bluuebunny/crossref_metadata_2025 huggingface dataset:
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

A 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

Mining 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

Acid‐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

Phosphorus 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

Land 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

To 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

Residues 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

Soil 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

Phosphorus 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.
Release ofCryptosporidiumandGiardiafrom Dairy Cattle Manure
Authors: Schijven Jack F. , Bradford Scott A. , Yang Shihui
Published: June 2010

Various physical factors affecting the release rate of naturally occurringCryptosporidium parvumoocysts andGiardia duodenaliscysts from dairy manure disks to sprinkled water were studied. The investigated factors included temperature (5 or 23°C), manure type (calf manure, a 50% calf and 50% cow manure mixture, and a 10% calf and 90% cow manure mixture), and water application method (mist or drip) and flow rate. Effluent concentrations of manure and (oo)cysts were always several orders of magnitude below their initial concentration in the manure, decreased gradually, and exhibited persistent concentration tailing. Release of manure and (oo)cysts were found to be related by a constant factor, the so‐called release efficiency of (oo)cysts. A previously developed (oo)cyst release model that included these release efficiencies provided a satisfactory simulation of the observed release. An effect of temperature on the release of manure and (oo)cysts was not apparent. The manure and (oo)cyst release rates from cow manure decreased faster than those from calf manure, and (oo)cyst release efficiencies from cow manure were higher than those from calf manure. In comparison with mist application, dripping water resulted in higher release rates of manure and (oo)cysts and in higher (oo)cyst release efficiencies due to the increased mechanical forces associated with droplet impact. Mist application at a higher flow rate resulted in faster release, but did not affect the (oo)cyst release efficiencies. The data and modeling approach described herein provide insight and an enhanced ability to describe the influence of physical factors on (oo)cyst release.
Nitrogen Availability from Composts for Humid Region Perennial Grass and Legume–Grass Forage Production
Authors: Lynch D. H. , Voroney R. P. , Warman P. R.
Published: June 2010

Perennial forages may be ideally suited for fertilization with slow N release amendments such as composts, but difficulties in predicting N supply from composts have limited their routine use in forage production. A field study was conducted to compare the yield and protein content of a binary legume–grass forage mixture and a grass monocrop cut twice annually, when fertilized with diverse composts. In all three years from 1998–2000, timothy (Phleum pratenseL.)–red clover (Trifolium pratenseL.) and timothy swards were fertilized with ammonium nitrate (AN) at up to 150 and 300 kg N ha−1yr−1, respectively. Organic amendments, applied at up to 600 kg N ha−1yr−1in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC), or sewage sludge (SSLC), plus liquid dairy manure (DM). Treatments DM at 150 kg N ha−1yr−1and CSC at 600 kg N ha−1yr−1produced cumulative timothy yields matching those obtained for inorganic fertilizer. Apparent nitrogen recovery (ANR) ranged from 0.65% (SSLC) to 15.1% (DMC) for composts, compared with 29.4% (DM) and 36.5% (AN). The legume component (approximately 30%) of the binary mixture acted as an effective “N buffer” maintaining forage yield and protein content consistently higher, and within a narrower range, across all treatments. Integrating compost utilization into livestock systems that use legume–grass mixtures may reduce the risk of large excesses or deficits of N, moderate against potential losses in crop yield and quality, and by accommodating lower application rates of composts, reduce soil P and K accumulation.
Quantification of the Effect of Fumigation on Short‐ and Long‐Term Nitrogen Mineralization and Nitrification in Different Soils
Authors: De Neve Stefaan , Csitári Gabor , Salomez Joost , Hofman Georges
Published: June 2010

The effect of soil fumigation on N mineralization and nitrification needs to be better quantified to optimize N fertilizer advice and predict NO−3 concentrations in crops and NO−3 leaching risks. Seven soils representing a range in soil texture and organic matter contents were fumigated with Cyanamid DD 95 (a mixture of 1,3‐dichloropropane and 1,3‐dichloropropene). After removal of the fumigant, the fumigated soils and unfumigated controls were incubated for 20 wk and N mineralization and nitrification were monitored by destructive sampling. The average short‐term N mineralization rates (ks) were significantly larger in the fumigated than in the unfumigated soils (P = 0.025), but the differences in ks between fumigated and unfumigated soils could not be related to soil properties. The average long‐term N mineralization rates (kl) were slightly larger in the fumigated soils but the difference with the unfumigated soils was not significant. Again, the differences in kl values could not be related to soil properties. Nitrification was inhibited completely for at least 3 wk in all soils, and an effect on nitrification could be observed up to 17 wk in one soil. An S‐shaped function was fitted to the nitrification data corrected for N mineralization, and both the rate constant (γ) and the time at which maximum nitrification was reached (tmax) were strongly correlated to soil pH. However, since no correlations were found between the effect of fumigation on N mineralization and soil properties, taking into account the effects of fumigation in fertilizer advice and in the prediction of NO−3 leaching risks will need further research.
Phosphorus Loss and Runoff Characteristics in Three Adjacent Agricultural Watersheds with Claypan Soils
Authors: Udawatta Ranjith P. , Motavalli Peter P. , Garrett Harold E.
Published: June 2010

Effects of precipitation, runoff, and management on total phosphorus (TP) loss from three adjacent, row‐cropped watersheds in the claypan region of northeastern Missouri were examined from 1991 to 1997 to understand factors affecting P loss in watersheds dominated by claypan soils. Runoff samples from each individual runoff event were analyzed for TP and sediment concentration. The annual TP loss ranged from 0.29 to 3.59 kg ha−1 with a mean of 1.36 kg ha−1 across all the watersheds during the study period. Significantly higher loss of TP from the watersheds was observed during the fallow period. Multiple small runoff events or several large runoff events contributed to loss of TP from the watersheds. Total P loss in 1993, a year with above‐normal precipitation, accounted for 30% of the total TP loss observed over seven years. The five largest runoff events out of a total of 66 events observed over seven years accounted for 27% of the TP loss. The five largest sediment losses were responsible for 24% of the TP loss over seven years. Runoff volume and sediment loss explained 64 to 73% and 47 to 58% of the variation in TP loss on watersheds during the study. Flow duration and maximum flow accounted for 49 and 66% of TP loss, respectively. The results of this study suggest that management practices that reduce runoff volume, flow duration, maximum flow, and sediment loss, and that maintain a suitable vegetative cover throughout the year could lower P loss in claypan soils.
Effects of Mineral Surfaces on Pyrene Partitioning to Well‐Characterized Humic Substances
Authors: Hur Jin , Schlautman Mark A.
Published: June 2010

Mineral surfaces can alter the ability of humic substances (HS) to bind hydrophobic organic contaminants. In this study, complete adsorption (i.e., to avoid HS adsorptive fractionation effects) of a small subset of well‐characterized terrestrial and aquatic HS on kaolinite and hematite significantly changed their subsequent organic carbon–normalized partition coefficients Kadsoc for pyrene relative to their original respective dissolved organic carbon–normalized partition coefficients Kdisoc Parallel experiments with ultrafiltration (UF) fractions obtained from purified Aldrich humic acid (PAHA) (Aldrich Chemical, Milwaukee, WI) gave similar results. The heterogeneity among the PAHA UF fractions was examined via their mineral surface adsorption characteristics and their subsequent ability to bind pyrene. As expected, variations in maximum adsorption densities (qmax), Langmuir adsorption constants (Kq), and pyrene Kadsoc values were observed among the PAHA UF fractions. However, general trends of qmax, Kq, and pyrene log Kadsoc values for the PAHA UF fractions versus the logarithm of their weight‐average molecular weights (MWw) did not typically match the corresponding trends obtained with the four aquatic and terrestrial HS. In general, an ideal mixture competitive adsorption model gave reasonable predictions for PAHA sorption to kaolinite and hematite based on their corresponding UF isotherm parameters. Ideal mixture predictions of pyrene partitioning to adsorbed PAHA from the corresponding UF fraction results were better for kaolinite versus hematite, indicating that the underlying mineral surface can alter the effects of HS heterogeneity on hydrophobic organic contaminant sorption.
Nitrate Leaching to Subsurface Drains as Affected by Drain Spacing and Changes in Crop Production System
Authors: Kladivko E. J. , Frankenberger J. R. , Jaynes D. B. , Meek D. W. , Jenkinson B. J. , Fausey N. R.
Published: June 2010

Subsurface drainage is a beneficial water management practice in poorly drained soils but may also contribute substantial nitrate N loads to surface waters. This paper summarizes results from a 15‐yr drainage study in Indiana that includes three drain spacings (5, 10, and 20 m) managed for 10 yr with chisel tillage in monoculture corn (Zea mays L.) and currently managed under a no‐till corn–soybean [Glycine max (L.) Merr.] rotation. In general, drainflow and nitrate N losses per unit area were greater for narrower drain spacings. Drainflow removed between 8 and 26% of annual rainfall, depending on year and drain spacing. Nitrate N concentrations in drainflow did not vary with spacing, but concentrations have significantly decreased from the beginning to the end of the experiment. Flow‐weighted mean concentrations decreased from 28 mg L−1 in the 1986–1988 period to 8 mg L−1 in the 1997–1999 period. The reduction in concentration was due to both a reduction in fertilizer N rates over the study period and to the addition of a winter cover crop as a “trap crop” after corn in the corn–soybean rotation. Annual nitrate N loads decreased from 38 kg ha−1 in the 1986–1988 period to 15 kg ha−1 in the 1997–1999 period. Most of the nitrate N losses occurred during the fallow season, when most of the drainage occurred. Results of this study underscore the necessity of long‐term research on different soil types and in different climatic zones, to develop appropriate management strategies for both economic crop production and protection of environmental quality.
Rate of Fall‐Applied Liquid Swine Manure
Authors: Gessel P. D. , Hansen N. C. , Moncrief J. F. , Schmitt M. A.
Published: June 2010

Reducing the delivery of phosphorus (P) from land‐applied manure to surface water is a priority in many watersheds. Manure application rate can be controlled to manage the risk of water quality degradation. The objective of this study was to evaluate how application rate of liquid swine manure affects the transport of sediment and P in runoff. Liquid swine manure was land‐applied and incorporated annually in the fall to runoff plots near Morris, Minnesota. Manure application rates were 0, 0.5, 1, and 2 times the rate recommended to supply P for a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Runoff volume, sediment, and P transport from snowmelt and rainfall were monitored for 3 yr. When manure was applied at the highest rate, runoff volume and sediment loss were less than the control plots without manure. Reductions in runoff volume and soil loss were not observed for spring runoff when frozen soil conditions controlled infiltration rates. The reduced runoff and sediment loss from manure amended soils compensated for addition of P, resulting in similar runoff losses of total P among manure application rates. However, losses of dissolved P increased with increasing manure application rate for runoff during the spring thaw period. Evaluation of water quality risks from fall‐applied manure should contrast the potential P losses in snowmelt runoff with the potential that incorporated manure may reduce runoff and soil loss during the summer.
Comparison of Three Enzyme Immunoassays for Measuring 17β‐Estradiol in Flushed Dairy Manure Wastewater
Authors: Hanselman Travis A. , Graetz Donald A. , Wilkie Ann C.
Published: June 2010

Natural steroidal estrogens are an environmental concern because low nanogram per liter concentrations in water can adversely affect aquatic vertebrate species by disrupting the normal function of their endocrine systems. There is a critical need to accurately measure estrogens in dairy wastes, a potential source of estrogens such as 17β‐estradiol, to assess the risk of estrogen contamination of agricultural drainage waters resulting from land application. Commercially available enzyme immunoassay (EIA) kits have been used for measuring 17β‐estradiol in livestock manure, but it is not known if different EIAs provide similar results. We compared three EIAs by measuring 17β‐estradiol in two samples of flushed dairy manure wastewater (FDMW). The measured concentrations of 17β‐estradiol in FDMW differed according to the immunoassay used. The differences were attributed to a matrix interference associated with coextracted humic substances. Future research should develop methods that enable routine measurement of 17β‐estradiol in livestock wastes by more conclusive analytical techniques such as gas chromatography–mass spectrometry.
Changes in the Nature of Sewage Sludge Organic Matter During a Twenty‐One‐Month Incubation
Authors: Smernik Ronald J. , Oliver Ian W. , McLaughlin Mike J.
Published: June 2010

Six sewage sludges from five sewage treatment plants in Australia were incubated for up to 21 months. Carbon losses at the end of the 21‐mo incubation varied substantially. The remaining organic matter was isolated by treatment with hydrofluoric acid (HF) and characterized using a range of solid‐state 13C nuclear magnetic resonance (NMR) spectroscopic techniques. By every measure (signal distribution in cross polarization [CP] and Bloch decay [BD] spectra, carbon NMR observability determined by spin counting, and the appearance of proton spin relaxation editing subspectra), the chemical composition of the residual organic matter appeared to be little different from that of the original sludges, even for those sludges that experienced the greatest carbon losses. Importantly, these NMR properties distinguish sewage sludge organic matter from soil organic matter. Thus, it should be possible to follow the decomposition of sewage sludge organic matter applied to soils in the field using solid‐state 13C NMR spectroscopy.
Near‐ and Mid‐Infrared Diffuse Reflectance Spectroscopy for Measuring Soil Metal Content
Authors: Siebielec Grzegorz , McCarty Gregory W. , Stuczynski Tomasz I. , Reeves James B.
Published: June 2010

Rapid and nondestructive methods such as diffuse reflectance infrared spectroscopy provide potentially useful alternatives to time‐consuming chemical methods of soil metal analysis. To assess the utility of near‐infrared reflectance spectroscopy (NIRS) and diffuse mid‐infrared reflectance spectroscopy (DRIFTS) for soil metal determination, 70 soil samples from the metal mining region of Tarnowskie Gory (Upper Silesia, Poland) were analyzed by both chemical and spectroscopic methods. Soils represented a wide range of pH (4.0–8.0), total carbon (5.1–73.2 g kg−1), and textural classes (from sand to silty clay loam). Soils had various contents of metals (14–4500 mg kg−1 for Zn, 18–6530 mg kg−1 for Pb, and 0.17–34 mg kg−1 for Cd), ranging from natural background levels to high contents indicative of industrial contamination in the region. Soil samples were scanned at the wavelengths from 400 to 2498 nm (near‐infrared region) and from 2500 to 25000 nm (mid‐infrared region). Calibrations were developed using the one‐out validation procedure under partial least squares (PLS) regression. Mid‐infrared spectroscopy markedly outperformed NIRS. Iron, Cd, Cu, Ni, and Zn were successfully predicted using DRIFTS. The coefficients of determination (R2) between actual and predicted contents were 0.97, 0.94, 0.80, 0.99, and 0.96 for those metals, respectively. Only Pb content was predicted poorly. Calibrations using NIRS were less accurate. Root mean squared deviation (RMSD) values were from 1.27 (Pb) to 3.3 (Ni) times higher for NIRS than for DRIFTS. Results indicate that DRIFTS may be useful for accurate predictions of metals if samples originate from one region.
Particulate Phosphorus Transport within Stream Flow of an Agricultural Catchment
Authors: McDowell R. W. , Wilcock R. J.
Published: June 2010

There is interest in quantifying phosphorus (P) loss from intensively grazed dairy landscapes to identify key pathways and target remediation methods. The Bog Burn drains a dairying catchment in Southland, New Zealand, and has been monitored at fortnightly intervals over a 12‐mo period at four sites for suspended sediment (SS), dissolved reactive phosphorus (DRP), and total phosphorus (TP). Time‐integrated samplers, deployed at 0.6 median water depth at each site (calculated from previous year's flow data), collected sediment samples, which were analyzed for SS, bioavailable phosphorus (BAP), and TP. Mean concentrations of DRP and TP in stream flow and BAP and TP in sediment were generally highest in summer or autumn (0.043 mg DRP L−1, 0.160 mg TP L−1, 173 mg BAP kg−1, 2228 mg TP kg−1) and lowest in winter or spring (0.012 mg DRP L−1, 0.034 mg TP L−1, 6 mg BAP kg−1, 711 mg TP kg−1), while loads were highest in winter. Analysis of 137Cs concentrations in trapped sediment, topsoil, subsoil, and stream bed and bank sediment indicated that trapped sediment was derived from topsoil and entered the stream either through tile drainage or, to a lesser extent, overland flow. Because concentrations of DRP and TP in stream flow are in excess of recommended limits for good water quality (>0.01 mg DRP L−1, 0.033 mg TP L−1), management should focus on the topsoil and specifically on decreasing P loss via tile drainage. This is best achieved by decreasing soil Olsen P concentrations, especially because, on average, Olsen P concentrations in the catchment were above the agronomic optimum.
Refined Tunable Methodology for Characterization of Contaminant–Particle Relationships in Surface Water
Authors: Marvin Christopher H. , Leppard Gary G. , West M. Marcia , Stern Gary A. , Boden Adrienne R. , McCarry Brian E.
Published: June 2010

To understand contaminant transport in aquatic systems, it is essential to define the physical characteristics of the primary particulate carriers. The distribution of organic pollutants with particle‐size class and particle morphology in a freshwater embayment (Hamilton Harbor, western Lake Ontario) was studied using a sequence of novel sample preparation and characterization techniques. Water samples (24 L) were fractionated according to particle‐size distribution using differential cascade sedimentation and centrifugation methods. These size fractions were subsequently subjected to a physicochemical characterization using scanning transmission electron microscopy and energy‐dispersive spectroscopy to identify flocs and individual colloidal particles in the size range of 1 nm to 1 mm in diameter. Analytical chemical analyses were performed to identify organic contaminants in extracts prepared from particle‐size classes, including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The contaminant distribution trends were very similar for all compound classes studied; contaminants were primarily associated with fractions containing particles less than 2 μm in diameter. Morphological characterization of these fractions showed the majority of the particulates to be humic fractals. The results of this study show that contaminants in aquatic systems can be preferentially associated with specific types of particle carriers, the characteristics of which can be clearly defined in terms of size and morphology.
Radionuclide Transport Above a Near‐Surface Water Table: IV. Soil Migration and Crop Uptake of Chlorine‐36 and Technetium‐99, 1990 to 1993
Authors: Shaw G. , Wadey P. , Bell J. N. B.
Published: June 2010

Vertical distributions of 36Cl and 99Tc are presented from deep and shallow lysimeters above artificially controlled water tables for a 4‐yr experiment from 1990 to 1993. Activity concentration profiles were all measured in late summer when a winter wheat (Triticum aestivum L. cv. Pastiche) crop was harvested. After harvest, activity concentrations in different organs of the crop were determined and crop uptake quantified as both an inventory ratio (IR) and a transfer factor (TFw), weighted to account for differential root and radionuclide distributions within the soil profile. Vertical distributions of radionuclides, crop roots within the soil, and IR and TFw values were each subjected to analysis of variance to estimate the individual and combined effects of soil depth and the year of the experiment on the results obtained. Chlorine‐36 and 99Tc exhibited highly significant variations in activity concentrations with soil depth and from year to year, indicating considerable physical mobility of both radionuclides. Soil‐to‐plant transfer was also high for both radionuclides compared with data obtained for gamma‐emitting radionuclides. The IR values indicated that up to 40% of 36Cl was incorporated in the crop's tissues at harvest, compared with a maximum of less than 1% for the less mobile gamma‐emitting radionuclides. On the basis of the TFw values determined, 36Cl uptake by winter wheat exceeded 99Tc uptake, indicating that 36Cl is highly bioavailable. Factors controlling the migration and bioavailability of both 36Cl and 99Tc in soils are discussed.
Kinetic Effect of Humic Acid on Alachlor Degradation by Anodic Fenton Treatment
Authors: Wang Qiquan , Lemley Ann T.
Published: June 2010

Contamination of water often results from the heavy use of agricultural chemicals, and the disposal of aqueous pesticide waste is a concern. Anodic Fenton treatment (AFT) has been shown to be a successful remediation method for pesticides in solution, but the effect of soil on the degradation kinetics of pesticides using this method has not been determined. The purpose of this study was to study the effect of humic acid, as a soil surrogate, on the degradation kinetics of alachlor [2‐chloro‐N‐(2,6‐diethylphenyl‐N‐(methoxymethyl) acetamide], a heavily used herbicide that has been studied in pure aqueous solution by AFT. The AFT consists of a controlled constant delivery of Fenton reagents, using an electrochemical half‐cell to deliver ferrous iron. Alachlor was quickly degraded by AFT, and the kinetics were found to obey the previously developed AFT model well. Degradation of alachlor by AFT in humic acid slurry showed that when the amount of humic acid was increased, alachlor degradation was significantly slowed down and the degradation kinetics were shifted from the AFT model to a first‐order model. Further experimentation indicated that humic acid not only competes with alachlor for hydroxyl radicals, reducing the degradation rate of the target compound, but also buffers the slurry at near neutral pH, blocking regeneration of ferrous ion from ferric ion and subsequently shifting the kinetics to first order. Degradation of several other pesticides in humic acid slurry also followed first‐order kinetics. These results imply that higher concentrations of Fenton reagents will be required for soil remediation.
Microcosm Studies on Anaerobic Phosphate Flux and Mineralization of Lake Sediment Organic Carbon
Authors: Song Jing , Luo Yongming , Zhao Qiguo , Christie Peter
Published: June 2010

Lake sediment has long been recognized as an important source of nutrients such as phosphorus. To gain a better understanding of phosphorus flux at the sediment–water interface, it is crucial to investigate the sediment porewater. There is also growing concern and interest in identifying whether organic‐rich sediment is an important source of greenhouse gases such as CO2 and CH4 In the present study, we took sediment samples from West Lake, a shallow hypereutrophic lake in Hangzhou, Zhejiang Province, China and incubated subsamples under anaerobic conditions at 25°C for 182 d using a specially designed microcosm that permits repeated extraction of sediment porewater and sampling of headspace gases. Anaerobic phosphate fluxes and mineralization of sediment organic carbon were measured. Average diffusive flux of soluble phosphorus was 0.81 mg P m−2 d−1 during the initial 18 d of incubation. Decomposition of sediment organic C followed zero‐order reaction kinetics and methane accounted for about 50% of the mineralization products. The results suggest that organic‐rich sediments can be important sources of P and methane under anaerobic conditions. Laboratory studies simulating field conditions and field studies are necessary to determine the contribution of sediment as a source of P and greenhouse gases.
Response of Biogeochemical Indicators to a Drawdown and Subsequent Reflood
Authors: Corstanje R. , Reddy K. R.
Published: June 2010

Temporal oscillations in hydrology are a common occurrence in wetlands and can result in alternating flooded and drained conditions in the surface soil. These oscillations in water levels can stimulate microbial activities and result in the mobilization and redistribution of significant amounts of carbon (C), nitrogen (N), and phosphorus (P). The goal of this study was to experimentally simulate a drawdown and reflood of marsh soil from a nutrient‐enriched site and a reference site of a wetland (Blue Cypress Marsh Conservation Area, Florida). The goal was to better understand the changes in biogeochemistry and microbial activities present in these soils as a result of hydrological fluctuations. Measurements of dissolved reactive phosphorus (DRP), ammonia, and nitrate in the floodwater indicated significantly higher (α = 0.05) NH4+ and DRP fluxes from the nutrient‐enriched site; floodwaters in the cores from both sites contained significant NO3− concentrations (9.6 mg N L−1), which was rapidly consumed over the core incubation period (30 d). Water level drawdown and reflooding initially stimulated the soil microbial biomass, methanogenic rates, and extracellular enzyme activities (acid phosphatase and β‐glucosidase). The anaerobic microbial metabolic activities (CO2) where initially significantly (α = 0.05) enhanced by the reflood, resulting in roughly equivalent rates as the aerobic respiratory activities (CO2), presumably as a function of the high water column NO3− levels. This study illustrates that the reflood event in the hydrological cycles in a wetland can significantly stimulate the activities of hydrolytic enzymes and microbiological communities in these soils.
Construction of Platinum‐Tipped Redox Probes for Determining Soil Redox Potential
Authors: Wafer Carrie C. , Richards J. Barrett , Osmond Deanna L.
Published: June 2010

Redox probes are typically constructed by soldering Pt wire to a metal wire or rod, such as copper or brass. The junction between the Pt and wire or rod is often sealed with an epoxy resin and hardener or with heat‐shrink tubing. Microcracks (small cracks invisible to the unaided eye) can form in the hardened resin and result in incorrect readings. The hardened resin is not easily removed, making repairs difficult. Heat‐shrink tubing is thin, lacks rigidity, and can be damaged in the soil. The method described in this paper used a thick‐walled, adhesive‐lined terminal insulator to seal the junction. The terminal insulators were easily applied and removed, which made faulty probes easy to repair. Two‐hundred forty probes were made with this method and eight were made with a marine epoxy resin. The probes were tested with a redox buffer solution (Light Solution) and were usable if they read +476 ± 10 mV. The probes were installed 0.76 and 1.5 m deep in the soil. The ability of the probes to provide reliable redox readings was examined by testing selected probes after 10 mo of use and testing all of the probes after completion of the study (19 mo). Ten of the twelve probes tested after 10 mo worked satisfactorily, while the other two clearly malfunctioned before testing. After the study was completed, 236 of the 240 of the probes worked satisfactorily. These results indicate that the construction method presented produces reliable, long‐lasting probes.
Nitrogen Mineralization from Organic Residues
Authors: Cabrera M. L. , Kissel D. E. , Vigil M. F.
Published: June 2010

Research on nitrogen (N) mineralization from organic residues is important to understand N cycling in soils. Here we review research on factors controlling net N mineralization as well as research on laboratory and field modeling efforts, with the objective of highlighting areas with opportunities for additional research. Among the factors controlling net N mineralization are organic composition of the residue, soil temperature and water content, drying and rewetting events, and soil characteristics. Because C to N ratio of the residue cannot explain all the variability observed in N mineralization among residues, considerable effort has been dedicated to the identification of specific compounds that play critical roles in N mineralization. Spectroscopic techniques are promising tools to further identify these compounds. Many studies have evaluated the effect of temperature and soil water content on N mineralization, but most have concentrated on mineralization from soil organic matter, not from organic residues. Additional work should be conducted with different organic residues, paying particular attention to the interaction between soil temperature and water content. One‐ and two‐pool exponential models have been used to model N mineralization under laboratory conditions, but some drawbacks make it difficult to identify definite pools of mineralizable N. Fixing rate constants has been used as a way to eliminate some of these drawbacks when modeling N mineralization from soil organic matter, and may be useful for modeling N mineralization from organic residues. Additional work with more complex simulation models is needed to simulate both gross N mineralization and immobilization to better estimate net N mineralized from organic residues.
Occurrence and Fate of Pharmaceuticals and Personal Care Products (PPCPs) in Biosolids
Authors: Xia Kang , Bhandari Alok , Das Keshav , Pillar Greg
Published: June 2010

Each year, large quantities of pharmaceuticals and personal care products (PPCPs) are used worldwide. Once conveyed to wastewater treatment plants, PPCPs can remain unchanged or undergo partial or complete transformation during wastewater treatment processes before discharge into the environment via effluent and biosolids for land application. Biosolids can be a major sink for some PPCPs. Previous investigations have indicated that land application of biosolids may be a potential important route through which PPCPs enter the environment. However, no information is available on exactly how closely the concentrations of PPCPs in the environmental media are related to the land application of PPCP‐containing biosolids. This paper reviews currently available information on the occurrence of PPCPs in biosolids, methods of analysis, the potential fate of PPCPs in biosolids‐applied soils, and composting as a potential means for removal of PPCPs from biosolids.