Journal of Environmental Quality 32:1-7 (2003)
© 2003 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America
EXECUTIVE SUMMARIES
This Issue in Journal of Environmental Quality
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Trace Gas Flux Measured from Landfarm Soils
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The emission of trace gases to the atmosphere from landfarms and bioremediation facilities is an area that has not been thoroughly investigated. The release of trace gases such as hydrocarbons from landfarms may impair regional air quality or pose health risks to on-site workers. Trace gas emissions from refinery and bioremediation landfarms were investigated in a mesocosm-scale simulator facility during experiments evaluating the impact of simulated cultivation and rainfall on trace gas fluxes. An evaluation of the impact of simultaneous water vapor fluxes on other trace gas fluxes highlighted the importance in lab-scale experiments of correcting trace gas fluxes from soils. Results from this research can be used to guide management practices at landfarms and to provide data to aid in assessing the impact of landfarms.
S. Ausma
(sausma{at}mpch-mainz.mpg.de)
Laboratory-Scale Measurement of Trace Gas Fluxes from Landfarm Soils. J. Environ. Qual. 32:
8–22.
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Residual Effects of Manure and Compost Applied to Soil
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The emissions of carbon dioxide from soil were similar among manure, compost, fertilizer, and no treatment check four years after termination of manure and compost application. Emission rates of methane and nitrous oxide were nearly zero, which indicated the residual effects of manure and compost had no negative impact on global warming. Four years after application stopped, manure and compost resulted in positive C and N balances in the soil (improved soil quality) compared with fertilizer and check treatments.
B. Eghball (beghball1{at}unl.edu)
Greenhouse Gas Emissions and Soil Indicators Four Years after Manure and Compost Applications. J. Environ. Qual. 32:
23–32.
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Long-Term Sulfur Deposition at Rothamsted, England
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Human activities have dramatically altered global sulfur cycling. Zhao et al. show the stable isotope ratios of S of archived plant and soil samples from the world's oldest agricultural experiment, the Rothamsted Broadbalk Experiment, England, reflected the dramatically changing SO2 pollution in the UK over the last 155 years. The S isotope ratios were used to estimate the contributions of anthropogenic S emissions to the soil S pool and plant uptake.
F. Zhao (fangjie.zhao{at}bbsrc.ac.uk)
Stable Sulfur Isotope Ratio Indicates Long-Term Changes in Sulfur Deposition in the Broadbalk Experiment since 1845. J. Environ. Qual. 32:
33–39.
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Stopping Perchlorate Transport to Ground Water
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Perchlorate contamination of drinking water and irrigation water is a growing problem, particularly in the western USA. Tipton et al. show indigenous microorganisms in some soils are capable of biodegrading perchlorate under anaerobic conditions and in the presence of sufficient C. Factors that appear to influence a soil's ability to biodegrade perchlorate include its C content and history of perchlorate exposure. Results suggest there is potential for perchlorate to be reduced in surface soils before it migrates to shallow ground water or is taken up by crops.
D.K. Tipton (d_tipton{at}hotmail.com)
Transport and Biodegradation of Perchlorate in Soils. J. Environ. Qual. 32:
40–46.
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Microorganisms Munch Insecticide
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Endosulfan, a broad-spectrum organochlorine insecticide, is used worldwide and its residues are found throughout the global biosphere polluting the environment. Siddique et al. isolated 10 endosulfan-degrading microorganisms capable of utilizing endosulfan as a C or S source. Isolated microorganisms degraded more endosulfan as a C source than S and about 90% of 
- and ß-endosulfan was degraded by the fungal strain F4 (Fusarium ventricosum) while bacterial strains Lin-3 (Pandoraea sp.) and B4 consumed about 80% of -endosulfan and 85% of ß-endosulfan as a C source during 15 d of incubation. Bacterial strains B4s and F4t degraded about 70% of - and ß-endosulfan as a S source during 15 d. Results suggest these active microbial strains may be used to promote degradation of endosulfan in the environment.
W.T. Frankenberger, Jr.
(william.frankenberger{at}ucr.edu)
Enrichment and Isolation of Endosulfan-Degrading Microorganisms. J. Environ. Qual. 32:
47–54.
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Biomethylation and Volatilization of Selenium from a Constructed Wetland
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The potential of rhizosphere microbes isolated from common reed plants grown in a subsurface-flow constructed wetland to biomethylate selenate or selenite was studied in liquid cultures under controlled conditions. Total mean percentages of volatilized Se from one-half Hoagland culture solutions (low C content) supplemented with selenate or selenite and inoculated with cultured rhizosphere microbes after 15 d of incubation were 7.9 and 49.1%, respectively. However, when the same microbes were cultured in tryptic soy broth (a culture medium high in C), the percentages of volatilized Se from selenate and selenite were 1.3 and 1.9%, respectively. Dimethylselenide (DMSe) in water samples was indirectly detected up to 2.4 µg Se L-1, which indicates part of the produced DMSe was dissolved in the matrix before being released into the atmosphere. Results show rhizosphere microbes isolated from common reed plants have a high potential of Se biomethylation and volatilization from selenate and selenite.
A.H. Azaizeh
(hazaizeh{at}hotmail.com)
The Potential of Rhizosphere Microbes Isolated from a Constructed Wetland to Biomethylate Selenium. J. Environ. Qual. 32:
55–62.
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Cleaning Up Polluted Wastewater
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Chlorinated phenols are major industrial and agricultural xenobiotics that pollute soil and ground water. Since it has been shown that laccases, a family of enzymes, catalyze the breakdown of phenolic compounds, the transformation of one or a mixture of several chlorinated phenols by a laccase from the fungus Trametes villosa was studied. Generally, the transformation of chlorinated phenols decreased if more than one phenol was added to the reaction mixture, but this inhibition could be reduced if the concentration of laccase was increased. Therefore, in spite of some limitations, the application of laccase to decontaminate wastewater polluted with chlorinated phenols appears feasible.
J.-M. Bollag (jmbollag{at}psu.edu)
Enzymatic Oxidative Transformation of Chlorophenol Mixtures. J. Environ. Qual. 32:
63–69.
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Finding Phosphorus Runoff from Agricultural Soils
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Where particulate P loss from agricultural fields makes a significant contribution to the annual P loading of watercourses, characterization of the desorption tendency of sediment-associated P in runoff is of importance in eutrophication. A simple extraction that could be used to assess the redox-sensitive P in field runoff without preconcentration of particulate matter was investigated by Uusitalo and Turtola. More than 70% of the P associated with poorly crystallized synthetic Fe-oxides was extracted by the method, whereas extractability of P associated with synthetic Al-hydroxides and four naturally occurring Ca-phosphate minerals was only 7 and <0.2%, respectively. For 79 runoff samples from a very-fine Typic Cryaquept, redox-sensitive P gave a linear response to relatively great concentrations of total solids. In soils that produce turbid runoff, the proposed extraction procedure can potentially be used as an aid in evaluating BMPs for water protection.
R. Uusitalo (risto.uusitalo{at}mtt.fi)
Determination of Redox-Sensitive Phosphorus in Field Runoff without Sediment Preconcentration. J. Environ. Qual. 32:
70–77.
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Reducing Simazine Runoff in Orchards
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Simazine loss via runoff in the San Joaquin Valley of California is a potential source of environmental contamination because simazine is widely used for weed control during the rainy season (November–March). Simazine loss in runoff was compared between row middles that were either undisturbed, the normal orchard practice, or subjected to shallow mechanical incorporation. Low water infiltration rate inhibited surface-applied herbicide incorporation into the soil matrix with natural rainfall in compacted soils. Mechanical incorporation of row middles significantly reduced runoff volumes, simazine concentrations, and mass losses in runoff after application.
F. Liu (FLIU{at}uckac.edu)
Simazine Runoff from Citrus Orchards Affected by Shallow Mechanical Incorporation. J. Environ. Qual. 32:
78–83.
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Halting Herbicide Leaching to Ground Water
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Irrigation practices and precipitation affect the leaching of herbicides to shallow ground water. Peak herbicide leaching to shallow ground water usually was associated with intense storm events occurring within days of herbicide application. Focused recharge was associated with storm runoff that ponded in drainage ditches on the surge-irrigated field, in the upgradient road ditch, and at the low end of the conventionally irrigated field. Sprinkler irrigation significantly lessened the occurrence of focused pesticide leaching.
R.F. Spalding (rspalding1{at}unl.edu)
Herbicide Loading to Shallow Ground Water beneath Nebraska's Management Systems Evaluation Area. J. Environ.
Qual. 32:
84–91.
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Herbicides Found in Ground Water beneath Irrigated Corn
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Herbicide profiles are described by intense multilevel sampling of ground water beneath managed irrigated corn fields. Age-dated ground water indicated triazine and acetamide use at the site and on upgradient soils significantly impacted water quality. Deethylatrazine and metolachlor ethane sulfonic acid concentrations far exceeded those of the parent herbicides. Atrazine's half-life approached 20 yr and atrazine was most probably transformed to hydroxyatrazine in the ground water beneath the site.
R.F. Spalding (rspalding1{at}unl.edu)
Herbicides in Ground Water beneath Nebraska's Management Systems Evaluation Area. J. Environ. Qual. 32:
92–99.
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Reducing Lead in Urban Soils
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A range of biosolids and biosolid composts were applied to a high-Pb soil from a home garden in Baltimore, MD. Addition of a high Fe biosolids compost generated from Baltimore biosolids at 10% dry weight of soil reduced Pb absorption in rats by 37% over the control soil. Results suggest amending urban soils with biosolids compost can reduce the bioavailability of Pb in those soils.
S. Brown (slb{at}u.washington.edu)
Effect of Biosolids Processing on Lead Bioavailability in an Urban Soil. J. Environ. Qual. 32:
100–108.
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Soil Arsenic Compared in Two Florida Cities
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The distribution of soil As in the two Florida cities of Miami and Gainesville was compared. Soil As concentrations varied both between cities and with land use type. In general, anthropogenic influences masked the impact of pedogenic processes on soil As concentrations.
T. Chirenje (tchirenj{at}ufl.edu)
Arsenic Distribution in Florida Urban Soils: Comparison between Gainesville and Miami. J. Environ. Qual. 32:
109–119.
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Organic Manures Enhance Cr(VI) Reduction
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Chromium is used as Cr(III) in the tannery industry and as Cr(VI) in the timber treatment industry. Chromium(VI) is highly toxic and carcinogenic, even when present in very low concentrations in water. Bolan et al. evaluated the effect of a number of organic manures on the reduction of Cr(VI) to Cr(III) and its subsequent phytotoxicity. Results showed organic manures enhanced Cr(VI) reduction and were effective in eliminating Cr phytotoxicity. The manure-enhanced Cr(VI) reduction is attributed to the supply of C and protons, and stimulation of microorganisms that are considered to be the major factors controlling Cr(VI) reduction.
N.S. Bolan
(N.S.Bolan{at}massey.ac.nz)
Effects of Organic Amendments on the Reduction and Phytoavailability of Chromate in Mineral Soil. J. Environ. Qual. 32:
120–128.
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Controlling Cadmium Sorption in Soil
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The dominating effect of pH for controlling sorption of Cd is well documented. By experimentally eliminating the dominant effect of pH, Holm et al. allowed for identification of soil components that may be important in controlling Cd sorption in whole soil samples. Among the different soil parameters and components present only C content and cation exchange capacity were found to be significant parameters for the 49 soils studied. None of the individual types of clay silicates and oxides were important in describing the variation in Cd distribution coefficients. Results suggest equilibrium pH is the dominant parameter describing Cd soil sorption and that even elimination of the pH effect combined with a very detailed characterization of the different soil components cannot add substantially to an explanation of the variation in Cd soil distribution coefficients.
P.E. Holm (peho{at}kvl.dk)
Correlation of Cadmium Distribution Coefficients to Soil Characteristics. J. Environ. Qual. 32:
138–145.
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Do Biosolids Accumulate in Soil?
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Farmers participating in a municipal biosolids land application program raised questions about accumulation of metals in soils and potential uptake of metals by forages. Fields that received biosolids before implementation of the USEPA Part 503 probably received biosolids with metal concentrations above current USEPA Part 503 regulatory limits. Although soil concentrations in these fields were well below the Part 503 cumulative limit, elevated Cd was seen in 3 out of 10 fields and the Cu to Mo ratio had decreased compared with fields that never received biosolids. Fields that received biosolids after Part 503 did not have elevated metals in the soil, and forage quality was similar to fields that never received biosolids.
J.W. Gaskin (jgaskin{at}engr.uga.edu)
Long-Term Biosolids Application Effects on Metal Concentrations in Soil and Bermudagrass Forage. J. Environ. Qual. 32:
146–152.
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Treating Metal-Contaminated Soils
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The effectiveness of two forms of phytate (Na–phytate and Ca–phytate) and hydroxyapatite (HA) to immobilize soluble metals (U, Ni, etc.) in contaminant soils was evaluated in a batch equilibration study. Hydroxyapatite and the sparingly soluble Ca–phytate performed quite similarly in reducing the solubility of U and Ni, as well as several other metal contaminants. Soluble Na–phytate, however, reduced the solubility of some metals at the lowest treatment level and increased solubility at the higher treatment levels, illustrating the importance of metal to ligand ratio in controlling metal–phytate solubility.
J. Seaman (Seaman{at}srel.edu)
In Situ Treatment of Metals in Contaminated Soils with Phytate. J. Environ. Qual. 32:
153–161.
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Riparian Buffer Removes Nitrate along Streams
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The Willamette Valley of Oregon has extensive areas of poorly drained, commercial grass seed lands. Little is known about the ability of riparian areas in these settings to reduce nitrate in water draining from grass seed fields. Wigington et al. examined shallow ground water at two study sites with similar soils and hydrology but contrasting riparian vegetation along an intermittent stream that drains perennial ryegrass fields. Results showed that even though there is great potential for NO3–N to be reduced as water moves through the noncultivated riparian zone with grass/herbaceous vegetation, the potential was not fully realized because only a small proportion of the stream flow interacted with riparian zone soils. Consequently, effective NO3 water quality management in poorly drained landscapes similar to the study watershed is primarily dependent on implementation of sound agricultural practices within grass seed fields and is less influenced by riparian zone vegetation.
P.J. Wigington
(wigington.jim{at}epa.gov)
Nitrate Removal Effectiveness of a Riparian Buffer along a Small Agricultural Stream in Western Oregon. J. Environ. Qual. 32:
162–170.
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Diuron and Its Products Detected in Stream Water
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A field study was designed to investigate the occurrence and distribution of diuron and its transformation products at a poorly drained field site located along an intermittent tributary of Lake Creek in the southern Willamette Valley of Oregon. Diuron and its transformation product 3-(3,4-dichlorophenyl)-1-methylurea (DCPMU) were the only significant residues detected. Diuron and DCPMU detected in soil before the second season's application indicated the persistence of diuron and DCPMU from the previous year's application. Surface runoff during the rainy season removes only a very small amount (<1%) of the applied herbicide. In addition, no evidence was obtained for the downward transport of diuron or its transformation products to deep ground water.
J. Field (Jennifer.Field{at}orst.edu)
Diuron Occurrence and Distribution in Soil and Surface and Ground Water Associated with Grass Seed Production. J. Environ. Qual. 32:
171–179.
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Land Use Influences Water Quality
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Land use and land use change have been shown to have significant impacts on water quality in aquatic ecosystems. If the linkages between land use and water quality can be characterized, then changes in aquatic ecosystems due to land use change can be anticipated, and the early onset of degraded water quality in aquatic ecosystems can be mitigated. Wayland et al. related the major solute chemistry of streams to land use through specific watershed scale sampling protocols, geographic information systems (GIS), and statistical analyses. Results show this method can identify relationships between land use and stream chemistry, even in aquatic ecosystems that are relatively unimpaired by human activities. Linkages between land use and water quality were better defined by combining data collected from several sampling events. These results begin to provide a framework for environmental monitoring using a set of chemical indicators most commonly measured in water quality studies.
D.T. Long (long{at}msu.edu)
Identifying Relationships between Baseflow Geochemistry and Land Use with Synoptic Sampling and R-Mode Factor Analysis. J. Environ. Qual. 32:
180–190.
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Sycamore Trees Slow Down Nitrogen Cycle
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In Mediterranean systems, the mobilization of N in the forest floor is parsimonious and occurs in pulses. Bernal et al. describe the N cycle in the forest floor of a Mediterranean riparian area afforested with sycamore. Dentrification is practically nil due to the low soil water amount, and the mobilization of N occurs mainly in summer and autumn after rain events. The toughness of sycamore leaves provokes the accumulation of N in particulate form that slows down the transfer of N to the soil. Due to their shape and low permeability, wind blow easily scours the sycamore leaves directly to the stream. The type of riparian trees in Mediterranean zones has a major importance in the ability of this system to retain N.
S. Bernal
(sbernal{at}porthos.bio.ub.es)
Leaf Litter Dynamics and Nitrous Oxide Emission in a Mediterranean Riparian Forest: Implications for Soil Nitrogen Dynamics. J. Environ. Qual. 32:
191–197.
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Carbon Isotope Ratios Can Explain Ecosystem Function
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Tropical ecosystems often become infertile shortly after conversion from native vegetation to agricultural management. A key unknown is how long the soil organic matter (SOM) produced by the native vegetation is actively cycled by the microbial community associated with the new land use. Burke et al. show stable C isotope ratios of phospholipid fatty acids (PLFAs) can be used to assess the contribution of native SOM to ecosystem function in systems that have undergone a vegetation shift from the C3 photosynthetic pathway to the C4 pathway at known times in the past. Further, PLFA composition can be used to elucidate general changes in soil microbial community structure associated with land use conversion.
R.A. Burke (burke.roger{at}epa.gov)
Stable Carbon Isotope Ratio and Composition of Microbial Fatty Acids in Tropical Soils. J. Environ. Qual. 32:
198–206.
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Phosphorus and Sediment Loss are Related to Carbon Quality
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The concentration and load of P and sediment lost in overland flow are affected by soil C concentration and quality. McDowell and Sharpley show sediment transport is inversely related to the degree of aggregation and hydrolyzable carbohydrate. Further, due to increased aggregation and decreased surface soil slaking, soil with a small amount of manure applied (up to 50 kg P ha-1 dairy manure) lost less P in overland flow than untreated soil. Manure application at low rates (<50 kg P ha-1) imparts physical benefits to surface soil, which decrease P loss potential. However, at greater application rates, this effect is negated and P transport is appreciably greater than that from untreated soil.
R.W. McDowell
(richard.mcdowell{at}agresearch.co.nz)
The Effects of Soil Carbon on Phosphorus and Sediment Loss from Soil Trays by Overland Flow. J. Environ. Qual. 32:
207–214.
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Chlordane Residues in Compost
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Technical chlordane usage in the USA has been outlawed since 1988, although this and many other persistent organic pollutants (POP) remain in the environment for decades. Lee et al. quantitate this POP in both commercial and municipal compost products, and provide support for a vegetative feedstock contribution, over and above contaminated soil, in the final compost product. Calculations based on the data indicate compost contributes to anthropogenic cycling of chlordane through the biosphere.
M. Incorvia Mattina
(maryjane.mattina{at}po.state.ct.us)
Persistent Organic Pollutants in the Environment: Chlordane Residues in Compost. J. Environ. Qual. 32:
224–231.
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Studying Molecular-Level Chemical Sorption
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Molecular-level forces, in addition to hydrophobic effects, can be important in sorption of electron-rich aromatic compounds to geosorbents. Nuclear magnetic resonance (NMR) relaxation time measurements provide an appropriate way to study these "new" binding forces in sorption processes. A better understanding of mechanisms for sorption of nonionic organic chemicals (NOCs) can be obtained through further studies of these molecular-level forces.
D. Zhu (d0z7577{at}yahoo.com)
Molecular-Level Investigation of Monaromatic Compound Sorption to Suspended Soil Particles by Deuterium Nuclear Magnetic Resonance. J. Environ. Qual. 32:
232–239.
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Soil Structures Influence Contamination Level
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Structures of soil organic matter (SOM) strongly affect sorption of organic compounds in soil. However, recent reports emphasize the role of only either aromatic or aliphatic components of SOM. In this study, soil humin is highly aliphatic, but has the highest nonlinear isotherm and sorption capacity as compared with soil humic acid and whole soil sample. A new structural conformation for aliphatic domains of SOM is proposed. In contrast, lignin is very aromatic and also has nonlinear isotherm and high sorption capacity. Both elevated temperatures and co-solvent increase the isotherm linearity of soil humin and lignin. Gunasekara and Xing conclude both components can affect sorption capacity and nonlinearity depending on the nature, origin, and diagenic age of SOM samples.
B. Xing (bx{at}pssci.umass.edu)
Sorption and Desorption of Naphthalene by Soil Organic Matter: Importance of Aromatic and Aliphatic Components. J. Environ. Qual. 32:
240–246.
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Local Weather Influences Crop Yield
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Increased surface runoff and nitrate (NO3) flux to the Mississippi River, which has been linked to escalating N fertilizer use on Midwest U.S. farms since the 1950s, illustrate the need to identify agricultural management practices that improve water quality and maintain food production. Kucharik and Brye examined the simultaneous response of NO3 leaching losses and maize yield to varied fertilizer N management in southern Wisconsin using a combination of field observations, climate data, and a process-based biosphere model. Simulations of future N fertilizer management scenarios (±30% from optimum) showed nonlinear relationships existed between changes in fertilizer use, NO3–N leaching losses, and crop yield given current climate variability. Simulated changes in NO3–N leaching were generally greater in magnitude than fertilizer-use changes, but crop yields were only marginally affected. During several years, local weather had a much greater effect on yield than changes in N fertilizer use.
C.J. Kucharik
(kucharik{at}facstaff.wisc.edu)
Integrated BIosphere Simulator (IBIS) Yield and Nitrate Loss Predictions for Wisconsin Maize Receiving Varied Amounts of Nitrogen Fertilizer. J. Environ. Qual. 32:
247–268.
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Methane Produced from Foraging Beef Cattle
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Methane (CH4) produced by fermentation in the rumen of cattle may play a role in global warming scenarios. Best management practices (BMP) grazing was compared to continuous grazing on CH4 production in several Louisiana forages. When the reduction of CH4 emissions from beef cattle is linked to improved grazing management strategies there is substantial improvement in total beef production efficiency. Using BMP significantly reduced the emission of CH4 per unit of animal weight gain. Management intensive grazing (MIG) is a BMP that offers the potential for more efficient utilization of grazed forage crops via controlled rotational grazing and more efficient conversion of forage into meat and milk. Projected CH4 annual emissions reflect a 22% reduction from BMP when compared to continuous grazing in this study.
A. DeRamus
(had2299{at}louisiana.edu)
Methane Emissions of Beef Cattle on Forages: Efficiency of Grazing Management Systems. J. Environ. Qual. 32:
269–277.
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Measuring Changes in Soil Carbon
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The potential to sequester atmospheric C in agricultural and forest soils to offset greenhouse gas emissions has generated interest in measuring changes in soil C resulting from changes in land management. However, small changes relative to total amounts of soil C and inherent spatial heterogeneity of soil C limit the ability to detect changes over time. A sampling protocol in which six cores are collected at each of five microplots, enabled detection on the order of 2.0 Mg C ha-1 in tilled soils in Tennessee by collection and analysis of cores from at least five microplots; two microplots in the forested system in Tennessee are required to detect differences of the same magnitude. More spatial heterogeneity in two forested sites in Washington increased the minimum detectable difference, but these systems—consisting of low C content sandy soil with irregularly distributed pockets of organic C in buried logs—are likely to rank among the most spatially heterogeneous of systems. The tested sampling design is relatively efficient for homogeneous soils and a different design is required for detection of small changes in more heterogenous soils, but our results indicate consistent intramicroplot differences at all of our sites will enable detection of much more modest changes if the same microplots are resampled.
R.T. Conant
(conant{at}nrel.colostate.edu)
Spatial Variability of Soil Carbon in Forested and Cultivated Sites: Implications for Change Detection. J. Environ. Qual. 32:
278–286.
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Phosphorus Speciation in a Sandy Grassland Soil
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Risks related to leaching of P are known to depend on speciation of P in soil. However, information on changes in inorganic and organic P fractions in soils exposed to long-term application with animal manure is still scarce. Koopmans et al. determined the effect of various fertilization regimes of grassland on P speciation in NaOH–Na2EDTA and water extracts of the top 5 cm of sandy soils using wet chemical analysis and liquid state 31P nuclear magnetic resonance (NMR) spectroscopy. After 11 yr of treatment with either N–P–K fertilizer or animal manures, inorganic P increased considerably in both NaOH–Na2EDTA and water extracts, while organic P remained relatively constant. Phosphorus-31 NMR analysis indicated orthophosphate monoesters were the main organic P compounds. Results suggest long-term application of animal manure caused an increase of the potential risk of mobilization of inorganic P in the top 5 cm of these soils.
G.F. Koopmans
(g.f.koopmans{at}alterra.wag-ur.nl)
Wet Chemical and Phosphorus-31 Nuclear Magnetic Resonance Analysis of Phosphorus Speciation in a Sandy Soil Receiving Long-Term Fertilizer or Animal Manure Applications. J. Environ. Qual. 32:
287–295.
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Cryptosporidium parvum Oocysts and Giardia lamblia Cysts Attach to Soil Particles
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Information about transport of C. parvum oocysts and G. lamblia cysts is essential for actual risk assessment and development of effective control practices. Several studies have suggested that attachment to soil particles is not likely to occur, but the hypothesis has not been well tested, partly because enumeration of C. parvum oocysts or G. lamblia cysts [written as (oo)cysts] in the presence of soil has been difficult. This difficulty was overcome by using a combination of flow cytometry, and epifluorescence and confocal microscopy to enumerate (oo)cysts in the presence of natural soil particles. Results show oppositely charged beads and (oo)cysts attach, while like-charged beads, (oo)cysts, and soil particles do not attach, suggesting electrostatic forces govern the interaction between (oo)cysts and natural soil particles. Therefore, when (oo)cysts have been entrained in overland flow (i.e., runoff), they will travel freely in the water, and not as part of the particulate sediment load.
J. Boll (jboll{at}uidaho.edu)
Evaluation of Attachment of Cryptosporidium parvum and Giardia lamblia to Soil Particles. J. Environ. Qual. 32:
296–304.
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Temporal Variability of Escherichia coli Ribotypes
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Ribotype profiling of E. coli is one of several genotypic methods with potential to determine the host origin of fecal bacteria in surface waters. As a source tracking tool, it requires a host origin database to identify environmental isolates. Jenkins et al. determined the effect temporal variability of E. coli ribotypes would have on a host origin database for beef cattle. Isolates of E. coli were obtained from fresh feces of six randomly chosen Black Angus steers at four different sampling times (for a total of 24 different steers). Results of ribotyping 451 isolates indicated apparent turnover and extensive diversity of ribotypes and suggest the necessity of ribotyping a large number (
900) of E. coli isolates per host to establish a host origin database that is independent of temporal variability or complete enough to be effective.
M.B. Jenkins
(mjenkins{at}arches.uga.edu)
Putative Temporal Variability of Escherichia coli Ribotypes from Yearling Steers. J. Environ. Qual. 32:
305–309.
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Phosphorus Levels in Soil and Runoff
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Soil test P levels in cropland often exceed those needed for optimum crop yields, potentially increasing P concentrations in runoff and hastening eutrophication of lakes and streams. Andraski and Bundy investigated the effect of soil type, tillage, recent manure additions, soil P extraction method, and soil sampling depth on the relationship between soil test P level and P concentration in runoff from corn production systems. In 213 observations, good relationships occurred between soil test P level and dissolved P concentration in runoff for most of the agronomic and environmental tests and sampling depths used. High corn residue surface cover, recent additions of manure, and low soil permeability influenced these relationships. More than 80% of the total P concentration in runoff was in the particulate P form and was strongly correlated to sediment loss, which was a function of surface cover on the moderately permeable/well-drained soils and of soil test P level and on the less permeable/poorly drained soils. In general, current agronomic soil P tests should provide sufficient information when used as a part of a comprehensive approach for identifying critical land areas subject to potentially high P losses in surface runoff.
T.W. Andraski (andraski{at}wisc.edu)
Relationships between Phosphorus Levels in Soil and in Runoff from Corn Production Systems. J. Environ. Qual. 32:
310–316.
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Reducing Chromium in the Vadose Zone
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Oliver et al. assessed the potential for microbially mediated reduction/immobilization of Cr(VI) to insoluble Cr(III) under unsaturated, vadose zone conditions. Batch microcosm and unsaturated flow column experiments showed native microbial communities in a subsurface sediment with no prior Cr(VI) exposure were capable of Cr(VI) reduction and Cr reduction was enhanced by adding high levels of nitrate and organic C. All of the immobilized Cr was in the form of Cr(III), as shown by XANES analysis. This suggests biostimulation of microbial Cr(VI) reduction in vadose zones by nutrient amendment is a promising strategy, and immobilization of close to 100% of Cr contamination could be achieved in a thick vadose zone.
T.L. Kieft (tkieft{at}nmt.edu)
Microbial Reduction of Hexavalent Chromium under Vadose Zone Conditions. J. Environ. Qual. 32:
317–324.
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Measuring Sedimentation in Wetlands
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Sedimentation measurement techniques and patterns of short-term sedimentation were examined in two 1-ha replicate created freshwater marshes in central Ohio, USA. Short-term (1 yr) sediment accumulation above feldspar, clay, glitter, and sand artificial marker horizons was compared at different water depths and distances from wetland inflow. A sediment budget estimated sediment retention of about 740 g m-2 yr-1 per wetland (43% removal rate), yet gross sediment accumulation was 36 000 g m-2 yr-1 measured by marker horizons. Sedimentation rates in deep, open water areas were significantly higher than in shallow, vegetated areas for both wetlands. Contrary to the expected spatial distribution, sedimentation was highly variable within the wetlands, suggesting bioturbation and turbulence may cause significant resuspension or high hydrologic loads may distribute sediments throughout the basins.
W.J. Mitsch (mitsch.1{at}osu.edu)
Patterns of Short-Term Sedimentation in a Freshwater Created Marsh. J. Environ. Qual. 32:
325–334.
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Predicting Phosphorus Amounts in Wetlands
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Litaor et al. tested the usability of the common soil-P index known as degree of P saturation (DPS) in an altered semiarid wetland ecosystem. They ascertained the spatial distribution of the DPS using sequential Gaussian simulation technique that provides a better assessment of the spatial uncertainty compared with the more traditional kriging technique. The spatial analysis suggested all the Histosols have a low probability (<10%) of exceeding the commonly used threshold of 0.25. The areas characterized by organo-mineral soils, such as hydromorphic Vertisols and marl gley soils, have a high probability (>60%) of exceeding the threshold value of 0.25. The ability to predict dissolved P concentrations in ground water based on the DPS values is difficult because of the preferential flow characteristics in this altered wetland, but even in cases of significant preferential flow, the residence time of the water within the field may last for many hours and the soil DPS may have useful environmental implications.
M.I. Litaor (litaori{at}telhai.ac.il)
Spatial Analysis of Phosphorus Sorption Capacity in a Semiarid Altered Wetland. J. Environ. Qual. 32:
335–343.
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Documenting Water Quality Changes in the Everglades
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Childers et al. documented decadal changes associated with water quality in oligotrophic Everglades wetlands by resampling soils and macrophytes along four transects in 1999 that were originally sampled in 1989. They found that water quality impacts worsened during this time in areas of the northern Everglades. In contrast, areas well south of the Everglades Agricultural Area did not decline during this time. Regular sampling of these transects will continue to be an important tool for long-term management and restoration of the Everglades.
D.L. Childers (childers{at}fiu.edu).
Decadal Change in Vegetation and Soil Phosphorus Patterns across the Everglades Landscape. J. Environ. Qual. 32:
344–362.
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Visualizing Water Flow Pathways
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Visualizing on-site water-flow pathways in soils under field conditions is important in water and pollutant transport studies. Wu and Lu developed a spray method to visualize the bromide water tracer in soil profiles. The water flow patterns appear in highly visible Prussian blue color after the soil profile is sprayed with a bromide indication solution. An alternative spray method, which utilizes iodide ion as a water tracer and a corresponding iodide indication solution, was also developed and recommended for use in soils with high chloride background.
L. Wu (Laowu{at}mail.ucr.edu)
Visualizing Bromide and Iodide Water Tracer in Soil Profiles by Spray Methods. J. Environ. Qual. 32:
363–367.
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Monitoring Escherichia coli with Petrifilm Plates
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A new method for measuring bacterial contamination of environmental waters is described in this multilaboratory study by Vail et al. 3M Petrifilm E. coli plates were compared with standard methods for counting E. coli in ambient waters. Petrifilm plates were convenient to use, and counts were highly correlated with the standard methods. The main disadvantage of the Petrifilm plates is that only 1 mL of water can be assayed directly, giving less precise measurements in samples containing low numbers of E. coli. However, their reliability and relatively low cost make Petrifilm plates suitable for citizen-based and educational monitoring, particularly when used to screen sites for more extensive testing by standard methods.
J.L. Ram (jeffram{at}med.wayne.edu)
Enumeration of Waterborne Escherichia coli with Petrifilm Plates: Comparison to Standard Methods. J. Environ. Qual. 32:
368–373.
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