bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Analysis of Climate Gases by Wide Bore Capillary Gas Chromatography
Authors: Sitaula Bishal K. , Luo Jiafa , Bakken Lars R.
Published: July 2010

A gas chromatographic method that gives sensitive and rapid (3.3 min) measurement of the three greenhouse gases CO2, CH4, N2O is described. A wide bore capillary column operated at optimal conditions gave sufficient separation to allow a switch of the column flow between two detector systems (TCD and FID in series, and ECD) during the chromatogram; thus, all three gases could be analyzed with a single sample injection. Application of a peristaltic pump allowed gas samples to be transfered directly from gas sampling vials, through a drying agent [Mg (Cl04)2] and into the injection loop (0.5 mL) Back flushing of the injection system (pump and drying agent) with He between each injection ensured minimal carry over between samples (<0.6%). Experiences with storage of gas samples in vials with butyl rubber septa are described.
Determination of Alachlor, Atrazine, and Metribuzin in Soil by Resin Extraction
Authors: Basta N.T. , Olness Alan
Published: July 2010

An accurate and precise procedure for simultaneous resin extraction of alachlor (2‐chloro‐2′,6′‐diethyl‐N‐methoxymethylacetanilide), atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine), and metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3(methylthio)‐1,2,4‐triazin‐5(4H)‐one] in soil extracts is described. The procedure consists of three steps: (i) equilibration of resin extractors (RE) with water extracts of soil, (ii) elution of pesticides from RE by using methanol, and (iii) determination and confirmation of pesticide by dual‐column gas chromatography with thermionic specific detection. Recovery of dissolved pesticides by anion‐exchange resin, cation‐exchange resin, and nonpolar resin was studied. Ion‐exchange resins generally adsorbed pesticides well, but showed poor desorption characteristics. The effect of solution pH and salt concentration on pesticide adsorption by a nonpolar resin was studied. Quantitative amounts of pesticide (>95%) were adsorbed from solution by a nonpolar resin over a wide range of solution pH (2.5–10.0) and dissolved salt (0–100 mM NaCl). Pesticide adsorbed by RE ranged from 80 to 90%, and methanol desorbed 80 to 85% of adsorbed pesticides. Overall pesticide recoveries by the RE procedure were very reproducible with an average recovery of 67.7 ± 2.0%. Results obtained by the RE procedure agreed closely with those obtained by solid‐phase extraction (SPE) with octadecyl (C18) bonded porous silica. Extraction time required by the RE procedure is a function of temperature and decreases from 5 d at 22 °C to 2 d at 75 °C. The RE procedure has the same degree of precision as C18‐SPE and is inexpensive.
Physical and Chemical Properties of Potential Topsoil Substitutes in Kentucky Oil Shale Mining Reclamation
Authors: Hower Judith M. , Barnhisel Richard I. , Hopkins T. C.
Published: July 2010

Because the soils that frequently overlie eastern U.S. oil shale outcrops and near‐surface deposits are relatively shallow, acidic, and infertile, use of topsoil substitutes and supplemental materials are anticipated to achieve satisfactory reclamation during surface mining. This study was conducted to determine the effects of weathering on selected overburden strata (the Borden and Bedford Shales) in terms of particle‐size distribution, moisture retention character, reactivity, and macronutrient availability. Shale samples were subjected to 40 freeze/thaw cycles in the laboratory to simulate field conditions. Laboratory analyses of “weathered” shales indicate these materials could be used as effective topsoil substitutes in mine reclamation. Shale weathering produced a material in the fine earth fraction that approached residual soils in ability to retain moisture and have low lime requirements. Suggested P amendment of weathered overburden was 75 to 150 kg P ha−1. Availability of K in weathered overburden exceeded levels in native soils and because these values were generally very high, K amendment of overburden materials would not be needed. To confirm these findings in terms of vegetative cover and growth response, the establishment of field test plots is necessary.
Carbon‐13 Nuclear Magnetic Resonance Spectra of Soil Water‐Soluble Organic Carbon
Authors: Novak J.M. , Bertsch P.M. , Mills G.L.
Published: July 2010

Water‐soluble organic carbon (WSOC) was extracted from the surface horizon (0–15 cm) of a South Carolina floodplain soil (Pickney series‐sandy, silicious, thermic Cumulic Humaquepts) using either 1.2‐µm Whatman glass fiber type C (GF) or polycarbonate (PC) (<0.4 µm) filters. The trend in functional group C distribution for both WSOC fractions was O‐alkyl > aliphatic > aromatic > carboxylic acid > carbonyl structures. Overall, the 13C NMR spectra showed similar functional group C distributions for fractions obtained with both filters.
Herbicide Adsorption and Organic Carbon Contents on Adjacent Low‐Input Versus Conventional Farms
Authors: Mallawatantri A.P. , Mulla D.J.
Published: July 2010

Little quantitative information is available concerning the long‐term impact of alternative framing practices on herbicide adsorption and soil factors that control adsorption. The objective of this study was to evaluate the effects of long‐term conventional vs. long‐term, low‐input farming management practices on herbicide adsorption and soil properties that control adsorption at different landscape positions. Soil samples were collected at depths of 0 to 15 cm along a 350‐m boundary between adjacent long‐term conventional and low‐input farms near Spokane, WA. These samples were characterized for soil organic C (OC) and clay contents, soil pH, and linear adsorption partition coefficients (Kd) using the 14C radiolabeled herbicides metribuzin [4, amino‐6‐11,1‐dimethylethyl)‐3‐(methylthio)‐1,24‐triazine‐5(4,1,1)‐one], diuron, [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea], 2,4‐D [(2,4‐dichlorophenoxy)acetic acid], and triallate [S‐(2,3,3‐trichloroally) diisopropylthiocarbamate]. Carbon contents were significantly higher on the low‐input farm than the conventional farm at all slope positions, with values at the bottom slope position of 19.4 g kg−1 on the low‐input farm and 12.2 g kg−1 on the conventional farm. Carbon contents also decreased significantly at upper slope positions, with values at the top slope of 9.0 g kg−1 on the low‐input farm and 6.0 g kg−1 on the conventional farm. The Kd values for the four herbicides studied were significantly larger on the low‐input farm than the conventional farm at all slope positions. Significant decreases in adsorption occurred on both farms at top‐slope positions relative to bottom‐slope positions. From 80 to 95% of the increase in Kd values could be explained by increases in OC contents, but the best‐fitting regression line had a large negative intercept for metribuzin, 2,4‐D, and diuron. We conclude from this that although the regression model may be used to estimate Kd values from measured OC contents at moderate to high values of OC, the model has no physicochemical significance and the slope of the model does not equate to a value for Koc.
Water Quality Characteristics Associated with Southern Plains Grasslands
Authors: Smith S. J. , Sharpley A. N. , Berg W. A. , Naney J. W. , Coleman G. A.
Published: July 2010

Water quality information regarding grasslands in the Southern Plains of Oklahoma and Texas is sparse. The objective of this study was to determine the extent to which the area's surface and groundwater quality is influenced by native and introduced grass management practices. Concentrations and amounts of sediment, N, and P in surface runoff water were determined for 14, 1‐ to 6‐ha watersheds in the Reddish Prairie and Rolling Red Plain land resource areas for periods of 3 to 13 yr. In general, surface water quality was influenced slightly during the study periods by dominant grass species, area grazing practices, or recommended fertilizer rates, but sediment losses were curtailed greatly by gully amelioration. Mean annual discharge ranged from 30 to 71 000 kg ha−1 for sediment, 0.1 to 11 kg ha−1 for total N, and 0.02 to 4 kg ha−1 for total P. Highest losses were from watersheds with established, active gullies. Annual soluble nutrient losses in surface runoff tended to be small, often <1 kg ha−1 N or P. Successful prediction of soluble P, particulate P, and particulate N in surface runoff was achieved using appropriate kinetic desorption and enrichment ratio procedures. Soluble N in surface runoff posed few water quality problems, but soluble and total P concentrations often exceeded proposed 0.01 and 0.02 mg L−1 respective critical limits for eutrophication, even on the more pristine watersheds. In the case of groundwaters, occasional, elevated NO3‐N (i.e., 18 mg L−1 maximum) concentrations were observed beneath certain N fertilized, introduced and native grasses on shallow water table (3–20 m depth), medium‐textured soils.
Ion Leaching in Forest Ecosystems along a Great Lakes Air Pollution Gradient
Authors: MacDonald N. W. , Burton A. J. , Liechty H. O. , Witter J. A. , Pregitzer K. S. , Mroz G. D. , Richter D. D.
Published: July 2010

A gradient of H+, SO2−4, and NO−3 deposition across the Great Lakes region raised concerns over impacts on soil solution chemistry and ion leaching in regional forest ecosystems. Ten study sites representing northern hardwood and oak ecosystems were established across the gradient of increasing deposition from Minnesota to Ohio. Lysimeters were installed at lower E and lower B horizon boundaries at each site and sampled over a 2‐yr period. In soil solutions collected at lower E horizon boundaries, H+ and SO2−4 wet deposition were correlated with solution concentrations of SO2−4 r = 0.82** and 0.92**) and Mg2+ (r = 0.75** and 0.85**), and with the SO2−4/inorganic anion ratio (r = 0.71** and 0.70**). In soil solutions collected at lower B horizon boundaries, SO2−4 deposition was correlated with solution SO2−4 concentrations (r = 0.92**). Greater ionic outputs from B horizons than atmospheric inputs indicated that net losses of Ca2+ and Mg2+ were occurring from all sites. Sulfate outputs above background levels contributed 33 to 2367 molc SO2−4 ha−1 yr−1 from north to south along the gradient, equal to 3.7 to 71.7% of annual cation outputs. Excess H+ deposition accounted for 8 to 34% of annual cation outputs from north to south, and as much as 72% at one site with coarse‐textured soils. Elevated cation losses related to H+ and SO2−4 deposition indicate that cation depletion remains a plausible consequence of pollutant deposition to forest ecosystems with poorly buffered soils.
Photosynthesis and Nitrogen Fixation in Soybean Exposed to Nitrogen Dioxide and Carbon Dioxide
Authors: Gupta Gian , Li Yuncong , Sandhu Ravinder
Published: July 2010

‘Williams‐82’ Soybean [Glycine max (L.) Merr.] plants, at the flowering stage, were exposed to NO2 (0.1 µmol mol−1, 7 h d−1) and CO2 (450 µmol mol−1, 12 h d−1) for 5 d singly and in combination in open‐top field chambers. The rate of photosynthesis (PN), specific root nodule nitrogenase activity (SNA), and leaf N were measured after exposure using the LICOR 6200 Portable Photosynthesis system, the acetylene‐ethylene reduction method, and the Kjeldahl digestion, respectively. The plants exposed to NO2 (with 350 µmol mol−1 CO2) showed significantly higher PN, SNA, and N compared with the control plants. The SNA and N were reduced, with no change in PN on exposing the plants to CO2 (in the absence of NO2). When the plants were exposed to a combination of these two gases, SNA was increased but the PN and N did not change. The stimulatory effect of NO2 was reduced by the inhibitory impact of CO2 on the parameters studied.
Physical and Chemical Properties of Coal Refuse from Southwest Virginia
Authors: Stewart B.R. , Daniels W.L.
Published: July 2010

Coal refuse is difficult to reclaim due to high potential acidity, very coarse texture, low water retention, and fertility. This study was undertaken to determine the physical and chemical properties and the reclamation potential of samples from 27 coal refuse piles of varying age. Selected physical and chemical properties varied widely across this sample set. The >2 mm fragment content was 60%, and the average texture of the <2 mm fraction was a sandy loam with 15% clay. The mean water retention difference, (−1.50 to −0.030 MPa), on a whole sample basis was 0.08 kg water/kg refuse. The pH varied from 3.0 to 8.3 due to differences in the amounts and reactivity of pyritic minerals in refuse. Older piles generally had lower pH values than more recent piles. The saturated paste electrical conductivity (EC) was higher in the younger refuse due to active pyrite oxidation. A 5:1 water to soil (w/w) extract shows promise as an effective screen for samples with potentially high EC values. Coal refuse was generally low in available P and B. Total elemental analysis revealed that Si, Al, Fe, and K were the most abundant elements. The physical factor most limiting to plant growth is likely to be low water holding capacity, while low pH was found to be the chemical factor most limiting to plant survival. These findings indicate that some refuse piles may be suitable for direct seeding, but many will require heavy lime and/or organic treatments for successful reclamation.
Nitrate Dynamics in Riparian Forests: Groundwater Studies
Authors: Simmons Robert C. , Gold Arthur J. , Groffman Peter M.
Published: July 2010

This study was conducted to assess the removal of groundwater nitrate (NO−3) in different soil drainage classes within three riparian forests located in Rhode Island. A solution of NO−3 and a conservative tracer [either bromide (Br−) or chloride (Cl−)] was applied in the growing and the dormant seasons to trenches upgradient of wetland locations with hydric soils (poorly and very poorly drained soils) and transition zone locations with somewhat poorly and moderately well‐drained soils located immediately upslope of the wetlands. To assess removal, the change in groundwater concentrations of NO−3 relative to the concentration of the conservative tracer was observed in monitoring wells located in each soil drainage class from June 1989 through April 1990. Removal of groundwater NO−3 was consistently high in the wetland locations, generally in excess of 80% in both growing and dormant seasons. In the transition zones, attenuation was less than 36% during the growing season, and ranged from 50 to 78% in the dormant season. Attenuation in the transition zones was positively correlated with water table elevations. Transition zone attenuation was high in the dormant season relative to the growing season likely because high water tables during the dormant season caused the contaminant plume to be exposed to soil with higher organic matter. The results suggest that both wetlands and transition zones between wetlands and uplands can be important sinks for groundwater NO−3.
Low‐Contaminant Jarosite Waste as a Fertilizer Amendment
Authors: Kanabo I.A.K. , Gilkes R.J.
Published: July 2010

Low‐contaminant jarosite (LCJ), with 1.1% N, 4.7% Zn, and 11% S, is a potential fertilizer source, but its use may create toxic conditions. This material was compared with standard fertilizers in glasshouse experiments and the effect of the application of jarosite to soils on the concentrations of heavy metals in plants was also investigated. On the basis of wheat (Triticum aestivum L.) yields, LCJ is about 5% as effective in supply N as NH4NO3. On the basis of Zn concentration in plant tops, LCJ was about 80% as effective as ZnSO4 in supplying Zn to wheat. Based on S concentrations in clover (Trifolium spp.) tops, LCJ was 30 and 60% as effective as CaSO4 in supplying S on light and heavy‐textured soils, respectively. Application of LCJ to soils resulted in elevated concentrations of Cd, Cu, and Zn in plant tissue. The increase in Cd concentration was such that it is unlikely that LCJ could be recommended as a fertilizer for plants grown for human or animal consumption.
Odor Control in Liquid Hog Manure by Added Amendments and Aeration
Authors: Al‐Kanani T. , Akochi E. , MacKenzie A. F. , Alli I. , Barrington S.
Published: July 2010

A reduction in the emission of malodorous gases from liquid hog manure (LHM) would represent an advantage for LHM use in agricultural systems. Procedures for the reduction of disagreeable odors during storage of LHM (Sus scrofa domesticus) were studied in the laboratory. Sphagnum peat moss (Sphagnum moss species), 1.5 M H2SO4, 1.7 M H3PO4, monocalcium phosphate monohydrate (MCPM), elemental S, CaCO3, and CaO were used to reduce odors. Amended and nonamended LHM was incubated with and without aeration for periods ranging from 2 to 720 h at 23 ± 0.4°C. Odor measurements of emitted air were carried out using a sensory panel. Gas chromatography‐mass spectrometry (GC‐MS) was used to identify specific odor‐producing compounds. The GC‐MS analysis revealed that added Sphagnum moss (SM) prevented the release of 1,2‐ethanediamine, N‐methyl methanamine, 3‐methyl 2‐butanamine, methyl hydrazine, ethanethioic acid, and methanethiol from LHM. Aeration as a treatment, in general, resulted in a greater reduction of odor presence and offensiveness than nonaeration. In nonaerated LHM treatments, SM at levels of 4 or 8% (w/w) or a combined treatment of 2% CaCO3 plus 1% SM resulted in a significant reduction in odor presence and offensiveness. Little odor reduction was observed with H2SO4, H3PO4, MCPM, and CaO, and no odor reduction was found with elemental S.
Effect of Seeding on Thermophilic Composting of Tofu Refuse
Authors: Nakasaki Kiyohiko , Watanabe Atsushi , Kitano Makoto , Kubota Hiroshi
Published: July 2010

Disposal of tofu processing residue is recently a serious problem in Japan. In this research, accelerated methods of composting tofu refuse were explored. The effect of seeding on the composting reaction rate of tofu refuse was examined by measuring changes in CO2 evolution, temperature, conversion of carbon, and microbial succession. The timing of CO2 evolution and microbial succession differed substantially when sterilized tofu refuse was seeded with two different inoculum sources. This difference was restricted only to early composting stages and the total amounts of CO2 evolved from both composts were similar in the later stage of refuse degradation. The analysis of microbial succession indicated that the types of microorganisms primarily responsible for composting of the refuse were the same in the later stages of both experiments. In contrast to the composting of sterilized tofu refuse, no measurable effect of seeding was observed when air‐dried tofu refuse was composted. Large numbers of microorganisms responsible for composting inhabited the air‐dried tofu refuse. Although the succession of thermophiles and patterns of CO2 evolution were different in composting sterilized and dried tofu refuses, no clear difference was observed in the final conversion of C of the raw refuse in all treatments.
Phosphorus Removal Processes in a Wetland after a Decade of Receiving a Sewage Effluent
Authors: Cooke James G.
Published: July 2010

A study was made of the processes leading to phosphorus (P) removal in a wetland that received a high load of sewage‐P for over a decade. The amounts of P accounted for by sediment deposition, sorption to detrital material, and uptake by above ground biomass were compared with the mass of P entering and leaving the wetland system. Phosphorus deposition was shown to be the most important sink for P with rates of up to 30 g P m−2 d−1 being recorded. The pronounced spatial distribution of deposition as well as laboratory experiments indicated that P deposition occurred predominantly by reaction between sewage‐wetland waters (high in P, alkaline pH) and natural wetland waters (high in Fe and Al, acid pH) at or immediately below confluences joining their flow streams. Studies on P mass transport showed that the P removal rate (28–70%) was considerably greater than published values suggest could be predicted for this highly loaded (≃34 g P m−2 yr−1) system. It is suggested that the wetland configuration, whereby the flow from a relatively small area of sewage‐impacted wetland, is joined by waters from much larger unimpacted wetlands, is the reason for the relatively large P removal in this system. The relative magnitudes of P sinks in this study are different enough from other studies to suggest that the present level of P removal in this wetland is sustainable.
Prediction of Bioavailable Phosphorus Loss in Agricultural Runoff
Authors: Sharpley Andrew N. , Smith S.J.
Published: July 2010

The loss of bioavailable P (BAP) in both soluble (SP) and participate (BPP, bioavailable particulate P) forms in agricultural runoff, can accelerate the eutrophication of surface waters. Bioavailable P represents P that is potentially available for algal uptake. Although prediction of BAP loss would provide a more reliable assessment of the impact of agricultural management on surface water eutrophication than just SP or total P (TP), currently no predictive equations are available. Bioavailable P transport in soluble and particulate forms in runoff from 20 agricultural watersheds in the Southern Plains over a 5‐yr period, was predicted using kinetic and enrichment ratio approaches, respectively. Measured and predicted SP and BPP concentrations of individual runoff events were similar for all watersheds and management practices over a range of 7 to 3522 and 3 to 4059 µg L−1, respectively. Calculated as the sum of SP and BPP, BAP loss in runoff was predicted accurately, with only a 12% error in measured mean annual loss (662 g ha−1 yr−1). Although BAP loss below 100 g ha−1 yr−1 was underestimated, above this value measured and predicted values closely followed a 1:1 relationship. Inclusion of these equations in comprehensive water quality models will improve the prediction of agricultural management on the biological response of receiving water bodies.
Effects of Two Earthworm Species on Movement of Septic Tank Effluent through Soil Columns
Authors: Jones L.A. , Rutledge E.M. , Scott H.D. , Wolf D.C. , Teppen B.J.
Published: July 2010

Development of a clogging layer at the soil‐gravel interface often causes failure of septic tank filter fields to transmit effluent. A column study was undertaken to determine whether earthworms (Lumbricus terrestris L. and L. rubellus Hoff.), through their burrowing activity, could reverse the negative effects of clogging layer formation. Twelve soil columns, 0.20 m in diameter by 0.38 m long, were constructed using gravel and subsoil of a Peridge soil (fine‐silty, mixed, mesic Typic Paleudalf). The columns were dosed for at least 263 d with 2.3 cm d−1 of septic tank effluent until clogging layers had formed and stabilized. Steady‐state effluent flux densities through the columns ranged from 1.9 to 2.9 µm s−1, so that about 2 h were required for drainage of the daily effluent dose. The columns were divided into four groups based on their hydraulic performances, and the columns in each group were treated with 25 L. rubellus, 25 L. terrestris, or no worms. Within 80 d the flux densities through the columns containing earthworms increased to between 4.8 and 12.4 µm s−1, or 40 to 135% of the initial maxima before clogging layer formation. Effluent flux densities through control columns remained constant. Earthworm survival rates were not significantly different (P > 0.05) between species, with 81% of L. rubellus and 95% of l. terrestris surviving. In two columns, L. rubellus cocoons hatched. During the 96‐d study, the earthworms lost less than 4% of their initial weights on a dry weight basis. The L. rubellus and L. terrestris produced channels with median diameters of 2.3 and 8.4 mm, respectively.
Managing Soil Moisture on Waste Burial Sites in Arid Regions
Authors: Anderson J. E. , Nowak R. S. , Ratzlaff T. D. , Markham O. D.
Published: July 2010

In semiarid regions, where potential evapotranspiration greatly exceeds precipitation, it is theoretically possible to preclude water form reaching interred wastes by (i) providing a sufficient cap of soil to store precipitation that falls while plants are dormant and (ii) establishing sufficient plant cover to deplete soil moisture during the growing season, thereby emptying the water storage reservoir of the soil. Here we discuss the theory and rationale for such an approach and then present the results of a field study to test its efficacy at the Idaho National Engineering Laboratory (INEL). We examined the capacity of four species of perennial plants to deplete soil moisture on simulated waste trenches and determined the effective water storage capacity of the soil. Those data enabled us to estimate the minimum depth of fill soil required to prevent deep drainage. Any of the species studied can use all of the plant‐available soil water, even during a very wet growing season. The water storage capacity of the soil studied is 17% by volume, so a trench cap of 1.6 m of soil should be adequate to store precipitation received at the INEL while plants are dormant. We recommend a fill soil depth of 2 m to provide a margin of safety in case water accumulates in local areas as a result of heavy snow accumulation, subsidence, or runoff. Fill soil requirements and choice of plant species will vary, but the concepts and general approach are applicable to other shallow land burial sites in arid or semiarid regions.
Atmosphere × Canopy Interactions of Nitric Acid Vapor in Loblolly Pine Grown in Open‐Top Chambers
Authors: Taylor G. E. , Owens J. G. , Grizzard T. , Selvidge W. J.
Published: July 2010

Many studies that address the impact of tropospheric O3 on agricultural and forested ecosystems utilize the open‐top chamber. During the production of O3 using electrical discharge generators fed with dry air, there is an inadvertent addition of HNO3 vapor, a highly reactive trace gas. While several studies have proposed that HNO3 vapor introduces artifacts, none has measured concentrations of the odd‐N2 trace gas in the chamber or investigated the fate of the N in the context of whole‐plant physiology and growth. These questions were investigated using open‐top chambers containing seedlings of loblolly pine (Pinus taeda L.) during the 1988 growing season in Oak Ridge, TN. The O3 treatments consisted of charcoal‐filtered or subambient (0.96 µmol m−3, 24‐h mean), ambient (1.62 µmol m−3, 24‐h mean), and elevated (2.36 µmol m−3, 24‐h mean) concentrations, the last being accomplished by proportional O3 addition over the diurnal period. Measurements of the HNO3 vapor concentration during dry periods only (no rainfall or ground‐level fog) averaged 28.6 nmol m−3 (subambient), 55.4 nmol m−3 (ambient air), and 240.0 nmol m−3 (elevated O3), an 8.4‐fold range. For every 100 mol of O3 added to the chamber, 28 mol of HNO3 vapor were inadvertently added; this ratio is several times higher than that previously reported. This result, taken with published estimates of leaf conductance to HNO3 vapor, indicates a maximum N deposition in the form of HNO3 vapor ranging from 19.5 pmol N cm−2 leaf area h−1 (subambient O3) to 171.9 pmol N cm−2 h−1 (elevated O3). Given the nutrient content of the seedlings and knowledge of the fate of HNO3 vapor on the leaf surface and leaf interior, the degree to which N deposition via HNO3 vapor met the N requirements of the loblolly pine seedlings was estimated. Seedlings in the elevated O3 treatment had an upper‐limit estimate of 3.5% for the needles and 1.8% for the whole plant of N derived from HNO3 vapor. The concentration of HNO3 vapor in the chambers, site of HNO3 vapor deposition, N requirements of the loblolly pine seedlings, and estimated threshold for phytotoxic effects of HNO3 vapor indicate that the inadvertent production of this odd‐N2 trace gas is important in understanding the atmospheric chemistry within the chambers, but that the level of N loading in this study is unlikely to affect physiology or growth. However, we recommend that studies that employ higher O3‐exposure scenarios recognize the potential for inadvertent N deposition, particularly in trees grown in N‐deficient substrate.
Atmospheric Transport of Organophosphate Pesticides from California's Central Valley to the Sierra Nevada Mountains
Authors: Zabik John M. , Seiber James N.
Published: July 2010

Atmospheric transport of organophosphate pesticides from California's Central Valley to the Sierra Nevada mountains was assessed by collecting air‐ and wet‐deposition samples during December, January, February, and March, 1990 to 1991. Large‐scale spraying of these pesticides occurs during December and January to control insect infestations in valley orchards. Sampling sites were placed at 114‐ (base of the foothills), 533‐, and 1920‐m elevations. Samples acquired at these sites contained chlorpyrifos [phosphorothioic acid; 0,0‐diethyl 0‐(3,5,6‐trichloro‐2‐pyridinyl) ester], parathion [phosphorothioic acid, 0‐0‐diethylo‐(4‐nitrophenyl) ester], diazinon {phosphorothioic acid, 0,0‐diethyl 0‐[6‐methyl‐2‐(1‐methylethyl)‐4‐pyrimidinyl] ester} diazinonoxon {phosphoric acid, 0,0‐diethyl 0‐[6‐methyl‐2‐(1‐methylethyl)‐4‐pyrimidinyl] ester}, and paraoxon [phosphoric acid, 0,0‐diethyl 0‐(4‐nitrophenyl) ester] in both air and wet deposition samples. Air concentrations of chloropyrifos, diazinon and parathion ranged from 13 to 13 000 pg/m3 at the base of the foothills. At 533‐m air concentrations were below the limit of quantification (1.4 pg/m3) to 83 pg/m3 and at 1920 m concentrations were below the limit of quantification. Concentrations in wet deposition varied with distance and elevation from the Central Valley. Rainwater concentrations at the base of the foot hills ranged from 16 to 7600 pg/mL. At 533‐m rain and snow water concentrations ranged from below the limit of quantification (1.3 pg/mL) to 140 pg/mL and at 1920 m concentrations ranged from below the limit of quantification to 48 pg/mL. These findings indicate that atmospheric transport of pesticides applied in the valley to the Sierra Nevada mountains is occurring, but the levels decrease as distance and elevation increase from the valley floor.
Pore Water Chemistry of Phosphogypsum‐Treated Soil
Authors: Luther S.M. , Dudas M.J.
Published: July 2010

Phosphogypsum (PG) is a gypsum‐based by‐product of phosphate fertilizer production and is commonly stored at plant sites. As stockpiles of the material accumulate worldwide, elemental leaching from repositories is of potential environmental concern. In this study, samples of glacial till, PG, and mixtures of the two were incubated with deionized water. Solution extracts were analyzed for chemical constituents. Speciated activities of Al, Cr, and Cu, obtained using GEOCHEM, were related to theoretical levels estimated from solubility constants of potential solubility‐controlling solids. Maximum pore water levels of As, B, Ca, Fe, K, Mn, Na, NH+4‐N, NO−3‐N, Ni, P, Se, Si, Sr, V, and Zn were less when PG was mixed with soil and allowed to equilibrate. However, only the concentrations of Cd, Fe, Ni, P, Sr, V, and Zn were less by close to an order of magnitude or more. The increase in pH with soil addition influenced these substantial changes in elemental concentrations. The activities of Cr and Cu species decreased with soil addition, but the suspensions were considerably undersaturated relative to potential solubility‐controlling solids. GEOCHEM indicated Al activities were in equilibrium with alunite, basaluminite, gibbsite, and jurbanite. As PG was neutralized through the addition of calcareous glacial till, solution levels of Al, Cd, Cr, Cu, Fe, Ni, P, Sr, V, and Zn all decreased substantially.
Nitrogen Transfers in a Rapidly Eroding Agroecosystem:Loess Plateau, China
Authors: Hamilton Hugh , Luk Shiu‐hung
Published: July 2010

A study was initiated to assess the influence of high erosion rates and sediment hyperconcentrations on patterns of N loss in China's Loess Plateau region. The study was conducted in a 12.6‐ha subbasin where the upper slopes are terraced and cultivated, and the lower slopes are grazed by sheep. Seventeen rainstorms were monitored over 2 yr at a flume located in the ephemeral channel at the basin outlet. Runoff events were characterized by large sediment concentrations (mean 508 kg m−3), dilution of dissolved NO3 + NO2‐N concentrations during periods of peak flow, and high sediment‐associated Kjeldahl N concentrations near the end of events when larger‐sized particles are deposited. Hyperconcentrated flow ensured that most entrained sediment and N was exported. Annual soil losses equaled 203.4 Mg ha−1 and 176.9 Mg ha−1 in 1987 and 1988. Total N losses equaled 76.4 kg ha−1 and 44.1 kg ha−1. In each year, one or two large events contributed the bulk of soil and N losses. About 98% of the N losses were sediment associated, with low‐intensity events having the highest soluble proportion. A simple N mass balance shows that erosion losses of N are serious, and that most of the N removed from both cultivated and grazed areas is exported. Results indicate that N cycling in this semiarid area is strongly influenced not only by the amount of rainfall, but also by the timing and intensity of the storms.
Effect of Starch Encapsulation and Temperature on Volatilization of Atrazine and Alachlor
Authors: Wienhold Brian J. , Sadeghi Ali M. , Gish Timothy J.
Published: July 2010

Volatilization of agricultural chemicals is one process whereby chemicals may enter into parts of the environment where they were not intended. Starch encapsulation of pesticides has been proposed as a way of modifying pesticide behavior in the soil environment. This study was conducted to assess how starch encapsulation and temperature affect volatilization of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] and alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide]. Volatilization was measured using agroecosystem chambers as model systems. Herbicides were applied at rates of 1.7 kg ha−1 for atrazine and 2.8 kg ha−1 for alachlor, as either a commercial formulation or a starch encapsulated formulation, to the surface of moist soils maintained at temperatures of 15, 25 and 35°C. Air was drawn through the chambers (2.5 m3 min−1) and herbicide in the vapor phase was trapped in polyurethane foam plugs. Volatilization of both herbicides increased as temperature increased. Volatilization of atrazine was less when applied as starch‐encapsulated formulation than the commercial formulation. After 35 d cumulative volatilization of atrazine ranged from <1% of that applied as starch‐encapsulated formulation at 15°C, to 14% of that applied as the commercial formulation at 35°C. Cumulative volatilization of alachlor was greater when applied as starch‐encapsulated formulation than as the commercial formulation. After 35 d, cumulative volatilization of alachlor ranged from >2% of that applied as either formulation at 15°C to 32% of that applied as starch encapsulated formulation at 35°C. Differences in volatilization behavior between these herbicides are likely to be due to differences in chemical properties of these herbicides.
Characteristics of Earthworm Burrow Lining Affecting Atrazine Sorption
Authors: Stehouwer R. C. , Dick W. A. , Traina S. J.
Published: July 2010

Vertically oriented earthworm burrows exist in many agricultural sites, especially in no‐tillage soils where the burrows are left intact from year to year. Earthworm burrows can function as preferential flow conduits and may enhance downward transport of surface‐applied pesticides. Earthworm activity induces changes in the soil characteristics of the burrow walls that may affect pesticide sorption and transport. Little information is available describing the properties of the lining material. Earthworm (Lumbricus terrestris L.) burrow lining and bulk soil at seven depth intervals from 0 to 50 cm were characterized with respect to pH, clay content, total organic C (TOC), water‐soluble organic C (WSOC), and alkaline phosphatase (AP) activity. Atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] sorption‐desorption isotherms were conducted on the same materials. Burrow linings were found to have a narrower range of pH and clay content than the bulk soil within the 0‐ to 50‐cm depth. Levels of TOC and WSOC in burrow linings were two to three times higher than in the bulk soil at the profile surface. This difference increased to eight times at the 35‐cm depth although concentrations were lower than at the profile surface. Activity of AP in burrow lining from 0 to 20 cm was three times greater than in the surface bulk soil, and at depths of 20 to 40 cm AP activity in burrow lining was similar to that of the surface bulk soil. Freundlich Kf values for atrazine sorption and desorption were higher for burrow lining than bulk soil at almost every depth. The largest differences (1.5‐ to 3‐fold) occurred in the 15‐ to 30‐cm depth range. Multivariate regression analysis of atrazine sorption‐desorption indicated that of the parameters measured, TOC could account for most of the variability in atrazine sorption‐desorption.
Des Moines River Nitrate in Relation to Watershed Agricultural Practices: 1945 Versus 1980s
Authors: Keeney D. R. , DeLuca T. H.
Published: July 2010

Concern for nitrate (NO3‐N) contamination of surface waters in Iowa has brought much speculation with regard to the source of NO3‐N. It is frequently assumed that the large percentage increase in fertilizer N use over the last 50 yr is the primary cause of high concentrations of NO3‐N in surface waters of central Iowa. We performed an analysis of data relating flow and NO3‐N concentration for the Des Moines River to identify the effect of agricultural practices on NO3‐N in the river. Annual and weekly stream flow values for the 1980‐1990 period at a site just below the city of Des Moines were positively related to the NO3‐N concentration in the river water for the 11‐yr period (r2 = 0.60, P < 0.01). From 1980 to 1991 the average annual NO3‐N concentration ranged from 2.0 mg L−1 in the low flow year of 1989 to 9.1 mg L−1 in 1982. Over the 11 yr, the river averaged 5.6 mg L−1 NO3‐N and had an average flow of 733 580 m3 h−1. In 1945, the average flow was 723 710 m3 h−1 and NO3‐N concentrations were 5.0 mg L−1. These values were similar to the 11‐yr average data obtained 35 to 45 yr later. We infer from the data that the intensive agricultural activities in 1945 and 1980 to 1990 are the major source of the NO3‐N to the river rather than solely N fertilizer. Changes in land management, cropping patterns, and land use are therefore required to markedly lower the NO3‐N levels of surface water in this basin.
Aerobic Degradation of Calcium Magnesium Acetate in Roadside Soils: Field Simulations from Soil Microcosms
Authors: Ostendorf D. W. , Pollock S. J. , De Cheke M. E. , Palaia T. A.
Published: July 2010

Aseptic soil samples from the 0.2‐m loamy sand cover and underlying sand fill of a state highway shoulder in southeastern Massachusetts were placed in sterile serum bottles at 5 °C, forming a series of aerobic soil microcosms. The sand fill belonged to the Carver coarse sand series (Mesic, uncoated Typic Quartzisamment), while the loamy sand was of unknown origin. The samples were dosed with reagent grade glacial acetic acid and commercially available calcium magnesium acetate [(CMA; Ca0.3Mg0.7(C2H3O2)2] solutions without acclimation, then sampled at various time intervals and analyzed by gas chromatography in a laboratory determination of the microbial degradation kinetics. The aerobic reaction rate varied strongly and directly with depth but was uniform with distance along and normal to the highway. A simple steady state transport simulation model balancing infiltration and degradation was derived and run with the observed microcosm kinetics for a range of assumed snowmelt rates. The resulting simulated profiles suggested that the loamy sand cover bad the potential to reduce O2 demand by CMA on groundwater for slow (10−7 m/s−1 snowmelt rates at 5 °C under aerobic conditions. Shoulders with more rapid infiltration, colder temperatures, and thinner loamy sand covers would pass more CMA to the underlying aquifer.
Small‐Scale Spatial Patterns of Bulk Atmospheric Deposition
Authors: Berndtsson Ronny
Published: July 2010

In total 14 bulk atmospheric deposition collectors were distributed over the city of Lund (about 20 km2) in the south of Sweden during September 1980 to June 1981. The observations were made to investigate small‐scale spatial variability of atmospheric deposition. Monthly bulk deposition samples were analyzed for Cl, Ptot, Zn, Cu, and Pb. Correlation analysis shows that the spatial scale for the variation pattern is of the order > 10 km for precipitation and Cl, and about 2 km for Ptot and metals. This indicates that remote sources with a general large‐scale deposition pattern are dominating for Cl deposition and that local sources dominate for Ptot, Zn, Cu, and Pb. The total atmospheric deposition in the investigated urban area is assumed to be superposed by three components: (i) regional background, (ii) urban background, and (iii) urban point deposition. The urban background deposition may be considerable in relation to regional background deposition. The urban point sources may represent deposition rates of twice or more of the total deposition.
Effects of Poultry Litter Application Rate and Rainfall Intensity on Quality of Runoff from Fescuegrass Plots
Authors: Edwards D.R. , Daniel T.C.
Published: July 2010

A 4 × 2 factorial experiment with three replications was conducted to determine how quality of runoff from grassed areas treated with poultry (Gallus gallus domesticus) litter is impacted by litter application rate and rainfall intensity for storms occurring 1 d after application. Poultry litter was applied at 0, 218, 435, and 870 kg N ha−1 to plots established with fescuegrass (Festuca arundinacea Schreb.) on a Captina silt loam soil (fine‐silty, mixed, mesic Typic Fragiudult). Simulated rainfall was applied 24 h after litter application at 5 and 10 cm h−1 until runoff had occurred for a duration of 0.5 h. Flow‐weighed composite samples were collected and analyzed for total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3‐N), nitrate nitrogen (NO3‐N), total phosphorus (TP), dissolved reactive phosphorus (DP), chemical oxygen demand (COD), total suspended solids, and electrical conductivity. Increasing the litter application rate significantly increased runoff concentrations of all litter constituents investigated. Concentrations of TKN, TP, DP, and COD significantly decreased with increasing rainfall intensity because of more runoff and the associated dilution. Masses of litter constituents transported off the plots via runoff significantly increased with both litter application rate and rainfall intensity. For a given rainfall intensity, the proportions of applied litter constituents lost in runoff were generally indendent of application rate with the exception of total N at the high rainfall intensity.
Evaluation of Solid‐State Fermentation Techniques to Dispose of Atrazine and Carbofuran
Authors: Berry Duane F. , Tomkinson Richard A. , Hetzel Glen H. , Mullins Donald E. , Young Roderick W.
Published: July 2010

Methods to dispose of unused concentrated and dilute formulated pesticide suspensions or solutions such as rinsate are urgently needed by small‐scale farm operators and applicators. The suitability of solid‐state fermentation (SSF) techniques to dispose of atrazine (2‐chloro‐4‐[ethylamino]‐6‐[isopropylamino]‐1,3,5‐triazine, purity 99.0%) and carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate, purity 99.0%) formulations was evaluated. Pesticides were added to bioreactors containing either sphagnum peat moss or steam‐exploded wood (SEW) and monitored periodically for disappearance. Soil column leaching studies and the USEPA standard toxicity characteristic leaching procedure were used to assess the potential environmental hazard of land application of spent lignocellulosic matrix materials. Pesticide bioavailability was determined with plant or animal bioassay indicators. In peat‐filled bioreactors containing atrazine at loading rates of 1.4, 2.0, and 7.2 g kg−1 (dry wt. basis), solvent extractable atrazine decreased to less than 0.2% of starting levels within 480 d. For the SEW‐filled bioreactors containing atrazine at a loading rate of 2.0 g kg−1, solvent extractability decreased to 20% of starting levels within 320 d. Extractable carbofuran in peat‐filled (initial loading rates 0.7, 1.8, and 5.0 g kg−1) and SEW‐filled (initial loading rate 5.0 g kg−1) bioreactors decreased to less than 0.05% of starting levels within 480 d. Both leachability and bioavailability of pesticides were dramatically reduced during the process of SSF. The amount of leachable pesticide remaining in peat sorbent following bioreactor start‐up was dependent on the initial pesticide loading rate and the length of bioreactor operation time. The use of SSF techniques to dispose of pesticide waste may prove a viable alternative to other disposal methods that are either too expensive or technically sophisticated.
Lake Water Quality Modeling for Projected Future Climate Scenarios
Authors: Stefan H. G. , Hondzo M. , Fang X.
Published: July 2010

A deterministic, one‐dimensional numerical simulation model for water temperature and dissolved oxygen (DO) in lakes of different size, depth, and trophic status has been formulated, validated, and applied to lakes in the north central USA. The standard error of predictions is on the order of 1 °C for temperature and 1.5 mg L−1 for DO. The model is driven by weather measurements at off‐lake weather stations. Simulations can be made for the open water season at daily timesteps and for as many years as weather data are available without any parameter adjustments. The model has been used to simulate the effect of climate change due to a doubling of atmospheric CO2 on water temperatures and DO in 27 lake classes in Minnesota. The lakes have been differentiated by surface area, maximum depth, and trophic status. Maximum water temperature near the surface is projected to increase by no more than 2 °C in midsummer, and DO will drop by less than 2 mg L−1 in the surface waters but will remain above 7 mg L−1. In contrast, hypolimnetic water temperature in mid‐summer may rise by as much as 4 °C or may become colder by as much as 4 °C. Hypolimnetic DO will be lower by as much as 8 mg L−1 in midsummer and DO depletion is projected to occur for a longer period of time in midsummer in lakes with seasonal summer stratification. Changes will be largest in spring and fall because the summer stratification season will lengthen by 20 to 90 d for different lake types.
Simulating Funnel‐Type Preferential Flow and Overall Flow Property Induced by Multiple Soil Layers
Authors: Ju S.‐H. , Kung K.‐J. S.
Published: July 2010

Funnel‐type preferential flow was observed in Plainfield sand (sandy, mixed, mesic Typic Udipsamment) of central Wisconsin. The objective of this paper was (i) to develop a numerical model based on the Richards equation and finite element scheme to simulate this preferential flow in a soil profile with inclined layers, and (ii) to determine flow properties in a soil with funnel‐type preferential paths. The model was first validated by testing against two‐dimensional (2‐D) laboratory results and then used to simulate water flow patterns in hypothetical 2D soil profiles made of medium sand with multiple randomly distributed, inclined coarse layers. The following results were found from the numerical experiments; (i) funnel‐type preferential flow paths could be deterministically simulated if soil layering structure, hydraulic conductivity of the overall profile, and threshold potential of the embedded coarse layers were known; (ii) distribution of the vertical component of flux was determined by the funneling effect along the upper coarse sand lenses. The lenses located in deeper parts of the profile would only influence macrotortuosity of the preferential flow paths; (iii) funnel‐type preferential flow paths were determined not only by soil structures and textures but also by water application rate; and (iv) although funnel‐type preferential paths were very complex, the vertical component of flux could be very simply described by two stochastic parameters—the mean and standard deviation of a log‐normal distribution after the flow paths became stationary.