0,6 Å. Das ein einsames Elektronenpaar aufweisende Kation Pb²⁺ folgt den Bindungsstärken der koordinierenden Anionen im Vergleich zu den Pendents mit abgeschlossener Elektronenschale.Differieren die Bindungsstärken der koordinierenden Anionen, bewegt sich Pb²⁺ offensichtlich auf das am schwächsten abgesättigte Anion zu. Falls die Summe der Bindungsstärken an den Anionen in allen Richtungen des Koordinationspolyeders gleich sind (wie im Wulfenit, Pb²⁺Mo⁶⁺O₄), dann kommt es zu keiner Verschiebung des Pb-Atoms.

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Dedicated to Prof. Josef Zemann, Keeper of the flame of chemical crystallography

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Deceased

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With 2 Figures     

Secular variations in kerogen structure and carbon,nitrogen and phosphorus concentrations in pre-Phanerozoic and Phanerozoic sedimentary rocks

Variations in the chemical composition of sedimentary rocks and the nature of kerogen through geologic time were investigated in order to obtain information on biological and environmental evolution during the pre-Phanerozoic eon. Rock samples differing in lithology, depositional environment, and age were pulverized, pre-extracted with organic solvents, and analyzed for total nitrogen (N), phosphorus (P) and organic carbon (org. C or C_T). Variations in the molecular structure of kerogen were measured by determining the ratio of org. C content after pyrolysis (C_R) to org. C content before pyrolysis (C_T), the $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratio being considered an index of the degree of condensed-aromatic (as opposed to aliphatic) character. The rocks included mudstones (Early Archean (> 3 · 10⁹ years old) to Miocene), carbonate rocks (mid-Proterozoic (1.3 · 10⁹ years old) to Eocene), cherts (Early Archean (> 3 · 10⁹ years old) to Late Proterozoic (0.8 · 10⁹ years old)), and coal (Archean (> 2.7 · 10⁹ years old) to Early Proterozoic (～1.8 · 10⁹ years old)).The mudstones and carbonates showed progressive increase in org. C content with decreasing age, as reported by other investigators, but the cherts unexpectedly showed a decrease in org. C content with decreasing age. In all samples, a simple inverse correlation between $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratio and org. C was observed, each rock type forming its own trend separate from but parallel to those of the other rock types. Thus, the older cherts tend to be richer in org. C and have lower $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratios, but the older carbonates and mudstones are poorer in org. C and have higher $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratios. For a given org. C concentration, chert has the highest $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratio and carbonate rock the lowest, mudstone being intermediate; this may mean that chert is relatively ineffective as a catalyst for the thermal cracking of kerogen or that it inhibits cracking. N appears to be correlated with org. C. The relationship between $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratio and org. C or N suggests that the concentrations of org. C and N in sedimentary rocks are largely determined by selective elimination of labile aliphatic and nitrogenous groups of kerogen during post-depositional maturation, although the nature, abundance and depositional environment of the organic source material must be taken into consideration as well. The observed secular variations of org. C, N and $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratio may be ascribed to several possible causes, including age-dependent post-depositional alteration of kerogen, secular decrease in the $\text{CO}{}_2\text{O}{}_2$ ratio of the atmosphere and hydrosphere during pre-Phanerozoic time, secular increase in rates of accumulation of organic matter in sediments and evolutionary changes in the composition of the biological source material. The secular variations of the carbonates and mudstones could be accounted for by age-dependent cumulative effects of post-depositional alteration alone, whereas the secular variations of the cherts probably reflect changes in the nature of the biological source material and the composition of the atmosphere and hydrosphere. The available evidence suggests that primary characteristics of kerogen are better preserved in chert than in the other types of sediment.The $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratios of the carbonates and cherts correlate negatively with the $\text{A}{}_{\mathrm{<mtext>465</mtext><mtext>m</mtext><mtext>\mu </mtext>}}\text{A}{}_{\mathrm{<mtext>665</mtext><mtext>m</mtext><mtext>\mu </mtext>}}$ absorbance ratios of “humic matter” extracted from the same rock samples with benzene—methanol. Thus, the greater the degree of condensed-aromatic character of the kerogen, the greater the degree of condensed-aromatic character of the solvent-extractable bituminous “humic matter” with which it is associated. In addition, the ratio of aliphatic to carbonyl-type groups ($\text{CH}{}_2\text{C=O}$) in the extractable “humic matter” of carbonates and cherts correlates with the non-extractable org. C content of the rocks, suggesting that the org. C data are related to the degree of aliphatic character of the kerogen. The chemical similarity between extractable “humic matter” and its associated kerogen is evidence that the “humic matter” is as old as its rock matrix and can be accepted as a valid chemical fossil. It also suggests that information obtainable from kerogen may be gotten more easily, rapidly and cheaply from solvent-extractable organic matter. The mudstones showed little or no relationship between $\text{A}{}_{\mathrm{<mtext>465</mtext><mtext>m</mtext><mtext>\mu </mtext>}}\text{A}{}_{\mathrm{<mtext>665</mtext><mtext>m</mtext><mtext>\mu </mtext>}}$ ratio and $\text{C}{}_{\mathrm{<mtext>R</mtext>}}\text{C}{}_{\mathrm{<mtext>T</mtext>}}$ ratio, or between $\text{CH}{}_2\text{C=O}$ ratio and org. C content. The data are consistent with the hypothesis that the kerogen in the carbonates and cherts is autochthonous, whereas the kerogen in the mudstones is partly allochthonous, implying the existence of soil humus and soil organisms in pre-Phanerozoic times. Moreover, the existence of coal in Archean sediments is consistent with the existence of very shallow-water and possibly terrestrial microfloras possessing adaptations for protection against ultraviolet solar radiation.The P content of the sediments showed a complicated zig-zag pattern of variation through geologic time. All the different suites of samples gave similar results, indicating that the variations represent phenomena whose effects were worldwide and independent of local environment. P levels are low in the early pre-Phanerozoic but rise with decreasing age until ～ 1 · 10⁹ years B.P., then fall to a minimum at (～0.7–0.8) · 10⁹ years B.P., and rise again to a lower Paleozoic (Ediacarian?) maximum, decline to a later Paleozoic minimum, and then rise again. The low P content of early pre-Phanerozoic sediments could be due to several factors, including high CO₂ content of seawater, anaerobic conditions in the sea, absence of stable-shelf environments, and low rates of primary production. The minimum in the Late Proterozoic is tentatively attributed to the Late Proterozoic glaciations. The data are consistent with the theory that the glacial episode was of worldwide extent.     

Nutrient and Radium Fluxes from Submarine Groundwater Discharge to Port Royal Sound, South Carolina

Water exchange between the coastal ocean and underlying aquifers provides a newly-recognized source of materials to the ocean. The flux of materials into the ocean from this process is termed submarine groundwater discharge (SGD). Both surficial and semi-confined aquifers contribute to SGD. Here we use ²²⁶Ra and ²²⁸Ra to quantify fluxes of SGD to Port Royal Sound, South Carolina, and to separate fluxes from the Upper Floridan (UFA) and surficial aquifers. Higher activity ratios of ²²⁸/²²⁶Ra in the surficial aquifer make this separation possible. We estimate total SGD fluxes of about 100 m³ s^-1 with about 80% being derived from the surficial aquifer. The SGD flux provides about1.8 × 10⁶ mol d^-1 of NH4 with almost 90% from the surficial aquifer. Because of strong differences in the concentration of PO4 within the UFA, PO₄ fluxes areless certain. Using the UFA wells with low PO₄ concentrations yields a flux of 1.2 × 10⁵ mol d^-1; using wells with high concentrations yields a flux of 2.0 × 10⁵ mol d^-1. In the first case virtually all of the PO₄ flux is from the surficial aquifer; in the second case, 40% is from the UFA.The UFA in this region has experienced dramatic changes as a result of withdrawals for human use. Prior to these withdrawals, total nutrient fluxes from the UFA may have been even larger. These changes in the UFA and similar coastal aquifers worldwide have the potential to significantly alter a major nutrient source for the coastal ocean.     

Weak and strong constraint data assimilation in the inverse Regional Ocean Modeling System (ROMS): Development and application for a baroclinic coastal upwelling system

We describe the development and preliminary application of the inverse Regional Ocean Modeling System (ROMS), a four dimensional variational (4DVAR) data assimilation system for high-resolution basin-wide and coastal oceanic flows. Inverse ROMS makes use of the recently developed perturbation tangent linear (TL), representer tangent linear (RP) and adjoint (AD) models to implement an indirect representer-based generalized inverse modeling system. This modeling framework is modular. The TL, RP and AD models are used as stand-alone sub-models within the Inverse Ocean Modeling (IOM) system described in [Chua, B.S., Bennett, A.F., 2001. An inverse ocean modeling system. Ocean Modell. 3, 137–165.]. The system allows the assimilation of a wide range of observation types and uses an iterative algorithm to solve nonlinear assimilation problems. The assimilation is performed either under the perfect model assumption (strong constraint) or by also allowing for errors in the model dynamics (weak constraints). For the weak constraint case the TL and RP models are modified to include additional forcing terms on the right hand side of the model equations. These terms are needed to account for errors in the model dynamics.Inverse ROMS is tested in a realistic 3D baroclinic upwelling system with complex bottom topography, characterized by strong mesoscale eddy variability. We assimilate synthetic data for upper ocean (0–450 m) temperatures and currents over a period of 10 days using both a high resolution and a spatially and temporally aliased sampling array. During the assimilation period the flow field undergoes substantial changes from the initial state. This allows the inverse solution to extract the dynamically active information from the synthetic observations and improve the trajectory of the model state beyond the assimilation window. Both the strong and weak constraint assimilation experiments show forecast skill greater than persistence and climatology during the 10–20 days after the last observation is assimilated.Further investigation in the functional form of the model error covariance and in the use of the representer tangent linear model may lead to improvement in the forecast skill.     

Responses of the mussel Mytilus edulis to copper and phenanthrene: Interactive effects

Most investigations of the responses of marine organisms to xenobiotics have concentrated on single contaminants and little is known of possible interactive effects of different classes of xenobiotics. As these latter seldom occur in environmental isolation, it is important to understand any interactions (synergistic or antagonistic) which may occur. This problem has been approached in the mussel Mytilus edulis by exposing estuarine mussels to copper (20 μg litre⁻¹) and phenanthrene (100 μg litre⁻¹) both individually and in combination, and measuring cytochemical subcellular and physiological responses after 3 days exposure and 3 days and 12 days recovery period. Results showed that mussels accumulated both xenobiotics during 3 days exposure. Depuration of copper was complete in 3 days recovery period, while loss of phenanthrene ranged from 30% to 70% of the concentration reached after 3 days exposure. There were no interactive effects on depuration.Both copper and phenanthrene reduced lysosomal hydrolase latency in digestive cells, and copper appeared to have a synergistic effect in preventing recovery of latency of lysosomal N-acetyl-β-hexosaminidase during the recovery period. There was evidence, in the digestive cells, of an antagonistic effect of copper on stimulation of activity of the microsomal respiratory chain (measured as NADPH-neotetrazolium reductase) by phenanthrene. Stimulation of this system by phenanthrene persisted after 12 days recovery period. There was a synergistic interaction of copper and phenanthrene on elevation of oxygen consumption and ammonium excretion. Clearance rates and scope for growth (physiological condition) were depressed by copper but not by phenanthrene after 3 days exposure.These findings are discussed in terms of known effects of copper and phenanthrene and the interactions are considered in terms of environmental effects measurements.     

A GPS and Cold Ocean Brightness Temperature Calibration of the ERS-2 and TOPEX/Poseidon Microwave Radiometers

Sea-level change studies from altimetric satellites are reliant on range stability of the sea surface heights computed from orbital positioning and geophysically corrected data. One such correction, namely the wet tropospheric delay induced by the highly variable atmospheric water vapor content, is provided by radiometers onboard ERS-2 and TOPEX/Poseidon (T/P). In this study the long-term stability of the ERS-2 microwave radiometer (E2MR) and the T/P microwave radiometer (TMR) are investigated with the observed drift in the brightness temperatures approximated by reference to the coldest temperatures over the oceans. The E2MR stability is characterized by a gain anomaly fall in 1996 and a drift in the 23.8 GHz channel. For the TMR, investigations show that the dominant drift is about 0.2 K/year in the 18 GHz channel over the first 7-8 years but stabilizing and even decreasing slightly thereafter. In contrast, the 21 GHz and 37 GHz channels are comparatively stable. Utilizing correction formulae a modified wet tropospheric range is inferred from “small-change” analysis of the radiometric correction given on the altimetric Geophysical Data Records. The accuracy of this formulism is validated by independent comparison against GPS derived wet tropospheric delays inferred at 14 coastal IGS stations with near continuous data from September 1992 through to the present day. Comparisons between GPS results for ERS-2 and T/P show that the E2MR path delay is 14 mm short. For T/P, the spatial distribution of the wet tropospheric enhancement is further investigated to show that the nonuniformity can equate to a deviation in sea-level height change of about 0.1 mm/year compared with global average sea-level change. Finally, the altimetric range stability of T/P is revisited by comparison against time series from the global network of tide gauges. Analysis shows that the validated TMR drift correction results in a residual trend of -0.27 ± 0.11 mm/yr which is not significant at the 3σ level.     

The fine structure of lysosomal membranes and endoplasmic reticulum in the digestive cells of Mytilus edulis exposed to anthracene and phenanthrene

The stability of lysosomes in the digestive cells of Mytilus edulis is affected by changes in both the chemical and physical conditions of the environment.¹ This type of response must reflect, at least in part, some change in the organisation of the lysosomal membrane, which is a structure which can be resolved by the electron microscope. However, conventional methods of tissue preparation have produced low contrast images of the digestive gland and damage to the lysosomal membranes. Recently a cryopreparation technique² has produced lysosomal membrane preparations in the digestive cells of the digestive gland of Mytilus which have high contrast and structural integrity (Fig. 1) in control animals. This method has been used to demonstrate pathological alterations in the lysosomal membrane induced by the polynuclear aromatic hydrocarbon (PNAH) phenanthrene. Anthracene, an isomeric PNAH, had no effect on the morphology of the lysosomal membrane. Phenanthrene also induced apparent proliferation of smooth endoplasmic reticulum in the digestive cells.     

An ancient linked fluid migration system: cold-seep deposits and sandstone intrusions in the Panoche Hills, California, USA

In central California, Maastrichtian–Danian shales of the Moreno Formation preserve a fluid migration system that developed along the western margin of the former Great Valley forearc basin. The system consists of a network of interconnected sandstone intrusions linked to overlying fossiliferous carbonates whose geochemistry, fauna, and petrology are characteristic of active cold seeps. The system is approximately 800 m thick and represents episodic migration and seafloor expulsion of fluids over at least 0.5×10⁶ years. This locality has the most extensive exposure yet discovered of a complete seep system, from underlying fluid pathways to seep deposits and associated communities.