bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Sorption of Nonionic Organic Solutes to Humic Acid‐Mineral Complexes: Effect of Cosolutes
Authors: Onken B. M. , Traina S. J. 
Published: July 2010

AbstractIn binary isotherms, pyrene and naphthalene sorption were enhanced by the presence of anthracene as a cosorbate. Sorption enhancement was observed at low fractional organic carbon content (foc) (<3 × 10−5) and diminished foc increased. The addition of cosolutes to low foc systems (<3 × 10−5) appeared to aid the transition from adsorption/condensation type surface interactions to an interaction more like partitioning. It is postulated that observed sorption enhancement in higher foc systems (= 3 × 10−5) was due to an increase in effective foc resulting from cosolute sorption. The presence of a cosolute did not affect systems where partitioning was already the primary process. If partitioning was not occurring, the addition of a cosolute reduced the surface excess of the solute by competing for adsorption sites. This competition occurred until surface organic C increased to a sufficient concentration to promote partitioning. This research indicates that the use of Koc values derived from Kow data in low foc systems significantly underestimate the interactions of nonionic organic solutes with low organic C surfaces.
Efficiency of Grass Buffer Strips and Vegetation Height on Sediment Filtration in Laboratory Rainfall Simulations
Authors: Pearce Robert A. , Trlica M. J. , Leininger Wayne C. , Smith James L. , Frasier Gary W. 
Published: July 2010

AbstractA laboratory rainfall simulation was conducted to compare the influence of three lengths of vegetation buffer strips and two vegetation heights on sediment filtration. The purpose of the experiment was to help evaluate stubble height grazing guidelines. Rainfall (50 mm h−1) was sprayed simultaneously over six trays (0.3 × 1.0 m). Concurrently, sediment laden (150 g tray−1) overland flow (50 mm h−1) was introduced to the upslope end of the trays. Two trays contained 12.5 cm, two trays contained 25.0 cm, and two trays contained 50.0 cm of Kentucky bluegrass (Poa pratensis L.) buffer strips during each simulation run. Paired buffer length trays either were clipped to the soil surface or grass was 10 cm tall. A significant interaction existed between vegetation buffer length and vegetation height. The clipped to the soil surface vegetation height was more effective as a sediment filter with the 12.5 cm buffer length than was the 10.0 cm height. Conversely, the 10.0 cm vegetation height was more efficient as a sediment filter with a 50 cm buffer length than was the clipped to the soil surface vegetation. No differences in sediment filtration efficiency existed between vegetation heights at the 25 cm buffer length. Additionally, 50 mm h−1 of rainfall was applied and 50 mm h−1 overland flow was added to six trays containing bare soil (no vegetation). Three the bare soil trays received sediment laden (150 g tray−1) overland flow and three trays received sediment free overland flow. All trays with the three vegetation buffer lengths had less sediment yield than did the bare soil trays. Results from this study suggest that vegetation height alone is not a suitable guideline for estimating sediment filtration and that length of vegetation buffer was more important than vegetation height in filtering sediment.
Simulating Atrazine Transport Using Root Zone Water Quality Model for Iowa Soil Profiles
Authors: Azevedo A. S. , Kanwar R. S. , Singh P. , Ahuja L. , Pereira L. S. 
Published: July 2010

AbstractThe pesticide component of the Root Zone Water Quality Model (RZWQM) was calibrated and evaluated for two tillage systems: no‐till (NT) and moldboard plow (MB). The RZWQM is a process‐based model that simulates the water and chemical transport processes in the soil‐crop‐atmosphere system. Observed data on atrazine concentrations in the soil profile, for model calibration and testing, were obtained from a field study in Iowa.Two statistical parameters, maximum error (ME) and coefficient of determination (CD), were used to evaluate the ability of the RZWQM to predict atrazine concentrations in the soil profile. The ME, CD, and other statistical tests indicated that there was a significant difference between predicted and observed atrazine concentrations. Comparison of simulated vs. observed atrazine concentrations with 1:1 line showed that atrazine concentrations were overpredicted, especially in the later part of the growing season. However, the model correctly predicted depth of atrazine penetration in the soil profile. Also, the range of predicted atrazine concentrations was within the same order of magnitude as observed concentrations. Although observed atrazine concentrations were usually higher in surface layers under MB than in NT treatment, the model did not show any consistent tillage effects on atrazine distribution in the soil profile. The results from this simulation study indicated that the following factors may be critical and should be considered when simulating pesticide transport in the subsurface environment: (i) macropore flow, (ii) variation in Koc and pesticide half‐life with depth, and (iii) interception of pesticide by surface residue during application.
Atrazine Mineralization in Laboratory‐Aged Soil Microcosms Inoculated with s‐Triazine‐Degrading Bacteria
Authors: Radosevich Mark , Traina Samuel J. , Tuovinen Olli H. 
Published: July 2010

AbstractAn atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine)‐mineralizing bacterial isolate was used as a biological probe to investigate the effects of atrazine residence time on subsequent bioavailability and biodegradatlon. [U‐14C‐ring]‐atrazine was reacted with sterile soils collected from long‐term, experimental, no‐till and conventional‐tillage plots. After aging for 1 d to 3 mo, the atrazine‐treated soils were inoculated with the bacterium (7 × 107 cells g−1) and 14CO2 evolution was measured with time. Mineralization of [U‐14C‐ring]‐atrazine could be described with a first‐order rate equation in soils from both tillage systems. Atrazine was rapidly mineralized in no‐till soil aged for 1 d, with 50% of the initial radioactivity recovered as 14CO2 within 2 d after inoculation. Both the mineralization rate constants (k) and the extent of mineralization (Pmax) decreased with soil residence time. conventional‐till soil, no significant aging effect was observed for soil reacted for 7 d; however, both the k and Pmax, values decreased with extended aging. Measurements of soil solution‐phase atrazine were determined by high‐pressure liquid chromatography analysis after solutions were retrieved by centrifugation. In no‐till soil, the observed degradation rates were 38 to 227 times slower than those predicted on the basis of solution‐phase experiments. The respective rates were 25 to 63 times slower in the conventional‐till soil. The results suggest that a significant fraction of the solution‐phase atrazine was sequestered from microbial attack and that the unavailable fraction increased with soil residence time.
The Aqueous Geochemistry of the Abandoned Spenceville Copper Pit, Nevada County, California
Authors: Levy D. B. , Custis K. H. , Casey W. H. , Rock P. A. 
Published: July 2010

AbstractThe Spenceviile Pit in Nevada County, CA, has been filled with acidic mine drainage for approximately 75 yr and is an active source of acidity and trace metals to an adjacent stream. This study was conducted to characterize the aqueous chemistry of the Spenceville Pit to better understand pit lake geochemistry. Filtered samples were collected at regular depth intervals and analyzed for Ca, Mg, Na, K, Fe, Al, Mn, Cu, Zn, Ba, Si, Ph, and P. The geochemical speciation model MINTEQA2 was used to calculate the activity ratios of Fe2+ (aq) to Fe3+ (aq) based on measurement of oxidation‐reduction potential using a combination Pt/Ag‐AgCl electrode, and to calculate saturation indices for various mineral phases. Sampling of the Spenceville Pit in summer (August) and in winter (December) shows that the deeper waters exhibit considerably higher concentrations of metals compared with the shallow waters, and that the water column may be permanently stratified. Neither the scavenging of trace metals (Cu, Ni, and Zn) by particulate iron‐hydroxide minerals nor their precipitation as metal sulfides exerts significant control on the distribution of metals in the pit water. Instead, elemental distributions appear to be controlled by the process of cyclic filling and evaporation. Analysis of mineral saturation states in the pit water and x‐ray diffraction analysis of the bottom sediments indicate that gypsum (CaSO4·2H2O), goethite (α‐FeOOH), jarosite [KFe3(SO4)2(OH)6], jurbanite (AlOHSO4·5H2O), and strengite (FePO4·2H2O) are solids that may potentially control elemental concentrations in the water colunm.
Carbon Dioxide‐Enriched Agroecosystems: Influence of Tillage on Short‐Term Soil Carbon Dioxide Efflux
Authors: Prior S. A. , Rogers H. H. , Runion G. B. , Torbert H. A. , Reicosky D. C. 
Published: July 2010

AbstractIncreasing atmospheric carbon dioxide (CO2) concentration can increase biomass production that may influence carbon (C) dynamics in terrestrial ecosystems. Soil CO2 efflux as affected by crop residues from high CO2 environments managed under different tillage systems has not been explored. This study examined the effects of tillage systems in a legume [soybean [Glycine max (L.) Merr.]] and nonlegume [grain sorghum [Sorghum bicolor] (L.) Moench.] CO2‐enriched agroecosystem on the rates of short‐term CO2 evolution from a Blanton loamy sand (loamy siliceous, thermic Grossarenic Paleudults). In the spring of 1994, CO2 efflux observations initiated within 5 s after a tillage event were compared to no‐tillage conditions for 8 d in plots where both crop species had been grown in open top field chambers under two CO2 conditions (ambient and twice ambient) for two seasons (1992 and 1993). Added CO2 increased yields, residue, and root biomass; higher percent ground cover was also observed in CO2‐enriched plots prior to the tillage treatment. Differences in C/N ratio of the residue may have influenced CO2 efflux rates; C/N ratio was highest for sorghum and was increased by elevated CO2. Efflux patterns were characterized by flushes of CO2 following initial tillage and rainfall events. Species × tillage and CO2 × species interactions were noted on several days and for total CO2 efflux values. Our results suggest that short‐term CO2 fluxes may be greater for tilled soybean and for soybean grown under elevated CO2; however, short‐term flux rates in the sorghum crop were affected by tillage, but not by CO2 level. These short‐term results should be viewed with caution when predicting long‐term C turnover in agroecosystems.
Chemical Fractionation of Cadmium, Copper, Nickel, and Zinc in Contaminated Soils
Authors: Ma Lena Q. , Rao Gade N. 
Published: July 2010

AbstractHeavy metals are potentially toxic to human life and the environment. Metal toxicity depends on chemical associations in soils. For this reason, determining the chemical form of a metal in soils is important to evaluate its mobility and bioavailability. Sequential extraction was used to fractionate four heavy metals (Cd, Cu, Ni, and Zn) from nine contaminated soils into six operationally defined groups: water soluble, exchangeable, carbonate, Fe‐Mn oxide, organic, and residual. The residual fraction was the most abundant pool for all four metals examined. A significant amount (2.4–44%) of Zn was present in the potentially available fraction: nonresidual fraction. A major portion (40–74%) of Cu was associated with the organic, Fe‐Mn oxide, and carbonate fractions in most of the soils. Contamination of Cd and Ni in these soils was not as severe as Zn and Cu. Assuming that mobility and bioavailability of these metals are related to their solubility and geochemical forms, and that they decrease in the order of extraction sequence, the apparent mobility and potential bioavailability for these four metals in the soils were: Zn > Cu > Cd > Ni. Metal distributions in different chemical fractions in these soils depended on respective total metal concentrations, except for Zn.
Wheat Grain Cadmium as Affected by Long‐Term Fertilization and Soil Acidity
Authors: Gavi F. , Basta N. T. , Raun W. R. 
Published: July 2010

AbstractSeveral studies have reported increases in grain Cd from long‐term continuous wheat (Triticum aestivum L.) systems. Increases in grain Cd have been associated with commercial fertilizer use, but information on long‐term use of N and P fertilizers on wheat grain Cd is limited. The objective of this study was to evaluate the impact of fertilization on wheat grain Cd from eight long‐term experiments that received 15 to 63 yr of N, P, and K fertilizer. Total Cd and Zn in soil and grain and soil properties including pH were determined. In general, long‐term N or P fertilization did not increase grain Cd, grain Zn, or soil Cd. In part, N and P fertilizer did not increase grain Cd because fertilizer did not increase soil Cd or Zn. Nitrogen fertilizer decreased soil pH in two experiments but these decreases were small (≤0.5) and did not affect grain Cd or Zn. Grain Cd and Zn were inversely related to soil pH, but not related to N or P fertilization. The relationship between soil pH (3.8 to 6.8) and grain Cd (9.7 to 45.2 µg kg−1) was described by a plateau‐linear‐plateau model with a negative slope from soil pH 5.0 to 6.4. The largest soil Cd and Zn contents were associated with high pH values, but grain Cd and Zn were inversely related to soil Cd and Zn. The maximum grain Cd content (45 µg kg−1) determined in this study was less than maximum limits of 50 to 100 µg Cd kg−1 in wheat grain established in other countries.
Biogeochemical Cycling in Coniferous Ecosystems on Different Aged Marine Terraces in Coastal Oregon
Authors: Bockheim J. G. , Langley‐Turnbaugh S. 
Published: July 2010

AbstractBiogeochemical cycling was studied in Sitka spruce [Picea sitchensis (Bong.) Carr.] and western hemlock‐Douglas‐fir [Tsuga heterophylla (Raf.) Sarg.‐Pseudotsuga menziesii (Mirbel) Franco] ecosystems on chronosequence of five uplifted marine terraces in coastal Oregon. The terraces occur 0.25 to 8.6 km from the Pacific Ocean and range from 80 to ∼500 kyr in age. The soils are highly weathered and include Inceptisols on the youngest terrace and Spodosols with clay‐enriched horizons and Ultisols on the older terraces. Bulk precipitation, throughfall, and soil solutions (four depths) were collected monthly from November 1992 through April 1993. The solutions were analyzed for pH, dissolved cations (Na, Mg, Ca, K, Fe, Al, and Si), anions (Cl, SO4, HCO3, NO3, and PO4), and organic C. Cations (µmolc L−1) in all solutions were ranked: Na > Mg > Ca ≥ K > H; anions were ranked: Cl > SO4 > NO3 >> HCO3. The Na/Cl ratio in all solutions was comparable to that of seawater. The mean sums of cations and anions in all solutions declined sharply with distance from the coast. Throughfall enrichment of all ions suggests that aerosol impaction of sea salts is a dominant process within the coastal fogbelt of Oregon. In that the soils have low inherent fertility, the trees appear to obtain Ca, Mg, K, and S primarily from atmospheric sources. These nutrients are utilized by abundant fine roots in the forest floor and upper 5 to 20 cm of mineral soil. Net cation loss is less than in other areas of the Pacific Northwest and is controlled by organic anions rather than the bicarbonate anion.
Nitrogen Cycling in Piedmont Vegetated Filter Zones: I. Surface Soil Processes
Authors: Verchot Louis V. , Franklin E. Carlyle , Gilliam J. Wendell 
Published: July 2010

AbstractSurface runoff is a major transport mechanism for particulate‐bound and dissolved N species from agricultural fields. One means of reducing nutrient loading in surface waters is the use of vegetative filter zones. The objective of this study was to evaluate the effectiveness of two forested filter zones (FFZ) for removing N from runoff in the Piedmont region of North Carolina. We used a spreading device to ensure dispersed flow in the FFZ. In addition to measuring inputs and outputs from each FFZ, we characterized the N cycle in the surface 30 cm of the soil profile to determine the fate of different N species retained in the FFZ. N loading increased as water passed through FFZ1: NO3‐N increased by 1.6 kg ha−1 yr−1, organic‐N increased by 13.4 kg ha−1 yr−1 and NH4‐N decreased by 0.2 kg ha−1 yr−1. The second FFZ was more effective with net retention of 0.2 kg ha−1 yr−1 for NO3‐N, 0.5 kg ha−1 yr−1 for organic‐N and 0.2 kg ha−1 yr−1 for NH4‐N. The FFZ were ineffective during the winter and spring when water filled pore space exceeded 35% in FFZ1 and 25% in FFZ2, and infiltration was low. Infiltration was the key factor controlling N pollutant removal from surface runoff. Therefore, the clayey soils of the Piedmont may not be as effective as the sandy coastal plain soils studied by other authors. Results from the analysis of the N cycle suggest that both uptake by the vegetation and leaching to deeper soil layers were the dominant fates of inorganic‐N.
Potential for Localized Compaction to Reduce Leaching of Injected Anions
Authors: Baker J. L. , Laflen J. M. , Schreiber M. M. 
Published: July 2010

AbstractNitrate‐nitrogen (NO3‐N) frequently is found in subsurface drainage waters from N‐fertilized cropland at concentrations exceeding 10 mg L−1, the drinking water standard. In this laboratory study, localized compaction during bromide (Br) application was studied as a potential method to reduce concentrations of anions such as Br− and NO−3 in water percolating from the top 30 cm of soil. Rainfall simulation was used to apply water under controlled conditions to undisturbed 76 by 76 by 30 cm deep soil columns taken from chisel‐plowed and no‐till fields in the fall after soybean [Glycine max (L.) Merr.] harvest. Potassium bromide at 149 kg ha−1 was broadcast or point injected with, or without, compaction around the point of injection. There were no significant differences in water volumes percolating through the columns, but concentrations and losses of Br in drainage water for the compacted point injection treatment were significantly less than those in drainage water from soil columns for point injection without compaction or broadcast application. The average Br concentration for no‐till compacted point injection was about 11% of the broadcast and 7% of the uncompacted point injection. For the chisel plow, the concentration for the compacted point injection was about 15% of both the broadcast and uncompacted point injection. Losses were also of about the same percentages. Localized compaction around the point of injection significantly reduced anion leaching in these undisturbed soil columns. This concept could be implemented in the field through design of applicators that compact the soil in a zone around either point‐injected or knifed‐in fertilizer.
Transport and Photolysis of Pentachlorophenol in Soils Subject to Evaporating Water
Authors: Donaldson Susan G. , Miller Glenn C. 
Published: July 2010

AbstractPentachlorophenol (PCP) was applied to loamy sand and sandy clay loam soils to determine the effect of upward evaporative flux on the rates of photolytic loss. Subirrigated soil columns were irradiated by ultraviolet lamps or sunlight to measure relative rates of photolytic loss under differing soil moisture regimes. Photolysis was initially rapid in loamy sand soil under near‐saturated flow conditions, with up to 55% more lost in light‐exposed treatments in 14 d as compared to dark controls. Rates of transport were slower in sandy clay loam soil, reflecting a soil sorption distribution coefficient of 10 mL/g, as compared to 0.4 mL/g in the loamy sand. Despite slower upward movement, similar amounts of photodegradation of PCP had occurred in the sandy clay loam soil after 14 d. Dropping the water table to the 15 or 25 cm depth resulted in unsaturated flow and increased losses to volatilization, with a much lower relative contribution of photodegradation over the course of the experiments. Up to 77% was lost from the loamy sand soil dark treatments during the 14‐day period, due to volatilization and irreversible sorption. Processes that translocate PCP into the sunlit surface zone under near‐saturated soil moisture conditions can be expected to enhance rates of photolytic loss while minimizing volatilization.
Determination of Total Dissolved Phosphorus in Soil Solutions
Authors: Rowland A. P. , Haygarth P. M. 
Published: July 2010

AbstractSoils are increasingly acknowledged as a source of P discharges in surface water. In order to monitor the transfer processes from soil to streams and rivers, a simple, sensitive, accurate, and robust method is required to determine trace concentrations of total dissolved P (TDP) in soil solution. This matrix provides a unique challenge to the analyst because it often contains trace concentrations of P in the presence of higher concentrations of organic and colloidal fractions that can interfere. Leachate waters were collected from lysimeter experiments covering 10 different soil types from the UK, ranging from sandy lowland agricultural grassland soil to an upland natural peaty gley soil, to critically evaluate the performance of different methods of analysis. Solutions of model compounds also provided measures of performance. Three methods involving digestion and colorimetric determination and one direct instrumental method were assessed. Methods evaluated were a mild digestion (persulfate), two rigorous oxidation procedures (peroxide‐Kjeldahl and nitric acid‐sulfuric acid) and inductively coupled plasma‐optical emission spectrometry (ICP‐OES). The ICP‐OES lacked the sensitivity to determine P concentrations below 100 µg L−1. Nitric acid‐sulfuric acid, a multi‐staged procedure, gave erratic recovery and was vulnerable to contamination. The best method for the analysis of soil solution or leachates was the acidified persulfate digestion because it produced reliable and accurate data. Thus we recommend that acid persulfate digestion is used to determine TDP in soil solution.
Sterile and Nonsterile Degradation of Carbon‐14‐Primisulfuron in Soil from Four Depths
Authors: Miller J. L. , Wollum A. G. , Weber J. B. 
Published: July 2010

AbstractThe degradation of 14C‐primisulfuron (2‐[[[[[4,6‐bis(difluoromethoxy)‐2‐pyrimidinyl]amino]carbonyl]amino]sulfonyl] benzoic acid) was monitored for 2 mo using soil microcosms under sterile and nonsterile conditions. Both chemical and biological degradation was detected. The half‐life was 2.1 wk for nonsterile samples from 0 to 5 cm, and 3.4 wk for nonsterile samples from 20 to 25 cm. After 7 wk, bound residues accounted for 48 and 27% of the recovered radioactivity in these samples, respectively. For sterile samples from the same depths, the half‐life was >7 wk and bound residues accounted for 7% of the recovered radiolabel. Disappearance and bound residue formation of primisulfuron were similar for both sterile and nonsterile samples from deeper in the profile (45–75 cm) indicating little biological degradation occurred in these subsurface samples. Chemical and microbial degradation of primisulfuron appeared to differ; the same metabolites were produced but at different times and in different amounts. Very little 14CO2 (<3%) was produced from any sample. These results indicate that initial hydrolyzation of the sulfonylurea bridge occurs both chemically and biologically, but does not occur readily in the subsoil. This may have implications for the prevention of groundwater contamination and for the bioremediation of contaminated soils.