Serum transferrin polymorphism in grey trout,Cynoscion regalis,from the lower Rappahannock River

Serum transferrin distribution was studied in grey trout, Cynoscion regalis, obtained from the lower Rappahannock River of Virginia. Three phenotypes were observed, representing two codominant alleles at a single gene locus. The distribution of the phenotypes, designated as Tf A, Tf B, and Tf AB, did not differ significantly from that predicted by Hardy-Weinberg analysis.     

The biogeochemistry of heavy metals in polluted lakes and streams at Flin Flon,Canada, and a proposed method for limiting heavy-metal pollution of natural waters

The biogeochemistry of Zn, Cd, Cu, Hg, and Fe in lakes and streams polluted by mine and smelter wastes emitted at Flin Flon, Canada, was investigated. In Schist Lake, a repository for both tailings-pond drainage and sewage, green algal blooms generated by nutrients from sewage promote entrapment of metals in sediments by (1) accumulation of metals from solution by algal seston, with preferential uptake of Zn, the most abundant metal, followed by sinking of the seston; and (2) production of H₂S during decomposition of dead algae, resulting in sulfide precipitation. Metals are partially resolubilized from seston as it decomposes while sinking. Preferential retention of Cu by sinking seston and by mud promotes Cu enrichment in the mud but the Cu/Zn ratio of mud varies with the Cu/Zn ratio of surface water seston. In bottom muds, partitioning of a metal between sulfide and organic matter is strongly dependent on the stability of the metal sulfide as measured by its standard entropy, the proportion of sulfide-bound metal decreasing in the order Hg>Cd>Cu>Fe>Zn. When sulfide-rich muds were heated under helium, x-ray diffraction revealed abundant well-crystallized ZnS (sphalerite) containing Cd, Hg, and Fe; only poorly crystallized traces of the mineral were detected in unheated mud, however. Cu sulfide failed to crystallize, suggesting interference by sorbed impurities. Metals were concentrated in H₂S-rich muds and extraction of muds with various solvents and by electrodialysis showed that sulfide was much more effective than organic matter in suppressing remobilization of metals. Remobilized Cu is probably bound to organic complexing agents. Some extractable complexing agents bind Cu preferentially with respect to Zn and Cd but others preferentially bind Zn and Cd; the complexes, being stable in the presence of free sulfide, may cause some release of metals from sulfide-rich muds in nature. These results indicate that introduction of sewage together with heavy-metal effluents into settling ponds could be an effective and economic method for limiting heavy-metal pollution of natural waters.     

The complex filling of alae crater,Kilauea Volcano,Hawaii

Since February 1969 Alae Crater, a 165-m-deep pit crater on the east rift of Kilauea Volcano, has been completely filled with about 18 million m³ of lava. The filling was episodic and complex. It involved 13 major periods of addition of lava to the crater, including spectacular lava falls as high as 100 m, and three major periods of draining of lava from the crater. Alae was nearly filled by August 3, 1969, largely drained during a violent ground-cracking event on August 4, 1969, and then filled to the low point on its rim on October 10, 1969. From August 1970 to May 1971, the crater acted as a reservoir for lava that entered through subsurface tubes leading from the vent fissure 150 m away. Another tube system drained the crater and carried lava as far as the sea, 11 km to the south. Much of the lava entered Alae by invading the lava lake beneath its crust and buoying the crust upward. This process, together with the overall complexity of the filling, results in a highly complicated lava lake that would doubtless be misinterpreted if found in the fossil record.     

Upscaling Permeability Measurements Within Complex Heterolithic Tidal Sandstones

We investigate numerically the effect of sample volume on the effective single-phase permeability of heterolithic tidal sandstones, using three-dimensional models reconstructed directly from large rock specimens measuring 45 × 30 × 15 cm. We find that both individual and averaged effective permeability values vary as a function of sample volume, which indicates that permeability data obtained from core-plugs will not be representative at the scale of a reservoir model grid-block regardless of the number of measurements taken. However, the error introduced by averaged data may be minimized using the appropriate averaging scheme for a given facies type and flow direction.     

High-resolution grain-size characterisation of gravel bars using imagery analysis and geo-statistics

The scarcity of grain-size data from gravel-bed rivers has traditionally hindered hydraulic, sediment transport and river habitat studies. A new remote sensing methodology to estimate grain-size distribution is presented. It combines textural digital images of the riverbed at 1 : 1000 and 1 : 40 scales with grain-size sampling. It was applied to a 12-km reach of the Isábena River (Central Pyrenees NE Spain). First, textural patterns for each grain-size range were obtained, selecting the most closely related texture variables, including the use of semivariograms. Second, multiple linear regression equations were derived from the textural variables to estimate each value of the grain-size distribution. The highest correlation values (r²) were obtained from the central part of the distribution (D₅₀ with a RMS error of 12.7%). Finally, new multiple linear regression equations to estimate the D₅₀ and D₈₄ were obtained from 1 : 1000 images and four textural variables. These were used to derive D₅₀ and D₈₄ maps of the riverbed, re-sampled at a resolution of 1.5 m pixels, with RMS estimation errors of 26% and 32%, respectively. Downstream change in grain-size is also well reproduced by the method. The mean D₅₀ of 72 and 32 mm were estimated in the upper and the lower reaches of the river, respectively. The methodology shows great potential for application, the relation between the spatial resolution of the images and the mean grain-size of the riverbed sediment being the main issue for future development.     

Mesquite (Prosopis glandulosa) germination and survival in black-grama (Bouteloua eriopoda) grassland: relations between microsite and heteromyid rodent (Dipodomys spp.) impact

Prosopis pallida H.B.K. is one of the most economically and ecologically important tree species in the arid and semi-arid lands of the American continent. Sections of P. pallida were used to describe its wood anatomy and to determine whether annual rings were visible or not. Results showed that P. pallida has well-differentiated annual growth rings and is therefore suitable for dendrochronological studies. Tree ring chronologies correlate well with precipitation events related to El Niño Southern Oscillation phases. A master chronology for the northern area of Peru was built with these data, and some physiological derivations from the anatomy of P. pallida wood are discussed.