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Wetlands have a substantial capacity for nitrogen and phosphorus attenuation from natural and artificial runoff events, according to a report by Casey and Klaine. They showed that attenuation occurs on the time scale of natural runoff events (6–48 hours). Land uses that are intensively managed with fertilizers can potentially contribute to nutrient loads in storm runoff. This study evaluated the ability of a natural wetland to remove nitrogen and phosphorus from both natural storm runoff and experimentally amended artificial runoff events.
R. Casey (racasey{at}towson.edu)
Nutrient Attenuation by a Riparian Watershed during Natural and Artificial Runoff Events. J. Environ. Qual. 30:1720–1731.
Wetland Nutrient Removal Mechanisms Revealed
Riparian wetlands serve as nutrient filters for surface and ground water between terrestrial and aquatic environments. Casey et al. now report that denitrification can be substantial in systems receiving pulsed nitrate inputs during storm runoff, and that sorption accounts for most phosphate attenuation. A bottomland wetland site successfully removed nutrients from storm-generated pulses of runoff on a short time scale (6–48 hours). Measured denitrification rates accounted for much of the observed nitrate attenuation, while phosphate sorption by the wetland soils accounted for phosphate losses from runoff water.
R. Casey (racasey{at}towson.edu)
Mechanisms of Nutrient Attenuation in a Subsurface Flow Riparian Wetland. J. Environ. Qual. 30:1732–1737.
Zinc, Copper Contaminate Sludge-Amended Tropical Soils
Trace-metal contamination of soils has been documented in temperate regions where metal-rich sewage sludge has been used as a fertilizer. Few studies have examined metal mobility in sludge-amended soils of tropical regions. Mbila et al. now report that Nigerian soils that received sewage sludge for 37 years have elevated levels of zinc and copper, reflecting the trace metal composition of the sewage sludge. Zinc and copper enrichment at all depths indicated that the applied metals had moved below the tillage zone. Moreover, the sludge-amended soils contained more potentially bioavailable metal ions than did the unamended soil. Although metal-sorbing iron-oxide minerals are abundant in these soils, the mobility of metals is probably closely linked to the low soil pH.
M.O. Mbila (mombila{at}syr.edu)
Distribution and Movement of Sludge-Derived Trace Metals in Selected Nigerian Soils. J. Environ. Qual. 30:1667–1674.
New Molybdenum Standards for Biosolids
The initial USEPA risk assessment for molybdenum (Mo) in biosolids suffered from limited data and overly simplified risk scenarios. O'Connor et al. reevaluated biosolids-Mo databases, refined risk assessment algorithms, and reassessed molybdenosis risk from land application of biosolids. They regard the modifications to algorithms, parameters, and calculations as conservative, and believe the risk of molybdenosis from biosolids Mo is small.
G.A. O'Connor (gao{at}ufl.edu)
A Modified Risk Assessment to Establish Molybdenum Standards for Land Application of Biosolids. J. Environ. Qual. 30:1490–1507.
Rainfall Nitrogen Pollutes Estuary
Nitrogen pollution in rain accounts for about 20% of the total nitrogen pollution to the nitrogen-sensitive Neuse River Estuary in North Carolina, according to a study by Whitall and Paerl. This flux varies spatially in the watershed and seasonally due to seasonal patterns in nitrogen emissions. Nitrogen pollution in rain is an important source of nitrogen to North Carolina coastal waters and should be included in basin-wide and regional nitrogen management strategies.
D. Whitall (drwhital{at}syr.edu)
Spatiotemporal Variability of Wet Atmospheric Nitrogen Deposition to the Neuse River Estuary, North Carolina. J. Environ. Qual. 30:1508–1515.
Herbicide Contamination Sources Identified
Cyanazine, one of three common triazine herbicides, contributed a significant portion of triazine degradation products transported down the Mississippi River during the 1993 flood. To identify cyanazine as the source, Meyer et al. developed a discrimination diagram based on the ratio of deisopropylatrazine (DIA) and deethylatrazine (DEA), common products of triazine herbicide degradation detected in surface water throughout the USA. Deisopropylatrazine has multiple parent sources (atrazine, cyanazine, and simazine) and DEA has only one parent source (atrazine). To distinguish DIA contributions of atrazine from other parent compounds in surface water the DIA to DEA ratio (D2R) was developed as a discriminator.
M.T. Meyer (mmeyer{at}usgs.gov)
Differentiating Nonpoint Sources of Deisopropylatrazine in Surface Water Using Discrimination Diagrams. J. Environ. Qual. 30:1836–1843.
Tracing Particle Transport Processes
Syversen et al. labeled soil particles with the radioactive tracer 134Cesium (134Cs) to study soil erosion and sedimentation patterns in a small Norwegian catchment with buffer zones. Since Cs is adsorbed to soil particles, they were able to trace erosion and sedimentation pathways for particles by measuring changes in the 134Cs activity on the soil surface and in runoff water after major runoff events. About 54% of the applied tracer remained at the soil surface at the end of the experiment, while most of the transported tracer moved vertically into the soil profile, probably during the first heavy rainfall after application. Sedimentation occurred in the upper part of the buffer zone.
N. Syversen
(nina.syversen{at}jordforsk.no)
Cesium-134 as a Tracer to Study Particle Transport Processes within a Small Catchment with a Buffer Zone. J. Environ. Qual. 30:1771–1783.
Poultry P Persists in Pastures
Broiler litter (chicken manure plus bedding material) applied to pastures can increase phosphorus (P) concentration in surface runoff. But it is not well known how long P concentration in surface runoff remains elevated. Pierson et al. now show that the P concentration in surface runoff can remain elevated for more than a year after a broiler litter application. Results suggest that P applied with broiler litter can persist on the surface of pastures for an extended period, thereby increasing its potential environmental impact.
M.L. Cabrera
(mcabrera{at}arches.uga.edu)
Phosphorus and Ammonium Concentrations in Surface Runoff from Grasslands Fertilized with Broiler Litter. J. Environ. Qual. 30:1784–1789.
Will Soil Survive Copper Pesticides?
Copper (Cu) sprays are widely used agriculturally to control plant diseases and are acceptable in organic agriculture, partly because Cu is a natural product with relatively low mammalian toxicity. Epstein and Bassein estimated the amount of Cu that loaded into soil in fields where multiple pesticide applications are made each year. Because Cu tends to accumulate in the topsoil, and many soil microorganisms that are essential for long-term soil function are harmed by Cu, the authors question whether current use of Cu is a sustainable practice in some fruit and nut orchards that are heavily treated.
L. Epstein (lepstein{at}ucdavis.edu)
Pesticide Applications of Copper on Perennial Crops in California, 1993 to 1998. J. Environ. Qual. 30:1844–1847.
Screening for Organotin Compounds in Landfill Leachates
Highly diverse chemical substances are introduced into municipal solid waste landfills. Since the range of possible contaminants exceeds the capabilities of monitoring programs, indicator substances need to be identified to prevent detrimental impacts on health and the environment. Mersiowsky et al. report the occurrence of organotin compounds from several sanitary landfill sites in Sweden, Italy, and Germany. Organotin species—organic metal compounds—were scrutinized due to their widespread industrial use and toxicological relevance. Findings of target compounds from eight landfill sites were below the limit of detection. Octyltin compounds were attributed to PVC products, whereas methylin and butylin compounds derived from diverse sources. Dealkylation and methylation of organotin compounds can occur by microbial transformation.
I. Mersiowsky
(mersiowsky{at}tutech.de)
Screening for Organotin Compounds in European Landfill Leachates. J. Environ. Qual. 30:1604–1611.
A 10-Year-Old Constructed Wetland Still Works
Ten years after construction, a cattail and soft rush–vegetated constructed wetland was still able to treat metal-contaminated leachate from a coal ash pile at the Widows Creek electric utility, Alabama, according to a report by Ye et al. The concentrations of iron and cadmium in inflow water were reduced by >91%, and the sediment was the primary sink for the elements removed from the wastewater. The use of constructed wetlands for the treatment of trace element–contaminated industrial wastewater has been demonstrated effectively in the past, but long-term treatment efficiency of constructed wetlands had not previously been established.
N. Terry (nterry{at}nature.berkeley.edu)
Trace Element Removal from Coal Ash Leachate by a 10-Year-Old Constructed Wetland. J. Environ. Qual. 30:1710–1719.
Herbicides, Nutrients Transported in Irrigation Runoff
During flood irrigation, irrigation water flows over the land surface and drains from the lower portion of the field. Pesticides and plant nutrients in the surface soil may be removed in the runoff water and contaminate downstream waters. Cessna et al. report that herbicide losses in the runoff water were generally <0.05% of amounts applied to flood-irrigated fields, whereas nutrient losses were of the order of 0.6% nitrogen and 1.6% phosphorus applied as fertilizer. Because of the large volume of flow in the South Saskatchewan River, the downstream quality of the river water was not significantly affected by herbicide and nutrient loadings of this magnitude.
A.J. Cessna (allan.cessna{at}ec.gc.ca)
Herbicide and Nutrient Transport from an Irrigation District into the South Saskatchewan River. J. Environ. Qual. 30:1796–1807.
Desorption–Dissolution Model under Reductive Conditions
Natural or provoked situations can cause variations in redox conditions that induce reductive dissolution of soil components. When this happens, heavy metals that may be bound to solid phases are released. To predict this process, Davranche and Bollinger established a surface desorption–dissolution model that considers the effect of reductive conditions on surface site density. The solid dissolution rate was taken into account by following changes in total surface site number (cation exchange capacity) under reductive conditions. This term was introduced in an electrostatic desorption model.
J. Bollinger (jcbollinger{at}unilim.fr)
A Desorption–Dissolution Model for Metal Release from Polluted Soil under Reductive Conditions. J. Environ. Qual. 30:1581–1586.
Plastic Mulch Increases Soil Erosion, Runoff
Fresh-market tomatoes are often grown in raised beds covered with plastic (polyethylene) mulch. Because 50 to 75% of the field is covered with an impervious plastic surface, there will be an increase in the quantity of runoff produced during rain events. Rice et al. now report a significant increase in surface runoff volume, soil erosion with runoff, and the quantity of pesticides measured in runoff from vegetable plots with plastic mulch compared with plots with hairy vetch. Results suggest that fresh-market vegetable production with plastic mulch may have a more harmful impact on the environment than production with the vegetative mulch.
P.J. Rice (price{at}soils.umn.edu)
Runoff Loss of Pesticides and Soil: A Comparison between Vegetative Mulch and Plastic Mulch in Vegetable Production Systems. J. Environ. Qual. 30:1808–1821.
Management Alters Phosphorus Losses
The effect of management practices on phosphorus (P) loss from corn fields extends beyond changes in soil P levels. Bundy et al. report that high soil test P levels and a history of manure application increased runoff soluble P concentrations. Residue accumulation from repeated manure additions lowered runoff volume and soluble P load. Tillage, to incorporate manure, lowered soluble P concentrations in runoff but increased total P concentrations and load due to higher sediment loss. Some practices, such as tillage, may have opposite effects on soluble P and total P losses, emphasizing the need to select practices that will control losses of the P forms having the greatest pollution potential. Results are from a study of P fertilization, tillage, and manure application with simulated rainfall.
L.G. Bundy
(lgbundy{at}facstaff.wisc.edu)
Management Practice Effects on Phosphorus Losses in Runoff in Corn Production Systems. J. Environ. Qual. 30:1822–1828.
Wetting–Drying Events Affect Effluent Transport
Where treated effluents are used for irrigation, there is concern about effluent impacts on pesticide transport. Seol and Lee describe the effects of wetting–drying (22 or 60°C) events on the movement of weakly basic pesticides in soil columns infiltrated with a swine waste–derived lagoon effluent (SW), an effluent-simulated buffer solution (SB), and calcium chloride (CC). The SW and SB increased column leachate pH, enhanced organic matter dissolution, and particle dispersion, and decreased average flow rates compared with CC. The coupled effect of these processes depended on soil texture and pesticide affinity to the soil. Enhanced pesticide movement was observed in some cases, with SW generally having the greatest impact. However, at the higher temperature, drying cycles for some soil–pesticide–effluent combinations, pesticide migration was reduced. The potential for effluent pH, electrolyte composition, and dissolved organic matter to enhance pesticide mobilization has been investigated under saturated or steady state conditions, but the interaction with wetting and drying events has not previously been measured.
L.S. Lee (lslee{at}purdue.edu)
Coupled Effects of Treated Effluent Irrigation and Wetting–Drying Cycles on Transport of Triazines through Unsaturated Soil Columns. J. Environ. Qual. 30:1644–1652.
Deicing Chloride Persists in Road Drainage System
Ever wonder what happens to all the salt applied to icy roads during the winter? Ostendorf et al. now reveal that applied chloride persists throughout the year as a residual source of dissolved contamination. Their findings are based on 3 years of field data, classical linear reservoir theory, and a new dissolution model. Results show that residual solid chloride continues to dissolve into rainfall that occurs in midsummer. They analyzed hyetographs, hydrographs, and pollutographs of an access road drainage system in eastern Massachusetts. Individual storm hydrographs and pollutographs showed dissolved chloride concentrations and residual solid chloride loads that persist at appreciable levels for 27 months. The storm calibrations imply a source strength that accurately models chloride dissolution kinetics through three salt seasons.
D.W. Ostendorf
(ostendorf{at}ecs.umass.edu)
Chloride Persistence in a Deiced Access Road Drainage System. J. Environ. Qual. 30:1756–1770.
Kinetic Modeling of 2,4-D Bioavailability
Park et al. have developed a bioavailability model to describe the desorption and biodegradation processes of 2,4-D herbicide in a slurry system. An enhanced transformation factor was introduced to express the increased biodegradation rate over that expected from the liquid phase only. This approach accounted for the increased degradation rates observed experimentally. Results provide evidence that desorption to the bulk solution is not prerequisite to degradation, and that sorbed substrate may be available for degradation.
T.C. Voice (voice{at}egr.msu.edu)
Kinetic Modeling of Bioavailability for Sorbed-Phase 2,4-Dichlorophenoxyacetic Acid. J. Environ. Qual. 30:1523–1527.
The Robustness of Phosphorus Loading Models
Models for estimating phosphorus loading in catchments are usually based on annual load estimates and verified by infrequent sampling. Hanrahan et al. investigated seasonal trends in phosphorus loads (for the year 1998) as well as annual trends (1990–1998) in a chalk catchment (River Frome, Dorset, UK). The predicted loads were in good agreement with weekly values from a long-term monitoring study. This demonstrates the robustness of the seasonal export coefficient model as a practical management tool.
G. Hanrahan
(ghanrahan{at}plymouth.ac.uk)
Phosphorus Loading in the Frome Catchment, UK: Seasonal Refinement of the Coefficient Modeling Approach. J. Environ. Qual. 30:1738–1746.
Soybean Accumulates Biosolid Molybdenum
Are legumes grown in biosolid-amended soils a troublesome source of molybdenum (Mo) to ruminants? O'Conner et al. report that soybean grown in fields contaminated with high levels of Mo from biosolids did accumulate Mo, but less than expected. Cattle diets typically contain only 
10% soybean meal, but cattle managers should ensure that total cow diets contain sufficiently low Mo materials (e.g., corn grain and stover) and mineral supplements to avoid Mo problems.
G.A. O'Connor (gao{at}ufl.edu)
Bioavailability of Biosolids Molybdenum to Soybean Grain. J. Environ. Qual. 30:1653–1658.
Grain Quality Criteria Exceeded at Low Soil Cadmium
Sewage sludge added to agricultural soils may allow toxic metals such as cadmium (Cd) to enter the food chain. Chaudri et al. used data from a long-term field experiment in which metal-contaminated sewage sludge was added to soil to show that the European Union wheat grain Cd limit was exceeded in soils containing less than the United Kingdom Cd limit of 3 mg kg-1. European Union regulations have set a Cd limit of 0.2 mg kg-1 fresh weight for bran, germ, and wheat grain. Clear seasonal and cultivar effects highlight multifactor influences on grain Cd content, and therefore the difficulty in determining soil Cd limits that are relevant for food quality legislation.
A.M. Chaudri
(amar.chaudri{at}bbsrc.ac.uk)
Cadmium Content of Wheat Grain from a Long-Term Field Experiment with Sewage Sludge. J. Environ. Qual. 30:1575–1580.
Soils May Reduce Allelopathic Expression
Legume cover crops have been shown to reduce weed growth in the subsequent crop in a rotation. However, the effect has been limited to relatively short periods following the incorporation of the crop residue. Ohno reports that oxidation of phenolic acids by metal oxides in soils reduces the phytotoxicity of the model allelochemicals. The results suggest that soils may limit the use allelopathy as a means of managing weeds.
T. Ohno (ohno{at}maine.edu)
Oxidation of Phenolic Acid Derivatives by Soil and Its Relevance to Allelopathic Activity. J. Environ. Qual. 30:1631–1635.
Solutes Leach from Spent Mushroom Substrate
Field weathering of spent mushroom substrate (SMS) produces an organic-rich solution that percolates into underlying soils and ground water. Guo et al. report that SMS leachate contains high concentrations of dissolved organic carbon and nitrogen, and inorganic salts K+, Ca2+, Cl-, and SO2-4. The top 90 cm of soil retains a significant fraction of leachate solutes during the common 2-year cycle of field weathering after mushroom production. The results were obtained by measuring the chemistry and fluxes of SMS and soil leachates in the field. Results suggest weathering of SMS at depths of 90 cm or greater may adversely impact ground water quality.
J. Chorover (jdc7{at}psu.edu)
Leachate Chemistry of Field-Weathered Spent Mushroom Substrate. J. Environ. Qual. 30:1699–1709.
New Method to Predict Partition Coefficients
The soil organic partition coefficient in soil–water systems (Koc) is an important parameter in modeling the behavior of soil pollutants and eventually leaching to ground water. Liang et al. have developed a soil leaching column chromatographic method that predicts the Koc of hydrophobic organic chemicals conveniently from their capacity factors. The method uses a reference soil as the packing material and water (or methanol–water mixtures) as the eluent. This approach could provide a more reliable way to predict Koc at a large scale from a correlation with the capacity factor than other reversed-phase column chromatographic methods.
X. Liang (liangxm{at}mail.dlptt.ln.cn)
Prediction of Soil Organic Partition Coefficients by a Soil Leaching Column Chromatographic Method. J. Environ. Qual. 30:1618–1623.
Biosolids Alter Runoff Water Quality after Forest Fire
Biosolids applied after forest wildfires might enhance revegetation efforts while reducing soil erodibility. Meyer et al. report that biosolids amendment lowered sediment concentrations but had mixed effects on water-quality constituents. Concentrations of all runoff constituents for all treatment rates were below levels recommended for drinking water standards, except lead. They applied Denver Metro Wastewater District composted biosolids at rates of 0, 40, and 80 Mg ha-1 to a severely burned, previously forested site near Buffalo Creek, CO. Simulated rainfall tests were conducted 3 years after the wildfire and 2 years following biosolids addition. Biosolids application to this site increased plant cover, which appears to provide erosion control.
K.A. Barbarick
(kbarbari{at}agsci.colostate.edu)
Biosolids Applications Affect Runoff Water Quality following Forest Fire. J. Environ. Qual. 30:1528–1532.
A Quick and Easy Phosphorus Loss Predictor
Concerns about eutrophication have encouraged development of methods for predicting losses of phosphorus (P) from agricultural soils. Torrent and Delgado demonstrate that the amount of dissolved reactive P (DRP) in a soil water extract is a useful index for predicting the potential release of P from soil to water. The amount of P released from a soil to a dilute electrolyte was proportional to the concentration of DRP in the soil solution raised to a power that decreases with increasing solution to soil ratio. The predictive value of this method was higher than that of the standard Olsen P. The proposed index is relatively insensitive to soil type, making it useful in areas with high soil variability. An additional advantage of their approach is that its determination is simple and rapid.
J. Torrent (cr1tocaj{at}uco.es)
Using Phosphorus Concentration in the Soil Solution to Predict Phosphorus Desorption to Water. J. Environ. Qual. 30:1829–1835.
Enzymes Aid Measurement of Manure Phosphorus
Phosphorus (P) from animal manure is sometimes associated with water quality degradation. He and Honeycutt describe a novel enzymatic approach to identify and quantify organic P forms in animal manure. Sequential fractions of pig and cattle manure were treated with enzymes capable of releasing inorganic P only from certain organic P compounds. Thus, the released inorganic P represents the amount of these organic P compounds in the manure. About one-half of the manure organic P was identified by the enzymatic treatments. This method may be useful for investigating the change and fate of organic P in animal manure, thus providing valuable information for managing manure-derived P in an environmentally responsible manner.
Z. He (zhe{at}maine.edu)
Enzymatic Characterization of Organic Phosphorus in Animal Manure. J. Environ. Qual. 30:1685–1692.
Composted By-Products Stabilize Manure Phosphorus
Inexpensive aluminum and iron by-products, coupled with composting, can immobilize dissolved phosphorus (P) for manure management and pollution prevention, according to a new report by Dao et al. They describe how shifts of dissolved and fluorite-extractable to more stable hydroxide-extractable P fractions reduce dissolved P in poultry manure. Composting alone had no effect on by-product efficacy, but it enhanced P immobilization into the citrate–bicarbonate–dithionite extractable fraction. Results suggested that the choice of immobilization agent affected the eventual stability of immobilized P forms as the iron by-product was more effective on a molar basis. Therefore, nonhazardous municipal and industrial by-products could be used to reduce excessive dissolved P in animal wastes.
T.H. Dao (thdao{at}anri.barc.usda.gov)
Manure Phosphorus Extractability as Affected by Aluminum- and Iron By-Products and Aerobic Composting. J. Environ. Qual. 30:1693–1698.
Soils Reveal Riparian Nitrate Retention Capacity
Although riparian buffer zones can help control nitrate originating from upland activities, their retention capacity varies with site characteristics. This variability can confound our ability to model the export of watershed nitrate and can limit efforts to target riparian restoration and management. Rosenblatt et al. demonstrate an approach to use SSURGO (Soil Survey Geographic Database) map classifications to stratify riparian zones into different levels of ground water nitrate removal capacity. The study focused on 100 randomly selected riparian locations in a variety of glaciated settings within Rhode Island. SSURGO classification based on a combination of geomorphology and hydric soil status created two functionally distinct sets of riparian sites. Results suggest that the SSURGO database can provide important insights into riparian zone nitrate removal potential.
A.J. Gold (agold{at}uri.edu)
Identifying Riparian Sinks for Watershed Nitrate using Soil Surveys. J. Environ. Qual. 30:1596–1604.
Hydrology, Sediment Chemistry Control Stream Water Phosphorus
Many source and transport factors control phosphorus (P) loss from agricultural landscapes at a watershed scale. McDowell and Sharpley report that the release of P from soil and stream sediments was related to the concentration of P at several points in a stream draining an agricultural watershed in central Pennsylvania. Phosphorus concentrations in baseflow were greater at the watershed outlet than at the upper-most point, whereas the opposite occurred during storms. These changes in stream P concentration were related to flow and chemical processes occurring over the watershed and within the stream. During baseflow, P concentrations were controlled by P release from stream sediments. However, erosion and runoff of P from the upper parts of the watershed, coupled with some binding of P by stream sediments, controlled the concentration of P in the stream during storm flows. These results show the importance of the different processes that control P concentrations in a stream and how the processes vary spatially and temporally.
A. Sharpley (ans3{at}psu.edu)
Phosphorus Export from an Agricultural Watershed: Linking Source and Transport Mechanisms. J. Environ. Qual. 30:1587–1595.
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