WorldWideScience

Sample records for tuscahoma marsh clays

  1. Clay mineralogy, grain size distribution and their correlations with trace metals in the salt marsh sediments of the Skallingen barrier spit, Danish Wadden Sea

    DEFF Research Database (Denmark)

    He, Changling; Bartholdy, Jesper; Christiansen, Christian

    2012-01-01

    metals. The clay assembly of the sediment consists of illite, kaolinite and much less chlorite and smectite. The major clay minerals of illite, kaolinite as well as chlorite correlate very poorly with all the trace metals investigated, due probably to the weak competing strength of these clays compared...... with the other adsorbents and to low availability of the mobile trace metals in the system. Correlation between trace metals and clay minerals may therefore be used as an indicator in environmental assessment. Fine grain fractions of the sediment increased markedly after salt marsh invasion in about 1931......To understand the behavior of trace metals in the salt marsh at Skallingen, Danish Wadden Sea, we investigated a profile from surface to 25 cm depth of the salt marsh sediment, focusing primarily on clay mineralogy and grain size distribution of the sediments and their relationship with trace...

  2. Ball clay

    Science.gov (United States)

    Virta, Robert L.

    2010-01-01

    The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

  3. Clay Play

    Science.gov (United States)

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  4. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global ball clay mining industry, particularly in the U.S., as of June 2011. It cites several firms that are involved in ball clay mining in the U.S., including HC Spins Clay Co. Inc., the Imerys Group and Old Hickory Clay Co. Among the products made from ball clay are ceramic tiles, sanitaryware, as well as fillers, extenders and binders.

  5. Suisun Marsh Primary Management Area

    Data.gov (United States)

    California Department of Resources — Suisun Marsh or the 'Marsh' means tidal marsh, water-covered areas, diked-off wetlands, seasonal marshes, lowland grasslands, upland grasslands, and cultivated...

  6. Suisun Marsh Secondary Management Area

    Data.gov (United States)

    California Department of Resources — Suisun Marsh or the 'Marsh' means tidal marsh, water-covered areas, diked-off wetlands, seasonal marshes, lowland grasslands, upland grasslands, and cultivated lands...

  7. Clay Houses

    Science.gov (United States)

    Pedro, Cathy

    2011-01-01

    In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

  8. Comparison of wetland structural characteristics between created and natural salt marshes in southwest Louisiana, USA

    Science.gov (United States)

    Edwards, K.R.; Proffitt, C.E.

    2003-01-01

    The use of dredge material is a well-known technique for creating or restoring salt marshes that is expected to become more common along the Gulf of Mexico coast in the future. However, the effectiveness of this restoration method is still questioned. Wetland structural characteristics were compared between four created and three natural salt marshes in southwest Louisiana, USA. The created marshes, formed by the pumping of dredge material into formerly open water areas, represent a chronosequence, ranging in age from 3 to 19 years. Vegetation and soil structural factors were compared to determine whether the created marshes become more similar over time to the natural salt marshes. Vegetation surveys were conducted in 1997, 2000, and 2002 using the line-intercept technique. Site elevations were measured in 2000. Organic matter (OM) was measured in 1996 and 2002, while bulk density and soil particle-size distribution were determined in 2002 only. The natural marshes were dominated by Spartina alterniflora, as were the oldest created marshes; these marshes had the lowest mean site elevations ( 35 cm NGVD) and became dominated by high marsh (S. patens, Distichlis spicata) and shrub (Baccharis halimifolia, Iva frutescens) species. The higher elevation marsh seems to be following a different plant successional trajectory than the other marshes, indicating a relationship between marsh elevation and species composition. The soils in both the created and natural marshes contain high levels of clays (30-65 %), with sand comprising < 1 % of the soil distribution. OM was significantly greater and bulk density significantly lower in two of the natural marshes when compared to the created marshes. The oldest created marsh had significantly greater OM than the younger created marshes, but it may still take several decades before equivalency is reached with the natural marshes. Vegetation structural characteristics in the created marshes take only a few years to become similar

  9. Salt marsh stability modelled in relation to sea level rise

    DEFF Research Database (Denmark)

    Bartholdy, Jesper; Bartholdy, Anders; Kroon, Aart

    2010-01-01

    Accretion on a natural backbarrier salt marsh was modeled as a function of high tide level, initial salt marsh level and distance to the source. Calibration of the model was based on up to ca 80 year old marker horizons, supplemented by 210Pb/137Cs datings and subsequent measurements of clay...... rise, the marsh at the specific location will eventually drown, whereas - with a sea level rise below this level – it will grow towards the top of the rising tidal frame. The short term variation of salt marsh accretion was found to correlate well with variations in the North Atlantic Oscillation...... - relatively quickly grow above the level of the highest astronomical tide, whereas this - in practice - will never happen for the latter....

  10. Freshwater Marsh. Habitat Pac.

    Science.gov (United States)

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    The materials in this educational packet are designed for use with students in grades 4 through 7. They consist of an overview, three lesson plans and student data sheets, and a poster. The overview describes how the freshwater marsh is an important natural resource for plant, animal, and human populations and how the destruction of marshes causes…

  11. Salt marsh stability modelled in relation to sea level rise

    DEFF Research Database (Denmark)

    Bartholdy, Jesper; Bartholdy, Anders; Kroon, Aart

    2010-01-01

    Accretion on a natural backbarrier salt marsh was modeled as a function of high tide level, initial salt marsh level and distance to the source. Calibration of the model was based on up to ca 80 year old marker horizons, supplemented by 210Pb/137Cs datings and subsequent measurements of clay...... thickness. Autocompaction was incorporated in the model, and shown to play a major role for the translation of accretion rates measured as length per unit time to accumulation rates measured as mass per area per unit time. This is important, even for shallow salt marsh deposits for which it is demonstrated...... that mass depth down core can be directly related to the bulk dry density of the surface layer by means of a logarithmic function. The results allow for an evaluation of the use of marker horizons in the topmost layers and show that it is important to know the level of the marker in relation to the salt...

  12. Carpinteria Salt Marsh Habitat Polygons

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — We identified five common habitat types in Carpinteria Salt Marsh: channels, pans (flats), marsh, salt flat and upland. We then drew polygons around each habitat...

  13. Salt marsh stability modelled in relation to sea level rise

    Science.gov (United States)

    Bartholdy, Jesper; Bartholdy, Anders T.; Kroon, Aart

    2010-05-01

    Accretion on a natural backbarrier salt marsh was modeled as a function of high tide level, initial salt marsh level and distance to the source. Calibration of the model was based on up to ca 80 year old marker horizons, supplemented by 210Pb/137Cs datings and subsequent measurements of clay thickness. Autocompaction was incorporated in the model, and shown to play a major role for the translation of accretion rates measured as length per unit time to accumulation rates measured as mass per area per unit time. This is important, even for shallow salt marsh deposits for which it is demonstrated that mass depth down core can be directly related to the bulk dry density of the surface layer by means of a logarithmic function. The results allow for an evaluation of the use of marker horizons in the topmost layers and show that it is important to know the level of the marker in relation to the salt marsh base. In general, deeper located markers will indicate successively smaller accretion rates with the same sediment input. Thus, stability analysis made on the basis of newly established marker horizons will be biased and indicate salt marsh stabilities far above the correct level. Running the model with a constant sea level revealed that balance between the inner and the outer salt marsh deposition can not be achieved within a reasonable time scale. Likewise it is shown that only one specific sea level rise provides equilibrium for a given location on the salt marsh. With a higher sea level rise, the marsh at the specific location will eventually drown, whereas - with a sea level rise below this level - it will grow towards the top of the rising tidal frame. The short term variation of salt marsh accretion was found to correlate well with variations in the North Atlantic Oscillation - the NAO winter index. Comparisons between the geomorphological development of wind tide affected salt marshes, like those present on the Danish North Sea coasts, and primary astronomically

  14. Sanctuary In the Marsh

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Of the world’s 15 species of crane, six live in Zhalong National Nature Reserve, a 210,000-hectare wetland in China. Consisting of many small lakes, swamps and sprawling meadows, the wetland is the most intact, pristine and vast marsh in the north. The wetland is an ideal habitat for

  15. Biosphere 2's Marsh Biome

    Science.gov (United States)

    Molnar, Jennifer; Goodridge, Kelven

    1997-01-01

    The Marsh Biome, which was modeled after the mangroves and marshes of southwest Florida, has an area of 441.2 sq m separated into three hydrologically independent sections: the Freshwater, Oligohaline and Salt Marshes. The divisions are made based on their salinity (approximately 0, 4, and 34 ppt. respectively), but they also contain different biological communities. The Freshwater and Oligohaline Marshes are mostly filled with various grasses and several trees, while the Salt Marsh houses regions of red, black, and white mangroves (Rhizophora mangle, Avicennia germinans, and Languncularia racemosa respectively). Overall, there are an estimated 80 species of plants within the biome. Water in the Salt Marsh follows a meandering stream from the algal turf scrubbers (apparatuses that clean the water of its nutrients and heavy metals while increasing dissolved oxygen levels) which have an outlet in the Salt Marsh section near sites 4 and 5 to the Fringing Red Mangrove section. The sections of the Salt Marsh are separated by walls of concrete with openings to allow the stream to flow through. Throughout this study, conducted through the months of June and July, many conditions within the biome remained fairly constant. The temperature was within a degree or two of 25 C, mostly depending on whether the sample site was in direct sunlight or shaded. The pH throughout the Salt Marsh was 8.0 +/- 0.2, and the lower salinity waters only dropped below this soon after rains. The water rdepth and dissolved oxygen varied, however, between sites.

  16. Biosphere 2's Marsh Biome

    Science.gov (United States)

    Molnar, Jennifer; Goodridge, Kelven

    1997-01-01

    The Marsh Biome, which was modeled after the mangroves and marshes of southwest Florida, has an area of 441.2 sq m separated into three hydrologically independent sections: the Freshwater, Oligohaline and Salt Marshes. The divisions are made based on their salinity (approximately 0, 4, and 34 ppt. respectively), but they also contain different biological communities. The Freshwater and Oligohaline Marshes are mostly filled with various grasses and several trees, while the Salt Marsh houses regions of red, black, and white mangroves (Rhizophora mangle, Avicennia germinans, and Languncularia racemosa respectively). Overall, there are an estimated 80 species of plants within the biome. Water in the Salt Marsh follows a meandering stream from the algal turf scrubbers (apparatuses that clean the water of its nutrients and heavy metals while increasing dissolved oxygen levels) which have an outlet in the Salt Marsh section near sites 4 and 5 to the Fringing Red Mangrove section. The sections of the Salt Marsh are separated by walls of concrete with openings to allow the stream to flow through. Throughout this study, conducted through the months of June and July, many conditions within the biome remained fairly constant. The temperature was within a degree or two of 25 C, mostly depending on whether the sample site was in direct sunlight or shaded. The pH throughout the Salt Marsh was 8.0 +/- 0.2, and the lower salinity waters only dropped below this soon after rains. The water rdepth and dissolved oxygen varied, however, between sites.

  17. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES

    Science.gov (United States)

    CLAY AND CLAY-SUPPORTED REAGENTS HAVE BEEN USED EXTENSIVELY FOR SYNTHETIC ORGANIC TRANSFORMATIONS. THIS OVERVIEW DESCRIBES THE SALIENT STRUCTURAL PROPERTIES OF VARIOUS CLAY MATERIALS AND EXTENDS THE DISCUSSION TO PILLARED CLAYS AND REAGENTS SUPPORTED ON CLAY MATERIALS. A VARIET...

  18. Nutrient Cycling in Piermont Marsh

    Science.gov (United States)

    Reyes, N.; Gribbin, S.; Newton, R.; Diaz, K.; Laporte, N.; Trivino, G.; Ortega, J.; McKee, K.; Sambrotto, R.

    2011-12-01

    We investigate the cycling of nutrients through a brackish tidal wetland about 40 km north of Manhattan in the Hudson River estuary. As part of a long-term ecological study of Piermont Marsh, a NOAA reference wetland managed by the NY State DEC, we are measuring dissolved inorganic nutrients on the Marsh surface and its drainage channels. The marsh occupies 400 acres along the southwest corner of Haverstraw Bay with approximately 2 km frontage to the estuary. It is supplied with nutrient-rich water and drained primarily along several tidal creeks and the hundreds of rivulets that feed them. During most tidal cycles the silty berm bounding the marsh is not topped. Human influence in the marsh's surrounding area has had profound effects, one of the most fundamental of which has been the shift from native grass species, predominantly Spartina alterniflora, to an invasive genotype of common reed, Phragmites australis. Along with this shift there have been changes in the root bed, the effective marsh interior and berm heights, the hydroperiod and, as a result, the ability of the marsh to be utilized by various types of Hudson estuary fish. The vegetative shift is believed to be anthropogenic, but the connection is not well understood, and it is not known what role biogeochemical perturbations are playing. We present two field seasons of nitrate, phosphate and silicate measurements from Sparkill Creek, a freshwater stream draining the surrounding highlands constitutes the northern boundary, two tidally driven creeks transect the Marsh from West to East: the Crumkill and an unnamed creek we have dubbed the "Tidal", Ludlow Ditch, a no-longer-maintained drainage channel grading gently from the northern part of the marsh to the South terminates in a wide tidal outlet that is its southern boundary. Net tidal cycle fluxes and fluxes resulting from runoff events are presented. Deviations from Redfield ratios and limiting nutrients are analyzed. Piermont Marsh data is compared

  19. Common clay and shale

    Science.gov (United States)

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global common clay and shale industry, particularly in the U.S. It claims that common clay and shale is mainly used in the manufacture of heavy clay products like brick, flue tile and sewer pipe. The main producing states in the U.S. include North Carolina, New York and Oklahoma. Among the firms that manufacture clay and shale-based products are Mid America Brick & Structural Clay Products LLC and Boral USA.

  20. Shore Stabilization with Salt Marsh Vegetation.

    Science.gov (United States)

    1983-01-01

    Poaceae), sedge family ( Cyperacea ), and rush family (Junoaowa.) commonly form coastal marshes. Coastal marshes occur naturally in the intertidal zone...Maine) ............................... 18 4 Pacific cordgrass marsh (San Francisco, California) .................. 19 5 Lyngbye’s sedge marsh (Oregon...26 Harvesting Pacific cordgrase seed..................... 59 27 Ordgrase-auasel plugs of Pacific cordgrassoo.. 9 . ..... . , 61 28 Lyngbye’a sedge

  1. Modified clay sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.; Srinivasan, K.R.

    1990-04-10

    This patent describes a clay-based sorbent. It comprises a clay having an external surface and lamellar layers; and cationic surfactant ions having a hydrocarbon portion and a cationic head portion, the cationic surfactant ions being irreversibly bound to the external surface by the hydrocarbon portion. This patent also describes cetylpyridinium-aluminum hydroxy-montmorillonite; the clay-based sorbent wherein the clay is a non-expandable clay; and the clay-based sorbent wherein the cationic surfactant ions are selected from the group consisting of ionized cetylpyridinium chloride and cetylakonium chloride.

  2. Marsh and Water Management Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The three freshwater impoundments--North, Bill Forward, and Stage Island Pools were constructed by diking off salt marsh on the west side of the barrier island in...

  3. Louisiana Marsh Management Plan 1995

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We sampled experimental research areas in the Barataria Basin of Louisiana during March and May, 1995, to examine the effects of structural marsh management on...

  4. Ecogeomorphic Heterogeneity Sculpts Salt Marshes

    Science.gov (United States)

    Leonardi, N.; Fagherazzi, S.

    2014-12-01

    We present cellular automata simulations and high-resolution field measurements of five sites along the United States Atlantic Coast, to investigate the erosion of marsh boundaries by wave action. For several years, we tracked marsh contours of three sites in Plum Island Sound and two sites in the Virginia Coastal Reserve using a Real-Time-Kinematic GPS, and measurements were collected up to 20 cm apart. The cellular automata model consists of a 2D square lattice, whose elements have randomly distributed resistance. Randomly distributed resistance values are meant to take into account the variety of biological and geomorphologic processes affecting each portion of the marsh. Among others, seepage erosion, crab burrowing, vegetation and sediment cohesion make difficult to predict which portion of the marsh will collapse first. In case of high wave power, erosion proceeds uniformly because each marsh portion has similar resistance if compared to the main external driver. On the contrary, when wind waves are weak and the local marsh resistance is strong, jagged marsh boundaries form. From a statistical viewpoint, the system behaves differently for the two extreme conditions of very low and very high wave power. The frequency magnitude distribution of erosion events approaches a Gaussian distribution in case of high wave power. In case of low wave power, the frequency magnitude distribution is characterized by a long-tailed power-law distribution. For the low wave power case, a long time is required to erode very resistant cells. However, once the most resistant cells are eliminated, several weak sites remain exposed and can be rapidly removed, with consequent generation of large-scale failures. Field data confirm model results, and show the passage from a logarithmic frequency magnitude distribution of erosion events to a Gaussian distribution for increasing wave power exposure. The logarithmic frequency magnitude distribution suggests the emergence of a critical

  5. Ten-Year Growth of Five Planted Hardwood Species Mechanical Weed Control on Sharkey Clay Soil

    Science.gov (United States)

    Roger M. Krinard; Harvey E. Kennedy

    1983-01-01

    Five hardwood species planted on Sharkey clay soil showed little practical difference in growth whether plots were mowed or diskedfor weed control in years 6 to 10, although disking had given better growth in the first 5 years. After 10 years, cottonwood (Populus deltoides Bartr. ex Marsh.) stem volume was at least three times greater than other species. Changes in...

  6. Biota - 2011 Vegetation Inventory - Marsh Lake, MN

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — 2011 Vegetation Classification for Marsh Lake, MN Vegetation Project Report, OMBIL Environmental Stewardship - Level 1 Inventory. Marsh Lake is located on the...

  7. Galveston Bay Marsh Terracing 2001-2002

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Marsh terracing is used to restore coastal wetlands by converting shallow nonvegetated bottom to intertidal marsh. Terraces are constructed from excavated bottom...

  8. Depth-distribution patterns and control of soil organic carbon in coastal salt marshes with different plant covers

    Science.gov (United States)

    Bai, Junhong; Zhang, Guangliang; Zhao, Qingqing; Lu, Qiongqiong; Jia, Jia; Cui, Baoshan; Liu, Xinhui

    2016-01-01

    This study was carried out in three kinds of salt marshes according to the vegetation covers, including Phragmites australis salt marsh (PSM), Suaeda salus salt marsh (SSM) and Tamarix chinensis-Suaeda salus salt marsh (TSSM). We applied allometric function, exponential function and logistic function to model the depth distribution of the SOCv and SOCc for each salt marsh, respectively. The results showed that the exponential function fits the depth distribution of the SOCv more well than other two functions. The SOCc can be fitted very well by all three functions for three salt marsh (Adj. R2 > 0.99), of which the allometric function was the best one. The mean topsoil concentration factors (TCFs) of three salt marshes were beyond 0.1, which means the SOC enrichment in surface soils due to plant cycling, but TCFs in PSM were significantly higher than those in SSM (P soils. The results of general linear model (GLM) suggested that four soil properties (soil water content, pH, soil salt content and silt+clay) and their interactive effects explained about 80% of the total variation of SOC stock in the top 20 cm soils and the 20–100 cm soil layers. PMID:27708421

  9. Depth-distribution patterns and control of soil organic carbon in coastal salt marshes with different plant covers

    Science.gov (United States)

    Bai, Junhong; Zhang, Guangliang; Zhao, Qingqing; Lu, Qiongqiong; Jia, Jia; Cui, Baoshan; Liu, Xinhui

    2016-10-01

    This study was carried out in three kinds of salt marshes according to the vegetation covers, including Phragmites australis salt marsh (PSM), Suaeda salus salt marsh (SSM) and Tamarix chinensis-Suaeda salus salt marsh (TSSM). We applied allometric function, exponential function and logistic function to model the depth distribution of the SOCv and SOCc for each salt marsh, respectively. The results showed that the exponential function fits the depth distribution of the SOCv more well than other two functions. The SOCc can be fitted very well by all three functions for three salt marsh (Adj. R2 > 0.99), of which the allometric function was the best one. The mean topsoil concentration factors (TCFs) of three salt marshes were beyond 0.1, which means the SOC enrichment in surface soils due to plant cycling, but TCFs in PSM were significantly higher than those in SSM (P < 0.05). Nearly 30% of SOC was concentrated in the top 20 cm soils. The results of general linear model (GLM) suggested that four soil properties (soil water content, pH, soil salt content and silt+clay) and their interactive effects explained about 80% of the total variation of SOC stock in the top 20 cm soils and the 20–100 cm soil layers.

  10. Thermostability of montmorillonitic clays

    OpenAIRE

    Petr Jelínek; Dobosz, Stanisław M.; Jaroslav Beňo

    2014-01-01

    Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC), the cis- is...

  11. Methane emission from freshwater marshes

    NARCIS (Netherlands)

    Nat, Frans-Jaco Willy Anthony van der

    2000-01-01

    This thesis describes the results of a four-year study into the CH4 cycle of freshwater marshes dominated by reed and bulrush. This research was conducted in the framework of the research theme carbon and nutrient dynamics in vegetated littoral systems of the department of Littoral Vegetation of t

  12. Combined effects of tides, evaporation and rainfall on the soil conditions in an intertidal creek-marsh system

    Science.gov (United States)

    Xin, Pei; Zhou, Tingzhang; Lu, Chunhui; Shen, Chengji; Zhang, Chenming; D'Alpaos, Andrea; Li, Ling

    2017-05-01

    Salt marshes, distributed globally at the land-ocean interface, are a highly productive eco-system with valuable ecological functions. While salt marshes are affected by various eco-geo-hydrological processes and factors, soil moisture and salinity affect plant growth and play a key role in determining the structure and functions of the marsh ecosystem. To examine the variations of both soil parameters, we simulated pore-water flow and salt transport in a creek-marsh system subjected to spring-neap tides, evaporation and rainfall. The results demonstrated that within a sandy-loam marsh, the tide-induced pore-water circulation averted salt build-up due to evaporation in the near-creek area. In the marsh interior where the horizontal drainage was weak, density-driven flow was responsible for dissipating salt accumulation in the shallow soil layer. In the sandy-loam marsh, the combined influences of spring-neap tides, rainfall and evaporation led to the formation of three characteristic zones, c.f., a near-creek zone with low soil water saturation (i.e., well-aerated) and low pore-water salinity as affected by the semi-diurnal spring tides, a less well-aerated zone with increased salinity where drainage occurred during the neap tides, and an interior zone where evaporation and rainfall infiltration regulated the soil conditions. These characteristics, however, varied with the soil type. In low-permeability silt-loam and clay-loam marshes, the tide-induced drainage weakened and the soil conditions over a large area became dominated by evaporation and rainfall. Sea level rise was found to worsen the soil aeration condition but inhibit salt accumulation due to evaporation. These findings shed lights on the soil conditions underpinned by various hydrogeological processes, and have important implications for further investigations on marsh plant growth and ecosystem functions.

  13. Sedimentary facies and paleoenvironmental interpretation of a Holocene marsh in the Gironde Estuary in France

    Institute of Scientific and Technical Information of China (English)

    WANG Jianhua; MASSE Laurent; TASTET Jean-Pierre

    2006-01-01

    The Monards Marsh is located on the northeastern bank of the Gironde Estuary in France. Lithological, sedimentological and micropalaeontological investigations were made on four cores to determine the evolution of Holocene sedimentary environments and processes in this area over the last 6 000 a. Three main lithological facies are distinguished from bottom to top: (1) grey laminated silty-sandy clay; (2) homogeneous dark grey silty clay; and (3) compact silty clay. About 26 benthic foraminifera species are identified and divided into six groups according to their ecological characteristics. In association with lithology, sedimentary structures and grainulometry, the distribution of foraminifera group is used to define external slikke, internal slikke, external schorre, internal schorre, and continental marsh facies. Combined with 14C(AMS) dating, these data indicate four successive paleoenvironments in the Monards Marsh: (1) Holocene transgression resulted in the development of a basal schorre facies overlying fluvial deposits that transformed to slikke facies sedimentation; the transgression maximum occurred around 5 600 to 5 400 a BP and was inferred to be associated with the last phase of the rapid Holocene sea-level rise; (2) post-trangressive maximum sedimentation resulted in a regressive sequence of deposits prograding towards the estuary, corresponding to the stabilisation of sea level after 5 400 a BP; (3) a slight positive tendency in the sea level around 2 800 a BP recorded in the central part of the marsh; and (4) the wetland to a continental marsh environment. The sequential pattern for the evolution of wetlands in this estuarine area during the Holocene is fluvial facies-blackish schorre facies-slikke facies-blackish schorre facies-continental marsh facies. Characteristics of sedimentary facies distribution and evolution reveal that the development of Holocene salt marsh in this area was controlled by the sea-level change and tidal range. The

  14. Clay Portrait Boxes

    Science.gov (United States)

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  15. Columns in Clay

    Science.gov (United States)

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  16. Clay Mineral: Radiological Characterization

    Science.gov (United States)

    Cotomácio, J. G.; Silva, P. S. C.; Mazzilli, B. P.

    2008-08-01

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and 40K in these clay minerals. The objective of this work is to determine the concentrations of 238U, 232Th, 226Ra, 228Ra, 210Pb and 40K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of 238U and 232Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for 226Ra, 228Ra, 210Pb and 40K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906±340 Bq kg-1 for 40K, 40±9 Bq kg-1 for 226Ra, 75±9 Bq kg-1 for 228Ra, 197±38 Bq kg-1 for 210Pb, 51±26 Bq kg-1 for 238U and 55±24 Bq kg-1 for 232Th, considering both kinds of clay.

  17. Siderophore sorption to clays.

    Science.gov (United States)

    Maurice, Patricia A; Haack, Elizabeth A; Mishra, Bhoopesh

    2009-08-01

    Siderophores are low molecular weight organic ligands exuded by some aerobic organisms and plants to acquire Fe under Fe-limited conditions. The hydroxamate siderophores may sorb to aluminosilicate clays through a variety of mechanisms depending upon the nature of the clay and of the siderophore along with solution conditions such as pH, ionic strength, and presence of metal cations. They may also affect metal binding to clays. Here, we review previous studies of siderophore sorption to aluminosilicate clays; briefly discuss how the techniques of X-ray diffractometry, Fourier-transform infrared spectroscopy, and X-ray absorption spectroscopy may be applied to such studies; review effects of siderophores on metal sorption to clays; and highlight some areas for future research.

  18. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Big Branch Marsh NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Model SummaryChanges in tidal marsh area and habitat type in response to sea-level rise were modeled using the Sea Level Affecting Marshes Model (SLAMM 6) that...

  19. Clay and concrete brick

    CSIR Research Space (South Africa)

    Dlamini, MN

    2014-03-01

    Full Text Available are manufactured from raw clay as their primary ingredient. However concrete brick has also become a favoured material in recent times. This review will adumbrate the impact of these building materials on energy use and the environment....

  20. Clay goes patchy

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    2011-01-01

    Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

  1. Carpinteria salt marsh habitat polygons

    Science.gov (United States)

    Lafferty, Kevin D.; Dunham, Eleca J.; Mancini, Frank T.; Stewart, Tara E.; Hechinger, Ryan F.

    2017-01-01

    We identified five common habitat types in Carpinteria Salt Marsh: channels, pans (flats), marsh, salt flat and upland.  We then drew polygons around each habitat type identified from a registered and orthorectified aerial photograph and created a GIS shapefile. Polygons were ground-truthed in the field. From these habitat polygons, one can use GIS applications to estimate the area of each habitat type in this estuary. These data support the following publications: Kuris, Armand M., et al. "Ecosystem energetic implications of parasite and free-living biomass in three estuaries." Nature 454.7203 (2008): 515-518.Hechinger, Ryan F., Kevin D. Lafferty, Andy P. Dobson, James H. Brown, and Armand M. Kuris. "A common scaling rule for abundance, energetics, and production of parasitic and free-living species." Science 333, no. 6041 (2011): 445-448.Hechinger, Ryan F., Kevin D. Lafferty, John P. McLaughlin, Brian L. Fredensborg, Todd C. Huspeni, Julio Lorda, Parwant K. Sandhu et al. "Food webs including parasites, biomass, body sizes, and life stages for three California/Baja California estuaries." Ecology 92, no. 3 (2011): 791-791.Buck, J.C., Hechinger, R.F., Wood, A.C., Stewart, T.E., Kuris, A.M., and Lafferty, K.D., "Host density increases parasite recruitment but decreases host risk in a snail-trematode system." Manuscript submitted for publication. Lafferty, K.D., Stewart, T.E., and Hechinger, R.F. (in press). Bird distribution surveys at Carpinteria Salt Marsh, California USA, January 2012 to March 2013: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7F47M95. 

  2. Magnificent Clay Murals

    Science.gov (United States)

    Kirker, Sara Schmickle

    2007-01-01

    Each August, third grade artists at Apple Glen Elementary in Bentonville, Arkansas, start the school year planning, creating, and exhibiting a clay relief mural. These mural projects have helped students to acquire not only art knowledge and techniques, but an even more important kind of knowledge: what it means to plan and successfully complete a…

  3. Rattles of Clay.

    Science.gov (United States)

    Banning, Donna

    1983-01-01

    Using the rattles of Native American cultures as inspiration, students used pinching, coiling, and slab and molding techniques to form the bodies of rattles and clay pellets for sound. Surface decoration included glazed and unglazed areas as well as added handles, feathers, and leather. (IS)

  4. Physical Properties of Latvian Clays

    OpenAIRE

    2012-01-01

    Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

  5. Marsh canopy leaf area and orientation calculated for improved marsh structure mapping

    Science.gov (United States)

    Ramsey III, Elijah W.; Rangoonwala, Amina; Jones, Cathleen E.; Bannister, Terri

    2015-01-01

    An approach is presented for producing the spatiotemporal estimation of leaf area index (LAI) of a highly heterogeneous coastal marsh without reliance on user estimates of marsh leaf-stem orientation. The canopy LAI profile derivation used three years of field measured photosynthetically active radiation (PAR) vertical profiles at seven S. alterniflora marsh sites and iterative transform of those PAR attenuation profiles to best-fit light extinction coefficients (KM). KM sun zenith dependency was removed obtaining the leaf angle distribution (LAD) representing the average marsh orientation and the LAD used to calculate the LAI canopy profile. LAI and LAD reproduced measured PAR profiles with 99% accuracy and corresponded to field documented structures. LAI and LAD better reflect marsh structure and results substantiate the need to account for marsh orientation. The structure indexes are directly amenable to remote sensing spatiotemporal mapping and offer a more meaningful representation of wetland systems promoting biophysical function understanding.

  6. Tidal Marsh Vegetation of China Camp, San Pablo Bay, California

    OpenAIRE

    Baye, Peter R.

    2012-01-01

    China Camp (Marin County, California) preserves extensive relict stands of salt marsh vegetation developed on a prehistoric salt marsh platform with a complex sinuous tidal creek network. The low salt marsh along tidal creeks supports extensive native stands of Pacific cordgrass (Spartina foliosa). The outer salt marsh accreted following hydraulic gold mining sedimentation. It consists of a wave-scarped pickleweed-dominated (Sarcocornia pacifica) high salt marsh terrace with a broad fringing ...

  7. Clay Animals and Their Habitats

    Science.gov (United States)

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  8. Marsh's Library and the Irish Catholic tradition

    OpenAIRE

    O'Connor, Thomas

    2004-01-01

    Narcissus Marsh (1638-1713), the founder of the first public library in Ireland, was of what Patrick Comerford, Catholic bishop of Waterford (1629-52) called 'the new fetch'd in religion'.1 So were Edward Stillingfleet (1635-1699), Elias Bouhéreau (1642-1719) and John Stearne (1660-1745), whose collections, with Marsh's own, form the core of Marsh's Library. These four collected material, in manuscript and in print, at a time when confessional differences, in Ireland, England and Europe, were...

  9. Sediment geochemistry of Corte Madera Marsh, San Francisco Bay, California: have local inputs changed, 1830-2010?

    Science.gov (United States)

    Takesue, Renee K.; Jaffe, Bruce E.

    2013-01-01

    Large perturbations since the mid-1800s to the supply and source of sediment entering San Francisco Bay have disturbed natural processes for more than 150 years. Only recently have sediment inputs through the Sacramento-San Joaquin Delta (the Delta) decreased to what might be considered pre-disturbance levels. Declining sediment inputs to San Francisco Bay raise concern about continued tidal marsh accretion, particularly if sea level rise accelerates in the future. The aim of this study is to explore whether the relative amount of local-watershed sediment accumulating in a tidal marsh has changed as sediment supply from the Sacramento-San Joaquin Rivers has decreased. To address this question, sediment geochemical indicators, or signatures, in the fine fraction (silt and clay) of Sacramento River, San Joaquin River, San Francisco Bay, and Corte Madera Creek sediment were identified and applied in sediment recovered from Corte Madera Marsh, one of the few remaining natural marshes in San Francisco Bay. Total major, minor, trace, and rare earth element (REE) contents of fine sediment were determined by inductively coupled plasma mass and atomic emission spectroscopy. Fine sediment from potential source areas had the following geochemical signatures: Sacramento River sediment downstream of the confluence of the American River was characterized by enrichments in chromium, zirconium, and heavy REE; San Joaquin River sediment at Vernalis and Lathrop was characterized by enrichments in thorium and total REE content; Corte Madera Creek sediment had elevated nickel contents; and the composition of San Francisco Bay mud proximal to Corte Madera Marsh was intermediate between these sources. Most sediment geochemical signatures were relatively invariant for more than 150 years, suggesting that the composition of fine sediment in Corte Madera Marsh is not very sensitive to changes in the magnitude, timing, or source of sediment entering San Francisco Bay through the Delta. Nor

  10. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

  11. Reversibility of soil forming clay mineral reactions induced by plant - clay interactions

    Science.gov (United States)

    Barré, P.; Velde, B.

    2012-04-01

    Recent data based upon observations of field experiments and laboratory experiments suggest that changes in phyllosilicate mineralogy, as seen by X-ray diffraction analysis, which is induced by plant action can be reversed in relatively short periods of time. Changes from diagenetic or metamorphic mineral structures (illite and chlorite) to those found in soils (mixed layered minerals in the smectite, hydroxy-interlayer mineral and illites) observed in Delaware Bay salt marsh sediments in periods of tens of years and observed under different biologic (mycorhize) actions in coniferous forests in the soil environment can be found to be reversed under other natural conditions. Reversal of this process (chloritisation of smectitic minerals in soils) has been observed in natural situations over a period of just 14 years under sequoia gigantia. Formation of smectite minerals from illite (potassic mica-like minerals) has been observed to occur under intensive agriculture conditions over periods of 80 years or so under intensive zea mais production. Laboratory experiments using rye grass show that this same process can be accomplished to a somewhat lesser extent after one growing season. However experiments using alfalfa for 30 year growing periods show that much of the illite content of a soil can be reconstituted or even increased. Observations on experiments using zea mais under various fertilizer and mycorhize treatments indicate that within a single growing season potassium can be extracted from the clay (illite layers) but at the end of the season the potassium can be restored to the clay structures and more replaced that extracted. Hence it is clear that the change in clay mineralogy normally considered to be irreversible, illite to smectite or chlorite to smectite observed in soils, is a reversible process where plant systems control the soil chemistry and the soil mineralogy. The changes in clay mineralogy concern mostly the chemical composition of the interlayer

  12. Vegetation - Suisun Marsh 1999 [ds160

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  13. Salt marsh construction costs and shrimp production

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Continuing wetland loss in Galveston Bay, Texas (USA) has led to the development of various salt marsh restoration projects. These constructed wetlands often attempt...

  14. Marsh Bird Monitoring Activities in Vermont 2000

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — As part of ongoing research into the status of Vermont's marsh birds, a statewide census of the black tern nesting population was undertaken again in the year 2000....

  15. Oregon Salt Marshes: How Blue are They?

    Science.gov (United States)

    Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...

  16. Evaluation of chemical control of marsh cane

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report discusses the feasibility of effective spraying of marsh cane (Phragmites communus) with a plant herbicide Amino Triazole (Weedazol) at Fish Springs...

  17. Vegetation - Suisun Marsh 2003 [ds162

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  18. F&G Street Marsh Contaminants Investigation

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — F&G Street Marsh, located in San Diego Bay National Wildlife Refuge, Chula Vista, San Diego, California, is a tidally influenced wetland providing habitat for...

  19. Vegetation Composition and Marsh Surface Elevation, 2015

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data table contains plant composition and marsh surface elevation data for 64 plots where Salicornia pacifica litter was buried at 7 sites in 2015. These data...

  20. Clay at Nili Fossae

    Science.gov (United States)

    2006-01-01

    This image of the Nili Fossae region of Mars was compiled from separate images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the High-Resolution Imaging Science Experiment (HiRISE), two instruments on NASA's Mars Reconnaissance Orbiter. The images were taken at 0730 UTC (2:30 a.m. EDT) on Oct. 4, 2006, near 20.4 degrees north latitude, 78.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36 to 3.92 micrometers, and shows features as small as 18 meters (60 feet) across. HiRISE's image was taken in three colors, but its much higher resolution shows features as small as 30 centimeters (1 foot) across. CRISM's sister instrument on the Mars Express spacecraft, OMEGA, discovered that some of the most ancient regions of Mars are rich in clay minerals, formed when water altered the planet's volcanic rocks. From the OMEGA data it was unclear whether the clays formed at the surface during Mars' earliest history of if they formed at depth and were later exposed by impact craters or erosion of the overlying rocks. Clays are an indicator of wet, benign environments possibly suitable for biological processes, making Nili Fossae and comparable regions important targets for both CRISM and HiRISE. In this visualization of the combined data from the two instruments, the CRISM data were used to calculate the strengths of spectral absorption bands due to minerals present in the scene. The two major minerals detected by the instrument are olivine, a mineral characteristic of primitive igneous rocks, and clay. Areas rich in olivine are shown in red, and minerals rich in clay are shown in green. The derived colors were then overlayed on the HiRISE image. The area where the CRISM and HiRISE data overlap is shown at the upper left, and is about 5 kilometers (3 miles) across. The three boxes outlined in blue are enlarged to show how the different minerals in the scene match up with different landforms. In the image at the upper right

  1. Thermostability of montmorillonitic clays

    Directory of Open Access Journals (Sweden)

    Petr Jelínek

    2014-05-01

    Full Text Available Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC, the cis- isomerism of bentonite is expected, while two peaks of de-hydroxylation (about 550 and 850 ºC are expected in the trans- one. In this overview, the bentonite structure, the water – bentonite interaction and the swelling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as well as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.

  2. Thermostability of montmorillonitic clays

    Institute of Scientific and Technical Information of China (English)

    Petr Jelnek; Stanisaw M.Dobosz; Jaroslav Beo; Katarzyna Major-Gabry

    2014-01-01

    Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC), thecis- isomerism of bentonite is expected, while two peaks of de-hydroxylation (about 550 and 850 ºC) are expected in thetrans- one. In this overview, the bentonite structure, the water - bentonite interaction and the sweling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as wel as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.

  3. A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

    Directory of Open Access Journals (Sweden)

    Graham Edward

    2006-04-01

    Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

  4. Black Tern Population Survey and other Marsh Bird Monitoring Activities in Vermont 2004

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report looks at marsh bird population trends within the marshes of Vermont, and investigates the effect of water level and marsh vegetation changes on marsh...

  5. Black Tern Population Survey and other Marsh Bird Monitoring Activities in Vermont 2003

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report looks at marsh bird population trends within the marshes of Vermont, and investigates the effect of water level and marsh vegetation changes on marsh...

  6. Black Tern Population Survey and other Marsh Bird Monitoring Activities in Vermont 2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report looks at marsh bird population trends within the marshes of Vermont, and investigates the effect of water level and marsh vegetation changes on marsh...

  7. Trace gas exchanges of marsh-pond-marsh constructed wetlands treating swine wastewater

    Science.gov (United States)

    Marsh-pond-marsh (MPM) constructed wetlands have been used effectively to treat wastewater from swine anaerobic lagoons. However, at high N loading rates, a significant portion of ammonia in the wastewater could be volatilized into the atmosphere. To mitigate ammonia emission, ponds can be covered w...

  8. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater

    Science.gov (United States)

    Marsh-pond-marsh (M-P-M) constructed wetlands have been used to treat wastewater from swine anaerobic lagoons. To mitigate undesired ammonia emission from M-P-M, ponds were covered with floating wetlands (M-FB-M). The pond sections of the M-FB-M were covered with floating wetlands consisted of recyc...

  9. Sea level driven marsh expansion in a coupled model of marsh erosion and migration

    Science.gov (United States)

    Kirwan, Matthew L.; Walters, David C.; Reay, William G.; Carr, Joel A.

    2016-05-01

    Coastal wetlands are among the most valuable ecosystems on Earth, where ecosystem services such as flood protection depend nonlinearly on wetland size and are threatened by sea level rise and coastal development. Here we propose a simple model of marsh migration into adjacent uplands and couple it with existing models of seaward edge erosion and vertical soil accretion to explore how ecosystem connectivity influences marsh size and response to sea level rise. We find that marsh loss is nearly inevitable where topographic and anthropogenic barriers limit migration. Where unconstrained by barriers, however, rates of marsh migration are much more sensitive to accelerated sea level rise than rates of edge erosion. This behavior suggests a counterintuitive, natural tendency for marsh expansion with sea level rise and emphasizes the disparity between coastal response to climate change with and without human intervention.

  10. Marsh Edge Erosion Effects in Coupled Barrier Island-Marsh Systems

    Science.gov (United States)

    Lauzon, R.; Moore, L. J.; Murray, A. B.; Walters, D.; Fagherazzi, S.; Mariotti, G.

    2014-12-01

    While until recently marsh loss was largely thought to be due to an inability for vertical accretion rates to match rates of sea level rise, marsh edge erosion by wind waves is now thought to be the leading cause of marsh loss worldwide. To better understand the response of coastal ecosystems to future changes in sea level and storm intensity, we further develop the coupled barrier-island marsh evolution model GEOMBEST+. We use the relationship between wave height (and therefore energy) and fetch and wind speed to add marsh edge erosion to the model, as well as to provide a more physical formulation for bay bottom erosion. Previous research addressing marshes in isolation from barrier islands (Mariotti and Fagherazzi, 2013) suggests that the existence of a backbarrier marsh is an unstable state, tending to either grow laterally to completely fill an adjacent basin or to erode away completely. Previous results of GEOMBEST+ experiments (Walters et al., in review) suggest that couplings with an adjacent barrier island can add an additional alternate long-lasting state: a narrow marsh supported by sediment influx from overwash. Here we present the results of new GEOMBEST+ model experiments that address how the addition of lateral erosion by wind waves affects the existence and characteristics of the narrow marsh state. Specifically, we seek to address how the frequency and characteristic time and space scales of the narrow march state are affected. Model experiments also explore more broadly the importance of wind wave effects in understanding the coupled dynamics of marsh-barrier island systems.

  11. Salt Marsh Integrity Vegetation Data at Chincoteague National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  12. Salt Marsh Integrity Bird Data at Chincoteague National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  13. Spatially integrative metrics reveal hidden vulnerability of microtidal salt marshes

    Science.gov (United States)

    Ganju, Neil K.; Defne, Zafer; Kirwan, Matthew L.; Fagherazzi, Sergio; D'Alpaos, Andrea; Carniello, Luca

    2017-01-01

    Salt marshes are valued for their ecosystem services, and their vulnerability is typically assessed through biotic and abiotic measurements at individual points on the landscape. However, lateral erosion can lead to rapid marsh loss as marshes build vertically. Marsh sediment budgets represent a spatially integrated measure of competing constructive and destructive forces: a sediment surplus may result in vertical growth and/or lateral expansion, while a sediment deficit may result in drowning and/or lateral contraction. Here we show that sediment budgets of eight microtidal marsh complexes consistently scale with areal unvegetated/vegetated marsh ratios (UVVR) suggesting these metrics are broadly applicable indicators of microtidal marsh vulnerability. All sites are exhibiting a sediment deficit, with half the sites having projected lifespans of less than 350 years at current rates of sea-level rise and sediment availability. These results demonstrate that open-water conversion and sediment deficits are holistic and sensitive indicators of salt marsh vulnerability.

  14. Salt Marsh Integrity Data at Rachel Carson National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  15. Salt Marsh Integrity Data at Moosehorn National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  16. Marsh Soil Responses to Nutrients: Belowground Structural and Organic Properties.

    Science.gov (United States)

    Coastal marsh responses to nutrient enrichment apparently depend upon soil matrix and whether the system is primarily biogenic or minerogenic. Deteriorating organic rich marshes (Jamaica Bay, NY) receiving wastewater effluent had lower belowground biomass, organic matter, and soi...

  17. Astronomical Forcing of Salt Marsh Biogeochemical Cascades

    Science.gov (United States)

    Morris, J. T.; Sundberg, K.

    2008-12-01

    Astronomically forced changes in the hydroperiod of a salt marsh affect the rate of marsh primary production leading to a biogeochemical cascade. For example, salt marsh primary production and biogeochemical cycles in coastal salt marshes are sensitive to the 18.6-year lunar nodal cycle, which alters the tidal amplitude by about 5 cm. For marshes that are perched high in the tidal frame, a relatively small increase in tidal amplitude and flooding lowers sediment salinity and stimulates primary production. Porewater sulfide concentrations are positively correlated with tidal amplitude and vary on the same cycle as primary production. Soluble reactive phosphate and ammonium concentrations in pore water also vary on this 18.6- year cycle. Phosphate likely responds to variation in the reaction of sulfide with iron-phosphate compounds, while the production of ammonium in sediments is coupled to the activity of diazotrophs that are carbon- limited and, therefore, are regulated by primary productivity. Ammonium also would accumulate when sulfides block nitrification. These dependencies work as a positive feedback between primary production and nutrient supply and are predictive of the near-term effects of sea-level rise.

  18. Carbon sequestration by Australian tidal marshes

    KAUST Repository

    Macreadie, Peter I.

    2017-03-10

    Australia\\'s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia\\'s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia\\'s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  19. Carbon sequestration by Australian tidal marshes

    Science.gov (United States)

    Macreadie, Peter I.; Ollivier, Q. R.; Kelleway, J. J.; Serrano, O.; Carnell, P. E.; Ewers Lewis, C. J.; Atwood, T. B.; Sanderman, J.; Baldock, J.; Connolly, R. M.; Duarte, C. M.; Lavery, P. S.; Steven, A.; Lovelock, C. E.

    2017-03-01

    Australia’s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia’s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia’s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  20. 80 FR 65469 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2015-10-26

    ... Clay Products Manufacturing; and NESHAP for Clay Ceramics Manufacturing; Final Rule #0;#0;Federal...; and NESHAP for Clay Ceramics Manufacturing AGENCY: Environmental Protection Agency (EPA). ACTION... NESHAP for Clay Ceramics Manufacturing. All major sources in these categories must meet...

  1. Salt Marshes as Potential Indicatore of Global Climate Change

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairens, David; Jung, S.H.;

    2011-01-01

    Coastal scientists postulate that salt marshes are significantly affected by dynamics of global climate. However, few studies have explicitly proposed a perspective that regards salt marshes as potential indicators of climate change. This review article evaluates the possibility of salt marshes a...

  2. Recent Trends in Bird Abundance on Rhode Island Salt Marshes

    Science.gov (United States)

    Salt marsh habitat is under pressure from development on the landward side, and sea level rise from the seaward side. The resulting loss of habitat is potentially disastrous for salt marsh dependent species. To assess the population status of three species of salt marsh dependent...

  3. Effect of hurricanes and violent storms on salt marsh

    Science.gov (United States)

    Leonardi, N.; Ganju, N. K.; Fagherazzi, S.

    2016-12-01

    Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

  4. Clay resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Maljers, D.; Gessel, S.F. van; Gruijters, S.H.L.L.

    2007-01-01

    Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabricationof bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrenceinformatio

  5. Clay resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Maljers, D.; Gessel, S.F. van; Gruijters, S.H.L.L.

    2007-01-01

    Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabrication of bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrence informat

  6. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p...

  7. Viscous property of dried clay

    Institute of Scientific and Technical Information of China (English)

    XU Li-sheng; LI Jian-zhong

    2006-01-01

    One dimensional and triaxial compression tests of air-dried and oven-dried Fujinomori clay and Pisa clay were carried out. Water content is less than 4.5 % and 1.0% for air-dried and oven-dried clay specimens, respectively. In all tests, axial strain rate was changed stepwise many times and drained creep tests were performed several times during monotonic loading at a constant strain rate. Global unloading (and also reloading in some tests) was applied during which creep loading tests were performed several times. Cyclic loading with small stress amplitude and several cycles was also performed to calculate the modulus of elasticity of the clay in tests. Local displacement transducer was used in triaxial compression test to increase measuring accuracy of axial strain. The results show that air-dried and oven-dried clay have noticeable viscous properties; during global unloading, creep deformation changes from positive to negative, i.e. there exist neutral points (zero creep deformation or no creep deformation point) in global unloading part of strain-stress curve; viscous property of Fujinomori clay decreases when water content decreases, i.e. viscous property of air-dried Fujinomori clay is more significant than that of oven-dried Fujinomori clay.

  8. Clay minerals in pollution control

    Energy Technology Data Exchange (ETDEWEB)

    Tateo, F. [Consiglio Nazionale delle Ricerche, Istituto di Ricerca sulle Argille, Tito Scalo, PZ (Italy)

    2000-07-01

    Clay minerals are fundamental constituents of life, not only as possible actors in the development of life on the Earth (Cairns-Smith and Hartman, 1986), but mainly because they are essential constituents of soils, the interface between the solid planet and the continental biosphere. Many, many authors have devoted themselves to the study of clays and clay minerals since the publication of the early modern studies by Grim (1953, 1962) and Millot (1964). In those years two very important associations were established in Europe (Association Internationale pour l'Etude des Argiles, AIPEA) and in the USA (Clay Mineral Society, CMS). The importance of these societies is to put together people that work in very different fields (agronomy, geology, geochemistry, industry, etc.), but with a common language (clays), very useful in scientific work. Currently excellent texts are being published, but introductory notes are also available on the web (Schroeder, 1998).

  9. Mineral resource of the Month: Clay

    Science.gov (United States)

    Virta, Robert L.

    2010-01-01

    Clays were one of the first mineral commodities used by people. Clay pottery has been found in archeological sites that are 12,000 years old, and clay figurines have been found in sites that are even older.

  10. Flow paths of water and sediment in a tidal marsh: relations with marsh developmental stage and tidal inundation height

    NARCIS (Netherlands)

    Temmerman, S.; Bouma, T.J.; Govers, G.; Lauwaet, D.

    2005-01-01

    This study provides new insights in the relative role of tidal creeks and the marsh edge in supplying water and sediments to and from tidal marshes for a wide range of tidal inundation cycles with different high water levels and for marsh zones of different developmental stage. Net import or export

  11. Viscosity and Plasticity of Latvian Illite Clays

    OpenAIRE

    2012-01-01

    Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

  12. Marsh benthic Foraminifera response to estuarine hydrological balance driven by climate variability over the last 2000 yr (Minho estuary, NW Portugal)

    Science.gov (United States)

    Moreno, João; Fatela, Francisco; Leorri, Eduardo; De la Rosa, José M.; Pereira, Inês; Araújo, M. Fátima; Freitas, M. Conceição; Corbett, D. Reide; Medeiros, Ana

    2014-09-01

    A high-resolution study of a marsh sedimentary sequence from the Minho estuary provides a new palaeoenvironmental reconstruction from NW Iberian based on geological proxies supported by historical and instrumental climatic records. A low-salinity tidal flat, dominated by Trochamminita salsa, Haplophragmoides spp. and Cribrostomoides spp., prevailed from AD 140-1360 (Roman Warm Period, Dark Ages, Medieval Climatic Anomaly). This sheltered environment was affected by high hydrodynamic episodes, marked by the increase in silt/clay ratio, decrease of organic matter, and poor and weakly preserved foraminiferal assemblages, suggesting enhanced river runoff. The establishment of low marsh began at AD 1380. This low-salinity environment, marked by colder and wet conditions, persisted from AD 1410-1770 (Little Ice Age), when foraminiferal density increased significantly. Haplophragmoides manilaensis and Trochamminita salsa mark the transition from low to high marsh at AD 1730. Since AD 1780 the abundances of salt marsh species (Jadammina macrescens, Trochammina inflata) increased, accompanied by a decrease in foraminiferal density, reflecting climate instability, when droughts alternate with severe floods. SW Europe marsh foraminifera respond to the hydrological balance, controlled by climatic variability modes (e.g., NAO) and solar activity, thus contributing to the understanding of NE Atlantic climate dynamics.

  13. THE EFFECT OF DRAINAGE ON CHEMICAL ELEMENTS CONTENT OF MARSH

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper takes marsh in the Sanjiang Plain as an example in order to research the effect of draining on the chemical elements in marsh. The Sanjiang Ecological Test Station of Mire and Uetland serves as the resarch base. The authors selected soil samples in the Sanjiang Plain (the top and the end of the drain, marsh soil and degeneration marsh soil), mainly analyzed contents of main ions (HCO3-, Cl-, SO42-and NO3-), main heavy metals (Fe, Mn, Znand Cu), nutritive elements (N, P,K), organic matter and pH value. By testing these samples as above, the paper initially researches the effect on chemical elements content by draining by the means of the contrast of chemical elements contents between marsh soil and degenerative marsh soil and different characteristics of marsh soil elements. Results show that a lot of chemical elements had been lost because of draining.

  14. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater.

    Science.gov (United States)

    Ro, Kyoung S; Hunt, Patrick G; Johnson, Melvin H; Matheny, Terry A; Forbes, Dean; Reddy, Gudigopuram B

    2010-01-01

    Oxygen transfer efficiencies of various components of the marsh-pond-marsh (M-P-M) and marsh-floating bed-marsh (M-FB-M) wetlands treating swine wastewater were determined by performing oxygen mass balance around the wetlands. Biological oxygen demand (BOD) and total nitrogen (TN) loading and escaping rates from each wetland were used to calculate carbonaceous and nitrogenous oxygen demands. Ammonia emissions were measured using a wind tunnel. Oxygen transfer efficiencies of the aerated ponds were estimated by conducting the ASCE standard oxygen transfer test in a tank using the same aeration device. Covering pond water surface with the floating bed slightly decreased oxygen transfer efficiency. The diffused membrane aeration (26.7 kg O2 ha-1 d-1) of M-P-M was surprisingly not as effective as plant aeration in the marsh (38.9 to 42.0 kg O2 ha-1 d-1). This unusually low oxygen transfer efficiency of the diffused aeration was attributed to its low submergence depth of 0.8 m compared to typical depth of 4.5 m. The wetlands consisting entirely of marsh removed similar amounts of C and N without investing additional equipment and energy costs of aerating ponds in the middle of wetlands.

  15. Structural Classification of Marshes with Polarimetric SAR Highlighting the Temporal Mapping of Marshes Exposed to Oil

    Directory of Open Access Journals (Sweden)

    Elijah Ramsey

    2015-09-01

    Full Text Available Empirical relationships between field-derived Leaf Area Index (LAI and Leaf Angle Distribution (LAD and polarimetric synthetic aperture radar (PolSAR based biophysical indicators were created and applied to map S. alterniflora marsh canopy structure. PolSAR and field data were collected near concurrently in the summers of 2010, 2011, and 2012 in coastal marshes, and PolSAR data alone were acquired in 2009. Regression analyses showed that LAI correspondence with the PolSAR biophysical indicator variables equaled or exceeded those of vegetation water content (VWC correspondences. In the final six regressor model, the ratio HV/VV explained 49% of the total 77% explained LAI variance, and the HH-VV coherence and phase information accounted for the remainder. HV/HH dominated the two regressor LAD relationship, and spatial heterogeneity and backscatter mechanism followed by coherence information dominated the final three regressor model that explained 74% of the LAD variance. Regression results applied to 2009 through 2012 PolSAR images showed substantial changes in marsh LAI and LAD. Although the direct cause was not substantiated, following a release of freshwater in response to the 2010 Deepwater Horizon oil spill, the fairly uniform interior marsh structure of 2009 was more vertical and dense shortly after the oil spill cessation. After 2010, marsh structure generally progressed back toward the 2009 uniformity; however, the trend was more disjointed in oil impact marshes.

  16. Effects of open marsh water management on numbers of larval salt marsh mosquitoes

    Science.gov (United States)

    James-Pirri, Mary-Jane; Ginsberg, Howard S.; Erwin, R. Michael; Taylor, Janith

    2009-01-01

    Open marsh water management (OMWM) is a commonly used approach to manage salt marsh mosquitoes than can obviate the need for pesticide application and at the same time, partially restore natural functions of grid-ditched marshes. OMWM includes a variety of hydrologic manipulations, often tailored to the specific conditions on individual marshes, so the overall effectiveness of this approach is difficult to assess. Here, we report the results of controlled field trials to assess the effects of two approaches to OMWM on larval mosquito production at National Wildlife Refuges (NWR). A traditional OMWM approach, using pond construction and radial ditches was used at Edwin B. Forsythe NWR in New Jersey, and a ditch-plugging approach was used at Parker River NWR in Massachusetts. Mosquito larvae were sampled from randomly placed stations on paired treatment and control marshes at each refuge. The proportion of sampling stations that were wet declined after OMWM at the Forsythe site, but not at the Parker River site. The proportion of samples with larvae present and mean larval densities, declined significantly at the treatment sites on both refuges relative to the control marshes. Percentage of control for the 2 yr posttreatment, compared with the 2 yr pretreatment, was >90% at both treatment sites.

  17. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had

  18. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had high

  19. Interpreter's Guide to Blackbird Marsh Nature Trail.

    Science.gov (United States)

    Environmental Studies Center, Pensacola, FL.

    This booklet was prepared to help the user interpret the natural history of Blackbird Marsh Nature Trail in Escambia County, Florida, and serves as a guide to the animal and plant life. The publication is part of a series of illustrated guides designed for use by teachers and students of all levels in conjunction with field trips to the 1200-acre…

  20. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    -type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...... have been tested successfully. At a natural water content of w=40-45% it is possible to establish a homogeneous membrane with hydraulic conductivity k...

  1. Constitutive model for overconsolidated clays

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

  2. Colloidal gels: Clay goes patchy

    Science.gov (United States)

    Kegel, Willem K.; Lekkerkerker, Henk N. W.

    2011-01-01

    Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

  3. Porosity Investigation of Kosova's Clay

    OpenAIRE

    Makfire Sadiku; Naim Hasani; Altin Mele

    2011-01-01

    Problem statement: Acid activated clay minerals are used as catalysts in the desulphurization of crude oil or as catalyst carrier, as drilling mud, as bleaching earth. Approach: The efficiency of the acid activation can be described in two ways. As increase of the surface and as increase of the cumulative pore volume after the activation. Results: In different samples of the clay mineral the activation was done with different sulfuric acid concentrations for two and 3h. Afterwards the specifi...

  4. Clays in radioactive waste disposal

    OpenAIRE

    Delage, Pierre; Cui, Yu-Jun; Tang, Anh-Minh

    2010-01-01

    Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth. The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept. In relation to these concepts, various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth. After introducing the concepts of waste isolation developed in Belgium, Fran...

  5. What makes a natural clay antibacterial?

    Science.gov (United States)

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

    2011-01-01

    Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

  6. Marsh expansion at Calaveras Point Marsh, South San Francisco Bay, California

    Science.gov (United States)

    Watson, Elizabeth Burke

    2008-07-01

    Studies of shoreline progradation along low-energy vegetated shorelines have been limited, as these environments are generally experiencing erosion rather than deposition, with extreme erosion rates frequently found. This study examined yearly changes along a vegetated shoreline at Calaveras Point Marsh, South San Francisco Bay, California, using aerial photography, to determine the roles of climatic, watershed, and coastal process in driving shoreline changes. In addition, sediment accumulation was monitored on a yearly basis at 48 locations across the marsh to determine the role of geomorphic factors in promoting accumulation. Calaveras Point Marsh was found to have expanded from 49.26 ± 5.2 to 165.7 ± 4.7 ha between 1975 and 2005. Although the rate of marsh expansion was not positively correlated with yearly variability in precipitation, local streamflow, delta outflow, water level observations, population growth, or ENSO indices, marsh growth was greater during years of higher than average temperatures. Warmer temperatures may have promoted the recruitment and growth of Spartina foliosa, a C 4 grass known to be highly responsive to temperature. Other factors, such as the formation of a coastal barrier, a recent change in the location of the mouth of the Guadalupe River, and channel readjustment in response to diking are credited with driving the bulk of the marsh expansion. Sediment accumulation was found to be high closest to channels and to the shoreline, at low elevations and in recently vegetated marsh. Globally, the pace of sea level rise exerts the primary control on wetland development and persistence. However, at local geographic scales, factors such as tectonic events, modifications to natural sediment transport pathways or land use changes may overwhelm the effects of regional sea level rise, and allow for wetlands to develop, expand and persist despite rapid sea level rise.

  7. Effect of Vegetation on Sediment Transport across Salt Marshes

    Science.gov (United States)

    Coleman, D. J.; Kirwan, M. L.; Guntenspergen, G. R.; Ganju, N. K.

    2016-12-01

    Salt marshes are a classic example of ecogeomorphology where interactions between plants and sediment transport govern the stability of a rapidly evolving ecosystem. In particular, plants slow water velocities which facilitates deposition of mineral sediment, and the resulting change in soil elevation influences the growth and species distribution of plants. The ability of a salt marsh to withstand sea level rise (SLR) is therefore dependent, among other factors, on the availability of mineral sediment. Here we measure suspended sediment concentrations (SSC) along a transect from tidal channel to marsh interior, exploring the role biomass plays in regulating the magnitude and spatial variability in vertical accretion. Our study was conducted in Spartina alterniflora dominated salt marshes along the Atlantic Coast from Massachusetts to Georgia. At each site, we deployed and calibrated optical back scatter turbidity probes to measure SSC in 15 minute intervals in a tidal channel, on the marsh edge, and in the marsh interior. We visited each site monthly to measure plant biomass via clip plots and vertical accretion via two types of sediment tiles. Preliminary results confirm classic observations that biomass is highest at the marsh edge, and that SSC and vertical accretion decrease across the marsh platform with distance from the channel. We expect that when biomass is higher, such as in southern sites like Georgia and months late in the growing season, SSC will decay more rapidly with distance into the marsh. Higher biomass will likely also correspond to increased vertical accretion, with the greatest effect at marsh edge locations. Our study will likely demonstrate how salt marsh plants interact with sediment transport dynamics to control marsh morphology and thus contribute to marsh resilience to SLR.

  8. Wave liquefaction in soils with clay content

    DEFF Research Database (Denmark)

    Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction...... is increased with increasing clay content, up to 30%, beyond which the mixture of silt and clay is not liquefied. Sand may become prone to liquefaction with the introduction of clay, contrary to the general perception that this type of sediment is normally liquefaction resistant under waves....

  9. 81 FR 31234 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2016-05-18

    ... AGENCY NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics... Brick and Structural Clay Products (BSCP) Manufacturing and the final NESHAP for Clay Ceramics... No. EPA-HQ-OAR-2013-0290 for Clay Ceramics Manufacturing. All documents in the dockets are listed...

  10. Salt Marsh Response and Recovery to Coseismic Subsidence

    Science.gov (United States)

    Aranda, A. N.; Carlin, J. A.; Rhodes, B. P.; Kirby, M.; Leeper, R. J.; Smith, R. W.

    2016-12-01

    Salt marshes worldwide are under increasing stress from eustatic sea level rise. Along the tectonically active west coast of North America, some salt marshes are also vulnerable to abrupt increases in relative sea level rise (RSLR) resulting from coseismic subsidence. Elevation zonation of sub-environments within a marsh provides the opportunity to interpret the sedimentary record in marshes to infer past earthquakes, which may improve understanding of regional seismic hazards and ecosystem response to increases in sea level. Our study area is the Seal Beach Wetlands (SBW), an 3 km2 salt marsh straddling the seismically active Newport-Inglewood fault zone in southern California. A previous study of the SBW identified sedimentary evidence of three coseismic subsidence events. Here, our goals were to identify coseismic subsidence events preserved in SBW stratigraphy and to quantify marsh recovery following an earthquake to assess marsh resiliency to rapid RSLR. To do this, we focused on one core collected near the fringe of the SBW and applied a suite of sedimentary and geochemical analyses. Our results indicated that the SBW may preserve sedimentary evidence of four potential coseismic subsidence events. Events were distinguished in the stratigraphy by a sharp upper contact interpreted as an abrupt shift in marsh depositional sub-environments, from a vegetated marsh, to an intertidal mudflat or a subtidal environment. This stratigraphy suggests that the marsh rapidly subsided, preserving the evidence of the vegetated marsh as a peat deposit overlain by a low-organic mud or muddy-sand layer. A typical marsh accretion facies succession occurred above each earthquake event in the core, suggesting full marsh recovery. From the core data, we also observed that the net average rate of marsh recovery, i.e., marsh accretion, was consistent. Estimated recovery rates between 0.6 and 1.1 mm/yr were comparable to the overall accretion rate and regional late Holocene RSLR rate

  11. Sea-Level Rise Impacts on Hudson River Marshes

    Science.gov (United States)

    Hooks, A.; Nitsche, F. O.

    2015-12-01

    The response of tidal marshes to increasing sea-level rise is uncertain. Tidal marshes can adapt to rising sea levels through vertical accretion and inland migration. Yet tidal marshes are vulnerable to submergence if the rate of sea-level rise exceeds the rate of accretion and if inland migration is limited by natural features or development. We studied how Piermont and Iona Island Marsh, two tidal marshes on the Hudson River, New York, would be affected by sea-level rise of 0.5m, 1m, and 1.5m by 2100. This study was based on the 2011-2012 Coastal New York LiDAR survey. Using GIS we mapped sea-level rise projections accounting for accretion rates and calculated the submerged area of the marsh. Based on the Hudson River National Estuarine Research Reserve Vegetation 2005 dataset, we studied how elevation zones based on vegetation distributions would change. To evaluate the potential for inland migration, we assessed land cover around each marsh using the National Land Cover Database 2011 Land Cover dataset and examined the slope beyond the marsh boundaries. With an accretion rate of 0.29cm/year and 0.5m of sea-level rise by 2100, Piermont Marsh would be mostly unchanged. With 1.5m of sea-level rise, 86% of Piermont Marsh would be flooded. For Iona Island Marsh with an accretion rate of 0.78cm/year, sea-level rise of 0.5m by 2100 would result in a 4% expansion while 1.5m sea-level rise would cause inundation of 17% of the marsh. The results indicate that Piermont and Iona Island Marsh may be able to survive rates of sea-level rise such as 0.5m by 2100 through vertical accretion. At rates of sea-level rise like 1.5m by 2100, vertical accretion cannot match sea-level rise, submerging parts of the marshes. High elevations and steep slopes limit Piermont and Iona Island Marsh's ability to migrate inland. Understanding the impacts of sea-level rise on Piermont and Iona Island Marsh allows for long-term planning and could motivate marsh conservation programs.

  12. How mobile are sorbed cations in clays and clay rocks?

    Science.gov (United States)

    Gimmi, T; Kosakowski, G

    2011-02-15

    Diffusion of cations and other contaminants through clays is of central interest, because clays and clay rocks are widely considered as barrier materials for waste disposal sites. An intriguing experimental observation has been made in this context: Often, the diffusive flux of cations at trace concentrations is much larger and the retardation smaller than expected based on their sorption coefficients. So-called surface diffusion of sorbed cations has been invoked to explain the observations but remains a controversial issue. Moreover, the corresponding surface diffusion coefficients are largely unknown. Here we show that, by an appropriate scaling, published diffusion data covering a broad range of cations, clays, and chemical conditions can all be modeled satisfactorily by a surface diffusion model. The average mobility of sorbed cations seems to be primarily an intrinsic property of each cation that follows inversely its sorption affinity. With these surface mobilities, cation diffusion coefficients can now be estimated from those of water tracers. In pure clays at low salinities, surface diffusion can reduce the cation retardation by a factor of more than 1000.

  13. Hawk migration over White Marsh, Maryland

    Science.gov (United States)

    Hackman, C.D.; Henny, C.J.

    1971-01-01

    The average number of hawks observed per hour in autumn migration between 1951-1954 and 1958-1961 at White Marsh, Maryland, was compared. The counts indicated that the status of the ten species observed may be divided into three categories: (1) relatively stable species (red-tailed hawk), (2) declining species (sparrow hawk, red-shouldered hawk, osprey, marsh hawk, and broad-winged hawk), and (3) rapidly declining species (peregrine falcon, Cooper?s hawk, bald eagle, and sharp-shinned hawk). The findings from this study are in agreement with the available literature and the status of the populations appears to be related to the food habits of the species.

  14. Carbon Storage in Tagus Salt Marsh Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Cacador, Isabel, E-mail: icacador@fc.ul.pt; Costa, Ana Luisa [University of Lisbon, Institute of Oceanography, Faculty of Sciences (Portugal); Vale, Carlos [Institute for Sea and Fisheries Research (IPIMAR) (Portugal)

    2004-06-15

    Seasonal variation of above ground and belowground biomass of Spartina maritima and Halimione portulacoides, decomposition rates of belowground detritus in litterbags, and carbon partitioning in plant components and sediments were determined in two Tagus estuary marshes with different environmental conditions. Total biomass was higher in the saltier marsh from 7,190 to 6,593 g m{sup -2} dw and below ground component contributed to more than 90%. Litterbag experiment showed that 30 to 50% of carbonis decomposed within a month (decomposition rate from 0.024 to 0.060 d{sup -1}). Slower decomposition in subsequent periods agrees with accumulation of carbon concentration in sediment. Atmospheric carbon annually transferred to the plant belowground biomass is stored more efficiently in sediments of Corroios than Pancas.

  15. VEGETATION TYPE AND THE INTERTIDAL MACROINVERTEBRATE FAUNA OF A BRACKISH MARSH: PHRAGMITES VS. SPARTINA

    Science.gov (United States)

    The responses of tidal marsh macroinvertebrate assemblages to the conversion of Spartina alterniflora marshes to marshes dominated by the invasive reed, Phragmites australis, are poorly understood. Changes in edaphic, vegetative, hydrological, and detrital conditions that attend ...

  16. Black Tern Population Survey and other Marsh Bird Monitoring Activities in Vermont 2002

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report takes a look at marsh bird population trends within the marshes of Vermont, and investigates the effect of water level and marsh vegetation changes on...

  17. Assessment of Soil Quality of Tidal Marshes in Shanghai City

    OpenAIRE

    Wang, Qing; TAN, JUAN; SHA, Chenyan; RUAN, Junjie; Min WANG; HUANG, Shenfa; Wu, Jianqiang

    2013-01-01

    We take three types of tidal marshes in Shanghai City as the study object: tidal marshes in mainland, tidal marshes in the rim of islands, and shoal in Yangtze estuary. On the basis of assessing nutrient quality and environmental quality, respectively, we use soil quality index (SQI) to assess the soil quality of tidal flats, meanwhile formulate the quality grading standards, and analyze the current situation and characteristics of it. The results show that except the north of Hangzhou Bay, N...

  18. Predictors of specialist avifaunal decline in coastal marshes.

    Science.gov (United States)

    Correll, Maureen D; Wiest, Whitney A; Hodgman, Thomas P; Shriver, W Gregory; Elphick, Chris S; McGill, Brian J; O'Brien, Kathleen M; Olsen, Brian J

    2017-02-01

    Coastal marshes are one of the world's most productive ecosystems. Consequently, they have been heavily used by humans for centuries, resulting in ecosystem loss. Direct human modifications such as road crossings and ditches and climatic stressors such as sea-level rise and extreme storm events have the potential to further degrade the quantity and quality of marsh along coastlines. We used an 18-year marsh-bird database to generate population trends for 5 avian species (Rallus crepitans, Tringa semipalmata semipalmata, Ammodramus nelsonii subvirgatus, Ammodramus caudacutus, and Ammodramus maritimus) that breed almost exclusively in tidal marshes, and are potentially vulnerable to marsh degradation and loss as a result of anthropogenic change. We generated community and species trends across 3 spatial scales and explored possible drivers of the changes we observed, including marsh ditching, tidal restriction through road crossings, local rates of sea-level rise, and potential for extreme flooding events. The specialist community showed negative trends in tidally restricted marshes (-2.4% annually from 1998 to 2012) but was stable in unrestricted marshes across the same period. At the species level, we found negative population trends in 3 of the 5 specialist species, ranging from -4.2% to 9.0% annually. We suggest that tidal restriction may accelerate degradation of tidal marsh resilience to sea-level rise by limiting sediment supply necessary for marsh accretion, resulting in specialist habitat loss in tidally restricted marshes. Based on our findings, we predict a collapse of the global population of Saltmarsh Sparrows (A. caudacutus) within the next 50 years and suggest that immediate conservation action is needed to prevent extinction of this species. We also suggest mitigation actions to restore sediment supply to coastal marshes to help sustain this ecosystem into the future.

  19. Effects of vegetation patterns and grazers on tidal marshes

    OpenAIRE

    Elschot, K.

    2015-01-01

    SUMMARYsoil. These effects of large-bodied grazers on soil properties in tidal marshes has beenlargely neglected so far, but need to be considered when we want to introduce livestockto ungrazed marshes.Next to above-ground grazing, we also find small grazers that grub for below-groundstorage organs in tidal marshes. This type of grazing removes the entire plant and it istherefore much more difficult for the vegetation to regenerate. This grubbing behaviorgenerally causes bare patches to form ...

  20. Charm of Purple Clay A private museum in Wuxi is devoted to purple-clay art

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Purple-clay art pieces will be on display in a museum opening soon in Wuxi, Jiangsu Province. The museum, named Shuaiyuan Purple Clay Museum, is part of the Shuaiyuan Purple Clay Art Exhibition Center

  1. Spatial patterns of plant litter in a tidal freshwater marsh and implications for marsh persistence.

    Science.gov (United States)

    Elmore, Andrew J; Engelhardt, Katharina A M; Cadol, Daniel; Palinkas, Cindy M

    2016-04-01

    The maintenance of marsh platform elevation under conditions of sea level rise is dependent on mineral sediment supply to marsh surfaces and conversion of above- and belowground plant biomass to soil organic material. These physical and biological processes interact within the tidal zone, resulting in elevation-dependent processes contributing to marsh accretion. Here, we explore spatial pattern in a variable related to aboveground biomass, plant litter, to reveal its role in the maintenance of marsh surfaces. Plant litter persisting through the dormant season represents the more recalcitrant portion of plant biomass, and as such has an extended period of influence on ecosystem processes. We conducted a field and remote sensing analysis of plant litter height, aboveground biomass, vertical cover, and stem density (collectively termed plant litter structure) at a tidal freshwater marsh located within the Potomac River estuary, USA. LiDAR and field observations show that plant litter structure becomes more prominent with increasing elevation. Spatial patterns in litter structure exhibit stability from year to year and correlate with patterns in soil organic matter content, revealed by measuring the loss on ignition of surface sediments. The amount of mineral material embedded within plant litter decreases with increasing elevation, representing an important tradeoff with litter structure. Therefore, at low elevations where litter structure is short and sparse, the role of plant litter is to capture sediment; at high elevations where litter structure is tall and dense, aboveground litter contributes organic matter to soil development. This organic matter contribution has the potential to eclipse that of belowground biomass as the root:shoot ratio of dominant species at high elevations is low compared to that of dominant species at low elevations. Because of these tradeoffs in mineral and organic matter incorporation into soil across elevation gradients, the rate of

  2. 80 FR 75817 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2015-12-04

    ... NESHAP for Clay Ceramics Manufacturing: Correction AGENCY: Environmental Protection Agency (EPA). ACTION...; and NESHAP for Clay Ceramics Manufacturing. These amendments make two technical corrections to...

  3. Implications of sedimentological and hydrological processes on the distribution of radionuclides: The example of a salt marsh near Ravenglass, Cumbria

    Science.gov (United States)

    Carr, A. P.; Blackley, M. W. L.

    1986-05-01

    This paper summarizes sedimentological and hydrological studies at a salt marsh site on the north bank of the River Esk near Ravenglass which have a bearing on the fate of the low-level radioactive effluent from the reprocessing facility at Sellafield, Cumbria. A range of techniques has been used including electromagnetic distance measurement (EDM) and pore water pressure studies. The results show that: (a) Over a two-year period there were no significant net changes in salt marsh creek level, although shorter-term (probably seasonal) fluctuations, of the order of 2 cm, occurred. These were attributed to expansion of clay particles during the winter months. Nearby, however, there were vertical changes of the order of 1 m due to erosion. (b) Pore water pressures indicated a dynamic situation with very rapid responses both to tidal fluctuations and to rainfall. During neap tides there was clear evidence for water seeping upwards from the underlying clay/sand interface. Shortlived radionuclides ( 95Zr/95Nb and 106Ru) were detected in this zone. (c) Soil polygons, once initiated by desiccation, thereafter provide preferential routes for water (and radionuclides) to the sub-surface sediment. These, and other results, are discussed in the context of previous studies. It is concluded that the complexity of the estuarine environment results in most data being site specific.

  4. Implications of sedimentological and hydrological processes on the distribution of radionuclides: the example of a salt marsh near Ravenglass, Cumbria

    Energy Technology Data Exchange (ETDEWEB)

    Carr, A.P.; Blackley, M.W.L.

    1986-05-01

    This paper summarizes sedimentological and hydrological studies at a salt marsh site on the north bank of the River Esk near Ravenglass which have a bearing on the fate of the low-level radioactive effluent from the reprocessing facility at Sellafield, Cumbria. A range of techniques has been used including electromagnetic distance measurement (EDM) and pore water pressure studies. The results show that: (a) Over a two-year period there were no significant net changes in salt marsh creek level, although shorter-term (probably seasonal) fluctuations, of the order of 2 cm, occurred. These were attributed to expansion of clay particles during the winter months. Nearby, however, there were vertical changes of the order of 1 m due to erosion. (b) Pore water pressures indicated a dynamic situation with very rapid responses both to tidal fluctuations and to rainfall. During neap tides there was clear evidence for water seeping upwards from the underlying clay/sand interface. Shortlived radionuclides (/sup 95/Zr//sup 95/Nb and /sup 106/Ru) were detected in this zone. (c) soil polygons, once initiated by desiccation, thereafter provide preferential routes for water (and radionuclides) to the sub-surface sediment. These, and other results, are discussed in the context of previous studies. It is concluded that the complexity of the estuarine environment results in most data being site specific.

  5. Ecogeomorphology of Spartina patens-dominated tidal marshes: Soil organic matter accumulation, marsh elevation dynamics, and disturbance

    Science.gov (United States)

    Cahoon, D.R.; Ford, M.A.; Hensel, P.F.; Fagherazzi, Sergio; Marani, Marco; Blum, Linda K.

    2004-01-01

    Marsh soil development and vertical accretion in Spartina patens (Aiton) Muhl.-dominated tidal marshes is largely dependent on soil organic matter accumulation from root-rhizome production and litter deposition. Yet there are few quantitative data sets on belowground production and the relationship between soil organic matter accumulation and soil elevation dynamics for this marsh type. Spartina patens marshes are subject to numerous stressors, including sea-level rise, water level manipulations (i.e., flooding and draining) by impoundments, and prescribed burning. These stressors could influence long-term marsh sustainability by their effect on root production, soil organic matter accumulation, and soil elevation dynamics. In this review, we summarize current knowledge on the interactions among vegetative production, soil organic matter accumulation and marsh elevation dynamics, or the ecogeomorphology, of Spartina patens-dominated tidal marshes. Additional studies are needed of belowground production/decomposition and soil elevation change (measured simultaneously) to better understand the links among soil organic matter accumulation, soil elevation change, and disturbance in this marsh type. From a management perspective, we need to better understand the impacts of disturbance stressors, both lethal and sub-lethal, and the interactive effect of multiple stressors on soil elevation dynamics in order to develop better management practices to safeguard marsh sustainability as sea level rises.

  6. Gulf-Wide Information System, Environmental Sensitivity Index Marsh, Geographic NAD83, LDWF (2001) [esi_fresh_marsh_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) fresh marsh data of coastal Louisiana. The ESI is a classification and ranking system, which...

  7. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  8. Boron Enrichment in Martian Clay

    Science.gov (United States)

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  9. Strength Properties of Aalborg Clay

    DEFF Research Database (Denmark)

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...... of Aalborg Clay by use of triaxial tests from four different locations. Both the drained strength (c and ϕ) and the undrained strength (cu) are assessed through two different methods: one where the strength is assumed to vary with the effective stress and another where the strength is found to be constant....

  10. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...

  11. Treatment of swine wastewater in marsh-pond-marsh constructed wetlands.

    Science.gov (United States)

    Reddy, G B; Hunt, P G; Phillips, R; Stone, K; Grubbs, A

    2001-01-01

    Swine waste is commonly treated in the USA by flushing into an anaerobic lagoon and subsequently applying to land. This natural system type of application has been part of agricultural practice for many years. However, it is currently under scrutiny by regulators. An alternate natural system technology to treat swine wastewater may be constructed wetland. For this study we used four wetland cells (11 m width x 40 m length) with a marsh-pond-marsh design. The marsh sections were planted to cattail (Typha latifolia, L.) and bulrushes (Scirpus americanus). Two cells were loaded with 16 kg N ha(-1) day(-1) with a detention of 21 days. They removed 51% of the added N. Two additional cells were loaded with 32 kg ha(-1) day(-1) with 10.5 days detention. These cells removed only 37% of the added N. However, treatment operations included cold months in which treatment was much less efficient. Removal of N was moderately correlated with the temperature. During the warmer periods removal efficiencies were more consistent with the high removal rates reported for continuous marsh systems--often > than 70%. Phosphorus removal ranged from 30 to 45%. Aquatic macrophytes (plants and floating) assimilated about 320 and 35 kg ha(-1), respectively of N and P.

  12. Remote sensing of wetlands, marshes, and shorelines in Michigan including St. John's Marsh

    Science.gov (United States)

    Lowe, D. S.

    1976-01-01

    Remote sensing data are used to show the strategic relationship of the endangered marsh to population centers of SE Michigan. The potential ecological consequences and the impact of past development and changing lake levels are discussed. Applications of remote sensing are presented showing its usefulness for preparing statewide infrared wetland and forest mapping.

  13. Delineation of marsh types and marsh-type change in coastal Louisiana for 2007 and 2013

    Science.gov (United States)

    Hartley, Stephen B.; Couvillion, Brady R.; Enwright, Nicholas M.

    2017-05-30

    The Bureau of Ocean Energy Management researchers often require detailed information regarding emergent marsh vegetation types (such as fresh, intermediate, brackish, and saline) for modeling habitat capacities and mitigation. In response, the U.S. Geological Survey in cooperation with the Bureau of Ocean Energy Management produced a detailed change classification of emergent marsh vegetation types in coastal Louisiana from 2007 and 2013. This study incorporates two existing vegetation surveys and independent variables such as Landsat Thematic Mapper multispectral satellite imagery, high-resolution airborne imagery from 2007 and 2013, bare-earth digital elevation models based on airborne light detection and ranging, alternative contemporary land-cover classifications, and other spatially explicit variables. An image classification based on image objects was created from 2007 and 2013 National Agriculture Imagery Program color-infrared aerial photography. The final products consisted of two 10-meter raster datasets. Each image object from the 2007 and 2013 spatial datasets was assigned a vegetation classification by using a simple majority filter. In addition to those spatial datasets, we also conducted a change analysis between the datasets to produce a 10-meter change raster product. This analysis identified how much change has taken place and where change has occurred. The spatial data products show dynamic areas where marsh loss is occurring or where marsh type is changing. This information can be used to assist and advance conservation efforts for priority natural resources.

  14. Records of change in salt marshes: a radiochronological study of three Westerschelde (SW Netherlands) marshes.

    Science.gov (United States)

    Dyer, F M; Thomson, J; Croudace, I W; Cox, R; Wadsworth, R A

    2002-03-01

    Three salt marshes on a 50-km transect along the north bank of the Westerschelde Estuary were investigated to determine whether salt marshes in the estuary had responded to shipping channel modifications in recent decades. Marsh accretion rates were estimated mainly from 137Cs profiles with further evidence from 241Am because changes in both rate of deposition and nature of the accreting material precluded use of standard 210Pb(excess) dating models. The 137Cs profiles usually show peaks corresponding to atmospheric deposition from the 1963 fallout maximum and sometimes from the Chernobyl accident, although intervening enhanced 137Cs activities derived from the nuclear reprocessing marine discharges of Sellafield and La Hague are clearly discernible. In all three marshes (Ritthem at the mouth of the estuary and Zuidgors and Waarde at 20 and 45 km upstream), a marked, near-coincident change in the rate of accumulation and in the grain size of material deposited occurred around 1980. This may be related to a combination of channel deepening and straightening operations undertaken in the mid-1970s and/or natural changes in winter wave climate.

  15. Picasso Masks: Cubism in Clay

    Science.gov (United States)

    Daddino, Michelle

    2010-01-01

    This article describes an art project developed by the author which provides a way to further the children's understanding of Picasso's Cubism style in 3-D. Through this project, upper-elementary students learn a bit about the life and art of Picasso as they gain a firm understanding of the style of art known as Cubism, and apply clay techniques…

  16. ADSORPTION OF SURFACTANT ON CLAYS

    Science.gov (United States)

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  17. Biodegradable Pectin/clay Aerogels

    Science.gov (United States)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  18. Geotechnical properties of Karwar marine clay

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.T.; Nayak, B.U.; Naik, R.L.

    Karwar marine clay possesses high plasticity characteristics with natural water content higher than the liquid limit. Liquidity index was as high as 1.7. Predominant clay mineral was kaolinite. Undrained shear strength showed an increasing trend...

  19. An Ecological Study of Gray Goose Marsh, Alviso California

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The area of our study is located in the heart of the 300m wide strip of land just north of Triangle Marsh, known as Gray Goose Marsh. This land used to be part of an...

  20. Oregon Salt Marshes: How Blue are They? November 12, 2015

    Science.gov (United States)

    We quantified carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries in Oregon, USA. Net carbon and nitrogen accumulation rates were quantified by measuring the content of these constituents in sediment that accumulated in marsh ha...

  1. SALT MARSHES ALONG THE COAST OF THE NETHERLANDS

    NARCIS (Netherlands)

    BAKKER, JP; DELEEUW, J; DIJKEMA, KS; LEENDERTSE, PC; PRINS, HHT; ROZEMA, J

    1993-01-01

    The area of salt marshes does no longer increase. The recent erosion coincides with a rise on MHT-level in the last 25 years. Despite the decrease in area, sedimentation continues, especially in the lower salt marsh, which acts as a sink of nitrogen. Assimilation and mineralization of nitrogen are

  2. Mangrove expansion into salt marshes alters associated faunal communities

    Science.gov (United States)

    Delbert L. Smee; James A. Sanchez; Meredith Diskin; Carl Trettin

    2017-01-01

    Climate change is altering the distribution of foundation species, with potential effects on organisms that inhabit these environments and changes to valuable ecosystem functions. In the Gulf of Mexico, black mangroves (Avicennia germinans) are expanding northward into salt marshes dominated by Spartina alterniflora (hereafter Spartina). Salt marshes are essential...

  3. Effects of vegetation patterns and grazers on tidal marshes

    NARCIS (Netherlands)

    Elschot, Kelly

    2015-01-01

    Increasing grazing pressures threaten grasslands on a global scale. Therefore, it is important to understand the impact of grazers on the functioning of an ecosystem. In this study, we focused on the effects of small and large grazers on the marsh vegetation and important marsh dynamics, such as sed

  4. The Stalled Recovery of the Iraqi Marshes

    Directory of Open Access Journals (Sweden)

    Richard H. Becker

    2014-01-01

    Full Text Available The Iraqi (Mesopotamian Marshes, an extensive wetlands system in Iraq, has been heavily impacted by both human and climate forces over the past decades. In the period leading up to the Second Gulf War in 2002, the marshlands were shrinking due to both a policy of draining and water diversion in Iraq and construction of dams upstream on the Tigris and Euphrates rivers. Following the war through 2006, this trend was reversed as the diversions were removed and active draining stopped. A combination of MODIS and GRACE datasets were used to determine the change in surface water area (SWA in the marshes, marshland extent and change in mass both upriver in the Tigris and Euphrates watersheds and in the marshlands. Results suggest that the post war dam removal and decreased pumping in 2003 provided only temporary respite for the marshlands (2003–2006 SWA: 1,477 km2 increase (600%, water equivalent depth (WED: +2.0 cm/yr.; 2006–2009: −860 km2 (−41% WED: −3.9 cm/yr.. Unlike in the period 2003–2006, from 2006 forward the mass variations in the marshes are highly correlated with those in the upper and middle watershed (R = 0.86 and 0.92 respectively, suggesting that any recovery due to that removal is complete, and that all future changes are tied more strongly to any climate changes that will affect recharge in the upper Tigris-Euphrates system. Precipitation changes in the watershed show a reduction of an average of 15% below the 15 yr mean in 2007–2011 This corresponds with published ensemble predictions for the 2071–2099 time period, that suggested similar marshland shrinkage should be expected in that time period.

  5. 21 CFR 186.1256 - Clay (kaolin).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain...

  6. Overestimation of marsh vulnerability to sea level rise

    Science.gov (United States)

    Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio

    2016-01-01

    Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-based models predict survival under a wide range of future sea level scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sea level rise, and the potential for marshes to migrate inland.

  7. Impact of sediment supply on Spartina salt marshes

    Institute of Scientific and Technical Information of China (English)

    SHEN Yong-Ming; YANG Jing-Song; WANG Yan-Hong; FENG Nian-Hua; ZHOU Qin; ZENG Hua

    2008-01-01

    During the past century,natural and human modifications of environmental systems have greatly accelerated coastal salt marsh deterioration and shoreline retreat in many regions worldwide.Field investigation,profile analysis,geographical information analysis,and remote sensing were employed in combination to study the effect of sediment on Spartina ulterniflora salt marshes of the coast in Jiangsu Province,East China.The results indicated that the propagation of Spartina alterniflora salt marshes was closely related to regional sediment conditions,especially the supply of fine-grained materials.Additionally,because of the dense and high grass in Spartina ulterniflora salt marshes,wave energy and tidal currents were baffled and weaker than those of the adjacent,unvegetated mud fiats.Fine sediment was hardly resuspended under the low energy conditions in the Spartina alterniflora salt marshes.

  8. Clay Cuffman: A Cool, Calm, Relaxed Guy

    Science.gov (United States)

    Booth, Gina

    2010-01-01

    This article describes Clay Cuffman, a simple clay-sculpture project that requires two or three sessions, and works for students from the upper-elementary level through high school. It takes about 1.5 pounds of clay per student--about the size of a small grapefruit. The Cuffman project is a great way for upper-elementary through high-school…

  9. Hydrodynamic erosion process of undisturbed clay

    NARCIS (Netherlands)

    Zhao, G.; Visser, P.J.; Vrijling, J.K.

    2011-01-01

    This paper describes the hydrodynamic erosion process of undisturbed clay due to the turbulent flow, based on theoretical analysis and experimental results. The undisturbed clay has the unique and complicated characteristics of cohesive force among clay particles, which are highly different from dis

  10. Clay & Children: More than Making Pots.

    Science.gov (United States)

    Kolbe, Ursula

    1997-01-01

    Working with clay enables young children to express, explore, and communicate their feelings and ideas. This resource booklet for early childhood practitioners and it promotes the clay table as a special place for shared discoveries, social interaction, and discussion. The booklet provides a glossary of terms used in clay work, as well as reasons…

  11. Florida's salt-marsh management issues: 1991-98.

    Science.gov (United States)

    Carlson, D B; O'Bryan, P D; Rey, J R

    1999-06-01

    During the 1990s, Florida has continued to make important strides in managing salt marshes for both mosquito control and natural resource enhancement. The political mechanism for this progress continues to be interagency cooperation through the Florida Coordinating Council on Mosquito Control and its Subcommittee on Managed Marshes (SOMM). Continuing management experience and research has helped refine the most environmentally acceptable source reduction methods, which typically are Rotational Impoundment Management or Open Marsh Water Management. The development of regional marsh management plans for salt marshes within the Indian River Lagoon by the SOMM has helped direct the implementation of the best management practices for these marshes. Controversy occasionally occurs concerning what management technique is most appropriate for individual marshes. The most common disagreement is over the benefits of maintaining an impoundment in an "open" vs. "closed" condition, with the "closed" condition, allowing for summer mosquito control flooding or winter waterfowl management. New federal initiatives influencing salt-marsh management have included the Indian River Lagoon-National Estuary Program and the Pesticide Environmental Stewardship Program. A new Florida initiative is the Florida Department of Environmental Protection's Eco-system Management Program with continuing involvement by the Surface Water Improvement and Management program. A developing mitigation banking program has the potential to benefit marsh management but mosquito control interests may suffer if not handled properly. Larvicides remain as an important salt-marsh integrated pest management tool with the greatest acreage being treated with temephos, followed by Bacillus thuringiensis israelensis and methoprene. However, over the past 14 years, use of biorational larvicides has increased greatly.

  12. Restoring Ecological Function to a Submerged Salt Marsh

    Science.gov (United States)

    Stagg, C.L.; Mendelssohn, I.A.

    2010-01-01

    Impacts of global climate change, such as sea level rise and severe drought, have altered the hydrology of coastal salt marshes resulting in submergence and subsequent degradation of ecosystem function. A potential method of rehabilitating these systems is the addition of sediment-slurries to increase marsh surface elevation, thus ameliorating effects of excessive inundation. Although this technique is growing in popularity, the restoration of ecological function after sediment addition has received little attention. To determine if sediment subsidized salt marshes are functionally equivalent to natural marshes, we examined above- and belowground primary production in replicated restored marshes receiving four levels of sediment addition (29-42 cm North American Vertical Datum of 1988 [NAVD 88]) and in degraded and natural ambient marshes (4-22 cm NAVD 88). Moderate intensities of sediment-slurry addition, resulting in elevations at the mid to high intertidal zone (29-36 cm NAVD 88), restored ecological function to degraded salt marshes. Sediment additions significantly decreased flood duration and frequency and increased bulk density, resulting in greater soil drainage and redox potential and significantly lower phytotoxic sulfide concentrations. However, ecological function in the restored salt marsh showed a sediment addition threshold that was characterized by a decline in primary productivity in areas of excessive sediment addition and high elevation (>36 cm NAVD 88). Hence, the addition of intermediate levels of sediment to submerging salt marshes increased marsh surface elevation, ameliorated impacts of prolonged inundation, and increased primary productivity. However, too much sediment resulted in diminished ecological function that was equivalent to the submerged or degraded system. ?? 2010 Society for Ecological Restoration International.

  13. Patterns of short-term sedimentation in a freshwater created marsh.

    Science.gov (United States)

    Harter, Sarah K; Mitsch, William J

    2003-01-01

    This study investigated different sedimentation measurement techniques and examined patterns of short-term sedimentation in two 1-ha replicate created freshwater marshes in central Ohio, USA. Short-term (one-year) sediment accumulation above feldspar, clay, glitter, and sand artificial marker horizons was compared at different water depths and distances from wetland inflow. A sediment budget was also constructed from turbidity and suspended sediment data for comparison with marker horizons. Glitter and sand marker horizons were the most successful for measuring sediment accumulation (81-100% marker recovery), while clay markers were completely unsuccessful. The sedimentation rate for both wetlands averaged 4.9 cm yr(-1) (36 kg m(-2) yr(-1)), and ranged from 1.82 to 9.23 cm yr(-1) (12.4 to 69.7 kg m(-2) yr(-1)). Sedimentation rates in deep, open water areas were significantly higher than in shallow, vegetated areas for both wetlands (t test, p wetlands, suggesting that bioturbation and turbulence may cause significant resuspension or that high hydrologic loads may distribute sediments throughout the basins. A sediment budget estimated sediment retention of approximately 740 g m(-2) yr(-1) per wetland (43% removal rate), yet gross sediment accumulation was 36,000 g m(-2) yr(-1) measured by marker horizons. These results suggest that erosive forces may have influenced sedimentation, but also may indicate problems with the sediment budget calculation methodology.

  14. The systems containing clays and clay minerals from modified drug release: a review.

    Science.gov (United States)

    Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

    2013-03-01

    Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied.

  15. Assessment of hydraulic restoration of San Pablo Marsh, California.

    Science.gov (United States)

    Grismer, Mark E; Kollar, J; Syder, J

    2004-11-01

    Inter-tidal marshes are dynamic diverse ecosystems at the transition zone between terrestrial and ocean environments. Geomorphologically, inter-tidal salt marshes are vegetated land-forms at elevations slightly greater than mean tidal levels that have distributed channels formed under ebb (drainage) tidal flows that widen and deepen in the seaward direction. The drainage channels enable tidal flows to circulate sediments and nutrients through the marsh system during normal tidal events, while depositing sediments during storm or seismic events. This dynamic system encourages considerable biodiversity while simultaneously providing water quality enhancement features that service marsh terrestrial life and marine life in the estuary. Reservoir creation limiting sediment transport, anticipated large increases in sea levels as well as agricultural and urban development have resulted in significant loss of inter-tidal marshes and subsequent adverse impacts on waterfowl, infauna and fisheries. The complex and continuously changing marsh channel hydraulics and sedimentary processes have severely constrained quantitative modeling of these marsh systems such that restoration/creation efforts remain something of an empirical science and further assessments are needed. The purpose of this paper is to outline current understanding of salt marsh hydrodynamics, sediment accretion processes and subsequent response of marsh vegetation to set the stage for assessment of a marsh restoration effort along San Pablo Bay near San Francisco, California. Several kilometers of drainage channels were constructed in a 624 ha disturbed salt marsh to restore tidal circulation and vegetation so as to enhance habitat for threatened species (e.g. clapper rail, harvest mouse, delta smelt and potentially anadromous fish species). Two distinct drainage channel systems ('east' and 'west') were installed having similar channel dimensions common to salt marshes in the region, but having design bankfull

  16. 78 FR 24717 - Crescent Ranger District; Deschutes National Forest; Klamath County, Oregon; Marsh Project...

    Science.gov (United States)

    2013-04-26

    ... Marsh, one of the largest high elevation wetland/marsh complexes in the continental United States. In... Forest Service Crescent Ranger District; Deschutes National Forest; Klamath County, Oregon; Marsh Project... statement (EIS) for a project called Marsh, in the southwestern portion of the Crescent Ranger District...

  17. Nitrogen and phosphorus limitation in a coastal barrier salt marsh : the implications for vegetation succession

    NARCIS (Netherlands)

    van Wijnen, HJ; Bakker, JP

    1999-01-01

    1 A factorial fertilizer experiment was conducted in a 15-year-old coastal barrier salt marsh with a low soil nitrogen content, and in an older 100-year-old marsh with a higher nitrogen content. Plots were fertilized at high and low marsh elevations in both marshes. Nitrogen and phosphorus were appl

  18. Mineral acquisition from clay by budongo forest chimpanzees

    NARCIS (Netherlands)

    Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consum

  19. Contact micromechanics in granular media with clay

    Energy Technology Data Exchange (ETDEWEB)

    Ita, Stacey Leigh [Univ. of California, Berkeley, CA (United States)

    1994-08-01

    Many granular materials, including sedimentary rocks and soils, contain clay particles in the pores, grain contacts, or matrix. The amount and location of the clays and fluids can influence the mechanical and hydraulic properties of the granular material. This research investigated the mechanical effects of clay at grain-to-grain contacts in the presence of different fluids. Laboratory seismic wave propagation tests were conducted at ultrasonic frequencies using spherical glass beads coated with Montmorillonite clay (SWy-1) onto which different fluids were adsorbed. For all bead samples, seismic velocity increased and attenuation decreased as the contact stiffnesses increased with increasing stress demonstrating that grain contacts control seismic transmission in poorly consolidated and unconsolidated granular material. Coating the beads with clay added stiffness and introduced viscosity to the mechanical contact properties that increased the velocity and attenuation of the propagating seismic wave. Clay-fluid interactions were studied by allowing the clay coating to absorb water, ethyl alcohol, and hexadecane. Increasing water amounts initially increased seismic attenuation due to clay swelling at the contacts. Attenuation decreased for higher water amounts where the clay exceeded the plastic limit and was forced from the contact areas into the surrounding open pore space during sample consolidation. This work investigates how clay located at grain contacts affects the micromechanical, particularly seismic, behavior of granular materials. The need for this work is shown by a review of the effects of clays on seismic wave propagation, laboratory measurements of attenuation in granular media, and proposed mechanisms for attenuation in granular media.

  20. Polyamide 66/Brazilian Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    E. M. Araújo

    2009-01-01

    Full Text Available Polyamide 66 (PA66/Brazilian clay nanocomposites were produced via direct melt intercalation. A montmorillonite sample from the Brazilian state of Paraíba was organically modified with esthearildimethylammonium chloride (Praepagen, quaternary ammonium salt and has been tested to be used in polymer nanocomposites. The dispersion analysis and the interlayer spacing of the clay particles in matrix were investigated by X-ray diffraction (XRD and transmission electron microscopy (TEM. Thermal behavior of the obtained systems was investigated by differential scanning calorimetry (DSC, thermogravimetry (TG, and heat deflection temperature (HDT was reported too. The nanocomposites exhibited a partially exfoliated structure, very interesting HDT values which are higher than those of pure PA66, and good thermal stability.

  1. Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

    Science.gov (United States)

    Sasser, C.E.; Gosselink, J.G.; Swenson, E.M.; Swarzenski, C.M.; Leibowitz, N.C.

    1996-01-01

    In the 1940s extensive floating marshes (locally called 'flotant') were reported and mapped in coastal wetlands of the Mississippi River Delta Plain. These floating marshes included large areas of Panicum hemitomon-dominated freshwater marshes, and Spartina patens/Scirpus olneyi brackish marshes. Today these marshes appear to be quite different in extent and type. We describe five floating habitats and one non-floating, quaking habitat based on differences in buoyancy dynamics (timing and degree of floating), substrate characteristics, and dominant vegetation. All floating marshes have low bulk density, organic substrates. Nearly all are fresh marshes. Panicum hemitomon floating marshes presently occur within the general regions that were reported in the 1940's by O'Neil, but are reduced in extent. Some of the former Panicum hemitomon marshes have been replaced by seasonally or variably floating marshes dominated, or co-dominated by Sagittaria lancifolia or Eleocharis baldwinii. ?? 1996 Kluwer Academic Publishers.

  2. Hands-on Virtual Clay

    OpenAIRE

    Pihuit, Adeline; Kry, Paul; Cani, Marie-Paule

    2008-01-01

    poster; International audience; This paper presents a new interaction system designed for hands-on 3D shape modeling and deformation through natural hand gestures. Our system is made of a Phantom haptic device coupled with a deformable foam ball that supports pressure sensors. These sensors detect forces exerted by the user's fingertips, and are used to control the configuration of a compliant virtual hand that is modeling soft virtual clay. During interaction, the user is provided both passi...

  3. Porosity Investigation of Kosova's Clay

    Directory of Open Access Journals (Sweden)

    Makfire Sadiku

    2011-01-01

    Full Text Available Problem statement: Acid activated clay minerals are used as catalysts in the desulphurization of crude oil or as catalyst carrier, as drilling mud, as bleaching earth. Approach: The efficiency of the acid activation can be described in two ways. As increase of the surface and as increase of the cumulative pore volume after the activation. Results: In different samples of the clay mineral the activation was done with different sulfuric acid concentrations for two and 3h. Afterwards the specific surface was measured by means of nitrogen adsorption. All the measured isotherms belong to the pseudo-two kind. After the activation the surface enhanced from around 100-180 m2 g-1. The mesopore distribution is calculated out of the hysteresis between adsorption-desorption isotherms of the nitrogen. Conclusion: It is shown that the activation increases significantly the amount of mesopores which is reflected in the cumulative volume. The macrospore volume of the clay samples were measured by means of mercury intrusion porosimetry for pore sizes up to 320 nm. The volume of the macrospores results to an increase up to two times after the activation. The cumulative volume of all the pores is shown like a good parameter of the efficiency of the acid activation. The measurements were fulfilled in the newly equipped laboratory of the surface characterizations of the Tirana University. These analyses are of big interest for the industry in Albania and Kosove.

  4. Environmental controls on multiscale spatial patterns of salt marsh vegetation

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairns, David; Bartholdy, Jesper

    2010-01-01

    physical processes operate. This study investigated such a topography-vegetation relationship in a Danish salt marsh, focusing upon two scales: a macro-scale (ca. 500 m) across the marsh platform, encompassing seaward and landward areas, and a meso-scale ( ca. 25 m) across tidal creeks. While long-term sea...... represented an ecological sequence from early to late succession, and strongly correlated with surface elevation. However, the gradient did not show any significant relationship with distance from shoreline or tidal channels. Our results suggest that, in salt marshes, elevation plays a still more important...

  5. Modeling storm and sea level rise impacts on marsh transgression

    Science.gov (United States)

    Carr, J. A.; Guntenspergen, G. R.; Kirwan, M. L.

    2016-12-01

    Coastal salt marsh systems provide critical ecosystem services, including key habitat and coastal protection. Both lateral extent, and vertical stability of salt marshes to sea level rise have been shown to be functions of both biotic, and abiotic drivers and feedbacks. As a result, the ecogeomorphic evolution of the system can exhibit strong non-linearities, discontinuities and thresholds. We developed a two-dimensional transect model to explore controls on marsh lateral extent, vertical stability and the potential for marsh transgression inland and upland. Salt marsh and upland regions in the model are discretized in 1 m increments with inundation frequency determined by the elevation of the individual cells, organogenic soil formation and mineral deposition rates, and the history of stochastic water levels. The transect extends from an idealized back barrier bay across the salt marsh platform and into the upland forest and is forced with auto and cross correlated synthetic stochastic wind speed, wind direction and water levels. The model incorporates key feedbacks between fetch, wave growth and subsequent lateral erosion rates and sediment supply to the marsh platform. Deposition of mineral sediment from the bay and/or internal ponds onto the marsh platform cells is dependent both on the inundation frequency and distance from a marsh edge. For each element along the transect, a Markov chain successional model was implemented that considers six distinct states, grass/saltmarsh, seedling, sapling, tree, dead standing tree, and bare. A non-static transition probability matrix, dependent on both inundation of the element and the prior vegetation state, was used in order to allow for feedbacks, both positive and negative, among different vegetation states and environmental drivers. The model was used to examine the qualitative behavior of the coupled systems under varied rates of sea level rise, external sediment supply, wind and storm statistics, tidal range, upland

  6. Elders Point East Marsh Island Restoration Monitoring Data Analysis

    Science.gov (United States)

    2017-09-21

    ER D C/ EL C R- 17 -1 Elders Point East Marsh Island Restoration Monitoring Data Analysis En vi ro nm en ta l L ab or at or y David...Point East Marsh Island Restoration Monitoring Data Analysis David S. Davis and David Yozzo HDR 1 International Boulevard Suite 1000 Mahwah, NJ...Engineers Washington, DC 20314-1000 Under Project #454750, “Elders Point East Marsh Island Restoration: Monitoring Data Analysis ” ERDC/EL CR-17-1 ii

  7. Modernity and putty-clay

    Science.gov (United States)

    Ganesh, Trichur Kailas

    This dissertation addresses issues arising out of the problems of capital accumulation, productivity growth and 'putty-clay' technology. The concept of economic modernity occupies a central place in the subject-matter studied here in that it expresses both the incessant drive for newness that characterizes economic reality and the persistence of dated techniques that successfully resist replacement. This study examines the way in which an expansive development-theoretic 'putty-clay' framework may be employed to explain the historical processes behind both the avalanche of newness (innovations) and the conservatism of technology in the U.S. economy. The guiding link is the fixity of investments in physical capital equipment over time and space. The dilemma of fixed capital is studied in the context of the constant entrepreneurial search for flexibility and liquidity. The thesis advanced is that a development (Entwicklung)-theoretic 'putty-clay' conceptualization of the economic system adequately addresses the recurring problems of fixity, flexibility, and liquidity, and thereby permits important insights into the enigma surrounding the persistent productivity growth slowdown and 'stagflation' of the late sixties and seventies and the related phenomena of physical 'capital obsolescence' and the financial or 'speculative explosions' of our times. The notion of 'putty-clay' used here is an innovative one in that it departs from the growth-theoretic literature to re-appear as a Schumpeterian theory of modernity modified by a Veblenite view of an economic system directed by the exigencies of the 'machine-process'. The empirical aptitude of a macroeconomic 'putty-clay' model to explain capital obsolescence mediated by the energy 'crises' (supply shocks) of the seventies and eighties is examined in a separate chapter with results that differ markedly from the standard (Berndt and Wood) conclusions for the U.S. economy. The final chapter in the dissertation reverts to the

  8. Wetland hydrology of the Elmley marshes

    OpenAIRE

    Gavin, H.

    2001-01-01

    Despite the importance of the hydrological regime for the functioning of wetland environments, the understanding of hydrological processes, particularly evaporative dynamics and clay soil moisture fluxes, is limited and the original research outlined in this thesis constitutes a real contribution to further the scientific understanding of wetland systems. Two lines of investigation are followed based upon field experiments and monitoring of groundwater and ditch water levels to...

  9. Habitat characteristics and eggshell distribution of the salt marsh mosquito, Aedes vigilax, in marshes in subtropical Eastern Australia.

    Science.gov (United States)

    Dale, Pat E R; Knight, Jon; Kay, Brian H; Chapman, Heather; Ritchie, Scott A; Brown, Michael D

    2008-01-01

    Research at 10 locations in coastal subtropical Queensland, Australia, has shown that salt marshes contained heterogeneous distributions of eggshells of the pest and vector mosquito Aedes vigilax (Skuse) (Diptera:Culicidae). The eggshell distribution was related to specific vegetation assemblages, with a mix of the grass, Sporobolus virginicus (L.) Kunth (Poales: Poaceae), and the beaded glasswort, Sarcocornia quinqueflora (Bunge ex (Ung.-Stern) A.J. Scott (Caryophyllales: Chenopodiaceae), as significantly higher in eggshells than any other vegetation. There were also high numbers in the mix of S. virginicus with the arrowgrass, Triglochin striata Ruiz & Pavón (Alismatales: Juncaginaceae). Both mixed types are found in relatively wetter areas, despite very few eggshells being found generally in the low marsh. Most sites contained S. virginicus and eggshell locations were variable for this species alone. This was probably related to its life form variability in response to salinity and location on the marsh. Location on the marsh was important for eggshell distribution with most eggshells around the edges of pools and depressions, followed by, but to a significantly lesser extent, the marsh surface. Eggshells were fewest in the low marsh. Partition analysis resulted in a tree that simplified and summarised the factors important for eggshell distribution confirming the individual analyses. The potential effects of climate, sea level and other change are also briefly discussed in the context of likely changes to land cover and relative location on the marsh. For example, increased sea level may lead to low marsh conditions extending into higher marsh area with implications for oviposition and numbers of eggshells.

  10. Assessing the Effects of Sea Level Rise on Plum Island Estuary Marshes Using a Hydrodynamic-marsh Modeling Tool

    Science.gov (United States)

    Demissie, H. K.; Bilskie, M. V.; Hagen, S. C.; Morris, J. T.; Alizad, K.

    2015-12-01

    Sea level rise (SLR) can significantly impact both human and ecological habitats in coastal and inland regions. Studies show that coastal estuaries and marsh systems are at the risk of losing their productivity under increasing rates of SLR (Donnelly and Bertness, 2001; Warren and Niering, 1993). The integrated hydrodynamic-marsh model (Hagen et al., 2013 & Alizad et al., 2015) uses a set of parameters and conditions to simulate tidal flow through the salt marsh of Plum Island Estuary, Massachusetts. The hydrodynamic model computes mean high water (MHW) and mean low water (MLW) and is coupled to the zero-dimensional Marsh Equilibrium Model (Morris et al. 2002) to estimate changes in biomass productivity and accretion. The coupled hydrodynamic-marsh model was used to examine the effects of different scenarios of SLR (Parris et al., 2012) on salt marsh productivity for the year 2100 in the Plum Island Estuary. In this particular study, responses of salt marsh production for different scenarios of SLR were compared. The study shows higher productivity of salt marsh under a low SLR scenario and lower productivity under the higher SLR. The study also demonstrates the migration of salt marshes under higher SLR scenarios. References: Alizad, K., S. C. Hagen, Morris, J.T., Bacopoulos, P., Bilskie, M.V., and John, F.W. 2015. A coupled, two-dimensional hydrodynamic-marsh model with biological feedback. Limnology and Oceanography, In review. Donnelly, J.P., and M.D. Bertness. 2001. Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise. Proceedings of the National Academy of Sciences 98: 14218-14223.Hagen, S.C., J.T. Morris, P. Bacopoulos, and J. Weishampel. 2013. Sea-Level Rise Impact on a Salt Marsh System of the Lower St. Johns River. ASCE Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 139, No. 2, March/April 2013, pp. 118-125.Morris, J.T., P.V. Sundareshwar, C.T. Nietch, B. Kjerfve, and D.R. Cahoon. 2002. Responses

  11. Stillwater Wildlife Management Area : Grasslands Management Plan : North Marsh Unit

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This plan is designed to serve as the initial Fish and Wildlife Service habitat management proposal for the North Marsh grazing unit of Stillwater National Wildlife...

  12. Salt Marshes of the Arctic National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this study was to map all salt marshes along the coastline of the Arctic National Wildlife Refuge, from the Canning River to the Canadian border....

  13. Marsh Survey Data 1991 - 1994 Seatuck National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a series of charts outlining and comparing the results of various marsh suveys that occurred at Seatuck National Wildlife Refuge between 1991 and 1994.

  14. Inventory and Monitoring Plan Big Branch Marsh National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Big Branch Marsh IMP was developed according to the Inventory and Monitoring (I 1) is an operational plan for one or more refuges that clearly states I 2)...

  15. Marsh Bird Monitoring Activities in Vermont in 1998

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Marsh bird studies performed in 1998 were primarily a continuation of the basic population monitoring started in previous years. A complete census of known black...

  16. Marsh and Water Management Plan : Clarence Cannon National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The marsh and water management plan outlines and describes management strategies for maintenance, rehabilitation, and development of managed waters on the Clarence...

  17. Prime Hook NWR Marsh Restoration Project Summary & Monitoring Plan 2015

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This living document provides a condensed explanation of wetland management history and a large-scale tidal marsh restoration project at Prime Hook NWR in Delaware....

  18. Marsh Bird Monitoring Activities in Vermont in 1999

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report outlines a continuation of the black tern monitoring which was initiated in 1990, as well as the marsh bird monitoring program which was started in 1996....

  19. Marsh Bird Monitoring Activities in Vermont in 1997

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Marsh bird studies performed in 1997 were primarily a continuation of the basic population monitoring started in previous years. A complete census of known black...

  20. Vegetation - Suisun Marsh, Change 1999 to 2000 [ds163

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  1. Investigations of Marsh Losses at Blackwater National Wildlife Refuge 1983

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A large body of scientific study over the last thirty years has resulted in ever increasing appreciation of the value of marshes and other wetlands as valuable...

  2. Preliminary survey of biodiversity in New Chicago Marsh

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — During the late winter and early springs 1995, we conducted a preliminary survey of biodiversity in New Chicago Marsh (NCM), at the south end of San Francisco Bay,...

  3. Big Branch Marsh National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Big Branch Marsh NWR for the next 15 years. This plan outlines the Refuge vision and...

  4. USFWS Salt Marsh Surface Elevation Table (SET) Data Analyses

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Most salt marshes are impacted to some extent by some type of anthropogenic alteration and are threatened by accelerated rates of sea-level. Understanding how best...

  5. Vegetation - Suisun Marsh, Change 1999 to 2003 [ds164

    Data.gov (United States)

    California Department of Resources — This vegetation mapping project of Suisun Marsh blends ground-based classification, aerial photo interpretation, and GIS editing and processing. The method is based...

  6. Ankeny - Peregrine Marsh Restoration: Reed Canary-Grass Restitution

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Peregrine Marsh will be a focal point of the Ankeny Hill Nature Center, a joint partnership between USFWS and Salem Audubon Society (SAS), which is a planned...

  7. Marsh and Water Management Plan: Trempealeau National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The objectives for marsh and water management on the Trempealeau NWR are: 1. to provide habitat for waterfowl, other migratory birds, and endangered or threatened...

  8. Hydrography - MO 2013 Outstanding Resource Waters - Marshes (SHP)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This feature class contains Missouri's Outstanding State Resource Waters - Marshes listed in Table E of the Water Quality Standards rule as published in the Code of...

  9. OMWM - Quality Mosquito Control on Cordgrass Salt Marshes

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Open marsh water management ( OMWM) has evolved from over twenty years of cooperative efforts between mosquito control and conservation agencies. Its beginning came...

  10. Marsh and Water Management Plan: Back Bay National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Back Bay National Wildlife Refuge Marsh and Water Management Plan has been developed to meet the station objectives set forth in the Master Plan. The purpose of...

  11. Wastewater effects on a waterhyacinth marsh and adjacent impoundment

    Science.gov (United States)

    Vega, Alberto; Ewel, Katherine Carter

    1981-11-01

    A waterhyacinth ( Eichhornia crassipes) marsh occupying two-thirds of the basin of a small Florida impoundment has received sewage effluent for nearly 20 years. Water from the marsh flows into an area that is maintained free of waterhyacinths, and is discharged through wells at the far end of the impoundment. A water budget for the basin was estimated, and phosphorus concentrations were measured monthly at three stations in the marsh and at the discharge wells in the lake. Productivity levels were measured monthly where the marsh joins the lake and at the discharge wells. Only 16% of the phosphorus that enters the basin is stored. Gross primary productivity levels in the open-water areas are very high (22 gO2m2day), but high respiration rates appear to keep the lake in steady-state.

  12. An inventory of wildlife resources, Marsh Fork, summer 1973

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Bureau of Sport Fisheries and Wildlife contracted us to do a wildlife resource inventory of the Marsh Fork in summer, 1973. We had planned the inventory in two...

  13. Some Biological Effects Of Ditching Tidewater Marshes Research Report 19

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Studies conducted over a 12-year period, 1935-47, of the biological effects of ditching tidewater marshes in Delaware for mosquito control showed that marked...

  14. Agassiz National Wildlife Refuge : Marsh and Water Management Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Marsh and Water Management Plan (MWMP) is intended to guide the management of Agassiz NWR wetlands into the twenty-first century. The foundation on which this...

  15. Thermal stability of PMMA–clay hybrids

    Indian Academy of Sciences (India)

    Tanushree Choudhury; Nirendra M Misra

    2010-04-01

    Materials with small particle size are being extensively used in composites and hybrid materials. Exfoliated clay–polymer hybrids show enhanced properties. Exfoliation of clay platelets can be affected by selecting dispersing agents. In the present work, clay dispersed by natural dispersant (soap stone powder), cetyl trimethyl ammonium bromide (CTAB) dispersed clay and acid clay (amorphous clay) are taken. They are then polymerized with poly methyl methacrylate (PMMA) by solution intercalation method. The thermal stability of these different clay–PMMA hybrids have been studied and compared with that of pure PMMA by differential scanning calorimeter (DSC). The bonding of clay with PMMA has been studied by IR. Morphology of clay–PMMA hybrids has been shown by SEM and XRD which indicate partially exfoliated structure in T606-4 and intercalated structures in T606-6 and T606-2.

  16. Storminess helps coastal marshes withstand sea level rise

    Science.gov (United States)

    Balcerak, Ernie

    2013-03-01

    Rising sea levels are predicted to threaten many coastal sea marshes around the world in the coming decades as the Earth's climate warms. In addition to accelerating sea level rise, global climate change is predicted to increase the frequency and severity of storms in many places around the world. However, few studies have taken into account how an increased storminess might affect the ability of coastal marshes to withstand sea level rise.

  17. Birds of Swale Marshes on John F. Kennedy Space Center

    Science.gov (United States)

    Breininger, David R.

    1992-01-01

    Birds were surveyed in several isolated freshwater wetlands on John F. Kennedy Space Center to determine species composition and the importance of these wet- lands to birds. The Red-winged Blackbird and Green-backed Heron were the two most abundant breeders in the swale marshes. The Common Yellowthroat was the most common winter resident but was rare in summer. These marshes are important features within landscapes dominated by uplands particularly because of their significance to amphibians and reptiles.

  18. Mars, clays and the origins of life

    Science.gov (United States)

    Hartman, Hyman

    1989-01-01

    To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

  19. Mangrove expansion and salt marsh decline at mangrove poleward limits.

    Science.gov (United States)

    Saintilan, Neil; Wilson, Nicholas C; Rogers, Kerrylee; Rajkaran, Anusha; Krauss, Ken W

    2014-01-01

    Mangroves are species of halophytic intertidal trees and shrubs derived from tropical genera and are likely delimited in latitudinal range by varying sensitivity to cold. There is now sufficient evidence that mangrove species have proliferated at or near their poleward limits on at least five continents over the past half century, at the expense of salt marsh. Avicennia is the most cold-tolerant genus worldwide, and is the subject of most of the observed changes. Avicennia germinans has extended in range along the USA Atlantic coast and expanded into salt marsh as a consequence of lower frost frequency and intensity in the southern USA. The genus has also expanded into salt marsh at its southern limit in Peru, and on the Pacific coast of Mexico. Mangroves of several species have expanded in extent and replaced salt marsh where protected within mangrove reserves in Guangdong Province, China. In south-eastern Australia, the expansion of Avicennia marina into salt marshes is now well documented, and Rhizophora stylosa has extended its range southward, while showing strong population growth within estuaries along its southern limits in northern New South Wales. Avicennia marina has extended its range southwards in South Africa. The changes are consistent with the poleward extension of temperature thresholds coincident with sea-level rise, although the specific mechanism of range extension might be complicated by limitations on dispersal or other factors. The shift from salt marsh to mangrove dominance on subtropical and temperate shorelines has important implications for ecological structure, function, and global change adaptation.

  20. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    Science.gov (United States)

    Miller, Sandi G (Inventor)

    2013-01-01

    A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

  1. Ceramic clays from the western part of the Tamnava Tertiary Basin, Serbia: Deposits and clay types

    Directory of Open Access Journals (Sweden)

    Radosavljević Slobodan

    2014-01-01

    Full Text Available Based on geological, mineralogical, physical, chemical and technological investigations in the Tamnava Tertiary Basin near Šabac town (western Serbia, deposits of ceramic clays were studied. These ceramic clays are composed of kaolin-illite with a variable content of quartz, feldspars, mica, iron oxides and hydroxides, and organic matter. Four main types of commercial clays were identified: i red-yellow sandy-gravely (brick clays; ii grey-white poor sandy (ceramic clays; iii dark-carbonaceous (ceramic clays; and iv lamellar (“interspersed” fatty, poor sandy (highly aluminous and ferrous clays. Ceramic clays are defined as medium to high plastic with different ranges of sintering temperatures, which makes them suitable for the production of various kinds of materials in the ceramic industry. [Projekat Ministarstva nauke Republike Srbije, br. OI-176016

  2. Membrane behavior of clay liner materials

    Science.gov (United States)

    Kang, Jong Beom

    Membrane behavior represents the ability of porous media to restrict the migration of solutes, leading to the existence of chemico-osmosis, or the flow of liquid in response to a chemical concentration gradient. Membrane behavior is an important consideration with respect to clay soils with small pores and interactive electric diffuse double layers associated with individual particles, such as bentonite. The results of recent studies indicate the existence of membrane behavior in bentonite-based hydraulic barriers used in waste containment applications. Thus, measurement of the existence and magnitude of membrane behavior in such clay soils is becoming increasingly important. Accordingly, this research focused on evaluating the existence and magnitude of membrane behavior for three clay-based materials that typically are considered for use as liners for waste containment applications, such as landfills. The three clay-based liner materials included a commercially available geosynthetic clay liner (GCL) consisting of sodium bentonite sandwiched between two geotextiles, a compacted natural clay known locally as Nelson Farm Clay, and compacted NFC amended with 5% (dry wt.) of a sodium bentonite. The study also included the development and evaluation of a new flexible-wall cell for clay membrane testing that was used subsequently to measure the membrane behaviors of the three clay liner materials. The consolidation behavior of the GCL under isotropic states of stress also was evaluated as a preliminary step in the determination of the membrane behavior of the GCL under different effective consolidation stresses.

  3. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Michael Rajamathi; Grace S Thomas; P Vishnu Kamath

    2001-10-01

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange properties together with surface basicity making them materials of importance for many modern applications. In this article, we discuss many different ways of making anionic clays and compare and contrast the rich diversity of this class of materials with the better-known cationic clays.

  4. Probing the water interactions in clay

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.H. [Lausanne Univ., Lausanne (Switzerland); Fischer, H.E. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Skipper, N.T. [Univ. College, London (United Kingdom)

    1999-11-01

    Clays, the microscopic mineral fraction of soils, are probably the most important substrate for interactions between water, the mineral world and the biosphere. A knowledge of the structuring of water and hydrated metal ions near clays surfaces is of importance in environmental science, including toxic and radioactive waste disposal, and in the industrial application of clays. The smectite clays, with their large hydrated internal surface areas represent excellent model systems for the interactions of aqueous phases with solid surface. We present the results of neutron diffraction experiments using isotopic substitutions to probe the structure in the aqueous interlayer region of Li-montmorillonite. (authors) 6 refs., 3 figs.

  5. Anthropogenic Impacts on the Evolution of Estuarine Fringe-marsh Shorelines: Implications of Coastal Setting on Marsh Sustainability

    Science.gov (United States)

    Mattheus, C. R.; Rodriguez, A. B.; McKee, B. A.; Currin, C.

    2009-12-01

    Fringe marshes, which are common to estuarine shorelines, provide essential ecosystem services to coastal regions, including carbon sequestration, provision of shelter and nursery grounds for aquatic and terrestrial animals, and buffering of lowland areas from marine flooding. Thousands of acres of intertidal wetlands are lost each year in the U.S., in part due to a recent acceleration in the rate of sea-level rise. The ability of a marsh to sustain itself by vertical accretion is generally limited by inorganic sediment supply. Despite a continuing global population boom, models attempting to forecast marsh response to future sea-level rise do not take land-use changes into account, which have the potential to alter sediment sources and modify or disrupt established sediment pathways. This study investigates how landscape modifications can alter nearshore sedimentation regimes and influence marsh-edge evolution. Marshes in this study are located in similar hydrologic and geographic settings within coastal North Carolina and have comparable vegetation densities; however, their respective coastal environments are affected by different land-use modifications. Site A is situated within an upper bay environment, whereas Site B is located along the estuarine shoreline of a barrier island. Both sites are part of the same estuarine system. Marsh-shoreline positions and surface elevations were monitored at the sites over a two-year period using high-resolution terrestrial LIDAR. This data set was supplemented with accretion rates obtained from radioisotope analysis, precipitation records, and information on land-use changes in an effort to develop an understanding of their effect on marsh evolution. The study region has undergone significant land-use changes, including the introduction of tree farming in the lower reaches of a tributary creek to the upper bay. Widespread deforestation in this watershed led to increased upland erosion and higher sediment-supply rates to the

  6. Restoring marsh elevation in a rapidly subsiding salt marsh by thin-layer deposition of dredged material

    Science.gov (United States)

    Ford, M.A.; Cahoon, D.R.; Lynch, J.C.

    1999-01-01

    Thin-layer deposition of dredged material on coastal marsh by means of high-pressure spray dredging (Jet-Spray??2) technology has been proposed as a mechanism to minimize wetland impacts associated with traditional bucket dredging technologies and to restore soil elevations in deteriorated marshes of the Mississippi River delta. The impact of spray dredging on vegetated marsh and adjacent shallow-water habitat (formerly vegetated marsh that deteriorated to open water) was evaluated in a 0.5-ha Spartina alterniflora-dominated salt marsh in coastal Louisiana. The thickness of dredged sediment deposits was determined from artificial soil marker horizons and soil elevation change was determined from sedimentation-erosion tables (SET) established prior to spraying in both sprayed and reference marshes. The vertical accretion and elevation change measurements were made simultaneously to allow for calculation of shallow (~5 m depth) subsidence (accretion minus elevation change). Measurements made immediately following spraying in July 1996 revealed that stems of S. alterniflora were knocked down by the force of the spray and covered with 23 mm of dredged material. Stems of S. alterniflora soon recovered, and by July 1997 the percent cover of S. alterniflora had increased three-fold over pre-project conditions. Thus, the layer of dredged material was thin enough to allow for survival of the S. alterniflora plants, with no subsequent colonization by plant species typical of higher marsh zones. By February 1998, 62 mm of vertical accretion accumulated at this site, and little indication of disturbance was noted. Although not statistically significant, soil elevation change was greater than accretion on average at both the spray and reference marshes, suggesting that subsurface expansion caused by increased root biomass production and/or pore water storage influence elevation in this marsh region. In the adjacent shallow water pond, 129 mm of sediment was deposited in July

  7. Vegetation Influences on Tidal Freshwater Marsh Sedimentation and Accretion

    Science.gov (United States)

    Cadol, D. D.; Elmore, A. J.; Engelhardt, K.; Palinkas, C. M.

    2011-12-01

    Continued sea level rise, and the potential for acceleration over the next century, threatens low-lying natural and cultural resources throughout the world. In the national capital region of the United States, for example, the National Park Service manages over 50 km^2 of land along the shores of the tidal Potomac River and its tributaries that may be affected by sea level rise. Dyke Marsh Wildlife Preserve on the Potomac River south of Washington, DC, is one such resource with a rich history of scientific investigation. It is a candidate for restoration to replace marsh area lost to dredging in the 1960s, yet for restoration to succeed in the long term, accretion must maintain the marsh surface within the tidal range of rising relative sea level. Marsh surface accretion rates tend to increase with depth in the tidal frame until a threshold depth is reached below which marsh vegetation cannot be sustained. Suspended sediment concentration, salinity, tidal range, and vegetation community all influence the relationship between depth and accretion rate. The complex interactions among these factors make sedimentation rates difficult to generalize across sites. Surface elevation tables (SET) and feldspar marker horizons have been monitored at 9 locations in Dyke Marsh for 5 years, providing detailed data on sedimentation, subsidence, and net accretion rates at these locations. We combine these data with spatially rich vegetation surveys, a LiDAR derived 1-m digital elevation model of the marsh, and temperature-derived inundation durations to model accretion rates across the marsh. Temperature loggers suggest a delayed arrival of tidal water within the marsh relative to that predicted by elevation alone, likely due to hydraulic resistance caused by vegetation. Wave driven coastal erosion has contributed to bank retreat rates of ~2.5 m/yr along the Potomac River side of the marsh while depositing a small berm of material inland of the retreating shoreline. Excluding sites

  8. Sea-level Rise Impacts on Hudson River Marshes and their Vegetation Zonation

    Science.gov (United States)

    Hooks, A.; Nitsche, F. O.

    2016-12-01

    Rising sea levels may cause tidal marshes to be vulnerable to submergence and affect their ability to perform ecosystem services. However, tidal marshes are dynamic ecosystems that can adapt to sea-level rise through inland migration and vertical growth. This study examines how four tidal marshes on the Hudson River (Piermont Marsh, Iona Island Marsh, Tivoli Bays, and Stockport Flats) would be affected by 0.5m, 1m, and 1.5m of sea-level rise by 2100. Using high-resolution LiDAR elevation data and vegetation data, we mapped sea-level rise projections in GIS, accounting for current accretion rates unique to each marsh. We calculated the submerged area of each marsh and analyzed how vegetation zonation in each marsh is expected to change due to rising sea levels. We found that the steep topography of the Hudson River banks limits the marshes' ability to migrate inland, emphasizing the role of elevation-building processes in adaptation. The marshes studied would experience minimal to no inundation under lower rates of sea-level rise such as 0.5m by 2100. At higher projected rates of sea-level rise (1.5m by 2100), Piermont Marsh and Tivoli Bays would experience significant inundation while Iona Island marsh and Stockport Flats would be less affected. Overall, Stockport Flats is projected to be the marsh most resilient to sea-level rise due to its higher accretion rate and its topography. Rising sea levels are also expected to change the areas of vegetation zones, with upland, high marsh, and mid marsh zones generally declining in area and with subtidal and low marsh vegetation zones generally expanding under high rates of sea-level rise. Understanding the impacts of sea-level rise on Hudson River marshes enables long-term planning to adapt to potential changes in marsh ecosystem services and could motivate and inform conservation efforts.

  9. Vertical distribution of Al, Cu, Fe and Zn in the soil salt marshes of the Sado estuary, Portugal

    Energy Technology Data Exchange (ETDEWEB)

    Reboredo, F.H.S.; Ribeiro, C.A.G.

    1984-01-01

    The vertical distribution of Al, Cu, Fe and Zn in the soil salt marsh of the river Sado estuary was studied. The results obtained by an acid digestion procedure, indicate that the mean values at the first sampling point (near the Atlantic Ocean and very close to a populous city) are lower when compared with those found at the other Stations (approximately 8.0 and 20.0 km upstream), where they are very similar. These findings are related to the different nature of the soil matrix (essentially sand at Station 1 and silt-clay at Station 2 and 3), and the reduced availability of the sandy fraction to bind trace metals. A correlation analysis for all the metals in different soil cores indicate that the correlation values at Station 1 are, generally, not significant. 4 tables.

  10. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    has been evaluated using standardised methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15 to 0.3m thick clay membrane have been tested...... successfully. At natural watercontent w = 40 to 45% it is possible to establish a homogeneous membrane with hydraulic conductivity k tests used for establishing swell and deformation properties showed...... to be very dependent on the stress level. It varies from k = E-11 to 2 E-13 m/s at vertical stresses from 5 to 4800 kPa and is clearly related to a reduced effective porosity diminishing with stress. Preliminary diffusion tests indicate a similar influence on the effective diffusion coefficient being much...

  11. Intraspecific variation in growth of marsh macrophytes in response to salinity and soil type: Implications for wetland restoration

    Science.gov (United States)

    Howard, R.J.

    2010-01-01

    Genetic diversity within plant populations can influence plant community structure along environmental gradients. In wetland habitats, salinity and soil type are factors that can vary along gradients and therefore affect plant growth. To test for intraspecific growth variation in response to these factors, a greenhouse study was conducted using common plants that occur in northern Gulf of Mexico brackish and salt marshes. Individual plants of Distichlis spicata, Phragmites australis, Schoenoplectus californicus, and Schoenoplectus robustus were collected from several locations along the coast in Louisiana, USA. Plant identity, based on collection location, was used as a measure of intraspecific variability. Prepared soil mixtures were organic, silt, or clay, and salinity treatments were 0 or 18 psu. Significant intraspecific variation in stem number, total stem height, or biomass was found in all species. Within species, response to soil type varied, but increased salinity significantly decreased growth in all individuals. Findings indicate that inclusion of multiple genets within species is an important consideration for marsh restoration projects that include vegetation plantings. This strategy will facilitate establishment of plant communities that have the flexibility to adapt to changing environmental conditions and, therefore, are capable of persisting over time. ?? Coastal and Estuarine Research Federation 2009.

  12. Flow, sedimentation, and biomass production on a vegetated salt marsh in South Carolina: toward a predictive model of marsh morphologic and ecologic evolution

    Science.gov (United States)

    Fagherazzi, S.; Mudd, S. M.; Morris, J. T.; Furbish, D. J.

    2004-12-01

    A 1-D model for exploring the interaction between hydrodynamics, sedimentation, and plant community evolution on a salt marsh populated by Spartina alterniflora is developed. In the model tidally induced flows over marsh platforms are affected by S. alterniflora through drag forces. In general macrophyte characteristics are determined by a wide range of processes; here, based on field studies at North Inlet estuary, South Carolina, the biomass of the S. alterniflora on the marsh platform is simply related to their time of submergence under tidally induced flows. Additionally, field data collected at North Inlet are used to relate biomass to plant area per unit volume, stem diameter, and an empirical drag coefficient. Sedimentation is also related to biomass, through either organogenic deposition or trapping of suspended sediment particles. The morphologic evolution of simulated marshes is explored by varying the sedimentation process and the rate of sea level rise. Different sedimentation processes result in marshes with different morphologies. An organogenic marsh is predicted to evolve under a regime of steady sea level rise into a platform with a relatively flat surface, whereas a marsh developed primarily through a trapping mechanism is predicted to have a surface that slopes gently away from the salt marsh creek. As predicted by 0-D modeling studies, sea level rise may be accommodated up to a certain critical sea level rise rate, after which the salt marsh platform will drown. Marshes that accrete through sediment trapping adjust to changes in sea level more rapidly than marshes that accrete through organogenic deposition.

  13. Salt-Marsh Landscapes and the Signatures of Biogeomorphic Feedbacks

    Science.gov (United States)

    D'Alpaos, A.; Marani, M.

    2014-12-01

    Salt marshes are coastal ecosystems which play a large role in the bio-geomorphological evolution of intertidal areas. The dense stands of halophytic plants which populate salt-marsh systems largely contribute to govern their dynamics, influencing marsh hydrodynamics and sediment transport through enhanced flow resistance and settling, and direct particle capture by plant stems. In addition, plants are known to increase vertical accretion through direct organic accretion. Looking across the salt-marsh landscape can one see the signatures of feedbacks between landscape and biota? Field evidence and the results of biomorphodynamic models indeed show that the interplay between physical and biological processes generates some striking biological and morphological patterns at different scales. One such pattern, vegetation zonation, consists in a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. Here we extend the model proposed by Marani et al. (2013) to a two-dimensional framework, furthermore including the effect of direct capture of sediment particles by plant stems. This allows us to account for the effect of the drainage density of tidal networks on the observed biogeomorphic patterns and to model the coupled evolution of marsh platforms and channel networks cutting through them. A number of different scenarios have been modelled to analyze the changes induced in bio-geomorphic patterns by plants with different characteristics, within marshes characterized by different drainage densities, or subjected to changing environmental forcing such as rates of relative sea level rise and sediment supply. Model results emphasize that zonation patterns are a signature of bio-geomorphic feedbacks with vegetation acting as a landscape constructor which feeds back on, directly alters, and contributes to shape tidal environments. In addition, model results show that

  14. Painting with Clay Van Gogh Style.

    Science.gov (United States)

    Skophammer, Karen

    1999-01-01

    Discusses Vincent Van Gogh's painting "Starry Night" and describes a lesson where fifth- and sixth-grade students created their own version of the artwork. Explains that the students utilized four colors of Permoplast clay, using their hands and fingers as brushes and blending tools and the clay as paint. (CMK)

  15. Sectioning Clay Models Makes Anatomy & Development Tangible

    Science.gov (United States)

    Howell, Carina Endres; Howell, James Endres

    2010-01-01

    Clay models have proved to be useful teaching aids for many topics in biology that depend on three-dimensional reasoning. Students studying embryonic development struggle to mentally reconstruct the three-dimensional structure of embryos and larvae by observing prepared slides of cross-sectional slices. Students who build clay models of embryos…

  16. Quick clay and landslides of clayey soils

    NARCIS (Netherlands)

    Khaldoun, A.; Moller, P.; Fall, A.; Wegdam, G.; de Leeuw, B.; Méheust, Y.; Fossum, J.O.; Bonn, D.

    2009-01-01

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay s

  17. Moessbauer Spectra of Clays and Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, F. E.; Wagner, U. [Technische Universitaet Muenchen (Germany)

    2004-06-15

    The physical, chemical and mineralogical aspects of the use of Moessbauer spectroscopy in studies of clay-based ceramics are described. Moessbauer spectra of pottery clays fired under oxidising, reducing and changing conditions are explained, and the possibilities of using Moessbauer spectra to derive information on the firing temperatures and the kiln atmosphere during firing in antiquity are discussed and illustrated by examples.

  18. Dehydration-induced luminescence in clay minerals

    Science.gov (United States)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  19. Active containment systems incorporating modified pillared clays

    Energy Technology Data Exchange (ETDEWEB)

    Lundie, P. [Envirotech (Scotland) Ltd., Aberdeen (United Kingdom)]|[Environmental Resource Industries Disposal Pty Ltd., Perth (Australia); McLeod, N. [Envirotreat Ltd., Kingswinford (United Kingdom)

    1997-12-31

    The application of treatment technologies in active containment systems provides a more advanced and effective method for the remediation of contaminated sites. These treatment technologies can be applied in permeable reactive walls and/or funnel and gate systems. The application of modified pillared clays in active containment systems provides a mechanism for producing permeable reactive walls with versatile properties. These pillared clays are suitably modified to incorporate reactive intercalatants capable of reacting with both a broad range of organic pollutants of varying molecular size, polarity and reactivity. Heavy metals can be removed from contaminated water by conventional ion-exchange and other reactive processes within the clay structure. Complex contamination problems can be addressed by the application of more than one modified clay on a site specific basis. This paper briefly describes the active containment system and the structure/chemistry of the modified pillared clay technology, illustrating potential applications of the in-situ treatment process for contaminated site remediation.

  20. Permeation properties of polymer/clay nanocomposites

    Science.gov (United States)

    Kalendova, A.; Merinska, D.; Gerard, J. F.

    2012-07-01

    The important characteristics of polymer/clay nanocomposites are stability, barrier properties and in the case of polyvinyl chloride also plasticizer migration into other materials. Therefore, the permeation properties of polymer/clay nanocomposites are discussed in this paper. The attention was focused to the polyethylene (PE) and polyvinyl chloride (PVC). Natural type of montmorillonite MMTNa+ and modified types of montmorillonite from Southern Clay Products were used as the inorganic phase. As the compounding machine, one screw Buss KO-kneader was employed. The principal aim is to fully exfoliate the clay into polymer matrix and enhanced the permeation properties. Prepared samples were tested for O2 and CO2 permeability. Polymer/clay nanocomposite structure was determined on the base of X-ray diffraction and electron microscopy (TEM).

  1. 1st International Conference on Calcined Clays for Sustainable Concrete

    CERN Document Server

    Favier, Aurélie

    2015-01-01

    This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

  2. Clay Dispersibility and Soil Friability-Testing the Soil Clay-to-Carbon Saturation Concept

    DEFF Research Database (Denmark)

    Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl;

    2012-01-01

    Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates either air......-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor effects on clay...

  3. Mineralogy and geotechnical characteristics of some pottery clay

    OpenAIRE

    Mujib Olamide ADEAGBO; Samuel Akinlabi OLA; Olumide Oluwapelumi OJURI

    2016-01-01

    The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-...

  4. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Marin Islands NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Marin...

  5. Salt Marsh Integrity Vegetation Data at Cape May and Supawna Meadows National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  6. Salt Marsh Integrity Vegetation Data at Rachel Carson National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  7. Salt Marsh Integrity Nekton Data at Rachel Carson National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  8. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Rappahannock NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  9. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Bayou Sauvage NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Bayou...

  10. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Mashpee NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  11. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Back Bay NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Back...

  12. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Cedar Keys NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Cedar...

  13. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Breton NWR [Draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  14. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Archie Carr NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  15. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Chassahowitzka NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  16. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Grand Bay NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Grand...

  17. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Blackwater NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  18. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Cedar Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Cedar...

  19. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Harris Neck NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  20. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Pine Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Pine...

  1. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Delta NWR : Revised [Draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Delta...

  2. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Currituck NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  3. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Nansemond NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  4. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Blackbeard Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  5. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Guam NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Guam...

  6. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Bombay Hook NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  7. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Amagansett NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  8. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Wolf Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Wolf...

  9. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Monomoy NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  10. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Potomac River NWR Complex

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  11. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Hobe Sound NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Hobe...

  12. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to St. Marks NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on St....

  13. Bandon Marsh National Wildlife Refuge interim monitoring: Fall 2010 - spring 2011

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Bandon Marsh National Wildlife Refuge is in the process of conducting a large-scale tidal marsh restoration project on the Ni-les’tun Unit, within the Coquille River...

  14. A RAPID NON-DESTRUCTIVE METHOD FOR ESTIMATING ABOVEGROUND BIOMASS OF SALT MARSH GRASSES

    Science.gov (United States)

    Understanding the primary productivity of salt marshes requires accurate estimates of biomass. Unfortunately, these estimates vary enough within and among salt marshes to require large numbers of replicates if the averages are to be statistically meaningful. Large numbers of repl...

  15. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to John Heinz NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on John...

  16. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Edwin B. Forsythe NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Edwin...

  17. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Swanquarter NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  18. [Quivira National Wildlife Refuge water quality data : Big and Little Salt Marsh, June 1991

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Water quality results from samples taken June 18th, 1991 at Quivira National Wildlife Refuge from Big Salt Marsh, Little Salt Marsh, and from a small wetland pool...

  19. A Climate Change Adaptation Strategy for Management of Coastal Marsh Systems

    Science.gov (United States)

    Sea level rise is causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat for fish, shellfish, and wildlife, includin...

  20. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Pinckney Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  1. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Pelican Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  2. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Moosehorn NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  3. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Crocodile Lake NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  4. Salt Marsh Integrity Nekton Data at Cape May and Supawna National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  5. Salt Marsh Integrity Bird Data at Cape May and Supawana Meadows National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Salt Marsh Integrity (SMI) project involves monitoring several salt marsh metrics such as: historical condition and geomorphic setting; ditch density;...

  6. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Merritt Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  7. Tidal Marsh Inventory for York County Virginia and town of Poquoson

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This inventory report and marsh guidelines study will explain marsh vegetation types and their evaluation throughout York County Virginia and the town of Poquoson....

  8. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Cape May NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Cape...

  9. Below the Disappearing Marshes of an Urban Estuary ...

    Science.gov (United States)

    Marshes in the urban Jamaica Bay Estuary, New York, USA are disappearing at an average rate of 13 ha/yr, and multiple stressors (e.g., wastewater inputs, dredging activities, groundwater removal, and global warming) may be contributing to marsh losses. Among these stressors, wastewater nutrients are suspected to be an important contributing cause of marsh deterioration. We used census data, radiometric dating, stable nitrogen isotopes, and soil surveys to examine the temporal relationships between human population growth and soil nitrogen; and we evaluated soil structure with computer-aided tomography, surface elevation and sediment accretion trends, carbon dioxide emissions, and soil shear strength to examine differences among disappearing (Black Bank and Big Egg) and stable marshes (JoCo). Radiometric dating and nitrogen isotope analyses suggested a rapid increase in human wastewater nutrients beginning in the late 1840s, and a tapering off beginning in the 1930s when wastewater treatment plants (WWTPs) were first installed. Current WWTPs nutrient loads to Jamaica Bay are approximately 13 995 kg N/d and 2767 kg P/d. At Black Bank, the biomass and abundance of roots and rhizomes and percentage of organic matter on soil were significantly lower, rhizomes larger in diameter, carbon dioxide emission rates and peat particle density significantly greater, and soil strength significantly lower compared to the stable JoCo Marsh, suggesting Black Bank has elevated d

  10. Effects of long-term grazing on sediment deposition and salt-marsh accretion rates

    OpenAIRE

    Elschot, K.; Bouma, T.J.; Temmerman, S.; J. P. Bakker

    2013-01-01

    Many studies have attempted to predict whether coastal marshes will be able to keep up with future acceleration of sea-level rise by estimating marsh accretion rates. However, there are few studies focussing on the long-term effects of herbivores on vegetation structure and subsequent effects on marsh accretion. Deposition of fine-grained, mineral sediment during tidal inundations, together with organic matter accumulation from the local vegetation, positively affects accretion rates of marsh...

  11. THE EFFECT OF CLAY DISPERSION ON THE CRYSTALLIZATION AND MORPHOLOGY OF POLYPROPYLENE/CLAY COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Qin Zhang; Xiao-lin Gao; Ke Wang; Qiang Fu

    2004-01-01

    PP/clay composites with different dispersions, namely, exfoliated dispersion, intercalated dispersion and agglomerates and panicle-like dispersion, were prepared by direct melt intercalation or compounding. The effect of clay dispersion on the crystallization and morphology of PP was investigated via PLM, SAXS and DSC. Experimental results show that exfoliated clay layers are much more efficient than intercalated clay and agglomerates of clay in serving as nucleation agent due to the nano-scale dispersion of clay, resulting in a dramatic decrease in crystal size (lamellar thickness and spherulites) and an increase of crystallization temperature and crystallization rate. On the other hand, a decrease of melting temperature and crystallinity was also observed in PP/clay composites with exfoliated dispersion, due to the strong interaction between PP and clay. Compared with exfoliated clay layers, the intercalated clay layers have a less important effect on the crystallization and crystal morphology. No effect is seen for samples with agglomerates and panicle-like dispersion, in regard to melting temperature, crystallization temperature, crystal thickness and crystallinity.

  12. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    NARCIS (Netherlands)

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive acceler

  13. The impact of sheep grazing on net nitrogen mineralization rate in two temperate salt marshes

    NARCIS (Netherlands)

    Kiehl, K; Esselink, Peter; Gettner, S; Bakker, JP

    2001-01-01

    Nitrogen mineralization rate was studied in grazing trials with three different stocking rates (0, 3, 10 sheep ha(-1)) in two man-made salt marshes, viz. a Puccinellia maritima-dominated low salt marsh and a high salt marsh dominated by Festuca rubra. Mineralization rates were derived from the amoun

  14. 75 FR 73121 - Bandon Marsh, Nestucca Bay, and Siletz Bay National Wildlife Refuges, Coos, Tillamook, and...

    Science.gov (United States)

    2010-11-29

    ... of Neskowin, Oregon. Neskowin Marsh incorporates unique freshwater wetland and bog habitats and... Fish and Wildlife Service Bandon Marsh, Nestucca Bay, and Siletz Bay National Wildlife Refuges, Coos... prepare a comprehensive conservation plan (CCP) for the Bandon Marsh, Nestucca Bay, and Siletz...

  15. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    NARCIS (Netherlands)

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive

  16. Man's Impact on the Environment: The Freshwater Marsh as an Ecosystem.

    Science.gov (United States)

    Brevard County School Board, Cocoa, FL.

    This teaching guide deals with the ecological composition of a marsh and the ecological effects certain changes might have on a marsh. This study focuses on the fresh water marsh found in the Florida Everglades which can furnish the student with several examples of past, present, and possible future ecological changes which impact this ecosystem.…

  17. Environmental assessment of Al-Hammar Marsh, Southern Iraq

    Directory of Open Access Journals (Sweden)

    Hind Fadhil Abdullah Al-Gburi

    2017-02-01

    Discussion and conclusions: Decreasing of Tigris and Euphrates discharges during the past decades due to drought conditions and upstream damming, as well as the increasing stress of wastewater effluents from anthropogenic activities, led to degradation of the downstream Al-Hammar Marsh water quality in terms of physical, chemical, and biological properties. As such properties were found to consistently exceed the historical and global quality objectives. However, element concentration decreasing trend at the marsh outlet station compared to other stations indicate that the marsh plays an important role as a natural filtration and bioremediation system. Higher element concentrations in winter were due to runoff from the washing of the surrounding Sabkha during flooding by winter rainstorms. Finally, the high concentrations of heavy metals in fish samples can be attributed to bioaccumulation and biomagnification processes.

  18. Some Tests on Heather Field Moraine Clay

    DEFF Research Database (Denmark)

    Jørgensen, Mogens B.; Jacobsen, Moust

    This report deals with oedometer tests on three samples of moraine clay from the Heather Field in the English part of the North Sea. The tests have been carried out in the very unelastic apparatus used in Denmark and with special test procedures differing from the ones used elsewhere. In Denmark...... the English North Sea moraine clays with the corresponding Danish Moraine Clays. The Danish test procedures are explained in details and some comments are given in the hope that they may not be banalities all of them....

  19. Ni clay neoformation on montmorillonite surface.

    Science.gov (United States)

    Dähn, R; Scheidegger, A; Manceau, A; Schlegel, M; Baeyens, B; Bradbury, M H

    2001-03-01

    Polarized extended X-ray absorption fine structure spectroscopy (P-EXAFS) was used to study the sorption mechanism of Ni on the aluminous hydrous silicate montmorillonite at high ionic strength (0.3 M NaClO4), pH 8 and a Ni concentration of 0.66 mM. Highly textured self-supporting clay films were obtained by slowly filtrating a clay suspension after a reaction time of 14 days. P-EXAFS results indicate that sorbed Ni has a Ni clay-like structural environment with the same crystallographic orientation as montmorillonite layers.

  20. Signatures of Biogeomorphic Feedbacks in Salt-Marsh Systems

    Science.gov (United States)

    D'Alpaos, Andrea; Marani, Marco

    2015-04-01

    Salt-marsh ecosystems which play a large role in the bio-geomorphological evolution of intertidal areas. Dense stands of halophytic vegetations which populate salt marshes largely control the dynamics of these ecosystems influencing marsh hydrodynamics and sediment transport through enhanced flow resistance and settling, and direct particle capture by plant stems. Moreover, plants are also known to increase vertical accretion through direct organic accretion. Field evidence and the results of biomorphodynamic models indeed show that the interplay between physical and biological processes generates some striking biological and morphological patterns at different scales. One such pattern, vegetation zonation, consists in a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. Here we develop a two-dimensional model which describes the mutual interaction and adjustment between tidal flows, sediment transport and morphology mediated by vegetation influence. The model allows us describe the coupled evolution of marsh platforms and channel networks cutting through them. A number of different scenarios were modelled to analyze the changes induced in bio-geomorphic patterns by plants with different characteristics, within marshes characterized by different drainage densities, or subjected to changing environmental forcing such as rates of relative sea level rise and sediment supply. Model results emphasize that zonation patterns are a signature of bio-geomorphic feedbacks with vegetation acting as a landscape constructor which feeds back on, directly alters, and contributes to shape tidal environments. In addition, model results show that biogeomorphic feedbacks critically affect the response and the resilience of salt-marsh landscapes to changes in the environmental forcing.

  1. A Baseline Study of Piermont Marsh as Nekton Habitat

    Science.gov (United States)

    Ortega, M.; Bloomfield, F.; Torres, T.; Ward, J.; Sanders, D.; Lobato, A.

    2011-12-01

    Between 2007 and 2011 we have conducted a study of fish populations and water quality in the Piermont Marsh, a brackish tidal wetland about 40 km north of Manhattan. This 5-year period represents the baseline for an ongoing ecological study of the marsh. The marsh, along with similar wetlands between the Federal Dam at Troy and the Battery, is an important refuge for juvenile fish, and it is believed that estuarine wetland dynamics are critical in population recruitment for coastal fisheries. Piermont Marsh has undergone a rapid transition from a primarily Spartina alternaflora and Spartina pattens setting to one dominated by an invasive genotype of common reed Phragmites australis. The impact of this shift on local fish populations, species diversity, and adult recruitment are not well understood. The long term goal of this study is to tease apart factors in by use of the marsh as a nekton habitat. Fish were collected in unbaited minnow gee traps which were deployed at slack tide and left for 24 hours. Samples were preserved in 10% buffered formalin. All organisms were identified to the lowest practical taxonomic level, enumerated, and measured. Gross weight was recorded for each sample set. Water quality measurements such as temperature, salinity and dissolved oxygen were collected concurrently with all sampling events. Sample collections were focused on the tidal creeks crossing the marsh, which provide the primary exchange of water and nutrients between the marsh interior and Hudson River estuary. As expected, most minnows captured were Fundulus heteroclitus. However a wide variety of other nekton, including species that are important to commercial and recreational coastal Atlantic fish stocks, was recorded as well. Comparisons are made between habitats such as erosional and depostional banks, rivulets, and exterior and interior marsh settings. Also involved were transient conditions such as temperature, salinity, dissolved oxygen levels, and hydroperiod

  2. Root-induced cycling of lead in salt marsh sediments.

    Science.gov (United States)

    Sundby, Bjørn; Caetano, Miguel; Vale, Carlos; Gobeil, Charles; George, Luther W; Nuzzio, Donald B

    2005-04-01

    A gold-mercury amalgam microelectrode was used in situ to measure Pb(II) by anodic stripping voltammetry and O2, Fe(II), Mn(II), and HS- by square-wave voltammetry in sediment pore water in a Haliomione portulacoides stand in a Tagus estuary salt marsh. The measurements were made in spring, summer, and fall, and were supplemented with analysis of Pb in solid phases and stable isotope analysis of Pb. In spring, the pore water was anoxic, Fe(II) reached concentrations as high as 1700 micromol/L, and Pb(II) was undetectable (Tagus Estuary salt marshes.

  3. Modeling the Retreat Processes of Salt Marsh Edge

    Science.gov (United States)

    Bendoni, M.; Cappietti, L.; Francalanci, S.; Rinaldi, M.; Solari, L.

    2012-12-01

    Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide coastal areas are being lost. In order to address this problem, experimental observations in a laboratory flume and field measurements in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat, with a focus on the erosion mechanisms caused by the action of wind and tidal waves. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves were generated according to a given wave spectrum. The physical model was constructed with the original soil and plants taken in a marsh of the lagoon of Venice, while the wave climate was reproduced according to field measurements. The experiments were conducted in the case of both unvegetated and vegetated bank: a first set of experiments was carried out considering only tidal wave; in the second, bank models experienced the effect of wind waves superimposed to the tide. The following data were collected during the experiments: wave climate interacting with the bank, flow velocity measurements in the eroded quasi-equilibrium configuration, pressure distribution along bank edge and internal pressure fluctuation and damping due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Subsequent to laboratory activity wave climate was measured close to a marsh edge in the Lagoon of Venice with the aim at identifying wave forcing on the bank surface during a moderate wind event and comparing results with the wave stress experienced by bank models in laboratory tests. Several pressure transducers installed close to the bed were used to collect wave height and wave direction with respect to the edge of the marsh. Laboratory data and field measurement

  4. Remote sensing of biomass of salt marsh vegetation in France

    Science.gov (United States)

    Gross, M. F.; Klemas, V.; Levasseur, J. E.

    1988-01-01

    Spectral data (gathered using a hand-held radiometer) and harvest data were collected from four salt marsh vegetation types in Brittany, France, to develop equations predicting live aerial biomass from spectral measurements. Remote sensing estimates of biomass of the general salt marsh community (GSM) and of Spartina alterniflora can be obtained throughout the growing season if separate biomass prediction equations are formulated for different species mixtures (for the GSM) and for different canopy types (for S. alterniflora). Results suggest that remote sensing will not be useful for predicting Halimione portulacoides biomass, but can be used to estimate Puccinellia maritima biomass early in the growing season.

  5. Effect of Oil Contamination on Infauna of Louisiana and Mississippi Marshes with Implications for Marsh Functioning

    Science.gov (United States)

    Brunner, C. A.; Yeager, K. M.; Briggs, K. B.; Keim, J.; Louchouarn, P.; Hatch, R. S.; Schindler, K. J.

    2012-12-01

    Heavy contamination by BP oil apparently affected infaunal marsh foraminifera by reducing their numbers and reducing their depth of habitation, but moderate to light oiling seemed to have little effect. Heavy oiling also reduced the standing stock of macrofauna compared to lightly and moderately oiled sites, which appeared to be stimulated by light oiling. Three sites in the marshes of Louisiana and Mississippi were examined before and after oiling by the Macondo well blowout of 2010: Belle Fontaine and the Rigolets in Mississippi Sound and Bay Jimmy in Barataria Bay, La. The sites were analyzed for standing stock, density, and species composition of the macrofauna, which accomplish most of the bioturbation; the meiofauna as represented by benthic foraminifera; sedimentary variables, including grain size and particulate organic carbon (POC); and the radionuclides 7Be, 234Th and 210Pb to assess short-term mixing and rates of sediment accumulation. Push cores were taken from the mid to lower marsh in the Spartina alterniflora zone and sliced variously. For physical variables, cores were sliced at 0.5-cm and 1-cm intervals to a meter or more. For foraminifera, cores were sliced at 1-cm intervals to 10 cm. For macrofauna, cores were sliced at 0-1-cm and 1-10-cm intervals. The vital stain rose Bengal was applied to both macrofaunal and foraminiferal samples. The degree of oiling was assigned from the shoreline cleanup assessment technique (SCAT) data published by the environmental response management application (ERMA), and cores were subsequently sampled for polycyclic aromatic hydrocarbons (PAHs). Heavy oiling appears to have affected standing stock and depth of habitation of meiofaunal foraminifera. Uncontaminated sites and sites lightly to moderately contaminated by Macondo oil had a depth of habitation deeper than 7 cm with most exceeding 10 cm, the limit of the sampling, with corresponding short-term mixing depths in the range of 0.75-4.5+ cm as defined by 7Be and

  6. Mullins' effect in polymer/clay nanocomposites

    DEFF Research Database (Denmark)

    Drozdov, Aleksey; Christiansen, Jesper de Claville; Klitkou, Rasmus

    2012-01-01

    Abstract. Experimental data are reported on polypropylene/clay nanocomposites in uniaxial cyclic tensile tests at room temperature (oscillations between maximum strains and the zero minimum stress with maximum strains increasing monotonically with number of cycles). Observations reveal fading...

  7. Toward Accurate Adsorption Energetics on Clay Surfaces

    CERN Document Server

    Zen, Andrea; Cox, Stephen J; Hu, Xiao L; Sorella, Sandro; Alfè, Dario; Michaelides, Angelos

    2016-01-01

    Clay minerals are ubiquitous in nature, and the manner in which they interact with their surroundings has important industrial and environmental implications. Consequently, a molecular-level understanding of the adsorption of molecules on clay surfaces is crucial. In this regard computer simulations play an important role, yet the accuracy of widely used empirical force fields (FF) and density functional theory (DFT) exchange-correlation functionals is often unclear in adsorption systems dominated by weak interactions. Herein we present results from quantum Monte Carlo (QMC) for water and methanol adsorption on the prototypical clay kaolinite. To the best of our knowledge, this is the first time QMC has been used to investigate adsorption at a complex, natural surface such as a clay. As well as being valuable in their own right, the QMC benchmarks obtained provide reference data against which the performance of cheaper DFT methods can be tested. Indeed using various DFT exchange-correlation functionals yields...

  8. Mullins' effect in polymer/clay nanocomposites

    DEFF Research Database (Denmark)

    Drozdov, Aleksey; Christiansen, Jesper de Claville; Klitkou, Rasmus

    2012-01-01

    Abstract. Experimental data are reported on polypropylene/clay nanocomposites in uniaxial cyclic tensile tests at room temperature (oscillations between maximum strains and the zero minimum stress with maximum strains increasing monotonically with number of cycles). Observations reveal fading of ...

  9. The Basics in Pottery: Clay and Tools.

    Science.gov (United States)

    Larson, Joan

    1985-01-01

    Art teachers at the middle school or junior high school level usually find themselves in a program teaching ceramics. The most essential tools needed for a ceramics class are discussed. Different kinds of clay are also discussed. (RM)

  10. Interaction of Auramine O with montmorillonite clays

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Avelardo U.C.; Poli, Alessandra L.; Gessner, Fergus; Neumann, Miguel G. [Instituto de Química de São Carlos, Universidade de São Paulo, Caixa Postal 780, 13560-970 São Carlos SP (Brazil); Schmitt Cavalheiro, Carla C., E-mail: carla@iqsc.usp.br [Instituto de Química de São Carlos, Universidade de São Paulo, Caixa Postal 780, 13560-970 São Carlos SP (Brazil)

    2013-04-15

    The spectroscopic behaviour of Auramine O (AuO) in aqueous suspensions of montmorillonite clays was studied using absorption and static and dynamic fluorescence techniques. The fluorescence of Auramine O increases immediately after mixing the dye solution with the suspension of clay due to its adsorption on the external surface of the clays, which restricts the torsional molecular motion of Auramine. At longer times, the dye molecules migrate into the interlamellar region of the clay particles. Aggregation of the dye molecules can occur in the interlayer region, leading to the decrease of the fluorescence emission. The fluorescence quantum yields (Φ{sub F}) of AuO on the natural montmorillonites SAz-1, SWy-1, Syn-1 and Laponite clays were 0.015, 0.007, 0.016 and 0.017, respectively. These values are higher than the Φ{sub F} of AuO in aqueous solution and are of the same order of magnitude of the Φ{sub F} found for viscous solvents such as n-hexanol and n-heptanol (0.014 and 0.015). Time-resolved fluorescence spectroscopy studies of adsorbed Auramine on clays revealed multi-exponential decays with components in the 25–36, 219–362 and 1300–1858 ps ranges. The short-lived components can be attributed to species bound to external surface and the longer lifetime is assigned to dye molecules in interlayer spaces interacting strongly with the clay. It seems clear that the binding of Auramine to clays causes a significant reduction of the rate of internal conversion that does involve rotational diffusion, so that the clay will be locked in a conformational geometry unfavourable for internal conversion. -- Highlights: ► Auramine O was dissolved in dispersions of different clays. ► The fluorescence quantum yields were higher than in aqueous solution. ► Decrease of the emission and triexponential decays were observed on SAz-1, LapRDS and SYn-1. ► On Swy-1 the decrease was slower and the decay monoexponential. ► The dye produces aggregates on the internal

  11. 2 nd Mid-European Clay Conference

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The 2nd Mid-European Clay Conference (MECC'04) was held between 20-24th September 2004, in Miskolc, Hungary. The idea to hold common conferences was accepted by the national clay groups of four neighbouring countries, Poland, Slovakia, Hungary and Croatia, during the EUROCLAY Meeting in Cracow, Poland, in 1999. The first conference was held in 2001 at Stará Lesná, in the High Tatra Mts. in Slovakia.

  12. Cobalt sorption in silica-pillared clays.

    Science.gov (United States)

    Sampieri, A; Fetter, G; Bosch, P; Bulbulian, S

    2006-01-03

    Silicon pillared samples were prepared following conventional and microwave irradiation methods. The samples were characterized and tested in cobalt sorption. Ethylenediammine was added before cobalt addition to improve the amount of cobalt retained. The amount of cobalt introduced in the original clay in the presence of ethylenediammine was the highest. In calcined pillared clays the cobalt retention with ethylenediammine was lower (ca. 40%). In all cases the presence of ethylenediammine increased twice the amount of cobalt sorption measured for aqueous solutions.

  13. CLAY SOIL STABILISATION USING POWDERED GLASS

    OpenAIRE

    2014-01-01

    This paper assesses the stabilizing effect of powdered glass on clay soil. Broken waste glass was collected and ground into powder form suitable for addition to the clay soil in varying proportions namely 1%, 2%, 5%, 10% and 15% along with 15% cement (base) by weight of the soil sample throughout. Consequently, the moisture content, specific gravity, particle size distribution and Atterberg limits tests were carried out to classify the soil using the ASSHTO classification system. Based on the...

  14. Dynamic properties of composite cemented clay

    Institute of Scientific and Technical Information of China (English)

    蔡袁强; 梁旭

    2004-01-01

    In this work,the dynamic properties of composite cemented clay under a wide range of strains were studied considering the effect of different mixing ratio and the change of confining pressures through dynamic triaxial test. A simple and practical method to estimate the dynamic elastic modulus and damping ratio is proposed in this paper and a related empirical normalized formula is also presented. The results provide useful guidelines for preliminary estimation of cement requirements to improve the dynamic properties of clays.

  15. 76 FR 76180 - Final Environmental Impact Statement/Environmental Impact Report (EIS/EIR) for the Suisun Marsh...

    Science.gov (United States)

    2011-12-06

    ... tidal wetlands and managed wetland activities in the Marsh. Restoration of tidal wetlands under the SMP... Bay Area Wetlands Ecosystem Goals Project, and the Service's Draft Recovery Plan for Tidal Marsh... low marsh to high marsh condition. The intended outcomes of the managed wetlands activities...

  16. Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

    DEFF Research Database (Denmark)

    Sørensen, Morten Kanne; Fabricius, Ida Lykke

    2013-01-01

    Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...

  17. On The Thermal Consolidation Of Boom Clay

    CERN Document Server

    Delage, Pierre; Cui, Yu-Jun

    2012-01-01

    When a mass of saturated clay is heated, as in the case of host soils surrounding nuclear waste disposals at great depth, the thermal expansion of the constituents generates excess pore pressures. The mass of clay is submitted to gradients of pore pressure and temperature, to hydraulic and thermal flows, and to changes in its mechanical properties. In this work, some of these aspects were experimentally studied in the case of Boom clay, so as to help predicting the response of the soil, in relation with investigations made in the Belgian underground laboratory at Mol. Results of slow heating tests with careful volume change measurements showed that a reasonable prediction of the thermal expansion of the clay-water system was obtained by using the thermal properties of free water. In spite of the density of Boom clay, no significant effect of water adsorption was observed. The thermal consolidation of Boom clay was studied through fast heating tests. A simple analysis shows that the hydraulic and thermal trans...

  18. Soil clay content underlies prion infection odds

    Science.gov (United States)

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  19. Effects of Clay on Properties of Polycarboxylate Superplasticizer and Solutions

    Institute of Scientific and Technical Information of China (English)

    WANG Lin; WANG Dongmin

    2015-01-01

    The inlfuence law of clay on mortar lfuidity mixed with polycarboxylate superplasticizer was studied. Several methods of inhibiting clay adsorption of polycarboxylate superplasticizer were discussed. The experimental results show that clay has signiifcant effect on the dispersion of polycarboxylate superplasticizer and montmorillonite clay has more signiifcant impact on mortar lfuidity than other clays. The pH value and the salts of the solution can affect the adsorption of clay to polycarboxylate superplasticizer. The incorporation of a small amount of sodium hydroxide solution, sodium silicate or cationic surfactants can improve the effect of the clay on the dispersion of polycarboxylate superplasticizer.

  20. Quantifying vegetation and nekton response to tidal restoration of a New England salt marsh

    Science.gov (United States)

    Roman, C.T.; Raposa, K.B.; Adamowicz, S.C.; James-Pirri, M.J.; Catena, J.G.

    2002-01-01

    Tidal flow to salt marshes throughout the northeastern United States is often restricted by roads, dikes, impoundments, and inadequately sized culverts or bridge openings, resulting in altered ecological structure and function. In this study we evaluated the response of vegetation and nekton (fishes and decapod crustaceans) to restoration of full tidal flow to a portion of the Sachuest Point salt marsh, Middletown, Rhode Island. A before, after, control, impact study design was used, including evaluations of the tide-restricted marsh, the same marsh after reintroduction of tidal flow (i.e., tide-restored marsh), and an unrestricted control marsh. Before tidal restoration vegetation of the 3.7-ha tide-restricted marsh was dominated by Phragmites australis and was significantly different from the adjacent 6.3-ha Spartina -dominated unrestricted control marsh (analysis of similarities randomization test, p Phragmites significantly declined, suggesting a convergence toward typical New England salt marsh vegetation. Before restoration shallow water habitat (creeks and pools) of the unrestricted control marsh supported a greater density of nekton compared with the tide-restricted marsh (analysis of variance, p fish and decapod species in all sampled habitats. This study provides an example of a quantitative approach for assessing the response of vegetation and nekton to tidal restoration.

  1. Gulf-Wide Information System, Environmental Sensitivity Index Intermediate Marsh, Geographic NAD83, LDWF (2001) [esi_intermediate_marsh_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) intermediate marshes data of coastal Louisiana. The ESI is a classification and ranking system, which...

  2. Gulf-Wide Information System, Environmental Sensitivity Index Brackish Marsh, Geographic NAD83, LDWF (2001) [esi_brackish_marsh_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) brackish marshes data of coastal Louisiana. The ESI is a classification and ranking system, which...

  3. Thresholds in marsh resilience to the Deepwater Horizon oil spill

    Science.gov (United States)

    Silliman, Brian R.; Dixon, Philip M.; Wobus, Cameron; He, Qiang; Daleo, Pedro; Hughes, Brent B.; Rissing, Matthew; Willis, Jonathan M.; Hester, Mark W.

    2016-09-01

    Ecosystem boundary retreat due to human-induced pressure is a generally observed phenomenon. However, studies that document thresholds beyond which internal resistance mechanisms are overwhelmed are uncommon. Following the Deepwater Horizon (DWH) oil spill, field studies from a few sites suggested that oiling of salt marshes could lead to a biogeomorphic feedback where plant death resulted in increased marsh erosion. We tested for spatial generality of and thresholds in this effect across 103 salt marsh sites spanning ~430 kilometers of shoreline in coastal Louisiana, Alabama, and Mississippi, using data collected as part of the natural resource damage assessment (NRDA). Our analyses revealed a threshold for oil impacts on marsh edge erosion, with higher erosion rates occurring for ~1–2 years after the spill at sites with the highest amounts of plant stem oiling (90–100%). These results provide compelling evidence showing large-scale ecosystem loss following the Deepwater Horizon oil spill. More broadly, these findings provide rare empirical evidence identifying a geomorphologic threshold in the resistance of an ecosystem to increasing intensity of human-induced disturbance.

  4. Geodetic Imaging of Marsh Surface Elevation with Terrestrial Laser Scanning

    Science.gov (United States)

    Nguyen, C. T.; Starek, M. J.; Gibeaut, J. C.; Lord, A.

    2015-12-01

    The resilience of marshes to a rising sea is dependent on their elevation response. Given the level of precision required to measure minute changes in marsh elevation over time, survey methods have to be adapted to minimize impacts to the sediment surface. Current approaches include Surface Elevation Tables (SETs), which are used to monitor wetland surface change with respect to an in situ vertical benchmark. Although SETs have been proven as an effective technique to track subtle sedimentation rates (productive estuarine ecosystems in the Gulf of Mexico. The study region is covered by dense and tall saw-grass that makes it a challenging environment for bare-earth mapping. For this survey, a Riegl VZ-400 TLS (1550 nm wavelength) was utilized. The system is capable of recording multiple returns per a transmitted pulse (up to 15) and provides full-waveform output for signal post-processing to extract returns. The objectives of the study are twofold: 1) examine impacts of TLS survey design, scan angle and scan density on marsh elevation mapping; 2) assess the capabilities of multiple-echo and full-waveform TLS data to extract the bare-earth surface below the dense vegetation. This presentation will present results of the study including the developed TLS survey protocol and data processing workflow, details on waveform and multi-echo approaches for ground point detection, and a discussion on error analysis and challenges for measuring marsh surface elevation with TLS.

  5. Thresholds in marsh resilience to the Deepwater Horizon oil spill

    Science.gov (United States)

    Silliman, Brian R.; Dixon, Philip M.; Wobus, Cameron; He, Qiang; Daleo, Pedro; Hughes, Brent B.; Rissing, Matthew; Willis, Jonathan M.; Hester, Mark W.

    2016-01-01

    Ecosystem boundary retreat due to human-induced pressure is a generally observed phenomenon. However, studies that document thresholds beyond which internal resistance mechanisms are overwhelmed are uncommon. Following the Deepwater Horizon (DWH) oil spill, field studies from a few sites suggested that oiling of salt marshes could lead to a biogeomorphic feedback where plant death resulted in increased marsh erosion. We tested for spatial generality of and thresholds in this effect across 103 salt marsh sites spanning ~430 kilometers of shoreline in coastal Louisiana, Alabama, and Mississippi, using data collected as part of the natural resource damage assessment (NRDA). Our analyses revealed a threshold for oil impacts on marsh edge erosion, with higher erosion rates occurring for ~1–2 years after the spill at sites with the highest amounts of plant stem oiling (90–100%). These results provide compelling evidence showing large-scale ecosystem loss following the Deepwater Horizon oil spill. More broadly, these findings provide rare empirical evidence identifying a geomorphologic threshold in the resistance of an ecosystem to increasing intensity of human-induced disturbance. PMID:27679956

  6. Mercury Speciation, Retention and Genomics in Fertilized Salt Marsh Sediments

    Science.gov (United States)

    Collins, C. W.; Lamborg, C. H.; Whalen, K.; Mincer, T.; Buchanan, W.; Huber, J. A.; Swarr, G.; Ganguli, P. M.; Bernhard, A.

    2014-12-01

    Recent studies have demonstrated that increased nutrient loading and eutrophication can impact the production of monomethylmercury (MMHg) in marine systems. Experimental plots in Great Sippewisset Marsh (GSM), Falmouth, Massachusetts USA, have been chronically treated with a mixed fertilizer during the growing season since 1971, providing nutrients and other elements, including mercury (Hg) to the salt marsh. To assess the retention, release and methylation of Hg in these marsh sediments in response to fertilization, we collected cores from control, low, high, and extra high fertilization plots across low and high marsh settings. We determined total mercury (HgT) and MMHg concentration and accumulation rates and compared them to those of atmospheric deposition and the loading from the mixed fertilizer. Environmental DNA was extracted from the core sub-samples and polymerase chain reaction (PCR) was used to detect three genes of interest: merA (Hg(II) reducing), hgcA (Hg(II) methylating) and dsrAB (dissimilatory sulfite reduction). Quantitative PCR (qPCR) will be performed in order to overlay the abundance and diversity of the three genes to the Hg profiles and speciation metadata. By comparing the genomic data to the geochemical patterns within the treatment plots we can develop a greater sense of how Hg cycling has changed as a result of fertilization and the overall response of GSM to long-term nutrient loading.

  7. New model describes toppling of salt marsh banks

    Science.gov (United States)

    Wendel, JoAnna

    2014-05-01

    Salt marshes are coastal habitats that store important nutrients and serve as shelter for many estuarial species. These habitats are threatened by rising seas and human expansion, so it has become increasingly important to improve models of how these habitats degrade.

  8. [Lake Mason and Soo Line Marsh project design approval

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This letter is the approval from the U.S. Fish and Wildlife Service of the designs created by Ducks Unlimited, Inc. for the Lake Mason and Soo Line Marsh National...

  9. Survey of marshes and wetlands in the Netherlands

    NARCIS (Netherlands)

    Mörzer Bruijns, M.F.; Salverda, Z.

    1965-01-01

    The Netherlands are well known as a lowlying country with many marshes, inland waters and “polders” below sealevel. The relative importance of the area of water and marshland is evident if one compares the areas of land utilisation in the Netherlands, given in ha in table I (Directie van de

  10. Temperature sensitivity of organic-matter decay in tidal marshes

    Science.gov (United States)

    Kirwan, M. L.; Guntenspergen, G. R.; Langley, J. A.

    2014-09-01

    Approximately half of marine carbon sequestration takes place in coastal wetlands, including tidal marshes, where organic matter contributes to soil elevation and ecosystem persistence in the face of sea-level rise. The long-term viability of marshes and their carbon pools depends, in part, on how the balance between productivity and decay responds to climate change. Here, we report the sensitivity of labile soil organic-matter decay in tidal marshes to seasonal and latitudinal variations in temperature measured over a 3-year period. We find a moderate increase in decay rate at warmer temperatures (3-6% per °C, Q10 = 1.3-1.5). Despite the profound differences between microbial metabolism in wetlands and uplands, our results indicate a strong conservation of temperature sensitivity. Moreover, simple comparisons with organic-matter production suggest that elevated atmospheric CO2 and warmer temperatures will accelerate carbon accumulation in marsh soils, and potentially enhance their ability to survive sea-level rise.

  11. Stock and losses of trace metals from salt marsh plants.

    Science.gov (United States)

    Caçador, Isabel; Caetano, Miguel; Duarte, Bernardo; Vale, Carlos

    2009-03-01

    Pools of Zn, Cu, Cd and Co in the leaf, stem and root tissues of Sarcocornia fruticosa, Sarcocornia perennis, Halimione portulacoides and Spartina maritima were analysed for a Tagus estuary (Portugal) salt marsh. Pools of Cu and Cd in the salt marsh were higher in spring/summer, indicating a net uptake of these metals during the growing season. Standing stocks of Zn, Cu, Cd and Co in the leaf and stem biomass of S. fruticosa, S. perennis and H. portulacoides showed a strong seasonal variation, with higher values recorded in autumn. The metal-containing leaves and stems that shed in the autumn become metal-containing detritus. The amount of this material washed out from the total marsh area (200 ha) was estimated as 68 kg of Zn, 8.2 kg of Cu, 13 kg of Co and 0.35 kg of Cd. The high tidal amplitude, a branched system of channels and semi-diurnal tidal cycle greatly favour the export of the organic detritus to adjoining marsh areas.

  12. Impacts of Intensified Agriculture Developments on Marsh Wetlands

    Directory of Open Access Journals (Sweden)

    Zhaoqing Luan

    2013-01-01

    Full Text Available A spatiotemporal analysis on the changes in the marsh landscape in the Honghe National Nature Reserve, a Ramsar reserve, and the surrounding farms in the core area of the Sanjiang Plain during the past 30 years was conducted by integrating field survey work with remote sensing techniques. The results indicated that intensified agricultural development had transformed a unique natural marsh landscape into an agricultural landscape during the past 30 years. Ninety percent of the natural marsh wetlands have been lost, and the areas of the other natural landscapes have decreased very rapidly. Most dry farmland had been replaced by paddy fields during the progressive change of the natural landscape to a farm landscape. Attempts of current Chinese institutions in preserving natural wetlands have achieved limited success. Few marsh wetlands have remained healthy, even after the establishment of the nature reserve. Their ecological qualities have been declining in response to the increasing threats to the remaining wetland habitats. Irrigation projects play a key role in such threats. Therefore, the sustainability of the natural wetland ecosystems is being threatened by increased regional agricultural development which reduced the number of wetland ecotypes and damaged the ecological quality.

  13. Geochemical evidence for cryptic sulfur cycling in salt marsh sediments

    DEFF Research Database (Denmark)

    Mills, Jennifer V.; Antler, Gilad; Turchyn, Alexandra V.

    2016-01-01

    investigate sulfur cycling in salt marsh sediments from Norfolk, England where we observe high ferrous iron concentrations with no depletion of sulfate or change in the sulfur isotope ratio of that sulfate, but a 5‰ increase in the oxygen isotope ratio in sulfate, indicating that sulfate has been through...

  14. Subgrid Modeling Geomorphological and Ecological Processes in Salt Marsh Evolution

    Science.gov (United States)

    Shi, F.; Kirby, J. T., Jr.; Wu, G.; Abdolali, A.; Deb, M.

    2016-12-01

    Numerical modeling a long-term evolution of salt marshes is challenging because it requires an extensive use of computational resources. Due to the presence of narrow tidal creeks, variations of salt marsh topography can be significant over spatial length scales on the order of a meter. With growing availability of high-resolution bathymetry measurements, like LiDAR-derived DEM data, it is increasingly desirable to run a high-resolution model in a large domain and for a long period of time to get trends of sedimentation patterns, morphological change and marsh evolution. However, high spatial-resolution poses a big challenge in both computational time and memory storage, when simulating a salt marsh with dimensions of up to O(100 km^2) with a small time step. In this study, we have developed a so-called Pre-storage, Sub-grid Model (PSM, Wu et al., 2015) for simulating flooding and draining processes in salt marshes. The simulation of Brokenbridge salt marsh, Delaware, shows that, with the combination of the sub-grid model and the pre-storage method, over 2 orders of magnitude computational speed-up can be achieved with minimal loss of model accuracy. We recently extended PSM to include a sediment transport component and models for biomass growth and sedimentation in the sub-grid model framework. The sediment transport model is formulated based on a newly derived sub-grid sediment concentration equation following Defina's (2000) area-averaging procedure. Suspended sediment transport is modeled by the advection-diffusion equation in the coarse grid level, but the local erosion and sedimentation rates are integrated over the sub-grid level. The morphological model is based on the existing morphological model in NearCoM (Shi et al., 2013), extended to include organic production from the biomass model. The vegetation biomass is predicted by a simple logistic equation model proposed by Marani et al. (2010). The biomass component is loosely coupled with hydrodynamic and

  15. Premiminary tests on modified clays for electrolyte contaminated drilling fluids

    OpenAIRE

    den Hamer, Davina; Di Emidio, Gemmina; Bezuijen, Adam; Verastegui Flores, Daniel

    2015-01-01

    The quality of a bentonite suspension declines in aggressive systems like brackish or saline pore water. An engineered clay (HYPER clay) was developed for sealing materials with enhanced resistance to aggressive conditions. The modified clay is produced by treating a sodium activated bentonite with a cellulose polymer following the HYPER clay process method. This study investigates the suitability of the modified clay for electrolyte contaminated drilling fluids. Drilling fluids become contam...

  16. NMR imaging and cryoporometry of swelling clays

    Science.gov (United States)

    Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

    2010-05-01

    Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic

  17. Tidal flushing restores the physiological condition of fish residing in degraded salt marshes.

    Science.gov (United States)

    Dibble, Kimberly L; Meyerson, Laura A

    2012-01-01

    Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus) at four tidally restricted and four tidally restored marshes in New England invaded by P. australis relative to adjacent reference salt marshes. We used physiological and morphological indicators of fish condition, including proximate body composition (% lipid, % lean dry, % water), recent daily growth rate, age class distributions, parasite prevalence, female gravidity status, length-weight regressions, and a common morphological indicator (Fulton's K) to assess impacts to fish health. We detected a significant increase in the quantity of parasites infecting fish in tidally restricted marshes but not in those where tidal flow was restored to reduce P. australis cover. Using fish length as a covariate, we found that unparasitized, non-gravid F. heteroclitus in tidally restricted marshes had significantly reduced lipid reserves and increased lean dry (structural) mass relative to fish residing in reference marshes. Fish in tidally restored marshes were equivalent across all metrics relative to those in reference marshes indicating that habitat quality was restored via increased tidal flushing. Reference marshes adjacent to tidally restored sites contained the highest abundance of young fish (ages 0-1) while tidally restricted marshes contained the lowest. Results indicate that F. heteroclitus residing in physically and hydrologically altered marshes are at a disadvantage relative to fish in reference marshes but the effects can be reversed through ecological restoration.

  18. Tidal flushing restores the physiological condition of fish residing in degraded salt marshes.

    Directory of Open Access Journals (Sweden)

    Kimberly L Dibble

    Full Text Available Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus at four tidally restricted and four tidally restored marshes in New England invaded by P. australis relative to adjacent reference salt marshes. We used physiological and morphological indicators of fish condition, including proximate body composition (% lipid, % lean dry, % water, recent daily growth rate, age class distributions, parasite prevalence, female gravidity status, length-weight regressions, and a common morphological indicator (Fulton's K to assess impacts to fish health. We detected a significant increase in the quantity of parasites infecting fish in tidally restricted marshes but not in those where tidal flow was restored to reduce P. australis cover. Using fish length as a covariate, we found that unparasitized, non-gravid F. heteroclitus in tidally restricted marshes had significantly reduced lipid reserves and increased lean dry (structural mass relative to fish residing in reference marshes. Fish in tidally restored marshes were equivalent across all metrics relative to those in reference marshes indicating that habitat quality was restored via increased tidal flushing. Reference marshes adjacent to tidally restored sites contained the highest abundance of young fish (ages 0-1 while tidally restricted marshes contained the lowest. Results indicate that F. heteroclitus residing in physically and hydrologically altered marshes are at a disadvantage relative to fish in reference marshes but the effects can be reversed through ecological

  19. Assessment of Soil Quality of Tidal Marshes in Shanghai City

    Institute of Scientific and Technical Information of China (English)

    Qing; WANG; Juan; TAN; Jianqiang; WU; Chenyan; SHA; Junjie; RUAN; Min; WANG; Shenfa; HUANG

    2013-01-01

    We take three types of tidal marshes in Shanghai City as the study object:tidal marshes in mainland,tidal marshes in the rim of islands,and shoal in Yangtze estuary.On the basis of assessing nutrient quality and environmental quality,respectively,we use soil quality index(SQI)to assess the soil quality of tidal flats,meanwhile formulate the quality grading standards,and analyze the current situation and characteristics of it.The results show that except the north of Hangzhou Bay,Nanhui and Jiuduansha with low soil nutrient quality,there are not obvious differences in soil nutrient quality between other regions;the heavy metal pollution of tidal marshes in mainland is more serious than that of tidal marshes in the rim of islands;in terms of the comprehensive soil quality index,the regions are sequenced as follows:Jiuduansha wetland>Chongming Dongtan wetland>Nanhui tidal flat>tidal flat on the periphery of Chongming Island>tidal flat on the periphery of Hengsha Island>Pudong tidal flat>Baoshan tidal flat>tidal flat on the periphery of Changxing Island>tidal flat in the north of Hangzhou Bay.Among them,Jiuduansha wetland and Chongming Dongtan wetland have the best soil quality,belonging to class III,followed by Nanhui tidal flat,tidal flat on the periphery of Chongming Island and tidal flat on the periphery of Hengsha Island,belonging to class IV;tidal flat on the periphery of Changxing Island,Pudong tidal flat,Baoshan tidal flat and tidal flat in the north of Hangzhou Bay belong to class V.

  20. Limited Influence of Urban Stormwater Runoff on Salt Marsh Platform and Marsh Creek Oxygen Dynamics in Coastal Georgia.

    Science.gov (United States)

    Savidge, William B; Brink, Jonathan; Blanton, Jackson O

    2016-12-01

    Oxygen concentrations and oxygen utilization rates were monitored continuously for 23 months on marsh platforms and in small tidal creeks at two sites in coastal Georgia, USA, that receive urban stormwater runoff via an extensive network of drainage canals. These data were compared to nearby control sites that receive no significant surface runoff. Overall, rainfall and runoff per se were not associated with differences in the oxygen dynamics among the different locations. Because of the large tidal range and long tidal excursions in coastal Georgia, localized inputs of stormwater runoff are rapidly mixed with large volumes of ambient water. Oxygen concentrations in tidal creeks and on flooded marsh platforms were driven primarily by balances of respiration and photosynthesis in the surrounding regional network of marshes and open estuarine waters. Local respiration, while measurable, was of relatively minor importance in determining oxygen concentrations in tidal floodwaters. Water residence time on the marshes could explain differences in oxygen concentration between the runoff-influenced and control sites.

  1. Can Oregon Marshes Keep Up With The Rising Tide? A Study of Short and Long Term Marsh Accretion.

    Science.gov (United States)

    More frequent inundation of Oregon coastal marshlands associated with rising sea level threatens these important and diverse habitats. Study plot accretion rates determined by the marker horizon method and longer term peak Cs137 detection in eight marsh systems from Coquille to ...

  2. Limited Influence of Urban Stormwater Runoff on Salt Marsh Platform and Marsh Creek Oxygen Dynamics in Coastal Georgia

    Science.gov (United States)

    Savidge, William B.; Brink, Jonathan; Blanton, Jackson O.

    2016-12-01

    Oxygen concentrations and oxygen utilization rates were monitored continuously for 23 months on marsh platforms and in small tidal creeks at two sites in coastal Georgia, USA, that receive urban stormwater runoff via an extensive network of drainage canals. These data were compared to nearby control sites that receive no significant surface runoff. Overall, rainfall and runoff per se were not associated with differences in the oxygen dynamics among the different locations. Because of the large tidal range and long tidal excursions in coastal Georgia, localized inputs of stormwater runoff are rapidly mixed with large volumes of ambient water. Oxygen concentrations in tidal creeks and on flooded marsh platforms were driven primarily by balances of respiration and photosynthesis in the surrounding regional network of marshes and open estuarine waters. Local respiration, while measurable, was of relatively minor importance in determining oxygen concentrations in tidal floodwaters. Water residence time on the marshes could explain differences in oxygen concentration between the runoff-influenced and control sites.

  3. Dynamics of biogenic Si in freshwater tidal marshes: Si generation and retention in marsh sediments (Scheldt estuary)

    NARCIS (Netherlands)

    Struyf, E.; Temmerman, S.; Meire, P.

    2007-01-01

    The sequestration and recycling of biogenic silica (BSi) in freshwater tidal marshes was modelled through the combination of short-term year round sediment trap data with a long-term sedimentation model, MARSED. The modelling was implemented through the complete evolution from a young rapidly rising

  4. Removal of boron from aqueous solution by clays and modified clays.

    Science.gov (United States)

    Karahan, Senem; Yurdakoç, Mürüvvet; Seki, Yoldaş; Yurdakoç, Kadir

    2006-01-01

    In order to increase the adsorption capacities of bentonite, sepiolite, and illite for the removal of boron form aqueous solution, the clay samples were modified by nonylammonium chloride. Specific surface areas of the samples were determined as a result of N2 adsorption-desorption at 77 K using the BET method. X-ray powder diffraction analysis of the clays and modified clays was used to determine the effects of modifying agents on the layer structure of the clays. The surface characterization of clays and modified clay samples was conducted using the FTIR technique before and after the boron adsorption. For the optimization of the adsorption of boron on clays and modified clays, the effect of pH and ionic strength was examined. The results indicate that adsorption of boron can be achieved by regulating pH values in the range of 8-10 and high ionic strength. In order to find the adsorption characteristics, Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms were applied to the adsorption data. The data were well described by Freundlich and Dubinin-Radushkevich adsorption isotherms while the fit of Langmuir equation to adsorption data was poor. It was reached that modification of bentonite and illite with nonylammonium chloride increased the adsorption capacity for boron sorption from aqueous solution.

  5. Determining Upper Bounds for the Clay-squirt Effect in Clay Bearing Sandstone

    DEFF Research Database (Denmark)

    Sørensen, Morten Kanne; Fabricius, Ida Lykke

    Sonic measurements of saturated bulk moduli of clay bearing sandstones show larger values than expected by Gassmann modelling from dry rock properties. This causes difficulties in extrapolation of laboratory data to different saturants or frequencies. Squirt flow from the clay phase of the rock...

  6. Seasonal variation of bromine monoxide over the Rann of Kutch salt marsh seen from space

    Science.gov (United States)

    Hörmann, Christoph; Beirle, Steffen; Penning de Vries, Marloes; Sihler, Holger; Platt, Ulrich; Wagner, Thomas

    2015-04-01

    Bromine monoxide (BrO) is an important catalyst in the depletion of tropospheric and stratospheric ozone (O3). In the troposphere, reactive bromine can be released from sea ice, volcanoes, sea-salt aerosol or salt lakes. For all of these natural sources enhanced BrO vertical column densities (VCDs) have been successfully observed from ground using Differential Optical Absorption Spectroscopy (DOAS). Until now, satellite observations were only reported for polar regions during springtime and volcanic emissions (mostly for major eruptions). We present the first satellite observations of enhanced monthly mean BrO VCDs over a salt marsh, the Rann of Kutch (India/Pakistan), during 2004-2014 as seen by the Ozone Monitoring Instrument (OMI). The Rann of Kutch is a so-called 'seasonal' salt marsh. During India's summer monsoon (June/July - September/October), the flat desert of salty clay and mudflats, which average 15 meters above sea level, fills with standing rain and sea water. With more than 7500 km2 it is the largest salt desert in the world and additionally one of the hottest areas of India with summer temperatures around 50 ° C and winter temperatures decreasing below 0 ° C. Probably due to these rather extreme conditions, the Rann of Kutch has not been yet investigated for atmospheric composition measurements by ground-based instruments. Satellite observations, however, provide the unique possibility to investigate the entire area remotely over a long-time period. The OMI data reveals recurring maximum BrO VCDs during April/May, but no enhanced column densities during the monsoon season while the area is flooded. In the following months the signal only recovers slowly while the salty surface dries up. We discuss the possible effects of temperature, precipitation and relative humidity on the release of enhanced reactive bromine concentrations. In order to investigate a possible diurnal cycle of the BrO concentration, the OMI results (at a local overflight time

  7. Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

    Energy Technology Data Exchange (ETDEWEB)

    Randall T. Cygan

    2007-06-01

    “Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

  8. Clay nanocomposites for use in Li batteries

    Science.gov (United States)

    Moore, Gregory John

    1999-11-01

    Nanocomposites, materials made of more than one component and combined in an ordered manner on the nanometer scale, were synthesized using clay mineral hosts with various types of guests. The guests include polymers such as polyethylene oxide (PEO) and polyaniline (PANI), large molecules such as ethylmethyl sulfone, tetramethylene sulfone, and various length alkylamines. Vanadyl groups (VO 2+) were also incorporated with the clays. The otherwise non-swellable mica clay, synthetic Na-fluorophlogopite, was expanded by intercalation of acidic ions such as Cu2+ and Fe3+. As aqueous solutions, these ions caused the stable fluoromica to go from its dehydrated interlayer spacing of 9.8 A to over 14 A. This clay became a host for many other reactions including swelling with alkylamines to over 25 A. However, despite hydrated Cu2+ ions swelling fluorophlogopite, polymeric species such as PEO or PANI could not be inserted. Another clay that was used for formation of nanocomposites came from a procedure for the synthesis of Li-taeniolite, Li(Mg2Li)Si 4O10F2. The clay was synthesized following a high temperature method that led to a non-reactive product. Instead, a novel precursor route was employed that gave a clay product with a single hydration layer. Various chemical analyses gave a formula of Li0.8(Mg 2.2Li0.8)Si4O10(F1.6O 0.4)·H2O. For the purpose of forming nanocomposite electrolytes, ethylmethyl sulfone was synthesized and incorporated into the clay. For comparison of different shaped sulfones, tetramethylene sulfone also was inserted into the layers for electrolytic studies. To make a polymer-clay electrolyte, polyethylene oxide was intercalated into the Li-taeniolite. All of these new electrolyte materials were characterized using impedance spectroscopy for measurement of their conductivity. Syntheses and analyses are thoroughly discussed for all of these materials. Special attention is placed on powder x-ray diffraction and thermogravimetric techniques to

  9. Marsh Creation in a Northern Pacific Estuary: Is Thirteen Years of Monitoring Vegetation Dynamics Enough?

    Directory of Open Access Journals (Sweden)

    Neil K. Dawe

    2000-12-01

    Full Text Available Vegetation changes were monitored over a 13-yr period (1982-1994 in the Campbell River estuary following the development of marshes on four intertidal islands. The marshes were created to mitigate the loss of a natural estuarine marsh resulting from the construction of a dry land log-sorting facility. Plant species coverage was measured along 23 permanent transects in planted and unplanted blocks on the constructed islands, and in naturally occurring low-marsh and mid-to-high marsh reference communities on nearby Nunn's Island. Five dominant species, Carex lyngbyei, Juncus balticus, Potentilla pacifica, Deschampsia caespitosa, and Eleocharis palustris established successfully and increased in cover in both planted and unplanted areas. The planted, unplanted, and Nunn's Island low-marsh sites had similar total plant cover and species richness by the 13th year. Principal components analysis of the transects through time indicated successful establishment of mid-to-low marsh communities on the constructed islands by the fourth year. Vegetation fluctuations on the constructed islands were greater than in the mid-to-high and low-marsh reference communities on Nunn's Island. Results showed that substrate elevation and island configuration were major influences on the successful establishment and subsequent dynamics of created marsh communities. Aboveground biomass estimates of marshes on the created islands attained those of the reference marshes on Nunn's Island between years 6 and 13. However, Carex lyngbyei biomass on the created islands had not reached that of the reference marshes by year 13. Despite the establishment of what appeared to be a productive marsh, with species composition and cover similar to those of the reference marshes on Nunn's Island, vegetation on the created islands was still undergoing changes that, in some cases, were cause for concern. On three of the islands, large areas devoid of vegetation formed between years 6 and 13

  10. Behavior of compacted clay-concrete interface

    Institute of Scientific and Technical Information of China (English)

    R.R. SHAKIR; Jungao ZHU

    2009-01-01

    Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared.Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface rough-ness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

  11. Environmental assessment of Al-Hammar Marsh, Southern Iraq.

    Science.gov (United States)

    Al-Gburi, Hind Fadhil Abdullah; Al-Tawash, Balsam Salim; Al-Lafta, Hadi Salim

    2017-02-01

    (a) To determine the spatial distributions and levels of major and minor elements, as well as heavy metals, in water, sediment, and biota (plant and fish) in Al-Hammar Marsh, southern Iraq, and ultimately to supply more comprehensive information for policy-makers to manage the contaminants input into the marsh so that their concentrations do not reach toxic levels. (b) to characterize the seasonal changes in the marsh surface water quality. (c) to address the potential environmental risk of these elements by comparison with the historical levels and global quality guidelines (i.e., World Health Organization (WHO) standard limits). (d) to define the sources of these elements (i.e., natural and/or anthropogenic) using combined multivariate statistical techniques such as Principal Component Analysis (PCA) and Agglomerative Hierarchical Cluster Analysis (AHCA) along with pollution analysis (i.e., enrichment factor analysis). Water, sediment, plant, and fish samples were collected from the marsh, and analyzed for major and minor ions, as well as heavy metals, and then compared to historical levels and global quality guidelines (WHO guidelines). Then, multivariate statistical techniques, such as PCA and AHCA, were used to determine the element sourcing. Water analyses revealed unacceptable values for almost all physio-chemical and biological properties, according to WHO standard limits for drinking water. Almost all major ions and heavy metal concentrations in water showed a distinct decreasing trend at the marsh outlet station compared to other stations. In general, major and minor ions, as well as heavy metals exhibit higher concentrations in winter than in summer. Sediment analyses using multivariate statistical techniques revealed that Mg, Fe, S, P, V, Zn, As, Se, Mo, Co, Ni, Cu, Sr, Br, Cd, Ca, N, Mn, Cr, and Pb were derived from anthropogenic sources, while Al, Si, Ti, K, and Zr were primarily derived from natural sources. Enrichment factor analysis gave results

  12. Coupled Wave Energy and Erosion Dynamics along a Salt Marsh Boundary, Hog Island Bay, Virginia, USA

    Directory of Open Access Journals (Sweden)

    Anthony M. Priestas

    2015-09-01

    Full Text Available The relationship between lateral erosion of salt marshes and wind waves is studied in Hog Island Bay, Virginia USA, with high-resolution field measurements and aerial photographs. Marsh retreat is compared to wave climate calculated in the bay using the spectral wave-model Simulating Waves Nearshore (SWAN. We confirm the existence of a linear relationship between long-term salt marsh erosion and wave energy, and show that wave power can serve as a good proxy for average salt-marsh erosion rates. At each site, erosion rates are consistent across several temporal scales, ranging from months to decades, and are strongly related to wave power. On the contrary, erosion rates vary in space and weakly depend on the spatial distribution of wave energy. We ascribe this variability to spatial variations in geotechnical, biological, and morphological marsh attributes. Our detailed field measurements indicate that at a small spatial scale (tens of meters, a positive feedback between salt marsh geometry and wave action causes erosion rates to increase with boundary sinuosity. However, at the scale of the entire marsh boundary (hundreds of meters, this relationship is reversed: those sites that are more rapidly eroding have a marsh boundary which is significantly smoother than the marsh boundary of sheltered and slowly eroding marshes.

  13. Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

    Science.gov (United States)

    Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

  14. One-Dimensional Simulation of Clay Drying

    Directory of Open Access Journals (Sweden)

    Siljan Siljan

    2002-04-01

    Full Text Available Drying of clay is simulated by a one-dimensional model. The background of the work is to form a better basis for investigation of the drying process in production of clay-based building materials. A model of one-dimensional heat and mass transfer in porous material is used and modified to simulate drying of clay particles. The convective terms are discretized by first-order upwinding, and the diffusive terms are discretized by central differencing. DASSL was used to solve the set of algebraic and differential equations. The different simulations show the effect of permeability, initial moisture content and different boundary conditions. Both drying of a flat plate and a spherical particle are modelled.

  15. Clay Improvement with Burned Olive Waste Ash

    Directory of Open Access Journals (Sweden)

    Utkan Mutman

    2013-01-01

    Full Text Available Olive oil is concentrated in the Mediterranean basin countries. Since the olive oil industries are incriminated for a high quantity of pollution, it has become imperative to solve this problem by developing optimized systems for the treatment of olive oil wastes. This study proposes a solution to the problem. Burned olive waste ash is evaluated for using it as clay stabilizer. In a laboratory, bentonite clay is used to improve olive waste ash. Before the laboratory, the olive waste is burned at 550°C in the high temperature oven. The burned olive waste ash was added to bentonite clay with increasing 1% by weight from 1% to 10%. The study consisted of the following tests on samples treated with burned olive waste ash: Atterberg Limits, Standard Proctor Density, and Unconfined Compressive Strength Tests. The test results show promise for this material to be used as stabilizer and to solve many of the problems associated with its accumulation.

  16. Synthesis and characterization of waterborne polyurethane/organic clay nanocomposites

    Institute of Scientific and Technical Information of China (English)

    Zai-feng LI; Sheng-jun WANG; Jin-yan LI

    2008-01-01

    Stable waterborne polyurethane/organic clay latex was synthesized by ultrasonically-assisted mixing with different clay content. Fourier transform infrared (FT-IR) spectra showed that the interaction between NH and C=O was enhanced with low content organic clay loaded. X-ray diffraction (XRD) results implied that the layered organic clay was exfoliated and the crystallization of the hard domain in the waterborne polyurethane (WPU) matrix was enhanced. Transmission electron microscopy (TEM) images show that the layered clay was exfoliated by WPU molecule. The tensile test shows that the mechanical prop-erties were improved by loading organic clay and the desired addition was 1 wt.%.

  17. Quick clay and landslides of clayey soils.

    Science.gov (United States)

    Khaldoun, Asmae; Moller, Peder; Fall, Abdoulaye; Wegdam, Gerard; De Leeuw, Bert; Méheust, Yves; Otto Fossum, Jon; Bonn, Daniel

    2009-10-30

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay soils. Reproducing landslides on a small scale in the laboratory shows that an additional factor that determines the violence of the slides is the inhomogeneity of the flow. We propose a simple yield stress model capable of reproducing the laboratory landslide data, allowing us to relate landslides to the measured rheology.

  18. Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

    Science.gov (United States)

    Moran, Anthony R; Hettiarachchi, Hiroshan

    2011-07-01

    Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

  19. Middle to Late Holocene Fluctuations of C3 and C4 Vegetation in a Northern New England Salt Marsh, Sprague Marsh, Phippsburg Maine

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, B J; Moore, K A; Lehmann, C; Bohlen, C; Brown, T A

    2006-05-26

    A 3.1 meter sediment core was analyzed for stable carbon isotope composition of organic matter and higher plant leaf wax (HPLW) lipid biomarkers to determine Holocene shifts in C{sub 3} (higher high marsh) and C{sub 4} (low and/or high marsh) plant deposition at the Sprague River Salt Marsh, Phippsburg, Maine. The carbon isotope composition of the bulk sediment and the HPLW parallel each other throughout most of the core, suggesting that terrestrial plants are an important source of organic matter to the sediments, and diagenetic alteration of the bulk sediments is minimal. The current salt marsh began to form 2500 cal yr BP. Low and/or high C{sub 4} marsh plants dominated deposition at 2000 cal yr BP, 700 cal yr BP, and for the last 200 cal yr BP. Expansion of higher high marsh C{sub 3} plants occurred at 1300 and 600 cal yr BP. These major vegetation shifts result from a combination of changes in relative sea-level rise and sediment accumulation rates. Average annual carbon sequestration rates for the last 2500 years approximate 40 g C yr{sup -1} m{sup -2}, and are in strong agreement with other values published for the Gulf of Maine. Given that Maine salt marshes cover an area of {approx}79 km{sup 2}, they represent an important component of the terrestrial carbon sink. More detailed isotopic and age records from a network of sediment cores at Sprague Marsh are needed to truly evaluate the long term changes in salt marsh plant communities and the impact of more recent human activity, including global warming, on salt marsh vegetation.

  20. Monitoring oil spill bioremediation using marsh foraminifera as indicators.

    Science.gov (United States)

    Sabean, J A R; Scott, D B; Lee, K; Venosa, A D

    2009-01-01

    A controlled experiment was conducted in June 2000 to identify the environmental impacts of weathered crude oil on an Atlantic coastal salt marsh to help evaluate in situ biological remediation techniques for restoring the environment. Foraminifera, marsh microfossils known to be sensitive to a range of environmental stress factors, were used to monitor the effects of the residual oil and the experimental treatments. Results show that the foraminifera responded quickly to the oil and that the oil had a statistically significant, negative impact, as demonstrated by a dramatic increase in deformities in the tests of Miliammina fusca, compared to specimens from the non-oiled control plots. The results clearly show that foraminifera can be excellent indicators of oil pollution using only the percent of deformed tests. The advantages that foraminifera provide are the ease of sampling, processing and examination, with the added benefit that these organisms leave a fossil record.

  1. Geochemical evidence for cryptic sulfur cycling in salt marsh sediments

    DEFF Research Database (Denmark)

    Mills, Jennifer V.; Antler, Gilad; Turchyn, Alexandra V.

    2016-01-01

    to represent the salt marsh sediments suggests that the uptake rate of sulfate during this cryptic sulfur cycling is similar to the uptake rate of sulfate during the fastest microbial sulfate reduction that has been measured in the natural environment. The difference is that during cryptic sulfur cycling, all...... investigate sulfur cycling in salt marsh sediments from Norfolk, England where we observe high ferrous iron concentrations with no depletion of sulfate or change in the sulfur isotope ratio of that sulfate, but a 5‰ increase in the oxygen isotope ratio in sulfate, indicating that sulfate has been through...... a reductive cycle replacing its oxygen atoms. This cryptic sulfur cycle was replicated in laboratory incubations using 18O-enriched water, demonstrating that the field results do not solely result from mixing processes in the natural environment. Numerical modeling of the laboratory incubations scaled...

  2. Crystallite size distribution of clay minerals from selected Serbian clay deposits

    Directory of Open Access Journals (Sweden)

    Simić Vladimir

    2006-01-01

    Full Text Available The BWA (Bertaut-Warren-Averbach technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic, and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA seams to be influenced by the genetic type of the clay sample.

  3. Effects of shock metamorphism on clay mineralogy: Implications for remote sensing of martian clays

    Science.gov (United States)

    Michalski, J. R.; Glotch, T. D.; Friedlander, L.; Bish, D. L.; Sharp, T. G.; Dyar, M. D.

    2012-12-01

    One of the most important discoveries in recent exploration of Mars has been the detection of clay minerals within materials exhumed by meteor impact, which point to ancient subsurface alteration and possible habitable conditions at depth. These "crustal clays" occur within central peaks, ejecta, and uplifted rims of many large craters (Ehlmann et al., Nature 2011). The geologic context of phyllosilicates in these settings suggests that most of these deposits represent clays that formed in the subsurface and were later exhumed by impact, rather than clays that formed as a consequence of impact. Therefore, crustal clays exposed at the surface are likely to have experienced some effects of shock metamorphism and/or thermal alteration related to meteor impact. We are investigating the effects of shock metamorphism on the mineralogy of phyllosilicates in the laboratory. Purified, size-separated clay mineral samples were pressed into pellets to decrease internal porosity and were subsequently shocked using the Flat Plate Accelerator at NASA Johnson Space Center. Five minerals (nontronite, saponite, serpentine, chlorite, and kaolinite) were shocked to six pressure steps (10, 20, 25, 30, 35, and 40 GPa). The recovered, shocked samples are being analyzed by thermal infrared emission, visible/near-infrared reflectance, X-ray diffraction (XRD), Mossbauer spectroscopy, and transmission electron microscopy (TEM). Results thus far suggest that shock metamorphism has little effect on the structure or infrared signature of the clay minerals at pressures clay is greatly decreased upon initial shock. At 40 GPa, this feature has lost all internal spectral structure, though a broad absorption in the same region is retained. Lastly, Mossbauer spectroscopy indicates that clays containing ferrous iron are progressively oxidized as a function of shock pressure. In the case of a meteor impact, intense shock pressures are highly localized phenomena although low shock pressures might affect

  4. Mineralogy and geotechnical characteristics of some pottery clay

    Directory of Open Access Journals (Sweden)

    Mujib Olamide ADEAGBO

    2016-12-01

    Full Text Available The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-size particles, 21% silt and 27% clay. Analysis of the clay-sized particles and the bulk materials shows: specific gravity of 2.07 and 2.66, liquid limit of 91.0% and 33.0%, plastic limit of 27.5% and 14.3%, plasticity index of 63.5% and 18.7% and a linear shrinkage of 7.9% and 5.4%, for both clay-sized particles and bulk clay respectively. The activity value of the clay material (0.64 suggests the presence of Kaolinite and Ilite; and these were confirmed with X-Ray diffraction on the bulk sample and clay-sized particles. X-Ray diffraction patterns shows distinctive peaks which highlight the dominance of Kaolinite (with 8 peaks in the pottery clay sample for both clay-sized particles and bulk material; while traces of other clay minerals like Illite and Halloysite and rock minerals like Mica, Feldspar and Chrysotile were also found. These results suggest that the clay possesses high viability in the manufacturing of ceramics, refractory bricks, paper, fertilizer and paint. The clay material can be used as a subgrade in road construction, since it possesses low swelling characteristics.

  5. Differentiating salt marsh species using foreground/background analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, M.; Pinzon, J.; Ustin, S.L.; Rejmankova, E. [Univ. of California, Davis, CA (United States)

    1996-10-01

    Three California salt marsh plant species have distinctive morphologies that could be remotely sensed by airborne spectrometers because the architectures create differences in canopy reflectance characteristics. This paper presents a method to differentiate wetland species using a modified spectral mixture analysis termed hierarchical foreground and background analysis (HFBA). To validate this approach, the method was applied to field spectral data from several salt marshes. Foreground and background analysis allows the user to direct analysis along a specified axis of variance by identifying vectors through the n-dimensional spectral volume by identifying vectors that comprise the information of selected subset of spectra which emphasizes the presence of a discriminative signature of interest. The goal of FBA is to project spectral variation along the most relevant axis of variance that maximizes spectral differences between groups, while minimizing spectral variation within each group. For this work, we selected a training set that allowed us to create HFBA vectors which efficiently discriminate species based on canopy spectral characteristics. Results indicated that the dominant species in these salts marshes could be clearly differentiated with greater than 90% certainty from field collected canopy spectrometer data. Hundred percent of Spartina and 79% of Salicornia were correctly classified at the first level of classification. The accuracy of classification for Salicornia improved to 87% in the second level of classification. The unclassified spectral samples were related to extraordinary conditions within the wetlands such as extreme biomass, salinity and nitrogen conditions. These patterns were apparent in AVIRIS (Airborne Visible/infrared Imaging Spectrometer) images which showed distinct zonation corresponding to the distributions of these species in the marsh. Results were confirmed by field reconnaissance. 19 refs., 3 figs., 4 tabs.

  6. Controls on soil organic carbon stocks in tidal marshes along an estuarine salinity gradient

    Science.gov (United States)

    Van de Broek, Marijn; Temmerman, Stijn; Merckx, Roel; Govers, Gerard

    2016-12-01

    Tidal marshes are sedimentary environments and are among the most productive ecosystems on Earth. As a consequence they have the potential to reduce atmospheric greenhouse gas concentrations by sequestering organic carbon (OC). In the past decades, most research on soil organic carbon (SOC) storage in marsh environments has focused on salt marshes, leaving carbon dynamics in brackish and freshwater marshes largely understudied and neglecting the diversity among tidal marshes. We therefore conducted an extensive sampling campaign to quantify and characterize SOC stock in marshes along a salinity gradient in the Scheldt estuary (Belgium and the Netherlands). We find that SOC stocks vary significantly along the estuary, from 46 in freshwater marshes to 10 kg OC m-2 in salt marshes. Our data also show that most existing studies underestimate total SOC stocks due to shallow soil sampling, which also influences reported patterns in OC storage along estuaries. In all sampled tidal marsh sediments the SOC concentration is more or less constant from a certain depth downward. However, this concentration decreases with increasing salinity, indicating that the amount of stable SOC decreases from the upper estuary towards the coast. Although the net primary production of macrophytes differs along the estuary, our data suggest that the differences in OC storage are caused mainly by variations in suspended sediment concentration and stable particulate OC (POC) content in the water along the estuary. The fraction of terrestrial suspended sediments and POC that is transported downstream of the maximum turbidity zone is very limited, contributing to smaller amounts of long-term OC sequestration in brackish and salt marsh sediments. In addition, high rates of sediment deposition on freshwater tidal marshes in the maximum turbidity zone promote efficient burial of OC in these marsh sediments.

  7. Tidal Flushing Restores the Physiological Condition of Fish Residing in Degraded Salt Marshes

    OpenAIRE

    Dibble, Kimberly L.; Meyerson, Laura A.

    2012-01-01

    Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus) a...

  8. Mosquitoes Associated with Ditch-Plugged and Control Tidal Salt Marshes on the Delmarva Peninsula

    OpenAIRE

    Leisnham, Paul T.; Sarah Sandoval-Mohapatra

    2011-01-01

    A study was conducted during the summer of 2009 (from July to September) to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November) ditches were plugged near the...

  9. The protective role of coastal marshes: a systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Christine C Shepard

    Full Text Available BACKGROUND: Salt marshes lie between many human communities and the coast and have been presumed to protect these communities from coastal hazards by providing important ecosystem services. However, previous characterizations of these ecosystem services have typically been based on a small number of historical studies, and the consistency and extent to which marshes provide these services has not been investigated. Here, we review the current evidence for the specific processes of wave attenuation, shoreline stabilization and floodwater attenuation to determine if and under what conditions salt marshes offer these coastal protection services. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a thorough search and synthesis of the literature with reference to these processes. Seventy-five publications met our selection criteria, and we conducted meta-analyses for publications with sufficient data available for quantitative analysis. We found that combined across all studies (n = 7, salt marsh vegetation had a significant positive effect on wave attenuation as measured by reductions in wave height per unit distance across marsh vegetation. Salt marsh vegetation also had a significant positive effect on shoreline stabilization as measured by accretion, lateral erosion reduction, and marsh surface elevation change (n = 30. Salt marsh characteristics that were positively correlated to both wave attenuation and shoreline stabilization were vegetation density, biomass production, and marsh size. Although we could not find studies quantitatively evaluating floodwater attenuation within salt marshes, there are several studies noting the negative effects of wetland alteration on water quantity regulation within coastal areas. CONCLUSIONS/SIGNIFICANCE: Our results show that salt marshes have value for coastal hazard mitigation and climate change adaptation. Because we do not yet fully understand the magnitude of this value, we propose that decision

  10. Response of a salt marsh microbial community to antibiotic contamination.

    Science.gov (United States)

    Fernandes, Joana P; Almeida, C Marisa R; Basto, M Clara P; Mucha, Ana P

    2015-11-01

    Salt marsh plants and associated microorganisms can have an important role in contaminant removal from estuaries, through bioremediation processes. Nevertheless, the interaction between emerging contaminants, namely antibiotics, and plant-microorganism associations in estuarine environment are still scarcely known. In this vein, the aim of the present study was to evaluate, in controlled conditions, the response of a salt marsh plant-microorganism association to a contamination with a veterinary antibiotic. For that a salt marsh plant (Phragmites australis) and its respective rhizosediment were collected in a temperate estuary (Lima estuary, NW Portugal) and exposed for 7 days to enrofloxacin (ENR) under different nutritional conditions in sediment elutriates. Response was evaluated in terms of ENR removal and changes in microbial community structure (evaluated by ARISA) and abundance (estimated by DAPI). In general, no significant changes were observed in microbial abundance. Changes in bacterial richness and diversity were observed but only in unplanted systems. However, multivariate analysis of ARISA profiles showed significant effect of both the presence of plant and type of treatment on the microbial community structure, with significant differences among all treatment groups. In addition, plants and associated microorganisms presented a potential for antibiotic removal that, although highly dependent on their nutritional status, can be a valuable asset to recover impacted areas such as estuarine ones.

  11. Mangrove expansion into salt marshes alters associated faunal communities

    Science.gov (United States)

    Smee, Delbert L.; Sanchez, James A.; Diskin, Meredith; Trettin, Carl

    2017-03-01

    Climate change is altering the distribution of foundation species, with potential effects on organisms that inhabit these environments and changes to valuable ecosystem functions. In the Gulf of Mexico, black mangroves (Avicennia germinans) are expanding northward into salt marshes dominated by Spartina alterniflora (hereafter Spartina). Salt marshes are essential habitats for many organisms, including ecologically and economically important species such as blue crabs (Callinectes sapidus) and Penaeid shrimp (e.g., Penaeus aztecus), which may be affected by vegetation changes. Black mangroves occupied higher tidal elevations than Spartina, and Spartina was present only at its lowest tidal elevations in sites when mangroves were established. We compared nekton and infaunal communities within monoculture stands of Spartina that were bordered by mangroves to nearby areas where mangroves had not yet become established. Nekton and infaunal communities were significantly different in Spartina stands bordered by mangroves, even though salinity and temperature were not different. Overall abundance and biomass of nekton and infauna was significantly higher in marshes without mangroves, although crabs and fish were more abundant in mangrove areas. Black mangrove expansion as well as other ongoing vegetation shifts will continue in a warming climate. Understanding how these changes affect associated species is necessary for management, mitigation, and conservation.

  12. Clay particle retention in small constructed wetlands.

    Science.gov (United States)

    Braskerud, B C

    2003-09-01

    Constructed wetlands (CWs) can be used to mitigate non-point source pollution from arable fields. Previous investigations have shown that the relative soil particle retention in small CWs increases when hydraulic load increases. This paper investigates why this phenomenon occurs, even though common retention models predict the opposite, by studying clay and silt particle retention in two Norwegian CWs. Retention was measured with water flow proportional sampling systems in the inlet and outlet of the wetlands, and the texture of the suspended solids was analyzed. The surface area of the CWs was small compared to the watershed area (approximately 0.07%), giving high average hydraulic loads (1.1 and 2.0 md(-1)). One of the watersheds included only old arable land, whereas the other included areas with disturbed topsoil after artificial land leveling. Clay particle retention was 57% for the CW in the first watershed, and 22% for the CW in the disturbed watershed. The different behavior of the wetlands could be due to differences in aggregate size and stability of the particles entering the wetlands. Results showed that increased hydraulic loads did affect CW retention negatively. However, as runoff increased, soil particles/aggregates with higher sedimentation velocities entered the CWs (e.g., the clay particles behaved as silt particles). Hence, clay particle settling velocity is not constant as assumed in many prediction models. The net result was increased retention.

  13. Calm, Cool, and Comfortable in Clay

    Science.gov (United States)

    Stylianou, Xanthippi Cynthia

    2010-01-01

    The author's fourth-grade students had just finished a drawing unit that focused on the human figure. Projects included charcoal gesture drawings and chalk manikin drawings in chiaroscuro. She wanted to integrate a new medium for students to continue their study of the human figure. Since students are always excited to work with clay, making clay…

  14. Classroom Instruction: The Influences of Marie Clay

    Science.gov (United States)

    McNaughton, Stuart

    2014-01-01

    Marie Clay's body of work has influenced classroom instruction in direct and indirect ways, through large overarching themes in our pedagogical content knowledge as well as specific smart practices. This paper focuses on her the contributions to our thinking about instruction which come from two broad theoretical concepts; emergent literacy…

  15. Radionuclide transport in clay during climate change

    NARCIS (Netherlands)

    Wildenborg, A.F.B.; Orlic, B.; Thimus, J.F.; Lange, G.de; Cock, S. de; Leeuw, C.S. de; Veling, E.J.M.

    2003-01-01

    The Dutch national research programme into the feasibility of retrievable storage of radioactive waste (CORA Programme Phase I; CORA: Comité Opslag Radioactief Afval = Committee on Radioactive Waste Disposal) examined the suitability of Tertiary clay deposts for such storage. Long-term isolation -

  16. Clay Shirky, Internet e il collegio invisibile

    Directory of Open Access Journals (Sweden)

    Maria Chiara Pievatolo

    2011-10-01

    Full Text Available Come Internet sta cambiando il nostro modo di pensare? Fra le 172 risposte presentate da Edge, Clay Shirky ne propone una particolarmente interessante per i ricercatori di professione. Internet, scrive Shirky, ha aumentato straordinariamente la capacità espressiva dell’umanità. Ma che una risorsa divenga abbondante, da scarsa che era, è una sfortuna, almeno per chi su [...

  17. geochemical and mineralogical characteristics of lithomargic clay ...

    African Journals Online (AJOL)

    Administrator

    GHANA: IMPLICATIONS FOR POSSIBLE INDUSTRIAL UTILIZATION. F.W.Y. Momade1 ... evaluative analyses, the lithomargic clay types could be exploited in the production of aluminium sulphate ... Two major processes have been reported to be ..... powder diffraction unit. .... for fats and oils used for soap, grease produc-.

  18. Bauxite washing for the removal of clay

    Institute of Scientific and Technical Information of China (English)

    Ishaq Ahmad; Ernst-Ulrich Hartge; Joachim Werther; and Reiner Wischnewski

    2014-01-01

    Clay impurities associated with bauxite negatively affect the Bayer process for alumina production. These impurities should be removed as far as possible by a beneficiation technique before the ore is used as feed for the Bayer process. In this current investigation, bauxite washing was conducted in the laboratory. Bauxite washing is a physical process that causes the disintegration and deagglomeration of the clay matrix, and bauxite is liberated from the clay (mainly rich in silica). Subsequently, separation occurs with the assistance of wet screening at a predetermined cut size. Three techniques were investigated in the laboratory: drum washing, water-jet washing, and ultrasonic washing. Various operating parameters were investigated for drum washing and water-jet washing, including materials retention time, drum rotation speed, solid concentration, water-jet spray duration, pressure, and height. We concluded that the retention time of bauxite inside the drum at a solid concentration of 55wt% and a drum rotation speed of 31 r/min is the dominant parameter for the removal of clay from the bauxite surface.

  19. Geotechnical studies of Jaitapur marine clay

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.T.; Nayak, B.U.

    A gravity corer was designed and fabricated for near shore sediment sampling. The corer was operated off Jaitapur, West Coast of India, and 70 cores were obtained. The performance of the corer was quite satisfactory. The core samples were soft clays...

  20. Black Carbon, The Pyrogenic Clay Mineral?

    Science.gov (United States)

    Most soils contain significant amounts of black carbon, much of which is present as discrete particles admixed with the coarse clay fraction (0.2–2.0 µm e.s.d.) and can be physically separated from the more abundant diffuse biogenic humic materials. Recent evidence has shown that naturally occurring...

  1. Clay Aerogel Supported Palladium Nanoparticles as Catalysts

    Directory of Open Access Journals (Sweden)

    Jared J. Griebel

    2016-04-01

    Full Text Available Highly porous, low density palladium nanoparticle/clay aerogel materials have been produced and demonstrated to possess significant catalytic activity for olefin hydrogenation and isomerization reactions at low/ambient pressures. This technology opens up a new route for the production of catalytic materials.

  2. Clay Corner: Recreating Chinese Bronze Vessels.

    Science.gov (United States)

    Gamble, Harriet

    1998-01-01

    Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

  3. Bauxite washing for the removal of clay

    Science.gov (United States)

    Ahmad, Ishaq; Hartge, Ernst-Ulrich; Werther, Joachim; Wischnewski, Reiner

    2014-11-01

    Clay impurities associated with bauxite negatively affect the Bayer process for alumina production. These impurities should be removed as far as possible by a beneficiation technique before the ore is used as feed for the Bayer process. In this current investigation, bauxite washing was conducted in the laboratory. Bauxite washing is a physical process that causes the disintegration and deagglomeration of the clay matrix, and bauxite is liberated from the clay (mainly rich in silica). Subsequently, separation occurs with the assistance of wet screening at a predetermined cut size. Three techniques were investigated in the laboratory: drum washing, water-jet washing, and ultrasonic washing. Various operating parameters were investigated for drum washing and water-jet washing, including materials retention time, drum rotation speed, solid concentration, water-jet spray duration, pressure, and height. We concluded that the retention time of bauxite inside the drum at a solid concentration of 55wt% and a drum rotation speed of 31 r/min is the dominant parameter for the removal of clay from the bauxite surface.

  4. Examination of effective stress in clay rock

    Directory of Open Access Journals (Sweden)

    Chun-Liang Zhang

    2017-06-01

    Full Text Available This paper examines the effective stress in indurated clay rock theoretically and experimentally. A stress concept is derived from the analysis of the microstructure and of the pore water in the highly-indurated Callovo-Oxfordian and Opalinus clay rocks, and subsequently validated by various experiments performed on these claystones. The concept suggests that the interparticle or effective stress in a dense clay–water system is transferred through both the adsorbed interparticle pore water in narrow pores and the solid–solid contact between non-clay mineral grains. The experiments show that the adsorbed pore water in the claystones is capable of bearing deviatoric effective stresses up to the failure strength. The applied stresses are for the most part or even totally transferred by the bound pore water, i.e. the swelling pressure in the interparticle bound pore water is almost equivalent to the effective stress. This stress concept provides a reasonable view to the nature of the effective stress in argillaceous rock and forms the fundamental basis for studies of the hydro-mechanical properties and processes in clay formations.

  5. HYDRAULIC CONDUCTIVITY OF THREE GEOSYNTHETIC CLAY LINERS

    Science.gov (United States)

    The hydraulic conductivity of three 2.9 m2 (32 sq ft) geosynthetic clay liners (GCLs) was measured. Tests were performed on individual sheets of the GCLs, on overlapped pieces of GCLs, and on composite liners consisting of a punctured geomembrane overlying a GCL. Hyd...

  6. Solute transport in cracking clay soils

    NARCIS (Netherlands)

    Bronswijk, J.J.B.; Ritsema, C.J.; Oostindie, K.; Hamminga, P.

    1996-01-01

    A bromide tracer applied to a cracked clay soil was adsorbed in the soil matrix close to the soil surface. Upon subsequent precipitation, a small part of the bromide dissolved and flowed rapidly through cracks to the subsoil and the groundwater. As a result, the groundwater and the drain discharge

  7. geotechnical characteristics of some southwestern nigeria clays as ...

    African Journals Online (AJOL)

    their suitability for use as barrier soils in waste disposal sites. ... Permeability, Barrier Soils, Clays, Leachate, Containment, Attenuation. 17 ... disposal facilities involving burial in natural clay ... them the probability of groundwater pollution by.

  8. Quantitative approach on SEM images of microstructure of clay soils

    Institute of Scientific and Technical Information of China (English)

    施斌; 李生林; M.Tolkachev

    1995-01-01

    The working principles of Videolab Image Processing System (VIPS), the examining methods of orientation of microstructural units of clay soils and analysing results on SEM images of some typical microstructures of clay soils using the VIPS are introduced.

  9. Climate change and sustainability of the carbon sink in Maritime salt marshes

    Energy Technology Data Exchange (ETDEWEB)

    Chmura, G.L. [McGill Univ., Montreal, PQ (Canada). Dept. of Geography, Global Environmental and Climate Change Centre

    2008-07-01

    Ideal carbon sinks do not emit greenhouse gases (GHGs) and are sustainable with future trends in global warming. This presentation discussed the potential for using Maritime salt marshes as carbon sinks. The marshes are covered with grasses adapted to saline soils. Photosynthesis by the marsh plants and algae fix the carbon dioxide (CO{sub 2}) directly from the atmosphere. The carbon is then buried by mineral sediment. Wetlands without saline water are known to produce methane. The carbon in salt marsh soils does not significantly decline with depth or time. Salt marshes and mangroves store an average of 210 g of CO{sub 2} per m{sup 2} per year. The tidal floodwaters keep the soils wet, which allows for slow decomposition. Canadian salt marsh soils have increased in thickness at a rate of between 2 to 4 mm per year. Measurement programs have demonstrated the sustainability of inner Bay of Fundy marshes in relation to rising sea levels. Opportunities for carbon sinks also exist in dyked marshes in the region. It was concluded that the salt marshes can account for between 4 to 6 per cent of Canada's targeted reductions under the Kyoto Protocol. tabs., figs.

  10. How sea level rise affects sedimentation, plant growth, and carbon accumulation on coastal salt marshes

    Science.gov (United States)

    Mudd, S. M.; Howell, S. M.; Morris, J. T.

    2009-12-01

    The rate of accretion on coastal salt marshes depends on feedbacks between flow, macrophyte growth, and sedimentation. Under favourable conditions, marsh accretion rates will keep pace with the local rate of sea level rise. Marsh accretion is driven by both organic and inorganic sedimentation; mineral rich marshes will need less organic sedimentation to keep pace with sea level rise. Here we use a numerical model of marsh accretion, calibrated by sediment cores, to explore the relationship between sea level rise and carbon sequestration on salt marshes in the face of differing supplies of inorganic sediment. The model predicts that changes in carbon storage resulting from changing sediment supply or sea-level rise are strongly dependant on the background sediment supply: if inorganic sediment supply is reduced in an already sediment poor marsh the storage of organic carbon will increase to a far greater extent than in a sediment-rich marsh, provided that the rate of sea-level rise does not exceed a threshold. These results imply that altering sediment supply to estuaries (e.g., by damming upstream rivers or altering littoral sediment transport) could lead to significant changes in the carbon budgets of coastal salt marshes.

  11. Estuaries as filters: the role of tidal marshes in trace metal removal.

    Directory of Open Access Journals (Sweden)

    Johannes Teuchies

    Full Text Available Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary.

  12. Estuaries as Filters: The Role of Tidal Marshes in Trace Metal Removal

    Science.gov (United States)

    Teuchies, Johannes; Vandenbruwaene, Wouter; Carpentier, Roos; Bervoets, Lieven; Temmerman, Stijn; Wang, Chen; Maris, Tom; Cox, Tom J. S.; Van Braeckel, Alexander; Meire, Patrick

    2013-01-01

    Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary. PMID:23950927

  13. Assessing tidal marsh vulnerability to sea-level rise in the Skagit Delta

    Science.gov (United States)

    Hood, W. Gregory; Grossman, Eric E.; Curt Veldhuisen,

    2016-01-01

    Historical aerial photographs, from 1937 to the present, show Skagit Delta tidal marshes prograding into Skagit Bay for most of the record, but the progradation rates have been steadily declining and the marshes have begun to erode in recent decades despite the large suspended sediment load provided by the Skagit River. In an area of the delta isolated from direct riverine sediment supply by anthropogenic blockage of historical distributaries, 0.5-m tall marsh cliffs along with concave marsh profiles indicate wave erosion is contributing to marsh retreat. This is further supported by a “natural experiment” provided by rocky outcrops that shelter high marsh in their lee, while being bounded by 0.5-m lower eroded marsh to windward and on either side. Coastal wetlands with high sediment supply are thought to be resilient to sea level rise, but the case of the Skagit Delta shows this is not necessarily true. A combination of sea level rise and wave-generated erosion may overwhelm sediment supply. Additionally, anthropogenic obstruction of historical distributaries and levee construction along the remaining distributaries likely increase the jet momentum of river discharge, forcing much suspended sediment to bypass the tidal marshes and be exported from Skagit Bay. Adaptive response to the threat of climate change related sea level rise and increased wave frequency or intensity should consider the efficacy of restoring historical distributaries and managed retreat of constrictive river levees to maximize sediment delivery to delta marshes.

  14. Mosquitoes Associated with Ditch-Plugged and Control Tidal Salt Marshes on the Delmarva Peninsula

    Directory of Open Access Journals (Sweden)

    Paul T. Leisnham

    2011-07-01

    Full Text Available A study was conducted during the summer of 2009 (from July to September to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November ditches were plugged near their outlets in two (‘experimental’ marshes with the aim to restore their natural tidal hydrology. The three other marshes were not plugged. Marshes were sampled from July to September in 2009 by using standard dip count method. A total of 2,457 mosquito larvae representing six species were collected on 15.4% (86/557 of all sample occasions and 399 adults representing four mosquito species were collected from landing counts. Aedes sollicitans, Anopheles bradleyi and Culex salinarius were the most common species collected in larval habitats, and Ae. sollicitans was the most common adult collected. Wooded habitats had more total mosquitoes, were also more frequently occupied by mosquitoes and had higher densities of mosquitoes than marsh habitats. Almost all larvae collected from marshes were from one experimental and one control site. The majority of larvae at the control site were Ae. sollicitans in marsh pannes while Cx. salinarius, An. bradleyi, Ae. cantator, and Ae. sollicitans were collected in high numbers from ditches at the experimental site. We found a difference in the proportion of marsh pannes occupied by Ae. sollicitans but not total mosquitoes sampled 4–5 days after spring tide events than on other occasions. Salinity measures of 42 larval habitats showed lower median salinity in mosquito-occupied habitats (11.5 ppt than unoccupied habitats (20.1 ppt, and in habitats in wooded areas followed by ditches and pannes in marsh areas. The results of

  15. Mosquitoes associated with ditch-plugged and control tidal salt marshes on the Delmarva Peninsula.

    Science.gov (United States)

    Leisnham, Paul T; Sandoval-Mohapatra, Sarah

    2011-08-01

    A study was conducted during the summer of 2009 (from July to September) to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November) ditches were plugged near their outlets in two ('experimental') marshes with the aim to restore their natural tidal hydrology. The three other marshes were not plugged. Marshes were sampled from July to September in 2009 by using standard dip count method. A total of 2,457 mosquito larvae representing six species were collected on 15.4% (86/557) of all sample occasions and 399 adults representing four mosquito species were collected from landing counts. Aedes sollicitans, Anopheles bradleyi and Culex salinarius were the most common species collected in larval habitats, and Ae. sollicitans was the most common adult collected. Wooded habitats had more total mosquitoes, were also more frequently occupied by mosquitoes and had higher densities of mosquitoes than marsh habitats. Almost all larvae collected from marshes were from one experimental and one control site. The majority of larvae at the control site were Ae. sollicitans in marsh pannes while Cx. salinarius, An. bradleyi, Ae. cantator, and Ae. sollicitans were collected in high numbers from ditches at the experimental site. We found a difference in the proportion of marsh pannes occupied by Ae. sollicitans but not total mosquitoes sampled 4-5 days after spring tide events than on other occasions. Salinity measures of 42 larval habitats showed lower median salinity in mosquito-occupied habitats (11.5 ppt) than unoccupied habitats (20.1 ppt), and in habitats in wooded areas followed by ditches and pannes in marsh areas. The results of this study suggest

  16. Carbon Sequestration in Tidal Salt Marshes of the Northeast United States.

    Science.gov (United States)

    Drake, Katherine; Halifax, Holly; Adamowicz, Susan C; Craft, Christopher

    2015-10-01

    Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m(2) compared to 16.2 kg C/m(2) in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on (137)Cs and (210)Pb dating of soil cores, ranged from 41 to 152 g/m(2)/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands.

  17. Impact of Mississippi River freshwater reintroduction on enhancing marsh accretionary processes in a Louisiana estuary

    Science.gov (United States)

    DeLaune, R. D.; Jugsujinda, A.; Peterson, G. W.; Patrick, W. H.

    2003-11-01

    To counteract extensive wetland loss a series of diversion projects have been implemented to introduce freshwater and sediment from the Mississippi River into Louisiana coastal wetlands. To keep pace with increases in water level due to subsidence Louisiana coastal marshes must vertically accrete through the accumulation of both organic matter and mineral sediment. The impact of Mississippi River freshwater diversion on enhancing vertical marsh accretion (mineral and organic matter accumulation) was examined in Breton Sound estuary, a coastal wetland experiencing marsh deterioration as result of subsidence and salt water intrusion. Using 137Cs dating and artificial marker horizons, increases in the rate of vertical marsh accretion were measured at marsh sites along a spatial gradient which has been receiving diverted water from the Mississippi River (Caernarvon diversion) since 1991. Vertical accretion and accumulation of mineral sediment organic matter and nutrients in the marsh soil profile, increased at marsh sites receiving freshwater and sediment input. Iron and manganese content of the marsh surface sediment were shown to be an excellent signature of riverine sediment deposition. Soil extractable phosphorus was higher and extractable sodium was lower at sites nearest freshwater and sediment input. Results demonstrated that freshwater diversion through sediment input and lowering of salinity will enhance marsh accretion and stability, slowing or reversing the rate of wetland loss.

  18. Temporal and spatial variation of arbuscular mycorrhizas in salt marsh plants of the Tagus estuary (Portugal).

    Science.gov (United States)

    Carvalho, L M; Caçador, I; Martins-Loução, M

    2001-12-01

    The factors which may influence temporal and spatial variation in plant arbuscular mycorrhizal (AM) colonization and propagule occurrence were evaluated in a Portuguese salt marsh poor in plant diversity. Two distinct sites were studied: a more-flooded (low marsh) and a less-flooded zone (high marsh). AM root colonization, AM fungal spore number and inoculum potential, soil edaphic parameters and tidal flooding time periods were analysed. Levels of AM colonization were considerable in Aster tripolium and Inula crithmoides but very low in Puccinellia maritima and non-existent in Spartina maritima, Halimione portulacoides, Arthrocnemum fruticosum and Arthrocnemum perenne. Fungal diversity was very low, with Glomus geosporum dominant at both marsh zones. Colonization showed no spatial variation within marsh zones but temporal variation was observed in the high marsh, dependent on plant phenological phases. In the low marsh, no significantly seasonal variation was observed. Apparently, plant phenological events were diluted by stressful conditions (e.g. flooding, salinity). Spore density was significantly different between marsh zones and showed temporal variation in both zones. This study showed that distribution of mycorrhizas in salt marsh is more dependent on host plant species than on environmental stresses.

  19. Coastal marsh response to rising sea levels in the Grand Bay, MS estuary

    Science.gov (United States)

    Alizad, K.; Hagen, S. C.; Morris, J. T.; Medeiros, S. C.; Bilskie, M. V.; Passeri, D. L.

    2015-12-01

    The Grand Bay estuary, situated along the border of Alabama and Mississippi, is a marine dominant estuary. Juncus roemerianus and Spartina alterniflora cover approximately 49% of the estuary (Eleuterius and Criss, 1991); However, this marsh system is prone to erosion more than other marsh systems in the state (Mississippi Department of Marine Resources 1999). Water level and wind-driven waves are critical factors that cause erosion in the Grand Bay estuary. Sediment transport induced by wave forces from the Gulf of Mexico and sea level rise force salt marshes to migrate landward (Schmid 2000). Understanding projected variations in vegetation can aid in productive restoration planning and coastal management decisions. An integrated hydro-marsh model was developed to incorporate the dynamic interaction between tidal hydrodynamics and salt marsh system. This model projects salt marsh productivity by coupling a two-dimensional, depth-integrated ADvanced CIRCulation (ADCIRC) finite element model and a parametric marsh model (Morris et al., 2002). The model calculates marsh productivity as a function of mean low water (MLW), mean high water (MHW), and the elevation of the marsh platform. The coupling exchange process is divided into several time intervals that capture the rate of sea level rise, and update the elevation and bottom friction from the computed marsh productivity. Accurate description of salt marsh platform is necessary for calculating accurate biomass results (Hagen et al. 2013). Lidar-derived digital elevation models (DEM) over-estimate marsh platform elevations, but can be corrected with Real Time Kinematic (RTK) survey data (Medeiros et al., 2015). Using RTK data, the salt marsh platform was updated and included in a high resolution hydrodynamic model. Four projections of sea level rise (Parris et al., 2012) were used to project salt marsh productivity for the year 2100 for the Grand Bay, MS estuary. The results showed a higher productivity under low sea

  20. A global analysis of the seaward salt marsh extent: The importance of tidal range

    Science.gov (United States)

    Balke, Thorsten; Stock, Martin; Jensen, Kai; Bouma, Tjeerd J.; Kleyer, Michael

    2016-05-01

    Despite the growing interest in ecosystem services provided by intertidal wetlands, we lack sufficient understanding of the processes that determine the seaward extent of salt marsh vegetation on tidal flats. With the present study, we aim to establish a globally valid demarcation between tidal flats and salt marsh vegetation in relation to tidal range. By comparing results from a regional GIS study with a global literature search on the salt marsh-tidal flat border, we are able to define the global critical elevation, above which salt marsh plants can grow in the intertidal zone. Moreover, we calculate inundation characteristics from global tide gauge records to determine inundation duration and frequency at this predicted salt marsh-tidal flat border depending on tidal range. Our study shows that the height difference between the lowest elevation of salt marsh pioneer vegetation and mean high water increases logarithmically with tidal range when including macrotidal salt marshes. Hence, the potentially vegetated section of the tidal frame below mean high water does not proportionally increase with tidal range. The data analysis suggests that inundation frequency rather than duration defines the global lower elevational limit of vascular salt marsh plants on tidal flats. This is critical information to better estimate sea level rise and coastal change effects on lateral marsh development.

  1. Deformation mechanisms in experimentally deformed Boom Clay

    Science.gov (United States)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  2. Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications

    CSIR Research Space (South Africa)

    Musyoka, Nicholas M

    2014-10-01

    Full Text Available Clay and its recrystallized zeolitic derivatives were used in this study as templating agents for carbon nanostructured materials. The conventional nanocasting process that involves impregnation with furfural alcohol and subsequent chemical vapour...

  3. Spatial Patterns of Plant Litter and Sedimentation in a Tidal Freshwater Marsh and Implications for Marsh Persistence

    Science.gov (United States)

    Elmore, A. J.; Cadol, D. D.; Palinkas, C. M.; Engelhardt, K. A.

    2014-12-01

    The maintenance of marsh platform elevation under sea level rise is dependent on sedimentation and biomass conversion to soil organic material. These physical and biological processes interact within the tidal zone, resulting in elevation-dependent processes contributing to marsh accretion. Here we explore spatial pattern in plant litter, a variable related to productivity, to understand its role in physical and biological interactions in a freshwater marsh. Plant litter that persists through the dormant season has an extended period of influence on ecosystem processes. We conducted a field and remote sensing analysis of plant litter height, biomass, vertical cover, and stem density (collectively termed plant litter structure) at a tidal freshwater marsh located along the Potomac River estuary. We completed two years of repeat RTK GPS surveys with corresponding measurements of litter height (over 2000 observations) to train a non-parametric random forest decision tree to predict litter height. LiDAR and field observations show that plant litter height increases with increasing elevation, although important deviations from this relationship are apparent. These spatial patterns exhibit stability from year to year and lead to corresponding patterns in soil organic matter content, revealed by loss on ignition of surface sediments. The amount of mineral material embedded within plant litter decreases with increasing elevation, representing an important trade-off with litter structure. Therefore, at low elevations where litter structure is short and sparse, the role of plant litter is to capture sediment; at high elevations where litter structure is tall and dense, litter contributes organic matter to soil development. Despite these tradeoffs, changes in elevation over time are consistent across elevation, with only small positive differences in elevation gain over time at elevations where the most sediment is deposited or where litter exhibits the most biomass.

  4. Habitat Characteristics and Eggshell Distribution of the Salt Marsh Mosquito, Aedes vigilax, in Marshes in Subtropical Eastern Australia

    OpenAIRE

    Dale, Pat E. R.; Knight, Jon; Kay, Brian H.; Chapman, Heather; Ritchie, Scott A.; Brown, Michael D.

    2008-01-01

    Research at 10 locations in coastal subtropical Queensland, Australia, has shown that salt marshes contained heterogeneous distributions of eggshells of the pest and vector mosquito Aedes vigilax (Skuse) (Diptera:Culicidae). The eggshell distribution was related to specific vegetation assemblages, with a mix of the grass, Sporobolus virginicus (L.) Kunth (Poales: Poaceae), and the beaded glasswort, Sarcocornia quinqueflora (Bunge ex (Ung.-Stern) A.J. Scott (Caryophyllales: Chenopodiaceae), as...

  5. Glowing clay: Real time tracing using a suite of novel clay based fluorescent tracers

    Science.gov (United States)

    Hardy, Robert; Quinton, John; Pates, Jackie; Coogan, Mike

    2015-04-01

    Clay is one of the most mobile fractions of soil due to its small particle size. It is also known to sorb many chemicals, such as nutrients (notably phosphorus), agrochemicals and heavy metals. The movement of clay is therefore linked with the transport and fate of these substances. A novel fluorescent clay tracing suite has been produced, together with an imaging technique. This suite consists of qualitative clay tracers, using rhodamine based fluorophores, and quantitative clay tracers, using metal based fluorophores. Efforts have also been made to allow integration of commercially available tracers, which are silt and sand sized. The clay tracers exploit the high affinity that montmorillonite has for Rhodamine B and Ru(bpy)3. This allows for an extremely thin layer of the fluorophore to be sorbed onto the clay's surface, in much that same way as materials in the natural environment will bind to clay. The tracer that is produced retains key chemical and physical properties of clay, such as size, shape and density. The retention of these micro-properties results in the retention of macro-properties, such as tendency to aggregate and cracking on drying. Imaging techniques have been developed to analyse these tracers. The imaging system uses diffused laser light to excite the tracer and a modified DSLR camera to image the soil surface. The images have been compiled into a time lapse video showing the movement of clay over the course of a rainfall event. This is the first time that the quantitative movement of clay has been recorded over a soil surface in real time. 4D data can be extracted from the images allowing the spatial location and intensity of tracer to be monitored over time, with mm precision and on the timescale of seconds. As the system can also work with a commercial tracer it is possible to investigate the movement of particles of almost any size and over a range of scales from soil box to hillside. This allows users to access this technique without

  6. Transport of inorganic compounds through compacted clay

    Energy Technology Data Exchange (ETDEWEB)

    Liao, W.P.

    1989-01-01

    Compacted clay liners are widely utilized as leachate barrier in landfills for waste. The main purpose of this research was to study the transport of inorganic compounds through compacted clay. The subjects of interest included the diffusional migration of chemicals at low flow rates, the effective porosity of fine-grained soils, the transport of solutes in unsaturated clays, and the effect of adsorption processes on the transport of reactive solutes. Two clay soils, kaolinite and Lufkin clay, were used in the laboratory column tests and subjected to constant hydraulic gradients of 1 to 50. Inorganic tracers (Cl{sup {minus}} Br{sup {minus}}, K{sup +}, and Zn{sup 2+}) were added to the permeating water as a step input. Conclusions are: (a) the experimental data from soil specimens subjected to various gradients showed that diffusional transport did affect the migration of the tracers in fine-grained media. At low gradients, hydrodynamic dispersion was almost solely related to molecular diffusion rather than mechanical mixing; (b) the breakthrough curves for kaolinite specimens showed that the ratios of effective porosity to total porosity were 0.25 to 1.0. The effect of low effective porosity on transport of the tracers was much greater than that of diffusion; (c) the soils that were not presoaked before tracers were introduced had lower effective porosity and greater dispersion of solutes that did the presoaked soils; (d) no evidence of the existence of a threshold gradient was observed; and (e) the retardation factors predicted from batch equilibrium tests matched the results from column tests poorly, probably due to hydrodynamic effects or geochemical differences between the two soil/solution systems.

  7. RESEARCH OF SWELLING OF SUZAKH CLAYS

    Directory of Open Access Journals (Sweden)

    Kubetskiy Valeriy Leonidovich

    2012-07-01

    Full Text Available In the course of construction of Sangtudinsky hydropower plant-1 on the River Vakhsh, it was deemed necessary to identify clay swelling properties in the event of alterations of the humidity mode of fructured half-rock soils, or the Suzakh clay, that accommodated tunnel-shaped water outlets within a section that was 75 meters long. The depth of tunnels was about 100 m. Any interaction with swelling soils could lead to destruction of the tunnel lining. Suzakh clays demonstrated the following physical and mechanical properties: density of particles of soil ρ= 2,69 g/cm; soil density ρ = 2.40-2.47 g/cm; porosity of 8.2-10.8 %; ultimate resistance to uniaxial compression = 13.1-31.0 MPa. Water saturated clay samples disintegrated into cloddy fragments; the rate of a longitudinal ultrasonic wave in the area of unaltered soils was equal to = 2500 m/c; repulse coefficient k was equal to 15 MPa/m; solidity coefficient (according to Protodyakonov was equal to 1,5; modulus of deformation in the massif was equal to 0.23 х10 MPa. The author proposed a methodology and designed a pilot set of equipment units designated for the identification of the swelling properties of fractured half-rock soils. Results of the pilot unit operation are presented in the article. Swelling properties are based on the monolith testing results. The programme contemplated a set of experiments held in various limit states on the surface of monoliths. Dependence between the swelling pressure and the swelling deformation in the course of water saturation was identified. The experiment demonstrates that alterations of the humidity mode of free surface Suzakh clays cause the relative deformation of swelling up to 1.1 %, and if the lining is rigid, the swelling pressure can exceed 4 MPa.

  8. Clays and clay minerals in Bikaner: Sources, environment pollution and management

    Science.gov (United States)

    Gayatri, Sharma; Anu, Sharma

    2016-05-01

    Environmental pollution can also be caused by minerals which include natural as well as human activities. Rapid urbanization, consumerist life style, anthropogenic deeds are increasing environmental pollution day by day. Fluctuation in our ecosystem or polluted environment leads to many diseases and shows adverse effects on living organisms. The main aim of this paper is to highlight the environmental pollution from clays and clay minerals and their mitigation..

  9. Assessing wildlife benefits and carbon storage from restored and natural coastal marshes in the Nisqually River Delta: Determining marsh net ecosystem carbon balance

    Science.gov (United States)

    Anderson, Frank; Bergamaschi, Brian; Windham-Myers, Lisamarie; Woo, Isa; De La Cruz, Susan; Drexler, Judith; Byrd, Kristin; Thorne, Karen M.

    2016-06-24

    Working in partnership since 1996, the U.S. Fish and Wildlife Service and the Nisqually Indian Tribe have restored 902 acres of tidally influenced coastal marsh in the Nisqually River Delta (NRD), making it the largest estuary-restoration project in the Pacific Northwest to date. Marsh restoration increases the capacity of the estuary to support a diversity of wildlife species. Restoration also increases carbon (C) production of marsh plant communities that support food webs for wildlife and can help mitigate climate change through long-term C storage in marsh soils.In 2015, an interdisciplinary team of U.S. Geological Survey (USGS) researchers began to study the benefits of carbon for wetland wildlife and storage in the NRD. Our primary goals are (1) to identify the relative importance of the different carbon sources that support juvenile chinook (Oncorhynchus tshawytscha) food webs and contribute to current and historic peat formation, (2) to determine the net ecosystem carbon balance (NECB) in a reference marsh and a restoration marsh site, and (3) to model the sustainability of the reference and restoration marshes under projected sea-level rise conditions along with historical vegetation change. In this fact sheet, we focus on the main C sources and exchanges to determine NECB, including carbon dioxide (CO2) uptake through plant photosynthesis, the loss of CO2 through plant and soil respiration, emissions of methane (CH4), and the lateral movement or leaching loss of C in tidal waters.

  10. Use of clay from kangerlussuaq in the Greenlandic construction industry

    DEFF Research Database (Denmark)

    Belmonte, Louise Josefine; Villumsen, Arne; Ottosen, Lisbeth M.

    2010-01-01

    Clay material from Kangerlussuaq in West Greenland was characterised and its possible use for the production of bricks, expanded clay products and inert filler material was investigated. It was generally found that it was possible to use the clay in all of the above mentioned materials, although,...

  11. Organically modified clays as binders of fumonisins in feedstocks.

    Science.gov (United States)

    Baglieri, Andrea; Reyneri, Amedeo; Gennari, Mara; Nègre, Michèle

    2013-01-01

    This study reports an investigation on the ability of organically modified clays to bind mycotoxins, fumonisins B1 (FB1) and B2 (FB2). Organically modified clays are commercia materials prepared from natural clays, generally montmorillonite, by exchanging the inorganic cation with an ammonium organic cation. A screening experiment conducted on 13 organically modified clays and 3 nonmodified clays, used as controls, has confirmed that the presence of an organic cation in the clay interlayer promoted the adsorption of both fumonisins. On the basis of the results of the screening test, four modified clays and a Na-montmorillonite were selected for the determination of the adsorption kinetics and isotherms. On all the tested materials adsorption took place within one hour of contact with fumonisins solutions. Adsorption isotherms have pointed out that the modified clays exhibited a higher adsorptive capacity than the unmodified clay. It was also demonstrated that, notwithstanding the reduced structural difference between FB1 and FB2, they were differently adsorbed on the modified clays. Addition of 2% modified clays to contaminated maize allowed a reduction of more than 70% and 60% of the amount of FB1and FB2 released in solution. Although in vivo experiments are required to confirm the effectiveness of the organically modified clays, these preliminary results suggest that these materials are promising as fumonisins binders.

  12. Strength and Deformation Properties of Tertiary Clay at Moesgaard Museum

    DEFF Research Database (Denmark)

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    The tertiary clay at Moesgaard Museum near Aarhus in the eastern part of Jutland in Denmark is a highly plastic, glacially disturbed nappe of Viborg Clay. The clay is characterised as a swelling soil, which could lead to damaging of the building due to additional heave of the soil. To take...

  13. Instrumental characterization of clay by XRF, XRD and FTIR

    Indian Academy of Sciences (India)

    Preeti Sagar Nayak; B K Singh

    2007-06-01

    Instrumental characterizations of the clay were performed by different techniques such as XRF, XRD and FTIR. XRF shows the chemical compositions of the clay where Al-oxide and silica oxide are present in major quantity whereas XRD confirms the presence of these minerals in clay. FTIR studies show the presence of quartz, alumina, haematite and different mineral matters.

  14. Recovery of Porosity and Permeability for High Plasticity Clays

    DEFF Research Database (Denmark)

    Krogsbøll, Anette; Foged, Niels Nielsen

    Clays, which have been loaded to a high stress level, will under certain conditions keep low porosity and permeability due to the high degree of compression. In some situations it seems that porosity and permeability will recover to a very high extent when the clay is unloaded. This seems...... the clay will expand to an even higher porosity....

  15. Comparative evaluation of clays from Abakaliki Formation with ...

    African Journals Online (AJOL)

    Okeey Aghamelu

    varied from 5.9 to 8.0 centipoises for 10 g clay per 350 ml water. Some of these natural .... lignite to clay mud to improve its rheological and filtration properties. ... naturally active bentonitic clays from Wyoming and Texas which are used in the ...

  16. Characterization of groundwater dynamics in landslides in varved clays

    NARCIS (Netherlands)

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trièves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  17. Characterization of groundwater dynamics in landslides in varved clays

    NARCIS (Netherlands)

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trieves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  18. Geological Investigations on Boulder-Clay of E. Groningen

    NARCIS (Netherlands)

    Gijzel, van P.; Overweel, C.J.; Veenstra, H.J.

    1959-01-01

    In this article the results of a study on boulder-clay in the neighbourhood of Winschoten (N.E. Netherlands) are communicated (Chapter I). The underlying sediments of the boulder-clay in this area consist of fine preglacial sands and black clay. In the nuclei of the many drumlins a strongly ice-push

  19. Geological Investigations on Boulder-Clay of E. Groningen

    NARCIS (Netherlands)

    Gijzel, van P.; Overweel, C.J.; Veenstra, H.J.

    1959-01-01

    In this article the results of a study on boulder-clay in the neighbourhood of Winschoten (N.E. Netherlands) are communicated (Chapter I). The underlying sediments of the boulder-clay in this area consist of fine preglacial sands and black clay. In the nuclei of the many drumlins a strongly ice-push

  20. Polymer-clay nanocomposites obtained by solution polymerization of vinyl benzyl triammonium chloride in the presence of advanced functionalized clay

    Indian Academy of Sciences (India)

    Raluca Ianchis; Dan Donescu; Ludmila Otilia Cinteza; Violeta Purcar; Cristina Lavinia Nistor; Critian Petcu; Cristian Andi Nicolae; Raluca Gabor; Silviu Preda

    2014-05-01

    Polymer-clay nanocomposites were synthesized by solution polymerization method using advanced functionalized clay and vinyl benzyl trimethyl ammonium chloride as monomer. First stage consisted in the silylation of a commercial organo-modified clay-Cl 20A using alkoxysilanes with different chain lengths. In the second step, the synthesis and characterization of polymer-nanocomposites were followed. To evaluate the clay functionalization process as well as the final polymer-clay products, thermogravimetric,X-ray diffraction, dynamic light scattering, Fourier transform infrared spectroscopy and three test liquid contact angles analyses were used. The loss of ammonium ions from commercial clay, the grafting degree, the lengths and the nature of alkyl chain influence the dispersion of the advanced modified clay into the polymer solution and, furthermore, the properties of the final polymer-clay nanocomposite film.

  1. Changes in Marsh Vegetation, Stability and Dissolved Organic Carbon in Barataria Bay Marshes Following the Deepwater Horizon Oil Spill

    Science.gov (United States)

    Holloway, J. M.; Aiken, G.; Kokaly, R. F.; Heckman, D.; Butler, K.; Mills, C. T.; Hoefen, T. M.; Piazza, S.

    2010-12-01

    Coastal wetlands in Southern Louisiana were contaminated by the release of record volumes of oil between April and July 2010. Barataria Bay was extensively impacted, resulting in the oiling and dieback of marsh grasses along a discontinuous margin up to 30m into the marshes. Shoreline stability and biogeochemistry have been monitored over three site visits between between July 10 and August 25, 2010. Initial observations in early July were that grasses, dominantly shape Spartina alterniflora and shape Juncus roemerianus, were bent over under the weight of a thick oil coating. The bent-over grasses were broken off along some reaches, leaving a stubbled shoreline more susceptible to erosion. Repeated site visits in mid and late August found visible erosion along some of the effected shorelines. Water samples were collected from the shoreline marsh remnants and from visibly unaffected marshes to characterize dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). In spite of visible oil sheens in unfiltered water from contaminated shorelines and no visible sign of impact on vegetation in the “control” sites with no visible oil on vegetation, DOC concentrations were similar in impacted and visibly unimpacted sites in Barataria Bay. Subsequent samples in mid- and late-August had increased DOC concentrations relative to previous sample events regardless of whether the site was visibly impacted. There was a general increase in specific UV absorbance (SUVA), an index of aromaticity, with increasing DOC concentrations, either due to seasonal effects or continued dissolution of petroleum compounds. Further chemical characterization using fluorescence and gas chromatography will be used to confirm the presence of petroleum compounds. The ratio of DOC to TDN also increased over time, which may have implications for vegetation regrowth and plant community structure, including the shift of grass species dominating effected marshes. These initial findings suggest

  2. Impact of land-use change and hard structures on the evolution of fringing marsh shorelines

    Science.gov (United States)

    Mattheus, Christopher R.; Rodriguez, Antonio B.; McKee, Brent A.; Currin, Carolyn A.

    2010-07-01

    Estuarine fringe marshes provide essential ecosystem services to coastal regions, including carbon sequestration and provision of shelter and nursery grounds for aquatic and terrestrial animals. The ability of a marsh to sustain itself by vertical accretion in response to sea-level rise is, in part, limited by inorganic sediment supply. Models attempting to forecast salt-marsh response to future sea-level rise commonly ignore land-use changes, despite the recent coastal population boom and the potential of land-use changes to alter sediment sources and modify established sediment-transport pathways. This study investigates the impacts of landscape modifications, which are typical of coastal areas, on the nearshore sedimentation and edge evolution of two fringing marshes. The sites examined include a marsh fringing the upper bay and a marsh fringing a beach ridge on the estuarine shoreline of a barrier island. Both sites are located in the same estuarine system, have similar hydrologic settings and comparable vegetation densities. Previous work, marsh cores, and a historical record from aerial photos indicate that although the fringe marshes are in different geomorphic locations, prior to anthropogenic modifications they were similar in terms of nearshore-sediment composition, scarp-shoreline morphology, and shoreline trajectory. The upper-bay marsh was impacted by the introduction of tree farming in the watershed of a tributary creek to the upper bay, which increased upland erosion and caused higher sedimentation rates in the estuary. The back-barrier marsh, which received no contribution from the tree farm because it is distal with respect to river input, was modified by the installation of a pier and rock sill. Terrestrial LIDAR, surface elevation tables, and accretion rates obtained from radioisotope analyses show that the deforestation induced high rates of nearshore and marsh accretion at the upper-bay site, which is promoting marsh colonization and expansion

  3. Tidal marsh susceptibility to sea-level rise: importance of local-scale models

    Science.gov (United States)

    Thorne, Karen M.; Buffington, Kevin J.; Elliott-Fisk, Deborah L.; Takekawa, John Y.

    2015-01-01

    Increasing concern over sea-level rise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-level rise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-level rise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-level rise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-level rise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-level rise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus. Under mid and high sea-level rise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sea level. Our modeling assumed no marsh migration upslope due to human

  4. Intertidal salt marshes as an important source of inorganic carbon to the coastal ocean

    Science.gov (United States)

    Wang, Zhaohui Aleck; Kroeger, Kevin D.; Ganju, Neil K.; Gonneea, Meagan; Chu, Sophie N.

    2016-01-01

    Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO2parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC is added to tidal water, the buffering capacity first decreases to a minimum and then increases quickly. Large additions of marsh DIC can result in higher buffering capacity in ebbing tide than incoming tide. Alkalization of tidal water, which mostly occurs in the summer due to anaerobic respiration, can further modify buffering capacity. Marsh exports of DIC and alkalinity may have complex implications for the future, more acidified ocean. Marsh DIC export exhibits high variability over tidal and seasonal cycles, which is modulated by both marsh DIC generation and by water fluxes. The marsh DIC export of 414 g C m−2 yr−1, based on high-resolution measurements and modeling, is more than twice the previous estimates. It is a major term in the marsh carbon budget and translates to one of the largest carbon fluxes along the U.S. East Coast.

  5. How do salt-marsh ecosystems respond to changes in the environmental forcings?

    Science.gov (United States)

    D'Alpaos, A.; Mudd, S. M.; Carniello, L.

    2012-04-01

    How do salt-marsh ecosystems respond to changes in the environmental forcings? This is a question of paramount importance due to the critical role exerted by salt-marsh ecosystems within the tidal landscape. Salt marshes in fact buffer coastlines against, filter nutrients and pollutants from tidal waters, provide nursery areas for coastal biota, and serve as a sink for organic carbon. Observations of marsh degradation worldwide and the acceleration in the rate of global sea level rise highlight the importance of improving our understanding of the chief processes controlling salt-marsh response to current natural climate changes and to the effects of changes in sediment supply. To address this important issue, we have applied a analytical model of biomorphodynamic evolution of salt-marsh ecosystems in the vertical plane, accounting for two-way interactions between ecological and geomorphological processes. Our results show that marshes are more resilient to a step decrease in the rate of relative sea level rise (RRSLR) rather than to a step increase of the same magnitude. However, marshes respond more rapidly to an increase in sediment load or vegetation productivity, rather than to a decrease (of the same amount) in sediment load or vegetation productivity. We also observe that marsh stability is therefore positively correlated with tidal range: marshes with high tidal ranges respond more slowly to changes in the environmental forcings and therefore are less likely to be affected by perturbations. Finally, the model suggests that, in the case of a oscillating RRSLR, marsh stratigraphy will be unable to fully record short-term fluctuations in relative mean sea level, whereas it will be able to capture long-term fluctuations particularly in sediment rich, microtidal settings.

  6. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Directory of Open Access Journals (Sweden)

    Landrou Gnanli

    2017-01-01

    Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  7. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Science.gov (United States)

    Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

    2017-06-01

    In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  8. The Conservation of Tidal Marsh Birds: Guiding action at the intersection of our changing land and seascapes

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Project Objectives: To identify critical areas for tidal marsh bird conservation and identify which marshes and species in the Northeast/Mid‐Atlantic are most...

  9. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Green Cay National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Green...

  10. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Conscience Point NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  11. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Rhode Island NWR Complex

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Rhode...

  12. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Great Bay NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Great...

  13. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Great White Heron NWR : Final report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Great...

  14. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Bayou Teche NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Bayou...

  15. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Supawna Meadows NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  16. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Alligator River National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  17. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Caloosahatchee National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  18. Application of the Sea-Level Affecting Marshes Model (SLAMM 6) to Cedar Keys NWR : Revised report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Cedar...

  19. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Bon Secour National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Bon...

  20. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Eastern Neck NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  1. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Pinellas National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  2. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Shell Keys National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Shell...

  3. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.1) to Oyster Bay NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Oyster...

  4. Development of a Climate Change Adaptation Strategy for Management of Coastal Marsh Systems in Southern New England USA

    Science.gov (United States)

    Sea level rise is accelerating throughout the U.S. Northeast causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat ...

  5. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Mandalay National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  6. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Nomans Land Island NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on Nomans...

  7. Application of the Sea-Level Affecting Marshes Model (SLAMM 5.0) to Crystal River NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Sea-Level Affecting Marshes Model (SLAMM) report presents a model for projecting the effects of sea-level rise on coastal marshes and related habitats on...

  8. Discontinuity networks in mud stones: an apparent contradiction for boom clay at Mol, opalinus clay at Mont Terri, Callovo-Oxfordian silty clay at Bure

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M. [Centre de Geologie de l' Ingenieur, 75 - Paris (France); Mazurek, M. [Bern Univ., Rock-Water Interaction, Institute of Geological Sciences (Switzerland); Vandenberghe, N. [Katholieke Universiteit (KU), Lab. voor stratigrafie Leuven (Belgium)

    2005-07-01

    The Rupelian Boom Clay at Mol, Belgium, the lower Aalenian Opalinus Clay at Mont Terri Switzerland and the Callovo-Oxfordian silty clay at Bure, France, are currently studied in the framework of deep geological radioactive waste confinement. These three mud-stones are calcareous to variable degrees. They vary from plastic clay at Mol to hard rock at Bure. All three have similar mineralogical constituents, especially with regards to the clay minerals and include mixed layers of illite and montmorillonite. Remarkably, in outcrop sections of massive clay formations and mud-stone in general, it is very common to observe a network of discontinuities resembling the jointing in hard rock. As such jointing clearly would influence underground works it is imperative to examine whether or not the three mud-rock formations under discussion have such a discontinuity network in all their mass. (authors)

  9. Coatings and films derived from clay/wax nanocomposites

    Science.gov (United States)

    Chaiko, David J.; Leyva, Argentina A.

    2006-11-14

    The invention provides methods for making clay/wax nanocomposites and coatings and films of same with improved chemical resistance and gas barrier properties. The invention further provides methods for making and using emulsions of such clay/wax nanocomposites. Typically, an organophillic clay is combined with a wax or wax/polymer blend such that the cohesion energy of the clay matches that of the wax or wax/polymer blend. Suitable organophilic clays include mica and phyllosilicates that have been surface-treated with edge or edge and surface modifying agents. The resulting nanocomposites have applications as industrial coatings and in protective packaging.

  10. Dioxins in primary kaolin and secondary kaolinitic clays.

    Science.gov (United States)

    Schmitz, Martin; Scheeder, Georg; Bernau, Sarah; Dohrmann, Reiner; Germann, Klaus

    2011-01-15

    Since 1996 dioxins have been repeatedly detected worldwide in Tertiary ball clays used as anticaking agent in the production of animal feed and a variety of other applications. The dioxins of these natural clays are very unlikely of anthropogenic source, but no model of dioxin enrichment has been established. A hypothetical model is presented which explains the highly variable dioxin loadings of the Tertiary kaolinitic clays by natural addition during clay-sedimentation. To prove this hypothesis, Tertiary primary nonsedimentary kaolin and sedimentary kaolinitic clays were collected at three profiles in Europe and analyzed for mineralogy, chemistry, organic carbon, and polychlorinated dibenzo-p-dioxins/-furans (PCDD/F). Primary kaolin, kaolinitic, and lignitic clays contained almost no PCDFs. PCDD concentration differed markedly between primary kaolin (3-91 pg/g) and secondary kaolinitic clay (711-45935 pg/g), respectively, lignitic clays (13513-1191120 pg/g). The dioxin loading of secondary kaolinitic and lignitic clays is approximately 10 to a few thousand times higher than in the primary kaolin or recent environmental settings. The dioxin concentrations decrease from octachlorodibenzo-p-dioxin to the tetrachlorodibenzo-p-dioxins and exhibit the "natural formation pattern". No correlation between PCDD/F concentration and bulk composition of clays was found. These findings support the hypothesis of the enrichment of dioxin in clays during sedimentation.

  11. [Mechanisms of removing red tide organisms by organo-clays].

    Science.gov (United States)

    Cao, Xi-Hua; Song, Xiu-Xian; Yu, Zhi-Ming; Wang, Kui

    2006-08-01

    We tested the influence of the preparation conditions of the quaternary ammonium compounds (QACs) modified clays on their capacities to remove red tide organisms, then discussed the mechanisms of the organo-clays removing red tide organisms. Hexadecyltrimethylammonium (HDTMA) improved the capacity of clays to flocculate red tide algae, and the HDTMA in metastable state enhanced the toxicity of the clay complexes to algae. The capacities of the organo-clays correlated with the toxicity and the adsorbed amount of the QACs used in clays modification, but as the incubation time was prolonged the stability of the organo-clays was improved and the algal removal efficiencies of the clay complexes decreased. When the adsorbed HDTMA was arranged in different clays in which the spatial resistance was different, there was more HDTMA in metastable state in the three-layer montmorillonite. Because of the homo-ion effect the bivalent or trivalent metal ions induced more HDTMA in metastable state and the corresponding organo-clays had high capacities to remove red tide organisms. When the reaction temperature was 60 degrees C the adsorbed HDTMA was easily arranged on cation exchange sites, if the temperature rose or fell the metastable HDTMA would increase so that the capacity of the clays was improved.

  12. Resin injection in clays with high plasticity

    Science.gov (United States)

    Nowamooz, Hossein

    2016-11-01

    Regarding the injection process of polyurethane resins in clays with high plasticity, this paper presents the experimental results of the pressuremeter and cone penetration tests before and after injection. A very important increase in pressure limit or in soil resistance can be observed for all the studied depths close to the injection points. An analytical analysis for cylindrical pore cavity expansion in cohesive frictional soils obeying the Mohr-Coulomb criterion was then used to reproduce the pressuremeter tests before and after injection. The model parameters were calibrated by maintaining constant the elasticity parameters as well as the friction angel before and after injection. A significant increase in cohesion was observed because of soil densification after resin expansion. The estimated undrained cohesions, derived from the parameters of the Mohr-Coulomb criterion, were also compared with the cone penetration tests. Globally, the model predictions show the efficiency of resin injection in clay soils with high plasticity.

  13. Clay mineral type effect on bacterial enteropathogen survival in soil.

    Science.gov (United States)

    Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific.

  14. Ecosystem metabolism in a temporary Mediterranean marsh (Donana National Park, SW Spain)

    DEFF Research Database (Denmark)

    Geertz-Hansen, O.; Montes, C.; Duarte, C.M.

    2011-01-01

    metabolic balance of the open waters supporting submerged macrophytes of the Donana marsh (SW Spain) was investigated in spring, when community production is highest. The marsh community (benthic + pelagic) was net autotrophic with net community production rates averaging 0.61 g C m(-2) d(-1), an...

  15. Effects of salinity variations on pore water flow in salt marshes

    Science.gov (United States)

    Shen, Chengji; Jin, Guangqiu; Xin, Pei; Kong, Jun; Li, Ling

    2015-06-01

    Spatial and temporal salinity variations in surface water and pore water commonly exist in salt marshes under the combined influence of tidal inundation, precipitation, evapotranspiration, and inland freshwater input. Laboratory experiments and numerical simulations were conducted to investigate how density gradients associated with salinity variations affect pore water flow in the salt marsh system. The results showed that upward salinity (density) gradients could lead to flow instability and the formation of salt fingers. These fingers, varying in size with the distance from the creek, modified significantly the pore water flow field, especially in the marsh interior. While the flow instability enhanced local salt transport and mixing considerably, the net effect was small, causing only a slight increase in the overall mass exchange across the marsh surface. In contrast, downward salinity gradients exerted less influence on the pore water flow in the marsh soil and slightly weakened the surface water and groundwater exchange across the marsh surface. Numerical simulations revealed similar density effects on pore water flow at the field scale under realistic conditions. These findings have important implications for studies of marsh soil conditions concerning plant growth as well as nutrient exchange between the marsh and coastal marine system.

  16. COASTAL SALT MARSH COMMUNITY CHANGE IN NARRAGANSETT BAY IN RESPONSE TO CULTURAL EUTROPHICATION

    Science.gov (United States)

    Coastal salt marshes are susceptible to cultural eutrophication, particularly the over-enrichment of nitrogen, because they are often located where surface water and groundwater discharge into estuaries. In this report, the current areal extent of coastal salt marshes in Narrag...

  17. POTENTIAL FOR THE DEVELOPMENT OF MARSH VEGETATION FROM THE SEED BANK AFTER A DRAWDOWN

    NARCIS (Netherlands)

    TERHEERDT, GNJ; DROST, HJ

    1994-01-01

    In the inundated part of the Oostvaardersplassen, a marsh in The Netherlands, most of the emergent vegetation disappeared due to herbivory and erosion, resulting in a shallow lake. The emergent vegetation was successfully re-established by means of a drawdown. A comparable flooded marsh was studied

  18. Common Marsh Plants of the United States and Canada. Resource Publication 93.

    Science.gov (United States)

    Hotchkiss, Neil

    Described in this guide are the emergent and semiemergent plants most likely to be found in inland and coastal marshes. The guide is intended for field identification of marsh plants without resources to technical botanical keys. The plants are discussed in seven groups. Within each group the kinds which resemble one another most closely are next…

  19. Influence of abiotic factors on spider and ground beetle communities in different salt-marsh systems

    NARCIS (Netherlands)

    Petillon, Julien; Georges, Anita; Canard, Alain; Lefeuvre, Jean-Claude; Bakker, Jan P.; Ysnel, Frederic

    2008-01-01

    Salt marshes are interesting and endangered ecosystems in West-Europe. Nevertheless, their arthropod fauna remains largely unknown and the factors determining assemblages at micro-habitat scale are poorly understood. Few data are also available about the effects of management measures in salt marshe

  20. Effects of Tide Stage on the Use of Salt Marshes by Wading Birds in Rhode Island

    Science.gov (United States)

    To determine how tide stage affects wading bird abundance, behavior, and foraging in three Narragansett Bay salt marshes (RI), we conducted surveys at 10-min intervals—across the full tidal range—during six days at each marsh in July/September of 2006. The wading bird community ...

  1. Parasite Recruitment and Host Risk in a Snail-Trematode System at Carpinteria Salt Marsh

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The project is located at Carpinteria Salt Marsh, part of the University of California Reserve System. The marsh is located at 34.40°N, 119.53°W, which is near the...

  2. Salt-marsh restoration : evaluating the success of de-embankments in north-west Europe

    NARCIS (Netherlands)

    Wolters, M; Garbutt, A; Bakker, JP

    2005-01-01

    De-embankment of historically reclaimed salt marshes has become a widespread option for re-creating salt marshes, but to date little information exists on the success of de-embankments. One reason is the absence of pre-defined targets, impeding the measurement of success. In this review, success has

  3. Microbial community analysis of a coastal salt marsh affected by the Deepwater Horizon oil spill.

    Directory of Open Access Journals (Sweden)

    Melanie J Beazley

    Full Text Available Coastal salt marshes are highly sensitive wetland ecosystems that can sustain long-term impacts from anthropogenic events such as oil spills. In this study, we examined the microbial communities of a Gulf of Mexico coastal salt marsh during and after the influx of petroleum hydrocarbons following the Deepwater Horizon oil spill. Total hydrocarbon concentrations in salt marsh sediments were highest in June and July 2010 and decreased in September 2010. Coupled PhyloChip and GeoChip microarray analyses demonstrated that the microbial community structure and function of the extant salt marsh hydrocarbon-degrading microbial populations changed significantly during the study. The relative richness and abundance of phyla containing previously described hydrocarbon-degrading bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria increased in hydrocarbon-contaminated sediments and then decreased once hydrocarbons were below detection. Firmicutes, however, continued to increase in relative richness and abundance after hydrocarbon concentrations were below detection. Functional genes involved in hydrocarbon degradation were enriched in hydrocarbon-contaminated sediments then declined significantly (p<0.05 once hydrocarbon concentrations decreased. A greater decrease in hydrocarbon concentrations among marsh grass sediments compared to inlet sediments (lacking marsh grass suggests that the marsh rhizosphere microbial communities could also be contributing to hydrocarbon degradation. The results of this study provide a comprehensive view of microbial community structural and functional dynamics within perturbed salt marsh ecosystems.

  4. alpha- and beta-diversity in moth communities in salt marshes is driven by grazing management

    NARCIS (Netherlands)

    Rickert, C.; Fichtner, A.; van Klink, R.; Bakker, J. P.

    2012-01-01

    This study evaluates the effects of long-term sheep grazing in salt marshes on the diversity of moths and derives conclusive management suggestions for the conservation of invertebrate diversity in salt marshes. Study sites were located on the Hamburger Hallig, on the Western coast of Schleswig-Hols

  5. Comparison of Bottomless Lift Nets and Breder Traps for Sampling Salt-Marsh Nekton

    Science.gov (United States)

    Vegetated salt-marsh surfaces provide refuge, forage, and spawning habitat for estuarine nekton, yet are threatened by accelerating rates of sea-level rise in southern New England and elsewhere. Nekton responses to ongoing marsh surface changes need to be evaluated with effective...

  6. Tidal Creek Morphology and Sediment Type Influence Spatial Trends in Salt Marsh Vegetation

    DEFF Research Database (Denmark)

    Kim, Daehyun; Cairns, David M.; Bartholdy, Jesper

    2013-01-01

    Zonal patterns of salt marsh plants and physical conditions have been addressed primarily across the elevation gradient from inland to coastline rather than across tidal creeks in relation to their hydro-geomorphic processes such as bar formation and bank erosion. We found at a Danish marsh...

  7. Relationships between sediment microbial communities and pollutants in two California salt marshes.

    Science.gov (United States)

    Cao, Y; Cherr, G N; Córdova-Kreylos, A L; Fan, T W-M; Green, P G; Higashi, R M; Lamontagne, M G; Scow, K M; Vines, C A; Yuan, J; Holden, P A

    2006-11-01

    Salt marshes are important ecosystems whose plant and microbial communities can alter terrestrially derived pollutants prior to coastal water discharge. However, knowledge regarding relationships between anthropogenic pollutant levels and salt marsh microbial communities is limited, and salt marshes on the West Coast of the United States are rarely examined. In this study, we investigated the relationships between microbial community composition and 24 pollutants (20 metals and 4 organics) in two California salt marshes. Multivariate ordination techniques were used to assess how bacterial community composition, as determined by terminal restriction fragment length polymorphism and phospholipid fatty acid analyses, was related to pollution. Sea urchin embryo toxicity measurements and plant tissue metabolite profiles were considered two other biometrics of pollution. Spatial effects were strongly manifested across marshes and across channel elevations within marshes. Utilizing partial canonical correspondence analysis, an ordination technique new to microbial ecology, we found that several metals were strongly associated with microbial community composition after accounting for spatial effects. The major patterns in plant metabolite profiles were consistent with patterns across microbial community profiles, but sea urchin embryo assays, which are commonly used to evaluate ecological toxicity, had no identifiable relationships with pollution. Whereas salt marshes are generally dynamic and complex habitats, microbial communities in these marshes appear to be relatively sensitive indicators of toxic pollutants.

  8. Behaviour of horses and cattle at two stocking densities in a coastal salt marsh

    NARCIS (Netherlands)

    Nolte, S.; Weyde, van der C.; Esselink, P.; Smit, C.; Wieren, van S.E.; Bakker, J.P.

    2017-01-01

    Livestock grazing has been practiced in salt marshes in the Wadden Sea area since 600 B.C. Currently livestock grazing is also applied for conservation management. However, effects of such grazing management on salt marshes are likely to vary depending on the species of livestock and stocking

  9. Behaviour of horses and cattle at two stocking densities in a coastal salt marsh

    NARCIS (Netherlands)

    Nolte, S.; Van der Weyde, C; Esselink, Peter; Smit, C.; Van Wieren, S.E.; Bakker, Jan P.

    Livestock grazing has been practiced in salt marshes in the Wadden Sea area since 600 B.C. Currently livestock grazing is also applied for conservation management. However, effects of such grazing management on salt marshes are likely to vary depending on the species of livestock and stocking

  10. Differentiating climatic and successional influences on long-term development of a marsh

    Energy Technology Data Exchange (ETDEWEB)

    Singer, D.K.; Jackson, S.T. [Northern Arizona Univ., Flagstaff, AZ (United States); Madsen, B.J.; Wilcox, D.A. [Great Lakes Science Center, Ann Arbor, MI (United States)

    1996-09-01

    Comparison of long-term records of local wetland vegetation dynamics with regional, climate-forced terrestrial vegetation changes can be used to differentiate the rates and effects of autogenic successional processes and allogenic environmental change on wetland vegetation dynamics. We studied Holocene plant macrofossil and pollen sequences from Portage Marsh, a shallow, 18-ha marsh in northeastern Indiana. Between 10 000 and 5700 yr BP the basin was occupied by a shallow, open lake, while upland vegetation consisted of mesic forests of Pinus, Quercus, Ulmus, and Carya. At 5700 yr BP the open lake was replaced rapidly by a shallow marsh, while simultaneously Quercus savanna developed on the surrounding uplands. The marsh was characterized by periodic drawdowns, and the uplands by periodic fires. Species composition of the marsh underwent further changes between 3000 and 2000 yr BP. Upland pollen spectra at Portage Marsh and other sites in the region shifted towards more mesic vegetation during that period. The consistency and temporal correspondence between the changes in upland vegetation and marsh vegetation indicate that the major vegetational changes in the marsh during the Holocene resulted from hydrologic changes forced by regional climate change. Progressive shallowing of the basin by autogenic accumulation of organic sediment constrained vegetational responses to climate change but did not serve as the direct mechanism of change. 84 refs., 7 figs., 2 tabs.

  11. Burrowing and foraging activity of marsh crabs under different inundation regimes

    Science.gov (United States)

    New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on...

  12. In Situ Burning Restores the Ecological Function and Structure of an Oil-Impacted Coastal Marsh

    Science.gov (United States)

    Baustian, Joseph; Mendelssohn, Irving; Lin, Qianxin; Rapp, John

    2010-11-01

    As the use of in situ burning for oil spill remediation in coastal wetlands accelerates, the capacity of this procedure to restore the ecological structure and function of oil-impacted wetlands becomes increasingly important. Thus, our research focused on evaluating the functional and structural recovery of a coastal marsh in South Louisiana to an in situ burn following a Hurricane Katrina-induced oil spill. Permanent sampling plots were set up to monitor marsh recovery in the oiled and burned areas as well as non-oiled and non-burned (reference) marshes. Plots were monitored for species composition, stem density, above- and belowground productivity, marsh resiliency, soil chemistry, soil residual oil, and organic matter decomposition. The burn removed the majority of the oil from the marsh, and structurally the marsh recovered rapidly. Plant biomass and species composition returned to control levels within 9 months; however, species richness remained somewhat lower in the oiled and burned areas compared to the reference areas. Recovery of ecological function was also rapid following the in situ burn. Aboveground and belowground plant productivity recovered within one growing season, and although decomposition rates were initially higher in the oiled areas, over time they became equivalent to those in reference sites. Also, marsh resiliency, i.e., the rate of recovery from our applied disturbances, was not affected by the in situ burn. We conclude that in situ burning is an effective way to remove oil and allow ecosystem recovery in coastal marshes.

  13. Marsh vertical accretion in a Southern California Estuary, U.S.A

    Science.gov (United States)

    Cahoon, D.R.; Lynch, J.C.; Powell, A.N.

    1996-01-01

    Vertical accretion was measured between October 1992 and March 1994 in low and high saltmarsh zones in the north arm of Tijuana estuary from feldspar market horizons and soil corings. Accretion in the Spartina foliosa low marsh (2-8.5 cm) was related almost entirely to episodic storm-induced river flows between January and March 1993, with daily tidal flooding contributing little or no sediment during the subsequent 12 month period of no river flow. Accretion in the Salicornia subterminalis high marsh was low (~1-2 mm) throughout the 17-month measuring period. High water levels in the salt marsh associated with the storm flows were enhanced in early January 1993 by the monthly extreme high sea level, when the low and high marshes were flooded about 0.5 m above normal high tide levels. Storm flows in January-March 1993 mobilized about 5 million tons of sediment, of which the low salt marsh trapped an estimated 31,941 tonnes, including 971 tonnes of carbon and 77 tonnes of nitrogen. Sediment trapping by the salt marsh during episodic winter floods plays an important role in the long-term maintenance of productivity of Tijuana estuary through nutrient retention and maintenance of marsh surface elevation. The potential exists, however, for predicted accelerated rates of sea-level rise to out-pace marsh surface elevation gain during extended periods of drought (i.e. low sediment inputs) which are not uncommon for this arid region.

  14. alpha- and beta-diversity in moth communities in salt marshes is driven by grazing management

    NARCIS (Netherlands)

    Rickert, C.; Fichtner, A.; van Klink, R.; Bakker, J. P.

    2012-01-01

    This study evaluates the effects of long-term sheep grazing in salt marshes on the diversity of moths and derives conclusive management suggestions for the conservation of invertebrate diversity in salt marshes. Study sites were located on the Hamburger Hallig, on the Western coast of Schleswig-Hols

  15. Guide to Common Tidal Marsh Invertebrates of the Northeastern Gulf of Mexico.

    Science.gov (United States)

    Heard, Richard W.

    The major groups of marine and estuarine macroinvertebrates of the tidal marshes of the northern Gulf of Mexico are described in this guide for students, taxonomists and generalists. Information on the recognition characteristics, distribution, habitat, and biology of salt marsh species from the coelenterate, annelid, mollusk and arthropod phyla…

  16. Effects of long-term grazing on sediment deposition and salt-marsh accretion rates

    Science.gov (United States)

    Elschot, Kelly; Bouma, Tjeerd J.; Temmerman, Stijn; Bakker, Jan P.

    2013-11-01

    Many studies have attempted to predict whether coastal marshes will be able to keep up with future acceleration of sea-level rise by estimating marsh accretion rates. However, there are few studies focussing on the long-term effects of herbivores on vegetation structure and subsequent effects on marsh accretion. Deposition of fine-grained, mineral sediment during tidal inundations, together with organic matter accumulation from the local vegetation, positively affects accretion rates of marsh surfaces. Tall vegetation can enhance sediment deposition by reducing current flow and wave action. Herbivores shorten vegetation height and this could potentially reduce sediment deposition. This study estimated the effects of herbivores on 1) vegetation height, 2) sediment deposition and 3) resulting marsh accretion after long-term (at least 16 years) herbivore exclusion of both small (i.e. hare and goose) and large grazers (i.e. cattle) for marshes of different ages. Our results firstly showed that both small and large herbivores can have a major impact on vegetation height. Secondly, grazing processes did not affect sediment deposition. Finally, trampling by large grazers affected marsh accretion rates by compacting the soil. In many European marshes, grazing is used as a tool in nature management as well as for agricultural purposes. Thus, we propose that soil compaction by large grazers should be taken in account when estimating the ability of coastal systems to cope with an accelerating sea-level rise.

  17. Effects of long-term grazing on sediment deposition and salt-marsh accretion rates

    NARCIS (Netherlands)

    Elschot, K.; Bouma, T.J.; Temmerman, S.; Bakker, J.P.

    2013-01-01

    Many studies have attempted to predict whether coastal marshes will be able to keep up with future acceleration of sea-level rise by estimating marsh accretion rates. However, there are few studies focussing on the long-term effects of herbivores on vegetation structure and subsequent effects on mar

  18. Napa River Salt Marsh Restoration Project. Volume 2: Environmental Impact Statement Comments Letters and Response

    Science.gov (United States)

    2004-06-01

    Sacramento splittail, San Pablo song sparrows, Point Reyes and soft bird’s beak, salt marsh harvest mice, clapper and black rails, and salt marsh...brackish and 5-12 saline waters on site are generally unsuitable for the red-legged frog (Rana aurora draytoni). The western pond turtle (Clemmys marmorata

  19. Below the Disappearing Marshes of an Urban Estuary: Historic Nitrogen Trends and Soil Structure

    Science.gov (United States)

    Marshes in the urban Jamaica Bay Estuary, New York, USA are disappearing at an average rate of 13 ha/yr, and multiple stressors (e.g., wastewater inputs, dredging activities, groundwater removal, and global warming) may be contributing to marsh losses. Among these stressors, wa...

  20. A New Approach to Monitoring Coastal Marshes for Persistent Flooding

    Science.gov (United States)

    Kalcic, M. T.; Undersood, Lauren W.; Fletcher, Rose

    2012-01-01

    Many areas in coastal Louisiana are below sea level and protected from flooding by a system of natural and man-made levees. Flooding is common when the levees are overtopped by storm surge or rising rivers. Many levees in this region are further stressed by erosion and subsidence. The floodwaters can become constricted by levees and trapped, causing prolonged inundation. Vegetative communities in coastal regions, from fresh swamp forest to saline marsh, can be negatively affected by inundation and changes in salinity. As saltwater persists, it can have a toxic effect upon marsh vegetation causing die off and conversion to open water types, destroying valuable species habitats. The length of time the water persists and the average annual salinity are important variables in modeling habitat switching (cover type change). Marsh type habitat switching affects fish, shellfish, and wildlife inhabitants, and can affect the regional ecosystem and economy. There are numerous restoration and revitalization projects underway in the coastal region, and their effects on the entire ecosystem need to be understood. For these reasons, monitoring persistent saltwater intrusion and inundation is important. For this study, persistent flooding in Louisiana coastal marshes was mapped using MODIS (Moderate Resolution Imaging Spectroradiometer) time series of a Normalized Difference Water Index (NDWI). The time series data were derived for 2000 through 2009, including flooding due to Hurricane Rita in 2005 and Hurricane Ike in 2008. Using the NDWI, duration and extent of flooding can be inferred. The Time Series Product Tool (TSPT), developed at NASA SSC, is a suite of software developed in MATLAB(R) that enables improved-quality time series images to be computed using advanced temporal processing techniques. This software has been used to compute time series for monitoring temporal changes in environmental phenomena, (e.g. NDVI times series from MODIS), and was modified and used to

  1. Clay mineralogy in agrochernozems of western Ukraine

    Science.gov (United States)

    Papish, I. Ya.; Chizhikova, N. P.; Poznyak, S. P.; Varlamov, E. B.

    2016-10-01

    The mineralogy of clay fractions separated from deep low-humus deep-gleyic loamy typical agrochernozems on loess-like loams of the Upper Bug and Dniester uplands in the Central Russian loess province of Ukraine consists of complex disordered interstratifications with the segregation of mica- and smectite-type layers (hereafter, smectite phase), tri- and dioctahedral hydromicas, kaolinite, and chlorite. The distribution of the clay fraction is uniform. The proportions of the layered silicates vary significantly within the profile: a decrease in the content of the smectite phase and a relative increase in the content of hydromicas up the soil profile are recorded. In the upper horizons, the contents of kaolinite and chlorite increase, and some amounts of fine quartz, potassium feldspars, and plagioclases are observed. This tendency is observed in agrochernozems developed on the both Upper Bug and Dniester uplands. The differences include the larger amounts of quartz, potassium feldspars, and plagioclases in the clay material of the Upper Bug Upland, while the contents of the smectite phase in the soil profiles of the areas considered are similar. An analogous mineral association is noted in podzolized agrochernozems on loess-like deposits in the Cis-Carpathian region of the Southern Russian loess province developed on the Prut-Dniester and Syan-Dniester uplands. The distribution of particle-size fractions and the mineralogy of the clay fraction indicate the lithogenic heterogeneity of the soil-forming substrate. When the drifts change, the mineral association of the soils developed within the loess-like deposits gives place to minerals dominated by individual smectite with some mica-smectite inter stratifications, hydromicas, and chlorite.

  2. Clay/polymer composites: the story

    OpenAIRE

    Fengge Gao

    2004-01-01

    Clay/polymer nanocomposites offer tremendous improvement in a wide range of physical and engineering properties for polymers with low filler loading. This technology can now be applied commercially and has received great attention in recent years. The major development in this field has been carried out over the last one and half decades. The progress, advantages, limitations, and current problems will be discussed in this review. So far, significant progress has been made in the development ...

  3. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes.

    Science.gov (United States)

    Leonardi, Nicoletta; Ganju, Neil K; Fagherazzi, Sergio

    2016-01-05

    Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

  4. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

    Science.gov (United States)

    Leonardi, Nicoletta; Ganju, Neil K.; Fagherazzi, Sergio

    2016-01-01

    Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

  5. Vegetation effects on fish distribution in impounded salt marshes

    Science.gov (United States)

    Stolen, Eric D.; Collazo, Jaime; Percival, H. Franklin

    2009-01-01

    We compared the density and biomass of resident fish in vegetated and unvegetated flooded habitats of impounded salt marshes in the northern Indian River Lagoon (IRL) Estuary of east-central Florida. A 1-m2 throw trap was used to sample fish in randomly located, paired sample plots (n = 198 pairs) over 5 seasons in 7 impoundments. We collected a total of 15 fish taxa, and 88% of the fishes we identified from the samples belonged to three species: Cyprinodon variegatus (Sheepshead Minnow), Gambusia holbrooki (Eastern Mosquitofish), and Poecilia latipinna (Sailfin Molly). Vegetated habitat usually had higher density and biomass of fish. Mean fish density (and 95% confidence interval) for vegetated and unvegetated sites were 8.2 (6.7–9.9) and 2.0 (1.6–2.4) individuals m-2, respectively; mean biomass (and 95%) confidence interval) for vegetated and unvegetated sites were 3.0 (2.5–3.7) and 1.1 (0.9–1.4) g m-2, respectively. We confirmed previous findings that impounded salt marshes of the northern IRL Estuary produce a high standing stock of resident fishes. Seasonal patterns of abundance were consistent with fish moving between vegetated and unvegetated habitat as water levels changed in the estuary. Differences in density, mean size, and species composition of resident fishes between vegetated and unvegetated habitats have important implications for movement of biomass and nutrients out of salt marsh by piscivores (e.g., wading birds and fishes) via a trophic relay.

  6. Oil Detection in a Coastal Marsh with Polarimetric SAR

    Science.gov (United States)

    Ramsey, E., III; Rangoonwala, A.; Suzuoki, Y.; Bannister, T.

    2011-09-01

    The NASA UAVSAR was deployed June 2010 to support Deep Water Horizon oil spill response activities specifically, oil detection and characterization, oil extent mapping in wetlands, coastal resource impact detection, and ecosystem recovery. The UAVSAR platform demonstrated enhanced capability to act rapidly and provide targeted mapping response. Our research focused on the effectiveness of high spatial resolution and fully polarimetric L-band Synthetic Aperture Radar (PolSAR) for mapping oil in wetlands, specifically within Barataria Bay in eastern coastal Louisiana. Barataria Bay contained a numerous site observations confirming spatially extensive shoreline oil impacts, multiple oil spill UAVSAR collections, and a near anniversary 2009 collection. PolSAR oil detection relied on decomposition and subsequent classifications of the single look complex (SLC) calibrated radar cross sections representing the complex elements of the scattering matrix. Initial analyses results found that shoreline marsh structural damage as well as oil on marsh plants and sediments without canopy structural damage were exhibited as anomalous features on post-spill SLC scenes but were not evident on the pre-spill SLC scene collected in 2009. Pre-spill and post-spill Freeman-Durden (FD) and Cloude-Pottier (CP) decompositions and the Wishart classifications seeded with the FD and CP classes (Wishart-FD) also highlighted these nearshore features as a change in dominate scatter from pre-spill to post-spill. SLC analyses also indicated penetration of oil ladened waters into interior marshes well past the immediate shorelines; however, these post-spill SLC analyses results could not be validated due to the lack of observational data and possible flooding in the pre-spill SLC scene.

  7. Climate changes in mangrove forests and salt marshes

    Directory of Open Access Journals (Sweden)

    Yara Schaeffer-Novelli

    Full Text Available Abstract This synthesis is framed within the scope of the Brazilian Benthic Coastal Habitat Monitoring Network (ReBentos WG 4: Mangroves and Salt Marshes, focusing on papers that examine biodiversity-climate interactions as well as human-induced factors including those that decrease systemic resilience. The goal is to assess difficulties related to the detection of climate and early warning signals from monitoring data. We also explored ways to circumvent some of the obstacles identified. Exposure and sensitivity of mangrove and salt marsh species and ecosystems make them extremely vulnerable to environmental impacts and potential indicators of sea level and climate-driven environmental change. However, the interpretation of shifts in mangroves and salt marsh species and systemic attributes must be scrutinized considering local and setting-level energy signature changes; including disturbance regime and local stressors, since these vary widely on a regional scale. The potential for adaptation and survival in response to climate change depends, in addition to the inherent properties of species, on contextual processes at the local, landscape, and regional levels that support resilience. Regardless of stressor type, because of the convergence of social and ecological processes, coastal zones should be targeted for anticipatory action to reduce risks and to integrate these ecosystems into adaptation strategies. Management must be grounded on proactive mitigation and collaborative action based on long-term ecosystem-based studies and well-designed monitoring programs that can 1 provide real-time early warning and 2 close the gap between simple correlations that provide weak inferences and process-based approaches that can yield increasingly reliable attribution and improved levels of anticipation.

  8. Role of bentonite clays on cell growth.

    Science.gov (United States)

    Cervini-Silva, Javiera; Ramírez-Apan, María Teresa; Kaufhold, Stephan; Ufer, Kristian; Palacios, Eduardo; Montoya, Ascención

    2016-04-01

    Bentonites, naturally occurring clays, are produced industrially because of their adsorbent capacity but little is known about their effects on human health. This manuscript reports on the effect of bentonites on cell growth behaviour. Bentonites collected from India (Bent-India), Hungary (Bent-Hungary), Argentina (Bent-Argentina), and Indonesia (Bent-Indonesia) were studied. All four bentonites were screened in-vitro against two human cancer cell lines [U251 (central nervous system, glioblastoma) and SKLU-1 (lung adenocarcinoma)] supplied by the National Cancer Institute (USA). Bentonites induced growth inhibition in the presence of U251 cells, and growth increment in the presence of SKLU-1 cells, showing that interactions between bentonite and cell surfaces were highly specific. The proliferation response for U251 cells was explained because clay surfaces controlled the levels of metabolic growth components, thereby inhibiting the development of high-grade gliomas, particularly primary glioblastomas. On the other hand, the proliferation response for SKLU-1 was explained by an exacerbated growth favoured by swelling, and concomitant accumulation of solutes, and their hydration and transformation via clay-surface mediated reactions.

  9. Cyclic Shearing Deformation Behavior of Saturated Clays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform stress-controlled cyclic single-direction torsional shear tests and two-direction coupled shear tests under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effects of initial shear stress and stress reversal on the clay's strain-stress behavior are examined, and the behavior of pore water pressure is studied. The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests. When the initial shear stress is large and no stress reversal occurs, the predominant deformation behavior is characterized by an accumulative effect. When the initial shear stress is zero and symmetrical cyclic stress occurs, the predominant deformation behavior is characterized by a cyclic effect. The pore water pressure fluctuates around the confining pressure with the increase of cycle number. It seems that the fluctuating amplitude increases with the increase of the cyclic stress. But a buildup of pore water pressure does not occur. The deformations of clay samples under the complex initial and the cyclic coupled stress conditions include the normal deviatoric deformation and horizontal shear deformation, the average deformation and cyclic deformation. A general strain failure criterion taking into account these deformations is recommended and is proved more stable and suitable compared to the strain failure criteria currently used.

  10. Spectromicroscopy of Fe distributions in clay microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Grundl, T. [Univ. of Wisconsin, Milwaukee, WI (United States); Cerasari, S.; Garcia, A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  11. Calculation of the debris flow concentration based on clay content

    Institute of Scientific and Technical Information of China (English)

    CHEN Ningsheng; CUI Peng; LIU Zhonggang; WEI Fangqiang

    2003-01-01

    The debris flow clay content has very tremendous influence on its concentration (γC). It is reported that the concentration can be calculated by applying the relative polynomial based on the clay content. Here one polynomial model and one logarithm model to calculate the concentration based on the clay content for both the ordinary debris flow and viscous debris flow are obtained. The result derives from the statistics and analysis of the relationship between the debris flow concentrations and clay content in 45 debris flow sites located in the southwest of China. The models can be applied for the concentration calculation to those debris flows that are impossible to observe. The models are available to calculate the debris flow concentration, the principles of which are in the clay content affecting on the debris flow formation, movement and suspending particle diameter. The mechanism of the relationship of the clay content and concentration is clear and reliable. The debris flow is usually of micro-viscous when the clay content is low (<3%), by analyzing the developing tendency on the basics of the relationship between the clay content and debris flow concentration. Indeed, the less the clay content, the less the concentration for most debris flows. The debris flow tends to become the water rock flow or the hyperconcentrated flow with the clay content decrease. Through statistics it is apt to transform the soil into the viscous debris flow when the clay content of ranges is in 3%-18%. Its concentration increases with the increasing of the clay content when the clay content is between 5% and 10%. But the value decreases with the increasing of the clay content when the clay content is between 10% and 18%. It is apt to transform the soil into the mudflow, when the clay content exceeds 18%. The concentration of the mudflow usually decreases with the increase of the clay content, and this developing tendency reverses to that of the micro-viscous debris flow. There is

  12. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    Science.gov (United States)

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P Net N2 O fluxes differed significantly among marsh zones (P = 0.009), averaging 9.8 ± 5.4 μg N m(-2)  h(-1) , -2.2 ± 0.9 μg N m(-2)  h(-1) , and 0.67 ± 0.57 μg N m(-2)  h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise.

  13. Deriving spatial and temporal patterns of coastal marsh aggradation from hurricane storm surge marker beds

    Science.gov (United States)

    Hodge, Joshua; Williams, Harry

    2016-12-01

    This study uses storm surge sediment beds deposited by Hurricanes Audrey (1957), Carla (1961), Rita (2005) and Ike (2008) to investigate spatial and temporal changes in marsh sedimentation on the McFaddin National Wildlife Refuge in Southeastern Texas. Fourteen sediment cores were collected along a transect extending 1230 m inland from the Gulf coast. Storm-surge-deposited sediment beds were identified by texture, organic content, carbonate content, the presence of marine microfossils and 137Cs dating. The hurricane-derived sediment beds facilitate assessment of changes in marsh sedimentation from nearshore to inland locations and over decadal to annual timescales. Spatial variation along the transect reflects varying contributions from three prevailing sediment sources: flooding, overwash and organic sedimentation from marsh plants. Over about the last decade, hurricane overwash has been the predominant sediment source for nearshore locations because of large sediment inputs from Hurricanes Rita and Ike. Farther inland, hurricane inputs diminish and sedimentation is dominated by deposition from flood waters and a larger organic component. Temporal variations in sedimentation reflect hurricane activity, changes in marsh surface elevation and degree of compaction of marsh sediments, which is time-dependent. There was little to no marsh sedimentation in the period 2008-2014, firstly because no hurricanes impacted the study area and secondly because overwash sedimentation prior to 2008 had increased nearshore marsh surface elevations by up to 0.68 m, reducing subsequent inputs from flooding. Marsh sedimentation rates were relatively high in the period 2005-2008, averaging 2.13 cm/year and possibly reflecting sediment contributions from Hurricanes Humberto and Gustav. However, these marsh sediments are highly organic and largely uncompacted. Older, deeper marsh deposits formed between 1961 and 2005 are less organic-rich, more compacted and have an average annual

  14. Dynamics of Small-Scale Topographic Heterogeneity in European Sandy Salt Marshes

    Directory of Open Access Journals (Sweden)

    Kelly Elschot

    2016-03-01

    Full Text Available Heterogeneity can boost biodiversity, as well as increase the resilience of an ecosystem to changing environmental conditions; therefore, it is important to understand how topographic heterogeneity in ecosystems is formed. Sandy tidal marshes have a repetitive pattern of higher elevated hummocks surrounded by lower elevated depressions, representing topographic heterogeneity at the scale of a few square meters. The aims of this study were to determine when this topographic heterogeneity forms, how it is structured, and whether it persists during marsh development. The soil topography of marshes consists of coarse-grained sediment formed before marsh vegetation development, with an overlaying fine-grained sediment layer formed after initial marsh development. To gain insight into the formation of topographic heterogeneity, we studied the underlying soil topography of four European sandy marshes, where topographic heterogeneity at a scale of a few square meters was present. The differences in elevation between hummocks and depressions can either be caused by heterogeneity in the coarse-grained sediment or by heterogeneity in the top layer containing the fine-grained sediment. Our results showed that the largest percentage of elevational differences between hummocks and depressions could be attributed to heterogeneity in the underlying coarse-grained substratum. Therefore, we conclude that the patterns in all four marshes were primarily formed before marsh development, before fine-grained sediment was deposited on top of the coarse-grained sediment. However, a smaller percentage of the elevational difference between hummocks and depressions can also be explained by the presence of thicker fine-grained sediment layers on top of hummocks compared with depressions. This implies that marsh accretion rates were higher on hummocks compared with depressions. However, this result was limited to very early stages of marsh development, as marsh accretion

  15. Hydrochemical characteristics of salt marsh wetlands in western Songnen Plain

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In western Songnen Plain of China, the saline-alkaline degree of water bodies is high in salt marsh wetlands. Generally, pH is above 8.0, and the hydrochemical types belong to HCO32--Na+. Through analysis on the basic saline variables such as CO32-, HCO32-, Cl-, Ca2+, Mg2+, SO42-, Na+, and the derivative variables such as SAR, SDR, RSC, SSP, the relationships between different variables are found, and the discriminant equations are established to identify different saline-alkaline water bodies by using principal component analysis.

  16. Allometry data and equations for coastal marsh plants.

    Science.gov (United States)

    Lu, Meng; Caplan, Joshua S; Bakker, Jonathan D; Adam Langley, J; Mozdzer, Thomas J; Drake, Bert G; Patrick Megonigal, J

    2016-12-01

    Coastal marshes are highly valued for ecosystem services such as protecting inland habitats from storms, sequestering carbon, removing nutrients and other pollutants from surface water, and providing habitat for fish, shellfish, and birds. Because plants largely determine the structure and function of coastal marshes, quantifying plant biomass is essential for evaluating these ecosystem services, understanding the biogeochemical processes that regulate ecosystem function, and forecasting tidal wetland responses to accelerated sea level rise. Allometry is a convenient and efficient technique for nondestructive estimation of plant biomass, and it is commonly used in studies of carbon and nitrogen cycles, energy flows, and marsh surface elevation change. We present plant allometry data and models developed for three long-term experiments at the Smithsonian Global Change Research Wetland, a brackish marsh in the Rhode River subestuary of the Chesapeake Bay. The dataset contains 9,771 measurements of stem height, dry mass, and (in 9638 cases) stem width across 11 plant species. The vast majority of observations are for Schoenoplectus americanus (8430) and Phragmites australis (311), with fewer observations for other common species: Amaranthus cannabinus, Atriplex patula, Iva frutescens, Kosteletzkya virginica, Polygonum hydropiper, Solidago sempervirens, Spartina alterniflora, Spartina cynosuroides, and Typha angustifolia. Allometric relationships take the form of linear regressions of biomass (transformed using the Box-Cox procedure) on either stem height and width, or on stem height alone. Allometric relationships for Schoenoplectus americanus were not meaningfully altered by elevated CO2 , N enrichment, the community context, interannual variation in climate, or year, showing that a single equation can be used across a broad range of conditions for this species. Archived files include: (1) raw data used to derive allometric equations for each species, (2) reports and

  17. Pentacyclic triterpenoid ketones in peat from Gannan Marsh, China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Abundant terrigenous triterpenoid ketones and a series of hopanoid ketones were detected in a peat sample from the recent Gannan Marsh. The identifieations of pentacyclic triterpenoid ketones are discussed in detail. Based on the compositional features of pentacyclic triterpenoid ketones in the sample, it is proposed that terrigenous triterpenoid kentones originate directly from organisms or are diagenetic oxidation products of their alcohols, and hopanoid ketones are formed from hopanoids (e.g. hopanoid alcohols and hopenes) by chemical and biochemical processes. These data provide evidence for the applied studies of pentacyclic triterpenoid ketones as biomarker compounds.``

  18. Nutrient cycling in salt marshes: An ecosystem service to reduce eutrophication

    DEFF Research Database (Denmark)

    Lillebø, A. I.; Sousa, A. I.; Flindt, M. R.;

    2013-01-01

    aims to draw attention to the sequestration capacity of salt marshes for the excess of nutrients, and to evaluate the ecological services provided by salt marsh halophytes by regulating the biogeochemical cycles of nitrogen (N) and phosphorus (P). In this context, two case studies will be presented...... and discussed: By comparing young and mature marshes colonised by Saprtina maritima, we will evaluate their behaviour as sink or source of nutrients; By comparing two halophytes with distinct life cycles (Spartina maritima and Scirpus maritimus), we will evaluate species-specific N and P cycling...... and sequestration in salt marshes. This chapter will thus emphasise that salt marsh halophytes have a crucial role on nutrient cycling and sequestration, providing ecological services that contribute to maintain the ecosystem health. © 2012 Nova Science Publishers, Inc. All rights reserved....

  19. Palatability and chemical defense of Phragmites australis to the marsh periwinkle snail Littoraria irrorata.

    Science.gov (United States)

    Hendricks, Lindsey G; Mossop, Hannah E; Kicklighter, Cynthia E

    2011-08-01

    Coastal marsh habitats are impacted by many disturbances, including habitat destruction, pollution, and the introduction of invasive species. The common reed, Phragmites australis, has been particularly invasive in the mesohaline regions of the Chesapeake Bay, but few studies have investigated its role in trophic interactions with North American marsh consumers. The marsh periwinkle snail Littoraria irrorata is a common grazer in marshes and grazes on the native grass Spartina alterniflora. Whether this snail grazes on Phragmites has not been addressed. We found Spartina leaves to be tougher than those of Phragmites, but despite this, snails consumed significantly more Spartina than Phragmites. Subsequent experiments demonstrated that Phragmites is chemically deterrent to snails by an unknown, moderately polar, compound. Further studies are required to more fully understand the interactions between Phragmites, herbivores, and Spartina, and how they may impact marsh ecosystems.

  20. Soil Carbon Stocks in a Shifting Ecosystem; Climate Induced Migration of Mangroves into Salt Marsh

    Science.gov (United States)

    Simpson, L.; Osborne, T.; Feller, I. C.

    2015-12-01

    Across the globe, coastal wetland vegetation distributions are changing in response to climate change. The increase in global average surface temperature has already caused shifts in the structure and distribution of many ecological communities. In parts of the southeastern United States, increased winter temperatures have resulted in the poleward range expansion of mangroves at the expense of salt marsh habitat. Our work aims to document carbon storage in the salt marsh - mangrove ecotone and any potential changes in this reservoir that may ensue due to the shifting range of this habitat. Differences in SOM and C stocks along a latitudinal gradient on the east coast of Florida will be presented. The gradient studied spans 342 km and includes pure mangrove habitat, the salt marsh - mangrove ecotone, and pure salt marsh habitat.This latitudinal gradient gives us an exceptional opportunity to document and investigate ecosystem soil C modifications as mangroves transgress into salt marsh habitat due to climatic change.

  1. Surface Properties and Permeability of Poly(Vinylidene Fluoride)-Clays (PVDF/Clays) Composite Membranes

    Science.gov (United States)

    Pramono, E.; Ahdiat, M.; Simamora, A.; Pratiwi, W.; Radiman, C. L.; Wahyuningrum, D.

    2017-07-01

    Surface properties are important factors that determine the performance of ultrafiltration membranes. This study aimed to investigate the effects of clay addition on the surface properties and membrane permeability of PVDF (poly-vinylidene fluoride) membranes. Three types of clay with different particle size were used in this study, namely montmorillonite-MMT, bentonite-BNT and cloisite 15A-CLS. The PVDF-clay composite membranes were prepared by phase inversion method using PEG as additive. The hydrophobicity of membrane surface was characterized by contact angle. The membrane permeability was determined by dead- end ultrafiltration with a trans-membrane pressure of 2 bars. In contact angle measurement, water contact angle of composite membranes is higher than PVDF membrane. The addition of clays decreased water flux but increased of Dextran rejection. The PVDF-BNT composite membranes reach highest Dextran rejection value of about 93%. The type and particle size of clay affected the hydrophobicity of membrane surface and determined the resulting membrane structure as well as the membrane performance.

  2. Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

    2012-07-01

    Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

  3. HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

    Energy Technology Data Exchange (ETDEWEB)

    Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

    2009-07-01

    Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

  4. Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes

    Science.gov (United States)

    Rosencranz, Jordan A.; Ganju, Neil K.; Ambrose, Richard F.; Brosnahan, Sandra M.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; MacDonald, Glen M.; Takekawa, John Y.; Thorne, Karen M.

    2016-01-01

    Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.

  5. Taxonomic synopsis of Notiospathius Matthews & Marsh, 1973 (Hymenoptera: Braconidae) from Colombia.

    Science.gov (United States)

    Rodriguez-Jimenez, Andrea; Sarmiento, Carlos E

    2016-06-29

    Notiospathius Matthews & Marsh, 1973 is the second most diverse genus of Doryctinae in the Neotropical region, however, in Colombia only two species have been reported and no studies on the diversity of the genus have been conducted. We present a taxonomic synopsis of the genus from Colombia. Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA) allowed the taxonomic evaluation of morphometric characters used by other authors and those proposed in the present study to differentiate the species. Forty seven of 104 characters studied are useful to discriminate the species. Twenty three species are reported. The following new records for Colombia are: Notiospathius angustus Marsh, 2002; N. badius Marsh, 2002; N. bicolor Marsh, 2002; N. ninae Marsh, 2002; N. rugonotum Marsh, 2002; N. shawi Marsh, 2002; N. tinctipennis (Cameron, 1887) and N. venezuelae López-Estrada & Zaldívar-Riverón, 2012. The following 14 new species are described: N. alejandroi sp. nov., N. amazonensis sp. nov., N. carmenae sp. nov., N. cundinamarcensis sp. nov., N. farallonensis sp. nov., N. julianoi sp. nov., N. magdalenensis sp. nov., N. marshi sp. nov., N. payae sp. nov., N. putumayensis sp. nov., N. quimbayensis sp. nov., N. tayronensis sp. nov., N. utriae sp. nov., N. vallensis sp. nov. Notiospathius ugaldei Marsh, 2002 is the junior synonym of N. columbianus (Enderlein, 1912); Notiospathius mariachi Reséndiz-Flores, Nunes and Zaldívar-Riverón, 2014 is the junior synonym of N. carolinae (Marsh, 2002); and N. chinanteco Reséndiz-Flores, Nunes and Zaldívar-Riverón, 2014 is the junior synonym of N. rugonotum Marsh, 2002. A comprehensive taxonomic key with illustrations is presented.

  6. REE and (э)Nd of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

    Institute of Scientific and Technical Information of China (English)

    LIU Jihua; SHI Xuefa; CHEN Lirong; HUANG Yongyang; WANG Yinxi; CUI Yingchun; BU Wenrui

    2005-01-01

    Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and 143Nd/144Nd. Montmorillonite/illite ratio (M/I ratio), total REE contents ((REE), LREE/HREE ratio and cerium anomaly (бCe) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio >1, бCe (0.85, (REE (400 μg/g, LREE/HREE ratio (4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio <1, бCe=0.86 to 1.5, ΣREE=200 to 350 μg/g, LREE/HREE ratio (6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The 143Nd/144Nd ratios or (э)Nd values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to (э)Nd values. Terrigenous clay minerals of type I with the (э)Nd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type II with the (э)Nd values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with (э)Nd values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with (э)Nd values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.

  7. Effects of invasive cordgrass on presence of Marsh Grassbird in an area where it is not native.

    Science.gov (United States)

    Ma, Zhijun; Gan, Xiaojing; Choi, Chi-Yeung; Li, Bo

    2014-02-01

    The threatened Marsh Grassbird (Locustella pryeri) first appeared in the salt marsh in east China after the salt marsh was invaded by cordgrass (Spartina alterniflora), a non-native invasive species. To understand the dependence of non-native Marsh Grassbird on the non-native cordgrass, we quantified habitat use, food source, and reproductive success of the Marsh Grassbird at the Chongming Dongtan (CMDT) salt marsh. In the breeding season, we used point counts and radio-tracking to determine habitat use by Marsh Grassbirds. We analyzed basal food sources of the Marsh Grassbirds by comparing the δ(13) C isotope signatures of feather and fecal samples of birds with those of local plants. We monitored the nests through the breeding season and determined the breeding success of the Marsh Grassbirds at CMDT. Density of Marsh Grassbirds was higher where cordgrass occurred than in areas of native reed (Phragmites australis) monoculture. The breeding territory of the Marsh Grassbird was composed mainly of cordgrass stands, and nests were built exclusively against cordgrass stems. Cordgrass was the major primary producer at the base of the Marsh Grassbird food chain. Breeding success of the Marsh Grassbird at CMDT was similar to breeding success within its native range. Our results suggest non-native cordgrass provides essential habitat and food for breeding Marsh Grassbirds at CMDT and that the increase in Marsh Grassbird abundance may reflect the rapid spread of cordgrass in the coastal regions of east China. Our study provides an example of how a primary invader (i.e., cordgrass) can alter an ecosystem and thus facilitate colonization by a second non-native species. © 2013 Society for Conservation Biology.

  8. Polypropylene–clay composite prepared from Indian bentonite

    Indian Academy of Sciences (India)

    Madhuchhanda Sarkar; Kausik Dana; Sankar Ghatak; Amarnath Banerjee

    2008-02-01

    In the present work, a set of experimental polypropylene (PP) clay composites containing pristine bentonite clay of Indian origin has been prepared and then characterized. The polymer clay composites are processed by solution mixing of polypropylene with bentonite clay using a solvent xylene and high speed electric stirrer at a temperature around 130°C and then by compression molding at 170°C. The mechanical properties of PP–clay composites like tensile strength, hardness and impact resistance have been investigated. Microstructural studies were carried out using scanning electron microscope and transmission electron microscope and the thermal properties were studied using differential scanning calorimeter. Mechanical properties of the prepared composites showed highest reinforcing and toughening effects of the clay filler at a loading of only 5 mass % in PP matrix. Tensile strength was observed to be highest in case of 5 mass % of clay loading and it was more than 14% of that of the neat PP, while toughness increased by more than 80%. Bentonite clay–PP composite (5 mass %) also showed 60% increase in impact energy value. However, no significant change was observed in case of hardness and tensile modulus. Higher percentages of bentonite clay did not further improve the properties with respect to pristine polypropylene. The study of the microstructure of the prepared polymer layered silicate clay composites showed a mixed morphology with multiple stacks of clay layers and tactoids of different thicknesses.

  9. Role of clay as catalyst in Friedel–Craft alkylation

    Indian Academy of Sciences (India)

    Tanushree Choudhury; Nirendra M Misra

    2011-10-01

    Solid acids have become increasingly important for many liquid-phase industrial reactions these days. Montmorillonite clays (2:1 clay mineral) have been used as efficient solid acid catalysts for a number of organic and liquid phase reactions and offer several advantages over classic acids. Tailor made catalysts can be prepared from clays by suitably adjusting their acidity and surface area by acid activation. In the present work, preparation, characterization and performance of Pt (II) clays, Cu (II) clays, acid clay, and sol–gel hybrids of Cu (II) clays as solid catalysts in a test Friedel–Craft alkylation reaction of benzyl chloride with toluene using differential scanning calorimeter (DSC) are reported. Product formation has been analysed by FTIR spectroscopy. The main objective of this work is to show how clay as a solid catalyst affects reaction rates and activation energies. Acidity and dispersion of solid catalysts are twomain factors which govern a catalysis reaction. Kinetic parameter analysis and XRD studies confirm that acid Pt (II) clay and Pt (II) clay dispersed by natural dispersants aremore effective catalysts. In contrast to the reactions using AlCl3, the experimental conditions are non-polluting and the final work up does not require any aqueous treatment.

  10. Effective Removal of Heavy Metals from Wastewater Using Modified Clay.

    Science.gov (United States)

    Song, Mun-Seon; Vijayarangamuthu, K; Han, EunJi; Jeon, Ki-Joon

    2016-05-01

    We report an economical and eco-friendly way to remove the heavy metal pollutant using modified clay. The modification of clay was done by calcining the natural clay from Kyushu region in Japan. Further, the removal efficiency for various pH and contact time was evaluated. The morphology of the clays was studied using the scanning electron microscopy (SEM). The structural and chemical analyses of modified clay were done by using X-ray diffraction (XRD), Raman spectroscopy, and Energy dispersion analysis (EDAX) to understand the properties related to the removal of heavy metal pollutant. Further, we studied the absorption efficiency of clay for various pH and contacting time using Ni polluted water. The modified clays show better removal efficiency for all pH with different saturation time. The adsorption follows pseudo-second order kinetics and the adsorption capacity of modified clay is 1.5 times larger than that of natural clay. The increase in the adsorption efficiency of modified clay was correlated to the increase in hematite phase along with increase in surface area due to surface morphological changes.

  11. Adsorption of dyes using different types of clay: a review

    Science.gov (United States)

    Adeyemo, Aderonke Ajibola; Adeoye, Idowu Olatunbosun; Bello, Olugbenga Solomon

    2015-09-01

    Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.

  12. Adsorption of dyes using different types of clay: a review

    Science.gov (United States)

    Adeyemo, Aderonke Ajibola; Adeoye, Idowu Olatunbosun; Bello, Olugbenga Solomon

    2017-05-01

    Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.

  13. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    Science.gov (United States)

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-06-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner.

  14. German flooding of the Pontine Marshes in World War II.

    Science.gov (United States)

    Geissler, Erhard; Guillemin, Jeanne

    2010-03-01

    The German army's 1943 flooding of the Pontine Marshes south of Rome, which later caused a sharp rise in malaria cases among Italian civilians, has recently been described by historian Frank Snowden as a unique instance of biological warfare and bioterrorism in the European theater of war and, consequently, as a violation of the 1925 Geneva Protocol prohibiting chemical and biological warfare. We argue that archival documents fail to support this allegation, on several counts. As a matter of historical record, Hitler prohibited German biological weapons (BW) development and consistently adhered to the Geneva Protocol. Rather than biological warfare against civilians, the Wehrmacht used flooding, land mines, and the destruction of vital infrastructure to obstruct the Allied advance. To protect its own troops in the area, the German army sought to contain the increased mosquito breeding likely to be caused by the flooding. Italians returning to the Pontine Marshes after the German retreat in 1944 suffered malaria as a result of environmental destruction, which was banned by the 1899 and 1907 Hague Conventions and by subsequent treaties. In contrast, a state's violation of the Geneva Protocol, whether past or present, involves the use of germ weapons and, by inference, a state-level capability. Any allegation of such a serious violation demands credible evidence that meets high scientific and legal standards of proof.

  15. CO2 adsorption isotherm on clay minerals and the CO2 accessibility into the clay interlayer

    Science.gov (United States)

    Gensterblum, Yves; Bertier, Pieter; Busch, Andreas; Rother, Gernot; Krooß, Bernhard

    2013-04-01

    Large-scale CO2 storage in porous rock formations at 1-3 km depth is seen as a global warming mitigation strategy. In this process, CO2 is separated from the flue gas of coal or gas power plants, compressed, and pumped into porous subsurface reservoirs with overlying caprocks (seals). Good seals are mechanically and chemically stable caprocks with low porosity and permeability. They prevent leakage of buoyant CO2 from the reservoir. Caprocks are generally comprised of thick layers of shale, and thus mainly consist of clay minerals. These clays can be affected by CO2-induced processes, such as swelling or dissolution. The interactions of CO2 with clay minerals in shales are at present poorly understood. Sorption measurements in combination scattering techniques could provide fundamental insight into the mechanisms governing CO2-clay interaction. Volumetric sorption techniques have assessed the sorption of supercritical CO2 onto coal (Gensterblum et al., 2010; Gensterblum et al., 2009), porous silica (Rother et al., 2012a) and clays as a means of exploring the potential of large-scale storage of anthropogenic CO2 in geological reservoirs (Busch et al., 2008). On different clay minerals and shales, positive values of excess sorption were measured at gas pressures up to 6 MPa, where the interfacial fluid is assumed to be denser than the bulk fluid. However, zero and negative values were obtained at higher densities, which suggests the adsorbed fluid becomes equal to and eventually less dense than the corresponding bulk fluid, or that the clay minerals expand on CO2 charging. Using a combination of neutron diffraction and excess sorption measurements, we recently deduced the interlayer density of scCO2 in Na-montmorillonite clay in its single-layer hydration state (Rother et al., 2012b), and confirmed its low density, as well as the expansion of the basal spacings. We performed neutron diffraction experiments at the FRMII diffractometer on smectite, kaolinite and illite

  16. Carbon Sequestration in Created and Natural Tidal Marshes of the Florida Panhandle

    Science.gov (United States)

    Rainville, K. M.; Davis, J.; Currin, C.

    2016-12-01

    Salt marshes are widely understood to be efficient at storing carbon in sediments (aka blue carbon) through the production of roots and rhizomes. These marshes are also able to trap sediments from incoming tides, slowly increasing their elevation over time. These qualities have led to a great deal of interest in creation and preservation of salt marshes for offsetting changes associated with anthropogenic CO2 emissions. Determinations of the value of marshes in terms of CO2 offsets requires detailed knowledge of sediment carbon storage rates, but to date, measured rates of carbon storage in created salt marsh sediments are sparse. We measured carbon storage in natural and created marshes along the Northern Gulf Coast of Florida. The created marshes were in `living shoreline' projects and ranged in age from 8 to 28 years. Dominant plant cover of the marshes included Spartina alterniflora and Juncus spp. At all sites, sediment cores (22-75 cm in depth) were collected, extruded in 5 cm increments, and carbon content was determined by elemental analysis. Measured C storage rates in the created marshes ranged from 60 to 130 g C m-2 yr-1 and decreased with marsh age. A decrease in storage rates over time is evidence of continued decomposition of stored carbon as sediments age, an important factor to consider when estimating the value of a given marsh for CO2 offsets. The rates measured in Florida are well below previously published average values ( 200 g m-2 yr-1) and also below the default value allowed for carbon crediting through the verified carbon standard (146 g m-2 yr), but similar to those measured in created marshes in North Carolina. In addition, factors such as dominant plant type, water inundation, temperature, latitude, biological belowground activity and biomass values can impact carbon storage rates of marshes among geographically distinct regions. This makes it especially important to determine carbon storage rates on a local scale, and not following a

  17. Habitat Evaluation Procedures (HEP) Report : Ladd Marsh, 2001 Technical Report.

    Energy Technology Data Exchange (ETDEWEB)

    Oregon Department of Fish and Wildlife

    2001-10-01

    ]) have been working together since 1991 to coordinate the planning, selection, and implementation of BPA-funded wildlife mitigation projects. In 1997, the Oregon wildlife managers developed a programmatic project for mitigation planning and implementation within Oregon. The Ladd Marsh Wildlife Area Additions project is one of many habitat acquisition and restoration projects proposed under the Oregon wildlife managers programmatic project that have been approved and recommended for funding by the NWPPC. The Ladd Marsh Wildlife Area Additions mitigation project will protect and restore wetland, riparian and other habitats on newly acquired parcels at ODFW's Ladd Marsh Wildlife Area (LMWA). Wildlife habitat values resulting from the acquisition and enhancement of Ladd Marsh Wildlife Area lands will contribute towards mitigating for habitat lost as a result of the development and operation of the Columbia Basin hydropower system. This report summarizes the HEP survey conducted in June 2001 to document the baseline habitat values on four parcels recently added to the Ladd Marsh Wildlife Area: the 309.66-acre Wallender property, the 375.54-acre Simonis property, the 161.07-acre Conley Lake property, and the 74.55-acre Becker property. The 2001 HEP Team was comprised of the following members and agencies: Susan Barnes (ODFW), Allen Childs (CTUIR), Tracy Hames (Yakama Indian Nation), Dave Larson (ODFW), Cathy Nowak (Cat Tracks Wildlife Consulting), and Ken Rutherford (ODFW). Results of the HEP will be used to (1) determine the pre-restoration habitat values of the project sites, (2) the number of Habitat Units to be credited to BPA for protection of habitats within the project area, (3) determine the enhancement potential of the sites, and (4) develop a habitat management plan for the area.

  18. Fighting the Barbarians in the Macedonian Marshes in 391

    Directory of Open Access Journals (Sweden)

    Alenka Cedilnik

    2010-12-01

    Full Text Available Chapters 48 and 49 of Book 4 in Zosimus’ New History present the Emperor Theodosius’ routing of the group of barbarians who had rebelled in 388, during Theodosius’ preparations for war against the usurper Magnus Maximus, and preyed on the population of Macedonia and Thessaly from their hiding-places in the Macedonian marshes until 391. According to Zosimus, they were defeated by Theodosius in the summer of 391 as he was returning from the West to Constantinople. The content of Zosimus’ report has raised the doubts of many modern historians, but despite the prevailing mistrust of his description of the battle, the course of events has never been treated in greater detail. The chief aim of the present paper is thus to examine the battle more closely, in connection with other known sources, and to weigh the extent to which Zosimus’ account may nevertheless reflect the actual events. Foregrounded are, above all, two basic questions: (1 Did Theodosius on his way back from the West in fact engage in a battle with those same barbarians who had been hiding in the Macedonian marshes since 388?; and (2 Does Zosimus’ report refer to a single event (i.e. merely to Theodosius’ skirmishes with the barbarians in the Macedonian marshes, or did Zosimus unwittingly confuse the information on two different battles (the battle in the Macedonian marshes and the later one at the Hebrus? When the information provided by Zosimus in the abovementioned passages is complemented by the information from Pacatus’ 389 panegyric to the Emperor Theodosius, by the reports on the uprising of the Thessalonians in the spring of 390, and by the edict permitting self-defence against robbers, which was addressed to the inhabitants of all provinces on July 1, 391, the circumstances and course of the battle might be interpreted as follows: In 388, during Theodosius’ preparations for war against Magnus Maximus, a group of the barbarians who had joined Theodosius

  19. Interactions between barrier islands and backbarrier marshes affect island system response to sea level rise: Insights from a coupled model

    Science.gov (United States)

    Walters, David; Moore, Laura J.; Duran Vinent, Orencio; Fagherazzi, Sergio; Mariotti, Giulio

    2014-09-01

    Interactions between backbarrier marshes and barrier islands will likely play an important role in determining how low-lying coastal systems respond to sea level rise and changes in storminess in the future. To assess the role of couplings between marshes and barrier islands under changing conditions, we develop and apply a coupled barrier island-marsh model (GEOMBEST+) to assess the impact of overwash deposition on backbarrier marsh morphology and of marsh morphology on rates of island migration. Our model results suggest that backbarrier marsh width is in a constant state of change until either the backbarrier basin becomes completely filled or backbarrier marsh deposits have completely eroded away. Results also suggest that overwash deposition is an important source of sediment, which allows existing narrow marshes to be maintained in a long-lasting alternate state (~500 m wide in the Virginia Barrier Islands) within a range of conditions under which they would otherwise disappear. The existence of a narrow marsh state is supported by observations of backbarrier marshes along the eastern shore of Virginia. Additional results suggest that marshes reduce accommodation in the backbarrier bay, which, in turn, decreases island migration rate. As climate change results in sea level rise, and the increased potential for intense hurricanes resulting in overwash, it is likely that these couplings will become increasingly important in determining future system behavior.

  20. Responses of salt marsh ecosystems to mosquito control management practices along the Atlantic Coast (U.S.A.)

    Science.gov (United States)

    James-Pirri, Mary-Jane; Erwin, R. Michael; Prosser, Diann J.; Taylor, Janith D.

    2012-01-01

    Open marsh water management (OMWM) of salt marshes modifies grid-ditched marshes by creating permanent ponds and radial ditches in the high marsh that reduce mosquito production and enhance fish predation on mosquitoes. It is preferable to using pesticides to control salt marsh mosquito production and is commonly presented as a restoration or habitat enhancement tool for grid-ditched salt marshes. Monitoring of nekton, vegetation, groundwater level, soil salinity, and bird communities before and after OMWM at 11 (six treatment and five reference sites) Atlantic Coast (U.S.A.) salt marshes revealed high variability within and among differing OMWM techniques (ditch-plugging, reengineering of sill ditches, and the creation of ponds and radial ditches). At three marshes, the dominant nekton shifted from fish (primarily Fundulidae species) to shrimp (Palaemonidae species) after manipulations and shrimp density increased at other treatment sites. Vegetation changed at only two sites, one with construction equipment impacts (not desired) and one with a decrease in woody vegetation along existing ditches (desired). One marsh had lower groundwater level and soil salinity, and bird use, although variable, was often unrelated to OMWM manipulations. The potential effects of OMWM manipulations on non-target salt marsh resources need to be carefully considered by resource planners when managing marshes for mosquito control.