CPMAS 13C NMR spectra of estuarine sedimentary humic acids

CPMAS ¹³C NMR spectra of two estuarine sedimentary humic acids were recorded on a Bruker WP-SY 200 spectrometer. Both samples were found to contain similar aromatic and aliphatic carbon fractions. The sedimentary humic acids have unusually high methoxyl contents and more than one type of methoxyl is indicated. The high methoxyl content may be related to relatively low values for estuarine sedimentary humic acid-metal complexes. Carbohydrate contents of the humic acid samples were also found to be low.     

Cleavage strain in the Variscan fold belt,County Cork,Ireland, estimated from stretched arsenopyrite rosettes

In south-west Ireland, hydrothermally formed arsenopyrite crystals in a Devonian mudstone have responded to Variscan deformation by brittle extension fracture and fragment separation. The interfragment gaps and terminal extension zones of each crystal are infilled with fibrous quartz. Stretches within the cleavage plane have been calculated by the various methods available, most of which can be modified to incorporate terminal extension zones. The Strain Reversal Method is the most accurate currently available but still gives a minimum estimate of the overall strain. The more direct Hossain method, which gives only slightly lower estimates with this data, is more practical for field use. A strain ellipse can be estimated from each crystal rosette composed of three laths (assuming the original interlimb angles were all 60°) and, because actual rather than relative stretches are estimated, this provides a lower bound to the area increase in the plane of cleavage. Based on the average of our calculated strain ellipses this area increase is at least 114% and implies an average shortening across the cleavage of at least 53%. However, several lines of evidence suggest that the cleavage deformation was more intense and more oblate than that calculated, and we argue that a 300% area increase in the cleavage plane and 75% shortening across the cleavage are more realistic estimates of the true strain. Furthermore, the along-strike elongation indicated is at least 80%, which may be regionally significant. Estimates of orogenic contraction derived from balanced section construction should therefore take into account the possibility of a substantial strike elongation, and tectonic models that can accommodate such elongations need to be developed.     

Using parabolas to describe the cross-sections of glaciated valleys

It is widely accepted that the simple power curve Y = aX^b can be used to describe the cross-section of glaciated valleys. There are, however, good reasons to suppose that this particular form of equation is inappropriate for this purpose.     

A late-glacial and post-glacial history of amsoldingersee and vicinity,Switzerland

A multidisciplinary approach was used to study the Late-Glacial and Post-Glacial history of a Swiss Plateau lake. Pollen analysis revealed thirteen major changes in vegetation. A series of coordinated fluctuations in vegetation and lacustrine trophic status were found, which were partially interpreted as the result of climatic changes. Oxygen isotope ratios revealed three major shifts in temperature which correspond with alterations in vegetation composition, sediment composition and lake trophic status. Cladoceran microfossils and fossil pigments were used as indicators of trophic status and reflected periods during which the lake was partially anoxic.     

Limnological investigation of biogenic silica sedimentation and silica biogeochemistry in Lake St. Moritz and Lake Zürich

Biogenic silica concentrations were determined from core samples of laminated sediments collected from Lake Zürich and Lake St. Moritz and used to calculate rates of biogenic silica sedimentation. In Lake Zürich biogenic silica sedimentation increased from 65 g SiO₂·^?2·yr^?1 in 1894 to nearly 900 g SiO₂·m^?2·yr^?1 in 1896 and in Lake St. Moritz biogenic silica sedimentation increased about 6-fold during the 1930s. Both periods of increased biogenic silica flux followed increased loadings of domestic sewage to the lakes. In Lake Zürich the period of increased flux only lasted for a few years whereas in Lake St. Moritz high fluxes were maintained to the top of the core. In Lake Zürich increased production and sedimentation of diatoms could be maintained only until the silca reservoir in the water mass was depleted whereas in Lake St. Moritz (0.10 year residence time and a mean depth of 25 m) diatom production and sedimentation was maintained at a high level by rapid replenishment of silica from tributary inputs. Although historical patterns of biogenic silica sedimentation differed for the two lakes, it is hypothesized that increased biogenic silica deposition in both lakes occurred because diatom production was stimulated by phosphorus enrichment of the water mass and that the silica biogeochemistry of both lakes was affected as a result.     

OCS,H2S,and CS2 fluxes from a salt water marsh

The diurnal-to-monthly behavior of the fluxes of OCS, H₂S, and CS₂ from a mixed-Spartina grass-covered site in a Wallops Island salt water marsh was determined through a series of experiments in August and September, 1982. Absolute flux values were determined for OCS and H₂S, while only relative values were determined for CS₂. The rates of emission of OCS and H₂S were observed to vary diurnally and to be strongly influenced by tides. The time-averaged flux values show that such mixed-Spartina stands are insignificant ( 1%) global sources of H₂S or CS₂ and insignificant contributors to the global OCS cycle (< 1%). These results demonstrate that some marsh regions play a minor role in the global sulfur budget and, consequently, that the inclusion of such areas in extrapolations of measurements of more productive regions could lead to an overestimate of the role of salt water marshes in the global sulfur budget.     

Measurement of atmospheric total ozone by the filter photometric method

The total ozone content in the atmosphere was determined from the multichannel photometer observations of direct solar radiation made in the urban environment at Pune (18° 32 N, 73° 51E, 559 m ASL) and Sinhagad hill station (18° 22N, 73° 45E, 1305 m ASL) during March 1980-February 1982. The total ozone content of the atmosphere was computed making use of the differential absorption of solar radiation due to ozone at 0.4 and 0.6 m wavelengths in the Chappuis band. The values of the ozone data obtained from the photometer observations at Pune and Sinhagad were compared with the corresponding ozone data obtained from the Dobson spectrophotometer located at Pune. Values of ozone obtained by the photometric method were found to be smaller by 8–18% than the Dobson values when Vigroux's absorption coefficients were used. Similarly, when the absorption coefficients of Inn and Tanaka (1953) were used, the ozone values obtained by the photometric method were smaller by 4–14% than the Dobson values. The ozone values at the hill station obtained from the photometric method were in better agreement (5%) with the Dobson values.     

Sr,Nd and Pb isotopic and REE geochemistry of St. Paul's Rocks: the metamorphic and metasomatic development of an alkali basalt mantle source

Surface samples of peridotites and hornblendite mylonites from St. Paul's Rocks, and dredge samples from the flanks of the massif, have been analyzed for Sr, Nd and Pb isotopic ratios and Rb, Sr, and REE concentrations. This data, coupled with previous K and REE data, are used to develop a self-consistent model for the genesis of these ultramafic rocks. This model involves metasomatism of an ocean island-type mantle about 155 m.y. ago by a strongly light-REE-enriched metasomatic fluid, probably derived from the same mantle. This metasomatism produced light-REE-enriched materials which were isotopically homogeneous on a small scale (100 m), and isotopically heterogeneous on a large (km) scale. The geochemical relationships between the peridotites and the hornblendites were established by metamorphic equilibration on a relatively small scale (<10 m). The average mantle produced by these events is characterized by⁸⁷Sr/⁸⁶Sr=0.7034,¹⁴³Nd/¹⁴⁴Nd=0.51291,²⁰⁶Pb/²⁰⁴Pb=19.33 and 207/204=15.63. An alkali basalt which postdates the mylon-itization of the ultramafic massif has an isotopic character which is identical to the average ultramafic massif; it also lies on the five-dimensional isotopic mantle plane of Zindler et al. (1982). With respect to major elements, trace elements, and Sr, Nd and Pb isotopes, the average ultramafic rock of the St. Paul's massif is an ideal candidate for a mantle source from which alkali basalts can be derived by partial melting; the St. Paul's massif is in fact the first such example of an ultramafic rock which meets all the requirements to be an alkali basalt source.     

Recvery of selected pathogens from Naples Bay,Florida, and associated waterways

The waters of Naples Bay, Florida, and associated waterways were monitored for potentially pathogenic bacteria, specificallyVibrio cholerae, V. parahaemolyticus, Salmonella, andPseudomonas aeruginosa. Ten to twelve stations were sampled over a period of eleven months.Vibrio cholerae was recovered in 33.6% of the 116 total samples andSalmonella in 28.4% of the samples. The results show that these bacteria exist in these waters and can be recovered from areas with both high and low numbers of total and fecal coliforms.