Geography,segregation and American urban society

Despite the growth and increasingly dominant role of cities within its economic, social and political life, the United States still possesses many ingrained ‘rural’ traits that served to characterize the emergent nation in the late 1700s. While an increase in the scale of settlement and related increasing differentiation and segregation between rich and poor, white and coloured, has taken place, within the city we continue to discern the manifestations of traditions which represent the basis of the American heritage. “What are the roots that clutch, what branches grow out of this stony rubbish?”     

How turbidity current frequency and character varies down a fjord‐delta system: Combining direct monitoring,deposits and seismic data

Submarine turbidity currents are one of the most important processes for moving sediment across our planet; they are hazardous to offshore infrastructure, deposit petroleum reservoirs worldwide, and may record tsunamigenic landslides. However, there are few studies that have monitored these submarine flows in action, and even fewer studies that have combined direct monitoring with longer‐term records from core and seismic data of deposits. This article provides one of the most complete studies yet of a turbidity current system. The aim here is to understand what controls changes in flow frequency and character along the turbidite system. The study area is a 12 km long delta‐fed fjord (Howe Sound) in British Columbia, Canada. Over 100 often powerful (up to 2 to 3 m sec^?1) events occur each year in the highly‐active proximal channels, which extend for 1 to 2 km from the delta lip. About half of these events reach the lobes at the channel mouths. However, flow frequency decreases rapidly once these initially sand‐rich flows become unconfined, and only one to five flows run out across the mid‐slope each year. Many of these sand‐rich, channelized, delta‐sourced flows therefore dissipated over a few hundred metres, once unconfined, rather than eroding and igniting. Upflow migrating bedforms indicate that supercritical flow dominated in the proximal channels and lobes, and also across the unconfined mid‐slope. These supercritical flows deposited thick sand beds in proximal channels and lobes, but thinner and finer beds on the unconfined mid‐slope. The distal flat basin records far larger volume and more hazardous events that have a recurrence interval of ca 100 years. This study shows how sand‐rich delta‐fed flows dissipate rapidly once they become unconfined, that supercritical flows dominate in both confined and unconfined settings, and how a second type of more hazardous, and much less frequent event is linked to a different scale of margin failure.     

Palestinian refugees: empirical and qualitative considerations

This paper focuses attention upon the existence of a Palestinian refugee population in the land about and immediately adjacent to Israel. It considers both the creation and the continuation of the refugee state within the host communities and the growth occurring within the refugee populations themselves. Some attention will be directed to a consideration of the refugee population vis à vis the dramatic upsurge in the number of former Soviet-CIS Jewish immigrants into Israel, that create further and deepening pressures upon land and water resources and Palestinian refugee matters. The paper is in three main parts following upon a general introduction to refugee studies. Firstly, a quantitative assessment of the Palestinian refugee population incorporates an empirical presentation of base Palestinian population totals and distributions, directing particular attention to growth in the period 1974–90. Secondly, several perspectives are presented as a backcloth to understanding certain of the continuing and mounting tensions within the Middle East in general and among the Palestinian refugee population in particular. Personal experiences of the writer as fieldworker are presented to provide a more general appreciation and awareness of the particular refugee situation within the Occupied Territories. The third part considers the developing and extending yet increasingly fundamental political consciousness among the Palestinian refugees, and certain envisaged reactions, and speculates upon continuing frustrations that are seen to be leading on to dramatic, mounting and extending violence.     

Powerful unconfined turbidity current captured by cabled observatory on the Fraser River delta slope,British Columbia,Canada

Turbidity currents are one of the main sediment transport processes on Earth, yet are notoriously difficult to monitor directly. This article presents the first direct and high bandwidth observation of a turbidity current using a cabled sea floor observatory. On 5 June 2012, a platform on Ocean Networks Canada, located in 107 m of water on the Fraser River delta slope, was displaced downslope and severed from its data cable. The platform weighed ca 1000 kg in water. The event took place during high river discharge, high tides and rapid sediment accumulation on adjacent upslope areas of the sea floor. Data recorded as it tumbled downslope allow a reconstruction of the flow, which is inferred to have been an unconfined turbidity current. Lines of evidence indicate that the flow came in as a bed hugging wedge, and built up to between 1 m and 4 m in height as the head passed through. Comparison with laboratory data suggest that the flow was initially supercritical. While the adjacent slope offset to the north clearly exhibits change over an annual resurvey period, the bathymetry directly at the event location show no resolvable change over a period from seven months before the event to one month after. Sediment cores collected after the event were pervasively biototurbated and they contain no obvious deposit connected with this event. The remarkable aspects of this research follow. The flow was powerful enough to carry a 1 tonne platform and sever a heavily armoured cable. The current occurred on the unchannelized open slope. This powerful event failed to cause discernible seabed elevation change. The flow was triggered by tidal conditions. The event was detected by a purpose‐designed cabled observatory, thus providing high bandwidth data and also alerting researchers in real time to mount follow‐on investigations.     

Field analysis of heavy metals by portable digital voltammeter

Water samples and acid extractions of stream sediments, gossans, soils and crushed pisolite samples have been analyzed in the field, using a portable digital voltammeter. This instrument, which uses the polarographic technique of anodic stripping voltammetry, can analyze to a sensitivity of 1 ppb in waters and acid extractions — equivalent to approximately 1 ppm in solid samples. The technique is at present suitable for analysis of Cd, Ph, Cu, Bi (and Zn if Cu is at low concentrations); future developments could extend the instrument capabilities to include Hg, Ag, Au, As, Sb and other elements of interest to the exploration geochemist. Water samples can be analyzed directly in the analytical cell of the instrument; for rocks, soils and biological materials an acid extraction procedure must be employed, and an aliquot of the acid extract added to the 40ml of cell electrolyte. Where a partial extraction technique is employed, e.g. by using HCl and ascorbic acid, the technique clearly does not provide total elemental analyses for the solid material. However, comparison of field results with conventional analytical methods (e.g. AAS) suggests that the technique is sufficiently accurate for the use of in-field, inter-active sampling (i.e. where the results of analysis are used to influence future sampling locations and densities) to be considered in certain types of geochemical exploration programs.     

Ciliate epibiont effects on feeding,energy reserves,and sensitivity to hydrocarbon contaminants in an estuarine harpacticoid copepod

Although epibiotic protozoans are commonly observed on the chitinous exoskeleton of aquatic crustaceans, relatively little is known about their ecological significance. The significance of protozoan epibionts on benthic copepods has never been examined.Coullana sp., a meiobenthic harpacticoid copepod, is abundant in Louisiana salt marshes and has high incidence (∼50%) of ciliate epibionts. Field and laboratory grazing experiments indicated that ciliate epibionts did not hinderCoullana feeding on benthic or planktonic algae. Contrary to expectations,Coullana with high levels of ciliate epibionts (>8 ind⁻¹) grazed at a significantly higher rate on¹⁴C-labeled benthic diatoms added to intact sediment cores than didCoullana with no epibionts.Coullana neutral lipids (examined using Nile Red, a hydrophobic fluorophore) were not significantly influenced by the presence of ciliate epibionts, suggesting that copepods are able to compensate for any additional energetic demands imposed by epibionts. Epibiont effects onCoullana susceptibility to hydrocarbon contaminants were measured by examining survivorship in diesel-spiked sediments. The presence of ciliate epibionts significantly decreased survivorship at relatively low PAH concentrations (12.8 ppm). While ciliate epibionts onCoullana do not dramatically alter total food acquisition or energy storage, they may cause stress, which in turn makesCoullana more susceptible to contaminants and possibly other natural stressors such as food limitation.