8 inclusive, and clays greater than or equal to 9. Prior to initiating the grain size analysis, a 

 subsample (approximately 5-20 g) was taken for total solids analysis (% dry weight) to allow 

 for determination of percent moisture. A sieve analysis was then performed in which the 

 sample was separated into size fractions greater than 62.5 /nm (<4 phi), sand and gravel, 

 and less than or equal to 62.5 /xm (>4 phi) silt and clay. The gravel-sand fraction was 

 subdivided further by mechanically dry-sieving it through a graded series of screens. The 

 wet-sieved and dry-sieved fractions less than 62.5 ^m were combined for each sample. The 

 silt-clay fraction was then subdivided using a pipet technique dependent upon the differential 

 settling rates of particles in a water column. 



2.4.2 Total Organic Carbon 



Total organic carbon was measured using EPA Method 9060. Organic carbon in the 

 samples was converted by the analyzer to carbon dioxide (COj), which was subsequently 

 measured by an infrared detector. The amount of COj is directly proportional to the 

 concentration of carbonaceous material in the sample. Inorganic forms of carbon (carbonate 

 and bicarbonate) are not included as part of the reported total organic carbon value. Total 

 organic carbon is a measurement of organic matter (both labile and refractory) in sediments. 



2.4.3 Metal and PAH Analysis 



Samples were analyzed using standard EPA procedures (Table 2-1). Cadmium and 

 lead were analyzed by graphite furnace atomic absorption techniques which allow for low 

 detection limit thresholds, whereas zinc was analyzed by inductively coupled argon plasma 

 emission spectrophotometry (ICP). Digestates can be heated in several stages allowing 

 removal of unwanted matrix components. Atomic absorption spectrophotometry 

 determinations are completed as single element analyses whereas analysis by ICP allows 

 simultaneous or rapid sequential determination of many different metals. The detection 

 threshold associated with ICP analysis is frequently higher than that of atomic absorption 

 spectrophotometry . 



Polynuclear aromatic hydrocarbons (PAHs) were analyzed by EPA Method 8270 

 which utilizes gas chromatography /mass spectrophotometry (GC/MS). The method detection 

 limit for PAHs is based on results obtained from the method blank processed with the 

 samples. The practical quantitation limit is the lowest level of measurement that can be 

 reliably achieved within specified limits of precision and accuracy during routine laboratory 

 operating conditions for a sample of a particular matrix. 



2.4.4 QA/QC 



Results submitted by the NED laboratory were found to be acceptable and supported 

 by appropriate documentation. Quality control checks from the NED laboratory consisted of 



Monitoring Cruise at the Western Long Island Sound Disposal Site, June 1991 



