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Articles 11701 - 11730 of 14153

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Effects Of Predation On Two Species Of Stream-Dwelling Crayfish (Orconectes Marchandi And Cambarus Hubbsi) In Pool And Riffle Microhabitats, Heidi Dukat, Daniel D. Magoulick Jan 1999

Effects Of Predation On Two Species Of Stream-Dwelling Crayfish (Orconectes Marchandi And Cambarus Hubbsi) In Pool And Riffle Microhabitats, Heidi Dukat, Daniel D. Magoulick

Journal of the Arkansas Academy of Science

Community structure may be governed by many abiotic and biotic factors. Of the biotic factors, predation is often considered to be critical in structuring freshwater stream communities. In the Warm Fork of the Spring River, the crayfish Cambarus hubbsi is found mainly in riffles, whereas the crayfish Orconectes marchandi is found in high numbers in pools. We hypothesized that predation, mainly by fish, is a factor causing this segregation. Higher predation rates for C. hubbsi than 0. marchandi in the pools and higher predation rates for 0. marchandi than C. hubbsi in the riffles were expected. A transplant tethering experiment …


Locating Napls In Ground Water Using Partitioning Fluorescent Dyes, A. Ghanem, J. Smith, M. Elzey, T. S. Soerens, M. A. Miah, G. Thoma Jan 1999

Locating Napls In Ground Water Using Partitioning Fluorescent Dyes, A. Ghanem, J. Smith, M. Elzey, T. S. Soerens, M. A. Miah, G. Thoma

Journal of the Arkansas Academy of Science

A major challenge in ground water remediation is locating nonaqueous phase liquids (NAPLs). Partitioning tracers can be used to identify NAPL sources between injection and extraction wells. NAPLs are only slightly soluble in water, pose a long-term source of groundwater contamination, and can be difficult to remove. The complexity of recovery processes requires the development of new technologies that guarantee cost effective methods for locating and quantifying NAPLs. Traditional methods like soil coring have been inefficient since they underestimate the quantity of NAPLs and are expensive. Partitioning tracer tests are some of the most recent methods developed for locating these …


A Spatial And Temporal Analysis Of Riparian Vegetation Along Satus Creek On The Yakama Indian Reservation, Kathryn Gellenbeck Jan 1999

A Spatial And Temporal Analysis Of Riparian Vegetation Along Satus Creek On The Yakama Indian Reservation, Kathryn Gellenbeck

All Master's Theses

Satus Creek provides critical habitat for the Yakima River Basin steelhead. A diverse community of riparian vegetation is important for healthy fish habitat; vegetation changes can affect shade, cover, channel structure, water quality, and food availability. The purpose of this thesis is to analyze and illustrate riparian vegetation change, both temporally and spatially, along three separate reaches of Satus Creek. A Geographic Information Systems approach was applied to assess the vegetation change by comparing plant species composition and density on 1949 and 1995 aerial photographs. The GIS approach allowed patterns and trends in the vegetation to be identified. In less …


Guide For Developing Integrated Aquatic Vegetation Management Plans In Oregon, Maribeth Gibbons, Mark Rosenkranz, Harry L. Gibbons, Mark Sytsma Jan 1999

Guide For Developing Integrated Aquatic Vegetation Management Plans In Oregon, Maribeth Gibbons, Mark Rosenkranz, Harry L. Gibbons, Mark Sytsma

Center for Lakes and Reservoirs Publications and Presentations

This manual focuses on controlling nuisance aquatic plants, occurring in Oregon lakes. To use this manual, it is necessary to distinguish between an aquatic plant problem, and a water quality enrichment problem that typically results in excessive algae production (See Box this page). The most serious type of aquatic plant problem is caused by invasion of a waterbody by a non-native species. Non-native weed invaders may flourish in suitable conditions and degrade habitat and other beneficial uses. The biology and ecology of weeds allows them to fluorish under a wide range of conditions. Nutrient enrichment is not a prerequisite for …


Salinity And Hydrology Of The Fence Road Catchment : A Focus Catchment Of The Blackwood Basin, Ben Whitfield Jan 1999

Salinity And Hydrology Of The Fence Road Catchment : A Focus Catchment Of The Blackwood Basin, Ben Whitfield

Resource management technical reports

It is the clearing of native vegetation and replacement with lower water-use annual crops and pastures that is responsible for the developing salinity problem. Traditional farming practices have led to increased recharge to the groundwater systems resulting in increased storage and/or greater areas or rates of discharge. Groundwater monitoring has revealed variable rates of rise throughout the Fence Road catchment, from static to 0.6 metres per year, in a period of average to below average rainfall.


Ocean Surface Maps From Blending Disparate Data Through Normal Mode Analysis, William John Schulz Jr. Jan 1999

Ocean Surface Maps From Blending Disparate Data Through Normal Mode Analysis, William John Schulz Jr.

OES Theses and Dissertations

Rapid environmental assessment is conducted using disparate data sources in the northwestern Gulf of Mexico. An overview of significant physical features in the Gulf highlights the complexities of the large and meso-scale circulations. Spectral analysis of high resolution current meter and drifter data reveals the significant forcing features detectable by readily available observing techniques. These observations are combined with boundary data extracted from the U.S. Navy's Modular Ocean Data Assimilation System (MODAS) through Normal Mode Analysis (NMA). The NMA blending process is described, and surface maps of velocity and convergence are produced. Using statistical and qualitative techniques, the NMA generated …


Comparison Of An Enzyme-Linked Immunosorbent Assay (Elisa) To Gas Chromatography (Gc) - Measurement Of Polychlorinated Biphenyls (Pcbs) In Selected Us Fish Extracts, James L. Zajicek, Donald E. Tillitt, Ted R. Schwartz, Christopher J. Schmitt, Robert O. Harrison Jan 1999

Comparison Of An Enzyme-Linked Immunosorbent Assay (Elisa) To Gas Chromatography (Gc) - Measurement Of Polychlorinated Biphenyls (Pcbs) In Selected Us Fish Extracts, James L. Zajicek, Donald E. Tillitt, Ted R. Schwartz, Christopher J. Schmitt, Robert O. Harrison

United States Geological Survey: Staff Publications

The analysis of PCBs in fish tissues by immunoassay methods was evaluated using fish collected from a US monitoring program, the National Contaminant Biomonitoring Program of the US Department of Interior, Fish and Wildlife Service. Selected composite whole fish samples, which represented widely varying concentrations and sources of PCBs, were extracted and subjected to congener PCB analysis by gas chromatography (GC) and total PCB analysis using an ELISA (ePCBs) calibrated against technical Aroclor 1248. PCB congener patterns in these fishes were different from the patterns found in commercial Aroclors or their combinations as demonstrated by principal component analysis of normalized …


Circulation, Vol. 6, No. 2, Center For Coastal Physical Oceanography, Old Dominion University Jan 1999

Circulation, Vol. 6, No. 2, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Winter 1999 issue of CCPO Circulation featuring article "Identifying Different Flow Constituents in Estuaries"


Frontogenesis In The North Pacific Oceanic Frontal Zones--A Numerical Simulation, Michael S. Dinniman, Michele M. Rienecker Jan 1999

Frontogenesis In The North Pacific Oceanic Frontal Zones--A Numerical Simulation, Michael S. Dinniman, Michele M. Rienecker

CCPO Publications

A primitive equation model [Geophysical Fluid Dynamics Laboratory's (GFDL's) MOM 2] with one degree horizontal resolution is used to simulate the seasonal cycle of frontogenesis in the subarctic frontal zone (SAFZ) and the subtropical frontal zone (STFZ) of the North Pacific Ocean. The SAFZ in the model contains deep (greater than 500 m in some places) regions with seasonally varying high gradients in temperature and salinity. The gradients generally weaken toward the east. The STFZ consists of a relatively shallow (less than 200 m in most places) region of high gradient in temperature that disappears in the summer/fall. The high …


Decadal Variabilities Of The Upper Layers Of The Subtropical North Atlantic: An Ocean Model Study, Tal Ezer Jan 1999

Decadal Variabilities Of The Upper Layers Of The Subtropical North Atlantic: An Ocean Model Study, Tal Ezer

CCPO Publications

Numerical simulations of the Atlantic Ocean during the period 1950 to 1989, using a sigma coordinate, free surface numerical model, show long-term variabilities in the upper ocean subtropical gyre similar to those obtained from observations. The simulations show how westward propagating planetary waves, originated in the eastern North Atlantic, affect interdecadal variabilities of ocean properties such as the Bermuda sea level, the Gulf Stream position and strength, and subsurface temperature anomalies in the western North Atlantic. Special attention is given to the dramatic sea level drop at Bermuda in the early 1970s, which is accompanied by cooling of subsurface layers …


Continental Runoff And Effects On The North Atlantic Ocean Subtropical Mode Water, Larry P. Atkinson, Chester E. Grosch Jan 1999

Continental Runoff And Effects On The North Atlantic Ocean Subtropical Mode Water, Larry P. Atkinson, Chester E. Grosch

CCPO Publications

Interannual salinity variations in North Atlantic Subtropical Mode Water (STMW) are well known although the cause is less well understood. Attempts to model local salinity variation with local evaporation and precipitation have not been successful and some authors invoke advection of low salinity water as the cause. Examination of the STMW and North American river runoff data suggests that runoff may partly explain the salinity variations. It is known that low salinity water resulting from Mississippi River outflow is transported well past Cape Hatteras. Spearman Rank Correlation analysis and spectra and cross-spectra Fourier correlation analysis both show that river flow …


Warm Water Formation And Escape In The Upper Tropical Atlantic Ocean - 1. A Literature Review, Sang-Ki Lee, G. T. Csanady Jan 1999

Warm Water Formation And Escape In The Upper Tropical Atlantic Ocean - 1. A Literature Review, Sang-Ki Lee, G. T. Csanady

CCPO Publications

We review current understanding of the warm water formation and escape process in the tropical Atlantic Ocean and point out the physical aspects of the process not yet fully explored. From this review, we found a need for a simple model capable of describing the first-order heat and mass balance in the tropical Atlantic Ocean. This line of work is continued in part 2 [Lee and Csanady, this issue]. Copyright 1999 by the American Geophysical Union.


Modeling The Effects Of Doliolids On The Plankton Community Structure Of The Southeastern Us Continental Shelf, A. G. Edward Haskell, Eileen E. Hofmann, Gustav-Adolf Paffenhofer, Peter G. Verity Jan 1999

Modeling The Effects Of Doliolids On The Plankton Community Structure Of The Southeastern Us Continental Shelf, A. G. Edward Haskell, Eileen E. Hofmann, Gustav-Adolf Paffenhofer, Peter G. Verity

CCPO Publications

A model of the lower trophic levels that consists of a system of coupled ordinary differential equations was developed to investigate the time-dependent behavior of doliolid populations associated with upwelling features on the outer southeastern US continental shelf. Model equations describe the interactions of doliolids with two phytoplankton size fractions, five copepod developmental stages and a detrital pool. Additional equations describe nitrate and ammonia. Model dynamics are based primarily upon data obtained from field and laboratory experiments for southeastern US continental shelf plankton populations. Variations on a reference simulation, which represents average upwelling conditions without doliolids, were carried out to …


Aquatic Vegetation In Irrigation Canals, Mark Sytsma, Michael Parker Jan 1999

Aquatic Vegetation In Irrigation Canals, Mark Sytsma, Michael Parker

Center for Lakes and Reservoirs Publications and Presentations

Preparation of this guidance manual for integrated aquatic vegetation management in irrigation canals was stimulated, in large part, by the accidental release of acrolein-treated irrigation water into Bear Creek in southern Oregon. The resulting fish kill brought into focus the need to examine the methods available for managing aquatic vegetation in flowing water. Furthermore, it demonstrated the need for technical assistance on aquatic vegetation management in Oregon. Vegetation management in flowing water is a difficult undertaking. The interconnectedness of natural and manmade water conveyance systems, the tenuous status of many aquatic species, and the necessity of water delivery for profitable …


The Impacts Of External Nutrient Sources On Marine Phytoplankton In An Eastern Shore Sea-Side Estuary, Claudette Lajoie Jenkins Jan 1999

The Impacts Of External Nutrient Sources On Marine Phytoplankton In An Eastern Shore Sea-Side Estuary, Claudette Lajoie Jenkins

OES Theses and Dissertations

The Eastern Shore of Virginia (Greens Creek) as well as a large portion of the North Atlantic coastline is characterized by estuarine systems not dominated by large river systems. Instead, small freshwater creeks influence many coastal systems yet little information has been documented on their ecological significance. The focus of this research is to identify the biogeochemical and physical interactions within an estuarine water-column and understand the importance of freshwater sources in governing phytoplankton production. The hypothesis of this research is that increases in external nutrient loading into Greens Creek will not result in an increase in primary production. The …


200,000 Years Of Climate Change Recorded In Eolian Sediments Of The High Plains Of Eastern Colorado And Western Nebraska, Daniel R. Muhs, James Swinehart, David Loope, John N. Aleinikoff, Josh Been Jan 1999

200,000 Years Of Climate Change Recorded In Eolian Sediments Of The High Plains Of Eastern Colorado And Western Nebraska, Daniel R. Muhs, James Swinehart, David Loope, John N. Aleinikoff, Josh Been

United States Geological Survey: Staff Publications

Loess and eolian sand cover vast areas of the western Great Plains of Nebraska, Kansas and Colorado (Fig. 1). In recent studies of Quaternary climate change, there has been a renewed interest in loess and eolian sand. Much of the attention now given to loess stems from new studies of long loess sequences that contain detailed records of Quaternary glacial-interglacial cycles, thought to be a terrestrial equivalent to the foraminiferal oxygen isotope record in deep-sea sediments (Fig. 2). Loess is also a direct record of atmospheric circulation, and identification of loess paleowinds in the geologic record can test atmospheric general …


Analysis Of The Gal-Chen–Zhang Single-Doppler Velocity Retrieval, Steven Lazarus, Alan Shapiro, Kelvin Droegemeier Jan 1999

Analysis Of The Gal-Chen–Zhang Single-Doppler Velocity Retrieval, Steven Lazarus, Alan Shapiro, Kelvin Droegemeier

Ocean Engineering and Marine Sciences Faculty Publications

The authors present herein an analysis of a single-Doppler velocity retrieval (SDVR) technique whereby the unobserved wind components are determined from single-Doppler radar data. The analysis is designed to provide information about the behavior and/or sensitivity of the SDVR scheme as a function of various internal and external parameters as well as about observational errors and weights. Results presented for retrieval of both the mean and local flow indicate that the SDVR breaks down if the reflectivity gradient vanishes or if a reflectivity isoline is locally perpendicular to the radar beam. In the absence of reflectivity or radial velocity errors, …


A Coupled Bio-Optical And Mixed Layer Model For The Equatorial Pacific, James Vincent Koziana Jan 1999

A Coupled Bio-Optical And Mixed Layer Model For The Equatorial Pacific, James Vincent Koziana

OES Theses and Dissertations

A one dimensional coupled bio-optical and mixed layer model is developed and applied to problems involving the role of phytoplankton-induced turbidity (PIT) on the vertical structure and heating of the upper ocean in the Equatorial Pacific Ocean. The bio-optical and mixed layer model for optically pure sea water was forced with climatological environmental conditions to provide a reference simulation for 140°W in the eastern Equatorial Pacific Ocean. This reference simulation was used for comparison to other simulations which considered the effects of variations in wind stress and solar input for a homogeneous chlorophyll a profile and variations in the magnitude …


Physical Control Of Biological Processes In The Central Equatorial Pacific: A Data Assimilative Modeling Study, Marjorie Anne Macwhorter Friedrichs Jan 1999

Physical Control Of Biological Processes In The Central Equatorial Pacific: A Data Assimilative Modeling Study, Marjorie Anne Macwhorter Friedrichs

OES Theses and Dissertations

A five-component data assimilative ecosystem model is developed in order to investigate the effects of physical processes encompassing a wide range of space and time scales, on the lower trophic levels of the highly dynamic central equatorial Pacific (140°W). Many of the biological processes included in the ecosystem model respond to environmental fluctuations with time scales between one and ten days, which are not typically resolved by basin to global scale circulation models. Therefore, the ecosystem model is forced using daily observations from the TAO mooring array. Model simulations successfully reproduce data collected both during and after the 1991–92 El …


Comparative Study Of Selenium Requirements Of Three Phytoplankton Species: Gymnodinium Catenatum, Alexandrium Minutum (Dinophyta) And Chaetoceros Cf. Tenuissimus (Bacillariophyta, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff Jan 1999

Comparative Study Of Selenium Requirements Of Three Phytoplankton Species: Gymnodinium Catenatum, Alexandrium Minutum (Dinophyta) And Chaetoceros Cf. Tenuissimus (Bacillariophyta, Martina A. Doblin, Susan I. Blackburn, Gustaaf M. Hallegraeff

OES Faculty Publications

This study investigated the selenium (Se) requirements of three phytoplankton species which commonly bloom in southern Australian estuaries. The present study showed that the toxic dinoflagellate Gymnodinium catenatum Graham had an obligate requirement for Se (IV) in culture. After two transfers (~ 4 weeks ≈ 7 generations) in Se-deficient seawater medium, this phytoplankton species exhibited a decline in growth rate (25%) and biomass yield (90%), while complete cessation of cell division occurred under prolonged (8 weeks ≈ 12 generations) Se starvation. Addition of 10-9-10-7 M H2SeO3 to nutrient-enriched seawater medium resulted in increased G.catenatum …


Limitation Of Algal Growth By Iron Deficiency In The Australian Subantarctic Region, Peter N. Sedwick, Giacomo R. Ditullio, David A. Hutchins, Philip W. Boyd, F. Brian Griffiths, A. Clive Crossley, Thomas W. Trull, Bernard Queguiner Jan 1999

Limitation Of Algal Growth By Iron Deficiency In The Australian Subantarctic Region, Peter N. Sedwick, Giacomo R. Ditullio, David A. Hutchins, Philip W. Boyd, F. Brian Griffiths, A. Clive Crossley, Thomas W. Trull, Bernard Queguiner

OES Faculty Publications

In March 1998 we measured iron in the upper water column and conducted iron- and nutrient-enrichment bottle-incubation experiments in the open-ocean Subantarctic region southwest of Tasmania, Australia. In the Subtropical Convergence Zone (∼42°S, 142°E), silicic acid concentrations were low (< 1.5μM) in the upper water column, whereas pronounced vertical gradients in dissolved iron concentration (0.12-0.84 nM) were observed., presumably reflecting the interleaving of Subtropical and Subantarctic waters, and mineral aerosol input. Results of a bottle-incubation experiment performed at this location indicate that phytoplankton growth rates were limited by iron deficiency within the iron-poor layer of the euphotic zone. In the Subantarctic water mass (∼46.8°S, 142°E), low concentrations of dissolved iron (0.05-0.11nM) and silicic acid (< 1μM) were measured throughout the upper water column, and our experimental results indicate that algal growth was limited by iron deficiency. These observations suggest that availability of dissolved iron is a primary factor limiting phytoplankton growth over much of the Subantarctic Southern Ocean in the late summer and autumn.


Resource Allocation And Sucrose Mobilization In Light Limited Eelgrass Zostera Marina, Teresa Alcoverro, Richard C. Zimmerman, Donald G. Kohrs, Randall S. Alberte Jan 1999

Resource Allocation And Sucrose Mobilization In Light Limited Eelgrass Zostera Marina, Teresa Alcoverro, Richard C. Zimmerman, Donald G. Kohrs, Randall S. Alberte

OES Faculty Publications

This study evaluated the ability of Zostera marina L. (eelgrass) to balance the daily photosynthetic deficit by mobilization of carbon reserves stored in below-ground tissues during a period of extreme winter light limitation. A quantitative understanding of the mobilization process and its limitations is essential to the development of robust models predicting minimum light levels required to maintain healthy seagrass populations. Plants were grown in running seawater tanks under 2 light regimes. One treatment was provided with 2 h irradiance-saturated photosynthesis (Hsat) to produce severe Light Limitation, while control plants were grown under 7 h Hsat, …


Bottom Reflection In A Shallow Tidal Bay, S B. Mahongo Dec 1998

Bottom Reflection In A Shallow Tidal Bay, S B. Mahongo

Tanzania Journal of Science

Bottom reflection of short-wave radiation was investigated using measurements taken from a platform in a shallow tidal lagoon on the eastern coast of Zanzibar, the Chwaka bay. Measurements were taken from 18 January to 9 February, 1996. The investigation was facilitated using a simple model of shallow water reflectance. The presumption that bottom reflection plays a significant role in the heat budget of the bay has been found to be incorrect. The computed mean value of the flux due to bottom reflection during this period was only of the order of 2Wm-2, and it is unlikely that variations …


Absorption Efficiencies And Biochemical Fractionation Of Assimilated Compounds In The Cold Water Appendicularian Oikopleura Vanhoeffeni, Alexander B. Bochdansky, Don Deibel, Richard B. Rivkin Dec 1998

Absorption Efficiencies And Biochemical Fractionation Of Assimilated Compounds In The Cold Water Appendicularian Oikopleura Vanhoeffeni, Alexander B. Bochdansky, Don Deibel, Richard B. Rivkin

OES Faculty Publications

Using Ge-68:C-14 dual-labeling, we investigated the absorption efficiency of diatom carbon for the cold water appendicularian Oikopleura vanhoeffeni. The absorption efficiency of bulk carbon (mean = 67%) was not influenced by body size or ingestion rate. For the first time for a pelagic tunicate, food and feces were fractionated into their major biochemical constituents (i.e., low-molecular-weight compounds, lipid, protein, and polysaccharide), allowing calculation of absorption efficiencies for each fraction. Low-molecular-weight compounds and proteins were preferentially absorbed over lipids and polysaccharides. However, predicted C:N ratios of the fecal pellets of O. vanhoeffeni were in the lower range of C:N ratios …


Observations On Groundwater Recharge In The Westdale Catchment, M F. Lewis, C E. Mcconnell Dec 1998

Observations On Groundwater Recharge In The Westdale Catchment, M F. Lewis, C E. Mcconnell

Resource management technical reports

A study of the role of groundwater carriers and barriers in controlling salinity was carried out in the Westdale Catchment by Lewis and McConnell (in preparation). Although that study was primarily concerned with groundwater flow and discharge processes, the data collected also provided rudimentary information on the timing of groundwater recharge events and their distribution across the landscape.


Experiments To Maximize Growth In Captive Florida Pompano (Trachinotus Carolinus), Brian J. Hicks Dec 1998

Experiments To Maximize Growth In Captive Florida Pompano (Trachinotus Carolinus), Brian J. Hicks

HCNSO Student Theses and Dissertations

Florida pompano (Trachinotus carolinus) are highly prized food and sport fish indigenous to coastal areas of the southeastern United States. A commercially valuable fishery has historically existed in the Gulf of Mexico and on the South Atlantic seaboard. Efforts to economically culture Florida pompano in a captive environment were only partially successful. Four experiments were performed to explore the physical and environmental requirements of Florida pompano and other closely related species in the Family (Carangidae):

Experiment #1- Semi-natural spawning was induced with newly developed hormonal implants. to initiate and sustain semi-natural spawning in captive Florida pompano. Fish collected from the …


Wet Deposition In A Global Size-Dependent Aerosol Transport Model: 2. Influence Of The Scavenging Scheme On 210pb Vertical Profiles, Surface Concentrations, And Deposition, W Guelle, Y J. Balkanski, Jack E. Dibb, M Schulz, F Dulac Nov 1998

Wet Deposition In A Global Size-Dependent Aerosol Transport Model: 2. Influence Of The Scavenging Scheme On 210pb Vertical Profiles, Surface Concentrations, And Deposition, W Guelle, Y J. Balkanski, Jack E. Dibb, M Schulz, F Dulac

Earth Sciences

The main atmospheric sink for submicron aerosols is wet removal. Lead 210, the radioactive decay product of 222Rn, attaches immediately after being formed to submicron particles. Here we compare the effects of three different wet-scavenging schemes used in global aerosol simulations on the 210Pb aerosol distribution using an off-line, size-resolved, global atmospheric transport model. We highlight the merits and shortcomings of each scavenging scheme at reproducing available measurements, which include concentrations in surface air and deposition, as well as vertical profiles observed over North America and western and central North Pacific. We show that model-measurement comparison of total …


Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul A. Mayewski, Jack E. Dibb, Sallie I. Whitlow, Zhongqin Lee, Qinzhao Yang Nov 1998

Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul A. Mayewski, Jack E. Dibb, Sallie I. Whitlow, Zhongqin Lee, Qinzhao Yang

Earth Sciences

Simultaneous sampling of aerosol (n = 20) and snow (n = 114) was made at Glacier 1, Tien Shan, between May 19 and June 29, 1996. Similar temporal patterns of some major ion (calcium, magnesium, potassium, sodium, chloride, and sulfate) concentrations between snow and aerosol show that snow chemistry basically reflects changes in the chemistry of the atmosphere. This gives us confidence in the reconstruction of past atmospheric change using some snow data. There are no significant correlations between aerosol and snow samples for ammonium and nitrate. This suggests that post-depositional and/or post-collection processes may alter ammonium and nitrate concentrations …


Nitric Acid Scavenging By Mineral And Biomass Burning Aerosols, A Tabazadeh, M Z. Jacobson, H B. Singh, O Brian Toon, J S. Lin, R B. Chatfield, A N. Thakur, R. Talbot, Jack E. Dibb Nov 1998

Nitric Acid Scavenging By Mineral And Biomass Burning Aerosols, A Tabazadeh, M Z. Jacobson, H B. Singh, O Brian Toon, J S. Lin, R B. Chatfield, A N. Thakur, R. Talbot, Jack E. Dibb

Earth Sciences

The abundance of gas phase nitric acid in the upper troposphere is overestimated by global chemistry-transport models, especially during the spring and summer seasons. Recent aircraft data obtained over the central US show that mineral aerosols were abundant in the upper troposphere during spring. Chemical reactions on mineral dust may provide an important sink for nitric acid. In regions where the mineral dust abundance is low in the upper troposphere similar HNO3 removal processes may occur on biomass burning aerosols. We propose that mineral and biomass burning aerosols may provide an important global sink for gas phase nitric acid, …


Completion Report: Arkansas State Plant Board Pesticide Ground Water Monitoring Project - Phase Vi, T. Nichols, P. Vendrell, K. Steele, H. D. Scott, C. Armstrong Nov 1998

Completion Report: Arkansas State Plant Board Pesticide Ground Water Monitoring Project - Phase Vi, T. Nichols, P. Vendrell, K. Steele, H. D. Scott, C. Armstrong

Arkansas Water Resources Center Technical Reports

No abstract provided.