Moderately persistent pollutants

Oil and many organic industrial effluents, including solid wastes such as organic fibres and pulps, are only slowly degraded by natural processes, often taking many months for complete decomposition. The time taken for untreated oil pollution on rocky shores to disappear depends on the exposure of the shore to wave action.

Table 10.2 Approximate timescales (maximums) for litter breakdown.

Litter item

Persistence

Glass bottle

1 million years (undisturbed)

Plastic bottles

Indefinitely

Aluminium cans and ring pulls

80-100 years

Tin cans

50 years

Leather, e.g. shoes

50 years

Nylon material

30-40 years

Plastic film container

20-30 years

Plastic bags

10-20 years

Plasticized paper

5 years

Wool garments

1-5 years

Cigarette butts

1-5 years

Orange peel and banana skins

2 years

In most cases the majority of the oil will have gone within about two years but thick tarry deposits can remain on the upper areas of sheltered shores for many years (IPIECA, 1995).

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