61    BIOSORPTION OF 1,2,3-TRICHLOROPROPANE
AND TRICHLOROETHYLENE BY THE DIATOM
THALASSIOSIRA PSEUDONANA
Bruce W. Berdanier, City Engineer
Shelby, Ohio 44875
INTRODUCTION
This study's objective was to determine the potential for algal sorption of 1,2,3-trichloro-
propane (TCP) and trichloroethylene (TCE) by a specific type of diatom, Thalassiosira pseudo-
nana. A number of investigations'-7 into the ability of green and blue-green algae to bioaccumu-
late organic chemicals were found. Most of these studies have focused on bioaccumulation in
algae for the purpose of predicting the effects that the concentration of organic chemicals in the
food chain could have on higher trophic level organisms such as fish, birds, and mammals. Some
of the studies have shown concentrations in the algae over 1,000 times the concentration in the
water for certain types of organic compounds.
No study of the sorption of TCP on any type of alga was found in the literature. One would expect small molecules with high octanol/water coefficients to quickly and effectively sorb into
cell lipids. Because TCE and TCP are both small, uncharged molecules, they also might be able
to penetrate into algal cells and be sorbed by lipids. One would also expect the bioconcentration
factor (BCF) to demonstrate a dependency on the initial aqueous concentrations of TCE and
TCP. Also, the only work done to date on the sorption of TCE on algae1 has been on green algae,
which has provided no insight into the sorption potential of TCE or TCP on diatoms, the dominant fresh water algae in the spring.
Very little attention has been given to the evaluation of diatoms in past studies. One study8 was
found that evaluated the bioaccumulation of DDT by freshwater diatoms, and another study9
evaluated the biosorption of PCB by marine diatoms. Only one study5 was located that compared
the sorption of dieldrin by green algae and both living and killed diatoms. A major part of the
reason for lack of studies concerning fresh water diatoms can be linked to the difficulty in cultur-
ing them in a laboratory setting. A great deal of time, equipment, and laboratory space has to be
devoted to the single operation of developing a culture of diatoms of significant enough concentration to conduct an experiment. On the other hand, several types of green algal cultures are
readily available from most university collections and are easier to culture in the laboratory.
I conducted bench-scale experiments at Ohio State University to determine the bioconcentration factor for TCP and TCE on a collection of diatoms that were representative of the diatoms
occurring in an upground reservoir during different seasons of the year. The diatoms were purchased in a preserved state and were diluted to the desired cell concentration for each experiment. Although the mechanisms involved in the transport and uptake of the chemicals still remain to be determined, and further investigations need to be undertaken to quantify the
differences in the sorptive capabilities of live and killed diatoms, studies5-10 have indicated that
sorption is on the same order of magnitude for live or killed diatoms. Also, the fact that the diatoms were killed gave this study control over the actual concentration and cell count throughout
each experiment, which investigators dealing with live cultures have not had.
A second, but important, objective of this study was to develop a comparatively simple
methodology for the identification and quantification of chlorinated hydrocarbons in both raw
and finished water supplies. Chlorinated compounds have become a growing concern as an ever
increasing number of chemically contaminated sites have been identified. Chlorinated compounds have been used successfully for industrial, municipal, agricultural, and residential applications throughout our country.
50th Purdue Industrial Waste Conference Proceedings. 1995. Ann Arbor Press. Inc., Chelsea. Michigan 48118.
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