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Full-Text Articles in Physical Sciences and Mathematics

Timing Movement Of Water Through The Biosphere 2 Rainforest Using Deuterium As An Isotopic Tracer, Katie Almeda, Joost Van Haren, Till Volkmann Jan 2016

Timing Movement Of Water Through The Biosphere 2 Rainforest Using Deuterium As An Isotopic Tracer, Katie Almeda, Joost Van Haren, Till Volkmann

STAR Program Research Presentations

Rain forest ecosystems play an important role in global functions such as being home to half of the species of plants and animals on the planet, acting as a carbon sink, and moving water from the ground back into the atmosphere. In the Amazon, approximately 50 to 80% of moisture produced remains in the ecosystem’s water cycle. As a result of deforestation and rising global temperatures, less moisture can be moved back into the atmosphere. The objective of this study was to trace how water moves through a rain forest system in order to gain insight on how different species …


Using Bromide Tracer To Measure Uranium Diffusivity In Ground Water Sediments, Francis Michael Tee, Morris E. Jones, Megan K. Dustin, Sharon Bone, John Bargar Aug 2015

Using Bromide Tracer To Measure Uranium Diffusivity In Ground Water Sediments, Francis Michael Tee, Morris E. Jones, Megan K. Dustin, Sharon Bone, John Bargar

STAR Program Research Presentations

More than 129 million liters of groundwater are contaminated with uranium at Old Rifle, Colorado – a former uranium-processing site that operated until 1958. The original Department of Energy (DOE) strategy for remediation, involving natural flushing of U from the groundwater through mixing with surface water, has not proven successful. Thin pockets of silt-, clay-, and organic-rich sediments referred to as naturally reduced zones (NRZs) act both as sinks and sources of U to the aquifer, contribute to plume persistence, and appear to be diffusion limited controlled.

To better understand how the NRZs are diffusion limited controlled, a bromide tracer …


Assessing The Influence Of Mineral Surface Chemistry On Soil Organic Matter Stability In The Us In Response To Climate Change, Alexandra Toledo, Katherine Heckman Aug 2014

Assessing The Influence Of Mineral Surface Chemistry On Soil Organic Matter Stability In The Us In Response To Climate Change, Alexandra Toledo, Katherine Heckman

STAR Program Research Presentations

Soils represent a significant pool for carbon storage and sequestration. Previous field experiments have indicated that some mineral compositions are more effective in preserving soil organic matter (SOM) from microbial degradation. Due to climate change, it is important to quantify which soil types are changing in mineral surface chemistry. One way to do that is by differentiating the SOM stabilization mechanisms in different soil types at various depths. This study focused on examining the distribution of soil mass and composition by the soils density and mineral classification and the soils stability by measuring the amount of carbon and radiocarbon abundance. …


The Influence Of Soil Organic Matter Stabilization Mechanisms On Carbon Mean Residence Time Within Various Ecosystems In The United States, Vicky Lynn Giese, Kate Heckman Phd Aug 2013

The Influence Of Soil Organic Matter Stabilization Mechanisms On Carbon Mean Residence Time Within Various Ecosystems In The United States, Vicky Lynn Giese, Kate Heckman Phd

STAR Program Research Presentations

Some terrestrial ecosystems and soils serve as carbon sinks, partially offsetting rising atmospheric CO2 levels. Physiochemical mechanisms of soil organic matter (SOM) stabilization affect how carbon stocks respond to global warming. In order to clarify the variance in SOM stabilization mechanisms across different soil types, SOM abundance, distribution and mean residence time (MRT) were compared for thirty-two soil samples from six ecosystems across the United States. Soils were previously described, collected and archived by the United States Geological Survey. Samples were processed by LLNL at the Center for Accelerator Mass Spectrometry (CAMS) using density fractionation to separate particulate organics …


Lithic Analysis Of Coyote Canyon Mammoth Site Sediments, Kaitlin M. Hill, George V. Last Aug 2013

Lithic Analysis Of Coyote Canyon Mammoth Site Sediments, Kaitlin M. Hill, George V. Last

STAR Program Research Presentations

The landforms and geologic layers of Southeastern Washington record fascinating, unique geologic events, including repeated catastrophic flooding that occurred during the last Ice Age. These floods left behind many distinctive features, and a variety of fossils. After discovery of mammoth-sized bones in 1999, and confirmation that more bones were still in place in 2008, the Coyote Canyon Mammoth Site near Kennewick, Washington was secured for research, and formal excavation began in 2010.

Previous research suggests that the remains are buried in Ice Age flood deposits, which are overlain by eolian sediments, and those in turn overlain by slope wash. We …


Trends In Soil Science Education And Employment, J. Havlin, N. Balster, S. Chapman, D. Ferris, T. Thompson, T. Smith Sep 2010

Trends In Soil Science Education And Employment, J. Havlin, N. Balster, S. Chapman, D. Ferris, T. Thompson, T. Smith

Earth and Soil Sciences

During the last several decades, members of the SSSA have discussed several trends related to soil science education, including: (i) declining academic programs and course offerings at land grant universities, (ii) decreased enrollments, and (iii) improved employment opportunities for soil science graduates (SSSA, 2006; Ferris et al., 2010). The SSSA Advocacy/Education Task Force met in 2007 and concluded that quantitative survey information was needed to document trends in soil science academic programs, student enrollment, faculty, and job opportunities for graduates. Suggested survey topics included:

  • Has the recognition of soil science as a distinct discipline increased or decreased?
  • How has the …


Effects Of Composted And Raw Manure And Ammonium Sulfate Applications On The Chemical Properties Of The Soils At Chorro Creek Ranch, San Luis Obispo, Ca., Renee Nall,, Craig Stubler, Christopher Appel, Tanner Campbell, Jose Gomez, Nathan Lurie, Russell Morgan, J. J. Scurich Nov 2009

Effects Of Composted And Raw Manure And Ammonium Sulfate Applications On The Chemical Properties Of The Soils At Chorro Creek Ranch, San Luis Obispo, Ca., Renee Nall,, Craig Stubler, Christopher Appel, Tanner Campbell, Jose Gomez, Nathan Lurie, Russell Morgan, J. J. Scurich

Earth and Soil Sciences

The majority of agricultural systems, especially large-scale, require inputs of nutrients. In addition, many large scale dairies produce vast quantities of waste that can be potentially recycled as nutrients. This study was conducted to determine the differences in properties of soils amended with manure, compost, and fertilizer, and to assess implications of using animal waste products for forage crop fertilization. Forage crops, wheat, barley, and oat mix have been grown on the Chorro Creek Ranch part of Cal Poly farmland, for 15 years. Ammonium sulfate fertilizer has been applied at a rate of 200 lbs/acre/year for the past 4 years. …


Overland Flow And Rainfall Simulation Studies On Ornamental Vegetation, Compost, And Jute Netting, Brent G. Hallock, Candace Kimmelshue, Steve Rein, Michael Curto, Misty Scharff Feb 2009

Overland Flow And Rainfall Simulation Studies On Ornamental Vegetation, Compost, And Jute Netting, Brent G. Hallock, Candace Kimmelshue, Steve Rein, Michael Curto, Misty Scharff

Earth and Soil Sciences

The literature is replete with studies quantifying erosion control effectiveness from raindrop impact on various vegetation types and erosion control products. However, there is little published overland flow research documenting the effectiveness of ornamental vegetation and erosion control products in filtering sediment and nutrients from stormwater runoff. The California Department of Transportation and the Office of Water Programs, California State University, Sacramento, has conducted two studies at the Erosion Control Research Facility at Cal Poly State University, San Luis Obispo addressing the use of ornamental vegetation as an erosion control treatment. The first study addressed how well ornamental vegetation, jute …


Analysis Of Chromium And Nickel In Soil And Plant Tissue Collected From The Experimental Vineyard At California Polytechnic State University, San Luis Obispo, Ca, Ian Leslie, Chip Appel, Craig Stubler, Kiana Amiri-Davani, Ashley Devalentine, Jose Gomez, Daniel Kim, Tommy Konwinski, Angie Quintana-Jones, Keith Patterson Oct 2008

Analysis Of Chromium And Nickel In Soil And Plant Tissue Collected From The Experimental Vineyard At California Polytechnic State University, San Luis Obispo, Ca, Ian Leslie, Chip Appel, Craig Stubler, Kiana Amiri-Davani, Ashley Devalentine, Jose Gomez, Daniel Kim, Tommy Konwinski, Angie Quintana-Jones, Keith Patterson

Earth and Soil Sciences

Serpentinitic soils often contain high concentrations of heavy metals, including chromium (Cr) and nickel (Ni). Soils derived from serpentine parent material are used for agricultural purposes throughout San Luis Obispo County, CA. This study was undertaken to determine the amount of total and bioaccessible Cr and Ni in soil and vine tissue from a vineyard planted on soils derived from serpentine geology. Eighteen soil and plant samples were collected from different slope position and vine types (syrah and chardonnay). Soil samples were collected from about 0 to 30 cm at the base of the vines and 15 to 20 leaf …


Erosion Control Performance Studies On Ornamental Vegetation, Compost, And Jute Netting, Brent Hallock Sep 2008

Erosion Control Performance Studies On Ornamental Vegetation, Compost, And Jute Netting, Brent Hallock

Earth and Soil Sciences

No abstract provided.


Sequential Sorption Of Lead And Cadmium In Three Tropical Soils, Chip Appel, Lena Q. Ma, Roy D. Rhue, William Reve Sep 2008

Sequential Sorption Of Lead And Cadmium In Three Tropical Soils, Chip Appel, Lena Q. Ma, Roy D. Rhue, William Reve

Earth and Soil Sciences

It is important to examine mechanisms of Pb and Cd sorption in soils to understand their bioavailability. The ability of three tropical soils to retain Pb, Cd, and Ca was evaluated. The objectives of this study were to (1) determine the extent to which soil sorption sites are metal specific, (2) investigate the nature of reactions between metals and soil surfaces, and (3) identify how metals compete for sorption sites when they are introduced to soils sequentially or concurrently. Lead was shown to be much less exchangeable than Cd and inhibited Cd sorption. Cadmium had little effect on Pb sorption, …


Water Quality Relative To Slope Toe Strip Type And Length, Brent G. Hallock, Lauren Corkins, Steve Rein, Michael Curto, Misty Scharff Feb 2007

Water Quality Relative To Slope Toe Strip Type And Length, Brent G. Hallock, Lauren Corkins, Steve Rein, Michael Curto, Misty Scharff

Earth and Soil Sciences

Vegetation plays an important role in decreasing soil particle detachment and transport from sites following disturbance. Past rainfall simulator research (Caltrans 2004) using 2.5 m L x 0.6 m W soil test boxes with a 0.25 m sod strip (1 :10 slope proportion) at the slope toe found statistically significant reduction of total sediment loss to near zero. A principle limitation of the previous in house experiment is that a 1: 10 proportion of sod strip to slope length is not practical, nor equivalent with many industry specifications. Therefore, another rainfall simulator experiment was designed and conducted from October 2005 …


Sequential Extraction Of Copper And Zinc From Two Californian Soils, Katharine Carr, Christopher Appel, Craig Stubler, Shana Mccarthy Nov 2006

Sequential Extraction Of Copper And Zinc From Two Californian Soils, Katharine Carr, Christopher Appel, Craig Stubler, Shana Mccarthy

Earth and Soil Sciences

In order to understand how to remediate soils contaminated with heavy metals, it is important to first understand their sorption mechanisms. The objective of this study was to evaluate the bioavailability of elevated levels of soil copper (Cu) and zinc (Zn) via sequential extraction. Elevated levels of Cu and Zn were added separately and concurrently to a Mollisol and an Entisol from the central coast of California. The exchangeable amount of Cu and Zn was then extracted from the sorbed amount via 0.1 M NaNO3. The residual fraction was then extracted with 0.1 M sodium citrate (NaC6 …


Total And Bioavailable Chromium Along A Toposequence In San Luis Obispo, Ca., Britani Harris, Christopher Appel, Craig Stubler, Arwen Ross, Maribel Alvarado, Katharine Carr, Byron Clamor, Lauren Corkins, Scott Grandi-Hill, Walter Levicki, Michael Wagoner, Ryan Tappero Nov 2006

Total And Bioavailable Chromium Along A Toposequence In San Luis Obispo, Ca., Britani Harris, Christopher Appel, Craig Stubler, Arwen Ross, Maribel Alvarado, Katharine Carr, Byron Clamor, Lauren Corkins, Scott Grandi-Hill, Walter Levicki, Michael Wagoner, Ryan Tappero

Earth and Soil Sciences

The presence of large quantities of Chromium metal in soil and plants is of major concern due to its toxicity to humans. Total (USEPA 3050a) and bioavailable (USEPA 1311) levels of chromium were measured along a serpentinic Central Coast toposequence. Soil from the surface and subsurface, as well as the above ground plants of the toposequence were determined and compared to several soil chemical and physical properties using a least squares regression. The binding environments and oxidation states were found through XANES and EXAFS x-ray spectroscopies. The total and bioavailable chromium concentrations of the soil averaged 1457.1 and 1.6 mg …


Analysis Of Compost Treatments To Establish Shrubs And Improve Water Quality, Brent G. Hallock, Anne Power, Steve Rein, Michael Curto, Misty Scharff Feb 2006

Analysis Of Compost Treatments To Establish Shrubs And Improve Water Quality, Brent G. Hallock, Anne Power, Steve Rein, Michael Curto, Misty Scharff

Earth and Soil Sciences

Utilization of compost as an erosion control tool is gaining momentum for many reasons. Compost offers excellent surface protection for reducing topsoil loss while providing a favorable substrate for hydroseed mixes. Soil moisture is retained and nutrients for vegetation are provided, meanwhile inhibiting undesirable plant species. However, there is wide variation in available compost sources and cost. Possible interactions between compost composition, soil type and vegetation production may occur. Hence, an experiment aimed to determine whether there is a noticeable difference in erosion control and seedling germination performance between several common types of compost applied at varying rates and methods …


Determination Of Total And Bioavailable Soil Lead From A Shooting Range In Central California., Phil Roberts, Chip Appel, Jake Shneider, Tamber Schmall, Melissa Simoes, Carissa Griffith, Dave Baker, Chad Lessard, Katharine Carr, Myles Davis, Cameron Sharp, Jesse Hitchcock, Craig Stubler, Jason Stuckey Nov 2005

Determination Of Total And Bioavailable Soil Lead From A Shooting Range In Central California., Phil Roberts, Chip Appel, Jake Shneider, Tamber Schmall, Melissa Simoes, Carissa Griffith, Dave Baker, Chad Lessard, Katharine Carr, Myles Davis, Cameron Sharp, Jesse Hitchcock, Craig Stubler, Jason Stuckey

Earth and Soil Sciences

Lead can pose a significant risk to environmental quality at and around shooting ranges due to its use in bullets and shot. The concentrations of Pb in soils, plants and surficial waters from a shooting range were determined in this study. Soil and plant samples were analyzed for total Pb (US EPA method 3050a) to determine the extent of Pb contamination. The toxicity characteristic leach procedure (TCLP; US EPA method 1311) was followed to ascertain bioavailable Pb. Soil samples ranged from 14.71 to 6346.15 mg Pb kg-1 soil with an average value of 1157.43 (±2000.57) mg Pb kg-1 soil across …


Establishment Of Native Vegetation For Erosion Control On The Cal Poly, San Luis Obispo, Campus., C Appel, A. Dere, K. Carr, M. Perry, C. Stubler, B. Hallock Nov 2004

Establishment Of Native Vegetation For Erosion Control On The Cal Poly, San Luis Obispo, Campus., C Appel, A. Dere, K. Carr, M. Perry, C. Stubler, B. Hallock

Earth and Soil Sciences

When applied to a bare slope, vegetation and mulch will prevent further erosion and enhance the aesthetic appeal of the area, ultimately improving the quality of the soil. If nothing is done to this barren slope, its condition will continue to deteriorate. Core samples were taken at six different sites located on a highly degraded and barren slope on the Cal Poly campus. Bulk density, porosity, soil temperature, and nitrogen and phosphorous levels were measured prior to vegetating the slope. Thirty-three groundcover rose bushes were planted and drip irrigation was installed. Mulch was laid down and two un-official coarse-sand walking …


Evaluation Of Extent And Bioavailability Of Chromium Contamination Near An Abandoned Strip Mine, C. Appel, J. Stuckey, A. Cosley, R. Donald, C. Griffith, S. Lager, M. Perry, T. Ray, P. Smith Oct 2004

Evaluation Of Extent And Bioavailability Of Chromium Contamination Near An Abandoned Strip Mine, C. Appel, J. Stuckey, A. Cosley, R. Donald, C. Griffith, S. Lager, M. Perry, T. Ray, P. Smith

Earth and Soil Sciences

Chromium is a potentially toxic element to plants and animals commonly associated with serpentine and anthropogenic sources. An abandoned Cr strip-mine at US National Guard Camp SLO, CA containing serpentinitic parent material was tested for total and bioavailable Cr in the soil and overlying vegetation via US EPA Methods 3050a (Total Cr) and 1311 (Total Characteristic Leaching Procedure, TCLP) (US EPA, 1995), respectively. The analysis of total and bioavailable Cr was used to assess the risk of nearby surface and groundwater contamination and to evaluate the site’s need for remediation. In addition, trends in soil Cr levels with respect to …


Mechanisms Of Lead, Copper, And Zinc Retention By Phosphate Rock, Xinde Cao, Lena Q. Ma, Dean R. Rhue, Chip S. Appel Oct 2004

Mechanisms Of Lead, Copper, And Zinc Retention By Phosphate Rock, Xinde Cao, Lena Q. Ma, Dean R. Rhue, Chip S. Appel

Earth and Soil Sciences

The solid–liquid interface reaction between phosphate rock (PR) and metals (Pb, Cu, and Zn) was studied. Phosphate rock has the highest affinity for Pb, followed by Cu and Zn, with sorption capacities of 138, 114, and 83.2 mmol/kg PR, respectively. In the Pb–Cu–Zn ternary system, competitive metal sorption occurred with sorption capacity reduction of 15.2%, 48.3%, and 75.6% for Pb, Cu, and Zn, respectively compared to the mono-metal systems. A fractional factorial design showed the interfering effect in the order of Pb > Cu > Zn. Desorption of Cu and Zn was sensitive to pH change, increasing with pH decline, whereas Pb …


Understanding The Mechanisms Of Lead, Copper, And Zinc Retention By Phosphate Rock, R. X. Cao, L. Q. Ma, R. D. Rhue, C. S. Appel Nov 2003

Understanding The Mechanisms Of Lead, Copper, And Zinc Retention By Phosphate Rock, R. X. Cao, L. Q. Ma, R. D. Rhue, C. S. Appel

Earth and Soil Sciences

The solid-liquid interface reaction between phosphate rock (PR) and metals (Pb, Cu, and Zn)was studied. Phosphate rock has the highest affinity for Pb, followed by Cu and Zn, with sorption capacities of 131, 114, and 83.2 mmol kg-1 PR, respectively. In the Pb-Cu-Zn ternary system, competitive metal sorption occurred with sorption capacity reduction of 15.2%, 48.3%, and 75.6% for Pb, Cu, and Zn, respectively. A fractional factorial design showed the interfering effect in the order of Pb>Cu>Zn. Desorption of Cu and Zn was sensitive to pH change, increasing with pH decline, whereas Pb desorption was decreased with a …


Cal Poly's Eswcc Teaches The Next Generation Of Soil Scientists, M. Perry, C. Appel Nov 2003

Cal Poly's Eswcc Teaches The Next Generation Of Soil Scientists, M. Perry, C. Appel

Earth and Soil Sciences

Since 1992, members of Cal Poly San Luis Obispo’s Earth, Soil, and Water Conservation Club (ESWCC), sponsored by the MESA Agricultural Initiative, have volunteered their time and expertise to educate middle-school students in soil science. ESWCC members assemble soil testing kits containing three soils, pH testing materials, and instructions for analyzing soil pore space, water infiltration rates, and soil texture by “feel”. The kits help over 200 California teachers convey the importance of soil science through simple physical and chemical procedures that provide a deeper understanding of soil. ESWCC members train teachers to run classroom experiments and to relate soil …


Point Of Zero Charge Determination In Soils And Minerals Via Traditional Methods And Detection Of Electroacoustic Mobility, Chip Appel, Lena Q. Ma, R. Dean Rhue, Elizabeth Kennelley Apr 2003

Point Of Zero Charge Determination In Soils And Minerals Via Traditional Methods And Detection Of Electroacoustic Mobility, Chip Appel, Lena Q. Ma, R. Dean Rhue, Elizabeth Kennelley

Earth and Soil Sciences

Points of zero charge were determined on two highly weathered surface soils from Puerto Rico, an Oxisol and Ultisol, as well as mineral-standard kaolinite and synthetic goethite using three methods: (1) potentiometric titration measuring the adsorption of H+ and OH− on amphoteric surfaces in solutions of varying ionic strength (I) (point of zero salt effect), (2) direct assessment of surface charges via non-specific ion adsorption as a function of pH and I (point of zero net charge), and (3) electroacoustic mobility of reversible particles as it varies with pH and I (isoelectric point). The first two methods yielded points of …


The Design And Construction Of A Rainfall Simulator, Jacqueline Blanquies, Misty Scharff, Brent Hallock Feb 2003

The Design And Construction Of A Rainfall Simulator, Jacqueline Blanquies, Misty Scharff, Brent Hallock

Earth and Soil Sciences

A reliable, accurate and portable rainfall simulator was needed for vegetative and erosion control research at California Polytechnic State University, San Luis Obispo (Cal Poly) for California Department of Transportation (Caltrans) and California State University Sacramento. This simulator was designed to be easily set up and maintained as well as able to create a variety of rainfall regimes. The nozzle performance tests and lateral spacing tests were performed at Cal Poly’s Erosion Research Facility. This simulator was designed and constructed based upon the principles of the Norton Ladder Type Rainfall Simulator. This simulator is the standard for research involving simulated …


Vegetation Establishment For Erosion Control Under Simulated Rainfall, Brent G. Hallock, Misty Scharff, Steve Rein, Kaila Dettman Feb 2003

Vegetation Establishment For Erosion Control Under Simulated Rainfall, Brent G. Hallock, Misty Scharff, Steve Rein, Kaila Dettman

Earth and Soil Sciences

The California Department of Transportation (Caltrans) manages rights of ways that transect 41 m H (101m ac) and span over 3000 m (9000 ft) in elevation from seashore to sup alpine. There are approximately 4,900 native and 1,000 naturalized alien plant species in California. Only a few hundred are reliably useful in erosion and sediment control. Specifying native and naturalized vegetation mixes for use in hydroseeding or plug planting in conjunction with mechanical erosion control methods can have varying result for minimizing accelerated soil erosion. To investigate these factors, Cal Poly, San Luis Obispo, in conjunction with Caltrans and CSU, …


Selectivities Of Potassium-Calcium And Potassium-Lead Exchange In Two Tropical Soils, Chip Appel, Lena Q. Ma, R. Dean Rhue, William Reve Jan 2003

Selectivities Of Potassium-Calcium And Potassium-Lead Exchange In Two Tropical Soils, Chip Appel, Lena Q. Ma, R. Dean Rhue, William Reve

Earth and Soil Sciences

Measurement of cation selectivity in soils provides important information about the affinity and binding strength of a particular cation on soil surfaces. Gaines-Thomas (KGT) selectivity coefficients were determined for a variety of K/Ca and K/Pb ratios on an Oxisol and Ultisol soil from Puerto Rico. The calculated KGT values indicated a preference for K+ over Ca2+ or Pb2+. The selectivity for Pb2+ was significantly greater than that for Ca2+ due to Pb2+'s larger hydrated charge density relative to that of Ca2+. The patterns of selectivity were independent …


Measuring Surface Chemical Properties Of Soil Using Flow Calorimetry, R. D. Rhue, Chip Appel, Nadine Kabengi Dec 2002

Measuring Surface Chemical Properties Of Soil Using Flow Calorimetry, R. D. Rhue, Chip Appel, Nadine Kabengi

Earth and Soil Sciences

Flow calorimetry, which is ideally suited for measuring reactions occurring at the liquid/solid interface, has been used to study the surface chemistry of many types of solids, but little use of it has been made in the study of surface reactions of soils. The purpose of this study was to demonstrate the application of flow calorimetry to the study of two fundamental soil chemical processes, namely cation exchange and phosphate sorption. Surface horizon samples of a Typic Acrorthox and a Typic Tropohumult from Puerto Rico, a strong acid cation exchange resin (Dowex 50W-8), and an amorphous Al(OH)3 were used. …


Heats Of K/Ca And K/Pb Exchange In Two Tropical Soils As Measured By Flow Calorimetry, Chip Appel, Dean Rhue, Lena Ma, Bill Reve Dec 2002

Heats Of K/Ca And K/Pb Exchange In Two Tropical Soils As Measured By Flow Calorimetry, Chip Appel, Dean Rhue, Lena Ma, Bill Reve

Earth and Soil Sciences

Flow calorimetry can provide useful information about surface chemical reactions in soils that cannot be obtained readily by other methods. When flow calorimetry is conducted over a range of surface coverages, different sorption heats can be calculated to yield information about how binding energies vary with coverage, i.e., surface heterogeneity. The purpose of this study was to determine heats of exchange for K/Ca and K/Pb systems using flow calorimetry and to evaluate the degree of surface heterogeneity with respect to cation exchange. Surface horizon samples from a Typic Acrorthox and Typic Tropohumult from Puerto Rico were used. Lead was adsorbed …


Selectivities Of K/Ca And K/Pb Exchange In Two Tropical Soils, C. S. Appel, L. Q. Ma, R. D. Rhue, W. Reve Nov 2002

Selectivities Of K/Ca And K/Pb Exchange In Two Tropical Soils, C. S. Appel, L. Q. Ma, R. D. Rhue, W. Reve

Earth and Soil Sciences

Measurement of cation selectivity in soils provides important information about the affinity and binding strength of a particular cation on soil surfaces. Gaines-Thomas (KGT) selectivity coefficients were determined for a variety of K/Ca and K/Pb ratios on an Oxisol and Ultisol soil from Puerto Rico. The calculated KGT values indicated a preference for K+ over Ca2+ or Pb2+. The selectivity for Pb2+ was significantly greater than that for Ca2+ due to the larger hydrated charge density of Pb2+ relative to that of Ca2+. The patterns of selectivity were independent of metal type. The selectivity of the Oxisol for Ca2+ or …


Concentration, Ph, And Surface Charge Effects On Cadmium And Lead Sorption In Three Tropical Soils, Chip Appel, Lena Ma Mar 2002

Concentration, Ph, And Surface Charge Effects On Cadmium And Lead Sorption In Three Tropical Soils, Chip Appel, Lena Ma

Earth and Soil Sciences

Reactions of heavy metals with soil are important in determining metal fates in the environment. Sorption characteristics of two heavy metals, Cd and Pb, in three tropical soils (Mollisol, Oxisol, and Ultisol) from Puerto Rico were assessed at varying metal concentrations (0 to 1.2 mM) and pH values (approximately 2 to 7). All soils sorbed more Pb than Cd. Sorption maxima were obtained for each metal for the Oxisol and Ultisol soils, but not the Mollisol. Sorption appeared to depend more on soil mineralogy than organic matter content. Sorption isotherms were linear within the sorption envelope with similar slopes for …


Importance Of Soil Texture To Vineyard Management, Thomas J. Rice Mar 2002

Importance Of Soil Texture To Vineyard Management, Thomas J. Rice

Earth and Soil Sciences

No abstract provided.