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

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