bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uptake and Translocation Studies in Balsam Fir Seedlings with 54Mn and 65Zn Radioisotopes Applied to Soil Surfaces
Authors: Lin Z.‐Q. , Barthakur N. N. , Schuepp P. H. , Kennedy G. G. 
Published: July 2010

AbstractPathways of heavy metal deposits in balsam fir [Abies balsamea (L) Mill.] seedlings were investigated by simultaneously applying 54Mn and 65Zn radioisotopes on soil surfaces. Downward movement of 54Mn and 65Zn in soils was documented to the 14 to 16 cm depth 70 d after application. One‐year‐old needles and 3‐yr‐old twigs concentrated more radioisotopes than older needles and younger twigs, respectively, with the sample specific activity (kBq kg−1) of 54Mn 5 to 10 times higher than that of 65Zn. The activity in seedlings on the 70th d of the experiment was 5.2% of the total remaining activity for 54Mn (6290 kBq) and 2.6 % for 65Zn (6031 kBq). The distribution of 54Mn in the seedling was 31% in roots, 31% in twigs, 26% in stems, and 12% in needles, while roots retained 86% of 65Zn. No appreciable migration of elements from internal tissues to epicuticular wax layers was found when shoots were washed in chloroform. The maximum leaching ratio was below 0.5 and 1.0% for 54Mn and 65Zn, respectively, when shoots were washed in simulated acid rain for 5 min.
The Effects of Substrate Type, Surface Water Depth, and Flow Rate on Manganese Retention in Mesocosm Wetlands
Authors: Stark Lloyd R. , Williams Frederick M. , Wenerick William R. , Wuest Paul J. , Urban Christopher 
Published: July 2010

AbstractA wetland mesocosm experiment was conducted to determine the effects on Mn retention of substrate type, surface water depth, and flow rate. The main objective of this experiment was to determine if sustained Mn retention could be accomplished under the specific experimental treatments, to recommend design parameters for the construction of field wetland systems for Mn treatment. Crushed limestone was clearly superior to spent mushroom substrate (SMS) with respect to Mn retention. The presence of a layer of free surface water detracted from Mn treatment, while lower flow rates enhanced Mn treatment. Sustained Mn retention was achieved using crushed limestone as the substrate coupled with an absence of surface free water, when inlet water had a pH of 7.0 and no appreciable Fe. Substrate metal extractions indicated that most of the Mn was retained as oxide‐bound Mn (72%), with most (88%) of the Mn retained at the surface of the wetland. Limestone “wetlands” are therefore recommended in the treatment of Mn in neutral‐pH mine water containing no Fe.
Transport Times of Dissolved Inorganic Phosphate in Soils
Authors: Gerritse R. G. 
Published: July 2010

AbstractAn empirically based equation is proposed for calculating the decrease, relative to water, of the mobility of phosphate in columns of soil, with increasing distance travelled and decreasing flow rate. The equation requires experimental determination of two parameters: the ratio of added phosphate in adsorbed and mobile phases of a soil, 1 d after an addition, and a coefficient determined by the decrease in rate of adsorption of phosphate with time. Breakthrough times of phosphate were obtained from leaching step increases in the concentration of dissolved phosphate through saturated columns of soil for a wide range of concentrations, rates of flow, soils, and column lengths. Calculated and experimentally observed mobilities of phosphate, relative to water, appear to fit a log‐linear relationship. This relationship allows prediction of mobilities of phosphate in soils at rates of flow and for distances travelled that are representative of field conditions.
Sorption and Degradation of Bentazon in Conventional‐ and No‐till Dundee Soil
Authors: Gaston L. A. , Locke M. A. , Zablotowicz R. M. 
Published: July 2010

AbstractHerbicides applied postemergence, such as bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide], reach the soil surface due to incomplete interception by the plant canopy or foliar washoff. Thus, potential off‐site transport is influenced by sorption equilibrium/kinetics and degradation. This study addressed the effects of tillage practice on the sorption and degradation of 14C‐labeled bentazon using Dundee silt loam soil (fine‐silty, mixed, thermic, Aeric Ochraqualf) taken from the conventional‐till (CT) and no‐till (NT) treatments of a tillage experiment without bentazon exposure for more than 3 yr. Data were generated for surface and subsurface samples. The kinetics of bentazon sorption in CT surface soil were rapid, with apparent equilibrium achieved in 1 h. Furthermore, the extent of sorption was low and the equilibrium distribution of solution and sorbed bentazon could be described using a linear model. Differences in soil organic matter between tillage treatments and with depth were not reflected in sorption behavior. However, degradation was more rapid in the CT surface soil than in the corresponding NT soil and more rapid in surface than subsurface soil. In all cases, degradation proceeded with little mineralization (<3%) over the 22‐d duration of these experiments, however, the amount of unextractable 14C (80:20, CH3OH:0.01 M CaCl2 extractant) increased with time. Analysis of the extractable fraction by HPLC gave no evidence of metabolites. Bentazon degradation was approximated using simple first‐order kinetics, however, the data were best described using two‐compartment models. Development of a bound 14C fraction, despite limited bentazon sorption and no evidence for extractable metabolites, suggested that metabolic intermediates exhibit high sorption affinity.
Methane Oxidation in a Neutral Landfill Cover Soil: Influence of Moisture Content, Temperature, and Nitrogen‐Turnover
Authors: Boeckx Pascal , Van Cleemput Oswald 
Published: July 2010

AbstractWell‐managed, aerated cover soils can have a mitigating effect on methane emission from landfills. The influence of moisture content, soil temperature, and N on the methane uptake capacity of a neutral landfill cover soil was examined. A soil moisture content of 15% w/w gave the maximum CH4 oxidation rate (2.36 ng CH4 h−1 g−1 soil). When wetter, CH4 consumption was slower (e.g., 1.6 ng CH4 h−1 g−1 at 30% w/w) because of a limited gas diffusion. At lower soil moisture, microbial activity was reduced and consequently the oxidation capacity decreased (e.g., 0.84 ng CH4 h−1 g−1 at 5% w/w). Optimum temperature was between 25 and 30°C. The calculated activation energy of the CH4 oxidation was 56.5 kJ K−1 mol−1. After NH+4 addition, a negative linear correlation was found between the methane oxidation rate and the nitrous oxide flux (R2 = 0.96, Y1 = 2.7 − 0.44 × Y2). Addition of NO−3 had no significant effect on CH4 oxidation. The effect of organic residue amendments depended on their C/N ratios. Crop residues with a high C/N ratio (wheat [Triticum sativum L.] and maize [Zea mays L.] straw) stimulated N‐immobilization and did not affect the methane‐oxidizing capacity. On the other hand, addition of crop residues with low C/N ratios (potato [Solanum tuberosum L.] and sugar beet [Beta vulgaris cv. Altissima] leaves) stimulated N‐mineralization, resulting in a strong inhibition of the methane oxidation.
Dissipation of Polycyclic Aromatic Hydrocarbons in the Rhizosphere
Authors: Reilley K. A. , Banks M. K. , Schwab A. P. 
Published: July 2010

AbstractResidual contamination of soils with polycyclic aromatic hydrocarbons (PAHs) is an environmental problem for many industrial operations, including the petroleum industry. Petroleum sludges high in PAHs are often treated through landfarming in which soil is mixed with sludge, kept bare of vegetation, tilled, and fertilized to encourage microbial degradation of the contaminants. However, recent research has demonstrated that plants can enhance the dissipation of organic pollutants in the immediate environment of the root (rhizosphere). The use of vegetation to increase the degradation of two common PAH contaminants, anthracene and pyrene, was investigated in a greenhouse experiment. Target compounds were added to a contaminated, landfarmed soil and a similar uncontaminated soil at a rate of 100 mg/kg. Four plant species were grown in each soil; after 4, 8, 16, and 24 wk of plant growth, soil and plant material were sampled and analyzed for the target PAHs. Vegetated soils had significantly lower concentrations of the PAHs than the unvegetated soils, ranging from 30 to 44% more degradation in the vegetated soils. Enhanced biological degradation in the rhizosphere appears to be a mechanism of dissipation. Leaching, plant uptake, abiotic degradation, mineralization to CO2, and irreversible sorption were shown to be insignificant in the overall mass balance of the target compounds. The presence of plants may enhance the clean‐up of PAH‐contaminated soils during in situ remediation.Joint contribution from the Engineering Exp. Stn. and Kansas Agric. Exp. Stn.
Characterization of Pesticide Sorption and Degradation in Macropore Linings and Soil Horizons of Thatuna Silt Loam
Authors: Mallawatantri A. P. , McConkey B. G. , Mulla D. J. 
Published: July 2010

AbstractThe effect of changes in soil characteristics with depth because of soil horizonation and macroporosity on fate of pesticides is poorly understood. Soil from the surface A horizons (0–0.65 m), albic E horizons (1.05–1.35 m), argillic Bt horizons (1.4–3.5 m), and surface linings of macropores in the argillic horizons (Bt‐M, 1.4–3.5 m) of a Thatuna silt loam (fine‐silty, mixed, mesic Xeric Argialbolls) were characterized for their physical, chemical, and microbiological effects on adsorption, desorption, and mineralization of 2,4‐D, carbofuran, and metribuzin. Organic carbon (OC) contents decreased for soil materials in the order A (1.22%) > Bt‐M (0.36%) > Bt (0.25%) = E (0.20%), and were correlated with the number of soil microbial colony forming units (log CFU) that decreased in the order A (7.4) > Bt‐M (6.1) > E (5.6) = Bt (5.4). Percent macroporosity (pores 2–5 mm diam.) decreased in the order Bt (1.1%) > A (0.7%) > E (0.6%), which is the same order for decreases in saturated hydraulic conductivity (log m s−1), namely; Bt (−6) > A (−6.2) > E (−7.0). Freundlich adsorption partition coefficients (Kf− L kg−1) for A horizon soil with 2,4‐D (1.1), carbofuran (1.0), and metribuzin (1.6) were significantly greater than in subsurface E or Bt matrix material. Sorption Kf values in macropore linings with carbofuran (1.1) and metribuzin (2.0) were comparable to or greater than their respective values of 1.0 and 1.6 in A horizon material. Percent mineralization in the A horizon after 139 d for [U‐14C] 2,4‐D (81.8%) and carbofuran (14.7%) was significantly greater than in all subsurface soil materials. Mineralization in Bt macropore linings for 2,4‐D (17.0%) and carbofuran (8.4%) was significantly greater than in other subsurface soil materials. Mineralization of [U‐14C] metribuzin was negligible (<3%) in all soil materials after 139 d.
Accumulation of Airborne Elements from Vehicles in Transplanted Lichens in Urban Sites
Authors: Garty J. , Kauppi M. , Kauppi A. 
Published: July 2010

AbstractThe objective of the current study is to compare the short‐term accumulation capacity of two epiphytic lichens characterized by a different type of thallus. The lichens Hypogymnia physodes (L.) Nyl. and Usnea hirta (L.) Weber em. Mot. were transplanted either to the vicinity of streets of low volume and slow traffic or to the vicinity of a highway in the city of Oulu, N. Finland, for a period of 45 d. Eleven elements were analyzed before and after transplantation. The two lichen species were found to possess a similar accumulating capacity for K and Mn. Hypogynmia physodes manifests a higher accumumulating capacity than U. hirta for Na, Fe, and Cu, whereas the more sensitive lichen U. hirta exhibits a higher accumulating capacity for Mg, despite a higher primary concentration of these elements in the thallus of H. physodes. Our findings show a relative high concentration of K, Fe, Mg, Zn, Mn, Pb, and Cu in thalli of H. physodes and Mg, Zn, Pb, Cu, and Cd in U. hirta in material transplanted to streets of low volume and slow traffic, over and above the concentration found in thalli retrieved from the vicinity of the highway. This may be explained by the higher rate of abrasion of car engines running idle near traffic lights and by the lesser ventilation near the close‐clustered streets of the inner city.
Mineralization of Hydrocarbons in Soils under Decreasing Oxygen Availability
Authors: Freijer Jan I. 
Published: July 2010

AbstractTechniques for remediation of soils contaminated with hydrocarbons (HCs) can be improved when the factors that control the decomposition rate are identified. In this study, the effect of O2 availability on the decomposition rate of hydrocarbons in soils is examined. A kinetic second‐order model with the O2 concentration and biomass concentration as rate‐controlling variables is used to quantify HC decomposition, O2 consumption, and CO2 production. Concentrations of O2 and CO2 are calculated analytically as a function of time in a three‐phase closed system. These calculations are compared with measurements of repetitive O2‐depletion experiments in closed jars containing a layer of soil contaminated with HCs. About 80% of the HC decrease could be attributed to mineralization, while the other 20% was assumed to be converted into biomass and metabolites. After calibration, model calculations agree with the experimental results, which makes the concept of O2 concentration and biomass concentration as rate‐controlling variables plausible. The parameter values that are obtained by calibration have a clear biochemical significance. It is concluded that attention has to be paid to the O2 supply in closed‐jar experiments to avoid erroneous interpretation of the results.
Historical Changes in Connecticut Lakes Over a 55‐Year Period
Authors: Siver Peter A. , Canavan Richard W. , Field Cathryn K. , Marsicano Laurence J. , Lott Anne‐Marie 
Published: July 2010

AbstractChanges in the chemical and physical conditions of 42 Connecticut lakes are compared between three time periods, the late 1930s, the mid‐ to late 1970s and the early 1990s. On average, lakes have decreased in Secchi disk depth by 1.2 m and doubled in total phosphorus concentration, many in a unidirectional manner. As a result, the suite of lakes can be characterized as having shifted from an oligo‐mesotrophic condition (1930s) to a late mesotrophic condition (1990s). Since the 1970s, lakes have increased in base cation concentrations an average of 70 μeq/L, many as the result of an increase in sodium. Increases in sodium were generally coupled with increases in chloride ions. Many of the lakes positioned in watersheds that have become more residential since the 1930s and/or 1970s have also increased in alkalinity. Despite the overall increase in base cations, chloride, and alkalinity, about 25% of the waterbodies that have remained situated in primarily forested watersheds in crystalline rock regions have decreased in total cation concentrations; about half of these lakes have also significantly decreased in alkalinity since the 1930s. The changes are discussed in relation to the degree of urbanization of the watersheds over the same time period.
Statewide GIS/Census Data Assessment of Nitrogen Loadings from Septic Systems in Pennsylvania
Authors: Nizeyimana Egide , Petersen G. W. , Anderson M. C. , Evans B. M. , Hamlett J. M. , Baumer G. M. 
Published: July 2010

AbstractDespite the role of septic systems in surface and groundwater N contamination, little statewide information has been collected or is available on the amount of N pollution from septic systems. This study reports on the development of a methodology to assess N released from septic systems at the state level and presents results of N loading estimates in Pennsylvania watersheds. The methodology describes steps to compute N loadings per watershed unit area within a Geographic Information System (GIS) framework based on (i) information on septic systems and population from the 1990 Census data, (ii) soil limitations to proper purification of septic system effluent acquired from the State Soil Geographic (STATSGO) data base, and (iii) daily N estimates per capita in septic system effluent from the literature. In this study, watersheds were ranked from 1 to 104 and grouped into three significantly different classes (high, medium, and low) according to their N loadings. The N loading ranges corresponding to these classes were 1.16 to 0.71 kg ha−1 yr−1, 0.66 to 0.41 kg ha−1 yr−1, and 0.38 to 0.03 kg ha−1 yr−1, respectively. High‐producing watersheds were generally located in suburbs adjacent to larger metropolitan areas. The watershed ranking, groups, and N loading results provided by this methodology can be combined with similar information from agriculture, atmospheric deposition, etc. in the attempt to account for all sources of nonpoint N pollution in a state or region.
Chemical Composition of Municipal Leaf Waste and Hand‐Collected Urban Leaf Litter
Authors: Heckman J. R. , Kluchinski D. 
Published: July 2010

AbstractMunicipal leaf waste delivered to New Jersey farms was sampled to evaluate its chemical composition and suitability for land application. Freshly fallen leaf litter samples were also collected and analyzed from seven different urban landscape tree species. Municipal leaf waste data from 100 samples in this study was summarized using frequency distributions to characterize its variability in composition. The chemical composition of municipal leaf waste was found to be quite variable. The minimum‐maximum and median values were as follows: (g kg−1) C, 363 to 516, 480; N, 6.6 to 16.2, 9.4; P, 0.2 to 2.9, 1.0; K, 0.9 to 8.8, 3.6; Ca 1.3 to 30.4, 17.3; Mg, 0.2 to 4.6, 2.4; S, 0.1 to 2.1, 1.1; (mg kg−1) B, 7 to 72, 38; Fe, 46 to 9800, 733; Al, 58 to 10554, 602; Mn, 19 to 1845, 406; Zn, 22 to 392, 67; Na, 36 to 325, 90; Cl, 68 to 3995, 1083; Cu, 2.8 to 31.5, 8.1; Co, 0.9 to 10.9, 2.7; Cd, 0.1 to 6.8, 1.3; Pb, 3 to 400, 18; Ni, 1 to 58, 5; Cr, 0.9 to 35.1, 6.6; Ba, 4.2 to 142.0, 49.4. Although municipal leaf waste contains significant amounts of valuable plant nutrients, the high C/N ratio (range: 26.8–71.8; median: 48.5) suggests that heavy applications are likely to cause immobilization of available soil N. Concentrations of Fe, Al, Pb, and Cd were generally higher and more variable in municipal leaf waste than in hand‐collected leaf litter. This suggests that contamination with urban soil during collection contributes to elevated Pb and Cd concentrations in municipal leaf waste. Given careful attention to N‐fertilizer practice, municipal leaf waste is a suitable material for application to farm land.
Resuspension and Diffusive Flux of Nitrogen and Phosphorus in a Hypereutrophic Lake
Authors: Reddy K. R. , Fisher M. M. , Ivanoff D. 
Published: July 2010

AbstractBottom sediments in shallow lakes can play a major role in releasing nutrients to the overlying water column during wind induced sediment resuspension or by constant flux due to diffusion. Internal nutrient loads due to these processes may be equal to or higher than external loads. Laboratory and field experiments were conducted on Lake Apopka, a shallow, hypereutrophic subtropical lake located in central Florida. Ammonium (NH+4) and soluble reactive P (SRP) flux during sediment resuspension were measured under laboratory conditions using intact sediment cores. Ammonium N and SRP flux due soley to diffusion were assessed using in situ porewater concentrations. Average diffusive flux from sediment to the overlying water was estimated to be 25 mg NH4‐N m−2 d−1 and 1 mg P m−1 d−2. Resuspension fluxes of NH+4 and SRP were higher than diffusive flux. Soluble reactive P profiles of porewater showed distinct profile differentiation, with the surface 0 to 8 cm sediment depth acting as a P‐depletion zone, and the underlying sediment displaying steep gradients in porewater SRP. These results suggest that dissolved NH+4 and SRP transport from the surface 8 cm of sediment was due to sediment resuspension, while below this depth, upward mobility of NH+4 and SRP was regulated by diffusion. Although dissolved N and P flux is upwards (from sediment to water column), during extended periods (annual cycle) the lake is functioning as a net sink for N and P by transforming inorganic pools of nutrients into organic forms and depositing them on the sediment surface.
Well Water Quality, Well Vulnerability, and Agricultural Contamination in the Midwestern United States
Authors: Richards R. Peter , Baker David B. , Creamer Nancy L. , Kramer Jack W. , Ewing D. Ellen , Merryfield Barbara J. , Wallrabenstein Laura K. 
Published: July 2010

AbstractThe Heidelberg College Cooperative Private Well Testing Program is designed to evaluate water quality in private rural wells. The program inexpensively provides large datasets that reflect relationships between well contamination and associated factors, and support local groundwater protection and education programs. Nearly 35 000 wells have been tested in Ohio, Indiana, Illinois, West Virginia, and Kentucky. Median nitrate concentration was 0.07 mg/L; 3.4% of wells exceeded the drinking water standard of 10 mg/L; 23% exceeded 1 mg/L. Triazines were detected in 4.9% of 12 362 samples; the atrazine MCL of 3.0 µg/L was exceeded in 0.1% of samples. Acetanilides were detected in 9.7% of 10 967 samples; 1.1% exceeded the alachlor MCL of 2.0 µg/L. Many acetanilide detections, and most higher concentrations, are due to an alachlor breakdown product and involve little or no alachlor. Information supplied by well owners was used to examine the impact of cultural and geological factors on well water quality. Concentrations are higher in wells that are shallower, older, dug, or driven; located close to cropland, feedlots, or chemical mixing sites; or located in sandy soils. Where wells combine the most vulnerable alternative for two or three factors, the probability of contamination increases dramatically. Mapping sometimes reveals spatial patterns of contamination that reflect geological influences. River valley aquifers, sandy soils with high water tables, karst areas, and reef structures with surficial expressions are all reflected in county maps of the data.