GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
31 巻 , 6 号
選択された号の論文の5件中1~5を表示しています
  • Chen-Tung Arthur Chen, Bing-Jye Wang
    1997 年 31 巻 6 号 p. 345-355
    発行日: 1997/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    One hundred forty three lakes, ponds and reservoirs in Taiwan and the offshore islands Penghu (Pescadores), Kinmen (Quemoy), Matsu, Hsioliuchiu, Lutao and Lanyu have been investigated in the past few years. Hereafter, the term lake is generally used for the three bodies of water discussed. According to the rock and soil compositions, the authors divided Taiwan into three regions. Zone I consists mainly of igneous rocks with lakes generally of low buffering capacity and low pH. Zone II consists mainly of noncalcareous sedimentary and metamorphic rocks with lakes of varying buffering capacity and pH. Those at high elevations generally have low buffering capacity and pH but many at low elevations have high alkalinity and pH. Zone III consists mostly of gravel, sand, clay, limestone and the alluvium zone with lakes of high buffering capacity and pH. About 27% of the lakes have low alkalinity and are mostly located in Zones I and II. These lakes are more threatened by acid rain and many indeed are acidic. They are mostly alpine and subalpine lakes or are located near the Tatun and Keelung volcano groups. The NTA (normalized total alkalinity) is used as an acidification index. The decrease of the NTA for Lovers Lake, Yuen-Yang Lake, Carp Lake (Hualien County) and Little Ghost Lake suggested acidification. The other lakes' NTA mostly remained constant. We also measured the concentrations of 53 chemical species: Ag, Al, Au, B, Ba, Be, Bi, Ca, Cd, C2H5COO-, Cl-, CO, Cr, Cu, Dy, Er, Eu, Fe, Gd, Ge, HCO3-, Hg, In, K, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, NO3-, NO2-, Pb, Pd, PO4-3, Pr, Sc, Si, Sm, Sr, SO4-2, Ta, Th, Te, Ti, Tm, V, Y, Yb, Zn and Zr in lake water samples. These concentrations were mostly within the limits set by the Environmental Protection Agency. Lovers Lake has lower pH but higher heavy metal concentrations than other lakes.
  • Nikos Th. Skoulikidis, Joseph C. Kondylakis
    1997 年 31 巻 6 号 p. 357-371
    発行日: 1997/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    To better understand the biogeochemical factors affecting seasonal variations of major Greek river water composition, multivariate analyses on four seasonal data matrices of thirteen major Greek rivers and tributaries have been applied. The main factors governing river water composition were “carbonate dissolution”, which is the most important factor in spring, autumn and winter, and “pollution”, which is most important in summer. Less important factors are “biological activity”, which predominates during the dry seasons and “sodium chloride enrichment”, which slightly influences river waters, primarily in spring, due to flushing processes. The Greek river catchments are characterized by different climatic, hydrographic, morphologic, petrographic and vegetative features and varying pollution impact. Nevertheless, biogeochemical processes controlling river composition appear to follow certain common seasonal trends, as they would be a part of an integrated ecosystem.
  • Shinichiro Noriki, Takehiko Shiribiki, Hodaka Yokomizo, Koh Harada, Sh ...
    1997 年 31 巻 6 号 p. 373-382
    発行日: 1997/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    Sequential methods to measure the concentrations of chemical elements in (1) acid soluble, (2) reducible, (3) oxidizable, (4) opal, and (5) refractory fractions of settling particles were developed. Concentrations of Cu and Ni of settling particles collected with HX-10 type sediment traps at 1.2 km and 4.8 km depths at 44°04'N, 155°03'E were measured by the methods. Copper was enriched in the reducible and oxidizable fractions, especially in the oxidizable fraction, both at 1.2 km and 4.8 km. The degree of vertical increase in Cu concentration of the oxide fraction is the largest among the five fractions. Nickel was most enriched in the oxide fraction with a concentration in the oxide fraction three times that of the oxidizable fraction. Nickel concentrations of the acid soluble and the reducible fractions decreased with depth. The results suggest that (1) Cu and Ni are incorporated in surface water into organic material and calcium carbonate particles, respectively, (2) organic material and calcium carbonate particles decompose in the water column, (3) Cu and Ni are regenerated from these particles, and (4) scavenging of Ni in intermediate and deep waters is not significant.
  • Pawel M. Lesniak, Hitoshi Sakai, Jun-ichiro Ishibashi, Hiroshi Wakita
    1997 年 31 巻 6 号 p. 383-394
    発行日: 1997/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    Mantle derived helium with R/RAM ratios up to 1, which accompanies CO2 exhalations and cold CO2-rich carbonated waters, has been found to escape through the 40 km thick continental lithosphere in the Outer Carpathians. Revised 4He/20Ne ratios of mantle and crust (6818 and 2.53 × 107, respectively) allow the estimation of the respective contribution of mantle, crust and air-derived helium to the bulk helium. Although isotopic ratios of noble gases attest to a mixing process which takes place between crust and mantle gases, carbon isotope ratios of the CO213C of -8.9 to -1.8 per mil) do not correlate with helium isotope ratios (R/RA), indicating complex processes of CO2 derivation. The R/RA ratios in methane-dominated gases are similar to those in CO2-rich gases, designating similar mode of helium supply. The CO2/3He ratios are up to 2 orders of magnitude higher than the secular CO2/3He ratio of mantle gas emanations at ocean ridges. It suggests that the recycled crustal carbon rather than mantle carbon is the principal source of CO2. The fluids of interest with their noble gases and other isotopic signatures and high concentrations of dissolved carbonates are similar to hydrothermal solutions observed in active marginal basins.
  • Takeshi Hanyu, Ichiro Kaneoka
    1997 年 31 巻 6 号 p. 395-405
    発行日: 1997/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    The usefulness of noble gas isotope systematics for understanding the volcanic systems is demonstrated in the case of Unzen Volcano, Japan. Noble gas concentrations and Ar isotope ratios were determined for coexisting plagioclase, hornblende and biotite in two dacitic volcanic rocks. Different species of minerals coexisting in a magma show different 40Ar/36Ar, and the 40Ar/36Ar is correlated to the grain sizes of the phenocrysts, indicating that they had crystallized in an evolving system of the magma. The variation of 40Ar/36Ar observed among samples can be explained by a two-component mixing: magmatic Ar and atmosphere-derived Ar. In order to explain the variation of 40Ar/36Ar, we propose a magmatic model in which the 40Ar/36Ar of magma had gradually decreased due to addition of atmosphere-derived Ar and, in the same sequence of time, phenocrysts had crystallized one after another as cooling of the magma had proceeded. Groundwater is the most probable candidate as carrier of atmosphere-derived Ar although crustal contamination is not completely excluded.
feedback
Top