Evaporation from the understorey in the Jarrah (Eucalyptus marginata Don ex Sm.) forest, southwestern Australia

Annual evaporation from groundflora, litter and soil of the jarrah forest was estimated from measurements of daily evaporation by ventilated chambers on several days over two separate 12-month periods. In the first year, when sampling ranged over 0.1 ha of forest, annual evaporation during daylight hours was estimated as 410 mm (0.32 rainfall). In the second year, sampling was more frequent, on a larger scale, and included the night hours. Annual evaporation was estimated at 360 mm (0.36 rainfall).

Similarly, in the second year, annual evaporation from two trees of the dominant middle storey species, Banksia grandis, was estimated at 7500 and 18,9001 respectively. The leaf area of these two trees was 9.6 and 22.4 m², respectively, so that annual evaporation, when expressed as mm³ per mm² leaf area, was similar for both trees (mean = 820 ± 30 mm). Applying that value to all Banksia trees in a hectare of forest, and using a measured estimate of leaf area index of 0.19, the estimated annual evaporation from the Banksia component was 155 mm (0.16 rainfall). For the upland part of the forest sampled, the combined annual evaporation from the lower and middle storeys accounted for about half (0.51) of the annual rainfall.

We conclude that reduced evaporation from the upper storey following clearing or thinning may be strongly counteracted by increased evaporation from the understorey due to increased availability of energy and water.     

Microseismicity and tectonics of Sinai

Five microearthquake seismographs were used at 11 sites in northern Sinai in the period February 1987 to February 1988 to study the microseismicity of the area around the Maghara coal mine for mine-development studies. A total of 270 events were recorded on 850 records. The magnitude, epicenter and depth of each event were calculated using suitable software for an Egyptian Geological Survey and Mining Authority's (EGSMA) XT computer. The interpretation of the seismic activity in the area is given in view of plate tectonics, the Sinai subplate boundary follows the Gulf of Aqaba and the Dead Sea. The plate and subplate boundaries are presently active, and there seems to be a diffuse zone of deformation between “NW Africa” and “Nubia” affecting the Cairo-Suez district.     

Effect of seabed instability on fixed offshore platforms

Storms, hurricanes, and earthquakes may cause seabed instability, especially if the seabed is weak. The seabed instability, manifested in movement of soil layers, exerts lateral forces that may cause large stresses in offshore foundations. The induced stresses may compromise the stability of the foundation and supported structure. The effect of seabed instability on a fixed offshore structure is examined in this study. The method used accounts for soil nonlinearity, dynamic soil resistance, and pile–soil–pile interaction within the stable soil layer. Dynamic p–y curves, dynamic t–z curves and q–z curves have been used to simulate the soil resistance in the lateral and axial directions. The effect of different parameters that influence the response of offshore structures to seabed instability is evaluated. The parameters considered include the value of soil movement, the sliding layer depth, the wave loading, the pile flexibility, the soil movement profile, and the axial loading at the pile head. The response predicted using the proposed analysis compared well with that calculated using a boundary element solution for a case history of a failed offshore platform.     

Management of shock loads wastewater produced from water heaters industry

Water heater manufacturing represents one sector of household electrical appliance industry. It includes several batch processes which resulted in a highly polluted wastewater as shock loads. The objective of this study was to manage the shock loads wastewater with a simple and cost-effective approach prior to final discharge into municipality. To achieve this objective, two approaches were studied. The first approach was the chemical treatment of the accumulated shock loads wastewater using alum and an anionic polymer. Although this approach produced a very high-quality effluent, it was economically and technically infeasible. The second approach was a controlled release of the shock loads to the normal daily discharge in a way that guarantees the compliance of the end-off-pipe with the National Regulatory Standards. This solution required establishment of an equalization tank for normal daily flow and a holding tank for controlled release of the shock loads. Mathematical calculations were carried out to determine the most violating parameters in order to calculate the mixing ratio the of shock loads with the normal daily flow. Full engineering design of the proposed solution was carried out. This approach was implemented and proved to be simple, easy to operate, cost-effective and can be replicated in similar batch processing manufacturing plants.     

Contemporary methods for retrieving the integrated atmospheric water-vapor content and the total cloud liquid-water content

A review of contemporary methods for determining integrated parameters of the water content in the atmosphere―atmospheric water-vapor content and cloud liquid-water content―is presented. Fields of these parameters can only be mapped spatially on the basis of using data of satellite measurements. The least errors of the retrieval of atmospheric water-vapor content and cloud liquid-water content is provided by methods based on using measurements of the satellite-borne scanning multichannel microwave radiometers over the ice-free ocean areas in the absence of precipitation. Most methods for retrieving the atmospheric water-vapor content and cloud liquid-water content from the data of microwave radiometers are based on results of numerical simulation of brightness temperatures of the upwelling microwave radiation of the ocean–atmosphere system. The evolution of satellite-borne microwave radiometers and methods for the retrieval of integrated parameters of water content is presented.     

Offshore sand sources for beach replenishment: Potential borrows on the continental shelf of the Eastern Gulf of Mexico

Erosion of sandy beaches is a worldwide problem that elicits innovative geoengineer‐ing techniques to reduce adverse impacts of shoreline retreat. Beach replenishment has emerged as the “soft”; shore‐stabilization technique of choice for mitigating beach erosion. This method of shore protection involves the addition of sand to the littoral sediment budget for sacrificial purposes. Because inland sand sources are often uneconomical or impractical to use, and known nearshore sources are limited, finding adequate quantities of suitable sand on the inner continental shelf is often vital to beach replenishment projects. The technical studies of survey and materials analysis that identify and delineate usable sand sources are sometimes almost as expensive as small‐project dredging, pumping, and placing the sand on the beach as fill. Inadequate quantity or substandard quality of shelf sand, as well as often‐prohibitive overhead expenses, thus compel shoreline managers to seek suitable sand sources offshore.

In the study area off the central‐west coast of Florida, offshore potential borrow areas (PBAs) were identified on the basis of studies conducted in reconnoitory and detailed phases. Sophisticated state‐of‐the‐art equipment used in this investigation provided more detailed subbottom mapping information than is normally obtained with conventional seismic equipment. An example of sand exploration studies was incorporated in a 215‐km² survey of offshore areas by conducting bathymetric surveys and subbottom seismic profiling, collecting jet probes, grab samples, and vibrocores, and analyzing sediment grading in subsamples from vibrocores. These combined analyses indicated that at least 8.8 ×10⁶ m³ of sand is available in potential borrow areas from 7.0 to 12 km offshore in water depths of 8.0 to 11.5 m. In the PBAs, mean grain size of sand falls into the range 0.13–0.53 mm, sorting averages 0.65–1.31ø, and the overall silt content varies from 3.9–8.5%. High silt contents (13–19%) mapped in some areas make these sedimentary deposits unsuitable as fill for artificial beach renourishment.     

Geomechanical modelling to assess fault integrity at the CO2CRC Otway Project,Australia

This paper presents the first published 3D geomechanical modelling study of the CO2CRC Otway Project, located in the state of Victoria, Australia. The results of this work contribute to one of the main objectives of the CO2CRC, which is to demonstrate the feasibility of CO₂ storage in a depleted gas reservoir. With this aim in mind, a one-way coupled flow and geomechanics model is presented, with the capability of predicting changes to the in situ stress field caused by changes in reservoir pressure owing to CO₂ production and injection. A parametric study investigating the pore pressures required to reactivate key, reservoir-bounding faults has been conducted, and the results from the numerical simulation and analytical analysis are compared. The numerical simulation indicates that the critical pore fluid pressure to cause fault reactivation is 1.15 times the original pressure as opposed to 1.5 times for the comparable analytical model. Possible reasons for the differences between the numerical and analytical models can be ascribed to the higher degree of complexity incorporated in the numerical model. Heterogeneity in terms of lateral variations of hydrological and mechanical parameters, effect of topography, presence of faults and interaction between cells are considered to be the main sources for the different estimation of critical pore pressure. The numerical model, which incorporates this greater complexity, is able then to better describe the state of stress that acts in the subsurface compared with a simple 1D analytical model. Moreover, the reactivation pressures depend mainly on the state of stress described; therefore we suggest that numerical models be performed when possible.     

Refractory metal nuggets within presolar graphite: First condensates from a circumstellar environment

Transmission electron microscope (TEM) investigations have revealed Os, Ru, Mo‐rich refractory metal nuggets within four different presolar graphites, from both the high‐density (HD) Murchison (MUR) and low‐density (LD) Orgueil (ORG) fractions. Microstructural and chemical data suggest that these are direct condensates from the gas, rather than forming later by exsolution. The presolar refractory metal nugget (pRMN) compositions are variable (e.g., from 8 < Os atom% < 77), but follow the same chemical fractionation trends as isolated refractory metal nuggets (mRMNs) previously found in meteorites (Berg et al. 2009). From these compositions one can infer a temperature of last equilibration with the gas of 1405–1810 K (e.g., Berg et al. 2009 at approximately 100 dyne cm^?2 pressure), which implies that the host graphites form over roughly the same range (in agreement with predictions) and that the pRMNs are chemically isolated from the gas when captured by graphite. Further, the pRMN compositions give evidence that HD graphites form at a higher T than LD ones. Chemical and phase similarities with the isolated mRMNs suggest that the mRMNs also condense directly from a gas, although from the early solar nebula rather than a presolar environment. Although the pRMNs themselves are too small for detection of isotopic anomalies, NanoSIMS isotopic measurements of their host graphites confirm a presolar origin for the assemblages. The two pRMN‐containing LD graphites show evidence of a supernova (SN) origin, whereas the stellar origins of the pRMNs in HD graphite are unclear, because only less‐diagnostic ¹²C enrichments are detectable (as is commonly true for HD graphites).     

Lithospheric thickness beneath the southern Kenya Rift: implications from basalt geochemistry

Geochemical data are reported for samples from the flanks and floor of the southern Kenya Rift Valley in the Lake Magadi area, and from two central volcanoes located within the rift valley. Rift lavas include samples of Singaraini and Ol Tepesi basalts on the eastern flank, Kirikiti basalts from the western flank, and plateau trachytes from the rift valley floor. Central volcano samples are from Ol Esayeiti and Lenderut located on the eastern flank. The rift basalts are mildly ne-normative, moderately evolved (Mg#=0.39-0.62) alkali basalts and show an overall range in differentiation. Incompatible trace element abundances are moderately elevated (Nb=17-51; Zr=93-274; La=17-55 ppm) and show strongly coherent variations and constant inter-element ratios (e.g. Zr/Nb=4.2-5.5; Nb/Ta=17.5ǂ.4; (La/Sm)_n=7.3ǃ.1); isotope ratios are restricted in range (⁸⁷Sr/⁸⁶Sr=0.70393-0.70436; ¹⁴³Nd/¹⁴⁴Nd=0.51272-0.51280; ²⁰⁶Pb/²⁰⁴Pb=19.87-19.92; ²⁰⁷Pb/²⁰⁴Pb=15.68-15.70; ²⁰⁸Pb/²⁰⁴Pb=39.56-39.71). Central volcano lavas are more alkaline in character and include basanite (Ol Esayeiti; Mg# >60) and hawaiite to benmoreite (Lenderut; Mg#=0.48-0.38). Incompatible element ratio are similar to those of the rift basalts, although the chondrite normalised REE patterns are steeper (La/Sm)_n=17.4ǃ.2). ⁸⁷Sr/⁸⁶Sr (0.70358, 0.70391), ¹⁴³Nd/¹⁴⁴Nd (0.51280, 0.51267), ²⁰⁶Pb/²⁰⁴Pb (19.96,20.17), ²⁰⁷Pb/²⁰⁴Pb (15.66,15.76) and ²⁰⁸Pb/²⁰⁴Pb (39.80,40.00) ratios of Ol Esayeiti basanites are similar to the rift basalts, whereas the Lenderut lavas have unusually low¹⁴³Nd/¹⁴⁴Nd (0.512388-0.512453) ratios for their ⁸⁷Sr/⁸⁶Sr (0.70370-0.70481) ratios, and distinctly less radiogenic and variable Pb isotope compositions (²⁰⁶Pb/²⁰⁴Pb=17.93-19.01; ²⁰⁷Pb/²⁰⁴Pb=15.43-15.58; ²⁰⁸Pb/²⁰⁴Pb=37.91-39.14). An integrated model is developed in which the geochemical signature of the lavas is attributed to variable degrees of melting to depths within the garnet stability field, and in the presence of residual amphibole. The stability fields of these phases in P-T space indicates that the lavas must have formed within the sub-continental lithosphere rather than within the underlying ambient asthenosphere or a rising mantle plume. The subcontinental lithospheric mantle must therefore extend to a depth of at least 75 km beneath the Lake Magadi area, which contrasts with recent gravity models for the area, which infer that lithospheric mantle is absent beneath this section of the southern Kenya Rift.     

The Darwin Rise demise: the western Pacific guyot heights trace the trans-Pacific Mendocino fracture zone

The Darwin Rise has been proposed so many times and in so many forms and places that the time has come to make a more comprehensive examination of the region. Lying on the NW Pacific Plate between the Geisha Guyots, the Mid-Pacific Mountains, the equator, and the trenches, the region is roughly bounded by magnetic anomaly M20 (147 Ma). It was subjected to a massive outpouring of lava about 105 to 120 Ma, which created the guyots and seamounts in that region. Guyots are excellent tools for studying events of long ago because they eroded in the same lowstand in the Cretaceous and guyot relief, therefore, is a surrogate for paleo-sealevel. The relief is derived by subtracting the break depth of the summit plateau of a guyot from the regional depth. Guyot relief would necessarily be less in the center than to the periphery if the feature formed on a pre-existing rise, as has been postulated. The existence of a paleo-Darwin Rise would give concentric contours for the region in question. Of the sixty guyots used in this study, thirty-seven of these guyots were surveyed using SASS multibeam in the Marcus-Wake seamount group. Twenty-three guyots were surveyed using random track single-beam sonar surveys. An entirely different scenario is shown. Data revealed a major fracture passing through the area coevally or after the guyots formed. Because the depths to the summit are not the same now, vertical tectonics occurred after subaerial erosion. This means the fracture formed during and after the erosion (roughly 105 Ma) and influenced the normal sequence of events in guyot formation. Depending on how one deciphers trends through the Hess Rise morass, SASS bathymetry shows a continuation of the Surveyor/Mendocino fracture zone swarm inside the M20 region to the NE of these data. The fracture swarm continues to the western Pacific trench system. Based on this information, if the Darwin Rise ever existed, it had to have done so elsewhere.