[en] Vertical changes in manganese partition and in sulfur, organic carbon, and nitrogen contents were determined for a 10-m core, KH69-2-23, from the Japan Basin. The delta¹³C value of organic carbon was also determined. The change in manganese partition with depth in the core suggests an alteration of the chemical form of manganese during diagenetic process. The contents of total sulfur, organic carbon, and nitrogen vary with depth corresponding very well to that of DCD (dichromate demand). The very high total sulfur content observed in several reduced portions was attributed to active sulfate reduction. A linear correlation between excess sulfur content and delta¹³C value was found in reduced portions. At least nine cycles of oxidized and reduced layers were recognized in the core studied. The cyclic change is discussed in connection with the change in the hydrological condition of the Japan Sea during the Late Pleistocene. (author)

[en] A pore water sampler has been designed and constructed for in situ squeezing of pore waters from marine sediments at different twelve depths including overlying bottom water. The instrument consist of two rigidly connected parts, a 1-m length of SUS tubing (5-cm o.d.) fitted with a sharp tip, and an open work superstructure, that protects parts such as twelve SUS cylinders, tubing connections, etc. Each of the twelve squeezing systems consists of a squeezing port of 2-cm diameter, a 10-m length of teflon tubing, and a spring-loaded cylinder providing the suction. It is lowered into the bottom and full 1-m penetration triggers the system and initiates sampling. At each of the sampling ports water is drawn through a polyethylene porous disk and a filter paper into the teflon tubing storage system and the cylinder. The instrument was operated on board of the R/V Tokai Daigaku Maru II in Shimizu Port and pore waters were obtained. Chemical compositions of the pore waters indicate that microbial sulfate reduction takes place in the sediment of Shimizu Port. The test suggests that the configuration of the instrument could be successful but these are several points to be improved. (author)

[en] Vertical profiles of C_org, S_tot, Br, Co, Zn, V, As, Sb, U, Al, Sc, La, Ce, Eu, Tb, Yb, Lu, Th, Cr, Hf, and Mn were measured mainly by instrumental neutron activation analysis in deep-sea sediment cores from the Japan Sea. These elements are grouped into four types on the basis of their vertical changes: aluminosilicate type (Al, Sc, REE, Th, Cr, and Hf); organic carbon type (C_org, Br, Co, Zn, and V); sulfide-sulfur type (S, As, Sb, and U); and manganese type (Mn and Ce). It is suggested that Mn and Ce are indicators for oxic conditions, Sb and U for mildly reducing conditions, and S and As for euxinic conditions. The change in redox conditions of the bottom water of the sea through the last glacial period is estimated. (J.P.N.)

[en] Aerosol deposits on leaves of various trees, especially cedar in different regions of Japan were collected to characterize the elemental composition using neutron activation analysis, ICP-AES, etc. and also investigate the effects of deposit aerosols on plants and the efficacy as an indicator for air pollution. Compared with the elemental composition of the soil, Se, Cr, Au, Br, As, Sb, Ag, etc. were more abundant in aerosols on cedar leaves. Especially, Sb is thought to be mostly derived from combustion of fossil fuels (exhaust gas from cars, etc.). Since Sb was accumulated on leaves at high levels and the analytical precision for Sb by neutron radioactivation was very high, the element was thought useful as an indicator for air pollution. If the amounts of Sb on the leaves of cedar and pine trees, which are widely distributed in Japan are determined, the degrees of pollution in all regions of Japan would be determined. In cedar trees of Saitama Prefecture where the deposit amounts of aerosols were comparatively larger, 42% of stoma was covered with the deposits, resulting that the rate of cuticular transpiration was increased and the amounts of basic elements leached from the leave surface was also increased. Thus, it was suggested that these changes might be the cause of recent declining of cedars in Japanese urban regions. (M.N.)

[en] Phytoplankton samples were collected during spring bloom seasons of diatom from three coastal areas of Japan by a NORP AC P-25 (25 μm opening) with a NGG52 prenet (335 μm opening) and 25 major and trace elements have been analyzed by INNA. Concentration ranges of analyzed phytoplankton samples are much wider than the concentration ranges compiled by Bowen (1979) except for As, and data of marine phytoplankton samples for Br, Sb, Hf, Sc, La, Ce, Sm and Eu were not included in the compilation. The analyzed 25 elements have been categorized into three groups: elements show positive correlation with Br, positive correlation with Al and no positive correlation with Br nor Al. The marine phytoplankton samples have been plotted on a MKT plot and proved that MKT plot is applicable to marine phytoplankton samples. (author)

[en] The authors have developed a method of graphitization from CO₂ samples for accurate ¹⁴C measurements by accelerator mass spectrometry. Their batch method, using a sealed Vycor tube, reduces the risk of contamination during graphitization and makes it possible to prepare many samples in a short time (typically 20 samples per day). They also describe details of the target-preparation method involving carbon isotopic fractionation during graphitization, yield of graphite from CO₂, ion-beam intensity of the target, and background (or blank) level estimated using bituminous coal

[en] The radioisotopes ²¹⁰Pb and ¹³⁷Cs were measured in twenty sediment cores obtained from Sagami Bay, Japan. Total ²¹⁰Pb concentrations of settling particles, collected by time-series sediment traps moored at 350 m and 20 m above the sea-floor (the water depth of 1550 m) near the deep-sea station SB in the central region of the bay, were also determined in order to estimate their settling fluxes. Mean sedimentation rates calculated from the inventories of ²¹⁰Pb_ex (unsupported) in sediment cores ranged from 0.05 to 0.19 g cm^-2 y^-1. At SB site where 6 cores were collected, the average rate was 0.11 ± 0.02 g cm^-2 yr^-1, which was similar to that calculated under the assumption that the age of the ¹³⁷Cs peak corresponds to its maximum fallout year of 1963. From the results of the time series sediment trap experiment, the average ²¹⁰Pb concentration of settling particles was 264 dpm g^-1 in the upper trap and 248 dpm g^-1 in the lower one, while the annual mean ²¹⁰Pb fluxes were calculated to be 388 dpm m^-2 d^-1 at the upper layer and 1392 dpm m^-2 d^-1 at the lower, respectively. The mass balance calculation of ²¹⁰Pb in the water-sediment column aptly demonstrates that the increase in ²¹⁰Pb flux at the lower layer results from the lateral transport of particulate ²¹⁰Pb near the bottom, and suggests that the amount of particulate ²¹⁰Pb corresponding to ca. 38% of the sinking flux to the bottom is not deposited into sediments but transported seaward through the benthic boundary layer. (author)