bluuebunny/crossref_metadata_2025_split huggingface dataset:
Persistence of Organic Contaminants in Sewage Sludge‐Amended Soil: A Field Experiment
Authors: Wilson S. C. , Alcock R. E. , Sewart A. P. , Jones K. C. 
Published: July 2010

AbstractDigested sludge was applied to plowed arable and pasture grassland plots and losses of specific volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo‐p‐dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and chlorophenols (CPs) monitored over 260 d. Sludge addition increased soil concentrations of all compounds in the plowed plot. VOCs, PCBs, and CPs concentrations declined to control plot values within 128 d of sludge amendment. Volatilization and biodegradation were considered important loss processes for these compounds. However, PCDD/F and of non‐o‐PCB 77 concentrations did not change consistently and remained elevated above control plot concentrations throughout the monitoring period. At Day 260 410 ± 53 ng ΣPCDD kg−1 and 250 ± 10 ng ΣPCDF kg−1 was detected in the sludged plot compared to 68 ± 9 ng ΣPCDD kg−1 and 170 ± 7 ng ΣPCDF kg−1 in the control plot. Data from the pasture plot has highly variable and differences between most contaminant concentrations in the sludged and control plots were insignificant. This was attributed to adherence of much of the applied sludge to vegetation rather than direct application to the soil surface and has important implications for elevated dietry intake of certain persistent organic compounds such as the PCDD/Fs. Further research is needed to evaluate the importance of sludge adherence to vegetation for human exposure to a range of contaminants detected in sludge. Contaminant movement to depth (20 cm) was not detected within 260 d for compounds monitored (VOCs and PCDD/Fs).
Fate of Summertime Airborne Organophosphate Pesticide Residues in the Sierra Nevada Mountains
Authors: Aston Linda S. , Seiber James N. 
Published: July 2010

AbstractThis study examines the processes of dilution, degradation, and sorption to plant foliage of organophosphate (OP) pesticides during the summertime in an air corridor originating in the southern Central Valley of California and moving into the nearby Sierra Nevada mountains. Residues of chlorpyrifos, methidathion, and their oxons were examined in air and pine needles at three sites in the southern Sierra to delineate the role these processes play in the atmospheric fate of these residues. At the site closest to the Central Valley, we found relatively high levels of parent OPs and oxons in needle and air samples. At higher elevations needles contained lesser amounts of OP residues and at lower frequency, while air primarily contained the oxon form. With increasing elevation the ratio of thion to oxon form of chlorpyrifos in air decreased from 1.85 to 0.46 indicating that atmospheric oxidation was occuring. Based on the amounts of foliar deposition found, we estimate that during summer months nearly 16 kg of chlorpyrifos and its oxon may enter Sequoia National Park plant foliage. We deduce that for airborne OP insecticides, foliar deposition is a significant summertime fate process, along with atmospheric degradation and dilution.
Transport and Transformation of Urea and Its Derivatives through a Mineral Subsoil
Authors: Swensen Berit , Singh Bal Ram 
Published: July 2010

AbstractThe transport and transformation potential of N compounds derived from urea, applied as a deicing agent during the winter period, have been investigated in a coarse, heterogeneous glacial‐contact deposit in southeast Norway. The hydrolysis of urea to ammonium‐N (NH+4‐N) and subsequent oxidation to nitrate‐N (NO−3‐N) was monitored by extraction of soil water from five depths (from 70 to 220 cm) in a lysimeter trench. Urea transport through a soil profile is normally negligible, although urea is a hydrophilic, uncharged molecule. In this study, urea was rapidly transported to at least 220 cm. The measured urea‐N concentrations varied from 2 to 50 mg L−1 throughout the profile. This transport was explained by minimal hydrolytic activity because of soil temperatures close to 0°C, and by different preferential flow mechanisms being important during the snowmelt period. Urea hydrolysis occurred at all depths. The NH+4‐N formed in this in situ hydrolysis was oxidized to NO−3‐N. The nitrification started immediately and was most rapid at the 70‐ and 105‐cm depth, but was detectable at all depths down to 220 cm 120 d after solute application. Nitrification also occurred during the winter following the urea application. One year after the urea application, about 40% of the applied urea‐N was recovered as NO−3‐N in the unsaturated zone (0–450 cm), and it is estimated that at least 50% of the applied N will reach the groundwater as NO−3‐N.
Shallow Groundwater Denitrification Rate Measurement by Acetylene Block
Authors: Bragan R. J. , Starr J. L. , Parkin T. B. 
Published: July 2010

AbstractWe field tested a short term, in situ method for measuring highly variable shallow groundwater denitrification rates using a methodology developed in an earlier, laboratory phase of this study. A pulse of tracer solution was injected and subsequently sampled within well clusters 50 cm in radius. The injectate contained dissolved acetylene (C2H2) to block denitrification at the nitrous oxide (N2O) stage of reduction. Six well clusters were established at two depths along a riparian area transect through field, grass, and woodland ecotypes. Bromide tracer, C2H2, and accumulated N2O were monitored at sample wells downgradient from each injection well. Adequate C2H2 concentrations (0.43 mM) to block N2O reduction between injection and sample wells were attained in five of the six well clusters tested. Acetylene peak concentrations moved laterally an average of 19% more slowly than the Br peak, N2O peak concentrations an average of 8% after C2H2 peaks. Highest denitrification rates of 2.8 and 3.3 mg N L−1 d−1 were observed near the surface of the water table within the grass buffer and riparian forest. Shallow groundwater denitrification rates in the adjoining field and 2 m deep into the saturated zone at all three ecotypes were <25% of the highest rates. Acetylene block procedures were thus used to determine in situ denitrification rates within a few days time with little disruption of soil structure or associated microbial communities. Portable equipment allows application at remote sites independent of line power and road access.
Iron‐Related Phosphorus in Overfertilized European Soils
Authors: Ruiz J. M. , Delgado A. , Torrent J. 
Published: July 2010

AbstractIron‐related P forms directly influence the amount of phosphate released from soils and sediments, particularly when subjected to reduction. In this work, we examined such P forms in 12 overfertilized, widely different European soils by using various single and sequential extraction techniques, including the use of a mild and a strong reductant (ascorbate and dithionite, respectively). Reductant‐soluble P (defined as the amount of P released by the specific action of a strong reductant) ranged from 2 to 63% of the total amount of P extracted by the sequential extraction procedure of Olsen and Sommers. More than 50% of reductant‐soluble P was released by the specific effect of ascorbate in most of the soils studied. The results of the sequential extractions suggest that, on average, about one‐half of the reductant‐soluble P was occluded in Fe oxides. Poorly crystalline and crystalline Fe oxides generally contained similar amounts of occluded P in absolute terms. However, P/Fe mole ratios were higher in poorly crystalline than in crystalline Fe oxides (X̄ = 5.9 and 1.7 × 10−2, respectively). We suggest that fertilizer P may have been occluded in Fe oxides, particularly in the poorly crystalline forms. The contribution of the parent material, pedogenesis, and fertilization to occluded P build‐up is difficult to assess. Though obtained in vitro, our results suggest that reduction of overfertilized soil materials in aquatic environments can release significant amounts of P; these in turn increase saturation of reduction‐resistant P‐adsorbing surfaces and thus help increase the P equilibrium concentration in solution.
Spatial and Temporal Variability of Herbicides in a Claypan Soil Watershed
Authors: Ghidey F. , Alberts E. E. , Lerch R. N. 
Published: July 2010

AbstractThe spatial and temporal variability of herbicides during the growing season were studied on a 35‐ha watershed located in the claypan soil region of north‐central Missouri. Soil samples were collected from the 0‐ to 5‐cm soil depth in 1993, and 0‐ to 5‐, 5‐ to 10‐, and 10‐ to 15‐cm soil depths in 1995 and analyzed for atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) and alachlor (2‐chloro‐N‐(2,6‐diethl‐N‐(methoxymethyl) acetanilide) concentrations. The effects of rainfall, topography, soil pH, cation exchange capacity (CEC), and organic matter (OM) content on the spatial distribution of herbicides were evaluated. There was no spatial dependency between samples taken immediately after herbicide application; however, spatial dependency was observed in the following sampling periods. During the year, <2.5% of atrazine and 2.0% of alachlor applied to the soil was lost in runoff, and the movement of herbicides below the layer of application was also very low throughout the sampling period. Atrazinc and alachlor concentrations in the soil decreased rapidly during the growing season. Concentrations measured 4 and 8 wk after application were <20 and 5% for atrazine, and <10 and 3% for alachlor, respectively, of those measured immediately after application. The study showed that the spatial and temporal variability of herbicide concentration was a function of the interaction between soil pH and the sorptive capacity of the soil (CEC and OM content). These findings are useful for site‐specific crop management to increase the efficiency of herbicide application and also to reduce the loss of excess herbicides to surface runoff.
Fluoride Solubility in Dust Emission from an Aluminum Smelter
Authors: Arnesen A. K. M. 
Published: July 2010

AbstractFluorides are emitted to the atmosphere as hydrogenfluoride (HF) gas and in particle forms from the production of aluminum (Al). The solubilities of fluoride (F) and Al in particle emission from an aluminum smelter were studied in relation to pH and dust/water ratio. A soil column experiment was performed to study the retention of dust‐components in soil and the effect on chemistry of soil leachate. The solubility of F in the dust decreased when pH in water was increased from 2 to 6.5. From pH 6.5 to 9, the solubility was almost constant. The solubility of Al decreased with increased pH up to pH about 7.5. The amounts of water‐soluble F increased from about 3.5% of the dust with dust/water ratio 1:100 to about 5.8% with dust/water ratio 1:10 000. The corresponding results for Al were 1.3 and 2% of the dust. Relatively high leaching of F occurred from columns with quartz‐sand. High leaching occurred from humus. A podzolic Bs‐horizon retained almost all of the added F. Leaching of Al and organic material were significantly elevated by the highest dust input in all the columns. Leaching of Na was elevated by the dust‐input, but differed less between the columns. Dust particles deposited will to a great extent solubilize and react with the soil. The retention of F and Al in the soil depends on soil type, with little sorption in organic soil and strong sorption in mineral horizons with Al‐oxides/hydroxides.
Phosphorus Transformations in the Sediments of Delaware's Agricultural Drainageways: II. Effect of Reducing Conditions on Phosphorus Release
Authors: Sallade Y. E. , Sims J. T. 
Published: July 2010

AbstractMost agricultural fields in Delaware's Inland Bays' watershed are high or excessive in P from long‐term applications of poultry litter (PL) and fertilizers and many are arable only because they have been drained by large open ditches. The possible role of sediments in these ditches in P loading to the Inland Bays was assessed in laboratory studies. Sediments collected from 17 ditches ranged in biologically available P (BAP) from 5 to 1218 mg P kg−1 and in soil test P from 3 to 62 mg P kg−1. Sequential fractionation indicated that Al‐P (0.05 N NH4F) and Fe‐P (1.0 N NaOH) were the predominant forms of sediment inorganic P. The degree of phosphorus saturation (DPS), defined as BAP ÷ PSI (P sorption index, a rapid measure of sediment P sorption capacity), averaged 46 and 37% in the top and bottom sediments, respectively. The potential for P release from sediments to drainage waters was determined by incubating all sediments under flooded, anoxic conditions for 21 d. The effects of time and temperature (7 and 35°C) on P release were determined in a separate study with six sediments incubated for 42 d. Initial P in solution was well correlated with BAP (r = 0.74***) and organic matter (r = 0.66***), while P release after 21 d was well correlated with DPS (r = 0.75***) and total Fe‐oxide content (r = 0.66***). A critical sediment DPS value of 40% is proposed to target drainage ditches with higher potential to release P to overlying waters.
Heavy Metals of the 20th Century Recorded in Oak Tree Rings
Authors: Jonsson Arne , Eklund Mats , Håkansson Karsten 
Published: July 2010

AbstractTree rings from 23 oak trees (Quercus robur L.) were used to monitor historical heavy metal emissions from anthropogenic sources on a regional scale. The concentrations of Cd and Pb in the tree rings were analyzed using atomic absorption spectrophotometry. From the results, chronologies were constructed representing the heavy metal background load of the 20th century. The chronologies were compared with calculated estimates of the accumulation of these metals in soil. The method of tree‐ring analysis proved to be useful for monitoring Cd and Pb emissions from diffuse sources when applied as a complement to other methods, in this case calculated accumulation. This study also indicates that no radial transport occurs in the inward direction, from sapwood to heartwood, but that outward diffusion to some extent might occur at least within the sapwood. The conspicuous difference between the soil/wood ratios for Cd and Pb implies that a larger proportion of the soil Cd is taken up by the tree than is the case for Pb.
Methyl Mercury Contamination and Emission to the Atmosphere from Soil Amended with Municipal Sewage Sludge
Authors: Carpi Anthony , Lindberg Steven E. , Prestbo Eric M. , Bloom Nicolas S. 
Published: July 2010

AbstractIn an effort to identify the effect of municipal sewage sludge application on mercury (Hg) concentrations in soil, we studied the contamination of sludge‐amended soil with inorganic and methyl Hg and the emission of these contaminants to the atmosphere using a Teflon dynamic flux chamber. The routine application of municipal sewage sludge to cropland significantly increased both total and methyl Hg in surface soil from 80 to 6100 µg kg−1 and 0.3 to 8.3 µg kg−1, respectively. Both inorganic and methyl Hg were transported from the sludge/soil matrix to the environment by emission to the atmosphere, however, there was no indication of Hg transport in limited soil water lysimeter experiments. Our data from soil amended with municipal sewage sludge represent the first quantitatively measured terrestrial source of methyl mercury (MeHg) to the atmosphere. Sludge‐amended soil emitted an average of 12 to 24 pg m−2 h−1 of monomethyl Hg and ∼100 ng m−2 h−1 of inorganic Hg to the atmosphere. A simple dispersion model suggests that sludge‐amended soil may increase regional atmospheric MeHg concentrations by ∼5%. These data highlight the need for further research to quantify the transport of Hg from sludge‐amended soil and identify the sources of MeHg in the atmosphere.
Application of Biosolids to Degraded Semiarid Rangeland: Nine‐Year Responses
Authors: White C. S. , Loftin S. R. , Aguilar R. 
Published: July 2010

AbstractRangeland restoration through surface application of biosolids (municipal sewage sludge) is an increasing practice. Biosolids supply both organic matter and available nutrients that are lacking in degraded rangeland soils. This study investigated the effects of biosolids applications of 0, 22.5, 45, and 90 Mg ha−1 to a degraded rangeland in 1985 on the soil chemical properties and N mineralization potentials 8 and 9 yr after the application, respectively. Following an initial increase in proportion to the application rate, levels of water‐extractable Ca, Mg, Na, nitate (NO3‐N), and electrical conductivity declined to that near the control soils after 8 yr. Nearly all diethylenetriaminepentaacetic acid (DTPA)‐extractable metals (Fe, Zn, Cu, Cd, and Pb) were highest in the collection 4 yr after application, but were near concentrations in the control soil after 8 yr. Nitrogen mineralization potentials were significantly higher (P < 0.05) in the 45 and 90 Mg ha−1 applications after 9 yr, indicating that site fertility remained higher even though most soil chemical properties were returning to untreated levels.
Mineralizable Nitrogen in Broiler Litter: II. Effect of Selected Soil Characteristics
Authors: Gordillo R. M. , Cabrera M. L. 
Published: July 2010

AbstractBroiler litter (BL) is a mixture of chicken (Gallus gallus domesticus) manure and bedding material that is commonly used as fertilizer for crops and pastures. Knowledge of the factors that determine the amount of potentially mineralizable N in BL is needed to estimate adequate application rates. Limited evidence suggests that soil characteristics such as texture can significantly affect the amounts of net N mineralized from BL. This work was conducted to compare the kinetics of N mineralization of the same BL in nine different soil samples, and to determine the effect of selected soil characteristics on the amount and rate of decomposition of potentially mineralizable N in BL. Samples from the same BL were mixed with nine soils (150 mg organic N kg−1, −0.02 MPa) and incubated at 25°C for 146 d. A two‐pool, first‐order kinetics model adequately described cumulative net N mineralized from the litter, which ranged from 364 to 784 g N kg−1 organic N. Multiple regression analysis generated statistically significant equations that identified the ratio of (sand content/water content at field capacity) and pH as soil characteristics with a significant effect on the fast and slow pools of mineralizable N. Combining a predictive equation for total mineralizable N based on BL characteristics with a predictive equation for total mineralizable N based on soil characteristics, we generated an equation that predicts total mineralizable N based on BL and soil characteristics. Future work should further test this equation and correlate plant N uptake with predicted values of potentially mineralizable N in BL.
Ammonia and Nitrous Oxide Emissions from Sprinkler Irrigation Applications of Swine Effluent
Authors: Sharpe R. R. , Harper L. A. 
Published: July 2010

AbstractIn the USA, swine operations produce more than 14 Tg of manure each year. About 30% of this manure is stored in anaerobic lagoons before effluent applications to land. Although land application is the preferred means of disposal and can supply nutrients for crop production, it leads to gaseous emissions of ammonia (NH3) and nitrous oxide (N2O), both of which can be detrimental to the environment. Our objectives were to quantify gaseous emissions of NH3 and N2O from effluent applications under field conditions and to relate N2O fluxes to soil water content. Three applications of swine effluent were applied to oat (Avena sativa “GA‐Mitchell”) starting at heading stage. Gaseous fluxes were determined from gas concentration profiles and the momentum balance transport coefficient. About 13% of the ammonium (NH4‐N) was lost through drift or volatilization of NH3 during irrigation. An additional 69% was volatilized within 24 h of application. Nitrous oxide emissions were low before effluent applications (19 mg N2O‐N ha−1 d−1) and increased to 0.25 t o 0.38 kg N2O‐N ha−1 d−1 after irrigation. Total N2O emissions during the measurement period were 4.7 kg N2O‐N ha−1, which was about 13% of total N applied. The large losses of NH3 and N2O illustrate the difficulty of basing effluent irrigation schedules on N concentrations and the data indicate that compared to N2O, NH3 emissions made greater contributions to N enrichment of the environment.
Variability of Leaf Phosphorus among Sugarcane Genotypes Grown on Everglades Histosols
Authors: Glaz Barry , Deren Christopher W. , Snyder George H. 
Published: July 2010

AbstractThe P content of drainage water of the Everglades Agricultural Area (EAA) of Florida must be reduced by at least 25% from a baseline mean calculated using 1978 through 1988 data. This minimum P reduction is one of several measures to sustain much of the unique habitat of remaining natural regions of the Everglades. The objectives of this study were to evaluate variability in leaf tissue P concentration among elite sugarcane (interspecific hybrids of Saccharum spp.) clones and to recommend sampling strategies to detect differences among clones. Leaf samples were collected four times per annual crop in the plant‐cane and first‐ratoon crops from three fields, representing low, medium, and high available soil P. Leaf P of sugarcane should be tested at several locations in at least two crop years, and at least once, but preferably twice per crop. The clone with the most leaf P had 0.65 g P kg−1 leaf tissue more than the clone with the least. This difference among leaves allowed us to speculate that P removal may differ by about 8.5 kg ha−1 among commercial cultivars and that genetic improvement of this trait could be feasible. If further studies show that differences in leaf P concentration can reliably predict differences in total P removal from a sugarcane field, then classification of cultivars for leaf P concentration could make available to EAA sugarcane farmers another best management practice (BMP) to reduce P content of their drainage waters.
Agricultural Nutrient Losses to Surface Water in the Netherlands: Impact, Strategies, and Perspectives
Authors: Van der Molen Diederik T. , Breeuwsma Auke , Boers Paul C. M. 
Published: July 2010

AbstractNutrient emissions from agricultural activities have become the dominant source of nutrient loads to freshwater in the Netherlands. This paper focuses on nutrient emissions from agriculture, emphasizing nutrient loads to surface waters, and strategies and perspectives to reduce these emissions. Although adverse environmental effects of intensive agriculture have been known for several years, it was not until 1987 that stabilization of animal manure production and application began. Since 1991 manure application rates have been reduced. Recently, application standards have been replaced by agriculturally inevitable nutrient losses and environmentally acceptable nutrient losses and these losses are reduced to an equilibrium fertilization in 2010, defined as the supply of manure and fertilizers that meets crop uptake and compensates for inevitable losses. In the 1980s, the most important tool to manage nutrient losses was a manure bookkeeping; recently a mineral bookkeeping has been introduced. Agricultural nutrient emissions to and their impact upon surface waters have been estimated from field experiments and model calculations, which indicate that the proposed legislation will not significantly improve water quality. Increasing areas will be saturated with P, especially where intensive livestock farming is located on sandy soils. Tailor‐made regional programs are necessary to achieve ecological restoration of surface waters, with priority for catchment areas with vulnerable receiving waters. These programs may consist of a further reduction of nutrient application rates, hydrological measures, selection of crops that extract P from the soils or measures to increase the P adsorption capacity of the soil, and buffer strips.