The downstream gradation of particle sizes in the Squamish river,British Columbia

The exponential downstream decline in particle size predicted by Sternberg (1875) is examined within a highly active alpine fluvial environment, the gravel-bed Squamish River in southwestern British Columbia. Transect survey procedures for sampling within the coarse alluvial gravels are described in detail. Downstream trends for various particle size statistics, plotted with distance from a major sediment source, are considered according to two scenarios. Evaluation of overall trends indicates that the downstream expression derived by Sternberg (1875) is not the most appropriate; rather, curves are better described by power functions. This reflects a very rapid decline in particle size immediately downstream of the major sediment source. Secondly, evaluation of downstream trends in relation to channel planform determines that exponential functions with different coefficients describe adequately relations within individual planform reaches. There is insufficient evidence to suggest which of these two scenarios may be appropriate. Several lines of evidence suggest that the trends found are more the result of selective sediment transport phenomena than of abrasion, a condition attributed to channel competence within a system dominated by sediment-supply conditions.     

Unequilibrated ordinary chondrites: A tentative subclassification based on volatile-element content

For unequilibrated ordinary chondrites (= UOC), two measures of primitiveness are available: volatile content, in principle reflecting accretion conditions from the solar nebula, and metamorphism, reflecting reheating in the parent bodies. These two measures do not always correlate, and we have therefore developed a tentative classification scheme based on volatile content that complements the Searset al. (1980) scheme based on metamorphism. Like the latter, it subdivides type 3 chondrites on a scale of 3.0 to 3.9; the notation 3.4/0 indicates a meteorite that is subtype 3.4 according to metamorphism and 3.0 according to volatile content.The classification is based mainly on C and Xe—two elements that are little affected by shock-induced reheating—and to a lesser extent on Ar³⁶,Bi,In, and Tl. Of 22 meteorites considered, the majority have concordant classifications (±0.2) on the two scales. However, 5 meteorites are richer in volatiles than their metamorphic grade indicates: Sharps 3.4/0, ALHA 77011 3.5/0, Ngawi 3.6/3, ALHA 77299 3.7/4, and Mezö-Madaras 3.7/3. It remains to be seen whether these differences indeed denote a more primitive nature.Some new clues to the formation of chondrites may eventually come from Xe and C. Their concentrations in UOC's vary by more than 5×, but the $\text{Xe}\text{C}$ ratio remains nearly constant at 3.4 × 10^?3 of the solar-system ratio. Even the ratios for other chondrite classes differ only slightly from that for UOC's, e.g., C3O (1.5×) and E3,4 (0.4×). Either the 4 factors determining this ratio (T, t, P, and internal surface area of the carbon) varied in complementary fashion, or—more probably—they varied only slightly in the entire source region of chondrites.     

The DH ratios of sap in trees: Implications for water sources and tree ring DH ratios

Measurements of $\text{D}\text{H}$ ratios of tree sap can be used to determine the source water for a tree. Based on these measurements, trees can be separated into three categories: those which rely solely on summertime rainfalls, those which rely solely on groundwaters and those which utilize both water sources. For trees in the last category, $\text{D}\text{H}$ ratios of sap can be used to quantify the relative contributions to the tree's source water of summertime rainfalls and groundwaters. These measurements can be used to select trees for tree ring isotope studies. Single source trees, those which rely solely on summertime rain or groundwaters, appear to be the best choices for measuring long records of tree ring $\text{D}\text{H}$ ratios.     

Constraints and Categories of Vadose Zone Monitoring Devices

Traditional monitoring methods using chemical analysis of ground water samples to detect pollutant migration are being superseded or used in conjunction with innovative approaches. A need to detect pollutants before they reach the water table has drawn interest to vadose (unsaturated) zone monitoring and brought together hydrogeologists, soil scientists and agricultural engineers who have been working on this subject for years.
Recent studies have identified over 50 different types of vadose zone monitoring devices and methods that have optimum utility in varying hydrogeologic settings. In general, measurements made in the vadose zone are trying to define storage, transmission of liquid waste in terms of flux and velocity, and pollutant mobility.
Criteria for the selection of alternative vadose zone monitoring methods are important for the development of site-specific systems. These criteria include: type of site; applicability to new, active, and abandoned sites; power requirements; depth limitations; multiple use capability; type of data collection system; reliability and life expectancy; degree of operational complexity; direct versus indirect methods; applicability to alternate media; effect on flow regime; and effect of hazardous waste on sampling or measurements. Application of the selection criteria is discussed in Everett et al. (1982a).     

Matrix material in type 3 chondrites—occurrence,heterogeneity and relationship with chondrules

Matrix material in type 3 chondrites forms rims on chondrules, metal-sulfide aggregates, Ca,Al-rich inclusions and chondritic clasts; it also forms lumps up to a millimeter in size, which may contain coarser silicates. Chondrules of all types were found with internal matrix lumps that appear to have entered the chondrules before the latter had crystallized. Mean concentrations of Mg, Na, Al and Ca in matrix occurrences show up to fivefold variations in a single chondrite. Variations between mean matrix compositions of individual type 3 ordinary chondrites are almost as large and partly reflect systematic differences between H, L and LL matrices. Such variations are probably a result of nebular separation of feldspathic material and ferromagnesian silicates.Compositions of chondrules and their matrix rims are normally unrelated, although rim compositions are correlated with those of matrix lumps inside chondrules. A single chondrule was found with a composition nearly identical to that of its internal matrix lump, suggesting that some chondrules may have formed from matrix material. Matrix lumps are as heterogeneous as chondrules, but mean chondrule and matrix compositions differ, even allowing for possible loss of metallic Fe,Ni during chondrule formation. Since bulk compositions of matrix lumps and rims have probably not changed significantly since their formation except for Fe-Mg exchange, our matrix samples cannot represent typical chondrule precursor materials.     

A staurolite-talc assemblage in tourmaline-phlogopite-chlorite schist from northern Victoria Land,Antarctica, and its petrogenetic significance

Staurolite and corundum are found as inclusions in tourmaline in a talc-phlogopite-chlorite-albite chist near Mount Bernstein (71°37S, 163°07E), northern Victoria Land, Antarctica. These inclusions are interpreted as relics of a staurolite-talc-corundum-chlorite assemblage that was stable during an early stage in the metamorphic cycle and subsequently armored by tourmaline, probably during the middle stage. Pressures and temperatures during the middle stage are estimated to be 650–700°C and 5.5–6.4 kbar. The transition from the early to the middle stage represents a roughly isothermal decrease in pressure of 2–3 kbar. During a late retrograde stage (T=300–370°C, P=3–5 kbar), staurolite was partly replaced by a muscovitic aggregate containing clinozoisite, pumpellyite, and margarite.The staurolite is unusually Si-poor (26.77, 25.85 weight % SiO₂ or 7.275, 7.091 Si per formula unit for 46 oxygens anhydrous), Al-rich (58.00, 57.85% Al₂O₃, 18.579, 18.702 Al), low in divalent cations (Fe+Mg+Mn+Zn=3.301, 3.560) and magnesian (atomic Mg/(Mg+Fe)=0.42, 0.40). Ion microprobe analysis of the first grain indicates about 0.2% Li₂O (0.219 Li) is present. The following substitutions are proposed to explain the unusual chemistry of this staurolite (crystallographic site notation of Smith 1968, in bold letters): Al(Si)+Al(Al(3A,B))Si(Si)+Fe(Fe), Li(Fe)+Al(Al(3A,B))2 Fe(Fe), and 2 Al(Al(3A,B)) 3 Fe(Fe).According to a pressure-temperature diagram constructed by the method of Schreinemakers for the model system FeO-MgO-Al₂O₃-SiO₂ (H₂O in excess), the talc-staurolite assemblage should be stable only in quartz-free rocks at temperatures near 700° C and pressures of 8 kbar or more. The rarity of the staurolite-talc assemblage even in Mg-Al-rich rocks metamorphosed at the appropriate pressure-temperature conditions is attributed to the appearance of anthophyllite or, in Na₂O-bearing rocks, gedrite. Orthoamphibole-cordierite and orthoamphibolekyanite assemblages with chlorite or corundum are incompatible with staurolite-talc±albite. In rocks lacking corundum and formed at pressures above the stability limit of cordierite, staurolite-talc may be metastable relative to orthoamphibole-kyanite, while in corundum-bearing rocks, staurolite-talc may appear under certain conditions, possibly at higher water activities than the orthoamphibole-kyanite assemblage.     

Pharmaceuticals and Other Organic Waste Water Contaminants Within a Leachate Plume Downgradient of a Municipal Landfill

Ground water samples collected from the Norman Landfill research site in central Oklahoma were analyzed as part of the U.S. Geological Survey (USGS) Toxic Substances Hydrology Program's national reconnaissance of pharmaceuticals and other organic waste water contaminants (OWCs) in ground water. Five sites, four of which are located downgradient of the landfill, were sampled in 2000 and analyzed for 76 OWCs using four research methods developed by the USGS. OWCs were detected in water samples from all of the sites sampled, with 22 of the 76 OWCs being detected at least once. Cholesterol (a plant and animal steroid), was detected at all five sites and was the only compound detected in a well upgradient of the landfill. N,N-diethyltoluamide (DEBT used in insect repellent) and tri(2-chloroethyl) phosphate (fire-retardant) were detected in water samples from all four sites located within the landfill-derived leachate plume. The sites closest to the landfill had more detections and greater concentrations of each of the detected compounds than sites located farther away. Detection of multiple OWCs occurred in the four sites located within the leachate plume, with a minimum of four and a maximum of 17 OWCs detected. Because the landfill was established in the 1920s and closed in 1985, many compounds detected in the leachate plume were likely disposed of decades ago. These results indicate the potential for long-term persistence and transport of some OWCs in ground water.     

Coronal magnetic-field model with non-spherical source surface

Previous global models of coronal magnetic fields have used a geometrical construction based on a spherical source surface because of requirements for computational speed. As a result they have had difficulty accounting for (a) the tendency of full magnetohydrodynamic (MHD) models to predict non-radial plasma flow out to r 10r and (b) the appreciable magnitude, 3, of B _r , (the radial component of B) consistently observed at r 1 AU. We present a new modelling technique based on a non-spherical source surface, which is taken to be an isogauss of the underlying potential field generated by currents in or below the photosphere. This modification of the source surface significantly improves the agreement between the geometrical construction and the MHD solution while retaining most of the computational ease provided by a spherical source surface. A detailed comparison between the present source-surface model and the MHD solution is made for the internal dipole case. The resulting B field agrees well in magnitude and direction with the coronal B field derived from the full MHD equations. It shows evidence of the slightly equatorward meridional plasma flow that is characteristic of the MHD solution. Moreover, the B field obtained by using our non-spherical source surface agrees well with that observed by spacecraft in the vicinity of the Earth's orbit. Applied to a solar dipole field with a moment of 1 G-r ³ , the present model predicts that B _r at r 1 AU lies in the range of 1–2 and is remarkably insensitive to heliomagnetic latitude. Our method should be applicable also to more general (i.e., more realistic) configurations of the solar magnetic field. Isogauss surfaces for two representative solar rotations, as calculated from expansions of observed photospheric magnetic-field data, are found to show large and significant deviations from sphericity.