41 



molecular weight PAHs (e.g., Figure 3-9). Limited Black Rock Harbor sediment PAH 

 data, analyzed before disposal in 1983, ranged from .017 ppm (naphthalene) to 5.0 ppm 

 (phenanthrene) to 9.8 ppm (benzo [a] anthracene). 



MQR PAH results were compared with recently analyzed data from three other 

 capped CLIS mounds (Section 4.3). Except for the two specific samples mentioned above, 

 all PAH concentrations are within the range of samples identified in other CLIS mounds as 

 remnant capped material (from Stamford and Black Rock Harbors). These results are 

 discussed further below (Section 4.3). 



3.3.4 Volatile Organic Results 



The only detected VOCs were acetone, methylene chloride, carbon disulfide, 2- 

 butanone, and 2-hexanone (Table 3-5). Several of these detections were actually below the 

 practical quantitation limit and reported as estimated, including all detections of 2-butanone 

 and 2-hexanone. The relative detections of acetone, carbon disulfide, and methylene chloride 

 in each of the five samples are similar (volatile ratios). All of these are common laboratory 

 reagents, yet the method blank contained no detections of these compounds, suggesting that 

 laboratory contamination was not a factor. 



The possibility of field contamination for these three compounds is remote as the 

 solvents used for cleaning sampling tools were methanol and isopropanol. The remaining 

 possibility is that the detections of these compounds are indicative of actual sediment 

 concentrations. Considering the volatile nature of these organic compounds, and the 

 variation in concentration in the five adjacent surface sediments, this possibility also seems 

 unlikely. 



Sediment Core Chemistry Data Summary from the MQR Mound, August and December 1991 



