382 



study Description: 



Sediment samples for trace metal analysis are collected 

 seasonally by removing the upper 1-2 cm of sediment from each 

 of three replicate 0.1 squeire meter grab ssimples collected at 

 43 stations on or near Georges Beink. The rig site Block 312* 

 represents both long-term regional station 5 and site-specific 

 station 5-1 . Approximately 382 sediment samples are selected 

 for analysis from the 15 long-term, regional stations and the 

 29 site-specific stations. Priority will be placed on samples 

 from all of the regional stations and the 19 primary stations 

 in the site-specific array. 



Sediment seunples are analyzed for aluminum, mercury, iron, 

 chromium, zinc, lead, copper, nickel, vanadium, and barium. 

 Samples au'e prepared for analysis by the complete acid 

 digestion method. Elements are analyzed by flameless or 

 flame atomic absorption and/or plasma emission spectrophotometry. 

 At all 15 regional and 19 primary site-specific stations > 

 analyses are performed on blended, unfractionated samples. 

 At selected stations, auialyses are performed on individual 

 replicates and on discrete grain-size fractions. 



Sediment grain-size analyses are performed using the 

 appropriate sieving and rapid sediment-analyzing techniques. 

 Results are presented as percent sand, silt, and clay. 

 Seind-size material is described as weight percent of 

 full phi fractions. 



Information Use: 



The final report containing the results of the first year 

 of this study will be submitted to MMS in December 1982. 

 The information from this study was presented to the Biological 

 Task Force to evaluate the effects of OCS exploratory 

 operations on the benthic communities of the Georges Bank area. 

 The information will be used in future pre- and post-sale 

 decisions related to environmental sensitivity of benthic 

 communities to OCS discharges, platform siting, discharge 

 requirements, and the adequacy of mitigating measures. 



