published on chitin/ toxicant interactions in wastewater, aquatic or marine environments.
Davar and Wightman (1981) presented uptake isotherms of 2,4 D, Dicamba, 2,4,5, T and
MCPA on chitosan, the deacetylated derivative, at room temperature. Wolfville (1978)
used chitin and chitosan for decolorization of paper mill effluents. Hung et al. (1977) used
shellfish-shell powders as absorbents for heavy metal ions from aqueous solutions.
In our earlier studies with the organophosphate, azinphosmethyl (Portier and Meyers,
1981), we reported on pesticide-induced microbial population changes and increases in
substrate utilization of chitin. Rapid uptake and utilization of chitin and its derivatives,
enhanced by controlled azinphosmethyl additions, was examined using a tagged chitin
polymer unit, N-acetyl D-glucosamine (glucosamine-l- 14 C). The work reported here is a
summarization of subsequent research with other toxicant classes using similar analytical
methods combining in situ and laboratory microcosm approaches. The objective of this
work is to characterize the influences of naturally-occurring substrates in toxicant biotransformation and biodegradation processes in estuarine ecosystems.
MATERIALS AND METHODS
Collection, Enumeration and Microcosm Test Protocol
Soil and sediment collections were made in the Terrebonne-Timbalier Bay and Barataria
Bay drainage basins in Louisiana. These watershed regions are comprised of distinct
vegetation zones and areas of contrasting salinity, all affected by a Gulfward movement of
water. Brackish and freshwater regions, located adjacent to intensively cultivated agricultural fields, are most directly affected by runoff.
Aluminium cylinder cores, 60 cm tall x 7.6 cm diameter, were inserted into the sediment to
the water level, capped and sealed, and stored on ice for transportation to the laboratory
for microbial analysis. All samples were processed within 12 h. Surface sediments from
the particular sites, i.e. the top 15 cm, were used to inoculate individual microcosms and
to categorize the major microbial groups present.
Several major toxicant classes were analyzed for environmental fate. Toxicants examined
included the organophosphate methyl parathion, phenol, pentachlorophenol, 2,4 dichlorophenol, 1,2 dichloroethane, and the organochlorine, Kepone (Chem Service). Radiolabelled versions of each toxicant were used when available (Pathfinder Laboratories).
Chitinoclasts were enumerated using a chitin medium containing 2.5 % precipitated chitin
(Sigma) plus mineral salts (Hsu and Lockwood, 1975). Preparation of the precipitated
chitin followed the methods of Okutani (1966) and Hood (1973). Pure chitin, ball-milled
for 72 h at 4°C, was dissolved in concentrated HCl in quantities of 10 g/150 ml. The
dissolved chitin was added to a large vol of distilled water. The milky white precipate was
washed repeatedly to remove acid, and the solution was adjusted to give a value of
10mg/ml at pH 7.2. The plates incubated at 30°C were inspected after 3 d. Colonies
exhibiting clearing zones were diagnostic of chitin utilization.
The microcosm systems used for this study have been discussed in detail elsewhere
(Portier, 1982 ; Portier, 1984; and Portier and Meyers, 1984). Water/sediment phase tests
were conducted in which toxicants were introduced into continuous flow and carbon
metabolism microcosms with sediment/ water interfaces analogous to that of the natural
environment. Replicate microcosm units were established for each toxicant with (N—6)
and without (N=6) chitin-amended sediments. An equal battery of microcosms served as
controls for both chitin-amended (N=6) and non-amended (N==6) tests, respectively. The
total number of all microcosms used for each toxicant test was N = 24. Microcosm
capacity was 2 L.
580
Davar and Wightman (1981) presented uptake isotherms of 2,4 D, Dicamba, 2,4,5, T and
MCPA on chitosan, the deacetylated derivative, at room temperature. Wolfville (1978)
used chitin and chitosan for decolorization of paper mill effluents. Hung et al. (1977) used
shellfish-shell powders as absorbents for heavy metal ions from aqueous solutions.
In our earlier studies with the organophosphate, azinphosmethyl (Portier and Meyers,
1981), we reported on pesticide-induced microbial population changes and increases in
substrate utilization of chitin. Rapid uptake and utilization of chitin and its derivatives,
enhanced by controlled azinphosmethyl additions, was examined using a tagged chitin
polymer unit, N-acetyl D-glucosamine (glucosamine-l- 14 C). The work reported here is a
summarization of subsequent research with other toxicant classes using similar analytical
methods combining in situ and laboratory microcosm approaches. The objective of this
work is to characterize the influences of naturally-occurring substrates in toxicant biotransformation and biodegradation processes in estuarine ecosystems.
MATERIALS AND METHODS
Collection, Enumeration and Microcosm Test Protocol
Soil and sediment collections were made in the Terrebonne-Timbalier Bay and Barataria
Bay drainage basins in Louisiana. These watershed regions are comprised of distinct
vegetation zones and areas of contrasting salinity, all affected by a Gulfward movement of
water. Brackish and freshwater regions, located adjacent to intensively cultivated agricultural fields, are most directly affected by runoff.
Aluminium cylinder cores, 60 cm tall x 7.6 cm diameter, were inserted into the sediment to
the water level, capped and sealed, and stored on ice for transportation to the laboratory
for microbial analysis. All samples were processed within 12 h. Surface sediments from
the particular sites, i.e. the top 15 cm, were used to inoculate individual microcosms and
to categorize the major microbial groups present.
Several major toxicant classes were analyzed for environmental fate. Toxicants examined
included the organophosphate methyl parathion, phenol, pentachlorophenol, 2,4 dichlorophenol, 1,2 dichloroethane, and the organochlorine, Kepone (Chem Service). Radiolabelled versions of each toxicant were used when available (Pathfinder Laboratories).
Chitinoclasts were enumerated using a chitin medium containing 2.5 % precipitated chitin
(Sigma) plus mineral salts (Hsu and Lockwood, 1975). Preparation of the precipitated
chitin followed the methods of Okutani (1966) and Hood (1973). Pure chitin, ball-milled
for 72 h at 4°C, was dissolved in concentrated HCl in quantities of 10 g/150 ml. The
dissolved chitin was added to a large vol of distilled water. The milky white precipate was
washed repeatedly to remove acid, and the solution was adjusted to give a value of
10mg/ml at pH 7.2. The plates incubated at 30°C were inspected after 3 d. Colonies
exhibiting clearing zones were diagnostic of chitin utilization.
The microcosm systems used for this study have been discussed in detail elsewhere
(Portier, 1982 ; Portier, 1984; and Portier and Meyers, 1984). Water/sediment phase tests
were conducted in which toxicants were introduced into continuous flow and carbon
metabolism microcosms with sediment/ water interfaces analogous to that of the natural
environment. Replicate microcosm units were established for each toxicant with (N—6)
and without (N=6) chitin-amended sediments. An equal battery of microcosms served as
controls for both chitin-amended (N=6) and non-amended (N==6) tests, respectively. The
total number of all microcosms used for each toxicant test was N = 24. Microcosm
capacity was 2 L.
580