Search

Search Results

• 61. [Article] Meridional fluxes of dissolved silicon in the southern ocean

  Meridional fluxes of silica across the Southern Ocean polar front are attributed to two different processes which generally act in opposite directions. Equatorward low frequency fluxes of silica inferred ...

  Citation × Citation Citation Abstract Copy Title: Meridional fluxes of dissolved silicon in the southern ocean Author: Jennings, Joe C. Meridional fluxes of silica across the Southern Ocean polar front are attributed to two different processes which generally act in opposite directions. Equatorward low frequency fluxes of silica inferred from ISOS current meter data in the Drake Passage are approximately balanced by poleward meridional diffusion of silica along surfaces of constant potential density. Considering only these two processes, a balance of the silicon budget in the Circumpolar Current can be achieved. The poleward diffusive flux along shoaling density surfaces may uaintain the high silicon concentrations characteristic of Antarctic surface waters south of the frontal zone. Title: Meridional fluxes of dissolved silicon in the southern ocean Author: Jennings, Joe C. Meridional fluxes of silica across the Southern Ocean polar front are attributed to two different processes which generally act in opposite directions. Equatorward low frequency fluxes of silica inferred from ISOS current meter data in the Drake Passage are approximately balanced by poleward meridional diffusion of silica along surfaces of constant potential density. Considering only these two processes, a balance of the silicon budget in the Circumpolar Current can be achieved. The poleward diffusive flux along shoaling density surfaces may uaintain the high silicon concentrations characteristic of Antarctic surface waters south of the frontal zone. Close

• 62. [Article] Flow-Solute : A Tool for Exploring the Effects of Nitrogen Management in Alternative Future Scenarios

  Surface water quality is a growing concern in the Willamette River Basin and elsewhere. The region's growing population is dependent on the availability of clean water for drinking water, irrigation, wastewater ...

  Citation × Citation Citation Abstract Copy Title: Flow-Solute : A Tool for Exploring the Effects of Nitrogen Management in Alternative Future Scenarios Author: Wentworth, Andrew Michael Surface water quality is a growing concern in the Willamette River Basin and elsewhere. The region's growing population is dependent on the availability of clean water for drinking water, irrigation, wastewater dilution, and wildlife habitat. Watershed management to produce economic goods and environmental services requires an understanding of basic hydrologic processes in addition to tools that accurately represent the interactions between human activity, biophysical processes, and climate change. In this study we developed a plug-in for the Envision modeling framework to explore where interactions between climate change and human activities are most likely to result in impaired water quality. This study has two primary objectives. The first is to develop a plug-in for Envision that can accurately simulate the effect of agricultural practices (e.g. fertilizer application rates and timing, crop selection, etc.) on the system's nitrogen budget. The second objective is to explore the landscape response to three future scenarios of changing climate, agricultural practices, and conservation actions as measured by nitrogen loading to surface waters in the Calapooia River Basin. The model we developed for this study was created by integrating algorithms from two widely used models: a conceptual hydrologic model and a nitrogen dynamics model. A number of changes were required to merge the two models and the accuracy of streamflow predictions suffered. The result of the scenario analysis was consistent with our expectations beginning the study: warmer and wetter climate scenarios were associated with higher annual nitrogen export rates, and policies that resulted in lower fertilizer application led to a decrease in annual nitrogen export rates. Title: Flow-Solute : A Tool for Exploring the Effects of Nitrogen Management in Alternative Future Scenarios Author: Wentworth, Andrew Michael Surface water quality is a growing concern in the Willamette River Basin and elsewhere. The region's growing population is dependent on the availability of clean water for drinking water, irrigation, wastewater dilution, and wildlife habitat. Watershed management to produce economic goods and environmental services requires an understanding of basic hydrologic processes in addition to tools that accurately represent the interactions between human activity, biophysical processes, and climate change. In this study we developed a plug-in for the Envision modeling framework to explore where interactions between climate change and human activities are most likely to result in impaired water quality. This study has two primary objectives. The first is to develop a plug-in for Envision that can accurately simulate the effect of agricultural practices (e.g. fertilizer application rates and timing, crop selection, etc.) on the system's nitrogen budget. The second objective is to explore the landscape response to three future scenarios of changing climate, agricultural practices, and conservation actions as measured by nitrogen loading to surface waters in the Calapooia River Basin. The model we developed for this study was created by integrating algorithms from two widely used models: a conceptual hydrologic model and a nitrogen dynamics model. A number of changes were required to merge the two models and the accuracy of streamflow predictions suffered. The result of the scenario analysis was consistent with our expectations beginning the study: warmer and wetter climate scenarios were associated with higher annual nitrogen export rates, and policies that resulted in lower fertilizer application led to a decrease in annual nitrogen export rates. Close

• 63. [Article] Primary productivity in the southeast Pacific Ocean : effects of enhanced ultraviolet-B radiation

  Anthropogenic releases of trace gases into the atmosphere are causing a decrease in stratospheric ozone concentrations and a subsequent increase in solar ultraviolet-B (UV-B)(280-320 nm) radiation reaching ...

  Citation × Citation Citation Abstract Copy Title: Primary productivity in the southeast Pacific Ocean : effects of enhanced ultraviolet-B radiation Author: Behrenfeld, Mike J. Anthropogenic releases of trace gases into the atmosphere are causing a decrease in stratospheric ozone concentrations and a subsequent increase in solar ultraviolet-B (UV-B)(280-320 nm) radiation reaching the earth's surface. The objective of this study was to determine the acute effects of enhanced UV-B radiation on the primary production of natural marine phytoplankton assemblages sampled over a wide latitudinal gradient and incubated under ambient levels of photosynthetically active radiation (PAR). Samples were collected approximately every 2 to 4° latitude in the southeast Pacific. Primary production was measured using the carbon-14 light and dark bottle technique. Fluorescent sunlamps were used to enhance the dose of UV-B radiation above ambient. Samples were maintained at ambient surface water temperature in a flow-through incubation tank. Enhanced UV-B radiation caused a significant mean decrease of 34% in surface water primary production. Decreases in primary production increased with and with increasing assimilation efficiencies. Results indicate that predicted increases in ambient solar UV-B radiation resulting from stratospheric ozone depletion could result in mean annual decreases of near-surface oceanic primary production of less than 1% near the equator to more than 32% at high southern latitudes. Title: Primary productivity in the southeast Pacific Ocean : effects of enhanced ultraviolet-B radiation Author: Behrenfeld, Mike J. Anthropogenic releases of trace gases into the atmosphere are causing a decrease in stratospheric ozone concentrations and a subsequent increase in solar ultraviolet-B (UV-B)(280-320 nm) radiation reaching the earth's surface. The objective of this study was to determine the acute effects of enhanced UV-B radiation on the primary production of natural marine phytoplankton assemblages sampled over a wide latitudinal gradient and incubated under ambient levels of photosynthetically active radiation (PAR). Samples were collected approximately every 2 to 4° latitude in the southeast Pacific. Primary production was measured using the carbon-14 light and dark bottle technique. Fluorescent sunlamps were used to enhance the dose of UV-B radiation above ambient. Samples were maintained at ambient surface water temperature in a flow-through incubation tank. Enhanced UV-B radiation caused a significant mean decrease of 34% in surface water primary production. Decreases in primary production increased with and with increasing assimilation efficiencies. Results indicate that predicted increases in ambient solar UV-B radiation resulting from stratospheric ozone depletion could result in mean annual decreases of near-surface oceanic primary production of less than 1% near the equator to more than 32% at high southern latitudes. Close

• 64. [Article] Distribution and variability of iron input to Oregon coastal waters during the upwelling season

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Distribution and variability of iron input to Oregon coastal waters during the upwelling season Author: Schwartz, Roseanne, Hales, Burke, Chase, Zanna, Cowles, Timothy J., van Geen, Alexander Copyrighted by American Geophysical Union. Title: Distribution and variability of iron input to Oregon coastal waters during the upwelling season Author: Schwartz, Roseanne, Hales, Burke, Chase, Zanna, Cowles, Timothy J., van Geen, Alexander Copyrighted by American Geophysical Union. Close

• 65. [Article] Heat and mass balances of the South Atlantic Ocean calculated from a numerical model

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Heat and mass balances of the South Atlantic Ocean calculated from a numerical model Author: Matano, Ricardo P., Philander, S. George H. copyrighted by American Geophysical Union Title: Heat and mass balances of the South Atlantic Ocean calculated from a numerical model Author: Matano, Ricardo P., Philander, S. George H. copyrighted by American Geophysical Union Close

• 66. [Article] Depth Distribution of Oceanic Shrimps (Decapoda ; Natantia) off Oregon

  Sixteen species of oceanic shrimps, seven Penaeidea and nine Caridea, appeared in 244 collections made within the upper 1500 m at one station in the northeast Pacific off Oregon. Most of the species were ...

  Citation × Citation Citation Abstract Copy Title: Depth Distribution of Oceanic Shrimps (Decapoda ; Natantia) off Oregon Author: Forss, Carl A., Pearcy, William G. Sixteen species of oceanic shrimps, seven Penaeidea and nine Caridea, appeared in 244 collections made within the upper 1500 m at one station in the northeast Pacific off Oregon. Most of the species were primarily mesopelagic in distribution. The most abundant species, Sergestes similis, was the only shrimp common in epipelagic waters at night and the only species clearly demonstrating did vertical migrations. Night catches exceeded day catches in near-surface waters, while day catches exceeded night catches at mid-depths. Sergestes similis migrated into the upper 50 m at night and on one occasion was collected at the surface. Title: Depth Distribution of Oceanic Shrimps (Decapoda ; Natantia) off Oregon Author: Forss, Carl A., Pearcy, William G. Sixteen species of oceanic shrimps, seven Penaeidea and nine Caridea, appeared in 244 collections made within the upper 1500 m at one station in the northeast Pacific off Oregon. Most of the species were primarily mesopelagic in distribution. The most abundant species, Sergestes similis, was the only shrimp common in epipelagic waters at night and the only species clearly demonstrating did vertical migrations. Night catches exceeded day catches in near-surface waters, while day catches exceeded night catches at mid-depths. Sergestes similis migrated into the upper 50 m at night and on one occasion was collected at the surface. Close

• 67. [Article] Waves and fractals

  The goal of this research project is to determine the fractal nature, if any, which surface water waves exhibit when viewed on a microscopic scale. Due to the relatively recent development of this area ...

  Citation × Citation Citation Abstract Copy Title: Waves and fractals Author: Gilliland, Crystal L. The goal of this research project is to determine the fractal nature, if any, which surface water waves exhibit when viewed on a microscopic scale. Due to the relatively recent development of this area of mathematics, a brief introduction to the study of fractal geometry, as well as several examples of fractals, are included in this paper. From that point, this paper addresses the specific situation of a surface wave as it nears the breaking point and attempts to detect the fractal structure of a wave at this given point when viewed on a microscopic scale. This is done from both a physical standpoint based on observations at the Hinsdale Wave Facility at Oregon State University and at Cape Perpetua, Oregon on the Pacific Coast, and from a theoretical standpoint based on a spring model. Title: Waves and fractals Author: Gilliland, Crystal L. The goal of this research project is to determine the fractal nature, if any, which surface water waves exhibit when viewed on a microscopic scale. Due to the relatively recent development of this area of mathematics, a brief introduction to the study of fractal geometry, as well as several examples of fractals, are included in this paper. From that point, this paper addresses the specific situation of a surface wave as it nears the breaking point and attempts to detect the fractal structure of a wave at this given point when viewed on a microscopic scale. This is done from both a physical standpoint based on observations at the Hinsdale Wave Facility at Oregon State University and at Cape Perpetua, Oregon on the Pacific Coast, and from a theoretical standpoint based on a spring model. Close

• 68. [Article] The changing carbon cycle in the Southern Ocean

  This is the publisher’s final pdf. The published article is copyrighted by The Oceanography Society and can be found at: www.tos.org/.

  Citation × Citation Citation Abstract Copy Title: The changing carbon cycle in the Southern Ocean Author: Takahashi, Taro, Newberger, Timothy, Goddard, John G., Chipman, David W., Sweeney, Colm, Hales, Burke, Sutherland, Stewart C., Iannuzzi, Richard A. This is the publisher’s final pdf. The published article is copyrighted by The Oceanography Society and can be found at: www.tos.org/. Title: The changing carbon cycle in the Southern Ocean Author: Takahashi, Taro, Newberger, Timothy, Goddard, John G., Chipman, David W., Sweeney, Colm, Hales, Burke, Sutherland, Stewart C., Iannuzzi, Richard A. This is the publisher’s final pdf. The published article is copyrighted by The Oceanography Society and can be found at: www.tos.org/. Close

• 69. [Article] Quantifying physical habitat in wadeable streams : surface waters

  We describe concepts, rationale, and analytical procedures for characterizing physical habitat in wadeable streams based on raw data generated from methods similar or equal to those of Kaufmann and Robison ...

  Citation × Citation Citation Abstract Copy Title: Quantifying physical habitat in wadeable streams : surface waters Author: Robison, E. George, Seeliger, Curt, Levine, Paul, Peck, David V., Kaufmann, Phillip R. We describe concepts, rationale, and analytical procedures for characterizing physical habitat in wadeable streams based on raw data generated from methods similar or equal to those of Kaufmann and Robison (in PB99-139156). We provide guidance for calculating measures or indices of stream size and gradient, sinuosity, substrate size and stability, habitat complexity and cover, woody debris size and abundance, residual pool dimensions and frequency, riparian vegetation cover and structure, anthropogenic disturbances, and channel-riparian interaction. We evaluated sampling precision of field habitat survey methods employed by EMAP in several hundred streams in Oregon and the Mid-Atlantic region, comparing variance among streams ('signals') with variance between repeat stream visits (measurement 'noise'). The final measure of the utility of a habitat approach is whether it is useful for interpreting controls on biota or impacts of human activity. Title: Quantifying physical habitat in wadeable streams : surface waters Author: Robison, E. George, Seeliger, Curt, Levine, Paul, Peck, David V., Kaufmann, Phillip R. We describe concepts, rationale, and analytical procedures for characterizing physical habitat in wadeable streams based on raw data generated from methods similar or equal to those of Kaufmann and Robison (in PB99-139156). We provide guidance for calculating measures or indices of stream size and gradient, sinuosity, substrate size and stability, habitat complexity and cover, woody debris size and abundance, residual pool dimensions and frequency, riparian vegetation cover and structure, anthropogenic disturbances, and channel-riparian interaction. We evaluated sampling precision of field habitat survey methods employed by EMAP in several hundred streams in Oregon and the Mid-Atlantic region, comparing variance among streams ('signals') with variance between repeat stream visits (measurement 'noise'). The final measure of the utility of a habitat approach is whether it is useful for interpreting controls on biota or impacts of human activity. Close

• 70. [Article] Cold halocline, increased nutrients and higher chlorophyll off Oregon in 2002

  Observed changes in the nutrient levels in the halocline of the California Current during 2002 indicated a natural eutrophication that was accompanied by increased chlorophyll and oxygen in surface water. ...

  Citation × Citation Citation Abstract Copy Title: Cold halocline, increased nutrients and higher chlorophyll off Oregon in 2002 Author: Wheeler, Patricia A., Huyer, Adriana, 1945-, Fleischbein, Jane Observed changes in the nutrient levels in the halocline of the California Current during 2002 indicated a natural eutrophication that was accompanied by increased chlorophyll and oxygen in surface water. Decreased oxygen in the lower water column over the shelf indicated that much of the phytoplankton production was respired rather than passed on to higher trophic levels. In 2002 the halocline water was >1ºC colder than usual and 0.5ºC colder than any previous observation. Four transect lines off the coast of Oregon show a 50% increase in nitrate, phosphate and silicate at 33 psu in 2002 compared to 1998–2001. The increase in nutrients resulted in a 2-fold increase in chlorophyll standing stocks during the summer of 2002 compared with the preceding four years. A significant portion of the increased production was subsequently respired resulting in low oxygen water over the shelf. Title: Cold halocline, increased nutrients and higher chlorophyll off Oregon in 2002 Author: Wheeler, Patricia A., Huyer, Adriana, 1945-, Fleischbein, Jane Observed changes in the nutrient levels in the halocline of the California Current during 2002 indicated a natural eutrophication that was accompanied by increased chlorophyll and oxygen in surface water. Decreased oxygen in the lower water column over the shelf indicated that much of the phytoplankton production was respired rather than passed on to higher trophic levels. In 2002 the halocline water was >1ºC colder than usual and 0.5ºC colder than any previous observation. Four transect lines off the coast of Oregon show a 50% increase in nitrate, phosphate and silicate at 33 psu in 2002 compared to 1998–2001. The increase in nutrients resulted in a 2-fold increase in chlorophyll standing stocks during the summer of 2002 compared with the preceding four years. A significant portion of the increased production was subsequently respired resulting in low oxygen water over the shelf. Close