Science.gov

Sample records for agency usepa mid-atlantic

  1. COMPARISON OF USEPA FIELD SAMPLING METHODS FOR BENTHIC MACROINVERTEBRATE STUDIES

    EPA Science Inventory

    Two U.S. Environmental Protection Agency (USEPA) macroinvertebrate sampling protocols were compared in the Mid-Atlantic Highlands region. The Environmental Monitoring and Assessment Program (EMAP) wadeable streams protocol results in a single composite sample from nine transects...

  2. COMPARING STRENGTHS OF GEOGRAPHIC AND NONGEOGRAPHIC CLASSIFICATIONS OF STREAM BENTHIC MACROINVERTEBRATES IN THE MID-ATLANTIC HIGHLANDS, USA

    EPA Science Inventory

    The US Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program (EMAP) sampled - 500 wadeable streams in the Mid-Atlantic Highlands region of the US during the late spring of 1993 to 1995 for a variety of physical, chemical, and biological indicat...

  3. COMPARING THE STRENGTHS OF GEOGRAPHIC AND NON-GEOGRAPHIC CLASSIFICATIONS OF STREAM BENTHIC MACROINVERTEBRATES IN THE MID-ATLANTIC HIGHLANDS, USA

    EPA Science Inventory

    The US Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program (EMAP) sampled approximately 500 wadeable streams in the Mid-Atlantic Highlands region of the US during the late spring of 1993 to 1995 for a variety of physical, chemical and biologi...

  4. DEVELOPMENT AND EVALUATION OF A MACROINVERTEBRATE BIOTIC INTEGRITY INDEX (MBII) FOR REGIONALLY ASSESSING MID-ATLANTIC HIGHLANDS STREAMS

    EPA Science Inventory

    The multimetric Macroinvertebrate Biotic Integrity Index (MBII) was developed from data collected at 574 wadeable stream reaches in the Mid-Atlantic Highlands region (MAHR) by the USEPA's Environmental Monitoring and Assessment Program (EMAP). Over 100 candidate metrics were eval...

  5. 77 FR 51968 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-28

    ... National Oceanic and Atmospheric Administration RIN 0648-XC188 Mid-Atlantic Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The Mid-Atlantic Fishery...

  6. 77 FR 65363 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... National Oceanic and Atmospheric Administration RIN 0648-XC298 Mid-Atlantic Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The Mid-Atlantic Fishery...

  7. THE MID-ATLANTIC INTEGRATED ASSESSMENT MAIA - ESTUARIES 1997-1998 SUMMARY REPORT

    EPA Science Inventory

    During the summers of 1997-98, a consortium of federal and state environmental agencies conducted the Mid-Atlantic Integrated Assessment (MAIA) program to characterize the environmental condition of the four major estuaries in the the mid-Atlantic region of the United States. The...

  8. 77 FR 76473 - Mid-Atlantic Fishery Management Council; Public Hearings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ... the hearing. January 15, 2013: 7-9 p.m.; Clarion Resort Fontainebleau Hotel, 10100 Coastal Highway... 0648-XC416 Mid-Atlantic Fishery Management Council; Public Hearings AGENCY: National Marine Fisheries... hearings. SUMMARY: The Mid-Atlantic Fishery Management Council (Council) will hold public hearings...

  9. INTEGRATION OF COASTAL ENVIRONMENTAL INDICATORS FOR THE U.S. MID-ATLANTIC REGION

    EPA Science Inventory

    The Mid-Atlantic Integrated Assessment (MAlA) Project began in 1994 as a partnership between USEPA's Region III Office and Office of Research and Development. This multi-year initiative was envisioned to: (1) improve the quality of environmental science and promote the use of sou...

  10. USEPA EPIC IMPERVIOUS SURFACE RESEARCH IN THE MID-ATLANTIC

    EPA Science Inventory

    Anthropogenic impervious surfaces have an important relationship with non-point source pollution (NPS) in urban watersheds. These human-created surfaces include such features as roads, parking lots, rooftops, sidewalks, and driveways. The amount of impervious surface area in a ...

  11. 78 FR 65973 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-04

    ... National Oceanic and Atmospheric Administration RIN 0648-XC955 Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and... L. Thompson, Acting Deputy Director, Office of Sustainable Fisheries, National Marine...

  12. Evaluation of stream chemistry and watershed characteristics in the mid-atlantic coastal plain

    SciTech Connect

    Janicki, A.; Morgan, M.; Lynch, J.

    1995-12-31

    The purpose of this study was to apply the stream classification model developed from Maryland Synoptic Stream Chemistry Study data base to assess the relative importance of acidic deposition and other anthropogenic disturbances on acidity in Mid-Atlantic Coastal Plain streams. Data pertaining to Mid-Atlantic Coastal Plain watershed geology, soils, land use type, and stream chemistry were obtained from USEPA National Stream Survey, USGS and County Soil Conservation Services from New Jersey to North Carolina. These data were used in a regression analysis to establish the relative importance of ions determining stream water acidity. The study results support the conclusion that acidic deposition has substantially altered the acid base chemistry of Mid-Atlantic Coastal Plain Streams.

  13. MID-ATLANTIC LANDCOVER CHANGE DATA BROWSER

    EPA Science Inventory

    The Mid-Atlantic region is comprised of southern New York, southern and western New Jersey, Pennsylvania, West Virginia, Maryland, Virginia, northeastern North Carolina, Delaware, and Washington, DC. It is an ecosystem rich in streams, wetlands, forests, estuaries, breeding birds...

  14. MACROINVERTEBRATE METRICS AND WATER CHEMISTRY RELATIONSHIPS FROM NON-WADEABLE STREAMS OF THE MID-ATLANTIC INTEGRITY ASSESSMENT

    EPA Science Inventory

    Macroinvertebrates were collected from non-wadeable streams during the summer of 1997 and 1998 for the USEPA Environmental Monitoring and Assessent Program (EMAP) Mid-Atlantic Integrated Assessment (MAIA). In this study we examined macroinvertebrate metrics to identify those whi...

  15. CONDITION OF THE MID ATLANTIC ESTUARIES: PRODUCTION OF A STATE OF THE ENVIRONMENT REPORT

    EPA Science Inventory

    The U.S. Environmental Protection Agency has released a report entitled Condition of the Mid-Atlantic Estuaries. That report summarizes the findings of several studies conducted by federal and state agencies and academic institutions in Chesapeake Bay, Delaware Estuary, and the c...

  16. Mid-Atlantic Regional Wind Energy Institute

    SciTech Connect

    Courtney Lane

    2011-12-20

    As the Department of Energy stated in its 20% Wind Energy by 2030 report, there will need to be enhanced outreach efforts on a national, state, regional, and local level to communicate wind development opportunities, benefits and challenges to a diverse set of stakeholders. To help address this need, PennFuture was awarded funding to create the Mid-Atlantic Regional Wind Energy Institute to provide general education and outreach on wind energy development across Maryland, Virginia, Delaware, Pennsylvania and West Virginia. Over the course of the two-year grant period, PennFuture used its expertise on wind energy policy and development in Pennsylvania and expanded it to other states in the Mid-Atlantic region. PennFuture accomplished this through reaching out and establishing connections with policy makers, local environmental groups, health and economic development organizations, and educational institutions and wind energy developers throughout the Mid-Atlantic region. PennFuture conducted two regional wind educational forums that brought together wind industry representatives and public interest organizations from across the region to discuss and address wind development in the Mid-Atlantic region. PennFuture developed the agenda and speakers in collaboration with experts on the ground in each state to help determine the critical issue to wind energy in each location. The sessions focused on topics ranging from the basics of wind development; model ordinance and tax issues; anti-wind arguments and counter points; wildlife issues and coalition building. In addition to in-person events, PennFuture held three webinars on (1) Generating Jobs with Wind Energy; (2) Reviving American Manufacturing with Wind Power; and (3) Wind and Transmission. PennFuture also created a web page for the institute (http://www.midatlanticwind.org) that contains an online database of fact sheets, research reports, sample advocacy letters, top anti-wind claims and information on how to

  17. INNOVATIVE ENVIRONMENTAL EDUCATION CONTRIBUTES TO IMPROVED MANAGEMENT PRACTICES IN THE MID-ATLANTIC

    EPA Science Inventory

    EPA and other federal agencies have conducted considerable research in the Mid-Atlantic region. EPA's Science to Achieve Results (STAR) program funds academic scientists and engineers to conduct complementary research. Some of the research results are being used, but there is a...

  18. DEVELOPMENT OF AN INDEX OF BIOTIC INTEGRITY FOR THE MID-ATLANTIC HIGHLANDS REGION

    EPA Science Inventory

    From 1993 to 1996, fish assemblage data were collected from 309 wadeable streams in the U.S. Mid-Atlantic Highlands region as part of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program. Stream sites were selected with a probabilistic sampl...

  19. MID-ATLANTIC COASTAL STREAMS STUDY: STATISTICAL DESIGN FOR REGIONAL ASSESSMENT AND LANDSCAPE MODEL DEVELOPMENT

    EPA Science Inventory

    A network of stream-sampling sites was developed for the Mid-Atlantic Coastal Plain (New Jersey through North Carolina) a collaborative study between the U.S. Environmental Protection Agency and the U.S. Geological Survey. A stratified random sampling with unequal weighting was u...

  20. MID-ATLANTIC COASTAL STREAMS STUDY: STATISTICAL DESIGN FOR REGIONAL ASSESSMENT AND LANDSCAPE MODEL DEVELOPMENT

    EPA Science Inventory

    A network of stream-sampling sites was developed for the Mid-Atlantic Coastal Plain (New Jersey through North Carolina) as part of collaborative research between the U.S. Environmental Protection Agency and the U.S. Geological Survey. A stratified random sampling with unequal wei...

  1. 78 FR 26616 - Mid-Atlantic Fishery Management Council (Council); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-07

    ... (Council); Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and... Hotel, 29 Perry St, Cape May, NJ 08204; telephone: (888) 944-1816. Council address: Mid-Atlantic Fishery..., 800 N. State Street, Suite 201, Dover, DE 19901; telephone: (302) 526-5255. SUPPLEMENTARY...

  2. Forecasting fish biomasses, densities, productions, and bioaccumulation potentials of Mid-Atlantic wadeable streams

    EPA Science Inventory

    Regional fishery conditions of Mid-Atlantic wadeable streams in the eastern United States are estimated using the BASS bioaccumulation and fish community model and data collected by the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP)....

  3. EVALUATION OF MACROINVERTEBRATE TRENDS IN STREAMS VULNERABLE TO ACID DEPOSITION IN THE MID-ATLANTIC HIGHLANDS REGION OF THE U.S.A.

    EPA Science Inventory

    Benthic macroinvertebrate and water chemistry samples were collected from wadeable stream sites in the Mid-Atlantic Highlands region of the U.S. during 1993-1995 and 2001 in support of USEPA's TIME (Temporally Integrated Monitoring of Ecosystems) Progam. This study was designed ...

  4. Mid-Atlantic elasmobranchs: Suitable metal scouts?

    PubMed

    Torres, Paulo; da Cunha, Regina Tristão; Dos Santos Rodrigues, Armindo

    2017-02-05

    Heavy metals are a hazard to marine fauna and human health. In this study we assess stable isotopes and metal content in Prionace glauca and Isurus oxyrinchus and analyse these results within and among other species and across regions and geographical areas. Also, we evaluate their suitability, together with Raja clavata and Galeorhinus galeus, as Mid-Atlantic bioindicators. Prionace glauca and I. oxyrinchus shared the same trophic level in a pelagic food web and did not present significant differences between genders or metals, except for As. Arsenic and Hg accumulated while Cd and Pb were not detected. One I. oxyrinchus presented Hg values above regulatory limits. A high Hg exposure was associated with I. oxyrinchus since its maximum weekly intake was exceeded. Elasmobranchs can be used as metal sentinels, each presenting different key features which defines a good marine bioindicator, allowing long-term monitoring at different temporal and spatial scales.

  5. ECOLOGICAL CONDITION OF THE U.S. MID-ATLANTIC ESTUARIES: THE MID-ATLANTIC INTEGRATED ASSESSMENT (MAIA)

    EPA Science Inventory

    The Mid-Atlantic Integrated Assessment (MAIA-Estuaries) evaluated ecological conditions in US Mid-Atlantic estuaries during the summers of 1997 and 1998. Over 800 probability-based stations were monitored in four main estuarine systems?Chesapeake Bay, the Delaware Estuary, Maryla...

  6. Mid-Atlantic Wind - Overcoming the Challenges

    SciTech Connect

    Daniel F. Ancona III; Kathryn E. George; Richard P. Bowers; Dr. Lynn Sparling; Bruce Buckheit; Daniel LoBue

    2012-05-31

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  7. Mid-Atlantic Wind - Overcoming the Challenges

    SciTech Connect

    Daniel F. Ancona III; Kathryn E. George; Lynn Sparling; Bruce C. Buckheit; Daniel LoBue; and Richard P. Bowers

    2012-06-29

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  8. Pesticides in surface water of the Mid-Atlantic region

    USGS Publications Warehouse

    Ferrari, Matthew J.; Ator, Scott W.; Blomquist, Joel D.; Dysart, Joel E.

    1997-01-01

    Water-quality data from 463 surface-water sites were compiled and analyzed to document the occurrence and distribution of pesticides in surface water of the Mid-Atlantic region as part of the Mid-Atlantic Integrated Assessment program of the U.S. Environmental Protection Agency. Those data collected by the U.S. Geological Survey from October 1973 through March 1997 were used in the analyses. Data are available for a large part of the Mid-Atlantic region, but large spatial gaps in the data do exist. USGS data bases contained analyses of surface-water samples for 127 pesticide compounds, including 12 degradates, but only 16 of the compounds were commonly detected. Atrazine, metolachlor, simazine, prometon, alachlor, tebuthiuron, cyanazine, diazinon, carbaryl, chlorpyrifos, pendimethalin, 2,4-D, dieldrin, DCPA, metribuzin, and desethylatrazine (an atrazine degradate) were detected in more than 100 of the samples analyzed. At least one pesticide was detected in about 75 percent of the samples collected and at more than 90 percent of the sites sampled. Concentrations greater than the Federal Maximum Contaminant Level (MCL) for drinking water of 3 micrograms per liter (ug/L) for atrazine were found in 67 of 2,076 samples analyzed; concentrations greater than the MCL of 2ug/L for alachlor were found in 13 of 1,693 samples analyzed, and concentrations greater than the MCL of 4 ug/L for simazine were found in 17 of 1,995 samples analyzed. Concentrations of four pesticides were greater than Federal Health Advisory levels for drinking water, and concentrations of nine pesticides were greater than Federal Ambient Water-Quality Criteria for the Protection of Aquatic Organisms. Streams draining basins with different land uses tend to have different pesticide detection frequencies and median concentrations. Median concentrations of herbicides tend to be highest in streams draining basins in which the major land use is agriculture, whereas median concentrations of insecticides

  9. 77 FR 65380 - 2012 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... AGENCY 2012 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast... Environmental Protection Agency is announcing the joint 2012 Fall Meeting of the Ozone Transport Commission (OTC... regarding reducing ground- level ozone precursors and matters relative to Regional Haze and...

  10. 78 FR 54644 - 2013 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-05

    ... AGENCY 2013 Fall Joint Meeting of the Ozone Transport Commission and the Mid-Atlantic Northeast... United States Environmental Protection Agency is announcing the joint 2013 Fall Meeting ] of the Ozone... will include topics regarding reducing ground-level ozone precursors and matters relative to...

  11. MAIA PROJECT SUMMARY: CONDITION OF THE MID-ATLANTIC ESTUARIES

    EPA Science Inventory

    The Mid-Atlantic Integrated Assessment (MAIA) is an interagency, multi disciplinary research, monitoring and assessment program to develop high-quality scientific information on the region's natural resources: current condition, stresssors, trends, and vulnerabilities. MAIA resul...

  12. BIOLOGICAL INTEGRITY IN MID-ATLANTIC COASTAL PLAINS HEADWATER STREAMS

    EPA Science Inventory

    The objective of this study was to assess the applicability of landscape metrics, in conjunction with stream water quality to estimate the biological integrity of headwater streams in the Mid-Atlantic Coastal Plains using multivariate techniques.

  13. Satellite Movie Sees Major Winter Storm Nearing Mid-Atlantic

    NASA Video Gallery

    This animation NOAA's GOES-East satellite imagery from Jan. 20 to 22 shows the movement of the system that is expected to bring a powerful winter storm to the U.S. Mid-Atlantic region. Credit: NASA...

  14. 75 FR 22623 - Outer Continental Shelf (OCS) Mid-Atlantic Proposed Oil and Gas Lease Sale 220 and Geological and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-29

    ... Minerals Management Service Outer Continental Shelf (OCS) Mid-Atlantic Proposed Oil and Gas Lease Sale 220 and Geological and Geophysical Exploration (G&G) on the Mid- and South Atlantic OCS AGENCY: Minerals... Environment (MS 5410), Minerals Management Service, Gulf of Mexico OCS Region, 1201 Elmwood Park...

  15. 75 FR 25291 - Outer Continental Shelf (OCS) Mid-Atlantic Proposed Oil and Gas Lease Sale 220

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE INTERIOR Minerals Management Service Outer Continental Shelf (OCS) Mid-Atlantic Proposed Oil and Gas Lease Sale 220 AGENCY: Minerals Management Service (MMS), Interior. ACTION: Notice of indefinite postponement of...

  16. Comparing strengths of geographic and nongeographic classifications of stream benthic macroinvertebrates in the Mid-Atlantic Highlands, USA

    USGS Publications Warehouse

    Waite, I.R.; Herlihy, A.T.; Larsen, D.P.; Klemm, D.J.

    2000-01-01

    The US Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program (EMAP) sampled ~500 wadeable streams in the Mid-Atlantic Highlands region of the US during the late spring of 1993 to 1995 for a variety of physical, chemical, and biological indicators of environmental condition. Eighty-eight sites that were minimally affected by human activities were chosen to determine the extent to which geographic and stream-based classifications accounted for variation in the composition of riffle macroinvertebrate assemblages. Bray-Curtis similarities among sites were calculated from the relative abundance of macroinvertebrates to assess the strength of classifications based on geography (ecoregions and catchments), habitat (slope and stream order), and water chemistry (conductivity). For comparison, a taxonomic classification (two-way indicator species analysis, TWINSPAN) and a gradient analysis (correspondence analysis, CA) were performed on the macroinvertebrate data. To assess the effect of taxonomic resolution, all analyses were completed at the family level and to lowest practical taxon. The large overall variation within and among ecoregions resulted in a low average classification strength (CS) of ecoregions, although some ecoregions had high CS. Stream order had the highest CS of the habitat and water chemistry classifications. Ecoregion CS increased, however, when stream sites were 1(st) stratified by stream order (ecoregions nested within stream order). Nested ecoregion CS did not increase within 1(st)-order streams, yet increased within 2(nd)- and 3(rd)-order streams. CA ordinations and TWINSPAN classification showed a clear gradient of streams along stream size (order), with a clear separation of 1(st)- and 3(rd)-order streams based on macroinvertebrate composition. The ordinations did not, however, show a distinct clustering of sites on the basis of ecoregions. Overall, the lowest practical taxon level of identification resulted in

  17. A Case Study of a Mid-Atlantic Coastal Front.

    DTIC Science & Technology

    1985-01-01

    AuIHOtf.J 8 CONTNACY ON GRANT NUWMELN(e) James T. Kroll 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM I i Lt. NT PRO)JCT. TASK [ AREA • W004K UNIT...A 1473 iTioN of I NOV b5 IS OUOLIE TE UNCLASS SLU A I 104 PA 𔃻: 1 ................................ ’,**.* Li 0 ABSTRACT KROLL, JAMES T. A Case...Study of a Mid-Atlantic Coastal FLont.(Under the direction of DAVID BARBER and GERALD WATSON ). N’A unique case of mid-Atlantic coastal fvontoqenesis on

  18. 77 FR 70149 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-23

    ... National Oceanic and Atmospheric Administration Mid-Atlantic Fishery Management Council (MAFMC); Public... (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The Mid-Atlantic Fishery Management Council (Council) and its Visioning and Strategic Planning ] Working Group will hold public...

  19. 77 FR 47820 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-10

    ... INFORMATION CONTACT: Christopher M. Moore Ph.D., Executive Director, Mid-Atlantic Fishery Management Council... to M. Jan Saunders at the Mid-Atlantic Council Office, (302) 526-5251, at least 5 days prior to...

  20. 78 FR 6072 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-29

    ...: Christopher M. Moore Ph.D., Executive Director, Mid-Atlantic Fishery Management Council, 800 N. State Street... to M. Jan Saunders at the Mid-Atlantic Council Office, (302) 526-5251, at least 5 days prior to...

  1. TRICARE Mid-Atlantic Region Business Planning Initiatives

    DTIC Science & Technology

    1999-06-01

    This paper discusses the business planning processes and the development of a business plan. A business plan reflects the ultimate goal of an...provides valuable information about business operations. An assessment of business planning initiatives within the TRICARE Mid-Atlantic Region is provided

  2. Mid-Atlantic Directory to Resources for Asian Studies.

    ERIC Educational Resources Information Center

    Crouch, Archie R., Ed.; Shulman, Frank Joseph, Ed.

    This directory of print and human resources in the Mid-Atlantic states provides secondary and college teachers and students with information and assistance in the area of Asian studies. The directory is also a unique resource for leaders responsible for the advancement of understanding between American communities and the peoples of Asia, and a…

  3. INTERACTIVE HABITAT MODELS FOR MID-ATLANTIC HIGHLAND STREAM FISHES

    EPA Science Inventory

    In most wadeable streams of the Mid-Atlantic Highland region of the eastern United States, habitat alteration resulting from development in the watershed is the primary stressor for fish. Models that predict the presence of stream fish species based on habitat characteristics ca...

  4. BIOLOGICAL INTEGRITY IN MID-ATLANTIC COASTAL PLAINS HEADWATER STREAMS

    EPA Science Inventory

    The objective of this study was to assess the applicability of using landscape variables in conjunction with water quality and benthic data to efficiently estimate stream condition of select headwater streams in the Mid-Atlantic Coastal Plains. Eighty-two streams with riffle sit...

  5. Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    SciTech Connect

    Saracino-Brown, Jocelyn; Smith, Courtney; Gilman, Patrick

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. The workshop was planned by Federal agency, academic, and private partners to promote collaboration between ongoing offshore ecological survey efforts, and to promote the collaborative development of complementary predictive models and compatible databases. The meeting primarily focused on efforts to establish and predict marine mammal, seabird, and sea turtle abundance, density, and distributions extending from the shoreline to the edge of the Exclusive Economic Zone between Nantucket Sound, Massachusetts and Cape Hatteras, North Carolina.

  6. 75 FR 51441 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-20

    ... National Oceanic and Atmospheric Administration RIN 0648-XY32 Mid-Atlantic Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meeting. SUMMARY: The Mid-Atlantic Fishery Management... (telephone: 410-859-3300). Council address: Mid-Atlantic Fishery Management Council, 800 N. State...

  7. 50 CFR 229.34 - Harbor Porpoise Take Reduction Plan Regulations-Mid-Atlantic.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Regulations-Mid-Atlantic. 229.34 Section 229.34 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE... Emergency Regulations § 229.34 Harbor Porpoise Take Reduction Plan Regulations—Mid-Atlantic. (a)(1) Regulated waters. The regulations in this section apply to all waters in the Mid-Atlantic bounded on...

  8. 50 CFR 229.34 - Harbor Porpoise Take Reduction Plan Regulations-Mid-Atlantic.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Regulations-Mid-Atlantic. 229.34 Section 229.34 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE... Emergency Regulations § 229.34 Harbor Porpoise Take Reduction Plan Regulations—Mid-Atlantic. (a)(1) Regulated waters. The regulations in this section apply to all waters in the Mid-Atlantic bounded on...

  9. 50 CFR 229.34 - Harbor Porpoise Take Reduction Plan Regulations-Mid-Atlantic.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Regulations-Mid-Atlantic. 229.34 Section 229.34 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE... Emergency Regulations § 229.34 Harbor Porpoise Take Reduction Plan Regulations—Mid-Atlantic. (a)(1) Regulated waters. The regulations in this section apply to all waters in the Mid-Atlantic bounded on...

  10. 50 CFR 229.34 - Harbor Porpoise Take Reduction Plan Regulations-Mid-Atlantic.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Regulations-Mid-Atlantic. 229.34 Section 229.34 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE... Emergency Regulations § 229.34 Harbor Porpoise Take Reduction Plan Regulations—Mid-Atlantic. (a)(1) Regulated waters. The regulations in this section apply to all waters in the Mid-Atlantic bounded on...

  11. 50 CFR 229.34 - Harbor Porpoise Take Reduction Plan Regulations-Mid-Atlantic.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Regulations-Mid-Atlantic. 229.34 Section 229.34 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE... Emergency Regulations § 229.34 Harbor Porpoise Take Reduction Plan Regulations—Mid-Atlantic. (a)(1) Regulated waters. The regulations in this section apply to all waters in the Mid-Atlantic bounded on...

  12. GLOBAL CHANGE RESEARCH NEWS #17: PUBLICATION OF MID-ATLANTIC REGIONAL ASSESSMENT

    EPA Science Inventory

    The report, "Preparing for a Changing Climate: The Potential Consequences of Climate Variability and Change - Mid-Atlantic Overview", summarizes the findings of the first Mid-Atlantic Regional Assessment. The Mid-Atlantic Regional Assessment was led by a team from The Pennsylvani...

  13. Organized Crime and Drug Enforcement Task Force. Hearing before the Committee on the Judiciary. United States Senate, Ninety-Eighth Congress, First Session on the Organized Crime and Drug Enforcement Task Force in the Mid-Atlantic Region Which Would Coordinate Government Agencies, Including U.S. Attorneys, the FBI, DEA, Customs Service, BATF, and the IRS. Dover, Delaware.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Senate Committee on the Judiciary.

    This document presents testimony and proceedings from the Congressional hearings on organized crime and drug enforcement in the Mid-Atlantic region, and government efforts to solve these problems. Opening statements are presented from Senators Strom Thurmond and Joseph Biden. Testimony is also presented from the United States attorneys for the…

  14. Impact of Mid-Atlantic sewage sludge probed

    NASA Astrophysics Data System (ADS)

    Blue, Charles

    1992-01-01

    Every year since 1986, 8 million tons of raw sewage has been dumped into the ocean at the Mid-Atlantic Bight, an area 100 miles off the coast of New York and New Jersey. Originally, this location was thought to be a safe dump site because of its considerable depth and strong ocean currents, which would prevent sewage from accumulating on the ocean floor. Recently, several scientists tested that assumption and found evidence for significant amounts of sewage accumulation at the dump site.Scientific studies of the dump site, coordinated by NOAA's National Undersea Research Program, will be presented at the 1992 AGU Ocean Science Meeting in New Orleans, January 27-31. The studies reveal the extent of sewage sludge accumulation at the Mid-Atlantic Bight and determine the environmental impact that significant accumulations of this material has on the ocean environment.

  15. Composition of basalts from the Mid-Atlantic Ridge

    USGS Publications Warehouse

    Engel, A.E.J.; Engel, C.G.

    1964-01-01

    Studies of volcanic rocks in dredge hauls from the submerged parts of the Mid-Atlantic Ridge suggest that it consists largely of tholeiitic basalt with low values of K, Ti, and P. In contrast, the volcanic islands which form the elevated caps on the Ridge are built of alkali basalt with high values of Ti, Fe3+, P, Na, and K. This distinct correlation between the form of the volcanic structures, elevation above the sea floor, and composition suggests that the islands of alkali basalt are derived from a parent tholeiitic magma by differentiation in shallow reservoirs. The volume of low-potassium tholeiites along the Mid-Atlantic Ridge and elsewhere in the oceans appears to be many times that of the alkali basalts exposed on oceanic islands. Tholeiitic basalts with about 0.2 K2O appear to be the primary and predominant magma erupted on the oceanic floor.

  16. An introduction to mid-Atlantic seasonal pools

    USGS Publications Warehouse

    Brown, L.J.; Jung, R.E.

    2005-01-01

    Seasonal pools, also known as vernal ponds, provide important ecological services to the mid-Atlantic region. This publication serves as an introduction to seasonal pool ecology and management; it also provides tools for exploring seasonal pools, including a full-color field guide to wildlife. Seasonal pools are defined as having four distinctive features: surface water isolation, periodic drying, small size and shallow depth, and support of a characteristic biological community. Seasonal pools experience regular drying that excludes populations of predatory fish. Thus, pools in the mid-Atlantic region provide critical breeding habitat for amphibian and invertebrate species (e.g., spotted salamander (Ambystoma maculatum), wood frog (Rana sylvatica), and fairy shrimp (Order Anostraca)) that would be at increased risk of predation in more permanent waters. The distinctive features of seasonal pools also make them vulnerable to human disturbance. In the mid-Atlantic region, land-use changes pose the greatest challenges to seasonal pool conservation. Seasonal pools are threatened by direct loss (e.g., filling or draining of the pool) as well as by destruction and fragmentation of adjoining terrestrial habitat. Many of the species that depend on seasonal pools for breeding spend the majority of their lives in the surrounding lands that extend a radius of 1000 feet or more from the pools; these vital habitats are being transected by roads and converted to other land uses. Other threats to seasonal pools include biological introductions and removals, mosquito control practices, amphibian diseases, atmospheric deposition, and climate change. The authors recommend a three-pronged strategy for seasonal pool conservation and management in the mid-Atlantic region: education and research, inventory and monitoring of seasonal pools, and landscape-level planning and management.

  17. Forecasting fish biomasses, densities, productions, and bioaccumulation potentials of mid-atlantic wadeable streams.

    PubMed

    Barber, M Craig; Rashleigh, Brenda; Cyterski, Michael J

    2016-01-01

    Regional fishery conditions of Mid-Atlantic wadeable streams in the eastern United States are estimated using the Bioaccumulation and Aquatic System Simulator (BASS) bioaccumulation and fish community model and data collected by the US Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP). Average annual biomasses and population densities and annual productions are estimated for 352 randomly selected streams. Realized bioaccumulation factors (BAF) and biomagnification factors (BMF), which are dependent on these forecasted biomasses, population densities, and productions, are also estimated by assuming constant water exposures to methylmercury and tetra-, penta-, hexa-, and hepta-chlorinated biphenyls. Using observed biomasses, observed densities, and estimated annual productions of total fish from 3 regions assumed to support healthy fisheries as benchmarks (eastern Tennessee and Catskill Mountain trout streams and Ozark Mountains smallmouth bass streams), 58% of the region's wadeable streams are estimated to be in marginal or poor condition (i.e., not healthy). Using simulated BAFs and EMAP Hg fish concentrations, we also estimate that approximately 24% of the game fish and subsistence fishing species that are found in streams having detectable Hg concentrations would exceed an acceptable human consumption criterion of 0.185 μg/g wet wt. Importantly, such streams have been estimated to represent 78.2% to 84.4% of the Mid-Atlantic's wadeable stream lengths. Our results demonstrate how a dynamic simulation model can support regional assessment and trends analysis for fisheries.

  18. What English Language Arts, Math, and Science Instructional Materials Have Districts in the Mid-Atlantic Region States Adopted? Issues & Answers. REL 2010-No. 096

    ERIC Educational Resources Information Center

    Burzichelli, Claudia; Morrill, William; Bausmith, Jennifer; Mackey, Philip E.; Magarelli, Christopher

    2010-01-01

    Despite increasing accountability requirements and a national call for transparency in public policy, Mid-Atlantic Region state education agencies indicate that they have little information about what instructional materials districts adopt. This report describes first-year results of an ongoing project to generate and share information on core…

  19. What English Language Arts, Math, and Science Instructional Materials Have Districts in the Mid-Atlantic Region States Adopted? Summary. Issues & Answers. REL 2010-No. 096

    ERIC Educational Resources Information Center

    Burzichelli, Claudia; Morrill, William; Bausmith, Jennifer; Mackey, Philip E.; Magarelli, Christopher

    2010-01-01

    Despite increasing accountability requirements and a national call for transparency in public policy, Mid-Atlantic Region state education agencies indicate that they have little information about what instructional materials districts adopt. This report describes first-year results of an ongoing project to generate and share information on core…

  20. PREDICTING THE OCCURRENCE OF NUTRIENTS AND PESTICIDES DURING BASE FLOW IN STREAMS: STATUS OF MID-ATLANTIC COASTAL PLAIN AND MIDWEST CORN BELT STUDIES

    EPA Science Inventory

    Random surveys of 174 headwater streams of the Mid-Atlantic Coastal Plain (MACP) and 110 third-order streams in the Midwest Corn Belt (MCB) were conducted in 2000 and 2004, respectively in two cooperative research studies by the U.S. Environmental Protection Agency and U.S. Geolo...

  1. CHARACTERIZATION AND PREDICTION OF NUTRIENTS AND PESTICIDES IN BASE FLOW CONDITIONS OF FIRST ORDER STREAMS IN THE MID-ATLANTIC COASTAL PLAIN-A COLLABORATIVE EFFORT

    EPA Science Inventory

    The Landscape Indicators for Pesticides Study in Mid-Atlantic Coastal Streams (LIPS-MACS) is a collaborative research effort between the U.S. Environmental Protection Agency's Office of Research and Development and the U.S. Geological Survey's National Water Quality Assessment Pr...

  2. 76 FR 68719 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... meeting. SUMMARY: The Mid-Atlantic Fishery Management Council's (Council) Scientific and Statistical... Council's Web site at www.mafmc.org . Special Accommodations The meeting is physically accessible...

  3. Diet of mid-Atlantic Sowerby's beaked whales Mesoplondon bidens

    NASA Astrophysics Data System (ADS)

    Pereira, J. N.; Neves, V. C.; Prieto, R.; Silva, M. A.; Cascão, I.; Oliveira, C.; Cruz, M. J.; Medeiros, J. V.; Barreiros, J. P.; Porteiro, F. M.; Clarke, D.

    2011-11-01

    The first mid-Atlantic diet of Mesoplodon beaked whales is presented, from ten Sowerby's Mesoplodon bidens stranded in the Azores region between 2002 and 2009. This doubles the worldwide number of stomachs sampled, and reveals new feeding habits for this species. The mean number of prey items per stomach was 85±89 (range: 12-238), with fish accounting for 99.3% and cephalopods contributing less than 1% of total prey. Fish otoliths from 15 families and cephalopod lower mandibles from three families were identified, representing 22 taxa. The diet consisted mainly of small mid-water fish, the most numerous being Diaphus sp., Lampanyctus sp. and Melamphaidae species. Myctophids were present in all stranded individuals, followed by Diretmidae, Melamphaidae and Opisthoproctus soleatus, while the remaining fish species were scarce or single occurrences. Consistency of diet in four different years reveals a divergence from all previous records in continental areas, where mainly neritic and shelf-break benthopelagic fish species have been reported. Mid-Atlantic Sowerby's beaked whales' showed dietary plasticity, feeding on the most abundant mid-water groups occurring between 0 and750 m. Trophic level from prey numerical frequency was estimated at 4.4±0.46.

  4. Linking Mid-Atlantic Landscapes to Glacio-Isostatic Adjustments

    NASA Astrophysics Data System (ADS)

    Pavich, M. J.

    2006-12-01

    Mid-Atlantic landscape studies have traditionally focused on the physiographic contrasts of landforms and their genetic processes. The strong contrasts of mountain, piedmont and coastal plain have dominated thinking about landscape history (Davis) and dynamic equilibrium (Hack). Timescales in these conceptual models are >106 years. Recent research on bedrock channel incision and uplift of late Pleistocene estuarine and marine deposits shows that significant landscape adjustments south of the glacial border occur on timescales of <105 years. Optically stimulated luminescence (OSL) dates and cosmogenic isotope exposure dating indicate that between ~36ka and ~10ka, uplift occurred at ~1m/ky and bedrock channels incised at ~0.6m/ky in the vicinity of Chesapeake Bay. These high rates, particularly compared to southern Appalachian landscapes in long- term isostatic equilibrium, are linked to the glacio-isostatic adjustments (GIA) created by the Laurentide ice of the latest glacial cycle. Recognition of major landform adjustments due to forebulge uplift and subsidence at this timescale requires a fundamental reassessment of Appalachian landscape models. Geomorphic and stratigraphic studies can provide important constraints on GIA models. The role of GIA in the mid-Atlantic region also provides information about ongoing landscape changes, particularly the potential for future subsidence.

  5. WATERSHED RESTORATION AND FISHERIES MANAGEMENT IN THE MID-ATLANTIC HIGHLANDS

    EPA Science Inventory

    This presentation is about watershed restoration and fisheries management in the Mid-Atlantic Highlands. The goal of the Canaan Valley Institue is to develop and implement solutions to restore damaged areas and protect aquatic systems in the Mid-Atlantic Highlands. A decision ana...

  6. Mid-Atlantic Consumer Purchasing Behavior and Knowledge of Locally Grown and Seasonal Produce

    ERIC Educational Resources Information Center

    Chamberlain, Amy J.; Kelley, Kathleen M.; Hyde, Jeffrey

    2013-01-01

    Mid-Atlantic urban consumers were surveyed on their fruit and vegetable purchasing behaviors and their knowledge of produce grown in the region. Consumers were generally unaware of what produce is grown in the mid-Atlantic and during what months they are harvested. Additionally, differences pertaining to number of produce items purchased were…

  7. GLOBAL CHANGE RESEARCH NEWS #6: PUBLICATION OF FIRST REPORT FROM MID-ATLANTIC REGIONAL ASSESSMENT (MARA)

    EPA Science Inventory

    This research news edition announces the publication of the first report from the Mid-Atlantic Regional Assessment (MARA). The report is entitled, *Climate Change Impacts in the Mid-Atlantic Region -- A Workshop Report.* MARA is being conducted as part of the USGCRP First Nation...

  8. CLIMATE IMPACTS ON NUTRIENT FLUXES IN STREAM FLOW IN THE MID-ATLANTIC REGION

    EPA Science Inventory

    As part of a national assessment process, researchers of the Mid-Atlantic Regional Assessment (MARA) are studying the impacts of climate variation and change on the natural and social systems of the Mid-Atlantic Region. This poster presents research investigating climate impacts ...

  9. COLLABORATIVE RESEARCH, MONITORING AND ASSESSMENT IN THE MID-ATLANTIC REGION

    EPA Science Inventory

    EPA Region 3 to implement a long-term research, monitoring, and assessment program in the Mid-Atlantic region - the Mid-Atlantic Integrated Assessment (MAIA). The MAIA mission is to develop a broad-based partnership to integrate scientific knowledge into the decision-making proc...

  10. 75 FR 4348 - Mid-Atlantic Fishery Management Council; Public Hearings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-27

    ... National Oceanic and Atmospheric Administration RIN 0648-XU05 Mid-Atlantic Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public hearings. SUMMARY: The Mid-Atlantic Fishery Management... Atlantic Mackerel, Squid, and Butterfish (MSB) Fishery Management Plan (FMP). See SUPPLEMENTARY...

  11. 77 FR 65364 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ... Fishery Management Council (Council) Staff will convene a meeting of the Visioning and Strategic Planning... National Oceanic and Atmospheric Administration RIN 0648-XC316 Mid-Atlantic Fishery Management Council..., Baltimore, MD 21240; telephone: (410) 859-3300. Council address: Mid-Atlantic Fishery Management...

  12. 75 FR 2488 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-15

    ...; telephone: (302) 674-2331. FOR FURTHER INFORMATION CONTACT: Daniel T. Furlong, Executive Director, Mid-Atlantic Fishery Management Council, 300 S. New Street, Room 2115, Dover, DE 19904; telephone: (302) 674... other auxiliary aids should be directed to M. Jan Bryan at the Mid-Atlantic Council Office, (302)...

  13. 76 FR 68745 - DC Energy, LLC; DC Energy Mid-Atlantic, LLC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... No: 2011-28690] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-8-000] DC Energy, LLC; DC Energy Mid-Atlantic, LLC v. PJM Interconnection, L.L.C.; Notice of Complaint Take notice... Commission (Commission), 18 CFR 385.206 (2011), DC Energy, LLC (DC Energy) and DC Energy Mid-Atlantic...

  14. Microbial ecology of deep-water mid-Atlantic canyons

    USGS Publications Warehouse

    Kellogg, Christina A.

    2011-01-01

    The research described in this fact sheet will be conducted from 2012 to 2014 as part of the U.S. Geological Survey's DISCOVRE (DIversity, Systematics, and COnnectivity of Vulnerable Reef Ecosystems) Program. This integrated, multidisciplinary effort will be investigating a variety of topics related to unique and fragile deep-sea ecosystems from the microscopic level to the ecosystem level. One goal is to improve understanding, at the microbiological scale, of the benthic communities (including corals) that reside in and around mid-Atlantic canyon habitats and their associated environments. Specific objectives include identifying and characterizing the microbial associates of deep-sea corals, characterizing the microbial biofilms on hard substrates to better determine their role in engineering the ecosystem, and adding a microbial dimension to benthic community structure and function assessments by characterizing micro-eukaryotes, bacteria, and archaea in deep-sea sediments.

  15. 77 FR 77036 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-31

    ... FURTHER INFORMATION CONTACT: Chris Moore, Ph.D., Executive Director, Mid-Atlantic Fishery Management... aids should be directed to Chris Moore, Ph.D. (see FOR FURTHER INFORMATION CONTACT) at least 5...

  16. 75 FR 20984 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ... Council's (MAFMC) Ad Hoc Search Committee will hold a closed meeting. DATES: Monday, May 10, 2010 from 9 a... INFORMATION: The Mid-Atlantic Council is currently seeking a new Executive Director. The Ad Hoc...

  17. A STRATEGY FOR INTEGRATED ECOLOGICAL RESTORATION OF RIPARIAN BUFFERS IN THE MID-ATLANTIC REGION

    EPA Science Inventory

    Increased sediments, nutrients, and other contaminants in the Mid-Atlantic region contribute to environmental problems ranging from stream degradation to possibly Pfiesteria attacks in Chesapeake Bay. Restoring riparian areas - the filters between terrestrial watersheds and aquat...

  18. 78 FR 48419 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ... CONTACT: Christopher M. Moore Ph.D., Executive Director, Mid-Atlantic Fishery Management Council, 800 N... emergency action under section 305(c) of the Magnuson-Stevens Fishery Conservation and Management...

  19. 76 FR 3878 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-21

    ...: (302) 674-2331. Council address: Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite 201, Dover, DE 19901; telephone: (302) 674-2331. FOR FURTHER INFORMATION CONTACT: Christopher M....

  20. 77 FR 77036 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-31

    ...: Christopher M. Moore Ph.D., Executive Director, Mid-Atlantic Fishery Management Council, 800 N. State Street... least 5 days prior to the meeting date. Dated: December 26, 2012. Tracey L. Thompson, Acting...

  1. 3D Propagation and Geoacoustic Inversion Studies in the Mid-Atlantic Bight

    DTIC Science & Technology

    2016-06-07

    3D Propagation and Geoacoustic Inversion Studies in the Mid-Atlantic Bight Kevin B. Smith Code PH/Sk, Department of Physics Naval Postgraduate...properties and measured transmission loss. Results from this analysis will be considered in the context of geoacoustic inversions . OBJECTIVES To...bathymetric features and ocean fronts near the shelf break of the mid-Atlantic Bight, and use of various data for geoacoutic inversion studies. The results

  2. Documenting nursing and health care history in the mid-Atlantic region.

    PubMed Central

    Weinberg, D M

    1993-01-01

    The records of health care institutions can be of great value to library patrons. Yet, librarians rarely provide these unique resources because records must be collected, arranged, and described before they can be useful to patrons. The University of Pennsylvania's Center for the Study of the History of Nursing conducted a survey of health care agencies in the mid-Atlantic region to locate records created by area health care institutions. The goals of this project were to develop a database of primary source materials, to place organizational records with enduring value at suitable repositories, and to assist in the development of in-house archival programs at agencies keeping records. In-house programs provide health care institutions with a systematic way to preserve their records for administrative, legal, fiscal, and research use. Such programs also facilitate access to information, reduce cost through records management, and promote an institution through preservation and use of its historical records. The survey demonstrated that record keeping is not coordinated in most institutions, and that institutional awareness of the organization or content of records is minimal. PMID:8428186

  3. Landscape correlates of breeding bird richness across the United States mid-Atlantic region

    USGS Publications Warehouse

    Jones, K.B.; Neale, A.C.; Nash, M.S.; Riitters, K.H.; Wickham, J.D.; O'Neill, R. V.; Van Remortel, R. D.

    2000-01-01

    Using a new set of landscape indicator data generated by the U.S.EPA, and a comprehensive breeding bird database from the National Breeding Bird Survey, we evaluated associations between breeding bird richness and landscape characteristics across the entire mid-Atlantic region of the United States. We evaluated how these relationships varied among different groupings (guilds) of birds based on functional, structural, and compositional aspects of individual species demographics. Forest edge was by far the most important landscape attribute affecting the richness of the lumped specialist and generalist guilds; specialist species richness was negatively associated with forest edge and generalist richness was positively associated with forest edge. Landscape variables (indicators) explained a greater proportion of specialist species richness than the generalist guild (46% and 31%, respectively). The lower value in generalists may reflect freer-scale distributions of open habitat that go undetected by the Landsat satellite, open habitats created by roads (the areas from which breeding bird data are obtained), and the lumping of a wide variety of species into the generalist category. A further breakdown of species into 16 guilds showed considerable variation in the response of breeding birds to landscape conditions; forest obligate species had the strongest association with landscape indicators measured in this study (55% of the total variation explained) and forest generalists and open ground nesters the lowest (17% of the total variation explained). The variable response of guild species richness to landscape pattern suggests that one must consider species' demographics when assessing the consequences of landscape change on breeding birds.Using a new set of landscape indicator data generated by the U.S. EPA, and a comprehensive breeding bird database from the National Breeding Bird Survey, we evaluated associations between breeding bird richness and landscape

  4. Mid-Atlantic Technology Applications Center. Quarters 1-4

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Mid-atlantic Technology Application Center (MTAC) pursued a number of initiatives designed to enhance the strategic position of the Langley Research Center (LaRC) and NASA in industry. Among these was a closer association with the ISA, International Society for Measurement and Control. During 1997, MTAC placed articles regarding NASA-developed technologies in each In Tech magazine. The monthly magazine is sent to 46,000 sensors and instrumentation professionals. In addition, MTAC coordinated NASXs participation in the ISA Tech 97 Conference, securing $112,000 of free exhibit space, 1500 NASA sensors posters at no cost to NASA, and thousands of dollars of free publicity. MTAC was awarded a contract by ISA to operate its Technical Resource Center (TRC). The goal of this project is to determine what user needs are in order to identify opportunities for collaboration between NASA centers and companies. In addition, the TRC work will lay the groundwork for the Technology Development Consortium (TDC) proposed by MTAC. The purpose of the TDC is to: match current industry needs with NASA technologies available now, and to identify future needs of NASA and industry which may lead to dual use projects. The goal of these activities is twofold: to infuse NASA technologies into the sensors and instrumentation industry and to secure industry funds to support NASA technology development projects. The instrumentation and sensors industry is valued at $30 billion worldwide, with $12 billion in sales in the United States. The growth rate averages 13.5%, so that by the year 2000, the industry will produce products worth $49 billion. More than 80% of instruments, sensors and control systems are currently manufactured in the United States. NASA and the industry do not have a history of collaborative projects; MTAC's initiatives in this area are designed to foster working relationships between the two parties that will help maintain U.S. leadership in this field. Mid-atlantic Technology

  5. Ground-water vulnerability to nitrate contamination at multiple thresholds in the mid-Atlantic region using spatial probability models

    USGS Publications Warehouse

    Greene, Earl A.; LaMotte, Andrew E.; Cullinan, Kerri-Ann

    2005-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency?s Regional Vulnerability Assessment Program, has developed a set of statistical tools to support regional-scale, ground-water quality and vulnerability assessments. The Regional Vulnerability Assessment Program?s goals are to develop and demonstrate approaches to comprehensive, regional-scale assessments that effectively inform managers and decision-makers as to the magnitude, extent, distribution, and uncertainty of current and anticipated environmental risks. The U.S. Geological Survey is developing and exploring the use of statistical probability models to characterize the relation between ground-water quality and geographic factors in the Mid-Atlantic Region. Available water-quality data obtained from U.S. Geological Survey National Water-Quality Assessment Program studies conducted in the Mid-Atlantic Region were used in association with geographic data (land cover, geology, soils, and others) to develop logistic-regression equations that use explanatory variables to predict the presence of a selected water-quality parameter exceeding a specified management concentration threshold. The resulting logistic-regression equations were transformed to determine the probability, P(X), of a water-quality parameter exceeding a specified management threshold. Additional statistical procedures modified by the U.S. Geological Survey were used to compare the observed values to model-predicted values at each sample point. In addition, procedures to evaluate the confidence of the model predictions and estimate the uncertainty of the probability value were developed and applied. The resulting logistic-regression models were applied to the Mid-Atlantic Region to predict the spatial probability of nitrate concentrations exceeding specified management thresholds. These thresholds are usually set or established by regulators or managers at National or local levels. At management thresholds of

  6. Characterization of Intraplate Seismicity in the Mid-Atlantic US

    NASA Astrophysics Data System (ADS)

    Soto-Cordero, L.; Meltzer, A.; Stachnik, J. C.

    2015-12-01

    Using data from the USArray TA and permanent seismic stations we explore the relationship between seismicity and lithospheric structure in the Mid-Atlantic US where previous studies suggest the clustering of seismicity within several seismic zones. Given low strain rates, creating a robust catalog of tectonic events with a low magnitude threshold is essential. Analysis of events in our study region with hypocenters determined by the Array Network Facility (ANF) during the last 2 years shows that 51% have a depth equal to zero. To assess whether the events are of natural or anthropogenic origin we apply a series of discriminants, such as, geographic correlation to known mining sites, temporal clustering and waveform characteristics. Using West Virginia as a test, we found 100% of events with zero depth are associated with mining operations. Interesting patterns emerge when comparing ANF locations of depths greater than zero with historic seismicity and events instrumentally recorded by permanent stations. Seismicity occurs in some regions where no seismic activity had been previously observed but events along the boundary between the Piedmont and Coastal Plain appear as a continuous band of seismicity making it more difficult to identify discrete seismic zones. Earthquake magnitude threshold is also examined in preparation for high-precision relocation of the events to better address the spatio-temporal nature of seismicity in the region. The ANF catalog shows a magnitude of completeness to 2.2 in the region. However, the ANSS catalog shows 58 events M≤2.2 in the last 2 years while the ANF catalog provides location for only 12 of those events (21%). Continued efforts to calibrate the detection and association algorithms will help lower the magnitude threshold and complete the catalog.

  7. Phytoplankton Assemblage Patterns in the Southern Mid-Atlantic Bight

    NASA Technical Reports Server (NTRS)

    Makinen, Carla; Moisan, Tiffany A. (Editor)

    2012-01-01

    As part of the Wallops Coastal Oceans Observing Laboratory (Wa-COOL) Project, we sampled a time-series transect in the southern Mid-Atlantic Bight (MAB) biweekly. Our 2-year time-series data included physical parameters, nutrient concentrations, and chlorophyll a concentrations. A detailed phytoplankton assemblage structure was examined in the second year. During the 2-year study, chlorophyll a concentration (and ocean color satellite imagery) indicated that phytoplankton blooms occurred in January/February during mixing conditions and in early autumn under stratified conditions. The chlorophyll a concentrations ranged from 0.25 microgram 1(exp -1) to 15.49 microgram 1(exp -1) during the 2-year period. We were able to discriminate approximately 116 different species under phase contrast microscopy. Dominant phytoplankton included Skeletonema costatum, Rhizosolenia spp., and Pseudo-nitzschia pungens. In an attempt to determine phytoplankton species competition/succession within the assemblage, we calculated a Shannon Weaver diversity index for our diatom microscopy data. Diatom diversity was greatest during the winter and minimal during the spring. Diatom diversity was also greater at nearshore stations than at offshore stations. Individual genera appeared patchy, with surface and subsurface patches appearing abruptly and persisting for only 1-2 months at a time. The distribution of individual species differed significantly from bulk variables of the assemblage (chlorophyll a ) and total phytoplankton assemblage (cells), which indicates that phytoplankton species may be limited in growth in ways that differ from those of the total assemblage. Our study demonstrated a highly diverse phytoplankton assemblage throughout the year, with opportunistic species dominating during spring and fall in response to seasonal changes in temperature and nutrients in the southern MAB.

  8. Hydrothermal Activity on the Southern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    German, C. R.; Connelly, D. P.; Evans, A. J.; Parson, L. M.

    2002-12-01

    We present evidence for high-temperature hydrothermal venting along the southern Mid-Atlantic Ridge (MAR) 2-14S. The MAR south of the equator has been identified as a key target for hydrothermal exploration because the large-offset Romanche and Chain fracture zones may act as important barriers to biological communication along the ridge-axis (Van Dover et al., Science, 2002). During RRS James Clark Ross cruise JR65 (Sept-Oct. 2001) we occupied a series of 13 CTD hydrocast stations, one each at the centre of a series of 2nd-order ridge-segments, close to and away from the influence of the Ascension Island "hotspot". Post-cruise laboratory analyses have revealed TDMn anomalies of >2nmol/litre (background = 0.5 nmol/litre) at stations within each of four segments located between the Chain and Ascension Fracture Zones (away from the "hotspot") and in the two northernmost "hot-spot influenced" segments to the south, between the Ascension and Boca Verde Fracture Zones. Strongest anomalies were observed in the segment closest to Ascension Island itself, where TDMn anomalies measured in bottle-samples coincided with optical back-scatter anomalies measured in situ using a SeaTech LSS light scattering sensor. A weaker TDMn anomaly was also observed adjacent to the Boca Verde Fracture Zone and coincident with a WOCE section which has previously reported evidence for primordial 3He release from the MAR-crest (Ruth et al., Deep Sea Res., 2000). Our survey covered a large section of ridge-crest, comparable to that investigated by Klinkhammer et al. (Nature, 1985) on the northern MAR. Multiple offset segments have been investigated and the data support the presence of multiple discrete hydrothermal sources. To-date, the best positional information we have for any one vent-site is in the segment immediately south of the Ascension Fracture Zone. Water depth in this segment is >3000m yet it is situated <100km from the port of Georgetown, Ascension. We believe this station to be

  9. Shelf-Slope Exchange in the Mid-Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Goodman, P. J.; Wilkin, J.

    2004-12-01

    A high resolution model (ROMS, the Regional Ocean Modeling System) of U.S. East Coast circulation from Newfoundland to Cuba is used to explore features of alongshelf freshwater transport, residence time, and shelf-sea/deep-ocean exchange. The focus of the analysis is the Mid-Atlantic Bight (MAB) shelf-slope system which, like continental shelves throughout the world, contributes to the oceanic budgets of heat, salt, and fresh water. In addition, the "continental shelf pump" transfers carbon from the atmosphere to the deep ocean through fluxes of dissolved organic carbon and particulate organic carbon off the shelves. Solar radiation, evaporation, rainfall, riverine input, gas exchange with the atmosphere, and biological production all modify the character of shelf waters. In the MAB, the shelf-slope front separates shallow coastal waters from slope waters and the Gulf Stream, extending residence times on the shelf and maintaining coastal salinities at significantly lower levels than those offshore. The southwestward coastal mean flow exchanges weakly with slope waters along most of the MAB, with the strongest offshore flow occurring at Cape Hatteras where much of the flow is entrained into the Gulf Stream front. The shelf circulation is influenced by input from the Hudson and Delaware Rivers and Chesapeake Bay. Along the shelf break, exchange is modulated by warm-core rings from the Gulf Stream and variability of the shelf-break front. Key features of the seasonal circulation such as the MAB "Cold Pool" are captured by the simulation. Measurements suggest that DOC in shelf and shallow slope waters of the MAB include both old marine carbon and a young terrestrial-riverine-estuarine component, and these carbon cycling processes are being studied with a companion primary production, nitogen and carbon cycle model directly coupled to ROMS. Results showing salinity, idealized dye and Lagrangian float tracking results from a ROMS simulation of the MAB shelf circulation

  10. 75 FR 48666 - Calpine Mid-Atlantic Marketing, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Calpine Mid-Atlantic Marketing, LLC; Supplemental Notice That Initial Market... supplemental notice in the above-referenced proceeding, of Calpine Mid-Atlantic Marketing, LLC's...

  11. 77 FR 5008 - Solios Power Mid-Atlantic Virtual LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Solios Power Mid-Atlantic Virtual LLC; Supplemental Notice That Initial... notice in the above-referenced proceeding of Solios Power Mid-Atlantic Virtual LLC's application...

  12. STATISTICAL TECHNIQUES FOR DETERMINATION AND PREDICTION OF FUNDAMENTAL FISH ASSEMBLAGES OF THE MID-ATLANTIC HIGHLANDS

    EPA Science Inventory

    A statistical software tool, Stream Fish Community Predictor (SFCP), based on EMAP stream sampling in the mid-Atlantic Highlands, was developed to predict stream fish communities using stream and watershed characteristics. Step one in the tool development was a cluster analysis t...

  13. PREDICTION OF FUNDAMENTAL ASSEMBLAGES OF MID-ATLANTIC HIGHLAND STREAM FISHES

    EPA Science Inventory

    A statistical software tool, the Stream Fish Assemblage Predictor (SFAP), based on stream sampling data collected by the EPA in the mid-Atlantic Highlands, was developed to predict potential stream fish communities using characteristics of the stream and its watershed.
    Step o...

  14. IMPACT OF CLIMATE VARIATION AND CHANGE ON MID-ATLANTIC REGION HYDROLOGY AND WATER RESOURCES

    EPA Science Inventory

    The sensitivity of hydrology and water resources to climate variation and climate change is assessed for the Mid-Atlantic Region (MAR) of the United States. Observed streamflow, groundwater, and water-quality data are shown to vary in association with climate variation. Projectio...

  15. INDICATORS OF CHANGE IN MID-ATLANTIC WATERSHEDS, AND CONSEQUENCES IN UPPER CHESAPEAKE BAY

    EPA Science Inventory

    The rate of change of atmospheric temperature in the Northern Hemisphere in the past century relative to the preceding millennium strongly suggests that we are in a period of rapid global climate change. The mid-Atlantic region is quite sensitive to larger-scale climate variation...

  16. 78 FR 55063 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-09

    ... Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meeting. SUMMARY: The Spiny Dogfish... address below. Webinar link: http://mafmc.adobeconnect.com/dogfish/ Council address: Mid-Atlantic Fishery...: The Spiny Dogfish Monitoring Committee will review the annual catch target (ACT) and other...

  17. 76 FR 54739 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-02

    ... Statistical Committee (SSC) and the Spiny Dogfish Monitoring Committee of the Mid-Atlantic Fishery Management.... until 5 p.m. and Thursday, September 22 from 8 a.m. until 5 p.m. The Spiny Dogfish Monitoring Committee... recommendations for spiny dogfish; special session for social/economics issues; review MAFMC five-year...

  18. 78 FR 52135 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-22

    .... SUMMARY: The Mid-Atlantic Fishery Management Council's (Council) Spiny Dogfish Advisory Panel (AP) will meet to develop a Fishery Performance Report for the Spiny Dogfish fishery in preparation for the... the Council address below. Webinar link: http://mafmc.adobeconnect.com/dogfish/ Council address:...

  19. 78 FR 48421 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ... Fishery Management Council's Spiny Dogfish Advisory Panel (AP) will meet to develop a Fishery Performance Report for the Spiny Dogfish fishery in preparation for the Council and the Council's Scientific and... link: http://mafmc.adobeconnect.com/dogfish/ Council address: Mid-Atlantic Fishery Management...

  20. 78 FR 53132 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-28

    ...-Atlantic Fishery Management Council's Spiny Dogfish Advisory Panel (AP) will meet to develop a Fishery Performance Report for the Spiny Dogfish fishery in preparation for the Council and the Council's Scientific...: http://mafmc.adobeconnect.com/dogfish/ Council Address: Mid-Atlantic Fishery Management Council, 800...

  1. ASSOCIATIONS BETWEEN NAO VARIBILITY AND U.S. MID-ATLANTIC REGION HYDROCLIMATOLOGY

    EPA Science Inventory

    Variability in the climate of the US Mid-Atlantic Region is associated with larger scale variability in the El Nino-Southern Oscillation (ENSO), the Pacific North American (PNA) teleconnection pattern, and the North Atlantic Oscillation (NAO). Collectively, these three large-scal...

  2. IMPACTS OF CLIMATE VARIATION AND CHANGE ON MID-ATLANTIC REGION HYDROLOGY

    EPA Science Inventory

    This study analyzes periodic variations in the climate of the mid-Atlantic Region over the last 100 years and uses general circulation models (GCMs) to project major climate trends for the next hundred years. Historical data include the Palmer Drought Severity Index (PDSI) for th...

  3. SELF-ORGANIZING MAPS FOR INTEGRATED ASSESSMENT OF THE MID-ATLANTIC REGION

    EPA Science Inventory

    A. new method was developed to perform an environmental assessment for the
    Mid-Atlantic Region (MAR). This was a combination of the self-organizing map (SOM) neural network and principal component analysis (PCA). The method is capable of clustering ecosystems in terms of envi...

  4. THE POTENTIAL IMPACTS OF CLIMATE CHANGE ON THE MID-ATLANTIC COASTAL REGION

    EPA Science Inventory

    This paper assesses the potential impacts of climate change on the mid-Atlantic coastal (MAC) region of the United States. In order of increasing uncertainty, it is projected that sea level, temperature and streamflow will increase in the MAC region in response to higher levels o...

  5. Greenhouse gas emissions from natural, restored, and prior-converted wetlands of the Mid-Atlantic

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The hydrologic restoration of drained agricultural wetlands may impact greenhouse gases, particularly nitrous oxide emissions. Assessment of this impact was part of the Natural Resource Conservation Service Mid-Atlantic Regional Conservation Effects Assessment Program (MIAR-CEAP), with sample sites ...

  6. Nitrous oxide emissions from natural, converted, and restored wetlands of the Mid-atlantic Coastal Plain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    On the Mid-Atlantic Coastal Plain of the United States, wetlands have often been drained and converted to agricultural use. Recent efforts by the Natural Resources Conservation Service have attempted to restore some of the prior-converted farmland back to their natural state. These restored wetlands...

  7. 75 FR 35768 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE..., and Bluefish Monitoring Committee's will hold a public meeting via webinar. DATES: The webinar will be... remotely via computer and/or phone access or may attend the meeting in person at the Mid- Atlantic...

  8. GLOBAL CHANGE RESEARCH NEWS #2: MID-ATLANTIC REGIONAL ASSESSMENT (MARA)

    EPA Science Inventory

    As part of this National Assessment effort mandated by the Global Change Research Act of 1990, EPA's Global Change Research Program is sponsoring the Mid-Atlantic Regional Assessment (MARA). With EPA sponsorship, a multi-disciplinary team of faculty members is leading the first a...

  9. Trophic Structure Over the Northern Mid-Atlantic Ridge: The Bathypelagic Zone Really Matters

    EPA Science Inventory

    We present preliminary results and ongoing efforts to characterize the trophic structure and energy flow of the pelagic ecosystems of the northern Mid-Atlantic Ridge (MAR), from Iceland to the Azores. This study is one component of the international CoML field project MAR-ECO (ww...

  10. APPLICATION OF A MULTIPURPOSE UNEQUAL-PROBABILITY STREAM SURVEY IN THE MID-ATLANTIC COASTAL PLAIN

    EPA Science Inventory

    A stratified random sample with unequal-probability selection was used to design a multipurpose survey of headwater streams in the Mid-Atlantic Coastal Plain. Objectives for data from the survey include unbiased estimates of regional stream conditions, and adequate coverage of un...

  11. 77 FR 12814 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ...; discussion of the peer review of the Management Strategy Evaluation Study of the ABC Control Rules... Monitoring Committee is to recommend management measures designed to achieve recommended catch limits... National Oceanic and Atmospheric Administration RIN0648-XB056 Mid-Atlantic Fishery Management...

  12. 76 FR 69706 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ..., Black Sea Bass Monitoring Committee, and the Mid-Atlantic Fishery Council's and the Atlantic States Marine Fisheries Commission's Summer Flounder, Scup, and Black Sea Bass Advisors will hold public... meeting agenda. ADDRESSES: The Summer Flounder, Scup, and Black Sea Bass Monitoring Committee...

  13. 77 FR 39998 - Mid-Atlantic Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-06

    ... the Bluefish, Summer Flounder, Scup, and Black Sea Bass Monitoring Committees of the Mid-Atlantic... meeting of the Council Monitoring Committees for bluefish, summer flounder, scup, and black sea bass will... 2013 ABC recommendations to the Council for summer flounder, scup, black sea bass and bluefish;...

  14. A SURVEY OF FISH CONTAMINATION IN SMALL WADEABLE STREAMS IN THE MID-ATLANTIC REGION

    EPA Science Inventory

    In 1993 and 1994, fish tissue samples were collected from first, second and third order streams in the Mid-Atlantic Region of the United States.The tissue samples were prepared from whole fish from prioritized lists of Small Target Species and Large Target Species. The two types ...

  15. VULNERABILITY OF ECOSYSTEMS OF THE MID-ATLANTIC REGION, USA, TO CLIMATIC CHANGE

    EPA Science Inventory

    Changes in the distribution of vegetation in the mid-Atlantic region of the United States were explored for two climate-change scenarios. The equilibrium vegetation ecology (EVE) model was used to project the distribution of life forms and to combine these into biomes for a doubl...

  16. Mid-Atlantic Region: A Report Identifying and Addressing the Educational Needs

    ERIC Educational Resources Information Center

    US Department of Education, 2011

    2011-01-01

    This report presents the deliberations of the Mid-Atlantic Regional Advisory Committee (RAC), one of 10 RACs established under the Educational Technical Assistance Act of 2002 (20 U.S.C. sections 9601 et. seq.) to assess the educational needs of the region. The committee's report outlines the educational needs across the District of Columbia and…

  17. Characterization Methods for Small Estuarine Systems in the Mid-Atlantic Region of the United States

    EPA Science Inventory

    Various statistical methods were applied to spatially discrete data from 14 intensively sampled small estuarine systems in the mid-Atlantic U.S. The number of sites per system ranged from 6 to 37. The surface area of the systems ranged from 1.9 to 193.4 km2. Parameters examined ...

  18. SPATIAL PATTERNS AND ECOLOGICAL DETERMINANTS OF BENTHIC ALGAL ASSEMBLAGES IN MID-ATLANTIC STREAMS, USA

    EPA Science Inventory

    We attempted to identify spatial patterns and determinants for benthic algal assemblages in Mid-Atlantic streams. Periphyton, water chemistry, stream physical habitat, riparian conditions, and land cover/use in watersheds were characterized at 89 randomly selected stream sites i...

  19. 78 FR 20897 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    .... Moore Ph.D., Executive Director, Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite 201... require emergency action under section 305(c) of the Magnuson-Stevens Fishery Conservation and Management..., 2013. William D. Chappell, Acting Deputy Director, Office of Sustainable Fisheries, National...

  20. 76 FR 9553 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-18

    ... of the Mid-Atlantic Fishery Management Council's (Council) Scientific and Statistical Committee (SSC) will meet with the Council's Atlantic Mackerel, Squid and Butterfish Industry Advisory Panel (AP... input from its Industry Advisory Panels in advance of SSC meetings where ABC recommendations are...

  1. 77 FR 22285 - Mid-Atlantic Fishery Management Council; Public Hearings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-13

    ... Amendment 14 to the Atlantic Mackerel, Squid, and Butterfish (MSB) Fishery Management Plan (FMP). DATES...://www.mafmc.org/fmp/msb.htm . Council address: Mid-Atlantic Fishery Management Council, 800 N. State... shad (river herrings and shads or ``RH/S'') in the MSB FMP. The Amendment has three purposes:...

  2. 75 FR 20984 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ...; telephone: (302) 674-2331. FOR FURTHER INFORMATION CONTACT: Daniel T. Furlong, Executive Director, Mid-Atlantic Fishery Management Council, 800 N. State Street, Suite 201, Dover, DE 19901;telephone: (302) 674... Council, 800 N. State St., Suite 201, Dover, DE 19901; telephone: 302-674-2331, or fax...

  3. ASSESSING THE HYDROGEOLOGIC CLASSIFICATION SYSTEM IN MID-ATLANTIC COASTAL PLAIN STREAMS USING BENTHIC MACROINVERTEBRATES

    EPA Science Inventory

    Assessing classification systems that describe natural variation across regions is an important first step for developing indicators. We evaluated a hydrogeologic framework for first order streams in the mid-Atlantic Coastal Plain as part of the LIPS-MACS (Landscape Indicators f...

  4. A REGIONAL SCALE TOXICITY ASSESSMENT OF SEDIMENT IN THE MID-ATLANTIC AND SOUTHERN ROCKIES, USA

    EPA Science Inventory

    As part of the Environmental Monitoring and Assessment Program (EMAP), sediment samples were collected to assess toxicity on a regional scale in streams and rivers in the Mid-Atlantic U.S. in 1994, 1997 and 1998, and in the Colorado Rocky Mountains in 1994 and 1995. Sample sites...

  5. The Mid-Atlantic Wetland Conservation Effects Assessment Project: Ecosystem Services, Conservation Practices, and Synergistic Monitoring

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Mid-Atlantic Region of the eastern U.S. is characterized by a diversity of coastal and freshwater wetland ecosystems that humans and other species depend upon. Ecosystem services provided by wetlands include the regulation of runoff and floodwaters, habitat for many unique organisms, pollutant r...

  6. ASSESSMENT FRAMEWORK FOR MID-ATLANTIC COASTAL PLAIN STREAMS USING BENTHIC MACRO INVERTEBRATES

    EPA Science Inventory

    A collaborative study among 6 states along the mid-Atlantic seaboard of the USA developed a consistent approach for collecting and interpreting macroinvertebrate data for low-gradient streams of the coastal plain. The study had 3 objectives: 1) to evaluate the validity of aggrega...

  7. SEDIMENT MICROBIAL RESPIRATION IN A SYNOPTIC SURVEY OF MID-ATLANTIC REGION STREAMS

    EPA Science Inventory

    l. The rate of microbial respiration on fine-grained stream sediments was measured at 196 first-to third-order sites in the mid-Atlantic region of the United States.2. Sample collection took place between April and July in 1993, 1994 and 1995.3. Study streams were randomly sele...

  8. ESTIMATING STREAMFLOW AND ASSOCIATED HYDRAULIC GEOMETRY, THE MID-ATLANTIC REGION, USA

    EPA Science Inventory

    Methods to estimate streamflow and channel hydraulic geometry were developed for ungaged streams in the Mid-Atlantic Region. Observed mean annual streamflow and associated hydraulic geometry data from 75 gaging stations located in the Appalachian Plateau, the Ridge and Valley, an...

  9. ASSESMENT OF THE CONDITION OF THE ECOLOGICAL RESOURCES OF THE MID-ATLANTIC

    EPA Science Inventory

    One objective of the Mid Atlantic Integrated Assessment (MAIA) program is a series of "state of the resource" assessment reports describing the condition of important natural resources within the region. These will culminate in an integrated statement of the ecological condition ...

  10. DECISION TOOL FOR RIPARIAN ECOSYSTEM MANAGMENT IN THE MID-ATLANTIC HIGHLANDS

    EPA Science Inventory

    In the Canaan Valley Highlands of the Mid-Atlantic, riparian zone restoration has been identified as a critical watershed management practice not only for the ecosystem services provided but also for the potential socioeconomic growth from environmental investment and job creatio...

  11. INNOVATIVE ENVIRONMENTAL EDUCATION CONTRIBUTES TO IMPROVED MANAGEMENT PRACTICES IN THE MID-ATLANTIC

    EPA Science Inventory

    The Mid-Atlantic Integrated Assessment (MAIA) and its partner, University of Maryland, Baltimore County (UMBC) have developed a graduate-level course focused on successful application of science by decision-makers to address a particular problem. Students conduct a literature rev...

  12. Ecological Condition of Coastal Ocean Waters Along the U.S. Mid-Atlantic Bight: 2006

    EPA Science Inventory

    This report presents the results of an assessment of ecological condition in coastal-ocean waters of the U.S. mid-Atlantic Bight (MAB), along the U.S. continental shelf from Cape Cod, MA and Nantucket Shoals to the northeast to Cape Hatteras to the south, based on sampling conduc...

  13. APPLICATION OF USEPA'S DRINKING WATER REGULATIONS TOWARDS RAINWATER CATCHMENT SYSTEMS

    EPA Science Inventory

    Rainwater harvesting is receiving increased attention worldwide as an alternative source of drinking water. Although federal agencies such as the USEPA acknowledge the existence of rainwater collection systems, the monitoring of this water source is still typically carried out b...

  14. 76 FR 56742 - Mid-Atlantic Fishery Management Council; Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-14

    ...; Workshop AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration... Ecosystems Based Fishery Management (EBFM) issues from biological, economic and social perspectives. DATES..., including recommendations for acceptable biological catch (ABC), preventing overfishing, maximum...

  15. The biogeography of Mid-Atlantic CEAP wetlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background/Question/Methods: The national U.S.D.A. Conservation Effects Assessment Project (CEAP) is a multi-agency effort to quantify the environmental benefits of conservation practices. The goal of CEAP is to determine the effectiveness of wetland conservation practices and programs, including im...

  16. Mid-Atlantic CEAP wetland restoration – lessons learned

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the past several decades there has been considerable effort to protect and restore wetlands throughout the United States. The United States Department of Agriculture Conservation Effects Assessment Project (CEAP) is a multi-agency effort to quantify the environmental benefits of conservation pr...

  17. IPOD-USGS multichannel seismic reflection profile from Cape Hatteras to the Mid-Atlantic Ridge

    USGS Publications Warehouse

    Grow, John A.; Markl, Rudi G.

    1977-01-01

    A 3,400-km-long multichannel seismic-reflection profile from Cape Hatteras to the Mid-Atlantic Ridge was acquired commercially under contract to the National Science Foundation and the U.S. Geological Survey. These data show evidence for massive erosion of the continental slope, diapirs at the base of the continental slope, and mantle reflections beneath the Hatteras Abyssal Plain.

  18. Some results of gradient electromagnetic sounding in Doldrums Mid-Atlantic Ridge fracture

    NASA Astrophysics Data System (ADS)

    Shneyer, V. S.; Trofimov, I. L.; Abramov, Yu. M.; Zhdanov, M. S.; Machinin, V. A.; Shabelyansky, S. V.

    1991-04-01

    The geoelectrical cross-section of the Doldrums Mid-Atlantic Ridge fracture has been investigated by means of the gradient electromagnetic sounding method. The method of experiment at sea, observation techniques, principles of processing and interpretation of the observed data are described. As a result, the first model of the deep geoelectrical structure of the ridge zone, with a high conducting layer at a depth of 30 km, has been constructed.

  19. Pathways of fish invasions in the Mid-Atlantic region of the United States

    USGS Publications Warehouse

    Lapointe, Nicolas W. R.; Fuller, Pam; Neilson, Matthew; Murphy, Brian R.; Angermeier, Paul

    2016-01-01

    Non-native fish introductions are a major threat to biodiversity and fisheries, and occur through numerous pathways that vary regionally in importance. A key strategy for managing invasions is to focus prevention efforts on pathways posing the greatest risk of future introductions. We identified high-risk pathways for fish establishment in the Mid-Atlantic region of the United States based on estimates of probability of establishment and records of previous introductions, which were considered in the context of emerging socioeconomic trends. We used estimates of propagule pressure, species’ environmental tolerance, and size of species pool to assess the risk of establishment by pathway. Pathways varied considerably in historic importance and species composition, with the majority of species introduced intentionally via stocking (primarily for sport, forage, or biocontrol) or bait release. Bait release, private stocking, illegal introductions intended to establish reproducing populations (e.g., of sport fish), aquaculture, and the sale of live organisms all create risks for future invasions in the Mid-Atlantic region. Of these pathways, bait release probably poses the greatest risk of introductions for the Mid-Atlantic region because propagule pressure is moderate, most released species are tolerant of local environmental conditions, and the pool of species available for transplantation is large. Our findings differ considerably from studies in other regions (e.g., bait release is a dominant pathway in the Mid-Atlantic region, whereas illegal introduction of sport fish is dominant in the western US and aquarium releases are dominant in Florida), demonstrating the need for regional-scale assessments of, and management strategies for, introduction pathways.

  20. Feeding ecology of Coryphaenoides rupestris from the mid-Atlantic Ridge.

    PubMed

    Bergstad, Odd Aksel; Gjelsvik, Guro; Schander, Christoffer; Høines, Age S

    2010-05-03

    The Macrourid fish roundnose grenadier, Coryphaenoides rupestris, is one of the most common benthopelagic fishes on the northern mid-Atlantic Ridge. The ecology of the species is comparatively well studied in continental slope waters of the North Atlantic, but not on the mid-Atlantic Ridge, which is a central mid-ocean area of its distribution. In total, 166 specimens from the RV G.O. Sars cruise in July 2004 were examined. The diet mainly comprised cephalopods, pelagic shrimps and fish. Pelagic and benthopelagic copepods were the most numerous prey, but did not contribute much on a weight basis. Cephalopods were by far the most important prey of the small grenadiers, while shrimps and fish became increasingly significant with increasing size. Previous studies from other areas have also found pelagic prey to be important, but in contrast to this study, cephalopods were generally of less importance. The study was an element of more wide-ranging food-web studies of the mid-Atlantic Ridge macro- and megafauna communities within the international MAR-ECO project.

  1. Particulate Matter Pollution and its Regional Transport in the Mid-Atlantic States

    NASA Astrophysics Data System (ADS)

    He, H.; Goldberg, D. L.; Hembeck, L.; Canty, T. P.; Vinciguerra, T.; Ring, A.; Salawitch, R. J.; Dickerson, R. R.

    2015-12-01

    Particulate matter (PM) causes negative effects on human health, impair visibility in scenic areas, and affect regional/global climate. PM can be formed through chemical changes of precursors, including biogenic VOCs and anthropogenic SO2 and NOx often from fossil fuel combustion. In the past decades, PM pollution in the US has improved substantially. However, some areas in the Mid-Atlantic States are still designated as 'moderate' nonattainment by EPA. We utilize datasets obtained during the NASA 2011 DISCOVER-AQ campaign to characterize the composition and distribution of summertime PM pollution in the Mid-Atlantic States. Aircraft measurements and OMI satellite retrieval of major anthropogenic precursors (NO2 and SO2) are analyzed to investigate the regional transport of PM precursors from upwind sources. We compare PM concentration and chemical composition observed during the field campaign to CMAQ simulations with the latest EPA emission inventory. Specifically, we focus on the secondary organic aerosol (SOA) chemistry in CMAQ simulations using various biogenic VOCs estimates from the MEGAN and BEIS models. Airborne PM observations including PILS measurements from DISCOVER-AQ campaign and OMI retrievals of HCHO are also used to validate and improve the representation of SOA chemistry and PM pollution within CMAQ. The comparison reveals the source and evolution of PM pollution in the Mid-Atlantic States.

  2. Does the mid-Atlantic United States sea level acceleration hot spot reflect ocean dynamic variability?

    NASA Astrophysics Data System (ADS)

    Kopp, Robert E.

    2013-08-01

    To test a hypothesized faster-than-global sea level acceleration along the mid-Atlantic United States, I construct a Gaussian process model that decomposes tide gauge data into short-term variability and longer-term trends, and into globally coherent, regionally coherent, and local components. While tide gauge records indicate a faster-than-global increase in the rate of mid-Atlantic U.S. sea level rise beginning ˜1975, this acceleration could reflect either the start of a long-term trend or ocean dynamic variability. The acceleration will need to continue for ˜2 decades before the rate of increase of the sea level difference between the mid-Atlantic and southeastern U.S. can be judged as very likely unprecedented by 20th century standards. However, the difference is correlated with the Atlantic Multidecadal Oscillation, North Atlantic Oscillation, and Gulf Stream North Wall indices, all of which are currently within the range of past variability.

  3. Development of an Extratropical Storm Wind, Wave, and Water Level Climatology for the Offshore Mid-Atlantic

    DTIC Science & Technology

    2015-08-01

    ER D C/ CH L TR -1 5- 11 Development of an Extratropical Storm Wind, Wave, and Water Level Climatology for the Offshore Mid-Atlantic...challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the...Development of an Extratropical Storm Wind, Wave, and Water Level Climatology for the Offshore Mid-Atlantic Michael F. Forte Field Research Facility

  4. USEPA/WSWRD MEMBRANE RESEARCH

    EPA Science Inventory

    The USEPA has been very active in membrane research. The following areas are currently being investigated: in-house fouling research, Information Collection Rule (ICR) treatment studies, inorganic scaling modeling, Environmental Technology Verification (ETV) program implementati...

  5. USEPA WATERSHED APPROACH

    EPA Science Inventory

    The U.S. Environmental Protection Agency's Office of Research and Development has developed a well defined research plan to evaluate pollutants within watersheds. This plan is defined by long term goals and annual performance measures. The first goal is to provide the approache...

  6. Carlsberg Ridge and Mid-Atlantic Ridge: Comparison of slow spreading centre analogues

    NASA Astrophysics Data System (ADS)

    Murton, Bramley J.; Rona, Peter A.

    2015-11-01

    Eighty per cent of all mid-ocean spreading centres are slow. Using a mixture of global bathymetry data and ship-board multibeam echosounder data, we explore the morphology of global mid-ocean ridges and compare two slow spreading analogues: the Carlsberg Ridge in the north-west Indian Ocean between 57°E and 60°E, and the Kane to Atlantis super-segment of the Mid-Atlantic Ridge between 21°N and 31°N. At a global scale, mid-ocean spreading centres show an inverse correlation between segment length and spreading rate with segmentation frequency. Within this context, both the Mid-Atlantic Ridge super-segment and Carlsberg Ridge are similar: spreading at 22 and 26 mm/yr full rates respectively, being devoid of major transform faults, and being segmented by dextral, non-transform, second-order discontinuities. For these and other slow spreading ridges, we show that segmentation frequency varies inversely with flank height and ridge axis depth. Segments on both the Mid-Atlantic Ridge super-segment and Carlsberg Ridge range in aspect ratio (ridge flank height/axis width), depth and symmetry. Segments with high aspect ratios and deeper axial floors often have asymmetric rift flanks and are associated with indicators of lower degrees of melt flux. Segments with low aspect ratios have shallower axial floors, symmetric rift flanks, and evidence of robust melt supply. The relationship between segmentation, spreading rate, ridge depth and morphology, at both a global and local scale, is evidence that rates of melting of the underlying mantle and melt delivery to the crust play a significant role in determining the structure and morphology of slow spreading mid-ocean ridges.

  7. Intense mixing of lower thermocline water on the crest of the Mid-Atlantic Ridge.

    PubMed

    St Laurent, Louis C; Thurnherr, Andreas M

    2007-08-09

    Buoyancy exchange between the deep and the upper ocean, which is essential for maintaining global ocean circulation, mainly occurs through turbulent mixing. This mixing is thought to result primarily from instability of the oceanic internal wave field, but internal waves tend to radiate energy away from the regions in which they are generated rather than dissipate it locally as turbulence and the resulting distribution of turbulent mixing remains unknown. Another, more direct, mixing mechanism involves the generation of turbulence as strong flows pass through narrow passages in topography, but the amount of turbulence generated at such locations remains poorly quantified owing to a lack of direct measurements. Here we present observations from the crest of the Mid-Atlantic Ridge in the subtropical North Atlantic Ocean that suggest that passages in rift valleys and ridge-flank canyons provide the most energetic sites for oceanic turbulence. Our measurements show that diffusivities as large as 0.03 m2 s(-1) characterize the mixing downstream of a sill in a well-stratified boundary layer, with mixing levels remaining of the order of 10(-4) m2 s(-1) at the base of the main thermocline. These mixing rates are significantly higher than the diffusivities of the order of 10(-5) m2 s(-1) that characterize much of the global thermocline and the abyssal ocean. Our estimates suggest that overflows associated with narrow passages on the Mid-Atlantic Ridge in the North Atlantic Ocean produce as much buoyancy flux as has previously been estimated for the entire Romanche fracture zone, a large strait in the Mid-Atlantic Ridge that connects the North and South Atlantic basins. This flux is equivalent to the interior mixing that occurs in the entire North Atlantic basin at the depth of the passages, suggesting that turbulence generated in narrow passages on mid-ocean ridges may be important for buoyancy flux at the global scale.

  8. Recycling of construction debris as aggregate in the Mid-Atlantic Region, USA

    USGS Publications Warehouse

    Robinson, G.R.; Menzie, W.D.; Hyun, H.

    2004-01-01

    Reclaimed asphalt pavement (RAP) and portland cement concrete (RPCC) are abundant and available substitutes for natural aggregate in many areas. This paper presents an overview of factors that affect recycled aggregate cost, availability, and engineering performance, and the results of a survey of business practices in the Mid-Atlantic region. For RAP, processing costs are less than those for virgin natural aggregate. Use of efficient asphalt pavement stripping technology, on-site reclamation, and linked two-way transport of asphalt debris and processed asphalt paving mix between asphalt mix plants and paving sites has led to extensive recycling of asphalt pavement in the Mid-Atlantic region of the US. Most of the sites that recycle asphalt pavement (RAP) are located in or near urban areas close to important transportation corridors. RPCC is a viable aggregate source in urban settings where unit costs for processed aggregate from RPCC and natural aggregate are comparable. Disposal fees charged at RPCC recycling sites help defray processing costs and the significantly lower tipping fees at recycling sites versus landfill disposal sites encourage recycling of construction debris as aggregate. Construction contractors and construction debris recycling centers, many of which have the ability to crush and process concrete debris at the job site, produce most RPCC. Production of RPCC aggregate from construction debris that is processed on site using portable equipment moved to the construction site eliminates transportation costs for aggregate and provides an economic incentive for RPCC use. Processing costs, quality and performance issues, and lack of large quantities where needed limit RPCC use. Most RPCC suppliers in the Mid-Atlantic area are located in counties with population densities greater than 400 people/km2 (1036 people/mile2) and that have high unit-value costs and limited local availability of natural aggregate. ?? 2004 Published by Elsevier B.V.

  9. Potential Economic Impacts from Offshore Wind in the Mid-Atlantic Region (Fact Sheet)

    SciTech Connect

    Keyser, D.; Tegen, S.; Flores, F.; Zammit, D.; Kraemer, M.; Miles, J.

    2014-01-01

    Offshore wind is a clean, renewable source of energy and can be an economic driver in the United States. To better understand the employment opportunities and other potential regional economic impacts from offshore wind development, the U.S. Department of Energy (DOE) funded research that focuses on four regions of the country. The studies use multiple scenarios with various local job and domestic manufacturing content assumptions. Each regional study uses the new offshore wind Jobs and Economic Development Impacts (JEDI) model, developed by the National Renewable Energy Laboratory. This fact sheet summarizes the potential economic impacts for the Mid-Atlantic region.

  10. A new species of Nidalia Gray, 1835 from Mid-Atlantic seamounts (Octocorallia, Alcyonacea, Nidaliidae)

    NASA Astrophysics Data System (ADS)

    López-González, Pablo J.; Gili, Josep-Maria

    2008-12-01

    A new soft coral species of the genus Nidalia, from seamounts to the south of the Azores Archipelago is described. The main features of Nidalia aurantia n. sp. are as following: colony torch-like, a capitulum light orange in colour, not laterally flattened, dome-shaped and not distinctly projecting beyond the stalk, an introvert with sparse sclerites transversally placed, and an anthocodial crown with 13 17 sclerite rows. The new species is compared with its closest congeners. This is the first time that a species of Nidalia has been located in the Mid-Atlantic Ocean.

  11. Nitrate retention as it affects groundwater pollution in Mid-Atlantic soils. Completion report

    SciTech Connect

    Sparks, D.L.

    1987-09-14

    Nitrate retention (NO/sub 3/) as it affects groundwater pollution was investigated on nine major Mid-Atlantic soil types. Objectives of the study were to determine the magnitude and rate of NO/sub 3/ retention and the effect of anion competition on NO/sub 3/ retention. The soils had a wide range in organic matter, clay and oxide content. Charge properties including anion exchange capacity (AEC) and point of zero salt effect (PZSE) were determined. The PZSE values were low indicating little anion-adsorption capacity, while AEC values often significant and increased with profile depth as oxide and clay contents increased.

  12. Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). Spot

    DTIC Science & Technology

    1989-02-01

    1978. Development of the northwestern Gulf of Mexico (May fishes in the Mid-Atlantic Bight. 1985). M.S. Thesis. Texas A&M Vol. IV. Carangidae through... Laguna Madre , a hypersaline estuary. Pages 383-389 Joseph, E.B. 1972. The status of in G. H. Lauff, ed. Estuaries, the sciaenid stocks of the Middle...Fisheries, other commercial sciaenids of the Morehead City, N.C. 80 pp. Texas Gulf. Bull. U.S. Bur. Fish . 44:129-214. Stickney, R.R., and M.L. Cuenco

  13. Earthquake swarms on the Mid-Atlantic Ridge - Products of magmatism or extensional tectonics?

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1990-01-01

    The spatial and temporal patterns and other characteristics of earthquakes in 34 earthquake swarms on the Mid-Atlantic Ridge were compared with those of well-studied earthquake swarms which accompany terrestrial volcanic eruptions, to test the assumption that the teleseismically observed earthquake swarms along mid-ocean ridges are indicators of volcanism. Improved resolution of these patterns for the mid-ocean ridge events was achieved by a multiple-event relocation technique. It was found that the teleseismically located earthquake swarms on the mid-ocean ridge system have few features in common with swarms directly associated with active magmatism in terrestrial volcanic rift zones such as Hawaii and Iceland. While the possibility that some of the mid-ocean earthquake swarms might be directly associated with a current episode of eruptive activity on the Mid-Atlantic Ridge cannot be excluded, none of the 34 swarms studied in this work was found to be a conspicuously attractive candidate for such a role.

  14. Sprecies profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic): Bluefish

    SciTech Connect

    Pottern, G.B.; Huish, M.T.; Kerby, J.H. )

    1989-02-01

    Species profiles are literature summaries of the taxonomy, morphology, distribution, life history, and environmental requirements of coastal fishes and invertebrates within a specified range. They are written to assist in environmental impact assessment and decision making by coastal planners and developers. Bluefish are the most important recreational fish in the United States, especially in the mid-Atlantic region. The commercial catch is smaller but has increased during recent years. One population spawns offshore during spring from northern Florida to North Carolina, and these young migrate into mid-Atlantic coastal waters to spend their summer and fall. A second population spawns offshore during summer from North Carolina to Massachusetts, but most of these young remain offshore for the remainder of the season. In late fall, young and adults of both populations migrate south until the following spring. Bluefish are migratory, opportunistic, pelagic predators throughout life, and their seasonal abundance may have profound community structuring effects. Schools of juvenile bluefish may be important forage for many pelagic predators, including adults of their own species. Photoperiod apparently triggers long-range migration, and temperature serves as a proximal cue to short-range migration. Bluefish are sensitive to bacterial infection in polluted water and have little tolerance for low oxygen conditions. 55 refs., 6 figs., 3 tabs.

  15. Satellite detection of phytoplankton export from the mid-Atlantic Bight during the 1979 spring bloom

    NASA Technical Reports Server (NTRS)

    Walsh, J. J.; Dieterle, D. A.; Esaias, W. E.

    1986-01-01

    Analysis of Coastal Zone Color Scanner (CZCS) imagery confirms shipboard and in situ moored fluorometer observations of resuspension of near-bottom chlorophyll within surface waters (1 to 10 m) by northwesterly wind events in the mid-Atlantic Bight. As much as 8 to 16 micrograms chl/l are found during these wind events from March to May, with a seasonal increase of algal biomass until onset of stratification of the water column. Rapid sinking or downwelling apparently occurs after subsequent wind events, however, such that the predominant surface chlorophyll pattern is approx. 0.5 to 1.5 micrograms/l over the continental shelf during most of the spring bloom. Perhaps half of the chlorophyll increase observed by satellite during a wind resuspension event represents in-situ production during the 4 to 5 day interval, with the remainder attributed to accumulation of algal biomass previously produced and temporarily stored within near-bottom water. Present calculations suggest that about 10% of the primary production of the spring bloom may be exported as ungrazed phytoplankton carbon from mid-Atlantic shelf waters to those of the continental slope.

  16. Nematocarcinus Milne Edwards, 1881 (Crustacea, Decapoda) from Southwestern Atlantic, including the Southern Mid-Atlantic Ridge area.

    PubMed

    Cardoso, Irene A; Burukovsky, Rudolf N

    2014-11-26

    The deep sea shrimp genus Nematocarcinus Milne Edwards, 1881 includes 47 species, ten of them have been recorded from the Atlantic Ocean. Herein, material sampled during three scientific projects (REVIZEE Central Fishery project; Campos Basin Deep Sea Environmental Project; Evaluation of Environmental Heterogeneity in the Campos Basin) made in the Southwestern Atlantic, off Brazil, is examined. In addition, material sampled from the South Mid Atlantic Ridge (MAR-ECO Project) was also examined. Four species are recorded for the first time to the southwestern Atlantic Ocean including Mid Atlantic Ridge area: Nematocarcinus faxoni Burukovsky, 2001; N. gracilipes Filhol, 1884; N. rotundus Crosnier & Forest, 1973 and N. tenuipes Spence-Bate, 1888.

  17. Temporal and directional patterns of nymphal Halyomorpha halys (Hemiptera: Pentatomidae) movement on the trunk of selected wild and fruit tree hosts in the Mid-Atlantic

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Halyomorpha halys (Stal) (Hemiptera: Pentatomidae) is an invasive and polyphagous herbivore that has been problematic in Mid-Atlantic fruit orchards, many of which are adjacent to woodlands containing its wild hosts. Our tree census in woodlands bordering 15 Mid-Atlantic apple orchards revealed 47 ...

  18. TESTING LANDSCAPE INDICATORS FOR STREAM CONDITION RELATED TO PESTICIDES AND NUTRIENTS: LANDSCAPE INDICATORS FOR PESTICIDES STUDY FOR MID-ATLANTIC COASTAL STREAMS (LIPS-MACS)

    EPA Science Inventory

    This research plan for the Landscape Indicators for Pesticides Study ? Mid-Atlantic Coastal Streams (LIPS-MACS) describes the rational and approach of developing a research project to evaluate statistical landscape indicator models for freshwater streams in the Mid-Atlantic Coas...

  19. MEASURING BASE-FLOW CHEMISTRY AS AN INDICATOR OF REGIONAL GROUND-WATER QUALITY IN THE MID-ATLANTIC COASTAL PLAIN

    EPA Science Inventory

    Water quality in headwater (first-order) streams of the Mid-Atlantic Coastal Plain during base flow in the winter and spring is related to land use, hydrogeology, and other natural and human influences. A random survey of water quality in 174 headwater streams in the Mid-Atlantic...

  20. A chemical climatology of lower tropospheric trace gases and aerosols over the mid-Atlantic region

    NASA Astrophysics Data System (ADS)

    Hains, Jennifer Carrie

    2007-12-01

    Ozone and aerosols affect air quality, visibility and human health. The University of Maryland research aircraft conducted flights over the Mid-Atlantic region between 1995 and 2005 to characterize pollution events. I developed a chemical climatology of trace gases and aerosols that can be used to validate and improve models. O3 and SO2 measured aboard the aircraft were compared with O3 and SO2 generated with the Community Multiscale Air Quality (CMAQ). In general, CMAQ under-estimates O3 above 500 m and over-estimates O3 below 500 m (possible reasons for this include chemistry not being properly represented in the model). A sensitivity test of the rate of photolysis of NO2 was performed and improving the photochemistry did improve the modeled O3. CMAQ over-predicts the SO2 column content by about 50%, possibly because the model gives SO2 too long a lifetime. To test this theory I developed a method for calculating the SO2 lifetime using in-situ measurements. The mean SO2 lifetime was 19 +/- 7 hours for measurements made in the daytime in the summer in the Mid-Atlantic region with in-cloud processes responsible for ˜80% of the removal. I made comparisons of three aerosol sampling systems and found the uncertainty of PM2.5, sulfate, and ammonium measured with the Speciation Trends Network is larger than what has been reported and is at least 20%. I have developed clustering methodologies to group back trajectories associated with aircraft profiles as well as group trace gas and aerosol profiles by size and shape. The first clustering method produced eight distinct meteorological regimes associated with pollution and haze events. I quantified the amount of O3 transported for each meteorological regime. Using the second method, I found a strong correlation between O3 profiles and point source NOx emissions. The comparisons of model and measured profiles, comparisons of surface measurements, and clustering methods are used to explain sources, sinks and distributions

  1. USEPA R&D Facility Open to Private Clients

    EPA Science Inventory

    The U.S. Environmental Protection Agency (U.S.EPA) landmark Safe Drinking Water Act Amendments of 1996 promised to provide safe drinking water to all Americans. Since that time many have not understood EPA involvement in the evaluation of drinking water technologies. To support a...

  2. Fuzzy decision analysis for integrated environmental vulnerability assessment of the mid-Atlantic Region.

    PubMed

    Tran, Liem T; Knight, C Gregory; O'Neill, Robert V; Smith, Elizabeth R; Riitters, Kurt H; Wickham, James

    2002-06-01

    A fuzzy decision analysis method for integrating ecological indicators was developed. This was a combination of a fuzzy ranking method and the analytic hierarchy process (AHP). The method was capable of ranking ecosystems in terms of environmental conditions and suggesting cumulative impacts across a large region. Using data on land cover, population, roads, streams, air pollution, and topography of the Mid-Atlantic region, we were able to point out areas that were in relatively poor condition and/or vulnerable to future deterioration. The method offered an easy and comprehensive way to combine the strengths of fuzzy set theory and the AHP for ecological assessment. Furthermore, the suggested method can serve as a building block for the evaluation of environmental policies.

  3. PaTH: towards a learning health system in the Mid-Atlantic region

    PubMed Central

    Amin, Waqas; Tsui, Fuchiang (Rich); Borromeo, Charles; Chuang, Cynthia H; Espino, Jeremy U; Ford, Daniel; Hwang, Wenke; Kapoor, Wishwa; Lehmann, Harold; Martich, G Daniel; Morton, Sally; Paranjape, Anuradha; Shirey, William; Sorensen, Aaron; Becich, Michael J; Hess, Rachel

    2014-01-01

    The PaTH (University of Pittsburgh/UPMC, Penn State College of Medicine, Temple University Hospital, and Johns Hopkins University) clinical data research network initiative is a collaborative effort among four academic health centers in the Mid-Atlantic region. PaTH will provide robust infrastructure to conduct research, explore clinical outcomes, link with biospecimens, and improve methods for sharing and analyzing data across our diverse populations. Our disease foci are idiopathic pulmonary fibrosis, atrial fibrillation, and obesity. The four network sites have extensive experience in using data from electronic health records and have devised robust methods for patient outreach and recruitment. The network will adopt best practices by using the open-source data-sharing tool, Informatics for Integrating Biology and the Bedside (i2b2), at each site to enhance data sharing using centrally defined common data elements, and will use the Shared Health Research Information Network (SHRINE) for distributed queries across the network. PMID:24821745

  4. Past permafrost on the Mid-Atlantic coastal plain, eastern United States

    USGS Publications Warehouse

    French, H.; Demitroff, M.; Newell, W.L.

    2009-01-01

    Sand-wedge casts, soil wedges and other non-diastrophic, post-depositional sedimentary structures suggest that Late-Pleistocene permafrost and deep seasonal frost on the Mid-Atlantic Coastal Plain extended at least as far south as southern Delaware, the Eastern Shore and southern Maryland. Heterogeneous cold-climate slope deposits mantle lower valley-side slopes in central Maryland. A widespread pre-existing fragipan is congruent with the inferred palaeo-permafrost table. The high bulk density of the fragipan was probably enhanced by either thaw consolidation when icy permafrost degraded at the active layer-permafrost interface or by liquefaction and compaction when deep seasonal frost thawed. ?? 2009 John Wiley & Sons, Ltd.

  5. The stratigraphic record of recent climate change in mid-Atlantic USA

    SciTech Connect

    Brush, G.S.; Hilgartner, W.B.; Khan, H. )

    1994-06-01

    The Medieval Warm Period and Little Ice Age recorded in sediments deposited in tributaries and marshes surrounding the Chesapeake and Delaware Bays in the mid-Atlantic region of USA, by changes in pollen and seeds of terrestrial and aquatic plants, and changes in influxes of charcoal, sediment, metals and nutrients. Fossil pollen and seeds portray a regional landscape characterized by conditions drier that present from about 1000 to 1200 AD. During the same period, high charcoal and sediment influxes indicate high fire frequency. This short dry interval was followed by an expansion of submerged aquatic plants, low marsh plants, and terrestrial plants that occupy wet habitats. Charcoal influxes are extremely low during the latter interval, which extended from about 1200 AD to 1500 AD. Plant macrofossil and pollen distributions indicate a second dry period extending from 1550 to 1650 AD, which appears similar to the earlier Medieval Warm interval.

  6. The influence of surface waves on water circulation in a mid-Atlantic continental shelf region

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Talay, T. A.

    1974-01-01

    The importance of wave-induced currents in different weather conditions and water depths (18.3 m and 36.6 m) is assessed in a mid-Atlantic continental-shelf region. A review of general circulation conditions is conducted. Factors which perturb the general circulation are examined using analytic techniques and limited experimental data. Actual wind and wave statistics for the region are examined. Relative magnitudes of the various currents are compared on a frequency of annual occurrence basis. Results indicated that wave-induced currents are often the same order of magnitude as other currents in the region and become more important at higher wind and wave conditions. Wind-wave and ocean-swell characteristics are among those parameters which must be monitored for the analytical computation of continental-shelf circulation.

  7. Sisterhood Surveyed. Proceedings of the Mid-Atlantic Women's Studies Association Conference (West Chester, Pennsylvania, October 1-2, 1982).

    ERIC Educational Resources Information Center

    Sessa, Anne Dzamba, Ed.

    Proceedings of the 1982 conference of the Mid-Atlantic Women's Studies Association are presented. Synopses of sessions include the following topics: iconography of sisterhood, matriarchy, ethnic and cultural critiques, political perspectives, and nontraditional women students. Conference papers and authors are as follows: "Friends for Half a…

  8. Educator Effectiveness Series: Assessing School Climate. Q&A with Jonathan Cohen, Ph.D. REL Mid-Atlantic Webinar

    ERIC Educational Resources Information Center

    Cohen, Jonathan

    2015-01-01

    The REL Mid-Atlantic Webinar discussed the elements in a positive school climate and shared different methods for assessing school data, including the Comprehensive School Climate Inventory. The Q&A presented in this document address the questions participants had for Dr. Cohen following the webinar. The webinar recording and PowerPoint…

  9. INDICATORS OF CHANGE IN THE MID-ATLANTIC WATERSHEDS AND CONSEQUENCES OF CLIMATE IN UPPER CHESAPEAKE BAY

    EPA Science Inventory

    The rate of change in Northern Hemisphere atmospheric temperature in the past century relative to the preceding millennium strongly suggests that we are in a period of rapid global climate change. The mid-Atlantic region is quite sensitive to larger scale climate variation, which...

  10. HISTORICAL CHANGES IN GLOBAL SCALE CIRCULATION PATTERNS, MID-ATLANTIC CLIMATE STREAM FLOW AND NUTRIENT FLUXES TO THE CHESAPEAKE BAY

    EPA Science Inventory

    The rate of change in Northern Hemisphere temperature in the past century strongly suggests that we are now in a period of rapid global climate change. Also, the climate in the mid-Atlantic is quite sensitive to larger scale climate variation, which affects the frequency and seve...

  11. THE RELATIONSHIP BETWEEN STREAM CHEMISTRY AND WATERSHED LAND COVER DATA IN THE MID-ATLANTIC REGION, U.S.

    EPA Science Inventory

    In order to investigate the relationship between stream chemistry and watershed land cover at the regional scale, we analyzed data from 368 wadeable streams sampled in the mid-Atlantic region of the U.S. during spring 1993-1994. Study sites were selected using a probability sampl...

  12. Conservation program and practice effects on ecosystem services in the mid atlantic region of the U.S

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The U.S. Department of Agriculture (USDA) Mid-Atlantic Regional (MIAR) Wetland Conservation Effects Assessment Project (CEAP-Wetland) study area covers approximately ~58,000 km2 in the eastern United States, including areas of within five states (North Carolina, Virginia, Maryland, Delaware, and New...

  13. DESIGN AND APPLICATION OF A STRATIFIED UNEQUAL-PROBABILITY STREAM SURVEY IN THE MID-ATLANTIC COASTAL PLAIN

    EPA Science Inventory

    A stratified random sample with unequal probability selection within strata was used to design a multipurpose survey of headwater watersheds in the Mid-Atlantic Coastal Plain. Objectives for data from the survey include unbiased estimates of regional headwater watershed condition...

  14. Bathypelagic Food Web Structure of the Northern Atlantic Mid-Atlantic Ridge Based on Stable Isotope Analysis

    EPA Science Inventory

    The objective of our study was to characterize the trophic connections of the dominant fishes of the deep-pelagic region of the northern Mid-Atlantic Ridge (MAR) with respect to vertical distribution using carbon (C) and nitrogen (N) stable isotope analysis. Our goals were to id...

  15. 75 FR 353 - AES Sparrows Point LNG, LLC and Mid-Atlantic Express, LLC; Notice of Availability of the Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-05

    ... Final General Conformity Determination for Maryland for the Proposed Sparrows Point LNG Terminal and...) import terminal and natural gas pipeline proposed by AES Sparrows Point LNG, LLC and Mid-Atlantic Express... following LNG terminal and natural gas pipeline facilities: A ship unloading facility, with two...

  16. Spatial distribution of brown marmorated stink bug (Hemiptera: Pentatomidae) injury at harvest in mid-Atlantic apple orchards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Brown marmorated stink bug's, Halyomorpha halys (Stal), injury to late-season apple cultivars was measured at harvest in 2011 and 2012 in commercial orchards in four mid-Atlantic states. In each orchard block, a border zone (adjacent to woods), an interior zone (near orchard center), and an interme...

  17. Appendix A of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    SciTech Connect

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the first appendix to the report, the workshop agenda.

  18. DETERMINING BACKGROUND EXPOSURE TO PETROLEUM AND COMBUSTION BY-PRODUCTS: COMPARISON OF MID-WESTERN AND MID-ATLANTIC REGIONS

    EPA Science Inventory

    Regional background levels of exposure to fish from petroleum and combustion by-products were determined for the state of Ohio and the mid-Atlantic region. Exposures were measured using bile metabolites that fluoresce at 290/335 nm for naphthalene(NAPH)-type compounds and at 380...

  19. Appendix E of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    SciTech Connect

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the fifth appendix to the report, the bibliography of references.

  20. COMPARISON OF MID-WESTERN AND MID-ATLANTIC REGIONS EXPOSURE CRITERIA FOR PETROLEUM AND COMBUSTION BY-PRODUCTS

    EPA Science Inventory

    Regional background levels of exposure to fish from petroleum and combustion by-products were determined for the state of Ohio (mid-Western) and the mid-Atlantic region. Exposures were measured using bile metabolites that fluoresce at 290/335 nm for naphthalene (NAPH)-type compou...

  1. Appendix C of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    SciTech Connect

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the third appendix to the report, the compendium of pre-workshop answers.

  2. DEVELOPMENT OF A MID-ATLANTIC LAND USE/ LAND COVER CHANGE DATA SET (1970S TO 1990S)

    EPA Science Inventory

    The Mid-Atlantic region (MAIA) is comprised of southern New York, southern and western New Jersey, Pennsylvania, West Virginia, Maryland, Virginia, northeastern North Carolina, Delaware, and Washington, D.C. in the lower-48 American States. It is an ecosystem rich in streams, wet...

  3. Brown Marmorated Stink Bug in the Mid-Atlantic States: Assessing Grower Perceptions, Economic Impact, and Progress

    ERIC Educational Resources Information Center

    Dellinger, Theresa A.; Day, Eric R.; Pfeiffer, Douglas G.

    2016-01-01

    Attendees at mid-Atlantic grower meetings were surveyed in 2012 and 2014 regarding their knowledge of the invasive brown marmorated stink bug (BMSB) and its impact. Responses to individual questions were paired and analyzed for independence between survey years. Despite a large-scale effort by Extension to inform growers and others about BMSB,…

  4. Further Geological Sampling Around the Rainbow Hydrothermal Site, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Ildefonse, B.; Andréani, M.; Hoisé, E.; Ballu, V.; Escartin, J.; Dyment, J.; Gaill, F.; Fouquet, Y.

    2007-12-01

    The Rainbow hydrothermal site, at 36°14'N on the Mid-Atlantic Ridge, is one of the few known site hosted in ultramafic basement. The MOMAR DREAM cruise (July 2007, R/V Pourquoi Pas ?) combined biological and geological objectives to study the role of abundant iron in controlling geological, biological and hydrological active processes at all scales. Two Nautile dives and a dredging program were achieved to further constrain the lithology and geological structures on the seafloor at the scale of the massif that hosts Rainbow. This massif is an inside corner high of the non-transform offset between the AMAR and South AMAR second-order ridge segments, and presents the characteristic dome morphology of oceanic core complexes. The abundant sediment cover of the massif precludes continuous geological mapping and completely successful dredging. However, our limited sampling is consistent with the lithological variability encountered in other oceanic core complexes along the Mid-Atlantic Ridge. The Rainbow serpentinite basement was continuously observed to a distance of about 1 km to the south of the hydrothermal site, with serpentinites sampled along N-S trending, fault planes steeply dipping to the West. Serpentinites were also found on the northwestern, northern, and northeastern flanks of the massif. Approximately 800 m the North of the hydrothermal site, the most prominent outcrop, cut by a family of subvertical, ~ E-W faults, is at least partly made of olivine- orthopyroxene bearing gabbro. Basalts and fresh basaltic glass were also recovered in talus and sediments on the Southwest and Northeast flanks of the massif.

  5. Carbon in Natural, Cultivated, and Restored Depressional Wetlands in the Mid-Atlantic Coastal Plain.

    PubMed

    Fenstermacher, D E; Rabenhorst, M C; Lang, M W; McCarty, G W; Needelman, B A

    2016-03-01

    Aerial extent of wetland ecosystems has decreased dramatically since precolonial times due to the conversion of these areas for human use. Wetlands provide various ecosystem services, and conservation efforts are being made to restore wetlands and their functions, including soil carbon storage. This Mid-Atlantic Regional USDA Wetland Conservation Effects Assessment Project study was conducted to evaluate the effects and effectiveness of wetland conservation practices along the Mid-Atlantic Coastal Plain. This study examined 48 wetland sites in Delaware, Maryland, Virginia, and North Carolina under natural, prior converted cropland, and 5- to 10-yr post wetland restoration states. The North Carolina sites mainly contained soils dominated by organic soil materials and therefore were analyzed separately from the rest of the sites, which primarily contained mineral soils. Soil samples were collected using the bulk density core method by horizon to a depth of 1 m and were analyzed for percent carbon. The natural wetlands were found to have significantly greater carbon stocks (21.5 ± 5.2 kg C m) than prior converted croplands (7.95 ± 1.93 kg C m; < 0.01) and restored wetlands (4.82 ± 1.13 kg C m; < 0.001). The restored and prior converted sites did not differ significantly, possibly the result of the methods used to restore the wetlands, and the relatively young age of the restored sites. Wetlands were either restored by plugging drainage structures, with minimal surface disturbance, or by scraping the surface (i.e., excavation) to increase hydroperiod. Sites restored with the scraping technique had significantly lower carbon stocks (2.70 ± 0.38 kg C m) than those restored by passive techniques (6.06 ± 1.50 kg C m; = 0.09). Therefore, techniques that involve excavation and scraping to restore hydrology appear to negatively affect C storage.

  6. Biologic Indicators of Seabed Methane Venting Along the US Mid-Atlantic Margin

    NASA Astrophysics Data System (ADS)

    Prouty, N.; Roark, E. B.; Demopoulos, A. W.; Condon, D. J.; Davis, K.; Ross, S.; Brooke, S.

    2014-12-01

    Evidence of seabed methane venting along the US Mid-Atlantic Margin is confirmed by the presence of authigenic carbonates and methantrophic deep-sea mussels, Bathymodiolus childressi, collected near areas of methane seepage. The biological indicators of methane venting presented here expand the understanding of widespread seepage identified by previous geophysical data. Both dead and living chemosynthetic mussels as well as authigenic carbonate samples were collected from Baltimore Canyon (360-430 m) and on the Virginia outer continental shelf (1600-1475 m). Stable isotope (carbon and sulfur) composition of mussel tissue material illustrates that the chemosynthetic communities are metabolically-dependent on methane rather than sulphide-oxidizing microbial symbionts. Average δ13C from tissue material was -62.80 ‰ and average δ34S was 12.58 ‰. Shell δ13C values were depleted relative to seawater dissolved inorganic carbon, highlighting the influence of methane concentration from cold seeps on shell growth. Lighter stable oxygen isotope values from shells collected at Baltimore Canyon reflect warmer temperatures relative to the colder and deeper Virginia seep site. However, at both sites isotopic disequilibrium relative to seawater δ18O suggests influence of enriched δ18O pore water. The chemical composition of the authigenic carbonates at both sites is dominated by aragonite rather than calcite, with an average δ13C signature of -46 ‰, a value expected from the microbially driven anaerobic oxidation of methane-rich fluids occurring at or near the sediment-water interface. This interpretation is supported by strontium isotope values close to modern seawater values. U/Th data are also reported from the authigenic carbonate stratigraphy to assess the timing and duration of methane venting along the US Mid-Atlantic Margin.

  7. Variation in physicochemical responses to urbanization in streams between two Mid-Atlantic physiographic regions.

    PubMed

    Utz, Ryan M; Eshleman, Keith N; Hilderbrand, Robert H

    2011-03-01

    Urban development substantially alters the physicochemistry of streams, resulting in biodiversity and ecosystem function loss. However, interregional comparisons of physicochemical impact in urban streams suggest that geoclimatic heterogeneity may influence the extent of degradation. In the Mid-Atlantic United States, the adjacent Coastal Plain and Piedmont physiographic provinces possess distinctly different hydrogeomorphic properties that may influence how stream ecosystems respond to urbanization. Recent bioassessments have demonstrated that biotic sensitivity to urbanization is relatively acute in the Piedmont, suggesting that physicochemical change as a consequence of urbanization may be greater in that province. We compared hydrologic, chemical, and thermal characteristics of Mid-Atlantic Coastal Plain and Piedmont first- through fifth-order streams along gradients of impervious surface cover (ISC) at multiple spatial scales. Linear models were applied to test if conditions in rural streams and the degree of impact from ISC varied between provinces. Mean and maximum summer temperatures in Piedmont streams increased more per unit of ISC than in the Coastal Plain. Contrary to expectations, however, variables that quantified high-flow event frequency, magnitude and duration, exhibited significantly greater impact along the ISC gradient in the Coastal Plain. Most chemical changes associated with increasing ISC were similar in the two provinces, although the interregional chemical composition of rural streams differed substantially for most parameters. Our findings demonstrate consistent interregional heterogeneity in stream ecosystem responses to urbanization. Landscape-scale management decisions with stream ecosystem conservation, mitigation, or restoration as a goal must therefore carefully consider the geoclimatic context in order to maximize effectiveness.

  8. A set of scientific issues being considered by the Environmental Protection Agency regarding: pesticide exposure modeling and climate change. SAP Minutes No. 2011-01. USEPA FIFRA Scientific Advisory Panel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USEPA Office of Pesticide Programs (OPP) reviewed most of its human and ecological exposure assessment models for conventional pesticides to evaluate which inputs and parameters may be affected by changing climate conditions. To illustrate the approach used for considering potential effects of c...

  9. Conceptual ecological model for management of breeding grassland birds in the Mid-Atlantic Region

    USGS Publications Warehouse

    Peterjohn, Bruce G.

    2006-01-01

    The status of grassland birds has become an increasingly important conservation issue. These species exhibit the most consistent population declines of any group of North American birds during the past 40 years. Anecdotal evidence suggests these declines have been occurring for nearly a century (Peterjohn and Sauer 1999). While the widespread conversion of grasslands into other habitats contributed to these declining populations, other factors such as habitat fragmentation and mowing regimes are also implicated (Vickery et al. 1999a). This plight of grassland birds has heightened awareness of the need for concerted conservation actions to reverse these seriously declining population trends. The National Park Service (NPS) is positioned to potentially contribute to grassland bird conservation in the Mid-Atlantic Region. The NPS maintains a number of historic sites and former battlefields that are managed for their cultural significance but also support wildlife populations. Many of these “cultural parks” maintain open landscapes to recreate land use patterns that existed at the times of the historical events. These open landscapes are primarily managed grasslands which could be maintained to benefit grassland birds. In 2005, the NPS initiated a project exploring the potential of “cultural parks” to support significant breeding grassland bird communities. This project involved parks within three NPS Inventory and Monitoring Program (I&M) networks, Mid-Atlantic, National Capital, and Eastern Rivers and Mountains. Five parks were selected for the initial focus of this study, all of which maintain open landscapes for interpretation of historic events. Most parks were selected because they represent the most extensive grassland habitats within their networks, with the rationale that if these parks cannot support significant breeding grassland bird communities, then parks with smaller acreages cannot support these communities either. The five parks included in

  10. Conceptual ecological model for management of breeding shrubland birds in the Mid-Atlantic Region

    USGS Publications Warehouse

    Peterjohn, Bruce G.

    2006-01-01

    While grassland birds have become the focus of increased conservation activities, the status of birds occupying shrubland habitats has received relatively little attention (Hunter et al. 2001). Yet, in eastern North America, shrubland birds exhibited consistent population declines during the past 40 years, based on data from the North American Breeding Bird Survey (Pardieck and Sauer 2001). These population declines primarily reflect large-scale changes in land use patterns during the previous century (Lorimer 2001). Large areas of marginal farmland were abandoned and underwent secondary succession during the first half of the twentieth century, producing abundant successional habitats favored by shrubland birds. As these habitats matured, combined with strict fire-suppression policies (Hunter et al. 2001), shrublands succeeded into mature forests, and shrubland bird communities were replaced by woodland birds (Irland 1982; Askins 1993). For example, while nearly 29% of New England forests were classified as sapling stage in 1950, only 8% remained at that stage in the 1980s (Askins 1993). The trend towards forest maturation and loss of shrubland habitats continues, yet concerted conservation activities have not been directed to benefit declining shrubland bird populations. The National Park Service (NPS) could contribute to shrubland bird conservation in the Mid- Atlantic Region. The NPS maintains a number of historic sites and former battlefields managed for their cultural significance but also support wildlife populations. Many of these “cultural parks” maintain open landscapes, recreating land use patterns existing at the times of the historical events. While these open landscapes are frequently managed grasslands, some parks also support successional habitats that could be managed to benefit shrubland birds. In 2005, the NPS initiated a project exploring the potential of “cultural parks” to support significant breeding grassland and shrubland bird

  11. Longer and More Frequent Mid-Atlantic Heat Waves by Mid-Century

    NASA Astrophysics Data System (ADS)

    Sewall, J. O.

    2011-12-01

    Changes in extreme weather events are an area of concern in the face of changing climate. Heat waves (periods of sustained, above normal temperature) are of particular interest given the heavy costs, not only in strain on infrastructure and utilities but also in loss of human life, they can engender (e.g. in the United States, 1995, 2001, 2010; in Europe, 2003, 2006, 2010). In many instances, the costs of heat waves are associated with insufficient local preparedness and infrastructure. With the Earth predicted to warm, future heat waves could be more frequent, sustained, or intense; therefore, preparation for such events might greatly reduce their societal impacts. This study focuses on potential heat wave changes in the highly populous (greater than 96 people/km2) mid-Atlantic region of the Eastern United States from Alexandria, VA through Washington, DC, Baltimore, MD, Philadelphia, PA, the entire state of New Jersey, New York, NY, Long Island, NY, and the entire state of Connecticut. A nested regional climate model (RegCM3) simulated future climate over this region at a 10 km horizontal resolution for two future emissions scenarios (SRES B1 and A1FI). Output from the NCAR CCSM3 drove the regional simulations for two fifteen-year windows from 2050 - 2064 and 2085 - 2099. The final decade of each simulation was averaged for analyses and compared to a 1990 - 1999 simulation. Under both future forcing scenarios, heat waves in the study region increase compared to the twentieth century. In the B1 simulation, the number of summer (June, July, and August average) days exceeding 37.8° C increased by up to 600% at mid-century and up to 200% at the end of the century; the duration of the longest summer heat wave (consecutive days exceeding 37.8° C) increased by up to 26 days at mid-century and up to 10 days by the end of the century. For the A1FI scenario, the number of summer days exceeding 37.8° C increased by up to 250% at mid-century and up to 1300% at the end of

  12. Pleistocene sediment fluxes at 29οN on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Middleton, J. L.; Mukhopadhyay, S.; Langmuir, C. H.; Saxby, A. M.; McManus, J. F.

    2013-12-01

    High resolution paleoclimate records are critical to the understanding of climate stability and instability through the Quaternary. We will present high resolution extraterrestrial helium-3 (3HeET) and planktic foraminifer oxygen isotope data from continuous 2 cm sampling of a new core (KN207-2-GGC6) taken from 29.21oN, 43.23oW on the Mid-Atlantic Ridge. These combined data sets will provide near millennial-scale insight into variations in the accumulation rates of biogenic carbonate and wind-blown terrigenous material throughout the most recent glacial-interglacial cycles. In addition, the combination of 3HeET and oxygen isotope measurements will constrain the influence of variable climate on lateral sediment transport at the Mid-Atlantic Ridge. Thus, our new data will be valuable in investigating instabilities in bottom currents, atmospheric circulation, continental aridity, and carbonate production and preservation. The concentration of 3HeET in marine sediments is a function of the delivery rate of 3HeET to the seafloor by interplanetary dust particles (IDPs) and the vertical rain rate of the bulk sediment. A constant IDP flux causes 3HeET concentrations to vary inversely with mass accumulation rate. Throughout the Quaternary, the constant IDP flux allows for the use of 3HeET as a constant flux-proxy to examine instantaneous sediment mass accumulation rates. Comparison of 3HeET and oxygen isotope data then can quantify the occurrence of sediment focussing within a core. GGC6 is one of a suite of gravity cores collected between 25-37oN on cruise KN207-2 of the R/V Knorr in the summer of 2012. GGC6, recovered from a water depth of 3004 m, is a 147 cm long core composed primarily of calcareous ooze. The carbonate content oscillates with broad maxima (90-95% CaCO3) around the core top and 70-110 cm depth, and minima around 40-60 cm depth (~85% CaCO3) and the core bottom (80-85% CaCO3). Helium data display excellent reproducibility in 3HeET and carbonate

  13. USEPA BIOMONITORING AND BIOINDICATOR CONCEPTS NEEDED TO EVALUATE THE BIOLOGICAL INTEGRITY OF AQUATIC SYSTEMS

    EPA Science Inventory

    This chapter presents the current uses, concepts and anticipated future directions of biomonitoring and bioindicators in the regulatory and research programs of the United States Environmental Protection Agency (USEPA). The chapter provides a historical look on how biomonitoring...

  14. USEPA BIOMONITORING AND BIOINDICATORS CONCEPTS NEEDED TO EVALUATE THE BIOLOGICAL INTEGRITY OF AQUATIC SYSTEMS

    EPA Science Inventory

    This chapter presents the current uses, concepts and anticipated future directions of biomonitoring and bioindicators in the regulatory and research programs of the United States Environmental Protection Agency (USEPA). The chapter provides a historical look on how biomonitoring ...

  15. SSOAP - A USEPA Toolbox for Sanitary Sewer Overflow Analysis and Control Planning - Presentation

    EPA Science Inventory

    The United States Environmental Protection Agency (USEPA) has identified a need to use proven methodologies to develop computer tools that help communities properly characterize rainfall-derived infiltration and inflow (RDII) into sanitary sewer systems and develop sanitary sewer...

  16. Comparison of episodic acidification of Mid-Atlantic Upland and Coastal Plain streams

    NASA Astrophysics Data System (ADS)

    O'Brien, Anne K.; Rice, Karen C.; Kennedy, Margaret M.; Bricker, Owen P.

    1993-09-01

    Episodic acidification was examined in five mid-Atlantic watersheds representing three physiographic provinces: Coastal Plain, Valley and Ridge, and Blue Ridge. Each of the watersheds receives a similar loading of atmospheric pollutants (SO42- and NO3-) and is underlain by different bedrock type. The purpose of this research was to quantify and compare the episodic variability in storm flow chemistry in Reedy Creek, Virginia (Coastal Plain), Mill Run and Shelter Run, Virginia (Valley and Ridge), and Fishing Creek Tributary and Hunting Creek, Maryland (Blue Ridge). Because episodic responses were similar from storm to storm in each of the watersheds, a representative storm from each watershed was discussed. Acidification, defined as the loss of acid-neutralizing capacity (ANC), was observed in all streams except Mill Run. Mill Run chemistry showed little episodic variability. During storms in the other streams, pH decreased while SO42-, NO3-, and K+ concentrations increased. Concentrations of Mg2+ and Ca2+ increased in Reedy Creek and Fishing Creek Tributary, but decreased in Shelter Run and Hunting Creek. Therefore the net effect of episodic changes on the acid-base status differed among the streams. In general, greater losses of ANC were observed during storms at Shelter Run and Hunting Creek, watersheds underlain by reactive bedrock (carbonate, metabasalt); comparatively smaller losses in ANC were observed at Reedy Creek and Fishing Creek Tributary, watersheds underlain by quartzites and unconsolidated quartz sands and cobbles. Increased SO42- concentrations were most important during storms at Reedy Creek and Fishing Creek Tributary, but organic anions (inferred by anion deficit) were also a factor in causing the loss of ANC. Dilution of base cations was the most important factor in the loss of ANC at Shelter Run. Both increased sulfate and dilution of base flow were important in causing the episodic acidification at Hunting Creek. The role of SO42- in

  17. Geological mapping of the Rainbow Massif, Mid-Atlantic Ridge, 36°14'N

    NASA Astrophysics Data System (ADS)

    Ildefonse, B.; Fouquet, Y.; Hoisé, E.; Dyment, J.; Gente, P.; Thibaud, R.; Bissessur, D.; Yatheesh, V.; Momardream 2008 Scientific Party*, T.

    2008-12-01

    The Rainbow hydrothermal field at 36°14'N on the Mid-Atlantic Ridge is one of the few known sites hosted in ultramafic basement. The Rainbow Massif is located along the non-transform offset between the AMAR and South AMAR second-order ridge segments, and presents the characteristic dome morphology of oceanic core complexes, although no corrugated surface has been observed so far. One of the objectives of Cruises MOMAR DREAM (July 2007, R/V Pourquoi Pas ?; Aug-Sept 2008, R/V Atalante) was to study the petrological and structural context of the hydrothermal system at the scale of the Rainbow Massif. Our geological sampling complements previous ones achieved during Cruises FLORES (1997) and IRIS (2001), and consisted in dredge hauls, and submersible dives by manned submersible Nautile and ROV Victor. The tectonics of the Rainbow Massif is dominated by a N-S trending fault pattern on the western flank of the massif, and a series of SW-NW ridges on its northeastern side. The active hydrothermal site is located in the area were these two systems crosscut. The most abundant recovered rock type is peridotite (harzburgite and dunite) that presents a variety of serpentinization styles and intensity, and a variety of deformation styles (commonly undeformed, sometimes displaying ductile or brittle foliations). Serpentinites are frequently oxidized. Some peridotite samples have melt impregnation textures. Massive chromitite was recovered in one dredge haul. Variously evolved gabbroic rocks were collected as discrete samples or as centimeter to decimeter-thick dikes in peridotites. Basalts and fresh basaltic glass were also sampled in talus and sediments on the southwestern and northeastern flanks of the massif. Our sampling is consistent with the lithological variability encountered in oceanic core complexes along the Mid-Atlantic Ridge and Southwest Indian Ridge. The stockwork of the hydrothermal system has been sampled on the western side of the present-day hydrothermal

  18. Comparison of episodic acidification of mid-Atlantic upland and Coastal Plain streams

    USGS Publications Warehouse

    O'Brien, Anne K.; Rice, Karen C.; Kennedy, Margaret M.; Bricker, Owen P.

    1993-01-01

    Episodic acidification was examined in five mid-Atlantic watersheds representing three physiographic provinces: Coastal Plain, Valley and Ridge, and Blue Ridge. Each of the watersheds receives a similar loading of atmospheric pollutants (SO42− and NO3−) and is underlain by different bedrock type. The purpose of this research was to quantify and compare the episodic variability in storm flow chemistry in Reedy Creek, Virginia (Coastal Plain), Mill Run and Shelter Run, Virginia (Valley and Ridge), and Fishing Creek Tributary and Hunting Creek, Maryland (Blue Ridge). Because episodic responses were similar from storm to storm in each of the watersheds, a representative storm from each watershed was discussed. Acidification, defined as the loss of acid-neutralizing capacity (ANC), was observed in all streams except Mill Run. Mill Run chemistry showed little episodic variability. During storms in the other streams, pH decreased while SO42−, NO3−, and K+ concentrations increased. Concentrations of Mg2+ and Ca2+ increased in Reedy Creek and Fishing Creek Tributary, but decreased in Shelter Run and Hunting Creek. Therefore the net effect of episodic changes on the acid-base status differed among the streams. In general, greater losses of ANC were observed during storms at Shelter Run and Hunting Creek, watersheds underlain by reactive bedrock (carbonate, metabasalt); comparatively smaller losses in ANC were observed at Reedy Creek and Fishing Creek Tributary, watersheds underlain by quartzites and unconsolidated quartz sands and cobbles. Increased SO42− concentrations were most important during storms at Reedy Creek and Fishing Creek Tributary, but organic anions (inferred by anion deficit) were also a factor in causing the loss of ANC. Dilution of base cations was the most important factor in the loss of ANC at Shelter Run. Both increased sulfate and dilution of base flow were important in causing the episodic acidification at Hunting Creek. The role of SO42

  19. Crust-Poor Lithosphere at Cold Spots in the Mid Atlantic and SW Indian Ridges

    NASA Astrophysics Data System (ADS)

    Brunelli, D.; Bonatti, E.; Cipriani, A.; Grindlay, N. R.; Ligi, M.; Paganelli, E.; Sclater, J.

    2007-12-01

    The Equatorial portion of the Mid Atlantic Ridge is thought to reflect a thermal minimum in the subridge structure, with deeper than normal axial topography underlain by high upper mantle seismic velocities revealed by tomography. This stretch of Ridge is intersected by a number of long offset transforms, the longest being the Romanche (offset ~950 km corresponding to ~50 Myr). As the Mid Atlantic Ridge axis approaches the Romanche transform from the south, it gradually deepens; its rift valley disappears, and, starting roughly 50 km from the transform, the basaltic crust becomes patchy and then disappears, leaving mantle ultramafics outcropping on the sea floor. Modelling the "cold edge" effect of the transform on the axial Ridge segment shows that partial melting of the subridge mantle decreases as the transform is approached. Crust-free lithosphere outcrops continuously for several hundred kilometers in a ~30 km wide belt south of the Romanche, indicating that the present-day lack of crustal production has been prevailing for at least 30 million years. The mantle derived serpentinized peridotites are of two types. The majority of the samples show evidence of strong impregnation by basaltic melts. The mineral chemistry of the samples that are free of impregnation suggests that they have undergone a very low degree of melting. These results suggest a quasi-crust-free lithosphere, produce by a mantle that has undergone little or no partial melting, unable to expel the small quantities of melt it generates. The small quantities of basalt produced in this area tend to have alkali affinity and are strongly enriched in H2O. Their REE content show a strong garnet signature, suggesting that they were generated mostly in the garnet peridotite mantle zone (> 20 kbar). This quasi-crust-free impregnated lithosphere probably prevails at cold spots along mid ocean ridges. Peridotites obtained recently from the SW end of the Andrew Bain transform, that offsets the SW Indian

  20. Crust-Poor Lithosphere at Cold Spots in the Mid Atlantic and SW Indian Ridges

    NASA Astrophysics Data System (ADS)

    Brunelli, D.; Bonatti, E.; Cipriani, A.; Grindlay, N. R.; Ligi, M.; Paganelli, E.; Sclater, J.

    2004-12-01

    The Equatorial portion of the Mid Atlantic Ridge is thought to reflect a thermal minimum in the subridge structure, with deeper than normal axial topography underlain by high upper mantle seismic velocities revealed by tomography. This stretch of Ridge is intersected by a number of long offset transforms, the longest being the Romanche (offset ~950 km corresponding to ~50 Myr). As the Mid Atlantic Ridge axis approaches the Romanche transform from the south, it gradually deepens; its rift valley disappears, and, starting roughly 50 km from the transform, the basaltic crust becomes patchy and then disappears, leaving mantle ultramafics outcropping on the sea floor. Modelling the "cold edge" effect of the transform on the axial Ridge segment shows that partial melting of the subridge mantle decreases as the transform is approached. Crust-free lithosphere outcrops continuously for several hundred kilometers in a ~30 km wide belt south of the Romanche, indicating that the present-day lack of crustal production has been prevailing for at least 30 million years. The mantle derived serpentinized peridotites are of two types. The majority of the samples show evidence of strong impregnation by basaltic melts. The mineral chemistry of the samples that are free of impregnation suggests that they have undergone a very low degree of melting. These results suggest a quasi-crust-free lithosphere, produce by a mantle that has undergone little or no partial melting, unable to expel the small quantities of melt it generates. The small quantities of basalt produced in this area tend to have alkali affinity and are strongly enriched in H2O. Their REE content show a strong garnet signature, suggesting that they were generated mostly in the garnet peridotite mantle zone (> 20 kbar). This quasi-crust-free impregnated lithosphere probably prevails at cold spots along mid ocean ridges. Peridotites obtained recently from the SW end of the Andrew Bain transform, that offsets the SW Indian

  1. Air Quality in the Mid-Atlantic/Northeast Region: An Aircraft Survey

    NASA Astrophysics Data System (ADS)

    Marufu, L. T.; Doddridge, B.; Taubman, B.; Piety, C.

    2002-12-01

    Parts of the U.S. Mid-Atlantic and Northeast are frequently in violation of the 125 ppbv 1-hr national ambient air quality standard for ozone (O3). The frequency of occurrence and spatial coverage of these violations are expected to increase when/if new standards for fine particulate matter (PM) and ozone averaged over 8-hr come into effect. Online aircraft measurements provide a powerful tool for determining the levels and origins of both primary and secondary pollutants of interest. During the summer of 2002 the University of Maryland at College Park used a twin engine Piper Aztec-F PA-27-250 aircraft to; investigate pollution transport (ozone, haze, and gaseous precursors) over region, state, and class 1 area boundaries; characterize planetary boundary layer (PBL) height, dynamics and development; investigate cross-corridor (transport corridors, metropolitan/ industrial areas) differences in air quality aloft leading to downwind enhancements in pollutants; investigate mesoscale and sub-regional transport influences (e.g. bay and sea breezes, low-level jets, urban island effects) upon near surface air quality and visibility; acquire in situ data for initialization, constraint, and evaluation of ongoing and planned measurement analyses efforts and modeling studies within the region. A total of 54 research flights (192.5 hours), consisting of fixed-position vertical survey spirals and constant altitude transects, were made upwind, near and downwind of selected major cities/industrial areas, transport corridors and class 1 areas in the Northeast, Mid-Atlantic regions. Preliminary results from upwind, near and downwind data show that major cities/industrial areas (Richmond, Washington, Baltimore, Philadelphia, New York and Boston) and transport corridors are net sources of primary and secondary pollutants (gaseous precursors, ozone, and haze). Class 1 areas (Shenandoah national park VA, Lye Brook NY, Mt. Washington in New Hampshire NH and Acadia in ME), on the other

  2. A Surficial Hydrogeologic Framework for the Mid-Atlantic Coastal Plain

    USGS Publications Warehouse

    Ator, Scott W.; Denver, Judith M.; Krantz, David E.; Newell, Wayne L.; Martucci, Sarah K.

    2005-01-01

    A surficial hydrogeologic framework was developed for the Mid-Atlantic Coastal Plain, from New Jersey through North Carolina. The framework includes seven distinct hydrogeologic subregions within which the primary natural physical factors affecting the flow and chemistry of shallow ground water and small streams are relatively consistent. Within most subregions, the transport of chemicals from the land surface to ground water and streams can be described by a fairly uniform set of natural processes; some subregions include mixed hydrogeologic settings that are indistinguishable at the regional scale. The hydrogeologic framework and accompanying physiographic and geologic delineations are presented in digital and printed format. The seven hydrogeologic subregions that constitute the framework were delineated primarily on the basis of physiography and the predominant texture (typical grain size) of surficial and (where surficial sediments are particularly thin) subcropping sediments. Physiography for the Mid-Atlantic Coastal Plain was constructed by standardizing and extrapolating previously published interpretations for the Coastal Plain of South Carolina and New Jersey, based on similar work in the other States. Surficial and subcropping geology were similarly compiled from previous publications by resolving inconsistencies in nomenclature, interpretation, and scale, and interpolating across unmapped areas. A bulk sediment texture was determined for each mapped geologic unit on the basis of published descriptions. Fundamental differences among the seven hydrogeologic subregions are described on the basis of hypotheses about surficial and shallow subsurface hydrology and water chemistry in each, as well as variable land use, soils, and topography. On the regional scale, the Coastal Lowlands (Subregion 1), the Middle Coastal Plain Fine Sediments (Subregion 3), the Middle Coastal Plain Sands with Overlying Gravels (Subregion 4), and the Inner Coastal Plain Upland

  3. The deep biosphere below North Pond: A mid-Atlantic microbial observatory

    NASA Astrophysics Data System (ADS)

    Edwards, K. J.; Bach, W.; Klaus, A.

    2011-12-01

    IODP Expedition 336 (Sept-Nov 2011) was executed to address fundamental microbiological questions concerning the nature of the subseafloor deep biosphere in oceanic hydrological, geological, and biogeochemical context (Edwards et al., 2010). Our principal objective is to study the subseafloor microbiological communities in young igneous ocean crust, in order to understand their role in ocean crust alteration and their ecology in hydrological and biogeochemical context. Specifically, we are testing the hypothesis that microbes play an active role in ocean crust alteration, while also exploring broad based ecological questions such as how hydrological structure and geochemistry influence microbial community structures. We will accomplish this by installing borehole observatories (CORKs) for coupled microbiological, geochemical, and hydrological experiments. These CORKs will allow us to monitor conditions and study processes in-situ,after the drilling disturbance and contaminating influences in the borehole environment have dissipated. Operations during Expedition 336 will lay the foundation for long-term monitoring, experimentation, and observations by subsequent ROV or submersible dive expeditions. CORKs will be used in perturbation and monitoring points for single- and cross-hole experiments, and will use recently developed novel in-situ microbiological experimentation system "FLOCS" (Orcutt et al., 2010a; Orcutt et al., 2010b). This talk will present initial results from Expedition 336 and discuss plans for future observatory operations. Edwards KJ, Bach W, Klaus A (2010). Mid-Atlantic ridge flank microbiology: Initiation of long-term coupled microbiological, geochemical, and hydrological experimentation within the seafloor at North Pond, western flank of the Mid-Atlantic ridge. IODP Sci. Prosp., 336. Integrated Ocean Drilling Program: College Station, TX. p 62 pp.http://publications.iodp.org/scientific_prospectus/336/ Orcutt B, Wheat CG, Edwards KJ (2010a

  4. Metal Concentrations in Two Commercial Tuna Species from an Active Volcanic Region in the Mid-Atlantic Ocean.

    PubMed

    Torres, Paulo; Rodrigues, Armindo; Soares, Lília; Garcia, Patrícia

    2016-02-01

    Concentrations of cadmium (Cd), mercury (Hg), and lead [Pb (µg g(-1) wet weight)] were determined in liver and muscle samples of 15 bigeye (Thunnus obesus) and 15 skipjack tunas (Katsuwonus pelamis) caught over an active volcanic region in the Mid-Atlantic Ocean (Azores, Portugal) and evaluated regarding consumption safety. None of the muscle samples (edible part) exceeded the European Union (EU) maximum limits (MLs) for Hg and Pb. Cd concentrations in muscle were much greater than EU MLs with 53 and 26 % of the bigeye tuna and skipjack tuna, respectively, in exceedance of the limits. Results obtained in this work, together with other studies in the same region, support the existence of an important volcanic source of Cd in waters of the Mid-Atlantic region, which should be carefully monitored given the importance of many commercial marine species for human consumption, mainly in Europe.

  5. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic)

    SciTech Connect

    Mercer, L.P. )

    1989-08-01

    Species profiles are literature summaries of the taxonomy, morphology, range, life, history, and environmental requirements of coastal aquatic species. They are designed to assist in environmental impact assessment. Weakfish are one of the most abundant fishes in the estuarine and nearshore waters of the Atlantic coast. Weakfish mature at age I throughout their range and spawning takes place in coastal and estuarine waters from March to September. Juveniles utilize the deeper areas within estuarine as nursery grounds, migrate from high to low salinity areas throughout the summer, return to high salinity areas in fall, and most leave the estuaries by late fall. Some may remain in estuarine and nearshore coastal waters in winter, particularly in southern areas. Adult weakfish migrate seasonally, north in spring and south in fall between inshore and offshore waters. Growth rates, maximum size, and longevity of weakfish are higher at the northern end of the range. Weakfish are an important recreational and commercial species in the Mid-Atlantic. Weakfish feed predominately on mysid shrimp and anchovies as juveniles, and on clupeids and anchovies as adults. Weakfish have been found over a temperature range of 9.5 to 30.8 {degrees}C. Juvenile weakfish have been found over a wider salinity range (0.1--31.7 ppt) than adults (6.6--32.3 ppt). 72 refs., 5 figs., 5 tabs.

  6. Saldanha Massif, Mid-Atlantic Ridge: A Controlled Source EM Study

    NASA Astrophysics Data System (ADS)

    Sinha, M. C.; Santos, F.; Dzhatieva, Z.; Dias, A.; Marques, A. F.; Silva, N.; de Nijs, I.

    2005-12-01

    In November-December 2004 a controlled source electromagnetic (CSEM) survey was carried out on the axis of the Mid-Atlantic Ridge during cruise Charles Darwin 167. The work is centred on a non-transform offset between the FAMOUS and AMAR segments, at 36 34' North. Here, a prominent feature is the Saldanha massif: a dome of unroofed mantle rocks, consisting largely of serpentised peridotites, and at whose summit significant low-temperature hydrothermal venting has been documented. Our objective is to determine the distribution of electrical resistivity and hence porosity over a volume of ~ 10 km x 10 km x 3 km vertically, in order to constrain the degree of penetration of seawater into the crust and uppermost mantle; to contrast the porosity structure here with volcanically hosted systems away from segment boundaries elsewhere on the MAR; and to constrain models of non-volcanic heat sources and hydrothermal circulation in ultramafic settings at slow spreading ridges. In addition to the CSEM survey we obtained swath bathymetry, gravity and magnetic data; water column physical properties and seafloor current data; and a number of dredge and gravity core samples. We shall present details of the data and samples, together with our preliminary analysis of the results.

  7. Delta-proteobacterial SAR324 group in hydrothermal plumes on the South Mid-Atlantic Ridge

    PubMed Central

    Cao, Huiluo; Dong, Chunming; Bougouffa, Salim; Li, Jiangtao; Zhang, Weipeng; Shao, Zongze; Bajic, Vladimir B.; Qian, Pei-Yuan

    2016-01-01

    In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far. PMID:26953077

  8. Delta-proteobacterial SAR324 group in hydrothermal plumes on the South Mid-Atlantic Ridge.

    PubMed

    Cao, Huiluo; Dong, Chunming; Bougouffa, Salim; Li, Jiangtao; Zhang, Weipeng; Shao, Zongze; Bajic, Vladimir B; Qian, Pei-Yuan

    2016-03-08

    In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far.

  9. Sounds from airguns and fin whales recorded in the mid-Atlantic Ocean, 1999-2009.

    PubMed

    Nieukirk, Sharon L; Mellinger, David K; Moore, Sue E; Klinck, Karolin; Dziak, Robert P; Goslin, Jean

    2012-02-01

    Between 1999 and 2009, autonomous hydrophones were deployed to monitor seismic activity from 16° N to 50° N along the Mid-Atlantic Ridge. These data were examined for airgun sounds produced during offshore surveys for oil and gas deposits, as well as the 20 Hz pulse sounds from fin whales, which may be masked by airgun noise. An automatic detection algorithm was used to identify airgun sound patterns, and fin whale calling levels were summarized via long-term spectral analysis. Both airgun and fin whale sounds were recorded at all sites. Fin whale calling rates were higher at sites north of 32° N, increased during the late summer and fall months at all sites, and peaked during the winter months, a time when airgun noise was often prevalent. Seismic survey vessels were acoustically located off the coasts of three major areas: Newfoundland, northeast Brazil, and Senegal and Mauritania in West Africa. In some cases, airgun sounds were recorded almost 4000 km from the survey vessel in areas that are likely occupied by fin whales, and at some locations airgun sounds were recorded more than 80% days/month for more than 12 consecutive months.

  10. Uranium enrichment in metalliferous sediments from the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Mills, R. A.; Thomson, J.; Elderfield, H.; Hinton, R. W.; Hyslop, E.

    1994-06-01

    Previous studies of metal-rich sediments at mid-ocean ridge spreading centres have suggested that U/Fe ratios are relatively constant from site to site. A suite of cores from the Mid-Atlantic Ridge has been analysed for U and Fe content and most samples exhibit constant U/Fe ratios. Sulphide-bearing parts of one core, however, contain excess U compared with that observed in other metalliferous sediments but apparently only during oxidative alteration of pyrite phases. Fission track registration has demonstrated that this excess U is intimately associated with sulphide grains in the sediment. Scanning electron microscope examination inidates that this U enrichment is limited to very small areas within the oxidation layer and is associated with an enhanced P concentration. Ion probe analyses allow semi-quantitative analyses of various elements through a U-rich grain. The observed distribution of U coupled with its specific enrichment suggests that microbial mediation might be controlling this enrichment. U/Fe ratios in fully oxidised TAG sediments are constant and approximately an order of magnitude higher than in young plume particulates. This discrepancy is attributed to a second type of post-depositional U enrichment producing an homogeneous distribution of U throughout the sediment.

  11. Determination of Trends in Ozone in the Mid-Atlantic Using Non-Negative Matrix Factorization

    NASA Astrophysics Data System (ADS)

    Brown, S. G.; Russell-Graham, A.; Xiao, P.; Balzano, L.

    2014-12-01

    Air pollution data are routinely collected at high time resolution at many sites in the United States, but such data are often assessed singularly or in small jurisdictional groups rather than on a large-scale, regional basis. Examining air pollution data, such as for ambient ozone, in a regional context may be advantageous given that air pollution is influenced by a combination of micro, local, and regional sources. Non-negative matrix factorization (NMF) algorithms have been widely used by the environmental research community to identify factors governing pollutant concentrations. NMF can also be useful for identifying and interpreting outlier data, particularly for large data sets. We applied NMF algorithms to ozone data collected at over 100 monitoring sites in the Mid-Atlantic states during the summer of 2013 to examine their utility for identifying outlier data and outlier monitoring sites in the ozone monitoring network. We compared results from five different NMF algorithms with various strengths (such as being robust to missing data or outliers) to assess differences in their ability to identify outliers and to determine underlying factors influencing ambient ozone concentrations. In the future, these NMF methods can be applied to any large data matrix, such as those from networks of small, low-cost air pollution sensors and large-scale environmental monitoring networks.

  12. Tuberculosis control activities before and after Hurricane Sandy--northeast and mid-Atlantic states, 2012.

    PubMed

    2013-03-22

    On October 29, 2012, Hurricane Sandy struck the U.S. northeast and mid-Atlantic seaboard; the effects of the storm extended to southeastern and midwestern states and to eastern Canada. At the time, 1,899 residents in the most affected areas were undergoing treatment for tuberculosis (TB) disease or infection. To ascertain the operational abilities of state and local TB programs during and after the storm and to determine whether lessons learned from a previous hurricane were effective in ensuring continuity of TB patient care, CDC interviewed staff members at all of the affected state and city TB control programs, including those in areas with power outages and flooded streets, tunnels, and subway lines. The interviews determined that continuity of care for TB patients in programs affected by Hurricane Sandy was better preserved than it had been during and after Hurricane Katrina in August 2005. This improvement might be attributed to 1) preparedness measures learned from Hurricane Katrina (e.g., preparing line lists of patients, providing patients with as-needed medications, and making back-up copies of patient records in advance of the storm) and 2) less widespread displacement of persons after Hurricane Sandy than occurred after Hurricane Katrina. Maintaining readiness among clinicians and TB control programs to respond to natural disasters remains essential to protecting public health and preserving TB patients' continuity of care.

  13. Low-frequency whale and seismic airgun sounds recorded in the mid-Atlantic Ocean.

    PubMed

    Nieukirk, Sharon L; Stafford, Kathleen M; Mellinger, David K; Dziak, Robert P; Fox, Christopher G

    2004-04-01

    Beginning in February 1999, an array of six autonomous hydrophones was moored near the Mid-Atlantic Ridge (35 degrees N-15 degrees N, 50 degrees W-33 degrees W). Two years of data were reviewed for whale vocalizations by visually examining spectrograms. Four distinct sounds were detected that are believed to be of biological origin: (1) a two-part low-frequency moan at roughly 18 Hz lasting 25 s which has previously been attributed to blue whales (Balaenoptera musculus); (2) series of short pulses approximately 18 s apart centered at 22 Hz, which are likely produced by fin whales (B. physalus); (3) series of short, pulsive sounds at 30 Hz and above and approximately 1 s apart that resemble sounds attributed to minke whales (B. acutorostrata); and (4) downswept, pulsive sounds above 30 Hz that are likely from baleen whales. Vocalizations were detected most often in the winter, and blue- and fin whale sounds were detected most often on the northern hydrophones. Sounds from seismic airguns were recorded frequently, particularly during summer, from locations over 3000 km from this array. Whales were detected by these hydrophones despite its location in a very remote part of the Atlantic Ocean that has traditionally been difficult to survey.

  14. Low-frequency whale and seismic airgun sounds recorded in the mid-Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Nieukirk, Sharon L.; Stafford, Kathleen M.; Mellinger, David K.; Dziak, Robert P.; Fox, Christopher G.

    2004-04-01

    Beginning in February 1999, an array of six autonomous hydrophones was moored near the Mid-Atlantic Ridge (35 °N-15 °N, 50 °W-33 °W). Two years of data were reviewed for whale vocalizations by visually examining spectrograms. Four distinct sounds were detected that are believed to be of biological origin: (1) a two-part low-frequency moan at roughly 18 Hz lasting 25 s which has previously been attributed to blue whales (Balaenoptera musculus); (2) series of short pulses approximately 18 s apart centered at 22 Hz, which are likely produced by fin whales (B. physalus); (3) series of short, pulsive sounds at 30 Hz and above and approximately 1 s apart that resemble sounds attributed to minke whales (B. acutorostrata); and (4) downswept, pulsive sounds above 30 Hz that are likely from baleen whales. Vocalizations were detected most often in the winter, and blue- and fin whale sounds were detected most often on the northern hydrophones. Sounds from seismic airguns were recorded frequently, particularly during summer, from locations over 3000 km from this array. Whales were detected by these hydrophones despite its location in a very remote part of the Atlantic Ocean that has traditionally been difficult to survey.

  15. Aerobic Anoxygenic Phototrophic Bacteria in the Mid-Atlantic Bight and the North Pacific Gyre. Revised

    NASA Technical Reports Server (NTRS)

    Cottrell, Matthew T.; Mannino, Antonio; Kirchman, David L.

    2005-01-01

    The abundance of aerobic anoxygenic phototrophic (AM) bacteria, cyanobacteria and heterotrophs was examined in the Mid-Atlantic Bight and the central North Pacific gyre using infrared fluorescence microscopy coupled with image analysis and flow cytometry. AAP bacteria comprised 5% to 16% of total prokaryotes in the Atlantic but only 5% or less in the Pacific. In the Atlantic, AAP bacterial abundance was as much as 2-fold higher than Prochlorococcus and 10-folder higher than Synechococcus. In contrast, Prochlorococcus outnumbered AAP bacteria 5- to 50-fold in the Pacific. In both oceans, subsurface abundance maxima occurred within the photic zone, and AAP bacteria were least abundant below the 1% light depth. Concentrations of bacteriochlorophyll a (BChl a) were low (approx.1%) compared to chlorophyll a. Although the BChl a content of AAP bacteria per cell was typically 20- to 250-fold lower than the divinyl-chlorophyll a content of Prochlorococcus, in shelf break water the pigment content of AAP bacteria approached that of Prochlorococcus. The abundance of AAP bacteria rivaled some groups of strictly heterotrophic bacteria and was often higher than the abundance of known AAP genera (Erythrobacter and Roseobacter spp.). The distribution of AAP bacteria in the water column, which was similar in the Atlantic and the Pacific, was consistent with phototrophy.

  16. Primordial 3He in South Atlantic deep waters from sources on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Rüth, Christine; Well, Roland; Roether, Wolfgang

    2000-06-01

    Helium isotope data from three zonal WOCE sections (11°S, 19°S and 30°S) in the South Atlantic are presented. Among other features we find a distinct δ 3He-maximum above the Mid-Atlantic Ridge (MAR) at all three latitudes. Using a hydrographic multiparameter analysis, we separate 3He emanating from the MAR from the large-scale 3He background. To our knowledge, this is the first confirmation of input of primordial 3He at the MAR in the South Atlantic. The source appears to be weak compared with the Pacific sources, causing 3He elevations (relative to background values) of only 2-3% directly above the MAR. This exceeds by several times the statistical and systematic data uncertainties, which amount to 0.35% each, so that detailed contouring of the MAR-derived 3He is possible. At 30°S and 11°S, a significant signal extends westward over at least 2000 km, whereas at 19°S the signal is more confined to the ridge area. The westward extensions indicate westward flow at depths near the ridge crest elevation, contradicting flow directions deduced previously by Reid (1989).

  17. Tectonic structure of the Mid-Atlantic Ridge near 16°30'N

    NASA Astrophysics Data System (ADS)

    Parnell-Turner, Ross; Schouten, Hans; Smith, Deborah K.

    2016-10-01

    The 16°30'N area of the Mid-Atlantic Ridge represents an area of present-day detachment faulting. Here we present shipboard bathymetric, magnetic and gravity data acquired up to 65 km from the ridge axis that reveal a varied tectonic history of this region. Magnetic data are used to calculate spreading rates and examine spreading rate variability along and across the axis. Bathymetric and gravity data are used to infer the crustal structure. A central magnetic anomaly 40% narrower than expected is observed along much of the study area. Misalignment between modern-day spreading center and magnetic anomalies indicates tectonic reorganization of the axis within the past 780 ka. Observed magnetic anomalies show a pattern of anomalous skewness consistent with rotation of magnetic vectors probably associated with detachment faulting. Relatively thin crust north of a small (˜7 km) nontransform offset coincides with a weakly magmatic spreading axis. In contrast, to the south a robust axial volcanic ridge is underlain by thicker crust. Variations in crustal structure perpendicular to the axis occur over tens of kilometers, indicating processes which occur over timescales of 1-2 Ma.

  18. Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

    USGS Publications Warehouse

    Taylor, Vivien F.; Jackson, Brian P.; Siegfried, Matthew R.; Navratilova, Jana; Francesconi, Kevin A.; Kirshtein, Julie; Voytek, Mary

    2012-01-01

    Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

  19. Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.

    PubMed

    Taylor, Vivien F; Jackson, Brian P; Siegfried, Matthew; Navratilova, Jana; Francesconi, Kevin A; Kirshtein, Julie; Voytek, Mary

    2012-05-04

    Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus, and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ(13)C and δ(15)N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life.

  20. A simulation analysis of the fate of phytoplankton within the mid-Atlantic bight

    NASA Technical Reports Server (NTRS)

    Walsh, J. J.; Dieterle, D. A.; Meyers, M. B.

    1986-01-01

    A time-dependent, three-dimensional simulation model of wind-induced changes of the circulation field, of light and nutrient regulation of photosynthesis, of vertical mixing as well as algal sinking, and of herbivore grazing stress, is used to analyze the seasonal production, consumption, and transport of the spring bloom within the mid-Atlantic Bight. The particular case (c) of a 58-day period in February-April 1979, simulated primary production, based on both nitrate and recycled nitrogen, with a mean of 0.62 g C sq m/day over the whole model domain, and an export at the shelf-break off Long Island of 2.60 g ch1 sq m/day within the lower third of the water column. About 57% of the carbon fixation was removed by herbivores, with 21% lost as export, either downshelf or offshore to slope waters, after the first 58 days of the spring bloom. Extension of the model for another 22 days of case (c) increased the mean export to 27%, while variation of the model's parameters in 8 other cases led to a range in export from 8% to 38% of the average primary production. Spatial and temporal variations of the simulated albal biomass, left behind in the shelf water column, reproduced chlorophyll fields sensed by satellite, shipboard, and in situ instruments.

  1. Diet composition of Bathylagus euryops (Osmeriformes: Bathylagidae) along the northern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Sweetman, C. J.; Sutton, T. T.; Vecchione, M.; Latour, R. J.

    2014-10-01

    The northern Mid-Atlantic Ridge, from Iceland to the Azores (MAR), is the largest topographical feature in the Atlantic Ocean. Despite its size, few studies have described dietary patterns of pelagic fishes along the MAR. MAR-ECO, a Census of Marine Life field project, aimed to describe the food web structure of abundant fish species along the ridge through a series of research expeditions to the MAR. Among the midwater fishes sampled during the MAR-ECO project, Bathylagus euryops (Osmeriformes: Bathylagidae) was the biomass-dominant pelagic species and ranked third in total abundance. In this paper, we describe the dietary composition of B. euryops along the MAR. Overall, copepods represented the dominant prey group consumed by B. euryops. Multivariate analyses, including a cluster analysis and a canonical correspondence analysis, revealed that fish size significantly influenced the diet of B. euryops with ostracods representing the most important prey group at small sizes (<95 mm) and decapod shrimp and calanoid copepods becoming more important with increasing fish size. Due to the high abundance and biomass observed along the MAR combined with its role as a link for energy transfer between zooplankton and higher trophic level predators, B. euryops appears to be an ecologically important species in the oceanic food web of the North Atlantic Ocean.

  2. Species composition and distribution patterns of fishes captured by longlines on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Fossen, I.; Cotton, C. F.; Bergstad, O. A.; Dyb, J. E.

    2008-01-01

    During the 2004 MAR-ECO expedition to the Mid-Atlantic Ridge, the M/S Loran deployed longlines and caught a total of 8518 fish, representing 40 species and 17 families. The 59 longline sets were distributed across the ridge axis at depths ranging from 400 to 4300 m within two sub-areas, i.e. just north of the Azores archipelago and in the Charlie-Gibbs Fracture Zone (CGFZ). Overall, chondrichthyans dominated the catches and contributed nearly 60% in terms of both weight and numbers. This was mainly due to the dominance of Etmopterus princeps in both sub-areas. Multidimensional scaling using species-by-station data indicated an assemblage distribution related primarily to factors varying by depth and latitude. Grouping patterns of stations were not very pronounced, suggesting a gradual spatial change rather than abrupt changes in species composition by depth or latitude. Catch rates peaked at the shallower stations in the CGFZ sub-area, and generally decreased with depth. Relatively large individuals dominated, and the overall mean weight was 2.4 kg. Average fish weight was lower in the CGFZ sub-area than in the southern sub-area. No depth-related pattern was found.

  3. Delta-proteobacterial SAR324 group in hydrothermal plumes on the South Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Cao, Huiluo; Dong, Chunming; Bougouffa, Salim; Li, Jiangtao; Zhang, Weipeng; Shao, Zongze; Bajic, Vladimir B.; Qian, Pei-Yuan

    2016-03-01

    In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far.

  4. Near seafloor bioluminescence, macrozooplankton and macroparticles at the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Craig, Jessica; Youngbluth, Marsh; Jamieson, Alan J.; Priede, Imants G.

    2015-04-01

    The benthic boundary layer is a region often perceived to be high in faunal abundance and biomass. In this study, we investigated the distribution of near seafloor bioluminescent zooplankton (BL), macrozooplankton (>1 cm) and macroparticles (>430 μm) at the Northern Mid-Atlantic Ridge at ca. 2500 m depth. At sites south of 52°N, the Charlie Gibbs Fracture Zone, BL density increased weakly towards the seafloor. This trend was driven by small bioluminescent crustaceans, comprising ca. 90% of the total BL density. Macroparticle density was coherent with BL density, exhibiting a small increase towards the seafloor. Appendicularians (animals as well as occupied and discarded houses) were the most abundant macrozooplankton, and the only group to show a significant increase in density towards the seafloor. The absence of pronounced increases in BL and macroparticle density, and no increase in macrozooplankton (except appendicularians), towards the seafloor do not support the conventional view of high concentrations of particulate organic matter and zooplankton biomass in the benthic boundary layer relative to overlying waters.

  5. Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

    PubMed Central

    Taylor, Vivien F.; Jackson, Brian P.; Siegfried, Matthew; Navratilova, Jana; Francesconi, Kevin A.; Kirshtein, Julie; Voytek, Mary

    2012-01-01

    Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus, and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life. PMID:23741175

  6. Seaweed biogeography of the mid-Atlantic coast of the United States

    NASA Astrophysics Data System (ADS)

    Searles, R. B.

    1984-06-01

    The northern boundary of the warm temperate region of the mid-Atlantic coast of the United States is set at Cape Hatteras; the southern boundary lies at Cape Canaveral. There is some spillover of cool temperate species south of Cape Hatteras into North Carolina and spillover of warm temperate species south of Cape Canaveral toward Palm Beach. Elements of the warm temperate flora also extend into the northern Gulf of Mexico, but precise limits to the flora cannot be drawn there. Thirty-one species are endemic to the warm temperate flora. The inshore waters of North Carolina include approximately equal numbers of species with northern and southern centres of distribution; the species of the offshore waters have predominantly southern affinities, but also include most of the endemic species. Seasonal changes in the shallow water flora of North Carolina reflect eurythermal cool temperate and tropical elements in winter and summer respectively and a year-round warm temperate element. These groupings have been verified by experimental studies in which light and temperature were varied. The deep water flora is a summer flora dominated by perennial species. The inshore, eurythermal cool temperate and tropical species have a variety of cryptic stages by which they persist throughout the year.

  7. Application of a multipurpose unequal probability stream survey in the Mid-Atlantic Coastal Plain

    USGS Publications Warehouse

    Ator, S.W.; Olsen, A.R.; Pitchford, A.M.; Denver, J.M.

    2003-01-01

    A stratified, spatially balanced sample with unequal probability selection was used to design a multipurpose survey of headwater streams in the Mid-Atlantic Coastal Plain. Objectives for the survey include unbiased estimates of regional stream conditions, and adequate coverage of unusual but significant environmental settings to support empirical modeling of the factors affecting those conditions. The design and field application of the survey are discussed in light of these multiple objectives. A probability (random) sample of 175 first-order nontidal streams was selected for synoptic sampling of water chemistry and benthic and riparian ecology during late winter and spring 2000. Twenty-five streams were selected within each of seven hydrogeologic subregions (strata) that were delineated on the basis of physiography and surficial geology. In each subregion, unequal inclusion probabilities were used to provide an approximately even distribution of streams along a gradient of forested to developed (agricultural or urban) land in the contributing watershed. Alternate streams were also selected. Alternates were included in groups of five in each subregion when field reconnaissance demonstrated that primary streams were inaccessible or otherwise unusable. Despite the rejection and replacement of a considerable number of primary streams during reconnaissance (up to 40 percent in one subregion), the desired land use distribution was maintained within each hydrogeologic subregion without sacrificing the probabilistic design.

  8. Near-bottom currents over the continental slope in the Mid-Atlantic Bight

    USGS Publications Warehouse

    Csanady, G.T.; Churchill, J.H.; Butman, B.

    1988-01-01

    From a set of 28 current meter records we have found that near-bottom currents faster than 0.2 m s-1 occur frequently over the outer continental shelf of the Mid-Atlantic Bight (bottom depth <210 m) but very rarely (<1% of the time) between bottom depths of 500 m and 2 km over the slope. The rarity of strong near-bottom flow over the middle and lower slope allows the accumulation of fine-grained sediment and organic carbon in this region. Fast near-bottom currents which do occur over the slope are invariably associated with topographic waves, although it is often superimposed inertial oscillations which increase current speed above the level of 0.2 m s-1. Episodes of intense inertial oscillations occur randomly and last typically for 10-20 days. Their energy source is unknown. Topographic wave energy exhibits a slight, but statistically significant, minimum over the mid-slope. These waves appear irregularly and vary both along isobaths and in time. The irregularity is presumably a consequence of random topographic wave generation by Gulf Stream instability. The current regime within sea-floor depressions in the slope (canyons and gullies) is distinctly different from that of the open slope; most notable is the near absence of topographic wave motion within depressions. ?? 1988.

  9. Strong seismic heterogeneity in layer 2A near hydrothermal vents at the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Arnulf, A. F.; Singh, S. C.; Harding, A. J.; Kent, G. M.; Crawford, W.

    2011-07-01

    We present a high-resolution 3D seismic image beneath the Lucky Strike volcano on the Mid-Atlantic Ridge using streamer tomography. To obtain a high-resolution ray coverage in layer 2A, we first downward continue the multichannel seismic (MCS) data close to the seafloor generating a synthetic ocean bottom experiment (SOBE) and then apply 3D travel-time tomography. We find that the upper crust is laterally heterogeneous on 2-3 km scale, with unusually low velocities (1.8-2.2 km.s-1) in the upper few hundred meters beneath the Lucky Strike volcanic edifices, but normal layer 2A velocities (2.2-3.0 km.s-1) beneath the lava lake. The low velocities could be due to extremely high porosity (25-50%) in recently erupted, highly fractured pillow lavas. The hydrothermal vent fields seem to lie at the boundary between the high-porosity edifices and the lower porosity lava lake. We have also imaged a reflector at the base of the volcanic edifices that is distinct from the deeper high-velocity gradient transition zone from layer 2A to 2B imaged so far. The new technique provides an image of the oceanic crust with resolutions comparable to that of seafloor geology, leading to new insight about volcanic and hydrothermal processes.

  10. Myctophid feeding ecology and carbon transport along the northern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Hudson, Jeanna M.; Steinberg, Deborah K.; Sutton, Tracey T.; Graves, John E.; Latour, Robert J.

    2014-11-01

    Myctophids are among the most abundant fishes in the world's ocean and occupy a key position in marine pelagic food webs. Through their significant diel vertical migrations and metabolism they also have the potential to be a significant contributor to carbon export. We investigated the feeding ecology and contribution to organic carbon export by three myctophid species, Benthosema glaciale, Protomyctophum arcticum, and Hygophum hygomii, from a structurally and ecologically unique ecosystem- the Mid-Atlantic Ridge (MAR). Similar to the results of previous studies, the diet of these fishes was primarily copepods and euphausiids, however, gelatinous zooplankton was identified in the diet of B. glaciale for the first time. Ridge section and time of day were significant explanatory variables in the diet of B. glaciale as determined by canonical correspondence analysis, while depth was the only significant explanatory variable in the diet of P. arcticum. Daily consumption by MAR myctophids was less than 1% of dry body weight per day and resulted in the removal of less than 1% of zooplankton biomass daily. Although lower than previous estimates of carbon transport by myctophids and zooplankton in other areas, MAR myctophid active transport by diel vertical migration was equivalent to up to 8% of sinking particulate organic carbon in the North Atlantic. While highly abundant, myctophids do not impart significant predation pressure on MAR zooplankton, and play a modest role in the active transport of carbon from surface waters.

  11. Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field.

    PubMed

    Singh, Satish C; Crawford, Wayne C; Carton, Hélène; Seher, Tim; Combier, Violaine; Cannat, Mathilde; Pablo Canales, Juan; Düsünür, Doga; Escartin, Javier; Miranda, J Miguel

    2006-08-31

    Crust at slow-spreading ridges is formed by a combination of magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers. The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate and fast-spreading centres, but it has been difficult to image such magma chambers beneath slow-spreading centres, owing to rough seafloor topography and associated seafloor scattering. In the absence of any images of magma chambers or of subsurface near-axis faults, it has been difficult to characterize the interplay of magmatic and tectonic processes in crustal accretion and hydrothermal circulation at slow-spreading ridges. Here we report the presence of a crustal magma chamber beneath the slow-spreading Lucky Strike segment of the Mid-Atlantic Ridge. The reflection from the top of the magma chamber, centred beneath the Lucky Strike volcano and hydrothermal field, is approximately 3 km beneath the sea floor, 3-4 km wide and extends up to 7 km along-axis. We suggest that this magma chamber provides the heat for the active hydrothermal vent field above it. We also observe axial valley bounding faults that seem to penetrate down to the magma chamber depth as well as a set of inward-dipping faults cutting through the volcanic edifice, suggesting continuous interactions between tectonic and magmatic processes.

  12. Karst of the Mid-Atlantic region in Maryland, West Virginia, and Virginia

    USGS Publications Warehouse

    Doctor, Daniel H.; Weary, David J.; Brezinski, David K.; Orndorff, Randall C.; Spangler, Lawrence E.; Brezinski, David K.; Halka, Jeffrey; Ortt, Richard A.

    2015-01-01

    The Mid-Atlantic region hosts some of the most mature karst landscapes in North America, developed in highly deformed rocks within the Piedmont and Valley and Ridge physiographic provinces. This guide describes a three-day excursion to examine karst development in various carbonate rocks by following Interstate 70 west from Baltimore across the eastern Piedmont, across the Frederick Valley, and into the Great Valley proper. The localities were chosen in order to examine the structural and lithological controls on karst feature development in marble, limestone, and dolostone rocks with an eye toward the implications for ancient landscape evolution, as well as for modern subsidence hazards. A number of caves will be visited, including two commercial caverns that reveal strikingly different histories of speleogenesis. Links between karst landscape development, hydrologic dynamics, and water resource sustainability will also be emphasized through visits to locally important springs. Recent work on quantitative dye tracing, spring water geochemistry, and groundwater modeling reveal the interaction between shallow and deep circulation of groundwater that has given rise to the modern karst landscape. Geologic and karst feature mapping conducted with the benefit of lidar data help reveal the strong bedrock structural controls on karst feature development, and illustrate the utility of geologic maps for assessment of sinkhole susceptibility.

  13. Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards.

    PubMed

    Leskey, T C; Hogmire, H W

    2005-02-01

    Pyramid traps coated with "industrial safety yellow" exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color ("industrial safety yellow" and "standard coroplast yellow") and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.

  14. Health and climate benefits of offshore wind facilities in the Mid-Atlantic United States

    NASA Astrophysics Data System (ADS)

    Buonocore, Jonathan J.; Luckow, Patrick; Fisher, Jeremy; Kempton, Willett; Levy, Jonathan I.

    2016-07-01

    Electricity from fossil fuels contributes substantially to both climate change and the health burden of air pollution. Renewable energy sources are capable of displacing electricity from fossil fuels, but the quantity of health and climate benefits depend on site-specific attributes that are not often included in quantitative models. Here, we link an electrical grid simulation model to an air pollution health impact assessment model and US regulatory estimates of the impacts of carbon to estimate the health and climate benefits of offshore wind facilities of different sizes in two different locations. We find that offshore wind in the Mid-Atlantic is capable of producing health and climate benefits of between 54 and 120 per MWh of generation, with the largest simulated facility (3000 MW off the coast of New Jersey) producing approximately 690 million in benefits in 2017. The variability in benefits per unit generation is a function of differences in locations (Maryland versus New Jersey), simulated years (2012 versus 2017), and facility generation capacity, given complexities of the electrical grid and differences in which power plants are offset. This work demonstrates health and climate benefits of offshore wind, provides further evidence of the utility of geographically-refined modeling frameworks, and yields quantitative insights that would allow for inclusion of both climate and public health in benefits assessments of renewable energy.

  15. Wildlife Densities and Habitat Use Across Temporal and Spatial Scales on the Mid-Atlantic Outer Continental Shelf. Final Report to the Department of Energy EERE Wind & Water Power Technologies Office

    SciTech Connect

    Williams, Kathryn A.; Stenhouse, Iain J.; Johnson, Sarah M.; Connelly, Emily E.

    2015-10-01

    The Mid-Atlantic Baseline Studies Project helped address environmental barriers to offshore wind energy development in the mid-Atlantic region by providing regulators, developers, and other stakeholders with comprehensive baseline ecological data and analyses. Project funders and collaborators from a range of academic institutions, non-governmental organizations, federal agencies, foundations, and private companies came together to study bird, sea turtle, and marine mammal distributions, densities, and movements on the mid-Atlantic Outer Continental Shelf between 2012 and 2014. Specific project activities and goals included the following: (1) Conduct standardized surveys to quantify bird, sea turtle, and marine mammal densities seasonally and annually throughout the study region and identify important habitat use or aggregation areas. (2) Develop statistical models to help understand the drivers of wildlife distribution and abundance patterns. (3) Use individual tracking data for several focal bird species to provide information on population connectivity and individual movements that is complementary to survey data. (4) Identify species that are likely to be exposed to offshore wind energy development activities in the mid-Atlantic study area. (5) Develop U.S.-based technological resources and assessment methods for future monitoring efforts, including a comparison of high resolution digital video aerial surveys to boat-based surveys. (6) Help meet data needs associated with National Environmental Policy Act (NEPA), Marine Mammal Protection Act, and Endangered Species Act requirements, by contributing several years of data and analysis towards future Environmental Impact Statements. This report consists of six parts: Project overview (executive summary and Chapters 1-2); Examining wildlife distributions and relative abundance from a digital video aerial survey platform (Chapters 3-6); Examining wildlife distributions and abundance using boat-based surveys

  16. Wave climate model of the Mid-Atlantic shelf and shoreline (Virginian Sea): Model development, shelf geomorphology, and preliminary results

    NASA Technical Reports Server (NTRS)

    Goldsmith, V.; Morris, W. D.; Byrne, R. J.; Whitlock, C. H.

    1974-01-01

    A computerized wave climate model is developed that applies linear wave theory and shelf depth information to predict wave behavior as they pass over the continental shelf as well as the resulting wave energy distributions along the coastline. Reviewed are also the geomorphology of the Mid-Atlantic Continental Shelf, wave computations resulting from 122 wave input conditions, and a preliminary analysis of these data.

  17. Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). American Oyster.

    DTIC Science & Technology

    1986-07-01

    may be expected to react to environmental changes caused by coastal development. Each profile has sections on taxonomy , life history, ecological role...Profiles: Life Histories and DT1CEnvironmental Requirements of Coastal Fishes ~ ~ T and Invertebrates (Mid-Atlantic) JUN1 9E AMERICAN OYSTER Coastal Ecology ...ificat ion Performed for U.S. Army Corps of Engineers DY Coastal Ecology Group Ditribution/ Waterways Experiment Station Avaiabiity oe Vicksburg, MS

  18. Long-term Bat Monitoring on Islands, Offshore Structures, and Coastal Sites in the Gulf of Maine, mid-Atlantic, and Great Lakes—Final Report

    SciTech Connect

    Peterson, Trevor; Pelletier, Steve; Giovanni, Matt

    2016-01-15

    This report summarizes results of a long-term regional acoustic survey of bat activity at remote islands, offshore structures, and coastal sites in the Gulf of Maine, Great Lakes, and mid-Atlantic coast.

  19. Energy landscapes: Coal canals, oil pipelines, and electricity transmission wires in the mid-Atlantic, 1820--1930

    NASA Astrophysics Data System (ADS)

    Jones, Christopher F.

    2009-12-01

    Coal canals, oil pipelines, and electricity transmission wires transformed the built environment of the American mid-Atlantic region between 1820 and 1930. By transporting coal, oil, and electrons cheaply, reliably, and in great quantities, these technologies reshaped the energy choices available to mid-Atlantic residents. In particular, canals, pipelines, and wires created new energy landscapes: systems of transport infrastructure that enabled the ever-increasing consumption of fossil fuels. Energy Landscapes integrates history of technology, environmental history, and business history to provide new perspectives on how Americans began to use fossil fuels and the social implications of these practices. First, I argue that the development of transport infrastructure played critical, and underappreciated, roles in shaping social energy choices. Rather than simply responding passively to the needs of producers and consumers, canals, pipelines, and wires structured how, when, where, and in what quantities energy was used. Second, I analyze the ways fossil fuel consumption transformed the society, economy, and environment of the mid-Atlantic. I link the consumption of coal, oil, and electricity to the development of an urban and industrialized region, the transition from an organic to a mineral economy, and the creation of a society dependent on fossil fuel energy.

  20. North Atlantic Current variability and associated mixing at the Mid-Atlantic Ridge (observed)

    NASA Astrophysics Data System (ADS)

    Walter, M.; Mertens, C.; Dengler, M.; Rhein, M.

    2012-12-01

    Observational evidence for enhanced turbulent energy dissipation at sites of topography- mesoscale flow interaction indicates the possible role of fronts and eddies as energy source for mixing. In consequence, changes in the (upper ocean) flow field must have an impact on stratification and circulation in the deep ocean as patterns of mixing and water mass transformation may be altered by changing the locations of flow-topography interactions. In the north Atlantic, the North Atlantic Current (NAC) that crosses the Mid-Atlantic Ridge (MAR) between 48° and 54°N is known to shift its position and develop different branch modes in response to the prevalent wind field. Strength and positioning of the branches is modulated by the slowly varying eddy field and corresponds to the gaps in the MAR: the northern branch, also known as subpolar front (SPF) crosses the ridge at the latitude of the Charlie-Gibbs Fracture Zone (CGFZ), the southern branches are less restricted and more eddy dominated, but tend to align with the Faraday or Maxwell Fracture Zones. We use repeated observations of hydrography and currents at the SPF west of the Mid-Atlantic Ridge to investigate the temporal variability of the spatial distribution of finescale variance and derived properties (as diapycnal diffusivity and integrated energy dissipation) in their relation to the position of the NAC. The CTD and lowered ADCP observations were carried out during three (summer) cruises in 2008, 2010, and 2011. During the 2008 cruise, additional microstructure data was collected at three stations, used to validate dissipation rates from a shear/strain parameterization in the upper 1200 m. The orientation of the repeat section is roughly in southeast-northwest direction, starting at about 48°N and ending near the western exit of the CGFZ. The position of the NAC shows considerable differences between the three realizations. In 2008, a single branch mode was found, with the SPF approximately at 50°30'N. In

  1. Igneous Crystallization Beginning at 20 km Beneath the Mid-Atlantic Ridge, 14 to 16 N

    NASA Astrophysics Data System (ADS)

    Kelemen, P.

    2003-12-01

    ODP Leg 209 drilled 19 holes at 8 sites along the Mid-Atlantic Ridge from 14° 43 to 15° 44 N. All sites were previously surveyed by submersible, and were chosen to be < 200 m from peridotite or dunite exposed on the seafloor; outcrops of gabbroic rock were also near some sites. One primary goal of Leg 209 was to constrain melt migration and igneous petrogenesis in this region where residual peridotites are exposed on both sides of the Ridge axis. At Sites 1269 and 1273, we penetrated 112 m of basaltic rubble; recovery was poor (3.7 m) and holes unstable, so drilling was terminated. Lavas form nearly horizontal surfaces overlying cliffs exposing peridotite and gabbro. At 6 other sites, we drilled a mixture of residual peridotite and gabbroic rocks intrusive into peridotite. We penetrated 1075 meters at these 6 sites, and recovered 354 m of core. Drilling at Sites 1268, 1270, 1271 and 1272 recovered 25% gabbroic rocks and 75% residual mantle peridotite. Core from Site 1274 is mainly residual peridotite, with a few m-scale gabbroic intrusions. Core from Site 1275 is mainly gabbroic, but contains 24% poikilitic lherzolite interpreted as residual peridotite "impregnated" by plagioclase and pyroxene crystallized from melt migrating along olivine grain boundaries; these impregnated peridotites were later intruded by evolved gabbros. Impregnated peridotites are also common at Site 1271, and present at Sites 1268 and 1270. The overall proportion of gabbroic rocks versus residual peridotites from these 6 sites is similar to previous dredging and submersible sampling in the area. The proportion of gabbro is larger than in"amagmatic" regions on the ultra-slow spreading SWIR and Gakkel Ridges. Impregnated peridotites from Site 1275 have "equilibrated" textures and contain olivine, 2 pyroxenes, plag and Cr-rich spinel. Their whole rock Mg#, Cr# and Ni are high, extending to residual peridotite values. 87 MORB glasses from 14 to 16° N with Mg# from 60 to 73 [from PetDB] could

  2. Temporal trends in nitrate and selected pesticides in Mid-Atlantic ground water.

    PubMed

    Debrewer, Linda M; Ator, Scott W; Denver, Judith M

    2008-01-01

    Evaluating long-term temporal trends in regional ground-water quality is complicated by variable hydrogeologic conditions and typically slow flow, and such trends have rarely been directly measured. Ground-water samples were collected over near-decadal and annual intervals from unconfined aquifers in agricultural areas of the Mid-Atlantic region, including fractured carbonate rocks in the Great Valley, Potomac River Basin, and unconsolidated sediments on the Delmarva Peninsula. Concentrations of nitrate and selected pesticides and degradates were compared among sampling events and to apparent recharge dates. Observed temporal trends are related to changes in land use and chemical applications, and to hydrogeology and climate. Insignificant differences in nitrate concentrations in the Great Valley between 1993 and 2002 are consistent with relatively steady fertilizer application during respective recharge periods and are likely related to drought conditions in the later sampling period. Detecting trends in Great Valley ground water is complicated by long open boreholes characteristic of wells sampled in this setting which facilitate significant ground-water mixing. Decreasing atrazine and prometon concentrations, however, reflect reported changes in usage. On the Delmarva Peninsula between 1988 and 2001, median nitrate concentrations increased 2 mg per liter in aerobic ground water, reflecting increasing fertilizer applications. Correlations between selected pesticide compounds and apparent recharge date are similarly related to changing land use and chemical application. Observed trends in the two settings demonstrate the importance of considering hydrogeology and recharge date along with changing land and chemical uses when interpreting trends in regional ground-water quality.

  3. Crystallization depth beneath an oceanic detachment fault (ODP Hole 923A, Mid-Atlantic Ridge)

    NASA Astrophysics Data System (ADS)

    Lissenberg, C. Johan; Rioux, Matthew; MacLeod, Christopher J.; Bowring, Samuel A.; Shimizu, Nobumichi

    2016-01-01

    Oceanic detachment faults are increasingly recognized as playing an integral role in the seafloor spreading process at slow and ultraslow spreading mid-ocean ridges, with significant consequences for the architecture of the oceanic lithosphere. Although melt supply is considered to play a critical control on the formation and evolution of oceanic detachments, much less well understood is how melts and faults interact and influence each other. Few direct constraints on the locus and depth of melt emplacement in the vicinity of detachments are available. Gabbros drilled in ODP Hole 923A near the intersection of the Mid-Atlantic Ridge and the Kane transform fault (23°N; the MARK area) represent magmas emplaced into the footwall of such a detachment fault and unroofed by it. We here present U-Pb zircon dates for these gabbros and associated diorite veins which, when combined with a tectonic reconstruction of the area, allow us to calculate the depths at which the melts crystallized. Th-corrected single zircon U-Pb dates from three samples range from 1.138 ± 0.062 to 1.213 ± 0.021 Ma. We find a crystallization depth of 6.4 +1.7/-1.3 km, and estimate that the melts parental to the gabbros were initially emplaced up to 1.5 km deeper, at <8 km below the seafloor. The tectonic reconstruction implies that the detachment fault responsible for the exposure of the sampled sequence likely crossed the ridge axis at depth, suggesting that melt emplacement into the footwall of oceanic detachment faults is an important process. The deep emplacement depth we find associated with "detachment mode" spreading at ˜1.2 Ma appears to be significantly greater than the depth of magma reservoirs during the current "magmatic mode" of spreading in the area, suggesting that the northern MARK segment preserves a recent switch between two temporally distinct modes of spreading with fundamentally different lithospheric architecture.

  4. Geochemical and microbial export from the Rainbow vent-site, 36N Mid-Atlantic Ridge.

    NASA Astrophysics Data System (ADS)

    Thurnherr, A. M.; German, C. R.

    2002-12-01

    We present results from a detailed investigation of the physical, chemical and microbial fluxes away from the Rainbow hydrothermal field 36N, Mid-Atlantic Ridge. Physical oceanographic studies (Thurnherr and Richards, JGR, 2001; Thurnherr et al. JPO, 2002) have used in situ CTD and optical back-scatter data, combined with lowered-ADCP measurements and long-term current meter records to investigate circulation through this section of the MAR rift-valley and to determine fluxes of plume particulate material away from the Rainbow vent-site. Using the continuous optical back-scatter data-set from a SeaTech LSS light scattering sensor mounted on our BRIDGET deep-tow vehicle and combining that data with analyses for (e.g.) TDMn and CH4 in discrete water-bottle samples collected during the BRIDGET tow-yos we can now construct integrated geochemical fluxes through the Rainbow hydrothermal plume. From the integrated LSS-anomaly flux across the sill NE of the Rainbow vent-site we estimate total Mn and methane fluxes which approach 1 mol/second being discharged through the non-buoyant hydrothermal plume. The fluxes calculated by this approach require discharge of the well-characterised Rainbow end-member fluids (Douville et al., Chem Geol., 2002) at a rate of >400 Litres per second. In addition to dissolved chemical export fluxes, particulate Fe and associated trace metal fluxes can also be calculated. Further, the Rainbow plume is characterised by high microbial concentrations (3 x background) the majority of which are also particle-attached. Molecular microbial analyses of samples of these particle-attached microbes have revealed that the majority of clones produced through PCR are archaeal in nature (bacteria typically dominate in the open ocean). In particular, group II marine archaea (euryarchaeota) are especially abundant, notably methanogens, consistent with the high dissolved methane fluxes associated with the Rainbow hydrothermal plume.

  5. Dependence of seismic coupling on normal fault style along the Northern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Olive, Jean-Arthur; Escartín, Javier

    2016-10-01

    While normal faults are essential in shaping the seafloor formed at slow spreading mid-ocean ridges, information on their behavior on short (seismic cycle) time scales is limited. Here we combine catalogs of hydro-acoustically and teleseismically recorded earthquakes to characterize the state of seismic coupling along the Northern Mid-Atlantic Ridge (MAR) between 12°N and 35°N. Along this portion of the MAR axis, tectonic extension is either taken up by steep conjugate faults that outline well-defined ridge-parallel abyssal hills, or dominantly by a large-offset detachment fault on one side of the axis. We investigate variations in seismicity and seismic moment release rates across 30 ridge sections that can be clearly characterized either as abyssal hill or detachment bearing. We find that detachment-bearing sections are associated with significantly greater seismicity and moment release rates than abyssal hill-bearing sections but show variability that may reflect the along-axis extent of individual detachment faults. Overall, the measured seismic moment release rates fail to account for the long-term fault slip rates. This apparent seismic deficit could indicate a mixed-mode of fault slip where earthquakes only account for ˜10-30% of offset buildup at abyssal hill faults, while the rest is accommodated by some form of transient aseismic creep. We find this seismic coupling fraction to be significantly greater (˜40-60%) at individual detachment systems, which is somewhat at odds with the common inference that detachment faults can sustain long-lived localized strain because they are weak. We therefore propose alternative interpretations for seismic coupling based on dynamic friction theory.

  6. Genetic connectivity between north and south Mid-Atlantic Ridge chemosynthetic bivalves and their symbionts.

    PubMed

    van der Heijden, Karina; Petersen, Jillian M; Dubilier, Nicole; Borowski, Christian

    2012-01-01

    Transform faults are geological structures that interrupt the continuity of mid-ocean ridges and can act as dispersal barriers for hydrothermal vent organisms. In the equatorial Atlantic Ocean, it has been hypothesized that long transform faults impede gene flow between the northern and the southern Mid-Atlantic Ridge (MAR) and disconnect a northern from a southern biogeographic province. To test if there is a barrier effect in the equatorial Atlantic, we examined phylogenetic relationships of chemosynthetic bivalves and their bacterial symbionts from the recently discovered southern MAR hydrothermal vents at 5°S and 9°S. We examined Bathymodiolus spp. mussels and Abyssogena southwardae clams using the mitochondrial cytochrome c oxidase subunit I (COI) gene as a phylogenetic marker for the hosts and the bacterial 16S rRNA gene as a marker for the symbionts. Bathymodiolus spp. from the two southern sites were genetically divergent from the northern MAR species B. azoricus and B. puteoserpentis but all four host lineages form a monophyletic group indicating that they radiated after divergence from their northern Atlantic sister group, the B. boomerang species complex. This suggests dispersal of Bathymodiolus species from north to south across the equatorial belt. 16S rRNA genealogies of chemoautotrophic and methanotrophic symbionts of Bathymodiolus spp. were inconsistent and did not match the host COI genealogy indicating disconnected biogeography patterns. The vesicomyid clam Abyssogena southwardae from 5°S shared an identical COI haplotype with A. southwardae from the Logatchev vent field on the northern MAR and their symbionts shared identical 16S phylotypes, suggesting gene flow across the Equator. Our results indicate genetic connectivity between the northern and southern MAR and suggest that a strict dispersal barrier does not exist.

  7. Brassica cover crops for nitrogen retention in the Mid-Atlantic coastal plain.

    PubMed

    Dean, Jill E; Weil, Ray R

    2009-01-01

    Brassica cover crops are new to the mid-Atlantic region, and limited information is available on their N uptake capabilities for effective N conservation. Forage radish (Raphanus sativus L. cv. Daikon), oilseed radish (Raphanus sativus L. cv. Adagio), and rape (Brassica napus L. cv. Dwarf Essex) were compared with rye (Secale cereale L. cv. Wheeler), a popular cover crop in the region, with regard to N uptake ability and potential to decrease N leaching at two sites in Maryland. Plants were harvested in fall and spring for dry matter and N analysis. Soil samples from 0 cm to 105 to 180 cm depth were obtained in fall and spring for NH(4)-N and NO(3)-N analyses. Ceramic cup tension lysimeters were installed at depths of 75 to 120 cm to monitor NO(3)-N in soil pore water. Averaged across 3 site-years, forage radish and rape shoots had greater dry matter production and captured more N in fall than rye shoots. Compared with a weedy fallow control, rape and rye caused similar decreases in soil NO(3)-N in fall and spring throughout the sampled profile. Cover crops had no effect on soil NH(4)-N. During the spring on coarse textured soil, pore water NO(3)-N concentrations in freeze-killed Brassica (radish) plots were greater than in control and overwintering Brassica (rape) and rye plots. On fine textured soil, all cover crops provided a similar decrease in pore water NO(3)-N concentration compared with control. On coarse textured soils, freeze-killed Brassica cover crops should be followed by an early-planted spring main crop.

  8. Chemosynthetic microbial activity at Mid-Atlantic Ridge hydrothermal vent sites

    NASA Astrophysics Data System (ADS)

    Wirsen, Carl O.; Jannasch, Holger W.; Molyneaux, Stephen J.

    1993-06-01

    Chemosynthetic production of microbial biomass, determined by 14CO2 fixation and enzymatic (RuBisCo) activity, at the Mid-Atlantic Ridge (MAR) 23° and 26°N vent sites was found in various niches: warm water emissions, loosely rock-attached flocculent material, dense morphologically diverse bacterial mats covering the surfaces of polymetal sulfide deposits, and filamentous microbes on the carapaces of shrimp (Rimicaris exoculata). The bacterial mats on polymetal sulfide surfaces contained unicellular and filamentous bacteria which appeared to use as their chemolithotrophic electron or energy source either dissolved reduced minerals from vent emissions, mainly sulfur compounds, or solid metal sulfide deposits, mainly pyrite. Moderately thermophilic Chemosynthetic activity was observed in carbon dioxide fixation experiments and in enrichments, but no thermophilic aerobic sulfur oxidizers could be isolated. Both obligate and facultative chemoautotrophs growing at mesophilic temperatures were isolated from all chemosynthetically active surface scrapings. The obligate autotrophs could oxidize sterilized MAR natural sulfide deposits as well as technical pyrite at near neutral pH, in addition to dissolved reduced sulfur compounds. While the grazing by shrimp on the surface mats of MAR metal sulfide deposits was observed and deemed important, the animals' primary occurrence in dense swarms near vent emissions suggests that they were feeding at these sites, where conditions for Chemosynthetic growth of their filamentous microbial epiflora were optimal. The data show that the transformation of geothermal energy at the massive polymetal sulfide deposits of the MAR is based on the lithoautotrophic oxidation of soluble sulfides and pyrites into microbial biomass.

  9. Distribution of Seismicity and thermal structure at Lucky Strike Hydrothermal Segment of Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Rai, A.; Singh, S. C.; Crawford, W. C.; Escartin, J.; Cannat, M.; Seher, T.

    2009-12-01

    The Lucky-strike segment (37.2 deg. N), located at the slow-spreading Mid-Atlantic Ridge (MAR) south of the Azores hot-spot, is characterized by a large hydrothermal field underlain by a 3-km deep magma chamber. To study the seismic activity in the Lucky-strike segment, four short-period and one broad-band ocean-bottom seismometers (OBSs) were deployed in a diamond shape at an spacing of 4.5 km, and centered at the hydrothermal field. These five OBSs recorded two horizontal, one vertical and one pressure channels, over a period of 13 months (06/08-08/09) as a part of the BBMOMAR experiment. All the five equipments have recorded large number of micro-earthquakes, earthquake swarms and teleseismic earthquakes. Here, we present the preliminary analysis of distribution of micro-seismicity in and around the Lucky-strike segment. We have detected about 6000 earthquakes to date. Out of these, we have located about 800 earthquakes which have been recorded by at-least four equipments with clear P- and S- arrivals. The distribution of earthquakes show a concentration of events at both inside corners North and South of the Lucky Strike segment, reaching maximum depths of more than 10 km, and a relative low number of events at the segment center, below the central volcano, with maximum depths reaching only 6 km. We have also identified several swarm activity in the region. This study will be extended to include the new data of 8/08-9/09 time period, after recovery and redeployment of instruments during the BATHYLUCK09 cruise. These additional data will thus provide the best constraints to date on the thermal structure throughout the segment and around the magma chamber at its center, and intern on the links between hydrothermal activity and deformation of the oceanic lithosphere at this site.

  10. Seismic structure of the U.S. Mid-Atlantic continental margin

    NASA Astrophysics Data System (ADS)

    Holbrook, W. Steven; Purdy, G. M.; Sheridan, R. E.; Glover, L., III; Talwani, M.; Ewing, J.; Hutchinson, D.

    1994-09-01

    Multichannel and wide-angle seismic data collected off Virginia during the 1990 EDGE Mid-Atlantic seismic experiment provide the most detailed image to date of the continent-ocean transition on the U.S. Atlantic margin. Multichannel data were acquired using a 10,800 cu inch (177 L) airgun array and 6-km-long streamer, and coincident wide-angle data were recorded by ten ocean bottom seismic instruments. A velocity model constructed by inversion of wide-angle and vertical-incidence travel times shows strong lateral changes in deep-crustal structure across the margin. Lower-crustal velocities are 6.8 km/s in rifted continental crust, increase to 7.5 km/s beneath the outer continental shelf, and decrease to 7.0 km/s in oceanic crust. Prominent seaward- dipping reflections comprise a 100-km-wide, 25-km-thick ocean- continent transition zone that consists almost entirely of mafic igneous material accreted to the margin during continental breakup. The boundary between rifted continental crust and this thick igneous crust is abrupt, occupying only about 20 km of the margin. Appalachian intracrustal reflectivity largely disappears across this boundary as velocity increases from 5.9 km/s to greater than 7.0 km/s, implying that the reflectivity is disrupted by massive intrusion and that very little continental crust persists seaward of the reflective crust persists seaward of the reflective crust. The thick igneous crust is spatially correlated with the East Coast magnetic anomaly, implying that the basalts and underlying intrusives cause the anomaly. The details of the seismic structure and lack of independent evidence for an appropriately located hotspot in the central Atlantic imply that nonplume processes are responsible for the igneous material.

  11. Population genetic structure of the abyssal grenadier (Coryphaenoides armatus) around the mid-Atlantic ridge

    NASA Astrophysics Data System (ADS)

    Ritchie, H.; Cousins, N. J.; Cregeen, S. J.; Piertney, S. B.

    2013-12-01

    Understanding the factors that affect the levels and distribution of genetic diversity in oceanic and deep sea environments is a central focus in marine population genetics. Whilst it has been considered that the oceans represent a homogenous environment that would facilitate dispersal and minimise population structure, it is now clear that topographical features and current patterns can influence the extent of spatial gene flow and promote significant population genetic divergence even at local scales. Here we examine patterns of population genetic structure among N. Atlantic populations of the cosmopolitan abyssal grenadier Coryphaenoides armatus in relation to two hypothesised barriers to gene flow-the mid-Atlantic Ridge and the Charlie-Gibbs Fracture Zone/Sub-Polar Front. A suite of microsatellite markers were developed to examine the spatial pattern of allelic variation among 210 individuals from ten sampling locations encompassing sites east and west of the MAR and north and south of the CGFZ, plus a geographically distinct sample of individuals from the Crozet Islands in the Indian Ocean. Considerable genetic diversity was detected among individuals (na=5-13 and HO=0.46-0.69 across populations) but with an overall lack of genetic divergence between populations. Pairwise estimates of divergence among NE Atlantic samples were small and non-significant (max FST=0.04) and Structure-based Bayesian analysis of genetic clusters returned no distinct population structure. The only indication of genetic structure was between the Atlantic and Indian Oceans, with FST estimates of ca. 0.05. Patterns of genetic diversity and divergence are discussed in relation to what has been resolved in Coryphaenoides congeners, and what is known about the life history and ecology of C. armatus.

  12. Temporal trends in nitrate and selected pesticides in mid-atlantic ground water

    USGS Publications Warehouse

    Debrewer, L.M.; Ator, S.W.; Denver, J.M.

    2008-01-01

    Evaluating long-term temporal trends in regional ground-water quality is complicated by variable hydrogeologic conditions and typically slow flow, and such trends have rarely been directly measured. Ground-water samples were collected over near-decadal and annual intervals from unconfined aquifers in agricultural areas of the Mid-Atlantic region, including fractured carbonate rocks in the Great Valley, Potomac River Basin, and unconsolidated sediments on the Delmarva Peninsula. Concentrations of nitrate and selected pesticides and degradates were compared among sampling events and to apparent recharge dates. Observed temporal trends are related to changes in land use and chemical applications, and to hydrogeology and climate. Insignificant differences in nitrate concentrations in the Great Valley between 1993 and 2002 are consistent with relatively steady fertilizer application during respective recharge periods and are likely related to drought conditions in the later sampling period. Detecting trends in Great Valley ground water is complicated by long open boreholes characteristic of wells sampled in this setting which facilitate significant ground-water mixing. Decreasing atrazine and prometon concentrations, however, reflect reported changes in usage. On the Delmarva Peninsula between 1988 and 2001, median nitrate concentrations increased 2 mg per liter in aerobic ground water, reflecting increasing fertilizer applications. Correlations between selected pesticide compounds and apparent recharge date are similarly related to changing land use and chemical application. Observed trends in the two settings demonstrate the importance of considering hydrogeology and recharge date along with, changing land and chemical uses when interpreting trends in regional ground-water quality. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  13. National Assessment of Shoreline Change; historical shoreline change along the New England and Mid-Atlantic coasts

    USGS Publications Warehouse

    Hapke, Cheryl J.; Himmelstoss, Emily A.; Kratzmann, Meredith G.; List, Jeffrey H.; Thieler, E. Robert

    2011-01-01

    Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of this study, the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the New England and Mid-Atlantic coasts is the fifth in a series of reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the Gulf of Mexico, the Southeast Atlantic, and, for California, the sandy shoreline and the coastal cliffs. The rates of change presented in this report represent conditions up to the date of the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. Because of the geomorphology of the New England and Mid-Atlantic (rocky coastlines, large embayments and beaches) as well as data gaps in some areas, this report presents beach erosion rates for 78 percent of the 1,360 kilometers of the New England and Mid-Atlantic coasts. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long

  14. Unexpected Widespread Detachment Faulting During Formation of Lithosphere at the Northern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Smith, D. K.; Schouten, H.; Escartin, J.; Cann, J. R.

    2007-12-01

    The region of the Mid-Atlantic Ridge (MAR) near 13N displays the topographic characteristics of prevalent and vigorous tectonic extension. Normal faults show large amounts of rotation, dome-shaped corrugated detachment surfaces (core complexes) intersect the seafloor within the inner valley floor, and dead core complexes cover the seafloor off-axis. Steep outward facing slopes indicate that the footwalls of many of the normal faults have rotated by more than 30 degrees suggesting at least 3 km of extension. The rotation occurs very close to the ridge axis and produces distinctive linear ridges with roughly symmetrical slopes. This morphology is very different from linear abyssal hill faults formed at magmatic sections of the ridge which display a smaller amount of backtilt (typically less than 15 degrees implying 1-1.5 km of extension). We suggest that the severe backtilt of faults is diagnostic of a region undergoing large amounts of tectonic extension on single faults. If faults are long-lived (more than 5 km extension) a dome-shaped corrugated surface develops in front of the ridges and lower crustal and upper mantle rocks are exposed. We have applied our understanding of the 13N region to the northern MAR between 15 and 35N and find up to15 ridge segments dominated by extreme fault rotation and core complex exhumation. Core complexes are not limited to inside corners of ridge-transform intersections but may occur anywhere along the length of a segment. A single ridge segment can have several active core complexes, some less than 25 km apart that are separated by swales. We present two models for multiple core complex formation: a continuous model in which a single detachment surface extends along axis to include all of the core complexes and swales, and a discontinuous model in which local detachment faults form the core complexes and magmatic spreading forms the intervening swales. Either model can explain the morphology that we observe. If there is a

  15. Upper mantle heterogeneity below the Mid-Atlantic Ridge, 0°-15°N

    NASA Astrophysics Data System (ADS)

    Bonatti, E.; Peyve, A.; Kepezhinskas, P.; Kurentsova, N.; Seyler, M.; Skolotnev, S.; Udintsev, G.

    1992-04-01

    Small-scale variations in composition of mantle-derived peridotites have been investigated in the 0°-15°N portion of the Mid-Atlantic Ridge (MAR), thanks to a relatively close-spaced peridotite sample coverage achieved by combining samples collected by Russian and U.S. expeditions. Areal variations in the composition of mantle-equilibrated minerals olivine, orthopyroxene, clinopyroxene, and spinel have been interpreted as due primarily to regional variations in the initial composition, degree of partial melting, and thermal structure of the upper mantle. Mantle rocks from the eastern part of the Romanche transform frequently contain a trapped fraction of basaltic melt, while undepleted mantle prevails in the western part of the Romanche, suggesting a "cold" upper mantle thermal regime in this region, which prevented significant melting. Immediately to the north, the St. Paul Fracture Zone (FZ) upper mantle shows intermediate degrees of melting, except for St. Peter-Paul Island which exposes metasomatized mantle rocks chemically and isotopically different from other oceanic peridotites. Between St. Paul FZ and 4°N (Strakhov FZ) we have an area of strongly depleted upper mantle. Farther north the Doldrums FZ area (˜8°N) appears to be underlain by moderately depleted upper mantle with some melt entrapment. The Vema FZ (11°N) is underlain by relatively homogenous upper mantle which has undergone a rather low degree of melting. The Mercurius and Marathon transforms (between 12° and 13°N) expose moderately depleted peridotites. Finally, the 15°20' FZ area shows relatively undepleted upper mantle on the northern side of the transform and at sites distant from the MAR axis and strongly depleted mantle south of the transform. The strongly depleted mantle from the 2°-3°N and 14°-15°N regions is associated spatially with light rare earth element enriched mid-ocean ridge basalt showing a "hot spot"-type geochemical signature. The areal association of refractory

  16. Origin of major element chemical trends in DSDP Leg 37 basalts, Mid-Atlantic Ridge

    USGS Publications Warehouse

    Byerly, G.R.; Wright, T.L.

    1978-01-01

    In this paper we summarize the major element chemical variation for basalts from the Deep Sea Drilling Project Leg 37 and relate it to stratigraphic position in each of five drilling sites. Least-squares techniques are successfully used to quantify the nature and extent of alteration in these basalts, and to correct the major element analysis back to a magmatic, or alteration-free, composition on the assumption that alteration takes place in two ways: (1) secondary minerals are introduced into veins and vesicles, and (2) CO2 and H2O react with components in the rock to form a simple alteration assemblage. A chemical stratigraphy is defined for these basalts by grouping lavas whose chemistries are related by low-pressure phenocryst-liquid differentiation as identified by least-squares calculation. Major chemical-stratigraphic units are as much as 200 m thick; correlations of these units can be made between the holes at site 332 (about 100 m apart), but not between the other sites. Compositions of parental magmas are calculated by extrapolating low-pressure variations to a constant value of 9% MgO. The differences in these extrapolated compositions reflect high-pressure processes, and suggest that clinopyroxene may be an important phase in either intermediate-level fractionation of basaltic liquids, or as a residual phase during the partial melting which produces these basaltic liquids. Several of the basaltic liquids calculated as parental to the Leg 37 basalts have CaO contents greater than 14% and indicate that the oceanic mantle is richer in CaO and Al2O3 than values used in pyrolite models for the upper mantle. A model for magma generation and eruption beneath the Mid-Atlantic Ridge embodies the following characteristics: 1. (1) Separate magma batches are generated in the mantle. 2. (2) Each of these may be erupted directly or stored at shallow depth where significant fractionation takes place. Common fractionation processes are inferred to be gravitative

  17. Spatiotemporal relationships between earthquakes of the mid-Atlantic Ridge and the Atlantic continental margins

    NASA Astrophysics Data System (ADS)

    Bolarinwa, Oluwaseyi J.

    The seismicity of the mid Atlantic Ridge (MAR) was compared in space and time with the seismicity along the Atlantic continental margins of Europe, Africa, North America, the Carribean and South America in a bid to appraise the level of influence of the ridge push force at the MAR on the Atlantic coastal seismicity. By analyzing the spatial and temporal patterns of many earthquakes (along with the patterns in their stress directions) in diverse places with similar tectonic settings, it is hoped that patterns that might be found indicate some of the average properties of the forces that are causing the earthquakes. The spatial analysis of the dataset set used shows that areas with higher seismic moment release along the north MAR spatially correlate with areas with relatively lower seismic moment release along the north Atlantic continental margins (ACM) and vice versa. This inverse spatial correlation observed between MAR seismicity and ACM seismicity might be due to the time (likely a long time) it takes stress changes from segments of the MAR currently experiencing high seismic activity to propagate to the associated passive margin areas presently experiencing relatively low seismic activity. Furthermore, the number of Atlantic basin and Atlantic coast earthquakes occurring away from the MAR is observed to be independent of the proximity of earthquake's epicenters from the MAR axis. The effect of local stress as noted by Wysession et al. (1995) might have contributed to the independence of Atlantic basin and Atlantic coast earthquake proximity from the MAR. The Latchman (2011) observation of strong earthquakes on a specific section of the MAR being followed by earthquakes on Trinidad and Tobago was tested on other areas of the MAR and ACM. It was found that that the temporal delay observed by Latchman does not exist for the seismicity along other areas along the MAR and ACM. Within the time window used for this study, it appears that seismicity is occurring

  18. Heat and Volume Fluxes at the Turtle Pits Vent Site, southern Mid Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Köhler, Janna; Walter, Maren; Mertens, Christian; Sültenfuß, Jürgen; Rhein, Monika

    2010-05-01

    The Turtle Pits vent site consists of eight known high temperature vents and several diffuse vent sites which are distributed over three hydrothermal fields: Turtle Pits, Comfortless Cove, and Red Lion. These vent fields are located in a north-south orientated rift valley at the Mid-Atlantic Ridge (MAR) near 5°S. The total volume and heat emissions of the entire Turtle Pits site have been calculated with three different approaches using data collected during a Meteor cruise in May 2006 and a L'Atalante cruise in January 2008. The data sets consist of vertical profiles and towed transects of temperature, salinity, and turbidity, as well as direct velocity measurements with a lowered acoustic Doppler current profiler (LADCP) and water samples for Helium isotope analysis. Vent fluid samples for noble gas analysis where taken with ROVs. Since the vent fluid is highly enriched in primordial 3He this noble gas can be used as a conservative tracer for vent fluid. The geographical setting of the vent site confines the particle plume to the rift valley since the depth of the valley exceeds the rise height of the plume. Therefore the fluxes of heat and volume can be estimated from the horizontal helium transport in the valley in combination with a mean 3He endmember concentration determined from the water samples taken with the ROVs. The comparison of the 3He concentrations measured south of the hydrothermal vents with the 3He signal north of the hydrothermal vents suggests a rather strong northward flow. This is confirmed by the tide corrected velocities observed with the LADCP during the Meteor cruise. The northward volume transport has been calculated using the local bathymetry and tide corrected velocities from the Meteor cruise. In combination with the 3He concentrations and the average 3He endmember concentration a flux of 1000 l/s is estimated, which corresponds to a heat flux of 1400 MW. The measured temperature anomalies within the plume combined with the known

  19. Degassing and contamination of noble gases in Mid-Atlantic Ridge basalts

    NASA Astrophysics Data System (ADS)

    Burnard, P.; Harrison, D.; Turner, G.; Nesbitt, R.

    2003-01-01

    New He, Ne, Ar and CO2 stepped-crushing data from the Mid-Atlantic Ridge show that contamination of basalts by atmospheric noble gases involves three or more components: unfractionated air, fractionated air with high 36Ar/22Ne (≥45) and fractionated air with low 36Ar/22Ne (≤5). In addition, the magmatic noble gases trapped in these basaltic glasses are variably fractionated such that 4He/40Ar* (where the asterisk indicates corrected for atmospheric contamination based on all 36Ar being atmospheric in origin) is in the range 3-12. Single samples have a range in 4He/40Ar* with the highest ratios in the final crush steps, consistent with the most fractionated (highest 4He/40Ar*) volatiles trapped in the smallest vesicles. It is not possible to distinguish between batch and Rayleigh degassing mechanisms. The complexities of the contamination and magmatic fractionation processes means that it is not possible to estimate 40Ar/36Ar of the mantle source to these basalts other than it must be higher than the highest ratio measured (26,200 ± 5200). Noble gas/CO2 ratios are also variable. While some CO2 adsorption during crushing exaggerates the variations in He/CO2 and Ar/CO2, we show that it is not possible to account for the entire variation as an analytical artefact: some of the variation is present in the vesicles. Variations in He/CO2 cannot be attributed to solubility controlled degassing because of the broadly similar solubilities of He and CO2 in tholeiitic magmas. The large range in He/CO2 in these glasses (factor of 10) is not accompanied by indications of major changes in melting regime or source region chemistry, therefore is thought to reflect late-stage (magmatic) fractionation of CO2 from the noble gases. It is not possible to identify an explicit mechanism, although both CO2 reduction (e.g., to hydrocarbons or graphite) and kinetic CO2-noble gas fractionation could account for the variations.

  20. Hydrothermal Activity and Volcanism on the Southern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Haase, K. M.; Scientific Party, M.

    2005-12-01

    In April 2005 four recently discovered different hydrothermal fields on the slow-spreading Mid-Atlantic Ridge (MAR) south of the Equator were studied and sampled using a remotely operated vehicle (ROV) during cruise METEOR 64/1. Three of these hydrothermally active fields (called Turtle Pits, Red Lion, and Wideawake) occur at about 3000 m water depth in the centre of a MAR segment at 4° 48'S which appears to be volcanically very active. The youngest lava flow partly covers the low-temperature, diffuse flow Wideawake mussel field and is thus probably only a few years old. The high-temperature Turtle Pits hydrothermal field with four active vent structures lies some 300 m west of the diffuse vent field and is characterized by boiling fluids with temperatures close to 400° C. The mineral assemblage recovered from inactive hydrothermal mounds includes massive magnetite+hematite+sulfate and differs from that of the presently active vents and indicates more oxidizing conditions during the earlier activity. The vent fluids at Turtle Pits contain relatively high contents of hydrogen which may have formed during iron oxidation processes when basaltic magmas crystallized. The high fluid temperatures, the change to more reducing conditions, and the relatively high hydrogen contents in the fluids are most likely due to the ascent of magmas from the mantle that fed the very recent eruption. The high-temperature Red Lion hydrothermal field lies some 2 km north of the Turtle Pits field and consists of at least four active black smokers surrounded by several inactive sulfide mounds. The composition of the Red Lion fluids differs significantly from the Turtle Pits fluids, possibly owing largely to a difference in the temperature of the two systems. The fourth hydrothermally active field on the southern MAR, the Liliput field, was discovered near 9° 33'S in a water depth of 1500 m and consists of several low-temperature vents. A shallow hydrothermal plume in the water column

  1. The seismicity of the equatorial Mid-Atlantic Ridge and its long-offset transforms

    NASA Astrophysics Data System (ADS)

    Smith, D. K.; Dziak, R. P.; Palmiotto, C.; Parnell-Turner, R. E.; Zheleznov, A.

    2012-12-01

    An array of eight hydrophones is monitoring seismicity of the equatorial Atlantic between 20N and 10S. The array is obtaining a two-year, continuous record of seismicity, which will provide an important new view of the spatial and temporal patterns of seismicity at the slow-spreading equatorial Mid-Atlantic Ridge (MAR) and its long-offset transforms. The hydroacoustically-recorded seismicity, which will be in hand in 2014, can be used to address several key questions concerning the modes of spreading along the strongly offset equatorial MAR, the short-term earthquake predictability on some of the longest transform faults in the oceans, and the dynamics of the NA-SA-AF triple junction whose exact location is not known. In addition, seismic patterns of the entire South Atlantic will be obtained (at reduced location accuracy), and will aid in understanding the dynamics of the southern MAR, Walvis Ridge, Rio Grande Rise, and other prominent seafloor features. The hydroacoustic data will also allow characterization of cetacean populations in the region as well as an assessment of the ambient noise levels due to shipping and oil exploration. To provide additional information on the short-term earthquake predictability (retrospective) on oceanic transform faults, we are identifying all magnitude mb >5 earthquakes in our existing hydroacoustic databases and searching for systematic foreshock activity associated with these events. We have multi-year earthquake databases accumulated from past hydrophone experiments along the Central, Southwest and Southeast Indian Ridges, the Juan de Fuca Ridge system, and the northern MAR. Preliminary results are very promising, and there appear to be several examples of clear foreshocks preceding mainshocks by several hours. Also as part of this project, we are compiling a bathymetric map of the equatorial MAR and its transforms between 20N and 10S. There have been several international mapping efforts in this region and the integration of

  2. Sea-level in the U.S. mid-Atlantic coast during the Common Era

    NASA Astrophysics Data System (ADS)

    Shaw, Timothy; García-Artola, Ane; Engelhart, Simon; Kemp, Andrew; Cahill, Niamh; Nikitina, Daria; Corbett, Reide; Brain, Matthew; Vane, Christopher; Walker, Jennifer; Pilarczyk, Jessica; Clear, Jennifer; Horton, Benjamin

    2016-04-01

    Understanding of Common Era sea-level change is fragmentary compared to understanding of temperature variability, for which several global syntheses have been generated. This limitation prevents accurate assessment of the Common Era relationship between temperature and global mean sea level (GMSL), including the sea-level response to climate phases such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Previous records of relative sea-level (RSL) change along the U.S. Atlantic coast during the Common Era have revealed spatial and temporal variability that reflects differences in the static-equilibrium effects of land ice changes and/or to ocean dynamic effects. Here we present two new RSL records spanning the Common Era from saltmarsh sites in the Delaware Bay and Chesapeake Bay. Motivation for this work stems from discrepancies in the timing and magnitude of sea-level changes for the mid-Atlantic coast. This region also experiences some of the highest rates of 20th century RSL change (up to ~5 mm/yr) along the U.S. Atlantic Coast. At Delaware Bay and Chesapeake Bay, extensive stratigraphic surveys revealed thick sequences of salt-marsh peat ideally suited to proxy-based RSL reconstructions utilizing foraminifera. Estimates of paleo marsh elevation were provided through contemporary training sets incorporating modern analogues from the full range of intertidal environments and subtracted from surveyed altitudes to provide RSL trends. Temporal constraints on sea-level changes were incorporated into a Bayesian framework using a composite chronology composed of AMS radiocarbon dating, short-lived radionuclides, regional pollution histories and pollen chronohorizons documenting land clearance events. The reconstructions showed a similar pre-instrumental RSL rise of ~1.1 - 1.6 mm/yr in Delaware Bay and Chesapeake Bay, respectively. The rate of RSL rise in both regions during the past ~130 years coincides with the increased rate observed in instrumental

  3. The Distribution and Abundance of Mercury Methylating Microorganisms in Mid-Atlantic Wetlands

    NASA Astrophysics Data System (ADS)

    Santillan, E. F. U.; Gilmour, C. C.; Schwartz, G.; Christensen, G. A.; King, A. J.; Elias, D. A.

    2015-12-01

    The discovery of the genes responsible for microbial methylmercury production, hgcAB, has led to the identification of novel Hg methylators with diverse metabolisms including Fe and SO42- reducing bacteria, syntrophs, and methanogens. We recently developed DNA probes for hgcA in each group of methylators: Deltaproteobacteria, Firmicutes, and Archaea [Christensen, 2015]. In this study, we use the probes to determine quantity and distribution of hgcA+ organisms in mid-Atlantic marshes and sediments, and in Hg-contaminated wetland soils. We also analyze hgcA distribution over a 28-day soil slurry experiment designed to evaluate the impact of activated carbon on Hg methylation and demethylation [Gilmour, 2015]. Initial soils show Deltaproteobacteria comprise most hgcA+ organisms. Methanogens encompass >45% of the remaining methylators. The addition of SO42- to induce SO42- reducing conditions in slurries caused the number of hgcA+ Deltaproteobacteria to increase and the number of hgcA+ methanogens to decrease to >32%. In soils and slurries, Firmicutes were below detection, suggesting our Firmicute primers are either unrepresentative in natural samples, or that hgcA+ Firmicutes are rare. This observation is interesting as Firmicutes include organisms with divergent metabolisms, and their role in environmental methylation is still unknown. Slurries also show no correlation between hgcA abundance and Hg concentrations. We now plan to explore how hgcA abundance relates to Hg-methylation and electron acceptor availability. Our results offer initial insights into the natural distribution of hgcA, supporting the idea that the distribution of different methylators is related to electron acceptors and redox chemistry. Christensen, G., Wymore, AM, King, A, Pdar, M, Hurt Jur, RA, Santillan, EFU, Gilmour, CC, Brandt, CC, Brown, SD, Palumbo, AV, Elias, DA (2015), A Study of Mercury Methylation Genetics: Qualitative and Quantitative Analysis of hgcAB in Pure Culture, paper presented

  4. Potential effects of climate change on freshwater ecosystems of the New England/Mid-Atlantic Region

    USGS Publications Warehouse

    Moore, M.V.; Pace, M.L.; Mather, J.R.; Murdoch, Peter S.; Howarth, R.W.; Folt, C.L.; Chen, C.-Y.; Hemond, Harold F.; Flebbe, P.A.; Driscoll, C.T.

    1997-01-01

    Numerous freshwater ecosystems, dense concentrations of humans along the eastern seaboard, extensive forests and a history of intensive land use distinguish the New England/Mid-Atlantic Region. Human population densities are forecast to increase in portions of the region at the same time that climate is expected to be changing. Consequently, the effects of humans and climatic change are likely to affect freshwater ecosystems within the region interactively. The general climate, at present, is humid continental, and the region receives abundant precipitation. Climatic projections for a 2 ??CO2 atmosphere, however, suggest warmer and drier conditions for much of this region. Annual temperature increases ranging from 3-5??C are projected, with the greatest increases occurring in autumn or winter. According to a water balance model, the projected increase in temperature will result in greater rates of evaporation and evapotranspiration. This could cause a 21 and 31% reduction in annual stream flow in the southern and northern sections of the region, respectively, with greatest reductions occurring in autumn and winter. The amount and duration of snow cover is also projected to decrease across the region, and summer convective thunderstorms are likely to decrease in frequency but increase in intensity. The dual effects of climate change and direct anthropogenic stress will most likely alter hydrological and biogeochemical processes, and, hence, the floral and faunal communities of the region's freshwater ecosystems. For example, the projected increase in evapotranspiration and evaporation could eliminate most bog ecosystems, and increases in water temperature may increase bioaccumulation, and possibly biomagnification, of organic and inorganic contaminants. Not all change may be adverse. For example, a decrease in runoff may reduce the intensity of ongoing estuarine eutrophication, and acidification of aquatic habitats during the spring snowmelt period may be

  5. Methanethiol abundance in high-temperature hydrothermal fluids from the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Reeves, E.; Seewald, J. S.; Saccocia, P.; van der Meer, M.

    2008-12-01

    The formation of aqueous organic sulfur compounds in hydrothermal systems remains poorly constrained, despite their potential significance in 'prebiotic' chemistry and the origin of life. The simplest - methanethiol (CH3SH) - has been implicated as a critical abiogenic precursor to the establishment of primitive microbial metabolism in early Earth hydrothermal settings. It also represents a readily-utilized substrate for microbial sulfate-reducing communities and a potential intermediate species in abiotic CH4 formation. To assess the abundance of CH3SH and factors regulating its stability under hydrothermal conditions we measured CH3SH concentrations in a suite of hydrothermal fluids collected from the Rainbow, Lucky Strike, TAG and Lost City hydrothermal sites located on the Mid-Atlantic Ridge. Fluids were collected using isobaric gas-tight samplers and analyzed for CH3SH by shipboard purge-and-trap gas chromatography. Measured concentrations at Rainbow (1.2 -- 223nM), Lucky Strike (1.1 -- 26nM), TAG (8.5 -- 11nM) and Lost City (1.6 -- 3.0nM) are all substantially lower than predicted for thermodynamic equilibrium with CO2, H2 and H2S at measured vent conditions. The highest concentrations (91 -- 223nM), however, were observed at Rainbow in intermediate temperature (128 -- 175°C) H2-rich fluids that may have undergone conductive cooling. Increased concentrations with decreasing temperature is consistent with the thermodynamic drive for the formation from CO2, suggesting a possible abiotic origin for CH3SH in some fluids. Substantially lower concentrations in the low temperature fluids at Lost City are consistent with the extremely low levels of CO2 and H2S in these fluids. Other possible sources of CH3SH to vent fluids must be considered, however, and include thermal alteration of biomass present in low-temperature environments and microbial consortia that produce CH3SH as a byproduct of anaerobic methane oxidation. Current models for the emergence of primordial

  6. The geochemical controls on vent fluids from the Lucky Strike vent field, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Von Damm, K. L.; Bray, A. M.; Buttermore, L. G.; Oosting, S. E.

    1998-08-01

    Hydrothermal vent fluids were collected from the Lucky Strike site at 37°17'N on the Mid-Atlantic Ridge in both 1993 and 1996. Seven vents were sampled with the DSV Alvin in 1993 and six vents were sampled in 1996 using the ROV Jason during the LUSTRE '96 Cruise. As three of the vents were sampled in both 1993 and in 1996, a time series of vent fluid chemistry is also reported. Measured temperatures ranged from 202 to 333°C at the 1618-1726 m depth of the vent field, which is located on Lucky Strike Seamount. These fluids are either equal to or less than the local bottom seawater in chlorinity. While the range in fluid compositions at Lucky Strike is generally within that observed elsewhere, the unusual aspects of the fluid chemistries are the relatively high pH and low Fe, Mn, Li and Zn. We attribute this, as well as an usually low Sr/Ca ratio, to reaction with a highly altered substrate. The high Si and Cu contents suggest a deep, as well as hot, source for these fluids. The fluid compositions therefore suggest formation by super-critical phase separation at a depth not less than 1300 m below the seafloor, and reaction with a relatively oxic, and previously altered, substrate. There is temporal variability in some of the vent fluid compositions as Li, K, Ca and Fe concentrations have increased in some of the vents, as has the Fe/Mn (molar) ratio, although the chlorinities have remained essentially constant from 1993 to 1996. While there is not a simple relationship between vent fluid compositions (or temperatures) and distance from the lava lake at the summit of the seamount, the vent fluids from many of the vents can be shown to be related to others, often at distances >200 m. The most southeasterly vents (Eiffel Tower and the Marker/Mounds vents) are distinct in chlorinity and other chemical parameters from the rest of the vents, although closely related to each other within the southeastern area. Similarly all of the vents not in this one area, appear

  7. Simulation of the 1979 spring bloom in the Mid-Atlantic Bight - A coupled physical/biological/optical model

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Walsh, John J.

    1992-01-01

    A coupled physical/biological/optical model is developed for studies of phytoplankton variability in the spring 1979 Mid-Atlantic Bight, as observed by CZCS imagery. The model incorporates advection, mixing, sinking, growth as a function of light, temperature, nutrient availability, and death as a function of ingestion. It produced chlorophyll concentrations within the first attenuated depth within 1 standard deviation of CZCS imagery on large scale. The primary production estimates obtained using this model were within reasonable agreement with those measured in situ.

  8. Nested rain cell contour statistics derived from radar measurements in the mid-Atlantic coast of the United States

    NASA Technical Reports Server (NTRS)

    Goldhirsh, Julius; Musiani, Bert H.

    1991-01-01

    During a period spanning more than 5 years, a series of low elevation rain radar measurements encompassing 17 rain days were systematically executed in the mid-Atlantic coast of the United States. Drop size distribution measurements with a nearby disdrometer were also acquired during the same rain days. The drop size data were utilized to convert the radar reflectivity factors to estimated rain rates for the respective rain days of operation. Applying developed algorithms to the radar and disdrometer data, 'core' values of rain intensities and nested families of rain rate isopleths enveloping them were identified and their equi-circle diameters were statistically analyzed.

  9. Inventory of non-federally funded marine pollution research, development and monitoring activities: Northeast and Mid-Atlantic Region

    SciTech Connect

    Caton, G.M.; Opresko, D.M.; Weaver, R.S.

    1985-12-01

    The Northeast and Mid-Atlantic inventory includes marine-pollution projects conducted in or are related to the states of Virginia, Maryland, Delaware, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, and Maine. Projects related to outer continental shelf, oceanic, coastal, and estuarine areas are included. Some projects related to freshwater areas are also included where these were conducted for the purpose of determining sources of pollutants in estuarine and coastal areas or the effects on the marine environment resulting from changes in freshwater areas.

  10. Sociocultural dimensions of supply and demand for natural aggregate; examples from the Mid-Atlantic region, United States

    USGS Publications Warehouse

    Robinson,, Gilpin R.; Brown, William M.

    2002-01-01

    The United States uses large quantities of natural aggregate to build and maintain a continuously expanding infrastructure. In recent years, per capita demand for aggregate in the United States has grown to about 9.7 metric tons (10.7 tons) per person per year. Over the next 25 years, the aggregate industry expects to mine quantities equivalent to all aggregate mined in the United States over the past 100 years. The issues surrounding supply and demand for aggregate in the mid-Atlantic states of Maryland, Pennsylvania, Virginia, and West Virginia illustrate competing requirements for industrial minerals and many simultaneous social and environmental objectives.

  11. Flows of Antarctic bottom water through fractures in the southern part of the North Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Morozov, E. G.; Tarakanov, R. Yu.; Makarenko, N. I.

    2015-11-01

    We study the flows of bottom waters of the Antarctic origin in deep fracture zones of the southern part of the North Mid-Atlantic Ridge. In the autumn of 2014, an expedition onboard the RV Akademik Sergey Vavilov carried out measurements of current velocities and thermohaline properties of bottom water in several quasi-zonal fractures in the southern part of the Northern Mid-Atlantic Ridge, which connect the deep basins of the West and East Atlantic, the Vema Fracture Zone (FZ) (10°50' N) and a group of sub-equatorial fractures: Doldrums (8°15' N), Vernadsky (7°40' N), and a nameless fracture at 7°30' N. The estimates of bottom water (θ < 2.0°C) transport through this group based on measurements from 2014 are approximately 0.28 Sv (1 Sv = 106 m3/s), which is close to 25% of the transport estimate through the Vema FZ (1.20 Sv) obtained in the same expedition. The coldest bottom water temperatures among the investigated fractures were recorded in the Vema FZ.

  12. Widespread active detachment faulting and core complex formation near 13 degrees N on the Mid-Atlantic Ridge.

    PubMed

    Smith, Deborah K; Cann, Johnson R; Escartín, Javier

    2006-07-27

    Oceanic core complexes are massifs in which lower-crustal and upper-mantle rocks are exposed at the sea floor. They form at mid-ocean ridges through slip on detachment faults rooted below the spreading axis. To date, most studies of core complexes have been based on isolated inactive massifs that have spread away from ridge axes. Here we present a survey of the Mid-Atlantic Ridge near 13 degrees N containing a segment in which a number of linked detachment faults extend for 75 km along one flank of the spreading axis. The detachment faults are apparently all currently active and at various stages of development. A field of extinct core complexes extends away from the axis for at least 100 km. Our observations reveal the topographic characteristics of actively forming core complexes and their evolution from initiation within the axial valley floor to maturity and eventual inactivity. Within the surrounding region there is a strong correlation between detachment fault morphology at the ridge axis and high rates of hydroacoustically recorded earthquake seismicity. Preliminary examination of seismicity and seafloor morphology farther north along the Mid-Atlantic Ridge suggests that active detachment faulting is occurring in many segments and that detachment faulting is more important in the generation of ocean crust at this slow-spreading ridge than previously suspected.

  13. An off-axis hydrothermal vent field near the Mid-Atlantic Ridge at 30 degrees N.

    PubMed

    Kelley, D S; Karson, J A; Blackman, D K; Früh-Green, G L; Butterfield, D A; Lilley, M D; Olson, E J; Schrenk, M O; Roe, K K; Lebon, G T; Rivizzigno, P

    2001-07-12

    Evidence is growing that hydrothermal venting occurs not only along mid-ocean ridges but also on old regions of the oceanic crust away from spreading centres. Here we report the discovery of an extensive hydrothermal field at 30 degrees N near the eastern intersection of the Mid-Atlantic Ridge and the Atlantis fracture zone. The vent field--named 'Lost City'--is distinctly different from all other known sea-floor hydrothermal fields in that it is located on 1.5-Myr-old crust, nearly 15 km from the spreading axis, and may be driven by the heat of exothermic serpentinization reactions between sea water and mantle rocks. It is located on a dome-like massif and is dominated by steep-sided carbonate chimneys, rather than the sulphide structures typical of 'black smoker' hydrothermal fields. We found that vent fluids are relatively cool (40-75 degrees C) and alkaline (pH 9.0-9.8), supporting dense microbial communities that include anaerobic thermophiles. Because the geological characteristics of the Atlantis massif are similar to numerous areas of old crust along the Mid-Atlantic, Indian and Arctic ridges, these results indicate that a much larger portion of the oceanic crust may support hydrothermal activity and microbial life than previously thought.

  14. Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere.

    PubMed

    Bonatti, Enrico; Ligi, Marco; Brunelli, Daniele; Cipriani, Anna; Fabretti, Paola; Ferrante, Valentina; Gasperini, Luca; Ottolini, Luisa

    2003-05-29

    A 20-Myr record of creation of oceanic lithosphere is exposed along a segment of the central Mid-Atlantic Ridge on an uplifted sliver of lithosphere. The degree of melting of the mantle that is upwelling below the ridge, estimated from the chemistry of the exposed mantle rocks, as well as crustal thickness inferred from gravity measurements, show oscillations of approximately 3-4 Myr superimposed on a longer-term steady increase with time. The time lag between oscillations of mantle melting and crustal thickness indicates that the mantle is upwelling at an average rate of approximately 25 mm x yr(-1), but this appears to vary through time. Slow-spreading lithosphere seems to form through dynamic pulses of mantle upwelling and melting, leading not only to along-axis segmentation but also to across-axis structural variability. Also, the central Mid-Atlantic Ridge appears to have become steadily hotter over the past 20 Myr, possibly owing to north-south mantle flow.

  15. EPA Method 544: A Case Study in USEPA Drinking Water Method Develpment

    EPA Science Inventory

    The 1996 amendments to the Safe Drinking Water Act required the U.S. Environmental Protection Agency (USEPA) to establish a Drinking Water Contaminant Candidate List (CCL) of chemicals and microbes that the Agency will consider for future regulation. One of the key pieces of info...

  16. REMOVING ORGANIC CONTAMINANTS OF REGULATORY INTEREST WITH MEMBRANE PROCESSES: USEPA'S SCREENING STUDIES

    EPA Science Inventory

    The 1996 amendments to the Safe Drinking Water Act require the US Environmental Protection Agency (USEPA) to establish a list of unregulated microbiological and chemical contaminants to aid in priority-setting for the Agency's drinking water program. This list, known as the Cont...

  17. High resolution topography of the Rainbow hydrothermal area, Mid-Atlantic Ridge, 36° 14 N

    NASA Astrophysics Data System (ADS)

    Gente, P.; Thibaud, R.; Dyment, J.; Fouquet, Y.; Ildefonse, B.; Hoise, E.; Bissessur, D.; Yatheesh, V.; Scientific Party, M.

    2008-12-01

    The Rainbow hydrothermal field at 36° 14 N on the Mid-Atlantic Ridge is one of the few known sites hosted in ultramafic environment. The active site is located on a dome structure in the non-transform offset between the AMAR and South AMAR second-order ridge segments. One of the objectives of Cruise MOMAR DREAM (Aug-Sept 2008, R/V Atalante and ROV Victor) was a near-bottom detailed and exhaustive mapping of the hydrothermal site and its vicinities using the multibeam echosounder Reson SeaBat 7125 (400 Khz) and the high sensitivity photographic camera OTUS installed on ROV Victor. This first high resolution survey of the Rainbow massif has provided bathymetric maps with a resolution of a centimeter in depth and space for the surveys carried out at the altitude of 10 m (close to Site Rainbow), and some ten centimeters for the surveys at 50 m (a larger area, 4x3 km long). The frequency of the pings is 7 cycles by second for 512 beams with an opening of 150° and a speed of the ROV of 0.3-0.4 m/s. The data have been processed with the CARAIBES software of IFREMER. The ROV is positioned with the Posidonia Ultra Short Baseline system (USBL) and an estimated navigation from the loch and heading of the vehicle. The active hydrothermal site extends along an EW direction on about 200 m. It is localized on one important mound, around 20 m in diameter, which displays the highest chimneys like "Thermitiere". Small chimneys are sparse at the east of this mound, and another inactive mound is located 200m in the northeast. The whole hydrothermal area is located just north of a highly fractured domain made of a series of north-south high- angle normal faults making steps at least 40 meters high. This 400 m wide tectonic area extends to the south on about 600-700 m. The faults give access to the stockwork of the hydrothermal system, which has been sampled. North of the hydrothermal area, a 400 m large landslide cut across the serpentinite environment. At a wider scale, the

  18. Controls of Plume Dispersal at the Slow Spreading Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Walter, M.; Mertens, C.; Koehler, J.; Sueltenfuss, J.; Rhein, M.; Keir, R. S.; Schmale, O.; Schneider v. Deimling, J.; German, C. R.; Yoerger, D. R.; Baker, E. T.

    2011-12-01

    The slow-spreading Mid-Atlantic Ridges hosts a multitude of different types of hydrothermal systems. Here, we compare the fluxes and the plume dispersal at three high temperature sites located in very diverse settings at comparable depths (~3000m): The recently discovered sites Turtle Pits, and Nibelungen on the southern MAR, and the Logatchev field in the North Atlantic. Plume mapping for these sites on cruises between 2004 and 2009 consisted of CTD Towyo-, Yoyo,- and station work, including velocity profiling, as well as water sampling for analysis of trace gases (CH4, H2, 3He/4He) and metals; temperature measurements and fluid sampling at the vent sites were carried out with an ROV. The aim of this work is to gain a better understanding of how the setting of a vent site affects the dispersal of the particle plume, and what means can be used to infer possible locations of vent sites based on the hydrographic properties and plume observations, using high resolution bathymetric mapping and hydrographic information. The ultramafic-hosted Nibelungen site (8°18'S) consists of a single active smoking crater, along with several extinct smokers, which is located off-axis south of a non-transform offset. The setting is characterized by rugged topography, favorable for the generation of internal tides, internal wave breaking, and vertical mixing. Elevated mixing with turbulent diffusivities Kρ up to 0.1 m2 s-1, 3 to 4 orders of magnitude higher than open ocean values, was observed close to the vent site. The mixing as well as the flow field exhibited a strong tidal cycle; the plume dispersal is thus dominated by the fast and intermittent vertical exchange and characterized by small scale spatial and temporal variability. The Turtle Pits vent fields (4°48'S) are located on a sill in a north-south orientated rift valley. The site consists of three (known) high temperature fields: Turtle Pits, Comfortless Cove, and Red Lion. The particle plume is confined to the rift

  19. Physical Properties of Samples Cored From Atlantis Oceanic Core Complex, Mid-Atlantic Ridge 30 N

    NASA Astrophysics Data System (ADS)

    Searle, R.; Blackman, D.; Karner, G.; Harris, A.; Frost, R.

    2005-12-01

    IODP expedition 304/305 penetrated 1415 m into Atlantis Oceanic Core Complex, in 1.5 - 2.0 My crust, 12 km W of the Mid-Atlantic Ridge axis. Bulk magnetic susceptibility (MS), non-contact resistivity (NCR), P-wave velocity (Vp), bulk density, porosity and thermal properties were measured on recovered samples of peridotite, olivine-rich troctolite, olivine gabbro, gabbro, oxide gabbro, diabase and basalt. The most variable properties were MS and NCR, which were highly correlated, implying that the same minerals carry each signal, most likely Fe-Ti oxides such as magnetite and ilmenite and possibly minor sulfides. MS generally increased with iron content and decreased in intervals where magnetite had altered to ilmenite in diabase. High MS tends to concentrate in narrow bands and correlates with oxide- and sulfide-bearing gabbros and serpentinized zones (reflecting magnetite production during alteration). It exceeds 0.00001 SI in some oxide gabbros, equivalent to 8% magnetite by volume. MS is thus a valuable aid for mapping zones of oxide injection and serpentinization or other alteration and for stratigraphic correlation between holes. Core sample Vp is generally constant at about 5.5 km/s to 350 mbsf, increases to around 6.0 km/s at 450 mbsf and maintains this value to 750 mbsf, below which there is a steady decrease to about 5.8 km/s at 1200 mbsf, then a sharper decrease to 5.5 km/s at the bottom of the hole. The initial increase may be caused by closing cracks. The 10% decrease from 750 mbsf is a surprise: it may be real or perhaps due to overburden stress release. However, there is no corresponding reduction in bulk density with depth to indicate microscopic cracking during recovery. The final sharp decrease may reflect progressively increasing alteration. The largest local Vp variations are associated with massive olivine gabbros and troctolitic gabbros. A minimum between 300 and 350 mbsf reflects a zone of serpentinization. There is no significant seismic

  20. Carslberg Ridge and Mid-Atlantic Ridge: Slow-spreading Apparent Analogs

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Murton, B. J.; Bostrom, K.; Widenfalk, L.; Melson, W. G.; O'Hearn, T.; Cronan, D. S.; Jenkins, W. J.

    2005-12-01

    We compare morphology, tectonics, petrology, and hydrothermal activity of a known section of the Mid-Atlantic Ridge (MAR) between the Kane and Atlantis fracture zones (full multi-beam coverage 21N to 31N) to the lesser known Carlsberg Ridge (CR; limited multi-beam coverage plus satellite altimetry). The CR extends from the Owen Fracture Zone (10N) to the Vityaz Fracture Zone (5S) and spreads at half-rates (~1.2-1.8 cm/yr) similar to the MAR: 1) Morphology: Both ridges exhibit distinct segmentation (primarily sinistral) and axial valleys with high floor to crest relief (range 1122-1771 m). Average lengths of segments (CR: 70 km; MAR: 50 km) and crest-to crest width of the axial valley are greater on the CR (40 km) than MAR (23 km). Axial volcanic ridges form the neovolcanic zone on both ridges, typically 2.6 km wide and 213 m high on the CR. Average water depth near segment centers is greater on the MAR (3933 m) than the CR (3564 m). V-shaped patterns oblique to the spreading axis are present on both ridges. 2) Tectonics: Segments on each ridge are predominantly separated by short-offset (<30 km) non-transform discontinuities with longer transform faults generally spaced hundreds of kilometers apart. Bulls-eye Mantle Bouguer Lows (-30 to -50 mgal) are present at centers of spreading segments on both ridges. Metamorphic core complexes of lower crust and upper mantle are present on the MAR section (at fracture zones) and at least at one locality at 58.33E on the CR. 3) Petrology: MORB composition from our 20 stations along the CR fall into the MORB family, with no evidence of hotspot inputs (no excess K or Nb), or extreme fractionation, similar to the MAR section. REE and trace element patterns between 57E and 61E on the CR indicate increasing melt depletion to the northwest, while glasses exhibit a striking systematic increase in MgO (decrease in fractionation) to the northwest and attain among the most primitive composition of any ocean ridge adjacent to the Owen

  1. Research Drilling on the Mid-Atlantic Ridge: IDDP Wells of Opportunity at Reykjanes, Iceland

    NASA Astrophysics Data System (ADS)

    Fridleifsson, G. O.; Franzson, H.; Thorhallsson, S.; Elders, W. A.

    2005-12-01

    There are some 10 new geothermal wells at Reykjanes, in SW-Iceland, being considered by the Iceland Deep Drilling Project (IDDP) as potential candidate wells of opportunity to explore for deep (4-5 km) supercritical fluids. The drill field is located where the Mid-Atlantic Ridge emerges from the Atlantic ocean at the tip of the Reykjanes Peninsula. The site is an ideal locality for a combined study on the evolution of a rifted oceanic crust and an active black smoker-type geothermal system. However, the oceanic pillow basaltic crust at Reykjanes is some 2-3 times thicker than normal ocean floor crust, which undoubtedly relates to it being part of the Icelandic Large Igneous Province. The deepest of the geothermal wells at Reykjanes is Drillhole RN-17, that was completed to 3082 m depth in February 2005. It is currently the prime candidate for deepening by the IDDP. The plan is to deepen it to 4 km in 2006, and to 5 km depth in 2007, with funding coming from Icelandic energy companies (Hitaveita Sudurnesja, Landsvirkjun and Orkuveita Reykjavikur), the Government of Iceland, the International Scientific Continental Drilling Program (ICDP) and the US National Science Foundation (NSF). The well RN-17 was drilled as a conventional production well with a 12 ¼ inch drillbit to 3082 m depth, and left barefoot, with a 13 3/8 inch production casing cemented down to 900 m. It will be flow tested this autumn. If the RN-17 well is selected by the IDDP for deepening, a 9 5/8 inch in casing will be cemented to 3081 m and drilling will be continued with an 8 ½ inch tricone bit to 4 km in the autumn of 2006. The ICDP and NSF will fund spot coring for scientific studies in this depth interval and a second flow test would be performed in winter 2007. The following autumn, a 7 inch casing would be cemented to 4 km depth and then a 5 inch retrievable liner would be inserted to support a hybrid coring system to continuously core down to 5 km depth, retrieving HQ sized core. A third

  2. Panmixia in a Fragmented and Unstable Environment: The Hydrothermal Shrimp Rimicaris exoculata Disperses Extensively along the Mid-Atlantic Ridge

    PubMed Central

    Teixeira, Sara; Serrão, Ester A.; Arnaud-Haond, Sophie

    2012-01-01

    Dispersal plays a fundamental role in the evolution and persistence of species, and especially for species inhabiting extreme, ephemeral and highly fragmented habitats as hydrothermal vents. The Mid-Atlantic Ridge endemic shrimp species Rimicaris exoculata was studied using microsatellite markers to infer connectivity along the 7100-Km range encompassing the sampled sites. Astonishingly, no genetic differentiation was found between individuals from the different geographic origins, supporting a scenario of widespread large-scale dispersal despite the habitat distance and fragmentation. We hypothesize that delayed metamorphosis associated to temperature differences or even active directed migration dependent on physical and/or chemical stimuli could explain these results and warrant further studies on adaptation and dispersal mechanisms. PMID:22679511

  3. "Esteeme a little of fish": fish, fishponds, and farming in eighteenth-century New England and the Mid-Atlantic.

    PubMed

    Roberts, Strother E

    2008-01-01

    Prior to the advent of scientific aquaculture in the mid-nineteenth century, English farming manuals of the seventeenth and eighteenth centuries instructed American colonists in the "art of husbandry," imparting advice and passing on the best-known strategies for keeping and rearing fish in enclosed ponds. The development of such ponds in the New England and Mid-Atlantic colonies during the eighteenth century marked the culmination of a long process by which British-American colonists adapted to declines in natural fish populations brought on by over-fishing and disruption of habitat by water-powered mills. The development of private fishponds as an increasingly important component of American mixed husbandry practices in long-settled areas by the end of the eighteenth century illustrates early American farmers' ability to successfully adapt to self-wrought changes in their physical environment.

  4. Drilling the Snake Pit hydrothermal sulfide deposit on the Mid-Atlantic Ridge, lat 23/sup 0/22'N

    SciTech Connect

    Detrick, R.S.; Honnorez, J.; Adamson, A.C.; Brass, G.; Gillis, K.M.; Humphris, S.E.; Mevel, C.; Meyer, P.; Petersen, N.; Rautenschlein, M.; Shibata, T.; Staudigel, H.; Yamamoto, K.

    1986-12-01

    A major high-temperature hydrothermal area has been discovered in the Mid-Atlantic Ridge rift valley about 25 km south of the Kane Fracture Zone. The vent field consists of a wide area (> 40,000 m/sup 2/) of dark hydrothermal deposits, numerous sulfide chimneys and mounds, some up to 11 m high, and high-temperature black-smoker vents. Ten shallow holes, the first ever drilled in an active submarine hydrothermal area, recovered friable, unconsolidated Fe, Cu-Fe, and Zn sulfides and several large fragments of massive sulfide (mainly chalcopyrite) from the locally thick (> 13 m) hydrothermal deposits. The vents are also associated with an unusual biological community of smaller, more mobile organisms than reported from the East Pacific Rise.

  5. Potential for shoreline changes due to sea-level rise along the U.S. mid-Atlantic region

    USGS Publications Warehouse

    Gutierrez, Benjamin T.; Williams, S. Jeffress; Thieler, E. Robert

    2007-01-01

    Sea-level rise over the next century is expected to contribute significantly to physical changes along open-ocean shorelines. Predicting the form and magnitude of coastal changes is important for understanding the impacts to humans and the environment. Presently, the ability to predict coastal changes is limited by the scientific understanding of the many variables and processes involved in coastal change, and the lack of consensus regarding the validity of existing conceptual, analytical, or numerical models. In order to assess potential future coastal changes in the mid-Atlantic U.S. for the U.S. Climate Change Science Program (CCSP), a workshop was convened by the U.S. Geological Survey. Assessments of future coastal change were made by a committee of coastal scientists with extensive professional experience in the mid-Atlantic region. Thirteen scientists convened for a two-day meeting to exchange information and develop a consensus opinion on potential future coastal changes for the mid-Atlantic coast in response to sea-level rise. Using criteria defined in past work, the mid-Atlantic coast was divided into four geomorphic compartments: spits, headlands, wave-dominated barriers, and mixed-energy barriers. A range of potential coastal responses was identified for each compartment based on four sea-level rise scenarios. The four scenarios were based on the assumptions that: a) the long-term sea-level rise rate observed over the 20th century would persist over the 21st century, b) the 20th century rate would increase by 2 mm/yr, c) the 20th century rate would increase by 7 mm/yr, or d) sea-level would rise by 2 m over the next few hundred years. Potential responses to these sea-level rise scenarios depend on the landforms that occur within a region and include increased likelihood for erosion and shoreline retreat for all coastal types, increased likelihood for erosion, overwash and inlet breaching for barrier islands, as well as the possibility of a threshold

  6. Results of APL rain gauge network measurements in mid-Atlantic coast region and comparisons of distributions with CCIR models

    NASA Technical Reports Server (NTRS)

    Goldhirsh, Julius; Gebo, Norman; Rowland, John

    1988-01-01

    In this effort are described cumulative rain rate distributions for a network of nine tipping bucket rain gauge systems located in the mid-Atlantic coast region in the vicinity of the NASA Wallops Flight Facility, Wallops Island, Virginia. The rain gauges are situated within a gridded region of dimensions of 47 km east-west by 70 km north-south. Distributions are presented for the individual site measurements and the network average for the year period June 1, 1986 through May 31, 1987. A previous six year average distribution derived from measurements at one of the site locations is also presented. Comparisons are given of the network average, the CCIR (International Radio Consultative Committee) climatic zone, and the CCIR functional model distributions, the latter of which approximates a log normal at the lower rain rate and a gamma function at the higher rates.

  7. Results of APL rain gauge network measurements in mid-Atlantic coast region and comparisons of distributions with CCIR models

    NASA Astrophysics Data System (ADS)

    Goldhirsh, Julius; Gebo, Norman; Rowland, John

    1988-08-01

    In this effort are described cumulative rain rate distributions for a network of nine tipping bucket rain gauge systems located in the mid-Atlantic coast region in the vicinity of the NASA Wallops Flight Facility, Wallops Island, Virginia. The rain gauges are situated within a gridded region of dimensions of 47 km east-west by 70 km north-south. Distributions are presented for the individual site measurements and the network average for the year period June 1, 1986 through May 31, 1987. A previous six year average distribution derived from measurements at one of the site locations is also presented. Comparisons are given of the network average, the CCIR (International Radio Consultative Committee) climatic zone, and the CCIR functional model distributions, the latter of which approximates a log normal at the lower rain rate and a gamma function at the higher rates.

  8. Chirp seismic-reflection data from the Baltimore, Washington, and Norfolk Canyons, U.S. mid-Atlantic margin

    USGS Publications Warehouse

    Obelcz, Jeffrey B.; Brothers, Daniel S.; ten Brink, Uri S.; Chaytor, Jason D.; Worley, Charles R.; Moore, Eric M.

    2014-01-01

    A large number of high-resolution geophysical surveys between Cape Hatteras and Georges Bank have been conducted by federal, state, and academic institutions since the turn of the century. A major goal of these surveys is providing a continuous view of bathymetry and shallow stratigraphy at the shelf edge in order to assess levels of geological activity during the current sea level highstand. In 2012, chirp seismic-reflection data was collected by the U.S. Geologial Survey aboard the motor vessel Tiki XIV near three United States mid-Atlantic margin submarine canyons. These data can be used to further our understanding of passive continental margin processes during the Holocene, as well as providing valuable information regarding potential submarine geohazards.

  9. National Commission on Libraries and Information Science Mid-Atlantic States Regional Hearing, Philadelphia, Pennsylvania, May 21, 1975. Volume Two. Written Testimony.

    ERIC Educational Resources Information Center

    National Commission on Libraries and Information Science, Washington, DC.

    This is the second of two volumes of written testimony presented to the National Commission on Libraries and Information Science (NCLIS) at its Mid-Atlantic States Regional Hearing held May 21, 1975 at Philadelphia, Pennsylvania. Statements are provided by academic, public, state, and special librarians, as well as by spokespersons for…

  10. PREDICTING THE OCCURRENCE OF NUTRIENTS AND PESTICIDES DURING BASE FLOW IN NONTIDAL HEADWATER STREAMS OF THE MID-ATLANTIC COASTAL PLAIN

    EPA Science Inventory

    Water quality in nontidal headwater (first-order) streams of the Mid-Atlantic Coastal Plain (MACP) during base flow in the late winter and spring is related to land use, hydrogeology, and other natural or human influences in contributing watersheds.

  11. Emergency Contraceptive Pills: A 10-Year Follow-up Survey of Use and Experiences at College Health Centers in the Mid-Atlantic United States

    ERIC Educational Resources Information Center

    Miller, Laura McKeller; Sawyer, Robin G.

    2006-01-01

    The authors conducted a 10-year follow-up study using a telephone survey to investigate the availability of emergency contraceptive pills (ECPs) at college health centers in the mid-Atlantic region of the United States. They also examined related issues, such as distribution procedure, existence of a written protocol, personnel involved,…

  12. The Squishy and Stubborn Problem of Retention: A Study of a Mid Atlantic Historically Black Institution with a Land-Grant Mission

    ERIC Educational Resources Information Center

    Nyirenda, Stanley M.; Gong, Tao

    2010-01-01

    This study of a Mid Atlantic Historically Black Institution (MAHBI) examines cognitive, social, and institutional factors to identify those that are most critical in contributing to the steady decline of the rate of student retention for this institution and others with similar characteristics. Secondary source data pertaining to three cohorts…

  13. An Investigation of the Relationship between the Components of School Climate and Leadership Behaviors on Student Achievement: Urban School Districts in the Mid-Atlantic Region

    ERIC Educational Resources Information Center

    Collins, Karmen J.

    2015-01-01

    The purpose of this research study was to investigate the relationship between the components of school climate and leadership behaviors on student achievement in an urban school district in the mid-atlantic region. School climate and leadership behaviors for the participating school districts was determined by the School Climate Survey (Corner…

  14. GLOBAL CHANGE RESEARCH NEWS #34: PUBLICATION OF FACT SHEET BY EPA REGION 3, "HOW WILL CLIMATE CHANGE AFFECT THE MID-ATLANTIC REGION?"

    EPA Science Inventory

    EPA's Global Change Research Program is pleased to announce the publication of a fact sheet entitled, "How Will Climate Change Affect the Mid-Atlantic Region?." This information sheet was prepared and published by EPA's Region 3 office. It summarizes key findings from the Mid-Atl...

  15. Common Core State Standards and Teacher Effectiveness. Q&A with Ross Wiener, Ph.D. REL Mid-Atlantic Teacher Effectiveness Webinar Series

    ERIC Educational Resources Information Center

    Regional Educational Laboratory Mid-Atlantic, 2013

    2013-01-01

    In this REL Mid-Atlantic webinar, Dr. Ross Wiener, Vice President and Executive Director of the Education and Society Program, Aspen Institute, discussed strategies for integrating the Common Core State Standards (CCSS) into teacher effectiveness systems, including ways in which the CCSS can support professional growth and inform teacher…

  16. Sampling techniques and detection methods for developing risk assessments for root-knot nematode (Meloidogyne incognita) on lima bean (Phaseolus lunatus) in the Mid-Atlantic region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lima bean, Phaseolus lunatus, is a cornerstone crop in the Mid-Atlantic region and Meloidogyne incognita, the southern root knot nematode (RKN), causes significant yield loss. The RKN has become more pervasive as toxic nematicides have been removed from the market, and risk evaluation research is ne...

  17. Appendix B of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data. Workshop to Establish Coordination and Communication

    SciTech Connect

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the second appendix to the report, the workshop participants.

  18. Impact of the invasive brown marmorated stink bug, Halyomorpha halys (Stal) in Mid-Atlantic tree fruit orchards in the United States: case studies of commercial management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four commercial orchards in the mid-Atlantic region of the United States were surveyed weekly in 2010 and 2011 for the presence of brown marmorated stink bug and the injury caused to both apple and peaches. Among tested sampling techniques, baited pyramid traps yielded the most brown marmorated sti...

  19. Appendix D of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data. Workshop to Establish Coordination and Communication

    SciTech Connect

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the fourth appendix to the report, the presentations from the workshop.

  20. Reinterpretation of the Franklin "Shore" in the Mid-Atlantic bight as a paleo-shelf edge

    NASA Astrophysics Data System (ADS)

    Goff, John A.; Austin, James A.; Fulthorpe, Craig S.

    2013-06-01

    The presence of a scarp sub-parallel to, but landward of, the modern continental shelf edge is commonly used to infer a fossil shoreline preserved during the course of a sea level rise and shoreline transgression. Advances in geophysical imaging, including bathymetric data compilations and high-resolution acoustic reflection, merit a review of these scarps and their origins. We focus on the Mid-Atlantic Bight, east coast of the United States, where four siliciclastic fossil shorelines have previously been identified and are still cited as such in the literature. Two of the scarps are not in evidence in the newest compilation of bathymetry. A third, the Mid-Shelf Scarp, is of limited extent and, as established in previous studies, represents a seaward edge of delta lobes rather than a fossil shoreline. The fourth, the Franklin Scarp, is a major topographic feature that extends from Cape Hatteras to Cape Cod. However, morphologic and stratigraphic evidence leads us to conclude that, instead of a fossil shore, this scarp represents a paleo-shelf edge, likely formed during the MIS 4 lowstand (~65 ka). Both the modern shelf edge and the Franklin Scarp deepen to the north by ~50 m, while systematically maintaining a depth offset of ~40 m. This observation, which cannot be attributed to glacial isostatic processes, is enigmatic but suggests fundamental environmental controls on the depth of the clinoform rollover. Furthermore, all the major shelf-indenting canyons in the Mid-Atlantic Bight are bounded landward by the Franklin Scarp, which suggests that interfluve progradation may be a more significant mechanism for growth of these canyons than headward erosion.

  1. Watershed Scale Impacts of Stormwater Green Infrastructure on Hydrology and Nutrient Fluxes in the Mid-Atlantic Region.

    NASA Astrophysics Data System (ADS)

    Jaffe, P. R.; Pennino, M. J.; McDonald, R.

    2015-12-01

    Stormwater green infrastructure (SGI), including rain gardens, detention ponds, bioswales, and green roofs, is being implemented in cities across the globe to help reduce flooding, decrease combined sewer overflows, and lessen pollutant transport to streams and rivers. Despite the increasing use of urban SGI, there is much uncertainty regarding the cumulative effects of multiple SGI projects on hydrology and water quality at the watershed scale. To assess the cumulative effects of SGI, major cities across the mid-Atlantic were selected based on availability of SGI, water quality, and stream flow data. The impact of SGI was evaluated by comparing similar watersheds, with and without SGI or by assessing how long-term changes in SGI impact hydrologic and water quality metrics over time. Most mid-Atlantic cities have a goal of achieving 10-75% SGI by 2030. Of these cites, Washington D.C. currently has the highest density of SGI (15.5%), while Philadelphia, PA and New York, NY have the lowest (0.14% and 0.28%, respectively). When comparing watersheds of similar size and percent impervious surface cover, watersheds with lower amounts of SGI, on average, show up to 40% greater annual total nitrogen and 75% greater total phosphorus loads and show flashier hydrology (as indicated by 35% greater average peak discharge, 26% more peak discharge events per year, and 21% higher peak-to-volume ratio) compared to watersheds with higher amounts of SGI. However, for cities with combined sewer systems (e.g. Washington, D.C. and Philadelphia, PA), there was no relationship between the level of combined sewer overflows (CSOs) and the amount of SGI, indicating the level of SGI may not yet be sufficient to reduce CSOs as intended. When comparing individual watersheds over time, increases in SGI show no significant effect on the long-term trends in nutrient loads or hydrologic variables, potentially being obscured by the larger effect of interannual variability.

  2. Anthropocene streams and base-level controls from historic dams in the unglaciated mid-Atlantic region, USA

    USGS Publications Warehouse

    Merritts, Dorothy; Walter, Robert; Rahnis, Michael; Hartranft, Jeff; Cox, Scott; Gellis, Allen; Potter, Noel; Hilgartner, William; Langland, Michael; Manion, Lauren; Lippincott, Caitlin; Siddiqui, Sauleh; Rehman, Zain; Scheid, Chris; Kratz, Laura; Shilling, Andrea; Jenschke, Matthew; Datin, Katherine; Cranmer, Elizabeth; Reed, Austin; Matuszewski, Derek; Voli, Mark; Ohlson, Erik; Neugebauer, Ali; Ahamed, Aakash; Neal, Conor; Winter, Allison; Becker, Steven

    2011-01-01

    Recently, widespread valley-bottom damming for water power was identified as a primary control on valley sedimentation in the mid-Atlantic US during the late seventeenth to early twentieth century. The timing of damming coincided with that of accelerated upland erosion during post-European settlement land-use change. In this paper, we examine the impact of local drops in base level on incision into historic reservoir sediment as thousands of ageing dams breach. Analysis of lidar and field data indicates that historic milldam building led to local base-level rises of 2-5 m (typical milldam height) and reduced valley slopes by half. Subsequent base-level fall with dam breaching led to an approximate doubling in slope, a significant base-level forcing. Case studies in forested, rural as well as agricultural and urban areas demonstrate that a breached dam can lead to stream incision, bank erosion and increased loads of suspended sediment, even with no change in land use. After dam breaching, key predictors of stream bank erosion include number of years since dam breach, proximity to a dam and dam height. One implication of this work is that conceptual models linking channel condition and sediment yield exclusively with modern upland land use are incomplete for valleys impacted by milldams. With no equivalent in the Holocene or late Pleistocene sedimentary record, modern incised stream-channel forms in the mid-Atlantic region represent a transient response to both base-level forcing and major changes in land use beginning centuries ago. Similar channel forms might also exist in other locales where historic milling was prevalent.

  3. Epidosites and related metabasaltic rocks from detachment faults on the Mid-Atlantic Ridge, 16.5°N

    NASA Astrophysics Data System (ADS)

    Cann, J. R.; Marschall, H.; Dick, H. J.; McCaig, A. M.; Humphris, S. E.; Smith, D. K.

    2013-12-01

    Epidosites, epidote-quartz-chlorite rocks, play an important part in the hydrothermal systems of ophiolites such as Troodos and Oman. They form by intense flow of high-temperature fluid through sheeted dykes, stripping them of metals and producing profound changes in rock chemistry. Since ophiolitic sulphide deposits are very similar to those of the modern ocean floor, it is surprising that epidosites have very rarely been recovered from the oceans. The only previous example reported from the Mid-Atlantic Ridge came from the west end of the Atlantis Massif detachment at 30°N (Quon and Ehlers 1963). On RV Knorr cruise 210-5 in May-June 2013 we conducted a detailed survey of a region of the crest of the Mid-Atlantic Ridge around 16.5°N that is dominated by detachment faulting. During the survey we made 15 dredge hauls that brought back metabasaltic rocks. Some of these were clearly dykes intrusive into the peridotites and gabbros of detachment footwalls. Many others were metamorphosed pillow lavas, presumably derived in some way from detachment hangingwalls. In two of the metabasaltic dredge hauls were a number of epidosites and in other dredges there were rocks related to epidosites. The apparent discrepancy between the oceans and ophiolites might be the result of differences in bulk rock composition, or in ocean chemistry back in the Cretaceous. But it might be lack of close attention to dredge hauls. On Knorr 210-5 our rock descriptions were organised more systematically than usual, but even so the epidosites did not stand out readily from the other metabasalts.

  4. Long-term observations of bottom current and bottom sediment movement on the mid-Atlantic continental shelf

    USGS Publications Warehouse

    Butman, Bradford; Noble, Marlene A.; Folger, David W.

    1979-01-01

    Long-term in situ observations made at three locations on the mid-Atlantic continental shelf during 1975–1976 clearly show intermittent movement of bottom sediment caused by currents, waves, and other forcing mechanisms. In winter, storm-associated bottom currents greater than 30 cm s−1 resuspended and transported sediments. Net water particle excursions during storms were about 20–30 km longshelf and 5–10 km cross-shelf. Wave-induced bottom currents also resuspended sediments during periods of low mean flow. Sediment motion was observed in summer, although bottom conditions were generally tranquil. Significant changes in suspended matter concentration were observed that were only partially related to bottom currents. These changes may have been caused by biological activity or advection. Bottom currents on the mid-Atlantic region of the continental shelf were characterized by a coherent, primarily cross-shelf tidal flow of 5–10 cm s−1 and a low-frequency longshelf component of 5–20 cm s−1. The longshelf current was coherent over length scales of 100 km at tidal frequencies and for motions with periods greater than 50 hours. For these longer periods the longshelf flow was coherent with wind stress, which implies that winds were a major driving force of the longshelf current. The cross-shelf current was not coherent at stations separated by 100 km except at tidal frequencies. Packets of high-frequency internal waves were observed during stratified conditions in summer with bottom currents as large as 20 cm s−1.

  5. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Surf Clam

    SciTech Connect

    Fay, C.W.; Neves, R.J.; Pardue, G.B.

    1983-10-01

    The surf clam (Spisula solidissima) is a dominant clam species in the mid-Atlantic region, and contributed 71.8% of all clam meats consumed in the United States between 1970 and 1974; total landings in 1981 were 20.9 thousand metric tons (46.1 million lb). Surf clams live in the coastal zone from the Gulf of Maine to Cape Hatteras, North Carolina; they are most common in the breaker zone, but occur to depths of 70 m (230 ft). They reach sexual maturity in 2 years and spawn in the mid-Atlantic region from mid-July through mid-October, often with two spawning peaks per year. Larval stages are planktonic; upon settlement, they metamorphose into juvenile clams. Adults live buried in sandy or gravel substrates, with siphons extended above the bottom for feeding and respiration. Surf clams may live up to 25 years and reach a size of 225 mm (8.9 inches). Larvae tolerate water temperatures of 14/sup 0/ to 30/sup 0/F (57/sup 0/) to 86/sup 0/F), and salinities as low as 16 ppt. Adults tolerate 0/sup 0/ to 28/sup 0/C (32/sup 0/ to 82/sup 0/F) and 12.5 ppt salinity or higher. Depletion of dissolved oxygen in ocean bottom waters was the major cause for large-scale surf clam mortalities off New York and New Jersey over the last two decades. Sewage, sludge, and heavy metals often cause accumulation of toxic materials in surf clam meats and force closure of beds to fishing to prevent human consumption of these toxic materials. 98 references, 2 figures, 3 tables.

  6. Hydrothermal activity at the Trans-Atlantic Geotraverse Hydrothermal Field, Mid-Atlantic Ridge crest at 26°N

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Thompson, G.; Mottl, M. J.; Karson, J. A.; Jenkins, W. J.; Graham, D.; Mallette, M.; von Damm, K.; Edmond, J. M.

    1984-12-01

    The first submersible observations of the only known active submarine hydrothermal field on a slow-spreading oceanic ridge are incorporated with results of 10 prior years of investigation to derive an understanding of periodicity, duration, and varying intensity of hydrothermal activity at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge crest near latitude 26°N. Hydrothermal activity has persisted at this location for at least 1×106 years based on the distribution of hydrothermal and hydrogenous mineralization with respect to crustal age. The hydrothermal activity has been cyclic, multistage, and episodic. Prior high-temperature hydrothermal venting stages with a periodicity of the order of 1×104 years and duration of the order of 101 years are deduced from the estimated ages of discrete sedimentary layers anomalously enriched in Cu, Fe, and Zn and correspond with the independently determined periodicity of volcanic eruptive cycles on the Mid-Atlantic Ridge. The most recent episode of high-temperature venting is inferred to have ceased in the recent past based on metal enrichment (Cu, Fe, Zn) in the surficial sediment layer. Low-temperature hydrothermal venting stages with a duration of the order of 1×104 years intervene between the short high-temperature stages and produce stratiform deposits of layered and earthy manganese oxide, iron oxide, hydroxide, and silicate. Bivalve-like forms with the characteristics of vent clams in various stages of dissolution are identified on bottom photographs. The fresh appearance of intact tubules composed of iron hydroxide that acted as vents on relict deposits, conductive heat flow anomalies in the sediment column, and the record of temperature anomalies and excess 3He in the near-bottom water column, suggest that the low-temperature hydrothermal discharge is intermittent at individual vents on a time scale of years.

  7. An oilspill risk analysis for the Mid-Atlantic (proposed sale 76) outer continental shelf lease area

    USGS Publications Warehouse

    Samuels, W.B.; Hopkins, Dorothy

    1982-01-01

    An oilspill risk analysis was conducted for the mid-Atlantic (proposed sale 76) Outer Continental Shelf (OCS) lease area. The analysis considered: the probability of spill occurrences based on historical trends; likely movement of oil slicks based on a climatological model; and locations of environmental resources which could be vulnerable to spilled oil. The times between spill occurrence and contact with resources were estimated to aid analysts in estimating slick characteristics. Critical assumptions made for this particular analysis were (1) that oil exists in the lease area, and (2) that 0.879 billion barrels of oil will be found and produced from tracts sold in sale 76. On the basis of this resource estimate, it was calculated that 3 to 4 oilspills of 1,000 barrels or greater will occur over the 30-year production life of the proposed sale 76 lease tracts. The results also depend upon the routes and methods chosen to transport oil from 0CS platforms to shore. Given the above assumptions, the estimated probability that one or more oilspills of 1,000 barrels or larger will occur and contact land after being at sea less than 30 days is 0.36; for spills 10,000 barrels or larger, the probability is 0.22. These probabilities also reflect the following assumptions: oilspills remain intact for up to 30 days, do not weather, and are not cleaned up. It is noteworthy that over 90 percent of the risk from proposed sale 76 is due to transportation rather than production of oil. In addition, the risks from proposed sale 76 are about 1/10 to 1/15 those of existing tanker transportation of crude oil imports and refined products in the mid-Atlantic area.

  8. Anthropocene streams and base-level controls from historic dams in the unglaciated mid-Atlantic region, USA.

    PubMed

    Merritts, Dorothy; Walter, Robert; Rahnis, Michael; Hartranft, Jeff; Cox, Scott; Gellis, Allen; Potter, Noel; Hilgartner, William; Langland, Michael; Manion, Lauren; Lippincott, Caitlin; Siddiqui, Sauleh; Rehman, Zain; Scheid, Chris; Kratz, Laura; Shilling, Andrea; Jenschke, Matthew; Datin, Katherine; Cranmer, Elizabeth; Reed, Austin; Matuszewski, Derek; Voli, Mark; Ohlson, Erik; Neugebauer, Ali; Ahamed, Aakash; Neal, Conor; Winter, Allison; Becker, Steven

    2011-03-13

    Recently, widespread valley-bottom damming for water power was identified as a primary control on valley sedimentation in the mid-Atlantic US during the late seventeenth to early twentieth century. The timing of damming coincided with that of accelerated upland erosion during post-European settlement land-use change. In this paper, we examine the impact of local drops in base level on incision into historic reservoir sediment as thousands of ageing dams breach. Analysis of lidar and field data indicates that historic milldam building led to local base-level rises of 2-5 m (typical milldam height) and reduced valley slopes by half. Subsequent base-level fall with dam breaching led to an approximate doubling in slope, a significant base-level forcing. Case studies in forested, rural as well as agricultural and urban areas demonstrate that a breached dam can lead to stream incision, bank erosion and increased loads of suspended sediment, even with no change in land use. After dam breaching, key predictors of stream bank erosion include number of years since dam breach, proximity to a dam and dam height. One implication of this work is that conceptual models linking channel condition and sediment yield exclusively with modern upland land use are incomplete for valleys impacted by milldams. With no equivalent in the Holocene or late Pleistocene sedimentary record, modern incised stream-channel forms in the mid-Atlantic region represent a transient response to both base-level forcing and major changes in land use beginning centuries ago. Similar channel forms might also exist in other locales where historic milling was prevalent.

  9. Ozonesonde Climatology and Satellite Product Evaluation: Tropospheric Ozone in the Mid-Atlantic from 2005-2010

    NASA Astrophysics Data System (ADS)

    Normile, C.; Thompson, A. M.; Schmidlin, F. J.; Schoeberl, M. R.

    2011-12-01

    Geostationary satellite missions are proposed to remotely assess regional air quality over large swaths, although the precise capability of the current set of satellite instruments to accurately resolve urban scale pollution remains unverified. We use the Trajectory Enhanced Tropospheric Ozone Residual product derived from Aura's Ozone Monitoring Instrument/Microwave Limb Sounder satellite data to examine the regional climatology of ozone pollution in the mid-Atlantic, focusing on the Washington, D.C. area and downwind Delmarva. We use the North American Regional Reanalysis to determine the synoptic scale flow patterns in the lower troposphere. In addition, a set of proxies (OMI NO2, surface ozone, cloud cover, and air mass classification) are employed to understand TTOR performance and interacting meteorological and chemical effects in the region. We find that the TTOR product accuracy varies substantially both temporally and spatially, improving during summer months (0.22% error in May compared to 11% error in October) for example, and over urban areas more than rural ones (12% error versus 16% error). TTOR product accuracy is influenced by air mass effects on advection and on planetary boundary layer ozone concentrations. Conditions conducive to ozone production yield a higher near-surface proportion of the tropospheric column as measured by Wallops Island ozonesondes. We identify synoptic-scale flow regimes that strengthen correlations between urban tropospheric ozone density and column density off the coast of the mid-Atlantic. These results indicate that remotely sensed measurements may indeed be able to discriminate urban influences on regional ozone and their effects in more remote areas and have implications for air quality assessment and model validation.

  10. USEPA RESEARCH ON INFILTRATION/INFLOW CONTROL

    EPA Science Inventory

    From the late 60's to early 80's, the USEPA conducted a series of research, development, and demonsration projects on the characterization, cause and consequence, and control of infiltation/inflow (I/I) in both sanitary and combined sewers. The research effort was driven by the n...

  11. SOLIDIFICATION/STABILIZATION - USEPA SUPERFUND PROGRAM

    EPA Science Inventory

    The USEPA experience in using Solidification/Stabilization (S/S) Technology to remediate Superfund sites is reviewed. Included are several case studies for insitu and exsitu treatment and sites containing both metals and organics, both separately, and mixed on the same site. Co...

  12. OVERVIEW OF USEPA'S SMALL SYSTEMS DEMONSTRATION PROGRAM

    EPA Science Inventory

    This presentation provides an overview of the USEPA Arsenic Treatment Technology Demonstration Program. The information includes the status of the projects on both round 1 and round 2 including some photos of the treatment systems. Limited information is given on the results of t...

  13. USEPA Santa Cruz River Public Survey Research

    EPA Science Inventory

    The USEPA Office of Research and Development, Western Ecology Division is investigating how urban households value different possibilities for the Santa Cruz River in southern Arizona. A random sample of households in the Phoenix and Tucson areas are being asked to provide their ...

  14. SUPPORT FOR USEPA'S PATHOGEN EQUIVALENCY COMMITTEE

    EPA Science Inventory

    This presentation will discuss recommended and new resources for the USEPA's Pathogen Equivalency Committee including: 1) Committee's creation in 1985 and its purpose 2) Drexel University Professor Chuck Haas' 2001 report (Assessment of the PEC Process) and its findings 3) NAS/NR...

  15. USEPA RESEARCH ON INFILTRATION/INFLOW CONTROL

    EPA Science Inventory

    From the late 60's to early 80's, the USEPA conducted a series of research, development, and demonstration projects on the characterization, cause and consequence, and control of infiltation/inflow (I/I) in both sanitary and combined sewers. The research effort was driven by the ...

  16. IDENTIFICATION AND LOCATION OF FUNDAMENTAL FISH ASSEMBLAGES IN THE MID-ATLANTIC HIGHLANDS

    EPA Science Inventory

    To predict fish community response to environmental restoration in the Highlands Region one must first have information on fish abundance and diversity. We used data collected by the US Environmental Protection Agency's EMAP (Environmental Monitoring and Assessment Program) to i...

  17. THE EFFECTS OF ECOSYSTEM RESTORATION ON NITROGEN PROCESSING IN AN URBAN MID-ATLANTIC PIEDMONT STREAM

    EPA Science Inventory

    Elevated nitrate levels in streams and groundwater pose human and ecological threats. The US Environmental Protection Agency, US Geological Survey, Institute of Ecosystem Studies, and Baltimore County Dept. of Environmental Protection and Resource Management are collaborating on...

  18. 75 FR 56994 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-17

    ...; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... SSC member orientation, (2) review stock assessment information and specify overfishing level and... formation of SSC Ecosystem Subcommittee and development of ecosystem terms of reference for the...

  19. 75 FR 55743 - Mid-Atlantic Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-14

    ...; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... assessment information and specify overfishing level and acceptable biological catch for spiny dogfish for... development of Industry Advisory Panel Reports; and (9) discuss formation of SSC Ecosystem Subcommittee...

  20. USEPA'S APPROACH TO THE DEVELOPMENT OF NEW ANALYTICAL METHODS FOR EMERGING CONTAMINANTS IN DRINKING WATER

    EPA Science Inventory

    The 1996 Amendments to the Safe Drinking Water Act require USEPA to perform Unregulated Contaminant Monitoring (UCM) for chemicals of interest to the Agency for possible future regulation. Many of these chemicals fall into the category of "emerging contaminants". An important e...

  1. Ecosystem Services - An Emerging Direction for the U.S.EPA

    EPA Science Inventory

    Forty years ago the United States Environmental Protection Agency (U.S.EPA) was formed to “protect human health and the environment”. In those days the environment was being severely, and obviously, degraded by any number of pollution inputs, and it was clear that a healthy envi...

  2. USEPA'S SMALL DRINKING WATER TREATMENT TECHNOLOGY DEMONSTRATIONS IN ECUADOR AND MEXICO

    EPA Science Inventory

    In order to support and help in the struggle to improve the quality of drinking water in the United States and abroad, the United States Environmental Protection Agency (USEPA) conducts research studies for the demonstration and evaluation of alternative and innovative drinking w...

  3. 75 FR 26920 - Mid-Atlantic Fishery Management Council; Spiny Dogfish Amendment 3 Scoping Process

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-13

    ...; Spiny Dogfish Amendment 3 Scoping Process AGENCY: National Marine Fisheries Service (NMFS), National... not noted in the initial Notice of Intent (NOI) for Amendment 3 to the Spiny Dogfish Fishery.... The scoping comment period for issues previously announced for Amendment 3 to the Spiny...

  4. Localized Deformation Beginning more than 15 km Beneath the Mid-Atlantic Ridge, 14 to 16 N

    NASA Astrophysics Data System (ADS)

    Kelemen, P.

    2003-12-01

    ODP Leg 209 drilled 19 holes at 8 sites along the Mid-Atlantic Ridge from 14° 43 to 15° N. All sites were surveyed by submersible, and chosen to be < 200 m from peridotite or dunite exposed on the seafloor; outcrops of gabbroic rock were also close to some sites. One of our primary goals was to constrain the mechanism of mantle upwelling, corner flow and exhumation of shallow mantle rocks. Drilling at Sites 1268, 1270-72, 1274 and 1275 penetrated 1075 meters, and recovered 354 m of core. At Sites 1268 and 1270-72 we recovered 25% gabbroic rocks and 75% residual mantle peridotite. Core from Site 1274 was mainly residual peridotite, while core from Site 1275 was mainly gabbroic. Most of the residual peridotites have nearly undeformed, protogranular textures. Orthopyroxenes are interstitial to olivine or even poikilitic. Rare, isolated clinopyroxene grains are also interstitial. Skeletal spinel grains have mm-scale extensions in three dimensions, with no discernable shape fabric. These textures are clearly different from porphyroclastic textures typical in ophiolites and fracture zone dredges. As described elsewhere at this meeting, impregnated peridotites contain olivine, 2 pyroxenes, plagioclase and spinel, and equilibrated at 0.54 GPa (+/-0.14 GPa, 2σ ) and 1220° C (+/-16° C, 2σ ) [Kinzler & Grove, JGR 92]. Melts entered the thermal boundary layer beneath the Mid-Atlantic Ridge at about 20 km [e.g., Sleep, JGR 75; Reid & Jackson, MGR 82; Grove et al JGR 92; Cannat JGR 96; Michael & Chase CMP 97; Braun et al., EPSL 00], and began to crystallize within impregnated peridotites and as discrete plutons intruding peridotite. Gabbroic rocks and peridotites from most sites underwent large tectonic rotations since aquiring remanent magnetization. At some sites, rotations may have exceeded 60° around near-horizontal axes parallel to the Mid-Atlantic Ridge. Such large rotations are unlikely to have been accomodated along a single fault, and instead blocks were

  5. Seismicity And Accretion Process Along The North Mid-Atlantic Ridge From The SIRENA Autonomous Hydrophone Data

    NASA Astrophysics Data System (ADS)

    Perrot, J.; Goslin, J.; Dziak, R. P.; Haxel, J. H.; Maia, M. A.; Tisseau, C.; Royer, J.

    2009-12-01

    The seismicity of the North Atlantic Ocean was recorded by the SIRENA array of 6 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed north of the Azores Plateau between 40° and 50°N from June 2002 to September 2003. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction to a magnitude completeness level (Mc) of ~2.8, to be compared to a Mc~4.7 for MAR events recorded by land-based seismic networks. A spatio-temporal analysis was performed over the 1696 events localized inside the SIRENA array. For hydrophone-derived catalogs, the acoustic magnitude, or Source Level (SL), is used as a measure of earthquake size. The ''source level completeness'', above which the data set is complete, is SLc=208 dB. The SIRENA catalog was searched for swarms using the cluster software of the SEISAN distribution. A minimum SL of 210 dB was chosen to detect a possible mainshock, and all subsequent events within 40 days following the possible mainshock, located within a radius of 15 km from the mainshock were considered as events of the swarm. 15 km correspond to the maximum fault length in a slow-ridge context. 11 swarms with more than 15 events were detected along the MAR between 40°et 50°N during the SIRENA deployment. The maximum number of earthquakes in a swarm is 40 events. The SL vs. time distribution within each swarm allowed a first discrimination between the swarms occurring in a tectonic context and those which can be attributed to volcanic processes, the latter showing a more constant SL vs. time distribution. Moreover, the swarms occurring in a tectonic context show a "mainshock-afterschock" distribution of the cumulative number of events vs. time, fitting a Modified Omori Law. The location of tectonic and volcanic swarms correlates well with regions where a positive and negative Mantle Bouguer

  6. Hydrothermal activity along the northern Mid-Atlantic Ridge and in the Bransfield Strait Backarc Basin, Antarctica

    NASA Astrophysics Data System (ADS)

    Chin, Carol S.

    1998-12-01

    Seafloor hydrothermal circulation through young oceanic crust results in the expulsion of fluids as both diffuse and focused flow in the form of hydrothermal venting. High-temperature hydrothermal fluids are enriched in reduced chemical species that rapidly oxidize upon interaction with ambient, oxygen-rich bottom waters, resulting in plumes that are detectable in the water column both by their dissolved chemical composition as well as by their particle concentration. This study employed a novel instrument package which detected both dissolved manganese and particle concentration in situ. This package also included a standard CTD (conductivity, temperature, depth) and rosette for the collection of water samples. Because hydrothermal plumes integrate the output from an entire vent field, measurements in plumes can be used to estimate vent field fluxes. Some geochemical tracers from hydrothermal vents can also be detected thousands of kilometers from their sources. Thus, plumes provide the means to prospect for undiscovered hydrothermal sites, and can also predict characteristics of the venting site. This work includes studies of hydrothermal plumes along the northern Mid-Atlantic Ridge and in the Bransfield Strait backarc basin, Antarctica. In recent years, the number of known hydrothermal sites on the Mid-Atlantic Ridge (MAR) has increased from two to seven, and most other segments between 12° and 41° N have shown evidence of high-temperature hydrothermal activity. Furthermore, it appears that as one approaches the Azores Plateau, the concentration of dissolved delta3He in the bottom water (originating from hydrothermal venting) increases, suggesting that hydrothermal activity increases toward the plateau. This is consistent with the significant tectonic extension and crustal fissuring observed near the Azores Platform, which is expected to support increased convection. The Bransfield Strait is a backarc basin between the Antarctic Peninsula and the South

  7. Short Term Effects of Particle Exposure on Hospital Admissions in the Mid-Atlantic States: A Population Estimate

    PubMed Central

    Kloog, Itai; Nordio, Francesco; Zanobetti, Antonella; Coull, Brent A.; Koutrakis, Petros; Schwartz, Joel D.

    2014-01-01

    Background Many studies report significant associations between PM2.5 (particulate matter <2.5 micrometers) and hospital admissions. These studies mostly rely on a limited number of monitors which introduces exposure error, and excludes rural and suburban populations from locations where monitors are not available, reducing generalizability and potentially creating selection bias. Methods Using prediction models developed by our group, daily PM2.5 exposure was estimated across the Mid-Atlantic (Washington D.C., and the states of Delaware, Maryland, New Jersey, Pennsylvania, Virginia, New York and West Virginia). We then investigated the short-term effects of PM2.5 exposures on emergency hospital admissions of the elderly in the Mid-Atlantic region.We performed case-crossover analysis for each admission type, matching on day of the week, month and year and defined the hazard period as lag01 (a moving average of day of admission exposure and previous day exposure). Results We observed associations between short-term exposure to PM2.5 and hospitalization for all outcomes examined. For example, for every 10-µg/m3 increase in short-term PM 2.5 there was a 2.2% increase in respiratory diseases admissions (95% CI = 1.9 to 2.6), and a 0.78% increase in cardiovascular disease (CVD) admission rate (95% CI = 0.5 to 1.0). We found differences in risk for CVD admissions between people living in rural and urban areas. For every10-µg/m3 increase in PM 2.5 exposure in the ‘rural’ group there was a 1.0% increase (95% CI = 0.6 to 1.5), while for the ‘urban’ group the increase was 0.7% (95% CI = 0.4 to 1.0). Conclusions Our findings showed that PM2.5 exposure was associated with hospital admissions for all respiratory, cardio vascular disease, stroke, ischemic heart disease and chronic obstructive pulmonary disease admissions. In addition, we demonstrate that our AOD (Aerosol Optical Depth) based exposure models can be successfully applied to epidemiological

  8. Wind effects on coastal zone color scanner chlorophyll patterns in the U.S. Mid-Atlantic Bight during spring 1979

    NASA Technical Reports Server (NTRS)

    Eslinger, David L.; Iverson, Richard L.

    1986-01-01

    Coastal zone color scanner (CZCS) chlorophyll concentration increases in the Mid-Atlantic Bight were associated with high wind speeds in continental shelf waters during March and May 1979. Maximum spring CZCS chlorophyll concentrations occurred during April when the water column was not thermally stratified and were spatially and temporally associated with reductions in wind speed both in onshelf and in offshelf regions. Increased chlorophyll concentrations in offshelf waters were associated with high wind speeds during May when a deep chlorophyll maximum was present. Chlorophyll patchiness was observed on length scales typical of those controlled by biological processes during the April low-wind period but not during March or May when wind speeds were greater. The spring CZCS chlorophyll maximum in the southern portion of the Mid-Atlantic Bight occurred in response to a reduction in mixed layer depth caused by decreased wind speeds and not by increased water column stratification.

  9. High paleointensities of the geomagnetic field from thermomagnetic studies on rift valley pillow basalts from the Mid- Atlantic Ridge.

    USGS Publications Warehouse

    Prevot, M.; Mankinen, E.A.; Gromme, S.; Lecaille, A.

    1983-01-01

    Nineteen pillow basalts dredged within the rift valley of the Mid-Atlantic Ridge at 36.8oN were studied by the Thellier stepwise heating method in order to determine the paleointensity of the geomagnetic field when they erupted on to the sea floor. Previously reported fission track ages are 2000-6000 yr for the youngest rocks (mainly olivine basalts) and 10 000-100 000 yr for the others (mainly plagioclase basalts and pyroxene basalts). All but three pillow basalts meet the conditions commonly considered as indicative of quite reliable paleointensity estimates; stability of the direction of NRM during its thermal demagnetization, constant ratio of NRM/TRM (natural remanent magnetization to thermoremanent magnetization) over 50% or more of the original NRM intensity (80 to 94% for 11 specimens), and reproducibility of low-temperature partial TRM(PTRM). However, strong field thermomagnetic measurements indicate that 11 of these 16 samples display a significant increase in Curie temperature (15 to 80oC) during the paleointensity experiments below 250oC, notwithstanding the linearity of the NRM-TRM plot in this temperature interval. This alteration, probably due to low-temperature oxidation of the specimens, seems typical of young pillow basalts and may result in paleointensity estimates which are too high.-from Authors

  10. Source and delivery of nutrients to receiving waters in the Northeastern and Mid-Atlantic regions of the United States

    USGS Publications Warehouse

    Moore, Richard B.; Johnston, Criag M.; Smith, Richard A.; Milstead, Bryan

    2011-01-01

    This study investigates nutrient sources and transport to receiving waters, in order to provide spatially detailed information to aid water-resources managers concerned with eutrophication and nutrient management strategies. SPAtially Referenced Regressions On Watershed attributes (SPARROW) nutrient models were developed for the Northeastern and Mid-Atlantic (NE US) regions of the United States to represent source conditions for the year 2002. The model developed to examine the source and delivery of nitrogen to the estuaries of nine large rivers along the NE US Seaboard indicated that agricultural sources contribute the largest percentage (37%) of the total nitrogen load delivered to the estuaries. Point sources account for 28% while atmospheric deposition accounts for 20%. A second SPARROW model was used to examine the sources and delivery of phosphorus to lakes and reservoirs throughout the NE US. The greatest attenuation of phosphorus occurred in lakes that were large relative to the size of their watershed. Model results show that, within the NE US, aquatic decay of nutrients is quite limited on an annual basis and that we especially cannot rely on natural attenuation to remove nutrients within the larger rivers nor within lakes with large watersheds relative to the size of the lake.

  11. Source and Delivery of Nutrients to Receiving Waters in the Northeastern and Mid-Atlantic Regions of the United States

    USGS Publications Warehouse

    Moore, R.B.; Johnston, C.M.; Smith, R.A.; Milstead, B.

    2011-01-01

    This study investigates nutrient sources and transport to receiving waters, in order to provide spatially detailed information to aid water-resources managers concerned with eutrophication and nutrient management strategies. SPAtially Referenced Regressions On Watershed attributes (SPARROW) nutrient models were developed for the Northeastern and Mid-Atlantic (NE US) regions of the United States to represent source conditions for the year 2002. The model developed to examine the source and delivery of nitrogen to the estuaries of nine large rivers along the NE US Seaboard indicated that agricultural sources contribute the largest percentage (37%) of the total nitrogen load delivered to the estuaries. Point sources account for 28% while atmospheric deposition accounts for 20%. A second SPARROW model was used to examine the sources and delivery of phosphorus to lakes and reservoirs throughout the NE US. The greatest attenuation of phosphorus occurred in lakes that were large relative to the size of their watershed. Model results show that, within the NE US, aquatic decay of nutrients is quite limited on an annual basis and that we especially cannot rely on natural attenuation to remove nutrients within the larger rivers nor within lakes with large watersheds relative to the size of the lake. ?? 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA.

  12. Seasonal and spatial patterns of Penilia avirostris and three tunicate species in the southern Mid-Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Ambler, Julie W.; Kumar, Ajoy; Moisan, Tiffany A.; Aulenbach, Donielle L.; Day, Melissa C.; Dix, Stephanie A.; Winsor, Michele A.

    2013-10-01

    The cladoceran Penilia avirostris and three tunicate species, Oikopleura dioica, Dolioletta gegenbauri and Thalia democratica, form a mesozooplankton group which ingests a wide range of particles from pico- to micro- plankton, grows rapidly due to asexual reproduction, and thus can have major impacts on phytoplankton populations. These four zooplankton species were the most abundant tunicate and cladoceran species in a study where zooplankton were sampled biweekly at five stations across the inner continental shelf in the Mid-Atlantic Bight in 2005, 2006 and 2007. Vertical tows were taken at shallow stations and depth stratified vertical tows at stations >10 m. P. avirostris and O. dioica had highly predictable seasonal cycles with peak abundances in July and August. D. gegenbauri also was present during this time period if upwelling favorable winds were present, which implies cross shelf transport from source populations in slope waters and the Gulf Stream. T. democratica only appeared in pulses when southerly winds were increasing in strength. The co-occurrence P. avirostris and the tunicate species with abundant Synechococcus and heterotrophic nanoflagellates during highly stratified summer conditions provide potential connections to microbial food webs as well as grazing opportunities on event scale blooms of dinoflagellate and diatoms species present in the area.

  13. Biogeographical distribution of Rimicaris exoculata resident gut epibiont communities along the Mid-Atlantic Ridge hydrothermal vent sites.

    PubMed

    Durand, Lucile; Roumagnac, Marie; Cueff-Gauchard, Valérie; Jan, Cyrielle; Guri, Mathieu; Tessier, Claire; Haond, Marine; Crassous, Philippe; Zbinden, Magali; Arnaud-Haond, Sophie; Cambon-Bonavita, Marie-Anne

    2015-10-01

    Rimicaris exoculata is a deep-sea hydrothermal vent shrimp whose enlarged gill chamber houses a complex trophic epibiotic community. Its gut harbours an autochthonous and distinct microbial community. This species dominates hydrothermal ecosystem megafauna along the Mid-Atlantic Ridge, regardless of contrasting geochemical conditions prevailing in them. Here, the resident gut epibiont community at four contrasted hydrothermal vent sites (Rainbow, TAG, Logatchev and Ashadze) was analysed and compiled with previous data to evaluate the possible influence of site location, using 16S rRNA surveys and microscopic observations (transmission electron microscopy, scanning electron microscopy and fluorescence in situ hybridization analyses). Filamentous epibionts inserted between the epithelial cell microvilli were observed on all examined samples. Results confirmed resident gut community affiliation to Deferribacteres, Mollicutes, Epsilonproteobacteria and to a lesser extent Gammaproteobacteria lineages. Still a single Deferribacteres phylotype was retrieved at all sites. Four Mollicutes-related operational taxonomic units were distinguished, one being only identified on Rainbow specimens. The topology of ribotype median-joining networks illustrated a community diversification possibly following demographic expansions, suggesting a more ancient evolutionary history and/or a larger effective population size at Rainbow. Finally, the gill chamber community distribution was also analysed through ribotype networks based on sequences from R. exoculata collected at the Rainbow, Snake Pit, TAG, Logatchev and Ashadze sites. Results allow the refining of hypotheses on the epibiont role and transmission pathways.

  14. Concentrations of mercury and other toxic elements in orange roughy, Hoplostethus atlanticus, from the Mid-Atlantic Ridge.

    PubMed

    Julshamn, K; Måge, A; Tyssebotn, I M B; Sæthre, L J

    2011-07-01

    Concentrations of the elements mercury, arsenic, cadmium and lead were measured in the muscle tissue of Orange roughy (Hoplostethus atlanticus) obtained from the Mid-Atlantic Ridge during the MAR: -ECO: expedition in the North Atlantic Ocean in 2004. The age of the fish varied from 1 to 139 years. To the best of our knowledge, the concentration of the heavy metals presented here is for one of the oldest fish in the literature, in addition to the fact that very little information on arsenic in Orange roughy has been previously published. The concentration of mercury in the fillet of the fish varied between 0.06 and 1.1 μg g⁻¹ w.w. Mercury was the only element that was positively correlated to the age. The concentrations of mercury were found to be below the maximum limits for Orange roughy set by EU at 1.0 μg g⁻¹ w.w, except for a 134 year fish sample with a concentration of 1.1 μg g⁻¹ w.w.

  15. Diversity and Metabolic Potentials of Subsurface Crustal Microorganisms from the Western Flank of the Mid-Atlantic Ridge.

    PubMed

    Zhang, Xinxu; Feng, Xiaoyuan; Wang, Fengping

    2016-01-01

    Deep-sea oceanic crust constitutes the largest region of the earth's surface. Accumulating evidence suggests that unique microbial communities are supported by iron cycling processes, particularly in the young (<10 million-year old), cool (<25°C) subsurface oceanic crust. To test this hypothesis, we investigated the microbial abundance, diversity, and metabolic potentials in the sediment-buried crust from "North Pond" on western flank of the Mid-Atlantic Ridge. Three lithologic units along basement Hole U1383C were found, which typically hosted ∼10(4) cells cm(-3) of basaltic rock, with higher cell densities occurring between 115 and 145 m below seafloor. Similar bacterial community structures, which are dominated by Gammaproteobacterial and Sphingobacterial species closely related to iron oxidizers, were detected regardless of variations in sampling depth. The metabolic potentials of the crust microbiota were assayed by metagenomic analysis of two basalt enrichments which showed similar bacterial structure with the original sample. Genes coding for energy metabolism involved in hydrocarbon degradation, dissimilatory nitrate reduction to ammonium, denitrification and hydrogen oxidation were identified. Compared with other marine environments, the metagenomes from the basalt-hosted environments were enriched in pathways for Fe(3+) uptake, siderophore synthesis and uptake, and Fe transport, suggesting that iron metabolism is an important energy production and conservation mechanism in this system. Overall, we provide evidence that the North Pond crustal biosphere is dominated by unique bacterial groups with the potential for iron-related biogeochemical cycles.

  16. Metal concentrations in the shell of Bathymodiolus azoricus from contrasting hydrothermal vent fields on the Mid-Atlantic Ridge.

    PubMed

    Cravo, A; Foster, P; Almeida, C; Bebianno, M J; Company, R

    2008-05-01

    Specimens of Bathymodiolus azoricus were sampled along the Mid-Atlantic Ridge at the Menez Gwen, Lucky Strike and Rainbow hydrothermal fields. Individual shells (n = 51), through the weight range 0.62 to 15.70 g, were analyzed for their magnesium, strontium, iron, manganese, copper, zinc and cadmium concentrations. Amongst the marine molluscs the shell of B. azoricus is confirmed as being particularly impoverished in strontium (mean 943 microg g(-1)). Trace metal concentrations in the shells decreased in the order Fe> Mn> Zn> Cu> Cd. Despite originating from trace metal rich environments mean concentrations were low (37.9, 13.2, 10.7, 1.1 and 0.7 microg g(-1), respectively). Irrespective of geographical origin magnesium, strontium and copper concentrations were primarily dictated by shell weight. In contrast cadmium concentrations were elevated in shells from the Rainbow field and ambient seawater chemistry imparted site specific chemical fingerprints to the shells with respect to the iron to manganese ratio.

  17. Free-living nematode species (Nematoda) dwelling in hydrothermal sites of the North Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Tchesunov, Alexei V.

    2015-12-01

    Morphological descriptions of seven free-living nematode species from hydrothermal sites of the Mid-Atlantic Ridge are presented. Four of them are new for science: Paracanthonchus olgae sp. n. (Chromadorida, Cyatholaimidae), Prochromadora helenae sp. n. (Chromadorida, Chromadoridae), Prochaetosoma ventriverruca sp. n. (Desmodorida, Draconematidae) and Leptolaimus hydrothermalis sp. n. (Plectida, Leptolaimidae). Two species have been previously recorded in hydrothermal habitats, and one species is recorded for the first time in such an environment. Oncholaimus scanicus (Enoplida, Oncholaimidae) was formerly known from only the type locality in non-hydrothermal shallow milieu of the Norway Sea. O. scanicus is a very abundant species in Menez Gwen, Lucky Strike and Lost City hydrothermal sites, and population of the last locality differs from other two in some morphometric characteristics. Desmodora marci (Desmodorida, Desmodoridae) was previously known from other remote deep-sea hydrothermal localities in south-western and north-eastern Pacific. Halomonhystera vandoverae (Monhysterida, Monhysteridae) was described and repeatedly found in mass in Snake Pit hydrothermal site. The whole hydrothermal nematode assemblages are featured by low diversity in comparison with either shelf or deep-sea non-hydrothermal communities. The nematode species list of the Atlantic hydrothermal vents consists of representatives of common shallow-water genera; the new species are also related to some shelf species. On the average, the hydrothermal species differ from those of slope and abyssal plains of comparable depths by larger sizes, diversity of buccal structures, presence of food content in the gut and ripe eggs in uteri.

  18. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (North and Mid-Atlantic): Blue mussel

    SciTech Connect

    Newell, R.I.E.

    1989-06-01

    The blue mussel, Mytilus edulis L. is a widely distributed and locally abundant bivalve mollusc in the North and Mid-Atlantic Regions. It is a valuable commercial species; regional landings in 1986 were worth nearly $4 million. It is a semi-sessile species, anchored by byssus threads to firm surfaces in littoral and sub-littoral environments at salinities ranging from 5 to 35 ppt. It is a suspension feeder, ingesting phytoplankton and detrital particles in the size range of 3--30 /mu/m. The geographical range of the species is limited by lethal water temperatures above 27/degree/C in the south and by temperatures too low for growth and reproduction in the north. Animals from the northern end of the range are stressed by temperatures above 20/degree/C, whereas those near the southern distributional limit are not severely stressed by temperatures as high as 25/degree/C. The blue mussel is diecious and oviparous. The planktotrophic larvae take about 3 weeks to develop and metamorphose. The environmental tolerances of larvae are more restricted than those of adults. The juveniles grow to approximately 1.5 mm while attached to filamentous algae before being carried by water currents to reattach to a firm substrate, often close to adult mussels. Larval and adult blue mussels are important prey items for many animals, including crabs, fishes, and birds. 95 refs., 5 figs., 2 tabs.

  19. The production of methane, hydrogen, and organic compounds in ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge.

    PubMed

    Konn, C; Charlou, J L; Holm, N G; Mousis, O

    2015-05-01

    Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge. Considering the vast number of these fields discovered or inferred, hydrothermal fluxes represent a significant input of H2 and CH4 to the ocean. Although there are lines of evidence of their abiogenic formation from stable C and H isotope results, laboratory experiments, and thermodynamic data, neither their origin nor the reaction pathways generating these gases have been fully constrained yet. Organic compounds detected in the fluids may also be derived from abiotic reactions. Although thermodynamics are favorable and extensive experimental work has been done on Fischer-Tropsch-type reactions, for instance, nothing is clear yet about their origin and formation mechanism from actual data. Since chemolithotrophic microbial communities commonly colonize hydrothermal vents, biogenic and thermogenic processes are likely to contribute to the production of H2, CH4, and other organic compounds. There seems to be a consensus toward a mixed origin (both sources and processes) that is consistent with the ambiguous nature of the isotopic data. But the question that remains is, to what proportions? More systematic experiments as well as integrated geochemical approaches are needed to disentangle hydrothermal geochemistry. This understanding is of prime importance considering the implications of hydrothermal H2, CH4, and organic compounds for the ocean global budget, global cycles, and the origin of life.

  20. Hydrothermal vent meiobenthos associated with mytilid mussel aggregations from the Mid-Atlantic Ridge and the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Zekely, J.; Van Dover, C. L.; Nemeschkal, H. L.; Bright, M.

    2006-08-01

    Deep-sea hydrothermal vents occur along the mid-ocean ridges and back-arc basins around the globe. There are very few community analyses of vent meiobenthos. The central objectives of this study were to identify and quantify for the first time the entire metazoan meiobenthic community associated with mussel aggregations of Bathymodiolus thermophilus Kenk and Wilson, 1985 from the EPR, 11°N and of Bathymodiolus puteoserpentis Cosel et al., 1994 from the Mid-Atlantic Ridge (MAR), 23°N. Using a quantitative sampling method, abundance, biomass, sex ratio, species richness, diversity, evenness, and trophic structure were studied based on three samples from each site. Meiobenthic abundance in each sample was unexpectedly low, but similar between sites. The community was composed of nematodes, copepods, ostracods, and mites, with a total of 24 species at EPR vents, and 15 species at MAR vents. While most copepod species were vent endemics within the family Dirivultidae, nematodes and harpacticoid copepods belonged to generalist genera, which occur at a variety of habitats and are not restricted to hydrothermal vents or the deep sea. The meiobenthos of hydrothermal-vent mussel beds constitutes a unique community unlike those of other sulfidic habitats, including the thiobios of shallow-water sediments and the meiobenthos of deep-sea, cold-seep sediments. The trophic structure was dominated by primary consumers, mainly deposit feeders, followed by parasites. Predatory meiofaunal species were absent.

  1. Cold-climate slope deposits and landscape modifications of the Mid-Atlantic Coastal Plain, Eastern USA

    USGS Publications Warehouse

    Newell, W.L.; Dejong, B.D.

    2011-01-01

    The effects of Pleistocene cold-climate geomorphology are distributed across the weathered and eroded Mid-Atlantic Coastal Plain uplands from the Wisconsinan terminal moraine south to Tidewater Virginia. Cold-climate deposits and landscape modifications are superimposed on antecedent landscapes of old, weathered Neogene upland gravels and Pleistocene marine terraces that had been built during warm periods and sea-level highstands. In New Jersey, sequences of surficial deposits define a long history of repeating climate change events. To the south across the Delmarva Peninsula and southern Maryland, most antecedent topography has been obscured by Late Pleistocene surficial deposits. These are spatially variable and are collectively described as a cold-climate alloformation. The cold-climate alloformation includes time-transgressive details of climate deterioration from at least marine isotope stage (MIS) 4 through the end of MIS 2. Some deposits and landforms within the alloformation may be as young as the Younger Dryas. Southwards along the trend of the Potomac River, these deposits and their climatic affinities become diffused. In Virginia, a continuum of erosion and surficial deposits appears to be the product of ‘normal’ temperate, climate-forced processes. The cold-climate alloformation and more temperate deposits in Virginia are being partly covered by Holocene alluvium and bay mud.

  2. Microearthquakes at the active Trans-Atlantic Geotraverse (TAG) hydrothermal mound, Mid-Atlantic Ridge, 26°08'N

    NASA Astrophysics Data System (ADS)

    Pontbriand, C.; Reves-Sohn, R. A.

    2010-12-01

    A small 200 m aperture network of five ocean bottom seismometers around the periphery the active TAG hydrothermal mound on the Mid-Atlantic Ridge (26°08’N) detected microearthquake events that may be associated with the subsurface hydraulics of the massive hydrothermal deposit. Seismic data were sampled at 100 Hz for a period of eight months spanning June, 2003 to February, 2004, during which time 24,191 locatable events were detected. Microearthquake hypocenters are concentrated within a 300 m radius of the sulfide mound in the top 250 m of crust, and exhibit a conical shape with the deepest events beneath the mound center. Event rates are steady at 180 events per day at the beginning of the study period and decline slightly to 116 events per day after whale calls elevate background noise levels about 2/3 of the way through the deployment. The mean local magnitude of events is -1.2 with a range of -2.9≦ML≦0.3. We suggest that events may be largely due to hydraulic fracturing of clogged flow conduits in the mineral deposit, which provides the possibility of using the microearthquake data to constrain subsurface flow parameters and the permeability structure of the active TAG deposit. Figure: A bathymetric map of the TAG area depicts a small aperture network of 5 ocean bottom seismometers (white triangles) around the periphery of the active TAG hydrothermal mound. High resolution bathymetry is from Roman and Singh, 2005.

  3. Microbial community structure of hydrothermal deposits from geochemically different vent fields along the Mid-Atlantic Ridge

    USGS Publications Warehouse

    Flores, Gilberto E.; Campbell, James H.; Kirshtein, Julie D.; Meneghin, Jennifer; Podar, Mircea; Steinberg, Joshua I.; Seewald, Jeffrey S.; Tivey, Margaret Kingston; Voytek, Mary A.; Yang, Zamin K.; Reysenbach, Anna-Louise

    2011-01-01

    To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt-hosted Lucky Strike (37°17'N, 32°16.3'W, depth 1600-1750m) and the ultramafic-hosted Rainbow (36°13'N, 33°54.1'W, depth 2270-2330m) vent fields along the Mid-Atlantic Ridge (MAR). Using multiplexed barcoded pyrosequencing of the variable region 4 (V4) of the 16S rRNA genes, we show statistically significant differences between the archaeal and bacterial communities associated with the different vent fields. Quantitative polymerase chain reaction (qPCR) assays of the functional gene diagnostic for methanogenesis (mcrA), as well as geochemical modelling to predict pore fluid chemistries within the deposits, support the pyrosequencing observations. Collectively, these results show that the less reduced, hydrogen-poor fluids at Lucky Strike limit colonization by strict anaerobes such as methanogens, and allow for hyperthermophilic microaerophiles, like Aeropyrum. In contrast, the hydrogen-rich reducing vent fluids at the ultramafic-influenced Rainbow vent field support the prevalence of methanogens and other hydrogen-oxidizing thermophiles at this site. These results demonstrate that biogeographical patterns of hydrothermal vent microorganisms are shaped in part by large scale geological and geochemical processes.

  4. Simulation analysis of moored fluorometer time series from the Mid-Atlantic Bight during 1987--1990

    SciTech Connect

    Walsh, J.J.

    1990-01-01

    The goal of the previous research during 1987-1990 within the DOE (Department of Energy) Shelf Edge Exchange Processes (SEEP) program in the Mid-Atlantic Bight was to understand the physical and biogeochemical processes effecting the diffusive exchange of the proxies of energy-related, by-products associated with particulate matter between estuarine, shelf, and slope waters on this continental margin. As originally envisioned in the SEEP program plan, SEEP-III would take place at Cape Hatteras to study the advective exchange of materials by a major boundary current. One problem of continuing interest is the determination of the local assimilative capacity of slope waters and sediments off the eastern seaboard of the US to lengthen the pathway between potentially harmful energy by-products and man. At basin scales, realistic specification of the lateral transport by western boundary currents of particulate matter is a necessary input to global models of carbon/nitrogen cycling. Finally, at these global scales, the generic role of continental margins in cycling greenhouse gases, e.g. CO{sub 2}, CH{sub 4}, and N{sub 2}O, is now of equal interest. This continuing research of model construction and evaluation within the SEEP program focuses on all three questions at local, regional, and basin scales. Results from SEEP-I and II are discussed as well as plans for SEEP-III. 14 figs., 3 tabs.

  5. Carbon storage in old-growth forests of the Mid-Atlantic: toward better understanding the eastern forest carbon sink.

    PubMed

    McGarvey, Jennifer C; Thompson, Jonathan R; Epstein, Howard E; Shugart, Herman H

    2015-02-01

    Few old-growth stands remain in the matrix of secondary forests that dominates the eastern North American landscape. These remnant stands offer insight on the potential carbon (C) storage capacity of now-recovering secondary forests. We surveyed the remaining old-growth forests on sites characteristic of the general Mid-Atlantic United States and estimated the size of multiple components of forest C storage. Within and between old-growth stands, variability in C density is high and related to overstory tree species composition. The sites contain 219 ± 46 Mg C/ha (mean ± SD), including live and dead aboveground biomass, leaf litter, and the soil O horizon, with over 20% stored in downed wood and snags. Stands dominated by tulip poplar (Liriodendron tulipifera) store the most live biomass, while the mixed oak (Quercus spp.) stands overall store more dead wood. Total C density is 30% higher (154 Mg C/ha), and dead wood C density is 1800% higher (46 Mg C/ha) in the old-growth forests than in the surrounding younger forests (120 and 5 Mg C/ha, respectively). The high density of dead wood in old growth relative to secondary forests reflects a stark difference in historical land use and, possibly, the legacy of the local disturbance (e.g., disease) history. Our results demonstrate the potential for dead wood to maintain the sink capacity of secondary forests for many decades to come.

  6. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic): Atlantic marsh fiddler

    SciTech Connect

    Grimes, B.H.; Huish, M.T.; Kerby, J.H.; Moran, D.; National Wetlands Research Center, Slidell, LA )

    1989-09-01

    The Atlantic marsh fiddler is the only endemic species of Uca in the Mid-Atlantic region. Males display a series of visual and acoustical displays during mating, with a weak waving and bleaching of the larger claw. Egg clutch size in female varies. Larvae are released in phase with nocturnal high tides. The 5 zoeal and 1 megalops stages compose much of the estuarine plankton. First and second crab stages are weak and unable to burrow. Adult lifespan is 1--1.5 years with 1--2 molts per year. Molting is temperature dependent and ceases below 20{degree}C. Crabs feed by scrubbing the preferred muddy substratum for diatoms, fungi, vascular plants, and debris, bioturbating and recycling the marsh surface. This crab is eaten regularly by estuarine birds, fish, crabs, and some mammals. This fiddler can acclimate to lower temperatures, but dies below 2-3{degree}C or above 40{degree}C. It prefers seawater, lacking freshwater tolerance. Oxygen uptake correlates with activity. Preferred habitats are muddy substrata and short smooth cordgrass. Burrow density decreases from low to high marsh. The Atlantic marsh fiddler has the highest radiation LD-50 of sympatric species of fiddler crabs. Insecticides Temefos, DDT, DDF, Aldrin, and Dieldrin, and contaminant PCB's, mercury, and cadmium reduce populations of fiddlers, some being concentrated in their tissues. 90 refs., 4 figs.

  7. Effects of highway construction on stream water quality and macroinvertebrate condition in a Mid-Atlantic Highlands watershed, USA

    USGS Publications Warehouse

    Chen, Y.; Viadero, R.C.; Wei, X.; Fortney, Ronald H.; Hedrick, Lara B.; Welsh, S.A.; Anderson, James T.; Lin, L.-S.

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  8. Adolescent religiousness and its influence on substance use: preliminary findings from the Mid-Atlantic School Age Twin Study.

    PubMed

    D'Onofrio, B M; Murrelle, L; Eaves, L J; McCullough, M E; Landis, J L; Maes, H H

    1999-06-01

    Research has consistently shown that religiousness is associated with lower levels of alcohol and drug use, but little is known about the nature of adolescent religiousness or the mechanisms through which it influences problem behavior in this age group. This paper presents preliminary results from the Mid-Atlantic School Age Twin Study, a prospective, population-based study of 6-18-year-old twins and their mothers. Factor analysis of a scale developed to characterize adolescent religiousness, the Religious Attitudes and Practices Inventory (RAPI), revealed three factors: theism, religious/spiritual practices, and peer religiousness. Twin correlations and univariate behavior-genetic models for these factors and a measure of belief that drug use is sinful reveal in 357 twin pairs that common environmental factors significantly influence these traits, but a minor influence of genetic factors could not be discounted. Correlations between the multiple factors of adolescent religiousness and substance use, comorbid problem behavior, mood disorders, and selected risk factors for substance involvement are also presented. Structural equation modeling illustrates that specific religious beliefs about the sinfulness of drugs and level of peer religiousness mediate the relationship between theistic beliefs and religious/spiritual practices on substance use. Limitations and future analyses are discussed.

  9. Effects of highway construction on stream water quality and macroinvertebrate condition in a mid-Atlantic highlands watershed, USA

    USGS Publications Warehouse

    Welsh, Stuart A.; Chen, Yushun; Viadero, Stuart C.; Wei, Xinchao; Hedrick, Lara B.; Anderson, James T.; Lin, Lian-Shin

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997–2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

  10. Effects of highway construction on stream water quality and macroinvertebrate condition in a mid-atlantic highlands watershed, USA.

    PubMed

    Chen, Yushun; Viadero, Roger C; Wei, Xinchao; Fortney, Ronald; Hedrick, Lara B; Welsh, Stuart A; Anderson, James T; Lin, Lian-Shin

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

  11. Distinct Benthic Community Trends Driven by Particle Transport and Deposition in Mid-Atlantic Bight Canyons, NW Atlantic

    NASA Astrophysics Data System (ADS)

    Demopoulos, A. W.; Robertson, C. M.; Bourque, J. R.; Mienis, F.; Duineveld, G.; Ross, S.; Brooke, S.; Davies, A. J.

    2014-12-01

    The Mid-Atlantic Bight (MAB) is a well-studied region of the U.S. East coast continental margin, rich in submarine canyons. Baltimore and Norfolk canyons were studied during the multidisciplinary Atlantic Deepwater Canyons project through funding from BOEM, NOAA, and USGS. Sediment and water column properties were assessed in the context of canyon physical dynamics and ecosystem ecology. Sediment samples were collected by NIOZ box corer in 2012 and 2013 along canyon axes and comparative adjacent slopes at standardized depths. Sediments were analyzed for grain size, organic content, stable carbon and nitrogen isotopes, chlorophyll a, and benthic infauna. Water column properties were sampled using CTD transects, and benthic landers and moorings positioned along canyon axes. Significant differences in sediment transport regimes were found for each canyon where observed nepheloid layers corresponded to shifts in infaunal community structure. Significant community shifts were observed in stations at depths > 900m in Baltimore Canyon, coinciding with higher organic matter concentrations at depths below the nepheloid layer. In contrast, adjacent slope communities exhibited a more uniform infaunal assemblage where distinct zonation patterns by depth were observed. Preliminary data for Norfolk Canyon suggest very different sediment deposition rates in the canyon and also show clear differences between canyon and slope benthic communities. Geological processes and canyon topography coupled with organic inputs and disturbance events are clear factors in determining benthic infaunal diversity and standing stock dynamics in and around these canyons.

  12. Nitrogen Stimulates the Growth of Subsurface Basalt-associated Microorganisms at the Western Flank of the Mid-Atlantic Ridge

    PubMed Central

    Zhang, Xinxu; Fang, Jing; Bach, Wolfgang; Edwards, Katrina J.; Orcutt, Beth N.; Wang, Fengping

    2016-01-01

    Oceanic crust constitutes the largest aquifer system on Earth, and microbial activity in this environment has been inferred from various geochemical analyses. However, empirical documentation of microbial activity from subsurface basalts is still lacking, particularly in the cool (<25°C) regions of the crust, where are assumed to harbor active iron-oxidizing microbial communities. To test this hypothesis, we report the enrichment and isolation of crust-associated microorganisms from North Pond, a site of relatively young and cold basaltic basement on the western flank of the Mid-Atlantic Ridge that was sampled during Expedition 336 of the Integrated Ocean Drilling Program. Enrichment experiments with different carbon (bicarbonate, acetate, methane) and nitrogen (nitrate and ammonium) sources revealed significant cell growth (one magnitude higher cell abundance), higher intracellular DNA content, and increased Fe3+/ΣFe ratios only when nitrogen substrates were added. Furthermore, a Marinobacter strain with neutrophilic iron-oxidizing capabilities was isolated from the basalt. This work reveals that basalt-associated microorganisms at North Pond had the potential for activity and that microbial growth could be stimulated by in vitro nitrogen addition. Furthermore, iron oxidation is supported as an important process for microbial communities in subsurface basalts from young and cool ridge flank basement. PMID:27199959

  13. Diversity and Metabolic Potentials of Subsurface Crustal Microorganisms from the Western Flank of the Mid-Atlantic Ridge

    PubMed Central

    Zhang, Xinxu; Feng, Xiaoyuan; Wang, Fengping

    2016-01-01

    Deep-sea oceanic crust constitutes the largest region of the earth’s surface. Accumulating evidence suggests that unique microbial communities are supported by iron cycling processes, particularly in the young (<10 million-year old), cool (<25°C) subsurface oceanic crust. To test this hypothesis, we investigated the microbial abundance, diversity, and metabolic potentials in the sediment-buried crust from “North Pond” on western flank of the Mid-Atlantic Ridge. Three lithologic units along basement Hole U1383C were found, which typically hosted ∼104 cells cm-3 of basaltic rock, with higher cell densities occurring between 115 and 145 m below seafloor. Similar bacterial community structures, which are dominated by Gammaproteobacterial and Sphingobacterial species closely related to iron oxidizers, were detected regardless of variations in sampling depth. The metabolic potentials of the crust microbiota were assayed by metagenomic analysis of two basalt enrichments which showed similar bacterial structure with the original sample. Genes coding for energy metabolism involved in hydrocarbon degradation, dissimilatory nitrate reduction to ammonium, denitrification and hydrogen oxidation were identified. Compared with other marine environments, the metagenomes from the basalt-hosted environments were enriched in pathways for Fe3+ uptake, siderophore synthesis and uptake, and Fe transport, suggesting that iron metabolism is an important energy production and conservation mechanism in this system. Overall, we provide evidence that the North Pond crustal biosphere is dominated by unique bacterial groups with the potential for iron-related biogeochemical cycles. PMID:27047476

  14. Occurrence of deep-water corals on the Mid-Atlantic Ridge based on MAR-ECO data

    NASA Astrophysics Data System (ADS)

    Mortensen, P. B.; Buhl-Mortensen, L.; Gebruk, A. V.; Krylova, E. M.

    2008-01-01

    Occurrence of deep-water corals on the Mid-Atlantic Ridge between the southern part of the Reykjanes Ridge and the Azores has been examined based on video surveys using remotely operated vehicles (ROV) and bycatch from longline and bottom trawl. Eight sites were surveyed with ROVs, and the bycatch material came from 16 trawl hauls and nine longline sets. Corals were observed at all sites surveyed with ROVs at depths between 800 and 2400 m, but most commonly shallower than 1400 m. The species richness of corals was high, with a total of 40 taxa recorded. Octocorals dominated the coral fauna with 27 taxa. Lophelia pertusa was one of the most frequently observed corals, present at five of the eight surveyed sites. It occurred on basaltic outcrops on the seamounts but always as relatively small colonies (<0.5 m in diameter). Massive live reef structures were not observed. The deepest record of Lophelia was at 1340 m, south of the Charlie Gibbs Fracture Zone. Accumulations of dead debris of coral skeletons could indicate a presence of former large Lophelia reefs at several locations. The number of megafaunal taxa was 1.6 times higher in areas where corals were present compared to areas without corals. Typical taxa that co-occurred with Lophelia were crinoids, certain sponges, the bivalve Acesta excavata, and squat lobsters. Signs of destructive fishing and lost gillnets were observed at several locations. The impact of fishing on deep-sea corals is discussed.

  15. Microbial community structure of hydrothermal deposits from geochemically different vent fields along the Mid-Atlantic Ridge

    SciTech Connect

    Flores, Gilberto E; Campbell, James H; Kirshtein, Julie D; Meneghin, Jennifer; Podar, Mircea; Steinberg, Joshua; Seewald, Jeffrey S; Tivey, Margaret Kingston; Voytek, Mary A; Reysenbach, Anna-Louise; Yang, Zamin Koo

    2011-01-01

    To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt-hosted Lucky Strike (37 17'N, 32 16.3'W, depth 1600-1750 m) and the ultramafic-hosted Rainbow (36 13'N, 33 54.1'W, depth 2270-2330 m) vent fields along the Mid-Atlantic Ridge (MAR). Using multiplexed barcoded pyrosequencing of the variable region 4 (V4) of the 16S rRNA genes, we show statistically significant differences between the archaeal and bacterial communities associated with the different vent fields. Quantitative polymerase chain reaction (qPCR) assays of the functional gene diagnostic for methanogenesis (mcrA), as well as geochemical modelling to predict pore fluid chemistries within the deposits, support the pyrosequencing observations. Collectively, these results show that the less reduced, hydrogen-poor fluids at Lucky Strike limit colonization by strict anaerobes such as methanogens, and allow for hyperthermophilic microaerophiles, like Aeropyrum. In contrast, the hydrogen-rich reducing vent fluids at the ultramafic-influenced Rainbow vent field support the prevalence of methanogens and other hydrogen-oxidizing thermophiles at this site. These results demonstrate that biogeographical patterns of hydrothermal vent microorganisms are shaped in part by large scale geological and geochemical processes.

  16. Nitrogen Stimulates the Growth of Subsurface Basalt-associated Microorganisms at the Western Flank of the Mid-Atlantic Ridge.

    PubMed

    Zhang, Xinxu; Fang, Jing; Bach, Wolfgang; Edwards, Katrina J; Orcutt, Beth N; Wang, Fengping

    2016-01-01

    Oceanic crust constitutes the largest aquifer system on Earth, and microbial activity in this environment has been inferred from various geochemical analyses. However, empirical documentation of microbial activity from subsurface basalts is still lacking, particularly in the cool (<25°C) regions of the crust, where are assumed to harbor active iron-oxidizing microbial communities. To test this hypothesis, we report the enrichment and isolation of crust-associated microorganisms from North Pond, a site of relatively young and cold basaltic basement on the western flank of the Mid-Atlantic Ridge that was sampled during Expedition 336 of the Integrated Ocean Drilling Program. Enrichment experiments with different carbon (bicarbonate, acetate, methane) and nitrogen (nitrate and ammonium) sources revealed significant cell growth (one magnitude higher cell abundance), higher intracellular DNA content, and increased Fe(3+)/ΣFe ratios only when nitrogen substrates were added. Furthermore, a Marinobacter strain with neutrophilic iron-oxidizing capabilities was isolated from the basalt. This work reveals that basalt-associated microorganisms at North Pond had the potential for activity and that microbial growth could be stimulated by in vitro nitrogen addition. Furthermore, iron oxidation is supported as an important process for microbial communities in subsurface basalts from young and cool ridge flank basement.

  17. Mesophotic reef fish assemblages of the remote St. Peter and St. Paul's Archipelago, Mid-Atlantic Ridge, Brazil

    NASA Astrophysics Data System (ADS)

    Rosa, Marcos Rogerio; Alves, Aline Cristina; Medeiros, Diego Valverde; Coni, Ericka Oliveira Cavalcanti; Ferreira, Camilo Moitinho; Ferreira, Beatrice Padovani; de Souza Rosa, Ricardo; Amado-Filho, Gilberto Menezes; Pereira-Filho, Guilherme Henrique; de Moura, Rodrigo Leão; Thompson, Fabiano Lopes; Sumida, Paulo Yukio Gomes; Francini-Filho, Ronaldo Bastos

    2016-03-01

    Mesophotic reef fish assemblages (30-90 m depth) of the small and remote St. Peter and St. Paul's Archipelago (SPSPA), Mid-Atlantic Ridge, Brazil, were characterized using remotely operated vehicles. Ordination analyses identified distinct fish assemblages in the upper (30-50 m) and lower (50-90 m) mesophotic zones, the former characterized by high abundances of species that are also abundant at euphotic reefs ( Caranx lugubris, Melichthys niger, Stegastes sanctipauli and Chromis multilineata) and the latter dominated by two mesophotic specialists ( Prognathodes obliquus and Chromis enchrysura). Planktivores dominated fish assemblages, particularly in the upper mesophotic zone, possibly due to a greater availability of zooplankton coming from the colder Equatorial Undercurrent in mesophotic depths of the SPSPA. Turf algae, fleshy macroalgae and scleractinian corals dominated benthic assemblages between 30 and 40 m depth, while bryozoans, black corals and sponges dominated between 40 and 90 m depth. Canonical correspondence analysis explained 74 % of the relationship between environmental characteristics (depth, benthic cover and complexity) and structure of fish assemblages, with depth as the most important independent variable. Juveniles of Bodianus insularis and adults of P. obliquus and C. enchrysura were clearly associated with branching black corals ( Tanacetipathes spp.), suggesting that black corals play key ecological roles in lower mesophotic reefs of the SPSPA. Results from this study add to the global database about mesophotic reef ecosystems (MREs) and provide a baseline for future evaluations of possible anthropogenic and natural disturbances on MREs of the SPSPA.

  18. Thermosipho affectus sp. nov., a thermophilic, anaerobic, cellulolytic bacterium isolated from a Mid-Atlantic Ridge hydrothermal vent.

    PubMed

    Podosokorskaya, O A; Kublanov, I V; Reysenbach, A-L; Kolganova, T V; Bonch-Osmolovskaya, E A

    2011-05-01

    A novel obligately anaerobic, extremely thermophilic, organotrophic bacterium, strain ik275mar(T), was isolated from a Mid-Atlantic Ridge deep-sea hydrothermal vent. Cells were rods surrounded by a sheath-like structure (toga), 0.4-0.9 µm in width and 1.2-6.0 µm in length. Strain ik275mar(T) grew at 37-75 °C, pH 5.6-8.2 and at NaCl concentrations of 10-55 g l(-1). Under optimum conditions (70 °C, pH 6.6, NaCl 20 g l(-1)), doubling time was 32 min. The isolate was able to ferment carbohydrates including starch, cellulose and cellulose derivatives. Acetate, H(2) and CO(2) were the main products of glucose fermentation. G+C content of DNA was 27 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain ik275mar(T) is a member of the genus Thermosipho. 16S rRNA gene sequence identity with the other species of the genus Thermosipho ranged from 93.7 to 94.5 %. Based on the phylogenetic analysis and physiological properties of the novel isolate, we propose a novel species, Thermosipho affectus sp. nov., with type strain ik275mar(T) ( = DSM 23112(T)  = VKM B-2574(T)).

  19. Volcanic Glasses as Habitat for Microfossils: Evidence from the Early Paleoproterozoic Pillow Lavas of Karelia and their Modern Analogues in the Mid-Atlantic Ridge

    NASA Technical Reports Server (NTRS)

    Adtafieva, M. M.; Rozanov, A. Yu; Sharkov, E. V.; Chistyakov, A. V.; Bogina, M. M.; Hoover, R. B.

    2009-01-01

    Microbial complexes were identified in the volcanic glasses from the ancient (2.4-Ga-old basaltic pillow-lavas of Karelia) and modern (pillow lavas of Mid-Atlantic ridge) volcanic rocks. It was shown that that their microbial colonization is likely to occur by the same mechanism. Thus, well preserved pillow lavas, which occupy a spacious fields in the Archean and Early Paleoproterozoic greenstone belts, are promising object for search of the earliest traces of life on Earth.

  20. Wave refraction diagrams for the Baltimore Canyon region of the mid-Atlantic continental shelf computed by using three bottom topography approximation techniques

    NASA Technical Reports Server (NTRS)

    Poole, L. R.

    1976-01-01

    The Langley Research Center and Virginia Institute of Marine Science wave refraction computer model was applied to the Baltimore Canyon region of the mid-Atlantic continental shelf. Wave refraction diagrams for a wide range of normally expected wave periods and directions were computed by using three bottom topography approximation techniques: quadratic least squares, cubic least squares, and constrained bicubic interpolation. Mathematical or physical interpretation of certain features appearing in the computed diagrams is discussed.

  1. The effects of macroinvertebrate taxonomic resolution in large landscape bioassessments: An example from the Mid-Atlantic Highlands, U.S.A.

    USGS Publications Warehouse

    Waite, I.R.; Herlihy, A.T.; Larsen, D.P.; Urquhart, N.S.; Klemm, D.J.

    2004-01-01

    1. During late spring 1993-1995, the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) sampled 490 wadeable streams in the mid-Atlantic Highlands (MAH) of the U.S. for a variety of physical, chemical and biological indicators of environmental condition. We used the resulting data set to evaluate the importance of differing levels of macroinvertebrate taxonomic resolution in bioassessments by comparing the ability of family versus genus to detect differences among sites classified by type and magnitude of human impact and by stream size. We divided the MAH into two physiographic regions: the Appalachian Plateau where mine drainage (MD) and acidic deposition are major stressors, and the Ridge and Valley where nutrient enrichment is a major stressor. Stream sites were classified into three or four impact classes based on water chemistry and habitat. We used stream order (first to third Strahler order) in each region as a measure of stream size. Ordination, 2 x 2 chi-square and biotic metrics were used to compare the ability of family and genus to detect differences among both stressor and size classes. 2. With one notable exception, there were only a small number of different genera per family (interquartile range = 1-4). Family Chironomidae, however, contained 123 different genera. As a result, significant information loss occurred when this group was only classified to family. The family Chironomidae did not discriminate among the predefined classes but many chironomid genera did: by chi-square analysis, 10 and 28 chironomid genera were significant in discriminating MD and nutrient impacts, respectively. 3. Family and genus data were similar in their ability to distinguish among the coarse impacts (e.g. most severe versus least severe impact classes) for all cases. Though genus data in many cases distinguished the subtler differences (e.g. mixed/moderate impacts versus high or low impacts) better than family, differences

  2. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Atlantic silverside

    SciTech Connect

    Fay, C.W.; Neves, R.J.; Pardue, G.B.

    1983-10-01

    Species profiles are literature summaries of the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. They are prepared to assist in environmental impact assessment. The Atlantic silverside (Menidia menidia) is an important link in estuarine food webs as an opportunistic omnivore and as forage for large piscivores such as striped bass (Morone saxatilis) and bluefish (Pomatomus saltatrix). Many times the Atlantic silverside is the most abundant fish species encountered in estuaries and tributaries. They mature at age 1 and spawn in the intertidal zone of estuaries from March to June in the mid-Atlantic region. Few 2-year-old fish are ever encountered, so the Atlantic silverside is basically a short-lived species. Most spawning occurs at high tide during new or full moon phases. Eggs are adhesive and are found attached to submerged vegetation. Larvae, juveniles, and adults generally inhabit similar areas. Sex is determined in larval development 32 to 46 days after hatching, and is a function of parental genotype and water temperature regime during the critical period. Fisheries for this species are not documented. Eggs can tolerate water temperatures between 15/sup 0/ and 30/sup 0/C, and larvae need temperatures above 15/sup 0/C for survival. Larvae tolerate relatively acute temperature increases. Upper lethal temperatures for juveniles and adults range from 30.5/sup 0/ to 33.8/sup 0/C, depending on acclimation temperature. Salinities of 20 ppt or lower significantly delay hatching and affect larval survival. Juveniles and adults tolerate the full range of naturally occurring salinities (i.e., freshwater to at least 37.8 ppt). 57 references, 2 figures.

  3. Landscape controls on the timing of spring, autumn, and growing season length in mid-Atlantic forests

    USGS Publications Warehouse

    Elmore, A.J.; Guinn, S.M.; Minsley, B.J.; Richardson, A.D.

    2012-01-01

    The timing of spring leaf development, trajectories of summer leaf area, and the timing of autumn senescence have profound impacts to the water, carbon, and energy balance of ecosystems, and are likely influenced by global climate change. Limited field-based and remote-sensing observations have suggested complex spatial patterns related to geographic features that influence climate. However, much of this variability occurs at spatial scales that inhibit a detailed understanding of even the dominant drivers. Recognizing these limitations, we used nonlinear inverse modeling of medium-resolution remote sensing data, organized by day of year, to explore the influence of climate-related landscape factors on the timing of spring and autumn leaf-area trajectories in mid-Atlantic, USA forests. We also examined the extent to which declining summer greenness (greendown) degrades the precision and accuracy of observations of autumn offset of greenness. Of the dominant drivers of landscape phenology, elevation was the strongest, explaining up to 70% of the spatial variation in the onset of greenness. Urban land cover was second in importance, influencing spring onset and autumn offset to a distance of 32 km from large cities. Distance to tidal water also influenced phenological timing, but only within ~5 km of shorelines. Additionally, we observed that (i) growing season length unexpectedly increases with increasing elevation at elevations below 275 m; (ii) along gradients in urban land cover, timing of autumn offset has a stronger effect on growing season length than does timing of spring onset; and (iii) summer greendown introduces bias and uncertainty into observations of the autumn offset of greenness. These results demonstrate the power of medium grain analyses of landscape-scale phenology for understanding environmental controls on growing season length, and predicting how these might be affected by climate change.

  4. Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

    NASA Astrophysics Data System (ADS)

    Obelcz, Jeffrey; Brothers, Daniel; Chaytor, Jason; Brink, Uri ten; Ross, Steve W.; Brooke, Sandra

    2014-06-01

    Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5-10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

  5. Comparing biosignatures from North Pond, Mid-Atlantic Ridge and the Louisville Seamount Chain, off New Zealand

    NASA Astrophysics Data System (ADS)

    Türke, Andreas; Ménez, Bénédicte; Bach, Wolfgang

    2016-04-01

    The subseafloor ocean represents Earth's largest aquifer and the flow of seawater fluxed through these flanks is > 1016 L/yr, rivaling the rate of river discharge into the oceans. When volcanic basalt glass is exposed to oxygen-rich seawater, rims of palagonite form at the expense of glass. Within subseafloor basalt glass, a range of putative microbial biosignatures have been interpreted as traces of life in these basaltic aquifers, and these have been studied as a potential analogue for early life on Earth or extraterrestrial habitats for several years. However, little is known about the relationship of the physical and chemical nature of the habitat and the prevalent types of biosignatures. We report and compare biosignatures from two distinctly different study sites that vary strongly. We analyzed rock samples microscopically for their putative textural biosignatures and their associated organic molecules via Fourier transform infrared spectrometry. The biosignatures found in basalts from the North Pond Region, at the western flank of the Mid-Atlantic Ridge 23°N, which is young well-oxygenated crust, are characterized by a small textural diversity. However, the organic molecules associated, show evidence for the occurrence of complex molecules like proteins. In contrast, the biosignatures from the Louisville Seamount Chain, which are much older (50 - 80 Ma), are more diverse in terms of textures, while the organic molecules are more degraded and suggest an Archaeal origin. We propose that microbial communities change significantly during crustal evolution and that microbes associated with older and severely altered crust may not be related to the textures commonly found within subseafloor basalt glass and often interpreted as trace fossils.

  6. Trawled megafaunal invertebrate assemblages from bathyal depth of the Mid-Atlantic Ridge (48°-54°N)

    NASA Astrophysics Data System (ADS)

    Alt, Claudia H. S.; Rogacheva, Antonina; Boorman, Benjamin; Alan Hughes, J.; Billett, David S. M.; Gooday, Andrew J.; Jones, Daniel O. B.

    2013-12-01

    We investigated the effects of contrasting surface primary production on the benthic invertebrate megafauna at four sites on the Mid-Atlantic Ridge. The sites, designated NW, NE, SW and SE, were located to the west and east of the Ridge axis and to the north and south of the Charlie-Gibbs Fracture Zone. Benthic megafauna were sampled in 2007 and 2009 with a semi-balloon otter trawl, at a target depth of 2,500 m. The total biomass and density of major taxonomic groups did not differ significantly between sites, despite those to the north being characterised by greater surface productivity than those to the south. However, the density and biomass of individual taxonomic groups, as well as diversity and body size, all showed significant differences between sites. Diversity was highest at the SE, and lowest at the NE site. Most species were larger to the north. Community composition was significantly different between all sites, with the greatest number of unique species found at the SE, and noticeably fewer unique species at the northern sites. There was no clear correlation between the surface productivity and community structure, suggesting complex ecological controls on the communities. It is speculated that, in addition to the energy supply, drivers such as strong currents and sediment characteristics, play an important role in shaping the communities at the different sites. To what extent the ridge acts as a dispersal barrier for benthic invertebrate fauna remains unclear. However, high numbers of species unique to the southern site suggest a limited dispersal between the northern and southern areas.

  7. Thermodesulfatator atlanticus sp. nov., a thermophilic, chemolithoautotrophic, sulfate-reducing bacterium isolated from a Mid-Atlantic Ridge hydrothermal vent.

    PubMed

    Alain, Karine; Postec, Anne; Grinsard, Elodie; Lesongeur, Françoise; Prieur, Daniel; Godfroy, Anne

    2010-01-01

    A novel, strictly anaerobic, thermophilic, sulfate-reducing bacterium, designated strain AT1325(T), was isolated from a deep-sea hydrothermal vent at the Rainbow site on the Mid-Atlantic Ridge. This strain was subjected to a polyphasic taxonomic analysis. Cells were Gram-negative motile rods (approximately 2.4 x 0.6 microm) with a single polar flagellum. Strain AT1325(T) grew at 55-75 degrees C (optimum, 65-70 degrees C), at pH 5.5-8.0 (optimum, 6.5-7.5) and in the presence of 1.5-4.5 % (w/v) NaCl (optimum, 2.5 %). Cells grew chemolithoautotrophically with H2 as an energy source and SO4(2-) as an electron acceptor. Alternatively, the novel isolate was able to use methylamine, peptone or yeast extract as carbon sources. The dominant fatty acids (>5 % of the total) were C(16 : 0), C(18 : 1)omega7c, C(18 : 0) and C(19 : 0) cyclo omega8c. The G+C content of the genomic DNA of strain AT1325(T) was 45.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences placed strain AT1325(T) within the family Thermodesulfobacteriaceae, in the bacterial domain. Comparative 16S rRNA gene sequence analysis indicated that strain AT1325(T) belonged to the genus Thermodesulfatator, sharing 97.8 % similarity with the type strain of Thermodesulfatator indicus, the unique representative species of this genus. On the basis of the data presented, it is suggested that strain AT1325(T) represents a novel species of the genus Thermodesulfatator, for which the name Thermodesulfatator atlanticus sp. nov. is proposed. The type strain is AT1325(T) (=DSM 21156(T)=JCM 15391(T)).

  8. Biophysical and Population Genetic Models Predict the Presence of "Phantom" Stepping Stones Connecting Mid-Atlantic Ridge Vent Ecosystems.

    PubMed

    Breusing, Corinna; Biastoch, Arne; Drews, Annika; Metaxas, Anna; Jollivet, Didier; Vrijenhoek, Robert C; Bayer, Till; Melzner, Frank; Sayavedra, Lizbeth; Petersen, Jillian M; Dubilier, Nicole; Schilhabel, Markus B; Rosenstiel, Philip; Reusch, Thorsten B H

    2016-09-12

    Deep-sea hydrothermal vents are patchily distributed ecosystems inhabited by specialized animal populations that are textbook meta-populations. Many vent-associated species have free-swimming, dispersive larvae that can establish connections between remote populations. However, connectivity patterns among hydrothermal vents are still poorly understood because the deep sea is undersampled, the molecular tools used to date are of limited resolution, and larval dispersal is difficult to measure directly. A better knowledge of connectivity is urgently needed to develop sound environmental management plans for deep-sea mining. Here, we investigated larval dispersal and contemporary connectivity of ecologically important vent mussels (Bathymodiolus spp.) from the Mid-Atlantic Ridge by using high-resolution ocean modeling and population genetic methods. Even when assuming a long pelagic larval duration, our physical model of larval drift suggested that arrival at localities more than 150 km from the source site is unlikely and that dispersal between populations requires intermediate habitats ("phantom" stepping stones). Dispersal patterns showed strong spatiotemporal variability, making predictions of population connectivity challenging. The assumption that mussel populations are only connected via additional stepping stones was supported by contemporary migration rates based on neutral genetic markers. Analyses of population structure confirmed the presence of two southern and two hybridizing northern mussel lineages that exhibited a substantial, though incomplete, genetic differentiation. Our study provides insights into how vent animals can disperse between widely separated vent habitats and shows that recolonization of perturbed vent sites will be subject to chance events, unless connectivity is explicitly considered in the selection of conservation areas.

  9. On the mass and salt budgets for a region of the continental shelf in the southern Mid-Atlantic Bight

    SciTech Connect

    Kim, Yoo Yin; Weatherly, Georges L.; Pietrafesa, Leonard J.

    2001-12-01

    Two field studies were conducted across and along the continental shelf, one from February to May 1996 (deployment 1) and the other from July to October 1996 (deployment 2), in part to determine the mass and salt budgets of shelf water from south of Cape Henry to north of Cape Hatteras, the southernmost portion of the Mid-Atlantic Bight. The temporal means of current meter records indicated that most of the water enters the region across its northern boundary near the shelf break as part of a southward, alongshore current and exits the southeast corner as a southeastward flowing current. Estimates of the volume transports indicated that not all the transport across the northern boundary was accounted for by transport across the southern boundary, and that the remainder occurred as a broad, diffusive flow across the eastern boundary at the shelf break. Time series of volume transport across northern and southern boundaries were very similar and associated with variations in the alongshore wind stress and sea level, indicative of a geostrophic balance. Examination of the individual current meter records indicated these fluctuations were very barotropic even during deployment 2, which included the stratified summer season. Time series of the volume transport across the eastern boundary at the shelf break strongly mirrored the volume transport across the northern boundary minus that across the southern boundary, suggesting that the inferred eastern boundary transport was real and accommodated whatever the southern boundary could not. The turbulent salt flux across each boundary contributes very little to the net respective mass fluxes because the salt fluxes are almost governed by current velocity fields. The instantaneous and mean salt fluxes across each boundary were very well approximated by the instantaneous and mean volume transports across the boundary times the deployment average salinity across that boundary, respectively. The Ocean Margins Program (OMP) moored

  10. Seasonal variations of fine particulate organosulfates derived from biogenic and anthropogenic hydrocarbons in the mid-Atlantic United States

    NASA Astrophysics Data System (ADS)

    Meade, L. Edward; Riva, Matthieu; Blomberg, Max Z.; Brock, Amanda K.; Qualters, Elisa Marie; Siejack, Richard A.; Ramakrishnan, Kumar; Surratt, Jason D.; Kautzman, Kathryn E.

    2016-11-01

    Organosulfates (OSs) are an important and ubiquitous class of organic compounds found in ambient fine particulate matter (PM2.5) that serves as markers for multiphase chemical processes leading to secondary organic aerosol (SOA) formation. In this study, high-volume filter sampling was implemented to collect PM2.5 samples during the August 2012-June 2013 time period in suburban Towson, MD. By utilizing ultra-performance liquid chromatography coupled with high-resolution quadrupole time-of-flight mass spectrometry employing an electrospray ionization source (UPLC/ESI-HR-QTOFMS), 58 OSs were characterized and quantified in PM2.5 collected across all seasons. The selection of the extraction solvent was also found to be important for OS characterization. Seasonal trends demonstrate that the atmospheric oxidation of biogenic volatile organic compounds (VOCs) dominates OS formation in early fall and spring, with substantial contributions from isoprene OS (∼15 ng/m3), and limonene and α-pinene OS (∼5 ng/m3). From November to March anthropogenic OSs, including polycyclic aromatic hydrocarbon (PAH)- and alkane-derived OSs recently characterized in laboratory-generated SOA, reached their highest levels averaging 4 ng/m3. Nitrogen-containing OSs derived from terpene chemistry remain consistent over the sampling period averaging 2 ng/m3 and do not demonstrate strong seasonal fluctuations. Correlations between the identified OSs and known organic acids that arise from either the atmospheric oxidation of biogenic or anthropogenic VOCs assist in source apportionment. Meteorological data coupled with air mass back-trajectory analyses using HYSPLIT provide insight into meteorological and transport conditions that promote the formation/occurrence of OSs within the mid-Atlantic U.S. region.

  11. OBS records of Whale vocalizations from Lucky-strike segment of the Mid-Atlantic Ridge during 2007-2008

    NASA Astrophysics Data System (ADS)

    Chauhan, A.; Rai, A.; Singh, S. C.; Crawford, W. C.; Escartin, J.; Cannat, M.

    2009-12-01

    Passive seismic experiments to study seismicity require a long term deployment of ocean-bottom seismometers (OBSs). These instruments also record a large amount of non-seismogenic signals such as movement of large ships, air-gun shots, and marine mammal vocalizations. We report a bi-product of our passive seismic experiment (BBMOMAR) conducted around the Lucky-strike hydrothermal field of the slow-spreading mid-Atlantic ridge. Five multi-component ocean-bottom seismometers (recording two horizontal, one vertical and one pressure channel) were deployed during 2007-2008. During 13 months of deployment, abundant vocalizations of marine mammals have been recorded by all the five equipments. By analyzing the frequency content of data and their pattern of occurrence, we conclude that these low-frequency vocalizations (~20-40 Hz) typically corresponds to blue and fin-whales. These signals if not identified, could be mis-interpreted as underwater seismic/hydrothermal activity. Our data show an increase in the number of vocalizations recorded during the winter season relative to the summer. As part of the seismic monitoring of the Lucky-strike site, we anticipate to extend this study to the 2008-2009 and 2009-2010 periods, after the recovery and deployment of the array during the BATHYLUCK09 cruise. Long-term and continuous records of calls of marine mammals provide valuable information that could be used to identify the species, study their seasonal behaviour and their migration paths. Our study suggestes that passive experiments such as ocean-bottom seismometers deployed at key locations, could provide useful secondary infromation about oceanic species besides recording seismicity, which is otherwise not possible without harming or interfering with their activity.

  12. End-Pleistocene Soil Constituents from Selected Sites on the Mid-Atlantic Coastal Plain: First Results

    NASA Astrophysics Data System (ADS)

    Lecompte, M. A.; Rock, B. N.; Demitroff, M.; Reid, M.; Lucas, L.; Hughes, D.; Hayden, L. B.

    2008-12-01

    Stratigraphic analyses of soil samples taken from dated and undated sites located along the mid-Atlantic Coastal Plain have yielded evidence of increased contemporary biomass burning, compared to under and overlying strata. Host strata ages are known or projected to bracket the onset of the Younger Dryas cooling episode at 12.9 cal ka. This ongoing investigation includes samples from: 1) a late-Pleistocene aged periglacial feature located within the Pine Barrens of southern New Jersey; 2) an artifact dated stratum (~ 12.9 ka) in an embankment on the Chesapeake Bay in Maryland; and 3) an as yet undated (C14 test results pending) embankment of the Perquimans River in northeastern North Carolina projected to be age-appropriate. Sample analysis of scanning electron (SEM) micrographs from the Chesapeake Bay site revealed charred fragments of late-Wisconsinan Krummholz birch (Betula) and species of spruce (Picea) and fir (Abies), which are not extant on the modern-day, temperate Coastal Plain. In addition, organic faunal material is found in association with ancient charred boreal wood, including hollow hair and skin fragments that are as yet unidentified, perhaps from cold climate adapted animals as inferred from host sediment age. Charred wood fragments are found to be attracted to a neodymium magnet. Some aggregates of organic matter appear to contain magnetic spherule-like grains whose composition is awaiting geochemical analysis. Photomicrographs of all specimens and a stratigraphic breakdown in the relative amount of burned carbon associated with each site and strata will be presented, along with the results of various analyses that are currently underway.

  13. Characteristic length scales and time-averaged transport velocities of suspended sediment in the mid-Atlantic Region, USA

    USGS Publications Warehouse

    Pizzuto, James; Schenk, Edward R.; Hupp, Cliff R.; Gellis, Allen; Noe, Greg; Williamson, Elyse; Karwan, Diana L.; O'Neal, Michael; Marquard, Julia; Aalto, Rolf; Newbold, Denis

    2014-01-01

    Watershed Best Management Practices (BMPs) are often designed to reduce loading from particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles are only moved downstream episodically, resting for long periods in storage between transport events. A theory is developed that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage given sediment budget data (by grain size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended sediment transport length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At 5 upland watersheds of the mid-Atlantic region, transport length scales for silt-clay range from 4 to 60 km, while those for sand range from 0.4 to 113 km. Mean sediment velocities for silt-clay range from 0.0072 km/yr to 0.12 km/yr, while those for sand range from 0.0008 km/yr to 0.20 km/yr, 4–6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100–1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to determine the complete distribution of suspended sediment velocities in real watersheds.

  14. Fish parasites in the bathyal zone: The halosaur Halosauropsis macrochir (Günther, 1878) from the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Klimpel, S.; Palm, H. W.; Busch, M. W.; Kellermanns, E.

    2008-01-01

    A total of 42 Halosauropsis macrochir from a single position on the Mid-Atlantic Ridge (MAR) were collected for studies on parasites and feeding ecology. A total of 9 different parasite species were found, with most of them belonging to the Digenea (4 species) and Nematoda (3). The host specific Degeneria halosauri, (Digenea) and Cystidicolidae indet. (Nematoda) were the predominant species, reaching a prevalence of 100.0% and 57.1% with intensities of infection of 1-12 and 1-10, respectively. Less host specific parasites such as Gonocerca phycidis (Digenea) and Tetraphyllidea indet. (Cestoda) occurred at low rates of infection. The parasite fauna of this bathyal fish can be described as predominantly adult and host specific, with larval and less host specific components. A total of 16 different food groups were identified, most of them of benthic origin or associated with the benthopelagial. The predominant prey organisms belonged to the Crustacea (e.g., Copepoda, Gammaridea, Amphipoda and Isopoda), which serve as main parasite vectors for H. macrochir. This deep-sea fish seems to follow a general pattern of fish parasites in the deep sea, with most isolated parasites belonging to the digeneans, nematodes and a cestode. The parasite composition is caused by the narrow depth range of the species and the restricted distribution of the fish family Halosauridae. The species richness was found to be lower than other demersal fish from the deep sea and shallow waters, however, higher than those from deep-sea fish living in the pelagial.

  15. Shewanella dovemarinesis sp. nov., a psychrotolerant bacterium isolated from Mid-Atlantic Ridge deep-sea sediments.

    PubMed

    Zhang, Jinwei; Burgess, James Grant

    2014-07-23

    Strains MAR441T and MAR445 were isolated from Mid-Atlantic Ridge (MAR) sediments with a depth of 2,734 m, and found to be member of the genus Shewanella. The strains were rod shaped, pigmented, non-motile, and capable of anaerobic growth either by fermentation of carbohydrates or by anaerobic respiration. The strains utilized a variety of electron acceptors, including nitrate and ferric compounds and could utilize peptone when grown anaerobically in a two-chambered microbial fuel cell (MFC), which use carbon cloth electrodes and deliver a stable power output of ~150-200 mW/m2. The major fatty acids were typical of the genus Shewanella, with major components of C13:0, iso-C13:0, iso-C15:0, C16:0, C16:1ω7c, C18:1ω7c and C20:5ω3 fatty acids. The DNA G+C content of strains MAR441T and MAR445 were 42.4 mol %. 16S rRNA gene sequence analysis indicated that strains MAR441T and MAR445 were most closely related to Shewanella olleyana (sequence similarities 97.9 %). DNA-DNA hybridization demonstrated only 15.6-37.2 % relatedness between strain MAR441T and the type strains of related Shewanella species. Phenotypic characteristics confirmed that these isolates constituted a novel species of the genus Shewanella. The type strain of Shewanella dovemarinensis is MAR441T (=ATCC BAA-2408 T =DSM24955 T).

  16. Shewanella electrodiphila sp. nov., a psychrotolerant bacterium isolated from Mid-Atlantic Ridge deep-sea sediments.

    PubMed

    Zhang, Jinwei; Burgess, J Grant

    2015-09-01

    Strains MAR441(T) and MAR445 were isolated from Mid-Atlantic Ridge sediments from a depth of 2734 m, and were found to belong to the genus Shewanella. The strains were rod-shaped, pigmented, non-motile and capable of anaerobic growth either by fermentation of carbohydrates or by anaerobic respiration. The strains utilized a variety of electron acceptors, including nitrate and ferric compounds, and could utilize peptone when grown anaerobically in a two-chambered microbial fuel cell, which used carbon cloth electrodes and delivered a stable power output of ,150-200 mW m(-2). The major fatty acids were typical of the genus Shewanella, with major components C13 : 0, iso-C13 : 0, iso-C15 : 0, C16 : 0, C16 : 1ω7c, C18 : 1ω7c and C20 : 5ω3 fatty acids. The DNA G+C content of strains MAR441(T) and MAR445 was 42.4 mol%. 16S rRNA gene sequence analysis indicated that strains MAR441(T) and MAR445 were most closely related to Shewanella olleyana (sequence similarities 97.9% to the type strain). DNA-DNA hybridization demonstrated only 15.6-37.2% relatedness between strain MAR441(T) and the type strains of related species of the genus Shewanella. Phenotypic characteristics confirmed that these isolates constituted a novel species of the genus Shewanella, for which the name Shewanella electrodiphila sp. nov. is proposed; the type strain is MAR441(T) (5ATCC BAA-2408(T) = DSM 24955(T)).

  17. Seasonal Abundance and Phenology of Halyomorpha halys (Hemiptera: Pentatomidae) on Different Pepper Cultivars in the Mid-Atlantic (United States).

    PubMed

    Philips, C R; Kuhar, T P; Dively, G P; Hamilton, G; Whalen, J; Kamminga, K

    2017-02-01

    The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive stink bug (Hemiptera: Pentatomidae) introduced into the United States in the mid-1990s. Since its initial establishment, it has spread throughout the east coast as far south as Georgia, and as far north as New Hampshire. While information is available regarding H. halys behavior and life history in some crops, relatively little information is available for vegetables such as peppers. Key questions include understanding when H. halys enters pepper fields to feed and how best to predict infestations, what population levels create economic damage, and if peppers that vary in capsaicin levels also vary in susceptibility to attack. To answer these questions, replicated plots were set up across four mid-Atlantic states using three types of peppers: sweet bell, sweet banana, and hot chili. We found that there was no difference in the overall abundance of all life stages of H. halys on all pepper varieties tested. However, there were differences in bug density by site, but these differences did not translate to differences in the proportion of damaged fruit. The presence of adult H. halys is a better predictor of damage in banana peppers, whereas nymphs are a better predictor in bell pepper. In addition, across all sites, the presence of egg masses was low in pepper crops and densities of both adults and immatures tend to peak on pepper plants in early August. Altogether, this information can be used to help develop a pest management program in peppers that will reduce crop losses to this new devastating pest, while reducing the reliance on insecticides to manage this pest at the same time.

  18. Estimating population abundance and mapping distribution of wintering sea ducks in coastal waters of the mid-Atlantic

    USGS Publications Warehouse

    Koneff, M.D.; Royle, J. Andrew; Forsell, D.J.; Wortham, J.S.; Boomer, G.S.; Perry, M.C.

    2005-01-01

    Survey design for wintering scoters (Melanitta sp.) and other sea ducks that occur in offshore waters is challenging because these species have large ranges, are subject to distributional shifts among years and within a season, and can occur in aggregations. Interest in winter sea duck population abundance surveys has grown in recent years. This interest stems from concern over the population status of some sea ducks, limitations of extant breeding waterfowl survey programs in North America and logistical challenges and costs of conducting surveys in northern breeding regions, high winter area philopatry in some species and potential conservation implications, and increasing concern over offshore development and other threats to sea duck wintering habitats. The efficiency and practicality of statistically-rigorous monitoring strategies for mobile, aggregated wintering sea duck populations have not been sufficiently investigated. This study evaluated a 2-phase adaptive stratified strip transect sampling plan to estimate wintering population size of scoters, long-tailed ducks (Clangua hyemalis), and other sea ducks and provide information on distribution. The sampling plan results in an optimal allocation of a fixed sampling effort among offshore strata in the U.S. mid-Atlantic coast region. Phase I transect selection probabilities were based on historic distribution and abundance data, while Phase 2 selection probabilities were based on observations made during Phase 1 flights. Distance sampling methods were used to estimate detection rates. Environmental variables thought to affect detection rates were recorded during the survey and post-stratification and covariate modeling were investigated to reduce the effect of heterogeneity on detection estimation. We assessed cost-precision tradeoffs under a number of fixed-cost sampling scenarios using Monte Carlo simulation. We discuss advantages and limitations of this sampling design for estimating wintering sea duck

  19. Mid- Atlantic Gas Hydrate, Heat Flow, and Basin Analysis: Implications to Hydrocarbon Production in the Carolina Trough

    NASA Astrophysics Data System (ADS)

    Phrampus, B. J.

    2015-12-01

    The new Mid- and South Atlantic Planning Areas for oil and gas leasing is proposed to open in 2021. This region lacks in contemporary geologic and geophysical petroleum data and has no conventional wells drilled within the proposed leasing area. As such, addressing the hydrocarbon potential of this region is particularly difficult. Here, we use new and legacy multi-channel seismic data with heat flow observations, ocean temperature measurements, and new seismic interpretations of gas hydrate deposits to determine basin-wide heat flow along the Mid- Atlantic. These data reveal a conductive heat flow regime along the continental margin with a lack of fluid flow that is consistent with sea floor spreading rates and cooling oceanic crust. We then use these observations in combination with basal heat flow models and sedimentation records to determine the thermal history of a cross section of the Carolina Trough. These models reveal varying depth of potential hydrocarbon production that begin at ~ 2000 mbsf and extend down to depths greater than 7000 mbsf across the Carolina Trough. These potentially productive depths correspond to varying stratal ages, but all models contain the Late Jurassic, which is a potential analog to the U.S. Gulf Coast's Smackover Formation. Additionally, the timing of hydrocarbon generation reveal that Early through Middle Jurassic evaporite deposits and Late Jurassic tight limestones should have been in place before the Early Jurassic source rocks reached a depth of burial sufficiently deep for the production of hydrocarbons. These potential seals may trap significant quantities of hydrocarbons with in the Jurassic layers, resulting in significant hydrocarbon potential within the Carolina Trough.

  20. The Production of Methane, Hydrogen, and Organic Compounds in Ultramafic-Hosted Hydrothermal Vents of the Mid-Atlantic Ridge

    PubMed Central

    Charlou, J.L.; Holm, N.G.; Mousis, O.

    2015-01-01

    Abstract Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge. Considering the vast number of these fields discovered or inferred, hydrothermal fluxes represent a significant input of H2 and CH4 to the ocean. Although there are lines of evidence of their abiogenic formation from stable C and H isotope results, laboratory experiments, and thermodynamic data, neither their origin nor the reaction pathways generating these gases have been fully constrained yet. Organic compounds detected in the fluids may also be derived from abiotic reactions. Although thermodynamics are favorable and extensive experimental work has been done on Fischer-Tropsch-type reactions, for instance, nothing is clear yet about their origin and formation mechanism from actual data. Since chemolithotrophic microbial communities commonly colonize hydrothermal vents, biogenic and thermogenic processes are likely to contribute to the production of H2, CH4, and other organic compounds. There seems to be a consensus toward a mixed origin (both sources and processes) that is consistent with the ambiguous nature of the isotopic data. But the question that remains is, to what proportions? More systematic experiments as well as integrated geochemical approaches are needed to disentangle hydrothermal geochemistry. This understanding is of prime importance considering the implications of hydrothermal H2, CH4, and organic compounds for the ocean global budget, global cycles, and the origin of life. Key Words: Hydrogen—Methane—Organics—MAR—Abiotic synthesis—Serpentinization—Ultramafic-hosted hydrothermal vents. Astrobiology 15, 381–399. PMID:25984920

  1. Distribution and feeding ecology of dolphins along the Mid-Atlantic Ridge between Iceland and the Azores

    NASA Astrophysics Data System (ADS)

    Doksæter, L.; Olsen, E.; Nøttestad, L.; Fernö, A.

    2008-01-01

    During Leg 1 of the MAR-ECO expedition on the R.V. G.O. Sars in June 2004 four main species of dolphins were observed along the Mid-Atlantic Ridge from Iceland to the Azores: pilot whale ( Globicephala melas) ( n=326), short-beaked common dolphin ( Delphinus delphis) ( n=273), white-sided dolphin ( Lagenorhynchus acutus) ( n=103), and striped dolphin ( Stenella coeruleoalba) ( n=86). Pilot whales and white-sided dolphins were found in cold (5-16 °C) and less-saline (34.6-35.8‰) water masses in the northern part of the study area, whereas common and striped dolphins inhabited warmer (12-22 °C) and more-saline (34.8-36.7‰) waters in the south. Dolphins tended to aggregate in areas of steep slopes, but actual bottom depth appeared to be less important. Based on spatial correlations between dolphin occurrence and candidate prey organisms recorded acoustically and by midwater trawling, mesopelagic fishes and squids were assumed to be important prey items, with Benthosema glaciale probably being the most important prey for pilot whales and white-sided dolphins, while Lampanyctus macdonaldi, Stomias boa ferox and Chauliodus sloani were probably of particular importance for common dolphins. Cephalopods, especially Gonatus sp. and Teuthowenia megalops were the most likely prey species of pilot whales and striped dolphins, respectively. The difference in physical habitat north and south of the Sub-polar Frontal Zone seemed to have important effects on prey distribution, in turn influencing dolphin distribution.

  2. Serpentinization of abyssal peridotites from the MARK area, Mid-Atlantic Ridge: Sulfur geochemistry and reaction modeling

    USGS Publications Warehouse

    Alt, J.C.; Shanks, Wayne C.

    2003-01-01

    The opaque mineralogy and the contents and isotope compositions of sulfur in serpentinized peridotites from the MARK (Mid-Atlantic Ridge, Kane Fracture Zone) area were examined to understand the conditions of serpentinization and evaluate this process as a sink for seawater sulfur. The serpentinites contain a sulfur-rich secondary mineral assemblage and have high sulfur contents (up to 1 wt.%) and elevated ??34Ssulfide (3.7 to 12.7???). Geochemical reaction modeling indicates that seawater-peridotite interaction at 300 to 400??C alone cannot account for both the high sulfur contents and high ??34Ssulfide. These require a multistage reaction with leaching of sulfide from subjacent gabbro during higher temperature (???400??C) reactions with seawater and subsequent deposition of sulfide during serpentinization of peridotite at ???300??C. Serpentinization produces highly reducing conditions and significant amounts of H2 and results in the partial reduction of seawater carbonate to methane. The latter is documented by formation of carbonate veins enriched in 13C (up to 4.5???) at temperatures above 250??C. Although different processes produce variable sulfur isotope effects in other oceanic serpentinites, sulfur is consistently added to abyssal peridotites during serpentinization. Data for serpentinites drilled and dredged from oceanic crust and from ophiolites indicate that oceanic peridotites are a sink for up to 0.4 to 6.0 ?? 1012 g seawater S yr-1. This is comparable to sulfur exchange that occurs in hydrothermal systems in mafic oceanic crust at midocean ridges and on ridge flanks and amounts to 2 to 30% of the riverine sulfate source and sedimentary sulfide sink in the oceans. The high concentrations and modified isotope compositions of sulfur in serpentinites could be important for mantle metasomatism during subduction of crust generated at slow spreading rates. ?? 2003 Elsevier Science Ltd.

  3. Bacterial diversity in hydrothermal sediment and epsilonproteobacterial dominance in experimental microcolonizers at the Mid-Atlantic Ridge.

    PubMed

    López-García, Purificación; Duperron, Sébastien; Philippot, Pascal; Foriel, Julien; Susini, Jean; Moreira, David

    2003-10-01

    We report here a molecular survey based on 16S rRNA genes of the bacterial diversity found in two deep-sea vent niches at the Mid-Atlantic Ridge: hydrothermal sediment (Rainbow site), and microcolonizers made of three different substrates (organic-rich, iron-rich and pumice) that were exposed for 15 days to a vent emission. Bacterial diversity in sediment samples was scattered through many bacterial divisions. The most abundant and diverse environmental sequences (phylotypes) in our libraries corresponded to the Gammaproteobacteria, followed by the Acidobacteria. We detected members of all the subdivisions within the Proteobacteria. Myxobacterial lineages were the most represented within the delta subdivision. Phylotypes ascribing to the Cytophaga-Flavobacterium-Bacteroides, Planctomycetales, high and low G + C Gram-positives, Nitrospirae, and the candidate division TM7 were also identified. Compared to this broad taxonomic coverage, microcolonizers were almost exclusively colonized by epsilonproteobacteria, although these exhibited considerable morphological and phylogenetic in-group diversity. No specificity for any of the substrates tested was seen. This observation further supports the idea of the ecological dominance of epsilonproteobacteria in the fluid-seawater interface environment. Because oxidation of reduced S species and/or sulphur-reduction is thought to be essential for their energetic metabolism in these areas, we mapped different oxidation states of S in individual bacterial filaments from the iron-rich microcolonizer. For this, we used high-resolution, non-destructive synchrotron micro-X-ray Absorption Near-Edge Spectroscopy (micro-XANES), which revealed the co-existence of different S oxidation states, from sulphide to sulphate, at the level of individual cells. This suggests that these cells were metabolizing sulphur in situ.

  4. Evaluation of two algorithms for a network of coastal HF radars in the Mid-Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Kohut, Josh; Roarty, Hugh; Randall-Goodwin, Evan; Glenn, Scott; Lichtenwalner, C. Sage

    2012-06-01

    The National High Frequency (HF) Surface Current Mapping Radar Network is being developed as a backbone system within the U.S. Integrated Ocean Observing System. This paper focuses on the application of HF radar-derived surface current maps to U.S. Coast Guard Search and Rescue operations along the Mid-Atlantic coast of the USA. In that context, we evaluated two algorithms used to combine maps of radial currents into a single map of total vector currents. In situ data provided by seven drifter deployments and four bottom-mounted current meters were used to (1) evaluate the well-established unweighted least squares (UWLS) and the more recently adapted optimal interpolation (OI) algorithms and (2) quantify the sensitivity of the OI algorithm to varying decorrelation scales and error thresholds. Results with both algorithms were shown to depend on the location within the HF radar data footprint. The comparisons near the center of the HF radar coverage showed no significant difference between the two algorithms. The most significant distinction between the two was seen in the drifter trajectories. With these simulations, the weighting of radial velocities by distance in the OI implementation was very effective at reducing both the distance between the actual drifter and the cluster of simulated particles as well as the scale of the search area that encompasses them. In this study, the OI further reduced the already improved UWLS-based search areas by an additional factor of 2. The results also indicated that the OI output was relatively insensitive to the varying decorrelation scales and error thresholds tested.

  5. Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

    USGS Publications Warehouse

    Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

    2013-01-01

    Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

  6. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Striped Bass

    SciTech Connect

    Fay, C.W.; Neves, R.J.; Pardue, G.B.

    1983-10-01

    Species profiles are literature summaries on the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. The striped bass (Morone saxatilis) is a highly valued recreational and commercial fish species and is surpassed in total recreational catch (weight) only by bluefish and Atlantic mackerel on the Atlantic coast. Males mature at age 2 or 3, and females at age 4 or 5. Striped bass are anadromous, spawning in fresh or nearly fresh water, from April through June in the Mid-Atlantic region. Upper Chesapeake Bay, its major tributaries, and the Chesapeake-Delaware Canal are the most important spawning grounds on the Atlantic coast. Eggs are semibuoyant, and require a minimum current velocity of 30.5 cm/s during development to keep them from settling and smothering on the bottom. Environmental conditions during the larval stage are considered most crucial in terms of future year class strength. Juveniles remain in or near areas of origin for 2 or 3 years, at which time a portion of the juveniles may join coastal migratory stocks, moving north in spring and summer and south in fall and winter. Temperature, salinity, current velocity, and turbidity are important environmental factors for striped bass. Eggs require water temperatures between 14/sup 0/C and 23/sup 0/C, salinities between 0 and 10 ppt, water currents of at least 30.5 cm/s, and turbidities less than 1000 mg/l for successful development and hatching. Larvae require temperatures between 10/sup 0/C and 25/sup 0/C, salinities between 0 and 15 ppt, and turbidities less than 500 mg/1 for survival. Juvenile and adult tolerances are generally wider. 171 references, 4 figures, 9 tables.

  7. Analysis of a PAH-degrading bacterial population in subsurface sediments on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Shao, Zongze; Cui, Zhisong; Dong, Chunming; Lai, Qiliang; Chen, Liang

    2010-05-01

    Little is known about the types and concentrations of polycyclic aromatic hydrocarbons (PAHs) existing in the deep-sea subsurface environment, which is believed to be cold, oligothrophic and of high static pressure. PAHs in the upper layers of the water column are unavoidably subjected to degradation while they are deposited to the sea floor and become embedded in the deep-sea sediment. In this report, a high concentration of PAHs was discovered in the sediment 2.7 m beneath the bottom surface at a water depth of 3962 m on the Mid-Atlantic Ridge (MAR). The total concentration of PAHs was 445 ng (g dry wt sediment) -1. Among the seven detected PAHs, the concentrations of phenanthrene (222 ng g -1) and fluorene (79 ng g -1) were relatively high. In addition, PAH-degrading bacteria were found within the sediments. As in a previously detected site on the MAR, in the PAH-enriched region of this site, a bacterium of the genus Cycloclasticus was found to be the predominant isolate detected by PCR-DGGE analysis. In addition, bacteria of the Halomonas, Marinobacter, Alcanivorax, Thalassospira and Maricaulis genera, were also included in the PAH-degrading community. In summary, a high concentration of PAHs was detected in the subsurface of the deep-sea sediment, and once again, the Cycloclasticus bacterium was confirmed to be a ubiquitous marine PAH degrader even in the subsurface marine environment. Considering the abundance of PAHs therein, biodegradation is thus thought to be inactive, probably because of the low temperature, limited oxygen and/or limited nutrients.

  8. Vertical datum conversion process for the inland and coastal gage network located in the New England, Mid-Atlantic, and South Atlantic-Gulf hydrologic regions

    USGS Publications Warehouse

    Rydlund, Jr., Paul H.; Noll, Michael L.

    2017-03-07

    Datum conversions from the National Geodetic Vertical Datum of 1929 to the North American Vertical Datum of 1988 among inland and coastal gages throughout the hydrologic regions of New England, the Mid-Atlantic, and the South Atlantic-Gulf have implications among river and storm surge forecasting, general commerce, and water-control operations. The process of data conversions may involve the application of a recovered National Geodetic Vertical Datum of 1929–North American Vertical Datum of 1988 offset, a simplistic datum transformation using VDatum or VERTCON software, or a survey, depending on a gaging network datum evaluation, anticipated uncertainties for data use among the cooperative water community, and methods used to derive the conversion. Datum transformations from National Geodetic Vertical Datum of 1929 to North American Vertical Datum of 1988 using VERTCON purport errors of ± 0.13 foot at the 95 percent confidence level among modeled points, claiming more consistency along the east coast. Survey methods involving differential and trigonometric leveling, along with observations using Global Navigation Satellite System technology, afford a variety of approaches to establish or perpetuate a datum during a survey. Uncertainties among leveling approaches are generally < 0.1 foot, and and Global Navigation Satellite System approaches may be categorized with uncertainties of ≤0.1 foot for a Level I quality category and ≥0.1 foot for Level II or III quality categories (defined by the U.S. Geological Survey) by observation and review of experienced practice. The conversion process is initiated with an evaluation of the inland and coastal gage network datum, beginning with altitude datum components and the history of those components queried through the U.S. Geological Survey Groundwater Site Inventory database. Subsequent edits to the Groundwater Site Inventory database may be required and a consensus reached among the U.S. Geological Survey Water

  9. Mid-Atlantic

    Atmospheric Science Data Center

    2014-05-15

    ... as a function of view angle are visible over both land and water. Scientists are using MISR data to monitor changes in clouds, Earth's surface, and pollution particles in the air, and to assess their impact on climate. MISR ...

  10. New Pressure Results from the Expedition 336 CORKs at North Pond, Western Flank of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Becker, K.; Villinger, H. W.; Davis, E. E.

    2014-12-01

    We report results from a nearly two-year record of pressure data from three CORK hydrogeological observatories in the ~8x15 km "North Pond" sedimented basin in ~7 Ma crust west of the mid-Atlantic Ridge at 23°N. The new data were recovered during operations with the ROV Jason from the German R/V Maria S. Merian in April of 2014. Two of the CORKs (in Holes U1382A and U1383C) had been installed during IODP Expedition 336 in fall of 2011, with an initial installment of 6-7 months data recovered in spring 2012, also by Jason from R/V Merian. The third hole, U1383B, was instrumented during the 2012 cruise with a "CORK-Lite" deployed by the ROV. All three installations monitor formation pressures in basement beneath the sediment pond. The new data confirm results of the first half-year of data, which suggested a slight formation overpressure (~10 kPa) relative to hydrostatic in the two full CORK installations. This was somewhat surprising given (a) the long history of downhole flow in DSDP Hole 395A that also penetrated basement beneath the sediment pond, and (b) prior observations at more thickly-sedimented eastern Pacific ridge flanks of formation underpressures in sites drilled into basement lows. The new results show a small phase lag and attenuation of formation tidal signals relative to seafloor tides that is the same in all three holes, which confirms that the CORKs are properly sealed at the seafloor. The phase lag and attenuation are also the same among three separate basement intervals in Hole U1383C, which suggests either that the entire drilled section is hydrogeologically well connected or that downhole packers between the intervals do not seal completely. We explore potential models to explain the slight observed overpressures. One possibility is that the geometry of the isolated sediment pond results in higher formation temperatures and less dense formation fluids immediately below the relatively impermeable sediment pond, such that surrounding cooler

  11. Lithospheric Structure, Stress, and Magmatism at the Rainbow Non-Transform Offset on the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Paulatto, M.; Canales, J. P.; Dunn, R. A.

    2014-12-01

    New oceanic lithosphere is formed at slow-spreading mid-ocean ridges by a combination of eruption and intrusion of magma and by tectonic exhumation and alteration of lower crustal and mantle rocks. We look at the relationship between these two processes and how their relative contributions vary at non-transform ridge-segment offsets (NTOs). Models of mantle upwelling predict magmatic input and heat flux to be relatively low at NTOs, yet many host high-temperature hydrothermal systems, which are difficult to explain without the presence of a crustal magmatic source. We analyzed newly acquired swath bathymetry, gravity and magnetic data from the MARINER experiment together with archived data from the Rainbow NTO (36º10' N) on the Mid-Atlantic Ridge. This NTO is currently experiencing both mantle exhumation and magmatic input as evidenced by the active Rainbow high-temperature hydrothermal field. We calculate mantle Bouguer gravity anomalies and crustal magnetization to constrain the lithospheric structure and tectonic evolution of the NTO during the past ~2 Myr. The swath bathymetry data are used to map faults, extrusive volcanic terrain and tectonized blocks and show that the style of crustal accretion varies along the adjacent ridge segments. Spatial changes in the style of extensional faulting are indicative of variations in the mechanical properties and the state of stress of the lithosphere. We suggest that the availability of magma to drive hydrothermal activity at Rainbow and other similar settings is controlled not only by the thermal regime and the structure of the lithosphere but also by the effect of local stress conditions on magma migration. Models of magma migration and dyking show that changes in the direction of minimum compressive stress affect the propagation of magmatic intrusions. We argue that stress rotation can explain the formation of crustal magma chambers at NTOs despite a reduced magmatic flux. These constraints help determine the role of

  12. Spreading Rate versus Magma Supply in the Region of Mid-Atlantic Ridge at 16.5° N

    NASA Astrophysics Data System (ADS)

    Palmiotto, C.; Schouten, H.; Smith, D. K.; Cann, J. R.; Dick, H. J.; Parnell-Turner, R. E.

    2013-12-01

    The region of Mid-Atlantic Ridge (MAR) at 16.5° N is a slow spreading center characterized by several detachment faults and oceanic core complexes. This area is ideal to study the relationship between the formation and the evolution of detachment faults, the role of magma supply during detachment faulting, and its effect on the magnetization of the crust at a slow-spreading center. In May-June 2013, during cruise KN210-05 on RV Knorr, we acquired multibeam bathymetry and sea surface magnetic anomaly data to understand the spreading history of a section of the MAR near 16.5° N. Multibeam data acquired using a SeaBeam 3012 system show that the ridge axis can be divided into a northern segment, characterized by a 4500-m deep axial valley, and a southern segment, which is characterized by a robust and continuous axial volcanic ridge which reaches to 3200 m water depth. Both segments are bordered to the west by active detachment faults. Magnetic data were acquired with a Marine Magnetics SeaSPY system, and inverted for crustal magnetization. The inversion assumes a constant thickness source layer of 0.5 km whose upper bound is bathymetry. Isochrons were identified from the magnetization map. We found that spreading rate is symmetric, and have calculated a total spreading rate in this area of ~24 km/Ma for the last 4 Ma. The central anomaly (Brunhes, 0-0.78 Ma) in the southern segment, however, has only half the predicted width of ~ 20 km and is located exclusively east of the axis. No Brunhes normal magnetization is recorded in the rift valley floor west of the axis, which is the hanging wall of the detachment. This observation confirms predictions from ';asymmetric' spreading at oceanic core complexes where slip along long-lived detachment faults take up extension on one (western) side and magmatic accretion occurs exclusively to the other (eastern) of the axis; the hanging wall, bounded by detachment fault and axis, should be as old as the core complex and its

  13. Lipid Biomarkers and Carbon Isotopic Composition from Authigenic Carbonates and Seep Sediments from the US Mid-Atlantic Margin

    NASA Astrophysics Data System (ADS)

    Campbell, P.; Prouty, N.; Demopoulos, A. W.; Roark, B.; Coykendall, K.

    2015-12-01

    Anaerobic oxidation of methane (AOM), mediated by Archaea and sulfate-reducing bacteria, is common in continental margin sediment and can result in authigenic carbonate precipitation. A lipid biomarker study was undertaken in Mid-Atlantic submarine canyons, focusing specifically on Baltimore and Norfolk canyons, to determine biomarker variability of carbonate rock and the associated sediment in cold seep communities dominated by chemosynthetic mussels, Bathymodiolus childressi. Preliminary 16S metagenomic results confirm the presence of free-living sulfur-reducing bacteria and methantrophic endosymbiotic bacteria in the mussels. Depleted d13C values in both the mussel tissue (-63 ‰) and authigenic carbonates (-48 ‰) support methanotrophy as the dominant nutritional pathway and AOM as the main driver of carbonate precipitation. In addition, paired 14C and 230Th dates are highly discordant, reflecting dilution of the 14C pool with fossil hydrocarbon derived carbon. Seep and canyon sediment, as well as authigenic carbonates, were collected and analyzed for a suite of biomarkers, including sterols, alcohols, alkanes and fatty acids, as well as δ13C values of select biomarkers, to elucidate pathways of organic matter cycling. A comparison of terrestrial biomarker signatures (e.g., n-alkane carbon preference index and C23 / (C23 + C29) values, HMW n-alkanes and C29 sterols) suggests that terrestrial inputs dominate the submarine canyon surface sediment, whereas seep sediment is predominantly marine autochthonous (i.e., cholesterol and 5α-cholestanol). Lipid biomarker profiles (e.g., n-alkanes in the C15 to C33 range) from authigenic carbonates mirror those found in the seep sediment, suggesting that the organisms mediating carbonate precipitation on the seafloor are characteristic of the assemblages present in the sediment at these sites. With widespread methane leakage recently discovered along the Atlantic Margin, the presence of AOM-mediated carbonate

  14. Observation of the Lithosphere and upper mantle structure from Greenland to the Mid Atlantic ridge using PP-precursors

    NASA Astrophysics Data System (ADS)

    Alvarado, D. R.; Gurrola, H.

    2012-12-01

    Observations based on PP and SS bounce point precursors have long been used to image the 410 and 660 km discontinuities. Because of noise (largely caused by scattering near the seismic stations) these data are generally low pass filtered and only offer resolution of the major transition zone discontinuities. Array processing, made possible by the EarthScope transportable array, have enabled us to improve the frequency content to 2Hz (depending on the richness of data in the area to be imaged). This study will focus on using PP-precursors to image lithospheric and upper-mantle discontinuities beneath the northern mid-Atlantic ridge (MAR) and the southern continental shelf of Greenland. Seismic images produced from the PP-precursor data were processed at frequencies ranging from 0.25 Hz to 2 Hz using different beam radii (BR) of 60, 150, and 250 km. The images using 0.25 Hz with a BR of 250 km were the least noisy but smeared features over a large region. The 2 Hz images with 60 km radii showed more localized features but must be used together with the low resolution images to separate noise from signal. The lithosphere-asthenosphere boundary (LAB) beneath the Southern continental shelf of Greenland was imaged at a depth of ~70 km. The LAB appears to shallow to a depth of ~50 km near the MAR. A low velocity body (a warm body, possibly partial melt) from the ridge was also imaged near the ridge at ~70 km depth beneath the LAB. The length of the low velocity body extended ~300 km west of the ridge before disappearing. Another low velocity body was observed at depths varying between 180 and 200 km, which may indicate the presence of a shallow 220 km discontinuity. Global tomography show low velocities from the surface to transition zone depths beneath the northern Atlantic (near Iceland). The resolution of our data at the 410 km depth is questionable, but this discontinuity appears to be 410 km beneath Greenland and deepens to ~430 km toward the MAR.

  15. Ecomorphodynamic feedbacks and barrier island response to disturbance: Insights from the Virginia Barrier Islands, Mid-Atlantic Bight, USA

    NASA Astrophysics Data System (ADS)

    Wolner, Catherine W. V.; Moore, Laura J.; Young, Donald R.; Brantley, Steven T.; Bissett, Spencer N.; McBride, Randolph A.

    2013-10-01

    Ecomorphodynamic feedbacks play an important role in the susceptibility and response of barrier islands to disturbance by overwash. Dune-building grasses, like Ammophila breviligulata, can help to restore areas of high relief after overwash events (i.e., resist disturbance). If overwash recurs before dunes have reestablished, however, overwash-adapted "maintainer" species, like Spartina patens (upright variety), may preferentially survive. Maintainer species help to preserve low, flat topography, thereby increasing the likelihood of future overwash (i.e., reinforcing disturbance). Under frequent disturbance conditions, this positive feedback may lead to overwash persistence. We explore the potential influence of the maintainer feedback on two morphologically distinct barrier islands in the Virginia Coast Reserve (VCR), located in the Mid-Atlantic Bight of the U.S. East Coast. Combined topographic and vegetation surveys show that on Hog Island (high-relief, rotating), where dunes dominated by A. breviligulata are ubiquitous, overwash zones are currently limited in extent and related to beach width rather than dominance by S. patens. Historical aerial photos and stratigraphic evidence (ground-penetrating radar, cores) indicate that gradual recovery has taken place following overwash events on Hog Island, except where the beach is narrow and eroding. Conversely, on Metompkin Island (low-relief, transgressing), overwash is widespread and dominated by S. patens, particularly along the rapidly migrating northern half of the island, where shell armoring is also common. Overwash has generally been more prevalent and persistent here than on Hog Island. We present a new conceptual model of the response of barrier islands to disturbance incorporating ecological and physical processes. Our findings suggest that in barrier systems where both dune-building grasses and overwash-adapted maintainer species are common (like the VCR), the maintainer feedback is likely to be a more

  16. In Search for Diffuse Hydrothermal Venting at North Pond, Western Flank of the Mid-Atlantic-Ridge

    NASA Astrophysics Data System (ADS)

    Villinger, H. W.; Becker, K.; Hulme, S.; Kaul, N. E.; Müller, P.; Wheat, C. G.

    2015-12-01

    We present results from temperature measurements made with a ROV temperature lance in sediments deposited on the slopes of abyssal hills and small basins surrounding North Pond. North Pond is a ~8x15 km large sediment basin located on ~7 Ma year old crust west of the Mid-Atlantic Ridge at 23°N. Data were collected with the ROV Jason II during cruise MSM37 on the German RV Maria S. Merian in April 2014. The temperature lance consists of a 60 cm long stainless steel tube (o.d. 12 mm) housing 8 thermistors with a spacing of 80 mm, resulting in an active length of 56 cm. Data are logged with an 8-channel data logger (XR-420-T8, RBR, Ottawa) and transmitted online to the control van of the ROV. Data reduction and temperature gradient calculation is done according to the HFRED algorithm (Villinger & Davis, 1987). 90 sites in total were visited, 88 gave good data for temperature gradient calculation. Calculated gradients are usually of good to very good quality. The gradients vary between less than 20 to more than 1000 mK/m reflecting the very heterogeneous distribution of geothermal heat flow. The expected conductive lithospheric heat flow for North Pond is ~190 mW/m2 (geothermal gradient of ~190 mK/m with a thermal conductivity of 1 W/Km). The highest temperature gradients are measured in places where temperature ~50 cm below the sediment-water boundary exceeds bottom water temperature by ~0.5 K . These high temperature gradients may reflect local hydrothermal circulation within the pillow lavas, however no focused discharge was detected. The analysis of temperature measurements made with the ROV-mounted CTD shows clearly detectable bottom water temperature anomalies. We infer that they are either caused by hydrothermal discharge through the thin sediment cover or through unsedimented pillow basalts nearby. Hydrothermal circulation in a North-Pond-like environment appears to be diffuse in nature, hence very difficult if not impossible to detect and to quantify.

  17. Along-axis variability in crustal accretion at the Mid-Atlantic Ridge: Results from the OCEAN study

    USGS Publications Warehouse

    Henstock, T.J.; White, Robert S.; McBride, J.H.

    1996-01-01

    The OCEAN experiment is an integrated geophysical study of a region of the Cape Verde abyssal plain that formed at 140 Ma. Deep seismic reflection and ocean bottom hydrophone (OBH) refraction data were acquired along lines parallel and perpendicular to the paleoridge axis trend identified from a detailed magnetic anomaly survey. The igneous basement is overlain by about 1.3 km of sediment which enables improved imaging of intracrustal structure beyond that possible near the Mid-Atlantic Ridge axis. We describe the results of a 150-km long profile oriented parallel to magnetic anomalies M15 and M16, along which deep seismic reflection data collected by the British Institutions Reflection Profiling Syndicate are complemented by refraction data constrained by four OBHs. The line spans an entire spreading segment between two fracture zones; the northern of which has an offset of 40 km and the other (central) has an offset of only 10 km. Away from the fracture zones, the mean igneous crustal thickness is 7.2 km; near both fracture zones, thinning of up to 4 km is observed, giving a mean igneous crustal thickness over the whole segment of approximately 6.5 km. Differences are seen between the two fracture zones in their seismic velocity structure, in the associated basement topography, and in the presence of a strong reflection extending into the mantle beneath the northern fracture zone. The boundary between oceanic layers 2 and 3 correlates with variably coherent normal incidence reflections and a change in the character of the reflectivity. A number of planar reflections up to 10 km in length are present within the middle and lower crust, dipping outward from beneath low-amplitude basement highs at ??? 15??; these appear to be present only within layer 3. The Moho has several expressions in the reflection data, including isolated reflection events, a local increase in reflected amplitudes, and a downward decrease in coherent reflections. At the center of the segment

  18. A geological perspective on sea-level rise and its impacts along the U.S. mid-Atlantic coast

    NASA Astrophysics Data System (ADS)

    Miller, Kenneth G.; Kopp, Robert E.; Horton, Benjamin P.; Browning, James V.; Kemp, Andrew C.

    2013-12-01

    We evaluate paleo-, historical, and future sea-level rise along the U.S. mid-Atlantic coast. The rate of relative sea-level rise in New Jersey decreased from 3.5 ± 1.0 mm/yr at 7.5-6.5 ka, to 2.2 ± 0.8 mm/yr at 5.5-4.5 ka to a minimum of 0.9 ± 0.4 mm/yr at 3.3-2.3 ka. Relative sea level rose at a rate of 1.6 ± 0.1 mm/yr from 2.2 to 1.2 ka (750 Common Era [CE]) and 1.4 ± 0.1 mm/yr from 800 to 1800 CE. Geological and tide-gauge data show that sea-level rise was more rapid throughout the region since the Industrial Revolution (19th century = 2.7 ± 0.4 mm/yr; 20th century = 3.8 ± 0.2 mm/yr). There is a 95% probability that the 20th century rate of sea-level rise was faster than it was in any century in the last 4.3 kyr. These records reflect global rise (˜1.7 ± 0.2 mm/yr since 1880 CE) and subsidence from glacio-isostatic adjustment (˜1.3 ± 0.4 mm/yr) at bedrock locations (e.g., New York City). At coastal plain locations, the rate of rise is 0.3-1.3 mm/yr higher due to groundwater withdrawal and compaction. We construct 21st century relative sea-level rise scenarios including global, regional, and local processes. We project a 22 cm rise at bedrock locations by 2030 (central scenario; low- and high-end scenarios range of 16-38 cm), 40 cm by 2050 (range 28-65 cm), and 96 cm by 2100 (range 66-168 cm), with coastal plain locations having higher rises (3, 5-6, and 10-12 cm higher, respectively). By 2050 CE in the central scenario, a storm with a 10 year recurrence interval will exceed all historic storms at Atlantic City.

  19. Volcanic and Tectonic Setting of Hydrothermal Activity on the Southern Mid-Atlantic Ridge, 4° - 11°S

    NASA Astrophysics Data System (ADS)

    Melchert, B.; Devey, C. W.; German, C. R.; Haase, K. M.; Koschinsky, A.; Lackschewitz, K.; Yoerger, D. R.

    2006-12-01

    The recurrence rate of volcanism at mid-ocean ridges should drop with spreading rate. Although the southern Mid-Atlantic Ridge, with a spreading full rate of ~3.6 cm/yr, might therefore be expected to show only sporadic magmatic activity, we present information on recently-discovered volcanically, tectonically and hydrothermally active areas south of the equator (at 4°48'S and 9°33'S, see also German et al. 2005; Haase et al. 2005 EOS Trans. AGU 86 (52) Fall Meet. Suppl. Abstr. OS21C-04 & -05). Around the 4°48'S area the median valley floor forms a ~10 km wide, hour-glass shaped, plateau with water depths of around 3000 m. Four closely-spaced vent fields (the high-temperature sites Turtle Pits, Red Lion and Comfortless Cove and the diffuse low-temperature Wideawake site) occur along a flat (total relief 50 m), volcanically and tectonically active 2 km section of this plateau (see German et al. 2005, Haase et al. 2005 op. cit. also Koschinsky et al. this meeting). The Turtle Pits site lies within a small depression associated with a fracture marked by aligned collapse pits. This central depression is surrounded by laminated sheet flows to the north and northwest, whereas jumbled flows are more prevalent to the east. Comfortless Cove is also associated with young volcanics and shows strong tectonic influence on vent location. Red Lion in contrast shows no clear tectonic control - it is characterised by four active chimneys which sit directly on a pillow lava floor. The 9°33'S area is situated on 11 km-thick crust (Bruguier et al. 2003 JGR 108 2093) at 1490 m water depth and is marked by fresh pillow lavas, sheet flows, lava lakes and collapse structures. Low- temperature, diffuse hydrothermal activity is abundant in the area (Haase et al. 2005; Koschinsky et al. 2006 op. cit.) as are larger extinct hydrothermal mounds suggesting more vigourous hydrothermalism in the past. All sites are located east of a large NNW trending escarpment flanking horst and graben

  20. Hydroacoustic seismicity along oceanic transform faults: Contrasts between the East Pacific Rise and Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Zheng, T.; Lin, J.; Zhong, Q.

    2015-12-01

    We investigate the characteristics of seismicity of oceanic transform faults through analyzing hydroacoustic data recorded along the fast-spreading East Pacific Rise (EPR) and slow-spreading Mid-Atlantic Ridge (MAR), respectively. The investigated region on the EPR is within 15°S-15°N from the Garrett to Clipperton Transform Fault during time period of June 1996 to September 2002. Meanwhile, the investigated region on the MAR is within 15°-37°N from the Fifteen-Twenty to Oceanographer Transform Fault during time period of February 1999 to August 2003. Using space-time correlation analysis, we matched hydroacoustic events with earthquakes from the Global Centroid Moment Tensor (GCMT) solutions for event magnitude greater than 4.8. Our analyses revealed systematic differences in the seismicity characteristics between the EPR and MAR: (1) Along the EPR, more than ninety percent of seismicity occurred within several kilometers from transform faults, a few percent occurred near over-lapping spreading centers, while the rest occurred along the ridge axis. Along the MAR, hydroacoustic seismicity is much more scattered near the ridge axis, transform faults, and non-transform offsets. (2) Near the EPR transform faults, the standard deviation of the separation distance of the hydroacoustic events from the morphologically-determined transform fault axis is s = 5.7 km. In contrast, the separation distance of hydroacoustic events to the transform faults is greater (s = 11.9 km), reflecting possibly more complex acoustic scattering due to complex MAR topography as well as more complex tectonic activity. (3) The mean hydroacoustic magnitude of the investigated EPR events is 3.3 (s = 0.6), while the mean hydroacoustic magnitude of the studied MAR events is 3.0 (s = 0.7). The mean hydroacoustic seismicity rate is 2.1 events per year per km of the EPR transform fault length, comparing to the mean seismicity rate of 0.5 events per year per km of the MAR transform fault length. (4

  1. Biodiversity patterns, environmental drivers and indicator species on a high-temperature hydrothermal edifice, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Sarrazin, Jozée; Legendre, Pierre; de Busserolles, Fanny; Fabri, Marie-Claire; Guilini, Katja; Ivanenko, Viatcheslav N.; Morineaux, Marie; Vanreusel, Ann; Sarradin, Pierre-Marie

    2015-11-01

    Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe), sulfide (TdS), copper (TdCu) and pH) on the distribution of macro- and meiofaunal species at small spatial scales (<1 m). There were differences in macro- and meiofaunal community structure between the different sampling locations, separating the hydrothermal community of the Eiffel Tower edifice into three types of microhabitats: (1) cold microhabitats characterized by low temperatures (<6 °C), high TdCu (up to 2.4±1.37 μmol l-1), high pH (up to 7.34±0.13) but low TdS concentrations (<6.98±5.01 μmol l-1); (2) warm microhabitats characterized by warmer temperatures (>6 °C), low pH (<6.5) and high TdS/TdFe concentrations (>12.8 μmol l-1/>1.1 μmol l-1 respectively); and (3) the third microhabitat characterized by intermediate abiotic conditions. Environmental conditions showed more variation in the warm microhabitats than in the cold microhabitats. In terms of fauna, the warm microhabitats had lower macro- and meiofaunal densities, and lower richness and Shannon diversity than the cold microhabitats. Six macrofaunal species (Branchipolynoe seepensis, Amathys lutzi, Bathymodiolus azoricus, Lepetodrilus fucensis, Protolira valvatoides and Chorocaris chacei) and three meiofaunal taxa (Paracanthonchus, Cephalochaetosoma and Microlaimus) were identified as being significant indicator species/taxa of particular microhabitats. Our results also highlight very specific niche separation for copepod juveniles among the different hydrothermal microhabitats. Some sampling units

  2. Seismic Structure of Volcanic Edifice and Lava Lake at the Lucky Strike Volcano, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Arnulf, A. F.; Singh, S. C.; Harding, A. J.; Kent, G.; Crawford, W. C.

    2010-12-01

    The top of the oceanic crust is formed by a heterogeneous process of magmatic eruptions and tectonic deformation at ocean spreading centres, creating 200-1000 m thick extrusive layer, sometimes called as layer 2A, thickness of which depends on spreading rate. The base of this layer is defined by a high velocity gradient zone where velocity increases from 2.5 km/s to 4.5 km/s. Although, wide-angle reflection image from this gradient zone and/or a velocity contour of 4.5 km/s provides idea of thickness Layer 2A, it has been difficult to obtain seismic images of this region with resolutions comparable to the length scales of the geologic processes. Drilling could be used to overcome the resolution gap but on its own would be prohibitively expensive. Using a combination of a synthetic ocean bottom experiment (SOBE) and three-dimensional tomographic technique, here we show the high resolution 3D velocity structure of the Lucky Strike volcano at Mid-Atlantic Ridge. We find that the upper oceanic crust is laterally heterogeneous on 2-3 km scales, with unusually low velocity (< 2.2 km/s) underneath the Lucky Strike volcanic edifices down to 300 m below the seafloor and normal velocity in layer 2A underneath the lava lake. Such a low velocity could be due to high porosity (> 25 %), suggestive of recently erupted, higly fractured pillow lavas. The location of the hydrothermal vent fields seems to lie at the boundary of high-porosity volcanic edifices and low porosity lava lake. A new reflector distinct from the usually imaged layer 2A-2B transition zone and consistent with a constructional origin is also observed at the base of the volcanic edifices. The strong lateral and vertical heterogeneities and the presence of secondary layer above classical Layer 2A might explain the controvery about the origin of seismic Layer 2A, i.e. volcanic versus alteration front. The new technique provides an image of the oceanic crust comparable to that of seafloor geology, leading to new

  3. Vertical distribution and relative abundance of gelatinous zooplankton, in situ observations near the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Youngbluth, M.; Sørnes, T.; Hosia, A.; Stemmann, L.

    2008-01-01

    Fourteen dives were conducted with the ROVs Aglantha and Bathysaurus to depths of 2335 m along the Mid-Atlantic Ridge (42∘52'- 53∘17'N). The most frequently observed gelatinous fauna in order of overall abundance included medusae, ctenophores, siphonophores, appendicularians, and tunicates. All of these animals, except the tunicates, occurred throughout the water column. Their relative abundances differed with depth and location. Identification to species was limited to easily recognized fauna because relatively few gelatinous animals were collected. Each group of gelatinous zooplankton tended to be most numerous in a region just south of the Charlie-Gibbs Fracture Zone. Medusae (mainly Aeginura grimaldii) were the most frequently encountered animals (up to 25 individuals per 100m3). On a vertical scale their abundance peaked from 550 to 800 m and these maxima were consistently within the SAIW and NACWe. In the NACW their densities were notably lower (up 2 individuals per 100m3) and the majority of the population was deeper, ranging from 800 to 1050 m. Ctenophores (mainly Bathocyroe fosteri) were most prominent (as many as 27 individuals per 100m3) in a zone from 300 to 600 m in the NACWe. Appendicularians (primarily oikopleurids) had a broader vertical distribution in all water masses, mainly from 450 to 1000 m. Up to 12 houses per 100m3 were noted in the NACWe, and these estimates are considered to be very conservative. Sorties near the sea floor (as deep as 2100 m) indicated these detritivores were a prominent component (up to 5 houses per 100m3) of the epibenthic macrozooplankton. Siphonophores (mostly calycophorans) reached densities of about 14 colonies per 100m3 in the NACWe and occurred mainly from 300 to 600 m, at most locations. Tunicates (salps and doliolids) were patchy in their distribution and infrequently observed. Salps were numerous (up to 3 solitary individuals per 100m3) at only one location (sta. 50) near the surface. Deep-living doliolids

  4. Predicting the Timing of Cherry Blossoms in Washington, DC and Mid-Atlantic States in Response to Climate Change

    PubMed Central

    Chung, Uran; Mack, Liz; Yun, Jin I.; Kim, Soo-Hyung

    2011-01-01

    Cherry blossoms, an icon of spring, are celebrated in many cultures of the temperate region. For its sensitivity to winter and early spring temperatures, the timing of cherry blossoms is an ideal indicator of the impacts of climate change on tree phenology. Here, we applied a process-based phenology model for temperate deciduous trees to predict peak bloom dates (PBD) of flowering cherry trees (Prunus×yedoensis ‘Yoshino’ and Prunus serrulata ‘Kwanzan’) in the Tidal Basin, Washington, DC and the surrounding Mid-Atlantic States in response to climate change. We parameterized the model with observed PBD data from 1991 to 2010. The calibrated model was tested against independent datasets of the past PBD data from 1951 to 1970 in the Tidal Basin and more recent PBD data from other locations (e.g., Seattle, WA). The model performance against these independent data was satisfactory (Yoshino: r2 = 0.57, RMSE = 6.6 days, bias = 0.9 days and Kwanzan: r2 = 0.76, RMSE = 5.5 days, bias = −2.0 days). We then applied the model to forecast future PBD for the region using downscaled climate projections based on IPCC's A1B and A2 emissions scenarios. Our results indicate that PBD at the Tidal Basin are likely to be accelerated by an average of five days by 2050 s and 10 days by 2080 s for these cultivars under a mid-range (A1B) emissions scenario projected by ECHAM5 general circulation model. The acceleration is likely to be much greater (13 days for 2050 s and 29 days for 2080s ) under a higher (A2) emissions scenario projected by CGCM2 general circulation model. Our results demonstrate the potential impacts of climate change on the timing of cherry blossoms and illustrate the utility of a simple process-based phenology model for developing adaptation strategies to climate change in horticulture, conservation planning, restoration and other related disciplines. PMID:22087317

  5. The physical oceanographic conditions along the Mid-Atlantic Ridge north of the Azores in June July 2004

    NASA Astrophysics Data System (ADS)

    Søiland, H.; Budgell, W. P.; Knutsen, Ø.

    2008-01-01

    During the MAR-ECO expedition in June and July 2004, 39 deep CTD stations were occupied with uneven spacing along the Mid-Atlantic Ridge (MAR) between 41°N and 61°N. The CTD stations coincided with the biological sampling stations and thus gave a detailed vertical description of the water properties at these locations. Many different water masses were identified. However, using the predominant water mass in the upper 500 m, four different hydrographic regions were identified. Stations in the vicinity of the Reykjanes Ridge north of 57°N were dominated by Modified North Atlantic Water (MNAW). Stations south of 56°30'N and north of the Sub-Polar Front (SPF) were dominated by Sub-Arctic Intermediate Water (SAIW). CTD data combined with along-track continuous surface temperature and salinity measurements, satellite sea-level anomaly data and sea-surface temperature (SST) and along-track current data (ADCP data) showed that the position of the SPF was at about 52°N, at the southern edge of the Charlie-Gibbs Fracture Zone (CGFZ). South of the SPF a Frontal Region with both North Atlantic Central Water (NACW) and SAIW present was observed, and south of about 50°N the predominant water mass in the upper 500 m was NACW. A ship-mounted RDI 75 kHz ADCP was operated during the cruise and yielded high quality data during the first leg. The currents showed large variations over short distances and were strongly affected by topography. The ADCP data was be used to describe the mesoscale eddy field along the MAR and to detect three jets in the North Atlantic Current (NAC). Data from a current meter mooring left for 10 months after the cruise at a seamount just to the south of CGFZ showed the dominance of the tidal currents in the area. Typical spring tidal currents were about 0.15 m s -1 and the mean flow an order of magnitude smaller, about 0.03 m s -1. A short-term mooring on a seamount farther south showed tidal currents of 0.3 m s -1. Binned 8-day, 4-km SST satellite

  6. Off-axis Submarine Massive Sulfide accumulation at the fault-controlled Logatchev 1 hydrothermal field, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Andersen, Christine; Theissen-Krah, Sonja; Hannington, Mark

    2016-04-01

    The largest Submarine Massive Sulfide (SMS) deposits in Mid-ocean ridge settings are found along slow-spreading ridges, where tectonic processes dominate and long-lived faults control the circulation of hydrothermal fluids through the oceanic crust. Here we combine results from 2D fluid flow simulations of the off-axis (8km), fault-controlled, high-T Logatchev 1 hydrothermal field (LHF1) at the Mid-Atlantic Ridge with data on vent fluid chemistry and the associated SMS deposit, which give insights about its accumulation history. Modeled high vent temperatures of 360°C, as measured at the active LHF1, result in a total integrated mass-flow rate through the seafloor of ~36 kg/sec scaled to 28 vent orifices of 10x10cm, located in the 7 known high-T sites at the LHF1. About 42% of the vent fluids are hotter than 350°C, the minimum temperature required for efficient metal transport, with a mass-flow rate of 13 kg/sec. This corresponds to ~400 kilotons of potentially SMS-forming hydrothermal fluids leaving the vent field per year. Combined with a total H2S-SiO2-metal (Zn+Cu+Fe) concentration of 732 ppm, measured in the LHF1 vent fluids, this makes a flux of ~300 t of hydrothermal precipitates per year. The SMS deposit at LHF1 has been dated to 58.200 years and has an estimated tonnage of 135 kilotons. Applying the above modeled annual discharge rate over the dated time period, results in an SMS accumulation efficiency of ~0.8% for the SMS deposit at the Logatchev 1 field, which fits the range of estimated global average for MORs between <0.3% and 3%. Our predicted depositional efficiency is based on numerical modeling, which simulates continuous and ideal venting. Realistically, venting at LHF1 might well have been fluctuating, including periods of low temperature discharge, where metal transport is insufficient or periods of inactivity, compensated by periods with a higher depositional efficiency than 0.8%. Such fluctuations could have been caused by variations in

  7. Observations of oceanic crust and mantle structures at a deep ocean seismic array in the Eastern Mid Atlantic

    NASA Astrophysics Data System (ADS)

    Hannemann, Katrin; Krüger, Frank; Dahm, Torsten

    2016-04-01

    In 2011, twelve ocean bottom stations (OBS) were installed approximately 100 km North of the Gloria Fault during the DOCTAR project (Deep OCean Test ARray). This fault marks the plate boundary between the Eurasian and African plate in the North Eastern Mid Atlantic. The experiment took place in water depth of 4-6 km, 800 km West of the Portuguese coast. The stations were equipped with broad band seismometers which recorded for ten months. We employ P and S receiver functions (RF) to have a closer look at the structure of crust and mantle. The ocean is a quite noisy environment, therefore the number of usable events is low (around 20) compared to RF studies on land. We use several quality criteria (e.g. signal to noise ratio, relative spike position) to select proper processing parameters for the calculation of the RF and carefully reviewed all later on used RF. Despite the low number of events, the usage of an array of OBS with an aperture of 75 km allows us to investigate deeper discontinuities (e.g. in 410 and 660 km depth) compared to single station approaches which are usually employed for OBS. Furthermore, we increase the number of usable events by applying array methods. We use move out corrected and stacked RF to have a closer look at the mantle transition zone, and estimate average depth values for the Moho, the lithosphere asthenosphere boundary (LAB) and the base of the asthenosphere. The Moho lies at depth of 7 km, the LAB at approximately 50 km and the asthenosphere has an approximated thickness of 110 km. We observe a slight increase in the time difference of the mantle discontinuity conversion times compared to PREM. RF give just information regarding the impedance contrast at a discontinuity instead of velocities. We additionally use P wave polarization of teleseismic events to estimate absolute S velocities beneath the single stations. All in all, we use the information gained by the RF analysis, and the analysis of the P wave polarization to

  8. Legacy effects of colonial millponds on floodplain sedimentation, bank erosion, and channel morphology, MID-Atlantic, USA

    USGS Publications Warehouse

    Schenk, E.R.; Hupp, C.R.

    2009-01-01

    Many rivers and streams of the Mid-Atlantic Region, United States (U.S.) have been altered by postcolonial floodplain sedimentation (legacy sediment) associated with numerous milldams. Little Conestoga Creek, Pennsylvania, a tributary to the Susquehanna River and the Chesapeake Bay, is one of these streams. Floodplain sedimentation rates, bank erosion rates, and channel morphology were measured annually during 2004-2007 at five sites along a 28-km length of Little Conestoga Creek with nine colonial era milldams (one dam was still in place in 2007). This study was part of a larger cooperative effort to quantify floodplain sedimentation, bank erosion, and channel morphology in a high sediment yielding region of the Chesapeake Bay watershed. Data from the five sites were used to estimate the annual volume and mass of sediment stored on the floodplain and eroded from the banks for 14 segments along the 28-km length of creek. A bank and floodplain reach based sediment budget (sediment budget) was constructed for the 28 km by summing the net volume of sediment deposited and eroded from each segment. Mean floodplain sedimentation rates for Little Conestoga Creek were variable, with erosion at one upstream site (-5 mm/year) to deposition at the other four sites (highest = 11 mm/year) despite over a meter of floodplain aggradation from postcolonial sedimentation. Mean bank erosion rates range between 29 and 163 mm/year among the five sites. Bank height increased 1 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p < 0.0001) resulting in progressively lowered hydraulic connectivity between the channel and the floodplain. Floodplain sedimentation and bank erosion rates also appear to be affected by the proximity of the segments to one existing milldam, which promotes deposition upstream and scouring downstream. The floodplain and bank along the 28-km reach produced a net mean sediment loss of 5,634 Mg/year for 2004-2007, indicating that bank

  9. Effects of non-native earthworms on on below- and aboveground processes in the Mid-Atlantic region

    NASA Astrophysics Data System (ADS)

    Szlavecz, K. A.; McCormick, M. K.; Xia, L.; Pitz, S.; O'Neill, J.; Bernard, M.; Chang, C.; Whigham, D. F.

    2011-12-01

    Many biotic and abiotic disturbances have shaped the structure of the deciduous forests in the Mid-Atlantic region. One major anthropogenic factor is land use history. Agricultural practices in the past undoubtedly facilitated non-native earthworm colonization and establishment. Today most secondary forests are dominated by European lumbricid earthworms, although native species also occur in some habitats. To investigate how earthworm community composition and abundance affect belowground processes and tree seedling growth we set up a field manipulation experiment at the Smithsonian Environmental Research Center in Edgewater, MD. A total of 66 experimental plots were set up in successional (70 yrs) and mature (150 yrs) Tulip-poplar-Oak associations. We manipulated earthworm abundance and leaf litter input, and planted seedlings of Tulip poplar, Red maple, Red oak, and American beech. The experiment lasted for two years during which we regularly monitored density, biomass and species composition of earthworm assemblages and measured soil respiration. Soil moisture, temperature and air temperature were also continuously monitored using a wireless sensor network. At harvest, soil bulk density, pH, N pools, C:N ratio, potential N-mineralization rates, and enzyme activity were determined. We used quantitative PCR to assess the community composition of soil fungi. We also determined the extent of mycorrhizal colonization and biomass of roots, shoots and leaves. We conducted likelihood ratio tests for random and fixed effects based on mixed model analyses of variance. Differences between soil depths and among sites and plots accounted for a large portion of the variation in many soil properties. Litter quality affected soil pH and N mineralization. Earthworm densities affected bulk density, inorganic N content, and N mineralization. Both mycorrhizal groups were more abundant in mature than in successional forests. Both ectomycorrhizal (ECM) and arbuscular (AM) fungi were

  10. High paleointensities of the geomagnetic field from thermomagnetic studies on Rift Valley pillow basalts from the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    PréVot, Michel; Mankinen, Edward A.; Grommé, Sherman; Lecaille, Alain

    1983-03-01

    Nineteen pillow basalts dredged within the rift valley of the Mid-Atlantic Ridge at36.8°N were studied by the Thellier stepwise heating method in order to determine the paleointensity of the geomagnetic field when they erupted on to the sea floor. Previously reported fission track ages are 2,000 to 6,000 years for the youngest rocks (mainly olivine basalts) and 10,000 to 100,000 years for the others (mainly plagioclase basalts and pyroxene basalts). All but three pillow basalts meet the conditions commonly considered as indicative of quite reliable paleointensity estimates: stability of the direction of NRM during its thermal demagnetization, constant ratio of NRM/TRM (natural remanent magnetization to thermoremanent magnetization) over 50% or more of the original NRM intensity (80 to 94% for 11 specimens), and reproducibility of low-temperature partial TRM (PTRM). However, strong field thermomagnetic measurements indicate that 11 of these 16 samples display a significant increase in Curie temperature (15 to 80°C) during the paleointensity experiments below 250°C, notwithstanding the linearity of the NRM-TRM plot in this temperature interval. This alteration, probably due to low-temperature oxidation of the specimens, seems typical of young pillow basalts and may result in paleointensity estimates which are too high. This result shows that excellence of remanence tests (NRM-TRM linearity and PTRM stability) does not ensure the absence of chemical changes during the Thellier experiments and therefore the validity of the paleointensity obtained. The assumption that reliable paleointensities are obtained when the Curie point increase is 10°C or less led to the selection of five of our specimens, all from the youngest group. Their mean paleointensity is 64.2±20.5 μT (standard deviation) and the corresponding virtual axial dipole moment (VADM) is 11.5±3.7× 1022 A m2. Given the variations of the VADM of the Earth's magnetic field over the last 6,000 years, as

  11. METHOD-SPECIFIC PRECISION AND BIAS RELATIONSHIPS DEVELOPED FROM DATA SUBMITTED DURING USEPA WASTEWATER LABORATORY PERFORMANCE EVALUATION STUDIES

    EPA Science Inventory

    This paper documents the process used by the United States Environmental Protection Agency (USEPA) to estimate the mean and standard deviation of data reported by in-control wastewater laboratories during Water Pollution (WP) studies. This process is then applied to the data rep...

  12. METHOD-SPECIFIC PRECISION AND BIAS RELATIONSHIPS DEVELOPED FROM DATA SUBMITTED DURING USEPA DRINKING WATER LABORATORY PERFORMANCE EVALUATION STUDIES

    EPA Science Inventory

    This paper documents the process used by the United States Environmental Protection Agency (USEPA) to estimate the mean and standard deviation of data reported by in-control drinking water laboratories during Water Supply (WS) studies. This process is then applied to the data re...

  13. Patterns in the Initial Teaching Assignments of Secondary English Teachers: Implications for Teacher Agency and Retention

    ERIC Educational Resources Information Center

    Bieler, Deborah; Holmes, Stephen; Wolfe, Edward W.

    2017-01-01

    This study examined the teaching assignments of English teachers in 13 Mid-Atlantic high schools across five states. Data on the experience levels of 175 English teachers teaching 246 classes and surveys from 85 teacher participants were collected. Findings reveal that major agency-thwarting challenges face new English teachers: They typically are…

  14. Structure of deep-sea pelagic fish assemblages in relation to the Mid-Atlantic Ridge (45° 50°N)

    NASA Astrophysics Data System (ADS)

    Fock, Heino O.; Pusch, Christian; Ehrich, Siegfried

    2004-07-01

    Pelagic fishes from depths of 250 to 3200 m from 45°N to 50°N were sampled during a mid-Atlantic cruise in 1982. These clustered into 6 assemblages, which were related to the Mid-Atlantic Ridge, the continental shelf edge and oceanic habitats. Spatial distribution of clusters coincided with SST and surface chlorophyll patterns. Cluster distribution further coincided with published mid-depth hydrography indicating that hydrographic recirculation features were an important determinant of community structure. Over the ridge, Melamphaidae, Serrivomeridae, Stomiidae and Centrolophidae increased in abundance. Horizontally, the myctophid Benthosema glaciale indicated the transition from temperate-subtropical to temperate-subarctic waters. The gadid Micromesistius poutassou and the alepocephalid Xenodermichthys copei were characteristic species for the shallow shelf edge assemblage. Vertically, extended depth ranges were stated for assemblages above MAR and the southern leg, as indicated for the species Gonostoma bathyphilum, and Schedophilus medusophagus. This was further tested for the saccopharyngid Saccopharynx ampullaceus. The increase of gelatinous plankton feeders over the ridge, in particular for S. medusophagus, is discussed with respect to a probable increase of gelatinous plankton abundance in the area considered. An error model was developed to address the contamination problem with respect to non-closing devices.

  15. Decadal Declines of Mercury in Adult Bluefish (1972-2011) from the Mid-Atlantic Coast of the U.S.A.

    PubMed

    Cross, Ford A; Evans, David W; Barber, Richard T

    2015-08-04

    Concentrations of total mercury were measured in muscle of adult bluefish (Pomatomus saltatrix) collected in 2011 off North Carolina and compared with similar measurements made in 1972. Concentrations of mercury decreased by 43% in the fish between the two time periods, with an average rate of decline of about 10% per decade. This reduction is similar to estimated reductions of mercury observed in atmospheric deposition, riverine input, seawater, freshwater lakes, and freshwater fish across northern North America. Eight other studies between 1973 and 2007 confirm the decrease in mercury levels in bluefish captured in the Mid-Atlantic Bight. These findings imply that (1) reductions in the release of mercury across northern North America were reflected rather quickly (decades) in the decline of mercury in adult bluefish; (2) marine predatory fish may have been contaminated by anthropogenic sources of mercury for over 100 years; and (3) if bluefish are surrogates for other predators in the Mid-Atlantic Bight, then a reduction in the intake of mercury by the fish-consuming public has occurred. Finally, with global emissions of mercury continuing to increase, especially from Asia, it is important that long-term monitoring programs be conducted for mercury in marine fish of economic importance.

  16. Dynamic Management of NOx and SO2 Emissions in the Texas and Mid-Atlantic Electric Power Systems and Implications for Air Quality.

    PubMed

    McDonald-Buller, Elena; Kimura, Yosuke; Craig, Michael; McGaughey, Gary; Allen, David; Webster, Mort

    2016-02-02

    Cap and trade programs have historically been designed to achieve annual or seasonal reductions in emissions of nitrogen oxides and sulfur dioxide from power plants. Emissions reductions may not be temporally coincident with meteorological conditions conducive to the formation of peak ozone and fine particulate matter concentrations. Integrated power system and air quality modeling methods were developed to evaluate time-differentiated emissions price signals on high ozone days in the Mid-Atlantic portion of the Pennsylvania-New Jersey-Maryland (PJM) Interconnection and Electric Reliability Council of Texas (ERCOT) grids. Sufficient flexibility exists in the two grids with marked differences in demand and fuel generation mix to accommodate time-differentiated emissions pricing alone or in combination with a season-wide program. System-wide emissions reductions and production costs from time-differentiated pricing are shown to be competitive with those of a season-wide program on high ozone days and would be more cost-effective if the primary policy goal was to target emissions reductions on these days. Time-differentiated pricing layered as a complement to the Cross-State Air Pollution Rule had particularly pronounced benefits for the Mid-Atlantic PJM system that relies heavily on coal-fired generation. Time-differentiated pricing aimed at reducing ozone concentrations had particulate matter reduction co-benefits, but if particulate matter reductions are the primary objective, other approaches to time-differentiated pricing may lead to greater benefits.

  17. Organic storage of CO 2 on the continental slope off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast

    NASA Astrophysics Data System (ADS)

    Walsh, John J.; Premuzic, Eugene T.; Gaffney, Jeffrey S.; Rowe, Gilbert T.; Harbottle, Garman; Stoenner, Raymond W.; Balsam, William L.; Betzer, Peter R.; Macko, Steven A.

    1985-07-01

    A comparison is made of organic content, sedimentation rates derived from 14C and 210Pb analyses, 13C and 15N isotope ratios, amorphous silica, particle size, and calcium carbonate within sediments from slopes off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast. These sediments are mainly marine, diatom-rich, and about one-third of the organic carbon is recent, reflecting a possible transient of shelf export in response to man's increased activities since the industrial revolution. Using a combination of sedimentation and mixing rates of carbon, the C:N ratio of sediments within the upper 50 cm, and the amount of nitrogen thought to be released from the coastal zone, independent estimates suggest a carbon loading to world slopes of ˜0.3 to 0.5 × 10 9 tons C y -1. The Bering slope exhibits no anthropogenic transients, however, while increased carbon loading may have occurred off Peru in response to overfishing and off the mid-Atlantic bight in response to eutrophication. The generality of our results depends on which of the three systems is most representative of world slopes.

  18. The consequences of landscape change on ecological resources: An assessment of the United States mid-Atlantic region, 1973-1993

    USGS Publications Warehouse

    Jones, K.B.; Neale, A.C.; Wade, T.G.; Wickham, J.D.; Cross, C.L.; Edmonds, C.M.; Loveland, T.R.; Nash, M.S.; Riitters, K.H.; Smith, E.R.

    2001-01-01

    Spatially explicit identification of changes in ecological conditions over large areas is key to targeting and prioritizing areas for environmental protection and restoration by managers at watershed, basin, and regional scales. A critical limitation to this point has been the development of methods to conduct such broad-scale assessments. Field-based methods have proven to be too costly and too inconsistent in their application to make estimates of ecological conditions over large areas. New spatial data derived from satellite imagery and other sources, the development of statistical models relating landscape composition and pattern to ecological endpoints, and geographic information systems (GIS) make it possible to evaluate ecological conditions at multiple scales over broad geographic regions. In this study, we demonstrate the application of spatially distributed models for bird habitat quality and nitrogen yield to streams to assess the consequences of landcover change across the mid-Atlantic region between the 1970s and 1990s. Moreover, we present a way to evaluate spatial concordance between models related to different environmental end-points. Results of this study should help environmental managers in the mid-Atlantic region target those areas in need of conservation and protection.

  19. An Atlantic hydrothermal plume: Trans-Atlantic geotraverse (TAG) area, Mid-Atlantic Ridge crest near 26°N

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.; Speer, Kevin G.

    1989-10-01

    The physical characteristics of an Atlantic hydrothermal plume and its seafloor sources are described from the first data set of water column properties associated with a high-temperature source area at a slow-spreading oceanic ridge. The observations comprise five near-bottom tows of a camera(color video and still)-temperature sensor array through the buoyant portion and 23 conductivity-temperature-depth (CTD) profiles through the neutrally buoyant portion of the plume made at the Trans-Atlantic Geotraverse Hydrothermal Field in the rift valley of the Mid-Atlantic Ridge at 26°08'N, 44°49'W in July 1985. The source area is a mound up to 250 m wide and 50 m high constructed primarily of massive sulfides between depths of 3620 and 3670 m at the base of the east wall. Flow and discharge regimes systematically changed from the center to the edge of the mound. High-temperature black smokers vented at fast rates (>1 m/s) from discrete sulfide chimneys and at slow rates from fractures, and clear solutions vented at slow rates from diffuse sources in the inner zone of the mound; intermediate-temperature blue-white and white smokers vented at slow rates from discrete sulfide/sulfate chimneys, and clear solutions vented from diffuse sources in the middle zone; patchy, diffuse discharge of clear solutions through sulfide talus occurred in the outer zone. The diffuse discharge of clear solutions and the discrete discharge from the white smokers were observed to turbulently rise up to several meters above the seafloor where the discharge was laterally advected in prevailing laminar flow at several centimeters per second. A convective heat flux of 8.8×106 W for only the black smokers that vented from fractures was estimated by applying a buoyant plume model to temperature anomalies measured with the towed array; this value is intermediate between values estimated for entire vent fields at the fast-spreading East Pacific Rise. Discharge from the black smokers rose to form the

  20. Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

    NASA Astrophysics Data System (ADS)

    Morris, A.; Pressling, N.; Gee, J. S.

    2011-12-01

    Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. One of the most extensively studied oceanic core complexes is Atlantis Massif, located at 30°N at the intersection of the Atlantis Transform Fault and the Mid Atlantic Ridge (MAR). The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305 (Hole U1309D). This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. Correlation of structures observed on oriented borehole (FMS) images and those recorded on unoriented core pieces allows reorientation of R1 remanences. The mean remanence direction in true geographic coordinates constrains the tectonic rotation experienced by the Atlantis Massif footwall, indicating a 46°±6° counterclockwise around a MAR-parallel horizontal axis trending 011°±6°. The detachment fault therefore initiated at a steep dip of >50° and then rotated flexurally to its present day low angle geometry (consistent with a 'rolling-hinge' model for detachment evolution). In a number of intervals, the gabbros exhibit a complex remanence structure with the presence of additional intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest

  1. Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

    NASA Astrophysics Data System (ADS)

    Morris, Antony; Pressling, Nicola; Gee, Jeffrey; John, Barbara; MacLeod, Christopher

    2010-05-01

    Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. For example, recent analyses suggest that detachment faults may underlie more than 50% of the Mid Atlantic Ridge (MAR) and may take up most of the overall plate divergence at times when magma supply to the ridge system is reduced. The most extensively studied oceanic core complex is Atlantis Massif, located at 30°N on the MAR. This forms an inside-corner bathymetric high at the intersection of the Atlantis Transform Fault and the MAR. The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305. This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. The core (Hole U1309D) reflects the interplay between magmatism and deformation prior to, during, and subsequent to a period of footwall displacement and denudation associated with slip on the detachment fault. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. In a number of intervals, however, the gabbros exhibit a complex remanence structure with the presence of intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest that they were acquired by a thermal mechanism. There appears to be no correlation between remanence structure and either the igneous

  2. Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

    NASA Astrophysics Data System (ADS)

    Morris, A.; Pressling, N.; Gee, J. S.

    2012-04-01

    Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. One of the most extensively studied oceanic core complexes is Atlantis Massif, located at 30°N at the intersection of the Atlantis Transform Fault and the Mid Atlantic Ridge (MAR). The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305 (Hole U1309D). This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. Correlation of structures observed on oriented borehole (FMS) images and those recorded on unoriented core pieces allows reorientation of R1 remanences. The mean remanence direction in true geographic coordinates constrains the tectonic rotation experienced by the Atlantis Massif footwall, indicating a 46°±6° counterclockwise around a MAR-parallel horizontal axis trending 011°±6°. The detachment fault therefore initiated at a steep dip of >50° and then rotated flexurally to its present day low angle geometry (consistent with a 'rolling-hinge' model for detachment evolution). In a number of intervals, the gabbros exhibit a complex remanence structure with the presence of additional intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest

  3. Patterns and contributions of floodplain and legacy sediments remobilized from Piedmont streams of the mid-Atlantic U.S.

    NASA Astrophysics Data System (ADS)

    Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen

    2015-04-01

    The perceived role of streambank erosion as a contributor to watershed sediment yield is an important driver of policy decisions for managing downstream impacts in the United States. In the Piedmont physiographic province of the eastern U.S. and in other regions of the south and midwest, the issue of 'legacy' sediment stored in stream valleys has long been recognized as a consequence of rapid deforestation and erosive agricultural practices following European settlement. Remobilization of stored floodplain sediment by bank erosion is frequently cited as a dominant component of watershed sediment budgets, with legacy sediment comprising the largest portion of this source. However there are few published studies documenting spatially extensive measurements of channel change throughout the drainage network on time scales of more than a few years. In this study we document 1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, 2) proportions of streambank sediment derived from legacy deposits, and 3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont. We measured gross erosion and channel deposition rates over 45 years within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 by comparing stream channel and floodplain morphology from LiDAR-based digital elevation data collected in 2005 with channel positions recorded on 1:2400-scale topographic maps from 1959-1961. Results were extrapolated to estimate contributions to watershed sediment yield from 1005 km2 of northern Baltimore County. Results indicate that legacy sediment is a dominant component (62%) of the sediment derived from bank erosion and that its relative importance is greater in larger valleys with broader valley floors and lower gradients. Although mass of sediment remobilized per unit channel length is greater in

  4. Investigation of extractable organic compounds in deep-sea hydrothermal vent fluids along the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    McCollom, Thomas M.; Seewald, Jeffrey S.; German, Christopher R.

    2015-05-01

    The possibility that deep-sea hydrothermal vents may contain organic compounds produced by abiotic synthesis or by microbial communities living deep beneath the surface has led to numerous studies of the organic composition of vent fluids. Most of these studies have focused on methane and other light hydrocarbons, while the possible occurrence of more complex organic compounds in the fluids has remained largely unstudied. To address this issue, the presence of higher molecular weight organic compounds in deep-sea hydrothermal fluids was assessed at three sites along the Mid-Atlantic Ridge that span a range of temperatures (51 to >360 °C), fluid compositions, and host-rock lithologies (mafic to ultramafic). Samples were obtained at several sites within the Lucky Strike, Rainbow, and Lost City hydrothermal fields. Three methods were employed to extract organic compounds for analysis, including liquid:liquid extraction, cold trapping on the walls of a coil of titanium tubing, and pumping fluids through cartridges filled with solid phase extraction (SPE) sorbents. The only samples to consistently yield high amounts of extractable organic compounds were the warm (51-91 °C), highly alkaline fluids from Lost City, which contained elevated concentrations of C8, C10, and C12n-alkanoic acids and, in some cases, trithiolane, hexadecanol, squalene, and cholesterol. Collectively, the C8-C12 acids can account for about 15% of the total dissolved organic carbon in the Lost City fluids. The even-carbon-number predominance of the alkanoic acids indicates a biological origin, but it is unclear whether these compounds are derived from microbial activity occurring within the hydrothermal chimney proximal to the site of fluid discharge or are transported from deeper within the system. Hydrothermal fluids from the Lucky Strike and Rainbow fields were characterized by an overall scarcity of extractable dissolved organic compounds. Trace amounts of aromatic hydrocarbons including

  5. UNITED STATES ENVIRONMENTAL PROTECTION AGENCY'S ENVIRONMENTAL INDICATORS INITIATIVE AND BIOMARKERS DATABASE

    EPA Science Inventory

    Within the United States Environmental Protection Agency (USEPA), there are several on-going programs and projects that collect health and environmental information. The USEPA's Environmental Indicators Initiative is one such program which includes the development of environmenta...

  6. USEPA RESEARCH ACTIVITIES TO CHARACTERIZE CHILDREN'S ENVIRONMENTAL EXPOSURES

    EPA Science Inventory

    Given the vulnerability of children to effects from environmental exposures, understanding links between children's health and environmental exposures is critical. In recent years, significant research has been initiated at USEPA to characterize children's exposures.

  7. Field observations and model simulations of low-level flows in the mid-Atlantic during August 1-5, 2006

    NASA Astrophysics Data System (ADS)

    Rabenhorst, Scott Daniel

    For years, basic mountain, sea breeze, and low-level jet (LLJ) circulations have been studied, usually in locations with a high frequency of occurrence, sharp gradients, or significant geographic prominence. However, there is evidence that similar circulations exist in non-classic locations with more mild topography and atmospheric gradients. One such understudied area is the U.S. Mid-Atlantic region. The Water Vapor Variability -- Satellite/Sondes (WAVES) 2006 field campaign provided a contiguous 5-day period of concentrated high resolution observations to examine fine-scale details of a weather pattern typical of the Mid-Atlantic summertime. These measurements presented an opportunity for an intensive modeling study to further investigate peculiar phenomena with verification against research-grade observations. The observations captured two significant events: an official LLJ and a cold front with a prefrontal trough. A pronounced diurnal cycle was revealed which can be categorized into three stages: (1) daytime growth of the planetary boundary layer (PBL), (2) flow intensification into a LLJ regime after dusk, and (3) interruption by downslope winds (DW) after midnight. The third stage is most interesting owing to the lack of literature documenting similar occurrences in the Mid-Atlantic, which can impact air quality forecasting. Prior to high resolution modeling of the case study, sensitivity studies were conducted examining four areas to which the model was believed most sensitive: (1) initial condition data, (2) cumulus schemes, (3) PBL parameterizations, and (4) initialization times. Results also revealed shortcomings in model precipitation and PBL profiles, model biases, urban anomalies, and tendencies for forecast convergence. High resolution regional modeling showed the evolution of these nocturnal events and were verified against WAVES observations. A hybrid solenoidal influenced afternoon and early evening circulation east of the mountains. Afternoon

  8. Small-scale distribution of deep-sea demersal nekton and other megafauna in the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Felley, J. D.; Vecchione, M.; Wilson, R. R., Jr.

    2008-01-01

    Videotapes from manned submersibles diving in the area of the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge were used to investigate the distribution of fishes, large crustaceans, epifaunal and sessile organisms, and environmental features along a series of transects. Submersibles MIR 1 and MIR 2 conducted paired dives in an area of mixed sediment and rock (beginning depth ca. 3000 m) and on a large pocket of abyssal-like sediments (depth ca. 4000 m). In the shallower area, the submersibles passed over extremely heterogeneous terrain with a diversity of nekton, epifaunal forms and sessile forms. In the first pair of dives, MIR 1 rose along the Mid-Atlantic Ridge from 3000 to 1700 m, while MIR 2 remained near the 3000 m isobath. Nekton seen in these relatively shallow dives included large and small macrourids (genus Coryphaenoides), shrimp (infraorder Penaeidea), Halosauropsis macrochir, Aldrovandia sp., Antimora rostrata, and alepocephalids. The last two were more characteristic of the upper areas of the slope reached by MIR 1, as it rose along the Mid-Atlantic Ridge to depths less than 3000 m. Distributions of some forms seemed associated with depth and/or the presence of hard substrate. Sessile organisms such as sponges and large cnidaria were more likely to be found in rocky areas. The second pair of dives occurred in an abyssal area and the submersibles passed over sediment-covered plains, with little relief and many fewer countable organisms and features. The most evident of these were holes, mounds, small cerianthid anemones, small macrourids and the holothurian Benthodytes sp. A few large macrourids and shrimp also were seen in these deeper dives, as well as squat lobsters ( Munidopsis sp.). Sponges and larger cnidaria were mostly associated with a few small areas of rocky substrate. Holes and mounds showed distributions suggesting large-scale patterning. Over all dives, most sessile and epifaunal forms showed clumped distributions. However, large

  9. Microbial iron mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to iron-oxidizing marine systems.

    PubMed

    Scott, Jarrod J; Breier, John A; Luther, George W; Emerson, David

    2015-01-01

    Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit) using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II) concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests that this organism

  10. Nitrogen fluxes in response to changing NOx emissions and deposition at EPA's Mid-Atlantic Long Term Monitoring (LTM) stream sites, 1990-2009

    NASA Astrophysics Data System (ADS)

    Funk, C.; Lynch, J. A.

    2012-12-01

    Surface water chemistry provides direct indicators of the potential effects of anthropogenic impacts, such as acid deposition and climate change, on the overall health of aquatic ecosystems. Long-term surface water monitoring networks provide a host of environmental data that can be used, in conjunction with other networks, to assess how water bodies respond to stressors and if they are potentially at risk (e.g., receiving pollutant deposition beyond its critical load). Two EPA-administered monitoring programs provide information on the effects of acidic deposition on headwater aquatic systems: the Temporally Integrated Monitoring of Ecosystems (TIME) program and Long Term Monitoring (LTM) program, designed to track the effectiveness of the 1990 Clean Air Act Amendments (CAAA) in reducing the acidity of surface waters in the Northeast and Mid-Atlantic. Here we compare trends in inorganic nitrogen emissions and deposition to streamwater nitrate (NO3-) concentration trends and NO3- export in headwater Mid-Atlantic streams. Annual NOx emissions from the fossil fuel based power sector, regulated under Title IV of the 1990 CAAA, decreased 67% from 6.7 million tones in 1990 to 2.0 million tones in 2009. Commensurate with decreased NOx emissions, there was a 31% reduction in total inorganic nitrogen deposition in the Mid-Atlantic region, from 8.7 kg N/ha to 6.0 kg N/yr. Over the same time period, surface water nitrate concentrations in headwater streams in the Northern Appalachian Plateau (n=9) and Central Appalachian mountains (n=66) improve (show a decreasing NO3- trend) at 30% and 50% of monitored sites, respectively. Despite these improvements, only 10% of monitored Appalachian streams show improvement in critical load status to no longer exceed the acid sensitivity threshold and experience adverse ecological effects. Information from long-term monitoring has shown that emission reductions have in improved environmental conditions and increased ecosystem protection

  11. Microbial Iron Mats at the Mid-Atlantic Ridge and Evidence that Zetaproteobacteria May Be Restricted to Iron-Oxidizing Marine Systems

    PubMed Central

    Scott, Jarrod J.; Breier, John A.; Luther, George W.; Emerson, David

    2015-01-01

    Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit) using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II) concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests that this organism

  12. Biodiversity and degradation potential of oil-degrading bacteria isolated from deep-sea sediments of South Mid-Atlantic Ridge.

    PubMed

    Gao, Xiangxing; Gao, Wei; Cui, Zhisong; Han, Bin; Yang, Peihua; Sun, Chengjun; Zheng, Li

    2015-08-15

    The indigenous oil-degrading bacterial consortia MARA and MARB were enriched from the deep-sea sediments of South Mid-Atlantic Ridge (MAR) with crude oil as sole carbon and energy sources. Biodiversity and community analyses showed that members of α-Proteobacteria were the key players in consortium MARA, whereas those of γ-Proteobacteria were the key players in consortium MARB, which were studied by MiSeq sequencing method. Gravimetric method estimated the oil degradation rates of MARA and MARB to be 63.4% and 85.8%, respectively, after 20d. Eleven cultivable oil degraders with different morphologies were isolated. These strains were identified as Alcanivorax, Bacillus, Dietzia, Erythrobacter, Marinobacter, Nitratireductor, and Oceanicola based on 16S rRNA gene sequences. Three strains belonging to Dietzia exhibited the highest oil degradation capability. Results indicated that the intrinsic biodegradation capacity of oil contaminants by indigenous microbial communities exists in South MAR sediments.

  13. A new species of Comephoronema (Nematoda: Cystidicolidae) from the stomach of the abyssal halosaur Halosauropsis macrochir (Teleostei) from the Mid-Atlantic Ridge.

    PubMed

    Moravec, Frantisek; Klimpel, Sven

    2007-08-01

    A new species of parasitic nematode Comephoronema macrochiri n. sp. (Cystidicolidae), is described from the stomach of the marine deep-sea fish Halosauropsis macrochir (abyssal halosaur) from the Mid-Atlantic Ridge (MAR). The new species, studied with both light and scanning electron microscopy, is characterized mainly by 6 pairs of preanal papillae, by which it principally differs from members of Ascarophis; the spicules are 297-375 microm and 99-120 microm long and fully developed eggs possess 2 long filaments on 1 pole. Rhabdochona beatriceinsleyae is transferred to Comephoronema as C. beatriceinsleyae (Holloway and Klewer, 1969) n. comb. Comephoronema macrochiri differs from all other congeners mainly in having eggs with filaments on 1 pole only, and from individual species by some additional features such as the number of preanal papillae, the shape of pseudolabial projections, and the body and organ measurements.

  14. Sea floor cycling of organic matter in the continental margin of the mid-Atlantic Bight. Final report, May 1, 1995--April 30, 1998

    SciTech Connect

    Jahnke, R.A.

    1998-12-31

    The objective of this project was to examine quantitatively the cycling of organic matter at the sea floor of the mid-Atlantic Bight continental margin. This information would be used to better understand sedimentary geochemical processes and, when used in conjunction with other measurements made within the DOE Ocean Margins Program, would be used to constrain the offshore and surface-to-deep water transport of organic carbon in this region. The latter information is critical in assessing the role of continental margins in the sequestration of anthropogenic carbon dioxide, the dominant greenhouse gas, in the deep ocean. Because the build-up of greenhouse gases in the atmosphere may cause significant changes in climate, this project had major societal importance.

  15. The national assessment of shoreline change: A GIS compilation of vector shorelines and associated shoreline change data for the New England and Mid-Atlantic Coasts

    USGS Publications Warehouse

    Himmelstoss, Emily A.; Kratzmann, Meredith G.; Hapke, Cheryl; Thieler, E. Robert; List, Jeffrey

    2010-01-01

    Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the fact that coastal infrastructure is subjected to flooding and erosion. As a result, there is an increased demand for accurate information regarding past and present shoreline changes. The U.S. Geological Survey's National Assessment of Shoreline Change Project has compiled a comprehensive database of digital vector shorelines and shoreline-change rates for the New England and Mid-Atlantic Coasts. There is currently no widely accepted standard for analyzing shoreline change. Existing measurement and rate-calculation methods vary from study to study and preclude combining results into statewide or regional assessments. The impetus behind the National Assessment project was to develop a standardized method that is consistent from coast to coast for measuring changes in shoreline position. The goal was to facilitate the process of periodically and systematically updating the results in an internally consistent manner.

  16. Assisting Students Struggling with Mathematics: Response to Intervention (RtI) for Elementary and Middle Schools. Q&A with Ben Clarke Ph.D and Paul Riccomini, Ph.D. REL Mid-Atlantic Event

    ERIC Educational Resources Information Center

    Clarke, Ben; Riccomini, Paul

    2013-01-01

    This REL Mid-Atlantic Event focused on effective strategies for screening, instruction, and differentiation of instruction as part of math RtI implementation. The Q&A presented in this document address the questions participants had for Dr. Clarke and Dr. Riccomini following the event. Dr. Clarke's and Dr. Riccomini's PowerPoint presentations…

  17. Effects of the Connected Mathematics Project 2 (CMP2) on the Mathematics Achievement of Grade 6 Students in the Mid-Atlantic Region. Final Report. NCEE 2012-4017

    ERIC Educational Resources Information Center

    Martin, Taylor; Brasiel, Sarah J.; Turner, Herb; Wise, John C.

    2012-01-01

    This study examines the effects of Connected Mathematics Project 2 (CMP2) on grade 6 student mathematics achievement and engagement using a cluster randomized controlled trial (RCT) design. It responds to a need to improve mathematics learning in the Mid-Atlantic Region (Delaware, Maryland, New Jersey, Pennsylvania, and Washington, DC). Findings…

  18. The Fauna Of Two New Discovered Hydrothermal Fields At 5°S And 9°33'S On The Mid-Atlantic-Ridge

    NASA Astrophysics Data System (ADS)

    Stecher, J. E.

    2005-12-01

    Before April 2005 there was a zoogeographical puzzle to solve: Are there any hydrothermal vent communities south of the equator the Atlantic Ocean, and if so, what will be their characteristics? Are they similar with those of the northern Atlantic Ocean or will they differ? Before the cruise 169 of the British "Charles Darwin" research vessel started, no vent site was discovered on the southern Atlantic Ridge. Using an autonomous underwater vehicle from WHOI, the first hydrothermal active vent site was found at 5°S in April 2005. With the support by British and American colleagues(Chris German and Tim Shank) the scientific crew of Meteor cruise M64/1 sampled this site at 5° first with the ROV "Quest 4000" from Marum, University Bremen. But far in excess of this success one more vent site was discovered and investigated by the Meteor cruise M64/1: the Lilliput Field at 9°33S on the Mid-Atlantic-Ridge. Our first results indicate that the identified taxa of the hydrothermal fields at 5°S and 9°33S resemble the northern Logatchev community (Gebruk et al. 2000) in most elements. Remarkable is the missing of following typical hydrothermal taxa: Decapods of the families Alvinocaridae, like Chorocaris, and Galatheidae, echinoderms like Ophiuridae and Ventfishes of the family Zoarcidae. Obviously the Romanch Fracture Zone act only partly as a physical barrier between vent fauna assemblages of the North and South Atlantic Oceans (see Shank 2004). Gebruk, A.V., Chevaldonne, P., Shank, T., Lutz, R.A. & Vrijenhoek, R.C. (2000): Deep-sea hydrothermal vent communities of the Logatchev area (14°45'N, Mid-Atlantic Ridge): diverse biotopes and high biomass. J. Mar. Biol. Assoc. U. K. 80: 383-393. Shank, T. (2004): The evolutionary puzzle of seafloor life. - Oceanus Magazine Vol. 42, No.2 http://oceanusmag.whoi.edu/v42n2/shank.html.

  19. The tectonic evolution of the Mid-Atlantic Ridge between 55°55'N and the Bight Transform Fault during the past 6 Ma

    NASA Astrophysics Data System (ADS)

    Benediktsdottir, A.; Hey, R. N.; Martinez, F.; Hoskuldsson, A.

    2014-12-01

    We present a new propagating rift model of the Mid-Atlantic Ridge between 55°55'N and the Bight Transform Fault (BTF) explaining the tectonic history of the area during the past 6 Ma, using marine magnetic anomalies collected in the fall of 2013. The data consist of thirteen flowline parallel lines across the ridge and they show that the accretion across the ridge has not been symmetric. Using Magellan, a new tool to model magnetic anomalies, we obtain a tectonic evolution of the area for the past 6 Ma. The area just south of the BTF (at 0-20 km distance) is characterized by a very large asymmetry in the magnetic data. This asymmetry is most clearly seen within the Brunhes anomaly, which has a big divide in it. Our model suggests that the ridge has shifted twice some 8-12 km to the east within the past 2 Ma resulting from two very rapid rift propagations. We could not determine whether the propagations were to the south or north because of very rapid propagation rates. The tectonic evolution of the area 20-90 km south of the BTF is simpler and the model is more readily understood. The model suggests that a few short lived propagators cause asymmetry in the area. They all, but one, propagate north toward the BTF and all, but one, transfer lithosphere from the Eurasian plate to the North-American plate. Unlike the prominent far reaching (> 100km) propagators just south of Iceland these propagators are short. They play an important role in the tectonic evolution of the ridge and our results suggest that the Mid-Atlantic Ridge in this area is very dynamic.

  20. Quantification of the effects of eustasy, subsidence, and sediment supply on Miocene sequences, mid-Atlantic margin of the United States

    USGS Publications Warehouse

    Browning, J.V.; Miller, K.G.; McLaughlin, P.P.; Kominz, M.A.; Sugarman, P.J.; Monteverde, D.; Feigenson, M.D.; Hernandez, J.C.

    2006-01-01

    We use backstripping to quantify the roles of variations in global sea level (eustasy), subsidence, and sediment supply on the development of the Miocene stratigraphic record of the mid-Atlantic continental margin of the United States (New Jersey, Delaware, and Maryland). Eustasy is a primary influence on sequence patterns, determining the global template of sequences (i.e., times when sequences can be preserved) and explaining similarities in Miocene sequence architecture on margins throughout the world. Sequences can be correlated throughout the mid-Atlantic region with Sr-isotopic chronology (??0.6 m.y. to ??1.2 m.y.). Eight Miocene sequences correlate regionally and can be correlated to global ??18O increases, indicating glacioeustatic control. This margin is dominated by passive subsidence with little evidence for active tectonic overprints, except possibly in Maryland during the early Miocene. However, early Miocene sequences in New Jersey and Delaware display a patchwork distribution that is attributable to minor (tens of meters) intervals of excess subsidence. Backstripping quantifies that excess subsidence began in Delaware at ca. 21 Ma and continued until 12 Ma, with maximum rates from ca. 21-16 Ma. We attribute this enhanced subsidence to local flexural response to the progradation of thick sequences offshore and adjacent to this area. Removing this excess subsidence in Delaware yields a record that is remarkably similar to New Jersey eustatic estimates. We conclude that sea-level rise and fall is a first-order control on accommodation providing similar timing on all margins to the sequence record. Tectonic changes due to movement of the crust can overprint the record, resulting in large gaps in the stratigraphic record. Smaller differences in sequences can be attributed to local flexural loading effects, particularly in regions experiencing large-scale progradation. ?? 2006 Geological Society of America.

  1. THE EFFECTS OF MACROINVERTEBRATE TAXONOMIC RESOLUTION IN LARGE LANDSCAPE BIOASSESSMENTS: AN EXAMPLE FROM THE MID-ATLANTIC HIGHLANDS, USA

    EPA Science Inventory

    The macroinvertebrate taxonomic resolution needed for detecting human impacts on stream ecosystems draws continued attention from stream ecologists. During late spring 1993-1995, the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) sam...

  2. LAND USE CHANGE DUE TO URBANIZATION FOR THE MID-ATLANTIC INTEGRATED ASSESSMENT REGION OF THE EASTERN UNITED STATES

    EPA Science Inventory

    The U.S. Environmental Protection Agency's (EPA) Regional Vulnerability Assessment Pro- gram (REVA) is designed to develop and demonstrate approaches to identify the ecosystems at the greatest risk from regional population growth and economic activity (Smith, 1999). A region is a...

  3. HYDROGEOLOGIC FOUNDATION IN SUPPORT OF ECOSYSTEM RESTORATION: BASE-FLOW LOADINGS OF NITRATE IN MID-ATLANTIC AGRICULTURAL WATERSHEDS

    EPA Science Inventory

    The study is a consortium between the U.S. Environmental Protection Agency (National Risk Management Research Laboratory) and the U.S. Geological Survey (Baltimore and Dover). The objectives of this study are: (1) to develop a geohydrological database for paired agricultural wate...

  4. Seismicity And Accretion Processes Along The Mid-Atlantic Ridge south of the Azores using data from the MARCHE Autonomous Hydrophone Array

    NASA Astrophysics Data System (ADS)

    Perrot, Julie; Cevatoglu, Melis; Cannat, Mathilde; Escartin, Javier; Maia, Marcia; Tisseau, Chantal; Dziak, Robert; Goslin, Jean

    2013-04-01

    The seismicity of the South Atlantic Ocean has been recorded by the MARCHE network of 4 autonomous underwater hydrophones (AUH) moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). The instruments were deployed south of the Azores Plateau between 32° and 39°N from July 2005 to August 2008. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation result in a detection threshold reduction from a magnitude completeness level (Mc) of ~4.3 for MAR events recorded by the land-based seismic networks to Mc=2.1 using this hydrophone array. A spatio-temporal analysis has been performed among the 5600 events recorded inside the MARCHE array. Most events are distributed along the ridge between lat. 39°N on the Azores Platform and the Rainbow (36°N) segment. In the hydrophone catalogue, acoustic magnitude (Source Level, SL) is used as a measure of earthquake size. The source level above which the data set is complete is SLc=205 dB. We look for seismic swarms using the cluster software of the SEISAN package. The criterion used are a minimum SL of 210 to detect a possible mainshock, and a radius of 30 km and a time window of 40 days after this mainshock (Cevatoglu, 2010, Goslin et al., 2012). 7 swarms with more than 15 events are identified using this approach between 32°et 39°N of latitude. The maximum number of earthquake in a swarm is 57 events. This result differs from the study of Simao et al. (2010) as we processed a further year of data and selected sequences with fewer events. Looking at the distribution of the SL as a function of time after the mainshock, we discuss the possible mechanism of these earthquakes : tectonic events with a "mainshock-aftershock" distribution fitting a modified Omori law or volcanic events showing more constant SL values. We also present the geophysical setting of these 7 swarms, using gravity, bathymetry, and available local geological data. This study illustrates the potential of

  5. USEPA MANUAL OF METHODS FOR VIROLOGY | Science ...

    EPA Pesticide Factsheets

    This chapter describes procedures for the detection of coliphases in water matrices. These procedures are based on those presented in the Supplement to the 20th Edition of Standard Methods for the Examination of Water and Eastewater and EPA Methods 1601 and 1602. Two quantitative procedures and one qualitative, presence-absence procedures are presented. The procedures can be used, without supplementary methods, to assay small volumes of water (10 mL to 1L). For larger volumes (>100L), large-scale concentration methods such as described in Chapter 14 may be incorporated into the assay scheme. However, as some concentration procedures may result in appreciable loss or inactivation of coliphage, it is recommended that the suitability of any large volume concentration method be evaluated in measured recovery trials before implementation. Develop sensitive techniques to detect and identify emerging human waterborne pathogenic viruses and viruses on the CCL.Determine effectiveness of viral indicators to measure microbial quality in water matrices.Support activities: (a) culture and distribution of mammalian cells for Agency and scientific community research needs, (b) provide operator expertise for research requiring confocal and electron microscopy, (c) glassware cleaning, sterilization and biological waste disposal for the Cincinnati EPA facility, (d) operation of infectious pathogenic suite, (e) maintenance of walk-in constant temperature rooms and (f) provid

  6. Hydrothermal activity on the southern Mid-Atlantic Ridge: Tectonically- and volcanically-controlled venting at 4 5°S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Murton, B. J.; Parson, L. M.; Prien, R. D.; Ramirez-Llodra, E.; Jakuba, M.; Shank, T. M.; Yoerger, D. R.; Baker, E. T.; Walker, S. L.; Nakamura, K.

    2008-09-01

    We report results from an investigation of the geologic processes controlling hydrothermal activity along the previously-unstudied southern Mid-Atlantic Ridge (3-7°S). Our study employed the NOC (UK) deep-tow sidescan sonar instrument, TOBI, in concert with the WHOI (USA) autonomous underwater vehicle, ABE, to collect information concerning hydrothermal plume distributions in the water column co-registered with geologic investigations of the underlying seafloor. Two areas of high-temperature hydrothermal venting were identified. The first was situated in a non-transform discontinuity (NTD) between two adjacent second-order ridge-segments near 4°02'S, distant from any neovolcanic activity. This geologic setting is very similar to that of the ultramafic-hosted and tectonically-controlled Rainbow vent-site on the northern Mid-Atlantic Ridge. The second site was located at 4°48'S at the axial-summit centre of a second-order ridge-segment. There, high-temperature venting is hosted in an ˜ 18 km 2 area of young lava flows which in some cases are observed to have flowed over and engulfed pre-existing chemosynthetic vent-fauna. In both appearance and extent, these lava flows are directly reminiscent of those emplaced in Winter 2005-06 at the East Pacific Rise, 9°50'N and reference to global seismic catalogues reveals that a swarm of large (M 4.6-5.6) seismic events was centred on the 5°S segment over a ˜ 24 h period in late June 2002, perhaps indicating the precise timing of this volcanic eruptive episode. Temperature measurements at one of the vents found directly adjacent to the fresh lava flows at 5°S MAR (Turtle Pits) have subsequently revealed vent-fluids that are actively phase separating under conditions very close to the Critical Point for seawater, at ˜ 3000 m depth and 407 °C: the hottest vent-fluids yet reported from anywhere along the global ridge crest.

  7. Deep-pelagic (0-3000 m) fish assemblage structure over the Mid-Atlantic Ridge in the area of the Charlie-Gibbs Fracture Zone

    NASA Astrophysics Data System (ADS)

    Cook, April B.; Sutton, Tracey T.; Galbraith, John K.; Vecchione, Michael

    2013-12-01

    Only a miniscule fraction of the world’s largest volume of living space, the ocean’s midwater biome, has ever been sampled. As part of the International Census of Marine Life field project on Mid-Atlantic Ridge ecosystems (MAR-ECO), a discrete-depth trawling survey was conducted in 2009 aboard the NOAA FSV Henry B. Bigelow to examine the pelagic faunal assemblage structure and distribution over the Charlie-Gibbs Fracture Zone (CGFZ) of the northern Mid-Atlantic Ridge. Day/night sampling at closely spaced stations allowed the first characterization of diel vertical migration of pelagic nekton over the MAR-ECO study area. Discrete-depth sampling from 0-3000 m was conducted using a Norwegian “Krill” trawl with five codends that were opened and closed via a pre-programmed timer. Seventy-five species of fish were collected, with a maximum diversity and biomass observed between depths of 700-1900 m. A gradient in sea-surface temperature and underlying watermasses, from northwest to southeast, was mirrored by a similar gradient in ichthyofaunal diversity. Using multivariate analyses, eight deep-pelagic fish assemblages were identified, with depth as the primary discriminatory variable. Strong diel vertical migration (DVM) of the mesopelagic fauna was a prevalent feature of the study area, though the numerically dominant fish, Cyclothone microdon (Gonostomatidae), exhibited a broad (0-3000 m) vertical distribution and did not appear to migrate on a diel basis. Three patterns of vertical distribution were observed in the study area: (a) DVM of mesopelagic, and possibly bathypelagic, taxa; (b) broad vertical distribution spanning meso- and bathypelagic depths; and (c) discrete vertical distribution within a limited depth range. Overall species composition and rank order of abundance of fish species agreed with two previous expeditions to the CGFZ (1982-1983 and 2004), suggesting some long-term consistency in the ichthyofaunal composition of the study area, at least

  8. CONCERNS/ISSUES OF USEPA'S ORD PATHOGEN EQUIVALENCY COMMITTEE

    EPA Science Inventory

    USEPA/ORD's emphasis is on protection of public health and good science. EPA's approach of minimizing health risks of land application by reducing pathogens below the detection limit via Class A treatment or Class B treatment followed by natural attenuation is discussed. The June...

  9. USEPA MUNICIPAL WASTEWATER TREATMENT BY CONSTRUCTED WETLANDS MANUAL

    EPA Science Inventory

    A description of the upcoming USEPA manual is presented along with discussion of salient points of the conceptual approach employed in its development. The manual is the first to recognize and identify the primary removal mechanisms in these systems when they are applied to preli...

  10. USEPA SITE PROGRAM APPROACH TO TECHNOLOGY TRANSFER AND REGULATORY ACCEPTANCE

    EPA Science Inventory

    The USEPA's SITE program was created to meet the demand for innovative technologies for hazardous waste treatment. The primary mission of the SITe Program is to expedite the cleanup of sites on the NPL. These sites often have multiple contaminants in soil and groundwater, and few...

  11. Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

    NASA Technical Reports Server (NTRS)

    Sheehan, Anne F.; Solomon, Sean C.

    1991-01-01

    Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

  12. FAMOUS and AMAR segments on the Mid-Atlantic Ridge: ubiquitous hydrothermal Mn, CH 4, δ3He signals along the rift valley walls and rift offsets

    NASA Astrophysics Data System (ADS)

    Bougault, H.; Aballéa, M.; Radford-Knoery, J.; Charlou, J. L.; Baptiste, P. Jean; Appriou, P.; Needham, H. D.; German, C.; Miranda, M.

    1998-09-01

    Dynamic hydrocast experiments enabled Mn (TDM), CH 4 concentrations and δ3He ratio to be recorded through vertical cross-sections of hydrothermal plumes along the FAMOUS segment and the southern part of the AMAR segment on the Mid-Atlantic Ridge between 36°N and 37°N. Mn, CH 4 and δ3He figures all along both segments are well above the seawater background in the open ocean: they are interpreted to be the result of time-integrated hydrothermal discharges dispersed and mixed in a closed basin delineated by the rift valley and the segment ends. Hydrothermal activity along the FAMOUS and AMAR segments appears to be similar. A comparison of the residence times of the three tracers from the dispersed, time-integrated signals is proposed. Although the background values in these closed basin are high, some proximal and (or) large hydrothermal inputs, overprinted on the general time-integrated plume, can be detected (i.e. the Rainbow site south of AMAR). Based on the depth and the location of plumes, hydrothermal activity is not, by far, limited to the neo-volcanic inner floor of the valley and should involve the walls and complex offsets of the rift valley. Considering the Mn and CH 4 concentrations in these plumes, two types of ocean-mantle interaction may be represented: hot, focused discharges on ultramafic exposures (Rainbow site) and low-temperature diffuse serpentinisation.

  13. IODP Expedition 336: initiation of long-term coupled microbiological, geochemical, and hydrological experimentation within the seafloor at North Pond, western flank of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Edwards, K.; Bach, W.; Klaus, A.

    2014-04-01

    Integrated Ocean Drilling Program (IODP) Expedition 336 addressed questions concerning subseafloor microbial life and its relation to seawater circulation and basalt-seawater reactions in the basaltic ocean crust. Sediment and basement samples were recovered at three drill sites located in the North Pond area, an 8 × 15 km large sediment pond on the 8 Ma western flank of the Mid-Atlantic Ridge around 22°45' N and 46°05' W in roughly 4450 m water depth. The average core recovery rate in basement was approx. 31%. The subseafloor depth of the basement holes ranges from 90 to 332 m; sediment thickness is between 36 and 90 m. Two of the holes (U1382A, and U1383C) were equipped with advanced Circulation Obviation Retrofit Kit (CORK) observatories, employing - for the first time - fiberglass casing. Another CORK string was deployed in Deep Sea Drilling Project (DSDP) Hole 395A, but the wellhead broke off upon final installment. Nonetheless, the North Pond observatory is fully operational and post-cruise observatory research is already underway. Combined geochemical and microbiological studies of the drill core samples and experimental CORK materials will help understand (1) the extent and activity of microbial life in basalt and its relation to basalt alteration by circulating seawater, and (2) the mechanism of microbial inoculation of an isolated sediment pond.

  14. Bathyal demersal fishes of Charlie Gibbs Fracture Zone region (49-54°N) of the Mid-Atlantic Ridge, I: Results from trawl surveys

    NASA Astrophysics Data System (ADS)

    Cousins, Nicola J.; Shields, Mark A.; Crockard, Deborah; Priede, Imants G.

    2013-12-01

    Demersal fishes were sampled by single-warp otter trawl (OTSB) at three sites on the Mid-Atlantic Ridge (MAR), to the northeast (NE), northwest (NW) and southeast (SE) of the Charlie-Gibbs Fracture Zone at approximately 2500 m depth. The mean abundance was 4109 fish km-2 (SD 3714) and biomass 897.1 kg km-2 (SD 842.9) compared with 1996 fish km-2 (SD 1497) and 721.2 kg km-2 (SD 387) at the same depth on the Porcupine Seabight (PSB) segment of the NE Atlantic Ocean margin from previous studies. There was no significant difference in biomass or abundance between the three sites on the MAR, nor in comparison with the ocean margin. A total of fish 22 species were recorded at the three MAR sites with evidence of highest species richness at the SE site. No unique species were found on the ridge; but there were differences in species composition between the PSB and the MAR. Coryphaenoides brevibarbis and Antimora rostrata were important at both the NE and NW trawl sites on the MAR whereas Halosauropsis macrochir was most important in the SE. We conclude that the MAR is an important habitat for species otherwise confined to narrow strips of appropriate depth around the North Atlantic Ocean margins. The MAR supports similar population densities to ocean margin settings but with differences in relative importance of different species between regions.

  15. Bacteria dominate the ammonia-oxidizing community in a hydrothermal vent site at the Mid-Atlantic Ridge of the South Atlantic Ocean.

    PubMed

    Xu, Wei; Li, Meng; Ding, Jie-Fei; Gu, Ji-Dong; Luo, Zhu-Hua

    2014-09-01

    Ammonia oxidation is the first and rate-limiting step of nitrification, which is carried out by two groups of microorganisms: ammonia-oxidizing bacteria (AOB) and the recently discovered ammonia-oxidizing archaea (AOA). In this study, diversity and abundance of AOB and AOA were investigated in five rock samples from a deep-sea hydrothermal vent site at the Mid-Atlantic Ridge (MAR) of the South Atlantic Ocean. Both bacterial and archaeal ammonia monooxygenase subunit A (amoA) gene sequences obtained in this study were closely related to the sequences retrieved from deep-sea environments, indicating that AOB and AOA in this hydrothermal vent site showed typical deep ocean features. AOA were more diverse but less abundant than AOB. The ratios of AOA/AOB amoA gene abundance ranged from 1/3893 to 1/242 in all investigate samples, indicating that bacteria may be the major members responding to the aerobic ammonia oxidation in this hydrothermal vent site. Furthermore, diversity and abundance of AOA and AOB were significantly correlated with the contents of total nitrogen and total sulfur in investigated samples, suggesting that these two environmental factors exert strong influences on distribution of ammonia oxidizers in deep-sea hydrothermal vent environment.

  16. Two new species of cystidicolid nematodes from the digestive tract of the deep-sea fish Coryphaenoides mediterraneus (Giglioli) (Macrouridae) from the Mid-Atlantic Ridge.

    PubMed

    Moravec, Frantisek; Klimpel, Sven

    2009-05-01

    Two new nematode species, Ascarophis longiovata n. sp. and Neoascarophis longispicula n. sp. (Cystidicolidae), are described from the digestive tract of the marine deep-water fish, the Mediterranean grenadier Coryphaenoides mediterraneus (Giglioli), from the Mid-Atlantic Ridge. The former species is characterised mainly by the structure of the mouth (large pseudolabia, each with well-developed dorsal and ventral extension and small apical protrusion; submedian labia almost absent), the large, elongate-oval, non-filamented eggs (60-66 x 18-27 microm), a cervical inflation of the cuticle, bifurcate deirids, and the length of the spicules (315-360 and 120-147 microm), whereas the latter (only males available) can be distinguished by the length of the spicules (960-1,149 and 258-351 microm) and their length ratio (1:1.91-2.71), the shape of the deirids (bifurcate, with long, narrow posterior arms), and the location of the excretory pore and deirids well posterior to the level of the nerve-ring.

  17. (210)Po and (210)Pb in the tissues of the deep-sea hydrothermal vent mussel Bathymodiolus azoricus from the Menez Gwen field (Mid-Atlantic Ridge).

    PubMed

    Charmasson, Sabine; Le Faouder, Antoine; Loyen, Jeanne; Cosson, Richard P; Sarradin, Pierre-Marie

    2011-01-15

    The hydrothermal deep-sea vent fauna is naturally exposed to a highly specific environment enriched in potentially toxic species such as sulfides, metals and natural radionuclides due to the convective seawater circulation inside the oceanic crust and its interaction with basaltic or ultramafic host rocks. However, data on radionuclides in biota from such environment are very limited. An investigation was carried out on tissue partitioning of (210)Po and (210)Pb, two natural radionuclides within the (238)U decay chain, in Bathymodiolus azoricus specimens from the Mid-Atlantic Ridge (Menez Gwen field). These two elements showed different distributions with high (210)Pb levels in gills and high (210)Po levels in both gills and especially in the remaining parts of the body tissue (including the digestive gland). Various factors that may explain such partitioning are discussed. However, (210)Po levels encountered in B. azoricus were not exceptionally high, leading to weighted internal dose rate in the range 3 to 4 μGy h⁻¹. These levels are slightly higher than levels characterizing coastal mussels (~1 μGy h⁻¹).

  18. Trophic influences of metal accumulation in natural pollution laboratories at deep-sea hydrothermal vents of the Mid-Atlantic Ridge.

    PubMed

    Kádár, Enikõ; Costa, Valentina; Segonzac, Michel

    2007-02-15

    This study reports on the concentration of both, toxic (Hg) and essential (Fe, Cu, Zn) metals in representative species, at four hydrothermal vents along the Mid-Atlantic Ridge (MAR) corresponding to the different exposure conditions that are the result of contrasted geological setting and different depths along the ridge axis. Macro fauna collected from these vent sites showed markedly different whole tissue concentration of metals reflecting exposure levels. Bio-transfer of metals within a typical hydrothermal food chain was investigated. There were trophic level-specific variations in essential metal accumulation showing a general trend within which the secondary consumers (predators/scavengers) and primary consumers (filter-feeder/symbiont reliant species like the mixotrophic mollusks and sponges all having metal concentrations above those in passive suspension-feeders such as echinoderms, gorgonians) accumulated highest concentrations of all elements followed by primary producers such as endosymbiont bacteria. Mercury accumulation followed a somewhat different sequence among the same taxonomic groups: top concentrations in the symbiont-bearing filter-feeder bivalves >crustaceans> sponges > bacteria > echinoderms, gorgonians and tunicates. There were no indications of biomagnification of Hg, Cu and Zn unlike Fe that showed positive transference factors (TF) along two trophic levels of a typical chain at Menez Gwen.

  19. On the role of abiogenic factors in the bioaccumulation of heavy metals by the hydrothermal fauna of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Demina, L. L.; Galkin, S. V.

    2008-12-01

    The distributions of Fe, Mn, Zn, Cu, Ni, Co, Cr, Pb, As, Ag, Cd, Se, Sb, and Hg in 128 samples of tissues of the organisms that inhabit hydrothermal vent fields of the Mid-Atlantic Ridge (Menez Gwen, Snake Pit, and Rainbow) depending on the abiotic environmental parameters were studied. The majority of the elements studied showed direct correlations between their concentrations in the fluids released and in the tissues of hydrothermal organisms. A higher degree of bioaccumulation of metals was revealed in the Bathymodiolus mussels and Rimicaris shrimps from the Rainbow hydrothermal vent field as compared to their analogues from Menez Gwen and Snake Pit. This corresponds to the maximum concentrations of the majority of the metals studied in the Rainbow high-temperature hydrothermal fluids. The highest degree of bioaccumulation of heavy metals was found in gills of the symbiotrophic mussels Bathymodiolus and in maxillipeds of the ectosymbiotic shrimps Rimicaris, i.e., in the organs that function in dependence on chemosynthetic bacteria. Within the Rainbow vent field, the shrimps, which inhabit in biotopes with more high-temperature conditions and therefore are more strongly subjected to the influence of fluids, were found to contain higher metal contents than mollusks. The Fe-Mn hydroxide films that cover mussel shells might serve as important reservoirs of other metals related to Fe and Mn.

  20. PGE fractionation in seafloor hydrothermal systems: examples from mafic- and ultramafic-hosted hydrothermal fields at the slow-spreading Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Pašava, Jan; Vymazalová, Anna; Petersen, Sven

    2007-04-01

    The distribution of platinum group elements (PGEs) in massive sulfides and hematite-magnetite±pyrite assemblages from the recently discovered basalt-hosted Turtle Pits hydrothermal field and in massive sulfides from the ultramafic-hosted Logatchev vent field both on the Mid-Atlantic Ridge was studied and compared to that from selected ancient volcanic-hosted massive sulfide (VHMS) deposits. Cu-rich samples from black smoker chimneys of both vent fields are enriched in Pd and Rh (Pd up to 227 ppb and Rh up to 149 ppb) when compared to hematite-magnetite-rich samples from Turtle Pits (Pd up to 10 ppb, Rh up to 1.9 ppb). A significant positive correlation was established between Cu and Rh in sulfide samples from Turtle Pits. PGE chondrite-normalized patterns (with a positive Rh anomaly and Pd and Au enrichment), Pd/Pt and Pd/Au ratios close to global MORB, and high values of Pd/Ir and Pt/Ir ratios indicate mafic source rock and seawater involvement in the hydrothermal system at Turtle Pits. Similarly shaped PGE chondrite-normalized patterns and high values of Pd/Pt and Pd/Ir ratios in Cu-rich sulfides at Logatchev likely reflect a similar mechanism of PGE enrichment but with involvement of ultramafic source rocks.

  1. Fine-scale velocity structure of upper oceanic crust from full waveform inversion of downward continued seismic reflection data at the Lucky Strike Volcano, Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Arnulf, A. F.; Harding, A. J.; Singh, S. C.; Kent, G. M.; Crawford, W.

    2012-04-01

    We present a fine-scale 2D velocity structure beneath the Lucky Strike Volcano on the Mid-Atlantic Ridge (MAR) using an elastic full waveform inversion (FWI) method. The FWI is a data driven procedure that allows simultaneous exploitation of both reflections and refractions energy in multi-channel seismic data to create a single self-consistent, high-resolution velocity image of the upper crust that can be used for geologic interpretation. The long-wavelength background P-wave velocity model required by the local optimization approach was created using a combination of downward continuation and 3D first-arrival travel-time tomography. The elastic waveform inversion was applied to carefully windowed downward continued data, where wide-angle reflections and refractions arrive in front of the water-wave and are thus isolated from the high-amplitude seafloor scattering energy that is particularly acute in areas of rough igneous seafloor. Waveform inversion reduces the misfit of the initial model by 76% after 19 iterations and strongly reduced the size of the residuals relative to the signal size. The final model shows fine scale structure beneath the northern part of the Lucky Strike volcano on a resolution of tens of meters. Evidence for successive lava sequences testifies to the constructional origin of the upper section of layer 2A. Normal faults are revealed within the shallow crust and are strongly correlated with seafloor observations.

  2. 2-D difference gel electrophoresis approach to assess protein expression profiles in Bathymodiolus azoricus from Mid-Atlantic Ridge hydrothermal vents.

    PubMed

    Company, Rui; Antúnez, Oreto; Bebianno, Maria João; Cajaraville, Miren P; Torreblanca, Amparo

    2011-11-18

    Hydrothermal vent mussels Bathymodiolus azoricus are naturally exposed to toxic chemical species originated directly from vent chimneys. The amount of toxic elements varies significantly among vent sites along the Mid-Atlantic Ridge and B. azoricus must be able to adapt to changes in hydrothermal fluid composition, temperature and pressure. The aim of this work was to study changes in the proteome in the "gill-bacteria complex" of mussels B. azoricus from three hydrothermal vent sites with distinct environmental characteristics using 2-D Fluorescence Difference Gel Electrophoresis (2-D DIGE). Results showed that 31 proteins had different expression profiles among vent sites and both cluster and principal component analysis confirm a clear separation of mussels between sites. This suggests the existence of specific parameters grouping individuals from the same hydrothermal site. Protein spots of the more abundant differentially expressed proteins were excised, digested with trypsin and identified by mass spectrometry. All identified proteins (actin, ubiquinone, S-adenosylhomocysteine hydrolase, cysteine peptidases, chaperonin and catalase) have been related previously with oxidative stress conditions and are known to be affected by ROS inducing stressors, including metals. Results point out to specific adaptations at the proteome level of B. azoricus depending on the level of toxicants present in their environment.

  3. High frequency sampling of the 1984 spring bloom within the mid-Atlantic Bight: Synoptic shipboard, aircraft, and in situ perspectives of the SEEP-I experiment

    NASA Technical Reports Server (NTRS)

    Walsh, J. J.; Wirick, C. D.; Pietrafesa, L. J.; Whitledge, T. E.; Hoge, F. E.; Swift, R. N.

    1986-01-01

    Moorings of current meters, thermistors, transmissometers, and fluorometers on the mid-Atlantic shelf, south of Long Island, suggest a cumulative seaward export of perhaps 0.35 g C/sq m/day between the 80 and 120 m isobaths during February-April 1984. Such a horizontal loss of algal carbon over the lower third of the water column would be 23 to 78% of the March-April 1984 primary production. This physical carbon loss is similar to daily grazing losses from zooplankton of 32-40% of the algal fixation of carbon. Metabolic demands of the benthos could be met by just the estimated fecal pellet flux, without direct consumption of algal carbon, while bacterioplankton needs could be served by excretory release of dissolved organic matter during photosynthesis. Sediment traps tethered 10 m off the bottom at the 120 m isobath and 50 m above the 500 m isobath caught as much as 0.16 to 0.26 g C /sq m/day during March-April 1984, in reasonable agreement with the flux estimated from the other moored instruments.

  4. Composition and origin of hydrothermal petroleum and associated lipids in the sulfide deposits of the Rainbow field (Mid-Atlantic Ridge at 36°N)

    NASA Astrophysics Data System (ADS)

    Simoneit, Bernd R. T.; Lein, Alla Yu.; Peresypkin, V. I.; Osipov, G. A.

    2004-05-01

    The lipid components in hydrothermal sulfide deposits from the Rainbow vent field (Mid-Atlantic Ridge at 36°N) were studied by gas chromatography/mass spectrometry. The Rainbow vent field is one of two known active hydrothermal systems related to abyssal circulation, where high-temperature fluids are formed during serpentinization of ultrabasic crustal rocks. The major amount of the extractable organic matter from the sulfides consists of normal and branched alkanes, UCM, PAHs, terpenoids, and fatty acids. The branched alkanes are comprised of unique gem-diethylalkane series, possibly from sulfide oxidizing bacteria, and biphytanes from archaea. The characteristic lipid and biomarker compounds found in the hydrothermal samples support a predominantly biological origin of the bitumens from the thermal transformation of the biomass of microorganisms (bacteria and archea) and minor macrofauna of this vent field. A search for molecular evidence for abiogenic thermocatalytic synthesis of organic compounds was negative. However, methane in the hydrothermal fluids and possibly a minor amount of the alkanes in the sulfides may be of an abiogenic origin in the Rainbow vent field.

  5. Comparison of marine gravity from shipboard and high-density satellite altimetry along the Mid-Atlantic Ridge, 30.5-35.5 deg S

    NASA Technical Reports Server (NTRS)

    Neumann, Gregory A.; Forsyth, Donald W.; Sandwell, David

    1993-01-01

    We compare new marine gravity fields derived from satellite altimetry with shipboard measurements over a region of more than 120,000 sq km in the central South Atlantic. Newly declassified satellite data were employed to construct free-air anomaly maps on 0.05 degree grids. An extensive gravity and bathymetry data set from four cruises along the Mid-Atlantic Ridge from 30.5-35.5 deg S provides a benchmark for testing the 2D resolution and accuracy of the satellite measurements where their crosstrack spacing is near their widest. The satellite gravity signal is coherent with bathymetry in this region down to wavelengths of 26 km, compared to 12.5 km for shipboard gravity. Residuals between the shipboard and satellite data sets have a roughly normal distribution. The standard deviation of satellite gravity with respect to shipboard measurements is nearly 7 mGal in a region of 140 mGal total variation, whereas the internal standard deviation at crossovers for GPS-navigated shipboard data is 1.8 mGal. The differences between shipboard and satellite data are too large to use satellite gravity to determine crustal thickness variations within a typical ridge segment.

  6. Photobacterium sanctipauli sp. nov. isolated from bleached Madracis decactis (Scleractinia) in the St Peter & St Paul Archipelago, Mid-Atlantic Ridge, Brazil.

    PubMed

    Moreira, Ana Paula B; Duytschaever, Gwen; Chimetto Tonon, Luciane A; Fróes, Adriana M; de Oliveira, Louisi S; Amado-Filho, Gilberto M; Francini-Filho, Ronaldo B; De Vos, Paul; Swings, Jean; Thompson, Cristiane C; Thompson, Fabiano L

    2014-01-01

    Five novel strains of Photobacterium (A-394T, A-373, A-379, A-397 and A-398) were isolated from bleached coral Madracis decactis (scleractinian) in the remote St Peter & St Archipelago (SPSPA), Mid-Atlantic Ridge, Brazil. Healthy M. decactis specimens were also surveyed, but no strains were related to them. The novel isolates formed a distinct lineage based on the 16S rRNA, recA, and rpoA gene sequences analysis. Their closest phylogenetic neighbours were Photobacterium rosenbergii, P. gaetbulicola, and P. lutimaris, sharing 96.6 to 95.8% 16S rRNA gene sequence similarity. The novel species can be differentiated from the closest neighbours by several phenotypic and chemotaxonomic markers. It grows at pH 11, produces tryptophane deaminase, presents the fatty acid C18:0, but lacks C16:0 iso. The whole cell protein profile, based in MALDI-TOF MS, distinguished the strains of the novel species among each other and from the closest neighbors. In addition, we are releasing the whole genome sequence of the type strain. The name Photobacterium sanctipauli sp. nov. is proposed for this taxon. The G + C content of the type strain A-394(T) (= LMG27910(T) = CAIM1892(T)) is 48.2 mol%.

  7. Marinitoga hydrogenitolerans sp. nov., a novel member of the order Thermotogales isolated from a black smoker chimney on the Mid-Atlantic Ridge.

    PubMed

    Postec, Anne; Le Breton, Claire; Fardeau, Marie-Laure; Lesongeur, Françoise; Pignet, Patricia; Querellou, Joël; Ollivier, Bernard; Godfroy, Anne

    2005-05-01

    A novel, thermophilic, anaerobic bacterium that is able to tolerate hydrogen was isolated from a deep-sea hydrothermal chimney collected at the Rainbow field on the Mid-Atlantic Ridge. Cells were rod-shaped and surrounded by a sheath-like outer structure (toga); they were weakly motile by means of a polar flagellum. They appeared singly, in pairs or in short chains. They grew at 35-65 degrees C (optimum 60 degrees C), pH 4.5-8.5 (optimum pH 6.0) and 10-65 g sea salts l(-1) (optimum 30-40 g l(-1)). The isolate was organotrophic, and able to grow on various carbohydrates or complex proteinaceous substrates. Growth was not inhibited under 100 % hydrogen or in the presence of 2 % oxygen in the gas phase. The isolate reduces sulfur, although sulfur reduction is not required for growth. The fermentation products identified on glucose were acetate, ethanol, formate, hydrogen and CO(2). The G + C content of the genomic DNA was 28 +/- 1 mol%. Phylogenetic analysis of the 16S rRNA gene placed the strain within the genus Marinitoga, order Thermotogales, in the bacterial domain. On the basis of the 16S rRNA gene sequence comparisons and physiological characteristics, the isolate is considered to represent a novel species, for which the name Marinitoga hydrogenitolerans sp. nov. is proposed. The type strain is AT1271(T) (=DSM 16785(T) = JCM 12826(T)).

  8. Insights about the genetic diversity and population structure of an offshore group of common bottlenose dolphins (Tursiops truncatus) in the Mid-Atlantic.

    PubMed

    Castilho, C S; Pedone-Valdez, F; Bertuol, F; Fruet, P; Genoves, R C; Di Tullio, J C; Caon, G; Hoffmann, L S; Freitas, T R O

    2015-04-15

    Although the genus Tursiops has a worldwide distribution and is globally well-studied, some dolphin populations continue to face high risks of decline. Hence, it is necessary to assess the genetic diversity and structure of this genus to properly assess its conservation status and to implement appropriate management actions. In Brazil, genetic studies on this group remain rare, particularly for populations inhabiting offshore waters. Saint Peter and Saint Paul Archipelago (SPSPA) is a small group of islands located in the Mid- Atlantic Ridge, where recent studies of the Tursiops truncatus group indicate that individuals are resident throughout the year around the archipelago, exhibiting considerable site fidelity. A previous study with this group indicated that the individuals form an isolated population. To test this hypothesis, and describe the genetic diversity of SPSPA individuals, we assessed 12 microsatellite loci and a portion of the mitochondrial control region. Bayesian analysis revealed that SPSPA bottlenose dolphins form a unique population. In a phylogeographic perspective, we found that individuals from SPSPA shared mtDNA haplotypes with inshore and offshore individuals from North Atlantic, suggesting that they are not currently isolated from their conspecifics. Mirroring mtDNA findings, microsatellite analysis revealed that most of the pairs of individuals sampled seem to be unrelated (83.8%) and no indication of inbreeding, what would be expected if a small population such as SPSPA was reproductively isolated.

  9. Diversity, distribution and antibiotic resistance of Enterococcus spp. recovered from tomatoes, leaves, water and soil on U.S. Mid-Atlantic farms.

    PubMed

    Micallef, Shirley A; Goldstein, Rachel E Rosenberg; George, Ashish; Ewing, Laura; Tall, Ben D; Boyer, Marc S; Joseph, Sam W; Sapkota, Amy R

    2013-12-01

    Antibiotic-resistant enterococci are important opportunistic pathogens and have been recovered from retail tomatoes. However, it is unclear where and how tomatoes are contaminated along the farm-to-fork continuum. Specifically, the degree of pre-harvest contamination with enterococci is unknown. We evaluated the prevalence, diversity and antimicrobial susceptibilities of enterococci collected from tomato farms in the Mid-Atlantic United States. Tomatoes, leaves, groundwater, pond water, irrigation ditch water, and soil were sampled and tested for enterococci using standard methods. Antimicrobial susceptibility testing was performed using the Sensititre microbroth dilution system. Enterococcus faecalis isolates were characterized using amplified fragment length polymorphism to assess dispersal potential. Enterococci (n = 307) occurred in all habitats and colonization of tomatoes was common. Seven species were identified: Enterococcus casseliflavus, E. faecalis, Enterococcus gallinarum, Enterococcus faecium, Enterococcus avis, Enterococcus hirae and Enterococcus raffinosus. E. casseliflavus predominated in soil and on tomatoes and leaves, and E. faecalis predominated in pond water. On plants, distance from the ground influenced presence of enterococci. E. faecalis from samples within a farm were more closely related than those from samples between farms. Resistance to rifampicin, quinupristin/dalfopristin, ciprofloxacin and levofloxacin was prevalent. Consumption of raw tomatoes as a potential exposure risk for antibiotic-resistant Enterococcus spp. deserves further attention.

  10. Photobacterium sanctipauli sp. nov. isolated from bleached Madracis decactis (Scleractinia) in the St Peter & St Paul Archipelago, Mid-Atlantic Ridge, Brazil

    PubMed Central

    Moreira, Ana Paula B.; Duytschaever, Gwen; Chimetto Tonon, Luciane A.; Fróes, Adriana M.; de Oliveira, Louisi S.; Amado-Filho, Gilberto M.; Francini-Filho, Ronaldo B.; De Vos, Paul; Swings, Jean; Thompson, Cristiane C.

    2014-01-01

    Five novel strains of Photobacterium (A-394T, A-373, A-379, A-397 and A-398) were isolated from bleached coral Madracis decactis (scleractinian) in the remote St Peter & St Archipelago (SPSPA), Mid-Atlantic Ridge, Brazil. Healthy M. decactis specimens were also surveyed, but no strains were related to them. The novel isolates formed a distinct lineage based on the 16S rRNA, recA, and rpoA gene sequences analysis. Their closest phylogenetic neighbours were Photobacterium rosenbergii, P. gaetbulicola, and P. lutimaris, sharing 96.6 to 95.8% 16S rRNA gene sequence similarity. The novel species can be differentiated from the closest neighbours by several phenotypic and chemotaxonomic markers. It grows at pH 11, produces tryptophane deaminase, presents the fatty acid C18:0, but lacks C16:0 iso. The whole cell protein profile, based in MALDI-TOF MS, distinguished the strains of the novel species among each other and from the closest neighbors. In addition, we are releasing the whole genome sequence of the type strain. The name Photobacterium sanctipauli sp. nov. is proposed for this taxon. The G + C content of the type strain A-394T (= LMG27910T = CAIM1892T) is 48.2 mol%. PMID:25024905

  11. Summary of environmental geologic studies in the Mid-Atlantic outer continental shelf area; results of 1978-1979 field seasons

    USGS Publications Warehouse

    Robb, James M.

    1983-01-01

    Because of the need for knowledge of an offshore area that is undergoing exploration for oil and gas resources, since 1975 the U.S. Bureau of Land Management (BLM) has funded studies of the environmental characteristics of the Mid-Atlantic Outer Continental Shelf. This volume briefly summarizes a final report to the BLM on the results of U.S. Geological Survey investigations stemming from data acquired during 1978 and 1979. The parent final report contains complete accounts of those investigations. The subjects of the studies range from the geologic effects of water currents and their capabilities of erosion and transportation, to delineation of potentially hazardous geologic characteristics of the area. Nine specific studies address the complexities of water currents, the nature of materials suspended in the sea waters, rates of mixing-in of material deposited on the bottom, and the sites of probable deposition of such materials, as well as sites and mechanisms of possible submarine landsliding or unstable bottom (engineering characteristics) of the Continental Slope and shelf.

  12. Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

    NASA Technical Reports Server (NTRS)

    Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

    2008-01-01

    Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

  13. Finescale parameterizations of energy dissipation in a region of strong internal tides and sheared flow, the Lucky-Strike segment of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Pasquet, Simon; Bouruet-Aubertot, Pascale; Reverdin, Gilles; Turnherr, Andreas; Laurent, Lou St.

    2016-06-01

    The relevance of finescale parameterizations of dissipation rate of turbulent kinetic energy is addressed using finescale and microstructure measurements collected in the Lucky Strike segment of the Mid-Atlantic Ridge (MAR). There, high amplitude internal tides and a strongly sheared mean flow sustain a high level of dissipation rate and turbulent mixing. Two sets of parameterizations are considered: the first ones (Gregg, 1989; Kunze et al., 2006) were derived to estimate dissipation rate of turbulent kinetic energy induced by internal wave breaking, while the second one aimed to estimate dissipation induced by shear instability of a strongly sheared mean flow and is a function of the Richardson number (Kunze et al., 1990; Polzin, 1996). The latter parameterization has low skill in reproducing the observed dissipation rate when shear unstable events are resolved presumably because there is no scale separation between the duration of unstable events and the inverse growth rate of unstable billows. Instead GM based parameterizations were found to be relevant although slight biases were observed. Part of these biases result from the small value of the upper vertical wavenumber integration limit in the computation of shear variance in Kunze et al. (2006) parameterization that does not take into account internal wave signal of high vertical wavenumbers. We showed that significant improvement is obtained when the upper integration limit is set using a signal to noise ratio criterion and that the spatial structure of dissipation rates is reproduced with this parameterization.

  14. Strategies, methods, and technologies adopted on the R.V. G.O. Sars MAR-ECO expedition to the Mid-Atlantic Ridge in 2004

    NASA Astrophysics Data System (ADS)

    de L. Wenneck, T.; Falkenhaug, T.; Bergstad, O. A.

    2008-01-01

    The MAR-ECO project aimed to gather information on mid-ocean ridge macro- and megafaunal assemblages and their distribution patterns in relation to the abiotic environment, and the target area extended from Iceland to the Azores, comprising waters associated with the Mid-Atlantic Ridge. Strategies and methods adopted on the 2004 international expedition on the R.V. G.O. Sars and M.S. Loran were selected in order to maximise data and sample collection in all pelagic and benthic habitats to a maximum depth of 3500 m, spanning the organism size range from mm to metres. The approach selected was to combine (1) Continuous sampling along the ship's track; (2) Point observations using a pre-defined set of samplers at pre-determined sites; and (3) Opportunistic sampling to study particular phenomena or carry out exceptional tasks. A wide range of nets and mid-water and bottom trawls were mobilised in order to collect biological samples. Hull-mounted, lowered and towed optical and acoustical instruments collected data and images. Two remotely operated vehicles (ROVs) were used for pelagic and demersal studies, and moored echosounders and cameras on benthic landers collected vessel-independent information. Observation of whales and seabirds were made from a custom-built observation area on top of the wheelhouse. Using a range of technologies from the same platform efficiently provided comprehensive results and enhanced the potential for new discoveries at the organism, community, and ecosystem levels.

  15. Lower bathyal and abyssal distribution of coral in the axial volcanic ridge of the Mid-Atlantic Ridge at 45°N

    NASA Astrophysics Data System (ADS)

    Morris, Kirsty; Tyler, Paul A.; Murton, Bramley; Rogers, Alex D.

    2012-04-01

    The deep-sea floor below 3000 m occupies 50% of the surface of the planet and is composed mainly of fine sediments. Most studies of deep-sea benthic fauna have concentrated on soft sediments with little sampling in rocky areas and even less on non-vent mid-ocean ridges. To assess the distribution and abundance of coral between 2500 m and 3500 m depths, video footage from the ROV Isis taken during a cruise to the Axial Volcanic Ridge (AVR) of the Mid-Atlantic Ridge at approx 45°30' N was analysed. Abundances per 100 m were calculated and mapped using Arc GIS, with a maximum of 59 being observed. 20 putative species were identified. Scleractinia were absent from the observed area and the coral fauna was dominated by Octocorallia. The data were separated into four substratum types, sediment, sloped rock, flat rock and mixed substratum, with both abundance and community being compared. Sedimented and rocky areas had different coral communities with sediment having a higher occurrence of Pennatulidae and Chrysogorgidae than rock. Sloped rock had the highest abundance of corals. We suggest that this increase in abundance reflects higher food availability as well as the solid substratum on which coral larvae settle.

  16. Source and Delivery of Nutrients to Receiving Waters in the Northeastern and Mid-Atlantic Regions of the United States1

    PubMed Central

    Moore, Richard B; Johnston, Craig M; Smith, Richard A; Milstead, Bryan

    2011-01-01

    Abstract This study investigates nutrient sources and transport to receiving waters, in order to provide spatially detailed information to aid water-resources managers concerned with eutrophication and nutrient management strategies. SPAtially Referenced Regressions On Watershed attributes (SPARROW) nutrient models were developed for the Northeastern and Mid-Atlantic (NE US) regions of the United States to represent source conditions for the year 2002. The model developed to examine the source and delivery of nitrogen to the estuaries of nine large rivers along the NE US Seaboard indicated that agricultural sources contribute the largest percentage (37%) of the total nitrogen load delivered to the estuaries. Point sources account for 28% while atmospheric deposition accounts for 20%. A second SPARROW model was used to examine the sources and delivery of phosphorus to lakes and reservoirs throughout the NE US. The greatest attenuation of phosphorus occurred in lakes that were large relative to the size of their watershed. Model results show that, within the NE US, aquatic decay of nutrients is quite limited on an annual basis and that we especially cannot rely on natural attenuation to remove nutrients within the larger rivers nor within lakes with large watersheds relative to the size of the lake. PMID:22457578

  17. Trace petroliferous organic matter associated with hydrothermal minerals from the Mid-Atlantic Ridge at the trans-Atlantic geotraverse 26°N site

    NASA Astrophysics Data System (ADS)

    Brault, M.; Simoneit, B. R. T.

    1989-07-01

    Hydrocarbons isolated from hydrothermal anhydrite, chalcopyrite, and sphalerite-enriched samples from the mid-Atlantic Ridge exhibit a high degree of thermal maturation, compared to a Fe-oxide-enriched sample, as evidenced by the high abundance of low molecular weight n-alkanes ranging from C14 to C25 with a broad distribution of naphthenes. These trace hydrothermally-derived petroleums contain some polycyclic aromatic hydrocarbons (PAH) and very low amounts of typical biomarkers (e.g., steroid hydrocarbons, triterpanes). The low levels of biomarkers may be due to removal by hydrothermal conversion to other products (e.g., aromatics) or have not yet formed. The Fe-oxide-enriched sample has a lower content of PAH than the other mineral samples; however, benzopyrenes and coronene are present at a significant level, and a series of mature triterpanes is also detectable. The loss of the lower molecular weight PAH in the Fe-oxide-enriched sample could be due to dissolution/oxidation processes. The presence of trace levels of petroleum strongly suggests its generation from contemporary organic detritus by hydrothermal activity and subsequent association with the minerals.

  18. Organochlorine pesticides, PCBs, dioxins, and metals in postterm peregrine falcon (Falco peregrinus) eggs from the Mid-Atlantic states, 1993-1999.

    PubMed

    Clark, Kathleen E; Zhao, Yuan; Kane, Cynthia M

    2009-07-01

    Peregrine falcons were extirpated from the eastern United States by 1964 due to the effects of dichloro-diphenyl-trichlorethane (DDT) (Peakall and Kiff 1988). As a result of restoration efforts, peregrines have largely recovered in the region but remain a barometer of environmental contamination. In the course of monitoring nests, biologists in the mid-Atlantic states collected peregrine falcon eggs that failed to hatch. In the period 1993-1999, 93 eggs were collected from 66 nests in 31 locations in New Jersey, Pennsylvania, Delaware, Maryland, and Virginia. We analyzed eggs for organochlorine pesticides, PCBs, and metals, and calculated toxic equivalencies (TEQs) for dioxins and furans. Organochlorine contaminants were detected in eggs from all parts of the region. Although nest success in all parts of the region was good, the PCB TEQ in the Atlantic-New Jersey region was significantly related to nest success, and the regionwide PCB TEQ was nearly significant for nest success across the five-state area. dichloro-diphenyl-dichloroethylene (DDE), DDT, and total PCBs were negatively correlated with eggshell thickness, although eggshell thinning (10.4%) was not at a level associated with deleterious population effects. The five states represented in this study are productive for peregrine falcons and have contributed to the recovery of this species. However, the results suggest that Atlantic coastal peregrines might be subject to contaminant burdens that have the potential to decrease nest success and productivity.

  19. Microbe-mediated transformations of marine dissolved organic matter during 2,100 years of natural incubation in the cold, oxic crust of the Mid-Atlantic Ridge.

    NASA Astrophysics Data System (ADS)

    Shah Walter, S. R.; Jaekel, U.; Huber, J. A.; Dittmar, T.; Girguis, P. R.

    2015-12-01

    On the western flank of the Mid-Atlantic Ridge, oxic seawater from the deep ocean is downwelled into the basaltic crust, supplying the crustal aquifer with an initial inoculum of organic matter and electron acceptors. Studies have shown that fluids circulating within the crust are minimally altered from original seawater, making this subsurface environment a unique natural experiment in which the fate of marine organic matter and the limitations of microbial adaptability in the context of reduced carbon supply can be examined. To make the subsurface crustal aquifer accessible, two CORK (Circulation Obviation Retrofit Kit) observatories have been installed at North Pond, a sediment-filled depression beneath the oligotrophic Sargasso Sea. Radiocarbon analysis of dissolved inorganic (DIC) and organic carbon (DOC) in samples recovered from these observatories show uncoupled aging between DOC and DIC with Δ14C values of DOC as low as -933‰ despite isolation from the open ocean for, at most, 2,100 years. This extreme value is part of a general trend of decreasing DOC δ13C and Δ14C values with increasing incubation time within the aquifer. Combined with reduced concentrations of DOC, our results argue for selective microbial oxidation of the youngest, most 13C-enriched components of downwelled DOC, possibly identifying these as characteristics of the more bioavailable fractions of deep-ocean dissolved organic matter. They also suggest that microbial oxidation during low-temperature hydrothermal circulation could be an important sink for aged marine dissolved organic matter.

  20. Variability in pigment concentration in warm-core rings as determined by coastal zone color scanner satellite imagery from the Mid-Atlantic Bight

    NASA Technical Reports Server (NTRS)

    Garcia-Moliner, Graciela; Yoder, James A.

    1994-01-01

    A time series of coastal zone color scanner (CZCS) derived chlorophyll (CZCS-chl) and sea surface temperature (SST) satellite imagery was developed for the Mid-Atlantic Bight (MAB). Warm-core rings (WCR) were identified by both the warmer SST signal as well as the low pigment concentrations of their cores. The variation in pigment concentrations and SST observed in satellite imagery over the geographic range and life span of four WCRs is investigated. The hypotheses are that pigment concentration increase during the lifetime of the WCR is a response to processes such as convective overturn, upwelling, edge enhancement due to increased vertical mixing, active convergence, or lateral exchange. Empirical orthogonal function analysis (EOF) is used to investigate the relationship between SST and pigment patterns observed in the presence of a WCR. The first two EOF modes explain more than 80% of the variability observed in all four WCRs and in both (SST and pigment) data sets. The results of this study show that, at the synoptic scales of staellite data, the variability observed in the WCRs is greater at the periphery of the rings. These results show that advective entrainment, rather than processes at ring center (e.g., shoaling of the pycnocline/nutricline in response to frictional decay) or at the periphery due to other processes such as vertical mixing, is the mechanism responsible for the observed variability.

  1. Use of geochemical mass balance modelling to evaluate the role of weathering in determining stream chemistry in five mid-Atlantic watersheds on different lithologies

    USGS Publications Warehouse

    O'Brien, Anne K.; Rice, Karen C.; Bricker, Owen P.; Kennedy, Margaret M.; Anderson, R. Todd

    1997-01-01

    The importance of mineral weathering was assessed and compared for five mid-Atlantic watersheds receiving similar atmospheric inputs but underlain by differing bedrock. Annual solute mass balances and volume-weighted mean solute concentrations were calculated for each watershed for each year of record. In addition, primary and secondary mineralogy were determined for each of the watersheds through analysis of soil samples and thin sections using petrographic, scanning electron microscope, electron microprobe and X-ray diffraction techniques. Mineralogical data were also compiled from the literature. These data were input to NETPATH, a geochemical program that calculates the masses of minerals that react with precipitation to produce stream water chemistry. The feasibilities of the weathering scenarios calculated by NETPATH were evaluated based on relative abundances and reactivities of minerals in the watershed. In watersheds underlain by reactive bedrocks, weathering reactions explained the stream base cation loading. In the acid-sensitive watersheds on unreactive bedrock, calculated weathering scenarios were not consistent with the abundance of reactive minerals in the underlying bedrock, and alternative sources of base cations are discussed.

  2. Late Neogene changes in North America and Antarctica absolute plate motions inferred from the Mid-Atlantic and Southwest Indian Ridges spreading histories

    NASA Astrophysics Data System (ADS)

    Iaffaldano, G.; DeMets, C.

    2016-08-01

    Reconstructions of absolute plate motions underpin our understanding of the plate torque balance, but are challenging due to difficulties in inferring well-dated rates and directions of plate movements from hot spot tracks. Useful information about plate dynamics can be inferred from rapid absolute plate motion changes, as these are linked only to the torque(s) that changed. Here we infer late Neogene changes in the absolute motions of North America and possibly Antarctica from changes in the easier-to-determine relative plate motions recorded along the Arctic, northern Mid-Atlantic and Southwest Indian Ridges. We show that Eurasia/North America and Nubia/North America motions changed by the same amount between 8 and 5 Ma, as may have Nubia/Antarctica and Somalia/Antarctica plate motions. By considering additional, independent constraints on Somalia/India plate motion, we argue that a scenario in which North America and Antarctica absolute motions changed is the simplest one that explains the observed changes in relative motions. We speculate that these changes are linked to the late Neogene dynamics of the Pacific plate.

  3. Metals fate and transport modelling in streams and watersheds: state of the science and USEPA workshop review

    USGS Publications Warehouse

    Caruso, B.S.; Cox, T.J.; Runkel, Robert L.; Velleux, M.L.; Bencala, Kenneth E.; Nordstrom, D. Kirk; Julien, P.Y.; Butler, B.A.; Alpers, Charles N.; Marion, A.; Smith, Kathleen S.

    2008-01-01

    Metals pollution in surface waters from point and non-point sources (NPS) is a widespread problem in the United States and worldwide (Lofts et al., 2007; USEPA, 2007). In the western United States, metals associated with acid mine drainage (AMD) from hardrock mines in mountainous areas impact aquatic ecosystems and human health (USEPA, 1997a; Caruso and Ward, 1998; Church et al., 2007). Metals fate and transport modelling in streams and watersheds is sometimes needed for assessment and restoration of surface waters, including mining-impacted streams (Runkel and Kimball, 2002; Caruso, 2003; Velleux et al., 2006). The Water Quality Analysis Simulation Program (WASP; Wool et al., 2001), developed by the US Environmental Protection Agency (USEPA), is an example of a model used for such analyses. Other approaches exist and appropriate model selection depends on site characteristics, data availability and modelling objectives. However, there are a wide range of assumptions, input parameters, data requirements and gaps, and calibration and validation issues that must be addressed by model developers, users and decision makers. Despite substantial work on model development, their successful application has been more limited because they are not often used by decision makers for stream and watershed assessment and restoration. Bringing together scientists, model developers, users and decision makers should stimulate the development of appropriate models and improve the applicability of their results. To address these issues, the USEPA Office of Research and Development and Region 8 (Colorado, Montana, North Dakota, South Dakota, Utah and Wyoming) hosted a workshop in Denver, Colorado on February 13–14, 2007. The workshop brought together approximately 35 experts from government, academia and consulting to address the state of the art for modelling metals fate and transport, knowledge gaps and future directions in metals modelling. It focused on modelling metals in high

  4. Draft Genome Sequence for the Type Strain Vulcanibacillus modesticaldus BR, a Strictly Anaerobic, Moderately Thermophilic, and Nitrate-Reducing Bacterium Isolated from Deep-Sea Hydrothermal Vents of the Mid-Atlantic Ridge

    PubMed Central

    Abin, Christopher A.

    2016-01-01

    Vulcanibacillus modesticaldus BRT was isolated from calcite-rich, metalliferous core samples collected at the Rainbow deep-sea hydrothermal vent field on the Mid-Atlantic Ridge. Here, we report the 2.2-Mb draft genome sequence for this strain, consisting of 100 contigs with a G+C content of 33.6% and 2,227 protein-coding sequences. PMID:27834704

  5. Draft Genome Sequence for the Type Strain Vulcanibacillus modesticaldus BR, a Strictly Anaerobic, Moderately Thermophilic, and Nitrate-Reducing Bacterium Isolated from Deep-Sea Hydrothermal Vents of the Mid-Atlantic Ridge.

    PubMed

    Abin, Christopher A; Hollibaugh, James T

    2016-11-10

    Vulcanibacillus modesticaldus BR(T) was isolated from calcite-rich, metalliferous core samples collected at the Rainbow deep-sea hydrothermal vent field on the Mid-Atlantic Ridge. Here, we report the 2.2-Mb draft genome sequence for this strain, consisting of 100 contigs with a G+C content of 33.6% and 2,227 protein-coding sequences.

  6. An Alternative to Channel-Centered Views of the Landscape for Understanding Modern Streams in the Mid-Atlantic Piedmont Region, Eastern USA

    NASA Astrophysics Data System (ADS)

    Merritts, D. J.; Walter, R. C.; Rahnis, M. A.; Oberholtzer, W.

    2008-12-01

    Stream channels generally are the focus of conceptual models of valley bottom geomorphology. The channel-centered model prevalent in the tectonically inactive eastern U. S. invokes meandering stream channels migrating laterally across valley floors, eroding one bank while depositing relatively coarse sediment in point bars on the other. According to this model, overbank deposition during flooding deposits a veneer of fine sediment over the gravel substrate. Erosion is considered normal, and the net volume of sediment is relatively constant with time. A dramatic change in conditions-land-clearing during European settlement--led to widespread aggradation on valley bottoms. This historic sedimentation was incorporated in the channel-centered view by assuming that meandering streams were overwhelmed by the increased sediment load and rapidly aggraded vertically. Later, elevated stream channels cut through these deposits because of decreased sediment supply and increased stormwater runoff accompanying urbanization. This view can be traced to early ideas of stream equilibrium in which incoming sediment supply and runoff determine stream-channel form. We propose a different conceptual model. Our trenching and field work along hundreds of km of stream length in the mid-Atlantic Piedmont reveal no point bars prior to European settlement. Instead, a polygenetic valley-bottom landscape underlies the drape of historic sediment. The planar surface of this veneer gives the appearance of a broad floodplain generated by long-term meandering and overbank deposition, but the "floodplain" is a recent aggradational surface from regional base-level rise due to thousands of early American dams that spanned valley bottoms. As modern streams incise into the historic fine-grained slackwater sediment, they expose organic-rich hydric soils along original valley bottom centers; talus, colluvium, bedrock, and saprolite with forest soils along valley margins; and weathered Pleistocene (and

  7. Manganese distribution in the water column near the Azores Triple Junction along the Mid-Atlantic Ridge and in the Azores domain

    NASA Astrophysics Data System (ADS)

    Aballéa, Martine; Radford-Knoery, J.; Appriou, P.; Bougault, H.; Charlou, J. L.; Donval, J. P.; Etoubleau, J.; Fouquet, Y.; German, C. R.; Miranda, M.

    1998-08-01

    As part of a multidisciplinary research effort aimed at quantifying mid-ocean ridge processes near the Azores, we conducted a survey of the water column above the mid-Atlantic Ridge (MAR) in the vicinity of the Azores Triple Junction. Manganese is a tracer of hydrothermal activity intimately related to mid-ocean ridge processes. This paper reports on 23 vertical depth profiles that were analyzed for total dissolvable manganese (TDM). TDM inputs attributable to hydrothermal circulation could be observed along the MAR in all of the southern Amar (36°15'N), Famous (36°45'N), and Lucky Strike (37°03'N and 37°17'N) segments and south of the Kurchatov fracture zone (40°10'N). To date, seafloor observations of hydrothermal activity on the seabed have been confirmed at Lucky Strike (37°17'N) and at the Rainbow site (36°14'N). Large-scale TDM distribution features along the axial valley of the MAR include a decrease in TDM concentrations from south to north (36°N to 38°30'N), followed by an increase to 40°N. In the basins within the Azores archipelago, we found the lowest TDM background levels of this study (0.4-0.6 nmol l -1) and, based on our data, no firm evidence for hydrothermal inputs of TDM. In the MAR axial valley, we observe both a more elevated TDM background (0.5-1.0 nmol l -1) and evidence for probable hydrothermal TDM inputs. This suggests that hydrothermal inputs contribute to a low-level chronic TDM plume throughout the axial valley of the MAR between 36° and 40°N.

  8. Deepwater mantle 3He plumes over the northern Mid-Atlantic Ridge (36°N-40°N) and the Azores Platform

    NASA Astrophysics Data System (ADS)

    Jean-Baptiste, P.; Fourré, E.; Dapoigny, A.; Charlou, J. L.; Donval, J.-P.

    2008-03-01

    As part of a multidisciplinary project aimed at studying mid-ocean ridge processes near the Azores, fifty water column profiles were analyzed for 3He/4He ratios in dissolved helium (a well-known hydrothermal tracer) from 36°N to 40°N along the Mid-Atlantic Ridge (MAR) and over the Azores Plateau. As expected, large δ3He anomalies could be observed over the Rainbow, Lucky Strike, and Menez Gwen hydrothermal sites. The main finding of the present study is the discovery of a large hydrothermal 3He plume north of the Açor Fracture Zone (north AFZ site), with a CH4/3He ratio indicative of a basaltic-hosted hydrothermal system. Clear 3He and CH4 anomalies, likely corresponding to unknown venting sites too, were also detected in the Amar Minor segment and south of the Kurchatov Fracture Zone. Evidence for substantial mantle helium degassing was also observed in the deep nodal basins along the Terceira Rift. On the basis of 3He plumes over the total length of the surveyed segments, the distribution of hydrothermal sites corresponds to a site frequency of 1.3 ± 0.2 site/100 km, in good agreement with the global vent field statistics of Baker and German (2004). For the Rainbow, Lucky Strike, and Menez Gwen sites, the application of a plume model based on the conservation of mass, heat, and momentum shows that the heat output computed by the model is only an estimation of the heat released by the focused part of the flow imputable to one single vent. Applied to the north AFZ venting site for which the height of the plume is not known precisely, the model does not allow us to discriminate between a Menez Gwen/Rainbow type of venting or a more focused vent complex such as the one observed at the TAG site (26°N).

  9. Development and evolution of detachment faulting along 50 km of the Mid-Atlantic Ridge near 16.5°N

    NASA Astrophysics Data System (ADS)

    Smith, Deborah K.; Schouten, Hans; Dick, Henry J. B.; Cann, Johnson R.; Salters, Vincent; Marschall, Horst R.; Ji, Fuwu; Yoerger, Dana; Sanfilippo, Alessio; Parnell-Turner, Ross; Palmiotto, Camilla; Zheleznov, Alexei; Bai, Hailong; Junkin, Will; Urann, Ben; Dick, Spencer; Sulanowska, Margaret; Lemmond, Peter; Curry, Scott

    2014-12-01

    multifaceted study of the slow spreading Mid-Atlantic Ridge (MAR) at 16.5°N provides new insights into detachment faulting and its evolution through time. The survey included regional multibeam bathymetry mapping, high-resolution mapping using AUV Sentry, seafloor imaging using the TowCam system, and an extensive rock-dredging program. At different times, detachment faulting was active along ˜50 km of the western flank of the study area, and may have dominated spreading on that flank for the last 5 Ma. Detachment morphologies vary and include a classic corrugated massif, noncorrugated massifs, and back-tilted ridges marking detachment breakaways. High-resolution Sentry data reveal a new detachment morphology; a low-angle, irregular surface in the regional bathymetry is shown to be a finely corrugated detachment surface (corrugation wavelength of only tens of meters and relief of just a few meters). Multiscale corrugations are observed 2-3 km from the detachment breakaway suggesting that they formed in the brittle layer, perhaps by anastomosing faults. The thin wedge of hanging wall lavas that covers a low-angle (6°) detachment footwall near its termination are intensely faulted and fissured; this deformation may be enhanced by the low angle of the emerging footwall. Active detachment faulting currently is limited to the western side of the rift valley. Nonetheless, detachment fault morphologies also are present over a large portion of the eastern flank on crust >2 Ma, indicating that within the last 5 Ma parts of the ridge axis have experienced periods of two-sided detachment faulting.

  10. Hydrographic and ecologic implications of foraminiferal stable isotopic response across the U.S. mid-Atlantic continental shelf during the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Makarova, Maria; Wright, James D.; Miller, Kenneth G.; Babila, Tali L.; Rosenthal, Yair; Park, Jill I.

    2017-01-01

    We present new δ13C and δ18O records of surface (Morozovella and Acarinina) and thermocline dwelling (Subbotina) planktonic foraminifera and benthic foraminifera (Gavelinella, Cibicidoides, and Anomalinoides) during the Paleocene-Eocene Thermal Maximum (PETM) from Millville, New Jersey, and compare them with three other sites located along a paleoshelf transect from the U.S. mid-Atlantic coastal plain. Our analyses show different isotopic responses during the PETM in surface versus thermocline and benthic species. Whereas all taxa record a 3.6-4.0‰ δ13C decrease associated with the carbon isotope excursion, thermocline dwellers and benthic foraminifera show larger δ18O decreases compared to surface dwellers. We consider two scenarios that can explain the observed isotopic records: (1) a change in the water column structure and (2) a change in habitat or calcification season of the surface dwellers due to environmental stress (e.g., warming, ocean acidification, surface freshening, and/or eutrophication). In the first scenario, persistent warming during the PETM would have propagated heat into deeper layers and created a more homogenous water column with a thicker warm mixed layer and deeper, more gradual thermocline. We attribute the hydrographic change to decreased meridional thermal gradients, consistent with models that predict polar amplification. The second scenario assumes that environmental change was greater in the mixed layer forcing surface dwellers to descend into thermocline waters as a refuge or restrict their calcification to the colder seasons. Although both scenarios are plausible, similar δ13C responses recorded in surface, thermocline, and benthic foraminifera challenge mixed layer taxa migration.

  11. Multi-year ground-based observations of aerosol-cloud interactions in the Mid-Atlantic of the United States

    NASA Astrophysics Data System (ADS)

    Li, Siwei; Joseph, Everette; Min, Qilong; Yin, Bangsheng

    2017-02-01

    The U.S. Mid-Atlantic region experiences a wide variability of aerosol loading and frequent episodes of elevated anthropogenic aerosol loading associated with urban pollution conditions during summer months. In this study, multi-year ground-based observations (2006 to 2010) of aerosol and cloud properties from passive, active and in situ measurements at an atmospheric measurement field station in the Baltimore-Washington corridor operated by Howard University were analyzed to examine aerosol indirect effect on single-layer warm clouds including cloud optical depth (COD), liquid water path (LWP), cloud droplet effective radius (Re) and cloud droplet number concentration (Nd) in this region. A greater occurrence of polluted episodes and cloud cases with smaller Re (<7 μm) were found during the polluted year summers (2006, 2007 and 2008) than the clean year summers (2009 and 2010). The measurements of aerosol particulate matter with aerodynamic diameter≤2.5 μm (PM2.5) were used to represent the aerosol loading under cloudy conditions. Significant negative relationships between cloud droplet Re and PM2.5 were observed. Cloud cases were separated into clean and polluted groups based on the value of PM2.5. The cloud droplet Re was found proportional to LWP under clean conditions but weakly dependent on LWP under polluted conditions. The Nd was proportional to LWP under polluted condition but weakly dependent on LWP under clean conditions. Moreover, the effects of increasing fine aerosol particles on modifying cloud microphysical properties were found more significant under large LWP than small LWP in this region.

  12. The role of pelagic swarm fish (Myctophidae: Teleostei) in the oceanic life cycle of Anisakis sibling species at the Mid-Atlantic Ridge, Central Atlantic.

    PubMed

    Klimpel, Sven; Kellermanns, Esra; Palm, Harry W

    2008-12-01

    First information is provided on the parasitation and feeding ecology of the myctophid fish species Myctophum punctatum and Notoscopelus kroyeri from the Mid-Atlantic Ridge (MAR), Central Atlantic. Four different parasite species were found in both fish with a similar high prevalence and intensity of infestation. The digeneans Gonocerca phycidis and Lethadena sp. were isolated as adults from the stomach, larval tetraphyllidean cestodes (Scolex pleuronectis) from the intestine, and genetically identified larval anisakid nematodes of Anisakis simplex (s.s.) from the body cavity. No further Anisakis sibling species could be identified. Both myctophids had small pelagic crustaceans, mainly copepods and hyperiids, within their stomach contents. Ostracods, euphausiids, decapods, and amphipods were minor food components, demonstrating the pelagic environment for both fish. The recorded parasites including the anisakid A. simplex (s.s.) perform pelagic life cycles within the region, benefiting from extensive diurnal vertical migrations of their fish hosts. Comparison of the host range among the anisakis sibling species suggests that the A. simplex complex has low host specificity, infecting toothed and baleen whales on their extensive oceanic migrations. This contrasts the Anisakis physeteris complex that is restricted to toothed whales of the families Kogiidae and Physeteridae. Specificity in the teleost intermediate hosts for both complexes seems to be low, and sympatric occurrence of different siblings within the same intermediate hosts is likely. Myctophid swarm fish as important copepod feeders at the MAR significantly contribute to the oceanic anisakid nematode life cycle, especially considering the 100% prevalence and high intensity of infestation. Further genetic identification of Anisakis nematodes is needed in order to understand the sibling species distribution, along the MAR and within other oceanic environments.

  13. Yamadazyma barbieri f.a. sp. nov., an ascomycetous anamorphic yeast isolated from a Mid-Atlantic Ridge hydrothermal site (-2300 m) and marine coastal waters.

    PubMed

    Burgaud, Gaëtan; Coton, Monika; Jacques, Noémie; Debaets, Stella; Maciel, Natália O P; Rosa, Carlos A; Gadanho, Mário; Sampaio, José Paulo; Casaregola, Serge

    2016-09-01

    Two yeast strains that are members of the same species were isolated from different marine habitats, i.e. one from Mid-Atlantic Ridge ocean water samples located in the direct vicinity of black smokers near the Rainbow deep-sea hydrothermal vent and one from Brazilian marine water samples off the Ipanema beach. Strains CLIB 1964T and CLIB 1965 are anamorphic ascomycetous yeasts affiliated to the Yamadazyma clade of Saccharomycetales. Interestingly, these strains were phylogenetically and distinctly positioned into a group of species comprising all species of the genus Yamadazyma isolated from marine habitats including deep-sea hydrothermal vents, i.e.Candida atmosphaerica,C. spencermartinsiae,C. atlantica,C. oceani and C. taylorii. These strains differed significantly in their D1/D2 domain sequences of the LSU rRNA gene from the closely related species mentioned above, by 2.6, 3.0, 3.4, 3.8 and 6.0 %, respectively. Internal transcribed spacer region sequence divergence was also significant and corresponded to 4.6, 4.7, 4.7, 12.0 and 24.7 % with C. atlantica,C. atmosphaerica, C. spencermartinsiae,C. oceani and C. taylorii, respectively. Phenotypically, strains CLIB 1964T and CLIB 1965 could be distinguished from closely related species by their inability to assimilate l-sorbose. CLIB 1964T (=CBS 14301T=UBOCC-A-214001T) is the designated type strain for Yamadazyma barbieri sp. nov. The MycoBank number is MB 815884.

  14. Structural Iron (II) of Basaltic Glass as an Energy Source for Zetaproteobacteria in an Abyssal Plain Environment, Off the Mid Atlantic Ridge.

    PubMed

    Henri, Pauline A; Rommevaux-Jestin, Céline; Lesongeur, Françoise; Mumford, Adam; Emerson, David; Godfroy, Anne; Ménez, Bénédicte

    2015-01-01

    To explore the capability of basaltic glass to support the growth of chemosynthetic microorganisms, complementary in situ and in vitro colonization experiments were performed. Microbial colonizers containing synthetic tholeitic basaltic glasses, either enriched in reduced or oxidized iron, were deployed off-axis from the Mid Atlantic Ridge on surface sediments of the abyssal plain (35°N; 29°W). In situ microbial colonization was assessed by sequencing of the 16S rRNA gene and basaltic glass alteration was characterized using Scanning Electron Microscopy, micro-X-ray Absorption Near Edge Structure at the Fe-K-edge and Raman microspectroscopy. The colonized surface of the reduced basaltic glass was covered by a rind of alteration made of iron-oxides trapped in a palagonite-like structure with thicknesses up to 150 μm. The relative abundance of the associated microbial community was dominated (39% of all reads) by a single operational taxonomic unit (OTU) that shared 92% identity with the iron-oxidizer Mariprofundus ferrooxydans PV-1. Conversely, the oxidized basaltic glass showed the absence of iron-oxides enriched surface deposits and correspondingly there was a lack of known iron-oxidizing bacteria in the inventoried diversity. In vitro, a similar reduced basaltic glass was incubated in artificial seawater with a pure culture of the iron-oxidizing M. ferrooxydans DIS-1 for 2 weeks, without any additional nutrients or minerals. Confocal Laser Scanning Microscopy revealed that the glass surface was covered by twisted stalks characteristic of this iron-oxidizing Zetaproteobacteria. This result supported findings of the in situ experiments indicating that the Fe(II) present in the basalt was the energy source for the growth of representatives of Zetaproteobacteria in both the abyssal plain and the in vitro experiment. In accordance, the surface alteration rind observed on the reduced basaltic glass incubated in situ could at least partly result from their activity.

  15. Short-term microbial and physico-chemical variability in low-temperature hydrothermal fluids near 5 degrees S on the Mid-Atlantic Ridge.

    PubMed

    Perner, Mirjam; Bach, Wolfgang; Hentscher, Michael; Koschinsky, Andrea; Garbe-Schönberg, Dieter; Streit, Wolfgang R; Strauss, Harald

    2009-10-01

    This study examines the representativeness of low-temperature hydrothermal fluid samples with respect to their chemical and microbiological characteristics. Within this scope, we investigated short-term temporal chemical and microbial variability of the hydrothermal fluids. For this purpose we collected three fluid samples consecutively from the same spot at the Clueless field near 5 degrees S on the southern Mid-Atlantic Ridge over a period of 50 min. During sampling, the temperature was monitored online. We measured fluid chemical parameters, characterized microbial community compositions and used statistical analyses to determine significant differences between the samples. Overall, the three fluid samples are more closely related to each other than to any other tested habitat. Therefore, on a broad scale, the three collected fluid samples can be regarded as habitat representatives. However, small differences are apparent between all samples. One of the Clueless samples even displayed significant differences (P-value < 0.01) to the other two Clueless samples. Our data suggest that the observed variations in fluid chemical and microbial compositions are not reflecting sampling artefacts but are related to short-term fluid variability due to dynamic subseafloor fluid mixing. Recorded temporal changes in fact reflect spatial heterogeneity found in the subsurface as the fluid flows through distinctive pathways. While conservative elements (Cl, Si, Na and K) indicate variable degrees of fluid-seawater mixing, reactive components, including Fe(II), O(2) and H(2)S, show that chemical and microbial reactions within the mixing zone further modify the emanating fluids on short-time scales. Fluids entrain microorganisms, which modify the chemical microenvironment within the subsurface biotopes. This is the first study focusing on short-term microbial variability linked to chemical changes in hydrothermal fluids.

  16. Microbial CO(2) fixation and sulfur cycling associated with low-temperature emissions at the Lilliput hydrothermal field, southern Mid-Atlantic Ridge (9 degrees S).

    PubMed

    Perner, Mirjam; Seifert, Richard; Weber, Stefan; Koschinsky, Andrea; Schmidt, Katja; Strauss, Harald; Peters, Marc; Haase, Karsten; Imhoff, Johannes F

    2007-05-01

    Lilliput was discovered in 2005 as the southernmost known hydrothermal field along the Mid-Atlantic Ridge. It is exceptional in that it lacks high-temperature venting probably because of a thickened crust. The absence of thermophilic and hyperthermophilic prokaryotes in emissions supports the argument against the presence of a hot subsurface at Lilliput, as is typically suggested for diffuse emissions from areas of high-temperature venting. The high phylogenetic diversity and novelty of bacteria observed could be because of the low-temperature influence, the distinct location of the hydrothermal field or the Bathymodiolus assemblages covering the sites of discharge. The low-temperature fluids at the Lilliput are characterized by lowered pH and slightly elevated hydrogen (16 nM) and methane ( approximately 2.6 microM) contents compared with ambient seawater. No typical hydrogen and methane oxidizing prokaryotes were detected. The higher diversity of reverse tricarboxylic acid genes and the form II RubisCO genes of the Calvin Benson-Bassham (CBB) cycle compared with the form I RubisCO genes of the CBB cycle suggests that the chemoautotrophic community is better adapted to low oxygen concentrations. Thiomicrospira spp. and Epsilonproteobacteria dominated the autotrophic community. Sulfide is the most abundant inorganic energy source (0.5 mM). Diverse bacteria were associated with sulfur cycling, including Gamma-, Delta- and Epsilonproteobacteria, with the latter being the most abundant bacteria according to fluorescence in situ hybridization. With members of various Candidate Divisions constituting for 25% of clone library sequences we suggest that their role in vent ecosystems might be more important than previously assumed and propose potential mechanisms they might be involved in at the Lilliput hydrothermal field.

  17. High variability in spatial and temporal size-based trophodynamics of deep-sea fishes from the Mid-Atlantic Ridge elucidated by stable isotopes

    NASA Astrophysics Data System (ADS)

    Reid, William D. K.; Sweeting, Christopher J.; Wigham, Ben D.; McGill, Rona A. R.; Polunin, Nicholas V. C.

    2013-12-01

    Demersal fish play an important role in the deep-sea ecosystem by acting as a link to mobile food in the water column, consuming benthic fauna, breaking down large food parcels and dispersing organic matter over large areas. Poor diet resolution from stomach content analysis often impairs the ability to assess differences in inter- and intra-population trophodynamics and therefore understand resource partitioning among deep-sea fishes. Antimora rostrata (predator-scavenger), Coryphaenoides armatus (predator-scavenger), Coryphaenoides brevibarbis (predator) and Halosauropsis macrochir (predator) were collected from 3 stations on the Mid-Atlantic Ridge (MAR) in 2007 and 2009 to investigate trophic ecology using δ13C and δ15N. Variability in lipid-normalised δ13C (δ13Cn) and δ15N was explained by body length in all species but slope and significance of the isotope-length relationships varied both temporally and spatially. δ15N increases with length were observed in A. rostrata at all stations, C. brevibarbis and H. macrochir at one or more stations but were absent in C. armatus. δ13Cn increased with length in A. rostrata but the slope of δ13Cn-length relationships varied spatially and temporally in C. armatus and C. brevibarbis. The co-occurring δ13Cn and δ15N size-based trends in A. rostrata and H. macrochir suggested that size-based trends were a result of increasing trophic position. In C. armatus and C. brevibarbis the isotope-length trends were difficult to distinguish among trophic position increases, shifts in resource use i.e. benthic to pelagic or internal physiology. However, the overall strength, direction and significance of isotope-length trends varied temporally and spatially which suggested varying degrees of overlap in trophic ecology and feeding plasticity among these species.

  18. Public support for a sugar-sweetened beverage tax and pro-tax messages in a Mid-Atlantic US state

    PubMed Central

    Donaldson, Elisabeth A; Cohen, Joanna E; Rutkow, Lainie; Villanti, Andrea C; Kanarek, Norma F; Barry, Colleen L

    2015-01-01

    Objective To examine the characteristics of supporters and opponents of a sugar-sweetened beverage (SSB) tax and to identify pro-tax messages that resonate with the public. Design A survey was administered by telephone in February 2013 to assess public opinion about a penny-per-ounce tax on SSB. Support was also examined for SSB consumption reduction and pro-tax messages. Individual characteristics including sociodemographics, political affiliation, SSB consumption behaviours and beliefs were explored as predictors of support using logistic regression. Setting A representative sample of voters was recruited from a Mid-Atlantic US state. Subjects The sample included 1000 registered voters. Results Findings indicate considerable support (50 %) for an SSB tax. Support was stronger among Democrats, those who believe SSB are a major cause of childhood obesity and those who believe childhood obesity warrants a societal intervention. Belief that a tax would be effective in lowering obesity rates was associated with support for the tax and pro-tax messages. Respondents reporting that a health-care provider had recommended they lose weight were less convinced by pro-tax messages. Women, Independents and those concerned about childhood obesity were more convinced by the SSB reduction messages. Overall, the most popular messages focused on the importance of reducing consumption among children without mentioning the tax. Conclusions Understanding who supports and opposes SSB tax measures can assist advocates in developing strategies to maximize support for this type of intervention. Messages that focus on the effect of consumption on children may be useful in framing the discussion around SSB tax proposals. PMID:25430945

  19. Hydrothermal Activity on the Southern Mid-Atlantic Ridge: Tectonically- and Volcanically-Hosted High Temperature Venting at 2-7 Degrees S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Parson, L. M.; Murton, B. J.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Prien, R. D.; Ramirez-Llodra, E. Z.; Shank, T. M.; Yoerger, D. R.; Jakuba, M.; Bradley, A. M.; Baker, E. T.; Nakamura, K.

    2005-12-01

    We have conducted a systematic investigation for hydrothermal activity along the southern Mid-Atlantic Ridge, 2°30-6°50 S. Our initial approach was to use a combination of multi-beam swath mapping, deep-tow sidescan sonar imaging and water column plume-detection using MAPRs and CTD-rosette system to locate new sites of hydrothermal activity immediately south of the Romanche and Chain Fracture zones. We wanted to test whether these geologic features represent a significant barrier to gene-flow along-axis away from northern MAR vent ecosystems. During the first leg of our research cruise (RRS Charles Darwin cruise CD169, Feb-Mar 2005) we used this approach to identify two hydrothermally active regions, one in a non-transform discontinuity near 4°S and the other in a segment centre characterised by very fresh sheet-flows near 5°S. During Leg 2 we returned to the second of these areas and deployed ABE, WHOI's autonomous underwater vehicle, in a three-phase strategy to prospect for, locate, and image new hydrothermal fields. During Phase 1 two discrete target areas were located ca. 1km apart along strike within the segment centre. During Phase 2 these two areas were each mapped in detail using an SM2000 system while in situ optical back scatter, Eh, temperature, Mn and Fe(II) sensors were used to confirm the interception of buoyant hydrothermal plumes rising from the seafloor. Finally we redeployed ABE (Phase 3) to collect photo-mosaics of each of two new vent-areas whilst simultaneously sampling their buoyant plumes by CTD-rosette for TDMn, Fe and CH4 analyses.

  20. Heterogeneous and asymmetric crustal accretion: New constraints from multibeam bathymetry and potential field data from the Rainbow area of the Mid-Atlantic Ridge (36°15'N)

    NASA Astrophysics Data System (ADS)

    Paulatto, Michele; Canales, Juan Pablo; Dunn, Robert A.; Sohn, Robert A.

    2015-09-01

    At slow-spreading mid-ocean ridges, crustal accretion style can vary significantly along and across ridge segments. In magma-poor regions, seafloor spreading can be accommodated largely by tectonic processes, however, the internal structure and formation mechanism of such highly tectonized crust are not fully understood. We analyze multibeam bathymetry and potential field data from the Rainbow area of the Mid-Atlantic Ridge (35°40'N-36°40'N), a section of the ridge that shows diverse accretion styles. We identify volcanic, tectonized and sedimented terrain and measure exposed fault area to estimate the tectonic strain, T, and the fraction of magmatic accretion, M. Estimated T values range from 0.2-0.4 on ridge segments to 0.6-0.8 at the Rainbow nontransform discontinuity (NTD). At segment ends T is asymmetric, reflecting asymmetries in accretion rate, topography and faulting between inside and outside offset corners. Detachment faults have formed preferentially at inside corners, where tectonic strain is higher. We identify at least two oceanic core complexes on the fossil trace of the NTD, in addition to the Rainbow massif, which occupies the offset today. A gravity high and low magnetization suggest that the Rainbow massif, which hosts a high-temperature hydrothermal system, was uplifted by a west dipping detachment fault. Asymmetric plate ages indicate localization of tectonic strain at the inside corners and migration of the detachment toward and across the ridge axis, which may have caused emplacement of magma into the footwall. Hydrothermal circulation and heat extraction is possibly favored by increased permeability generated by fracturing of the footwall and deep-penetrating second-generation faults.