A retrospective study of the chemical analysis cost for the remediation of Lower East Fork Poplar Creek, Oak Ridge, Tennessee

A retrospective study of the remediation of Lower East Fork Poplar Creek (LEFPC) in Oak Ridge, Tennessee was completed. The study was conducted by reviewing the public Comprehensive Environmental Response, Compensation, and Liability Act record documents associated with the remediation of LEFPC and through discussions with the project staff involved or familiar with the project. The remediation took place in two phases. The first phase involved the excavation of about 5,560 yd{sup 3} of soil at the National Oceanic and Atmospheric Administration (NOAA) locations in 1996. The second phase involved the excavation of 39,200 yd{sup 3} at another NOAA location and at the Bruner location in 1997. For the entire project (remedial investigation through cleanup), a total of 7,708 samples (1 sample for each 5.8 yd{sup 3} of soil remediated) were analyzed for mercury. The project obtained special regulatory approval to use two methods for the determination of mercury in soils that are not part of the Resource Conservation and Recovery Act SW-846 methods manual. The mercury analysis cost was $678,000, which represents 9.6$38,000, which represents a 5.3% savings relative to the estimated cost of using an off-site laboratory, and savings in the amount of $890,000 (12.5$7.1 M cleanup cost), associated with expediting execution of the cleanup work by providing rapid (< 3 hours) sample result turnaround time. The manner in which the analytical services were procured for the LEFPC project suggest that the development of new chemical analysis technology must address deployment, performance, regulatory, robustness, reliability, and business appropriateness factors if the technology is to be used in environmental remediation

Speech Communication

Contains research objectives, summary of research and reports on one research project.U. S. Air Force Cambridge Research Laboratories under Contract F19628-69-C-0044National Institutes of Health (Grant 2 ROl NB-04332-08)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

Speech Communication

Contains research objectives and summary of research on three research projects and reports on three research projects.National Institutes of Health (Grant 5 RO1 NS04332-12)U. S. Navy Office of Naval Research (Contract ONR N00014-67-A-0204-0069)Joint Services Electronics Program (Contract DAAB07-74-C-0630)National Institutes of Health (Grant 2 RO1 NS04332-11

Speech Communication

Contains research objectives, summary of research and reports on three research projects.U. S. Navy - Office of Naval Research (Contract N00014-67-A-0204-0064)U. S. Navy - Office of Naval Research (Contract N00014-67-A-0204-0069)National Science Foundation (Grant GK-31353)National Institutes of Health (Grant 5 RO1 NS04332-10)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300Bell Telephone Laboratories Fellowshi

Speech Communication

Contains research objectives, summary of research and reports on three research projects.U. S. Air Force Cambridge Research Laboratories under Contract F19628-69-C-0044National Institutes of Health (Grant 5 R01 NS04332-09)M.I.T. Lincoln Laboratory Purchase Order CC-57

Speech Communication

Contains research objectives and summary of research.National Institutes of Health (Grant 2 RO1 NS04332-11)National Institutes of Health (Grant 5 RO1 NS04332-11)U. S. Navy Office of Naval Research (Contract ONR N00014-67-A-0204-0069

Sedimentary pyrite sulfur isotope compositions preserve signatures of the surface microbial mat environment in sediments underlying low-oxygen cyanobacterial mats

The sedimentary pyrite sulfur isotope (delta S-34) record is an archive of ancient microbial sulfur cycling and environmental conditions. Interpretations of pyrite delta S-34 signatures in sediments deposited in microbial mat ecosystems are based on studies of modern microbial mat porewater sulfide delta S-34 geochemistry. Pyrite delta S-34 values often capture delta S-34 signatures of porewater sulfide at the location of pyrite formation. However, microbial mats are dynamic environments in which biogeochemical cycling shifts vertically on diurnal cycles. Therefore, there is a need to study how the location of pyrite formation impacts pyrite delta S-34 patterns in these dynamic systems. Here, we present diurnal porewater sulfide delta S-34 trends and delta S-34 values of pyrite and iron monosulfides from Middle Island Sinkhole, Lake Huron. The sediment-water interface of this sinkhole hosts a low-oxygen cyanobacterial mat ecosystem, which serves as a useful location to explore preservation of sedimentary pyrite delta S-34 signatures in early Earth environments. Porewater sulfide delta S-34 values vary by up to similar to 25 parts per thousand throughout the day due to light-driven changes in surface microbial community activity that propagate downwards, affecting porewater geochemistry as deep as 7.5 cm in the sediment. Progressive consumption of the sulfate reservoir drives delta S-34 variability, instead of variations in average cell-specific sulfate reduction rates and/or sulfide oxidation at different depths in the sediment. The delta S-34 values of pyrite are similar to porewater sulfide delta S-34 values near the mat surface. We suggest that oxidative sulfur cycling and other microbial activity promote pyrite formation in and immediately adjacent to the microbial mat and that iron geochemistry limits further pyrite formation with depth in the sediment. These results imply that primary delta S-34 signatures of pyrite deposited in organic-rich, iron-poor microbial mat environments capture information about microbial sulfur cycling and environmental conditions at the mat surface and are only minimally affected by deeper sedimentary processes during early diagenesis