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
 |
Forest Stress Detection through Chlorophyll Analysis
|
|---|
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.
|
Leaf Optics Indicate Chlorophyll Concentration
|
|---|
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.
|
Spectral Reflectance Linked to N Status in Cotton
|
|---|
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.
|
Spectral Reflectance of Salt-Affected Soils
|
|---|
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.
|
Environmental Mapping Based on Spatial Variability
|
|---|
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.
|
Use of a Phosphorus Indexing Tool
|
|---|
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.
|
Phytostabilization of Trace Elements in Mine Tailings
|
|---|
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.
|
Gaseous Emissions of Contaminants in Burning of Tires
|
|---|
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.
|
Emission of Gases from Pig Slurry Applied to a Pasture
|
|---|
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.
|
Treatment of 2,4-D Polluted Soil Using Free and Immobilized Laccase
|
|---|
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.
|
Sewage Sludge Compost and Vineyards
|
|---|
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.
|
Acidic Mine Waste Reclamation Possible without a Soil Cover
|
|---|
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.
|
Statistical Techniques Useful in Identifying Sources of Nitrate in Ground Water
|
|---|
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.
|
Bacterial Tolerance Levels and Forms of Copper and Zinc
|
|---|
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.
|
Changes of Cadmium Distribution in Soil Induced by Phytoextraction
|
|---|
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.
|
Sewage Sludge and Long-Term Impact on Trace Metal Budget
|
|---|
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.
|
Assessing the Spatial Distribution of Urban Soil Contaminants
|
|---|
Mapping the spatial distribution of a contaminant is an integral component of risk assessment and may be achieved using geostatistical techniques such as kriging. These techniques provide a means of estimating either the value of a soil attribute at locations between samples, or the probability that the attribute value will exceed a given threshold at a particular location. Cattle et al. compared multiple indicator kriging and kriging with the CDF of order statistics for their ability to predict the probability of exceeding a contamination threshold and produce the best map to delineate contaminated from noncontaminated soil. Both types of kriging were conducted with local and global variograms using a dataset of 807 urban topsoil Pb concentrations. Validation data were evaluated using root mean square errors, the percentage of sites misclassified by each method, and the expected loss resulting from incorrect classifications. All methods were very similar; however, the most accurate predictions were obtained using local multiple indicator kriging.
J.A. Cattle (cattlej{at}epa.nsw.gov.au)
Kriging Method Evaluation for Assessing the Spatial Distribution of Urban Soil Lead Contamination. J. Environ. Qual. 31:
1576–1588.
|
Humans Alter Suspended Particle Patterns in Streams
|
|---|
Suspended fine particles (seston) are an important component of energy and nutrient cycling in streams, but they can also be pollutants associated with human activities in watersheds. Whiles and Dodds report there are predictable patterns regarding suspended particles and filter-feeding macroinvertebrate communities across a gradient of stream sizes in the Kansas River drainage, but human impacts, specifically impoundments and suburban development, greatly alter these relationships. In particular, total seston and organic seston concentrations increase with stream size, but impoundments and suburban development obscure this relationship. Filter-feeder diversity increases with organic seston concentrations, but this trend is also altered by impoundments and suburban development, which change seston dynamics and suppress filter-feeder diversity. Observed relationships underscore the need for future regulatory decisions regarding suspended particles to account for both natural patterns and existing human impacts.
M.R. Whiles
(mwhiles{at}zoology.siu.edu)
Relationships between Stream Size, Suspended Particles, and Filter-Feeding Macroinvertebrates in a Great Plains Drainage Network. J. Environ. Qual. 31:
1589–1600.
|
Test Soil to Predict Phosphorus Leaching
|
|---|
Subsurface pathways can play an important role in agricultural phosphorus (P) losses that can decrease surface water quality. Maguire and Sims evaluated six agronomic and environmental soil tests for predicting losses of P in leachate from intact soil cores from five soil series that had a wide range in soil test P. Leachate dissolved reactive P (DRP) was frequently above concentrations associated with eutrophication, and when compared with soil test P a change point was determined, below which leachate DRP increased slowly per unit increase in soil test P, and above which leachate DRP increased rapidly. Environmental soil tests (WSP, CaCl2–P, and FeO–P) were slightly better at predicting leachate DRP than agronomic soil tests (Mehlich-1 P, Mehlich-3 P, and the M3-PSR), although the M3-PSR was as good as the environmental soil tests if two outliers were omitted. The results support using a single extraction with Mehlich-3 on a soil to give both the agronomic P requirement (Mehlich-3 P), as well as a risk assessment for P loss in leachate (Mehlich 3-PSR) that can be integrated with other site properties and P management.
R.O. Maguire (rmaguire{at}udel.edu)
Soil Testing to Predict Phosphorus Leaching. J. Environ. Qual. 31:
1601–1609.
|
Nitrogen Input/Output Changes in the Mississippi River Basin
|
|---|
Nitrogen enrichment of rivers contributes to eutrophication and hypoxia in coastal waters such as the Gulf of Mexico. In recent years, several N budgets for the Mississippi River Basin have been developed to account for changes in N sources and sinks in the second half of the 20th century. McIsaac et al. conducted a comparative analysis for these N budgets. Some of these budgets appear to overestimate N contributed from mineralization of soil organic matter as well as N lost from the basin as ammonia volatilized from crop canopy senescence. Trends in the annual difference between N inputs and outputs for each budget were compared with trends in nitrate flux in the Lower Mississippi River between 1960 and 1998. A statistical model that accounted for 95% of the variation in nitrate flux in the Lower Mississippi River was based on an N budget that assumed volatilized ammonia was redeposited within the basin and average soil organic N in the basin was not increasing or decreasing in quantity.
G. McIsaac (gmcisaac{at}uiuc.edu)
Relating Net Nitrogen Input in the Mississippi River Basin and Nitrate Flux in the Lower Mississippi River: A Comparison of Approaches. J. Environ. Qual. 31:
1610–1622.
|
Ion Cycling in Upper Michigan Forests
|
|---|
Management practice, forest cover type, and soil type all influence ion cycling in hemlock–northern hardwood forests of upper Michigan. All of the stands examined featured striking losses of base cations (Ca, Mg, K), NO3 and SO4 that are likely influenced by acidic deposition enriched in NO3 and SO4. Leaching losses of nutrients were greater in (i) old-growth than in managed northern hardwoods, (ii) old-growth northern hardwoods than in old-growth hemlock, and (iii) fragic (Alfic Oxyaquic Fragiorthods) than nonfragic soils (Entic Haplorthods).
J.G. Bockheim
(bockheim{at}facstaff.wisc.edu)
Ion Cycling in Hemlock–Northern Hardwood Forests of the Southern Lake Superior Region: A Preliminary Study. J. Environ. Qual. 31:
1623–1629.
|
Sorption and Degradation of Phosmet in Soil
|
|---|
Sorption and degradation of pesticides influence their potential to move through soil and cause contamination of the surrounding environment. The extent to which sorption and degradation might influence the potential of the organophosphate pesticide phosmet to leach through soil was studied using two Australian soils of contrasting properties. Sorption was directly related to organic matter content and inversely related to clay content, and followed a Freundlich isotherm at all depths, while degradation followed first order kinetics. Soil organic carbon, and to a lesser degree clay content, influenced both phosmet sorption and degradation, with the importance of each component being a function of soil type. This means it would be difficult to obtain a single parameter to describe sorption and degradation across a range of soil types.
H.C. Suter (hsuter{at}mira.net)
Sorption and Degradation Characteristics of Phosmet in Two Contrasting Australian Soils. J. Environ. Qual. 31:
1630–1635.
|
Uptake of PAHs by Vegetables
|
|---|
Contamination of soils with polycyclic aromatic hydrocarbons (PAHs) represents a potential risk for human health since recent research has demonstrated that plants were able to uptake and transfer some of these organic pollutants. Fismes et al. investigated the phytoavailability and transfer of PAHs on three vegetables (lettuce, potato, and carrot) cultivated on historically industrial contaminated soils. Results show the presence of PAHs in soils has no detrimental effect on plant growth. The vegetables grown on contaminated soils uptake PAHs both by roots and by leaves and translocate them to other organs. Except in potato pulp, PAH accumulation rates in different plant parts were correlated with PAH concentrations in soils.
J. Fismes
(Joelle.Fismes{at}ensaia.inpl-nancy.fr)
Soil-to-Root Transfer and Translocation of Polycyclic Aromatic Hydrocarbons by Vegetables Grown on Industrial Contaminated Soils. J. Environ. Qual. 31:
1649–1656.
|
Organo–Clay Complex May Reduce Herbicide Leaching
|
|---|
The herbicide imazaquin is negatively charged at basic pHs of calcareous soils and exhibits high leaching potential. Crystal violet (CV)–montmorillonite complexes become positively charged with adsorption of CV above the cation exchange capacity (CEC) of montmorillonite and thus enable the adsorption of imazaquin. The amount of imazaquin sorbed on CV–clay complexes reached 93 to 95% of the amount added and the rate of imazaquin release into water was slow (5% after 24 hours at concentrations of the CV–clay–imazaquin complex suspensions of 5 g/kg). Leaching of imazaquin from CV–montmorillonite formulations through soil (Rhodoxeralf) columns was four times less that than of technical imazaquin. The CV–montmorillonite–imazaquin formulations were still as bioactive as the commercial formulation and supplied enough imazaquin to inhibit the root growth of sorghum. The CV–montmorillonite complexes at a loading above the CEC appear to be suitable for preparation of organo–clay–imazaquin formulations that may reduce herbicide leaching significantly.
T. Polubesova
(polubeso{at}agri.huji.ac.il)
Imazaquin Adsorbed on Pillared Clay and Crystal Violet–Montmorillonite Complexes for Reduced Leaching in Soil. J. Environ. Qual. 31:
1657–1664.
|
Sorption Interactions between Imazaquin and Humic Acid from an Oxisol
|
|---|
Sorption of nonpolar pesticides in soil has been directly related with organic matter, with the humic substances its principal member. Reaction mechanisms of the herbicide imazaquin with an Oxisol from Brazil, including its humic acid, was studied using spectroscopic techniques and polarographic methods. The IM sorption increased as the soil–solution pH decreased. This enhancement in sorption was attributed to the hydrophobic affinity of the herbicide by the humic acid, and to the electrostatic interaction between the protonated quinoline group of imazaquin and negative sites of the humic acid. This research indicated a weak interaction between imazaquin and the soil and its humic acid, involving hydrogen bonding, proton transfer and cation exchange (at low pH), and mainly hydrophobic interactions. No strong reaction mechanism, such as charge-transfer, was involved.
L. Martin-Neto
(martin{at}cnpdia.embrapa.br)
Sorption Intereactions between Imazaquin and a Humic Acid Extracted from a Typical Brazilian Oxisol. J. Environ. Qual. 31:
1665–1670.
|
Sugar Maple Forest Decline Related to Soil Acidification
|
|---|
Previous studies have shown in noncalcareous soils that acid deposition may have increased soil leaching of basic cations above the rate of input from soil weathering and atmospheric depositions. This phenomenon may have increased soil acidity levels, and as a consequence, may have reduced the availability of these essential nutrients for forest growth. Fourteen plots of the Forest Ecosystem Research and Monitoring Network in Quebec were used to examine the relation between postindustrial growth trends of sugar maple and acid deposition (N and S), stand decline rate, and soil exchangeable nutrient concentrations. Atmospheric N and S deposition and soil exchangeable acidity were positively associated to stand decline rate, and negatively to the tree basal area increment trend. The growth rate reduction reached on average 17% in declining stands compared with healthy ones. The results showed a significant sugar maple growth rate reduction since 1960 on acid soils. Appearance of the forest decline phenomenon in Quebec can be attributed, at least partially, to soil acidification and acid deposition levels.
L. Duchesne
(louis.duchesne{at}mrn.gouv.qc.ca)
Basal Area Growth of Sugar Maple in Relation to Acid Deposition, Stand Health, and Soil Nutrients. J. Environ. Qual. 31:
1676–1683.
|
Chinese Brake for Phytoremediation of Arsenic-Contaminated Soils
|
|---|
The extraction efficiency of arsenic by plants is a key factor for the successful application of phytoremediation. Tu et al. report Chinese brake is very capable of producing relatively large biomass (18 g/plant) and accumulating large amounts of arsenic in its aboveground biomass (>10 g/kg). Thus, it can be used to phytoremediate arsenic-contaminated soils.
C. Tu (ctu2{at}unity.ncsu.edu)
Arsenic Accumulation in the Hyperaccumulator Chinese Brake and Its Utilization Potential for Phytoremediation. J. Environ. Qual. 31:
1671–1675.
|
Salinity Partitioning between Soil and Irrigated Soybean
|
|---|
Partitioning of Ca2+, Na+, and Cl- between soil and soybean plants under different irrigation regimes was studied using both field and modeling assessments. About 20% of the applied Ca2+ was recovered in harvested soybean biomass in all irrigation treatments. Plant uptake of either Na+ or Cl- was less than 0.5% in the drip and furrow irrigation treatments, and about 2% in the sprinkler irrigation treatment. Compared with the total seasonal salt input, mass balances between 65 and 108% were obtained. For plants that avoid taking up salt ions, most salt inputs accumulate in the soil and need to be removed periodically to prevent soil salinization.
D. Wang (dwang{at}soils.umn.edu)
Ion Partitioning among Soil and Plant Components under Drip, Furrow, and Sprinkler Irrigation Regimes: Field and Modeling Assessments. J. Environ. Qual. 31:
1684–1693.
|
Chemistry of Scots Pine Xylem after Long-Term Fertilization
|
|---|
Scots pine trees were growing in three locations in southern Finland for about 50 years and fertilized with N or with Ca, N, and P. Long-term forest fertilization increased the volume of stem wood and caused slight changes in the xylem secondary compounds, i.e., monoterpenes, resin acids, and total phenolics. Resin acids and phenolics seemed to be more responsive to N treatment than monoterpenes. Concentration of several individual monterpenes in sapwood were positively correlated with the corresponding monoterpene emission. Long-term forest fertilization might cause slight changes in concentrations of xylem extractives, which may have significance in the decay resistance of wood.
A.-M. Manninen
(Anne-Marja.manninen{at}uku.fi)
Secondary Metabolite Concentrations and Terpene Emissions of Scots Pine Xylem after Long-Term Forest Fertilization. J. Environ. Qual. 31:
1694–1701.
|
Salmonella Survival and Viability Unaltered by Suspended Particles
|
|---|
Understanding the influence of suspended particles on the survival and viability of pathogenic bacteria is of critical importance to human health because of current problems with overpopulation, contaminated runoff, and changing wastewater treatment policies that may lead to an increased load of living pathogens discharged into sources of freshwater. Water from the Duluth, MN, harbor of Lake Superior was inoculated with clay, silt, or flocculent organic particles (in a range of concentrations) and a model pathogen, S. typhimurium. Measured loss rates of attached and free cells were similar indicating attachment to particles did not enhance the persistence of Salmonella cells. Suspended particles had a minimal effect on the survival and viability of S. typhimurium; the losses of total, viable, or culturable Salmonella were generally the same across particle treatments and concentrations. It appears unlikely suspended particles would provide a means for S. typhimurium to persist at hazardous levels in freshwater.
R.P. Maki (rmaki{at}sfwmd.gov)
Salmonella typhimurium Survival and Viability is Unaltered by Suspended Particles in Freshwater. J. Environ. Qual. 31:
1702–1709.
|
Phosphorus and Nitrogen in Runoff from Simulated Fairways
|
|---|
Intensively managed golf courses could increase nutrient concentrations in surface waters via surface transport. The transport of nitrate N and phosphate P from simulated fairways was determined. The highest concentration and mass of P in runoff was during the first simulated 50-mm rainfall at 4 hours after treatment with a dramatic decrease for subsequent events. Total P transported for all events was 15.6 and 13.8% of that added at 5 and 11 kg ha-1 P, respectively. Total nitrate N transported was 1.5 and 0.9% of that added at 12 and 24 kg ha-1 ammonium N, respectively. Results indicate turfgrass management should include applying minimum amounts of irrigation immediately after fertilizer application and avoiding application before intense rain or when soil is very moist.
L.M. Shuman
(lshuman{at}gaes.griffin.peachnet.edu)
Phosphorus and Nitrate Nitrogen in Runoff following Fertilizer Applications to Turfgrass. J. Environ. Qual. 31:
1710–1715.
|
Leaching in Drainage Lysimeters Compared to Surrounding Soil
|
|---|
The convective lognormal transfer function (CLT) model was used to compare solute leaching under field conditions in drainage lysimeters with leaching in undisturbed soil adjacent to lysimeters. The CLT parameters indicate expected means for lysimeter and soil core solute concentration distributions closely matched, but smaller sampling support may cause higher variance of soil core concentrations. Disruption of solute transport mechanisms in repacked lysimeters could also interfere in the comparison. Smaller CLT median values obtained in these sandy soils, compared with most published values, indicate excessive leaching, but persistent tracer solute concentrations in the top soil layer indicate plant cycling or preferential flow also significantly interfere under transient water and field conditions.
M.O. Gasser
(mogasser{at}grr.ulaval.ca)
Solute Transport Modeling under Cultivated Sandy Soils and Transient Water Regime. J. Environ. Qual. 31:
1722–1730.
|
Manure Export through Turfgrass Sod Reduces Nutrient Loads
|
|---|
Surface applications of composted manure can enhance turfgrass growth and excess manure nutrients could be exported through sod harvests. Clippings and soil and plant components of sod were sampled to quantify the proportion of dairy manure P and N removed in a single harvest. The percentages of applied manure P removed in sod were similar, even when manure rates doubled. In contrast, the percentages removed in sod differed among bluegrass, bermudagrass, and buffalograss turf. The large percentages of applied manure P and N in sod harvests of the three turf species indicated manure exports through sod was a feasible practice for reducing nutrient loads on fields and watersheds.
D.M. Vietor (dvietor{at}tamu.edu)
Export of Manure Phosphorus and Nitrogen in Turfgrass Sod. J. Environ. Qual. 31:
1731–1738.
|
Nutrient Processing Capacity of a Constructed Wetland
|
|---|
In Ireland, free-water surface wetlands are becoming popular for the treatment of secondary wastewaters. In a 2-year study of the efficacy of a constructed wetland in western Ireland, Healy et al. show the primary treatment mechanism is the physical settlement of organic matter. After more than 3 years of wetland operation, adsorption isotherm data show the wetland still has available sorption sites. This study demonstrates that, although water temperature speeds up nitrate reduction rates, it also triggers eutrophication in the retention pond. With low flushing rates and no plant growth, the incorporation of a retention pond into wetland has no functional relevance to its operation.
M. Healy (mark.healy{at}nuigalway.ie)
Nutrient Processing Capacity of a Constructed Wetland in Western Ireland. J. Environ. Qual. 31:
1739–1747.
|
Bioavailability of Phosphorus in Surface Water
|
|---|
The potential bioavailability of organic phosphorus (P) in surface water treatment wetlands may provide vital information required for the further removal of P and estimation of ecological significance of the discharge. Pant et al. show phosphodiesterase hydrolyzed high amounts of organic P in surface waters from inflow and outflow regions of a submerged aquatic vegetation–dominated treatment wetland of the Everglades, suggesting the domination of bioavailable diester P in the waters. Phosphorus-31 NMR spectroscopy revealed surficial sediments from the inflow region contained high proportions of polynucleotides, nucleoside monophosphates, and previously unreported glycerophosphoethanolamine, and phosphoenolpyruvates. However, at the outflow the relative proportion of polynucleotides and nucleoside monophosphates were reduced substantially. This study suggests treatment wetlands may sequester P via accretion of organic matter; however, resuspension of surficial sediments in the water column can export high amounts of potentially bioavailable P with the discharge.
H.K. Pant (hari{at}mail.ifas.ufl.edu)
Bioavailability of Organic Phosphorus in a Submerged Aquatic Vegetation–Dominated Treatment Wetland. J. Environ. Qual. 31:
1748–1756.
TOP
Forest Stress Detection through...
Leaf Optics Indicate Chlorophyll...