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EXECUTIVE SUMMARIES

This Issue in Journal of Environmental Quality

	Measuring Gas Production and Movement in Soil

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

S. Allaire (sallaire{at}sga.ulaval.ca)

A Dynamic Two-Dimensional System for Measuring Volatile Organic Compound Volatilization and Movement in Soils. J. Environ. Qual. 31:1079–1087.

	N2O Emissions from Maize–Groundnut Rotation

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Agricultural soils of the humid tropics, receiving large amounts of inorganic and organic N fertilizers, are conducive to N₂O production and release. Khalil et al. report that added chicken manure showed a higher and persistent influence on N transformation and N₂O release than inorganic N alone or in combination with maize and groundnut residues. The mineral N added or mineralized from organic amendments became low by 2 to 4 weeks, coinciding with the small N₂O fluxes or its consumption in a few isolated instances. Direct annual emission from a maize–groundnut rotation was lower than that estimated using methodology of the Intergovernmental Panel on Climate Change. The N₂O–N loss of N applied, either as inorganic N alone or in combination with organic amendment plus N-fixed, ranged from 0.49 to 0.83% from the cropping system, indicating an insignificant response from an agronomic standpoint.

M.I. Khalil

(khalil_ibrahim{at}yahoo.com)

Nitrous Oxide Emissions from an Ultisol of the Humid Tropics under Maize–Groundnut Rotation. J. Environ. Qual. 31:1071–1078.

	Atmospheric MTBE in Rural California

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Atmospheric methyl tertiary butyl ether (MTBE) was measured near the University of California–Berkeley Blodgett Forest Research Station on the western slope of the Sierra Nevada Mountains of California. Concentrations were generally lower than 0.3 ppb and the diurnal cycle reflected transport from and dilution of sources in the Central Valley. Correlations and ratios of MTBE to other anthropogenic hydrocarbons and back-trajectory analysis were used to determine an average regional hydroxyl radical concentration, and to conclude that nonequilibrium ground deposition is small compared with oxidation in the atmosphere.

G.W. Schade

(gws{at}nature.berkeley.edu)

Atmospheric Methyl Tertiary Butyl Ether (MTBE) at a Rural Mountain Site in California. J. Environ. Qual. 31:1088–1094.

	Transport of Bacteriophage in Shale Saprolite

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Tracer experiments in a column of undisturbed fractured shale saprolite collected at a depth of 1.2 to 1.4 m show that microbial contaminants, in this case the bacteriophage strains PRD-1 and MS-2, can be transported rapidly and with little attenuation in these materials. Bacteriophage retention decreased substantially as the saturated flow rate increased, suggesting microbial transport in these materials will tend to be episodic, coinciding with heavy rains and rapid flow rates.

L.D. McKay (lmckay{at}utk.edu)

Influence of Flow Rate on Transport of Bacteriophage in Shale Saprolite. J. Environ. Qual. 31:1095–1105.

	Competition for Sorption Sites on Zeolite

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Competition between cationic surfactants and metal cations for sorption onto negatively charged mineral surfaces has strong influence on the use of surfactants for environmental remediation. Sorption capacity and the affinity for Cs⁺, Sr²⁺, La³⁺, Pb²⁺, and Zn²⁺ of clinoptilolite decreased as surfactant loading on the zeolite increased, indicating pre-sorbed cationic surfactants block sorption sites for metal cations. On the other hand, sorption of cationic surfactants on zeolite preloaded with different metal cations and the desorption of pre-sorbed metal cations by cationic surfactants were strongly affected by chain length of the surfactant tail groups. More metal cations desorbed as the surfactant chain lengths increased, indicating cationic surfactant may be used as desorbing agents for ex situ soil decontamination.

Z. Li (li{at}uwp.edu)

Influence of Quaternary Ammonium on Sorption of Selected Metal Cations onto Clinoptilolite Zeolite. J. Environ. Qual. 31:1106–1114.

	Competitive Adsorption between Arsenic and Organic Acids

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Naturally occurring, ubiquitous organic acids such as humic (Hap), fulvic (FA), or citric acid (CA) may increase the bioavailability of arsenate [As(V)] and arsenite [As(III)] at the iron oxide–water interface. Arsenate adsorption on ferrihydrite was lowered in the presence of CA between pH 3 and 5, whereas Hap and FA had no effect on As(V) adsorption. The adsorption of As(III) on ferrihydrite was lowered by CA and FA between pH 3 and 7, but not by Hap. Results of this study stand in contrast to a previous study with goethite and show the importance of the adsorbent phase in competitive adsorption reactions of the arsenic–organic acid system. Additional research is needed examining other common mineral surfaces.

M.J. Eick (eick{at}vt.edu)

Adsorption of Arsenate and Arsenite on Ferrihydrite in the Presence and Absence of Dissolved Organic Carbon. J. Environ. Qual. 31:1115–1123.

	Fate of Dimethyldiselenide

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Behavior of dimethyldiselenide in the soil environment is important in understanding the biogeochemical cycling of selenium (Se). Zhang and Frankenberger report dimethyldiselenide is not a stable form of Se in soil. Dimethyldiselenide was highly dissolved in water and sorbed onto soil. Chemical and biological transformations of dimethyldiselenide converted a large amount of dimethyldiselenide to elemental Se and nonvolatile organic Se. Microbial conversion of dimethyldiselenide to dimethylselenide indicated dimethyldiselenide may be one of the important precursors of dimethyselenide in the soil environment.

W.T. Frankenberger, Jr.

(williamf{at}orange.ucr.edu)

Fate of Dimethyldiselenide in Soil. J. Environ. Qual. 31:1124–1128.

	Copper Adsorption–Desorption in Contaminated Soils

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Copper (Cu) concentrations have reached contaminating levels in some soils through applications of Cu-containing fungicides, stable manures (e.g., pig slurry), and liquid or solid wastes from Cu-related mining and manufacturing. Understanding adsorption–desorption behavior of Cu²⁺ is important for management of Cu-contaminated soils. Yu et al. show adsorption and desorption of Cu²⁺ at contaminated levels in two red soils could be described by the Freundlich and the simple Langmuir models. Adsorption of Cu²⁺ decreased with soil pH and the number of protons released per Cu²⁺ adsorbed increased with increasing Cu²⁺ concentration up to a Cu loading of 2 g kg^-1 soil. The distribution coefficient (K_d) of Cu²⁺ in the soils decreased exponentially with increasing Cu²⁺ loadings. After five successive extractions with 1 mol L^-1 NH₄Ac (pH 5.0), 61 to 95% of the total adsorbed Cu²⁺ was desorbed, indicating high release potential of the adsorbed Cu²⁺.

Z.L. He (zhe{at}mail.ifas.ufl.edu)

Adsorption–Desorption Behavior of Copper at Contaminated Levels in Red Soils from China. J. Environ. Qual. 31:1129–1136.

	Low Levels of Lead Found in Appalachian Hardwoods

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
While there have been many studies assessing the condition of the spruce–fir ecosystem in the southern Appalachian Mountains, there is scarce published data regarding northern hardwood forest health in that region. Fisher et al., using dendrochemical techniques, examined concentrations of Pb and Ca in growth rings of an important northern hardwood species, American beech, at Mount Rogers and Whitetop Mountain, Virginia. They examined the relationships between metal concentration and stem growth patterns at research plots established at two elevations (1371 and 1524 m). Decadal measurements of ring widths were inversely correlated with Pb and Ca concentrations and higher-elevation plots contained increased concentrations of Pb. Lead and calcium concentrations in rings were associated with decreased growth measurements. Although an increased trend of both Pb and Ca concentrations was observed over time, specifically during the 1860s and mid-1900s, maximum concentrations of Pb found in tree rings located on Mt. Rogers and Whitetop Mountain were considered lower than levels found in tree rings taken in other regions that are considered contaminated.

L.S. Fisher (fishers{at}ornl.gov)

Dendrochemical Analysis of Lead and Calcium in Southern Appalachian American Beech. J. Environ. Qual. 31:1137–1145.

	Selenium Sequestration Revealed by Stable Isotopes

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Selenium (Se) contamination is a pervasive concern in the western San Joaquin Valley of California, particularly in areas associated with agricultural drainage water. Selenium stable isotope ratios can be used as indicators of Se transformation processes, and are especially useful in distinguishing between (i) plant and algal uptake (assimilation) of Se oxyanions followed by deposition and mineralization of the reduced Se, and (ii) chemical or bacterial respiratory reduction of Se oxyanions to elemental Se. Herbel et al. measured ⁸⁰Se/⁷⁶Se ratios in macrophytes, surface and shallow ground waters, and sediment extracts of constructed flow-through wetland, agroforestry, and evaporation pond systems, which were designed to treat or impound Se-affected drainage water. Comparisons of the ⁸⁰Se/⁷⁶Se values indicate that assimilatory reduction, deposition, and mineralization, rather than chemical or bacterial respiration reduction, was the dominant reduction and accumulation pathway in sediments at the investigated sites. This work demonstrates the utility of Se stable isotope analyses in the first such study of San Joaquin Valley contamination.

M.J. Herbel (mjherbel{at}usgs.gov)

Selenium Stable Isotope Ratios in California Agricultural Drainage Water Management Systems. J. Environ. Qual. 31:1146–1156.

	Soil Factors Contributing to Trace Metal Mobility

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Dissolved organic matter is expected to contribute to trace metal mobility in soils of neutral to alkaline pH following amendment with biosolids. The concentrations of dissolved organic carbon (DOC) and Cu collected 10 cm below the zone of biosolids addition were increased in both an irrigated and dryland soil, resulting in a positive correlation between Cu and DOC. Zinc mobility was positively correlated with electrical conductivity, suggesting a cation exchange mechanism influenced Zn mobility.

D. Heil (dheil{at}lamar.colostate.edu)

Solution Chemistry Influence on Metal Mobility in Biosolids-Amended Soils. J. Environ. Qual. 31:1157–1165.

	Winter-Applied Manure Alters Snowmelt

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Although the practice of manure landspreading in winter is thought to lead to excessive P runoff losses, field experiments to explore the issue are extraordinarily difficult. To learn the effects of winter-applied manure on snowmelt, experiments were performed to partition the problem into tractable parts, and the phenomena was captured in a mechanistic snow ablation model. The manure–snow model simulated the observed delay in snow cover disappearance caused by manure. Model simulations showed that during intense melting events, manure reduced the energy available for melt to the underlying snow. Even relatively light applications of manure gave substantial reductions in peak melt rate. Lower peak rates beneath manure may allow greater infiltration of meltwater compared with bare snow. This enhanced infiltration and attenuated peak water outflow rate may partially mitigate the enhanced likelihood of P runoff of unincorporated winter-spread manure.

C. Kongoli (Cezar.Kongoli{at}noaa.gov)

Influence of Manure Application on Surface Energy and Snow Cover: Field Experiments. J. Environ. Qual. 31:1166–1173.

Influence of Manure Application on Surface Energy and Snow Cover: Model Development and Sensitivities. J. Environ. Qual. 31:1174–1183.

	Modeling Atmospheric N Deposition and Transport

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Atmospheric deposition of nitrate-N and ammonium-N has been identified as a major factor in the decline of water quality in the Chesapeake Bay, and may account for 25 to 80% of the total N load. Recent estimates were reassessed using a high-resolution wet deposition model, improved dry deposition and nutrient retention estimates, existing soils and land use data, and geographic information systems software. Model results for years 1984 to 1996 indicate atmospheric N deposition represents 20 to 32% of the total N load to the Chesapeake Bay. Data suggest dry N deposition is considerably less than previous estimates, and substantial inter- and intra-annual variation in N deposition rates exist that should be considered in management strategies.

S.A. Sheeder (sas371{at}psu.edu)

Modeling Atmospheric Nitrogen Deposition and Transport in the Chesapeake Bay Watershed. J. Environ. Qual. 31:1194–1206.

	Vegetation Change Linked to Nutrient Losses

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Hillslopes in central California, once covered by coastal sage scrub communities, have been largely replaced with annual grasslands. Fierer and Gabet conducted rainfall simulation experiments to determine the impact of this vegetation change on rates of C and N removal in surface runoff waters. Results from these experiments were incorporated into a numerical model to estimate hillslope scale sediment-bound nutrient losses. They found type conversion of coastal sage scrub to annual grasslands increases hillslope nutrient losses and this may have profound effects on stream water quality in the region.

N. Fierer (fierer{at}lifesci.ucsb.edu)

Carbon and Nitrogen Losses by Surface Runoff following Changes in Vegetation. J. Environ. Qual. 31:1207–1213.

	Agroforestry Reduces NPS in Water

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Agroforestry practices purport to play a significant role in nonpoint-source pollution reduction. Udawatta et al. have demonstrated that agroforestry and contour strips reduce runoff, sediment, phosphorus, and nitrate loss from agricultural watersheds in a corn–soy-bean rotation. Further, as trees grow and their root systems expand, greater impacts are expected, especially in further reducing the export of nutrients off site.

R.P. Udawatta

(udawattar{at}missouri.edu)

Agroforestry Practices, Runoff, and Nutrient Loss: A Paired Watershed Comparison. J. Environ. Qual. 31:1214–1225.

	Polymer Effects on Herbicide Sorption

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Application of polymers to soil to enhance infiltration and reduce soil erosion is a growing practice. Among the polymers, polyacrylamide is the one most frequently used. The impacts of polyacrylamide and other polymers on sorption of herbicides were assessed by the batch equilibrium method. Polyacrylamide treatment kinetically reduced the sorption rate of all herbicides. The effects of polymers on the equilibrium sorption amounts of herbicides depend on the charge and molecular characteristics of polymers and herbicides, and salt concentration in the solution. At high salt concentrations, equilibrium sorption amounts of all herbicides were essentially unaffected or slightly decreased by the polymers, while at low salt concentrations, polymers could slightly increase or decrease herbicide sorption. Electrostatic interaction and competition for sorption sites are two primary underlying mechanisms for the polymer influence.

L. Wu (laowu{at}mail.ucr.edu)

Anionic Polyacrylamide Effects on Sorption and Desorption of Metolachlor, Atrazine, 2,4-D, and Picloram. J. Environ. Qual. 31:1226–1233.

Picloram and Napropamide Sorption as Affected by Polymer Addition and Salt Concentration. J. Environ. Qual. 31:1234–1239.

	Site-Specific Fertilizer Phosphorus Application

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
Site-specific management of P is done to optimize crop production and to minimize the loss of P from soils. The spatial variability of the available P before fertilizer application (P₀) and the P fixation tendency of soil both need to be taken into account for variable-rate P application. Lee et al. document the spatial variability of the fertilizer P availability index (F_p), which shows the P fixation tendency, and develop a strategy that takes the spatial distribution of this index into account for site-specific P application. They used ordinary kriging in spatial interpolation of F_p and P₀. The spatial distributions of both F_p and P₀ were simultaneously used to make a recommendation map for variable-rate P application.

D.Y. Lee (dylee{at}ccms.ntu.edu.tw)

Site-Specific Phosphorus Application Based on the Kriging Fertilizer-Phosphorus Availability Index of Soils. J. Environ. Qual. 31:1248–1255.

	Protect Topsoil from Wind Erosion in Northwest China

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide Copper Adsorption-Desorption in... Low Levels of Lead... Selenium Sequestration Revealed... Soil Factors Contributing to... Winter-Applied Manure Alters... Modeling Atmospheric N... Vegetation Change Linked to... Agroforestry Reduces NPS in... Polymer Effects on Herbicide... Site-Specific Fertilizer... Protect Topsoil from Wind... Water Quality in Georgia... Geographic Variability of... Predict Phosphorus Loss from... The Search for a... Mixing Soil Aggregates Alters... Soil-Bound Contaminants and... Manure and Fertilizer Effects... Compost Curing Influences... Reduce Ammonia Losses from... Wastewater Sludge as a... Wastewater Treatment Process... Water Treatment Residuals Reduce... Relating Soil Test P... Ag Lands-Wetlands May Release...

 
For decades, wind erosion has triggered dust/sand storms, buffeting Beijing and areas of northwest China to the point of being hazardous to human health while rapidly eroding crop and livestock productivity. The EPIC (Environmental Policy Integrated Climate) field-scale simulation model was used to assess long-term impacts of improved crop rotations and crop residue management practices on wind erosion in Inner Mongolia, China. Simulation results indicate preserving crop stalks until land is prepared by zone tillage for the next year's crop in lieu of using stalks as a source of heating fuel or livestock fodder reduces wind erosion by 60%. At the same time, grain and potato yields were maintained or improved. Reductions in erosion also resulted from delaying stalk removal until late January through late April. Altering current crop rotation systems by expanding corn, wheat, and millet, and reducing potato and pea production, reduced simulated wind erosion, thus diminishing the severity of dust/sand storms in northwestern China. Saving and protecting topsoil over time will sustain land productivity and has long-term implications for improving conditions of rural poverty in the region.

E. Wang (wang{at}tarleton.edu)

Simulated Effects of Crop Rotations and Residue Management on Wind Erosion in Wuchuan, West-Central Inner Mongolia, China. J. Environ. Qual. 31:1240–1247.

	Water Quality in Georgia Streams

TOP Measuring Gas Production and... N2O Emissions from Maize... Atmospheric MTBE in Rural... Transport of Bacteriophage in... Competition for Sorption Sites... Competitive Adsorption between... Fate of Dimethyldiselenide