The Response of Macrobenthic Communities to Environmental Variability in Tropical Coastal Waters

The relative contributions of spatial and temporal fluctuations are different in shaping natural communities in a tropical coastal/estuarine system. Understanding how coastal communities respond to these fluctuations is still equivocal, and thus, available data are rare. Here, multiple analytical approaches were used to identify key spatial and temporal factors, and to quantify their relative roles in shaping a macrobenthic community through space (contamination degree, physical parameters, and sediment characteristics) and time (climatic factors, season, and year). A dataset of eight sampling times was analyzed over a period of 2 years, in which macrobenthic species abundances were sampled. A total of 33 species were identified, including 18 bivalves, 5 gastropods, and 4 crustaceans. The other taxa were less diverse. The results show that there were no significant temporal changes of macrobenthic community structure, but spatial changes were significant and synchronized with environmental factors (i.e., sediment characteristics, water depth, and the distance from anthropogenic sources). This study demonstrates that spatial factors played a primary role in structuring of macrobenthic assemblages, whereas the influence of temporal factors appeared less across geographically distinct sites. Thus, temporal variation of a coastal macrobenthic community appears to be controlled by partly different processes at different scales.     

A study of the behaviour of brittle rocks subjected to confined stress based on the Mohr–Coulomb failure criterion

In this study the relationship between brittle rocks’ behaviour and uniaxial compression stress is obtained based on the Mohr-Coulomb failure criterion and the behavioural characteristics of brittle rocks under uniaxial compression stress are investigated. According to the laboratory uniaxial compression tests on granite rocks, and also available results in the literature, required parameters in the study are obtained. It is indicated that the behaviour of brittle rocks which is affected by uniaxial compression is function of cohesion. In the other words, cohesion changes as the uniaxial compression increases. Also, in yield point where its stress is equivalent to the uniaxial compressive strength, the cohesion maximises. By suggesting a new viewpoint to the Mohr’s circle, normal stresses on failure plane, shear stresses tangential to the failure plane and hydrostatic stresses are investigated. Results show that, normal stress on the failure plane in yield point of the behavioural curve equals zero and shear stress tangential to the failure plane is maximum which is equal to the maximum rocks’ natural strength. Also, in this point the strength is equi-pressure, therefore the stress is of hydrostatic type.     

Landslide susceptibility mapping based on frequency ratio and logistic regression models

The aim of this study is to apply and compare a probability model, frequency ratio and statistical model, and a logistic regression to Sajaroud area, Northern Iran using geographic information system. Landslide locations of the study area were detected from interpretation of aerial photographs and field surveys. Landslide-related factors such as elevation, slope gradient, slope aspect, slope curvature, rainfall, distance to fault, distance to drainage, distance to road, land use, and geology were calculated from the topographic and geology map and LANDSAT ETM satellite imagery. The spatial relationships between the landslide location and each landslide-related factor were analyzed and then landslide susceptibility maps were produced using the frequency ratio and forward stepwise logistic regression methods. Finally, the maps were tested and compared using known landslide locations, and success rates were calculated. Predicted accuracy values for frequency ratio (79.48%) and logistic regression models showed that the map obtained from frequency ratio model is more accurate than the logistic regression (77.4%) model. The models used in this study have shown a great deal of importance for watershed management and land use planning.     

Heavy metal contamination in water and sediment of the Port Klang coastal area, Selangor, Malaysia

This investigation presents the temporal and spatial distribution of heavy metals (As, Cd, Cr, Cu, Ni, Pb, Hg, and Zn), in water and in sediments of Port Klang, Malaysia. Water and sediment samples were collected from 21 stations at 3-month intervals, and contamination factor $ (C_{\text{f}} ) $ and contamination degree $ (C_{\text{d}} ) $ were calculated to estimate the contamination status at the sampling stations. Cluster analysis was used to classify the stations based on the contamination sources. Results show that concentrations of As, Cd, Hg, and Pb in sediment and As, Cd, Hg, Pb, Cr, and Zn in water were significantly higher than the background values at which these metals are considered hazardous. The main sources of heavy metal contamination in Port Klang were industrial wastewater and port activities.     

Control of Cambrian evaporites on fracturing in fault-related anticlines in the Zagros fold-and-thrust belt

Orientation and distribution of fractures in the Oligocene–Early Miocene Asmari Formation (a major reservoir rock of the Zagros petroleum system) were investigated in two anticlines of the Zagros fold-and-thrust belt. The Sim and Kuh-e-Asmari anticlines developed in the areas of the Zagros characterized by the occurrence and absence of Cambrian evaporites at the bottom of the stratigraphic pile, respectively. The aim was to outline major differences in terms of fracture spacing and saturation. Organic matter maturity and clay minerals-based geothermometers suggest that the depth of deformation for the top of the Asmari Formation in the Kuh-e-Asmari anticline was in the range of 1.5–2.7 km assuming a geothermal gradient of 22.5 °C/km. The Asmari Formation in the Sim anticline probably experienced a slightly deeper sedimentary burial (maximum 3 km) with a geothermal gradient of 20 °C/km. The spacing of fractures is generally 2–3 times larger (i.e., strain accommodated by fracturing is smaller) in the Sim anticline than in the Kuh-e-Asmari anticline. This is consistent with regional geological studies, analogue, and numerical models that suggest that thrust faults geometry and related folds are markedly different in the absence or presence of a weak decòllement (evaporites). The larger spacing in the Sim anticline is also consistent with higher temperature predicted for the Asmari Formation in this area. By contrast, the orientation of fractures with respect to the fold axes is the same in both anticlines. The fracture systems are rather immature in both anticlines. The amount and density of fractures in the twofolds are controlled by regional (occurrence/absence of salt and probably different burial), rather than local features (fold geometry).     

Optimal Port Design Minimizing Standing Waves with A Posteriori Long Term Shoreline Sustainability Analysis

China Ocean Engineering - Optimization theory is applied to a coastal engineering problem that is the design of a port. This approach was applied to the redesign of La Turballe Port in order to...     

A detailed receiver function image of the lithosphere beneath the Kopeh-Dagh (Northeast Iran)

The Kopeh-Dagh fold belts are among the most seismically active areas in Northeastern Iran, which build the northern part of the Alpine–Himalayan orogen in western Asia. They act as the abrupt northeastern limit to active deformation in Iran. We perform a combined P and S receiver function analysis to detect the major discontinuities within the lithosphere beneath Northeast Iran. Our results obtained from 12 short period and broadband seismological stations significantly map the lateral variations of the Moho boundary. Based on P receiver functions, we show that the Moho depth varies from ～43 km beneath the southern Kopeh-Dagh foreland basin to ～49 km below the northern part of the basin. S receiver functions reliably reveal an average Moho depth of ～50–55 km beneath the Kopeh-Dagh mountain range showing the regional shortening in response to the collision of Arabia with Eurasia. Furthermore, we observe clear conversions with negative polarity at ～8.5–9.5 s in S receiver functions, which could be related to the conversion at the lithosphere–asthenosphere boundary. This may show a relatively thin continental lithosphere of about 85–95 km beneath the Kopeh-Dagh implying that the lithosphere was influenced by geodynamical reworking processes in the past.     

Early Berriasian ammonites from Shal, Talesh region (NW Alborz Mountains, Iran)

An early Berriasian (Berriasella jacobi Zone) ammonite fauna is described for the first time from the Alborz Mountains in northwest Iran. It has been collected from a section located near the village of Shal (Talesh region); in addition to rare phylloceratids, lytoceratids and Neolissoceras, the majority of ammonites belong to the neocomitid subfamily Berriasellinae. With the exception of a new genus and species, Taleshites fuersichi, these taxa are common in European and North African Tethyan successions. Associated calpionellids confirm the early Berriasian age of the ammonite-bearing levels.     

Optimally locating additional drill holes in three dimensions using grade and simulated annealing

Average kriging variance is a standard tool used in optimization of the location of additional drill holes. However, this tool cannot distinguish between areas with different priorities. This limitation could be eliminated by using weighted average kriging variance. This paper extends the problem of optimal location to three dimensional cases, use grade as a weight and search optimum locations by simulated annealing. Weighted average kriging variance is used as objective function. The method is applied to a copper deposit. Results have shown that weighting of the estimation variance with ??grade?? is effective only when the difference among the grades estimated for different blocks is considerable.     

Numerical simulation of waves in the Caspian Sea: calibration and verification of the observation-based source terms

Ocean Dynamics - Third-generation models employ a host of parameterization schemes to consider the input wind forcing and the wave energy dissipation under different physical settings and...