bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors Controlling Seasonal Nutrient Profiles in a Subtropical Peatland of the Florida Everglades
Authors: Koch‐Rose M. S. , Reddy K. R. , Chanton J. P. 
Published: July 2010

AbstractApproximately 75% of soil nutrients in the Everglades are stored in the organic form; thus, factors affecting seasonal organic matter and associated nutrient mineralization will influence nutrient availability to marsh vegetation. To assess the factors controlling mineralization in the field, pore water nutrients including NH+4, NO−3 and, soluble reactive P (SRP) were determined along with soil Eh, pH, temperature, and water levels at eutrophic, mesotrophic, and oligotrophic sites through a dry and rainy season. Indicators of anaerobic microbial activity, SO2−4, methane (CH4), CH4‐stable isotope signatures, and dissolved inorganic carbon (DIC) were sampled at all three sites. At the enriched site, SRP and NH+4 levels were 95 and 706 µM during summer months and 11 and 26 µM spring concurrent with N/P ratios of three and maximum macrophyte growth. Low seasonal variability in SRP was found at oligotrophic sites where pore water N/P ratios ranged from 39 to 551 throughout the year. During the spring dry season, Eh exceeded 300 mV at all three sites. In all other seasons, soils remained flooded and Eh averaged −100 to −200 mV. Methane and DIC, and isotopic 13C ratios in the eutrophic sites, relative to those found under oligotrophic conditions, suggest greater microbial production rates at enriched sites. Oligotrophic Everglades soils appear to have limited microbial activity and consequently, dampened seasonal pore water nutrient levels in response to fluctuating Eh, pH, water level, and temperature regimes.
In‐Situ Dissipation of Benomyl, Carbofuran, Thiobencarb, and Triclopyr at Three Soil Depths
Authors: Johnson W. G. , Lavy T. L. 
Published: July 2010

AbstractData are lacking concerning the persistence of pesticides used in Arkansas rice production. Studies were conducted to examine the dissipation characteristics in field studies of four commonly used pesticides. Crowley silt loam soil (fine, montmorillonitic thermic Typic Albaqualfs) from 2, 20, or 60 cm was treated with benomyl (methyl‐1‐(butylcarbamoyl)‐2‐benzimidazole‐2‐yl carbamate), carbofuran (2,3‐dihydro‐2,2‐dimethylbenzofuran‐7‐yl methylcarbamate), thiobencarb (S‐[(4‐chlorophenyl)methyl]diethylcarbamothioate), or triclopyr ([(3,5,6‐trichloro‐2‐pyridinyl)oxy]acetic acid), and buried in leaching or degradation containers for 0, 34, 104, 184, 280, 371, 736, or 1066 d at Stuttgart, AR. Degradation of carbofuran, thiobencarb, and triclopyr was more rapid than the benomyl metabolite MBC (methyl‐2‐benzimidazole carbamate) with the time for 50% of the initial dose to dissipate (DT50) being 94 d or less. The carbofuran metabolite 3‐keto carbofuran (2,3‐dihydro‐2,2‐dimethyl‐3‐keto‐benzofuranyl‐N‐methyl carbamate) was not detected during this time period. Trace levels of 3‐hydroxy carbofuran (2,3‐dihydro‐2,2‐dimethyl‐3‐hydroxy‐benzofuranyl‐N‐methyl carbamate) were detected periodically. The benomyl metabolite MBC was the most persistent pesticide in this study with DT50 values of 179 to 1020 d. The rates of dissipation decreased with increasing soil depth for all pesticides.
The Distribution of Uranium and Thorium Decay‐Series Radionuclides in the Environment—A Review
Authors: Cowart J. B. , Burnett W. C. 
Published: July 2010

AbstractNatural radioactivity has played an indispensable role in the development of the earth to the form and shape that we now observe. Energy from radioactivity powers the large‐scale processes that move the continents and cycle the elements. Most of the energy due to radioactivity comes from members of the three decay‐series, two of which are parented by isotopes of uranium, 238U and 235U, and one by 232Th. These decay‐series cascade to produce radioactive offspring such as Ra, Rn, and Po, but the ultimate fate of all members of these series is to end as a stable isotope of Pb. Rocks or minerals that provide sites for the long‐lived decay‐series parents, U and Th, are destined to be associated with the other members of the decay‐series. The rocks that tend to host U and Th include some crystalline rocks such as granite and quartz‐conglomerate metamorphics, and certain sedimentary rocks such as organic shales, sandstones, carbonates, and phosphorites. All materials at the earth's surface eventually are broken down to their constituent parts and then, usually by the agency of water, transported to environments where they again may be geochemically sorted. The sorting processes at or near the surface of the earth operate on radioelements just as they do on other elements. The result is that the various radioelements are not simply dispersed but rather tend to accumulate in certain environments or rock types. Thus, the behavior of the radioelements found in the natural environment is based on their geochemistry, half‐life, and the nature of their surroundings.
Papermill Sludge, Phosphorus, Potassium, and Lime Effect on Clover Grown on a Mine Soil
Authors: Feagley S. E. , Valdez M. S. , Hudnall W. H. 
Published: July 2010

AbstractPots containing mine soil treated with lime, fertilizer, and bleached, primary papermiil sludge (at the rate of 56, 112, and 224 Mg/ha added alone or in combination with fertilizer [P and K]) were planted to subterranean clover (Trifolium subterranean L.) in the first phase of a two‐phase study. Fertilizer was found necessary to revegetate the mine soil, and the addition of sludge and fertilizer significantly (α<0.05) increased yield over the fertilizer only. This favorable effect of sludge was observed during the second harvest, with 112 Mg/ha giving the maximum yield. Biological N2 fixation and native N did not raise the N concentration in clover within the normal range (2.9–3.8%). Fertilizer application improved N uptake by the forage. The N concentration in clover declined with successive harvests. However, sludge application minimized this decline. Phosphorus was found to be at normal range (0.1–0.2%) in all cases, except at the sludge rate of 112 and 224 Mg/ha without fertilizer. Excessive tissue concentrations of K, Ca, S, Fe, Cu, Zn, and Al were observed in the unfertilized mine soil and K, Ca, Zn, and Al were excessive in all treatments.
Phosphate and Trace Metal Availability from Sewage‐Sludge Incinerator Ash
Authors: Bierman Peter M. , Rosen Carl J. 
Published: July 2010

AbstractIncineration is practiced to reduce sewage sludge volume, but disposal of the resulting ash remains an important waste‐management problem. The objectives of a field study conducted from 1987 to 1990 were to evaluate sewage‐sludge‐incinerator ash as a P fertilizer, determine trace metal availability, and assess the liming potential of the ash. The soil was an Estherville sandy loam (sandy, mixed, mesic Typic Hapludoll) with an initial pH of 5.7. Treatments compared P rates of 35, 70, and 140 kg ha−1 yr−1 from triple‐superphosphate fertilizer with equivalent ash rates based on citrate‐soluble (available) P. A control receiving no P application was included. Field corn (Zea mays L.) was grown the first 3 yr and sweet corn was grown in 1990. Limited effects on growth occurred the first 2 yr, but in 1989 and 1990 both ash and phosphate fertilizer significantly increased yield. Yield response to ash was equivalent to phosphate fertilizer for 1989 field corn, but significantly less for sweet corn in 1990. Ash and phosphate fertilizer both increased tissue P concentrations, but phosphate fertilizer was the more effective P source. Olsen's soil P extractant provided a more useful measure of plant available P than Bray P‐1 for ash‐amended soil. Ash increased diethylenetriaminepentaacetic‐acid (DTPA) extractable Cu, Zn, and Cd in the 0‐ to 15‐cm soil depth and slightly buffered soil pH. Concentrations of Cu and Zn in plant tissue were consistently higher, and Mn consistently lower, with ash than with phosphate fertilizer. In 1990, ash also significantly increased tissue Cd and Mo in sweet corn. Tissue trace metal concentrations were not in the range of anticipated phytotoxicity or animal health problems.
Cloudwater and Ozone Effects upon High Elevation Red Spruce: A Summary of Study Results from Whitetop Mountain, Virginia
Authors: Thornton F. C. , Joslin J. D. , Pier P. A. , Neufeld H. , Seiler J. R. , Hutcherson J. D. 
Published: July 2010

AbstractThis paper integrates the results of a number of studies on the effects of cloudwater and ozone (O3) on red spruce (Picea rubens Sarg.) seedlings, saplings, and mature trees at Whitetop Mountain, VA, over a 3‐yr period. These investigations consisted of (i) seedling chamber exclusion studies, (ii) mature tree branch chamber exclusion studies, and (iii) field experiments comparing responses of seedlings, saplings, and mature trees. The studies included treatments that: (i) excluded clouds and O3 (COE), (ii) excluded clouds and had ambient O3 (CE), and (iii) exposed plants to both clouds and O3 either with (CC) or without (AA) chambers. Seedlings and mature branches in the various treatments were compared with respect to growth rates, gas exchange rates, foliar nutrition, and chlorophyll and wax content. Soil solution, throughfall, and foliar responses of mature trees near the summit, receiving differing amounts of cloud exposure (low cloud and high cloud sites) were also monitored. Ozone was found to have minimal effects on the parameters measured, whereas cloudwater exposure was found to have adverse effects on several response parameters. Chambered seedlings that were exposed to cloudwater (AA and CC), and mature trees at the high cloud site had significantly lower foliar Ca and Mg concentrations than their counterparts, which were protected from exposure (seedlings) or received low cloud exposure (mature). A 3 to 5°C increase in cold tolerance was also measured in seedlings from which cloudwater was excluded. These findings suggest that cloudwater‐mediated effects are currently having a negative impact on the health of red spruce, and may be involved in red spruce decline in the eastern USA.
The Nitrogen Filtering Capability of Carolina Poplar in an Artificial Riparian Zone
Authors: O'Neill G. J. , Gordon A. M. 
Published: July 2010

AbstractThe extensive use of inorganic N fertilizers in agricultural operations has been identified as an important source of nonpoint NO3−‐N pollution, contaminating both ground and surface waters. The ability of trees planted in the riparian zone of streams draining agricultural areas, however, to filter NO3−‐N in drainage water and reduce loadings to watercourses has not been proven conclusively. This study evaluated the ability of Carolina poplar (Populus × canadensis Moench) to remove NO3−‐N from a saturated soil zone. An artificial riparian zone was designed to facilitate subsurface movement of NO3−‐N through the rooting zone of trees. A Mariotte container was used to maintain a saturation zone and to deliver two NO3−‐N concentrations (12.0 and 24.6 mg L−1) to the rooting zone. Planting densities of one and two poplar trees per compartment (0.48 m2) were compared with a control with no‐trees. Four sampling locations were used to monitor the NO3−‐N concentration of the soil solution as it moved through the tree rooting zone. The filtering of NO3−‐N from the soil solution followed a quadratic function. The one and two poplar tree densities filtered 11 and 14%, respectively, more NO3−‐N from the saturated soil zone than the control and over time, were able to lower the NO3−‐N concentration in the saturated soil zone over time. Tree roots showed a significant increase in dry weight and TKN% with increasing NO3−‐N concentration. These results indicate the N filtering capability of Carolina poplar with subsequent accumulation of the N in root biomass.
Hexavalent Chromium Extraction from Soils: Evaluation of an Alkaline Digestion Method
Authors: Vitale R. J. , Mussoline G. R. , Petura J. C. , James B. R. 
Published: July 2010

AbstractThe accurate quantification of total Cr(VI) in soils is relevant to human health concerns because Cr(VI) is significantly more toxic than Cr(III). Hot alkaline solution has been shown to extract soluble and insoluble forms of Cr(VI) from soils, but incomplete recovery of Cr(VI) spikes and the oxidation of soluble Cr(III) spikes in certain soils have been suggested as method deficiencies. A laboratory method study was performed to (i) test the method's accuracy, (ii) understand the soil chemical processes responsible for poor Cr(VI) spike recoveries, and (iii) develop definitive interpretations for Cr(VI) spike recovery data. Test results for >1500 field soil samples and the method study of eight diverse soil materials demonstrated dissolution of soluble and insoluble Cr(VI) spikes and the method's reliability for Cr(VI) characterization. Complete dissolution of K2CrO4, BaCrO4, and PbCrO4 spikes confirmed the extraction of soluble and insoluble Cr(VI) forms. Ancillary soil chemical parameters, including oxidation‐reduction potential (ORP) (reported herein as Eh), pH, S2−, and total organic C were quantified and interpreted to explain poor Cr(VI) spike recoveries. Highly reducing samples yielded 0% Cr(VI) spike recoveries, as predicted from Eh‐pH relationships, and unspiked soil samples contained no detectable Cr(VI). In soils containing Cr(VI) and in most aerobic soils without native Cr(VI), acceptable Cr(VI) spike recoveries were obtained. Ancillary parameter characterization demonstrated that strongly reducing samples cannot maintain Cr(VI) laboratory matrix spikes. Correct interpretation of poor Cr(VI) spike recovery data should avoid labeling these data as unacceptable method results without ancillary parameter characterization of such samples.
Soil, Groundwater, and Plant Resources in Sludge‐Treated Bigtooth Aspen Sapling Ecosystems
Authors: Hart James B. , Nguyen Phu V. 
Published: July 2010

AbstractSludge fertilization of a 10‐yr‐old coppice bigtooth aspen (Populus grandidentata Michx.) with 500 to 600 kg ha−1 N, and associated nutrients, resulted in plant, soil, and groundwater responses that are important silviculturally, ecologically, and environmentally. Results included: sapling biomass growth responses of 66% over 4 yr; ecologically significant and environmentally acceptable understory, ground flora, and regeneration responses; increased amounts of soil nutrients in available, cycling, and physiologically active forms; storage of nutrients in the forest floor but not the surface and subsurface soil; increased nutrients in soil water; and significant but environmentally acceptable levels of groundwater contamination. Responses are explained as perturbations in normal ecological processes. Aspen growth responses continued after 4 yr, but are expected to moderate to near unfertilized levels unless nutrients are reapplied.
Fate of Bromoxynil n‐Butyrate and iso‐Octanoate Applied as a Mixture to a Wheat Field
Authors: Grover R. , Smith A. E. , Cessna A. J. 
Published: July 2010

AbstractDissipation of bromoxynil (3,5‐dibromo‐4‐hydroxybenzonitrile), applied as a 1:1 mixture of the n‐butyrate and iso‐octanoate esters, in the air, crop, and soil components was measured in a spring wheat (Triticum aestivum L.) field, both during and following its application. Drift losses during spraying were <1% of the amount applied, with no phenol derivative being detected in air samples collected during application. Following application, cumulative vapor loss for the n‐butyrate and iso‐octanoate esters (phenol equivalent, p.e.) over the 5‐d postapplication period were estimated to be 16 and 7%, respectively. Little or no free phenol residues were detected in the air above the treated field. The crop canopy intercepted approximately 20% of the application. Ester deposits on plant surfaces were rapidly dissipated with >75% of the total ester residues on the crop being lost or hydrolyzed 24 h after treatment. There were no detectable residues in the seed or straw at harvest. In the soil, the half‐lives of n‐butyrate and iso‐octanoate were <1 and ∼4 d, respectively. Hydrolysis was, however, more rapid under moist soil conditions, with the n‐butyrate being converted more rapidly to phenol than the iso‐octanoate. Phenol breakdown was also moisture dependent but much slower, with >95% dissipation occurring only after 8 wk.
Anakeesta Stream Acidification and Metal Contamination: Effects on a Salamander Community
Authors: Kucken D. J. , Davis J. S. , Petranka J. W. , Smith C. K. 
Published: July 2010

AbstractWe examined how stream degradation can affect adjoining streamside communities by comparing the density, age structure, and microhabitats of salamanders in forests adjoining contaminated and noncontaminated sections of Beech Flats Creek in the Great Smoky Mountains National Park. A section of Beech Flats Creek was contaminated due to exposure of Anakeesta rock formations in 1963. Chronic changes that have occurred since then include a reduction in pH, an increase in metal concentrations, and a nearly complete elimination of all macroinvertebrates, salamander larvae, and fish. Comparisons of control and impacted plots indicate that two stream‐breeding species (Desmognathus quadramaculatus; Eurycea wilderae) have been nearly eliminated from impacted stream sections, while two other species (D. ochrophaeus; D. imitator) that breed in both streams and seepages have been reduced by about half. In contrast, terrestrial‐breeding species (Plethodon jordani; D. wrighti) appear to have increased markedly following the reduction in stream‐breeders. Juvenile P. jordani comprised a significantly greater percentage of the population on impacted plots compared with controls. Microhabitat use on control and impacted plots did not differ significantly for any species. Changes in the densities and age structure of terrestrial breeders on impacted plots may have been due to the elimination of D. quadramaculatus, which is a major predator on other salamanders, or to release from competition with adults of stream‐breeding species. Overall, our data indicate that stream contamination from Anakeesta exposure can alter the structure of streamside salamander communities both by directly eliminating species with biphasic life cycles, and by indirectly altering ecological interactions among community members.
Transport and Retention of Fecal Bacteria at Sewage‐Polluted Fractured Rock Sites
Authors: Malard Florian , Reygrobellet Jean‐Louis , Soulié Michel 
Published: July 2010

AbstractIn 1991 to 1993, a bacteriological investigation was made of the numbers of fecal bacteria present in groundwater of a limestone site located in the Lez Basin, Southern France. Sampling was carried out in closely spaced 60‐m deep wells located on either side of a sewage‐polluted river to determine the spatio‐temporal distribution of total coliforms, fecal coliforms, and fecal streptococci in groundwater. High differences in fecal bacteria concentrations observed between wells were largely attributable to two types of infiltration mechanisms controlling the groundwater recharge. A quick infiltration process promoted channelized flow of bacterial contaminants through large vertical fractures connected to enlarged bedding joints. In such conductive channels, the reduction of fecal bacteria concentrations resulted only from the flushing and dilution ability of groundwater. However, in the less permeable parts of the site, clogging of the small‐sized fissures of the unsaturated zone by sludge particles might reduce the seepage rates and remove bacterial contaminants from percolating water. This straining effect was considered as a temporary retention process because fecal bacteria were eluted by subsequent rainwater percolation. Results of another bacteriological survey carried out on a thinly fissured gneiss aquifer contaminated by percolating sewage from numerous septic tanks also demonstrated that a similar accumulation and elution cycle had to be considered to explain the temporal pattern of well contamination.
Toxic Metal Accumulation from Agricultural Use of Sludge: Are USEPA Regulations Protective?
Authors: McBride M. B. 
Published: July 2010

AbstractThe new USEPA regulations for the use of sewage sludges will permit concentrations of particular toxic metals to increase locally on agricultural land by a factor of a hundred or more above present soil concentrations. Short‐term field experiments have shown that the adsorptive properties of sludges themselves often prevent excessive uptake of many of these metals into crops, a protection attributable largely to the added organic matter. This protection cannot be considered to be permanent or effective for all toxic metals, as indicated by data from old sludged sites. Differences in degree of protection are evident for greenhouse and field experiments, largely attributable to different rooting patterns and degree of sludge mixing in these two situations. The USEPA reliance on field data for metal uptake by corn (Zea mays L.) has led to an underestimation of phytoxicity thresholds applicable to a wider range of crops, in part because corn is able to root deeply and is metal‐tolerant. Also, the decision to use 50% yield reduction and plant top (rather than root) concentrations of heavy metals as phytotoxicity indicators may have obscured incipient toxicity. Long‐term field observations (several decades) often show that sludge‐applied metals can remain sufficiently available, even in nonacid soils when total metal concentrations are below the proposed EPA limits, to harm sensitive crops and microbes. It is concluded that the ultimate impact of toxic metals from sewage sludges at levels approaching the proposed USEPA limits on various soil‐crop systems is potentially harmful.
Reductive Dechlorination of Carbon Tetrachloride Mediated by Cationic Water‐Soluble Metalloporphyrins
Authors: Lewis Thomas A. , Morra Matthew J. , Habdas Jan , Czuchajowski Leszek , Brown Paul D. 
Published: July 2010

AbstractMicrobial degradation of halogenated pollutants in wastewaters may be limited by toxic contaminant concentrations or poor membrane permeability of the target compound. Extracellular catalysts can be used in wastewater treatment schemes to overcome these limitations. Water soluble porphyrins with functional groups suitable for immobilization were synthesized as catalysts for reductive dehalogenation of organic contaminants. Synthesized mesosubstituted porphyrins contained (with one exception) three N‐methyl‐4‐pyridinium substituents and a phenyl substituent having the ‐OH, ‐OCH3, ‐NH2, or ‐C(O)OCH2C6H4‐CH=CH2 group located in the p‐position. Catalytic activity was assessed by measuring carbon tetrachloride disappearance in reactions containing a synthetic porphyrin, dithiothreitol, and tris buffer (pH 8.2). Porphyrins metallated with Co or Ni had higher catalytic activities than those metallated with Fe. Changes in meso substituents also altered catalytic activity, with aminophenyl substitution resulting in porphyrins catalyzing the highest rates of carbon tetrachloride disappearance. Although chloroform, dichloromethane, and carbon monoxide were found to be breakdown products, no methane was detected and <40% of the carbon tetrachloride could be recovered in identified volatile products. When 14C carbon tetrachloride was used as substrate, approximately 80% of the label was found in the aqueous phase of the reaction mixture. Synthetic porphyrins have potential utility in wastewater treatment as catalysts for reductive dehalogenation, but further identification of degradative products is necessary.