This link has been bookmarked by 2 people . It was first bookmarked on 12 Oct 2007, by Arne Løining.
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02 Nov 09
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One hundred and sixty four plastic particles (mean length 4.1 mm) recovered from the scats of fur seals (Arctocephalus spp.) on Macquarie Island were examined. Electron micrographs of 41 of the plastic particles showed that none could be identified as plastic pellet feedstock from their shapes. Commonly, such pellets are cylindrical and spherical. Instead, all the 164 plastic particles from the seal scats were angular particles of seven colours (feedstock particles are normally opaque or white) and could be classified into two categories: i) Fragmented along crystal lines and likely to be the result of UV breakdown and ii) Worn by abrasion (where striations were clearly visible) into irregular shapes with rounded corners. White, brown, green, yellow and blue were the most common colours. In composition, they came from five polymer groups; polyethylene 93%, polypropylene 4%, poly(1-Cl-1-butenylene) polychloroprene 2%, melamine-urea (phenol) (formaldehyde) resin 0.5% and cellulose (rope fibre) 0.5%. The larger groups are buoyant with a specific gravity less than that of sea-water. These small plastic particles are formed from the breakdown of larger particles (fragments). Their origin seems to be from the breakdown of user plastics washed ashore and ground down on cobbled beaches. Certainly most particles (70%) had attained their final form by active abrasion. It is hypothesised that the plastic particles were washed out to sea and then selected by size and consumed by individuals of a pelagic fish species, Electrona subaspera, who in turn were consumed by the fur seals. Thus the particles were accumulated both by the fish and the seals in the usual process of their feeding.
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The accumulation of plastic debris in the oceans and on beaches all over the world has been observed and reported for at least three decades with frequent publication from 1970 into the late 1980s (1). Amongst this marine debris, small plastic pellets from industrial feedstock especially, but also small fragments, were observed early on (2-7). Although measures were enforced to limit the input of plastic to the sea already in 1988 (8), plastic debris continued to appear in great densities in surface waters (9), on beaches (10) and even on the ocean floor (11-13). It is now recognised that much of that plastic originated from terrestrial sites as well as from vessels and quantities are difficult to estimate (14). It is therefore not surprising to find numbers of plastic items on geographically remote islands such as the Pitcairn Islands (15), Bird Island, South Georgia (16), New Zealand’s subantarctic islands (17,18) and Macquarie and Heard Islands in the Southern Ocean (19,20) and even at some beaches on the Antarctic Peninsula (21,22).
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Neuston net sampling in sea surface waters for plastics, has been carried out in coastal areas, areas highly frequented by tankers and fishing vessels, and in areas away from such activities. Small plastic particles were found in all these areas. While Ryan (23) reported a mean density of 3 600 plastic particles km-2 on the sea surface off South Africa, Day et al. (24) found numbers up to 0.3 x 106 plastic particles km-2 in the North Pacific east of Japan. In 2001 Moore et al. (25) described a mean abundance of 0.3 x 106 and a maximum of almost 1 x 106 plastic particles km-2 in the North Pacific central gyre. As well as feedstock, it was recognised that remnants of manufactured plastic products (user plastic) found in the marine environment also result from plastic product break down. This break down probably occurs through wave action and ultraviolet light acting both at sea and with grinding from rocks and sand on beaches. This conclusion was supported by the abundance of small plastic particles, mainly fragments, being correlated with the abundance of larger plastic items in the sea (26,27, 24). Also, Moore et al. (25) found that most of the plastic fragments they sampled were thin films (described as similar to the plastic used in sandwich bags), mono-filament line, and miscellaneous fragments.
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12 Oct 07
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This biological accumulation of small plastic pieces through the near-island oceanic food-web is akin, by inadvertent consumption of anthropomorphic materials, to that of the accumulation of some pesticides through other marine mammal food-webs.
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