Turbidity regimes over fringing coral reefs near a mining site at Lihir Island,Papua New Guinea

An extensive sediment transport survey took place at Lihir Island (Papua New Guinea), where mining operations involve disposal of waste rocks and soil in nearshore waters. To investigate the potential impact of these practices over neighbouring fringing reefs, turbidity and sediment accumulation were measured continuously for extended periods. Turbidity records provided a map of observed impact zones based on turbidity thresholds. The main zoning features were (a) that an extreme turbidity gradient persists between the inner harbour (turbidity levels of 100-1000 mg l(-1)) and the adjacent reefs (turbidity levels in the order of 10 mg l(-1)), and (b) that observed zones conform with pre-operations impact predictions. Accumulation measurements unveiled no significant sediment accumulation over fringing coral reefs. This study contributes to the understanding of the potential impact of sediment discharge to nearshore waters.     

An axisymmetric lagrangian technique for predicting earth penetration including penetrator response

A computational technique for earth penetration is presented which includes the direct coupling between the deformable target model and a deformable model of the penetrator. In this fully Lagrangian approach, both the target and penetrator are discretized to represent the anticipated terradynamic and structural responses. A sliding interface is used between the two models to provide the time-dependent terradynamic-to-penetrator interaction. This technique has the unique advantage of including the target-to-penetrator interaction in one calculation in a continuous and consistent manner. Comparisons of calculated penetration with full-scale field test data are given.     

Experimental techniques for the investigation of dust condensation processes

Two experimental methods by which silicates may be condensed from vapors of their constituents are discussed and compared. Each has some relevance to astrophysical processes, though the experiments are by necessity simpler than the astrophysical environments.Invited contribution to the Proceedings of a Workshop onThermodynamics and Kinetics of Dust Formation in the Space Medium, held at the Lunar and Planetary Institute, Houston, 6–8 September, 1978.     

Choice or circumstance: The UK as the location of asylum applications by Bosnian and Somali refugees

Questions concerning why asylum seekers make their applications in particular countries rather than others have not been fully researched. Some explanation can be found via aggregate migration theories, but there is a need to consider the circumstances of individual movers. Respondents here were drawn from amongst Bosnian and Somali refugees in northern England. The interviews showed that asylum movement is of a variety of types, with two stage migration commonly involved – firstly immediate flight to a neighbouring haven, and secondly on to a more permanent place of settlement. Very few respondents had any real choice in where they ended up. Instead, family circumstances, cultural connections, and the actions of a variety of institutions produced scenarios in which there was generally no alternative to the actual destination arrived at. It is suggested that a mix of individual level and institutional explanations is needed to understand patterns of asylum destinations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Trace-metal pollution of soils in northern England

Data from a regional geochemical survey of topsoils (n=818) in rural and peri-urban areas over a single parent material (Coal Measures) are used to identify two types of trace-metal pollution - severe local contamination at 20 sites and widespread, diffuse pollution in more densely populated areas. Median concentrations of several trace metals in topsoils were significantly higher in areas of high, compared to low, population density (percentage increases in parenthesis): As (31), Cu (39), Fe (7), Mo (26-36), Ni (29), Pb (20), Sn (40), and Zn (11). Four potential pathways of diffuse trace-metal pollution are postulated: coal-ash dispersal, atmospheric aerosols derived from coal combustion, the historical spreading of sewage waste, and those related to road vehicles. The statistical analysis of geochemical data classified by local, human population density can be an effective means of identifying the magnitude and extent of diffuse pollution, and could help to establish natural background levels.     

Seasonal and spatial water quality changes in the outflow plume of the Atchafalaya River,Louisiana, USA

The objective of this study was to examine the interaction between the Atchafalaya River and the Atchafalaya Delta estuarine complex. Measurements of suspended sediments, inorganic nutrients (NO₃ ^?, NH₄ ⁺, PO₄ ^3?), chlorophylla (chla), and-salinity were taken monthly from December 1996 to January 1998. These data were compiled by season, and the Atchafalaya River plume data were also analyzed using the Generalized Additive Model technique. There were significant decreases in NO₃ ^? concentrations during summer, fall, and winter as river water passed through the estuary, that were attributable to chemical and biological processes rather than dilution with ambient water. In some regions there were higher chla concentrations during summer and fall compared to winter and spring, when river discharge and the introduction of inorganic nutrients were highest, suggesting biological processes were active during this study. The presence of NH₄ ⁺, as a percentage of available dissolved inorganic nitrogen, increased with distance from the Atchafalaya River, indicative of remineralization processes and NO₃ ^? reduction. Mean PO₄ ^3? concentrations were often higher in the estuarine regions compared to the Atchafalaya River. During summer total suspended solid (TSS) concentrations increased with distance from the river mouth, suggesting a turbidity maximum. Highest chla concentrations were found in the bayous and shallow water bodies of the Terrebonne marshes, as were the lowest TSS concentrations. The low chla concentrations found in other areas of this study, despite high inorganic nutrient concentrations, suggest light limitation as the major control of phytoplankton growth. Salinity reached near seawater concentrations at the outer edge of the Atchafalaya River plume, but much lower salinities (<10 psu) were observed at all other regions. The Atchafalaya Delta estuarine complex buffers the impact of the Atchafalaya River on the Louisiana coastal shelf zone, with a 41% of 47% decrease in Atchafalaya River NO₃ ^? concentrations before reaching Gulf waters.