Organizational Dynamics of the U.S. Logistics Industry: An Economic Geography Perspective*

Although the logistics industry provides critical services to all sectors of the economy, few studies exist in economic geography that examine and explain the organizational dynamics of this industry. This article highlights the significance of the logistics industry in contemporary industrialization and argues that an enriched understanding of the interaction between technology and space can be achieved by examining the evolution of an industry that plays a central role in the contemporary economy. We focus on dimensions that are identified as particularly important: organizational, geographic, and risk and security.     

Mixed layer depth climatology of the North Pacific based on Argo observations

A monthly mean climatology of the mixed layer depth (MLD) in the North Pacific has been produced by using Argo observations. The optimum method and parameter for evaluating the MLD from the Argo data are statistically determined. The MLD and its properties from each density profile were calculated with the method and parameter. The monthly mean climatology of the MLD is computed on a 2° × 2° grid with more than 30 profiles for each grid. Two bands of deep mixed layer with more than 200 m depth are found to the north and south of the Kuroshio Extension in the winter climatology, which cannot be reproduced in some previous climatologies. Early shoaling of the winter mixed layer between 20–30°N, which has been pointed out by previous studies, is also well recognized. A notable feature suggested by our climatology is that the deepest mixed layer tends to occur about one month before the mixed layer density peaks in the middle latitudes, especially in the western region, while they tend to coincide with each other in higher latitudes.     

Fractionation of sulfur isotopes and selenium between coexisting sulfide minerals from the Besshi deposit,Central Shikoku,Japan

Fractionation of sulfur isotopes and selenium was measured between coexisting pyrite and chalcopyrite and between coexisting pyrrhotite and chalcopyrite from the Besshi deposit of Kieslager-type, Central Shikoku, Japan. In all the pyrite-chalcopyrite pairs studied, ³⁴S is enriched in pyrite relative to chalcopyrite, while selenium is enriched conversely in chalcopyrite relative to pyrite. The mean ³⁴S_py-cp value is +0.53±0.36 per mil, and the mean value of the distribution coefficient of selenium, D_cp-py, is 2.58±0.64. In all the pyrrhotite-chalcopyrite pairs studied, the two minerals are very close to each other both in sulfur isotope and Se/S ratios. The mean ³⁴S_po-cp value is –0.08±0.16 per mil and the mean D_cp-po value is 0.99±0.05. The results have been discussed in comparison with similar data obtained for the Hitachi deposits of Kieslager-type, Japan (Yamamoto et al. 1983).     

Effect of ocean acidification on coastal phytoplankton composition and accompanying organic nitrogen production

The effect of ocean acidification, caused by the increase in pCO₂ in seawater, on phytoplankton population and on related organic nitrogen production was experimentally examined by use of a natural coastal microbial population. pCO₂ and pH were controlled by aeration with air in which pCO₂ was at the current level (control), for which ambient air was used, and with air in which pCO₂ was ??800?? and ??1200?? ppm, in 500-L culture vessels. The experiment was continued for 15?days after addition of the inorganic nutrients such as nitrate, phosphate, and silicate. During most of the experimental period, a minor increase in phytoplankton biomass was noted, probably because of low irradiance, an increase in phytoplankton biomass was observed at the end of the experiment. Flow cytometric and microscopic observations revealed that this increase was because of Chrysochromulina sp. (Haptophyceae). The growth of Chrysochromulina sp. was most obvious in the control vessel, and tended to be obscured by increasing pCO₂ (decrease in pH), indicating the possibility that ocean acidification inhibits the growth of specific phytoplankton groups, for example Chrysochromulina sp. Production of particulate organic nitrogen (PON), determined by the ¹⁵N tracer method, also diminished under acidified conditions compared with that at the current level.     

Organic micropollutants in marine plastics debris from the open ocean and remote and urban beaches

To understand the spatial variation in concentrations and compositions of organic micropollutants in marine plastic debris and their sources, we analyzed plastic fragments (∼10 mm) from the open ocean and from remote and urban beaches. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), dichloro-diphenyl-trichloroethane and its metabolites (DDTs), polybrominated diphenyl ethers (PBDEs), alkylphenols and bisphenol A were detected in the fragments at concentrations from 1 to 10,000 ng/g. Concentrations showed large piece-to-piece variability. Hydrophobic organic compounds such as PCBs and PAHs were sorbed from seawater to the plastic fragments. PCBs are most probably derived from legacy pollution. PAHs showed a petrogenic signature, suggesting the sorption of PAHs from oil slicks. Nonylphenol, bisphenol A, and PBDEs came mainly from additives and were detected at high concentrations in some fragments both from remote and urban beaches and the open ocean.     

The use of microstructures for discriminating turbiditic and hemipelagic muds and mudstones

The microstructures of turbiditic and hemipelagic muds and mudstones were investigated using a scanning electron microscope to determine whether there are microstructural features that can differentiate turbiditic from hemipelagic sedimentary processes. Both types of muddy deposits are, in general, characterized by randomly‐oriented clay particles. However, turbiditic muds and mudstones also characteristically contain aggregates of ‘edge‐to‐face’ contacts between clay particles with long‐axis lengths of up to 30 μm. Based on observations of the clay fabric of the experimentally‐formed muds settled from previously agitated muddy fluids, these types of aggregates, hereafter referred to as ‘aggregates of clay particles’, are interpreted as having been formed by the collision of component flocs in turbulent fluids. Furthermore, some aggregates of clay particles have ‘face‐to‐face’ contacts between clay particles; this is similar to face‐to‐face aggregates characteristically developed in fluid‐mud deposits that are commonly recognized only in turbiditic mudstones, indicating the possibility of a final stage of deposition under highly‐dense conditions, such as temporary fluid muds. In conjunction with earlier proposed lithofacies‐based and ichnofacies‐based criteria, aggregates of clay particles should be useful for the differentiation of turbiditic and hemipelagic muddy deposits, particularly with limited volumes of non‐oriented samples from deep‐water successions.     

Ore mineralogy and sulfur isotope study of the massive sulfide deposit of Filon Norte,Tharsis Mine,Spain

The volcanogenic massive sulfide deposit of Filon Norte at Tharsis is hosted by carbonaceous black slate and connected only partly with stockwork veins. The massive ores are usually composed of fine-grained pyrite with subordinate amounts of sphalerite, chalcopyrite, galena and arsenopyrite. Monoclinic pyrrhotite sometimes occurs in massive pyritic ores in the apparently middle and upper horizons of the orebody, and siderite-rich ores are interstratified with compact pyritic ores in the apparently lower horizons. From the occurrence of monoclinic pyrrhotite, together with the FeS contents of sphalerite mostly ranging from 11 to 16 mol %, it is inferred that the sulfide minerals of the massive orebody were precipitated in euxinic muds on the sea-floor at temperatures below 250°C. The negatively shifted, highly variable ³⁴S values of the massive ores and their close similarity to those of the underlying black slates strongly suggest that the sulfide sulfur of the massive orebody and the slates is cognate and biogenic.     

Occurrence of phosphatic microfossils in an Ediacaran–Cambrian mid-oceanic paleo-atoll limestone of southern Siberia

New phosphatic microfossils were recently discovered in an Ediacaran–Cambrian mid-oceanic paleo-atoll limestone in the southern Gorny Altai Mountains in southern Siberia. Microfossils with calcium phosphate shells are abundant in the limestone that occurs as an exotic block within a Cambrian accretionary complex in the Kurai area. SEM observations confirm that the calcium phosphatic shells are ellipsoidal and equal-sized, about 200–300 μm in diameter. Shell walls are about 1 μm thick. As the absence of external and internal structures hinders a detailed comparison/identification, these microfossils are tentatively treated here as paleontological problematica. EPMA-analysis confirmed the concentration of elements P and Ca in microfossil shells and the absence in the matrix, suggesting the primary phosphatic composition of the shells. Because phosphatic microfossils are generally scarce in the Ediacaran but abundant from the Lower Cambrian, in particular within pre-trilobitic SSF assemblages, the phosphatic fossil-bearing limestone in the Kurai area possibly belongs to the Lower Cambrian. The present find proves that mid-oceanic paleo-seamounts as well as continental shelf domains had already been inhabited by diverse metazoans in the Ediacaran–Cambrian transitional interval.     

Size distributions of aerosol number concentrations and water-soluble constituents in Toyama, Japan: A comparison of the measurements during Asian dust period with non-dust period

Size-separated aerosol number concentrations and water-soluble constituents were measured in Toyama, the Hokuriku district, near the coast of the Japan Sea, during the spring and summer in 2003. The number concentrations of coarse particles were significantly high in April, which was due to Asian dust events called Kosa in Japanese. Particulate nssCa²⁺, which is mostly present in the coarse-mode particles, was significantly high in April. On the other hand, the concentrations of NH₄⁺ and nssSO₄²⁻, which mainly exist as the accumulation-mode particles were not high in April. The mass-size distributions of water-soluble constituents were compared with the size-separated number concentrations of particles. Backward trajectory analysis was also employed to examine the transport process of the air mass in Toyama.     

Sedimentary Steryl Chlorin Esters (SCEs) and Other Photosynthetic Pigments as Indicators of Paleolimnological Change Over the Last 28,000 Years from the Buguldeika Saddle of Lake Baikal

Detailed depth profiles of photosynthetic pigments in a sediment core (G-12) collected at the BDP93 site, the Buguldeika saddle, of south Lake Baikal, along with depth profiles of total organic carbon (TOC) and biogenic silica, were studied to elucidate the temporal changes of phytoplankton assemblages in the lake during the past 28 kyr. In addition to the quantification of carotenoids by high-performance liquid chromatography with photodiode-array detection (HPLC-PDA), steryl chlorin esters (SCEs) were analyzed by HPLC-PDA, HPLC-mass spectrometry (LC-MS) and sterols in SCEs by gas chromatography–mass spectrometry (GC–MS) to enrich the taxonomical information on the phytoplankton composition. Allochthonous input of organic matter from the Selenga River resulted in the higher TOC contents in core G-12 than in a previously reported core (G-6) collected at another site from the southern basin. The poorer correlation in core G-12 than in G-6 between TOC and chlorophyll-a-originating pigments, which are indicative of autochthonous production, also indicated a significant allochthonous input at the site. The abundance of lutein among the carotenoids detected, and the good correlation of total chlorophyll a and b shows that green algae represented a significant portion of the phytoplankton, accompanying the diatoms at the G-12 site, after the last glacial period. The presence of cryptomonads and cyanobacteria were confirmed from marker carotenoids in the sediment core. GC–MS analysis of sterols in SCEs detected marker sterols of diatoms, green algae, chrysophytes and dinoflagellates. The depth profiles of the measured indicators gave consistent features for temporal changes in phytoplankton assemblage at the G-12 site of Lake Baikal after the last glacial maximum. Notably, the profile of a chrysophyte-specific sterol in SCEs was consistent with the reported distribution of chrysophyte cysts during the Holocene. The presence of phytoplankton, such as green algae, diatoms and chrysophytes, in Lake Baikal during the late last glacial period was indicated by the analysis of sterols in SCEs. Sedimentary carotenoids and sterols in SCEs were found to give complementary information about phytoplankton composition. These molecular indicators allow us to reconstruct past lake phytoplankton assemblages responding to environmental changes with a time resolution as high as age–depth relationship in sediments attainable at present.