Biotransference and biomagnification of selenium copper,cadmium, zinc,arsenic and lead in a temperate seagrass ecosystem from Lake Macquarie Estuary,NSW, Australia

In this study the biotransference of selenium copper, cadmium, zinc, arsenic and lead was measured in a contaminated seagrass ecosystem in Lake Macquarie, NSW, Australia, to determine if biomagnification of these trace metals is occurring and if they reach concentrations that pose a threat to the resident organisms or human consumers. Selenium was found to biomagnify, exceeding maximum permitted concentrations for human consumption within carnivorous fish tissue, the highest trophic level examined. Selenium concentrations measured within carnivorous fish were also above those shown to elicit sub-lethal effects in freshwater fish. As comparisons are made to selenium concentrations known to effect freshwater fish, inferences must be made with caution. There was no evidence of copper, cadmium, zinc or lead biomagnification within the food web examined. Copper, cadmium, zinc and lead concentrations were below concentrations shown to elicit adverse responses in biota. Copper concentrations within crustaceans M. bennettae and P. palagicus were found to exceed maximum permitted concentrations for human consumption. It is likely that copper concentrations within these species were accumulated due to the essential nature of this trace metal for many species of molluscs and crustaceans. Arsenic showed some evidence of biomagnification. Total arsenic concentrations are similar to those found in other uncontaminated marine ecosystems, thus arsenic concentrations are unlikely to cause adverse effects to aquatic organisms. Inorganic arsenic concentrations are below maximum permitted concentrations for human consumption.     

The Keisarhjelmen detachment records Silurian–Devonian extensional collapse in Northern Svalbard

At the junction of the Atlantic and Arctic margins, the crustal‐scale Keisarhjelmen detachment of north‐west Svalbard records previously unrecognised magnitudes of extension. The detachment separates a corrugated metamorphic core complex in the footwall from a mantling Devonian supradetachment basin in the hangingwall. The detachment has a top‐N displacement of more than 50 km, which is aligned with the map‐scale corrugations, and an upwards ductile to brittle transition with shear related footwall retrogression. This configuration has striking similarities to extensional collapse detachments in the paired Scandinavian–Greenland Caledonides, but orientation and position link the detachment with the Ellesmerian orogen.     

Palynological studies in the western arm of Lake Superior

Lake Superior sediments contain pollen whose changes through time can be corelated with dated pollen diagrams from small lakes in the region. A core collected in 1972 from the deep trough (265 m) off Silver Bay (47° 09′N, 91°20′W) penetrated 6.25 cm of taconite tailings, 55 cm of postglacial silty clay, and 93.5 cm of late-glacial varves. Seven levels in the core were dated by stratigraphic and palynological techniques. The varves stopped forming about 9000 years ago, probably when glacial ice retreated to the north shore. The last 100 varves accumulated at about 10 mm/yr, but the average net sedimentation rate subsequently slowed to 0.05 mm/yr until the time of settlement about 1890. The sedimentation rate then increased by a factor of 10, to 0.5 mm/yr until 1956 when taconite processing began. The postsettlement interval can be recognized by marked increases of ragweed and chenopod pollen that result from land disturbance caused by forest clearance and agriculture. The postsettlement interval is also present at the top of six cores from four other sites in western Lake Superior, collected in water from 25–140 m deep. The postsettlement sedimentation rate varies from 0.1–0.8 mm/yr, suggesting that man has greatly increased sediment yield to the lake in the last 80 years.     

Nonlinear Response of Single Piles in Sand Subjected to Lateral Loads using k hmax Approach

This paper presents results of analysis of full-scale pile load test data of 14 piles embedded in either loose or medium dense sands. The analysis was performed using two methods, p–y curve approach and a more recently developed k_hmax approach. Comparison of the results obtained using both the methods is also presented. A step-by-step analysis procedure is presented for predicting lateral load deflection response of single piles in sand using the k_hmax approach. The results presented show that the k_hmax approach has promise over the p–y curve approach because of its simplicity and the fact that it provides upper- and lower-bound curves, which are valuable guides to making engineering decisions. For loose sands, a new range of k_hmax values is recommended to better predict the lateral load–deflection response of single piles.     

Palynological and Radiocarbon Evidence for Deglaciation Events in the Green Bay Lobe, Wisconsin

A new and significant site of organic silty sand has been found beneath the Valders till at Valders Quarry in northeastern Wisconsin. This is now the earliest known late-glacial site associated with red till ice advances in the western Great Lakes area. Leaves of terrestrial plants washed into a small depression provide a date of 12,965 ± 200 yr B.P. (WIS-2293), which is significantly older than the Two Creeks Forest Bed (ca. 11,800 yr B.P.). Percentage and concentration pollen diagrams suggest that the site was open and distant from a closedPiceaforest. No wood orPiceaneedles have been found. This date is statistically indistinguishable from 12,550 ± 233 yr B.P., the mean of three dates for the end of inorganic varve sedimentation at Devils Lake, 160 km southwest at the terminus of the Green Bay Lobe. Assuming that the Green Bay lobe vacated its outermost moraine in the interval from 13,000 to 12,500 yr B.P., only a short time was available for retreat of the ice margin over 350 km, drainage of red sediment from Lake Superior into the Lake Michigan basin, readvance of over 250 km, retreat of at least 80 km, and advance to this site. The time for these events appears to have been too short to resolve by current radiocarbon technique. This extremely rapid collapse of the Green Bay lobe has a calibrated age of about 15,000 cal yr B.P., about that of the dramatic warming seen in the Greenland ice cores.     

Near-surface foundation level assessment from seismic measurements: a case study of north Jeddah City,Saudi Arabia

In this study, a comprehensive assessment on the generation mechanism, distribution characteristics, and extension rules of structure cracks was conducted by in situ monitoring and field investigation in the Chengchao Iron Mine. Structure cracks are affected by many factors, e.g., surface deformation, structure strength, occurrence position, and machine vibration. They initially occur in a structure when the strength of the structure is not enough to resist the inner strain as surface deformation increases. In contrast, increases in width and length of structure crack exert stress release in the structure and thus decrease structure deformation surrounding the crack. A great ground crack may adversely aggravate structure cracking and release the stress of surrounding rock masses. In addition, micro cracks in rock masses provide favorable conditions for the generation and extension of cracks, resulting that cracks occur in shaft walls more easily and extend towards the deeper. The initial distribution of cracks is generally consistent with such micro cracks. Subsequently, cracks in deep rock masses will extend along the strike of the mined-out area as surface deformation increases. Sensibilities to cracking of structures are changed by their different strain resistances and become stronger from bolt-shotcrete shaft, bolt-shotcrete tunnel, and brick-concrete building to brick wall. Based on distribution characteristics of cracks and wave velocity in rock masses, the overlaying strata affected by underground mining can be divided into four zones: broken zone, broken transition zone, crack generation zone, and micro deformation zone.