No description available.

Thesis (Ph. D.)--Washington State University. / Includes bibliographical references.

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. / Committee Co-Chair: Joseph B. Hughes; Committee Co-Chair: Kurt D. Pennell; Committee Member: Danny D. Reible; Committee Member: Frank E. Loeffler; Committee Member: Jim C. Spain; Committee Member: Martial Taillefert; Committee Member: Terry W. Sturm.

Thesis (M.S. in chemical engineering)--Washington State University, August 2006. / Includes bibliographical references (p. 69-74).

Thesis (M. Sc.)--University of Hong Kong, 2005.

Sediments serve as the ultimate sink for many hydrophobic organic compounds and thus present a residual environmental risk many years after sources of contamination are eliminated. Monitored natural attenuation and ex situ treatment processes are often ineffective for treatment; as such in situ remediation technologies (i.e., capping) are under review. A conventional in situ remediation technology for refractory sediment contaminants is placement of a clean layer of material as a cap. A series of design models was developed to predict the performance of caps composed of the traditional material, sand. A passive sampling method using polydimethylsiloxane (PDMS) fibers for evaluating the performance of caps was developed and tested in the laboratory. The results of the laboratory analysis showed the ability to measure pore water concentration profiles in caps, the consistency of profiles with design model predictions, and correlation of PDMS-derived concentrations with contaminant uptake in test organisms. Potentially more effective caps composed of permeable adsorptive materials (to retard contaminant migration) and impermeable materials (to divert groundwater flow) were placed along with a conventional sand cap in the Anacostia River in Washington DC in 2004. Field tests of this site showed the ability to measure in situ pore water concentration profiles in caps using a field-deployable version of the PDMS passive sampling device and demonstrated the necessity of pore water-based approaches for analyzing caps. A model for assessing the uptake rates of HOCs within PDMS fibers was developed and shown to predict the kinetics of HOC sorption into fibers. The model is based on external-mass transport processes, which through a series of analyses were shown to be more significant than internal diffusion in PDMS fibers. Using the PDMS approach, field bioaccumulation tests at the Anacostia site as well as at San Diego Bay and Hunters Point Naval Shipyard showed stronger correlation of PDMS-based pore water concentrations than solid-phase concentrations with observations of bioaccumulation in the field. The overall conclusions suggest that pore water concentrations can often be a better indicator of risk than bulk solid concentrations. / text

Contaminated surficial sediments represent a potential point of entry into the food web for environmental pollutants that are toxic to fish, wildlife, and humans. One approach for managing polluted sediments is in situ capping, the placement of clean fill material, such as sand, atop the polluted sediments. A cap stabilizes the underlying sediment and physically separates pollutants from benthic organisms that inhabit the sediment/water interface. Additionally, a sediment cap can be amended with sorbents to sequester hydrophobic organic chemicals. While the physical processes affecting contaminant transport in sediment caps are readily modeled, fate and transport processes mediated by sediment bacteria are location-specific and thus highly uncertain. Laboratory bench-scale tests were employed to aid in the design of a sediment cap in Onondaga Lake. Recognizing the importance of bacterial activity beneath the benthic zone for affecting the risks of contaminant exposure, anaerobic processes were emphasized. A combination of batch and column tests were used to determine whether (1) bacteria in sediments were capable of biotransforming methylated and chlorinated benzenes, (2) the ability to biotransform the contaminants of interest would be translated from the sediments to a sand cap, (3) the rate of biogenic gas production in sediments would threaten the integrity of a sand cap, and (4) the contribution of gas-phase contaminant transport to the overall transport of contaminants from the sediments was significant. The apparent anaerobic biotransformation of toluene in a sand cap was supported by detection of a genetic biomarker for anaerobic toluene degradation, the development of substantial biomass in the sand column, apparent anaerobic biotransformation of toluene in sediment slurries, and the concomitant reduction of iron in the sand column. The dissimilarity in bacterial community composition between sediment and sand cap samples suggests that contaminant biotransformation capability cannot be predicted from community analysis. For sediments that failed to demonstrate biotransformation potential, amending a sand column with organophilic clay proved effective at retarding transport of the contaminants of interest. This work advances methods for characterizing bacterial processes in sediments and demonstrates the potential for anaerobic biotransformation of organic contaminants in sand caps. / text

Thesis (M.S.)--Youngstown State University, 2008. / Includes bibliographical references (leaves 36-40). Also available via the World Wide Web in PDF format.

Thesis (M.S. in engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Feb. 4, 2010). "College of Engineering and Architecture." Includes bibliographical references (p. 50-55).

Sediment Quality Guidelines (SQGs) serve as scientific benchmarks, or reference points of chemical contaminants levels for evaluating the possibility of occurrence of adverse biological responses in the aquatic environment. SQGs are important because the quality of sediment has significant influences on the health of aquatic organisms, and the use of SQGs is a critical means to protect and manage various aquatic ecosystems. In this study, nine conventional derivation methods are described and contrasted. Their uses and limitations, which in general reduce the ecological relevance of SQGs in applications, are discussed. Improvements can be made through implementing elements like site-specific, field-based, chemical mixtures assessments, etc. in the SQG derivation process. The Hong Kong sediment management system, which focuses on classification of dredged sediment for their disposal options, is reviewed. I suggest that the current system shall be subject to major review. First, SQG values (i.e., LCEL and UCEL) shall be reviewed with the establishment of a new database. Second, a new set of guidelines shall be derived site-specifically for the disposal area. Third, the chemical priority list shall be expanded to include other contaminants of environmental concerns. Forth, a tier of evaluating bioavailability of the target contaminant can be incorporated in the classification framework in order to assess the portion of chemicals that causes toxicity in the sediment. Finally, the biological test can be improved by using ecologically relevant local species. The need of the site-specificity in SQG derivation is justified in this study, by deriving two sets of SQGs (i.e., ERL, ERM, TEL, PEL and AET) using data from two geologically distinct areas in Hong Kong, which are the Hong Kong-Zhuhai-Macao Bridge (HZMB) area and the Kai Tak development area. The derived SQGs of arsenic, chromium, nickel and zinc are higher in the HZMB areas, but those of copper, mercury, lead and silver are higher in the Kai Tak area. In addition, the incidence rates of effect data with the same contaminants concentrations are different between the HZMB and Kai Tak area. The discrepancies among the derived SQGs and the incidence rates indicate that site-specific SQGs are essential. Furthermore, the analysis of incidence rates of effect data with different contaminants concentrations shows that the HKSQG (i.e., LCEL and UCEL) has to be reviewed, especially for arsenic, because high toxicity is not resulted at a high arsenic concentration range in the dataset. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management