bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential Nitrification and Denitrification on Different Surfaces in a Constructed Treatment Wetland
Authors: Bastviken Sofia Kallner , Eriksson Peder G. , Martins Irene , Neto João M. , Leonardson Lars , Tonderski Karin 
Published: June 2010

ABSTRACTImproved understanding of the importance of different surfaces in supporting attached nitrifying and denitrifying bacteria is essential if we are to optimize the N removal capacity of treatment wetlands. The aim of this study was therefore to examine the nitrifying and denitrifying capacity of different surfaces in a constructed treatment wetland and to assess the relative importance of these surfaces for overall N removal in the wetland. Intact sediment cores, old pine and spruce twigs, shoots of Eurasian watermilfoil (Myriophyllum spicatum L.), and filamentous macro‐algae were collected in July and November 1999 in two basins of the wetland system. One of the basins had been constructed on land that contained lots of wood debris, particularly twigs of coniferous trees. Potential nitrification was measured using the isotope‐dilution technique, and potential denitrification was determined using the acetylene‐inhibition technique in laboratory microcosm incubations. Nitrification rates were highest on the twigs. These rates were three and 100 times higher than in the sediment and on Eurasian watermilfoil, respectively. Potential denitrification rates were highest in the sediment. These rates were three times higher than on the twigs and 40 times higher than on Eurasian watermilfoil. The distribution of denitrifying bacteria was most likely due to the availability of organic material, with higher denitrification rates in the sediment than on surfaces in the water column. Our results indicate that denitrification, and particularly nitrification, in treatment wetlands could be significantly increased by addition of surfaces such as twigs.
Soil Microbial Communities Associated with Bt and Non‐Bt Corn in Three Soils
Authors: Blackwood Christopher B. , Buyer Jeffrey S. 
Published: June 2010

ABSTRACTThe effects of expression of Cry endotoxin by Bt corn (transgenic corn engineered to express Bacillus thuringiensis toxin) on soil microbial community structure were assessed in a growth chamber experiment. Two lines of transgenic corn expressing different Cry endotoxins were compared with their respective non‐transgenic isolines in three soil types with differing textures. Phospholipid fatty acid (PLFA) profiles from bulk soil and community‐level physiological profiles (CLPP) from the rhizosphere community were used to assess community structure. Differences in PLFA profiles due to soil type were significant, accounting for 73% of the total variability in the dataset. Differences in bacterial and fungal CLPP profiles due to soil type were statistically significant, but probably not biologically important, accounting for 6.3 and 3.8% of the total variability, respectively. Neither expression of Cry endotoxin nor corn line had a significant effect on microbial profiles, except in the high‐clay soil where both factors significantly affected bacterial CLPP profiles (accounting for 6.6 and 6.1% of the variability in that soil, respectively). Expression of Cry endotoxin also significantly reduced the presence of eukaryotic PLFA biomarker in bulk soils, although it is unclear which groups of eukaryotes were affected. We conclude that the effects of transgenic Bt corn in this short‐term experiment are small, and longer‐term investigations are necessary.
Plant and Soil Responses to Biosolids Application following Forest Fire
Authors: Meyer V. F. , Redente E. F. , Barbarick K. A. , Brobst R. B. , Paschke M. W. , Miller A. L. 
Published: June 2010

ABSTRACTSoil stability and revegetation is a great concern following forest wildfires. Biosolids application might enhance revegetation efforts and enhance soil stability. In May 1997, we applied Metro Wastewater Reclamation District (Denver, CO, USA) composted biosolids at rates of 0, 5, 10, 20, 40, and 80 Mg ha−1 to a severely burned, previously forested site near Buffalo Creek, CO to improve soil C and N levels and help establish eight native, seeded grasses. The soils on the site belong to the Sphinx series (sandy‐skeletal, mixed, frigid, shallow Typic Ustorthents). Vegetation and soils data were collected for four years following treatment. During the four years following treatment, total plant biomass ranged from approximately 50 to 230 g m−2 and generally increased with increasing biosolids application. The percentage of bare ground ranged from 4 to 58% and generally decreased with increasing biosolids rate. Higher rates of biosolids application were associated with increased concentrations of N, P, and Zn in tissue of the dominant plant species, streambank wheatgrass [Elymus lanceolatus (Scribn. & J.G. Sm) Gould subsp. lanceolatus], relative to the unamended, unfertilized control. At two months following biosolids application (1997), total soil C and N at soil depths of 0 to 7.5, 7.5 to 15, and 15 to 30 cm showed significant (P < 0.05) linear increases (r2 > 0.88) as biosolids rate increased. The surface soil layer also showed this effect one year after application (1998). For Years 2 through 4 (1999–2001) following treatment, soil C and N levels declined but did not show consistent trends. The increase in productivity and cover resulting from the use of biosolids can aid in the rehabilitation of wildfire sites and reduce soil erosion in ecosystems similar to the Buffalo Creek area.
Denitrification Potential in Relation to Lithology in Five Headwater Riparian Zones
Authors: Hill Alan R. , Vidon Philippe G. F. , Langat Jackson 
Published: June 2010

ABSTRACTThe influence of riparian zone lithology on nitrate dynamics is poorly understood. We investigated vertical variations in potential denitrification activity in relation to the lithology and stratigraphy of five headwater riparian zones on glacial till and outwash landscapes in southern Ontario, Canada. Conductive coarse sand and gravel layers occurred in four of the five riparian areas. These layers were thin and did not extend to the field–riparian perimeter in some riparian zones, which limited their role as conduits for ground water flow. We found widespread organic‐rich layers at depths ranging from 40 to 300 cm that resulted from natural floodplain processes and the burial of surface soils by rapid valley‐bottom sedimentation after European settlement. The organic matter content of these layers varied considerably from 2 to 5% (relic channel deposit) to 5 to 21% (buried soils) and 30 to 62% (buried peat). Denitrification potential (DNP) was measured by the acetylene block method in sediment slurries amended with nitrate. The highest DNP rates were usually found in the top 0‐ to 15‐cm surface soil layer in all riparian zones. However, a steep decline in DNP with depth was often absent and high DNP activity occurred in the deep organic‐rich layers. Water table variations in 2000–2002 indicated that ground water only interacted frequently with riparian surface soils between late March and May, whereas subsurface organic layers that sustain considerable DNP were below the water table for most of the year. These results suggest that riparian zones with organic deposits at depth may effectively remove nitrate from ground water even when the water table does not interact with organic‐rich surface soil horizons.
Enhanced Desorption of Herbicides Sorbed on Soils by Addition of Triton X‐100
Authors: Rodríguez‐Cruz M. S. , Sánchez‐Martín M. J. , Sánchez‐Camazano M. 
Published: June 2010

ABSTRACTA study of the desorption of atrazine (1‐chloro‐3‐ethylamino‐5‐isopropylamino‐2,4,6‐triazine) and linuron [1‐methoxy‐1‐methyl‐3‐(3,4‐dichlorophenyl)urea] adsorbed on soils with different organic matter (OM) and clay contents was conducted in water and in the presence of the non‐ionic surfactant Triton X‐100 at different concentrations. The aim was to gain insight into soil characteristics in surfactant‐enhanced desorption of herbicides from soils. Adsorption and desorption isotherms in water, in all Triton X‐100 solutions for atrazine, and in solutions of 0.75 times the critical micelle concentration (cmc) and 1.50cmc for linuron fit the Freundlich equation. All desorption isotherms showed hysteresis. Hysteresis coefficients decreased for linuron and increased or decreased for atrazine in Triton X‐100 solutions. These variations were dependent on surfactant concentration and soil OM and clay contents. In the soil–water–surfactant system desorption of linuron from all soils was always greater than in the soil–water system but for atrazine this only occurred at concentrations higher than 50cmc. For the highest Triton X‐100 concentration (100cmc), the desorption of the most hydrophobic herbicide (linuron) was increased more than 18‐fold with respect to water in soil with an OM content of 10.3% while the atrazine desorption was increased 3‐fold. The effect of Triton X‐100 on the desorption of both herbicides was very low in soil with a high clay content. The results indicate the potential use of Triton X‐100 to facilitate the desorption of these herbicides from soil to the water–surfactant system. They also contribute to better understanding of the interactions of different molecules and surfaces in the complex soil–herbicide–water surfactant system.
Phosphorus Availability for Plant Uptake in a Phosphorus‐Enriched Noncalcareous Sandy Soil
Authors: Koopmans G. F. , Chardon W. J. , Ehlert P. A. I. , Dolfing J. , Suurs R. A. A. , Oenema O. , van Riemsdijk W. H. 
Published: June 2010

ABSTRACTMining soil phosphorus (i.e., harvesting P taken up from the soil by a crop grown without external P addition) has been proposed as a possible management strategy for P‐enriched soils to decrease the risk of P leaching. We performed a pot experiment in a greenhouse where grass was cropped on a P‐enriched noncalcareous sandy soil at zero P application over a period of 978 d. We determined the long‐term availability of soil P and evaluated the effectiveness of mining soil P to decrease P in different pools. There were two treatments: soil layers in the pots of either 5 or 10 cm thickness. Soils were analyzed at various stages of the experiment. Phosphorus in soil solution and the total pool of sorbed P were estimated using 1:10 (w/v) 0.01 M CaCl2 extracts and acid ammonium oxalate (Pox), respectively. A desorption isotherm was constructed, which described the relationship between P in soil solution and the total pool of sorbed P for the soils of the 5‐ and 10‐cm treatments. The Langmuir equation gave a very good description of the isotherm. In the long‐term, 65% of Pox in the initial soil can be removed by plant uptake, as was calculated from the Langmuir equation and a critical P concentration in soil solution at which P uptake can just be maintained. Thus, Pox may be largely plant available. From the strong nonlinearity of the desorption isotherm, it can be understood why the relative decrease of the P concentration in the CaCl2 extracts was much larger than the relative decrease of Pox Mining soil P decreased the P concentration in soil solution effectively and, therefore, risk of P leaching from our P‐enriched soil.
Use of Stream Chemistry for Monitoring Acidic Deposition Effects in the Adirondack Region of New York
Authors: Lawrence Gregory B. , Momen Bahram , Roy Karen M. 
Published: June 2010

ABSTRACTAcid‐neutralizing capacity (ANC) and pH were measured weekly from October 1991 through September 2001 in three streams in the western Adirondack Mountain region of New York to identify trends in stream chemistry that might be related to changes in acidic deposition. A decreasing trend in atmospheric deposition of SO42− was observed within the region over the 10‐yr period, although most of the decrease occurred between 1991 and 1995. Both ANC and pH were inversely related to flow in all streams; therefore, a trend analysis was conducted on (i) the measured values of ANC and pH and (ii) the residuals of the concentration–discharge relations. In Buck Creek, ANC increased significantly (p < 0.05) over the 10 yr, but the residuals of ANC showed no trend (p > 0.10). In Bald Mountain Brook, ANC and residuals of ANC increased significantly (p < 0.01), although the trend was diatonic—a distinct decrease from 1991 to 1996 was followed by a distinct increase from 1996 to 2001. In Fly Pond outlet, ANC and residuals of ANC increased over the study period (p < 0.01), although the trend of the residuals resulted largely from an abrupt increase in 1997. In general, the trends observed in the three streams are similar to results presented for Adirondack lakes in a previous study, and are consistent with the declining trend in atmospheric deposition for this region, although the observed trends in ANC and pH in streams could not be directly attributed to the trends in acidic deposition.
Phosphorus Removal in a Wetland Constructed on Former Arable Land
Authors: Liikanen Anu , Puustinen Markku , Koskiaho Jari , Väisänen Tero , Martikainen Pertti , Hartikainen Helinä 
Published: June 2010

ABSTRACTPhosphorus in surface runoff water may cause eutrophication of recipient water. This study clarifies the mechanisms of P removal in the wetland of Hovi, Finland, constructed on arable land in 1998. Before the construction, the surface soil (removed in the construction) and subsoil (the current wetland bottom) were analyzed for Al and Fe oxides (Alox and Feox) reactive in P sorption, and for the distribution of P between various pools as well as for P exchange properties. Retention of P from runoff water within the wetland was studied from 1999 to 2001 in situ and factors affecting the P removal (O2 availability and P concentration in water) were investigated in a laboratory microcosm. The processes taking place in the wetland diminished by 68% the total P load and by 49% the dissolved reactive P load. Desorption–sorption tests indicated that without removal of the surface soil, there would have been a risk of the wetland being a source of P, since the equilibrium P concentration of the soil removed was high compared with the mean P concentration of the inflowing water. The subsoil contained less P and high amounts of reactive oxides, which could bind P. Evidently, the P sorption by Alox played an important role in a first phase removal of P, since the wetland retained P efficiently even under anoxic conditions, where Fe tends to be reduced. Fine‐textured, mineral soil on the bottom of the wetland (subsoil of the former arable land) seemed to be very efficient in retaining P from agricultural runoff.
Ammonia Volatilization from Surface‐Applied Poultry Litter under Conservation Tillage Management Practices
Authors: Sharpe R. R. , Schomberg H. H. , Harper L. A. , Endale D. M. , Jenkins M. B. , Franzluebbers A. J. 
Published: June 2010

ABSTRACTLand application of poultry litter can provide essential plant nutrients for crop production, but ammonia (NH3) volatilization from the litter can be detrimental to the environment. A multiseason study was conducted to quantify NH3volatilization rates from surface‐applied poultry litter under no‐till and paraplowed conservation tillage managements. Litter was applied to supply 90 to 140 kg N ha−1Evaluation of NH3volatilization was determined using gas concentrations and the flux‐gradient gas transport technique using the momentum balance transport coefficient. Ammonia fluxes ranged from 3.3 to 24% of the total N applied during the winter and summer, respectively. Ammonia volatilization was rapid immediately after litter application and stopped within 7 to 8 d. Precipitation of 17 mm essentially halted volatilization, probably by transporting litter N into the soil matrix. Application of poultry to conservation‐tilled cropland immediately before rainfall events would reduce N losses to the atmosphere but could also increase NO3leaching and runoff to streams and rivers.
Heavy Metal Accumulation by the Halophyte Species Mediterranean Saltbush
Authors: Lutts Stanley , Lefèvre Isabelle , Delpérée Christine , Kivits Sandrine , Dechamps Caroline , Robledo Antonio , Correal Enrique 
Published: June 2010

ABSTRACTTo identify Cd‐ and Zn‐accumulating plants exhibiting a high growth rate, seeds from the halophyte species Mediterranean saltbush (Atriplex halimus L.) were collected on a heavy‐metal‐contaminated site in southeastern Spain (Llano del Beal, Cartagena). Seedlings from this ecotype were exposed for 3 wk to 0.1 mM Cd or Zn in a nutrient solution in a fully controlled environment. All plants remained alive and no significant growth inhibition was recorded until the end of the experiment. Mean Cd and Zn accumulation in aerial parts was 830 and 440 mg kg−1, respectively, and the rate of metal translocation even increased with the duration of stress exposure. Resistance to heavy metals in this species may be partly linked to precipitation of Cd in oxalate crystals in the stems. A Cd‐induced decrease in glutathione concentration also suggests that phytochelatins overproduction may occur in these conditions. We conclude that Mediterranean saltbush, which is able to produce up to 5 Mg dry matter ha−1 yr−1, may be an effective species for phytoextraction and should be tested for this purpose in field conditions.
Sorption of Sulfonamide Pharmaceutical Antibiotics on Whole Soils and Particle‐Size Fractions
Authors: Thiele‐Bruhn S. , Seibicke T. , Schulten H.‐R. , Leinweber P. 
Published: June 2010

ABSTRACTResidues of pharmaceutical antibiotics are found in the environment, whose fate and effects are governed by sorption. Thus, the extent and mechanisms of the soil sorption of p‐aminobenzoic acid and five sulfonamide antibiotics (sulfanilamide, sulfadimidine, sulfadiazine, sulfadimethoxine, and sulfapyridine) were investigated using topsoils of fertilized and unfertilized Chernozem and their organic–mineral particle‐size fractions. Freundlich adsorption coefficients (Kf) ranged from 0.5 to 6.5. Adsorption increased with aromaticity and electronegativity of functional groups attached to the sulfonyl–phenylamine core. Adsorption to soil and particle‐size fractions increased in the sequence: coarse silt < whole soil < medium silt < sand < clay < fine silt and was influenced by pH. Sorption nonlinearity (1/n ≤ 0.76) indicated specific interactions with functional groups of soil organic matter (SOM). Phenolic and carboxylic groups, N‐heterocyclic compounds, and lignin decomposition products were tentatively assigned as preferred binding sites using statistical analysis of pyrolysis–mass spectra and adsorption coefficients. Adsorption of sulfonamides to mineral soil colloids was weaker and resulted in a stronger desorption from clay‐size fractions. Moreover, steric accessibility of organic–mineral complexes in clay‐size fractions was significantly reduced. With a quantitative structure–property relationship (QSPR) model, combining the organic carbon concentration, the sulfonamides' chromatographic capacity factor (k′), and nondissociated species concentration (CFa), distribution coefficients (Kd) were estimated with a cross‐validated regression coefficient Q2 = 0.71. Modeling and molecular mechanics calculations of antibiotic–SOM complexes showed preferred site‐specific sorption via hydrogen bonds and van der Waals interactions. Distinct chemical structural properties, such as aromaticity and van der Waals volumes, correlated with the sorption data.
Polycyclic Aromatic Hydrocarbon Release from a Soil Matrix in the In Vitro Gastrointestinal Tract
Authors: Van de Wiele Tom Richard , Verstraete Willy , Siciliano Steven Douglas 
Published: June 2010

ABSTRACTSoil ingestion is an important exposure route by which immobile soil contaminants enter the human body. We assessed polycyclic aromatic hydrocarbon (PAH) release from a contaminated soil, containing 49 mg PAH kg−1, using a SHIME (Simulator of the Human Intestinal Microbial Ecosystem) reactor comprising the stomach, duodenal, and colon compartments. Polycyclic aromatic hydrocarbon release was defined as that fraction remaining in the digest supernatant after centrifugation for 5 min at 1500 × g The PAH release in the stomach digest was only 0.44% of the total PAH present in soil, resulting in PAH concentrations of 23 μg PAH L−1 chyme. The lower PAH releases in duodenum (0.13%) and colon (0.30%) digests, compared with the stomach digest, were thought to be attributed to combined complexation and precipitation with bile salts, dissolved organic matter, or colon microbiota. We studied these complexation processes in an intestinal suspension more in depth by preparing mixtures of 9‐anthracenepropionic acid, a Bacillus subtilis culture, and cholin as model compounds for PAHs, organic matter, and bile salts, respectively. Bile salts or organic matter in the aqueous phase initially enhance PAH desorption from soil. However, desorbed PAHs may form large aggregates with bile and organic matter, lowering the freely dissolved PAH fraction in the supernatant. Using the model compounds, mathematical equations were developed and validated to predict PAH complexation processes in the gastrointestinal tract. Contaminant release and subsequent complexation in the gut is an important prerequisite to intestinal absorption and thus bioavailability of that contaminant. The data from this research may help in understanding the processes to which PAHs are subjected in the gastrointestinal tract, before intestinal absorption.
Relationship between Soil Test Phosphorus and Phosphorus in Runoff
Authors: Schroeder Philip D. , Radcliffe David E. , Cabrera Miguel L. , Belew Carolee D. 
Published: June 2010

ABSTRACTPhosphorus loss in runoff from agricultural fields has been identified as an important contributor to eutrophication. The objective of this research was to determine the relationship between phosphorus (P) in runoff from a benchmark soil (Cecil sandy loam; fine, kaolinitic, thermic Typic Kanhapludult) and Mehlich III–, deionized water–, and Fe2O3–extractable soil P, and degree of phosphorus saturation (DPS). Additionally, the value of including other soil properties in P loss prediction equations was evaluated. Simulated rainfall was applied (75 mm h−1) to 54 1‐m2 plots installed on six fields with different soil test phosphorus (STP) levels. Runoff was collected in its entirety for 30 min and analyzed for total P and dissolved reactive phosphorus (DRP). Soil samples were collected from 0‐ to 2‐, 0‐ to 5‐, and 0‐ to 10‐cm depths. The strongest correlation for total P and DRP occurred with DPS (r2 = 0.72). Normalizing DRP by runoff depth resulted in improved correlation with deionized water–extractable P for the 0‐ to 10‐cm sampling depth (r2 = 0.81). The STP levels were not different among sampling depths and analysis of the regression equations revealed that soil sampling depth had no effect on the relationship between STP and P in runoff. For all forms of P in runoff and STP measures, the relationship between STP and runoff P was much stronger when the data were split into groups based on the ratio of oxalate‐extractable Fe to Al. For all forms of P in runoff and all STP methods, R2 increased with the inclusion of oxalate‐extractable Al and Fe in the regression equation. The results of this study indicate that inclusion of site‐specific information about soil Al and Fe content can improve the relationship between STP and runoff P.