some places. However, sediment toxic- 

 ity is not usually found at NS&T sites be- 

 cause they are chosen to be represen- 

 tative of more than isolated locations. 



It appears that, on a national scale, 

 biological effects are restricted to ex- 

 tremely contaminated and spatially lim- 

 ited locales. That result is, of course, a 

 welcome assessment of the status of 

 coastal contamination. However, it is 

 very important to continue to test for 

 possible effects, especially non-lethal 

 ones. 



Ongoing projects at the NMFS Environ- 

 mental Conservation Division in Seattle 

 are seeking to find contaminant re- 

 sponses in fish that are less dramatic 

 than liver tumors, but may be more often 

 found and of possible significance to the 

 longevity or reproductive potential of the 

 species. For example, while there is not 

 yet a nationwide set of data, livers of fish 

 are being biochemically examined for 

 the activity of enzymes produced to me- 

 tabolize organic contaminants. Direct 

 measurements of the reproductive suc- 

 cess of fish are being made in selected 

 locations. 



The NS&T Program serves as an ex- 

 perimental matrix in which to find bio- 

 logical responses that are being caused 

 by chemical contamination. Research 

 into effects of contaminants is not re- 

 stricted to NS&T sites. Intact, samples 

 are deliberately collected in very con- 

 taminated areas to test whether the 

 hypothesized response occurs under 

 extreme conditions. Once it is known 

 that a response occurs under these 

 conditions, it will be possible to incorpo- 

 rate the measurement into NOAA's 

 national monitoring program. 



Temporal Trends of 

 Contaminants in Sediments 



Sediment data can be used to describe 

 the spatial distribution of contamination, 

 but periodic analyses of surface sedi- 

 ments do not reveal temporal trends. 

 Organisms on the seafloor mix newly 

 arrived particles into the existing sedi- 

 ment. Whenthe NS&T Program samples 

 the upper one to two centimeters of 

 sediment, we do not know how much 

 time has been integrated into that 

 sample. It could be, for example, that 

 the upper 10 cm of sediment are all 

 mixed together and that sediment is 

 delivered slowly at that site. Quite pos- 

 sibly, a chemical concentration of the 

 surface represents a 20-year average. 

 Getting chronological data from sedi- 

 ments requires a knowledge of rates of 

 particle deposition and rates of sedi- 

 ment mixing. 



It is possible, under certain circum- 

 stances, to find sediment that can be 

 specially examined so that layers in 

 vertical sections can be associated with 

 a sequence of years. Generally, the 

 objective is to apply radiological dating 

 techniques to sediments that are not 

 overly disturbed by biological activity 

 and have sufficiently rapid rates of sedi- 

 mentation. The NS&T Program has 

 begun investigations in this field, but 

 there are data collected in other pro- 

 grams that allow an important general 

 observation about trends in contamina- 

 tion. 



Figure 3 contains data extracted from a 

 number of scientific papers. The impor- 

 tant point is that contaminant concen- 

 trations in sediments, except possibly 

 for copper, have begun to decrease 



12 



