Determination of Phosphate in Saudi Arabian Waters

The procedures for the determination of phosphate are based on the reduction of molybdophosphoric heteropoly acids using ascorbic acid. Measurements of the complex products formed with rhodamine B and chlorophenol red dyes and the reduced molybdophosphoric acid are made at 490 and 510 nm with molar absorptivities of 28571 and 20949 l/mol. cm with each dye, respectively. Phosphate could be determined in the concentration ranges of 0.44 to 1.21 and 0.44 to 1.32 μg/l PO₄-P with rhodamine B and chlorophenol red dyes, respectively. The results obtained are compared with those of molybdophosphoric acid with rhodamine B and chlorophenol red using stannous chloride as reducing agent. These procedures are used for the determination of phosphate in the Kingdom of Saudi Arabia.     

Storm-water hydrograph separation of run off from a mine-tailings impoundment formed by thickened tailings discharge at Kidd Creek, Timmins, Ontario

The Kidd Creek Cu---Zn sulphide mine is located near Timmins, Ontario. Mill tailings are thickened and deposited as a thickened slurry in a circular, conical-shaped pile with an area of approximately 1200 ha. Deposition of tailings as a thickened slurry results in a relatively uniform grain-size distribution and hydraulic conductivity, and a thick tension-saturated zone above the water table. The tailings are drained by numerous small, ephemeral stream channels, which have developed in a radial pattern. During storms, water from these streams collects in catchment ponds where it is held before treatment. The contribution of tailings pore water to the run off is of interest because of the potential for discharge of pore water containing high concentrations of Fe(II)-acidity, metals and SO₄ to the stream. Hydraulic head measurements, measurements of water-table elevation and groundwater flow modelling were conducted to determine the mechanisms responsible for tailings pore water entering the surface streams. Chemical hydrograph separation of storm run off in one of these streams, during three rainfall events, using Na and Cl as conservative tracers, indicates that the integrated tailings pore water fraction makes up between less than 1 % and 20% of the total hydrograph. This range is less than the maximum fraction of tailings pore water of 22–65% reported for run off from a conventional tailings deposit. At this site, preferential flow through permeable fractures may be the dominant mechanism causing discharge of tailings pore water to storm run off. Estimates of the mass of Fe(II) that discharges to the surface run off from the pore water range up to 2800 mg s⁻¹ during a moderate intensity, long duration rainfall event. The greatest potential for discharge of significant masses of solutes derived from the pore water exists during long duration rainfall events, when the water table rises to the surface over large areas of the tailings impoundment.     

The water balance of the Dead Sea: an integrated approach

The Dead Sea is the lowest spot on Earth. It is a closed saline lake located in the middle of the Jordan Rift Valley between Lake Tiberias and the Red Sea. Its major tributaries are the Jordan River itself and the Dead Sea side wadis. The Dead Sea has a unique ecosystem and its water has curative, industrial and recreational significance. The level of the Dead Sea has been continuously falling since the early 1930s at an average rate of 0·7 m per year. The water level, as of February 1998, is about 410·9 m below mean sea level. In this paper, a water balance model is developed for the Dead Sea by considering different hydrological components of this water balance, including precipitation, runoff, evaporation and groundwater flow. This model is calibrated based on historical levels of the Dead Sea. Different scenarios are investigated, including the proposed Dead Sea–Red Sea Canal. This project is supposed to halt the shrinking of the Dead Sea and restore it to pre‐1950 levels in the next century. Copyright © 2000 John Wiley & Sons, Ltd.     

Kinematics of the bottom of the Eurasia Basin near the Spitsbergen domain

Prior to extension of the lithosphere in the Eurasia Basin, the Yermak Plateau was an element of the Eurasian Arctic margin. Extension of the Barents Sea shelf culminated gradually in rifting of the continental crust with separation of this block from the continent during Chrons C25r?C26n (57.656?59.237 Ma ago) and emplacement of numerous basic dikes, which could be responsible for the formation of high-amplitude magnetic anomalies on the Yermak Plateau. The investigation included reconstruction of axes in the breakup zones along peripheral continental fragments of Spitsbergen with determination of the Euler poles and angles of rotation, which describe the kinematics of this process. It is revealed that the difference between depths of conjugate isobaths can be as large as many tens of meters, which reflects the nonuniformly scaled slide of peripheral areas of the continental crust along the plane of the crustal-penetrating fault and, correspondingly, their different subsidence during rifting.     

Laboratory soil piping and internal erosion experiments: evaluation of a soil piping model for low‐compacted soils

Mechanistic models have been proposed for soil piping and internal erosion on well‐compacted levees and dams, but limited research has evaluated these models in less compacted (more erodible) soils typical of hillslopes and streambanks. This study utilized a soil box (50 cm long, 50 cm wide and 20 cm tall) to conduct constant‐head, soil pipe and internal erosion experiments for two soils (clay loam from Dry Creek and sandy loam from Cow Creek streambanks) packed at uniform bulk densities. Initial gravimetric moisture contents prior to packing were 10, 12 and 14% for Dry Creek soil and 8, 12, and 14% for Cow Creek soil. A 1‐cm diameter rod was placed horizontally along the length of the soil bed during packing and carefully removed after packing to create a continuous soil pipe. A constant head was maintained at the inflow end. Flow rates and sediment concentrations were measured from the pipe outlet. Replicate submerged jet erosion tests (JETs) were conducted to derive erodibility parameters for repacked samples at the same moisture contents. Flow rates from the box experiments were used to calibrate the mechanistic model. The influence of the initial moisture content was apparent, with some pipes (8% moisture content) expanding so fast that limited data was collected. The mechanistic model was able to estimate equivalent flow rates to those observed in the experiments, but had difficulty matching observed sediment concentrations when the pipes rapidly expanded. The JETs predicted similar erodibility coefficients compared to the mechanistic model for the more erodible cases but not for the less erodible cases (14% moisture content). Improved models are needed that better define the changing soil pipe cross‐section during supply‐ and transport‐limited internal erosion, especially for piping through lower compacted (more erodible) soils as opposed to more well‐compacted soils resulting from constructing levees and dams. Copyright © 2013 John Wiley & Sons, Ltd.     

Semi-automated procedures for shoreline extraction using single RADARSAT-1 SAR image

Coastline identification is important for surveying and mapping reasons. Coastline serves as the basic point of reference and is used on nautical charts for navigation purposes. Its delineation has become crucial and more important in the wake of the many recent earthquakes and tsunamis resulting in complete change and redraw of some shorelines. In a tropical country like Malaysia, presence of cloud cover hinders the application of optical remote sensing data. In this study a semi-automated technique and procedures are presented for shoreline delineation from RADARSAT-1 image. A scene of RADARSAT-1 satellite image was processed using enhanced filtering technique to identify and extract the shoreline coast of Kuala Terengganu, Malaysia. RADSARSAT image has many advantages over the optical data because of its ability to penetrate cloud cover and its night sensing capabilities. At first, speckles were removed from the image by using Lee sigma filter which was used to reduce random noise and to enhance the image and discriminate the boundary between land and water. The results showed an accurate and improved extraction and delineation of the entire coastline of Kuala Terrenganu. The study demonstrated the reliability of the image averaging filter in reducing random noise over the sea surface especially near the shoreline. It enhanced land-water boundary differentiation, enabling better delineation of the shoreline. Overall, the developed techniques showed the potential of radar imagery for accurate shoreline mapping and will be useful for monitoring shoreline changes during high and low tides as well as shoreline erosion in a tropical country like Malaysia.     

GIS-Oriented Database on Seismic Hazard Assessment for Caucasian and Crimean Regions

Izvestiya, Atmospheric and Oceanic Physics - Zones of higher seismic hazard occupy about 20% of Russia’s territory, and 5% are characterized by extremely high hazard. These latter are, in...     

The Australian-Antarctic segment of Gondwana

Australia is one of the major continental terranes in Gondwana’s structure. At the same time, the precise position of Australia in this structure has not yet been clearly identified. According to different works, Australia is connected to Antarctica in a number of areas near Wilkes Land, Adelie Land, and Victoria Land. The comprehensive analysis of the geological and geophysical data allows us to reconstruct the optimal relative position of the continents and to reach a conclusion about the propagation of the tectonic structures of Australia towards Antarctica.     

Kinematic Model of Development of Eastern Areas of the Gakkel Mid-Ocean Ridge in the Eurasian Basin of the Arctic Ocean

Oceanology - A new map of the axes of linear magnetic anomalies for eastern regions of the Eurasian Basin has been compiled. Based on the results of Russian geomagnetic surveys, paleoanomaly C25...     

Introduction of geospatial perspective to the ecology of fish-habitat relationships in Indonesian coral reefs: A remote sensing approach

Coral reef ecosystems worldwide are now being harmed by various stresses accompanying the degradation of fish habitats and thus knowledge of fish-habitat relationships is urgently required. Because conventional research methods were not practical for this purpose due to the lack of a geospatial perspective, we attempted to develop a research method integrating visual fish observation with a seabed habitat map and to expand knowledge to a two-dimensional scale. WorldView-2 satellite imagery of Spermonde Archipelago, Indonesia obtained in September 2012 was analyzed and classified into four typical substrates: live coral, dead coral, seagrass and sand. Overall classification accuracy of this map was 81.3% and considered precise enough for subsequent analyses. Three sub-areas (CC: continuous coral reef, BC: boundary of coral reef and FC: few live coral zone) around reef slopes were extracted from the map. Visual transect surveys for several fish species were conducted within each sub-area in June 2013. As a result, Mean density (Ind. / 300 m²) of Chaetodon octofasciatus, known as an obligate feeder of corals, was significantly higher at BC than at the others (p < 0.05), implying that this species’ density is strongly influenced by spatial configuration of its habitat, like the “edge effect.” This indicates that future conservation procedures for coral reef fishes should consider not only coral cover but also its spatial configuration. The present study also indicates that the introduction of a geospatial perspective derived from remote sensing has great potential to progress conventional ecological studies on coral reef fishes.