OCS Study 

MMS 2000-060 

Coastal Marine Institute 

Biodegradation of Aromatic Heterocycles 

from Petroleum-Produced Water and 

Pyrogenic Sources in Marine Sediments 

Final Report 

Louisiana 

. . 

Gulf of Mexico 

U.S. Department of the Interior Cooperative.Agreement wmkiw Minerals Management Service Coastal Marine Institute Gulf of Mexico OCS Region RK Louisiana State University 
OCS Study 

MMS 2000-060 

Coastal Marine Institute 

Biodegradation of Aromatic Heterocycles 

from Petroleum-Produced Water and 

Pyrogenic Sources in Marine Sediments 

Final Report 

Authors 

W. James Catallo 

August 2000 

Prepared under MMS Contract 

14-35-0001-30660-19920 

by 

Laboratory of Ecological Chemistry 

Toxicology Department 

School of Veterinary Medicine 

Louisiana State University 

Baton Rouge, Louisiana 70803 

Published by 

U.S . Department of the Interior Cooperative Agreement 

Minerals 1management Service Coastal Marine Institute 

Gulf of Mexico OCS Region Louisiana State University 

DISCLAIMER 

This report was prepared under contract between the Minerals Management Service 

(MMS) and the Louisiana State University A&M, Baton Rouge, LA 70803. This report 

has been technically reviewed by the MMS, and it has been approved for publication. 

Approval does not signify that the contents necessarily reflect the views and policies of 

the MMS, nor does mention of trade names or commercial products constitute 

endorsement or recommendation for use. It is, however, exempt from review and 

compliance with the MMS editorial standards . 

REPORT AVAILABILITY 

Extra copies of this report may be obtained from the Public Information Office (Mail Stop 

5034) at the following address: 

U.S . Department of the Interior 

Minerals Management Service 

Gulf of Mexico OCS Region 

Public Information Office (MS 5034) 

1201 Elmwood Park Boulevard 

New Orleans, LA 70123-2394 

Telephone: 504-736-2519 or 1-800-200-GULF 

CITATION 

Catallo, W. J . 2000. Biodegradation of Aromatic Heterocycles from Petroleum-Produced 

Water and Pyrogenic Sources in Marine Sediments. OCS Study MMS 2000-060 . 

U .S. Department of the Interior, Minerals Management Service, Gulf of Mexico 

OCS Region, New Orleans, LA. 28 pp . 

ACKNOWLEDGEMENTS 

Thanks are extended to Dr. Thomas Junk (ULM Chemistry Dept.), Mr. Robert Murray, 

Ms . L. Dana Civils (LSU Laboratory for Ecological Chemistry), Dr. Jorje Aravena (LSU 

Electrical Engineering), Dr. Rishi Meyhandan (LSU Physics and Astronomy), and Dr. 

Ronald D . DeLaune (LSU Wetland Biogeochemistry Inst.), and Dr. Pasquale Roscigno 

(MMS, New Orleans) for critical review, advise, experimental work, and discussion . 

iii 

EXECUTIVE SUMMARY 

This report summarizes laboratory studies and associated technical development on the 

influence of hydrology on biogeochemical processes, particularly those that govern the transport 

and transformation of pollutant organic chemicals in wetland sediments . The goals were to : 1) 

determine the effects of static vs. dynamic hydrology on biogeochemical behavior of tidal wetland 

sediment systems, with respect to central variables (e.g., redox potential dynamics) and pollutant 

transformation, 2) design and build hydrodynamic microcosms for this purpose that are 

reproducible, well controlled, and adequately monitored in the laboratory and, 3) develop 

analytical approaches for target pollutant chemicals that allow for detection of small but 

significant concentration differences between time points and treatments. This last goal was 

included because most common methods used for identification of chemicals mixtures in 

sediments are semi-quantitative (i .e ., provide for order-of-magnitude differentiation in analyte 

concentrations), and it was expected that differences in target pollutant levels between treatments 

in this work would be inside this margin and not discernible using standard approaches . The 

pollutant chemicals examined here included representative N-, O-, and S- heterocycles (NOSHs) 

that occur in coal chemicals, crude oils, and pyrogenic mixtures. The target analytes were 

quinoxaline, 2-methylquinoxaline, 2,3-dimethylquinoxaline, benzothiazole, dibenzofuran, 

phenazine, dibenzothiophene, phenothiazine, acridine, and phenanthridine . These and other 

NOSHs are found in in pollutant mixtures near certain industrial activity, hazardous waste sites, 

and major harbors . They are of interest because of their apparent stability in aquatic sediments 

except for certain (turbulent, well-oxidized) conditions under which they are labile. Further, many 

NOSH compounds are acutely toxic, with some also mutagenic and/or carcinogenic in mammals. 

They were synthesized in deuterated form using approaches developed for this and related work, 

and used as isotopic dilution standards in GC-MS analysis of sediments collected from 

experimental sediments over some 20 weeks. The sediments were exposed to three hydrologic 

conditions : static drained (oxidized redox potentials), static flooded (reduced redox potentials), 

and tidal (alternating redox potential). It was found that the physcochemical and biological 

behavior of the sediments in the microcoms was similar to that observed in natural settings, and in 

accord with prevailing theory. Redox potential time series and sediment trace gas signatures from 

the different treatments were analogous to those encountered in field settings continuously 

flooded and drained systems had reduced (mean - 428 mV) and oxidized (+ 73 mV) Eh values, 

respectively, with no evidence of daily or longer periodic variation . The tidal systems exhibited 

oscillating Eh values, with significant amplitudes (40 - 180 mV/0 .5 d) . Analysis of the signals 

using the wavelet transform confirmed the presence of strong diurnal Eh variations, with a mean 

value period of 23 .78 ± 2.10 h . Thermal and light cycles in the laboratory had little effect of the 

Eh time signature : variation of tide stage throughout the day and at different times of the year (the 

experiments were conducted in an annex not equipped with climate control) did not affect the 

tidal Eh signal period . Biogeochemical gas mixtures leaving the sediments also reflected the 

hydrological status of the treatments : the major gases observed were COZ from microbial 

respiration (drained) vs. COZ with small sulfide and methane outputs (tidal), vs. relatively large 

amounts of sulfides and methane. Transformation of the NOSH analytes was different in each of 

the hydrologic regimes, with the rate of transformation and the number of NOSHs degraded 

decreasing in the following order: drained > tidal > flooded. This can be clearly discerned in 

v 
Figures 10-12 with respect to the number of NOSHs transformed so as to afford a recovery of 

under 25 ppm at 16 weeks. Except for one sample showing a concentration spike at week 18, the 

drained system showed the elimination of quinoxaline, 2-methylquinoxaline, 2,3-

dimenthylquinoxaline, and phenanthridine by week 16, with the recovered concentrations of the 

other NOSHs also diminished well below 25 ppm (i .e, tenfold concentration reductions) . Under 

tidal conditions, quinoxaline, 2-methylquinoxaline, and phenothiazine were eliminated more 

rapidly than in any other treatment, with phenazine and phenanthridine reduced below 25 ppm by 

week 16 . By 17 .5 weeks, all NOSH analytes were transformed so that recoveries were less than 

25 ppm. Under flooded conditions, only quinoxaline and dimethyl quinoxaline were degraded to 

recovery levels below 50 ppm within 16 weeks, and these were completely eliminated by week 17. 

Other than these, only phenothiazine and 2,3-dimethylquinoxaline were transformed to below 50 

ppm recovery by week 20. The sediment concentrations of the other NOSHs remained static, 

with recovery levels remaining relatively constant between 100 and 170 ppm for acridine, 

phenanthridine, acridine, and phenazine between weeks 7 and 20. These results indicated that 

sediments and associated biota exposed to tidal pulsing (analogous to a streamside salt marsh 

ecophene) removed more NOSH compounds faster and to lower levels than a flooded sediment 

(analogous to a flooded interior ecophene or an impounded system). Although the drained 

sediments showed the fastest and most general degradation of the NOSH target analytes, this 

condition is not realistic in a "wetland" setting by definition : the sediments are not flooded, redox 

conditions are more characteristic of "uplands" and the vegetative situation would change within a 

few years because facultative wetland and upland species easily outcompete obligate wetland 

plants upon draining. Thus, of the two wetland possibilities (tidal vs . flooded), the tidal systems 

were better able to transform the NOSH compounds. From a contaminated sediment perpective, 

an optimal remediation stategy for these NOSHs would encompass dredging ofaffected areas 

followed by upland placement and tilling to maintain well-oxidized conditions. From an ecological 

perspective, promoting in sitzt remediation of NOSHs and other organic pollutants would involve 

exposing as much contaminated sediment as possible to the action of tides, while minimizing the 

area exposed to prolonged flooding. Obviously, this kind of undertaking in a real wetland would 

involve an integrated set of engineering interventions that encompass hydrologic, sedimentologic, 

and plant-system variables in a progressive sense. The author is aware of no actual cases in which 

this has been successfully attempted or contemplated: much further study is called for in 

ecological mesocosms and other controlled settings where important variables and true causal 

relationships can be identified and evaluated. 

vi 
TABLE OF CONTENTS 

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Hydrodynamic Wetland Microcosms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Hydrodynamic Wetland Mesocosms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Signal Acquisition and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Synthetic Organic Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 

NOSH Transformation Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

Citations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 

vu 

LIST OF FIGURES 

Figure 1 . NOSH Target Analytes Examined in This Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Figure 2. Schematic Diagram of the Tide Simulation Microcosm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Figure 3 . Schematic Diagram of the Gas Sampling/Analysis System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Figure 4. Schematic Diagram of the Tidal Wetland Mesocosm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

Figure 5 . Total Ion Trace of Protiated NOSH Analytes and Deuterated Isotopic Dilution 

Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

Figure 6. Time Series of Eh from Shallow and Deep Electrodes Placed in Tide Simulation 

Microcosms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

Figure 7. Headspace Gases from the Drained/Oxidized Microcosm by FTIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Figure 8. Headspace Gases from the Tidal Microcosm by FTIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

Figure 9. Headspace Gases in the Flooded/Reduced Microcosm by FTIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Figure 10 . NOSH Transformation Profiles from the Drained/Oxidized Microcosm. . . . . . . . . . . . . . . . . . . 23 

Figure 11 . NOSH Transformation Profiles for the Tidal Microcosm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 

Figure 12 . NOSH Transformation Profiles for the Flooded/Reduced Microcosm . . . . . . . . . . . . . . . . . . . . 25 

Introduction 

The work discussed here addresses the influence of hydrology on biogeochemica( 

processes that govern transport and transformation of selected pollutant chemicals in wetland 

sediment-plant systems . "Biogeochemical" refers to a group of coupled biological (e.g., 

microbial, plant) and physicochemical (e.g. flood-drain events from tides and floods) processes 

that to a large extent determine the productivity, habitat quality, and regional-global significance 

of wetland and other ecosystems (Catallo 1999; Catallo et al . 1999). Previous microcosm studies 

showed that degradation and transformation rates and pathways of aromatic hydrocarbons (AHs) 

and N-, O-, and S- heterocycles (NOSHs) differed significantly in marine sediments of different 

particle sizes and under oxidized vs. reduced conditions (Catallo 1996a, Catallo and Gambrell 

1994). In these experiments, AH and NOSH transformation was evaluated in stirred, bubbled 

controlled Eh/pH reactors containing sediment slurries maintained as "oxidized, well-drained", 

"moderately reducing anoxic", and highly reducing-methanogenic" . AH and NOSH degradation 

rates generally were: oxidized ? moderately reducing » methanogenic. The reactors employed 

for this work were first-order feedback control systems activated whose domains were predefined 

by acceptable Eh ranges for each treatment . As a result, Eh outputs were sinusoidal, and spectral 

analysis of the waveforms demonstrated that sampling interventions and other regular system 

perturbations were detected by the electrodes and preserved in the Eh vs . time record for each 

system. This suggested that the Eh might well change rapidly and reproducibly in response to 

other periodic forcing, such as diurnal tidal flushing, but this had not been examined in the 

previous literature . Further, it was clear that, among other difficulties discussed (loc . cit.), the 

terms "oxidized, well-drained" applied to wetland sediments constituted an oxymoron (by 

definition and by the fact that aggressive upland plants such as Phragmites comnrunis soon 

displace obligate wetland plants upon draining of a normally flooded or tidal system) . 

Nevertheless, this treatment type was evaluated because large quantities of wetland and aquatic 

sediments are disposed of in upland or otherwise well-drained situations, so evaluation of these 

sediments was deemed important, albeit not especially compelling from the perspective of 

"wetlands ecology" . 

Apart from the differential NOSH and AH transformation rates observed in these 

experiments, the results also suggested that the redox potential (Eh) as measured at Pt electrodes 

can be a dynamic nonlinear variable in wetland sediments that can respond quickly and 

significantly to changing conditions, and that this information can be preserved in time series of 

Eh provided adequate sampling intervals are employed. It was clear that the interaction of tides 

with sediments should be included as a treatment in further studies of biogeochemical processing 

of contaminants. In order to do this, much effort was expended in the design, monitoring, and 

evaluation of hydrodynamic sediment microcosms (20 gallon) and later, mesocosms (300 - 3000 

gallons) containing a biocenosis comprised of sediments, plants, microbes, meiofauna, and 

macrofauna (Catallo 1999). 

The central aims of the current study were : 1) determine the effects of static vs. dynamic 

hydrology on biogeochemical behavior of salt marsh sediments, particularly with respect to major 

output variables (e.g ., Eh dynamics, trace gas signatures) and pollutant disposition and 

transformation, 2) design, build, and optimize microcosms for this purpose that are reproducible, 

well controlled, and adequately monitored in laboratory systems and, 3) develop 
extraction analytical approaches for NOSH target chemicals that allow for detection of small but 

significant concentration differences between time points and treatments. This last goal was 

especially important because most common methods used for identification of chemicals in 

complex mixtures are semi-quantitative (i .e ., provide for order-of-magnitude differentiation in 

analyte concentrations), and it was expected that differences between NOSH transformation 

profiles in different treatments of this study would be below this threshold (Catallo 1996b) . 

The pollutant chemicals selected for this work included representative N-, O-, and Sheterocycles (NOSHs) that occur in coal chemicals, several crude oils, and pyrogenic 

(combustion-generated) mixtures (Figure 1 ; Turov et al . 1987) . These and other NOSHs are 

found in pollutant mixtures near certain industrial activity, hazardous waste sites, and major 

harbors. They enter coastal marine and wetland ecosystems through a) direct dumping/spillage, 

b) fluvial transport of dissolved and sediment-associated chemicals from source outfalls, 

deposition of combustion-generated airborne particles, semivolatiles (e.g., from the so-called in 

sitrt burns of spilled oils) and polar residues and, c) assorted natural processes, including marine 

oil seeps and reactions between biogenic organic matter and sub- and super-critical water at deep 

sea hydrothermal vents. They are of continuing interest because they can accumulate to 

bioavailable levels in aquatic sediments and many NOSH compounds are acutely toxic, with some 

(e.g., the quinolines, carbazoles, and benzoquinolines and their oxidized metabolic and 

environmental transformation products) being mutagens and/or carcinogens in mammals (Catallo, 

1996a, Warshawsky 1992, Catallo et al . 1994) . 

The target analytes initially envisaged for the sediment transformation work were 

quinoxaline, 2-methylquinoxaline, 2,3-dimethylquinoxaline, benzothiazole, dibenzofuran, 

phenazine, dibenzothiophene, phenothiazine, acridine, and phenanthridine (Figure 1) . 

Unfortunately, synthetic and analytical problems arose with benzothiazole and dibenzofuran that 

were not tractable within the time frame of this work. Thus, these compounds were not examined 

and no data on their transformation in the context of this work is presented here. Other data, 

however, exist on the transformation of these materials in oxidized and reduced marine sediments 

of different particle size (Catallo, 1996a) . The synthetic problems with these compounds were 

surmounted, and relevant data and references are provided herein which may be of use to future 

workers in these areas. Further, although large tidal mesocosms containing plants and 

macrofauna were developed, optimized, and examined at the end of the study presented here, 

expected continuance funding from MMS was not forthcoming, and these systems had to be 

dedicated to other work. As a result, chemical transformation results are available only from the 

tidal microcosms. A full description of these mesocosms can be found in the literature (Catallo 

1999). 

2 
C 

O O~ N C H3 a( N C H3 

N 

Quinoxaline 2-Methylquinoxaline 2,3-Dimethylquinoxaline 

asio 

Dibenzofuran Phenazine Dibenzothiophene 

as)o 

OON 

N =N 

H Acridine 

Phenothiazine Phenanthridine 

O 

N 

Benzothiazole 

Figure 1 . NOSH Target Analytes Examined in This Study 

3 

Materials and Methods 

The main areas of research and development for this study were 1) hydrodynamic 

ecological mesocosm design, maintenance, and characterization, 2) process output signal 

detection (sensors, electronics, EPROM and other low level software), acquisition (portable, 

multi-channel data acquisition), and analysis (wavelet transform and signal reconstruction) and, 3) 

synthetic organic and environmental analytical chemistry (developing ways to detect subtle 

differences in chemical transformation between treatments using available instrumentation) . 

These will be summarized below. 

Hydrodynamic Wetland Microcosms. These systems were comprised of twenty (20) gallon glass 

aquaria containing salt marsh sediment columns (Figure 2). Salt marsh sediments were collected 

from Terrebonne LA, mixed with sand and commercial seed starter (5% w/w, each) and wetted 

with sterile Instant Ocean (15 ppt) . The sediments then were added to cylinders (26 cm i .d .) made 

first of wire, and ultimately of plastic mesh (0.5 cm) to a height of 38 cm . The wire mesh was 

discontinued after trial runs because it interfered with Eh measurements . The systems were 

covered with plexiglass containing throughputs for gas sampling and electrode wire leads . A 

diurnal tide was simulated by pumping artificial seawater (15 g/L Instant Ocean) into and out of 

the aquarium once daily (i .e . one high and one low per 24 hours) using peristaltic pumps and 

controlled by battery-powered timers . The seawater resevoir was continuously aerated . At "high 

tide", the sediment columns were covered with ca. 8 cm of water. At "low tide" about 5 cm of 

water remained in the aquarium. Two Eh electrodes (below) were positioned in the top 1 cm of 

sediment (surface) and two additional electrodes were placed deep within the column, in the 

continually flooded zone near the bottom . Trace gases were analyzed by direct sampling of 

headspace gases under vacuum to a 10 meter cell connected to a Buck Scientific FTIR 

spectrometer with gold optics and 4 cm' resolution (Figure 3). Molecular sieve SA and Ascarite 

A (Aldrich) traps were used to reduce water and COZ spectral interference and increase 

sensitivity . Compounds were identified using authentic gas standards (Scott Specialty Gases) and 

published spectral libraries from NIST . Digital background subtractions were performed using 

spectra of normal laboratory air sampled immediately prior to sampling the microcoss, and 

handled identically (i .e ., reference air samples were passed through the sampling loop of the 

system and through the traps). Thus, COZ and water vapor signals in the experimental spectra 

represent excesses of these materials in the microcosm headspaces vs. the laboratory air . 

Redox potential was logged using Pt wire -SCE electrode cells and a multichannel logger 

(Catallo 1999 - below). The platinum electrodes were constructed by welding Cu wire to 0.5 cm 

lengths of 12 guage Pt wire. The junction and Cu lead were enclosed in glass tubes of varying 

lengths, and both ends were sealed using a blowtorch. Hence, a ca. 0.5 cm length of Pt was 

exposed to the sediments while junctions and leads were enclosed in sealed glass. The electrodes 

were polished with light emory paper, soaked in aqua regia and then distilled water. Each 

electrode was calibrated prior to use with a 1% quinhydrone solution . 

The fidelity and response time of potenial measurements was examined by connecting the 

Pt end of each electrode to the working lead of a EG&G PAR 173 scanning Potentiostat and 

sweeping the potential positive and negative between +1 and -IV vs. the saturated calomel 

electrode (SCE) . The potential registered by the Pt electrode was monitored using a voltmeter 

attached to the Cu lead. The purpose of the calibration and response tests was to confirm that the 

5 
---- " ' ' I ~- 4 

10 

Schematic Diagram of Tide Simulation Microcosm. 1 . Data logger, 

2 . calomel reference electrode, 3 . salt bridge, 4. platinum electrodes, 

5 . concentrated KCI solution, 6. soil column enclosures, 7 . water 

inletloutlet, 8 . automatic peristaltic pumps, 9. resevoir feed . 

Fi~aure 2_ Schematic Diagram of the lide 5imula 

6 
Switch ~ H2O Traps . r 

Controller 

T1 T2 ~ 

PUMP Sediment Colum 

. . . . . . titititititititi FT-1 R 

. . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . 

. . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . 

. . . . . . . . 

. . . . . . . . . . . . . . . . 

. . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Figure 3 . Schematic Diagram of the Gas Sampling/Analysis System 
electrodes provided accurate solution Eh readings, and that these readings were instantaneous and 

within 5 mV of one another (i .e ., there were no changes in junction potentials or other 

interference within the experimental electrodes). Electrodes failing the quinhydrone calibration or 

not accurately and rapidly registering positive and negative potenial changes generated by the 

potentiostat were rejected. 

Eh data were logged using a custom, stand-alone data acqusition-storage module 

developed and constructed in the laboratory. The data logger was designed to be field deployable 

and replace a large data acquisition system (National Instruments MIO-l G acquisition board, 

SCXI preamplifier/multiplexer, 486/66 microcomputer with LabView Software) in experimental 

situations where available space or portability were of issue. The data logger was constructed 

with the following features : a) electronic components have ultra-low standby current requirements 

(1 .3 ~A total system in standby mode, 30 ~A during acquisition sweep of l ms); b) the 

components are stable to environmental temperatures (-40 oC - +70 oC); c) total memory 32 

kbytes and data acquisition rates are programmable 1 min - 24 h . Data can be downloaded in situ 

via RS232C serial port and IBM compatible computer (including notebooks and portables). Each 

unit consists of 12.5 x 10 .5 cm board, seven input channels with single or individual reference 

capabilities (continuous monitoring of a 2 .342 V reference) . The unit was powered by battery 

(5 .5 - 12 V), but a solar panel or normal AC/step-down transformer sources also could be used . 

The manufacturing cost of the system was low (with printed circuit boards around $15) so the 

unit was considered expendible if lost/destroyed during field work . With a standard 6V battery 

and a sampling interval of 1 h, the unit could stand atone in the field for approximately 100 d. 

Samples were collected at rates between 1 Hz and 1/h, depending on the application (in general, 

the rates were 1-2/h) . 

Hydrodynamic Wetland Mesocosms. The few available sources on construction and theory of 

microcosmology (e.g., Beyers and Odum 1993), provide very little practical insight to the 

construction and behavior of hydrodynamic wetland mesocosms . The "tidal" systems one finds 

are oriented to small scales with, in one case water reservoirs moved vertically using timed 

stepper motors (Beyers and Odum 1993) . This may be practicable at small scales (e.g., 20 

(Yallons), but if one desires to evaluate true ecological volumes (e .g., > 10 times this size) 

encompassing plants and perhaps macrofauna as well as sediments, microbes and water, then an 

entirely different approach would seem to be called for. The basic design ethos used here was to 

keep moving parts to a minimum, strive for simplicity so that failure modes would be relatively 

limited, constrain costs, and use available, easily replaceable (mass-produced, modular) 

components. The mesocosm that evolved had a volume of 300 gallons, but the basic design was 

easily upscaled to 10 times that size or larger (Figure 4). Basically, each system relied on only 

one machine (a pump), and its function was controlled by a binary (on-ofd timer . The pump 

moves water out of the mesocosm into elevated storage tanks over a 12 h period simulating a 

falling tide. When the storage tanks are filled this activates a siphon which returns the water to 

the mesocosm with simple flow restriction used to control the return time (again, 12 h) . The 

other managed input was artificial sunlight, which shone for 10 hours per day followed by 14 of 

relative darkness. The lights were synchronized with normal day time because the mesocosms 

were located in a laboratory annex containing no climate control and a large wall fan open to the 

outside environment . Sediments and plants (smooth cordgrass or oyster grass, Sj)crrtifla 

allerriif7ora) were collected from Louisiana salt marshes and were replaced with our greenhouse8 
v v 

10 

1 . Light banks with timers, 2 . Plants, 3 . Sediment, 

4 . Agricultural mesh and burlap, 5 . Oyster Shell, 

6 . Pumps, 7 . Cobble Stones, S . Reservoirs, 

9 . Simulated tide range, 10. 300-3000 Gallon Enclosure . 

lclllf^P d CrhAmatir fliant-mm of +h ., T;a-,l i .i,.+l ..~a nn,.,.,...,.,. ... 

9 
reared S. alterniflora . Only this dominant plant was collected: no attempt was made to reproduce 

the vegetative diversity of the marsh by collecting the other typical salt marsh species. The plants 

were transplanted to six 300 gallon mesocosms which comprised duplicates of each hydrologic 

condition to be examined :flooded-anaerobic (oxygen deficient), with water exchanged weekly, 

drained-aerobic (well oxygenated), with water flushed into the system weekly, and 3) Jidal, 

pulsed by a simulated diurnal tide . Data indicated that the tidal sediments alternated between 

mildly anaerobic and aerobic during the course of the of the flood drain cycle. The "ocean water" 

used was a commercial material of identical elemental composition as seawater, and this was 

inoculated with authentic estuarine water at about 20% by volume. These systems have been run 

for as long as two years, and the annual grass S. alterrzif7ora was observed to go through its entire 

life cycle including producing viable seeds and maintaining some known fungal (Catallo et al . 

1996c) and insect endosymbionts . 

Signal Acquisition and Analysis. A biogeochemical system can be viewed as a signal processor, 

with inputs (e .g ., light and heat cycles, water fluctuations, inputs of organic matter and toxic 

chemicals) impinging on the system, influencing its behavior (e.g., aerobic vs. anaerobic microbial 

metabolism), and influencing the magnitude and time structure of numerous outputs (water 

chemistry; trace gas identities and evolution time series, below). The inputs 

u(t) SYSTEM y(t) 

SYSTEM 

U (0 Y (t) 

Schematic diagram of a general system showing single continuous input and 

output variable fimctions, u(t) and y(l), respectively . mentioned are impulses or excitation functions having importance to system processes and all of 

these must be krzowrz (identified) and measured accurately with appropriate sampling 

frequencies . The former is important because confounding and collinear variables can invalidate 

normal statistical approaches and corrupt causal ascriptions (Catallo et al 1999; Asher 1983) and 

the latter because processes changing faster than the sampling rate applied to them can cause 

error (aliasing) when spectral analysis techniques are applied to the time series (Brockwell and 

Davis 1991 ; Mallat 1998) . These functions, (zi(t)), can be of many kinds : e .g., linear, spike, ramp, 

threshold, sinusoidal. Signals are outputs, y(t) carrying information about system processes. 

Signals are structured in time, whereas noise is not, and increase relative to noise as the square 

root of the sampling repetitions ; (S/N) = n'12(S/N), ; where S is signal amplitude, N is noise 

amplitude, (S/N), is signal :noise ratio after one data acquisition (scan), n is the number of sample 

scans, and (S/N) is the signal noise ratio after n scans . The states of the system can be defined by 

the stable and transient domains occupied by output signals y(t). 

It frequently is assumed that biogeochemical processes change slowly (i .e .,weeks-months) 

and therefore adequate sampling of many outputs can be performed at rates on the order of I /day 

10 
to 1/month (Catallo 1999). Unfortunately, it must first be verified that there are no cyclic outputs 

from the system with frequencies greater than the sampling rate, and this is rarely done. As a 

result, the assumption that widely-spaced data points from dynamic systems can be connected by 

linear interpolation to accurately reconstruct system temporal behavior becomes a matter of faith 

rather than demonstration . Further, attempts to analyze such a time series in order to determine 

its component waves can be highly inaccurate and misleading . The upshot of this is that complex 

system variables (u(1)) and signals (y(1)) cannot be interpreted accurately if data points are 

gathered rates slower than the changes in the process . For virtually all ecological system 

processes, classical single resolution Fourier analysis of time series suffers from major analytical 

drawbacks, not the least of which being its inability to accommodate nonstationarity in the the 

data -i .e ., transients and other deviations from perfect statistical regularity in the signals . Single 

resolution analysis of nonstationary time series leads to abasing of power spectra (Brockwell and 

Davis 1991 ; Mallat 1998) in ways that are not readily interpreted or identified . It was clear from 

preliminary time series of Eh, pH, temperature , and humidity on the microcosms that 

nonstationarity was a major feature of the input and output variables of concern in this work . As 

a result, multi-resolution "wavelet" analysis was applied to the time series of signals from the 

microcosms . 

Wavelet analysis is a recent development in applied mathematics (Mallat 1998) that has 

stimulated an enormous interest in many disciplines including signal processing/reconstruction, 

vision science, medical imaging, and physiology. The wavelet transform is a technique that allows 

for the acquisition of both localized time and frequency information about a signal. It's ability to 

dilate and shift time windows with respect to a signal allows for transient features to be 

accommodated, long and short term variations to be compensated, and periodic features to be 

isolated, identified, and if needed, enhanced . In a sense, the wavelet approach has operational and 

conceptual affinities with the use of an oscilloscope to visualize waveforms in circuits : time 

sampling windows are varied by the analyst in an attempt to isolate component waveforms of 

complex signals as standing waves, with frequency data available as the inverse of the time 

window used to capture the particular wave of interest. Waveform components and their 

alterations by specific processors are obtained by thoroughly permuting the available sampling 

windows. 

The definition of the continuous time wavelet transform (CWT) entails an "analysis 

wavelet," ~Ii (t), and the family of shifted and dilated versions 

~11 aji 

= I a I -"r yi (t -h)lcr 

The transform of x (t) E L2(R) is then 

T '[x] (cz, h) _ I a I -ir f x(t) P *( t - 1))/a d! 

The analysis wavelet, yi must satisfy the admissibility condition 

C'p=f I T(iv) 12/wd1v<co 

This condition guarantees the existence of the inverse transform 

11 
x = Cyf' IIIW [x] (cz, h) ~V *(t - h)/cr dadh; (integrals evaluated ± ~c) 

One way to realize the transform is using the filter bank interpretation and defining 

hu (1) = yr (-t/a) 

It follows that 

7' [x] (cz> h) - x (r) ha (t) -f x(l) ha (h - l) dl 

So, for each scale, a, the CWT is comprised by the output of a filter with impulse- response h,, (t) . 

Since the filters are dilated according to a scale parameter, their frequency response is modified 

accordingly, and with the discretion of the analyst . Hence, the wavelet transform maps a function 

of one variable into a function of two independent variables (time, scale) . There is, as a 

consequence, significant redundancy and if desired, the time/scale parameters can be rendered 

discrete and the signal will still be preserved in the transform samples. A standard discretization 

approach employs a logarithmic step for the scale parameter and a scale-dependent discretization 

for the temporal parameter . Thus a discretized wavelet transform can be defined via 

`w(m.nl 

= I [X] (Zm, Zmjl) 

In effect, a family of wavelets of the form yr ,,n = 2-'`12 V(t / 2' -yi) is deployed. 

Even in the discretized case the representation can be optimized by requiring the wavelet 

family, l~/m,n to be an orthonormal as a set . In this case for each value of the integer m, the 

collection of vectors { y/,,; n E Z}, defines a subspace, Wm. As the dilation parameter is held 

constant, all wavelets in that subspace have the same scale. The projection of a function, x(t), on 

this subspace is interpreted as the details of the function at that particular scale. Since increasing 

the value of the integer, n2, introduces larger dilations in the basic wavelet, its time resolution 

decreases . The sum of all details for all values m >_ mo is said to give a representation of x(t) up to 

resolution mo. Mathematically, the representations exist in the subspace 

V. = (@k,. Wk 

One of the bulwarks of multiresolution analysis is that a unique analysis function ~9 (1) can be 

defined such that the collection { ~p m,  = 2-`12 Vr(t / 2' -ri) } spans the subspace, Vm, and these are 

easy to compute recursively . If, for example the representation of a signal up to a fine resolution 

level, ni , is in the form 

X" 

- 

L. 

~Cmo 

n ( '0 mu,n 

n 

one can define a digital filter, H, receiving as input the discrete signal, { c"= c"',; ti E 7} and 

producing as output the coefficients of the next lower resolution, c"'°+' . Similarly, the digital 

12 
filter, G, can be defined as receiving the same input and producing as output the details at 

resolution level mo,. 

The wavelet packet approach applies to discrete time functions, such as those obtained by 

sampling a continuous time signal. It can be considered as the discrete version of the 

multiresolution decomposition . Using suitable digital filter banks, a discrete time signal is 

decomposed into orthogonal components which also have disjoint frequency changes. Then, by 

combining various orthogonal components one can develop representations of the signal at 

various resolution levels . For cases of ecological signals, such as the Eh time series realized in the 

tidal microcosms of the current study, periodic features, transients, and long term trends can be 

determined without unknown aliasing in resulting spectra . A further advantage is that the effects 

of low resolution sampling can be examined, and the resulting effects of aliasing on the signal 

analysis evaluated. This also was applied to the Eh time series as an illustration of the perils of 

under-sampling outputs dynamic systems and then applying spectral analytical or other analytical 

techniques to those data. 

Synthetic Organic Chemistry. In order to quantify minor or subtle differences in transformation of 

target compounds between hydrological/biogeochemical treatments, it is desirable to have stable 

isotope-labeled (e .g ., deuterated) standards for each target compound of interest . These 

standards can be added to sediments before extraction, and serve as internal "monitors" of 

extraction and analytical efficiencies for the target compounds. As these deuterated standards 

have properties virtually identical to the target compounds, their loss in the various steps of 

extraction and analysis are the same as the compounds under study. With appropriate controls 

and other procedures, this allows for quantitative analyses (percent differences can be detected), 

rather than semi-quantitative data (order-of-magnitude differences are detected) provided by 

many analytical approaches (Catallo 1996b) . In addition to the quantitative nature of isotopic 

dilution vs. the order-of-magnitude or semi-quantitative nature of standard GC-MS of 

environmental extracts, the deuterated standards also allowed for data streamlining : when isotopic 

dilution standards are used in known amounts, quantitation is simply a matter of integral ratios 

between the standard (known concentration and base peak integral) and the target analyte 

(concentration unknown, base peak integral known) . Unfortunately, commercial availability of all 

NOSHs is limited or nonexistent . As a result, methods were developed in our laboratory to label 

the target compounds with deuterium either using de rrovo or post-synthetic approaches 

(reviewed in Junk and Catallo 1996), the latter typically using supercritical deuterium oxide 

(D20), or "heavy water". A basic example of this strategy is given below : 

H H D D 

H H D20 D D 00" o0 00 

D ~N ~D 

H p 

13 
Supercritical water is extremely corrosive, and commercial stainless steel reactors leaked or 

exploded (destroying furnaces and part of a wall) after a few hours . As a result, a substantial 

amount of effort in the first year of this work was devoted to designing reactors that withstand 

supercritical aqueous conditions and were large enough to permit multi-gram labeling of target 

compounds. With this accomplished, the target compounds were made in quantities sufficient for 

use in the transformation studies of NOSHs in the microcosms . Unfortunately, NOSHs including 

benzothiazole and phenothiazine were unstable even in subcritical water, and novel synthetic 

protocols had to be devised for them. 

Benzothiazole-d 1 was prepared according to a published procedure found in Chikashita et 

al . (1989) . It was found that some H-D exchange occurred when the deuterated material was 

exposed to water over several months. Further, the pure compound was clear, and storage over 

several months gave rise to a burnt red color. The pure compound then was obtained by 

distillation . Benzothiazole(4,5,6,7)-d4 was synthesized according to a synthesis developed for 

this study and detailed in Junk et al . 1997a. 

Quinoxaline-d6, 2-methylquinoxaline-d8, and 2,3-dimethylquinoxaline-d 10 also were 

prepared by syntheses developed for this work and published in Junk et al . 1997b. 

Attempts to prepare phenazine-d8 and acridine-d9 by a) base-catalyzed supercritical 

isotope exchange at 400 °C for 6 hrs following Junk and Catallo (1996, 1997), b) acid catalyzed 

isotope exchange at 220 °C for two days, and c) palladium catalyzed exchange at 250 °C for two 

days all resulted in extensive substrate decomposition . All compounds were subsequently 

prepared by base-catalyzed near-critical exchange at 300 °C for four hours . Exchange was 

carried out by heating 300 mg substrate, 15 mL D20 and 0.1 mL 40% NaOD (in D20) in a 30 

mL Hastelloy G22 autoclave . The crude products were extracted with dichloromethane, the 

solvent evaporated and deuterated quinoxaline and 2,3-dimethylquinoxaline purified with a 

microdistillation apparatus. Phenazine and acridine were crystallized from methanol . Further 

purification was achieved by chromatography (200 mesh silica gel, hexane : DCM 10 : I v/v). 

Yields ranged from 45 to 55% . 

Dibenzofuran-d8, dibenzothiophene-d8, phenothiazine-d8, phenanthridine-d9 were 

prepared using the published Supercritical Isotope Exchange (SDE) technique of Junk and Catallo 

(1996), which has been awarded a US Patent (Catallo and Junk 1998). A 30 mL Hastelloy-C22 

autoclave was charged with the 0 .3 g of the respective substrates, 15 mL deuterium oxide, and 

0.1 mL 40% deuterium deuteroxide solution . Exchange was achieved by heating to 400 °C for 6 

hrs . Compounds were collected by filtration and purified by chromatography over 200 mesh silica 

gel using hexane as mobile phase for dibenzofuran, dibenzothiophene, and phenanthridine, 

dichloromethane for phenothiazine. Yields for dibenzothiophene and phenanthridine were above 

75% and have been reported along with a range of other AHs and NOSHs (Junk and Catallo 

1996). Those of dibenzofuran and phenothiazine were 92 and 86%, respectively . No attempts 

were made to preclude the facile back-exchange of the N-H proton of phenothiazine during 

workup under ambient (open-air) conditions because this analyte would be exposed to water 

during the sample extraction. 

NOSH Transformation Studies . Three sediment columns were equilibrated under drained, 

flooded and tidal conditions for two weeks. The sediments then were collected from the surface 

third of the enclosures from each hydrologic type. Protiated (hydrogenated) NOSH compounds 

in acetone were added to the sediments with mechanical mixing (2 h) to provide uniform levels of 

14 
the individual target contaminants between 200 and 400 ppm on a weight basis. Care was taken 

to maintain the biogeochemical condition of the sediments (oxidized vs. reduced) during mixing 

by purging the system and flooding the headspace of the mixing enclosure with Ar. The 

sediments then were reintroduced to their respective microcosms in a fresh column enclosure. 

The three hydrologic regimes were initiated and "time zero" samples were collected within 8 h of 

placement using a glass corer. Subsequent samples were taken at intervals (1-4 weeks) depending 

on estimators of microbial activity and previous recovery of NOSH target analytes . After 

collection, the sediment-water samples (ca. 10 g) were weighed and amended with deuterated 

isotopic dilution standards for each NOSH target analyte at the levels near the sediment 

concentrations. The samples then were Soxhlet extracted with dichloromethane (DCM - 48 h), 

with the extract subsequently dried (Na2S04) and concentrated under N2 . The residual sediments 

in the extraction thimbles were dried and weighed. The sample extracts then were subjected to 

GC-MS in the full scan mode. NOSH target analyte concentrations in the extract were 

determined vs. the isotopic dilution standard by ratios of correpsonding peak integrals . These 

extract concentrations were corrected for concentration factor and dry weight of sediment in the 

original sample. An example of the resolution of protiated NOSH analytes and their respective 

deuterated isotopic dilution standards is given in Figure 5 . 

15 
Be zo(h)quinoline 

Benzo(h)quinoline-d 

Phenanthrene"I

., 

Phenanthrene-d 

1e7 

NN 

0 

34.0 34 .5 35 .0 35.5 

Elution Time 

Figure 5 . Total Ion Trace of Protiated NOSH Analytes and Deuterated Isotopic Dilution Standards 
Results and Discussion 

The biogeochemical behavior of the hydrodynamic microcoms was very similar to that 

observed in natural settings, and in accord with prevailing theory (Odum 1983, Catallo 1999) . 

Redox potential time series and sediment trace gas signatures from the different treatments were 

analogous to those encountered in field settings (Catallo 1999) . With respect to the redox 

potential, the continuously flooded and drained systems had reduced (mean - 428 mV) and 

oxidized (+ 73 mV) Eh values, respectively, with no evidence of daily or longer periodic variation. 

The routine (weekly) wetting/draining of the drained system, and water changing in the flooded 

system did not affect these trends : apparently the pre-equilibration of sediments prior to addition 

of the NOSH analytes afforded a degree of redox potential poising (i .e ., "buffering") that was not 

affected by the brief maintenance interventions . The tidal systems, however, exhibited oscillating 

Eh values, with significant amplitudes (40 - 180 mV; Figure 6) . Analysis of theses signals using 

the wavelet transform confirmed the presence of strong diurnal Eh variations, with a mean value 

period of 23 .78 ± 2.10 h. It has been shown that these diurnal signals were 1) reproducible in the 

tide microcosms, 2) found in the corresponding tidal mesocosms, which also contained the plant 

S. alternifZora and, 3) observable in tidal field sites vs. impounded areas not receiving tidal input 

(Catallo 1999). Thermal and light cycles in the laboratory had no discernable effect on the Eh 

time signature : variation of tide stage throughout the day and at different times of the year (the 

experiments were conducted in an annex not equipped with climate control) did not affect the 

tide-derived Eh signal period. 

As an exercise, the effect of sampling frequency on the detection and accurate isolation of 

the 24 h waveform in the Eh data was examined by simulating the time series derived from a 16 h 

sampling frequency (not uncommon in laboratory studies, and much more rapid than most field 

studies). The results were striking : sampling at 1/16 h eliminated the detection of the 24h 

waveform in the Eh time series, and subsequent wavelet analysis gave the (erroneous) result of a 

waveform close to 48 h in period. 

The Eh traces shown in Figure 6 are characteristic of the tidal systems in three main 

respects: the sinusoidal Eh oscillations continued for as long as the tides were applied, but ceased 

immediately when static conditions ensued, 2) the waveforms are asymmetric, exhibiting 

hysteresis with respect to oxidation and reduction and, 3) electrodes at the different depths were 

out of phase (as expected), with deeper electrodes showing smaller amplitudes (probably 

reflecting the effects of compaction) . These features were consistent through the experimental 

runs, and with subsequent work (Catallo 1999). The hysteresis of measured redox potentials 

(item 2, above) suggests that the Pt electrode-Ag/AgCI cell is quasi-reversible with respect to 

oxidation and reduction in sediments (i .e ., it is patently non-Nernstian) and this almost certainly 

reflects compositional as well as bulk phase chemical variables in situ . Unpacking these factors 

and adequately describing the physics involved is far beyond the scope of this communication, and 

might well be impossible given the current level of theory on heterogeneous electrochemical 

systems. In spite of this problem, the electrodes in the tidal systems remained functional 

throughout the duration of the experiments, and rarely had to be replaced . The electrodes in the 

oxidized and reduced static microcosms, however, were replaced frequently because of 

passivation with oxides and sulfides (respectively). It would seem that dynamic Eh conditions 

reduced the level of passivation on the working electrodes, and provided for conditions most 

favorable for obtaining accurate potential values vs . the more static, well-poised conditions in the 

17 
0 .30 

0 .25 

11 

0.20 40 

Q 

°' Logger lead Q disconnect on 

> 0.15 M 11 40 shallow electrode 

l 

0 0 .10 

a 

0 .05 

o -+- Deep (15 cm) 

0 .00 0 2 4 

8 16 18 E3 Shallow (5 cm) 

Time (Days) 

Figure 6 . Time Series of Eh from Shallow and Deep Electrodes Placed in the Tide Simulation Microcosms 
other treatments . "Reconditioning" of solid electrode surfaces by alternating oxidation-reduction 

cycles (i .e ., cyclic removal of surface metal oxides and sulfides by alternating redox processes) has 

not been reported elsewhere, and represents an area of interest for further research . 

Biogeochemical gas mixtures leaving the sediments also reflected the hydrological status 

of the treatments: the major gases observed were COZ from microbial respiration (drained, Figure 

7), vs . C02 with small methane signal (tidal; Figure 8), vs. large amounts of methane (flooded 

conditions; Figure 9). The gas profiles in each treatment were checked weekly, and were 

consistent throughout the experiment. The FTIR analysis of trace gases used here was adequate 

for crude monitoring purposes, but factors including spectral interferences (e.g., H2O and HZS ; 

CH4 and (CH3)ZS), low sensitivity of detection for some sulfides (e.g., HzS), and adsorption of 

volatile hydrocarbons and sulfides on the traps makes this approach untenable for high resolution 

work. This is why "sulfides + methane" is indicated on some figures : sulfides could be smelled 

during these sampling interventions (and on the traps afterwards), and the methane resonances 

around 1300 cm-1 clearly were augmented by sulfides, most likely mixtures of HZS and 

dimethylsulfide . As a result of this difficulty, intermediate resolution (2 - 6 cm-') FTIR is not 

well-suited to detailed evaluation of biogeochemical gas mixtures from sediments, but can be used 

for low resolution "spot checks" and single analyte monitoring in cases where one gas clearly 

predominates in a mixture and can be unambiguously detected . More specific approaches 

including photoacoustic FTIR and headspace GC-MS offer increased sensitivity, very high 

resolution, and accurate 3-dimensional identification of sediment gases, but these approaches 

have yet to be evaluated in the current context. 

Transformation of the NOSH analytes was different in each of the hydrologic regimes, 

with the rate of transformation and the number of NOSHs degraded decreasing in the following 

order: drained > tidal > flooded . This can be clearly discerned in Figures 10-12 with respect to 

the number of NOSHs transformed so as to afford a recovery of under 50 ppm at 16 weeks. 

Except for one sample showing a concentration spike at week 18, the drained system showed the 

most complete elimination of quinoxaline, 2-methylquinoxaline, 2,3-dimenthylquinoxaline, and 

phenanthridine by week 16, with the recovered concentrations of the other NOSHs also 

diminished to or below 25 ppm (i .e ., a tenfold concentration reduction). Under tidal conditions, 

quinoxaline, 2-methylquinoxaline, and phenothiazine were eliminated more rapidly than in any 

other treatment, with phenazine and phenanthridine reduced below 25 ppm by week 16 . By 17.5 

weeks, all NOSH analytes were transformed so that recoveries were less than 25 ppm. Under 

flooded conditions, only quinoxaline and dimethyl quinoxaline were degraded to recovery levels 

below 50 ppm within 16 weeks, and these were completely eliminated by week 17 . Other than 

these, only phenothiazine and 2,3-dimethylquinoxaline were transformed to below 50 ppm 

recovery by week 20 . The sediment concentrations of the other NOSHs remained static, with 

recovery levels remaining relatively constant between 100 and 170 ppm for acridine, 

phenanthridine, acridine, and phenazine between weeks 7 and 20. It would seem then, that except 

for quinoxaline, 2-methylquinoxaline, and perhaps phenothiazine, there was a redox effect on 

transformation rate for the NOSH compounds studied here. 

These transformation studies, while preliminary, clearly indicated that tidal flushing 

optimizes the transformation of some NOSH compounds, and that in situ or "passive" remdiation 

of coal- and petro- chemical pollution in coastal wetlands should include design features that 

1Q 
N 0 

115 

105 

17f I 

qmrn~ ~y 

°i 95 

Y . . 

W 

,E (n Water 

85 

H 

75 Carbon Dioxide 

65 

600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600 3900 

Wave Number (cm-1) 

Figure 7 . Headspace Gases from the Drained/Oxidized Microcosm by FTIR 
N 

N 

140 

120 

f 

100 

N r ~ Yr 

D 

. I . r 

Methane 

80 Methane + Carbon 

Mixed Sulfides Dioxide 

600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600 3900 

Wave Number~cm-') 

Figure 8 . Headspace Gases from the Tidal Microcosm key FTI-R 
N 

130 

110 

90 

U 

C 

70 

E 

L 

50 Methane + 

Mixed Sulfides Carbon Dioxide 

Methane 

30 

10 

600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600 3900 

Wave Number (cm-) 

Figure 9 . Headspace Gases in the flooded/Reduced Mi~erocosm by FTI~2 
350 

300 

250 

200 

c 0 

L 

150 

U 

C 

O 

U 

100 

50 

0 

0 4 8 12 16 20 

Time (weeks) 

$ Quinoxaline 

0 2-methylquinoxaline 

O 2,3-dimethylquinox 

--f- Phenazine 

"- Dibenzothiophene 

-"- Acridine 

Phenanthridine 

-I- Phenothiazine 

Figure 10 . NOSH Transformation Profiles from the Drained/Oxirli~zed Mierososm 
N 

350 

300 

250 

200 

c 0 

150 

U 

C 0 

v 100 

50 

0 

- - - 

O ~` 

X1. . . : . : : . . . . . . ..1, 

-- ----- - --- ----- .~ . ~ . 

El 

~-~- " 

O 

. . 

.Q 

0 4 8 12 16 20 

Time (weeks) 

-6- Quinoxaline 

C~ 2-methylquinoxaline 

O 2,3-dimethylquinox 

-A-- Phenazine 

Dibenzothiophene 

" - Acridine 

Phenanthridine 

Phenothiazine 

Figure 11 . NOSH Transformation Profiles for the Tidal Microcosm 
N 

400 

350 

300 

250 

c 

200 

C 

v 150 

c 0 

U 

100 

0 

50 

0 4 8 12 16 20 

Time (weeks) 

-O- Quinoxaline 

0 2-methylquinoxaline 

O 2,3-dimethylquinox 

--*. - Phenazine 

"- Dibenzothiophene 

--t- Acridine 

Phenanthridine 

-f- Phenothiazine 

Figure 12 . NOSH Transformation Profiles for the Flooded/Reduced Microcosm 
accommodate prevailing hydroperiods, including tides and seasonal events . For most settings 

where NOSH and AH contamination is a problem, the well-drained/oxidized approach is not an 

option unless complete excavation and reclamation of the system is envisaged. 

In an abstract sense, the use of hydroperiodicity for simultaneous chemical remediation 

and ecological recovery of polluted systems seems promising in light of this and subsequent work 

(Catallo 1999) . It would involve, at the very least, attempts to optimize the tidal volume of the 

wetland without compromising its integrity. Obviously, this kind of undertaking in a real wetland 

would involve an integrated set of engineering interventions that encompass hydrologic, 

sedimentologic, and plant-system variables in a progressive sense. The same is true of the use of 

marginally-contaminated dredge materials for coastal habitat restoration projects. The author is 

aware of no actual cases in which this has been successfully attempted or contemplated . Much 

further ecological study is called for in mesocosms and other controlled settings where variables 

and causal relationships can be identified and ranked with respect to holistic endpoints including, 

but not limited to, pollutant transformation . 

26 
Citations 

Asher, H. B. 1983 . Causal Modeling. SAGE University Paper 3, Sage Publishers, Newbury 

Park, CA. ISBN 0-8039-0654-4. 

Brockwell, P. J. and R. J. Davis. 1991 . Time Series : Theory and Methods. Springer Verlag, NY. 

Beyers, R. J. and H.T. Odum . 1993 . Ecological Microcosms. Springer Advanced Texts in Life 

Sciences, (D. E. Reichle, Ed.) Springer-Verlag NY, 557 pp. 

Catallo, W. J. 1999. Hourly and daily variation of sediment redox potential in tidal wetland 

sediments . USGS Biological Resources Division, Biological Science Report, 

USGSBRDBSR-O1-1999. 

Catallo, W. J., R.P. Gambrell, K. R. Reddy, J . H. Pardue, J. Blankemeyer, and B Pugesek . 

1999 . Biogeochemical Processes, In : Ecotoxicology and Risk Assessment for Wetlands, 

ISBN: 1-880611-16-3; SETAC Special Publication Series, SETAC Foundation for 

Environmental Education, Pensacola FL, pp . 27-69. 

Catallo, W. J and T. Junk. 1998. United States Patent # 5,830,763 (11/3/98). Process for 

Preparing Deuterium Tagged Compounds. 

Catallo, W. J. 1996a. Transformation of N-, O-, and S- heterocycles (NOSHs) in estuarine 

sediments: Effects of redox potential and particle size." Chemosphere: 33/12 :2543-2563 . 

Catallo, W. J. 1996b . Bioremediation : statistical and analytical needs, 1996b . In: C.E. Proffitt 

and P. F. Rosigno (eds.) . Proceedings - Gulf of Mexico and Caribbean Oil Spills in Coastal 

Ecostystems: Assessing Effects, Natural Recovery, and Progress in Remediation 

Research. OCS Study/MMS 95-0063 . U.S. Department of Interior, Mineral Management 

Service, Gulf of Mexico Region, New Orleans LA, pp . 109-129. 

Catallo, W. J., W. Henk, L. Younger, O. Mills, D. J. Thiele, and S . P. Meyers. 1996c. Trace 

metal uptake by Pichia spartinae, an endosymbiotic yeast in the salt marsh cord grass, 

Spartina alternifZora . Chemistry and Ecology, 13(2) :113-131 . 

Catallo, W. J., D. H. Hoover, and D. Vargas . 1994. Effects of quinoline on ultrastructure in 

Paramecium caudatzrm and the protective effects of dissolved calcium, Aquatic Toxicol., 

29(324):291-303 . 

Catallo, W. J. and R. P. Gambrell. 1994. Fates and Effects of N-, O-, and S- Heterocycles 

(NOSHs) from Petroleum and Pyrogenic Sources in Marine Sediments. Final Grant 

Completion Report, OCS Study/MMS 674-2010. U.S. Dept. of the Interior, Minerals 

Management Service, Gulf of Mexico OCS Regional Office, New Orleans, La . 72 pp. 

27 
Chikashita, H. , S. Komazawa, and N. J. Ishimoto. 1989 . Bull. Soc . Jpn, 1989, 62, 1215 . 

Junk T. and W. J. Catallo. 1996 . Preparative supercritical deuterium exchange in arenes and 

heterocycles . Tetrahedron Letts. 37 :3445 . 

Junk, T. and W. J. Catallo . 1997 . Organic reactions in supercritical polar fluids . Chemical Soc. 

Rev., 26:401-406 . Royal Society of Chemists (U.K .) . 

Mallat, S . 1998. A Wavelet Tour of Signal Processing . Academic Press, NY 577 pp. 

ISBN 0-12-466605-1 . 

Odum, H. T. 1983 Ecological and General Systems. University of Colorado Press, Boulder CO, 

644 pp . 

Turov, Y. P. , N. N. Gerasimova, T. A. Sagschenko, and O.A. Bieko . 1987. Group composition 

of the low molecular weight nitrogen bases of Samotlor crude oil . Petr. Chem. USSR. 

27(1) :20-25 . 

Warshawsky, D. 1992. Environmental sources, carcinogenicity, mutagenicity, metabolism, and 

DNA binding of nitrogen and sulfur heterocyclic aromatics. Environ. Carcino. Ecotox. 

Revs. C(10):1-71 . 

28 
QPPt~,'NT of ry~y The Department of the Interior Mission 

o`' p As the Nation's principal conservation agency, the Department of the Interior has responsibility for 

most of our nationally owned public lands and natural resources. This includes fostering sound use of 

our land and water resources; protecting our fish, wildlife, and biological diversity; preserving the 

_. aC6 environmental and cultural values of our national parks and historical places; and providing for the 

4ACH 9 ~9 enjoyment of life through outdoor recreation . The Department assesses our energy and mineral 

resources and works to ensure that their development is in the best interests of all our people by 

encouraging stewardship and citizen participation in their care. The Department also has a major 

responsibility for American Indian reservation communities and for people who live in island territories 

under U.S . administration . 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary 

responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf 

(OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute 

those revenues . 

Aly~ll,K,~" Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally sound 

exploration and production of our Nation's offshore natural gas, oil and other mineral resources. The 

MMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely and 

accurate collection and disbursement of revenue from mineral leasing and production due to Indian 

tribes and allottees, States and the U.S . Treasury . 

The MMS strives to fulfill its responsibilities through the general guiding principles of : (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially affected 

parties and (2) carrying out its programs with an emphasis on working to enhance the quality of life for 

all Americans by lending MMS assistance and expertise to economic development and environmental 

protection .