Over the last century, human activity has resulted in an increasing rate of release of hydrocarbons that, in one way or another, have become parts of marine sediments. This trend is especially evident in sediments that have been deposited in the vicinity of industrialized urban centres.

In this paper, hydrocarbon distribution-patterns of coastal marine sediments near to two urban centres (Providence, Rhode Island, and Los Angeles, California) are examined in detail. At each location the spatial distribution of sedimentary hydrocarbons shows the greatest concentrations in areas of natural sediment-deposition near to the urban center. Examination of sediment cores from these areas shows that fossil hydrocarbons have increased from a minor fraction of total sedimentary hydrocarbons a century ago to being the major contributors today. Results from other industrialized areas of North America and Europe indicate that these patterns are typical.

Sediments that are remote from population centres have markedly lower concentrations of hydrocarbons than those deposited near to such centres, as might indeed be expected. Yet indications of anthropogenic contributions of hydrocarbons are detectable even in remote polar locations. In addition to hydrocarbons coming directly from fossil fuels, aromatic hydrocarbons that had been formed during incomplete combustion of other carbonaceous material, also accumulate in marine sediments. Fortunately, hydrocarbons from these two sources (fossil-fuel and other combustion) can be distinguished chemically.

The biological status of an isolated, man-made pond established in 1957 is described principally after its first 20 years of existence. The pond is located in the dry sagebrush region of south-central Washington (USA), and is colonized by Bulrushes, Cattails, and numerous Algae. Migratory waterfowl were the first vertebrate users of the pond; and with the establishment of shoreline plant communities and submerged macrophytes, the pond now provides nesting habitat for several duck species, American Coots, and Pied-billed Grebes. Use of the pond by large mammals is limited to visits by Mule Deer, Coyotes, and Raccoons. There are no Muskrats or Beavers in the pond. Turtles and Garter Snakes are not found in or around the pond but are present in the near-by Columbia and Yakima Rivers. The absence of these vertebrate animals is attributed to the isolation of the pond and the absence of connecting surface waterways between the pond and the regional watercourses. The only fish in the pond are Goldfish—presumably of artificial introduction.

Some of the more sedentary pond organisms—aquatic arthropods, crustaceans, and snails—may have reached the pond in raw Columbia River water, or been transported as eggs externally attached to waterfowl, or possibly been voided into the pond along with avian faecal material.

The pond contains low levels of industrially-derived radionuclides—especially caesium-137. Radiocaesium is mostly confined to bottom sediments, but is readily assimilated by biota and so appears in all trophic levels. Some of the societal concerns and research potentials associated with the pond are discussed with special references to food-chain and biotic transport mechanisms.