The Asia-Pacific Rim's transport and telecommunications systems: spatial structure and corporate control since the mid-1980s

There is a need to move from discussing the Asia-Pacific Rim's leading port cities as shipping centres measured by container throughput. This shift in focus involves examining how different transport and telecommunications systems are interacting with each other at an international scale under the power and control of major world operators. Using a three-level network framework an attempt is made to illustrate and explain the formation of multilayered trade/communications corridors and hubs/headquarters in the Asia-Pacific Rim since the mid-1980s and to identify the factors affecting them. From this examination of spatial structure and corporate control three levels of cities in the Asia-Pacific Rim are recognised: first level cities with strong corporate representation in container shipping, air cargo, air passenger and telecommunications; second level cities with marked corporate representation in one but not all four modes; and third level cities with no marked corporate representation in any mode but with strong throughput. The third level includes the Asia-Pacific Rim's ‘true’ port cities. Perhaps the ambiguous category ‘port city’ should be reserved for them. This revised version was published online in July 2006 with corrections to the Cover Date.     

No evidence for thermogenic methane release in coal from the Karoo-Ferrar large igneous province

The Early Jurassic Toarcian oceanic anoxic event (T-OAE) and concurrent negative carbon-isotope (δ¹³C) excursion have recently been attributed to either the release of methane (CH₄) clathrates or thermogenic CH₄ gas associated with the Karoo-Ferrar large igneous province (LIP) into coals and organic-rich shales. ¹²C-enriched thermogenic CH₄ production associated with the Karoo-Ferrar would result in residual material being ¹²C-depleted nearer the intrusions. In this study, geochemical analyses (carbon isotopes, volatile matter (VM), vitrinite reflectance (R_o)) are reported for two coal transects associated with dykes intruding the No. 4L coal in the Highveld Coalfield, Karoo Basin, South Africa. VM decreases from over 35% to around 15% in one transect, and the second transect shows a less pronounced decrease (from > 25% to ~ 16%). Accompanying the decrease in VM content is an increase in R_o from background levels of around 0.7% to over 4% adjacent to the dyke; used as a palaeo-geothermometer, R_o values indicate background temperatures of ~ 100 °C increasing to > 300 °C close to the contact. Despite changes in VM and R_o, there are no significant changes in δ¹³C, certainly not of the magnitude that would be expected associated with large-scale thermogenic CH₄ generation. These and other Gondwanan coals have low vitrinite and liptinite contents (components more prone to CH₄ generation), in part explaining the modest decreases in VM adjacent to the dykes. This, combined with the relatively narrow metamorphic aureole surrounding the intrusions and the likelihood that at least some of the volatiles generated by the intrusion were trapped as coalbed CH₄ or condensed as pyrolytic carbon, suggests only limited CH₄ release. In addition, based on original estimates of moisture contents in these coals and the depth at time of intrusion (1,000–2,000 m) the dykes would have lost most of their energy heating and evaporating water, thus having very little remaining energy to generate thermogenic CH₄.     

Preliminary laboratory studies of the optical scattering properties of the crystal clouds

Ice crystal clouds have an influence on the radiative budget of the earth; however, the exact size and nature of this influence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90° than do water droplets, and that the halo effects are visible in a laboratorygenerated cloud when the ice crystal concentration is sufficiently small to prevent masking from multiple scattering.     

Physical Controls on Spatial Variability in Decomposition of Organic Matter in Lake Kinneret,Israel

High resolution chemical data collected during summer 2003 indicate that the lower water mass (LWM) of the thermally stratified Lake Kinneret (LK) can be subdivided into three layers: a benthic boundary layer (BBL), overlain by the hypolimnion (HYP), and on top, the lower part of the metalimnion (ME-L). After onset of thermal stratification, the BBL is the first layer that turns anoxic, followed shortly afterward by the ME-L, while the HYP remains oxic and has relatively higher pH until later in summer. Thus, during the early summer, the HYP forms an oxygen-containing layer in-between two DO-deficient layers. Somewhat later, the HYP is characterized by still having significant levels of nitrate NO₃, while in both adjacent layers nitrate is already removed through denitrification. The mechanisms controlling the gradual decline of dissolved oxygen (DO) in the HYP during the summer were studied. The seasonal mean lake-wide vertical eddy diffusion coefficient in this layer, evaluated from heat flux measurements, is approximately 4 × 10⁻⁶ m² s⁻¹. The vertical oxygen flux due to diffusion from within the HYP toward its oxygen-deficient upper and lower boundaries accounts for most of the slow summer decline in DO in this layer. A smaller portion of this decline can be attributed to in-layer respiratory processes. The low turbidity, relatively high pH, and slow accumulation rate of NH₄ in the HYP support the notion that the slower mineralization processes occurring in this layer result from relatively low ambient concentrations of biodegradable organic matter, most probably due to the short residence time of the particles settling through this layer.