Contaminants' Organic Affinity for Protozoan-Modified Dissolved Organic Matter (DOM)
Nella Green, Environmental Science Dep't, Barnard Elizabeth Kujawinski, Research mentor, Barnard Dallas Abbott, Seminar advisor, LDEO
Protozoa: Flagellates & Ciliates
Protozoa are found in all aquatic systems This project focuses on brackish water flagellate and ciliate protozoa Protozoa were collected from the Hudson river
DOM in the Global Carbon Cycle
--DOM / DOC is one of the largest oceanic sinks of organic carbon --Protozoan feeding and egestion have been proposed to be a significant regulatory mechanism of DOM in aquatic systems --Protozoa may release as much as 20-30% of their digested prey as DOM
from Schimel, et al. 1995. CO2 and the carbon cycle. In: Climate Change 1994. Cambridge University Press: Cambridge, UK.
Feeding sequence for protozoan grazers
a,b) c) Phagocytosis Prey cell is hydrolyzed by digestive enzyme secreted into vacuole Digestion products are absorbed through membrane Incompletely digested prey, digestive enzymes and unassimilated DOM/DOC are released
d) e)
Nagata, T. in Microbial Ecology of the Oceans. Kirchman, D,L, ed. Wiley-Liss Contaminants
Hexachlorobenzene 2000
Organic Log Kow = 5.50 Dibutyl Phthalate Log Kow = 4.57
Pyrene Log Kow = 5.13
Lindane Log Kow = 3.78
Phenanthrene Log Kow = 4.57
Nitrobenzene Log Kow = 1.83
Experimental design
-High density ciliate population is incubated at room temperature in a 2 x 107 cell/ml bacterial culture -Culture is vacuum filtered through 0.2 nm filter -Filtrate is used in the common headspace glassware: DOM and contaminants in the inside beaker, brackish water in the outside beaker
Common headspace glassware
Extraction of Contaminants
Contaminants from the inside and outside beaker were vacuum-extracted with methanol and dichloromethane
Gas Chromatograph and M...