bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occurrence of Nitrite in the Lough Neagh River System
Authors: Smith R. V. , Foy R. H. , Lennox S. D. , Jordan C. , Burns L. C. , Cooper J. E. , Stevens R. J. 
Published: July 2010

AbstractThe Lough Neagh catchment area covers about one‐third of the land area of Northern Ireland. This report documents NO2− concentrations in the major rivers entering Lough Neagh, which are frequently in the range of 100 to 150 μg N L−1 and exceed the European Community (EC) water quality guide values. The contribution of land drainage to NO2− loads carried by these rivers was estimated to be about 40%. The remaining 60% of NO2− appears to originate from N transformations at the sediment‐water interface of the river system. The available evidence suggests that NH+4 originating from agricultural pollution provides the N substrate for nitrification by Nitrosomonas to NO2−. What is anomalous is why this NO2− is not further oxidized rapidly to NO−3 by Nitrobacter. A possible mechanism is that the Nitrobacter is retarded by the presence of free ammonia concentrations that can be predicted to be present in the range of 65 to 76 μg N L−1.
Leaching of Bromacil and Norflurazon as Affected by Herbicide Mixture
Authors: Tan S. , Singh M. 
Published: July 2010

AbstractIt is a common practice to apply herbicides as mixtures of two or more products; however, no information is available about the effect of the mixture on leaching of each herbicide in soils. This study was designed to evaluate the effect of tank mixed herbicide combinations on the leaching potential of bromacil (5‐Bromo‐3‐sec‐butyl‐6‐methyluracil) and norflurazon [4‐chloro‐5‐(methylamino)‐2‐(a,a,a‐trifluoro‐m‐tolyl)‐3(2H)‐pyridazinone]. Leaching bromacil or norflurazon in soil columns under different increments of water application was measured using a radioactive tracer method. Metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide] and terbacil (3‐tert‐Butyl‐5‐chloro‐6‐methyluracil) significantly decreased the leaching of norflurazon when the amount of water application was equivalent to two or more pore volumes. Oxadiazon [2‐tert‐butyl‐4‐(2,4‐dichloro‐5‐isopropoxyphenyl)‐Δ2‐1,3,4‐oxadiazolin‐5‐one] and simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine] significantly reduced the leaching of norflurazon when three and four pore volumes of water were applied. Trifluralin (α,α,α‐Trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) significantly decreased the leaching of norflurazon when two or three pore volumes of water were applied. The combining herbicides with bromacil had no effect on bromacil leaching except for diuron 4L formulation and napropamide, which decreased bromacil leaching under certain levels of water application. None of the herbicides tested significantly increased the leaching of bromacil or norflurazon.
Spatial and Seasonal Nitrous Oxide and Methane Fluxes in Danish Forest‐, Grassland‐, and Agroecosystems
Authors: Ambus Per , Christensen Søren 
Published: July 2010

AbstractFluxes of N2O and CH4 were measured monthly from 1990 through 1992 along a topogradient in a spruce forest (Picea abies L.), beech forest (Fagus silvatica L.), riparian grassland, coastal grassland, abandoned farmland, upland arable soil, and drained arable soil in Denmark. Spatial coefficints of variation (CV) in N2O emissions ranged between 106 and 617%. A consistent spatial pattern occurred across a temporary flood water boundary in the coastal grassland. Although inorganic N levels were low at this site, N2O emission rates compared with those at the N‐fertilized sites. Maximum N2O emission generally occured in the spring and autumn. Spatial CVs in CH4 fluxes ranged between 166 and 1787%, and consistent spatial patterns were found at the riparian and coastal grassland sites where CH4 was produced in temporarily flooded areas at rates of 7877 and 112 mg C m−2 yr−1, respectively. Uptake, as well as emission of CH4, reached maximum rates when soils dried up, presumably because CH4 diffusion became unconstrained. Annual site means of N2O emission were inversely correlated with CH4 uptake, and were 77 and 91 mg N and C m−2 in the spruce forest, 80 and 37 mg N and C m−2 in the beech forest, 66 and 69 mg N and C m−2 in the riparian, 124 and 7 mg N and C m−2 in the coastal grassland, 26 and 80 mg N and C m−2 in the abandoned farmland, 361 and 22 mg N and C m−2 in the upland arable, and 467 and 11 mg N and C m−2 in the drained arable. In this study, spatial variability in trace‐gas fluxes was high and poorly explained at all sites. The results suggest large‐scale integrative measurement techniques are necessary to obtain accurate flux estimates of N2O and CH4 from these ecosystems.
Sampling Mast for Measuring Volatile Organic Compounds in the Near‐Surface Atmosphere
Authors: Yates S. R. , Ernst F. F. , Gan J. , Spencer W. F. 
Published: July 2010

AbstractAccurate measurement of the atmospheric concentration of volatile organic compounds is essential when estimating the emission rate from the soil surface or in studies relating to worker exposure to volatile compounds. For estimating the surface flux, many methods are available which, in general, require profiles of the concentration during the experimental period. For example, the aerodynamic and the integrated horizontal flux methods require precise determination of the atmospheric concentration so that either the concentration gradients or the concentration profiles can be obtained. The accuracy of this information has a direct effect on the accuracy of the flux measurements. The proposed air sampling device provides a suitable method for measuring the atmospheric concentration of volatile compounds. Two designs are illustrated along with a description of their construction and operation. Their use is illustrated with concentration profiles observed in the field.
Off‐Site Movement of Pesticide‐Contaminated Fill from Agrichemical Facilities during the 1993 Flooding in Illinois
Authors: Roy W. R. , Chou S.‐F. J. , Krapac I. G. 
Published: July 2010

AbstractTwenty retail agrichemical facilities were flooded. There was a concern that pesticide‐contaminated road fill at these facilities had been transported into residential areas by the flooding. Forty fill and flood‐related sediment samples were collected at six facilities. No significant accumulation of sediments was present at any of the six facilities. At five of the six facilities, it did not appear that road fill had been transported off‐site. Pesticides were detected in sediment samples collected off‐site adjacent to five of the facilities. Of the 21 samples collected off‐site, atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazide) and metolachlor (2‐chloro‐6′‐ethyl‐N‐(2‐methoxy‐1‐methylethyl)acet‐o‐toluidine) were detected in 86 and 81% of the samples, respectively. When compared with on‐site concentrations, off‐site pesticide concentrations were either at similar levels, or were as much as three orders of magnitude less. The interpretation of the pesticide data was difficult and often inconclusive, because there were no background data on the occurrence and distribution of pesticides at each site before flooding.
Effects of Pocket Gopher Burrowing on Cesium‐133 Distribution on Engineered Test Plots
Authors: Gonzales G. J. , Saladen M. T. , Hakonson T. E. 
Published: July 2010

AbstractVery low levels of radionuclides exist on soil surfaces from atmospheric fallout following weapons testing or from stack discharges, and from exposure of some of the older waste storage and disposal sites worldwide. Biological factors including vegetation and animal burrowing can influence the fate of these surface contaminants. Animal burrowing introduces variability in radionuclide migration that confounds estimation of nuclide migration pathways, risk assessment, and assessment of waste burial performance. A field study on the surface and subsurface erosional transport of surface‐applied 133Cs as affected by pocket gopher (Thomomys bottae) burrowing was conducted on simulated waste landfill caps at the Los Alamos National Laboratory in north central New Mexico. Surface loss of Cs, adhered to five soil particle size ranges, was measured several times over an 18‐mo period while simulated rainfalls were in progress. Gophers reduced Cs surface loss by significant amounts, 43%. Cesium surface loss on plots with only gophers was 0.8 kg totalled for the study period. This compared with 1.4 kg for control plots, 0.5 kg for vegetated plots, and 0.2 kg for plots with both gophers and vegetation. The change in Cs surface loss over time was significant (P < 0.01). Relatively little subsurface Cs was measured in plots containing only gophers (0.7 g kg−1). Vegetation‐bearing plots had significantly more total subsurface Cs (µ = 1.7 g kg−1) than plots without vegetation (µ = 0.8 g kg−1). An average of 97% of the subsurface Cs in plots with vegetation was located in the upper 15 cm of soil (SDR1 + SDR2) compared with 67% for plots without vegetation. Vegetation moderated the influence of gopher activity on the transport of Cs to soil subsurfaces, and stabilized subsurface Cs by concentrating it in the rhizosphere. Gopher activity may have caused Cs transport to depths below that sampled, 30 cm. The results provide distribution coefficients for models of contaminant migration where animal burrowing occurs.
Electromagnetic Conductivity Surveys of Dairies for Groundwater Nitrate
Authors: Drommerhausen D. J. , Radcliffe D. E. , Brune D. E. , Gunter H. D. 
Published: July 2010

AbstractA recent study of dairies in a five‐county area in north Georgia found a high incidence of NO3 contaminated well water. We used a ground electromagnetic conductivity meter to survey eight dairies in the region to determine the source of contamination. Ground conductivities were highest in the loafing areas on most dairies. These are the corrals or small fields near the barn where the milking herd is kept when it is not in the barn or on pasture and other areas near the barn where there is high animal traffic. Conductivities were typically 15 to 20 mS m−1 in these areas, compared with <10 mS m−1 in the pastures away from barns. Water samples from groundwater monitoring wells installed in the loafing areas on three dairies to depths of 7 to 10 m had NO3‐N concentrations between 47 and 135 mg L−1. Shallow ground conductivities in the vicinity of these wells were 10 to 24 mS m−1. There was evidence of seepage at three of the six lagoons we surveyed, but the loafing areas appeared to be a greater threat to drinking water supplies because they were closer to the milking barn where the supply well was located. Stocking rates were probably high enough in the loafing areas to result in excessive N deposition from manure, but not high enough to cause anerobic conditions that would inhibit mineralization or promote denitrification. Best management practices need to be developed that address NO3 leaching from loafing areas.
Distribution and Chemical Characteristics of Cations in Annual Rings of Japanese Cedar
Authors: Momoshima N. , Eto I. , Kofuji H. , Takashima Y. , Koike M. , Imaizumi Y. , Harada T. 
Published: July 2010

AbstractThe objectives of this study were to investigate the distribution and chemical characteristics of cations in annual rings of Japanese cedar (Cryptomeria japonica D. Don) grown in a healthy stand of an unindustrialized region in Japan and discuss the possibility of using cations in tree‐rings as a chronological index of acidic deposition. Radial distributions of some cations and P at different vertical positions of the stem were analyzed for five trees from the same mountain. Each cation and P in all trees showed a specific distribution in its radial pattern but similar distribution trends were observed at all vertical positions. The cations and P were classified into three groups: (I) constant radial concentrations (Ca2+, Sr2+, Na+, and probably Ba2+), (II) high concentrations in the heartwood and low in the sapwood (Mg2+, K+, Rb+, Cs+), and (III) increasing concentrations in the sapwood (P, Mn2+, Cu2+). The total concentration of cations exceeded the calcium‐binding capacity (CBC) of the wood, and the excess was attributed to K+ in a salt form. The CBC increased from the sapwood/heartwood boundary toward the pith in the heartwood but remained constant in the sapwood. The increase of CBC in the heartwood was consistent with the profile of Mg2+, indicating a transfer of Mg2+ into heartwood and fixation on the acquired binding site. The radial distribution of 90Sr was closely related to the cumulative deposition of fallout from the nuclear weapon tests, but that of 137Cs was unrelated. This suggests immobility of Sr2+ and mobility of Cs+ in the horizontal direction of wood. The conservation of the historical 90Sr/Sr2+ change indicated that no influence of heartwood formation on the chemical environment of Sr2+ in cedar xylem and a possibility of using Sr2+ as a chronological index of nutrient availability. A steady‐state in nutrient availability is speculated for trees growing in this mountain because all of the trees analyzed show constant radial distributions of Sr2+ for decades.
Ammonia Impacts on Atrazine Leaching through Undisturbed Soil Columns
Authors: Liu Zhuojing , Clay S. A. , Clay D. E. , Harper S. S. 
Published: July 2010

AbstractAmmonia‐based fertilizers, such as anhydrous ammonia, aqua ammonia, and urea, initially increase soil pH, reducing atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) sorption and increasing atrazine desorption. Increased amounts of atrazine in soil solution may increase atrazine's leaching potential. This laboratory study investigated atrazine leaching behavior when ammonia and atrazine applications overlap. Nondisturbed 15‐cm diam. by 15‐cm depth soil columns were excavated from a Brandt silty clay loam (fine silty, Pachic Udic Haploboroll) and a Ves clay loam (fine silty, mixed mesic Typic Hapludalf). Concentrated NH4OH was applied to the soil surface at 0 or 220 kg N ha−1. Immediately after fertilizer application, 1.9 kg atrazine (spiked with ring‐labeled 14C‐atrazine) ha−1 was applied. One day after chemical application, soil columns were leached with 5.4 L of water. The ammonia application increased leachate and surface soil pH by about 2.5 and 3.5 pH units, respectively. The amount of 14C collected in leachate from ammonia‐treated columns was 60 and 30% greater for the Brandt and Ves soils, respectively, compared with untreated columns. Less 14C remained in the surface of the ammonia‐treated columns than in the surface of the untreated columns. These data indicate that the interaction between ammonia‐based fertilizers and atrazine must be considered when evaluating atrazine movement through soil. Applications of atrazine and ammonia‐based fertilizers that increase pH should be physically separated to limit the leaching potential of atrazine.
Chemical Movement in Relation to Tillage System and Simulated Rainfall Intensity
Authors: Myers J. L. , Wagger M. G. , Leidy R. B. 
Published: July 2010

AbstractThe Piedmont region in the southeastern USA is characterized by sloping, crust‐prone soils conducive to runoff losses of agricultural chemicals. Three tillage‐residue management systems were compared for their effect on concentrations of atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine], metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide], and bromide in surface runoff and in the soil profile of a Pacolet sandy clay loam (clayey, kaolinitic, thermic Typic Kanhapludults). These systems included conventional tillage (CT), no‐tillage grain production with corn (Zea mays L.) residue (NTG), and no‐tillage silage production without residue (NTS). The first simulated rainfall event consisted of a low (1.27 cm h−1) or high (5.08 cm h−1) rainfall rate applied for 30 min following herbicide and bromide application. One week later, the high rate was simulated on all plots. The CT treatment generally produced less surface runoff, and accompanying lower chemical concentrations, compared with both no‐tillage treatments on the first date. Runoff differences due to tillage system were less on the second date because of surface sealing processes under CT. Averaged over 2 yr, the percentage of applied atrazine lost on the first runoff event was 6.2% for NTG, 4.4% for NTS, and 1.5% for CT. Losses of atrazine in runoff on the second date were 1.5, 1.4, and 1.0% of that applied for NTG, NTS, and CT, respectively. The surface 7.5 cm of soil contained the highest concentrations of chemicals for all treatments, with treatment differences occurring primarily in the surface 0 to 15 cm of soil. Lower runoff values under CT generally resulted in higher soil chemical concentrations.
Soil Depth and Temperature Effects on Microbial Degradation of 2,4‐D
Authors: Veeh R. H. , Inskeep W. P. , Camper A. K. 
Published: July 2010

AbstractNumerous soil factors and climatic conditions affect the degradation rate of pesticides in soils. A major soil factor influencing herbicide degradation is the composition and abundance of the microbiota, which has been shown to vary considerably with soil depth. Another important variable affecting microbial growth and degradation kinetics is temperature. Soil samples from 0‐ to 30‐, 30‐ to 60‐, and 60‐ to 120‐cm depths of two Montana soils were placed in reaction flasks and treated with 14C‐labeled 2,4‐D at representative field use rates at temperatures of 10, 17, and 24°C. A carrier gas was used to continuously evacuate evolved 14CO2 into NaOH traps as a measure of 2,4‐D degradation. Comparisons of the effects of soil depth and temperature were made by fitting experimental data to both first‐order and logistic kinetic models. Degradation rates of 2,4‐D decreased significantly with increasing soil depth and were positively correlated with bacterial plate counts. Effects of temperature on degradation rate constants were adequately described using the Arrhenius equation. Degradation rates of 2,4‐D and bacterial enumerations were positively correlated with changes in soil organic C as a function of soil depth. These results support the idea that changes in organic C with soil depth could be used as a parameter for estimating changes in degradation rate as a function of soil depth. Efforts to model the transport of 2,4‐D in soils should account for variation in degradation rate as a function of soil depth and temperature.
Calibration and Evaluation of Subsurface Drainage Component of RZWQM V.2.5
Authors: Singh P. , Kanwar R. S. , Johnsen K. E. , Ahuja L. R. 
Published: July 2010

AbstractThis study was designed to calibrate and evaluate the subsurface drain flow component of the Root Zone Water Quality Model (RZWQM; Version 2.5) for four tillage‐systems: chisel plow (CP), moldboard plow (MB), no‐tillage (NT), and ridge‐tillage (RT). Measured subsurface drain flow data for 1990 was used for model calibration. Main parameters calibrated were lateral saturated hydraulic conductivity, and effective porosity. Subsurface drain flow predictions were made using calibrated parameters and compared with measured subsurface drain flows for 1991 and 1992. Measured subsurface drain flow data for all 3 yrs was obtained from the Nashua Water Quality Site in Iowa. The model, in general, showed a good agreement between measured and predicted subsurface drain flow values, although discrepancies existed for several days of a given year. Coefficients of determination calculated for predicted vs. measured daily subsurface drain flows ranged from 0.51 to 0.68 for 1990, 0.70 to 0.78 for 1991, and 0.54 to 0.69 for 1992. Simulated tillage effect on subsurface drain flows for 1991 and 1992 were consistent with those for calibrated year 1990 (maximum subsurface drain flow was observed under NT and minimum under MB). However, observed tillage effects varied from year to year, indicating a change in soil hydraulic properties, e.g., macroporosity. Other factors that could have caused the discrepancies between measured and simulated subsurface drain flows were: groundwater flux due to natural gradient, deep seepage, inaccuracies involved in the estimation of breakpoint rainfall data, and spatial variability in soil properties.
Responses of Phytoplankton Photosynthesis and Phosphorus Kinetics to Resuspended Sediments in Copper Sulfate‐Treated Ponds
Authors: Nalewajko C. , Prepas E. E. 
Published: July 2010

AbstractSix farm ponds (dugouts) and one lake that differ in the history of copper sulfate (CuSO4) treatment were selected for studies of effects of sediments resuspension on phytoplankton. All sites are located within 50 km of Peace River, Alberta, and are shallow, hardwater, and eutrophic. Effects of sediment resuspension on phytoplankton photosynthesis were assessed by changes in the photosynthesis‐irradiance (P‐I) curve parameters, Pmax and a, after addition of sediment at 2% v/v to lakewater samples; the effects on phytoplankton P‐state were assessed by changes in 32P‐PO4 turnover time. Copper concentrations in sediments of Gour no. 4, the dugout that had received the largest dosage of CuSO4, were 60‐times greater than untreated sites but were only 1.5 to 3‐times greater at the other treated sites. Changes of Pmax and a were not correlated with Cu concentrations in the sediments. Instead, the prevailing P‐state in lakewater could better explain the observed trends in Pmax after sediment addition. Pmax values decreased at sites where phytoplankton were P‐limited (32P‐PO4 turnover time <63 min) and increased at more P‐sufficient sites (32P‐PO4 turnover time >63 min). Stimulation of Pmax and increase in 32P‐PO4 turnover time were positively correlated. With the exception of Gour no. 4, values of a increased in all treatments. Similar changes in Pmax and a in response to sediment addition occurred in laboratory experiments with P‐sufficient cultures of Anabaena flos‐aquae. We suggest that, with the exception of grossly Cu‐polluted sediments, resuspension of sediments in waters previously treated with CuSO4 will enhance phytoplankton photosynthesis by increasing P availability, and possibly by supplying Cu at trace metal levels.
Renal Cadmium Concentrations in Mice and Shrews Collected from Forest Lands Treated with Biosolids
Authors: Nickelson Sally A. , West Stephen D. 
Published: July 2010

AbstractThis study examined the long‐term effects of biosolids (mixed domestic‐industrial anaerobically digested sewage sludge) application to forested lands on kidney Cd concentration in omnivorous mice (Peromyscus sp.) and insectivorous shrews (Sorex sp.). Animals from eight biosolids‐treated sites, located in two different areas in western Washington, were examined and compared with those captured on seven control sites. Varying amounts of biosolids had been applied either 4, 11, or 15 yr previously. Kidney Cd was significantly greater in Sorex than in Peromyscus on all treatment sites. Though Cd levels in Peromyscus from some treatment sites were significantly increased over corresponding controls, levels from the highest dose treatment sites were comparable to controls found at other sites, so it is doubtful that biosolids had a significant long‐term effect on the omnivores. Cadmium levels in Sorex from all treatment sites except those receiving the lowest dose of biosolids were significantly greater than controls. Kidney Cd concentrations in shrews trapped from the 11‐yr postapplication sites were approximately equivalent to those in shrews trapped 2 yr after application on those same sites. However, the elevated levels of Cd found in Sorex, while highly significant statistically, did not appear to be biologically significant.