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To evaluate the American College of Rheumatology (ACR) starter set of quality measures for rheumatoid arthritis (RA) in an actual patient cohort that preceded publication of the quality measures.We retrospectively applied the 2006 ACR quality criteria to a prospectively studied cohort of 568 patients with RA treated by 1,932 unique physicians including 255 different rheumatologists between the years 1999 and 2003. Data on performance were obtained from self‐report surveys and medical record review within 12 months.At least 1 joint examination was performed in 98% of patients. Patient and physician global assessments were reported for 79% and 74% of patients, respectively. A total of 85% of patients received disease‐modifying antirheumatic drugs (DMARDs). DMARD adjustments were made for 50% of patients in whom increasing disease activity was noted at least once and for 64% of patients in whom increasing disease activity was noted during 2 (of 4) 3‐month periods within the year. Compared with self‐report surveys, medical records substantially underreported performance on quality measures.The ACR‐endorsed quality measures for RA can be assessed using available data sources. When both self‐report and medical record data are used, adherence rates, designed to serve as minimum standards of care, were moderate or high for most measures. Prior to using indicators to compare quality across groups, specific strategies for operationalizing measures and for using accurate data sources to assess adherence to the measures should be defined.

To construct quality measures with measurement validity and meaning for clinicians.We conducted a prospective cohort study of rates of change in disease‐modifying antirheumatic drug (DMARD) and/or systemic corticosteroid drug or dose for 568 patients with rheumatoid arthritis (RA) across 6,159 clinical encounters within 12 months to examine how changes in clinical specifications change adherence.Rates of DMARD change were sensitive to specifications regarding the intensity of disease activity (severe or moderate), duration of specified disease activity, and length of the observation period. Over 12 months, the proportions of 377 patients with severe disease activity observed for 1‐month, 2‐month, and 3‐month time blocks who had a change in DMARD drug or dose were 36%, 57%, and 74%, respectively. Over 12 months, a change in DMARD drug or dose was observed for 44%, 50%, and 68% of 377 patients with severe disease within 3 months, 6 months, and 12 months, respectively, of the patient meeting criteria for severe disease activity. A change in DMARD drug or dose was observed for 21%, 23%, and 34% of 149 patients with moderate disease activity within 3, 6, and 12 months, respectively, of the patient meeting criteria for moderate disease activity.Rates of pharmacologic interventions for patients with moderate and severe RA disease activity vary substantially by intensity and duration of disease activity and by duration of period for observing change. Lack of precision in explicit process criteria could substantially mislead comparisons of quality of care across comparison groups.

The present study focused on understanding the sorption characteristics of acridine (AcN) and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in this article show that the degree of sorption of NHCs on phyllosilicates was dependent on the nature of the participating sorbates and sorbents. Sorption of the selected NHCs was pH-dependent, with maximum sorption occurring at low pH conditions, especially at pH < pKa of the NHC. Though sorption of the cationic forms of the NHCs on clays was preferred, neutral, zwitterionic, and anionic species of NHCs also sorbed on the clay surfaces. Spectroscopic studies have shown that sorbed NHC molecules formed clusters on clay surfaces, which acted as templates for molecular aggregation. Finally, we have also found that the clay surfaces promoted protonation of neutral AcN molecules at low sorbate concentrations.

Vertically oriented earthworm burrows exist in many agricultural sites, especially in no‐tillage soils where the burrows are left intact from year to year. Earthworm burrows can function as preferential flow conduits and may enhance downward transport of surface‐applied pesticides. Earthworm activity induces changes in the soil characteristics of the burrow walls that may affect pesticide sorption and transport. Little information is available describing the properties of the lining material. Earthworm (Lumbricus terrestrisL.) burrow lining and bulk soil at seven depth intervals from 0 to 50 cm were characterized with respect to pH, clay content, total organic C (TOC), water‐soluble organic C (WSOC), and alkaline phosphatase (AP) activity. Atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] sorption‐desorption isotherms were conducted on the same materials. Burrow linings were found to have a narrower range of pH and clay content than the bulk soil within the 0‐ to 50‐cm depth. Levels of TOC and WSOC in burrow linings were two to three times higher than in the bulk soil at the profile surface. This difference increased to eight times at the 35‐cm depth although concentrations were lower than at the profile surface. Activity of AP in burrow lining from 0 to 20 cm was three times greater than in the surface bulk soil, and at depths of 20 to 40 cm AP activity in burrow lining was similar to that of the surface bulk soil. Freundlich Kfvalues for atrazine sorption and desorption were higher for burrow lining than bulk soil at almost every depth. The largest differences (1.5‐ to 3‐fold) occurred in the 15‐ to 30‐cm depth range. Multivariate regression analysis of atrazine sorption‐desorption indicated that of the parameters measured, TOC could account for most of the variability in atrazine sorption‐desorption.

A lysimeter study was conducted at the Ohio State University Turfgrass Research Center, Columbus, to investigate NO3‐N leaching losses from fertilized turfgrass. Nitrogen fertilizer treatments were applied to ‘Baron’ Kentucky bluegrass (Poa pratensisL.) seeded and sodded turf established on a Miamian silt loam (fine, mixed, mesic Typic Hapludalf). Treatments included two N sources, urea and resin‐coated urea (RCU); and Two fertilization programs, one that emphasize spring and summer applications (SSF) and the second program that included a late season application (LSF). Both the SSF‐ and LSF‐fertilization programs received 218.2 kg N ha−1yr−1. The NO3‐N leachate concentrations from seeded turfgrass exceeded those from sodded turf for the first 3 mon. As the turf matured, NO3‐N losses from sod exceeded NO3‐N from the seeded plots. Leachate concentrations were 1.1 and 3.5 mg NO3‐N L−1for seed and sod turf, respectively, from April 1990 through March 1991. Less rooting in the sodded plots resulted in greater N loss. Annual NO3‐N losses were not affected by N source. During the winter of 1991, significantly (P= 0.05) higher percolate NO3‐N concentrations were recorded from urea‐treated plots (3.66 mg NO3‐N L−1) vs. RCU (2.10 mg NO3‐N L−1), however. Similarly, N programs did not result in annual differences in percolate concentration, but differed during the winter of 1991. Concentrations were 3.37 and 2.39 mg NO3‐N L−1for LSF and SSF, respectively. The NO3‐N leaching losses from all treatments exceeded the maximum concentration limit (MCL) early in the study. These high concentrations were caused by soil disturbance during establishment. During the 2nd yr, NO3‐N leaching results were more representative of typical turfgrass situations with mean annual flow‐weighted NO3‐N concentrations well below the MCL. Different N sources and fertilizer programs did not result in greater NO3‐N percolate losses compared to unfertilized turfgrass plots.

The sorption of Co(II), and Cu(II), and Mn(II) by the manganese oxide birnessite, was studied at pH 3.3 to 8.9 to ascertain the mechanisms responsible for heavy metal induced releases of Mn from MnO2. Cobalt sorption resulted in a release of Mn to solution and the presence of Mn(II) on the oxide surface. Manganese releases during Cu addition only occurred if Mn(II) was present on the oxide prior to Cu sorption. The simultaneous sorption of Co + Cu resulted in greater releases of Mn than were observed during Co sorption alone. In all cases, Mn release was found to increase with decreased pH. It is suggested that Mn releases during Co(II) sorption result not only from the oxidation of Co(II) to Co(III), but also from a direct exchange of Co(II) for Mn(II) produced during the redox reaction.

Suspensions of a synthetic manganese oxide, birnessite, were treated with Fe(II), nitrite, glutamic acid and a water soluble sewage sludge extract, to study the effect of these reductants on Mn released by Cu sorption. In all cases, oxidation of the reductant was thought to result in a reduction of solid phase Mn(III) or Mn(IV), to Mn(II). In each instance, Mn(III) or Mn(IV) reduction was accompanied by an increase in suspension pH. In the case of the nitrite treatment, the observed ratio of Mn(II) formed to nitrate produced suggested that nitrite oxidation resulted from the reduction of Mn(IV). The production of Mn(II) and NH+4in the glutamic acid‐treated birnessite suspensions was attributed to direct, chemical, oxidative deamination of glutamic acid by the manganese oxide. The greatest releases of Mn(II) were observed when Cu sorption occurred subsequent to the exposure of the oxide suspensions to the reductants, but Mn(II) was also released during the simultaneous applications of the reductants and Cu. The presence of Cu always resulted in larger releases of Mn than were observed in the absence of Cu. No Mn(II) was released by Cu sorption on untreated oxide. These surface reduction and metal ion sorption reactions may be responsible for changes in Mn(II) solubility following the addition of heavy metals to soils.

Chemical and physical fractionation techniques were used to study the effects of organic and conventional management practices on soil organic matter (SOM) characteristics. We isolated SOM from: (i) organic animal‐based, manure‐amended (ORG‐AN), (ii) organic cash‐grain‐based, cover cropped (ORG‐CC), and (iii) conventional, cash‐grain‐based (CONV) rotations. We quantified the total C and N contents of humin (HN) and humic substances (HS), and light (LF), heavy (HF), fine organo‐clay, and organo‐sand fractions. Management changed the quantity and distribution of C and N in physically and chemically isolated fractions. The ORG‐CC soil had significantly greater quantities of C in its HN, HS, LF, and HF fractions than the CONV soil. Management impacted the distribution of C and N only in the LF fraction. The ORG‐CC had a larger percentage and proportion of C and N in its LF than the other soils. The percentage of soil N in HS was higher in the ORG‐AN and ORG‐CC than in the CONV soil. Even though the quantity of N in the CONV's HN equaled the other soils, it had the highest percentage and proportion of N allocated to this fraction. Farming systems did not significantly alter the C and N contents of HS or the quantity of C associated with selected particle‐size fractions; however, the C content of fine clay isolated from aggregated soil was significantly greater than the C content of clay isolated from loose soil. By isolating macroorganic matter (LF) in concert with HS and HN fractions, we were able to assess management practice impacts on SOM characteristics.

Diffuse reflectance Fourier transform infrared (DR‐FTIR) spectroscopy was used to investigate the effects of organic and conventional management practices on soil organic matter (SOM) chemistry. We characterized physically and chemically isolated SOM fractions collected from Rodale's Farming Systems Trial (FST) experiment and used ratios of reactive (O‐containing) and recalcitrant (C, H and/or N) functional group heights to characterize SOM fraction composition. Based on peak ratio comparisons, we determined that humic acid (HA) in the manure‐amended organic rotation was more reactive than HA isolated from crop‐residue‐amended soils. Reactive/recalcitrant (O/R) peak ratios indicated that fulvic acid (FA) and particulate organic matter or light fraction (LF) isolated in April were most reactive in the organic cash‐grain‐based rotation. By June LF reactivity had changed; O/R ratios of LF and litter (LT) fractions isolated from the conventional and organic cash‐grain soils were greater than the manure‐amended soil's ratios. We did not draw any conclusions about management impacts on SOM composition from spectra of fine‐clay‐(FC) and sand‐ (S) sized fractions. Using DR‐FTIR we were able rank SOM fraction reactivity; average O/R ratios were FA > LT > HA > LF > FC. No consistent link between SOM fraction O/R ratios and reported C/N ratios or biological availability was made. Humic acid O/R ratios were most consistent with other estimates of overall SOM biological activity. More research is needed to clarify the relationship between the composition of specific SOM fractions and their functional significance in mineral soils.

Organic management practices and mixed‐crop rotations have beneficial impacts on biologically active soil organic matter (SOM); however, the specific impacts of these practices on SOM composition and turnover characteristics are not known. The effect of organic and conventional management on soil C cycling was assessed using soils collected from Rodale's Farming Systems Trial experiment, which included organic‐manure amended, organic‐legume cover cropped, and conventionally managed‐inorganically fertilized farming systems. Soil respiration rates, atom % 13C, and cross polarization 13C nuclear magnetic resonance (CP‐MAS 13C NMR) were used to trace the fate of 13C‐labeled acetate added to soils incubated for 2 and 13 wk. Microbial activity and C turnover rates were initially greater in the manure‐amended soil than in the other two soils. Acetate mineralization lagged in the cover‐cropped soil during the first 2 wk. Low atom % 13C in the conventional soil showed that, even though its soil respiration rates, and therefore overall microbial activity, equaled rates in the cover‐cropped soil, microorganisms present in this soil metabolized significantly more of the applied acetate. By the end of the experiment, C cycling characteristics of the cover‐cropped soil were similar to the manure‐amended soil; NMR spectra indicated 13C was incorporated into new SOM in both of these soils. Soil respiration and 13C assimilation rates in the conventional soil remained relatively low. Microorganisms in the organic soils mineralized and respired more native C and assimilated more 13C than the conventional soil. Conversely, the conventional soil mineralized more and assimilated less 13C than the organic soils. Differences observed in this laboratory experiment may or may not reflect on C cycling occurring in the field.

Field trials in Ohio have shown that the Bray‐1 P soil‐test level for optimum corn (Zea maysL.) production is greater for no‐till than for conventionally (moldboard plow) tilled corn. Studies using Hoytville silty clay loam (fine, illitic, mesic Mollic Ochraqualf) and Canfield silt loam (fine‐loamy, mixed, mesic Aquic Fragiudalf) taken from long‐term no‐tillage plots indicated decreased retention of P against the Bray‐1 extractant in surface soils, compared with samples from deeper within the soil profile. In an effort to further examine the P‐retention characteristics of no‐till soil profiles, experiments were prepared using P‐sorption isotherms, before and after a series of sequential anion resion extractions. Prior to sequential extractions, the isotherms showed decreased sorption of P at the soil surface (0–2 cm), compared with deeper soil layers. Resin extraction removed more P from surface layers than deeper depths, and the quantity of P removed with each extraction declined much more quickly in the surface layers than in lower depths. After resin extraction there was a trend for greater retention of P against the Bray‐1 extractant in the upper soil layers. Sorption isotherms created after resin extraction show increased P sorption at all depths and closer agreement between the shape of the isotherm curves. It appears that accumulated P on the soil surface saturates P fixation sites, resulting in differential retention of P with depth.

Data is limited on the mineralogical characteristics and formation mechanisms of P‐bearing solids that occur in soils due to P fertilization. This study was conducted to characterize, isolate, and infer formation mechanisms for P‐rich particles found in two excessively fertilized soils. Phosphorus‐rich particles were described in terms of morphology, elemental composition, and crystallinity using electron optical techniques. These particles were found in the <2.2 Mg/m3density separates from the clay fractions of a Plainfield loamy sand (mixed, mesic Typic Udipsamment) and Blount silt loam (fine, illitic, mesic Aeric Ochraqualf) that had been excessively fertilized for more than 20 y. Particle morphologies indicated that the P‐rich materials exist as discrete particles as well as coatings on other particles. The elemental composition of the particles varied within as well as between particles. Phosphorus concentrations in the P‐rich materials ranged from 5.6 to 27.2% per mole of cation (mole cation%). Aluminum and Si were the dominant elements associated with P, while Ca, Fe, and Mn generally were present at low concentrations. The P‐rich materials were amorphous to electron diffraction and can generally be described as an amorphous mixed Al‐Si‐P substance. An analogy was made between the P‐rich materials, the amorphous analog of variscite, and allophane.

Eleven samples representing six soil series were selected for this study of excessively fertilized soils. Phosphorus sources included fertilizers, sewage sludges, and manures. The samples had Bray Pl extractable P levels ranging from 29 to 640 mg P/kg and 1:1 soil/water pH values ranging from 5.4 to 7.4 The equivalent of 25 g of dry soil and 50 mL of water were incubated at 298K. Samples were sacrificed for analysis periodically during the 130‐d test period. The activities of most ions, as estimated with GEOCHEM, were relatively constant throughout the course of the experiment. The concentrations of organic and inorganic C for samples that had been amended with sewage sludges or manures varied considerably during the course of the experiment. Samples that produced high supernatant pH values (>6.8) generally were more soluble than hydroxyapatite and less soluble than octacalcium phosphate and were slow in attaining constant ion activity products relative to the Ca phosphate minerals considered. Samples that produced low supernatant pH values (<6.8) indicated an equilibrium with the amorphous analog of variscite throughout the experiment.

There has been little success with direct methodologies in isolating or characterizing phosphate minerals or P‐bearing solids in soils, due primarily to the fact that P solids represent a relatively minor component of the soil matrix. This study was conducted to evaluate a method for concentrating P in soils and to characterize P‐solids phases by a variety of direct mineralogical methods. Eleven soil samples representing six soil series from Illinois, Michigan, Wisconsin, and New York were fractionated according to particle size, with the clay‐sized fractions being further separated into the density ranges of <2.2, 2.2 to 2.5, and >2.5 Mg/m3. The density separates were examined by scanning transmission electron microscopy in conjunction with energy dispersive x‐ray analysis, x‐ray diffraction (XRD), and Fourier‐transformed infrared (FTIR) spectroscopy. Total P concentrations were generally highest in the clay‐sized fractions, compared with the sand‐ and silt‐sized fractions, and always highest in the lowest‐density separates, compared with the remaining two density fractions. Discrete P‐rich particles were found in most density separates, with the highest abundances occurring in the < 2.2 and 2.2 to 2.5 Mg/m3fractions. Particles generally contained detectable quantities of Al and Si and various combinations of K, Ca, and Fe. Phosphorus concentrations within individual P‐rich particles were highly variable. Analysis of the density separates with XRD and FTIR spectroscopy was not successful in identifying discrete P minerals.

The sorption of heavy metals in soil may result in the release of protons or other metal cations. Manganese release to soil solution has been observed with the addition of certain heavy metals to soil. In this study Ni, Cu, and Cd in Na salt solutions of Cl−and ClO4−were leached through soil, and the effluents analyzed. Peak or pulse increases in the Mn concentration were coincidental with appearance of Ni, Cu, or Cd in the effluent. Increased Na salt concentrations resulted in increased Mn release, even though the amount of heavy metal sorbed decreased. Copper treatments produced a decreased effluent pH, which probably accounted for some of the released Mn. Nickel and Cd treatments, on the other hand, resulted in slight or no significant effluent pH decrease. Several possible mechanisms are introduced that could account for Mn release. It is most probable that proton release with Ni, Cu, or Cd sorption accounts for most of the Mn release.

Fertilizer use efficiency of K can be low in soils that adsorb K+in a nonexchangeable form. Simultaneous proximal injection of anhydrous ammonia (AA) and KCl solution in such a soil, however, has been shown to increase exchangeable and solution K+. In order to better understand the mechanisms for this effect, the exchange of K and Ca in a Hoytville silty clay loam soil (fine, illitic, mesic Mollic Ochraqualf) previously injected with AA was investigated across dimensions of distance and time from the point of AA injection. Data for both soil adsorbed and equilibrium solution K and Ca were obtained directly. Exchange isotherms and calculated Vanselow selectivity coefficients showed K selectivity was decreased near the point of AA injection and this effect diminished with increasing distance and time from the injection point. The greatest changes in selectivity occurred near the K end member of the exchange isotherms. Total adsorbed metal charge (Q) was increased by AA injection and the increase in Qwas greatest near the Ca end member of the isotherms. This evidence suggests that (i) pH increases with AA injection temporarily increased the Ca selectivity of the soil organic fraction, giving a decrease in total soil K selectivity, and (ii) direct interactions between K+and NH+4on mineral surfaces had little effect on K selectivity.

Quinoline is an N‐containing heterocyclic contaminant associated with creosote wastes and may be biologically degraded under aerobic and anaerobic conditions. Quinoline‐degrading bacteria were utilized to investigate the rate of quinoline desorption from smectite clay at low surface concentrations and its subsequent mineralization. Fluorescence spectroscopy and 14C‐quinoline mineralization techniques were used to compare the observed desorption rates to mineralization rates. Microbial utilization was desorption‐rate limiting. Desorption and microbial utilization may be modeled as pseudo‐first‐order reactions whose first‐order rate constant (kobs) is independent of surface concentration. The difference between quinoline disappearance from solution and from the clay surface as observed by fluorescence spectroscopy was comparable to the difference between microbial utilization of the solution and the surface‐bound species. The utilization of quinoline from solution was about 30 times more rapid than surface‐bound quinoline. The surface‐bound species appeared to be protected from microbial attack and, hence, desorption was required prior to utilization. The desorption process is suggested to be a chemical‐reaction‐controlled process rather than film diffusion controlled, as is typically suggested for an exchange process. The biotransformation of quinoline to 2‐hydroxyquinoline, observed in solution by fluorescence spectroscopy, was about five to eight times faster than the subsequent disappearance of 2‐hydroxyquinoline. When quinoline was sorbed, however, no 2‐hydroxyquinoline was observed in solution or on the surface of the clay. It is suggested that quinoline may be transformed to 2‐hydroxyquinoline at the cell surface and that 2‐hydroxyquinoline is the species that is transported into the cell prior to further degradation.

The interaction of imazaquin (2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐3‐quinolinecarboxylic acd) and imazethapyr ((±)‐2‐4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐ethyl‐3‐pyridinecarboxylic acid) with clay suspensions and humic acid was studied using a batch equilibrium method and by fluorescence emission spectroscopy. The objectives of this study were to: (i) determine the effect of different sorbents and pH on the sorption of imazaquin and imazethapyr, and the hysteresis in adsorption‐desorption isotherms, and ii) evaluate the effect of pH on the mechanisms of imidazolinone herbicide sorption by specimen hectorite. Sorption of both herbicides increased as pH decreased, but the increased sorption was most evident as soil pH decreased from 5 to 3. Illite and kaolinite, which exhibit more pH‐dependent charge characteristics and less total surface area than hectorite, can impart important adsorptive character to soil, especially with regard to imazethapyr. Humic acid had much greater affinity for both herbicides than clay did, indicating that organic matter content could be a major factor controlling the sorption of these herbicides in soils. The rate of desorption varied among absorbents and between herbicides; imazethapyr desorbed more readily than imazaquin from most adsorbents. The results of fluorescence emission spectroscopy indicated that imazaquin and imazethapyr molecules were protonated and sorbed on the clay surface under acidic conditions. The extent of protonation was greater in the clay suspensions than in clay‐free solutions.

Ochreous precipitates and associated solutions were collected from waters draining abandoned coal works at 28 locations in eastern Ohio. Major and trace element contents of the precipitates were determined, and comparisons were made with source solutions to evaluate the effects of pH, organic C, and ionic strength on solid‐phase composition and trace metal distribution. The pH and calcalated ionic strength of the effluents ranged from 2.6 to 7.8 and 6 to 106 mmol L−1, respectively. Associated precipitates consisted primarily of poorly crystallized oxides and oxyhydroxides of Fe with jarosite occuring as a major constituent of only one specimen. Mean Fe, SO4, Al, and Si contents of the precipitates were 8.7, 1.34, 1.11, and 0.25 tool kg−1, respectively. Silicon content increased with increasing pH of the source solution suggesting pH‐dependent adsorption. In contrast, SO4and Al appeared to be influenced both by precipitation and adsorption reactions. Partition coefficients for As, B, Ba, Co, Cu, Cr, Mn, P, and Zn showed a preferential accumulation of all elements by the solid phase with mean log Kdvalues ranging from 2.9 for Cu to 6.3 for As. Manganese, Co, and Zn all showed increased partitioning into the solid phase with increasing pH and decreasing ionic strength of the drainage waters. Copper appeared to be strongly associated with organic matter, and a weaker but positive relationship was also observed with Co and Zn. No effects of pH, ionic strength, or organic C were observed for any other trace elements. Solubility equilibrium calculations suggested that the solid phase concentrations of Co, Cr, Cu, Mn, Zn, and As were primarily controlled by adsorption and/or coprecipitation phenomena whereas Ba and P activities in solution exceeded the solubilities of barite and strengite, respectively.

In 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 focincreased. The addition of cosolutes to low focsystems (<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 focsystems (= 3 × 10−5) was due to an increase in effective focresulting 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 Kocvalues derived from Kowdata in low focsystems significantly underestimate the interactions of nonionic organic solutes with low organic C surfaces.

Carbon‐normalized distribution coefficients (Koc) of organic solutes appear to increase as the amount of organic C in a system decreases. This study was conducted to determine the effect of fractional organic C content (foc) on the sorption of anthracene and pyrene. Batch‐sorption experiments were conducted on reagent CaCO3, a geologic calcite, and a montmorillonite to measure anthracene and pyrene sorption. An organic C‐free mineral surface and two surface loadings of humic acid (HA) were evaluated. The Kocof anthracene and pyrene varied with focas well as with the underlying mineral surface. The sorption of anthracene and pyrene to all HA‐mineral complexes increased with increases in foc, while Kocfor the compounds decreased. In higher focsystems (>3 × 10−5), isotherms were C‐type curves indicative of partitioning. In lower focsystems (<3 × 10−5), isotherms were commonly L and S‐type curves indicative of adsorption and condensation. Sources of potential experimental artifact examined were loss of HA from the mineral surface to solution, dissolution of CaCO3during the experiment, and loss of NOS to experimental glassware or volatilization. None were found to contribute to the observations made. Our results suggest that adsorption‐condensation of pyrene and anthracene created more surface excess than predicted by partitioning alone as evidenced by the large experimental Kocvalues obtained.

Specific impacts of organic management practices on soil organic matter characteristics have not been documented. This study tested how organic management practices influence soil fertility by investigating whether 10 yr of organic or conventional management generated differences in biologically active soil organic matter (SOM) pools at the Rodale Institute Research Center's long‐term Farming Systems Trial experiment (FST). The experiment included an organically managed rotation that was animal based, an organic treatment that was cash‐grain based, and a conventional cash‐grain‐based rotation. The biologically active SOM matter pools of the three FST treatment soils were compared through characterization of soil CO2evolution, available inorganic N pools and N mineralization rates, water‐dispersible organic carbon (WDOC), and particulate organic matter (light fraction). Soils receiving the organic treatments accumulated biologically active C. Accumulated organic matter in the manureamended soil was the most labile whereas the cover‐cropped soil accumulated the most organic matter overall. In the cover‐cropped soil, higher total C and N, particulate SOM, and reduced WDOC contents indicated that its SOM was more stable than SOM in the other two treatment soils. The conventionally managed soil had the lowest biological activity (N supply and soil respiration rates) and did not accumulate SOM during the 10‐yr experiment. Assays that characterize particulate organic matter emerged as the best indices of biologically active SOM because they documented important quality (i.e., biological lability) and quantity aspects of SOM character in the Rodale FST soils.

Previous studies have attributed hydrophobicity in sandy soils to alkaline extractable macromolecular complexes, as well as lipid fractions, but have not included wettable soils for comparison. Our study was conducted to compare the alkaline‐extractable and lipid fractions of a nonwettable soil to a wettable soil from creeping bentgrass (Agrostis stoloniferaL. var. stolonifera) sand greens. Samples were collected from two sites and several extraction sequences performed on each. Humates were extracted in 1.25 mol L−1NaOH. Alkaline‐extractable fractions were separated by precipitation with 6 mol L−1HCl. Acid precipitated and nonprecipitated fractions were purified, lyophilized, and analyzed by Fourier transform infrared spectroscopy. In addition, the acid nonprecipitated fractions, which included fulvic acids, were analyzed by solid‐phase 13C nuclear magnetic resonance spectroscopy. Lipid fractions were extracted with a soxhlet apparatus using either hexane or methanol as solvent. Lipid fractions were analyzed by gas chromatography‐mass spectroscopy. No qualitative differences were observed with Site 1 extracts, and it appeared that hydrophobicity may have been at least partly due to physical or structural differences. Qualitative differences were observed with Site 2 extracts when initially extracted with methanol.

Abstract:  The purpose of this work was to assess the influence of redox conditions on benzoate biodegradation coupled with oxygen and nitrate as electron acceptors. A benzoate-degrading, facultatively denitrifying bacterium was isolated from a sediment sample and was tentatively identified as Comamonas terrigena (strain J92-6). The experimental system was based on sand columns that were filled with liquid medium containing benzoate and nitrate. The columns were inoculated to provide a fixed biofilm on the sand. Conditions were created by aeration, dinitrogen-purging, and sodium sulfide amendment that comprised oxic, anoxic, and reduced (–375 mV) zones, respectively, at different depths of the columns. Anaerobic biodegradation of benzoate was nitrate-dependent and proceeded at all redox potential values ranging from +400 to –375 mV. Thus, benzoate degradation coupled with denitrification was not inhibited at low redox potentials characteristic of sulfate reduction and methanogenesis. The results demonstrate that the fixed biofilm column system can be successfully used to evaluate the influence of environmental factors on the biodegradation of benzoate, a central decomposition product of anaerobic, aromatic hydrocarbon biodegradation.

In many temperate region no‐tillage agro‐ecosystems, the vertically oriented burrows of the nightcrawler earthworm (Lumbricus terrestrisL.) function as preferential flow paths and may promote the rapid downward transport of surface‐applied chemicals. The burrows of nightcrawlers, however, are lined with a material that is enriched in organic C relative to the surrounding soil matrix that may affect transport of organic chemicals. Vie investigated the effect of this lining on the sorption and retention of four herbicides: atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N(2‐methoxy‐1‐methylethyl)acetamide], dicamba (3,6‐dichloro‐2‐methoxybenzoic acid), and primisulfuron [3‐[4,6‐bis(difluoromethoxy)‐pyrimidin‐2yl]‐1‐(2‐methoxy carbonylphenyl sulfonyl) urea]. Batch sorption isotherms were determined using burrow lining and bulk soil collected from seven depth intervals from 0 to 50 cm. Sorption of the more strongly sorbed herbicides (atrazine and metolachlor) was enhanced by a factor of up to three on burrow lining relative to bulk soil, while there was little or no enhancement of the weakly sorbed herbicides (dicamba and primisulfuron). Transport and retention of these herbicides was measured in intact burrows in undisturbed soil blocks. Concentrations of the two strongly sorbed herbicides decreased during flow through nightcrawler and artificial (unlined) burrows, with the largest decreases occurring in earthworm burrows. Concentrations of the two weakly sorbed herbicides decreased very little during flow through either type of burrow. Retained herbicide concentrations were higher in nightcrawler than in artificial burrow walls, and decreases in concentration from the surface to the second 1‐mm wall layer were greater in nightcrawler than in artificial burrow walls. These results indicate the material lining nightcrawler burrows may significantly retard herbicide transport during lateral flow into and out of burrows.

The adsorption envelope for selenite on two alluvial soils from the San Joaquin Valley, California, was investigated with respect to variations in solution composition. Sodium‐saturated soil pastes were mixed with solutions containing sulfate, phosphate, and Ca ions in a background electrolyte of 50 mol NaCl m−3. The effects of increasing chloride concentration were investigated at 100 mol NaCl m−3. No discernible change in the amount of selenite adsorbed was found as a result of increased chloride concentration or through the addition of 16 mmol Na2SO4kg−1. In contrast, an initial concentration of phosphate comparable to that of selenite resulted in a decrease of selenite adsorbed by approximately one‐half. The addition of 100 mol CaCl2m−3resulted in significant increases in selenite adsorption on both soils above pH 5, which could be attributed to precipitation or an increase of surface charge through Ca adsorption.

The adsorption of selenite by five alluvial soils from the San Joaquin Valley, California, was investigated with respect to the effects of soil composition and pH. Soil samples were prepared in the form of Na‐saturated pastes. Adsorption experiments were carried out in a 50 mol NaCl m−3background at initial selenite concentrations comparable with those found in natural soil systems. The samples were equilibrated under N2‐stirring in a constant‐temperature apparatus with pH and redox conditions monitored. Selenite adsorption by the soils decreased uniformly with increasing pH in the range 4 to 9 and was independent of soil series above pH 6.

Noncrystalline aluminosilicates termed allophane and imogolite are common constituents of spodosols, soils derived from volcanic ash, and many inceptisols. The surface charge characteristics of their synthetic analogues may be used to better understand their ion retention properties. In this study, we determined the point of zero salt effect (PZSE) by potentiometric titration of allophanes with Al/Si ratios of 1.12, 1.52, and 2.04 and of imogolite with an Al/Si ratio of 2.02. We also used microelectrophoresis to determine the point of zero charge (PZC) at the particle shear plane for the same materials in CI solutions of Li, Na, Cs, and tetramethyl ammonium. The PZSE decreased with decreasing Al/Si ratio for the allophanes, but the imogolite PZSE was much lower than that of the allophane with 2.04 Al/Si. The PZC was always higher than the PZSE of the same material, especially for imogolite. The results are best explained if cations reside within the hollow tubes of imogolite. This conclusion is supported by a fluorescence study that showed that only quenchers smaller than the inner diameter of the imogolite tube could fully quench Ce-imogolite.

Abstract:  The stimulatory effect of earthworms (Lumbricus terrestris L.) on soil microbial activity was studied under microcosm-controlled conditions. The hypothesis was tested that microbial stimulation observed in the presence of a soil invertebrate would be due to the utilization of additional nutritive substances (secretion and excretion products) that it provides. Changes in microbial activity were monitored by measuring simultaneously CO2 release and protozoan population density. The increase in CO2 released in the presence of earthworms was found to result from both earthworm respiration and enhanced microbial respiration. The stimulation of microbial activity was confirmed by a significant increase in protozoan population density, which was 3–19 times greater in the presence of earthworms. The respiratory rate of L. terrestris was estimated to be 53 μl O2 g–1 h–1. Earthworm respiration significantly correlated with individual earthworm weight, but there was no correlation between the increase in microbial respiration and earthworm weight. This finding does not support the hypothesis given above that enhanced microbial respiration is due to utilization of earthworm excreta. A new hypothesis that relationships between microbial activity and earthworms are not based on trophic links alone but also on catalytic mechanisms is proposed and discussed.

The sorption properties of Co, Cu, Ni, and Ca were studied in a mixed mineral suspension of synthetic MnO2and Wyoming montmorillonite. The distribution of the sorbed cations between the two solid phases was measured by indirect chemical fractionation with acidified NH2OH-HCl and by direct X-ray spectroscopic analysis of mineral particles using electron microscopy. Electron microscope and NH2OH-HCl measurements of the quantity of Co sorbed on MnO2agreed within 6%. Seventy-seven, 67, and 69% of the total Co, Cu, and Ni sorbed by the mixed mineral suspension was found on the manganese oxide. The opposite distribution was found for sorbed Ca with 28% on the manganese oxide and 72% on the montmorillonite particles. The observed differences in metal sorption by these minerals are related to the cation-sorption mechanisms of manganese oxide and montmorillonite. Изучались сорбционные свойства Со, Сu, Nі, и Са в суспензиях смешанных минералов-синтетической МnО2и вайомингского монтмориллонита. Распределение сорбираванных катионов между двумя твердыми фазами измерялось при помощи химического фракционирования с подкисленным NН2ОН-НСl и при помощи прямого рентгеновского спектрального анализа частиц минералов, используя электронную микроскопию. Результаты измерений количества Со, сорбированного на МnО2, при помощи электронного микроскопа и NН2ОН-НСl совпадали с точностью до 6%. Семьдесят семь, 67, и 69% общего количества Со, Сu, и Nі, сорбированных суспензией смешанных минералов, было обнаружено на двуокиси марганца. Противоположное распределение было обнаружено для сорбированного Са—28% на двуокиси марганца и 72% на монтмориллонитовых частицах. Наблюдаемые разницы в сорбции металлов этими минералами связаны с механизмами сорбции катионов двуокисью марганца и монтмориллонитом. [Е.G.] Es wurden die Sorptionseigenschaften von Co, Cu, Ni, und Ca in einer gemischten Mineralsuspension aus synthetischem MnO2und Montmorillonit von Wyoming untersucht. Die Verteilung der sorbierten Kationen zwischen den zwei festen Phasen wurde durch indirekte chemische Fraktionierung mit angesäuertem NH2OH-HCl und dutch direkte röntgenspektroskopische Analyse mittels Elektronenmikroskopie der Mineralteilchen gemessen. Elektronenmikroskopische und NH2OH-HCl-Messungen der an MnO2adsorbierten Co-Menge stimmten innerhalb von 6% überein. Es zeigte sich, daß am Manganoxid 77, 67, bzw. 69% der gesamten durch die gemischte Mineralsuspension adsorbierten Co-, Cu-, und Ni-Menge adsorbiert wurde. Die umgekehrte Verteilung wurde für das sorbierte Ca gefunden, wobei 28% am Manganoxid und 72% an den Montmorillonitteilchen adsorbiert waren. Die beobachteten Unterschiede bei der Metallsorption durch diese Minerale hängen mit dem Kationensorptionsmechanismus von Manganoxid und Montmorillonit zusammen. [U.W.] Les propriétés de sorption de Co, Cu, Ni, et Ca ont été étudiées dans une suspension de minéraux mélangés consistant de MnO2synthétique et de montmorillonite du Wyoming. La distribution des cations sorbés entre les deux phases solides a été mesurée par fractionation chimique indirecte avec du NH2OH-HCl acidifié et par l’analyse spectroscopique directe des rayons-X des particules minérales utilisant la microscopie électronique. Les mesures obtenues du microscope électronique et de NH2OH-HCl de la quantité de Co sorbée sur MnO2étaient à 6% pres. Soixante dix-sept, 67, et 69% du Co, Cu, et Ni total sorbé par la suspension de minéraux melangés ont été trouvés sur l’oxide de manganèse. Une distribution opposée a àté trouvée pour le Ca sorbé avec 28% sur l’oxide de manganèse et 72% sur les particules de montmorillonite. Les différences observées de sorption de métal de ces minéraux sont associées aux mécanismes de sorption de cations de l’oxide de manganése et de montmorillonite. [D.J.]