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3.3.2 Sediment Chemistry and Grain Size 



The results of the sediment grain size analyses indicate that the grain size distribution 

 between the three reference areas is quite similar. In all cases, reference area sediments 

 were comprised mainly of fme-grained material (silts and clay), followed by sand, and then 

 gravel. The results of the grain size analyses are reported in Appendix C, Table 7. 



Further analysis shows that 2500W has the highest fme-grained sediment fraction of 

 the reference areas, averaging 74.6%, followed by 4500E (68.1%) and CLIS-REF (54.2 %) 

 (Appendix C, Table 7). The widest range of individual values was also found at 2500W; 

 ranging from 54% to 85.5%. The ranges between station values at 4500E and CLIS-REF 

 were lower, ranging from 53.3% to 76.9% at 4500E, and 48.7% to 61.5% at CLIS-REF. 

 The highest percentage of sand was at CLIS-REF, averaging 44.1%, followed by 4500E 

 (31.4%) and 2500W (25.0%). Gravel was only a minor constituent at the reference areas, 

 comprising only 1.7% of the sediments at CLIS-REF, and 0.5% and 0.4% at 4500E and 

 2500W, respectively. 



The results of the TOC analyses were similar in comparisons between the three 

 reference areas. Average concentrations for 4500E, 2500W, and CLIS-REF were 

 21750 ppm, 22500 ppm, and 20000 ppm, respectively (Appendix C, Table 7). 



Comprehensive sediment chemistry analysis indicated the averaged LMW PAH 

 values were 0.863 ppm, 0.643 ppm, and 0.619 ppm at 2500W, 4500E, and CLIS-REF, 

 respectively (Appendix C, Table 8). Variation of all individual analytes between stations 

 within each area was low, indicated by the low standard deviations for each compound. 

 Total LMW value variation between stations of individual areas was also low, ranging from 

 0.595 ppm to 0.641 ppm at CLIS-REF, 0.593 ppm to 0.731 ppm at 4500E, and 0.783 ppm 

 to 1.052 ppm at 2500W. 



High molecular weight PAH results were similar to the results above, in that CLIS- 

 REF contained the lowest average HMW PAH concentrations of 1.850 ppm, followed by 

 4500E with 2.327 ppm, and 2500W with 2.981 ppm (Appendix C, Table 8). Variability 

 between reference areas and intraspecific station data was low. Values at CLIS-REF ranged 

 from 1 .740 ppm to 1 .908 ppm. The range of HMW PAH values at 4500E was 2. 186 ppm 

 to 2.478 ppm. Variability at 2500W was the highest of the three reference areas with values 

 ranging from 2.414 ppm to 2.958 ppm. The average values of total PAHs (LMW plus 

 HMW) at the 4500E, 2500W, and CLIS-REF were 2.970 ppm, 3.844 ppm, and 2.470 ppm, 

 respectively (Appendix C, Table 8). 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1994 



