A general mixing equation with applications to Icelandic basalts

The mixing equation applied by Vollmer [1] to Pb and Sr isotope ratios is shown to be a general equation applicable to consideration of element and isotope ratios. The mixing equation is hyperbolic and has the form:Ax + Bxy + Cy + D = 0where the coefficients are dependent on the type of plot considered: i.e. ratio-ratio, ratio-element, or element-element. Careful use of this equation permits testing whether mixing is a viable process, places constraints on end member compositions, allows distinction between mixing of sources and mixing of magmas, and should allow distinction between recent mixing and long-term evolution of sources.The available chemical data for postglacial basalts from Iceland and along the Reykjanes Ridge are not consistent with either mixing of magmas or simple mixing of an enriched ocean island source with a depleted ocean ridge source. If the available analyses for basalts are representative of the source regions, the data are consistent with at least two models neither of which can be properly tested with the available data.(1) There are two separate mixing trends: one beneath Iceland with the alkali basalt source and a depleted Iceland source as end members; the second along the Reykjanes Ridge with a heterogeneous ocean ridge basalt source and a source similar to that for intermediate basalts on Iceland as end members. The depleted Iceland source and the depleted ocean ridge source are not the same.(2) The chemistry of the basalts is not determined by mixing. Instead the basalts are derived from a multiplicity of sources with a similar history which have been isolated for hundreds of millions of years.     

Effects of bottom sediments on the survival of Enterobacter aerogenes in seawater

The survival of the coliform bacterium Enterobacter aerogenes in seawater was greatly affected by the underlying bottom sediments. The presence of sediments which contained higher concentrations of organic nutrients than the overlaying seawater prolonged the survival and even enabled growth of the bacterial cells. Results obtained from chemical analysis indicated that sediments of fine-grained, silt-clay type contained highest amounts of organic nutrients as compared with sediments with larger particle sizes such as silt and sand grains. Thus, nutrient contents of the sediments were found to be inversely proportional to sediment particle size. The degree of prolonged survival of E. aerogenes was also found to be inversely proportional to the size of the sediment particles presented. Release of the bound nutrients which became available to cells of E. aerogenes from sediments by action of waves and human activities can explain, at least in part, why high counts of coliform bacteria are obtained in coastal and beach waters.     

Review of Lagrangian stochastic models for trajectories in the turbulent atmosphere

We review the theoretical basis for, and the advantages of, random flight models for the trajectories of tracer particles in turbulence. We then survey their application to calculate dispersion in the principal types of atmospheric turbulence (stratified, vertically-inhomogeneous, Gaussian or non-Gaussian turbulence in the surface layer and above), and show that they are especially suitable for some problems (e.g., quantifying ground emissions).     

Seismic observations at an overstep of the western North Anatolian Fault (Abant–Sapanca region, Turkey)

The course of the active North Anatolian Fault system from Lake Abant to Lake Sapanca was traced by its high micro-earthquake activity. If approaching from the east this section includes a broad south to north overstep (fault offset) of the main fault. Local seismicity has been recorded in this area by a semi-permanent network of 8 stations since 1985 within the frame of the Turkish–German Joint Project for Earthquake Research. The effect of the overstep and its complex fracture kinematics are reflected by the seismicity distribution, the variations of composite fault-plane solutions, and by the spatial coda-Q distribution. Areas of different stress orientation can be distinguished and assigned to different groups of faults. The stresses and the tectonic pattern only in part correspond to a simple model of an extensional overstep and its correlative pull-apart basin. Other types of deformation involved are characterized by normal faulting on faults parallel to the general course of the main strike-slip fault and by synthetic strike-slip faults oriented similar to Riedel shears. Shear deformation by this fault group widely distributed in an area north and east of the main fault line may play an important role in the evolution of the overstep. The development of a pull-apart basin is inhibited along the eastern half of the overstep and compatibility of both strands of the main fault (Bolu–Lake Abant and Lake Sapanca– Izmit–Marmara Sea) seems to be achieved with the aid of the fault systems mentioned. The extension of the missing part of the pull-apart basin seems to be displaced to positions remote from the Lake Abant–Lake Sapanca main fault line, i.e. to the Akyaz?–Düzce basin tract. Highest Q-values (lowest attenuation of seismic waves) were found in the zone of highest seismicity north and west of the overstep which is the zone of strongest horizontal tension. If high coda-Q is an indicator for strong scattering of seismic waves it might be related to extensional opening of fractures.     

The Berchtesgaden National Park (Bavaria, Germany): a platform for interdisciplinary catchment research

The Berchtesgaden National Park (Bavaria, Germany), a study site of the UNESCO Man and the Biosphere program in the catchment of Berchtesgadener Ache, is introduced as a platform for interdisciplinary research. As the investigation of how human activities affect the natural resources in the park area, which has been defined a main aim of the program, naturally requires expertise from different scientific fields, interdisciplinary research has been fostered in the national park plan since the very beginning of the Man and the Biosphere program in 1981. To analyze the complex interactions and mutual dependencies between socio-economic and natural systems, a variety of monitoring programs have been initialized in different disciplines (e.g. climate sciences, zoology, botany) that are addressed in this paper. As a result of these research efforts, the park offers a profound data basis to be used in future studies (e.g. land cover classifications, maps of geological and soil conditions). Detailed information is provided on a climate monitoring network that has been installed in the park starting in the year 1993. The network has been continuously extended over the years and now provides extraordinary comprehensive information on meteorological conditions in the park, setting the basis for current as well as for potential future climate-related studies. A special characteristic of the station network is the fact that it covers a large range of elevations from 600 m a.s.l in the valleys to 2,600 m a.s.l in the summit regions and is therefore able to capture altitudinal gradients in meteorological variables as typical for Alpine regions. Due to the large number of stations in high elevations (15 stations are in elevations higher than 1,500 m a.s.l) the network provides information on the complex hydrometeorological conditions in summit regions which are often insufficiently represented in observation networks due to the increased costs for maintenance of climate stations in these locations. Beside the various monitoring programs, a variety of numerical models have been (further) developed for application in the park area that make extensive use of the different data collected and therefore largely benefit from the comprehensive data pool. The potential and necessity of the climate monitoring network for modelling studies is demonstrated by utilizing the meteorological recordings in the framework of a hydrometeorological simulation experiment. Further examples of environmental modelling efforts are shortly described together with preliminary model results.     

无定形氢氧化铝的表面酸度

通过酸碱滴定法以及分析反应后的溶液和反应后固体的XRD表征等方法测定了合成氢氧化铝的表面酸度。XRD结果表现出4个宽峰,说明合成产物是无定形的。滴定实验的固体产物的XRD的分析表明,无定形的氢氧化铝在碱性的环境下(pH>10),迅速转化成为结晶的三羟铝石。滴定过程中和反应后的溶液分析计算出无定形氢氧化铝的溶解度,为1010.3。滴定实验中加入的酸或碱与溶解的铝和其表面羟基发生质子化作用或脱质子化作用。表面酸度常数,表面羟基密度和比表面积用FITEQL4.0进行了评价。无定形氢氧化铝的表面酸度@K.FUKUSHI$Research Center for…     

Heat island and oasis effects of vegetative canopies: Micro-meteorological field-measurements

Dry-bulb temperature, dew-point, wind speed, and wind direction were measured in and around an isolated vegetative canopy in Davis CA from 12 to 25 October 1986. These meteorological variables were measured 1.5 m above ground along a transect of 7 weather stations set up across the canopy and the upwind/downwind open fields. These variables were averaged every 15 minutes for a period of two weeks so we could analyze their diurnal cycles as well as their spatial variability. The results indicate significant nocturnal heat islands and daytime oases within the vegetation stand, especially in clear weather. Inside the canopy within 5 m of its upwind edge, daytime temperature fell by as much as 4.5 °C, whereas the nighttime temperature rose by 1 °C. Deeper into the canopy and downwind, the daytime drop in temperature reached 6 °C, and the nighttime increase reached 2 °C. Wind speed was reduced by ~ 2 ms^–1 in mild conditions and by as much as 6.7 ms^–1 during cyclonic weather when open-field wind speed was in the neighborhood of 8 ms^–1. Data from this project were used to construct correlations between temperature and wind speed within the canopy and their corresponding ambient, open-field values.With 10 Figures     

Zircon trace element characteristics and ages in granulite xenoliths: a key to understanding the age and origin of the lower crust,Arkhangelsk kimberlite province,Russia

Garnet granulite and pyroxenite xenoliths from the Grib kimberlite pipe (Arkhangelsk, NW Russia) represent the lower crust beneath Russian platform in close vicinity to the cratonic region of the north-eastern Baltic (Fennoscandian) Shield. Many of the xenoliths have experienced strong interaction with the kimberlite host, but in others some primary granulite-facies minerals are preserved. Calculated bulk compositions for the granulites suggest that their protoliths were basic to intermediate igneous rocks; pyroxenites were ultrabasic to basic cumulates. A few samples are probably metasedimentary in origin. Zircons are abundant in the xenoliths; they exhibit complex zoning in cathodoluminescence with relic cores and various metamorphic rims. Cores include oscillatory zircon crystallized in magmatic protoliths, and metamorphic and magmatic sector-zoned zircons. Recrystallization of older zircons led to the formation of bright homogeneous rims. In some samples, homogeneous shells are surrounded by darker convoluted overgrowths that were formed by subsolidus growth when a change in mineral association occurred. The source of Zr was a phase consumed during a reaction, which produced garnet. Late-generation zircons in all xenoliths show concordant U–Pb ages of 1.81–1.84 Ga (1,826 ± 11 Ma), interpreted as the age of last granulite-facies metamorphism. This event completely resets most zircon cores. An earlier metamorphic event at 1.96–1.94 Ga is recorded by some rare cores, and a few magmatic oscillatory zircons have retained a Neoarchaean age of 2,719 ± 14 Ma. The assemblage of metaigneous and metasedimentary rocks was probably formed before the event at 1.96 Ga. Inherited magmatic zircons indicate the existence of continental crust by the time of intrusion of magmatic protoliths in the Late Archaean. The U–Pb zircon ages correspond to major events recorded in upper crustal rocks of the region: collisional metamorphism and magmatism 2.7 Ga ago and reworking of Archaean rocks at around 1.95–1.75 Ga. However, formation of the granulitic paragenesis in lower crustal rocks occurred significantly later than the last granulite-facies event seen in the upper crust and correlates instead with retrograde metamorphism and small-volume magmatism in the upper crust.     

Contrasting soils and landscapes of the Piedmont and Coastal Plain, eastern United States

The Piedmont and Coastal Plain physiographic provinces comprise 80 percent of the Atlantic Coastal states from New Jersey to Georgia. The provinces are climatically similar. The soil moisture regime is udic. The soil temperature regime is typically thermic from Virginia through Georgia, although it is mesic at altitudes above 400 m in Georgia and above 320 m in Virginia. The soil temperature regime is mesic for the Piedmont and Coastal Plain from Maryland through New Jersey. The tightly folded, structurally complex crystalline rocks of the Piedmont and the gently dipping “layer-cake” clastic sedimentary rocks and sediments of the Coastal Plain respond differently to weathering, pedogenesis, and erosion. The different responses result in two physiographically contrasting terrains; each has distinctive near-surface hydrology, regolith, drainage morphology, and morphometry.The Piedmont is predominantly an erosional terrain. Interfluves are as narrow as 0.5 to 2 km, and are convex upward. Valleys are as narrow as 0.1 to 0.5 km and generally V-shaped in cross section. Alluvial terraces are rare and discontinuous. Soils in the Piedmont are typically less than 1 m thick, have less sand and more clay than Coastal Plain soils, and generally have not developed sandy epipedons. Infiltration rates for Piedmont soils are low at 6–15 cm/h. The soil/saprolite, soil/rock, and saprolite/rock boundaries are distinct (can be placed within 10 cm) and are characterized by ponding and/or lateral movement of water. Water movement through soil into saprolite, and from saprolite into rock, is along joints, foliation, bedding planes and faults. Soils and isotopic data indicate residence times consistent with a Pleistocene age for most Piedmont soils.The Coastal Plain is both an erosional and a constructional terrain. Interfluves commonly are broader than 2 km and are flat. Valleys are commonly as wide as 1 km to greater than 10 km, and contain numerous alluvial and estuarine terrace sequences that can be correlated along valleys for tens of kilometers. Coastal Plain soils are typically as thick as 2 to 8 m, have high sand content throughout, and have sandy epipedons. These epipedons consist of both A and E horizons and are 1 to 4 m thick. In Coastal Plain soils, the boundaries are transitional between the solum and the underlying parent material and between weathered and unweathered parent material. Infiltration rates for Coastal Plain soils are typically higher at 13–28 cm/h, than are those for Piedmont soils. Indeed, for unconsolidated quartz sand, rates may exceed 50 cm/h. Water moves directly from the soil into the parent material through intergranularpores with only minor channelization along macropores, joints, and fractures. The comparatively high infiltration capacity results in relatively low surface runoff, and correspondingly less erosion than on the Piedmont uplands.Due to differences in Piedmont and Coastal Plain erosion rates, topographic inversion is common along the Fall Zone; surfaces on Cenozoic sedimentary deposits of the Coastal Plain are higher than erosional surfaces on regolith weathered from late Precambrian to early Paleozoic crystalline rocks of the Piedmont. Isotopic, paleontologic, and soil data indicate that Coastal Plain surficial deposits are post-middle Miocene to Holocene in age, but most are from 5 to 2 Ma. Thus, the relatively uneroded surfaces comprise a Pliocene landscape. In the eastern third of the Coastal Plain, deposits that are less than 3.5 Ma include alluvial terraces, marine terraces and barrier/back-barrier complexes as morphostratigraphic units that cover thousands of square kilometers. Isotopic and soil data indicate that eastern Piedmont soils range from late Pliocene to Pleistocene in age, but are predominantly less than 2 Ma old. Thus, the eroded uplands of the Piedmont “peneplain” comprise a Pleistocene landscape.