Woods Hole Oceanographic Institution

Elizabeth B Kujawinski Behn

»Using stable isotope probing to characterize differences between free-living and sediment-associated microorganisms in the subsurface.
»DOM in Lake Superior
»Deepwater Horizon hydrocarbons in the marine environment
»Microbes and marine DOM, Ann. Rev. Mar. Sci. 2011
»Greenland ice sheet outlet glacier: Insights from a new isotope-mixing model
»Groundwater DOM, GCA 2011
»Dispersants & DWH, ES&T 2011
»FT-MS variability in DOM, Org Geochem 2010
»Predatory Flavobacteria, FEMS Microb Ecol 2010
»Greenland Ice Sheet DOM, GCA 2010
»Protozoa and bacteria in aquifers, FEMS Microb Ecol, 2009
»Source markers in DOM, GCA 2009
»Automated data analysis, Anal. Chem. 2006
»Marine DOM and ESI FT-ICR MS; Marine Chem 2004
»DOM extraction by C18; Org. Geochem. 2003
»Black carbon by ESI FT-ICR MS; ES&T 2004
»ESI FT-ICR MS review; Env. Forensics 2002
»Marine protozoan surfactants; Marine Chem. 2002
»ESI MS and NOM; Org. Geochem. 2002
»ESI FT-ICR MS & humic acids; Anal. Chem. 2002
»Protozoan DOM & PCBs; ES&T 2001
»Protozoa & Fe, Th, C; Aquat. Microb. Ecol. 2001
»PCB uptake by protozoa; AEM 2000

E. B. Kujawinski, J. W. Farrington and J. W. Moffett, The importance of passive diffusion in the uptake of PCBs by phagotrophic protozoa, Applied and Environmental Microbiology 66: 1987-1993, 2000

Phagotrophic protozoan grazers represent an intersection between two methods of introduction of chlorobiphenyls (CBs) into marine organisms – diffusion through surface membranes and ingestion of contaminated prey.  This study compares the relative importance of these two processes in the overall uptake of CBs by unicellular protists. Uptake rates and steady-state concentrations were compared in laboratory cultures of grazing and non-grazing protozoans.  These experiments were conducted with a 10mm marine scuticociliate (Uronema, sp.), bacterial prey (Halomonas halodurans), and a suite of 21 CB congeners spanning a range of aqueous solubilities.  The dominant pathway of CB uptake by both grazing and non-grazing protozoa was diffusion.  Bioconcentration factors (BCFs) were equivalent in grazing and non-grazing protozoa for all congeners studied.  Rate constants for uptake into and loss from the protozoan cell and depuration from bacteria were independently determined using 14C-3,3’,4,4’-tetrachlorobiphenyl (congener #77).  The bacterial depuration rate constant was -0.04 + 0.01 min-1.  The protozoan first-order uptake rate constant and second-order loss rate constant were 0.38 + 0.03 min-1 and (1.1 + 0.1) X10-5 (g org C)-1 min-1, respectively.  Magnitudes of the uptake and loss processes were calculated and compared with a numerical model.  The model result was consistent with the data from the bioaccumulation experiment and corroborated the hypothesis that diffusive uptake is faster than ingestive uptake in phagotrophic unicellular protozoa.


A reprint is available here.

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