bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Degassing of Carbon‐14 Dioxide: Rates and Factors
Authors: Sheppard Marsha I. , Ewing L. L. , Hawkins J. L.
Published: July 2010

Soil air normally contains elevated levels of CO2 relative to the atmosphere. The primary source of soil C is plant‐root and microbial respiration. The exchange of soil and atmospheric CO2 is important to many environmental concerns, such as acid rain, global warming and waste management. Proposed disposal of high‐level nuclear wastes containing primarily inorganic 14C may provide a source of 14CO2 to the atmosphere. Field and laboratory experiments show that 14CO2 soil degassing rate constants, the flux density (Bq·m2·s−1) divided by soil inventory (Bq·m−2), range from −10−7 to −10−2 s−1, and that the loss of inorganic 14C is driven primarily by gaseous diffusion. These constants are affected by soil pH and porosity, with smaller influences of soil temperature, moisture and organic matter content. Degassing rate constants derived through mass balance calculations to estimate loss differ only by 20% from direct trapping methods. Frozen soil degassing rate constants were up to 25 times smaller than lab values, indicating that annual 14C loss rates in northern climates would be lower because of reduced gaseous diffusion during the winter months. Using our field data, we recommend an annual 14C soil degassing rate constant of −1 × 10−6 s−1 for acidic soils and a value of −5 × 10−7 s−1 for calcareous soils. For probabilistic assessment modelling, we recommend a geometric mean degassing constant of −4.3 × 10−7 s−1 with a geometric standard deviation of 3.26 for three different soils. This indicates the median half‐life of 14C in surface soils is 18 d, with a 99% confidence interval of 13 h and 640 d.
A Two‐Region Model of Preferential Flow of Chemicals Using a Transfer Function Approach
Authors: Grochulska J. , Kladivko E. J.
Published: July 2010

Preferential flow processes are often used to explain rapid leaching of chemicals through intact soils. In this study we postulate a physical model within the framework of transfer function modeling, to describe the multiple chemical mass peaks in leachate from multiple rainstorms after a one‐tune chemical application. Two flow regions are assumed, the fast flow zone (preferential flow region) and a slow flow zone. The fast flow zone is completely leached of chemicals during each rainstorm event and subsequently replenished by the slow zone during periods between storms. Using the model equations, the chemical masses are calculated and fitted to the observed values of bromide, atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐S‐triazine) and alachlor [2‐chloro‐2′‐6′‐diethyl‐N‐(methoxymethyl)‐acetanilide] and several parameters characterizing the flow are found. These parameters are: cross‐sectional areas occupied by the fast and slow flow zones, mean chemical travel time, coefficient of variation (CV) characterizing the spread of the travel times, mixing time describing the rate of the chemical mixing with the pure water, and the coefficient of the effective mass transport between the slow and fast zones. The fitted parameters are examined to see whether they are attributable to any physical or chemical explanation, and if they indicate that the model assumptions are reasonable. The mean chemical travel times and the CV of travel times are similar for all three chemicals, suggesting that sorption is negligible during flow through the fast flow zone. The rate of chemical mixing with the new rainwater, as well as the rate of mass transport from the slow zone to the fast zone between storms, is related to the sorption properties of the chemicals. The model shows promise in describing preferential flow of pesticides under multiple rainstorms from data on bromide under the same water flow conditions.
Changes of Soil Nitrate‐Nitrogen and Denitrification as Affected by Nitrogen Fertilizer on Two Quebec Soils
Authors: Liang B. C. , MacKenzie A. F.
Published: July 2010

Corn (Zea mays L.) production may result in NO−3‐N accumulation in soils because of high N fertilizer applications. Nitrate‐N in soil may be lost by denitrification and leaching. Prediction of the amount lost would be helpful in minimizing these losses. Field experiments were conducted to investigate the effects of N fertilizer rates on soil NO−3‐N under corn on two soils of contrasting texture from 1988 to 1991 in southwestern Quebec. Denitrification as affected by previous N fertilizer rates was estimated for the nongrowing season of 1990–1991. Soil NO−3‐N levels in the fall increased linearly with increasing N fertilizer rates above the normal N rate both on clay and sandy clay loam soils. However, NO−3‐N could have been leached out of the rooting zone on the coarser Chicot soil (fine‐loamy, mixed, frigid Typic Hapludalf) in the late growing season, depending on rainfall. The changes in soil NO−3‐N over winter were a function of both soil NO−3‐N levels the previous fall and over‐winter precipitation. Denitrification losses varied from 7 to 24 kg ha−1 during the nongrowing season, increasing with N fertilizer rates only on the Ste. Rosalie clay soil (fine, mixed, frigid Typic Humaquept). In comparison with total NO−3‐N disappearance over the same period, losses of NO−3‐N due to denitrification were relatively small. Thus, significant portions of NO−3‐N losses were probably due to leaching both on clay and sandy clay loam soils.
Contaminant Enrichment and Properties of Soil Adhering to Skin
Authors: Sheppard S. C. , Evenden W. G.
Published: July 2010

The adhesion of contaminated soil to skin has potentially important health implications, because the contaminants may ultimately be ingested or absorbed through the skin. Previous studies indicated that the adhering soil is enriched in contaminant concentration relative to the original soil because of the selective adhesion of finer particles. This study investigated this enrichment using 11 markedly different soils. Two sandy soils consistently gave very high contaminant enrichment ratios, with a mean enrichment of 10‐fold. The other soils all had enrichment ratios above unity. Scanning electron microscopy illustrated the potential for strong adhesion of very fine clay particles. The contaminant enrichment ratios were positively correlated to enrichments in specific surface area, organic matter content, and extractable Fe content. Correlations to soil textural properties and detailed particle‐size analysis of the adhering soil indicated that 50 to 100 µm may be a critical particle size: larger grains and aggregates do not adhere readily to skin. Because of this, enrichment ratios will vary positively with the proportion of particles in the whole soil that are greater than 50 µm. A simple model is provided to predict enrichments using information from routine soil particle‐size analysis.
Radionuclides in Milk of Dairy Heifers Raised on Forages Harvested from Phosphatic Clay Soils on Reclaimed Mined Land
Authors: Staples C. R. , Umana R. , Stricker J. A. , Shibles D. , Hayen M. J. , Hissem C. D. , Lough D. S. , Demorest D. L.
Published: July 2010

Alfalfa (AR; Medicago sativa L.) and corn (CSR; Zea mays L.) were grown in phosphatic clay soils on phosphate‐mined reclaimed land in central Florida. Corn (CSC) also was grown on unmined land and served as a control forage. Upon harvesting, plants were chopped and ensiled. Concentrations of 226Ra averaged 2.44, 0.26, and 0.15; 210Pb averaged 1.04, 0.63, and 0.52; and 210Po averaged 1.59, 0.59, and 1.26 Bq kg−1 DM for AR, CSR, and CSC, respectively. These forages were fed separately to Holstein dairy replacement heifers (Bos taurus) (n = 15 per forage) from approximately 9 to 25 mo of age. Heifers gave birth to calves at approximately 24 mo of age. Samples of milk were collected on d 1, 15, and 30 of lactation and analyzed for radionuclides. Averaged across sampling days, heifers fed AR had greater milk concentrations of 226Ra compared with those fed CSR (0.27 vs. 0.22 Bq kg−1 DM; P<0.10), which, in turn, had greater milk concentrations compared with heifers fed CSC (0.22 vs. 0.13 Bq kg−1 DM; P<0.05). Heifers fed AR also had greater milk concentrations of 210Po compared with heifers fed CSR (0.58 vs. 0.30 Bq kg−1 DM; P<0.10), but values of CSR‐fed heifers were not different from CSC‐fed heifers (0.45 Bq kg−1 DM). Lead‐210 was greater in milk from heifers fed CSR compared with those fed AR or CSC (1.38 vs. 0.94 and 0.92 Bq kg−1 DM; P<0.13), respectively. Plasma S and Cu concentrations suggested subclinical molybdenosis in heifers fed AR. However, all heifers grew at an acceptable rate, conceived normally, had normal gestation periods, gave high quality colostrum at calving, and produced similar amounts of milk.
Naturally Occurring Radionuclides in Tissue from Beef Fed Phosphatic Clay‐Grown Forages
Authors: Stricker J. A. , Hanlon E. A. , West R. L. , Shibles D. B. , Sumner S. L. , Umana R.
Published: July 2010

This study was designed to determine if beef animals (Bos taurus) fed forages grown on reclaimed phosphate land accumulated selected radionuclides in muscle, kidney, or bone tissues. Sixty (60) beef steers (average weight 194.5 kg) were randomly assigned to one of four treatment groups: unmined pasture (control), reclaimed pasture, full feed of alfalfa (Medicago sativa L.) hay, or full feed of corn (Zea mays L.) silage both grown on reclaimed phosphatic clay. Animals remained on the study for approximately 14 mo and were then slaughtered. Radium226 in muscle tissue from the reclaimed pasture treatment was 0.081 Bq kg−1 and higher (P<0.05) than in muscle tissue from the other three treatments. Radium226 levels in kidney tissue from the unmined and reclaimed pasture treatments were higher (P<0.05) than from both corn silage and alfalfa hay treatments. Bone 226Ra levels were higher than both muscle and kidney tissue (P<0.05), but no statistically significant differences were observed in bone samples among the four treatment groups. Results of this study indicate no food safety problems from consuming products from beef animals fed forages grown on reclaimed phosphate land.
Atrazine and Metolachlor Dissipation in Soils Incubated in Undisturbed Cores, Repacked Cores, and Flasks
Authors: Topp Edward , Smith Ward N. , Reynolds W. Daniel , Khan Shahamat U.
Published: July 2010

This study compared three different laboratory methods for determining soil pesticide dissipation kinetics and pathways. The dissipation kinetics of the herbicides atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) and metolachlor (2‐chloro‐6′‐ethyl‐N‐(2‐methoxy‐1‐methylethyl)acet‐o‐toluidine) were examined in three soils (sandy loam, loam, clay loam) incubated for 63 d in flasks or intact cores (20 by 20 cm) under controlled moisture (field capacity) and temperature (25°C) conditions in the laboratory. The dissipation of metolachlor and atrazine were also examined in repacked cores of the loam soil adjusted to the field bulk density. The rates of atrazine or of metolachlor dissipation in soils incubated in flasks or in intact cores were indistinguishable (P<0.05). The rate of net accumulation of extractable transformation products from radiolabeled atrazine and the rate of nonextractable residue formation in soils incubated in flasks and intact cores were likewise the same. However, the rate of dissipation of metolachlor, the rate of accumulation of atrazine transformation products, and the rate of formation of nonextractable atrazine residues were all significantly slower in repacked cores of the loam soil. These results indicate that, under controlled laboratory conditions, atrazine and metolachior dissipation occured at the same rate in undisturbed soil cores and in flask incubations with soil that had been disrupted by previous air‐drying and sieving. We conclude that, at least in some soils, structure need not necessarily be maintained in laboratory soil pesticide dissipation experiments.
Isotherms of Cadmium Sorption Density
Authors: Schulte Andreas , Beese Fritz
Published: July 2010

To study Cd sorption, 16 soil samples of different chemical soil reactions were taken and analyzed for their physical and chemical properties. Adsorption of ethylene glycol monoethyl ether (EGME) and N2 were determined to establish the specific surface area of the soils. The sorption of Cd was modeled on a per‐mass basis using the Langmuir and Freundlich equations as well as per‐surface area basis. Traditional sorption isotherms reveal the relation between the amount of Cd sorbed and the Cd concentration in the soil solution only for the soil under study and can therefore not be applied, or can be applied only with restrictions, to other soils. To meet the aim of modeling Cd sorption and mobility for other soils or locations differing greatly in their properties, we attempted to establish a generalizing sorption isotherm for soils of entirely different composition of the solid phase. On the basis of characteristic values the 16 soil samples taken were grouped into three different reaction types (aluminum‐hydroxide, silicate, and carbonate‐buffer range). The generalizing Cd sorption density isotherms for these different soil groups introduced in the following provide a useful mathematical model for the quantity‐intensity relation of Cd in soils that differ greatly in their specific surface area and their composition.
Leachability of Heavy Metals from Growth Media Containing Source‐Separated Municipal Solid Waste Compost
Authors: Sawhney B. L. , Bugbee G. J. , Stilwell D. E.
Published: July 2010

The leaching of heavy metals in source‐separated municipal solid waste (MSW) compost was determined by irrigation leaching of growth medium, admixed with varying amounts of compost, used for container grown plants. Perennial flowers (black‐eyed Susan, Rudbeckia hirta L.) were grown in 2‐L containers filled with the growth medium for a 10‐wk period. Rainfall was supplemented with overhead irrigation to supply 2 cm of water per day. Leachates collected over each 2‐wk period were analyzed for Cd, Cr, Cu, Ni, Pb, and Zn using atomic spectrometry. Concentrations of the heavy metals in the leachates increased with increasing proportions of MSW compost in the growth medium, but decreased with time of leaching. Leaching of the metals occurred at relatively high concentrations initially, followed by continued leaching at low concentrations. The initial leaching of heavy metals is attributed to their soluble or exchangeable forms and the subsequent slow leaching to the solid compounds. The concentrations of the heavy metals remained below the current drinking water standards in all treatments throughout the leaching period. The results thus suggest that contamination of ground water with heavy metals from source‐separated MSW compost applied as a soil amendment should be negligible, as the low concentrations in the leachates leaving the surface soil would be further attenuated by the subsoil.
Diel Changes in Iron(III)/Iron(II) in Effluent from Constructed Acid Drainage Treatment Wetlands
Authors: Wieder R. Kelman
Published: July 2010

Within the past decade, over 400 wetlands have been constructed to treat acid coal mine drainage (AMD). This study was undertaken to examine whether the efficiency with which constructed wetlands retain Fe present in AMD changes on a day‐night basis. In each of live AMD treatment wetlands, constructed with a different organic substrate (Sphagnum peat with limestone and fertilizer, Sphagnum peat, sawdust, straw‐manure, or mushroom compost), hourly sampling of inflow and outflow waters was conducted over a 19‐h (July 1990) and 24‐h period (May 1991). The chemical composition of the influent AMD was relatively stable over the duration of either sampling period. However, a striking diel pattern of shifts in the relative abundances of Fe2+ and Fe3+ in outflow waters was observed for both Sphagnum peat wetlands on both sampling dates, and for the straw‐manure and mushroom compost wetlands on the May 1991 sampling date. Prior to sunrise, 75 to 100% of the soluble Fe in outflow waters was Fe2+; prior to sunset, 62 to 88% of the soluble Fe was Fe3+. The documented did shifts in Fe3+ vs. Fe2+ abundance in outflow waters are greater in magnitude than any previously reported for a natural system and suggest that the cycling of Fe in AMD treatment wetlands is more dynamic than previously recognized and that standard daytime only sampling protocols are inadequate for assessing Fe retention‐release in AMD treatment wetlands.
Characterization and Settling of Solid Contaminants in Coal Mine Effluent
Authors: Zhou Z. , Bateman J. C. , Babchin A. , Bird G. W.
Published: July 2010

Groundwater and runoff water at surface coal mines are often contaminated with suspended solids and should be treated before it is discharged to surface water bodies. The suspended solids in the waste effluent of the Highvale mine, Alberta, Canada, are dominantly micron and submicron sized, dioctahedral smectite. They form stable colloidal suspensions in sodium bicarbonate solutions. Theoretical consideration suggests that the suspended smectite can be flocculated by divalent cations such as Ca2+. Experimental results show that even a small amount (2.7 mM) of gypsum can flocculate the system and cause clays to settle. Depending on the solution composition, up to 85% of the effluent volume can be reduced after 24 h settling. The clay settling rate is affected by both NaHCO3 and gypsum concentrations. Without gypsum addition, no settling occurs regardless of NaHCO3 concentrations (2 to 30 mM). At a fixed NaHCO3 concentration, clay settling rate increases with an increase in gypsum concentration. At a fixed gypsum concentration, the rate of clay settling decreases with an increase in NaHCO3 concentration. The initial settling rate (ISR) can be correlated to the equivalent fraction of Na+ on the clay surface (ENa) or the exchangeable sodium percentage (ESP) on the smectite surface. Linear regression of the experimental data gives an empirical equation ISR = −0.170 − 0.459 log(ENa) with a regression coefficient of 0.917, where ENa = ESP/100. The functional relation between solid settling rate and ESP can be useful in the design of sediment ponds for treatment of coal mine effluent.
Solubility of Cyanide in Contaminated Soils
Authors: Meeussen Johannes C. L. , Keizer Meindert G. , van Riemsdijk Willem H. , de Haan Frans A. M.
Published: July 2010

At more than 200 sites in the Netherlands, the soil is contaminated with cyanide as a result of industrial activities. The mobility of cyanide, which mainly occurs in the form of iron cyanide complexes [Fe(CN)63− + Fe(CN)64−], plays an important role in predicting the possible hazards for the environment and human health. Cyanide mobility was investigated by assessing data on cyanide concentrations in groundwater at contaminated sites, and by examination of three contaminated soils. High cyanide concentrations were found in the groundwater at sites with alkaline soils (pH ca. 7.5), whereas much lower concentrations were found in the groundwater with acidic soils (pH ca. 4). This agreed with the assumption that the behavior of cyanide in these contaminated soils is largely governed by the solubility of Prussian blue [Fe4(Fe(CN)6)3(s)], which is relatively insoluble under acidic conditions. In the acidic soils, the concentrations in the soil water appeared to be close to equilibrium with Prussian blue. In alkaline soils this precipitate is extremely soluble. The presence of this material here was possibly the result of slow dissolution kinetics. Precipitation of Prussian blue in acidic soils does not prevent dissolved iron cyanide concentrations from exceeding Dutch soil quality standards.
Nitrous Oxide Emission in Relation to Soil Factors at Low to Intermediate Moisture Levels
Authors: Robertson Kerstin
Published: July 2010

The objective of this study was to investigate the N2O emission from agricultural soils (14 field plots/38 measurements) as a function of environmental and soil factors‐clay content, soil temperature, soil moisture, total organic C and N, water‐soluble organic C, nitrate and ammonium concentrations, and pH‐that are considered of significance for N2O production in soil. Passible relations were tested by multiple linear regression and multivariate data analysis (PLS). A significant (P ≤ 0.05) relation (linear regression) was obtained only between N2O emission rates and NO−3 concentration in soil. However, the degree of explanation was low (R2 = 13%). If one field, with N2O emission rate several orders of magnitude higher than from the others, was excluded from the analysis a significant relation with the NH+4 concentration was obtained. In this case the degree of explanation was 17%. The results from the PLS analysis were similar to those from the regression analysis. If clay soils (>40% clay) were analyzed separately, NH+4 concentration and soil moisture accounted for 65% (P < 0.05) of the variability of the N2O emission rates. In the medium‐ and low‐clay soils no similar relationships were found. In conclusion, the obstacles caused by the complexity of the soil system and the different scales of measurement of N2O emission rates and soil factors probably obscured the possibility to relate the N2O emission rates to single or combinations of soil factors.
Solute Movement through Quartz‐Diorite Saprolite Containing Quartz Veins and Biological Macropores
Authors: Williams J. P. , Vepraskas M. J.
Published: July 2010

Saprolite is not permitted for use in on‐site wastewater disposal in North Carolina if quartz veins occur within 60 cm (2 ft) of the septic trench bottom because such features might transmit raw sewage quickly to groundwater. This study evaluated the time of travel (TOT) of a Br− solute through quartz veins in saprolite. Two 150 by 150 cm drainfields were constructed over saprolite containing quartz veins. Following saturation of the saprolite, a Br− tracer and dye were applied for a specific time period. The drainfields were then excavated to 90 cm, the dye pattern mapped, and soil samples collected for Br− analysis. There was no signilicant difference (α = 0.10) in depth of Br− penetration in saprolite with and without quartz veins. On the other hand, mean depth of Br− penetration increased from 14 cm for saprolite without macropores to 40 cm in saprolite with macropores (root channels) that extended to depths between 40 to 90 cm. A simple time of travel model predicted maximum depth of solute movement accurately where macropores were not present. To improve predictions for macropores, effective saturated hydraulic conductivities for saprolite with and without macropores were calculated and then used to estimate different rates of solute movement through saprolite when macropores were and were not present.
Nitrous Oxide Flux from Poultry‐Manured Erosion Plots and Grass Filters after Simulated Rain
Authors: Coyne M. S. , Gilfillen R. A. , Blevins R. L.
Published: July 2010

Adding carbon‐rich materials to fields, like manure, may enhance denitrification. Grass filters, which are used to trap surface runoff from these fields, may also provide a carbon‐rich environment that favors water infiltration and denitrification. Nitrous oxide (N2O) may be evolved these settings. It is a radiatively important trace gas and intermediate in the denitrification pathway and several other microbial processes. We measured N2O flux, after simulated rain, using a soil cover technique in poultry‐manured plots and grass filters receiving their runoff. Intact soil cores were used to relate the N2O flux to the denitrification potential of the plots. Nitrous oxide fluxes were smaller in grass filters than in manured plots, even though more denitrifying bacteria were present. The average N2O flux in the three most dynamic erosion plots was 755 µg N2O‐N m−2h−1, which was 39% of the maximal denitrification rate measured in acetylene‐blocked, NO−3‐amended soil cores. Nitrous oxide flux immediately after rainfall was greater than N2O flux measurements reported for similar agricultural settings.
Factors Controlling Throughfall Characteristics at a High Elevation Sierra Nevada Site, California
Authors: Brown Aaron D. , Lund L. J.
Published: July 2010

The composition of throughfall (TF) is influenced by wet and dry deposition on foliar surfaces and by chemical and biological interactions between rain and the foliage. The relative importance of these processes was investigated for TF collected in the summer months of 1985, 1986, and 1987 under three subalpine species, chinquapin (Chrysolepis sempervirens Hjelmqvist), western white pine (Pinus monticola Dougl.), and willow (Salix orestera Schneider), in the Emerald Lake Watershed, Sequoia National Park, California. The depth of rain and days since the last storm were used to predict net‐TF deposition in a multiple linear regression model. Dry deposition to needle surfaces had the greatest influence on western white pine TF composition. Net‐TF data for this species were used to estimate mean dry deposition rates for the summer. These data show that NH+4, NO−3, and SO2−4 dry deposition rates exceed median summer wet deposition rates by 1.5, 1.9, and 1.0 times, respectively. Willow foliage had the greatest influence on TF composition and western white pine the least. Estimated foliar release of cations and organic anions by willow during summer rain is a substantial fraction of annual wet deposition of those ions. Weak organic acid anions derived from foliar release are a significant component of net‐TF in all three species, particularly willow, where summer fluxes of organic acids were at least 51% of the total estimated annual wet deposition of organic anions.
Attainment and Effects Issues Regarding Alternative Secondary Ozone Air Quality Standards
Authors: Lee E. Henry , Hogsett William E. , Tingey David T.
Published: July 2010

The present secondary National Ambient Air Quality Standard (NAAQS) for O3, established in 1979, is based on limited information from a few field studies on vegetation and may not be protective of crop damage due to O3, alone or in combination with other pollutants. Considerable information from field studies conducted in the past decade indicate that there is poor functional correspondence between agricultural production and the air quality index of the current secondary NAAQS for O3. Because the current O3 NAAQS is based on data for extreme values of air quality, the index (or form) of the NAAQS ignores key features of hourly exposure data that are desirable and important to minimizing the risk of crop damage. Previous analyses of existing vegetation effects data indicate that exposure indices that cumulated the hourly O3 concentrations over the season, as well as preferentially weighted the higher concentrations appear to have major advantages over the mean and peak indices on the basis of statistical fits to the data. The peak‐weighted, cumulative indicators whose form and level are determined from crop studies were found useful in achieving a target production level that is higher than that of the current O3 NAAQS indicator with fewer violations. These alternative air quality indicators compare favorably with the current O3 NAAQS in terms of protection against adverse welfare effects and air quality properties to better identify areas having adequate air quality.
Ozone and Carbon Dioxide Effects on Spider Mites in White Clover and Peanut
Authors: Heagle A. S. , Brandenburg R. L. , Burns J. C. , Miller J. E.
Published: July 2010

Effects of O3 and/or elevated CO2 on two‐spotted spider mites (Tetranychus urticae Koch) grown on an O3‐sensitive and an O3‐resistant clone of white clover (Trifolium repens L.) were measured in greenhouse and field experiments. Peanut (Arachis hypogeae L.) ‘NC‐9’ was used in one greenhouse study with O3. In field studies, O3 treatments were charcoal filtered air (CF), nonfiltered air (NF), and two NF treatments with O3 added for 12 h d−1 at proportions of ≈ 1.25 and 1.50 times the ambient O3 concentration. In greenhouse studies, constant amounts of O3 were added to CF for 6 h d−1 to achieve mean concentrations ranging from 5 to 100 nL L−1. For the greenhouse O3 × CO2 experiment, CO2 concentrations were ambient and approximately twice‐ambient for 24 h d−1. Plants were exposed to O3 and/or CO2 for ≈7 d before infestation with mites; daily exposures continued for 14 to 28 d to allow reproduction for at least two generations. Leaves were sampled to count eggs, larvae, nymphs, and adults. Ozone caused more chlorosis and necrosis on the O3‐sensitive clover clone (NC‐S) than on the O3‐resistant clone (NC‐R). Carbon dioxide enrichment increased shoot growth of both clones by ≈33%. Statistical analyses indicated significant O3 effects in some experiments and nonsignificant O3 effects in others. A trend toward increased mite populations with increased O3 occurred, however, on NC‐S in all trials. No consistent trends occurred with NC‐R. With peanut, a significant linear increase in mite population occurred with increased O3. Carbon dioxide enrichment increased the rate of population increase on both clover clones, but more so on NC‐R. At 22 to 28 d after infestation, the total population in the twice‐ambient CO2 treatment was 65% greater than in the ambient treatment for NC‐R and 22% greater than in the ambient treatment for NC‐S. There were no statistically significant interactive effects between CO2 and O3 on mite population growth. The apparent clone effects on mite population response to O3 and CO2 strongly suggest that responses were mediated through the host plants.
Clinoptilolite Zeolite Influence on Nitrate Leaching and Nitrogen Use Efficiency in Simulated Sand Based Golf Greens
Authors: Huang Z. T. , Petrovic A. M.
Published: July 2010

The trend in golf greens construction during the past three decades has been towards putting greens with at least 90% sand and limited amounts of silt, clay, or organic matter. High sand based systems typically have low cation‐exchange capacity (CEC) and large saturated hydraulic conductivities (>30 cm h−1), thus, are prone to NO−3 leaching and possibly contribute to ground or surface water contamination. Clinoptilolite zeolite (CZ) has a high CEC (160 cmol kg−1), a large affinity for NH+4 ions and water molecules that may reduce N leaching on sand based putting greens. The impact of CZ amendment of sand putting greens on N leaching and N uptake by creeping bentgrass (Agrostis stolonifera L.) was determined. The lysimeter method was used for growing creeping bentgrass in the greenhouse to determine NO−3 and NH+4 leaching potential and fertilizer N use efficiency. Four N levels (0, 98, 196, and 293 kg NH+4‐N ha−1) and two media, sand‐CZ mix (9:1, w/w), and unamended sand, were included as treatments. Sand plus CZ had a lowered concentration of NO−3 and NH+4 in leachate while doubling the water retention capacity and increasing CEC 200 fold. The greatest reduction of N leaching was found from lysimeters amended with CZ at the highest N rate. Nitrate and NH+4 leaching was 86 and 99% lower, respectively, than the unamended sand lysimeters. The N fertilizer use efficiency was improved by 16 to 22% with the addition of CZ to sand, depending on N application rate. Amendment of sandy rooting media with clinoptilolite promoted better fertilizer N uptake efficiency and reduced N leaching from a highly leachable soil.
Plutonium‐239 + 240 and Americium‐241 in Soils East of Rocky Flats, Colorado
Authors: Litaor M. Iggy , Thompson M. L. , Barth G. R. , Molzer P. C.
Published: July 2010

Soils east of the Rocky Flats (RF) near Golden, CO, were contaminated with Pu‐239 + 240 and Am‐241 as a result of past waste‐storage practices. The physicochemical parameters that govern the actinides distribution in the soil are poorly understood. Twenty‐six soil pits at various distances and directions from a contaminated site at RF were excavated, sampled, and analyzed for actinide activities as well as selected physical, chemical, and mineralogical attributes. Plutonium‐239 + 240 and Am‐241 activities in the soils ranged from 164 280 Bq/kg to 0.0037 Bq/kg, decreasing with distance from the source. More than 90% of the Pu‐239 + 240 and Am‐241 activities were confined to the upper 12 cm of the soil, regardless of the soil characteristics, or distance and direction from the source. Evidence of preferential transport in macropores formed along decayed root channels was observed in four soil pits and had translocated Pu‐239 + 240 to a depth of 90 cm. This transport mechanism increased by a factor of 30 the level of Pu‐239 + 240 activity at this depth. Earthworm activity is probably important in the redistribution of actinides in the upper 40 cm of many of the soils investigated. Planning of future remedial activities at RF should consider the findings of this contaminant‐transport study.
The Effect of Technetium‐99 and Environmental Conditions on Soybean Physiology
Authors: Degenkolb Stephanie J. , Neel James W. , Papin Patrick J.
Published: July 2010

Technetium‐99 is considered a long‐term risk of nuclear energy because it has a long half‐life, mass 99 is produced at a high yield during nuclear fission, and Tc‐99 is taken up readily by aquatic and terrestrial organisms. Plants are an important intermediate of Tc‐99 food chain transfer to animals and humans. The present study investigated adenosine triphosphate (ATP), photosynthesis and structural responses of intact soybean seedlings [Glycine max (L.) Merr. cv. Williams] to micromolar amounts of Tc‐99 under different ambient light levels. Adenosine triphosphate was measured directly in primary leaf extract after 6 d of exposure to Tc at varying concentrations (up to 5 µM Tc‐99). The results indicated that under full light conditions (320 µmol photon m−2 s−1), soybean primary leaves contained nanomolar concentrations of ATP almost twice as high as for untreated plants. With a reduction of light intensity by 50%, primary leaf pertechnetate uptake and leaf ATP content were reduced regardless of Tc‐99 exposure levels. Gas exchange measurements with a Li‐Cor 6200 Portable Photosynthesis system indicated a significant decline of photosynthetic rate and a higher internal CO2 accumulation under full light conditions, while stomatal conductance decreased as a function of Tc‐99 concentration. Several possible mechanisms of Tc interaction with chloroplast ultrastructure are proposed. A hypothesis related to the metabolic behavior of Tc in higher plants is presented.
Effect of pH on the Distribution and Occurrence of Aquatic Fungi in Six West Virginia Mountain Streams
Authors: Dubey Tara , Stephenson Steven L. , Edwards Pamela J.
Published: July 2010

Aquatic fungi in six streams located on or near the Fernow Experimental Forest in Tucker County, West Virginia, were studied during the 1991 and 1992 growing seasons. Water pH was >5.9 in three of the streams, while the others were more acidic, with average pH = 4.2, 3.9, and 3.2. Sampling methods included (i) isolating conidia from stream water using membrane filtration, (ii) placing bags containing leaves of four tree species in the streams for periods ranging from 2 to 16 wk, and (iii) baiting the streams with various types of other organic material. The stream mycoflora included 156 taxa (47 zoosporic fungi [chytridiaceous fungi and water molds] and 109 hyphomycetes [60 Ingoldian and 49 non‐Ingoldian forms]). Twenty‐seven taxa of zoosporic fungi were recorded from the stream with the highest pH (7.9); only 15 to 18 taxa were collected from other streams. Based on conidia filtered from water samples, the number of taxa of hyphomycetes generally was lower in streams with low pH; however, fewest conidia were recorded at the two extremes of the pH gradient. Northern red oak (Quercus rubra L.) leaves were colonized by an average of 16.0 hyphomycete taxa in the six streams, sugar maple (Acer saccharum Marsh.) by 15.3 taxa, and mixed red maple (A. rubrum L.), and American beech (Fagus grandifolia Ehrh.) by 15.2 taxa. For all three types of leaves, more taxa generally were present in the less acidic streams and fewer in the more acidic streams.
Uptake of Cesium‐137 by Crops from Contaminated Soils
Authors: Demirel H. , Özer I. , Çelenk I. , Halitligil M. B. , Özmen A.
Published: July 2010

The Turkish tea crop was contaminated following the Chernobyl nuclear accident. Finding ways to dispose of the contaminated tea (Camellia sinensis L.) without damaging the environment was the goal of this research conducted at the Turkish Atomic Energy Authority (TAEA). In this study, an investigation was made of 137Cs activities of the plants and the ratios of transfer of 137Cs activity to plants when the contaminated tea was applied to the soil. Experiments were conducted in the field and in pots under greenhouse conditions. The activities of the tea applied in the field ranged from 12 500 to 72 800 Bq/m2, whereas this activity was constant at 8000 Bq/pot in the greenhouse experiment. The transfer of 137Cs from soil to the plants was between 0.037 and 1.057% for wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), corn (Zea mays indentata Sturt), bean (Phaseolus vulgaris L.), lettuce (Lactuca sativa L.), and grass (Lolium perenne L.). The ratio of the transfer of 137Cs activity to plants increased as the activity 137Cs in tea applied to soil was increased. The activity in the plants increased due to increased uptake of 137Cs by plants.
Radionuclide Transport above a Near‐Surface Water Table: I. An Automated Lysimeter Facility for Near‐Surface Contaminant Transport Studies
Authors: Burne S. , Wheater H. S. , Butler A. P. , Johnston P. M. , Wadey P. , Shaw G. , Bell J. N. B.
Published: July 2010

The design and operation is described of a field lysimeter experimental facility to investigate the migration in vegetated soils of contaminants from near‐surface groundwater. Automatic control systems in auxiliary buffer tanks were used to maintain fixed water table depths of 35 and 65 cm, respectively. A cocktail of radionuclides, consisting of 137Cs, 109Cd, 60Co, 22Na, 36Cl, and 99Tc, was introduced to an inert substrate below the water table and recirculated to provide uniform groundwater concentrations. Continuous monitoring was undertaken of water imports/exports, the vertical distribution of soil water potential and soil temperature, and climatological variables. Regular measurements were made of soil moisture content, crop root distribution, crop height and leaf area index, as well as radiochemical concentrations in groundwater and the control system. Intensive radiochemical analyses were made on soil cores and crop. Hydrological results for 1990 and 1991 show a strong contrast in climatic conditions between the 2 yr. Radiochemical data are presented in an accompanying paper.
Radionuclide Transport above a Near‐Surface Water Table: II. Vertical Distribution of Gamma Activities within Soil Profiles in Relation to Wheat Rooting Density and Soil‐to‐Plant Transfers
Authors: Wadey P. , Shaw G. , Bell J. N. , Minski M. J.
Published: July 2010

Radiochemical results are described from a replicated field lysimeter experiment to investigate the upward migration of radionuclides in vegetated soils above near‐surface contaminated groundwater. Water tables were maintained at depths of 35 cm (shallow) and 65 cm (deep), below which a cocktail of radionuclides including 137Cs, 109Cd, 60Co, and 22Na was introduced. Results of the vertical migration and plant uptake are presented from the first 2 yr of an ongoing experiment with winter wheat (Triticum aestivum L.). As expected, 137Cs, 60Co, and 109Cd proved to be highly sorbed to the soil solid phase in the regions of the water table and exhibited a lesser degree of up‐profile transport than 22Na in shallow lysimeters. However, in deep lysimeters, 137Cs and 60Cs appeared to be preferentially accumulated at the soil surface; a biological translocation mechanism is postulated to account for this observation. It was clear from a statistical analysis of vertical radionuclide distributions that, in physicochemical terms, 22Na was the most mobile of the radionuclides studied. The distribution of this radionuclide within the soil profiles showed a significant shift between the two growth seasons examined, whereas the distributions of the other radionuclides remained static between 1990 and 1991. Each radionuclide showed a distinct and consistent distribution pattern throughout the crop tissues, although the differences in tissue specific activities for individual radionuclides were found to be nonsignificant with the exception of 22Na. Soil‐to‐plant transfer factors (TFw) were calculated using mean soil specific activities weighted according to the fractional abundance of roots and measured soil specific activities in discrete soil layers. The TFw values were significantly lower in 1991 than in 1990 in both shallow and deep lysimeters; it is postulated that this was due to a much greater fiux of water through the crop in 1990, which was characterized by high evapotranspiration rates and a substantial negative water budget. In both years, TFw values were, in general, significantly higher for deep lysimeters than for shallow lysimeters. This is thought to provide evidence of enhanced radionuclide absorption by the relatively small fraction of roots in the vicinity of the deeper water table.
Usefulness of Selenium for the Reduction of Mercury Emmission from Crematoria
Authors: Hogland William K. H.
Published: July 2010

In Sweden there are no legislative regulations regarding mercury in fluegas emission from crematoria. The crematoria do not have treatment facilities to reduce mercury emissions, although they are the third highest emission source of mercury in Sweden. Included in this paper are the data on mercury emission during cremations with and without the addition of selenium for the reduction of mercury emission. Tests were carried out during 22 cremations. The use of selenium gave emission reductions of 80 to 85% in stack gases, and 20 to 50% in the emission peaks.
Fluometuron Sorption and Transport in Dundee Soil
Authors: Gaston L. A. , Locke M. A.
Published: July 2010

The mobility of a synthetic organic compound in soil is affected by degradation and sorption reactions. Sorption is often a nonequilibrium process, leading to greater mobility and increased potential for contamination of shallow groundwater. Accordingly, this study was undertaken to examine sorption kinetics of the herbicide fluometuron [N,N‐dimethyl‐N′‐[3‐(trifluoromethyl)‐phenyl]urea] in Dundee silty clay loam (fine‐silty, mixed, thermic Aeric Ochraqualfs), a common soil in the Mississippi Delta. Batch experiments indicated sorption equilibrium was achieved by 72 h contact time. Other data suggested little degradation of fluometuron within this time. The approach to equilibrium was characterized by an initially very rapid reaction, followed by a slower rate of sorption. This behavior could be equally well described by either a nonlinear two‐site equilibrium/kinetic or equilibrium/diffusion model. Reaction parameters determined from the batch experiments were further validated by use in a transport model to predict fluometuron movement in this soil. Within parameter uncertainty, the two‐site equilibrium/kinetic model gave accurate predictions of fluometuron mobility. Explicitly modeling time‐dependent sorption as a diffusion process offered minor improvement in transport predictions.
Sewage Sludge Application Effects on Runoff Water Quality in a Semiarid Grassland
Authors: Harris‐Pierce R. L. , Redente E. F. , Barbarick K. A.
Published: July 2010

One of the concerns of land application of sewage sludge (also referred to as biosolids) to rangeland is its effect on the amount and quality of runoff water. In this study, we applied three treatments consisting of 0, 22, and 41 Mg ha−1 of municipal sewage sludge to Larim gravelly sandy loam (Ustollic Arginstoll) and Altvan sandy loam (Aridic Argiustoll) soils in paired plots on two slope gradients (8 and 15%). We used a one‐time application of simulated rainfall for 30 rain at a rate of 100 mm h−1 and collected and analyzed the runoff. We found greater sediment loads in the runoff on 8% slopes due to the larger amount of line soil particles (<2‐mm diam.) in the soil compared with 15% slopes. As sludge rate increased from 0 to 41 Mg ha−1, decreasing concentrations (P < 0.05) of Al (0.55–0.26 mg L−1) and Fe (0.29–0.15 mg L−1) in unfiltered samples of runoff water resulted. Increasing sludge rate from 0 to 41 Mg ha−1 increased (P ≤ 0.05) sediment (0.5–1.0 g L−1), organic N (0.5–25 mg L−1), NH4‐N (0.5–76 mg L−1), and total Na (6.6–10.4 mg L−1), K (4.8–24.8 mg L−1), B (0.016–0.70 mg L−1), P (0.4–15.8 mg L−1), Cu (0.007–0.62 mg L−1), Ni (0.006–0.50 mg L−1), and Mo (0.005–0.52 mg L−1). Concentrations of all measured constituents in the runoff water were less than USEPA standards for drinking water and recommended levels for livestock water.
Effects of Acidification on Bryophyte Communities in West Virginia Mountain Streams
Authors: Stephenson Steven L. , Studlar Susan Moyle , McQuattie Carolyn J. , Edwards Pamela J.
Published: July 2010

Bryophytes (mosses and liverworts) are often more responsive to water chemistry changes than are vascular plants. In this study, the relationships of bryophyte communities to stream pH and water chemistry were studied, using six streams on or near the Fernow Experimental Forest in Tucker County, West Virginia. Streams were surveyed with line transects using stratified random sampling. Bryophyte communities, based on species composition and structure, fell into three groups, corresponding to basic, moderately acidic, and very acidic stream water. For streams with sandstone beds, species diversity declined with decreasing pH, and no bryophytes were present at pH 3.15. The dominant species in moderately acidic to highly acidic streams is Scapania undulata, a species found to have exceptional tolerance to high acidity and toxic metal levels in Europe and Japan. Scapania undulata was transplanted from a stream with a pH of 5.97 to one with a pH of 3.15. In 3 mo, ultrastructural damage was observed. Acidity (pH) probably was not the only factor involved in controlling species composition and cell ultrastructure, since the two most acidic streams are subject to acid mine drainage and have very high concentrations of dissolved solids, particularly SO4 and Al. Other trace metals commonly associated with acidic surface waters also may have contributed to the differences in species composition.
Soil Phosphorus as a Potential Nonpoint Source for Elevated Stream Phosphorus Levels
Authors: Abrams M. M. , Jarrell W. M.
Published: July 2010

Eroded soils, as a potential nonpoint P source, have come under scrutiny, particularly in agricultural watersheds. Surface water and groundwater in the Tualatin River Basin (TRB) of Northwestern Oregon have maximum concentrations of 2.1 and 2.6 mg P/L, respectively. We hypothesized that TRB soils are a major P source in the basin because of their high native soil P concentrations and soil P adsorption characteristics. We sampled eight soil series from both lowland and upland positions in the TRB, with both andic and nonandic mineralogy. All soils sampled had high total P concentrations (660–2304 mg P/kg soil). High average extractable P (Bray P1, 74 mg P/kg soil, and ammonium bicarbonate, 35.7 mg P/kg soil) concentrations were found primarily in lowland, nonandic soils. There was no significant difference between P sorption maxima; however, P affinity was significantly higher in upland soils (0.19 L/mg P) than in lowland soils (0.04 L/mg P). Upland, andic soils, due to their erosion potential and high TP levels (average of 1889 mg P/kg soil), could be a P source for surface waters. Lowland, nonandic soils, due to their high extractable P concentrations and lower P sorption affinity, could be a source for both surface and groundwater. Thus, all soils studied, comprising approximately 50% of TRB soils, are potential nonpoint P sources in this watershed, indicating that native soil P is a potential source of nonpoint P pollution.