Zinc oceanic

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium. 

C19-0088. Using standard potentials, explain why the steel propeller of an ocean-going yacht has a zinc collar. 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Corrosion is also important when a plant is located near the ocean. Table 2-5 also gives the corrosion rates for steel and zinc specimens that were placed 80 and 800 feet from the shore.24 As a general rule it is best to keep all equipment at least 800 feet from the shore to minimize the effects of corrosion. Similarly, if a plant is to be located on a peninsula, it should be built on the leeward side and not the windward side. 

Several ions (e.g., manganese, iron (II), iron (III), cobalt, nickel, copper, zinc, cadmium, lead, and uranyl) react with pyrocatechol violet, and to some extent are extracted together with aluminium. The interferences from these ions and other metal ions generally present in seawater could be eliminated by extraction with diethyldithiocarbamate as masking agent. With this agent most of the metal ions except aluminium were extracted into chloroform, and other metal ions did not react in the amounts commonly found in seawater. Levels of aluminium between 6 and 6.3 pg/1 were found in Pacific Ocean and Japan Sea samples by this method. 

Zinc has only been measured accurately in open ocean by a few investigators [239,604-607]. Few data are available because of very low zinc concentrations in seawater and the ubiquitous sources of zinc contamination. The uncertainty of all zinc measurements prior to these investigations, and the paucity of reliable data since, have left little information for the environmental chemist to unravel the biogeochemical behaviour of zinc or to detect waters perturbed by anthropogenic inputs. 

Interest in zinc concentrations in the ocean stems from its dual role as a required nanonutrient and as a potential toxicant due to its widespread industrial and marine usage [519,605]. The major inputs of zinc to surface seawater include atmospheric deposition (both natural and anthropogenic in... 

A comparison was carried out on the results obtained using ICP-AES and AAS for eight elements in coastal Pacific Ocean water. The results for cadmium, lead, copper, iron, zinc, and nickel are in good agreement. For iron, the data obtained by the solvent extraction ICP method are also in good agreement with those determined directly by ICP-AES. In most of the results the relative standard deviations were 4% for all elements except cadmium and lead, which had relative standard deviations of about 20% owing to the low concentrations determined. 

Rainbow, P.S. 1989. Copper, cadmium and zinc concentrations in oceanic amphipod and euphausiid crustaceans, as a source of heavy metals to pelagic seabirds. Mar. Biol. 103 513-518. 

Bruland, K. W. (1989). Oceanic zinc speciation complexation of zinc by natural organic ligands in the central North Pacific, Limnol. Oceanogr., 34, 267-283. 

There are other metals for which compelling cases can be made to produce contamination-free oceanic reference seawater. These include other bioactive metals (e.g., zinc, cobalt, cadmium, and copper), tracers of anthropogenic contamination (e.g., lead, Box 3.1), and non-bioactive metals used as tracers of geochemical and physical processes (e.g., aluminum). 

Doe BR (1994) Zinc, copper, and lead in mid-ocean ridge basalts and the source rock control on Zn/Pb in ocean-ridge hydrothermal deposits. Geochim Cosmochim Acta 58 2215-2223 Ehrlich S, Butler I, Halicz L, Rickard D, Oldroyd A, Matthews A (submitted) Experimental study of copper isotope fractionation between aqueous Cu(II) and covellite, CuS. Chem Geol Finney LA, O Halloran TV (2003) Transition metal speciation in the cell insights from the chemistry of metal ion receptors. Science 300 931-936... 

Elements that are not biolimiting have quite different vertical concentration profiles. Thus, the shapes of vertical concentration profiles can be used to infer the most important bio-geochemical processes acting on the chemical of interest. In this chapter and the next, we will explore several sets of vertical profiles for nitrogen, phosphorus, and silicon, obtained from different parts of the world s ocean. In Chapter 11, we will investigate the vertical profiles of the micronutrients, such as iron and zinc. 

As shown in Table 11.1, hydrothermal emissions are a major source of soluble iron, manganese, and zinc and a minor source of aluminum, cobalt, copper, and lead. Other elements with significant hydrothermal inputs include lithium, rubidium, cesium, and potassium. Considerable uncertainty also surroimds these flux estimates because they are the result of extrapolations from measurements made at a small number of hydrothermal systems at single points in time. These fluxes appear to vary significantly over short time scales as tectonic activity abruptly opens and closes cracks in the oceanic crust. 

Correlation plots for the North Pacific Ocean concentration data from Figure 11.14 (a) zinc versus nitrate, phosphate, and silica, (b) cadmium versus nitrate, phosphate, and silica, (c) copper versus nitrate, phosphate, and silica, and (d) nickel versus nitrate, phosphate, and silica. 

In some locations, high-temperature fluids undergo considerable subsurfece mixing with relatively fresh seawater. This leads to precipitation of the less soluble iron and copper sulfides within the conduits. The fluids discharging into the ocean generally have temperatures less than 400°C and are milky white because of zinc sulfide precipitates. These white smokers also build chimneys, some of which are as much as 13 m high. Because of their lower temperatures, white smokers are typically encrusted with worm... 

Iodine is essential in the mammalian diet to produce the thyroid hormone thyroxine deficiency in humans causes goitre. Collectively, deficiencies of iodine, iron, zinc and vitamin A in humans are thought to be at least as widespread and debilitating as calorie deficiencies (Welch and Graham, 1999). The main source of iodine in soils is oceanic salts rather than parent rock, and so deficiency is most widespread in areas remote from the sea (Fuge, 1996). In principle deficiency is easily corrected with dairy supplements. However in practice this is not always feasible. Addition of iodate to irrigation water has successfully corrected widespread iodine deficiency in parts of China where the usual methods of supplementation had failed (Cao et al., 1994 Jiang et al 1997). However there is not much information on the behaviour of iodine in soil and water systems. 

Simulation results are shown here in terms of zinc metal vented into the ocean by hydrothermal fluid saturated with respect to zinc sulfide, the concentration of which increases exponentially with temperature (capped at 14.5 ppm at 400°C). The specific relation is similar to the one given by Large (1992), and is calibrated to end-member concentrations derived from seafloor observations (Seyfried et al. 2003). Details of the calculations are outlined in Carr et al. (2008). 

Pichat S, Douchet C, Albarede F (2003) Zinc isotope variations in deep-sea carbonates from the eastern equatorial Pacific over the last 175 ka. Earth Planet Sci Lett 210 167-178 Pineau F, Javoy M (1983) Carbon isotopes and concentrations in mid-ocean ridge basalts. Earth Planet Sci Lett 62 239-257... 

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