Grasse River Research Articles

Chronology of transpression, magmatism, and sedimentation in the Thompson Nickel Belt (Manitoba, Canada) and timing of Trans-Hudson Orogen – Superior Province collisionThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

The Thompson Nickel Belt marks the boundary between the Archean Superior Province and the Trans-Hudson Orogen in Canada. It comprises Archean gneisses, and Paleoproterozoic rocks with metasediments and metavolcanites (Ospwagan Group) and intrusions. The gneisses are frequently migmatitic and host numerous pegmatites. The western belt boundary is a fault contact with the Kisseynew Domain of the Reindeer Zone. In the south, the transition zone between the belt and the Kisseynew Domain comprises granitoids and a detrital sequence (Grass River Group), part of which grades into turbidites in the Kisseynew Domain. The eastern belt boundary is a diffuse zone where the Archean east–west (E–W) structural trend changes into the north-northeast (NNE) trend of the belt. This paper presents U–Pb ages for granitoids and 207Pb/206Pb detrital zircon ages from the Ospwagan and Grass River groups. Ages and a comparison of events in the belt and in the eastern Reindeer Zone have major implications. The change from stable platform deposits to syn-tectonic filling and emplacement of mafic intrusions in the Ospwagan Group are attributed to the convergence between the Reindeer Zone and the Superior Province at 1891–1885 Ma. At ca. 1850 Ma, continuing convergence led to drowning of marginal basins of the Superior craton and to the development of a transpressive regime in the belt, the onset of which could be as old as ca. 1885 Ma. Metamorphic ages of 1818–1785 record closure of the Kisseynew basin and crustal thickening. Collision of the new continental block with the Superior Province was accommodated by transpression until 1750–1720 Ma.

Age, growth, mortality, and abundance of lake sturgeon in the Grasse River, New York, USA

Summary An increased understanding of lake sturgeon (Acipenser fulvescens) population dynamics is a key requirement for successful management efforts. Little is known regarding the Grasse River population of lake sturgeon except that it is one of a few populations in New York State where spawning has been documented. Thus our purpose was to assess the current status of lake sturgeon in the Grasse River system, including age, growth, mortality, and abundance. Age was determined for 196 of 211 lake sturgeon by examination of sectioned pectoral fin rays. Ages ranged from 0 to 32 years and the annual mortality rate for fish between ages 7 and 14 was 16.8%. The weight (W, g) to total length (TL, mm) relationship was W = 1.281 × 10−6TL3.202. The von Bertalanffy growth equation was TL = 1913(1−e−0.0294(t+9.5691)). While the range of observed ages was similar to that of nearby St. Lawrence River populations, mean weight at age for an individual at 1000 mm TL was lower than that observed for lake sturgeon within Lake St. Francis of the St. Lawrence River. Predicted growth based on von Bertalanffy parameters was similar to that observed for the nearby Lake St. Francis. An open population estimator using the POPAN sub-module in the Program MARK produced an abundance estimate of 793 lake sturgeon (95% CI = 337–1249).

Comparison of field and laboratory exposures of Lumbriculus variegatus to polychlorinated biphenyl‐impacted river sediments

A method is described for conducting 14-d in situ sediment bioaccumulation tests with the freshwater oligochaete Lumbriculus variegatus, at the bottom of a slow-flowing river. The in situ test exposure chambers were constructed from cylindrical plastic tubes with flow-through mesh screens and were attached to a wire basket that was weighted to the river bottom at seven sites in the lower Grasse River in New York State, USA. This design was successful in exposing L. variegatus to native sediment and overlying water under field conditions, with adequate organism mass recovery (87 ± 19%). Results compared well with ex situ laboratory bioaccumulation conducted in parallel, expressed in terms of tissue concentration, biota-sediment accumulation factors (BSAFs), and bioaccumulation factors (BAFs). Bioaccumulation of polychlorinated biphenyls (PCBs) in L. variegatus (µg PCB/g wet wt) in laboratory and field tests was found to be within a factor of 2. The small variation between in situ and ex situ may have been caused by differences in water exchange rate under the two exposure scenarios, or other factors affecting organism behavior. Values of BSAF showed a hyperbolic trend with K(OW) , peaking at BSAF of 7 for congeners with log K(OW) of 6. Bioaccumulation factors also peaked at a value of 10(6.5) for congeners with log K(OW) value of 6 but remained steady around that value for the higher K(OW) congeners. These observations may reflect under-equilibration or reduced bioavailability of more hydrophobic PCBs in worm tissues or other analytical artifacts.

Water Quality Trends at Inflows to Everglades National Park, 1977–2005

Restoration of the Florida Everglades is important for the health of the natural system, including both the "River of Grass" and its downstream estuaries. Water quality improvement is one indicator of successful restoration in this complex ecosystem. Using the period of record of 1977 through 2005, we evaluated data from seven inflow sites to the Everglades National Park (ENP) for temporal trends of various forms of phosphorus (P) and nitrogen (N) and analyzed them using principal component analysis and factor analysis without flow adjustments. Locally estimated scatter plot smoothing (LOESS) trend lines identified two inflection points (three time periods) of changing trend in total P (TP) concentration at the seven sites. Results indicated that overall water quality in ENP inflow improved from 1977 to 2005, with significant downward trends in TP concentration. The overall trend ofTP is probably mediated by hydrology, which is evident by a negative relationship between flow and annual average TP concentration at the majority of stations within the available data, although additional changes in vegetation due to hydroperiod may have some effects. Total N (TN), total Kjeldahl N, and total organic N concentrations also generally decreased at inflow sites. Water quality standards for TP, TN, and NH4+ -N were exceeded at selected sites during the study period. Principle component analysis and factor analysis detected a grouping of sampling sites related to the water delivery system that could be used as indicators to better manage monitoring resources. Study results suggest that water quality data analyses could provide additional insight into the success of a restoration management plan and on how monitoring may be modified for more efficient use ofresources.

Jack E. Davis: An Everglades Providence: Marjory Stoneman Douglas and the American Environmental Century

For those with patience, Jack E. Davis’s An Everglades Providence: Marjory Stoneman Douglas and the American Environmental Century, (The University of Georgia Press, Athens, Georgia, 2009), can at times be a most rewarding read. At the same time, some readers’ patience may be tried because Davis, an Associate Professor at the University of Florida, has packed the book with levels of detail that do not always seem warranted for his treatment of Douglas’s long life and her central role in helping to save what is left of the Everglades. There is little doubt, as Davis makes clear, that Douglas was a remarkable woman. She, as much as, or more than most, was responsible for bringing attention to the beauty and uniqueness of lower Florida’s wetland ecosystem, and few worked harder than she to bring about their preservation. Douglas, a journalist, novelist and essayist, poet, social activist, environmentalist, and author of perhaps the seminal work on the Everglades, River of Grass, was by all accounts a force to be reckoned with. Without her passion and advocacy for the Everglades, it is hard to imagine that today there would be an Everglades in any meaningful sense of the term. The account Davis gives in An Everglades Providence is carefully documented. In his research Davis seems to have left no source pertaining to Douglas’s life unexamined. Davis’s biography is over 600 pages long, and this does not include over 120 pages of footnotes. Davis is so careful about his documentation that virtually every paragraph concludes with a footnote. Lovers of this scholarly attention to detail should be pleased. But this reviewer found that this close attention to detail is sometimes unnecessary. As I made my way into the book, I got the feeling that Davis was attempting too much at once, and that he may have been more successful by dividing the effort into several volumes, each with its own theme. Not only does

The Everglades: North America’s subtropical wetland

The Everglades is the largest subtropical wetland in the United States. Because of its size, floral and faunal diversity, geological history and hydrological functions on the Florida landscape, the remaining Everglades are considered to be the crown jewel of U.S. wetlands. It is also called a “sentinel wetland” to test our society’s resolve for ecosystem restoration. Originally called Pa-hay-okee (“grassy lake”) by the American Indians, it was later popularized as the “river of grass” by Marjory Stoneman Douglas. This metaphor unfortunately has led to a simplistic view of the complexities of the Everglades ecosystem and how it functions on the landscape. Often incorrectly referred to as the “marsh” or “swamp,” the Everglades is a fen peatland or alkaline mire. These are important distinctions when one considers how different marshes and swamps are from peatlands in terms of their hydrologic controls, biogeochemistry, rate of peat development, plant and animal communities and-importantly-succession patterns. This paper provides a brief review of the geological processes that led to the development of the Everglades, compares historic and current hydrologic flow patterns, assesses nutrient conditions, presents information on vegetation communities and succession patterns, and provides a new peatland classification of the Everglades system, which may help in the development of a more appropriate restoration management framework.

An Everglades providence: Marjory Stoneman Douglas and the American environmental century

This is the first major biography of one of America's premier environmentalists. No one did more than Marjory Stoneman Douglas to transform the Everglades from the country's most maligned swamp into its most beloved wetland. By the late twentieth century, her name and her classic Everglades: River of Grass had become synonymous with Everglades protection. The crusading resolve and boundless energy of this implacable elder won the hearts of an admiring public while confounding her opponents - growth merchants intent on having their way with the Everglades. Douglas' efforts ultimately earned her a place among a mere handful of individuals honored as a namesake of a national wilderness area.In the first comprehensive biography of Douglas, Jack E. Davis explores the 108-year life of this compelling woman. Douglas was more than an environmental activist. She was a suffragist, a lifetime feminist and supporter of the ERA, a champion of social justice, and an author of diverse literary talent. She came of age literally and professionally during the American environmental century, the century in which Americans mobilized an unprecedented popular movement to counter the equally unprecedented liberties they had taken in exploiting, polluting, and destroying the natural world.The Everglades were a living barometer of America's often tentative shift toward greater environmental responsibility. Reconstructing this larger picture, Davis recounts the shifts in Douglas' own life and her instrumental role in four important developments that contributed to Everglades protection: the making of a positive wetland image, the creation of a national park, the expanding influence of ecological science, and the rise of the modern environmental movement. In the grand but beleaguered Everglades, which Douglas came to understand is a vast natural system that supports human life, she saw nature's providence.

Measurement of activated carbon and other black carbons in sediments

Black carbon in sediment, present natively or added as a treatment amendment in the form of activated carbon, reduces contaminant bioavailability. Field evaluation of activated carbon effectiveness in reducing contaminant bioavailability requires accurate methods to measure the amendment in sediments. The most commonly used method to separate black carbon from natural organic matter in soils and sediments is low temperature (375 °C) thermal oxidation which resulted in significant losses of activated carbons. A method was developed to isolate activated carbon using a solution of concentrated sulfuric acid and potassium dichromate to oxidize the natural organic matter while preserving the activated carbon. The chemical oxidation method was applied to assess the delivery of activated carbon to sediments in a pilot-scale demonstration project carried out in Grasse River, NY. Using this method on sediment from the Grasse River, over 98% of the natural organic matter was removed while preserving at least 95% of the activated carbon. The method was also demonstrated on other carbonaceous geosorbents and native black carbon in several sediment samples.

The effect of activated carbon on partitioning, desorption, and biouptake of native polychlorinated biphenyls in four freshwater sediments

The present study evaluated the effect of activated carbon amendment in four freshwater sediments from the Great Lakes (North America) areas of concern with a wide range of sediment geochemical characteristics (0.83-5.1% total organic carbon) and polychlorinated biphenyl (PCB) concentrations (0.33-84.7 microg/g). The work focused on understanding the impact of activated carbon amendment on PCB aqueous partitioning, PCB desorption characteristics, and PCB biouptake in a freshwater oligochaete (Lumbriculus variegatus). The results showed that PCB aqueous equilibrium concentrations, rapid desorption fractions, and biouptake by the oligochaete were reduced after activated carbon amendment. Addition of activated carbon at a dose of 0.5-fold native organic carbon reduced PCB bioaccumulation by 42% for Niagara River sediment, 85% for Grasse River sediment, 74% for Milwaukee River sediment 1, and 70% for Milwaukee River sediment 2. A linear relationship was observed between log biota-sediment accumulation factor and the first 6-h desorption fractions for each PCB homologue for treated and untreated sediments. Water-lipid bioconcentration factors for PCB congeners were largely conserved after amendment with activated carbon. Our present results suggest that at steady state, changes in the aqueous PCB concentrations can be used to predict changes in PCB bioaccumulation in deposit-feeding organisms. Thus, use of advanced pore-water measurement techniques, such as solid-phase extraction passive samplers, may be suitable for long-term monitoring of treatment performance.

Biodynamic Modeling of PCB Uptake by Macoma balthica and Corbicula fluminea from Sediment Amended with Activated Carbon

Activated carbon amendment was assessed in the laboratory as a remediation strategy for freshwater sediment contaminated with polychlorinated biphenyls (PCBs) from the Grasse River (near Massena, NY). Three end points were evaluated: aqueous equilibrium PCB concentration, uptake into semipermeable membrane devices (SPMDs), and 28-day bioaccumulation in the clam Corbicula fluminea. PCB uptake by water, SPMDs, and clams followed similar trends, with reductions increasing as a function of carbon dose. Average percent reductions in clam tissue PCBs were 67, 86, and 95% for activated carbon doses of 0.7, 1.3, and 2.5% dry wt, respectively. A biodynamic model that incorporates sediment geochemistry and dietary and aqueous uptake routes was found to agree well with observed uptake by C. fluminea in our laboratory test systems. Results from this study were compared to 28-day bioaccumulation experiments involving PCB-contaminated sediment from Hunters Point Naval Shipyard (San Francisco Bay, CA) and the clam Macoma balthica. Due to differences in feeding strategy, M. balthica deposit-feeds whereas C. fluminea filter-feeds, the relative importance of the aqueous uptake route is predicted to be much higher for C. fluminea than for M. balthica. Whereas M. balthica takes up approximately 90% of its body burden through sediment ingestion, C. fluminea only accumulates approximately 45% via this route. In both cases, results strongly suggest that it is the mass transfer of PCBs from native sediment to added carbon particles, not merely reductions in aqueous PCB concentrations, that effectively reduces PCB bioavailability and uptake by sediment-dwelling organisms.

Sm-Nd Isotope Technique as An Exploration Tool: Delineating the Northern Extension of the Thompson Nickel Belt, Manitoba, Canada

Application of Nd isotope mapping to aid mineral exploration has been tested successfully in areas north of the well-prospected, productive portion of the Thompson nickel belt in Manitoba, Canada. Economic nickel deposits in this main part of the belt are restricted to the Ospwagan Group cover sequence and ultramafic sills overlying Archean basement gneisses. Distinguishing some units in the Ospwagan Group from its basement and less prospective Paleoproterozoic paragneiss of the Burntwood Group in the area is difficult based on lithology, stratigraphy, geochemistry, and structure alone. However, the Ospwagan Group has a unique Nd isotope signature that allows it to be identified with certainty. A compilation of Nd isotope data from the main portion of the Thompson nickel belt and a new dataset from drill core and reconnaissance mapping clearly support early exploration indications that basement gneiss and narrow belts of the Ospwagan Group typical of the belt extend northeast of the main part of belt for at least 100 km. This confirms the presence of a large new area for nickel exploration, the limits of which are still unknown. In this poorly exposed, northern area, crustal-residence Nd model ages (T CR ) are instrumental in clearly separating (1) the Ospwagan Group supracrustal rocks (T CR = 2.8–3.2 Ga) that host the nickel deposits from (2) Neoarchean basement gneiss (T CR = 3.2–3.5 Ga), (3) juvenile, overthrust Burntwood (T CR = 2.2–2.6 Ga), Grass River, and Sickle (T CR = 2.0–2.4 Ga) Groups paragneisses, and (4) fragments of a Mesoarchean gneiss complex (T CR = 3.5–4.1 Ga), the latter being the host of precious metal prospects. The variation in Nd model ages not only distinguishes the different supracrustal successions, but the variable inheritance of ancient crustal material in units of Archean gneiss reflected in Nd model ages serves as a tool to unravelling the complexly interleaved structure of this crust and aids in tracing the potentially nickel-hosting Ospwagan Group in narrow structural keels. The robustness of the Nd isotope system under the conditions of high-grade metamorphism and migmatization attained in the Thompson nickel belt makes this an ideal tool for distinguishing between units of economically prospective and barren gneiss in frontier areas where other methods have failed, are difficult to apply, or have led to erroneous interpretations.

Lithostratigraphy and Geochemistry of the High-Grade Metasedimentary Rocks in the Thompson Nickel Belt and Adjacent Kisseynew Domain, Manitoba: Implications for Nickel Exploration

Exploration for nickel in the Thompson nickel belt is focused on specific paragneiss units within the Paleoproterozoic sedimentary and volcanic cover succession (Ospwagan Group) on the northwestern margin of the Archean Superior craton. These units host ultramafic bodies and all significant nickel deposits in the Thompson nickel belt. Knowledge of the lithostratigraphy is therefore essential for finding the units with the highest potential for the discovery of new nickel deposits. This is made practical by a distinctive stratigraphic succession with numerous marker units, including metamorphosed quartzite, carbonate, pelite, iron formation, and graywacke, as summarized in this paper. However, the sedimentary rocks are generally highly deformed and metamorphosed, making the recognition of some units difficult and their sedimentary origin obscure. To better recognize the sedimentary protoliths of orehosting and related units, a simple plot of SiO 2 versus Al 2 O 3 is used to estimate the approximate proportions of siliciclastic and chemical sedimentary components. This demonstrates that much of the succession, which was previously considered to be derived from calcareous and ferruginous chemical sediments, is a hybrid containing a substantial siliciclastic component, thus explaining the present mineralogy and geochemistry and assisting in the recognition of units at various metamorphic grades. Extended-element plots, using the most abundant metapelite unit in the Ospwagan Group as the normalizing factor, show a common provenance for the entire group. They also illustrate a clear difference between the Ospwagan Group and the underlying basements gneiss and allow the Ospwagan Group to be distinguished from petrographically similar but economically barren, younger paragneiss units of the Burntwood and Grass River groups. Unlike the Ospwagan Group, the younger units, which predominate in the Kisseynew Domain adjoining the Thompson nickel belt, were derived mainly from an exotic Paleoproterozoic arc-related source and therefore have a different geochemical signature. This geochemical difference can be utilized in areas of sparse geologic information, such as beneath Phanerozoic or glacial cover, where initial exploration drilling tests new geophysical targets. Combined litho- and chemostratigraphy improve insight into basin evolution, which probably occurred on a ca. 2 Ga passive continental margin or shelf. The ca. 1880 Ma maficultramafic magmatism related to the nickel deposits may have formed in a different tectonic environment, possibly in a continental back arc associated with a recently proposed episode of felsic calc-alkaline plutonism.

Microcosm Experiments to Assess the Effects of Temperature and Microbial Activity on Polychlorinated Biphenyl Transport in Anaerobic Sediment

Increased polychlorinated biphenyl (PCB) loadings from sediment to the water column under low-flow conditions during late spring and summer months have been observed in the Grasse River (Massena, NY) and other PCB-contaminated rivers in the United States. Temperature appears to be an important factor affecting this phenomenon, as increased sediment temperature leads to increased microbial and bioturbator activity as well as increased rates of diffusion and desorption. Laboratory-scale sediment microcosms were developed and used to study with fine-scale resolution the effects of temperature and microbial activity on PCB transport in river sediment. Over the time course of these experiments, with the extraction procedures used, irreversible sorption of each congener to sediment was observed and increased with aging of the sediment. Temperature-dependent transport was observed for PCB congeners 2,4,5-trichlorobiphenyl (BZ29), 2,5-dichlorobiphenyl (BZ9), and 2-chlorobiphenyl (BZ1) in Grasse River sediment and a synthetic sediment system. The fastesttransport of the congeners occurred in biologically active Grasse River sediment followed by biologically inactive (autoclaved) Grasse River sediment, and synthetic sediment. The increased transport in biologically active sediment demonstrated the importance of microbial activity, in particular gas bubble generation, in PCB transport in near-surface sediments.

Searching for the Grass River

Searching for the Grass River

Release of Polychlorinated Biphenyls from River Sediment to Water under Low-Flow Conditions: Laboratory Assessment

The diffusive release of polychlorinated biphenyls (PCBs) from sediments to water under low-flow conditions was measured for surficial sediments with different PCB concentrations collected from the Grasse River near Massena, N.Y. Data on PCB sediment-water equilibrium partitioning and PCB mass release flux from sediments were used to assess the extent and mass transfer rate of PCB release under low-flow conditions in the Grasse River. Microcosm studies were employed to evaluate the release flux of PCBs under quiescent conditions for various river sediments and sediment mixtures. The observed total-PCB release fluxes ranged from about 1 to 20 mg/m2⋅year, showing predominantly dichloro- through tetrachlorobiphenyls. Analyses of water column samples from the Grasse River under low-flow conditions also indicated the predominance of dichloro- through tetrachlorobiphenyls as in the microcosm tests. Data on PCB equilibrium partitioning between water and sediment were used to estimate sediment porewater concentra...

Pilot‐scale demonstration of in situ capping of PCB‐containing sediments in the lower Grasse River

AbstractA fish‐consumption advisory is currently in effect in a seven‐mile stretch of the Grasse River in Massena, New York, due to elevated levels of PCBs in fish tissue. One remedial approach that is being evaluated to reduce the PCB levels in fish from the river is in situ capping. An in‐river pilot study was conducted in the summer of 2001 to assess the feasibility of capping PCB‐containing sediments of the river. The study consisted of the construction of a subaqueous cap in a seven‐acre portion of the river using various combinations of capping materials and placement techniques. Optimal results were achieved with a 1:1 sand/topsoil mix released from a clamshell bucket either just above or several feet below the water surface.A longer‐term monitoring program of the capped area commenced in 2002. Results of this monitoring indicated: 1) the in‐place cap has remained intact since installation; 2) no evidence of PCB migration into and through the cap; 3) groundwater advection through the cap is not an important PCB transport mechanism; and 4) macroinvertebrate colonization of the in‐place cap is continuing. Additional follow‐up monitoring in the spring of 2003 indicated that a significant portion of the cap and, in some cases, the underlying sediments had been disturbed in the period following the conclusion of the 2002 monitoring work. An analysis of river conditions in the spring of 2003 indicated that a significant ice jam had formed in the river directly over the capping pilot study area, and that the resulting increase in river velocities and turbulence in the area resulted in the movement of both cap materials and the underlying sediments. The pilot cap was not designed to address ice jam–related forces on the cap, as the occurrence of ice jams in this section of the river had not been known prior to the observations conducted in the spring of 2003. These findings will preclude implementation of the longer‐term monitoring program that had been envisioned for the pilot study. The data collected immediately after cap construction in 2001 and through the first year of monitoring in 2002 serve as the basis for the conclusions presented in this article. It should be recognized that, based on the observation made in the spring of 2003, some of these conclusions are no longer valid for the pilot study area.The occurrence of ice jams in the lower Grasse River and their importance on sediments and PCBs within the system are currently under investigation. © 2003 Wiley Periodicals, Inc.

Buffalo Tiger: a life in the Everglades

In 1959 a group of Miccosukee Indians, frustrated in their attempts to gain official recognition by the United States, met with Fidel Castro and were recognized by the Cuban government. The man behind this unprecedented move to provoke the United States government into action was Buffalo Tiger, a Miccosukee elder who has become one of the most prominent Indian leaders in the southeastern United States in the modern era. This book is the story of Buffalo Tiger's life, told in his own words. Born in a small village in the Everglades in 1920, Buffalo Tiger grew up immersed in the traditional customs and language of the Miccosukees. Making their home for generations in the remote reaches of the Everglades, the Miccosukees were able to retain much of their older way of life well into the twentieth century. As the modern world encroached on the Miccosukees and the Everglades shrank around them, Buffalo Tiger became an energetic and outspoken leader of the community. He and other Miccosukees fought for years to escape the shadow of the larger, better known, and more politically powerful Seminoles. As the first tribal chairman of the Miccosukees, Buffalo Tiger oversaw the adoption of a tribal constitution and worked diligently for reforms and to protect the community's cultural and natural resources. In the 1970s the Miccosukees became the first modern tribe to take complete control of their affairs and federal budget. Buffalo Tiger's penetrating observations about his people and the world around them, combined with the skilled scholarship of historian Harry A. Kersey Jr., strikingly illuminate a memorable life, a tireless leader, and an Indian community still proud to call the River of Grass its home.

Multimedia Chemical Fate Model for Environmental Dredging

Dredging the bed-sediment of rivers, lakes, estuaries, and harbors is a process of remediating contaminated sites. Whether used alone or in conjunction with in situ capping or natural recovery, its application results in the loss of contaminants to the surroundings. A steady-state multimedia box model has been developed consisting of a dredge element that initiates chemical release in a flowing stream and an algorithm for residue transport to air, water, and sediment, both with and without silt curtain containment. The model quantifies these losses and, commencing with the original in-place contaminant mass, determines the quantity targeted for dredging and the quantity ''delivered to shore.'' The latter is a measure of the efficiency of the dredging operation. The model was developed from experience gained studying the effectiveness of environmental dredging at three sites: Bayou Bonfouca ~Slidell, La.!, Grasse River ~Massena, N.Y.!, and Manistique Harbor ~Manistique, Mich.!. This paper describes the multimedia model theory and algorithm development and demonstrates its use in the application to the Bayou Bonfouca Superfund site, which was dredged for removal of creosote waste containing 16 polyaromatic hydrocarbons.

Reductive dechlorination of polychlorinated biphenyls as affected by sediment characteristics

The effect of sediment sources on the selection of polychlorinated biphenyl (PCB) dechlorinating competence was investigated using sediments from two different locations, the Grasse River and Owasco Lake. These two sediments had a similar organic carbon content but different particle size distribution. The two PCB-free sediments were spiked with Aroclor 1248 and inoculated with microorganisms from the Reynolds and General Motors sites in the St. Lawrence River, which exhibited different dechlorination patterns. When each inoculum was serially transferred into fresh sediments four times (every 8–10 weeks), they still maintained the initial dechlorination patterns regardless, the source of sediments and the number of transfers, and dechlorination patterns of the two inocula in the same sediments did not converge. In a parallel approach, when the acclimated microorganisms from the Reynolds site were inoculated into fresh sediments from both sources as well as sediments enriched with organic carbon (2%, w/v), the dechlorination pattern remained unchanged after a 40-week incubation. These results suggest that the sediment characteristics or organic carbon content did not play a role in the selection of dechlorinating populations.

Modeling the biophysical and social dynamics of a ‘River of Grass’: a challenge for hydroinformatics

A number of major water resource ecosystem restoration projects are currently underway in the United States. One is focused on the Everglades, a unique ecosystem in southern Florida. The Everglades restoration project is estimated to cost some $8 billion over a period of about 50 years. It is not only a challenge to scientists attempting to understand the physical and biological processes affecting the unique hydrology and ecology but also to planners and decision makers dealing with the social dynamics of the people living in the area. People impact the Everglades, and the rate of population growth in southern Florida shows no sign of decreasing. The outcome of this ecosystem restoration effort will largely be determined by the land use decisions and social activities of these people over the next several decades. It may also be influenced by political decisions made far outside the region, such as in Washington with respect to sugar subsidies (i.e., our relations with Cuba). It may be influenced by climate change (e.g., sea level rise) as well. In this complex physical and social environment, scientists from private and public agencies are working together with all concerned stakeholders to plan and manage the restoration project. Models are being developed and used to estimate the various impacts that may result from any plan or management policy. As expected, there exist conflicts among various stakeholders. If there was ever a challenge for those involved in building models and associated decision support systems for impact prediction and for communicating information to multiple stakeholders having quite different interests and concerns—all in an effort to obtain some consensus or shared visions of what should be done, and why—this project provides one.