Rational reference levels for Pacific coast radioactive pollution studies supplied by samples from northern Baja California.

Abstract

Radioactive pollution may be expected in coastal waters as the result of increased populations and use of nuclear fuels. Studies to estimate how objectionable these may become in the future near southern California and Baja California are being made at the Scripps Institution. Between Ensenada and Santa Barbara lies a permanent coastal eddy (countercurrent) that strongly influences dispersal of pollutants, oceanic water first coming toward shore near Ensenada and then sweeping northward. Therefore to determine whether or not pollution has reached a marine plant or an animal or sediment collected near San Diego, Los Angeles, or Santa Barbara, analytical comparisons must be made with identical samples collected near Ensenada where the coast is most directly contacted with cleaner oceanic waters. However, many other factors also must be considered before early traces of a coastal radioactive pollution can be demonstrated scientifically. The ocean contains natural radioactivities in small amounts and also measurable amounts of radioactive refuse from weapons tests. Even in the open ocean, radioactive backgrounds are continually changing. Therefore, to estimate what radioactivity was present before a contamination took place, one must refer to the past history of weapons fallout and must consider what factors, physical, chemical or biological, act to redistribute this fallout in the ocean. All branches of oceanography must be enlisted.