2.0 METHODS 



2.1 Field Procedures 



Samples were collected aboard the US Environmental Protection Agency's (EPA) 

 vessel O.S.V. Anderson by the NED during 5-7 June 1989. LORAN-C, calibrated to a fixed 

 reference point, was used for navigational control. Water depths at the sample stations 

 ranged from approximately 60 to 90 meters. 



Three replicate grab samples were taken at twenty-six stations located within or 

 adjacent to the western half of the MBDS (Figure 1-2). Replicate grabs are collected in 

 order to average out local sediment variation. Contaminant concentrations are, in general, 

 highly dependent upon local sediment redox conditions, and dredged materials are 

 characterized by high variability (Morton and Karp 1980). Results are presented for each 

 approximate station location rather than for each replicate (Figure 2-1). 



Two reference areas (18-17 and FG-23), located south of the site (Figure 1-1), were 

 also sampled in triplicate. Two additional replicates were collected from 18-17 from the 

 same grab sample as a measure of field sampling replicability. Each station sample replicate 

 was analyzed for a suite of metals and total organic carbon (TOC) by the NED laboratory. 

 Samples from the three replicate grabs were composited at each station for analysis of a suite 

 of semivolatiles. Replicate samples from station 18-17 were analyzed individually for 

 semi volatile compounds. 



Grab samples were taken at each station using a Smith-Mclntyre grab sampler. One 

 core was taken from each grab sample using polycarbonate tubes which had been rinsed with 

 seawater by the NED laboratory prior to the cruise; stainless steel spoons were used to 

 stabilize lifting the core from the grab sampler. The grab sampler and the stainless steel 

 spoons were thoroughly rinsed with seawater between each station. The replicate samples at 

 reference station 18-17 were taken without the use of stainless steel spoons. Cores were 

 taken from the center of each grab to avoid contamination. Samples were stored at 

 approximately 4° C in plastic sample bags and then transported to the NED laboratory where 

 they were stored again at approximately 4° C until analysis. 



2.2 Laboratory Procedures 



Samples were analyzed for both metal and organic constituents (Table 2-1). Metals, 

 including chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg), 

 and lead (Pb), were analyzed using the EPA's Test Methods for Evaluating Solid Waste 

 (SW-846) procedures (Table 2-1; EPA 1986). Sediment samples were acid digested (Method 

 3050) and analyzed using direct aspiration atomic absorption (AA) except for mercury (Hg) 

 analysis (Method 7471). Mercury was analyzed using cold vapor atomic absorption 



Chemical Analyses of Sediment Sampling at the Massachusetts Bay Disposal Site, June 1989 



