bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport of Antibiotic‐resistant Escherichia coli Through Western Oregon Hillslope Soils Under Conditions of Saturated Flow
Authors: Rahe T. M. , Hagedorn C. , McCoy E. L. , Kling G. F. 
Published: July 2010

AbstractField experiments using strains of antibiotic resistant Escherichia coli were conducted to evaluate the events which would occur when a septic‐tank drainfield became submerged in a perched water table and fecal bacteria were subsequently released into the ground water. Three separately distinguishable bacterial strains were inoculated into three horizontal lines installed in the A, B, and C horizons of two western Oregon hillslope soils. Movement was evaluated by collecting ground water samples from rows of modified piezometers (six piezometers/row) placed at various depths and distances downslope from the injection lines. Transport of E. coli differed at both sites with respect to movement rates, zones in the soil profiles through which major translocation occurred, and the relative numbers of cells transported over time. Movement rates of at least 1,500 cm/hour were observed in the B horizon at one site. The strains of E. coli survived in large numbers in the soils examined for at least 96 hours and appeared to be satisfactory as tracers of subsurface water flow. The concept of partial displacement (or turbulent flow through macropores) is discussed as an explanation of the rapid movement of substantial numbers of microbial cells through saturated profiles.
Effect of Bentonite on Plant Availability of Sludge‐Borne Heavy Metals in Soil
Authors: Sims Tom , Boswell Fred C. 
Published: July 2010

AbstractAgricultural use of industrial sewage sludge is limited by the presence of potentially toxic heavy metals within the sludge. Cation exchange capacity (CEC) has been identified as a soil property that is involved in inhibition of heavy metal mobility in the soil, and in subsequent plant uptake of these metals. In addition, other soil factors such as pH influence plant uptake of metals. This investigation was conducted to determine how modification of soil CEC would affect soil availability and plant uptake of selected sludge‐borne heavy metals.Cation exchange capacity and soil pH were altered by the addition of bentonite. Sewage sludge from a highly industrialized section of Atlanta, Georgia, was used as the heavy metal source. These materials were arranged in a 3 × 4 factorial using three bentonite and four sewage sludge rates and then combined with a Cecil sandy loam soil. Wheat (Triticum aestivum L. McNair 1813) was grown as an indicator crop under greenhouse conditions for 2 mo. Analyses of plant and soil samples indicate that addition of sewage sludge results in an increase in soil and plant concentrations of certain heavy metals. Concentrations of selected microelements extracted from soil mixes by DTPA were positively correlated with plant component levels. Introduction of bentonite resulted in increases in soil CEC and pH and reductions in concentrations of these same elements in the soil and plant. These data suggest that soils selected for land application of sewage sludge containing high heavy metal levels should have relatively high CEC and pH levels. Further work is necessary to differentiate between the CEC and pH effects of bentonite on the disposition of these and other heavy metals.
Sources, Levels, and Reactions of Boron in Florida Waters
Authors: Carriker Neil E. , Brezonik Patrick L. 
Published: July 2010

AbstractLevels of boron in Florida natural waters are generally low, (median value <50 µg/liter for 120 samples) and not of toxic concern. However, municipal sewage effluents have levels high enough (150–800 µg/liter) to cause phytotoxicity, at least to sensitive plants such as citrus. Detergent use of borate softeners and perborate bleaches is evidently the source of the elevated boron levels in sewage. Boron concentrations in rainfall increase with proximity to either coast in peninsular Florida, reaching levels of 80–90 µg/liter. Marine aerosols are thus implicated as an important natural source in the boron cycle of Florida. Model ecosystem studies indicated little bioaccumulation and no toxic hazard at levels expected in natural waters. Interactions of boron with clays and with dissolved organic color (humates) were found to be small, and boron behaves as an essentially conservative element in natural waters.
Temperature and pH as Limiting Factors in Loss of Nitrate from Saturated Atlantic Coastal Plain Soils
Authors: Gilliam J. W. , Gambrell R. P. 
Published: July 2010

AbstractNitrate reduction rates under water‐saturated conditions were determined for two acid Atlantic Coastal Plain topsoils and their acid subsoils at 5, 15, and 25°C. Nitrate reduction readily occurred in subsoils even at pH values of 4.5 when an energy source was added. It was concluded that the acid pH values which commonly occur in Atlantic Coastal Plain soils is not a serious limiting factor in NO3− reduction.The temperatures of 5 to 15°C which exist in the shallow ground water of the Atlantic Coastal Plain soils during much of the winter limits the rate of NO3− reduction. Nitrate reduction can occur in these soils at 5°C but the rate is relatively slow and is highly dependent upon the amount of available C. A significant amount of NO3− reduction can be expected during the winter in poorly drained soils which contain relatively high organic matter contents.
Status of the Aflatoxin Problem in Corn
Authors: Zuber M. S. , Lillehoj E. B. 
Published: July 2010

AbstractAflatoxin, a potent carcinogenic metabolite produced by the fungus Aspergillus flavus, has been clearly demonstrated to be a kernel contaminant in both preharvest and postharvest corn. Research has been conducted on: (i) fungus invasion of the ear; (ii) effects of the environment on aflatoxin levels; and (iii) methods of control.A. flavus infects developing ears in both southern and corn belt regions but growing conditions in the southern U.S. are more conducive to the fungal infection process and subsequent toxin production. Most observations indicated that a break in the pericarp is necessary for fungal establishment. Insects, particularly larvae of the second European corn borer, corn earworm, and fall armyworm, have been implicated in causing breaks as well as serving as vehicles for carrying the inoculum to the potential infection site. Conditions of stress such as those caused by drought have been shown to enhance the aflatoxin contamination problem. Suggested control methods are: (i) plant only adapted hybrids with the highest level of resistance against ear‐damaging insects; (ii) employ management practices that will either reduce stress or shift the ear development stage to miss a likely stress period.Preliminary results suggest that either A. flavus growth or aflatoxin levels are under genetic control, but corn genotypes cannot be recommended at this time that would entirely eliminate the aflatoxin contamination problem in corn.
Behavior of Chromium in Soils: III. Oxidation
Authors: Bartlett Richmond , James Bruce 
Published: July 2010

AbstractBecause reduced Cr has been considered to be the stable form in soils, we were surprised to find that added trivalent Cr oxidizes readily to the hexavalent form under conditions prevalent in many field soils. The key to the oxidation appears to be the presence in the soil of oxidized Mn, which serves as the electron acceptor in the reaction. The relative ability of a soil to oxidize Cr may be predicted by measuring Mn reducible by hydroquinone, or it may be determined directly by means of a quick test in which Cr(III) is added to a fresh moist soil sample.Oxidation of Cr by soils was not discovered earlier because the importance of studying fresh field soils, rather than crushed, dried, stored samples, was not appreciated. Plants were severely damaged by Cr(VI) formed from Cr(III) added to fresh soil samples. Hexavalent Cr still was present in a soil stored moist at 25°C for 5 mo.
A Generalized Water Quality Index Based on Multivariate Factor Analysis
Authors: Joung H. M. , Miller W. W. , Mahannah C. N. , Guitjens J. C. 
Published: July 2010

AbstractWater quality indexes permit an evaluation of water quality conditions in comparative terms. This paper presents a methodology for derivation of a generalized water quality index based on factor analysis (a multivariate statistical technique), and examines the geographical applicability of such an index. Ten pollutant parameters from water quality data accumulated in the Carson Valley of Nevada during the 1974, 1975, and 1976 irrigation seasons provided the basis for two indexes: i) WQITN = f(temp., BOD, TP, EC, DODP); and ii) WQIPN = f(temp., BOD, PO4‐P, EC, DODP). Regression analysis of the indexes as functions of water quality variables from two river basins in Nevada indicated WQITN to be the better index (F‐test 99%, R2 = 0.9098). The WQITN formulation was then compared with index values suggested by water quality experts (WQIE). Regression coefficients were determined for WQIE and WQITN index regression equations as functions of water quality data from selected locations throughout the United States. The proposed WQITN appeared the most geographically acceptable index (F‐test 99%, R2 = 0.9754). The model estimated by factor analysis was shown to have good potential as a generalized water quality index. Use of the suggested methodology for the development of generalized, as well as specific‐use water quality indexes, may enable better geographic identification of problem areas contributing to water pollution and the development of appropriate water quality standards. Standardization of the indexes in terms of a range of acceptability, e.g., light, moderate, or severe pollution, is suggested for further investigation.
Effects of Divalent Metal Chlorides on Respiration and Extractable Enzymatic Activities of Douglas‐Fir Needle Litter
Authors: Spalding Brian P. 
Published: July 2010

AbstractThe rates of CO1 evolution from Douglas‐fir (Pseudotsuga menziesii [Mirb.] Franco) needle litter, following application of divalent metal (Hg, Cd, Pb, Ni, Zn, and Cu) chlorides at rates of 10, 100, and 1,000 µg/g and Ca chloride at 7, 68, and 683 µg/g, were monitored at 2‐ to 3‐day intervals for 4 weeks; extractable enzymatic activities were also measured on additional samples at 1 day, 2, and 4 weeks following treatment. All metals except Pb inhibited respiration when applied at the highest level. Cellulase activity was depressed by treatments of 1,000 µg/g of either Hg or Cd after 4 weeks but was not affected initially (1 day after). After 4 weeks, xylanase activity was also depressed by the 1,000‐µg/g Hg treatment. Apparently these enzymatic activities declined due to decreased enzyme synthesis associated with inhibited microbial growth rather than by direct enzymatic inhibition. Although addition of Hg or Cu chlorides directly to litter extracts caused marked inhibition of most enzymatic activities, equivalent levels, when applied to the needle litter, produced no inhibitions in extracts after 1 day, except for invertase activity. lnvertase activity was depressed at all intervals and β‐glucosidase activity was elevated at all intervals by Hg at the 1,000‐µg/g level. The level of extractable ninhydrin‐reactive compounds was elevated by this Hg treatment at all intervals similar to the effect of fumigation of soil or litter. Regardless of treatment, cellulase and xylanase activities were correlated (r = 0.70, n = 192).
Technetium Sources and Behavior in the Environment
Authors: Wildung R. E. , McFadden K. M. , Garland T. R. 
Published: July 2010

AbstractTechnetium (Tc) may enter the environment as a result of nuclear weapons testing, nuclear power production, nuclear fuel reprocessing, nuclear waste storage, and pharmaceutical use. The isotope 99Tc has a long half‐life and relatively high fission yield, and an understanding of its behavior and effects in the environment is essential to complete assessment of the environmental impact of the nuclear fuel cycle. Although little is known of Tc environmental behavior, the aqueous chemistry of Tc is well understood and limited laboratory investigations have been conducted on its behavior in soils, plants, and waters. On the basis of this current knowledge, the behavior and implications of Tc in the environment are assessed and avenues of research are suggested.The most stable chemical species of Tc in aqueous solution is the pertechnetate ion, TcO4−. As the pertechnetate ion, Tc is highly soluble in water and in soil, but reduced forms (dioxide and sulfide) have limited solubility; sorption is significant in surface soils of high organic C content and low pH and may be significant in subsoils and geologic media under reduced conditions. A fraction of the sorption measured in surface soils may also have been due to immobilization in microbial cells. The pertechnetate ion is readily available to microbiota, algae, and higher plants and is toxic to higher plants at relatively low soil levels (0.1 µg/g). In higher plants, it is transported largely as the pertechnetate ion and toxicity appears to be due to biochemical rather than radiation effects. Uptake and toxicity appear to be due to Tc functioning as a nutrient analog. Preliminary studies indicate that, in contrast to hydrolyzable radionuclides, incorporation of Tc in plants reduces Tc absorption in animals.Ultimately, the mobility and availability of Tc to biota will be governed by the quantity and form emitted and its form and solubility over the long‐term in soils, sediments, and waters. Uptake by biota will be dependent upon the rate and extent of Tc movement across biological membranes and its toxicity. Proper evaluation of these phenomena will be largely dependent on development of an understanding of Tc sorption mechanisms in soils and sediments and the determination of the stable forms of soluble chemical species that occur in the environment over the long term.
Runoff Water Quality as Affected by Surface‐applied Dairy Cattle Manure
Authors: Long F. Leslie 
Published: July 2010

AbstractThe effect of dairy cattle manure on runoff water quality was determined. The manure was surface‐applied to Coastal bermudagrass (Cynodon dactylon [L.] Pers.) on a Norfolk sandy loam with < 2% slope, at the rate of 45 metric tons/ha per year for 4 years in split applications. Manure applications slightly increased biochemical oxygen demand (BOD) values of runoff water; the maximum value was < 20 mg/liter and annual mean values were all < 10 mg/liter with no BOD buildup in the runoff water over the 4‐year period. Nitrate levels in runoff water were increased by the manure, but all annual mean values were below critical levels at < 8 mg NO3‐N/liter. During the first 2 years, about 30 kg/ha total N was lost in runoff, but < 6 kg N/ha was lost during the third and fourth years.
Herbicide Runoff from Upland Piedmont Watersheds—Data and Implications for Modeling Pesticide Transport
Authors: Leonard R. A. , Langdale G. W. , Fleming W. G. 
Published: July 2010

AbstractRunoff and persistence of selected herbicides were studied on four small Piedmont watersheds in Georgia during four growing seasons. This is part of a study designed to provide data for developing and testing mathematical models for agricultural chemical transport. Seasonal runoff losses were determined relative to watershed management, herbicide type and persistence, mode of application, and time of runoff in relation to application timing. Seasonal losses were usually < 2% of the application, unless large runoff volumes were generated shortly after application. Average storm herbicide concentrations in runoff were correlated with herbicide concentrations at the 0‐ to 1‐ cm depth increment of the watershed soils at the time of runoff. Paraquat concentrations in runoff (predominantly sediment associated) were well correlated and positive with the product of soil herbicide concentration and sediment in runoff. Equations describing soilbased herbicide transfer to runoff were power functions with exponents near unity with the form: Y = a xb. Simple relationships such as those developed in this study along with hydrology and erosion/sediment models may he useful in predicting pesticide runoff potential when assessing relative impacts of management decisions. The next step would be to describe key management practices in terms of these coefficients and exponents.
The Effect of Soil‐added Cadmium on Several Plant Species
Authors: Miles L. J. , Parker G. R. 
Published: July 2010

AbstractSeveral species (Andropogon scopanus, Shus radicans, Rudbeckia hirta, Anemone cylindrica, Monarda fistulosa, Poa pratensis, and Liatris spicata) native to northwestern Indiana were grown from seed in the greenhouse for 6 weeks. An uncontaminated sandy soil was utilized as the substrate with four levels of soil‐added Cd. The concentrations added ranged from 0 to 100 µg Cd/g soil and were comparable to surface soil Cd concentration levels found in the urban‐industrial region of northwestern Indiana.Data on germination, survival, height, and dry weight were collected. Germination, survival, and weight were found to exhibit a negative response to increasing soil Cd concentration over all species. Height, however, was not found to be a consistently good indicator of Cd response. While overall species' differences were noted, no differences could be conclusively shown among the species for Cd tolerance, although there were indications that this was the case. All effects noted were of a low level for the soil‐added Cd concentrations utilized.
Factors Influencing the Volatilization of Mercury from Soil
Authors: Rogers Robert D. , Mc Farlane James C. 
Published: July 2010

AbstractMercury volatilization from soils amended to 1 ppm mercury with mercuric nitrate decreased substantially within 1 week after application. During the first week, 20% of the applied mercury was lost from a silty clay‐loam soil and 45% was lost from a loamy sand soil. Volatilization of Hg from the loamy sand soil resulted in a concurrent decrease in ammonium nitrate‐extractable mercury. Other work with sterile soil indicates that the volatilization was mediated by microorganisms.
Transformations of Carbon, Nitrogen, and Metals in Soils Treated with Waste Materials
Authors: Sommers L. E. , Nelson D. W. , Silviera D. J. 
Published: July 2010

AbstractIntact soil cores were used to evaluate decomposition, NH3 volatilization, N transformations, and metal movement in soils treated with sewage sludges and antibiotic processing wastes. Soil cores were leached monthly with water and incubated for 1 year. An insignificant amount (<1%) of the NH4+‐N applied was lost through NH3 volatilization. The addition of wastes to five soils established that soil properties did not influence decomposition. In contrast, appreciable differences in decomposition were observed when different wastes were added to the same soil. Significant amounts of NO3− were leached from soils treated with antibiotic wastes, while essentially no NO3− leaching occurred in soils receiving sewage sludge, suggesting that denitrification and/or immobilization are major N loss mechanisms in soils treated with sewage sludge. Minimal amounts of P and metals were leached from sludge‐amended soils. Soil analysis indicated that the majority of the added Zn, Cu, Cd, Ni, and Pb remained in the zone of sludge incorporation (0–7.5 cm) with minimal or no movement into the 7.5‐ to 15‐cm soil depth.
Sediment and Nutrient Yield from Residential Construction Sites
Authors: Daniel T. C. , Mc Guire P. E. , Stoffel D. , Miller B. 
Published: July 2010

AbstractRunoff from three residential construction site watersheds in southeastern Wisconsin was monitored for a 2‐year period. Automatic water quality monitoring equipment was established which sampled each event proportional to flow. Loading rates for sediment and nutrients were developed on an event basis and summed to produce annual loads.Concentrations for suspended solids (SS), organic plus exchangeable N [(Or + Ex)‐N], and total P preceded and paralleled the flow rate during runoff events. With the exception of nitrate plus nitrite nitrogen (NO3 + NO2)‐N, the soluble water quality parameters were independent of flow. Commonly, the (NO3 + NO2)‐N concentration was 1.0 mg/liter and varied inversely proportional to flow. The most common concentrations of dissolved phosphorus and ammonium were 0.05 and 0.10 mg/liter, respectively.Average sediment yield for the three single land use watersheds was 19.2 metric tons /ha per year. Concentrations of 60,000 mg/liter SS were observed for major events; 15,000 to 20,000 mg/liter were common for moderate events. Regression analyses of several independent variables identified flow (Q) as the single most important variable examined for explaining sediment load. Considered in combination, the product of flow and flow rate (Qqp) best explained sediment yield (r2 = 0.62).Yields of contaminants from residential construction sites are inherently variable and site dependent. Strict extrapolation or comparison of results to other areas or existing literature values is difficult. However, when compared to runoff data from a simultaneous agricultural watershed investigation, the yield of contaminants from construction sites is considerably higher (19.2 vs. <1 metric ton/ha per year of sediment).
Decomposition of Anaerobically Digested Sewage Sludge as Affected by Soil Environmental Conditions
Authors: Terry R. E. , Nelson D. W. , Sommers L. E. 
Published: July 2010

AbstractMicrobial oxidation of organic components in anaerobically digested sludge is an important aspect of the fate of sludges in soils. The objectives of this study were to determine the effects of soil characteristics, sludge management procedures, and environmental conditions on the decomposition rate of sewage sludge in soils. Synthetic sewage sludge was prepared by anaerobically digesting a mixture of 14C‐labelled Candida utilis cells and inorganic salts. The sludge prepared was similar in composition to anaerobically digested municipal sludges. After incorporation into soil, decomposition of sludge was rapid during the first 28 days, but the decomposition rate was low and relatively constant for the remainder of the incubation period. At the end of 336 days of incubation, 46% of synthetic sludge organic 14C was evolved as CO2, suggesting that one fraction of anaerobically digested sludge was readily decomposable when added to an aerobic soil. However, the major portion of sludge organic matter was resistant to decomposition. Factors such as soil texture, pH, and moisture content had little effect on sludge decomposition rates. Decomposition was greatest in soil samples receiving surface‐applied sludge and in samples incubated at high temperature (30°C) as compared to samples having sludge incorporated or incubated at 21°C.
Acidification of Headwater Streams in the New Jersey Pine Barrens
Authors: Johnson Arthur H. 
Published: July 2010

AbstractSixteen years of stream pH data indicate acidification of two relatively undisturbed headwater streams of the New Jersey Pine Barrens. Average yearly stream pH decreased approximately 0.2 to 0.5 units in the two small streams that have long‐term records. Hydronium ion concentration is correlated with SO4 in the two headwater streams in approximately a 1:1 ratio by equivalents, suggesting that H2SO4 is an important source of the acidity. A decrease in precipitation pH over the period is suggested in the literature and may be responsible for the decreasing stream pH.