Journal of Environmental Quality 31:705-710 (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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Moisture and Land Use Influence Denitrification End-Products
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When soil is wet, microbes known as denitrifiers can convert soil nitrate to the gases N2, the major constituent of Earth's atmosphere, and N2O, a trace gas that contributes to global warming. Bergsma et al. created laboratory precipitation events to discover whether short-term moisture history interacts with long-term land use history to influence the relative amount of N2O produced by denitrifiers. Nitrous oxide (N2O) was one-third of the N gas produced by soil from an 11-year-old successional system, regardless of moisture history. For soil from a continuously cropped system, however, the N2O component was one-third if the soil had been wet for 2 days, but soared to nine-tenths of total N gas if the soil had been wet for only a few hours. Taking the interaction of land use and soil moisture history into consideration could lead to more accurate models of N2O flux and global warming.
T.T. Bergsma
(tbergsma{at}kbs.msu.edu)
Influence of Soil Moisture and Land Use History on Denitrification End-Products. J. Environ. Qual. 31:
711–717.
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Pesticide Volatilization Model for Turfgrass
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Chemicals used for control of turfgrass pests may volatilize, resulting in potential health hazards for turf users. Field measurements of pesticide volatilization are time-consuming, expensive, and impractical for the full range of chemicals, weather, and site conditions encountered in practice. Environmental and health assessments of pesticide volatilization must generally be based on mathematical modeling. This research has shown pesticide volatilization from turf can be reasonably predicted by a model based on estimates of turf evapotranspiration, adjusted to chemical vaporization using ratios of saturated vapor pressure and latent heat of vaporization. Testing results showed the model to be a relatively conservative approach for predicting pesticide volatilization. Predicted mean losses exceeded observations by 20%, and the model explained 67% of the observed variation in volatilization fluxes. The model was most accurate for those chemicals that exhibited the largest volatilization losses.
D.A. Haith (dah13{at}cornell.edu)
Modeling Pesticide Volatilization from Turf. J. Environ. Qual. 31:
724–729
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Roundup Ultra Enhances Soil Microbial Activity
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The objective of this study was to determine the impact of Roundup Ultra on soil microbial biomass and activity across a range of soils (9) varying in fertility. Soil microbial biomass (SMB) C was highly correlated to SMB N with and without Roundup Ultra (RU) addition. Carbon and N mineralized were also highly correlated. The slopes (C/N ratio) of the regression for both C and N mineralization decreased threefold with the addition of RU and was attributed to the 3:1 ratio of C/N by the glyphosate contained in RU. Roundup Ultra appeared to be rapidly degraded by soil microbes regardless of soil texture or organic matter content. Also, soil microbial activity appeared to be enhanced with increasing additions of RU.
S. Senseman (s-senseman{at}tamu.edu)
Effect of Roundup Ultra on Microbial Activity and Biomass from Selected Soils. J. Environ. Qual. 31:
730–735.
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Using Chemistry and Biology to Remediate TNT
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Wastes generated from the manufacture or decommissioning of munitions currently contaminate both soil and ground water at many sites around the world. Previous methods for the remediation of these wastes have been based solely on either chemical or biological means. A newly developed process that couples both chemical and biological degradation has been shown by Hess and Schrader to be more effective than either technology alone and may produce almost 80% destruction of TNT in aqueous solution. This combined abiotic and biotic process may also be useful for the remediation of munitions-contaminated soils.
T.F. Hess (tfhess{at}uidaho.edu)
Coupled Abiotic–Biotic Mineralization of 2,4,6-Trinitrotoluene (TNT). J. Environ. Qual. 31:
736–744.
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Factors Affect Nitrogen Uptake Efficiency in Citrus
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Applying N more frequently and increasing its residence time in the root zone from 2 to 8 hours increased N uptake efficiency (NUE) of young citrus seedlings from 17 to 82%. A simple conceptual model was developed for describing the potential risk of N leaching under field conditions as a function of root density, soil N concentration, and soil temperature. Using this model, it is concluded that low NUE values associated with the use of high application rates of reclaimed water for citrus irrigation appeared to be related to N displacement below the root zone prior to complete N uptake.
J.M. Scholberg
(jmscholberg{at}mail.ifas.ufl.edu)
Soil Temperature, Nitrogen Concentration, and Residence Time Affect Nitrogen Uptake Efficiency in Citrus. J. Environ. Qual. 31:
759–768.
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Sorption of Ferricyanide and Ferrocyanide Differs
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Along with large amounts of sulfate, the iron–cyanide complexes ferricyanide [Fe(CN)6]3- and ferrocyanide [Fe(CN)6]4- are present in soil on sites of former manufactured gas plants. Rennert and Mansfeldt show the presence of sulfate decreases ferricyanide sorption on goethite, but not that of ferrocyanide. Chloride and phosphate desorb ferricyanide from goethite, where phosphate does not desorb ferrocyanide at pH 3.5. The results were obtained in batch experiments with goethite suspensions, ferri- and ferrocyanide as the sorptives, sulfate as the competitive sorptive, and phosphate and chloride as desorbing agents. The study confirms that iron–cyanide complexes are sorbed on goethite by different mechanisms.
T. Mansfeldt
(tim.mansfeldt{at}ruhr-uni-bochum.de)
Sorption of Iron–Cyanide Complexes on Goethite in the Presence of Sulfate and Desorption with Phosphate and Chloride. J. Environ. Qual. 31:
745–751.
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Tillage and Irrigation Affect Environmental Quality
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It is widely recognized that long histories of frequent plowing and irrigation can result in deteriorated soil quality. However, little is known about the short-term effects of common agricultural practices such as tillage and irrigation on soil and environmental quality. Calderon and Jackson find that tillage followed by irrigation results in increased CO2 efflux from soil to the atmosphere, as well as net accumulation of nitrate in soil within a matter of days. Tillage tends to favor a physical release of soil dissolved CO2, whereas irrigation increases soil respiration and results in a CO2 efflux of biological origin. These results are based on a field experiment on a silt loam soil in the Central Valley of California. These findings underscore the importance of understanding the effect of agronomic disturbances because of the close relationship between agricultural practices and the condition of our environment and soils.
F. Calderón (fjcgztsp{at}yahoo.com)
Rototillage, Disking, and Subsequent Irrigation: Effects on Soil Nitrogen Dynamics, Microbial Biomass, and Carbon Dioxide Efflux. J. Environ. Qual. 31:
752–758.
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Phosphorus Leaches from Prairie and Corn Agroecosystems
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Most studies of P movement in soil have based conclusions on patterns of extractable soil P as a function of depth, which led to the assumption of no substantial leaching because of high P fixation capacity in mineral soils. Recent studies have indicated soil solution concentrations and subsurface P leaching are larger than once thought. Brye et al. show leachate-P concentrations from natural and managed agroecosystems exceeded 0.01 mL P L-1, and leaching was more from N-fertilized corn, regardless of tillage, than from prairie or N-unfertilized corn from which leachate-P concentrations and loads were similar. Drainage and solute leaching measurements were conducted using equilibrium-tension lysimeters. Results indicate dissolved-P concentrations in excess of acceptable critical limits can leach below the root zone of corn grown with conventional N rates and that of natural ecosystems more than 20 years after being restored from cultivated agriculture. Results also indicate N fertilization increases mobile-P concentrations in leachate solution.
K.R. Brye (kbrye{at}uark.edu)
Phosphorus Leaching under a Restored Tallgrass Prairie and Corn Agroecosystems. J. Environ. Qual. 31:
769–781.
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Precision Management of Pesticide Leaching?
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Legislation and farm management are constantly struggling with the environmental impacts of pesticide use. Van Alphen and Stoorvogel present a step-wise evaluation of the effects of soil variability and weather conditions on pesticide leaching. Leaching was strongly affected by soil variability at the within-field, field, and farm levels. Opportunities for precision management were apparent, but depended on the scale level at which environmental thresholds were implemented. When legislation is formulated in this issue, the presented step-wise evaluation can serve as a basis for identification and precision management of high-risk pesticides.
J.J. Stoorvogel
(jetse.stoorvogel{at}bodlan.beng.wau.nl)
Effects of Soil Variability and Weather Conditions on Pesticide Leaching—A Farm-Level Evaluation. J. Environ. Qual. 31:
797–805.
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Sediment Resuspension Changes Arsenic Partitioning
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Although occurring regularly in shallow lakes, the role of oxic resuspension as a mechanism for contaminant remobilization remains ill defined. Using a sequential extraction scheme, Linge and Oldham show how resuspension changes As partitioning in contaminated sediments from a shallow wetland. The sediment's inherent buffering capacity limits effect of pH variation on As remobilization or partitioning but the changes in contaminant sediment partitioning measured reflect the mechanisms controlling remobilization.
K.L. Linge (linge{at}cwr.uwa.edu.au)
Arsenic Remobilization in a Shallow Lake: The Role of Sediment Resuspension. J. Environ. Qual. 31:
822–828.
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Trace Element Migration from Pyrite Tailings
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Under toxic tailings from a pyrite mine in southern Spain, an Fe-rich layer formed in the carbonate soils, immediately underneath the tailings, when sulfides oxidized to sulfates, acidifying and polluting the soils with Zn, Cu, As, Pb, Co, Cd, Sb, Bi, Tl, and In. Less mobile elements (As, Bi, In, Pb, Sb, and Tl) concentrated toward the top of the layer, more mobile elements (Co, Cd, Zn, and Cu) precipitating where pH was basic. Concentrations, greatest in the upper 6 mm of soil, became negligible below 15 mm. Acidity degraded clay minerals while gypsum formed autigenically, as did complex salts, sulfates, jarosite, and Fe oxihydroxides.
C. Dorronsoro
(cfdorron{at}goliat.ugr.es)
Migration of Trace Elements from Pyrite Tailings in Carbonate Soils. J. Environ. Qual. 31:
829–835.
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Landscape Metrics and Estuarine Sediment Contamination
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Quantitative relationships were developed between landscape metrics and sediment contamination for 75 small estuarine systems across the mid-Atlantic and southern New England regions of the USA. Variation in sediment contamination levels across small estuarine systems was related to the surrounding land cover composition and point source discharges of pollutants. The influence of these variables was mitigated by sediment characteristics and estuarine dynamics. The landscape metrics important for explaining variation in sediment metals levels were the percent area of nonforested wetlands (negative contribution), percent area of urban land, and point source effluent volume and metals input (positive contributions). The metrics important for sediment organic levels and total polycyclic aromatic hydrocarbons were percent area of urban land (positive contribution) and percent area of nonforested wetlands (negative contribution).
J.F. Paul
(Paul.John{at}epamail.epa.gov)
Landscape Metrics and Estuarine Sediment Contamination in the Mid-Atlantic and Southern New England Regions. J. Environ. Qual. 31:
836–845.
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Landscape–Stream Water Quality Relationships
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Traditionally, the relationships between terrestrial systems and lotic systems have been studied by classifying aerial photography or satellite imagery into discrete land use–land cover (LULC) classes. Griffith et al. examined, in addition to LULC, the relationship between a satellite-derived vegetation index and landscape pattern metrics with six stream water quality parameters: P, N, conductivity, turbidity, the index of biotic integrity, and a habitat index. The results for a study region of more than 250 watersheds in Nebraska, Kansas, and Missouri revealed that, in most cases, the satellite-derived vegetation index was as highly correlated or more strongly correlated to the water quality parameters than were LULC, landscape pattern metrics, or a combination of the latter two. This study makes a new contribution to landscape–water quality studies by being among the first to examine empirical relationships between landscape pattern metrics and vegetation indices to water quality on a multistate scale. The findings underscore the usefulness of the satellite-derived normalized difference vegetation index as a potential broad-scale screening indicator of the status and condition of midwestern stream watersheds.
J. Griffith (Griffith{at}usgs.gov)
Preliminary Comparison of Landscape Pattern–Normalized Difference Vegetation Index (NDVI) Relationships to Central Plains Stream Conditions. J. Environ. Qual. 31:
846–859.
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Modeling of Microbial Contaminants on Grazing Farmlands
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Pastoral grazing practices, which create a diffuse source and disposal of animal waste, significantly contribute to the fecal contamination of catchments. The public health risk from agricultural pollution has substantial implications for farming practices and international image, both for trade and tourism. However, population distribution, transport process, and fate of fecal materials are difficult to explain using only monitored information due to the complexity of temporal and spatial variation. Tian et al. introduced an integrated and process-based modeling approach for characterizing the movement of fecal materials from land to streams and instream mobilization through interactions among processes on fecal pools in land surfaces and stream segments. The validation result showed the method is appropriate for modeling pathogenic contaminations originating from farmlands.
Y.Q. Tian
(tian{at}nature.berkeley.edu)
Spatial and Temporal Modeling of Microbial Contaminants on Grazing Farmlands. J. Environ. Qual. 31:
860–869.
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Assessing Regional Scale Nutrient Delivery
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As soil erosion and sediment delivery vary through space, nutrient delivery also varies as nutrients are often fixed to soil particles. Through the analysis of sediment deposits in flood control ponds, the regional scale variability of nutrient delivery from agricultural watersheds was determined for the Loess Belt in Belgium. Besides spatial variability in sediment dynamics, regional variations in nutrient application rates are also important in explaining nutrient delivery variability. A recent policy that redistributes surplus manure may increase total nutrient delivery in the future.
G. Verstraeten
(gert.verstraeten{at}geo.kuleuven.ac.be)
Regional Scale Variability in Sediment and Nutrient Delivery from Small Agricultural Watersheds. J. Environ. Qual. 31:
870–879.
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Sorption and Mobility of Imidacloprid in Soil
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The effect of dissolved organic carbon (DOC) on sorption and mobility of imidacloprid in a calcareous soil from southeastern Spain was evaluated. A commercial peat (DOC-PE) and high-purity tannic acid (DOC-TA) were used as sources of DOC. Results show DOC reduces imidacloprid sorption by competing with the pesticide molecules for sorption sites on the soil surface, thereby allowing an enhanced leaching process for imidacloprid and an increased ground water potential contaminant.
E. González-Pradas
(egonzale{at}ual.es)
Effects of Dissolved Organic Carbon on Sorption and Mobility of Imidacloprid in Soil. J. Environ. Qual. 31:
880–888.
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Insecticide Partitioning in a Golf Putting Green
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Research on the fate of pesticides in turf ecosystems is important for a better understanding of the potential impact of pesticide use on the environment and human health. Wu et al. investigated the environmental fate of two commonly used insecticides, trichlorfon (Dylox) and chlorpyrifos (Dursban), in a putting green under customary field management practices at the University of California-Riverside. Volatilization, clipping removal, and soil residues of the two insecticides were quantified and leaching was monitored. Results showed the fraction of applied insecticides leaving the turf putting greens was minimal.
L. Wu (Laowu{at}mail.ucr.edu)
Partitioning and Persistence of Trichlorfon and Chlorpyrifos in a Creeping Bentgrass Putting Green. J. Environ. Qual. 31:
889–895.
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Fate Modeling of Benzo[a]- pyrene in Tianjin, China
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A Level III fugacity model was applied to characterize the transfer processes and environmental fate of benzo[a]pyrene in wastewater-irrigated areas of Tianjin, China. Results indicate there was generally good agreement between the predicted and observed concentrations of the chemical in various media and the differences were within an order of magnitude for air, soil, and sediment, Relatively high concentrations of the compound were found in the soil and sediment, with the soil serving as the dominant sink in the area. Benzo[a]pyrene, with a slow metabolic rate, was found to accumulate in fish in the area.
S. Tao (Taos{at}urban.pku.edu.cn)
Modeling the Fate of Benzo[a]pyrene in the Wastewater-Irrigated Areas of Tianjin with a Fugacity Model. J. Environ. Qual. 31:
896–903.
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Plants Extract Contaminats from Soil
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A field test was conducted to determine the ability of three plant species to extract 137Cs and 90Sr from contaminated soil. Amaranthus retroflexus, Brassica juncea, and Phaseolus acutifolius (A. Gray) were planted in a series of spatially randomized cells in soil that was contaminated in the 1950s and 1960s. Concentration ratios for 137Cs for Amaranthus, Brassica, and Phaseolus were 2.58, 0.46, and 0.17, respectively. For 90Sr they were substantially higher, 6.5, 8.2, and 15.2, respectively. Estimates of times required to remove 50% of the two contaminants, assuming two crops of Amaranthus per year, are 7 years for 90Sr and 18 years for 137Cs.
M. Fuhrmann (fuhrmann{at}bnl.gov)
Uptake of Cesium-137 and Strontium-90 from Contaminated Soil by Three Plant Species; Application to Phytoremediation. J. Environ. Qual. 31:
904–909.
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Nitrogen Contaminates the Yellow River
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Nitrogen contamination has been, and continues to be, one of the most serious problems in the Yellow River of China. In a study analyzing monitoring data on N contamination for the Yellow River Basin in the years 1980, 1990, 1997, and 1999, Xinghui et al. found (i) the N concentration in tributaries and mainstream showed an increasing trend from the upper to the lower basin, (ii) N in the water in mainstream and tributaries of the Yellow River was attributed mainly to point sources, and (iii) the ammonium N and total inorganic N content of the river water increased significantly in mainstream and tributaries during the study period.
Xia Xinghui (xiaxh{at}bnu.edu.cn)
Nitrogen Contamination in the Yellow River Basin of China. J. Environ. Qual. 31:
917–925.
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Runoff from a Biosolids-Fertilized Forested Watershed
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Pure biosolids without composting are typically not applied to steep slopes in the Pacific Northwest, USA, due to concerns about runoff of biosolids into surface waters. Direct particle movement and nutrient losses are primary considerations, as surface waters are P limited and ammonia-N can be toxic to fish. Grey and Henry examined surface water runoff from a steeply sloped forested watershed before and after biosolids application and found no evidence of direct runoff of P or N forms. The application of biosolids did not change the concentration of P forms in runoff water, nor did it affect the concentration–discharge relationship. Conversely, biosolids application elevated runoff water nitrate-N concentrations and changed the concentration–discharge relationship beginning 9 months after application. Phosphorus and N exported in runoff water were less than 1% of that applied in biosolids, suggesting strong retention within the watershed.
M.A. Grey (mgrey{at}synagro.com)
Phosphorus and Nitrogen Runoff from a Forested Watershed Fertilized with Biosolids. J. Environ. Qual. 31:
926–936.
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Decision Support System for Phosphorus Management
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Different fields in a watershed do not contribute equally to P losses. Also, causes for high P losses vary and, therefore, abatement practices should be fieldspecific. A GIS-based decision support system consisting of the Maryland P index, diagnosis and prescription expert systems, and a hydrologic model (GLEAMS) was developed to: (i) identify high-risk fields for P losses, (ii) identify site-specific causes for P losses, (iii) recommend appropriate best management practices (BMPs), and (iv) evaluate proposed BMPs. Only small parts of the total area (5–10%) of a small agricultural watershed in southwest Sweden were classified as having high potential for P movement. Field-specific probable causes for P losses and BMPs were suggested for each high-risk field. The simulations conducted with the GLEAMS model showed that implementation of the recommended BMP decreased P losses considerably.
F. Djodjic (Faruk.Djodjic{at}mv.slu.se)
A Decision Support System for Phosphorus Management at a Watershed Scale. J. Environ. Qual. 31:
937–945.
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Impact of Wood Ash on Lake Ecosystems
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The favorable effects of wood ash on forest growth have been known for a long time, and in recent years the interest in large-scale utilization of wood ash as a forest fertilizer has increased. Environmental risks of wood ash application on lake ecosystems have not been studied. Tulonen et al. showed, using tank experiments, that addition of wood ash increased pH and nutrient concentrations of lake water, but decreased phytoplankton growth. However, a small-scale application of wood ash on the drainage basins of two humic lakes, corresponding to less than 19% of total catchment, had only minor impact on water quality and biota of recipient lakes.
T. Tulonen
(tiina.tulonen{at}helsinki.fi)
Limnological Effects of Wood Ash Application to the Subcatchments of Boreal, Humic Lakes. J. Environ. Qual. 31:
946–953.
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Poultry Litter Ash Benefits Crops
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In order to limit P runoff from the Chesapeake Bay watershed, the Maryland Water Quality Act of 1998 was introduced to limit excessive poultry litter use on agricultural land. Alternative management of poultry litter by burning it to produce electricity is being investigated. This study was to test the effectiveness of poultry ash as a P fertilizer for wheat growth compared with that of reagent-grade potassium phosphate on limed and nonlimed soils. Plant yields were similar for both P sources, but the litter ash treatments caused a higher concentration of P in the wheat shoots compared with the potassium phosphate. Thus, the phosphate from the ash was readily available for uptake by roots. As a result of incineration, P in the litter ash was less water soluble than in the unburned litter, and marketing of the ash may reduce costs of litter management.
E.E. Codling
(codlinge{at}ba.ars.usda.gov)
Poultry Litter Ash as a Potential Phosphorus Source for Agricultural Crops. J. Environ. Qual. 31:
954–961.
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Sorption Kinetics of Toluene in Humin
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The time scale for organic chemical vapor sorption without mass transfer hindrance, observed with an innovative IR-spectroscopic technique, is less than a few minutes with the thin humin film. Shih and Wu also show there is no detectable level of residual toluene in humin after desorption, as revealed either by the gravimetric analysis or by the FTIR absorbance obtained at either low or high humidity. These results indicate the sorption of toluene to humin is reversible and mainly diffusion-controlled.
Y. Shih (d7541007{at}ms.cc.ntu.edu.tw)
Sorption Kinetics of Toluene in Humin under Two Different Levels of Relative Humidity. J. Environ. Qual. 31:
970–978.
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Scrubber Wastes are Complex Systems
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Scrubbing technologies developed to reduce sulfur dioxide emissions from coal-fired utilities generate large quantities of waste materials. These flue gas desulfurization wastes are usually complex mixtures of fly ash, excess sorbent, and various reaction products. Beneficial uses for these materials are needed to avoid costly land filling, but permits for utilization are commonly based on bulk chemical analyses. Such analyses do not reflect the spatial distribution of potentially hazardous components, nor do they indicate the possible impact of secondary reactions that may alter the distribution or bioavailability of these components. Laperche and Bigham demonstrate that simple fractionation and selective dissolution techniques can be coupled with standard chemical and mineralogical analyses to provide a detailed characterization of both fresh and aged flue gas desulfurization wastes for better environmental decision making.
V. Laperche (laperche{at}cnrssp.org)
Quantitative, Chemical, and Mineralogical Characterization of Flue Gas Desulfurization By-Products. J. Environ. Qual. 31:
979–988.
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Cattle Manure Influences Soil Hydrological Properties
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Limited information exists on the effect of long-term application of beef cattle manure on soil hydrological properties in the Great Plains region of North America. We found that annual application of high rates of manure to a clay loam soil under dryland and irrigation over 24 years resulted in an increase in soil water retention, field soil water content, ponded infiltration, proportion of macropores, and saturated hydraulic conductivity. In contrast, increased manure rate had no influence on unsaturated hydraulic conductivity. These results were based on field and laboratory measurements of soil hydrological properties conducted during a 2-year period. Overall, soil hydrological parameters generally had a neutral or positive response to 24 years of annual manure addition, and long-term application of beef cattle manure should not cause any detrimental effects to water retention and storage, water flow, or pore-size distribution.
J.J. Miller (millerjj{at}em.agr.ca)
Hydrological Properties of a Clay Loam Soil after Long-Term Cattle Manure Application. J. Environ. Qual. 31:
989–996.
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Simple Numerical Model Predicted Composing
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Large-scale composting of municipal refuse collected from large areas is not widespread because of the difficulty of avoiding contamination by impurities. A solution to the problem of impurities is the use of personal composting machines; this allows garbage, the main constituent of the compostable fraction of municipal refuse, to be treated at the site where generated. Composting machines for personal use are operated by fed-batch operation. There has been no report of the use of a numerical model to express the degradation of organic matter in a fed-batch composting operation. Nakasaki et al. show a simple numerical model based on a first-order kinetic equation can predict organic matter degradation in fed-batch composting. This model is expected to be used in the design of high-performance personal composting machines, thereby encouraging the composting of garbage, the most difficult material to compost without contamination.
K. Nakasaki
(tcknaka{at}ipc.shizuoka.ac.jp)
A Simple Numerical Model for Predicting Organic Matter Decomposition in a Fed-Batch Composting Operation. J. Environ. Qual. 31:
997–1003.
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Kraft Mill Residues Affect Soil Microbial Activity and Growth of Pine Seedlings
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The production of bleached Kraft pulp generates inorganic and organic residues that are usually deposited on the soil surface or land-filled. Studies conducted to address the impact of these solid wastes on the environment are scarce. Jordan et al. show forest soils exposed to ashes, fly ashes, or dregs allow substantial seed germination and seedling growth of Monterey pine, an important tree for pulping, under greenhouse conditions. In contrast, soils exposed to brown rejects, grits, or a mixture of all these residues were detrimental for germination, plant growth, or both. No significant changes in the microbial community of soils exposed to these solid residues were observed by determination of culturable counts or culture-independent analysis of the microbial community DNA. Results indicate landspreading of some of these solid residues deserves assessment under field conditions.
M. Jordan
(mjordan{at}genes.bio.puc.cl)
Kraft Mill Residues Effects on Monterey Pine Growth and Soil Microbial Activity. J. Environ. Qual. 31:
1004–1009.
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Performance of Wastewater Treatment Wetlands in Cold Climates
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Constructed wetlands are widely used for wastewater treatment, but there is little information on processes affecting their performance in cold climates, effects on plants on seasonal performance, or plant selection for cold regions. Allen et al. evaluated the effects of three plant species on seasonal removal of dissolved organic matter (OM) (measured by chemical oxygen demand and dissolved organic carbon) and root zone oxidation status (measured by redox potential [Eh] and sulfate [SO2-4] in subsurface-flow wetland microcosms). All plants enhanced OM removal compared with unplanted controls, but plant effects and differences among species were much greater at 4°C, during dormancy, than at 24°C, during the growing season. Seasonal differences in OM removal corresponded to species' apparent abilities to increase root zone oxygen supply.
W. Allen (wallen{at}CH2M.com)
Temperature and Wetland Plant Species Effects on Wastewater Treatment and Root Zone Oxidation. J. Environ. Qual. 31:
1010–1016.
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Riparian Ground Water Denitrification Method
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Although riparian zones can markedly decrease the flux of N from watersheds, major questions surround the influence of site and management factors on the ground water N removal capacity of riparian zones. These questions argue for timely and affordable in situ assessment methods. To quantify ground water denitrification in discrete locations of riparian zones, Addy et al. modified and evaluated an in situ method based on injection of 15N-enriched nitrate and recovery of 15N-enriched dissolved gases. This method can provide useful insights into spatial and temporal patterns of denitrification in riparian zones. In conjunction with measurements of ground water flowpaths, the method holds promise for establishing the role of riparian zones in the flux of nitrate within watersheds.
A. Gold
(ago7110u{at}postoffice.uri.edu)
In Situ Push–Pull Method to Determine Ground Water Denitrification in Riparian Zones. J. Environ. Qual. 31:
1017–1024.
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Controls of Denitrification at the Upland–Riparian Wetland Interface
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Ground water NO-3 concentrations decrease as ground water flows through riparian zones toward the stream, improving water quality. Recent studies showed the upland–wetland interface was controlling diffuse NO-3 fluxes. However, results regarding the impact of different vegetation on these buffering capacities were contradictory, mainly because of comparison of sites with diverse hydrogeomorphic conditions. Clement et al. evaluate the effect of three distinct vegetation covers on denitrification activity in adjacent riparian zones located in the same hydrogeomorphic stream valley system. Spatial and temporal analyses of denitrification activity at these three upland–wetland interfaces emphasize the importance of the topography of the valley rather than the vegetation cover in controlling denitrification activity in riparian wetlands.
J-C. Clément
(clement{at}aesop.rutgers.edu)
Seasonal Dynamics of Denitrification along Topohydrosequences in Three Different Riparian Wetlands. J. Environ. Qual. 31:
1025–1037.
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Slime Molds Hyperaccumulate Zinc
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Samples of the slime mold Fuligo septica were collected from an ecologically diverse selection of sites across the former USSR and in North Korea to determine their Zn concentrations. The biomass collected ranged from 305 to 968 mg, wheres Zn concentrations in plasmodia of F. septica ranged from 8400 to 23000 mg kg-1 dry wt. The ability to hyperaccumulate Zn seems to be unique to this species, but how it does this is a question requiring future research. The identification of an active Zn sequestration mechanism could lead to the cloning of the corresponding genes and their use in bioremediation following implantation into plants with a larger biomass. Fuligo septica's ability to hyperaccumulate Zn may also be significant in studies of toxic metal impacts in forest systems.
R.D. Robarts
(richard.robarts{at}ec.gc.ca)
Zinc Accumulation by the Slime Mold Fuligo septica (L.) Wiggers in the Former Soviet Union and North Korea. J. Environ. Qual. 31:
1038–1042
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Related articles in JEQ:
- Kraft Mill Residues Effects on Monterey Pine Growth and Soil Microbial Activity
- Miguel Jordan, Miguel Angel Sánchez, Leandro Padilla, Ricardo Céspedes, Miguel Osses, and Bernardo González
JEQ 2002 31: 1004-1009.
[Abstract]
[Full Text]
- Temperature and Wetland Plant Species Effects on Wastewater Treatment and Root Zone Oxidation
- Winthrop C. Allen, Paul B. Hook, Joel A. Biederman, and Otto R. Stein
JEQ 2002 31: 1010-1016.
[Abstract]
[Full Text]
- In Situ Push–Pull Method to Determine Ground Water Denitrification in Riparian Zones
- Kelly Addy, D. Q. Kellogg, Arthur J. Gold, Peter M. Groffman, Gina Ferendo, and Carl Sawyer
JEQ 2002 31: 1017-1024.
[Abstract]
[Full Text]
- Seasonal Dynamics of Denitrification along Topohydrosequences in Three Different Riparian Wetlands
- Jean-Christophe Clément, Gilles Pinay, and Pierre Marmonier
JEQ 2002 31: 1025-1037.
[Abstract]
[Full Text]
- Zinc Accumulation by the Slime Mold Fuligo septica (L.) Wiggers in the Former Soviet Union and North Korea
- Daniel A. Zhulidov, Richard D. Robarts, Alexander V. Zhulidov, Olga V. Zhulidova, Danila A. Markelov, Viktor A. Rusanov, and John V. Headley
JEQ 2002 31: 1038-1042.
[Abstract]
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Moisture and Land Use...
Pesticide Volatilization Model...