2.0 MATERIALS AND METHODS 



Field test objectives were evaluated in the Upper Providence River, Rhode Island at 

 selected stations. Spectral data on PAHs in sediment were collected using UV-R and 

 qualitatively compared with existing bulk sediment chemistry. Prior to the field test, the 

 response characteristics of UV-R were determined in a series of laboratory bench tests in 

 which ambient sediments were mixed with known concentrations of PAHs of interest. 



2.1 Laboratory Studies 



In the development of the UV-R technology, SAIC as part of its Internal Research 

 and Development (IR&D) program, conducted a series of experiments since 1993 to 

 evaluate PAH fluorescence properties and optimized the UV-R hardware and software 

 systems for PAH detection and analysis. For this report, example laboratory data sets 

 derived from anthracene-spiked water and sediment matrices are included to provide a 

 comparison for interpretation of field results. Results of four treatments are presented: 



1) seawater only; 



2) seawater -I- 1000 ppm anthracene; and 



3) anthracene -I- seawater -I- sediment at 1000 ppm final concentration. 



2.2 Field Sampling 



Field deployment of the UV-R system was carried out from November 22-26, 

 1997, at nine stations shown in Figure 1 including one site each at Sassafras Point, Fields 

 Point Bulkhead, State Pier, and Station E Pipes, and two sites each at the Shooters Dock 

 and the Hurricane Barrier. The sites were selected based on historical measurements of 

 PAH concentration within the general study area. No traditional chemical analyses of 

 PAH concentration were made at the time of UV-R deployment. 



2.3 Camera Operation 



Deployment of the UV-R camera is similar to the deployment of the white light 

 REM GTS® camera (Rhoads and Germano 1986). The UV-R camera is lowered to the 

 bottom and the prism descends to the seafloor, slowed by hydraulic pistons, and is allowed 

 to penetrate the sediment. When the optical prism is in the mud, the camera first collects a 

 digital RGB image consisting of 640 x 480 pixels to allow for visualization of objects in 

 the sediment as well as the sediment/water interface. The 640 x 480 image is divided into 

 "bins," four pixels on each side. The 4x4 pixel binning is applied to increase signal 

 strength for fluorescence detection while still providing adequate image resolution. A 

 mercury (Hg) vapor light source sequentially emits four separate excitation wavelengths of 

 299, 314, 335, and 365 nm. The PAHs in the sediment absorb energy at these 



