Table 2. Limits of detection and quantification for pesticides and polychlorinated 

 biphenyls (PCBs) in surface sediments. 



Compound Sediment 



MLOD a MLOQ b 



Hexachlorobenzene 



Lindane (gamma-BHC) 



Heptachlor 



Aldrin 



Heptachlor epoxide 



Alpha-chlordane 



Trans-nonachlor 



Dieldrin 



Mirex 



o^'-DDE 



r^rj'-DDE 



o,p_'-DDD 



r^rj'-DDD 



o.ry-DDT 



p_,p_'-DDT 



PCBs: 



Dichloro 



Trichloro 



Tetrachloro 



Pentachloro 



Hexachloro 



Heptachloro 



Octachloro 



Nonachloro 



a MLOD = Method Limit of Detection (ng/g dw) 

 ^MLOQ = Method Limit of Quantification (ng/g dw) 



Metals. For all elements except mercury, samples were thawed, allowed to warm to room 

 temperature, and then wet-homogenized. Sample aliquots were freeze-dried to a constant dry 

 weight and ground to a homogeneous powder. Approximately 0.2 g of dry powdered sediment 

 was digested overnight with concentrated nitric acid, in capped Teflon centrifuge tubes. 

 Samples were later placed in a 95°C water bath for 2 hours and then autoclaved. After 

 cooling, samples were diluted to 50 mL with Milli-Q™ water and stored in polyethylene 

 bottles until analysis. 



Approximately 20-g aliquots were stored frozen in polyethylene bottles for mercury 

 analysis. Wet samples were used for mercury analysis to avoid possible losses during the 

 drying process. Approximately 1-g ww of the sample was weighed into a borosilicate bottle. 

 Next, 5 mL of concentrated HNO3 and 5 mL of concentrated H2SO4 were added. The sample 

 was heated in a 95 percent water bath for 2 hours, cooled, and a saturated solution of 

 KMNO4 was added (approximately 5 mL) until a purple color persisted. The sample was 

 then heated again, cooled, capped, and refrigerated until analysis. 



14 



