The role of wood char in organic chemical sorption by soils: Studies in the absence and presence of natural organic matter

Wood char is an important source of environmental black carbon (BC) that affects the fate of organic contaminants in soils and sediments and plays a role in carbon cycling. Currently, there is need to better understand the interactions of hydrophobic organic chemicals (HOCs) with BC under environmental conditions that include the presence of natural organic matter (NOM). In addition, the research community has need for char standards that are representative of natural char and reproducible for laboratory use.; Following a brief Introduction and Background (Chapter 1), Chapter 2 presents a scientific approach to the production of synthetic chars that have common properties with a natural char produced by forest fire. Synthetic chars that can serve as surrogates for natural chars must be able to be repeatedly produced in order to facilitate interlaboratory research. For example, the manufacture of appropriate synthetic chars for HOC sorption studies requires that many aspects of surface chemistry and pore structure (including surface area) be reasonably similar to those of natural chars. The natural char (natchar) examined for this purpose was that of a pitch pine obtained from the New Jersey Pine Barrens; however, the developed characterization approach is more generally applicable toward understanding and producing surrogate synthetic materials for any natural wood char.; Three synthetic chars among the many investigated in Chapter 2 were chosen for further study: R650/F450, R650/F525, and R650/F1000. The R650/F525 synthetic char has measured characteristics (density, surface area, H/C ratio, surface charge) most closely resembling that of the natural char, the R650/F1000 synthetic char has a surface area similar to both the R650/F525 char and the natural char but with a significantly different H/C ratio and surface charge; and finally, the R650/F450 synthetic char has an H/C ratio and surface charge similar to both the R650/F525 and natural chars, but much lower measured surface area.; The majority of this dissertation effort (described in Chapters 3, 4, and 5) was devoted to studying sorption of chlorobenzene and 1,2-dichlorobenzene, first with well-characterized samples of untreated natchar and the three synthetic wood chars (Chapter 3) and then to the chars after prior exposure to (pre-loading with) NOM from Dismal Swamp Water (DSW) (Chapter 5). Prior to preparation of the NOM-loaded chars, independent studies of NOM sorption to the chars were conducted (Chapter 4).; Chapter 6 presents case study examples to show how BC and humic substances can impact partitioning and adsorption processes. (Abstract shortened by UMI.)...