Pescadero Marsh annotated bibliography
Pescadero Marsh annotated bibliography:
Abram, D., D. Clarks, et al. (2006). Reconstructing the sediment history of Pescadero Lagoon- preliminary report (PDF). Liverpool, University of Liverpool: 4.
The evolution of Pescadero Lagoon was reconstructed in terms of relative sea level and how this has altered the distribution of environments within the catchment. Sediment stratigraphy was sampled by gouge coring and examines using the Troels-Smith classification scheme. Magnetic susceptibility tracing was applied to further clarify sediment provenance. Our results show a transition from a terrestrial to a marine dominated depositional environment and suggest that tectonic subsidence has acted significantly on the area.
B.G.C. (1988). Berlogar Geotechnical Consultants. Geotechnical report Pescadero Marsh: Pescadero State Beach, Pescadero, California (PDF), for Office of the State Architect.
This report was commissioned by the Office of the State Architect for the purposes of assessing geologic conditions in the marsh. Conclusions were presented on marsh chronostratigraphy, estimated depth to bedrock, soil compressibility and compaction characteristics. The goal of the project is to ultimately restore parts of the marsh complex. The following qualitative and quantitative date was collected: Review of pertinent geologic maps and literature; Examination of stereopaired aerial photos; Geologic reconnaissance by staff; Nine test borings to max. depth of 76.5 feet; 26 hand-augered bores; Lab analysis to evaluate engineering properties of marsh soils; Radiocarbon dating and palynological exams to evaluate the age of the marsh.
Bell, C., A. Dover, et al. (2006). An Investigation into the Sedimentary Record of Coastal Lowlands: Waddell Creek (PDF), Univerity of Liverpool.
Boscacci, E. J. (2004). Pescadero Creek. Creek modification options to remove floodway restrictions and recover San Francisco garter snake populations. Prepared for the Pescadero Foundation., BKF Engineers, 540 Price Avenue, Redowwd City, CA.
The purpose of this report is to provide a plan that documents Creek channel modification required to reduce or eliminate the extent of the floodway within the urban/Rural Boundary Line of Pescadero. The purpose of this study is to present a conceptual idea of the extent of modifications required for purposes of discussion with approval Agencies.
Bostick, B., C., C. Chen, et al. (2004). “Arsenite Retention Mechanisms within Estuarine Sediments of Pescadero, CA.” [Subscription required] Environmental Science and Technology 38: 3299-3304.
Arsenic, a toxic metalloid, is commonly associated with sulfide minerals in anoxic sediments. Here we characterize arsenic(III) retention on sediments from a sulfidic estuarine marsh using a series of sorption experiments, and probe the structure of retained arsenite with X-ray absorption spectroscopy. Although the extent of sorption varied with sampling locations, several adsorption characteristics were apparent. A fraction of arsenite adsorbed over the entire pH range examined, although it was most extensive at pH greater than 7, and conformed to a Langmuir isotherm. Iron sulfide phases were responsible for As partitioning in these sediments. Initially, an FeAsS-like precipitate formed with a structure similar to those reported for As(III) sorbed on iron sulfides, a complex that is highly reactive. Following reaction for 21 d, much of the FeAsS-like precipitate was converted to As2S3. A drop in the redox potential accompanied this conversion, suggesting that the evolution of sulfide and other reduced species stabilizes bound arsenic. Processes discerned in this study reveal the importance of sulfide minerals in As sequestration within anoxic environments.
Chambers, L. A. (1982). “Sulfur isotope study of a modern intertidal environment, and the interpretation of ancient sulfides.” [Subscription required] Geochimica et Cosmochimica Acta 46(5): 721-728.
Extensive sulfur isotope distribution data for sulfides precipitated in an intertidal environment show no distinctive features when compared with isotope values for other marine, sedimentary sulfides. The fractionation ranges from a = 1.030 to a = 1.048. The pattern is characteristic for a system essentially open to sulfate, and isotope analyses of interstitial sulfates are corroborative. A population of sulfate-reducing bacteria of the order of 109 organisms per cc of interstitial water is indicated. Seasonal variation of the isotope distribution reflects a transient sulfide composition and a bacterial population in which the fractionation effect is indirectly controlled by temperature. The data presented for this modern shallow water environment are at variance with an earlier assessment of isotopic distributions in ancient sulfides which linked shallow water environments with limited fractionation (a less-than-or-equals, slant 1.025) in a closed system.
Cook, W. and A. Cook (1997). Butano Creek sedimentation and flooding.
William Cook is a Pescadero resident and a San Mateo Coutny real estate agent interested in the flooding of Butano Creek at Pescadero Creek Road bridge. The flooding of this area has been linked to moderate to severe erosion in the upper watershed. Primarily, this document is a compilation of all known studies and reports that have addressed this issue. In addition it is a chronology of the work that Mr. Cook has initiated and accomplished.
This document, no doubt, led to the 1999 Proposal for the implementation of preferred alternatives of the California Department of Parks and Recreation Pescadero Marsh Hydrological Enhancement Plan. Although there is no new quantitative data in this package, there is some interesting historical information. The following information is contained in this document: *Butano Creek: Sedimentation and flooding, Status report and report on actions 1900 – 1996, prepared by the coordinated Resource Management and Planning (CRMP); *Butano Creek Channel Clearing Project Information, 1997; *Permits for creek work for the 1997 project and for work on the Bean Hollow Road bridge over Butano Creek; *Letter from the governing body of Pescadero, the Pescadero Municipal Advisory Council to the California Department of Forestry and Fire Protection regarding their perception of timber harvest plan inadequacies in the Pescadero-Butano watershed.; *Photographs of flooding in winter 1996-1997; *Army Corps of Engineers Reconnaissance report; *Flood control improvements Pescadero and Butano Creeks.
This document is a proposal to form a cooperative between land owners, California State Parks and Recreation and the Natural Heritage Foundation (NHF) for the purpose of implementing the preferred alternative, Create a South Delta Marsh, of the Phillip Williams Associate’s Hydrological enhancement plan. NHF is a national non-profit specializing in the protection and management of wetlands. The document includes the following two quantitative graphics: *1965 and 1999 cross section of Butano Creek at the Pescadero Creek Road Bridge; *October, 1997 to January, 1999 Butano Creek water levels at Pescadero Creek Road bridge
Curry, R. R., T. Kidwell, et al. (1985). Pescadero Marsh Management: A plan for persistence and productivity Hydrologic study (Phase I and II) Pescadero Marsh for California State Parks
Robert Curry, Ph.D., and his team from UC Santa Cruz conducted this study primarily to advise State Parks on marsh restoration and long-term management. The following graphs, photos and technical discussions of historic studies are included in the document: *1928 aerial photo, 1854 topographical map and 1983 lagoon mouth photos; *Discussion of current issues affecting the Pecadero watershed and marsh and the need for a system-wide management approach; *Discussion on goals and outlines a method for an enhancement project; *Discussion on the effects of structural geology on the Pescadero watershed; *Discussion of the geomorphological effects on the watershed; *Discussion of beach sediment origin based on dissertation research by Gerald Weber (UC Santa Cruz); *Discussion on beach and lagoon characteristics based on aerial photos; *Discussion of human alterations to the marsh complex (i.e. Highway 1, tunnel in rock at mouth); *Discussion on the marsh and stream section as they pertain to sediment grain size and deposition found in cores; *Discussion on sea-level and tectonic contributions to marsh formation based on knowledge from Central California; *Discussion on the human alternations to the marsh and alternatives approaches to restoration planning; *Recommendations for restoration
The following quantitative studies were reported:*Two years of close observation of beach conditions, lagoon water levels, tidal conditions, streamflow and beach profile surveys (June 1983 to December 1984); *Model conditions of change through historic time using reports from 1939, 1969, 1979, 1981, 1982 and 1984; *Developed a synthetic record for Pescadero Creek; *Constructed storm event record from precipitation records and runoff records; *Tidal corrections for Pescadero based on observation; *Elevation data from surveys; *Flood analysis based on flow gauge records; *Sediment transport model based on data from low flow years; *Tidal exchange and breakout floods based on flow and sediment model.
Elliott, B. G. (1975). The natural resources of Pescadero Marsh and environs, (PDF) California Department of Fish and Game.
This document is a review of the marsh and its natural resources. The purpose of this inventory is to assist private citizens, planners, administrators and others concerned with the development of the Pescadero coastal area. The report contains the following qualitative discussions and lists: *(List and discussions of plants, birds, reptiles, amphibians, fish and mammals of the marsh; *Discussion of the major wildlife habitat types in the watershed; *History of the area
Conclusions: *Low stream flows in summer/fall will lead to the siltation of creeks and the death of the marsh; *Levees, dikes and reduced flushing at mouth reduces flushing of North Pond and North Marsh; *Water quality suffers in downstream areas from lowered water tables and well contamination.
ESA (2004). Environmental Science Associates. Pescadero-Butano watershed assessment.
This document contains a discussion on erosion and sediment delivery in Pescadero and Butao Creek watersheds for the last century as well as a complete discussion on the history and evolution of the upper watershed’s current conditions. The following is a list of those discussions and additional analysis: *Discussion on the quality of salmonid habitat in Pescadero and Butano Creeks; *Analysis of gauge record at the USGS Pescadero Creek flow gauge; *Comparison of present and historical bridge cross-sections in both watersheds; *Sediment source and volume study (Pacific Watershed Associates 2003); Stream channel study (channel geomorphic conditions in selected streams); Quantitative and qualitative assessment of watershed salmonid habitat.
Handler, N., A. Paytan, et al. (2006). “Human Development is Linked to Multiple Water Body Impairments Along the California Coast.” [Subscription required] Estuaries and Coasts 29(5): 860-870.
To elucidate relationships between land cover and water quality along the central California coast, we collected monthly samples from 14 coastal waterway outlets representing various degrees of human development. Sites were distributed between three salinity categories, freshwater, estuarine, and marine, to better understand land cover-water quality relationships across a range of coastal aquatic ecosystems. Samples were analyzed for fecal indicator bacteria (FIB), dissolved nutrients, stable nitrogen isotopes in particulate organic matter, and chlorophyll a (chl a). Sediment samples from 11 sites were analyzed for the concentration of the anthropogenic organic contaminant perfluorooctane sulfonate and its precursors (SPFOS). While the data indicated impairment by nutrient, microbial, and organic contaminants at both agricultural and urban sites, the percentage of agricultural land cover was the most robust indicator of impairment, showing significant correlations (p , 0.05) to FIB, nutrient, chl a, and SPFOS levels. FIB densities were strongly influenced by salinity and were highest at sites dominated by agriculture and urbanization. Nutrient levels and chl a correlated to both agricultural and urban land use metrics as well. Positive correlations among FIB, nutrients, chl a, and SPFOS suggest a synergy between microbial, nutrient, and organic pollution. The results emphasize the importance of land management in protecting coastal water bodies and human health, and identify nutrient, microbial, and organic pollution as prevalent problems in coastal California water bodies.
Jennings, M. R. and M. P. Hayes (1990). Status of the California Red-legged frog, Rana aurora draytonii, in the Pescadero Marsh Natural Preserve.
Pescadero Marsh was believed to be one of the largest, if not the largest, breeding colony of red-legged frogs in California. This survey was conducted to assess the size and range of the Pescadero Marsh population. The study also compared the Pescadero population to a control population in Pico Creek, San Luis Obispo. This region has a similar temperature and tidal regime, but has not suffered the habitat alteration and bull frog introductions that Pescadero has. The following quantitative data was collected: *15 days of nighttime sampling for egg masses, juveniles and adults; *Size distribution of 64 captured adult frogs (length snout to vent); *Comparison chart of Pescadero frogs’ lengths versus Pico Creek’s frog lengths; *Egg and embryo survival and rates of hatch deformation at varying salinities; *Surface salinity data from 1978 to 1989, sites selected from Violis (1979), Smith 1987 and this study; *Maps of sites and associated vegetation.
Kamman (2006). Kamman Hydrology and Engineering Inc. Data Synthesis and Hydrodynamic model development feasibility report Pescadero Lagoon, San Mateo County, California. Prepared for the California Coastal Conservancy.
This report summarizes the results of the following tasks, undertaken by KHE to initiate the assessment and scoping study: *Review existing data and prior studies related to Pescadero Lagoon hydrologic, flow and water quality characteristics and fish habitat; *Interview available resource agency personnel regarding existing information and theories related to fish die-offs in the marsh; and *Identify data gaps and additional information, including hydrological studies of Pescadero Marsh, needed to support technical analysis and model development; *Prepare a proposed scope of work to address data gaps identified as part of this evaluation; *Define the requirements for and feasibility of developing a numerical model that can be used to determine the causes of fish die-offs in Pescadero Lagoon; *Evaluate the feasibility of developing a numerical model that can be used as planning and analysis tool for evaluating potential physical and management actions to reduce the likelihood of future fish die-offs and enhance ecological habitats within Ppeescadero lagoon/marsh; and, *Prepare a proposed scope of work to conduct a numerical modeling study (if feasible) to determine the cause(s) of fish die-offs within the estuary, and identify measure to ameliorate the problem.
Parks (1992). California Department of Parks and Recreation. Pescadero Marsh Natural Preserve hydrologic enhancement project (PDF).
This plan is based upon recommendations from the 1987, 1988 and 1990 Phillip and Williams hydrologic surveys. There are five major components: levee removal, levee construction, levee breach, channel excavation, excavation material disposal and sag pond construction. This document contains detailed descriptions and maps of these five project areas. The document also includes: *Existing and estimated, post-project creek, channel and upland cross sections of Pescadero and Butano marsh areas; *Map of soil types; *Pre-restoration photos.
P.W.A. (1987). Phillip Williams and Associates. Pescadero Marsh survey report
This document was prepared for the purposes of providing baseline environmental data for future research, monitoring and restoration. The greatest contribution of this study is the detailed topographic maps of just the marsh. There are six large topographic maps with a one-inch to 100 foot scale, 1 foot contours, aerial photographic base and bathymetry. *34 cross sections of creek, marsh, pond and channel geometry; *Area and volume surveys for elevations below 10 feet for the entire marsh and then for four sub- regions of the marsh; *A 1988 reconnaissance report on the geomorphology of Butano Creek below Butano Falls; *Butano and Pescadero Creek flood frequency analysis based on USGS stream flow gauges; *Tide frequency curve; *Tidal datums for Pescadero area in open ocean;*Ten vegetation transects performed at established State Parks sites.
An additional document titled Pescadero Marsh hydrological and topographical analysis was submitted in 1988 by Williams/Swanson. This document is essentially a compilation of several different studies, some conducted by Williams/Swanson, some not. The following is a list of those documents: *Three maps comprise the “geophysical report”; *Construction of hypsometry data for Pescadero marsh from historical maps (Morrison 1988); *Hydraulic evaluation of Pescadero Creek Bridge Replacement (Caltrans 1984); *Subsurface geophysical investigation at the mouth of Pescadero (Swanson 1988); *Flood insurance study, San Mateo County, California unincorporated areas (Federal Emergency Management Agency 1982).
P.W.A. (1990). Phillip Williams and Associates. John Williams. Pescadero Marsh hydrological enhancement plan.
This document was the plan that guided the plans for the 1993 and 1997 restoration action of the marsh. The comprehensive review of the history and literature includes the following: *Discussion on the historical setting of the marsh; *Discussion of the present setting of the marsh; *Discussion on mouth dynamics as they pertain to bedrock (Caltrans cores and Curry’s (1985) surveys at the mouth of Pescadero Creek included); *Discussion on vertical stratification based on Smith 1990; *Discussion on accelerated erosion based on Osterling (1987) and Williams (1988, Butano recon report); *Bried discussion of biology based on studies by Elliot (1975), Jennings and Hayes (1990), Smith (1990), Anderson and Morgan (1975) and Metroupolis (1989); *Discussion of management problems and opportunities; *Discussion of enhancement options for managers; *Includes a draft of the ACOE recon report for flood control
In addition, the following quantitative studies were performed: *Stage-volume relations and tidal prism; *Siltation of lagoon and stream channels based on aerial photos and historical cross sections; *Sediment transport in Butano Creek based on measurements, with a discussion on Curry’s explanation; *Flood flows and elevations in the preserve
PWA (2003). Pacific Watershed Associates. Sediment Assessment of Roads and Trails within the Pescadero/Memorial/Sam McDonald County Park Complex, Pescadero Creek Watershed, San Mateo County, California. Prepared for San Mateo County Parks and Recreation Department and California Department of Fish and Game.
In January 2002, Pacific Watershed Associates (PWA) was contracted by San Mateo County Parks and Recreation (SMCPR) to inventory 65 miles of roads and trails within the Pescadero/Memorial/Sam McDonald County Park Complex for sites of future erosion and sediment delivery to streams, and toprepare a prioritized erosion prevention plan (Figure 1). This project was funded through a CDFG S.B. 271 watershed restoration grant (Contract # P-0030412). This project was specifically aimed at identifying future erosion sources that are impacting fish bearing streams and to develop prescriptions aimed at reducing sediment input to the watershed. This project was not concerned with those erosional features that are not delivering sediment to the stream network.
ROC (1987). Ralph Osterling Consultants Inc. Analysis of the Pescadero Marsh watershed
Osterling consultants were contracted by Peninsula Open Space Trust to develop an analysis on sediment sources within the upper watershed lands that flow into Pescadero Marsh. This was primarily undertaken because of concern regarding sedimentation and loss of ecological integrity in the coastal wetland system. Mitigation measures for sediment reduction are also presented in this report. This report includes six, large, 1:12,000 scale topographic maps of the entire Pescadero watershed, including the marsh area. Other maps that would be extremely helpful include: *Distribution of rainfall by elevation for the watershed *Soil associations of the watershed
Discussions included focus on the following topics: *Logging history; *Mitigation measures; *Current conditions of the entire watershed
Quantitative undertakings include: *Stream Reach Inventory and Channel Stability Evaluation based on a modified method used by U. S. Forest Service Region 5 (California); *Fish habitat survey of portions of upper Pescadero and Butano creek (1986).
Rondeau, H. and K. Himes. (2000). “Plant list Pescadero Marsh.”
Some plants observed along the Sequoia Audubon trail, Pescadero Marsh, during a CNPS field trip, October 21 1989. Leaders: Hawkeye Rondeau and Ken Himes.
Sloan, R. (2006). Ecological Investigations of a fish kill in Pescadero Lagoon, CA. San Jose, San Jose State University. Masters of Science.
This thesis investigates the cause of annual fish and invertebrate kills and describes the water quality setting during the 2004 and 2005 sandbar breaches. The study found hypoxia, and the associated hydrogen sulfide toxicity, to be the most likely cause of species mortality. Salinity stratification was found to predict bottom water dissolved oxygen while nutrient concentrations or wind did not. Nutrient loading data and surface water nutrient concentrations suggest mild eutrophication, but do not explain water quality complications after sandbar closure. The following quantitative data was collected between fall 2004 and winter 2005: *Monthly vertical profiles for DO, salinity and temperature (weekly during sandbar closure) and bottom water hydrogen sulfide concentrations; *Monthly surface nutrient and chlorophyll a sampling at 8 marsh locations and two creek locations just upstream of the marsh (12/04 – 1/06); *Bi-weekly, duplicate, surface and bottom nutrient and chlorophyll a samples for eight marsh locations; *Continuous bottom water DO, salinity, temperature and pH for seven marsh locations; *Continuous surface and bottom water DO, salinity, temperature and pH for eight marsh locations; *Bi-monthly surface sediment collection for organic carbon content and sediment size distribution; *Sediment and bottom water pollution screen for common agriculturally-associated toxins in two marsh locations; *Aquatic and marine macrovegetation percent cover estimates for eight marsh locations (3/05 – 12/05).
Smith, J. Lagoon Ecology of Central Coast Steelhead and Tidewater Goby (PDF), San Jose State University: 4.
This five-year long, comprehensive study was undertaken for the purposes of understanding the quality of habitat that Pescadero Marsh Natural Preserve and other, smaller systems on the central coast of California were providing. He performed extensive fish and water quality surveys, focusing exclusively on the marsh and lagoon habitats. In this report Smith discusses the effects of stream flow, tidal action and sandbar formation on the quality of the lagoon habitat for fish and other aquatic species. The study includes the following quantitative data: *Vertical profiles of DO, salinity and temperature in Pescadero creek, Butano Creek, Pescadero Marsh and the lagoon for the summer and fall of 1984-1989; *Fish assemblage composition and length distributions of seined species in Pescadero Creek, Butano Creek, Pescadero Marsh and the lagoon (primarily from summer and fall surveys, 1984 – 1989).
Smith, J. and D. Reis (1997). Pescadero Marsh Natural Preserve salinity, tidewater goby and red-legged frog monitoring for 1995-1996.
This study was undertaken in an attempt to assess the functioning of the estuary/marsh complex in response to the restoration and to propose recommendations for further restoration. The following quantitative data was collected: *Salinity and temperature vertical profiles in 18 sites, ranging from Dec. 94 to Dec. 96; *Surface elevation was also recorded at the same 18 sites from Dec. 94 to Dec. 96; *1995 late summer dipnet and seine survey for red-legged frog larvae, adults were tallied during water quality transects; *Egg mass counts performed on 16 days from Feb. 22 to April 30 in 1996; *Seine and dipnet larval surveys were conducted on 20 days from April 17 through June 21, 1996; *53 Adult and juvenile day surveys were conducted between Jan. 28 and Dec. 8 1996; *San Francisco garter snake sightings were recorded during water quality and frog surveys; *Tidewater gobies sampled by seine and dipnet in 1995 and 1996; *Distribution maps of red-legged frog egg masses, juveniles and adults, Pacific tree frogs and bull frogs.
Swanson (1999). Swanson Hydrology and Geomophology. Pescadero Creek Road hydraulic study.
This report was compiled for the purpose of evaluating flood abatement measures for the Pescadero Creek Bridge road over Butano Creek. The flows of Pescadero and Butano were modeled using the U.S. Army Corps of Engineers Riven Analysis System simulation model. The model was calibrated using existing conditions from the February 1998 flood. The document discusses the merit of raising the bridge 13 ft. above mean sea level.
Swanson (2002). Swanson Hydrology and Geomorphology. Biogeochemical function of the San Lorenzo River Lagoon, 2002 season results.
This document compares Aptos, San Lorenzo, Soquel, Scott Creek and Pescadero lagoon systems using primarily nutrient and water quality analysis. Regarding Pescadero lagoon, the following data were discussed: *1997 grab sample from Pescadero Creek fro nitrate, nitrite and phosphate; *DO, salinity, temperature, pH and depth from a continuous monitoring probe place in Pescadero marsh in late summer and fall of 2002; *Grab samples analyzed fro nitrate and phosphate from Butano and Pescadero Creeks monthly in the summer and fall of 2002; *Discussion of chemical processes during bar closure and breeching.
Swenson, R. O. (1999). “The ecology, behaviour and conservation of the tidewater goby, Eucyclogobius newberryi.” [Subscription required] Environmental Biology of Fishes 55: 99-114.
USACE (1989). Army Corps of Engineers. Draft – Section 205 – Reconnaissance Report: Flood Control Improvements, Pescadero and Butano Creeks, San Mateo County, California (PDF).
This report was performed as a provision of the Section 205 of the Flood Control Act of 1948. The study addresses the flooding of Pescadero and Butano Creek near the town of Pescadero. It includes economic evaluations of several alternatives to flooding protection. The study found that a project on Pescadero Creek was economically justified, while one at Butano Creek was not.
USFWS (2005). Recovery Plan For the Tidewater Goby (Eucyclogobius newberryi) (PDF), Pacific Region U. S. Fish and Wildlife Service Portland, Oregon.
Viollis, F. S. (1979). The evolution of Pescadero Marsh (PDF). San Francisco State University. Masters of Science.
This document provides an excellent geological, ecological and human history of Pescadero Marsh. The following lists, graphs and pictures are included in the document: *Tables of breeding bird census and area productivity (Metropulos 1978); *Pre-1900 aerial photos of the town; *1970 aerial photo of the marsh and town; *1925 map of farm properties, indicating salt and freshwater vegetation; *Photos indicating the slow conversion of a freshwater marsh to a brackish water marsh; *Geologic map of lower Pescadero Creek (USGS misc. field study map 1972); *Photos indicating dune vegetation changes; *Photos indicating changes in the marsh caused by human disturbance, i.e. levees, bridges, cultivation, roads, etc.
The quantitative studies that were performed include: *6, 500-700 cm cores in selected marsh areas were analyzed for particle size, visible stratifications and biotic composition.; *Carbon 14 dating to determine rate of deposition.
Whisney, P. B. (1984). Hydraulic evaluation Pescadero Creek bridge replacement. Caltrans, Dept. of Transportation.
The document discusses four alternatives for the Highway One bridge replacement. It includes discussion on flood events and information collected in the 1984 FEMA flood insurance study. Alternatives were discussed and evaluated based on modeling.
Wilkin, R. T. and R. G. Ford (2006). “Arsenic solid-phase partitioning in reducing sediments of a contaminated wetland.” [Subscription required] Chemical Geology 228(1): 156-174.
The geochemical partitioning of arsenic in organic-rich sediments from a contaminated wetland is examined using X-ray absorption spectroscopy and selective chemical extraction procedures, and evaluated in context to the anoxic diagenesis of iron and sulfur. The interaction between ground water and surface water has a significant influence on iron sulfide formation in the wetland sediments. Ground-water seeps supply concentrations of sulfate, dissolved hydrocarbons, ferrous iron, and arsenic, and sediments located near seeps are anomalously enriched in arsenic, reactive iron, and acid-volatile sulfides. Degree-of-sulfidation (DOS) values are high in sediments adjacent to sites of ground-water discharge, ranging from 0.57 to 1.0. Pyrite (FeS2) formation is apparently not limited by the abundance of any one primary reactant, e.g., organic carbon, sulfate, or reactive iron; instead, persistence of precursor iron monosulfides is attributed to slow pyrite formation kinetics due to low concentrations of reactive intermediate sulfur species or possibly due to high concentrations of arsenite, dissolved organic-carbon, or other solutes that adsorb to iron monosulfides surfaces and impede transformation reactions to pyrite. Greigite (Fe3S4) accounts for > 80% of total reduced sulfur in sediments rich in acid-volatile sulfide and X-ray absorption spectroscopy data for magnetic separates provide direct evidence that As(III) is, at least in part, associated with reduced sulfur in the form of greigite. However, pyrite can only account for a small percentage, < 20%, of the total arsenic budget in the reduced sediments. Although pyrite is the predicted stable endpoint for reactive iron and sulfur, it appears that within a 30 y time period pyrite is a relatively unimportant host for arsenic in the system investigated here. The abundance of reactive iron in the sediments prevents accumulation of dissolved sulfide and thus prevents formation of soluble thioarsenic species. X-ray absorption near-edge structure (XANES) spectroscopy indicates only the presence of As(III) in the reduced sediments. Results of linear combination fitting of reference spectra to sediment spectra are consistent with sulfur- and/or oxygen-coordinated As(III) in association with iron monosulfides and ferrous-bearing carbonates or hydroxides.