Journal of Environmental Quality 31:1417-1423 (2002)
© 2002 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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Forest Stress Detection through Chlorophyll Analysis
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Chlorophyll concentration and fluorescence are indicators of vegetation stress that can be measured with hyperspectral remote sensing methods. Zarco-Tejada et al. describe leaf and canopy radiative transfer models to simulate hyperspectral reflectance as a function of leaf biochemistry, chlorophyll fluorescence, and canopy structure in sugar maple. Experiments were conducted at laboratory and airborne levels using the Compact Airborne Spectrographic Imager (CASI) sensor for airborne data collection from two sites of sugar maple of high and low stress condition, showing a double-peak feature on canopy derivative reflectance in the red edge spectral region attributed to chlorophyll fluorescence and pigment content effects. The Derivative Chlorophyll Index (DCI) was developed, calculated as D705/D722, where Dx is the derivative reflectance measured at wavelength X. The proposed dCi optical index is a function of the combined effects of fluorescence and chlorophyll content, and is used in this study to detect forest stress using airborne hyperspectral imagery.
P.J. Zarco-Tejada
(zarco{at}terra.phys.yorku.ca)
Vegetation Stress Detection through Chlorophyll a + b Estimation and Fluorescence Effects on Hyperspectral Imagery. J. Environ. Qual. 31:
1433–1441.
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Leaf Optics Indicate Chlorophyll Concentration
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Environmental conditions that inhibit plant growth frequently cause subtle to dramatic decreases in leaf chlorophyll content. Leaf optical properties in the visible spectrum depend strongly on leaf chlorophyll concentration and thus may serve as relative indicators of plant vigor and environmental quality. Carter and Spiering show that leaf reflectance, transmittance, and absorptance corresponded most precisely with chlorophyll concentration at wavelengths near 700 nm. Results were based on integrating sphere measurements of green to yellow leaves sampled from five species of vascular plants. The incorporation of a spectral band centered near 700 nm in chlorophyll meters and remote sensors would be expected to yield tools that are useful in evaluating plant responses to the environment.
G.A. Carter (gcarter{at}ssc.nasa.gov)
Optical Properties of Intact Leaves for Estimating Chlorophyll Concentration. J. Environ. Qual. 31
1424–1432.
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Spectral Reflectance Linked to N Status in Cotton
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Remote sensing has potential to assess cotton nutrient status, and thereby reduce off-site effects of excessive N fertilizer use. Detection of N status requires identification of spectral wavebands in which vegetation reflectance is responsive to unfavorable growth conditions. Read et al. find that reflectance measures involving the violet or blue region of the spectrum (400–450 nm) and the more commonly featured red-edge region (680–720 nm) are most suitable for remote assessment of chlorophyll, and hence N in cotton. Results are based on hyperspectral measurements at a resolution of 5 nm obtained from leaves and canopies grown under restricted N supply at various growth stages. Changes in cotton reflectance due to N stress can provide an effective tool for managing crop N inputs, either on a site-by-site basis or before visible stress symptoms.
J.J. Read
(jjread{at}msa-msstate.ars.usda.gov)
Narrow-Waveband Reflectance Ratios for Remote Estimation of Nitrogen Status in Cotton. J. Environ. Qual. 31:
1442–1452.
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Spectral Reflectance of Salt-Affected Soils
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Rapid identification and large-scale mapping of salt-affected lands using remote sensing techniques will help improve salinity management in watersheds and ecosystems. Howari et al. examined spectral reflectance of soils treated with saline solutions containing NaCl, NaHCO3, Na2SO4, and CaSO4·2H2O using a high-resolution spectroradiometer. They found hyperspectroscopy can be used to identify the presence of primary diagnostic spectral features of gypsum, nahcolite, thenardite, and halite crusts. The findings can be applied in investigating new-generation airborne hyperspectral data.
F. Howari (f-howari{at}tamu.edu)
Spectral Properties of Salt Crusts Formed on Saline Soils. J. Environ. Qual. 31:
1453–1461.
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Environmental Mapping Based on Spatial Variability
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Novel probabilistic models of piece-wise-homogeneous images are used in environmental mapping to segment real images. Any "image–land cover map" pair constitutes an example of a Markov random field specified by a joint Gibbs probability distribution of images and maps. A proposed model takes into account the local interactions between pixels assumed to represent the properties of environmental objects. Experiments were carried out with the images of two unique reservoirs of high-quality pure water in Siberia—Lake Baikal and Lake Teletskoye. Environmental mapping is realized within a unified framework of Bayesian decision.
N. Kovalevskaya
(knm{at}iwep.secna.ru)
Environmental Mapping Based on Spatial Variability. J. Environ. Qual. 31:
1462–1470.
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Use of a Phosphorus Indexing Tool
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In 1998, the Maryland legislature mandated nitrogen and phosphorus nutrient management planning for nearly all of Maryland's commercial agricultural operations. State regulations required that a phosphorus indexing tool (P Index) be used for determining the potential for P losses from agricultural land. The Maryland P Site Index (PSI) was evaluated on 646 state-representative field sites. Of the representative fields, 69% were determined to have a low P loss rating, 19% were in the medium P loss rating category, 8% were determined to be high risk for P loss, and 4% rated as very high P loss potential. Fifty-five percent of the fields evaluated had soil test P levels less than the 75 mg kg-1 Mehlich-1 P environmental threshold established by state regulations. The Maryland PSI will be deployed for use in constructing farm nutrient management plans well before its predictive capabilities can be objectively and rigorously validated. In the mean time, the Maryland PSI should function adequately as a tool to assist in the prioritization of field P loss risk potential.
F.J. Coale (fc26{at}umail.umd.edu)
Accelerated Deployment of an Agricultural Nutrient Management Tool: The Maryland Phosphorus Site Index. J. Environ. Qual. 31:
1471–1476.
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Phytostabilization of Trace Elements in Mine Tailings
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Phytostabilization may limit the leakage of trace elements from mine tailings. Stoltz and Greger studied the growth, element uptake, and impact on mine tailings of two cottongrass species (Eriophorum angustifolium and E. scheuchzeri) with limed and unlimed submersed mine tailings. Plant establishment had little effect on element release in the limed tailings; only Zn levels were increased. However, in unlimed tailings, plant establishment increased pH and reduced levels of heavy metals and As in the drainage water. Thus, plants can be used for phytostabilization of metals in mine tailings and the lime treatment of acid mine drainage can be reduced.
E. Stoltz (Eva.Stoltz{at}botan.su.se)
Cottongrass Effects on Trace Elements in Submersed Mine Tailings. J. Environ. Qual. 31:
1477–1483.
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Gaseous Emissions of Contaminants in Burning of Tires
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A study of the environmental impact of the use of scrap tires as a fuel substitute was conducted at a cement plant. The use of a combination of tires and coal, as opposed to the use of only coal, caused variations in the rates of emission of pollutants. The study recorded an increase in the emission rates for CO, SO2, and HCl, and a decrease for NOx, when tires were included. The rate of emission for metals increased for Fe, Al, Zn, Pb, Cr, Mn, and Cu, and decreased for Hg. The emission rate of organic compounds dropped by 14% for polycyclic aromatic hydrocarbons, 8% for naphthalene, 37% for chlorobenzene, and 45% for dioxins/furans. The maximum concentrations at ground level (after atmospheric dispersion) experienced an increase of 12 to 24% in particulate matter, increases in CO, SO2, HCl, Fe, Al, Zn, and Pb, and decreases in NOx, polycyclic aromatic hydrocarbons, naphthalene, chlorobenzene, and dioxins/furans. Results showed the maximum ground-level concentrations were well within environmental standards.
F. Carrasco (felix.carrasco{at}udg.es)
Gaseous Contaminant Emissions as Affected by Burning Scrap Tires in Cement Manufacturing. J. Environ. Qual. 31:
1484–1490.
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Emission of Gases from Pig Slurry Applied to a Pasture
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Much animal manure is being applied to small land areas close to animal confinements, with the result that the environment is affected by emissions of ammonia (NH3), methane (CH4), and nitrous oxide (N2O). Sherlock et al. show ammonia was lost at a fast rate immediately after slurry application, but the rate of loss declined quickly thereafter. Total NH3 losses from the treated pasture amounted to 57 kg N ha-1 (22.5% of TAN applied). Methaneemission was highest immediately after application, as dissolved CH4 was released from the slurry. Emission then continued at a low rate for 
7 days and the net emission of CH4 was 1052 g C ha-1 (0.08% of C applied). Nitrous oxide emission was low for the first 14 days after slurry application, then showed peaks of emission and emission finally reached background levels after 90 days. Nitrous oxide emission amounted to 7.6 kg N ha-1 (2.1% of N applied).
S.G. Sommer
(Sveng.sommer{at}agrsci.dk)
Ammonia, Methane, and Nitrous Oxide Emission from Pig Slurry Applied to a Pasture in New Zealand. J. Environ. Qual. 31:
1491–1501.
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Treatment of 2,4-D Polluted Soil Using Free and Immobilized Laccase
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The ability of phenoloxidases to polymerize phenols and mediate covalent binding of these chemicals to humic substances is well documented; little is known, however, about the performance of phenoloxidases in soil. Ahn et al. report phenols can be efficiently transformed in soil by both free and immobilized laccase from Trametes villosa. In general, immobilized laccase performed better than free laccase. However, the amount of activity lost with immobilization was roughly the same as the amount of free laccase needed to maintain the same level of remediation. Also, taking into account the high cost of immobilization, using free Trametes villosa laccase for soil remediation appeared to be a more practical option.
J.-M. Bollag (JMBollag{at}psu.edu)
Treatment of 2,4-Dichlorophenol Polluted Soil with Free and Immobilized Laccase. J. Environ. Qual. 31:
1509–1515.
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Sewage Sludge Compost and Vineyards
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Biosolids are applied to crops to supply organic matter and N. However, there is concern this practice can increase concentrations of macronutrients and heavy metals in soil, and leaching can be high on perennial crops that have low nutrient requirements. The environmental hazard of sewage sludge compost applied on a French vineyard was evaluated in a 2-year study. The experiment showed an increase of soil organic matter without heavy metal contamination. However, N and P increased and some migrated in the soil. The environmental risks of sewage sludge amendment on perennial crops is discussed, and a maximum rate for application on vineyards is proposed. N. Korboulewsky (nathalie.korboulewsky{at}univ.u-3mrs.fr) Environmental Risks of Applying Sewage Sludge Compost to Vineyards: Carbon, Heavy Metals, Nitrogen, and Phosphorus Accumulation. J. Environ. Qual. 31:
1522–1527.
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Acidic Mine Waste Reclamation Possible without a Soil Cover
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Acidic mine waste from a high elevation gold mine (3500 m) in southwestern Colorado can be directly revegetated when properly neutralized, fertilized, and amended with organic matter. Winter and Redente found treatments using mushroom compost as an organic amendment and lime as a neutralizing agent supported productive plant communities after four growing seasons that had similar levels of production as treatments using topsoil to cover the mine-waste material. These results provide an alternative reclamation approach for highly acidic mine waste and soil materials under extreme environmental conditions and where topsoil availability is limited or nonexistent.
E.F. Redente
(edr{at}cnr.colostate.edu)
Reclamation of High-Elevation, Acidic Mine Waste with Organic Amendments and Topsoil. J. Environ. Qual. 31:
1528–1537.
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Statistical Techniques Useful in Identifying Sources of Nitrate in Ground Water
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Classification trees, statistical techniques that have been used during the last 15 to 20 years for medical diagnosis and for decision analysis in a variety of nonenvironmental science disciplines, were used to determine the most important water-quality variables in identifying sources of nitrate contamination in shallow ground water from the Costal Plain of North Carolina. Ground water samples were collected from 49 wells contaminated with nitrate from one of five sources (hog lagoon wastes, inorganic fertilizer on row crops, inorganic fertilizer on golf courses, septic system wastes, and chicken wastes). Two predictive models were formulated, where Model 1 was derived from data from 47 wells having 32 water quality variables including 
15N and Model 2 was derived from data from 49 wells having the same variables except 15N. Variables determined to be important for source identification included 15N, Na + K, Na/K ratio, Zn, and Ca/Mg ratio, with overall classification success for both models better than 80% for all five source categories and 71 to 100% success for individual categories. Model 2 correctly classified 17 ground water samples, collected independently for previous studies, into the known contamination source categories associated with each water sample.
T.B. Spruill (tspruill{at}usgs.gov)
Application of Classification-Tree Methods to Identify Nitrate Sources in Ground Water. J. Environ. Qual. 31:
1538–1549.
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Bacterial Tolerance Levels and Forms of Copper and Zinc
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The effects of various fractions of Cu and Zn on soil bacteria were evaluated by an indicator—the heavy metal tolerance level of the bacterial community, shown as IC50, in soil samples collected near a mine. The sequence of effects of various fractions of Cu and Zn on the IC50s, evaluated with correlation analysis, were: total concentrations in the soils <<< exchangeable fractions < calculated free metal ion activities = total concentrations in the soil solutions. The estimated free-Cu and -Zn in the soil solutions have more importance than complexed forms in determining bacterial resistance.
K. Saeki (ksaeki{at}agr.kyushu-u.ac.jp)
Relationships between Bacterial Tolerance Levels and Forms of Copper and Zinc in Soils. J. Environ. Qual. 31:
1570–1575.
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Changes of Cadmium Distribution in Soil Induced by Phytoextraction
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The chemical form of heavy metals in soils influences strongly the uptake by plants used in phytoextraction. In an acidic soil, Hammer and Keller show by sequential extraction that major changes in metal compartmentation in the rhizosphere of the Cd and Zn hyperaccumulator Thlaspi caerulescens occur in the exchangeable and organic matter–bound Cd pools. In contrast, with a calcareous soil most Cd was bound to carbonates, which hindered uptake by the hyperaccumulator. The metal-tolerant Salix viminalis influenced only marginally the metal pool system in both soils because of its relatively low total metal uptake. It was concluded organic matter–bound Cd may constitute a significant part of the bioavailable pool of Cd in soils and Thlaspi caerulescens was able to deplete significant Cd from this pool. It is thus a potential candidate for efficient phytoextraction of Cd in acidic soils. However, generalization will be possible only after more research is performed to predict to what extent the Cd pool system can be altered by plants in other situations.
D. Hammer
(daniel.hammer{at}epfl.ch)
Changes in the Rhizosphere of Heavy Metal-Accumulating Plants as Evidenced by Chemical Extractants. J. Environ. Qual. 31:
1561–1569.
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Sewage Sludge and Long-Term Impact on Trace Metal Budget
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Application on agricultural land is commonly used for sewage sludge disposal, because it is low cost and reclaims some of the fertilizer value of nutrients in the material. Uncertainty exists about the long-term fate of polluting trace metals contained in sewage sludge. Keller et al. report that in an experiment where they applied liquid sewage sludge repeatedly to a brown soil/meadow system (undisturbed lysimeters), the main long-term risk was the rapid increase in trace metal concentrations in the topsoil, which if not controlled, may eventually lead to toxic levels in herbage. Removal in plant material was much greater than losses in drainage water. The impact of sewage sludge on drainage water composition was for limited periods and affected only NO3–N, Cl, Ni, and Cu concentrations. Particulate matter and dissolved organic C leaching appeared to be additional risk factors for metal leaching. After 37 months of monitoring, some metal concentrations had not returned to background levels. The experiment points out the necessity of both short- and long-term monitoring when applying sewage sludge to soils.
C. Keller (catherine.keller{at}epfl.ch)
Trace Metal Leaching through a Soil–Grassland System after Sewage Sludge Application. J. Environ. Qual. 31:
1550–1560.
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Assessing the Spatial Distribution of Urban Soil Contaminants
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Forest Stress Detection through...
Leaf Optics Indicate Chlorophyll...