45 



sediment samples, a data gap was identified between Cores RR-15 and RR-26 (Figures 2-4 

 and 2-9) . Four additional cores from the Royal River were examined to clarify distinctions 

 between the upper and middle reaches of the esmary. To better characterize the sediments 

 in the boundary region between the two reaches of the river, Cores RR-6, RR-5, and RR-3 

 were selected from cores archived at the GSO and processed at the SAIC Environmental 

 Testing Center in the sunmier of 1997. In addition, comparisons were made between 

 samples preserved in methanol and formalin (Section 3.8.2). 



The procedures for washing, sieving, and examining mineralogy and picking of 

 microfossils in the 63 fxm to 500 iivn. fraction were the same as described in the methods 

 for the other core and grab samples (Section 3.7). Most of the gray, oxidized exterior of 

 the core half was removed prior to sampling. Core RR-3 samples are split into two 

 sections to compare formalin and methanol preservation solutions; the other two cores 

 were placed in formalin solution only (Section 3.8.2). Given the depth actually dredged 

 for each location, RR-6 sample was a composite of the top 1 foot of core; RR-5, of the top 

 4 feet; and RR-3, of the top 3 feet. The bottom section of RR-3 was not used because it 

 was found to be dry and cracked. The second section of RR-5 from which the top 1 foot 

 was sampled was slightly drier and more oxygenated than the other cores. 



3.8.2 Comparison of Methods of Microfossil Preservation 



The samples originally collected for microfossil analysis from the Royal River cores 

 were stored in a 70% methanol/seawater solution. Because the density of microfossils was 

 very low in some Royal River samples, a stronger fixative (buffered formalin with Rose 

 Bengal stain) was used to compare relative preservation between the two methods. For the 

 precap survey meiofauna and mineralogical analyses, the sediments of each grab sample 

 were subdivided into two pre-cleaned 1 liter bottles, with one preserved in a 70% 

 methanol/seawater solution, and one preserved in a buffered Rose 



Bengal/formalin/seawater solution. Both samples collected from grab Station 50NE were 

 processed and analyzed for specimen concentration comparisons between the methanol- 

 based versus the formalin-based preservatives. 



The preliminary results showed that the dredged material preserved in the buffered 

 Rose Bengal/formalin solution yielded a higher abundance of both foraminifera and 

 thecamoebians relative to the methanol-preserved sample. As a result, only the sediments 

 preserved in buffered Rose Bengal/formalin solution were analyzed for the remainder of 

 the samples. For the postcap survey, all 46 samples were preserved with a buffered 

 formalin solution for meiofauna preservation. 



The final comparison of the effect of the type of preservative was conducted on 

 samples collected from the additional Royal River cores (Section 3.8.1). Due to the 

 paucity of microfossils in many of the sediment samples from the upper reach of the Royal 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



