48 research outputs found
Geochemistry of Lake Waters from the South Island, New Zealand
Snow and lake water samples from the New Zealand region have
been analyzed for a range of constituents. The results indicate that the lake waters
are generally low in ionic constituents and that these constituents are distributed
uniformly with depth in the lakes. The concentrations of sodium and potassium
in the lake waters indicate that these elements are derived principally by direct
atmospheric transport of marine aerosols. Calcium, magnesium, and silica are
enriched relative to sodium in the lake waters when compared with rainwater
by leaching of the surrounding schist and graywackes in the sequence calcium >
magnesium > silicon silica. SO4 2- is also enriched relative to sodium in the lake
water compared with the precipitation samples
Manganese Crusts and Nodules from the Hawaiian Ridge
Manganese stains, crusts, and nodules are widely distributed on
the insular slopes of the Hawaiian ridge. The thickness of the manganese crusts
depends on depth of water, water circulation, and the age and lithology of
the substrate, and varies from absent to stains off the island of Hawaii to a
maximum of 5 cm in the vicinity of Midway. Scanning electron microscope
studies indicate that the internal structure of the manganese crusts is relatively
featureless compared with that of deep-sea manganese nodules. Reconsideration
of ages of manganese deposits from the Hawaiian archipelago indicates
that the rates of accretion of manganese crusts are probably in the same range
as those of deep-sea deposits and that the crusts do not accrete at a much faster
rate than deep-sea deposits as previously suggested. Iron staining is observed
in the volcanic substrates and becomes more apparent with the increasing age
of the substrate. There appears, however, to be no evidence that iron oxide is
a ubiquitous control factor in initiating manganese crustal growth. Because
of the terrain and the rocky nature of the substrate, diagenetic processes
within the sediment column probably play no major role in controlling the
composition of manganese crusts on the flanks of the island ridge
Manganiferous Soil Concretions from Hawaii
Manganiferous soil concretions have been located in pineapple
and sugar cane plantations of the Schofield Plateau, Oahu, and black manganiferous
coatings on the surface of soils have been observed on the crests of
embankments next to pineapple plantations on Oahu, Molokai, and Lanai.
The concretions and coatings are found inoxisols derived from volcanic
parent material. The moisture regime of the soils is characterized by alternate
wet and dry periods. This alternation facilitates remobilization and reprecipitation
of manganese and to a much lesser extent iron and associated trace metals
in the soils. Optimum conditions for manganiferous soil concretion development
are encountered on the Schofield Plateau, where mean annual rainfall exceeds
1000 mm/year but where there is a net evaporation loss from the soils during
the dry period (May through October). Remobilization of manganese is less
pronounced in the oxisols of Molokai and Lanai, where mean annual rainfall
is lower. Thin manganiferous coatings rather than concretions therefore form
in these islands.
The contents of Mn, Fe, Cu, and Ni of the soils on which Hawaiian concretions
form are higher than those of New Zealand soils in which manganese
soil concretions are found. This is reflected by the much redder color of the
Hawaiian concretion-bearing soils compared with their New Zealand counterparts.
Rare earths show an enrichment sequence: parent rock ---+ soil ---+ soil
concretion. A small positive Ce anomaly is noted in the soil and is more marked
in the concretions. This may be due to the increasing oxidation of Ce in the
concretions relative to the soil, although contamination of the soil by concretionary
material may also playa role. The parent rock shows no Ce anomaly.
Barium and Pb are enriched in concretions relative to the surrounding soil,
whereas D, Th, Hf, Nb, Zr, and As are present in similar or higher concentrations
in the soil relative to the concretions. Arsenic may follow Fe in the
soils. Todorokite is the predominant manganese mineral in the Hawaiian soil
concretions, not pyrolusite as previously reported. Scanning electron microscope
studies show the crystalline nature of the manganese oxide minerals
in the concretions
Minor and rare elements in manganese crusts and nodules and sediments from the Manihiki Plateau and adjacent areas: Results of HMNZS Tui cruises
Human impact on the environment in Japan and New Zealand: A comparison
Because of its proximity to Asia, Japan has been populated by humans for a much longer time period than New Zealand and has a much higher population density. The similarity in geology and tectonic setting of the two island groups has forced both peoples to confront similar environmental hazards but this was achieved in different ways. During the Edo period (1600-1868) when contact with outside countries was limited, the Japanese adapted their agricultural practices to the environment and developed an agricultural system that corresponds closely to the ideals of sustainability. Indeed, it can be argued that the farming lifestyle of the Edo period was the most advanced way of life that can be adopted without depleting stock resources. Following the Meiji restoration in 1868, the policy of rapid industrialization led to many environmental mistakes, particularly after World War II. By the end of the 1960s, Japan was the world's most polluted country. The situation has subsequently improved greatly from this low point but much remains to be done. New Zealand was initially occupied by the Maori over 1000 years ago. They did more environmental damage than was previously thought, particularly in burning off bush and destroying the bird life. However, it was the colonization of New Zealand by the Europeans after 1840 that led to the greatest environmental damage with their introduction of farming methods unsuited to the conditions. Although the need for better scientific planning of land use practices within New Zealand is recognized, sustainable management of the environment remains a distant goal. More detailed study of the agricultural methods and lifestyles adopted in Japan during the Edo period could help in defining the concept of sustainability. (C) 2000 Elsevier Science B.V
State of the art in marine geological science
GKSS has carried out the economic and technical feasibility study for long-term experiments using the Modular Abyssal Benthic Laboratory (MABEL). The study was funded by the Commission of the European Community (contract no. MAST-CT91-0074). Within this study the state of the art in marine geological science was reviewed and prepared as an appended report. It covers the international programmes which were established for deep-sea geological research as well as the instrumentation developed for these investigations and used in these programmes. The research and development results are reported in a comprehensive manner with reference to an extensive bibliography. This report shows the tremendous development in the study of all aspects of the deep-sea-floor. The increasing sophistication of instrumentation means that deep-sea marine geology will be increasingly based on long-term in-situ monitoring which will hopefully lead to a quantum leap in our understanding of processes occurring over half the earth's surface. (orig.)Available from TIB Hannover: RA 3251(95/E/32) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Distribution, Morphology, and Geochemistry of Manganese Nodules from the Valivia 13/2 Area, Equatorial North Pacific
Manganese nodules were collected during cruise 13/2 of R.V.
Valdivia in 1976 in a small area of the equatorial north Pacific characterized by
abyssal hill topography. The sediments are dominantly siliceous oozes in which
extensive dissolution ofsiliceous material has taken place. Three principal nodule
morphologies were recovered: polynucleate nodules, mononucleate nodules, and
manganese crusts. Polynucleate nodules occur throughout the entire depth range
studied whereas mononucleate nodules are found principally below 5000 m;
manganese crusts are restricted to the abyssal hill environments. Nodule density
remains on average roughly constant (> 7 kg/m2) with water depth (although
varying considerably, 0-27 kg/m2, throughout the area), but the form in which
the nodules occur changes with water depth. Nodule composition was investigated
as a function of water depth, nodule size, and nodule morphology and
shown to be related principally to nodule morphology. Mononucleate nodules
have higher contents of Mn, Ni, Cu, and Zn and lower contents of Fe and Co
than polynucleate nodules. The lithogenous fraction in the nodules is similar in
both morphologies, although it varies considerably with nodule size. Both
morphologies contain todorokite andJ-Mn02as the principal manganese oxide
phases, but todorokite is relatively more abundant in the mononucleate nodules.
The data are best interpreted in terms of the diagenetic supply of the transition
elements Mn, Ni, Cu, and Zn to the nodules resulting from the in situ dissolution
of siliceous tests in the sediment column. This process is more pronounced in the
abyssal regions than on the flanks of the abyssal hills and leads to the enrichment
of these elements in the larger mononucleate nodules embedded at the sediment
-water interface there. This enhanced supply of transition elements also leads to
the stabilization of todorokite in these nodules. Polynucleate nodules appear to
be preferentially formed under conditions of higher sedimentation rate on the
flanks of abyssal hills in an environment where abundant seeds are available.
Mononucleate nodules are formed in abyssal environments characterized by
lower sedimentation rate where enhanced rates of supply of biogenically derived
elements can take place