bluuebunny/crossref_metadata_2025 huggingface dataset:
Abiological Methylation of Mercury in Soil
Authors: Rogers Robert D.
Published: July 2010

The results from this work define several factors influencing the methylation of mercuric ion in soil. Two of the most important findings were that it is possible to extract the mercury methylating factor from soil with a solution of 0.5/V sodium hydroxide (NaOH) and that this factor is responsible for the abiological methylation of Hg in the soils under investigation.

The ability of the soil extract to methylate Hg is influenced by temperature, mercuric ion concentrations, and solution pH. In addition, it was found that the methylating ability of the soil extract was stable at high temperatures (121C), but was lost after exposure to ultraviolet radiation.

When the 0.5/V NaOH extract of soil was separated into a soluble fraction and an insoluble precipitate, the ability to methylate mercuric ion remained with the soluble fraction. It was found that the methylating factor was lost when the 0.5/V NaOH extract was dialyzed against distilled water. Other work showed that the methylating factor passes through dialysis tubing into the distilled water.
Nitrogen Fertilizer and Nitrate Concentrations in Tributaries of the Upper Sangamon River in Illinois
Authors: Klepper Robert
Published: July 2010

Cross section multiple regressions were used to test the importance of nitrogen fertilizer use for variations in the nitrate nitrogen concentrations in 16 small tributaries of the Sangamon River in east central Illinois. Data were collected and regressions were run for 2 years, 1974 and 1975. Nitrate nitrogen concentrations in the spring of each year were regressed on estimated nitrogen fertilizer use per hectare of watershed in the previous crop or calendar year and variables representing other aspects of agronomic practice and hydrologic features. The fertilizer data were collected by surveying approximately 300 farmers. Nitrate nitrogen concentrations were measured at 4‐week intervals. The regression results are not clear‐cut but lend support to nitrogen fertilizer use as an important explanatory variable for variations in nitrate nitrogen concentrations.
Nitrate Leaching During Long‐term Spray Irrigation for Treatment of Secondary Sewage Effluent on Woodland Sites
Authors: Hook J. E. , Kardos L. T.
Published: July 2010

Two waste water‐treated sites at The Pennsylvania State University Wastewater Renovation Project were monitored to measure nitrate and total N in soil water. Both long‐term waste water irrigation and varied irrigation rates were examined. Soil water was sampled by porous cup samplers. The concentration of N at the 120‐cm depth was taken as a measure of N which escaped the root zone and which would leach to the ground water. Recharge volume was calculated from irrigation, rainfall, and potential evapotranspiration.

A hardwood forest site located on a well‐drained sandy loam soil was irrigated year round with secondary municipal effluent at a rate of 5 cm/week. In the last 6 of 9 years of effluent treatment 83% of the 4,954 kg N/ha added leached from the site. Nitrate concentration in soil water at the 120‐cm depth was generally > 15 mg N/liter. The hardwood forest was also ineffective in keeping nitrate concentration below 10 mg N/liter at the 120‐cm depth when the 5‐cm weekly application was split into two 2.5‐cm irrigations or when it was lowered to 2.5 cm/week year round.

An abandoned old field site planted with white spruce (Picea glauca Moench) and located on a well‐drained clay loam soil was irrigated with effluent at 5 cm/week from Apr. through Nov. each year, beginning in 1963. Nitrate concentration at the 120‐cm depth rarely exceeded 10 mg N/liter and only 36% of the 1,246 kg N/ha applied leached during the 6th through the 9th years of this effluent treatment. In the 10th and 11th years, when the application rate was increased to 7.5 cm/week, nitrate concentration exceeded 10 mg N/liter at the 120‐cm depth, and the amount of N which leached increased to 75% of the amount applied.
Survival and Movement of Fecal Indicator Bacteria in Soil under Conditions of Saturated Flow
Authors: Hagedorn C. , Hansen D. T. , Simonson G. H.
Published: July 2010

Antibiotic‐resistant fecal bacteria were used to monitor the degree of movement and subsequent ground water contamination by septic‐tank effluent discharged into a drainfield under saturated conditions. Two pits of different depths were constructed to simulate drainfield beds, and ground water samples were removed during 32‐day sampling intervals from sampling wells installed at set distances from each inoculation pit. The bacteria added to the deep pit were released into a B2t horizon which contained a higher clay content than the A horizon in which the shallower pit was installed. Streptomycin‐resistant strains of Escherichia coli and Streptococcus faecalis amended to each pit site moved in a directional manner, required more time to reach sampling wells when inoculated into the deeper of the two pits, and moved relatively long distances when considering that the area where the sites were located had only a 2% slope. Bacterial numbers peaked in the sampling wells in association with major rainfall patterns and the populations required longer periods to peak in the wells furthest from the inoculation pits. The results indicated that antibiotic‐resistant bacteria eliminated the problem of differentiating between the amended bacteria and those nonresistant strains already in the soil, and the potential is excellent for including this type of microbiological procedure for assessing the suitability of a soil site for septic‐tank and waste water drainfield installations.
Availability of Sulfur in Fly Ash to Plants
Authors: Elseewi Ahmed A. , Bingham F. T. , Page A. L.
Published: July 2010

Fly ash from a coal‐fired power plant was added to soil in variable amounts and the availability of sulfur to a variety of plant species from this source was compared to that of gypsum. The study was conducted under greenhouse conditions with a calcareous and two acid soils which were low in plant‐available sulfur.

The fly ash used contained 0.4% S, all of which is extractable by NH4OAc. When mixed with a calcareous and an acid soil at rates of 1–2% by weight, the fly ash corrected a S deficiency in the soil and maximized the yield of alfalfa (Medicago sativa L.) and bermudagrass (Cynodon dactylon L.). The increase in yield (twofold to threefold in alfalfa and 40 to 70% in bermudagrass) was accompanied by an increase in the S content of the plant tops from a deficiency level (< 0.1%) to a sufficiency level (≥ 0.2%). The availability of fly ash‐S and gypsum (CaSO4·2H2O)‐S was compared by the addition of equal amounts of S from the two sources (25‐, 50‐, and 100‐mg S/kg soil) to an acid soil. Yield and S content of turnip (Brassica rapa L.) and white clover (Trifolium repens L.) were equally improved, demonstrating that the availability of fly ash derived‐S is equivalent to that of gypsum‐S.
Trophic Status Related to Sediment Chemistry of Canadian Prairie Lakes
Authors: Allan R. J. , Williams J. D. H.
Published: July 2010

Concentrations of different sediment phosphorus forms vary in the Prairie lakes studied. Extremely high surface sediment available P concentrations in the Fishing Lakes of southern Saskatchewan were related to P loading from municipal and other cultural sources. Mean available P concentrations in surface sediments from the Fishing Lakes are higher than those found in other Prairie lakes and in most other Canadian lakes. Sediment cores show that presettlement concentrations of available P in the Fishing Lakes are higher than occur today in surface sediments from culturally eutrophied lakes, such as Lake Erie, elsewhere in Canada.

Free iron is concentrated in the surface 10 to 15 cm of sediment cores from the Fishing Lakes and Lake Erie. Such a distribution, when coupled to low free Fe/available P ratios, is considered to reflect conditions favorable for P regeneration when anoxic conditions develop under winter ice cover.

For the winter of 1976–1977, a mean sediment phosphorus release rate of 8.6 mg/m2 per day was calculated for the Fishing Lakes.
Influence of Cadmium and Zinc on Carbon Dioxide Evolution from Litter and Soil from a Black Oak Forest
Authors: Chaney W. R. , Kelly J. M. , Strickland R. C.
Published: July 2010

Studies have shown that heavy metals can reduce decomposition rates. Since litter decomposition is an essential part of forest mineral cycles, understanding the degree of impact that these substances have on such a key process is important. Two similar black oak forests, East Chicago (impacted) and Willow Slough (background), were chosen as study areas. Microcosms containing litter and mineral soil were collected at each site and returned to the laboratory where comparative measurements of carbon dioxide evolution were taken at 0, 12, 36, and 84 hours, and at 23 days. Measurements indicated a higher decomposition rate for the Willow Slough microcosms (138 mg CO2/hour per kg at 23 days) compared to the East Chicago microcosms (94 mg CO2/hour per kg). Additional microcosms from Willow Slough were treated with solutions containing all possible combinations of 0, 0.1, or 10 ppm CdCl2 and 0, 100, or 1,000 ppm ZnCl2. Metal concentrations applied were equivalent to litter and soil levels at East Chicago. Statistically significant differences were detected only 36 hours and 23 days after treatment. Reduced respiration rates were associated with high concentrations of CdCl2/ZnCl2. Suppression of respiration rates due to osmotic effects of metal salts was rejected after microcosms treated with KCl and CaCl2 exhibited no change in respiration. While high levels of cadmium and zinc produced reductions in respiration rates compared to controls, low level treatments may have stimulated decomposition slightly.
Erosional Transport and Deposition of Plutonium and Cesium in Two Small Midwestern Watersheds
Authors: Muller Robert N. , Sprugel Douglas G. , Kohn Barbara
Published: July 2010

The soils and sediments of two small watersheds and their retaining ponds were sampled in a study of the erosional transport of plutonium and cesium in midwestern ecosystems. In a watershed which had been used exclusively for row crops no relationship was observed between plutonium content of the sediments and location in the pond or clay content. In a pasture watershed sorting of the eroded material had occurred prior to entry into the pond and also within the pond. Clay content in the pasture pond sediments was significantly higher than in the soils of the surrounding watershed and increased with increasing distance from the inlet. Plutonium concentration in the sediments was strongly correlated with clay content, reflecting the higher plutonium content of finer soil particles. Cesium behaved similarly to plutonium in the soils and sediments of both watersheds. Where sorting occurs, as in the pasture watershed, deposits of fine sediments will contain higher plutonium and cesium concentrations than in the original surface soil.
Gel Filtration Studies of Trace Metal‐Fulvic Acid Solutions Extracted From Sewage Sludges
Authors: Baham John , Ball N. B. , Sposito Garrison
Published: July 2010

Trace metal‐fulvic acid solutions extracted with NaOH from two chemically different sewage sludges and separated from humic acid using HCl were fractionated on a column of Sephadex G‐10 gel using deionized water at pH 5.65 as the eluant. The effluent from the gel was analyzed in 3‐ml increments for organic C, Cl, and the metals Cd, Cu, Fe, Ni, and Zn. Elution diagrams prepared with the analytical data showed multiple maxima in organic C concentration and a single maximum in Cl concentration (indicating the presence of inorganic salts). Fe and Cu showed concentration maxima that followed closely those in both the organic and inorganic fractions, while Cd, Ni, and Zn tended to show maxima following the inorganic fraction peak and only one or two of the organic C maxima. The data indicated that Cu and Fe formed complexes with sludge‐derived fulvic acid (FA) under the conditions of the experiment. Cd, Ni, and Zn were associated with the FA only weakly, in a manner dependent on the nature of the sludge, and in the relative order of affinity Zn > Ni > Cd. These data suggested that sludge‐derived FA behaves toward trace metals as a relatively harder Lewis base than Cl−.

Infrared spectra of the eluted organic fractions indicated that protein decomposition products and polysaccharide components appear in the fractions of relatively larger molecular size, as do the components containing SO3H groups. The IR spectra also gave evidence that COOH and SO3H functional groups are involved in metal‐FA interactions. An important organic fraction of sludge‐derived FA was identified that appears to be an aliphatic, carboxylic acid mixture which can complex only Cu significantly.
Nitrification and Denitrification in Cattle Manure‐Amended Soil
Authors: Guenzi W. D. , Beard W. E. , Watanabe F. S. , Olsen S. R. , Porter L. K.
Published: July 2010

Dry cattle manure was mixed with soil at a rate of 45 and 90 metric tons/ha and amended with K15NO3, and (15NH4)2SO4 in separate treatments. The greenhouse experiment included an uncropped and a sorghum (Sorghum vulgure Pers.) treatment. Soil atmosphere was analyzed for CO2, N2, O2 + Ar, N2O, and enriched 15N2. The energy‐rich manure created a high biological oxygen demand and caused low O2 and high CO2 concentrations in the soil environment. Evidence for denitrification was obtained by the presence of N2O and 15N enriched N2‐in the soil gases for the manure treatments amended with 15NO3− and 15NH4+. The 15N enriched N2 in the soil gases in the uncropped soil decreased to background levels after 10 days in the NO3−‐amended manured soils, whereas 15N2 enrichment from 15NH4+‐amended manured soils existed at 39 days. The recovery of NO3−‐15N in the uncropped soils was 90.2% without manure, 9.4% with 45, and 8.1% with 90 metric tons/ha of manure. Recovery of NH4+‐15N in the uncropped soil was 92.2% without manure, 60.3% with 45, and 57.0% with 90 metric tons/ha of manure. Higher concentrations of added fertilizer N were recovered in the cropped system. In this study, where manure was mixed thoroughly with soil, water was added daily to field capacity, and O2 concentrations were never below 3.1%, denitrification must have occurred in anaerobic microsites in a predominantly aerobic system. The results for the NH4+‐manure treatment demonstrated that both nitrification and denitrification occurred simultaneously.
Seasonal Runoff Losses of Nitrogen and Phosphorus from Missouri Valley Loess Watersheds
Authors: Alberts E. E. , Schuman G. E. , Burwell R. E.
Published: July 2010

Seasonal losses of nitrogen and phosphorus in surface runoff were determined for a 7‐year period from three corn‐cropped watersheds in southwestern Iowa. Three seasonal periods were defined: fertilizer, seedbed, and establishment period from April through June (P1); reproduction and maturation period from July through November (P2); and residue period from December through March (P3).

Most of the average annual total N and P losses were associated with the sediment portion of runoff and occurred during P1. The extreme susceptibility of the loess soils to erosion during P1 must be taken into account when designing conservation practices to control plant nutrient losses. Seasonal discharges of runoff, sediment, and nutrients were much lower from a level‐terraced watershed than from two contour‐farmed watersheds, which demonstrates the benefit of terracing in resource conservation.

Average annual soluble N and P losses were quite low and never exceeded 1% of the annual fertilizer application. These losses were the highest during P3 from the contour‐farmed watersheds.

Water and sediment weighted nutrient concentrations were the highest from the contour‐farmed watersheds during P3, when residues covered the soil surface. Leaching of soluble nutrients from the residue and the greater selectivity of the soil erosion process for the finer fractions of the soil (i.e., clay and organic material) during snowmelt runoff are probably the factors responsible.
Availability of Sulfur in Sewage Sludge to Plants: A Comparative Study
Authors: Elseewi Ahmed A. , Page A. L. , Bingham F. T.
Published: July 2010

Alfalfa (Medicago saliva L.), white clover (Trifolium repens L.), and turnip (Brassica rapa L.) were grown on calcareous and acid soils low in available sulfur amended with sewage sludge and gypsum (CaSO4·2H2O) at rates equivalent to 0 and 80 ppm S for alfalfa and 0, 25, 50, and 100 ppm S for white clover and turnip. The availability of S from the two sources was evaluated through measurements of yield, total‐S concentration in the plant tissue, S uptake expressed in mg/pot, S recovery, and SO4‐S concentration in the soil. Addition of either sludge or gypsum corrected the S deficiency in the plants and significantly increased the dry matter yields. Improvements in yields were associated with increased S concentrations in the plant from deficiency levels (0.010 to 0.088%) to levels ≥ 0.2%. The average ratio of total S concentration in the sludge‐treated plants to that in the gypsum‐treated plants was 0.83, and the average S uptake and S recovery ratios were 1.09 and 0.95, respectively, indicating comparable availability of S in the two sources. Initial concentrations of NH4‐OAc‐extractable SO4‐S in the soil were increased twofold to sevenfold by application of sludge to the soil. The ratio of post‐harvest SO4‐S in sludge‐ and gypsum‐treated soils ranged from 0.39 to 2.27 with a mean of 0.95. The results demonstrate that sewage sludge is a potential source of available S to plants.
Persistence of Tebuthiuron in Surface Runoff Water, Soil, and Vegetation in the Texas Blacklands Prairie
Authors: Bovey R. W. , Burnett E. , Meyer R. E. , Richardson C. , Loh A.
Published: July 2010

The concentration of tebuthiuron (N‐[5‐(1,1‐dimethylethyl)‐1,3,4‐thiadiazol‐2‐yl)‐N,N′‐dimethylurea) applied in the spray or pellet form was measured in surface runoff water from watersheds which received natural or simulated rainfall. The persistence of tebuthluron in soil and vegetation was also investigated.

Pelleted tebuthiuron was applied at 2.24 kg/ha (active ingredient) to a 1.3‐ha rangeland watershed. A 2.8‐cm rain, 2 days after application, produced 0.94 cm runoff which contained an average of 2.2 ppm of tebuthiuron. Tebuthiuron concentration decreased rapidly with each subsequent runoff event and after 3 mo was <0.05 ppm; none was detected in runoff water 1 year after treatment. The concentration of tebuthiuron, applied as a spray at 1.12 kg/ha, decreased to <0.01 ppm within 4 mo in runoff from a small plot which received simulated rainfall. On 0.6‐ha plots, mean tebuthiuron (sprays and granules) concentration was 0.50 ppm or less in water when the first runoff event occurred 2 mo after application. Concentrations of tebuthiuron in soil and grass from pellet applications were low (<1 ppm) and decreased with time.
Cadmium‐Enriched Sewage Sludge Application to Acid and Calcareous Soils: Effect on Yield and Cadmium Uptake by Lettuce and Chard
Authors: Mahler R. J. , Bingham F. T. , Page A. L.
Published: July 2010

Eight soils with pH values ranging from 4.8 to 7.8 were treated with 1% sewage sludge amended with variable amounts of CdSO4. The concentration of Cd in the soils ranged from 0.1 to 320 µg Cd/g. Lettuce (Lactuca sativa var. longifolia) and Swiss chard (Beta vulgaris vat. cicla) were grown to maturity in pot cultures on the treated soils to determine the effect of soil pH on yield and Cd uptake. Fifty percent yield decrements for acid and calcareous soils, respectively, were associated with the following concentrations of Cd in soil: lettuce—214 and 139 µg/g; chard—175 and 250 µg/g. Tissue concentrations of Cd associated with the 50% yield decrement for acid and calcareous soils, respectively, were as follows: lettuce—470 and 160 µg/g; chard—714 and 203 µg/g.

Multiple regression analysis of yields as a function of pH, CEC, % CaCO3, % organic carbon (OC), % sand‐silt‐clay, and Cd addition rate revealed a highly significant yield relationship with Cd addition rate, % OC, % clay, and pH (lettuce: R2 = 0.82***; chard: R2 = 0.93***). Leaf Cd was significantly related to soil parameters as follows: lettuce—saturation extract Cd and CEC, R2 = 0.82***; chard—saturation extract Cd and pH, R2 = 0.89***.
Fate of 2,4‐D in a Naff Silt Loam Soil
Authors: Wilson R. G. , Cheng H. H.
Published: July 2010

Laboratory studies were conducted to determine the adsorption, desorption, hydrolysis, and breakdown of commercially formulated isooctyl ester and dimethylamine salt of 2,4‐D [(2,4‐dichlorophenoxy) acetic acid] in a Naff silt loam soil. More 2,4‐D was adsorbed to the surface soil than to soil at lower depths, and the percentage of 2,4‐D adsorbed decreased as the total amount of 2,4‐D present increased. Adsorbed 2,4‐D was gradually desorbed from soil by successively exchanging the solution in equilibrium with soil with distilled water. Formulated 2,4‐D isooctyl ester applied to moist soil underwent hydrolysis to the anionic form at a rapid rate, with >80% of the ester hydrolyzed in 72 hours. High amounts of 2,4‐D in runoff (sediment and water) retarded the active degradation of carboxyl‐14C 2,4‐D when 2,4‐D was incubated in runoff from a wheat field treated with various formulations and rates of 2,4‐D. The presence of the ester formulation at the high rate of application increased the lag period before degradation of carboxyl‐14C and ring‐14C 2,4‐D occurred in soil. However, once the active breakdown of carboxyl‐14C and ring‐14C 2,4‐D was initiated, little difference could be detected in the degradation patterns. At the end of the 10 weeks of incubation in runoff or in soil, only 1% of the 14C‐2,4‐D originally applied to the soil could be identified as 2,4‐D.
Effects of Evaporative Salt Water Cooling Towers on Salt Drift and Salt Deposition on Surrounding Soils
Authors: Wiedenfeld R. P. , Hossner L. R. , McWilliams E. L.
Published: July 2010

Five salt water cooling towers recently constructed near Galveston Bay, Texas, have been shown to contribute to salt deposition in the surrounding area. Levels as high as 1,200 kg/ha per year of total salt were encountered within 100 m of the towers, but decreased in a logrithmic fashion with distance to <300 kg/ha per year at 434 m with only 16% attributable to the cooling towers. The remaining deposition was caused by natural sea spray which varies widely but averages about 250 kg/ha per year in the study area. Changes in composition of air‐borne salts with distance from the cooling towers were noted, primarily as a narrowing of the Na/Ca ratio. Salinity levels in the soil are in equilibrium with naturally deposited salts. Enhanced salt deposition levels due to the cooling towers initially caused only slight effects in the soils closest to the towers, but may eventually lead to both salinization and solonization in the surrounding vicinity.
Radiological Investigations of an Abandoned Uranium Tailings Area
Authors: Moffett D. , Tellier M.
Published: July 2010

Tailings have been accumulating in the Elliot Lake area since mining started some 20 years ago. The tailings solids were impounded by construction of dams, resulting in the discharge of a clear and neutral outflow which at that time was considered to be a satisfactory practice. However, acid generated in the tailings by oxidation of pyrite has solubilized certain heavy metals which can escape through the semiporous embankments or as outflow during heavy rainfalls. It is now evident that these areas, some of which have been idle for over 12 years, release acids and certain naturally occurring radionuclides to an unacceptable degree. In most cases the acid tailings outflows are neutralized to pH 8.5 to precipitate these heavy metals. This neutralization will have to be continued indefinitely, unless a better remedy is found.

An investigation is underway at a 16‐ha pyrite‐containing uranium tailings area to determine what happens to certain radioactive elements. The analysis of solid samples showed the activities of 226Ra, 210Pb, and 210Po were lower than could be accounted for by their radioactive decay since disposal. Uranium and thorium also have been significantly leached out of the tailings surface. The collection and analysis of water samples from the water table beneath the tailings area revealed two classes of water: a low‐acid class (<1,000 ppm acidity) and a high‐acid class. The acidity of the water was directly related to the weathering of pyrite in the surface layers of the tailings. The high‐acid water samples generally contained higher concentrations of 210Pb, 232Th, 230Th, 220Th, and uranium than low‐acid water samples. The low‐acid water samples contained only elevated concentrations of 226Ra which, if released untreated, would exceed water quality criteria. See page samples below the tailings dam were also monitored and analyzed, and may exceed desirable water quality criteria for 226Ra and 210Pb if not treated.
Effects of Liquid Swine Waste Applications on Corn Yield and Soil Chemical Composition
Authors: Sutton A. L. , Nelson D. W. , Mayrose V. B. , Nye J. C.
Published: July 2010

A 2‐year field experiment was conducted to study the effects of salt (0.2 and 0.5%) in swine rations, liquid waste handling systems (aerobic and anaerobic), and application rates on the recycling of swine wastes to Fox silt loam and Chalmers silt loam soils cropped to corn (Zea mays L.).

Liquid swine waste (1.8 to 3.0% dry matter) was applied annually at rates of 45, 90, and 134 metric tons/ha. The high rate provided an average of 378 kg N, 113 kg P, 163 kg K, and 42 kg Na per ha. Check and inorganic fertilizer (168 kg N/ha, 56 kg P/ha, 112 kg K/ha) treatments were included.

Soil Na, nitrate N, and extractable P concentrations increased with increasing waste application rates. Soil electrical conductivity was not affected by waste application rate. The effects of dietary salt levels and waste handling systems on the chemical composition of the soils were inconsistent.

There was evidence for downward movement of Na, K, and NO3− in the soil profile of plots receiving waste and fertilizer. Downward movement of NO3− was observed to a greater extent in fertilizer‐treated plots than in waste‐treated plots. Under climatic conditions prevailing in this study, 2 years of waste application had no detrimental effects on the chemical composition of the two silt loam soils.

Soil application of waste resulting from different dietary salt levels and waste handling systems resulted in similar corn yields and leaf chemical composition. Yields were higher from plots treated with waste and inorganic fertilizer compared to the check plot. Corn yields increased with increasing rates of waste application up to the 90‐metric tons/ha rate, then leveled off. Nitrogen, P, and K concentrations in corn ear leaf tissue increased with increasing waste applications.
Metal Distribution in Forested Ecosystems in Urban and Rural Northwestern Indiana
Authors: Parker G. R. , Mc Fee W. W. , Kelly J. M.
Published: July 2010

Metal distribution in vegetation and soil components, annual inputs, and losses were determined in undisturbed urban and rural ecosystems in northwestern Indiana. The urban area has been exposed to contamination from industrial and other urban sources for about 100 years. The levels of cadmium, zinc, copper, and lead (Cd, Zn, Cu, and Pb) were significantly higher in the soils and vegetation on the urban site compared to a similar system in a rural setting 67 km away. Metal concentration in the top 2.5 cm of soil averaged 10 ppm Cd, 2,456 ppm Zn, 463 ppm Pb, and 119 ppm Cu. This was 20 to 100 times more concentrated than that found on the rural site. The surface litter (O horizon) on the urban site also had four to nine times greater metal concentration and total metal quantities were many times greater in the urban ecosystem than on the rural site. The higher soil levels were reflected in higher concentrations in most plant species, but species differed greatly in metal levels.

Greater than 95% of the weight of all four metals was found in the soil (0–25 cm) for both dune and wetland ecosystems. The remaining metal burden is equally distributed between the surface litter and the plant biomass.

Slightly more Cd and twice as much Zn entered the urban site than the rural site during 1975–76. Annual input of Pb and Cu was four times greater on the urban site. While pollution control has apparently reduced annual input to the urban site, metal concentrations will remain high due to the low rates of leaching losses measured.
Timing and Rate of Fertilizer Nitrogen for Sugarbeets Related to Nitrogen Uptake and Pollution Potential
Authors: Hills F. J. , Broadbent F. E. , Fried Maurice
Published: July 2010

Nitrogen (N) uptake by sugarbeets (Beta vulgaris L.) from fertilizer and soil, as related to time and rate of application, was evaluated at Davis, California, in two field experiments utilizing 15N‐deleted ammonium sulfate. There were no significant differences in root, top, or sugar yield when fertilizer N (135 kg/ha) was applied at planting, at thinning, split equally between thinning and layby, or split equally between planting, thinning, and layby. Also, there were no substantial differences in soil or fertilizer N in tops and roots in response to these dates of application.

Fertilizer N recovery was 47% when 112 kg N/ha were applied to achieve maximum sugar yield. Roots removed as much N as that applied and tops contained an additional 105 kg N/ha. When applied N was 2.5 times the amount required for maximum sugar yield, tops and roots contained almost as much N as applied. The sugarbeet crop, carefully fertilized, has potential for alleviation of nitrate pollution of ground water.
Zinc and Cadmium Contents of Agricultural Soils and Corn in Northwestern Indiana
Authors: Pietz R. I. , Vetter R. J. , Masarik D. , Mc Fee W. W.
Published: July 2010

Soil and corn (Zea mays L.) leaf and grain samplings were conducted in northwestern Indiana to determine if airborne heavy metal particulates containing Cd and Zn from the northwestern Indiana industrial‐urban complex, situated on the south side of Lake Michigan, were contaminating soils and crops. Sampling in the region revealed no widespread metal contamination. Some metal enrichment had occurred on agricultural soils in Gary and East Gary, Ind. Corn leaf concentrations of Cd, Pb, and Zn fluctuated with sampling location, but grain Cd and Pb levels remained essentially constant at <0.05 and <0.4 µg/g, respectively. A comparison of Zn/Cd ratios in soils, and in corn leaves and grain, suggested that Cd was more actively accumulated in the corn plant but not the grain.

Because of the limited acreage affected and the relatively low metal levels observed, no human or animal health problems are expected from harvested crops or silage.

The use of log distance vs. log metal concentration in regression analysis showed that the limited metal contamination of agricultural soils was mainly in a southeasterly direction from the industrial‐urban area.
Influence of the Chemical Form of Mercury on its Adsorption and Ability to Leach Through Soils
Authors: Hogg T. J. , Stewart J. W. B. , Bettany J. R.
Published: July 2010

The adsorption of Hg by two soils, differing in chemical and physical characteristics, indicated that both organic Hg compounds (methyl mercuric chloride [MMC] and phenyl mercuric acetate [PMA]) and inorganic compounds (mercuric chloride [HgCl2]) followed the linear form of the Langmuir adsorption isotherm. The highest adsorption maxima for all Hg compounds were found for the soils which had the higher organic matter content and clay content. Adsorption maxima increased in the order MMC < PMA < HgCl2.

A two‐rate effluent leaching experiment was conducted utilizing undisturbed soil cores of the same two soils and the same three Hg compounds (labeled with 203Hg) which were applied uniformly to the top 0–10 cm of each column. In contrast to the movement of other cations in the effluent and soil, even at the higher irrigation rate, none of the applied Hg was found to move below the 10‐ to 20‐cm soil layer. More MMC than HgCl2 or PMA were found in the 10‐ to 20‐cm layer; however, the differences were small. The lack of movement of Hg and the high adsorption maxima was a consequence of the strong binding between Hg compounds and soil. The inability of weak chemical extractants (CaCl2, NH4OAc, DTPA, EDTA) to remove significant quantities of Hg confirmed this hyphothesis. Seven to 31% of the applied Hg was lost from the columns during the experiment presumably by volatilization.
The Uptake of 203Hg‐Labeled Mercury Compounds by Bromegrass from Irrigated Undisturbed Soil Columns
Authors: Hogg T. J. , Bettany J. R. , Stewart J. W. B.
Published: July 2010

Bromegrass (Bromus inermis) was grown under conditions of sewage effluent irrigation on undisturbed soil columns in which the 0‐ to 10‐cm layers had been treated with 10 µg Hg/g soil as 203Hg‐labeled mercuric chloride (HgCl2), phenyl mercuric acetate (PMA), and methyl mercuric chloride (MMC). Mercury concentrations in plant dry matter decreased over three successive harvests and highest values were found on MMC‐treated soils of fine texture and low organic matter content (2.0 to 0.2 µg Hg/g for first and third harvest, respectively).

Exposure of the plants and soils to simulated fall conditions resulted in a small but significant increase in the Hg concentration of plant dry matter. Higher levels of Hg were found in plant stems (up to 0.88 µg Hg/g) than plant foliage (up to 0.24 µg Hg/g) at the termination of the experiment and even higher levels in the main roots (up to 42.5 µg Hg/g) and fine roots (up to 106.4 µg Hg/g) separated from the 0–10 cm soil layer. Mercury concentration of roots decreased with depth for all Hg treatments but were still 150 times greater than background levels in the MMC‐treated soils at the 40‐ to 60‐cm depth. A significant amount of all forms of applied Hg (10–32%) was lost during the experiment, presumably by volatilization. The majority of the remaining Hg in the soil was found to be strongly bound and not extractable by weak salt solutions, dilute acids, and chelates.
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

Field 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

Agricultural 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

Levels 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

Nitrate 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

Aflatoxin, 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

Because 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

Water 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

The 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

Technetium (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.