bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Transgenic Indian Mustard Plants for Phytoremediation of Metal‐Contaminated Mine Tailings
Authors: Bennett Lindsay E. , Burkhead Jason L. , Hale Kerry L. , Terry Norman , Pilon Marinus , Pilon‐Smits Elizabeth A. H. 
Published: August 2012

ABSTRACTTransgenic Indian mustard [Brassica juncea (L.) Czern.] plants overproducing the enzymes γ‐glutamylcysteine synthetase (ECS) or glutathione synthetase (GS) were shown previously to have increased levels of the metal‐binding thiol peptides phytochelatins and glutathione, and enhanced Cd tolerance and accumulation. Furthermore, transgenic Indian mustard plants overexpressing adenosine triphosphate sulfurylase (APS) were shown to have higher levels of glutathione and total thiols. These results were obtained with a solution culture. To better examine the phytoremediation potential of these transgenics, a greenhouse experiment was performed in which the transgenics were grown on metal‐contaminated soil collected from a USEPA Superfund site near Leadville, Colorado. A grass mixture used for revegetation of the site was included for comparison. The ECS and GS transgenics accumulated significantly (P < 0.05) more metal in their shoot than wild‐type (WT) Indian mustard, while the APS plants did not. Of the six metals tested, the ECS and GS transgenics accumulated 1.5‐fold more Cd, and 1.5‐ to 2‐fold more Zn, compared with wild‐type Indian mustard. Furthermore, the ECS transgenics accumulated 2.4‐ to 3‐fold more Cr, Cu, and Pb, relative to WT. The grass mixture accumulated significantly less metal than Indian mustard: approximately 2‐fold less Cd, Cu, Mn, and Zn, and 5.7‐fold less Pb than WT Indian mustard. All transgenics removed significantly more metal from the soil compared with WT Indian mustard or an unplanted control. While WT did not remove more metal than the unplanted control for any of the metals tested, all three types of transgenics significantly reduced the soil metal concentration, and removed between 6% (Zn) and 25% (Cd) of the soil metal. This study is the first to demonstrate enhanced phytoextraction potential of transgenic plants using polluted environmental soil. The results confirm the importance of metal‐binding peptides for plant metal accumulation and show that results from hydroponic systems have value as an indicator for phytoremediation potential.
Characterization of Selenate Removal from Drainage Water Using Rice Straw
Authors: Zhang Yiqiang , Frankenberger William T. 
Published: August 2012

ABSTRACTRemoval of selenium (Se) from agricultural drainage water is very important for protecting wildlife in wetland systems. We conducted a series of experiments on selenite [Se(IV)] adsorption and selenate [Se(VI)] reduction to determine Se removal from drainage water amended with 1000 μg/L of Se(VI) or Se(IV) and 5 g of rice (Oryza sativa L.) straw. Under sterile conditions, the added Se(IV) was not adsorbed to the rice straw within 2 d of the experiment and the added Se(VI) was not reduced within 14 d. In contrast, added Se(VI) in a nonsterile rice‐straw solution was reduced rapidly, from 930 μg/L at Day 3 to 20 μg/L at Day 5, with an increase in unprecipitated elemental Se [Se(0)] and total Se(0). In the last several days of the experiments, unprecipitated Se(0) was the major Se form in the rice‐straw solution, with a small amount of organic Se(−II). This study showed that Se removal from drainage water in the presence of rice straw involves a two‐step process. The first is the microbial reduction of Se(VI) to Se(IV) and then to colloidal Se(0). The second is flocculation and precipitation of colloidal Se(0) to the bottom of the experimental flasks and the surface of rice straw.
Risk Assessment of Pesticide Runoff from Turf
Authors: Haith Douglas A. , Rossi Frank S. 
Published: August 2012

ABSTRACTThe TurfPQ model was used to simulate the runoff of 15 pesticides commonly applied to creeping bentgrass (Agrostis stolonifera L.) fairways and greens on golf courses in the northeastern USA. Simulations produced 100‐yr daily records of water runoff, pesticide runoff, and pesticide concentration in runoff for three locations: Boston, MA, Philadelphia, PA, and Rochester, NY. Results were summarized as annual and monthly means and annual maximum daily loads (AMDLs) corresponding to 10‐ and 20‐yr return periods. Mean annual pesticide runoff loads did not exceed 3% of annual applications for any pesticide or site, and most losses were substantially less than 1% of application. However, annual or monthly mean concentrations of chlorothalonil, iprodione, and PCNB in fairway runoff often exceeded concentrations that result in 50% mortality of the affected species (LC50) for aquatic organisms. Concentrations of azoxystrobin, bensulide, cyfluthrin, and trichlorfon in extreme (1 in 10 yr or 1 in 20 yr) events often approached or exceeded LC50 levels. Concentrations of halofenozide, mancozeb, MCPP, oxadiazon, propiconazole, thiophanate‐methyl, triadimefon, and trinexapac‐ethyl were well below LC50 levels, and turf runoff of these chemicals does not appear to be hazardous to aquatic life in surface waters.
Cholesterol, β‐Sitosterol, Ergosterol, and Coprostanol in Agricultural Soils
Authors: Puglisi Edoardo , Nicelli Marco , Capri Ettore , Trevisan Marco , Del Re Attilio A. M. 
Published: August 2012

ABSTRACTIn this work we analyzed the sterol content of agricultural soils. Three eukaryotic sterols, cholesterol, β‐sitosterol, and ergosterol were chosen as representative of the animal, plant, and fungal kingdoms, while coprostanol was validated as a marker of human fecal matter contamination. Three soils subjected to different treatments (sewage sludge application, irrigation by saline waters, and contamination by industrial and municipal wastes) were sampled and their sterol content was measured and compared with adjacent untreated soils. The effects of time, location, and treatment were evaluated by means of a number of statistical techniques. β‐Sitosterol concentration varied from 0.9 to 30 mg kg−1 Lesser values were measured in Cremona (2.1 mg kg−1) than in Bari (4.0 mg kg−1) and Naples (10.9 mg kg−1) soils. No significant effects were detected for cholesterol and ergosterol. Coprostanol was present after sewage sludge disposal and contamination by industrial and municipal wastes, while it was absent in the soil treated with saline water and in the adjacent untreated soil. Coprostanol concentration did not vary much within site and time of sampling, with a mean value of 0.2 mg kg−1 We confirmed coprostanol as a useful persistent marker of human fecal matter contamination. Multivariate analysis highlighted a clear distinction between the eukaryotic sterols and coprostanol. In addition, a different behavior between ergosterol and cholesterol on one side and β‐sitosterol on the other was detected. This preliminary work suggests that sterols deserve a deeper study of their use as indicators in agricultural soils.
Enrichment and Isolation of Endosulfan‐Degrading Microorganisms
Authors: Siddique Tariq , Okeke Benedict C. , Arshad Muhammad , Frankenberger William T. 
Published: August 2012

ABSTRACTEndosulfan (6,7,8,9,10,10‐hexachloro‐1,5,5a,6,9,9a‐hexahydro‐6,9‐methano‐2,3,4‐benzo‐dioxathiepin‐3‐oxide) is a cyclodiene organochlorine currently used as an insecticide all over the world and its residues are posing a serious environmental threat. This study reports the isolation and identification of enriched microorganisms, capable of degrading endosulfan. Enrichment was achieved by using the insecticide as either the sole source of carbon or sulfur in parallel studies. Two strains each of fungi (F1 and F4) and bacteria (BF2 and B4) were selected using endosulfan as a sole carbon source. A Pandoraea species (Lin‐3) previously isolated in our laboratory using lindane (γ‐HCH) as a carbon source was also screened for endosulfan degradation. F1 and F4 (Fusarium ventricosum) degraded α‐endosulfan by as much as 82.2 and 91.1% and β‐endosulfan by 78.5 and 89.9%, respectively, within 15 d of incubation. Bacterial strains B4 and Lin‐3 degraded α‐endosulfan up to 79.6 and 81.8% and β‐endosulfan up to 83.9 and 86.8%, respectively, in 15 d. Among the bacterial strains isolated by providing endosulfan as a sulfur source, B4s and F4t degraded α‐endosulfan by as much as 70.4 and 68.5% and β‐endosulfan by 70.4 and 70.8%, respectively, after 15 d. Degradation of the insecticide occurred concomitant with bacterial growth reaching an optical density (OD600) of 0.366 and 0.322 for B4 and Lin‐3, respectively. High OD600 was also noted with the other bacterial strains utilizing endosulfan as a sulfur source. Fungal and bacterial strains significantly decreased the pH of the nutrient culture media while growing on endosulfan. The results of this study suggest that these novel strains are a valuable source of potent endosulfan‐degrading enzymes for use in enzymatic bioremediation.
Biowaste Effects on Soil and Native Plants in a Semiarid Ecosystem
Authors: Martínez F. , Cuevas G. , Calvo R. , Walter I. 
Published: August 2012

ABSTRACTMany soils of the Mediterranean region with a semiarid climate are subjected to progressive degradation as a result of water erosion. Biosolids and municipal solid wastes (MSW) were surface‐applied once at three rates (40, 80, and 120 Mg ha−1) to different plots in a degraded semiarid ecosystem. The study was conducted to determine the effects of such applications on soil chemical properties and native vegetation over a three‐year period. Soil N, P, and K initially increased with increasing biowaste application rates, but then decreased over time. Levels of Zn and Cu were higher in MSW than biosolid‐treated plots, and increased in both years after application. Concentrations of soil Cd, Pb, Ni, and Cr did not change as a result of biowaste amendment in the study period. The growth of native plants was enhanced by the addition of biowastes. Total plant canopy and plant biomass increased significantly and remained higher in all treatments than in the control plot over the three‐year period. The species richness of native plants decreased with increasing biowaste rates. Differences in the development of native plant communities between treatments were observed, and were more remarkable three years after biowaste application. Tissue N, P, K, Zn, and Cu levels increased with the biowaste application rate, but concentrations of tissue Pb, Cd, Ni, and Cr did not increase significantly. Biowastes applied at the rate of 80 Mg ha−1gave rise to the most favorable soil and native vegetation results while avoiding environmental risks.
Nitrate Leaching and Nitrogen Recovery Following Application of Polyolefin‐Coated Urea to Potato
Authors: Zvomuya Francis , Rosen Carl J. , Russelle Michael P. , Gupta Satish C. 
Published: August 2012

ABSTRACTHigh N fertilizer and irrigation amounts applied to potato (Solanum tuberosum L.) on coarse‐textured soils often result in nitrate (NO3) leaching and low recovery of applied fertilizer N. This 3‐yr study compared the effects of two rates (140 and 280 kg N ha−1) of a single polyolefin‐coated urea (PCU) application versus split applications of urea on ‘Russet Burbank’ potato yield and on NO3 leaching and N recovery efficiency (RE) on a loamy sand. Standard irrigation was applied in all years and excessive irrigation was used in another experiment in the third year. At the recommended rate of 280 kg N ha−1, NO3 leaching during the growing season was 34 to 49% lower with PCU than three applications of urea. Under standard irrigation in the third year, leaching from five applications of urea (280 kg N ha−1) was 38% higher than PCU. Under leaching conditions in the first year (≥25 mm drainage water in at least one 24‐h period) and excessive irrigation in the third year, PCU at 280 kg N ha−1 improved total and marketable tuber yields by 12 to 19% compared with three applications of urea. Fertilizer N RE estimated by the difference and 15N isotope methods at the 280 kg N ha−1 rate was, on average, higher with PCU (mean 50%) than urea (mean 43%). Fertilizer N RE values estimated by the isotope method (mean 51%) were greater than those estimated by the difference method (mean 47%). Results from this study indicate that PCU can reduce leaching and improve N recovery and tuber yield during seasons with high leaching.
Ethylenediaminedissuccinate as a New Chelate for Environmentally Safe Enhanced Lead Phytoextraction
Authors: Grčman H. , Vodnik D. , Velikonja‐Bolta Š. , Leštan D. 
Published: August 2012

ABSTRACTUsing a soil column experiment, we compared the effect of a single dose and weekly additions of ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedissuccinate (EDDS) on the uptake of Pb, Zn, and Cd by Chinese cabbage [Brassica rapa L. subsp. pekinensis (Lour.) Hanelt], and on the leaching of heavy metals through the soil profile. The analysis of plant material revealed that both chelates increased the concentrations of Pb and, to a lesser extent, also of Zn and Cd in the leaves of the test plant. The most effective applications were single doses of 10 mmol EDTA and EDDS kg−1 soil, which caused the concentrations of Pb in the shoots to increase 94.2‐ and 102.3‐fold, respectively, relative to the control. The same dose of EDTA increased the concentration of Zn and Cd in the leaves 4.3‐ and 3.8‐fold and of EDDS 4.7‐ and 3.5‐fold, respectively. In treatments with weekly additions and lower concentrations of both chelates, EDTA was more effective than EDDS in increasing the plant uptake of Pb. In soil columns treated with weekly additions of 10 mmol kg−1 EDTA, on average 22.7, 7.0, and 39.8% of initial total Pb, Zn, and Cd in the soil were leached through the soil profile. The same amount of EDDS caused much lower leaching of Pb and Cd—only 0.8 and 1.5% of initial total concentrations. Leaching of Zn, 6.2% of the total concentration, was comparable with the EDTA treatment. A biotest with red clover (Trifolium pratense L.) indicated a greater phytotoxic effect of EDTA than EDDS addition. EDDS was also less toxic to soil fungi, as determined by phospholipid fatty acid (PLFA) analysis, and caused less stress to soil microorganisms, as indicated by the trans to cis PLFA ratio. Chelate addition did not prevent the development of arbuscular mycorrhiza on red clover.
Apatite and Phillipsite as Sequestering Agents for Metals and Radionuclides
Authors: Knox A. S. , Kaplan D. I. , Adriano D. C. , Hinton T. G. , Wilson M. D. 
Published: August 2012

ABSTRACTLaboratory and greenhouse studies were conducted to quantify apatite and phillipsite (zeolite) sequestration of selected metal contaminants. The laboratory batch study measured the sorption of aqueous Co2+, Ba2+, Pb2+, Eu3+, and UO22+ Apatite sorbed more Co2+, Pb2+, Eu3+, and UO22+ from the spike solution than phillipsite, resulting in distribution coefficients (Kd values) of >200 000 L kg−1 Phillipsite was more effective than apatite at sorbing aqueous Ba2+ Results from the laboratory study were used to design the greenhouse study that used a soil affected by a Zn–Pb smelter from Pribram, Czech Republic. Two application rates (25 and 50 g kg−1) of phillipsite and apatite and two plant species, maize (Zea mays L.) and oat (Avena sativa L.), were evaluated in this study. There was little (maize) to no (oat) plant growth in the unamended contaminated soil. Apatite and, to a slightly lesser extent, phillipsite additions significantly enhanced plant growth and reduced Cd, Pb, and Zn concentrations in all analyzed tissues (grain, leaves, and roots). The sequestering agents also affected some essential elements (Ca, Fe, and Mg). Phillipsite reduced Fe and apatite reduced P and Fe concentrations in oat tissues; however, the level of these elements in oat leaves and grains remained sufficient. Sequential extractions of the soil indicated that the Cd, Pb, and Zn were much more strongly sorbed onto the amended soil, making the contaminants less phytoavailable.
Trace Element Speciation in Poultry Litter
Authors: Jackson B. P. , Bertsch P. M. , Cabrera M. L. , Camberato J. J. , Seaman J. C. , Wood C. W. 
Published: August 2012

ABSTRACTTrace elements are added to poultry feed for disease prevention and enhanced feed efficiency. High concentrations are found in poultry litter (PL), which raises concerns regarding trace element loading of soils. Trace metal cation solubility from PL may be enhanced by complexation with dissolved organic carbon (DOC). Mineralization of organo–As compounds may result in more toxic species such as As(III) and As(V). Speciation of these elements in PL leachates should assist in predicting their fate in soil. Elemental concentrations of 40 PL samples from the southeastern USA were determined. Water‐soluble extractions (WSE) were fractionated into hydrophobic, anionic, and cationic species with solid‐phase extraction columns. Arsenic speciation of seven As species, including the main As poultry feed additives, roxarsone (ROX; 3‐nitro‐4‐hydroxyphenylarsonic acid) and p‐arsanilic acid (p‐ASA; 4‐aminophenylarsonic acid), was performed by ion chromatography–inductively coupled plasma–mass spectrometry (IC–ICP–MS). Total As concentrations in the litter varied from 1 to 39 mg kg−1, averaging 16 mg kg−1 Mean total Cu, Ni, and Zn concentrations were 479, 11, and 373 mg kg−1, respectively. Copper and Ni were relatively soluble (49 and 41% respectively) while only 6% of Zn was soluble. Arsenic was highly soluble with an average of 71% WSE. Roxarsone was the major As species in 50% of PL samples. However, the presence of As(V) as the major species in 50% of the PL samples indicates that mineralization of ROX had occurred. The high solubility of As from litter and its apparent ready mineralization to inorganic forms coupled with the large quantity of litter that is annually land‐applied in the USA suggests a potential detrimental effect on soil and water quality in the long term.
Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates
Authors: Tokunaga Tetsu K. , Wan Jiamin , Hazen Terry C. , Schwartz Egbert , Firestone Mary K. , Sutton Stephen R. , Newville Matthew , Olson Keith R. , Lanzirotti Antonio , Rao William 
Published: August 2012

ABSTRACTBiogeochemical transformations of redox‐sensitive chemicals in soils can be strongly transport‐controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(III) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr‐contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate– and reaction rate–limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments.
The Potential of Rhizosphere Microbes Isolated from a Constructed Wetland to Biomethylate Selenium
Authors: Azaizeh H. A. , Salhani N. , Sebesvari Z. , Emons H. 
Published: August 2012

ABSTRACTThe potential of rhizosphere microbes isolated from common reed [Phragmites australis (Cav.) Trin. ex Steud] plants grown in a subsurface‐flow constructed wetland to biomethylate selenate or selenite was studied in liquid cultures under controlled conditions. Total mean percentages of volatilized Se from half‐strength Hoagland culture solutions (low C content) supplemented with selenate or selenite and inoculated with cultured rhizosphere microbes after 15 d of incubation were 7.9 and 49.1%, respectively. There was a relative best fit (r = 0.87) between total number of rhizosphere and cultured microbes and the percentage of volatilized Se in Hoagland solution after 15 d of incubation. However, when the same microbes were cultured in tryptic soybean broth (TSB) medium (high C content), the percentages of volatilized Se from selenate and selenite were 1.3 and 1.9%, respectively. The volatilization percentages of Se from selenate or selenite in culture solutions inoculated with rhizosphere suspension instead of cultured rhizosphere microbes were very low (1.2–3.0%) in both cultivation media. In all experiments, selenite was volatilized significantly (p < 0.05) in higher amounts by cultured rhizosphere microbes after 15 d of incubation compared with selenate. Dissolved biomethylated dimethylselenide (DMSe) in water samples taken from the subsurface‐flow bed was determined by purging with helium. The DMSe in water samples was indirectly detected up to 2.4 μg Se L−1, which indicates that part of the produced DMSe was dissolved in the matrix before being released into the atmosphere. Our results show that rhizosphere microbes isolated from common reed plants have a high potential of Se biomethylation and volatilization from selenate and selenite.
Validation of Procedures to Quantify Nonextractable Polycyclic Aromatic Hydrocarbon Residues in Soil
Authors: Northcott Grant L. , Jones Kevin C. 
Published: August 2012

ABSTRACTThis study was conducted to optimize butanol solvent shake extraction, dichloromethane soxtec extraction, and methanolic saponification extraction for the selective extraction of aged polycyclic aromatic hydrocarbons from soil. Extraction kinetics for these methods was established to determine the optimal time necessary to achieve exhaustive compound extraction. This resulted in times of 12, 6, and 5 h, respectively, for butanol, dichloromethane, and saponification, to extract polycyclic aromatic hydrocarbons from previously spiked, then aged soil. Increasing the soil mass to butanol volume ratio reduced the proportion of polycyclic aromatic hydrocarbon extracted by butanol, highlighting the importance of determining and maintaining a constant soil to solvent ratio for comparative purposes. Drying soil samples before dichloromethane soxtec extraction reduced by 30 to 76% the amount of polycyclic aromatic hydrocarbons extracted. The effect of sample drying is discussed with relevance to enhancing the formation of nonextractable compounds in soil and compound losses previously assumed by volatilization. The optimized extraction procedures provided low variability with relative standard deviations ≤ 5.2% for analysis of multiple replicates. The results obtained by the optimized procedures provided equivalent or improved reproducibility to those obtained by other methods reported in the literature.