bluuebunny/crossref_metadata_2025 huggingface dataset:
Putative Temporal Variability of Escherichia coli Ribotypes from Yearling Steers
Authors: Jenkins M. B. , Hartel P. G. , Olexa T. J. , Stuedemann J. A.
Published: August 2012

Escherichia coli is a ubiquitous component of the intestinal microflora of warm‐blooded animals, and is an indicator of fecal contamination of surface waters. Ribotype profiling of E. coli is one of several genotypic methods that has been developed to determine the host origin of fecal bacteria. Like most genotypic methods of source tracking, ribotyping requires a host origin database to identify environmental isolates. To determine the extent of temporal variability of ribotypes and its effect on a host origin database, E. coli isolates were obtained from fecal samples of two herds of Black Angus steers at a long‐term experimental site at four sampling times from October 1999 to July 2000. Fecal samples were taken from six randomly chosen steers at each time. At a similarity index of 90% as calculated by unweighted pair‐group method using arithmetic averages (UPGMA), 240 ribotypes were identified from 451 E. coli isolates. Only 20 ribotypes (8.3%), comprising 33% of the total isolates, were shared among sampling times and were considered resident ribotypes. Two of the twenty resident ribotypes appeared at three sampling times, and the remaining eighteen appeared at two. The majority of the ribotypes, therefore, were transient and unique to each sampling time and steer. Both the apparent turnover of E. coli ribotypes and a clonal diversity index of 0.97 (indicative of extensive ribotype variability) suggest the necessity of ribotyping a large number E. coli isolates per host to establish a host origin database that is independent of temporal variability, or complete enough to be effective.
Relationships between Phosphorus Levels in Soil and in Runoff from Corn Production Systems
Authors: Andraski Todd W. , Bundy Larry G.
Published: August 2012

Phosphorus‐enriched runoff from cropland can hasten eutrophication of surface waters. A soil P level exceeding crop needs due to long‐term fertilizer and/or manure applications is one of several potential sources of increased P losses in runoff from agricultural systems. Field experiments were conducted at locations representative of three major soil regions in Wisconsin in corn (Zea mays L.) production systems to determine the effect of tillage, recent manure additions, soil P extraction method, and soil sampling depth (0–2, 0–5, and 0–15 cm) on the relationship between soil test P level and P concentrations in runoff. Runoff from simulated rainfall (75 mm h−1) was collected from 0.83‐m2 areas for 1 h after rainfall initiation and analyzed for dissolved phosphorus (DP), total phosphorus (TP), and sediment. The DP fraction of the TP concentration in runoff ranged from 5 to 17% among sites with most of the variation in TP due to varying sediment concentration on the well‐drained silt loam soils and to soil test P level on the poorly drained silty clay loam soil. In 213 observations across a range of soils and managements, good relationships occurred between soil test P level and DP concentration in runoff for most of the tests and sampling depths used. Recent manure additions and high levels of surface cover from corn residue sometimes masked this relationship. The slope of DP relative to soil test P level was markedly higher on the silty clay loam soil than on the silt loam soils possibly due to soil permeability–infiltration rate differences. Agronomic soil P tests were as effective as environmentally oriented soil P tests for predicting DP concentrations in runoff.
Patterns of Short‐Term Sedimentation in a Freshwater Created Marsh
Authors: Harter Sarah K. , Mitsch William J.
Published: August 2012

This study investigated different sedimentation measurement techniques and examined patterns of short‐term sedimentation in two 1‐ha replicate created freshwater marshes in central Ohio, USA. Short‐term (one‐year) sediment accumulation above feldspar, clay, glitter, and sand artificial marker horizons was compared at different water depths and distances from wetland inflow. A sediment budget was also constructed from turbidity and suspended sediment data for comparison with marker horizons. Glitter and sand marker horizons were the most successful for measuring sediment accumulation (81–100% marker recovery), while clay markers were completely unsuccessful. The sedimentation rate for both wetlands averaged 4.9 cm yr−1 (36 kg m−2 yr−1), and ranged from 1.82 to 9.23 cm yr−1 (12.4 to 69.7 kg m−2 yr−1). Sedimentation rates in deep, open water areas were significantly higher than in shallow, vegetated areas for both wetlands (t test, p < 0.05). However, observed sedimentation patterns may be attributed more to preferential flow through open water areas than to water depth or presence of vegetation. Contrary to the expected spatial distribution, sedimentation was highly variable within the wetlands, suggesting that bioturbation and turbulence may cause significant resuspension or that high hydrologic loads may distribute sediments throughout the basins. A sediment budget estimated sediment retention of approximately 740 g m−2 yr−1 per wetland (43% removal rate), yet gross sediment accumulation was 36 000 g m−2 yr−1 measured by marker horizons. These results suggest that erosive forces may have influenced sedimentation, but also may indicate problems with the sediment budget calculation methodology.
Spatial Analysis of Phosphorus Sorption Capacity in a Semiarid Altered Wetland
Authors: Litaor M. I. , Reichmann O. , Belzer M. , Auerswald K. , Nishri A. , Shenker M.
Published: August 2012

The observed increase in phosphorus (P) loading into the Jordan River could increase eutrophication processes in Lake Kinneret, the only freshwater lake in Israel, which provides 25% of the country's drinking water. The P may originate from the peat soils of the highly altered Hula Valley's semiarid wetland ecosystem through which the Jordan River runs. The objectives of this research were to ascertain the sorption capacity of these soils and to identify areas with high potential for P release from soils to ground water. We extracted 80 soil samples collected across the valley with ammonium oxalate and determined the ratio of extractable P to Fe and Al, from which we derived the degree of phosphorus saturation (DPS). A relatively low DPS (<15%) was observed in Histosols compared with the high DPS (>30%) observed in many of the hydromorphic organo–mineral soils. We used a sequential Gaussian simulation technique to assess the spatial pattern of the DPS and found that the Histosols have a low probability (<10%) of exceeding the widely used environmental DPS threshold of 25%. The areas characterized by mineral soils, such as hydromorphic Vertisols and various marl redoximorphic soils, have a high probability (>60%) of exceeding the threshold value. The ability to predict the concentrations of dissolved P in ground water based on DPS values was somewhat impaired because of the preferential flow characteristics in this altered wetland.
Enumeration of Waterborne Escherichia coli with Petrifilm Plates
Authors: Vail J. H. , Morgan R. , Merino C. R. , Gonzales F. , Miller R. , Ram J. L.
Published: August 2012

Escherichia coli is often monitored in environmental waters as an indicator of the possible presence of human pathogens associated with feces. Petrifilm E. coli/coliform count plates (3M, Minneapolis, MN), previously validated for enumerating E. coli in food, were tested for monitoring E. coli in environmental water. Escherichia coli counts in environmental water samples enumerated with Petrifilm were significantly correlated (R > 0.9; slope = 0.9–1.0; p < 0.001) with counts obtained with three commonly used methods, mTEC (Becton Dickinson, Sparks, MD), m‐ColiBlue (Hach, Loveland, CO), and Colilert‐18/IDEXX Quanti‐Tray 2000 (IDEXX, Westbrook, ME). Blue colonies on Petrifilm plates were most reliably identified as E. coli when accompanied by gas formation, as determined by characterization of the colonies on MacConkey agar plates (PML Microbiologicals, Mississauga, ON, Canada) and by polymerase chair reaction (PCR) with E. coli–specific primers. The main disadvantage of Petrifilm plates for environmental water testing is the small volume (1 mL per sample) that can be tested; however, the plates appear to be suitable for screening and locating sites that exceed criteria for total body and partial body contact. Simplicity of use and storage, reliability, and relatively low cost make Petrifilm plates suitable for volunteer‐based and educational water quality monitoring applications, particularly when used as a preliminary screening method to identify problem sites.
Pathogen Survival in Swine Manure Environments and Transmission of Human Enteric Illness—A Review
Authors: Guan Tat Yee , Holley Richard A.
Published: August 2012

The influence of zoonotic pathogens in animal manure on human health and well‐being as a direct or indirect cause of human enteric illness is examined. Available international data are considered, but the study is focused on the developing situation in western Canada, where it is certain there will be further rapid growth in livestock numbers, particularly hogs. Major pathogens considered are Escherichia coli O157:H7, Salmonella, Campylobacter, Yersinia, Cryptosporidium, and Giardia Canada is now the leading exporter of pork internationally, but recent increases in production contrast with constant domestic levels of pork consumption and declining levels of foodborne illness caused by pork. Effects of increased levels of manure production are not quantifiable in terms of effects on human health. The presence of major pathogens in manure and movement to human food sources and water are considered on the basis of available data. Survival of the organisms in soil, manure, and water indicate significant variability in resistance to environmental challenge that are characteristic of the organisms themselves. Generally, pathogens survived longer in environmental samples at cool temperatures but differences were seen in liquid and solid manure. Based on actual data plus some data extrapolated from cattle manure environments, holding manure at 25°C for 90 d will render it free from the pathogens considered above.
Transport and Biodegradation of Perchlorate in Soils
Authors: Tipton Deborah K. , Rolston Dennis E. , Scow Kate M.
Published: August 2012

Perchlorate (ClO−4) contamination of ground water and surface water is a widespread problem, particularly in the western United States. This study examined the effect of biodegradation on perchlorate fate and transport in soils. Solute transport experiments were conducted on two surface soils. Pulses of solution containing perchlorate and Br− were applied to saturated soil columns at steady state water flow. Perchlorate behaved like a nonreactive tracer in Columbia loam (coarse‐loamy, mixed, superactive, nonacid, thermic Oxyaquic Xerofluvent) but was degraded in Yolo loam (fine‐silty, mixed, superactive, nonacid, thermic Mollic Xerofluvent). Batch experiments demonstrated that perchlorate removal from solution in Yolo loam was caused by biodegradation. Other batch experiments with Yolo loam surface and subsurface soils, Columbia loam surface soil, and dredge tailings demonstrated that perchlorate biodegradation required anaerobic conditions, an adequate carbon source, and an active perchlorate‐degrading microbial population. The sequential reduction of perchlorate and NO−3 by an indigenous soil microbial community in Yolo loam batch systems was also studied. Nitrate reduction occurred much sooner than perchlorate reduction in soils that had not been previously exposed to perchlorate, but NO−3 and perchlorate were simultaneously reduced in soils previously exposed to perchlorate. The results of this study have implications for in situ remediation schemes and for agricultural soils that have been contaminated by perchlorate‐tainted irrigation water.
Odor and Gas Release from Anaerobic Treatment Lagoons for Swine Manure
Authors: Lim Teng‐Teeh , Heber Albert J. , Ni Ji‐Qin , Sutton Alan L. , Shao Ping
Published: August 2012

Odor and gas release from anaerobic lagoons for treating swine waste affect air quality in neighboring communities but rates of release are not well documented. A buoyant convective flux chamber (BCFC) was used to determine the effect of lagoon loading rate on measured odor and gas releases from two primary lagoons at a simulated wind speed of 1.0 m s−1 Concentrations of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), sulfur dioxide (SO2), and nitric oxide (NO) in 50‐L air samples were measured. A panel of human subjects, whose sensitivity was verified with a certified reference odorant, evaluated odor concentration, intensity, and hedonic tone. Geometric mean odor concentrations of BCFC inlet and outlet samples and of downwind berm samples were 168 ± 44 (mean ± 95% confidence interval), 262 ± 60, and 114 ± 38 OUE m−3 (OUE, European odor unit, equivalent to 123 μg n‐butanol), respectively. The overall geometric mean odor release was 2.3 ± 1.5 OUE s−1 m−2 (1.5 ± 0.9 OU s−1 m−2). The live mass specific geometric mean odor release was 13.5 OUE s−1 AU−1 (animal unit = 500 kg live body mass). Overall mean NH3, H2S, CO2 and SO2 releases were 101 ± 24, 5.7 ± 2.0, 852 ± 307, and 0.5 ± 0.4 μg s−1 m−2, respectively. Nitric oxide was not detected. Odor concentrations were directly proportional to H2S and CO2 concentrations and odor intensity, and inversely proportional to hedonic tone and SO2 concentration (P < 0.05). Releases of NH3, H2S, and CO2 were directly proportional (P < 0.05) to volatile solids loading rate (VSLR).
Polycyclic Aromatic Hydrocarbons (PAHs) and Estrogenic Compounds in Experimental Flue Gas Streams
Authors: Muthumbi W. , De Boever P. , Pieters J. G. , Siciliano S. , D'Hooge W. , Verstraete W.
Published: August 2012

The importance of combustion processes as a source of substances with estrogenic activity in the environment was investigated. Wood (nontreated and treated with wood preservatives), barbecue charcoal, meat, and kitchen waste were combusted in a laboratory‐scale incinerator. Flue gas emissions (particulates and gaseous pollutants) were trapped in polyurethane foam cartridges. The cartridges were subjected to Soxhlet extraction and part of the extracts redissolved in dimethylsulfoxide (DMSO) for analyses of estrogenic activity by means of the yeast‐based human estrogen receptor (hER) bioassay. A synthetic estrogen, 17‐α‐ethinylestradiol (EE2), was used as the reference estrogenic compound. Part of the extracts was analyzed for the 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs). Estrogenic compounds in the flue gas (wood) were as high as 234 ± 25 ng m−3 EE2 equivalent compared with 27 to 81 ng m−3 EE2 equivalent in flue gas from combustion of barbecue charcoal. Concentrations of polycyclic aromatic hydrocarbons in both flue gas streams were in the range of 21 000 ± 2000 and 240 ± 110 ng m−3, respectively. In general, the concentrations of EE2 equivalent in the flue gas samples were at least a factor of 1000 lower than total PAH concentration. The EE2 levels were not related to the concentration of PAHs in any flue gas sample.
Nitrous Oxide, Nitric Oxide, and Nitrogen Dioxide Fluxes from Soils after Manure and Urea Application
Authors: Akiyama Hiroko , Tsuruta Haruo
Published: August 2012

Nitrous oxide is a greenhouse gas, and NO and NO2 play a key role in atmospheric chemistry. Nitrous oxide, NO, and NO2 fluxes from fertilized soils were measured six times per day by an automated flux monitoring system for one year, beginning on 21 May 1998. Pac choi (Brassica spp.) was cultivated for two months, and the plots were left fallow the remainder of the year. Two types of manure, poultry manure (PM) and swine manure (SM), and a chemical fertilizer, urea, were applied to the soil. The total amount of nitrogen applied in each case was 15 g N m−2 The total fluxes from PM, SM, and urea for the year were 184, 61.3, and 44.8 mg N m−2 for N2O, respectively; 9.95, 16.6, and 148 mg N m−2 for NO, respectively; and −6.21, −7.23, and −7.84 mg N m−2 for NO2, respectively. A negative correlation was found between the NO flux and the NO concentration of the chamber air just after the chamber was closed, when a flux from the atmosphere to soil was observed for 10 months. The mean gross NO production, the NO uptake rate constant, and the apparent compensation point for this period were 0.79 to 0.95 μg N m−2 h−1, 120 to 128 L m−2 h−1, and 5.65 to 7.35 ppbv, respectively.
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

Transgenic 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

Removal 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

The 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

In 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

Endosulfan (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

Many 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

High 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

Using 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

Laboratory 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

Trace 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

Biogeochemical 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

The 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

This 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.
Distribution Behavior of Pyrene to Adsorbed Humic Acids on Kaolin
Authors: Terashima Motoki , Tanaka Shunitz , Fukushima Masami
Published: August 2012

The distribution behavior of pyrene on humic acid (HA)–kaolin complexes, prepared by adsorbing HA on kaolin, was investigated by batch experiments. The distribution coefficient (Kd) of pyrene on the HA–kaolin complex increased with the fraction (foc) of organic carbon adsorbed to the surface of the kaolin. This can be attributed to hydrophobic interactions between pyrene and the adsorbed HAs. The effects of adsorbed HAs were quantitatively evaluated by calculating the distribution coefficient (Koc) and affinity constant (Kadsoc) for pyrene to the adsorbed HAs. A fluorescence quenching method was employed to determine the affinity constant (Kaqoc) of pyrene to HAs dissolved in an aqueous solution. When the Koc values were compared with the Kaqoc values, the Koc values were found to be 4 to 11 times larger than the Kaqoc values. On the other hand, the Kadsoc values were 4 to 9 times larger than the Kaqoc values. These indicate that the affinity for pyrene is enhanced by the adsorption of HAs to kaolin. In addition, the Koc values increased with increasing average molecular weights of the HAs. These results demonstrate that HAs, when they are adsorbed to clay minerals, play an important role in the deposition of polycyclic aromatic hydrocarbons (PAHs) in a soil environment.
Fertilizer Use Efficiency and Nitrate Leaching in a Tropical Sandy Soil
Authors: Nyamangara J. , Bergström L. F. , Piha M. I. , Giller K. E.
Published: August 2012

Maize (Zea mays L.) production in the smallholder farming areas of Zimbabwe is based on both organic and mineral nutrient sources. A study was conducted to determine the effect of composted cattle manure, mineral N fertilizer, and their combinations on NO3 concentrations in leachate leaving the root zone and to establish N fertilization rates that minimize leaching. Maize was grown for three seasons (1996–1997, 1997–1998, and 1998–1999) in field lysimeters repacked with a coarse‐grained sandy soil (Typic Kandiustalf). Leachate volumes ranged from 480 to 509 mm yr−1 (1395 mm rainfall) in 1996–1997, 296 to 335 mm yr−1 (840 mm rainfall) in 1997–1998, and 606 to 635 mm yr−1 (1387 mm rainfall) in 1998–1999. Mineral N fertilizer, especially the high rate (120 kg N ha−1), and manure plus mineral N fertilizer combinations resulted in high NO3 leachate concentrations (up to 34 mg N L−1) and NO3 losses (up to 56 kg N ha−1 yr−1) in 1996–1997, which represent both environmental and economic concerns. Although the leaching losses were relatively small in the other seasons, they are still of great significance in African smallholder farming where fertilizer is unaffordable for most farmers. Nitrate leaching from sole manure treatments was relatively low (average of less than 20 kg N ha−1 yr−1), whereas the crop uptake efficiency of mineral N fertilizer was enhanced by up to 26% when manure and mineral N fertilizer were applied in combination. The low manure (12.5 Mg ha−1) plus 60 kg N ha−1 fertilizer treatment was best in terms of maintaining dry matter yield and minimizing N leaching losses.
Residual Soil Nitrate after Potato Harvest
Authors: Bélanger Gilles , Ziadi Noura , Walsh John R. , Richards John E. , Milburn Paul H.
Published: August 2012

Nitrogen loss by leaching is a major problem, particularly with crops requiring large amounts of N fertilizer. We evaluated the effect of N fertilization and irrigation on residual soil nitrate following potato (Solanum tuberosum L.) harvests in the upper St‐John River valley of New Brunswick, Canada. Soil nitrate contents were measured to a 0.90‐m depth in three treatments of N fertilization (0, 100, and 250 kg N ha−1) at two on‐farm sites in 1995, and in four treatments of N fertilization (0, 50, 100, and 250 kg N ha−1) at four sites for each of two years (1996 and 1997) with and without supplemental irrigation. Residual soil NO3–N content increased from 33 kg NO3–N ha−1 in the unfertilized check plots to 160 kg NO3–N ha−1 when 250 kg N ha−1 was applied. Across N treatments, residual soil NO3–N contents ranged from 30 to 105 kg NO3–N ha−1 with irrigation and from 30 to 202 kg NO3–N ha−1 without irrigation. Residual soil NO3–N content within the surface 0.30 m was related (R2 = 0.94) to the NO3–N content to a 0.90‐m depth. Estimates of residual soil NO3–N content at the economically optimum nitrogen fertilizer application (Nop) ranged from 46 to 99 kg NO3–N ha−1 under irrigated conditions and from 62 to 260 kg NO3–N ha−1 under nonirrigated conditions, and were lower than the soil NO3–N content measured with 250 kg N ha−1 We conclude that residual soil NO3–N after harvest can be maintained at a reasonable level (<70 kg NO3–N ha−1) when N fertilization is based on the economically optimum N application.
Phosphorus Removal in Vegetated Filter Strips
Authors: Abu‐Zreig Majed , Rudra Ramesh P. , Whiteley Hugh R. , Lalonde Manon N. , Kaushik Narinder K.
Published: August 2012

Vegetated filter strips (VFS) are used recently for removal, at or near the source, of sediment and sediment‐bound chemicals from cropland runoff. Vegetation within the flowpath increases water infiltration and decreases water turbulence, thus enhancing pollutant removal by sedimentation within filter media and infiltration through the filter surface. Field experiments have been conducted to examine the efficiency of vegetated filter strips for phosphorus removal from cropland runoff with 20 filters with varying length (2 to 15 m), slope (2.3 and 5%), and vegetated cover, including bare‐soil plots as control. Artificial runoff used in this study had an average phosphorus concentration of 2.37 mg L−1 and a sediment concentration of 2700 mg L−1 The average phosphorus trapping efficiency of all vegetated filters was 61% and ranged from 31% in a 2‐m filter to 89% in a 15‐m filter. Filter length has been found to be the predominant factor affecting P trapping in VFS. The rate of inflow, type of vegetation, and density of vegetation coverage had secondary influences on P removal. Short filters (2 and 5 m), which are somewhat effective in sediment removal, are much less effective in P removal. Increasing the filter length beyond 15 m is ineffective in enhancing sediment removal but is expected to further enhance P removal. Sediment deposition, infiltration, and plant adsorption are the primary mechanisms for phosphorus trapping in VFS.
A Two‐Dimensional Model for Simulating the Transport and Fate of Toxic Chemicals in a Stratified Reservoir
Authors: Gu Roy R. , Chung Se‐Woong
Published: August 2012

A two‐dimensional reservoir toxics model is essential to establishing effective water resources management and protection. In a reservoir, the fate of a toxic chemical is closely connected with flow regimes and circulation patterns. To better understand the kinetic processes and persistence and predict the dissipation of toxic contaminants in the reservoir during a spill or storm runoff event, a toxics submodel was developed and incorporated into an existing laterally integrated hydrodynamics and transport model. The toxics submodel describes the physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. The two‐dimensional toxicant simulation model was applied to Shasta Reservoir in California to simulate the physico–chemical processes and fate of a volatile toxic compound, methyl isothiocyanate (MITC), during a chemical spill into the Sacramento River in 1991. The predicted MITC concentrations were compared with those observed. The effect of reservoir flow regimes on the transport and fate of the toxic substance was investigated. The results suggested that the persistence of MITC is significantly influenced by different flow regimes. Methyl isothiocyanate is more persistent in the reservoir under an interflow condition due to reduced volatilization from deep layers than under an overflow condition. In the overflow situation, the plume moved more slowly toward the dam and experienced greater dissipation. This analysis can assist in toxic spill control and reservoir management, including field sampling and closure of water intakes.