bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sewage Sludge Effects on Soil and Plant Quality in a Degraded, Semiarid Grassland
Authors: Fresquez P. R. , Francis R. E. , Dennis G. L. 
Published: July 2010

AbstractA major problem affecting grassland productivity in the semiarid southwestern USA is the low quantity of soil organic matter and plant‐available N. In this study, dried, anaerobically digested sewage sludge was applied at three rates (22.5, 45, and 90 Mg ha−1) to a degraded semiarid grassland site to determine the effects of sludge on soil chemical and heavy metal properties, and vegetative yields and quality over two growing seasons. Most nutrients, including soil N, P, and K, increased linearly as a result of sludge amendment. Soil pH decreased linearly from 7.8 to 7.4 with the application of sludge after the second growing season, but did not significantly increase the solubility of soil heavy metals (Pb and Cd). On the other hand, the levels of DTPA‐extractable soil micronutrients (i.e., Cu, Mn, Zn) increased linearly with sludge rates to levels recommended for adequate plant growth. Total herbaceous plant yields increased significantly with sludge amendment, particularly at the 45 Mg ha−1 sludge rate, as compared with the control treatment. Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] yields increased two‐ to threefold in amended plots over the unamended control after two growing seasons. The forage quality of blue grama, galleta [Hilaria jamesii (Torr.) Benth.], and bottlebrush squirreltail [Sitanion hystrix (Nutt.) J.G. Sm.], improved significantly as the levels of tissue N, P, and K, and crude protein increased linearly with sludge application. As expected, levels of Cd and Pb in all plant tissues did not increased significantly as a result of sludge amendment. All micronutrients increased to acceptable levels in deficient plant tissues. Sewage sludge applied at the rate of 45 Mg ha−1 gave the most favorable soil and vegetation results.
Thallium Toxicity in Bean
Authors: Kaplan D. I. , Adriano D. C. , Sajwan K. S. 
Published: July 2010

AbstractHydroponic, rhizotron, and field studies were conducted to determine the effect of Tl on the biomass and nutrient concentrations in roots and leaves of bean plants. Loamy sand soils in the field and rhizotron cells were treated with Tl, Cd, Cr, Ni, and V. Bush beans (Phaseolus vulgaris L.) were planted in both studies. The hydroponic study consisted of growing soybean [Glycine max (L.) Merr.] in Hoagland's solution treated with Tl. All three studies showed that Tl accumulated in the roots and not in aerial portions of the plant. In the hydroponic study, micromolar concentrations of Tl added to the nutrient solution drastically altered the concentration of certain nutrients in soybean tissues and significantly reduced plant biomass. Thallium‐treated plants had fewer nodes than the normal ones. In addition, Tl caused the roots to become severely stunted with few lateral branches. The lower, more mature leaves of the treated plants exhibited chlorosis in spite of Fe concentrations comparable to the control plants. Based on tissue analyses, there was a concomitant increase in K concentrations in high Tl treatments, whereas Ca and Mg concentrations in leaves decreased below critical levels for normal growth. In addition, diagnosis and recommendation integrated system (DRIS) indicated that Ca was relatively more deficient than Mg; DRIS also identified Mn as being deficient.
Aqueous Behavior of Chromium in Coal Fly Ash
Authors: Rai Dhanpat , Szelmeczka Roger W. 
Published: July 2010

AbstractStudies were conducted to determine the dominant reactions controlling aqueous Cr concentrations in four coal fly ashes. The fly ashes were adjusted to a range of pH values between 2 and 10. Chromium was found to be present in these aqueous and solid phases as Cr(III). Because of the amorphous character of the important Cr(III) compounds [(Fe,Cr)(OH)3 and Cr(OH)3] and because of the very low total Cr content (<0.025%) of the fly ashes, it was not possible to identify directly the Cr‐containing compounds. However, an indirect technique for identifying Cr compounds, comparison of observed activities with those in equilibrium with known solid phases, and with those obtained after spiking the coal ash suspensions with Cr(III), suggest that Cr concentrations are controlled by (Fe,Cr)(OH)3(am) at low pH and by (Fe,Cr)(OH)3(am) and/or Cr(OH)3(am) at pH values greater than ∼5.
Virus Transport and Survival in Saturated and Unsaturated Flow through Soil Columns
Authors: Powelson David K. , Simpson James R. , Gerba Charles P. 
Published: July 2010

AbstractWater with entrained disease‐causing virus entering soil normally passes through water‐saturated and unsaturated regions before reaching the groundwater. The effects of saturated and unsaturated flow on the survival and transport of a virus, MS‐2 bacteriophage, were compared. The viruses were added to well water and applied to soil columns 0.052 m in diameter and 1.05 m long. The soil material was Vint loamy fine sand (a sandy, mixed, hyperthermic Typic Torrifluvent) mixed with recent alluvium. Samples of the soil water were taken daily at 0.20, 0.40, and 0.80 m depths through porous stainless steel samplers and at 1.05 m from the percolate leaving the column. For saturated flow the virus concentrations reached the influent concentration in less than two pore volumes (PV). For unsaturated flow the concentrations remained at levels much lower than the influent, ranging from 27% of inflow at 0.20 m (18 PV) to 5% at 1.05 m (3.3 PV). At the end of the experiments soil samples from each depth were assayed to determine virus adsorption to the soil. The average distribution coefficient of the unsaturated columns, 0.27, indicates very little adsorption. The number balance showed that only 39% of the unsaturated flow virus were accounted for. It appears that under unsaturated flow conditions enhanced inactivation of this virus occurs.
Effect of Conventional vs. No‐Tillage on Pesticide Leaching to Shallow Groundwater
Authors: Isensee A. R. , Nash R. G. , Helling C. S. 
Published: July 2010

AbstractA field site was established at Beltsville, MD, in 1986 to assess the effect of conventional and no‐till cultural practices on the movement of pesticides into shallow groundwater. Groundwater samples taken from unconfined (<1.5 m deep) and confined (<3 m deep) monitoring wells in 1986–1988 were analyzed for atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], deethylatrazine [6‐chloro‐N‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide], cyanazine [2‐[[4‐chloro‐6‐(ethylamino)‐1,3,5‐triazine‐2‐y1]amino)‐2‐methylpropanenitrile], and carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate). Atrazine was found in groundwater all year, while cyanazine, alachlor, and carbofuran were present only for a short period (<3 mo) after pesticide application. Fairly constant background levels of <0.5 µg L−1 atrazine were found under fields treated before 1986, while levels under continuously treated fields were <2.0 µg L−1 for 22 of 25 samplings. Pesticide residues in unconfined groundwater were usually higher (ca. 2 to 4×) than in confined groundwater. Rainfall timing relative to pesticide application was critically important to pesticide leaching. A prolonged rain immediately after the 1988 application resulted in peak atrazine and cyanazine levels of ca. 200 µg L−1 in unconfined and ca. 30 to 40 µg L−1 in confined groundwater, which resulted in short‐term levels ca. 2 to 50× greater under no‐till than conventional till plots. Results of this study suggest that preferential transport occurred.
Nitrate Contamination of Groundwater under Irrigated Coastal Plain Soils
Authors: Weil R. R. , Weismiller R. A. , Turner R. S. 
Published: July 2010

AbstractTo develop best management practices (BMP) for agricultural land to protect groundwater, data is needed on the leaching of N from irrigated coastal plain soils treated with poultry manure. This study was conducted to determine the vertical and seasonal patterns of NO3 leaching under such soils. Four commercially farmed corn (Zea mays L.) fields were studied, two receiving only fertilizer N (240 to 360 kg N ha−1 over a 2‐yr period) and two with a continuing history of poultry manure applications (25–29 Mg ha−1 over 2 yr). In each field, a transect of four monitoring wells was installed 4 to 8 m deep (1 m below the seasonally low water table). Three additional wells were installed in forestiand adjacent to three of the fields. Groundwater and soils (to 1.5‐m depth) were periodically sampled for analysis of NO3‐N. Under the unmanured field, groundwater NO3‐N concentrations averaged 15.1 mg L−1 during August through November 1986, while the corresponding figure for the manured fields was not significantly different at 18.3 mg L−1. Two months after spreading manure in November and December, as much as 104 mg NO3‐N was measured in the groundwater under the manured fields. From December 1986 through September 1987 the groundwater under the manured fields had significantly higher NO3‐N concentrations than did that under the unmanured fields (43.7 vs. 18.1 mg L−1, respectively). Only for one well site with a buried A horizon did high Cl to NO3‐N ratios and low NO3‐N concentrations indicate rapid denitrification. The forestland groundwater always contained <1 mg NO3‐N L−1, and high Cl to NO3‐N ratios, suggesting that NO3 in the cropland groundwater was lost after entering the forested areas, and that forests may therefore protect waterways from subsurface N contamination.
Assessment of Cumulative Impacts to Water Quality in a Forested Wetland Landscape
Authors: Childers Daniel L. , Gosselink James G. 
Published: July 2010

AbstractOne important focus of applied ecology is the assessment of environmental impacts and the recommendation of ways to avoid or minimize these impacts. Cumulative impacts result from the accumulation of many human activities whose impacts, although not individually measurable, together sum to significant adverse effects. Assessment of cumulative impacts requires a landscape approach and large‐scale analysis. In our procedure for determining cumulative impacts in bottomland hardwood forests (BLHF), changes in landscape integrity over time were assessed using structural and functional ecosystem indices. In this article we present a historical analysis of water quality in the Tensas Basin, Louisiana, as part of the cumulative impacts analysis of this BLHF landscape. Historical records of suspended sediment, N, P, and turbidity from three streams in the Tensas Basin were analyzed. Significant positive relationships between water levels in these streams and concentrations of total P, total Kjeldahl N, total suspended sediment, and turbidity confirmed a loading phenomenon characteristic of watersheds in which much of the original forest cover has been cleared. Eighty‐five percent of the original forest in the Tensas Basin has been converted to agricultural fields. Temporal trends in nutrient concentration show that water quality has been declining steadily since 1958 in one river, whereas in the other two the decline largely occurred before then. Nitrogen/phosphorus ratios in two of the three rivers (2.9:1 and 4.6:1 by weight, 6.4:1 and 10.2:1 by molar ratio) were lower than expected in P‐limited freshwater systems, where N/P ratios are generally > 10 to 15 by molar ratio. Most of the excess in P is probably related to the geochemical adsorption of P to sediment particles and selective loading of P during erosive storm events. As a result, in much of the Tensas Basin the nutrient limiting aquatic primary productivity—and thus the most critical nutrient to control—may be N. Between 1978 and 1986, P levels exceeded 0.1 mg L−1 96% of the time (P concentrations > 0.1 mg L−1 signal eutrophy in lotic systems). Total suspended sediment concentration patterns were erratic and in excess of 80 mg L−1 over half the time in two of the three streams studied (1966–1986). A goal‐oriented management plan for improved water quality in the Tensas Basin was devised based on this cumulative impact assessment. Improvement of the aquatic ecosystem can be achieved in a number of ways, including the reestablishment of natural hydrologic flow wherever possible, the use of agricultural practices that reduce runoff, the protection of existing forested corridors along streams, and the mitigative creation of new buffering zones. In this conservation plan, site‐by‐site permitting occurs within the context of a comprehensive plan for managing the renewable resources of the entire Tensas Basin landscape; a plan based on the intensity of past cumulative impacts to the ecosystem.
Growth and Yield of Field‐Grown Soybean in Response to Enhanced Exposure to Ultraviolet‐B Radiation
Authors: Sinclair T. R. , N'Diaye O. , Biggs R. H. 
Published: July 2010

AbstractConcern has been raised about the projected depletion of stratospheric ozone and the resultant increased exposure of crops to ultraviolet (UV)‐B radiation. Studies done in growth chambers and greenhouses indicate that substantial decreases in photosynthetic activity and leaf area growth may result from enhanced exposure to UV‐B radiation. However, for soybean [Glycine max (L.) Merr.] very few studies have been done under field conditions, and these studies either used unfiltered UV lamps or harvested only a few plants to determine seed yield. The objective of this study was to examine the influence of a 32% enhancement of UV‐B irradiance at Gainesville, FL on the growth and yield under field conditions of six soybean cultivars. No influence of either UV‐A or UV‐B radiation was detected on any growth parameter studied. Leaf area development, internode length, phyllochron index, flowering date, podding date, crop growth rate, and final seed yield were unaffected by enhanced exposure to ultraviolet radiation. These results indicate that soybean crops are not in jeopardy from the projected increase in exposure to ultraviolet radiation.
Effects of Ozone, Sulfur Dioxide, Soil Water Deficit, and Cultivar on Yields of Soybean
Authors: Heggestad Howard E. , Lesser Virginia M. 
Published: July 2010

AbstractThe effects of ozone (O3) stress on bean yields and seed size of four soybean cultivars [Glycine max (L.) Merr.] grown in open‐top chambers in 1981, 1982, and 1983 are presented. The O3 treatments included charcoal filtered (CF) and nonfiltered (NF) air, and 0.03, 0.06, and 0.09 µL L−1 O3 added 7 h d−1 to NF air. The effects of SO2 in concentrations from 0.005 to 0.224 µL L−1 (4 h d−1, 5 d wk−1) from the seedling stage to maturity were studied in 1981 and 1982. In 1982 and 1983 the effects of soil moisture stress (SMS) and well‐watered (WW) soil conditions on the response of soybean to O3 stress were determined. The primary objective was the evaluation of 3 yr of soybean data from our site using the nonlinear Weibull and the polynomial dose‐response models to relate yield responses to O3 exposure doses. The variables also included SO2, soil moisture, and cultivar. The homogeneity of the response equations were compared to permit development of the smallest set of homogeneous equations over years. Both O3 and SO2 negatively impacted bean yields and seed size. No interactions between O3 and SO2 were indicated. With the Weibull model, interactions between O3 and soil moisture were observed with ‘Forrest’ in 1982 and ‘Williams’ in 1983. With an O3 level considered typical in soybean production areas (seasonal 7 h d−1, 0.055 µL L−1) compared to background O3 (0.025 µL L−1) and using all data from 3 yr of experiments, the Weibull model predicted the same (15%) mean yield loss under both SMS and WW regimes.
Relationship between Xylem Trace Metals and Radial Growth of Loblolly Pine in Rural Alabama
Authors: Jordan D. N. , Wright L. M. , Lockaby B. G. 
Published: July 2010

AbstractThis study was undertaken to evaluate the relationship between the metals Al, Cd, Cu, Mn, Pb, and Zn and the basal area increment (BAI) of loblolly pine (Pinus taeda L.) in an old growth stand in Alabama. The BAI is the annual stand average area increment at breast height, estimated from increment borer core samples at breast height. The sampled trees have inner annual ring dates ranging from 1843 to 1918. Significant negative linear relationships were found between concentrations of Cd, Pb, Zn, and the BAI series. Aluminum and Cu concentrations were inversely related to BAI. No significance was exhibited for Mn. These findings are discussed as potential contributing factors to forest decline. No correlation was found between the soil‐extractable levels of the metals and the concentration in the most recent xylem tissue. A significant correlation was found between bark Zn and recent xylem Zn concentrations. No other metals exhibited correlations between recent xylem and soil or bark concentration.
Metolachlor Transport in Surface Runoff
Authors: Buttle J. M. 
Published: July 2010

AbstractIn 1987 metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] was applied to a 5.5‐ha corn field in southern Ontario, Canada, in two separate areas—as a preemergence surface spray with cross‐contour plowing and as a pre‐plant incorporated treatment with contour plowing. The application rate for both treatments was 2.64 kg a.i. ha−1. Metolachlor concentrations in soils and in the dissolved and adsorbed phases in runoff from natural rainstorms were monitored throughout the growing season. Persistence in soils decreased exponentially after application, although there was evidence of temporary accumulation of metolachlor in footslope areas. Dissolved concentrations in runoff decreased with time, while temporal trends in adsorbed concentrations reflected changes in metolachlor persistence in soils. Average ratios of adsorbed to dissolved herbicide concentrations ranged from 7 to 57, and were dependent upon hydrological and pedologic conditions within the treatments. Sediment carried between 9 to 58% of the total metolachlor yield from runoff plots during individual storms, and 20 to 46% of the total yield over the monitoring period. Herbicide incorporation and contour plowing led to significant reductions in dissolved and adsorbed concentrations, and in total metolachlor loss in runoff, relative to application as a preemergence spray with cross‐contour plowing. Incorporation was associated with an increase in the relative importance of sediment in metolachlor transport. Variations in herbicide losses and the relative importance of transport vectors within a given treatment were linked to local hydrological processes.
Adsorption and Desorption of 2,4,6‐Trinitrotoluene by Soils
Authors: Pennington Judith C. , Patrick William H. 
Published: July 2010

AbstractPotential environmental hazards are posed by the presence of 2,4,6‐trinitrotoluene (TNT) in soils of U.S. Army Ammunition Plants (AAP). Especially important is TNT interaction with the top several centimeters of soil, where highest concentrations occur. The TNT adsorption and desorption studies were conducted using soil samples collected from 13 AAP. Steady state adsorption and desorption of TNT with test soils was reached within 2 h. Batch TNT adsorption isotherms were best fit by the Langmuir adsorption model and had an average adsorption coefficient (Kd) of 4.0 for all soils. The TNT adsorption Kd's were most highly correlated with extractable Fe, cation exchange capacity, and clay content. Almost all of the adsorbed TNT was desorbed after three sequential desorption cycles. These results suggest that adsorption in surface soils will not greatly retard movement of TNT to lower soil horizons. The pH exerted little effect on adsorption and desorption, but oxidized conditions consistently decreased adsorption of TNT compared to reduced conditions. Two transformation products of TNT, 4‐amino‐2,6‐dinitrotoluene and 2‐amino‐4,6‐dinitrotoluene, were detected during the 24‐h test period under both oxidized and reduced conditions.
Adsorption, Degradation, and Plant Availability of 2,4‐Dinitrophenol in Sludge‐Amended Calcareous Soils
Authors: O'Connor G. A. , Lujan J. R. , Jin Yan 
Published: July 2010

Abstract2,4‐Dinitrophenol (DNP) is a moderately weak acid that is expected to be highly labile (leachable and plant available) in high‐pH soils. The adsorption and degradation behavior of DNP in two sludge‐amended, calcareous soils was determined and used to explain DNP uptake by plants grown in the soils in the greenhouse. The DNP adsorption was minor in both soils and was only slightly affected by sludge. The DNP degradation was rapid in both soils and was unaffected by sludge. Thus, despite limited soil adsorption, plant uptake of DNP was minor in all crops and plant parts owing to rapid soil DNP degradation. Even if a municipal sludge highly contaminated with DNP was identified (an unlikely occurrence), concerns over possible plant contamination should not limit sludge applications to calcareous soils at agronomic rates. Rapid degradation will minimize opportunities for plant uptake of DNP from contaminated soils or leaching of DNP to groundwater, given careful water management.
Influence of Fly Ash on Soil Microbial Activity and Populations
Authors: Pichtel J. R. , Hayes J. M. 
Published: July 2010

AbstractIncubation studies were conducted to assess the influence of various combination levels of alkaline (pH 12.2) powerplant fly ash and sewage sludge on soil microbial activity and numbers. A Glynwood (fine, illitic, mesic. Aquic Hapludalf) silt loam soil was mixed with 0, 5, 10, or 20% (w/w) ash and 0 or 5% composted sewage sludge. Respiration was strongly depressed in the 10 and 20% ash treatments over 28 d. Sludge addition improved respiration in all ash treatments except the 20% treatment. Total bacterial, actinomycete, and fungal counts in the soil typically decreased with increasing ash content. Counts were depressed by 57, 80, and 86%, respectively, at the 20% ash application rate. Sludge application increased microbial numbers but all populations were lower at the highest ash rates compared to the untreated control. Soil phosphatase, sulfatase, dehydrogenase, and invertase were inhibited as ash treatment levels increased. Catalase activity was not significantly affected by ash concentration. Addition of the sludge to the ash‐soil mixtures generally enhanced enzyme activity. The results indicate that high rates of fly ash to soils may hinder normal decomposition and nutrient cycling processes. This may be partially alleviated, however, by coapplication of a readily oxidizable organic substrate such as sewage sludge.
Sorption and Degradation of Pentachlorophenol in Sludge‐Amended Soils
Authors: Bellin Cheryl A. , O'Connor George A. , Jin Yan 
Published: July 2010

AbstractSorption and degradation of pentachlorophenol (PCP) by two alkaline and one acid soil was studied in the presence and absence of sewage sludge. The PCP concentrations used (0.1–10 mg kg−1) included PCP rates expected with land application of normal municipal sewage sludges. Sorption/desorption isotherms, derived using batch equilibrium techniques, were described by the Freundlich equation. The PCP sorption increased with increasing sludge additions. Desorption in the alkaline soils was completely reversible and no irreversible residues were formed. Leaching of PCP would be most likely in the unamended alkaline soils. Degradation of PCP at low (0.75 mg kg−1) initial concentration was rapid (t1/2 ≈10–15 d) in alkaline soils, but much slower (t1/2 ≈38 d) in the acid soils. Sludge additions to the soils did not substantially affect PCP degradation. More rapid degradation of PCP in the alkaline vs. acid soils was attributed to less sorption and more favorable conditions for microbial activity. Rapid degradation in the alkaline soil, and greater sorption in the acid soil, reduces the chance of PCP leaching. However, longer PCP residence times in the acid soil increase the possibility for plant uptake.