摘要:

A deep‐sea pump system, originally designed as an in‐situ particle sampler, was modified into an “in‐situ heavy‐metal sampler” in order to overcome the problems of shipboard contamination and low concentration in seawater analysis. The pump system was equipped with a prefilter, ion‐exchange columns, and an inductive flow meter to measure low flow rates. Preconcentration factors of up to 500 could be achieved in a pumping time of about 5 h. Metal analysis was done onboard ship by measuring the enriched solutions with stripping voltammetric methods. The pumping device was tested and optimized on four research cruises under varying conditions. Data from the Mediterranean Sea and the northeast Atlantic for up to eight heavy metals, including Mn, Fe, Co, Ni, Zn, Cu, Cd, and Pb, suggest the wide applicability of the system and the advantage of the in‐situ preconcentration process.

ISSN:1064-119X    

DOI:10.1080/10641199609388319

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Cobalt‐rich manganese deposits on Pacific seamounts have become a focal point as one of the marine mineral resources with the most potential for the twenty‐first century. Extent and distribution of the deposits have not yet been well determined. Conventional survey techniques have estimated the distribution of the deposits by the surface coverage of nodules and crusts based only on visual observations. In order to determine more clearly the distribution characteristics of the deposits, a large‐diameter gravity coring system was developed and used during survey cruises of the research vesselR/V Hakurei‐maru No.2 in 1991 and 1991 Samples and photos obtained using the system have provided significant data and information for investigation of the economic potential and processes of formation of these deposits. Analysis of the cores provided important new findings on crust thickness, buried deposits, and debris flow‐like deposition. Based on the initial experience with the large‐diameter corer, some corer design improvements are presented.

ISSN:1064-119X    

DOI:10.1080/10641199609388320

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Ferromanganese concretions within the Polish Exclusive Economic Zone (EEZ) are found mainly in the depth range 60–70 m on the thresholds between the Bomholm Basin and Slupsk Furrow and between the Gotland and Gdansk Basins. They also occur on elevations of the seafloor within the Bomholm Basin, on the southern slopes of Slupsk Furrow, and on the lower southwestern slopes of the Gotland Basin. They occur mainly as surface deposits on very thin (<0.2 m), poorly sorted lag deposits. The concretions are predominantly discoidal and are formed around a single nucleus of sandstone or erratic rock of variable size. The ferromanganese oxides display internal layering with alternate layers of almost black manganese oxides and buff iron axyhydroxides. The concretions consist mainly of todorokite and quartz, with lesser amounts of feldspar, kaolinite, and montmorillonite. They are characterized by relatively high Fe/Mn ratios (0.9–3.5) and high contents of detrital elements (Ti, Na, K, Ca, and Mg) but low contents of the transition elements (Cu, Zn, Pb, Cr, Co, and Ni). The deposits are associated with the very dynamic environment near the halocline, where internal waves erode the sediment and create conditions of sediment nondeposition favorable for the formation of the concretions. A number of factors contribute to the high abundance of ferromanganese concretions in the Baltic Sea. One is the high input of iron and manganese by the rivers draining into it This is a consequence of the widespread occurrence of bogs and swamps in the catchment area of the Baltic Sea, which results in the river waters having high humic acid contents and low pH. Another major factor is the buildup of dissolved iron and manganese in the anoxic basins of the Baltic Sea during periods of stagnation. These waters are flushed during major inflow events, when oxygenated water from the North Sea displaces the stagnant waters of the anoxic basins. Iron and manganese in these waters are then transported laterally and deposited in the surface of ferromanganese concretions on topographic highs. We believe that the iron is deposited rapidly after such events but that the manganese is deposited over a much longer time period, thus accounting for the layering in the concretions. The rate of deposition of these elements is essentially controlled by the input of oxygen in the waters of the North Sea. These periods of major inflows are grouped but significant events, for concretions occur on average about 11 times per century. We therefore estimate that the concretions have grown much more slowly than previously thought (about 0.013–0.018 mm/yr), and that a concretion 20 mm in diameter would have an age of about 500–800 years. Higher concentrations of heavy metals have been recorded in the outer layers of the concretions, and it is possible that these can serve as indicators of heavy‐metal pollution in the Baltic Sea. The concretions range from sporadic to intermediate abundance. As such, they have no economic potential.

ISSN:1064-119X    

DOI:10.1080/10641199609388321

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The United Nations Law of the Sea (LOS) Convention includes provisions given in Article 76 for establishing the outer limits of a coastal state's legal continental shelf and for denoting the seaward extent of rights over natural resources. A preliminary determination of these limits has been done for the U.S. east coast. The methodology used is a viable and cost‐effective approach that appears ideally suited to coastal states having large amounts of interpreted bathymetric and geophysical data pertaining to their continental shelves. The determinations are reproducible, use unbiased published data, and conform to the intent of the LOS Convention.

ISSN:1064-119X    

DOI:10.1080/10641199609388322

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A total of 843 samples of Pacific Ocean polymetallic nodules (PNs) from five survey areas have been studied (metals analyzed: Mn, Fe, Ni, Cu, Co, Zn, Pb). The statistical analysis included the following techniques: factor R analysis, quick cluster Q analysis into 50 preclasses, various hierarchical cluster Q analyses (HCAs) using the preclasses (application of different HCAs to an identical set of data and of an identical HCA to two different subsets of the data), comparison of the HCA. The PNs of the survey areas can be grouped into five geochemical types (I‐V). The genesis of the PNs was interpreted as early diagenetic, hydrogenetic, and mixed (early diagenetic/hydrogenetic and hydrogenetic/hydrothermal. In addition, some further conclusions regarding the applicability of various HCA techniques depending on the structure of the data set have been drawn.

ISSN:1064-119X    

DOI:10.1080/10641199609388323

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Digital color logs of cores from leg 146, holes 893A and 893B, have been taken from images captured during January 1993, within days after the cores were split and described. The images were captured and color analyses performed on the Ocean Drilling Program (ODP) color digital imaging system, which was assembled from relatively inexpensive, off‐the‐shelf components. The images were used to calculate sedimentation rates by fitting chronological data from hole 893A to void‐corrected depths determined by eliminating all voids mapped from the images as >1 cm in length measured downcore. Color measurements were made at intervals between 0.22 and 1.0 mm in length, and thenCommission Internationale de l'Eclairage(CIE) 1931 chromaticity values were computed. Results plotted within CIE chro‐maticity space lie in close proximity to the Munsell 5Y hue plane, confirming that the instrumental color analysis technique has produced results consistent with those of the human observers who described colors visually. Significant periodicities occurring at 12, 17, 31, and 90 years correlate with sunspot activity cycles, suggesting that color variations may reflect global climatic forcing functions. Linear correlation between color data sets from holes 893A and 893B suggests that as much as 1.2 m of material present at or near the top of hole 893B may not have been recovered from hole 893A, and that there is a 70‐cm depth discrepancy in the opposite direction at 51.5 m below seafloor (mbsf). The article recommends that the 1931 CIE chromaticity system be used routinely for describing colors of geological materials because it readily accommodates the mathematical manipulations required for statistical and time‐series analyses and avoids the subjectivity and other weaknesses inherent in the Munsell Color System.

ISSN:1064-119X    

DOI:10.1080/10641199609388324

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:1064-119X    

DOI:10.1080/10641199609388325

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:1064-119X    

DOI:10.1080/10641199609388318

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor