The chemical composition of a Greenland glacier

Chemical analyses on water from dated strata of a south Greenland permanent ice sheet revealed that there is a larger amount of sulfate in samples accumulated during the past decade than in those 60 or more years older. This increase is attributed to combustion of fossil fuel. With the exception of mercury, cadmium and possibly copper, the heavy metal distributions in the glacial waters are similar to those in atmospheric dusts. Previously reported higher mercury values in recently deposited strata were not confirmed.     

Origin of Lau Basin Rise sediment

The chemistry and mineralogy of sediments in the vicinity of the active rise in the Lau Basin can be accounted for by weathering of tholeiitic basalts exposed in the Basin, the introduction of pumice fragments derived from the Tonga Ridge, precipitation of ferromanganese minerals from sea water and pore water addition.     

Scavenging of particulate matter in coastal waters

The uptake of a suite of 19 metals from coastal seawaters upon both glass and Teflon surfaces reflected primarily the sorption of particulate matter derived from crustal rock weathering. Uptake for all elements was greater in the light than in the dark. Based upon these and earlier results, a new definition of scavenging for environmental systems is proposed.     

Molybdenum in marine deposits

The distribution and rates of accumulation of Mo in marine deposits have been determined and compared with the same parameters for U and Mn. High concentrations of Mo are associated both with oxidizing environments represented by the presence of ferro-manganese oxide-rich sediments (where Mo/U ～- 3) and with reducing environments (where Mo/U is about unity). The supply of Mo by streams is more than adequate to balance the measured removal rate in normal deep-sea deposits and no submarine volcanic ‘emanations’ need be involved. On an ocean-wide basis, 4 · 3 μg Mo/cm²/1000 yr is supplied in solution by streams. Of this, 2·0 μg Mo/cm²/1000 yr is removed in deep-sea sediments and manganese nodules. The remaining 2·3 μg Mo/cm²/1000 yr is probably removed in primarily (but not exclusively) near-shore reducing sediments. The average Mo accumulation rate in these environments is about 1000 μg Mo/cm²/1000 yr; thus only 0·23 per cent of the world ocean area need be such reducing sites.     

Marine geochemistry—2: scavenging redux

Inorganic surfaces sorb dissolved and particulate phases from seawater onto organic films from a variety of sources. Heavy metals such as Au, Pt, Mn and Cd come to the coatings primarily from particulate phases. This observation confirms a previous finding of this laboratory for the uptake of U, Pu and Po. With depth in the open ocean there are greater contributions from the dissolved phases. Microbial and photochemical processes can enrich surfaces in some metals through reduction reactions. Copper and Mn enrichments in the films are attributed to the photo-reductions of Cu(II) to Cu(I) and manganese oxides to Mn(II), respectively, while the uptake of Mo is a consequence of the reduction, mediated by organisms, of molybdate to Mo(V) or Mo(IV). Cadmium, on the other hand, appears to be bioaccumulated in the films.     

Aspects of rhodium marine chemistry

Rhodium, one of the least abundant of the Pt-group elements in the earth's crust, has the second highest concentration in seawater. This may be a consequence of strong complexing, perhaps kinetically restrained with time constants of the order of centuries to millenia. The element shows a nutrient-like distribution in waters of the Pacific Ocean. Pelagic and coastal sediments have Rh concentrations close to crustal values. There is a remarkable enrichment of Rh in ferromanganese minerals that cannot be explained by oxidative capture. Unlike the other Pt-group elements, Rh is enriched in the high temperature hydrothermal sulfide deposits as well as phosphorites.     

Some comparative marine chemistries of rhenium, gold, silver and molybdenum

Four metals, Re, Au, Ag and Mo, whose dissolved forms in seawater can potentially be reduced to insoluble states, have been measured in a variety of solids depositing under anoxic conditions: hydrothermal sulfides; coastal sediments; and phosphorites. For comparative purposes these elements have also been determined in ferromanganese minerals and pelagic sediments which have accumulated under oxidizing conditions. Rhenium appears to be a unique sentinel for identifying reducing depositional environments, where enrichments of greater than three orders of magnitude above crustal concentrations are found. Molybdenum follows Re in these sediments but Mo is enriched also in those that accumulate under oxidizing conditions. The reported Mo crustal concentrations appear low in comparison to our measured sedimentary values. Gold and Ag are concentrated in hydrothermal deposits and sulfides appear to be involved in the precipitation of these elements. Coastal sediments adjacent to a domestic outfall of Los Angeles, California contain extraordinary high accumulations of anthropogenic Au, Ag and Pt. The study seeks an understanding of the mobilities and sinks of these metals in the marine environment during the major weathering cycle. Further, anthropogenic contributions to their sedimentary concentrations are identified.     

Differential citizenship in the shadow state

State restructuring through decentralization, privatization, and related processes has prompted the growth of the non-profit sector as a `shadow state' increasingly responsible for social service delivery and community development. In this context, the question arises as to how citizenship, defined as inclusion in a polity through the distribution of rights and resources, is realized within the shadow state. If non-profit organizations are assuming functions of the state but access to the shadow state is unevenly distributed, the result may be selective disenfranchisement or differential citizenship. This paper examines the nature of differential access to citizenship within the shadow state by looking at the practices and contexts of non-profit community development corporations (CDCs) in the city of Newark, New Jersey. The shadow state is affected by structural and contextual influences including financial, policy, and political factors that produce differential organizational capacity, uneven spatial coverage, client selectivity, inadequate program support, unrecognized need, and unconsidered clients' preferences. These contextualized practices in turn result in differential access to citizenship in the shadow state. Solutions to the problem of differential citizenship require improvements in the structural and contextual conditions influencing the scope and capacity of the non-profit sector.     

ClT-3 — ein neues Gerät für die Chloridbestimmung in der Wasseranalytik

The device is used for the coulometric titration of chloride with electrolytically generated silver ions and biamperometric end-point indication via a second pair of silver electrodes. The device consists of the external measuring cell with the generator- and indicator-electrode systems and a magnetic stirrer as well as the titrator proper, which contains all electric and electronic components for the realization of the course of measurements up to the digital display of measured values. Four modes of operation can be chosen with the units mmol/1 Cl^? or mg Cl^? in 100 ml sample and sample volumes of 50 μ and 200 μl the compensation of systematic dosing errors or the taking into account of constant matrix effects being possible by means of a steplessly adjustable correction factor between 0.95 and 1.05. The measuring range is 25 … 2,000 mg/1 Cl^? with variability coefficients between 0.3 and 3% if a microlitre pipette with a PE pipette tip is used. An even lower variability of the results can be expected from an improved sample dosing Disturbances caused by ions subject to electrolytic redox processes were detected (Fe, S^2?, CrO₄^2?).