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EXECUTIVE SUMMARIES

This Issue in Journal of Environmental Quality

	Crust Formation Reduces Ammonia Emissions

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

	Methyl Bromide Air Concentration Predicted by Use

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
The exposure assessment of methyl bromide depends on estimation or measurement of its air concentrations. Li et al. (p. 420–428) propose a methodology for systematically exploring the empirical relationship between methyl bromide use intensity and ambient air concentrations. Monitored air concentrations were regressed to methyl bromide use over various spatiotemporal scales that step-wise increased around the monitoring site and monitoring period. Results showed the best fit was Y = 0.46 + 0.00120X (R² = 0.95, n = 11), where Y was the 8-wk average ambient air concentration (µg/m³) and X was the weekly average use (kg/wk) over an area of 11.3 x 11.3 km² (7 x 7 mile²). This model can be used in methyl bromide subchronic exposure assessment from field fumigation.

	Milk Production Intensity and Greenhouse Gas Emissions

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Livestock production is a major contributor to Ireland's greenhouse gas (GHG) emissions. Life cycle assessment methodology was used to compare GHG emission for Irish dairy units operating within an agri-environmental scheme and as conventional dairy units. Casey and Holden (p. 429–436) show that on average total emissions from conventional units were around 18% greater than the agri-environmental scheme units, while emissions per hectare were 17% greater but there was no significant difference in terms of emission per unit milk produced. In terms of the intensity of milk production, it was concluded that fewer cows producing more milk at lower stocking rates are required to achieve a national reduction in GHG emissions from Irish dairy production. Such a move would represent extensification in terms of area, but intensification in terms of animal husbandry.

	Tillage Affects Soil Carbon Dioxide Emission

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Intensive tillage systems can induce soil carbon dioxide (CO₂) emission and soil C loss. Al-Kaisi and Yin (p. 437–445) report that no-tillage and strip-tillage systems significantly increased total soil organic C at the 0- to 10-cm soil depths compared with chisel and moldboard plow tillage systems after 3 yr of tillage practices. Soil CO₂ release immediately after tillage operation with moldboard plow was significantly greater than that from conservation tillage systems. Cumulative soil CO₂ release from soil with conservation tillage systems was 19 to 41% less than moldboard plow tillage system. Adopting less intensive tillage systems such as no-tillage and strip-tillage are effective in reducing CO₂ emission, thus improving soil C sequestration in a corn–soybean rotation.

	Subirrigation Enhances Reduction of N2O to N2

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Water table management, consisting of free drainage and controlled drainage–subirrigation, is a beneficial practice that has been shown to improve drainage water quality by reducing nitrate pollution through enhanced denitrification. Denitrification is the major biological process by which nitrates are reduced to N₂, with nitrous oxide (N₂O) being an intermediary product. Whether nitrate removal by denitrification is beneficial to the wider environment depends on whether the dominant end product is N₂O or N₂. Elmi et al. (p 446–454) report on a 2-yr field-scale study during which total denitrification (N₂O + N₂), N₂O production, and N₂O to N₂O + N₂ ratios in subsurface environment (0–0.45 m) as influenced by water table management were quantified. Denitrification rates in the soil profile were generally greater under subirrigation than free drainage in most sampling dates. Ratios of N₂O to N₂O + N₂ were lower in subirrigation plots than free drainage, suggesting the subirrigation treatment created conditions that enhance further reduction of N₂O to N₂. It was concluded that higher denitrification rates under subirrigation than free drainage do not necessarily add to concerns over global atmospheric N₂O loadings as the majority of gaseous N would have been emitted as N₂ under our field conditions.

	Methane Oxidation Discovered in Slurry Storages

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Livestock manure is a significant source of atmospheric methane (CH₄), especially during liquid storage. Petersen et al. (p. 455–461) show that methane-oxidizing bacteria inhabit surface crusts of slurry storages and conclude that the process is a potentially important sink for methane produced during storage. Surface crust materials were sampled from experimental storages with cattle slurry or anaerobically digested cattle slurry. Methane was oxidized by extracts of surface crust material and by field-moist material, but not by autoclaved samples. Partial drying of surface crust samples stimulated methane oxidation. Methane oxidation rates were comparable with the activity in wetlands and rice paddies. Measures to ensure crust formation with or without a solid cover appear to be a cost-effective greenhouse gas mitigation option.

	Unraveling Complexities of Polycyclic Aromatic Hydrocarbon Degradation

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Polycyclic aromatic hydrocarbons, such as phenanthrene and naphthalene, are ubiquitous pollutants and can sometimes resist biodegradation. Phytooxidation is often listed as a cause of structural changes that can promote or inhibit biodegradation of these compounds. Holt et al. (p. 462–468) report that 9,10-phenanthrenequinone catalyzes its own formation as the main photoproduct of phenanthrene. This quinone also inhibits biodegradation of naphthalene, while phenanthrene itself does not. Finally, one phenanthrene-degrading enrichment culture degrades the quinone cometabolically. These behaviors of 9,10-phenanthrenequinone are even more interesting as they apply to complex mixtures such as creosote.

	Straining and Attachment of Oocysts

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Knowledge of the processes that control the movement and fate of pathogenic Cryptosporidium parvum oocysts is required to protect water supplies. Previous studies and models have neglected straining as a mechanism of oocyst deposition, and assumed that oocyst migration was controlled by attachment. Laboratory and mathematical modeling studies were undertaken by Bradford and Bettahar (p. 469–478) to examine mechanisms of oocyst transport and deposition in ground water systems. Results indicate that oocysts can also be retained in small pores due to straining. The ability of a mathematical model to describe oocyst transport in three sands was improved by inclusion of straining, attachment, and detachment.

	Desorption of Arsenate from Kaolinite

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Arsenic is highly toxic and therefore represents a potential threat to the environment and human health. The mobility and bioavailability of As in soil is mostly controlled by adsorption and desorption reactions. Quaghebeur et al. (p. 479–486) report that the amount of arsenate desorbed over time using a flow-through setup was higher in comparison with the amount desorbed over time using a traditional batch desorption setup. The pH had a large effect on the amount of arsenate desorbed from kaolinite, with both an increase and a decrease in pH (from the initial pH 6.4) enhancing arsenate desorption. Modelling desorption over time revealed that pH can influence arsenate desorption over extended periods of time.

	Selenium Removal by Zerovalent Iron

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Removal of Se from Se-contaminated water is important in protecting wetland wildlife. Zhang et al. (p. 487–495) used zerovalent Fe to remove selenate from water in the presence of varying concentrations of Cl^–, SO₄^2–, NO₃^–, HCO₃^–, and PO₄^3–. Under an open condition, zerovalent Fe effectively removed 100 and 93% of the added selenate in the 10 mM Cl^– and SO₄^2– solutions, respectively. Selenate was also removed from 5, 50, and 100 mM Cl^–; 1, 5, and 10 mM NO₃^–; 5, 50, and 100 mM SO₄^2–; 1, 5, and 10 mM HCO₃^–; and 1 and 5 mM PO₄^3– solutions during a 2-d experiment. This work suggests zerovalent Fe may be an effective agent to remove Se from Se-contaminated agricultural drainage water.

	Prediction of Metal Availability to Wheat

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
This is the first paper to investigate bioavailability of a suite of metals in soil simultaneously using such a comprehensive set of chemical techniques. It is also the first time the new technique of diffusive gradients in thin films (DGT) and the concept of effective concentration (C_E) have been used to assess Zn, Cd, Cu, and Pb availability to wheat. Nolan et al. (p. 496–507) found that Zn uptake is best predicted by DGT, Pb uptake by DGT and soil solution, Cd uptake by DGT and CaCl₂ extractable, and surprisingly Cu uptake by total Cu. The underlying processes that determine these findings are discussed.

	Copper Availability in Biosolids-Amended Israeli Soils

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Although having many potential benefits, land application of biosolids may pose a risk to the environment because the material commonly has high concentrations of heavy metals (with Cu being a major concern). It is therefore important to determine whether the practice will lead to Cu toxicity in the environment, particularly over the medium to long term when organic matter and other protective components in the biosolids may break down. Oliver et al. (p. 508–513) report that, even when applied at rates vastly exceeding current practices, the availability of Cu sourced from biosolids was low and stable, and did not increase over a 7-yr period. Therefore, current practices do not pose a significant risk to the environment in terms of Cu toxicity. The availability of Cu was monitored using isotopic dilution techniques.

	Lake Sediments Characterize Catchment Erosion

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Increasing concern for the problems of soil degradation and associated off-site sedimentation at the regional and global scale has highlighted the need for improved information on rates of soil loss and sediment sources and thus for new approaches to assembling such information. Zhang and Walling (p. 514–523) report how the Cs-137 content of sediment cores collected from lakes and reservoirs can be used to characterize surface erosion rates and the main sediment sources in the upstream catchment. The rate of decline of Cs-137 concentrations in the upper part of a sediment core provides valuable information on the rate of soil loss from the eroding areas of the upstream watershed. Equally, the magnitude of the Cs-137 concentrations in recently deposited sediment provides a means of assessing the relative importance of surface and channel, gully, and/or subsurface erosion in contributing to the sediment deposited in the lake or reservoir. The approach has been successfully tested using the Cs-137 profiles for sediment cores collected from lakes and reservoirs in areas representative of a wide range of erosion intensities.

	Ground Water Denitrification in Deep Riparian Wetland Soils

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
The contribution of riparian areas to the catchment-scale N budget is of great interest to researchers and land use managers. Kellogg et al. (p. 524–533) found that within two common geomorphic settings (i.e., glacial outwash and alluvial), riparian wetlands can remove substantial ground water nitrate at depths down to 3 m at sites located in permeable stratified sediments. Correlations of site characteristics with in situ ground water denitrification rates varied with depth below the soil surface. At 65 cm, ground water denitrification rates varied with factors associated with the surface ecosystem (temperature, dissolved organic C). At deeper depths, ground water denitrification rates were significantly higher closer to the stream where the subsoil often contains organically enriched deposits that indicate fluvial geomorphic processes, such as intermittent flooding events and stream meandering. High ground water denitrification rates observed in hydric soils down to 3 m within 10 m of the stream in both alluvial and glacial outwash settings argue for the importance of both types of riparian wetland settings as potential N sinks at the catchment scale.

	Herbicide Leaching in Tropical Soils

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Intensive application of organic chemicals to a newly irrigated sugarcane area in the semiarid western part of Reunion Island (France) has prompted local regulation agencies to question the potential to contaminate ground water resources. Bernard et al. (p. 534–543) used the simple attenuation factor approach to assess potential leaching of five herbicides through the vadose zone of two Inceptisols. Results show a lower risk of leaching in temperate regions due to the tropical conditions characterized by higher temperatures and an abundance of highly adsorbent soils. Potential leaching of the herbicides was found to be unlikely except during the raining period (December to mid-April) and especially 40 d within February and March when there is a 2.5% probability of recharge rates equal to or higher than 50 mm d^–1.

	New Insights into Chlordane Contamination

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Sediments are increasingly recognized as both carrier and potential source of contaminants in aquatic environments. Using linear regression and principal axis analysis, Ouyang et al. (p. 544–551) discovered that a linear correlation existed between -chlordane and total chlordane as well as between -chlordane and total chlordane, whereas no correlation existed between trans-nonachlor and total chlordane. A GIS-based kriging analysis showed that the Cedar River and the north end of the Ortega River in Florida, USA, had total sediment chlordane concentrations above the probable effect level (4.79 µg/kg), which could pose a potential risk to aquatic life.

	Hydrophobic Fractions Sorb Organic Compounds

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Dissolved organic matter (DOM) from wastewater can affect the sorption behavior of organic compounds in soils. Ilani et al. (p. 552–562) have tested the role of structural fractions of wastewater DOM in sorption of organic pollutants. For all sorbates, binding to the hydrophobic neutral (HoN) fractions was much higher than to the hydrophobic acid (HoA) fractions and bulk DOM. Higher sorption coefficients were exhibited by DOM samples containing a higher level of hydrophobic fractions (HoA + HoN), suggesting the sorption of hydrophobic organic compounds by DOM is governed by the level of these structural substances. Although the HoN fraction made up a relatively small portion of DOM (<10%) and is mainly composed from aliphatic moieties, it is a dominant sorbent, especially in DOM, which is characterized by low hydrophobicity.

	Phytase Does Not Increase Phosphorus Solubility

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Poultry and swine growers routinely include phytase in dietary formulations. Phytase improves diet P availability by cleaving phytate bonds that are abundant in cereal grains typically fed to livestock. By cleaving the phytate bond, the cereal grain P can be absorbed by swine and poultry. However, this has raised the concern of whether or not phytase increases the solubility of excreted P, thereby increasing the risk for short-term environmental pollution. The goal of research by Angel et al. (p. 563–571) was to determine if phytase, when fed correctly with a concurrent reduction in dietary total phosphorus (TP), increased excreted water-soluble phosphorus (WSP) or if observed increases in WSP are due to microbial activity, post-excretion. Experiments were conducted with broiler chickens, turkeys, and swine. Incubation of excreta resulted in increased WSP, irrespective of phytase addition. Addition of antibiotics before incubation prevented the increase in WSP. Therefore, when phytase is used properly (i.e., with a simultaneous decrease in non-phytin P), WSP or WSP as a percent of TP are not affected. The increase in WSP as a percent of TP post-excretion is a function of excreta microbial activity and not dietary phytase addition.

	One Extraction Coefficient Predicts Runoff Phosphorus

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Computer models help identify agricultural areas with high potential for P transport in runoff. Most models use a constant extraction coefficient to predict dissolved P in runoff from soil P, but it is unclear how extraction coefficients should vary to account for soil properties, management practices, or hydrology. In a literature review, Vadas et al. (p. 572–580) found that for 18 studies, extraction coefficients using Mehlich-3 or Bray-1 soil P data did not differ for 26 of 31 soils. When using water-extractable soil P data, extraction coefficients for 17 of 20 soils did not differ. Finally, extraction coefficients using soil P sorption saturation data were the same for all 10 soils investigated. This review justifies the use of a constant extraction coefficient in models.

	Resuspension of Bacteria-Laden Sediments

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
The association of microorganisms with sediment particles is one of the primary complicating factors in assessing microbial fate in aquatic systems. Jamieson et al. (p. 581–589) relate the transport characteristics of Escherichia coli to the sediments to which they were attached, and illustrate that the resuspension of contaminated bed sediments contributes to water quality degradation during stormflow events. In streams possessing a mixture of cohesive and noncohesive sediments, the transport properties of the cohesive sediments will largely control the movement of sediment-associated bacteria.

	Reducing Nitrate Losses to Tile Drainage

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Substantial amounts of nitrate from agricultural crop production systems can be transported to surface water in subsurface drainage from poorly drained soils. Randall and Vetsch (p. 590–597) measured nitrate losses in subsurface drainage from a corn–soybean rotation as affected by fall and spring application of N as anhydrous ammonia and nitrapyrin (NP), a nitrification inhibitor. Nitrate concentrations and losses averaged across the six years were highest for fall N and lowest for spring, preplant N, but concentrations were still greater than the drinking water standard (10 mg L^–1) in three of six years, when using the recommended application rate. Nitrapyrin applied with ammonia in the fall reduced nitrate concentrations in the drainage water but not when applied in the spring. Under these conditions, losses of nitrate in subsurface tile drainage from a corn–soybean rotation were reduced by 10% when including NP with fall-applied N, by 14% with spring, preplant N, and by 6% when including NP with spring-applied N compared with fall N without NP.

	Phosphorus Bioavailability Decreases as Dung Dries

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Knowledge of the bioavailability of P in dung from grazing animals is important for soil fertility, transfer in runoff, and potential surface water quality deterioration. McDowell and Stewart (p. 598–607) report that analysis by sequential fractionation of fresh and air-dry dung of dairy cattle, deer, and sheep grazing pasture showed that P in fresh dung was in bioavailable water and biocarbonate fractions, and shifted to more recalcitrant HCl and residual P fractions when air-dried. Furthermore, changes in organic P detected by ³¹P nuclear magnetic resonance of NaOH-EDTA extracts were attributed to degradation of bioavailable orthophosphate diesters to monoesters. This decrease in bioavailability with moisture status has implications for the positioning and timing of grazing in relation to hydrologically active areas likely to produce runoff and for soil fertility.

	Leaching of Glyphosate and AMPA from Field Sites

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Leaching of pesticides is an important process with respect to contamination risk to the aquatic environment. Kjær et al. (p. 608–620) report that as both glyphosate and amino-methylphosphonic acid (AMPA) can leach through structured soils, they thereby pose a potential risk to the aquatic environment. At one loamy soil, glyphosate and AMPA thus leached from the root zone into tile drains (1 m below ground surface) in average concentrations exceeding 0.1 µg L^–1, which is the EU threshold value for drinking water. On another loamy soil, where precipitation was less and of lesser intensity, residence time in the root zone seems to have been sufficient to prevent leaching of glyphosate. Although leaching of AMPA was observed at this site, the concentrations were generally low, being in the order of 0.05 µg L^–1 or less. On the coarse sandy soil, however, the risk of glyphosate leaching was found to be negligible. Infiltrating water passed through a matrix rich in Al and Fe, thus providing good conditions for both sorption and degradation.

	Data Availability Affects Parameter Identification

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
A major problem with dual-permeability pesticide leaching models has been the lack of reliable procedures for parameter identification. Larsbo and Jarvis (p. 621–634) investigated six parameters controlling macropore flow and pesticide sorption and degradation, applying the model MACRO to a comprehensive field data set of bromide and bentazone transport in a structured soil. Generalized likelihood uncertainty estimation analyses of parameter conditioning for different combinations of field data showed that both resident and flux concentrations were needed to obtain highly conditioned and unbiased parameters and that data on tracer transport generally improved the conditioning of macropore flow parameters. However, not all selected parameters were highly conditioned by the observations even with the complete data set.

	Effluent Treatment Differs Between Soils

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Land application is a widely applied practice for treating wastewater. Barton et al. (p. 635–643) show how four contrasting soil types varied in their ability to treat effluent applied N and P, and hence limit nutrient leaching. Matching effluent nutrient loadings to plant N uptake, plant P uptake, and soil P storage minimized nutrient leaching. Choosing soil types and irrigation rates that minimize preferential flow and maximize the time effluent spends in the surface soil further reduced the risk of nutrient leaching. Leaching of native soil N may be an additional source of N that needs to be considered when designing land-treatment systems. Furthermore, measuring total N and total P, in addition to inorganic forms, is recommended when measuring the leaching of these elements from effluent irrigated soils.

	Feedlot Soil Composition Determines Emissions

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
The manure and moisture content on cattle feedlots varies across the feedlot pen and with time and is a major factor controlling greenhouse gas emissions, odor compound production, N transformations or losses, and dust. Over a 2-wk period, Miller and Berry (p. 644–655) measured gas fluxes, odor compound content, nitrogenous compounds, and the dust potential in three artificial feedlot surface mixtures at six moisture levels. Based on their results, they developed a model describing the relationship among manure, moisture, dominant microbial activities, and the potential environmental consequences associated with the varying manure and moisture landscape of cattle feedlot pens.

	Feedlot Soil Composition Affects Pathogen Survival

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
The moisture and manure contents of soils at cattle feedlot surfaces vary spatiotemporally and probably are important factors in the persistence of zoonotic pathogens in the animal production environment. Berry and Miller (p. 656–663) investigated the impacts of water and manure content on E. coli O157:H7 in feedlot soils, and found that levels of this pathogen either persisted or increased at all but the lowest water contents examined. Manure content modulated the effect of water on E. coli growth, suggesting that increases in manure content may reduce the water potential of feedlot soils. The E. coli and coliform populations responded similarly to E. coli O157:H7. Because high numbers of E. coli O157:H7 can survive in feedlot soils over a wide range of water and manure contents, the pen surface may be an appropriate target for interventions to reduce this pathogen from the feedlot environment.

	Modeling Carbon and Nitrogen Transformations of Compost

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Environmentally sound management of composts in agriculture relies on matching the release of available N from compost-amended soils to crop demand. Beraud et al. (p. 664–675) determined the decomposition rate parameters of two composts under controlled conditions, and then used the NCSOIL model to predict mineral-N concentration dynamics in a soil–wheat system after successive annual applications of compost. Sewage sludge compost (SSC) and cattle manure compost (CMC) mineralization characteristics showed similar partitioning into two components of differing ease of decomposition. The labile component accounted for 16 to 20% of total C and 11 to 14% of total N, and it decomposed at a rate of 2.4 10^–2 d^–1, whereas the resistant pool had a decomposition rate constant of 1.2 to 1.4 x 10^–4 d^–1. The main differences between the two composts resulted from their total C and N, and inorganic N contents, which were determined analytically. The NCSOIL model was modified to include the effects of the following factors on the C and N dynamics in soil: (i) mineral N uptake by plants and (ii) release of very labile organic C in root exudates. This labile organic C enhanced N immobilization following application, and so decreased the N available for uptake by plants.

	Dry Coal Combustion Products Properties

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Beneficial and environmentally safe recycling of dry flue gas desulfurization (FGD) products require detailed knowledge of their properties. Kost et al. (p. 676–686) report chemical and physical properties of 59 dry FGD samples collected from 13 locations representing four major FGD scrubbing technologies. Dioxin levels, reported as total toxicity equivalents (TTE), for two high-volume FGD product samples used for mine reclamation were 0.48 and 0.53 ng kg^–1 and this was about equal to the background level (0.57 ng kg^–1) measured in a mine spoil. For most elements found in the FGD products, the quality of the coal seems more important than the technologies used to combust the coal and scrub the sulfur from the combustion gases.

	Dietary Changes Affect Phosphorus Speciation in Manures

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Modifying animal diets by reducing mineral P additions and using phytase enzymes to enhance animal utilization of P in feed grains can reduce P in broiler litters and turkey manures. Improved diets help reduce P surpluses on animal feeding operations and decrease the likelihood of nonpoint P pollution of surface and ground waters. Toor et al. (p. 687–697), using X-ray absorption near edge structure (XANES) spectroscopy and chemical fractionation, found that modifying poultry diets reduced manure P concentrations by up to 50%. Dietary changes also affected P speciation. Broiler litters produced from diets using phytase and reduced mineral P contents and turkey manures from normal diets contained 65 to 79% of the P as dicalcium phosphate and no hydroxylapatite. However, turkey manures produced from phytase-based diets had higher Ca to P ratios and equal percentages of dicalcium phosphate (32–46%) and hydroxylapatite (35–39%). Understanding how diets affect P speciation in manures allows us to better predict how animal feeding strategies will affect plant P uptake and P loss to water.

	Diet Affects Gaseous Emissions from Pig Manure

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Manipulation of the diet of pigs may alter composition of the manure and thereby environmental and agricultural qualities of the manure. Laboratory studies of Velthof et al. (p. 698–706) showed that manipulation of pig diets resulted in changes in manure composition, potential emissions of methane (CH₄) and ammonia (NH₃) during storage, and nitrous oxide (N₂O) and carbon dioxide (CO₂) after soil application. Emissions of NH₃ and CH₄ during storage were smaller at a low than at a high dietary protein content. The effect on N₂O emission markedly differed between the two tested soils, which points at interactions with soil properties. From the tested diets, decreasing the protein content has the largest potential to simultaneously decrease NH₃ and CH₄ emissions during manure storage and N₂O emission from soil.

	Nitrate Removal in Riparian Wetlands

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
The reduction of nitrate concentration in water represents an important environmental issue. Thanks to the denitrification processes, riparian wetlands can contribute to such a reduction. However, the efficiency of removal is quite variable since its prediction must be known to be able to use the latter at the landscape scale. Maître et al. (p. 707–716) propose a tool to quantify the denitrifying removal capacity at such a scale and demonstrate that specific local pedological and hydrogeological conditions remain predominant factors in controlling the denitrifying removal capacity.

	Phosphorus Enrichment Triggers Everglades Cascade

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
To determine effects of prolonged P addition on Everglades marshes, P was delivered at low levels (5, 15, and 30 µg L^–1 above ambient) for 5 yr to flow-through channels in pristine marsh. Gaiser et al. (p. 717–723) found that microbial communities in periphyton and floc rapidly sequestered added P, which led to degradation of floating periphyton mats and soil P enrichment. Water total P concentration was not elevated until after plant stem densities increased and consumer biomass was altered in Year 5. Prolonged additions at any above-ambient level trigger a cascade of ecological imbalances that ultimately converge to a similar enriched endpoint.

	Reservoir Sediments Release Phosphorus

TOP Crust Formation Reduces Ammonia... Methyl Bromide Air Concentration... Milk Production Intensity and... Tillage Affects Soil Carbon... Subirrigation Enhances Reduction... Methane Oxidation Discovered in... Unraveling Complexities of... Straining and Attachment of... Desorption of Arsenate from... Selenium Removal by Zerovalent... Prediction of Metal Availability... Copper Availability in Biosolids... Lake Sediments Characterize... Ground Water Denitrification in... Herbicide Leaching in Tropical... New Insights into Chlordane... Hydrophobic Fractions Sorb... Phytase Does Not Increase... One Extraction Coefficient... Resuspension of Bacteria-Laden... Reducing Nitrate Losses to... Phosphorus Bioavailability... Leaching of Glyphosate and... Data Availability Affects... Effluent Treatment Differs... Feedlot Soil Composition... Feedlot Soil Composition Affects... Modeling Carbon and Nitrogen... Dry Coal Combustion Products... Dietary Changes Affect... Diet Affects Gaseous Emissions... Nitrate Removal in Riparian... Phosphorus Enrichment Triggers... Reservoir Sediments Release...

 
Sediment P release in lakes and reservoirs is often enough to enhance and maintain anthropogenic eutrophication, even if external P sources are abated. Haggard et al. (p. 724–728) report that bottom sediments in Lake Eucha, OK, release significant amounts of P into the overlying waters. Sediment P flux was about four times greater under anaerobic conditions compared with aerobic conditions. Sediments released enough P at Lake Eucha to equal 25% of the annual external load from catchment sources. Thus, water quality improvements may not result from external reductions if reservoir sediment P release is not addressed.

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