bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic Carbon Fractions in Extracts of O and B Horizons from a New England Spodosol: Effects of Acid Treatment
Authors: David Mark B. , Vance George F. , Rissing Joseph M. , Stevenson Frank J.
Published: July 2010

We examined the effects of H2SO4 and HNO3 on dissolved organic carbon (DOC), pH, and DOC fractions in extracts from Spodosol O and B horizon samples of a forest soil from eastern Maine. Preliminary work with HNO3 at p[H+] = 3 (1 to 24 h shaking, ionic strength adjustment with NaNO3 (I = 0.1 to 0.001) indicated rapid equilibration (1 h) of DOC in treatment solutions with B horizon samples, but that DOC levels in extracts from the O horizon increased continuously over time. In the remaining work, H2SO4 and HNO3 and their Na salts were added at a constant I of 0.01 and solutions were recovered after shaking for 16 h. The DOC in O horizon extracts decreased with increasing acidity, reaching a minimum at p[H+] = 2 (from ca. 5 mmol C L−1 with no acid addition to ca. 2 mmol C L−1). For the B horizon extracts, DOC increased with increasing acidity. Percent neutralization of added H+ ranged from 18 to 99% in the O horizon for acid treatments ranging from p[H+] = 1 to 4 respectively; B horizon values were 16 to 85% for H2SO4 and 2 to 70% for HNO3. The DOC in O horizon solutions was dominated by hydrophobic and hydrophilic acids (ca. 45 and 20% of DOC, respectively), which were altered by acidic inputs; primarily by a decrease in hydrophobic acids (45 to ca. 15–18% of DOC) and an increase in hydrophilic acids (ca. 20 to 35–40% of DOC) as acidity increased. For the B horizon, similar trends were observed, although hydrophobic/hydrophilic acid ratios were lower, indicating that hydrophobic acids have a lower solubility with increasing acidity. From an environmental perspective, increasing acidic inputs through wet and dry deposition on forest Spodosols of New England may have significant consequences in the solubilization and transport of metals and acidity because of differences in DOC fractions.
Direct Effects of Simulated Acid Rain on Sexual Reproduction in Corn
Authors: DuBay Denis T.
Published: July 2010

The process of sexual reproduction in flowering plants often exposes pollen grains to the environment and the potential effects of atmospheric deposition. Experiments were designed to determine whether simulated acid rain treatments just before or after pollination could adversely influence reproductive processes and seed set in corn (Zea mays L.). Container‐grown corn with sexually mature tassels and ears were exposed once to simulated rain at four pH levels for 1 h, beginning 1 h after artificial pollination or ending 10 min before artificial pollination. The single, artificial pollination deposited an average of 85 pollen grains per silk. Simulated rain treatment at pH 4.5, 3.5, or 2.5 after pollination reduced the percentage seed set of treated ears 7, 29, and 34%, respectively, as compared with pH 5.5. Simulated rain at pH 5.5 after pollination reduced seed set 24% as compared with no‐rain controls. The pH of simulated rain applied before pollination did not affect seed set, and pH 5.5 rain applied before pollination had no effects on seed set compared to no‐rain controls. Microscopic observations indicated that pollen germination and pollen tube penetration of the silk were completed by the time the rain treatments began 1 h after pollination. This infers that simulated acid rain influenced pollen tubes after they entered the silks. These results suggest that plant sexual reproduction could be adversely affected by acidic precipitation at pH levels observed for rain events in eastern North America.
Temporal Variation in Nitrate and Nutrient Cations in Drainage Waters from a Deciduous Forest
Authors: Foster N. W. , Nicolson J. A. , Hazlett P. W.
Published: July 2010

Temporal variations in soil solution and stream chemistry were examined in 1984 in an undisturbed sugar maple‐yellow birch (Acer saccharum Marsh.‐Betula alleghaniensis Britton) forest in the Turkey Lakes Watershed, Ontario. Nitrate was the dominant anion associated with cation depletion from soil. Nitrogen in precipitation was less important than soil N in the determination of solution chemistry. Growing‐season increases in NH+4 and NO−3 in soil solution were greatest in the Oe horizon and decreased with depth. Nitrate concentrations in mineral soil solution and streamwater were highest during the dormant period and peaked at the start of spring snowmelt. Although NO−3 concentrations in streamwater were positively correlated (r = 0.7–0.9) with NO−3 and Ca2+ concentrations in mineral soil solution during the dormant period, NO−3 contributed far less to cation fluxes in streamwater than HCO−3 or SO2−4.
Guidelines for Selenium in Irrigation Waters
Authors: Albasel N. , Pratt P. F. , Westcot D. W.
Published: July 2010

Because of the relatively high concentration of Se in the agricultural drainage waters of the west side of the San Joaquin Valley (SJV) in California and the potential for reuse of these waters on salt tolerant crops, a reassessment of quality criteria for Se in irrigation waters for this area was needed. The specific conditions for this area that justified a reassessment were (i) the Se in the drainage waters of the West Side is largely in the selenate (SeO4) form which is not appreciably adsorbed by soils and is thus readily leached from the root zone, (ii) the waters containing high concentrations of Se have substantial concentrations of sulfate (SO4) that dramatically reduce SeO4 adsorption by plants, (iii) the salinity of the waters that contain high Se concentrations demand leaching fractions (LF) that insure that Se is also leached from the root zone, and (iv) kinetics of Se‐species transformations. Recent research with alfalfa (Medicago sativa L.), which is one of the most sensitive as crop growth for Se accumulation, suggests that this crop can tolerate an average soil solution Se concentration (Sess) of 250 µg/L without exceeding the limit of 4 mg Se/kg in the dry weight of forage that has been set to protect bovine animals from Se toxicity. Based on a model the Se in the irrigation water (Seiw) can increase of 100 µg/L at LFs of 0.2 to 0.3 without exceeding the maximum (Sessm) established for this crop when irrigated with sulfate waters. Thus, the recommended maximum Seiw for alfalfa grown on the West Side of the SJV is 100 µg/L. Guidelines for other crops can be established if the relationships among Seiw, Sessm, LF, the Se in harvested products (Sehp), and the maximum Sehp for various uses of products for protection of wildlife, domestic animals, and humans are known.
Guidelines for Molybdenum in Irrigation Waters
Authors: Albasel N. , Pratt P. F.
Published: July 2010

Molybdenum (Mo) in relatively high concentrations has been found in saline SO2−4‐dominated agricultural drainage waters of the West Side of the San Joaquin Valley (WSSJV) of California. Because of the potential for using these waters for irrigating salt‐tolerant crops, an assessment of quality guidelines for Mo for the specific conditions of the WSSJV was justified. The unique conditions of (i) alkaline soils favoring Mo mobility, (ii) the high leaching fractions required to control salinity in the root zone, and (iii) the effect of SO2−4 in reducing Mo absorption by plants suggested that the guideline of 10 µg L−1 to protect crops and animals be increased to 50 µg L−1 for the WSSJV. The Mo input at this concentration assuming the use of 10 000 m3 of water ha−1 will be 0.5 kg h −1.
Agricultural Impacts of Coal Mine Subsidence: Effects on Corn Yields
Authors: Darmody R. G. , Jansen I. J. , Carmer S.G. , Steiner J.S.
Published: July 2010

Undergronnd coal mining methodology is moving toward techniques that cause immediate planned subsidence of the overlying land. Damage done by subsidence to structures has been documented, but the effects on agricultural productivity are undocumented. This study was conducted to (i) determine the extent of measurable subsidence effects associated with planned subsidence mining, (ii) measure the impact of subsidence on corn (Zea mays L.) yield, and (iii) compare the effects of longwall and high extraction retreat mining methods. Five locations in southern Illinois were included in the 3 yr of the study. A total of 4605 ha in 1985, 6747 ha in 1986, and 7764 ha in 1987 were involved. These areas represented unmined control areas as well as longwall (LW) and high extraction retreat (HER) types of mines. Aerial photographs of the study locations were taken in the spring of each year. Subsided areas were identified, classified, and measured on the photos. The average percent of the study urea with measurable subsidence effects was 7.5% for LW mining and 3.3% for HER mining. Corn was harvested each year on selected subsided and nearby unsubsided reference areas. The weighted average reduction in corn yield on land above the mines was calculated by multiplying the affected area by the associated yield reduction. The weighted average yield reduction was 4.7% for LW mining and 1.8% for HER mining. Results for the individual years varied with the weather: the greater the precipitation, the greater the yield reductions. The results also reflect the yearly variation in mining activity, crop sample areas, and overall study areas. In addition, the mitigation of subsidence effects in place at the time of the study also influenced the results, but the potential for mitigation for either mining type was not included in the research.
Vegetation of Waste Disposal Areas at a Coal‐Fired Power Plant in Kansas
Authors: Mulhern D. W. , Robel R. J. , Furness J. C. , Hensley D. L.
Published: July 2010

Disposal of scrubber sludge and fly ash waste from coal‐fired power plants is a costly problem for utilities. Current regulations call for the retired waste areas to be covered with topsoil, then seeded to produce a protective vegetative cap. We conducted field tests over a 3‐yr period to determine if a vegetative cover could be established without first adding topsoil to waste sites. Seven herbaceous and six tree species were planted on scrubber sludge and bottom ash sites. These substrates were first amended with fertilizer, and then hay, woodchips, or cow (Bos taurus) manure. The bottom ash was not capable of supporting vegetative growth, even with amendment. Tall wheatgrass [Agropyron elongatum, (Host) Beauv.], tall fescue (Festuca arundinacea Schreb.], yellow sweet clover (Melilotus officinalis Lam.), and Japanese millet [Echinochloa crusgalli (L.) Beanv.] grew well on scrubber sludge, as did eastern cottonwood (Populus deltoides Marsh.) and eastern red cedar trees (Juniperus virginiana L.). Generally, herbaceous plants grew best on scrubber sludge to which manure and fertilizer were added, and the trees survived and grew best on scrubber sludge amended with woodchips and fertilizer. This study demonstrates that a good vegetative cover can be produced on scrubber sludge waste areas without first covering them with topsoil.
Effects of Long‐Term 2,4‐D and MCPA Field Applications on Soil Residues and Their Rates of Breakdown
Authors: Smith A. E. , Aubin A. J. , Biederbeck V. O.
Published: July 2010

A 3‐yr rotation of wheat (Triticum aestivum L.), wheat, and summerfallow in field plots on a clay soil at the Indian Head Experimental Farm, Saskatchewan, has been receiving annual applications of ester and amine formulations of 2,4‐D (2,4‐dichlorophenoxyacetic acid) since 1947, and MCPA (4‐chloro‐2‐methylphenoxyacetic acid) since 1953. In the fall of 1987, after 40 successive applications of 2,4‐D and 34 annual treatments of MCPA, soil samples were taken from the 0‐ to 15‐cm and 15‐ to 30‐cm depths of replicate treatments. Gas chromatographic analysis revealed that residual amounts of 2,4‐D and MCPA were less than 0.02 mg kg−1, indicating that there had been complete degradation of the herbicides. Under laboratory conditions, the breakdown of 2.0 mg kg−1 (14C)2,4‐D and (14C)MCPA was slightly faster in soils that had received continuous applications with the appropriate herbicide, than in soil from the untreated control plots, suggesting some soil microbial adaptation in response to long‐term use of these herbicides.
Prediction of Soluble Phosphorus Transport in Agricultural Runoff
Authors: Sharpley A. N. , Smith S. J.
Published: July 2010

The soluble phosphorus (SP) concentrations of runoff for individual events from agricultural land were predicted using relationships describing soil P desorption kinetics and effective depth of surface soil‐runoff interaction (E). These values were compared with concentrations measured for runoff from 9 grassed and 11 cropped watersheds in the Southern Plains, USA, over a 10‐yr period. Using a constant value of E for a given watershed, measured SP concentrations were over‐estimated by up to 4415% for runoff events of > 0.75 mm in volume. Using a value of E calculated for each runoff event from soil loss, correlation coefficients between measured and predicted values and prediction errors were improved (R2 = 0.95–0.99 and error = 11–18%) compared to use of a constant E value (R2 = 0.21–0.83 error = 38–380%) averaged for each watershed location. Although these improvements did not significantly (5% level) affect estimates of the amounts of SP transported, the improvements will be important from environmental aspects, in terms of assessing the impact of agricultural management practices on P‐related eutrophication for all runoff events.
Heavy Metal Accumulation in Small Mammals following Sewage Sludge Application to Forests
Authors: Hegstrom Linda J. , West Stephen D.
Published: July 2010

The application of sewage sludge to forested land as a fertilizer may result in the transfer of heavy metals from sludge to wildlife. Levels of four heavy metals (Cd, Pb, Zn, and Cu) were measured in livers and kidneys of insectivorous Trowbridge's shrews (Sorex trowbridgii) and shrew‐moles (Neurotrichus gibbsii), and granivorous deer mice (Peromyscus maniculatus) from sludge‐treated and untreated sites at Charles Lathrop Pack Forest, located near Eatonville, WA. Heavy metal levels were higher in the organs of Trowbridge's shrews from sledge‐treated areas than in those from untreated areas. Only Cd was elevated in both organs of the deer mouse. Shrew‐moles from sludge‐treated sites had higher levels of Cd and Pb, but not Zn or Cu, than those from untreated sites. In general, heavy metal levels in the three species from control sites at Pack Forest were similar to levels found in animals from five other control sites in western Washington. Samples of liver and kidney tissue from Trowbridge's shrews were examined for evidence of heavy metal‐induced lesions. Despite the high levels of heavy metals found in Trowbridge's shrews, no lesions were found in their organs.
Effectiveness of Mechanical Aeration in Floating Aquatic Macrophyte‐Based Wastewater Treatment Systems
Authors: DeBusk T. A. , Reddy K. R. , Clough K. S.
Published: July 2010

Outdoor tanks containing the floating aquatic macrophyte water hyacinth [Eichhornia crassipes (Mart) Solms] were provided with diffuse aeration to evaluate its effect on wastewater treatment efficiency and plant growth. Light aeration (0.003 and 0.021 L m−2 min−1) had no effect on the treatment of primary domestic effluent in the batch‐fed water hyacinth tanks. Heavy aeration (1.03 and 3.53 L m−2 min−1) raised wastewater dissolved oxygen (DO) concentrations, but did not improve biochemical oxygen demand (BOD5) removal efficiency or increase plant growth rates during 21‐d experiments. Heavy aeration slightly increased wastewater N removal, but the effectiveness of aeration for nutrient removal was not consistent among experiments. In continuous‐flow raceways fed primary domestic effluent, vigorous aeration (6.1 L m−2 min−1) improved effluent quality, with contaminant removal rates averaging 77% (BOD5) and 76% (suspended solids [SS]) in nonaerated raceways, and 94% (BOD5) and 89% (SS) in aerated raceways. Results of this study suggest that the high aeration requirement for enhanced contaminant removal in floating aquatic macrophyte systems (FAMS) is due not only to poor O2 transfer efficiencies (1.6–4.0%), but also to the inefficient utilization of O2 for BOD5 removal. The primary benefit of moderate aeration (0.1–1.0 L m−2 min−1) in FAMS appears to be the elevation of wastewater DO concentrations (from 0.5 to 2.5 mg L−1), which may be useful for controlling odors and mosquito proliferation.
Sulfate Adsorption and Desorption Reversibility in a Variety of Forest Soils
Authors: Harrison Robert B. , Johnson Dale W. , Todd Don E.
Published: July 2010

Subsurface soil samples were collected from 20 forest sites of differing soil and cover type, atmospheric deposition history and physiographic location. Samples were analyzed for S pools, sulfate adsorption capacity, adsorption reversibility, and associated soil properties in order to compare the relative S chemistry and SO4 retention capacities of the sites. The SO4 adsorption capacity was determined by sequential equilibration of air‐dried soil samples with a percolating solution of 0.25 mM CaSO4, and adsorption reversibility by leaching both SO4 saturated and untreated soil samples with deionzed water. Phosphate extractable SO4 was measured at the end of each series of equilibrations as a means of estimating irreversibly adsorbed SO4. A total of 32 out of 36 soil horizons studied showed net SO4 adsorption, ranging from a desorption of 0.4 to an adsorption of 7.2 mmol SO4 kg−1. Thus, most of these soils were not yet saturated with respect to a solution concentration of 0.25 mM SO4. Most soil horizons showed irreversible SO4 adsorption (an average of 36% of adsorbed SO4 was retained irreversibly) as evidenced both by changes in phosphate extractable SO4 and by a comparison of desorption of SO4 before and after saturation by the 0.25 mM SO4 solution. When adsorption and adsorption reversibility observations were compared with measured soil properties, the presence of hydrous oxides of Al and native SO4 were the best indicators of SO4 adsorption potential. Most adsorption/desorption/extraction sequences showed mass conservation of SO4, indicating inorganic SO4 adsorption appeared to be far more important in these procdures than organic S incorporation or mineralization. It is unclear how much air‐drying, sample treatment, and the procedures followed might have changed the inorganic and organic S pools of these soils.
Analysis of Effects of Atmospheric Carbon Dioxide and Ozone on Cotton Yield Trends
Authors: Reddy V. R. , Baker D. N. , McKinion J. M.
Published: July 2010

Cotton (Gossypium hirsutum L.) yields have declined since 1964 despite improvements in technology and introductions of higher‐yielding cultivars. Cotton scientists have been unable to identify exact causes of the yield decline. For the past 25 yr, global atmospheric CO2 concentration ([CO2]) has been increasing due to the increased burning of fossil fuels; cotton has been found to be sensitive to [CO2]. Cotton has also been found to be sensitive to atmospheric ozone concentration ([O3]) at levels that occur regularly where it is grown.

To analyze the effects of [CO2] and [O3] on cotton‐yield trends, simulations were made using the cotton crop model GOSSYM. Input data for simulations were obtained from cotton breeders' trial sites located at Florence, SC; Stoneville, MS; College Station, TX; Phoenix, AZ; and Fresno, CA.

The simulated effects of the [CO2] and [O3] on cotton yields changed from location to location due to interactions with soil, plant, and atmospheric variables and with nutrient levels in the soil. Given enough N, the increased [CO2] would probably result in a 10% increase in lint yield. Due to N stress sometime during the growing season, however, the plants could not fully utilize the increased [CO2]. Ozone concentration increased during the period of cotton‐yield decline, and this increase in [O3] was found to affect simulated cotton yields adversely. It appears that O3 is one of the contributing factors to the yield decline. Overall O3 had a more adverse effect on simulated cotton yields at locations where O3 was present at higher concentrations, i.e., Phoenix, AZ and Fresno, CA.
Infiltration of Wastewater in a Newly Started Pilot Sand‐Filter System: III. Transformation of Nitrogen
Authors: Pell Mikael , Nyberg Fred
Published: July 2010

The objective of the study was to monitor the chemical dynamics associated with N transformations from start‐up until a steady state was reached in a pilot sand‐filter system consisting of a three‐chambered septic tank, a sand filter with a one person capacity, and eight columns. The system was loaded with 67 L m−2 d−1 of an artificial wastewater. The untreated wastewater contained 114 mg Kjeldahl N L−1 and 0.12 mg NH+4‐N L−1. Mineralization reached a steady state in the septic tank after 2 wk of operation; thereafter, 65 ± 6% of the effluent N was NH+4‐N. In the column effluent the concentrations of NH+4‐N increased during the first 6 wk of operation, whereafter a stabilization at 60 to 80 mg NH+4‐N L−1 occurred. The mean proportion of effluent N in mineralized form for the whole period was 88 ± 6%. Three weeks after start‐up, all effluent N from the sand filter was in mineralized form and remained high for the rest of the study period. The effluent concentrations of NH+4‐N increased rapidly during the first 2 wk after which it decreased to less than 3 mg L−1. The concentration of NO−3‐N was initially low. It then increased until about Day 30 when it stabilized at 64 to 71 mg NO−3‐N L−1. Elevated concentrations of NO−2‐N were observed between Days 8 and 45. Nitrifying activity reached a steady state after 6 wk of operation. During this state a considerable amount of nitrification took place in the upper 1.5 cm and all wastewater N had been nitrified after 15 cm of percolation. By the end of the operating period the total amount of influent N in the septic tank had been reduced by 17%. Corresponding reductions for the columns and sand filter were 18 and 33%, respectively.
Field Persistence Studies with the Herbicide Glufosinate‐Ammonium in Saskatchewan Soils
Authors: Smith Allan E. , Belyk Murray B.
Published: July 2010

Field plots on clay at Regina and Indian Head, and on clay loam at White City, Sask., were treated with glufosinate‐ammonium (the ammonium salt of DL‐homoalanin‐4‐ylmethylphosphinic acid) at a rate of about 1kg ha−1 during June or July 1988. At regular intervals, soil samples were taken from the 0‐ to 10‐cm and 10‐ to 20‐cm soil levels and extracted and analyzed gas chromatographically for glufosinate remaining. In addition, amounts of the soil metabolite MPPA [3‐(hydroxymethylphosphinyl)propionic acid] were also monitored. Providing there was adequate moisture, breakdown of the herbicide was rapid with no glufosinate detectable in any of the soils by the end of September 1988. In all soils the breakdown of MPPA was slower than that of glufosinate. Maximum amounts of the metabolite formed in the soils ranged from 0.26 kg ha−1 in the clay loam to 0.52 kg ha−1 in the clay at Regina. By the end of September there were 0.23, 0.06, and 0.17 kg ha−1 of MPPA in the 0‐ to 10‐cm soil level at Regina, White City, and Indian Head, respectively. There was no leaching of either glufosinate or MPPA to soil depths below 10 cm.
Decompostion of Hydrazine in Aqueous Solutions
Authors: Moliner Ana M. , Street J. J.
Published: July 2010

The effects of several environmental factors on the fate of hydrazinc in aqueous systems were studied. In aqueous systems, the primary mechanism of hydrazine (N2H4) degradation appears to be a four‐electron oxidation to N2 gas by oxygen. The oxidation rate was very slow in distilled water but increased with the addition of catalysts such as Cu(II) and phosphate ions. Conditions that accelerated the formation of the hydrazyl radical, the first step in hydrazine oxidation, increased the proportion of one‐electron oxidation. This resulted in increasing the formation of ammonia as one of the degradation products. Ammonia evolution was correlated with Cu(II) and phosphate ion concentrations, as well as with temperature. Hydrazine oxidation was primarily dependent on the rate of the oxygen diffusion from the gas phase.
Behavior of Aromatic Surfactants and PCBs in Sludge‐Treated Soil and Landfills
Authors: Marcomini A. , Capel P. D. , Lichtensteiger Th. , Brunner P. H. , Giger W.
Published: July 2010

The aromatic surfactant linear alkylbenzenesulphonate (LAS) and the refractory biointermediates of nonylphenol polyethoxylates (NPEO), namely nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO), together with polychlorinated biphenyls (PCBs) and organic carbon (OC), were determined in sludge‐treated soil at 19 time intervals during a 1‐yr period after sludge application. The initial concentrations of LAS, NP, NP1EO, and NP2EO in the amended soil were 45, 4.7, 1.1 and 0.1 mg/kg (dry wt.); the residual mean concentrations, 320 d after the last sludge application, were 5, 0.5, 0.1, and 0.01 mg/kg for LAS, NP, NP1EO, and NP2EO, respectively. All of the aromatic surfactants demonstrated a very fast decrease in concentration (>80% within the first month), presumably due to biodegradation, but all of them exhibited a residual concentration in the soil after 320 d. Total PCBs and OC showed no significant soil concentration changes, within the error of analysis, over this same 1‐yr period. The pattern of PCB congeners also demonstrated no substantial changes, indicating that they all behave very similarly. The LAS and PCBs were also measured in samples from dated ponds of four sludge‐only landfills which were in use at different times over the past 30 yr. The increase in the use of LAS and decrease in the open use of PCBs was reflected in the sludge pond concentrations at one site where there was a continuous record from 1972 to 1986.
A Semiautomated Instrument for Measuring Total and Radiolabeled Carbon Dioxide Evolution from Soil
Authors: Shelton Daniel R. , Parkin Timothy B.
Published: July 2010

The design and operation of a semiautomated instrument for measuring total and radiolabeled CO2 evolution from soil is described. In the recirculation mode, headspace gases are recirculated in a closed loop through an infrared (IR) detector. After a steady state is achieved, the concentration of total CO2 is read and recorded. In the flush mode, compressed air is used to flush CO2 from the headspace into test tubes containing trapping solution. Radiolabeled carbon dioxide is quantified by counting aliquots of trapping solution in a liquid scintillation counter. The variability associated with the IR detector is 3.6% (coefficient of variation). The trapping efficiency is 100% (±2.0%). The variability associated with two different methods of pesticide application to soil was also investigated. With the slurry method, aliquots of air‐dried soil were added to a pesticide solution [carbofuran(2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate)] with thorough mixing. With the spray method, the carbofuran solution was applied as an aerosol to soil that had been previously wetted. There was little difference in the variability of total CO2 production between the two methods. The variability associated with 14CO2 evolution from soil (carbofuran hydrolysis), however, was greater with sprayed soil than with slurred soil, suggesting that the slurry method resulted in a more homogenous distribution of pesticide throughout the soil. The low analytical variability associated with measurements of total CO2 and 14CO2 production, as well as the large number of samples that can be accommodated (up to 94 flasks or intact soil cores) make this instrument ideal for the execution of the large screening studies needed to obtain reliable estimates of the spatial variability of rates of pesticide degradation.
The Fate of Nitrogenous Fertilizers Applied to Turfgrass
Authors: Petrovic A. Martin
Published: July 2010

Maintaining high quality surface and groundwater supplies is a national concern. Nitrate is a widespread contaminant of groundwater. Nitrogenous fertilizer applied to turfgrass could pose a threat to groundwater quality. However, a review of the fate of N applied to turfgrass is lacking, but needed in developing management systems to minimize groundwater contamination. The discussion of the fate of N applied to turfgrass is developed around plant uptake, atmospheric loss, soil storage, leaching, and runoff. The proportion of the fertilizer N that is taken up by the turfgrass plant varied from 5 to 74% of applied N. Uptake was a function of N release rate, N rate and species of grass. Atmospheric loss, by either NH3 volatilization or denitrification, varied from 0 to 93% of applied N. Volatilization was generally <36% of applied N and can be reduced substantially by irrigation after application. Denitrification was only found to be significant (93% of applied N) on fine‐textured, saturated, warm soils. The amount of fertilizer N found in the soil plus thatch pool varied as a function of N source, release rate, age of site, and clipping management. With a soluble N source, fertilizer N found in the soil and thatch was 15 to 21% and 21 to 26% of applied N, respectively, with the higher values reflecting clippings being returned. Leaching losses for fertilizer N were highly influenced by fertilizer management practices (N rate, source, and timing), soil texture, and irrigation. Highest leaching losses were reported at 53% of applied N, but generally were far less than 10%. Runoff of N applied to turfgrass has been studied to a limited degree and has been found seldom to occur at concentrations above the federal drinking water standard for NO−3. Where turfgrass fertilization poses a threat to groundwater quality, management strategies can allow the turfgrass manager to minimize or eliminate NO−3 leaching.
Plant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants
Authors: Allen L. H.
Published: July 2010

As global population increases and industrialization expands, carbon dioxide (CO2) and toxic air pollutants can be expected to be injected into the atmosphere at increasing rates. This analysis reviews a wide range of direct plant responses to rising CO2, increasing levels of gaseous pollutants, and climate change, and to potential interactions among the factors. Although several environmental interactions on stomata and foliage temperatures are reviewed briefly, a comprehensive review of effects of potential climatic change on plants is not a major objective of this analysis. Research shows that elevated CO2 increases photosynthetic rates, leaf area, biomass, and yield. Elevated CO2 also reduces transpiration rate per unit leaf area, but not in proportion to reduction of stomatal conductance, because foliage temperature tends to rise. With increasing leaf area and foliage temperature, water use per unit land area is scarcely reduced by elevated CO2. Increases in photosynthetic water‐use efficiency are caused primarily by increased photosynthesis rather than reduced transpiration. Gaseous pollutants (O3, SO2, NOx, H2S) affect plants adversely primarily by entry through the stomata. An example calculation showed that reduction in stomatal conductance by doubled CO2 could potentially reduce the effects of ambient O3 and SO2 by 15%. However, information on the interaction of CO2 and air pollutants is scanty. More research is needed on these interactions, because regional changes in air pollutants are occurring concurrently with global changes in CO2.
A Review of the Response of Epicuticular Wax of Conifer Needles to Air Pollution
Authors: Turunen M. , Huttunen S.
Published: July 2010

The effects of air pollutants on the epicuticular wax structure of conifer needles and the ecophysiological consequences of the injuries are reviewed on the basis of published literature and the authors' recent investigations. Degradation of the epicuticular waxes, which appears as a fusion of wax tubes in the epistomatal chambers and finally results in an amorphous appearance of the waxes, is the most common micromorphological injury type observed in studies on the genera Abies, Larix, Picea, and Pinus. The rate of erosion correlates well with the level of air pollution, but clear evidence for the specificity of the symptoms for different air pollutants has not been observed. It is concluded that the erosion of the epicuticular waxes, a phenomenon with a large geographic distribution, is a relevant factor of the multiple forest decline syndrome. Erosion of the waxes can change needle wettability and rain retention. Increased needle wettability and permeability of the cuticles can result in enhanced leaching of nutrients and uptake of pollutants. Increased or decreased stomatal and cuticular diffusion resistance of the needles leads to altered transpiration rates. Due to the changed chemical microenvironment of the needles, the conifers are predisposed to various biotic and abiotic stresses. Because the epicuticular waxes are one of the first targets of a variety of air pollutants, they can widely be used as an early indicator of air pollution effects.
Aluminum Speciation Using Morin: I. Morin and Its Complexes with Aluminum
Authors: Browne B. A. , McColl J. G. , Driscoll C. T.
Published: July 2010

In this and a companion study, we developed a procedure that uses the fluorescing chelating agent morin (2,3,4,5,7‐pentahydroxy‐flavone) to speciate aqueous Al in the acidic pH range. Morin is a pentaprotic acid with five weakly acidic functional groups. However, only the first proton dissociation reaction was found to be significant in the acidic pH range, and a simple monoprotic model (pKal = 5.04) accurately described proton binding. Aluminum and morin formed complexes of 1:1 and 1:2 and/or 1:3 (Al/morin) stoichiometry, but at low total morin concentrations (near 1 µM) only 1:1 species were prevalent. The equilibrium chemistry of 1:1 Al/morin complexes in the acidic pH range was closely described by a parabolic model consistent with the formation of three complexes: AlH4MOR2+, Al(OH)H4MOR+, and Al(OH)2H4MOR0. For Al and six potentially interfering cations, the order of affinity for morin relative to Al in the acidic pH range was approximately as follows: Al > Fe(III) > Cu > Fe(II) > Ca > Mg > Mn = Zn. Formation of competing cation‐morin complexes was enhanced with increasing pH. None of the tested cations formed complexes with morin with fluorescence spectra overlapping the spectra of the Al‐morin complexes.
Aluminum Speciation Using Morin: II. Principles and Procedures
Authors: Browne B. A. , Driscoll C. T. , McColl J. G.
Published: July 2010

In this study we present an analytical technique that uses a dilute aqueous solution of the fluorescing chelating agent morin (2,3,4,5,7‐pentahydroxyflavone) (1 µM) to distinguish between Al species in acidic solutions. Sensitive and accurate speciation estimates were obtained for synthetic solutions containing low concentrations of model Al binding ligands (1 µM F or 0.001 M SO4). Good agreement existed with thermochemical modeling predictions, and accurate equilibrium constants were estimated for AlF2+ and Al(SO4)+. For the F solutions, speciation measurements made with morin were superior to measurements made with the F ion selective electrode. For natural water samples (n = 108) exhibiting a wide range of pH and concentrations of Al binding ligands, the addition of morin did not obscure the subtleties of the Al species distribution. The average redistribution of Al species in the presence of morin was less than 3%, and a correction factor was applied to calculate the species distribution prior to morin addition. The fraction of total Al bound with organic solutes estimated using morin (74%) was significantly higher than in previous studies using other techniques. The magnitude of uncertainties in species concentration estimates, estimated by Monte Carlo simulation, varied with pH, Al concentration, and total morin concentration. For 1 µM morin solutions, maximum uncertainties for major Al species were low (approx. <12%) in the pH range between 3 and 7.
Lake Level Influences on Sediment and Nutrient Retention in a Lakeside Wetland
Authors: Clausen J. C. , Johnson G. D.
Published: July 2010

Lake levels, sediment and nutrient retention, and flows were studied in a 180‐ha wetland adjacent to Lake Champlain, VT, to assess the role of lake levels on sediment and nutrient retention within the wetland. This wetland received both point and nonpoint sources of nutrients. Input, output, and within‐wetland water samples were collected at 15 sites, and flows were measured nine times in 1983 at lake levels varying over 2 m. The ratio of wetland inflow to outflow was related to changes in lake levels. During spring, the concentrations of total suspended solids, total P, and total Kjeldahl N throughout the wetland were lower than during summer and fall periods. Wetland outlet concentrations decreased with rising lake levels. When wetland inflows exceeded outflow, there was a net mass retention of total suspended solids, total P, and total Kjeldahl N. Exports from the wetland decreased as lake level increased. The sediment and nutrient treatment capacity of this lakeside wetland appeared to be dominated by hydrologic influences.
Release of Radon‐222 by Vascular Plants: Effect of Transpiration and Leaf Area
Authors: Lewis B. G. , MacDonell M.M.
Published: July 2010

At disposal sites for wastes containing radium (Ra), vegetative stabilization may allow escape of radon (Rn) via uptake and mass flow of the gas in the plant transpiration stream. The main objectives of this work were to determine the magnitude and factors of such transport. Corn (Zea mays L.), sunflower (Helianthus annuus L.), and tall fescue (Festuca arundinacea Schreb.) were grown in uranium mill railings solids containing 226Ra (4.4 × 103 Bq kg−1). The quantities of 222Rn released by the plants in a controlled environment chamber were measured in relation to water transpired and leaf areas. The 226Ra and 222Rn in corn xylem liquid, and diffusion of 222Rn across paraffin wax barriers, were also measured. The 222Rn release rates by the plants ranged from about 8 to 28 mBq s−1 m−2 of leaf area, and were unrelated to the quantity of water transpired. Generally, the plants tended to release twice as much radon at 15°C than at 30°C, a phenomenon explained in part by the increased solubility of Rn in water at the lower temperature. We suggest that the bulk of 222Rn released by the plants is taken up by mass flow in water, but at the leaf mesophyll Rn diffuses independently of water, through the entire leaf cross‐section, unimpeded by the cuticle and epicuticular wax. The species of plant does not appear to be a major factor in the quantity of Rn released to the air; rather, the amount of Rn released into the atmosphere from a given area of vegetated land is expected to be in direct proportion to the leaf area index.
Effects of Extraction Methods and Sample Storage on Properties of Solutions Obtained from Forested Spodosols
Authors: Ross Donald S. , Bartlett Richmond J.
Published: July 2010

Soil solutions obtained by three methods from Spodosols at a high‐elevation, forested study site were compared. Solutions were extracted by miscible displacement, by centrifugation, and by compressing a soil‐packed syringe. Analyses of pH, inorganic anions, total and reactive Al, and organic C showed few differences between miscible displacement and the syringe‐pressure methods. However, centrifugation at a relative centrifugal force (RCF) of 9700 m s−2 consistently produced solutions with significantly higher pH and F− content than did the other methods. Differences after centrifugation also were found in Cl−, NO−3, SO2−4, but Al, but less frequently. Effect of soil storage time on solutions obtained using the syringe‐pressure technique was studied. Both Oa and Bhs horizon samples showed large increases in solution NO−3 after 24 h of storage at 3°C. During 36 d of storage, NO−3 levels increased by as much as 10‐fold and were accompanied by pH decreases. Measurements in solutions obtained from samples that had been frozen for 36 d were higher than in the original solutions, except for NO−3 and pH. Changes with freezing appeared to be related to large increases in soluble organic C. Our results suggest that soil solution samples should be obtained very quickly after sampling of soils and that high‐speed centrifuge techniques may give erroneous results. The syringe‐pressure method is relatively rapid, simple, and easily performed in the field. However, it may not be practical under dry conditions.
Plant Uptake of Sludge‐Borne PCBs
Authors: O'Connor G. A. , Kiehl D. , Eiceman G.A. , Ryan J.A.
Published: July 2010

Plant uptake of sludge‐borne polychlorinated biphenyls (PCBs) (similar to Aroclor 1248) was evaluated in a greenhouse study with two food‐chain crops and a grass species. Polychlorinated biphenyl loading to two soils was varied in one experiment by adding different rates of a municipal sewage sludge heavily contaminated (52 mg kg−1 with PCBs. In a second experiment, Aroclor 1248 was spiked into unamended soils or soils amended with another sludge containing <1 mg kg−1 PCBs. Analysis of PCBs was by GC/MS with a reliable detection limit in plants of 20 µg kg−1 for individual chlorinated classes (tri‐, tetra‐, and pentachlorobiphenyls) and total PCBs. Only carrots (Daucus carota) were contaminated with PCBs, and contamination was restricted to carrot peels. Current USEPA guidelines for land application of sludges based on sludge PCB content are shown to be extremely conservative.
Volatilization of Selenium from Agricultural Evaporation Pond Water
Authors: Thompson‐Eagle E. T. , Frankenberger W. T.
Published: July 2010

A major concern in the San Joaquin Valley, CA, is that high levels of Se in agricultural drainage water are concentrating to hazardous levels in evaporation ponds. The primary objective of this study was to determine factors that affect Se biomethylation and thus permanently remove Se directly from evaporation pond water. Pond water samples (14–2000 µg Se L−1) were set up as laboratory mesocosms. The natural formation of dimethylselenide (DMSe) in unamended water was less than 1% of the total Se inventory after 40 d of incubation. No Se methylation took place in autoclaved, unamended pond water. L‐Methionine (10 µM) stimulated DMSe production in nonsterile pond water, and in autoclaved water (1 µM). Increasing the temperature to 35°C and the addition of 1% (wt/wt) glucose with a fungal inoculum, Alternaria alternata, doubled DMSe production over the controls after 25 d of incubation. Carbon sources such as glucose, maltose, sucrose, and galacturonic acid at 2 g C L−1 under ambient conditions slightly enhanced indigenous Se methylation (1.5‐fold). Of the amino acids tested, L‐methionine (0.02 g C L−1) stimulated DMSe evolution from pond water more so than L‐cysteine, L‐cystine, and L‐serine. The proteins, egg albumen, casein, and gluten (2 g C L−1) dramatically increased Se biomethylation causing a 23, 41, and 10% Se loss from the inventory, respectively, after 43 d of incubation. The stimulation of Se volatilization from evaporation pond water through specific amendments could prove to be promising as a field detoxification technique.
Surface‐Facilitated Chemical Degradation of Tetraphenylboron in Soil
Authors: Mills Gary L. , Kaplan Daniel , Schwind Donna , Adriano Domy
Published: July 2010

Laboratory studies were conducted to examine the surface‐promoted degradation of tetraphenylboron (TPB) in soil. The results indicated that TPB degrades rapidly in soil and that the processes involved are predominately abiotic reactions. The initial products of degradation of TPB are diphenylborinic acid (DPBA) and biphenyl. A portion of the DPBA produced subsequently degrades to produce boric acid. However, only about 20% of the total B added initially to the soil as TPB was accounted for by the measured species at the end of the experiment. Most of the remaining B appears to be present in moderately stable organic compounds. Comparison of the degradation rates in different soils indicated that the rates in the surface soil were somewhat higher than in the subsoil. The only measured characteristic of these soils that follows a corresponding trend is soil organic matter content. Additional experiments indicated that rates of the initial reaction are inversely related to soil moisture content. Observed reaction products indicate that the initial step in the degradation process is a two‐step oxidation at Lewis acid sites associated with soil component surfaces.
An Ultraviolet Absorbance Method of Estimating the Percent Aromatic Carbon Content of Humic Acids
Authors: Traina Samuel J. , Novak Jeff , Smeck Neil E.
Published: July 2010

The aromatic C content of humic acids strongly influences the complexation of nonpolar organic solutes by humic substances. A rapid method of estimating the aromatic C content of humic acids would be useful in studies of the fate of nonpolar organic solutes in soils and natural waters. The relationship between the UV absorptivity of nine different dissolved humic substances, measured at a wavelength of 272 nm, and their aromatic C content, as determined by 13C CPMAS NMR, was evaluated. The percent aromatic C (determined by NMR) was strongly correlated (r = 0.94) with the UV absorptivity measurements. It is suggested that determinations of UV absorptivity at 272 nm can be used to provide a quantitative estimate of the aromatic C content of dissolved humic acids.
Sensitivity of Tree Seedlings to Aluminum: I. Honeylocust
Authors: Sucoff Edward , Thornton F. C. , Joslin J. D.
Published: July 2010

Literature about the effects of Al on trees is reviewed in this article, emphasizing factors to consider when interpreting how seedling growth responds to Al. This article integrates two soil and two hydroponic studies that examine how honeylocust (Gleditsia triacanthos L.) seedlings respond to Al. The studies determined that honeylocust is the most Al‐sensitive forest tree to have been studied in detail. Plant biomass and root number declined as Al in the soil or hydroponic solution increased. Growth was most consistently related to e{Al3+} ({Al3+} is the Al3+ activity in the solution) or to the ratio of MAL/Ca (MAL is inorganic monomeric Al). In our study root number declined 50% between 0 and 0.05 mM MAL (0 to 0.012 mM {Al3+}). Root weight was also negatively related to root Al and positively related to root Ca. Levels of solution MAL/Ca and {Al3+} associated with more than 20% reductions in honeylocust growth were found in lysimeter solutions collected from a number of forested watersheds. However, such levels are probably not common in the natural edaphic range of honeylocust.
Nitrous Oxide Emissions from Fertilized Soils: Summary of Available Data
Authors: Eichner Melissa J.
Published: July 2010

Direct measurements of fertilizer‐derived N2O emission data from 104 field experiments reported in agriculture and soil science literature that were obtained between 1979 and 1987 were summarized and used to estimate worldwide fertilizer‐derived N2O emissions. Although without statistical determination, there appears to be a trend between emissions and type and quantity of fertilizer applied; the available data does not indicate a trend between emissions and a particular soil type or agriculture system. Using the fraction of the N fertilizer evolved as N2O and fertilizer consumption estimates for five fertilizer types, 0.1 to 1.0 Tg N2O‐N (avg. 0.3; median 0.2) were estimated to be released during the “sampling period.” If these estimates are doubled to account for emissions after the sampling period and emissions from fertilizer lost in drainage water and ground‐water, the expected range would be 0.2 to 2.1 Tg N2O‐N (avg. 0.7; median 0.5) emitted into the atmosphere in 1984. The magnitude of this estimate is in agreement with recent global estimates. If 100 Tg N fertilizer are consumed worldwide in the year 2000, the global release of fertilizer‐derived emissions into the atmosphere will probably not exceed 3 Tg N2O‐N in the year 2000. It is estimated that 23 to 315 Gg N2O‐N were emitted into the atmosphere from fields of cultivated leguminous crops in 1986. Future research needs were suggested.