bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport Times of Dissolved Inorganic Phosphate in Soils
Authors: Gerritse R. G.
Published: July 2010

An empirically based equation is proposed for calculating the decrease, relative to water, of the mobility of phosphate in columns of soil, with increasing distance travelled and decreasing flow rate. The equation requires experimental determination of two parameters: the ratio of added phosphate in adsorbed and mobile phases of a soil, 1 d after an addition, and a coefficient determined by the decrease in rate of adsorption of phosphate with time. Breakthrough times of phosphate were obtained from leaching step increases in the concentration of dissolved phosphate through saturated columns of soil for a wide range of concentrations, rates of flow, soils, and column lengths. Calculated and experimentally observed mobilities of phosphate, relative to water, appear to fit a log‐linear relationship. This relationship allows prediction of mobilities of phosphate in soils at rates of flow and for distances travelled that are representative of field conditions.
Sorption and Degradation of Bentazon in Conventional‐ and No‐till Dundee Soil
Authors: Gaston L. A. , Locke M. A. , Zablotowicz R. M.
Published: July 2010

Herbicides applied postemergence, such as bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide], reach the soil surface due to incomplete interception by the plant canopy or foliar washoff. Thus, potential off‐site transport is influenced by sorption equilibrium/kinetics and degradation. This study addressed the effects of tillage practice on the sorption and degradation of 14C‐labeled bentazon using Dundee silt loam soil (fine‐silty, mixed, thermic, Aeric Ochraqualf) taken from the conventional‐till (CT) and no‐till (NT) treatments of a tillage experiment without bentazon exposure for more than 3 yr. Data were generated for surface and subsurface samples. The kinetics of bentazon sorption in CT surface soil were rapid, with apparent equilibrium achieved in 1 h. Furthermore, the extent of sorption was low and the equilibrium distribution of solution and sorbed bentazon could be described using a linear model. Differences in soil organic matter between tillage treatments and with depth were not reflected in sorption behavior. However, degradation was more rapid in the CT surface soil than in the corresponding NT soil and more rapid in surface than subsurface soil. In all cases, degradation proceeded with little mineralization (<3%) over the 22‐d duration of these experiments, however, the amount of unextractable 14C (80:20, CH3OH:0.01 M CaCl2 extractant) increased with time. Analysis of the extractable fraction by HPLC gave no evidence of metabolites. Bentazon degradation was approximated using simple first‐order kinetics, however, the data were best described using two‐compartment models. Development of a bound 14C fraction, despite limited bentazon sorption and no evidence for extractable metabolites, suggested that metabolic intermediates exhibit high sorption affinity.
Methane Oxidation in a Neutral Landfill Cover Soil: Influence of Moisture Content, Temperature, and Nitrogen‐Turnover
Authors: Boeckx Pascal , Van Cleemput Oswald
Published: July 2010

Well‐managed, aerated cover soils can have a mitigating effect on methane emission from landfills. The influence of moisture content, soil temperature, and N on the methane uptake capacity of a neutral landfill cover soil was examined. A soil moisture content of 15% w/w gave the maximum CH4 oxidation rate (2.36 ng CH4 h−1 g−1 soil). When wetter, CH4 consumption was slower (e.g., 1.6 ng CH4 h−1 g−1 at 30% w/w) because of a limited gas diffusion. At lower soil moisture, microbial activity was reduced and consequently the oxidation capacity decreased (e.g., 0.84 ng CH4 h−1 g−1 at 5% w/w). Optimum temperature was between 25 and 30°C. The calculated activation energy of the CH4 oxidation was 56.5 kJ K−1 mol−1. After NH+4 addition, a negative linear correlation was found between the methane oxidation rate and the nitrous oxide flux (R2 = 0.96, Y1 = 2.7 − 0.44 × Y2). Addition of NO−3 had no significant effect on CH4 oxidation. The effect of organic residue amendments depended on their C/N ratios. Crop residues with a high C/N ratio (wheat [Triticum sativum L.] and maize [Zea mays L.] straw) stimulated N‐immobilization and did not affect the methane‐oxidizing capacity. On the other hand, addition of crop residues with low C/N ratios (potato [Solanum tuberosum L.] and sugar beet [Beta vulgaris cv. Altissima] leaves) stimulated N‐mineralization, resulting in a strong inhibition of the methane oxidation.
Dissipation of Polycyclic Aromatic Hydrocarbons in the Rhizosphere
Authors: Reilley K. A. , Banks M. K. , Schwab A. P.
Published: July 2010

Residual contamination of soils with polycyclic aromatic hydrocarbons (PAHs) is an environmental problem for many industrial operations, including the petroleum industry. Petroleum sludges high in PAHs are often treated through landfarming in which soil is mixed with sludge, kept bare of vegetation, tilled, and fertilized to encourage microbial degradation of the contaminants. However, recent research has demonstrated that plants can enhance the dissipation of organic pollutants in the immediate environment of the root (rhizosphere). The use of vegetation to increase the degradation of two common PAH contaminants, anthracene and pyrene, was investigated in a greenhouse experiment. Target compounds were added to a contaminated, landfarmed soil and a similar uncontaminated soil at a rate of 100 mg/kg. Four plant species were grown in each soil; after 4, 8, 16, and 24 wk of plant growth, soil and plant material were sampled and analyzed for the target PAHs. Vegetated soils had significantly lower concentrations of the PAHs than the unvegetated soils, ranging from 30 to 44% more degradation in the vegetated soils. Enhanced biological degradation in the rhizosphere appears to be a mechanism of dissipation. Leaching, plant uptake, abiotic degradation, mineralization to CO2, and irreversible sorption were shown to be insignificant in the overall mass balance of the target compounds. The presence of plants may enhance the clean‐up of PAH‐contaminated soils during in situ remediation.

Joint contribution from the Engineering Exp. Stn. and Kansas Agric. Exp. Stn.
Characterization of Pesticide Sorption and Degradation in Macropore Linings and Soil Horizons of Thatuna Silt Loam
Authors: Mallawatantri A. P. , McConkey B. G. , Mulla D. J.
Published: July 2010

The effect of changes in soil characteristics with depth because of soil horizonation and macroporosity on fate of pesticides is poorly understood. Soil from the surface A horizons (0–0.65 m), albic E horizons (1.05–1.35 m), argillic Bt horizons (1.4–3.5 m), and surface linings of macropores in the argillic horizons (Bt‐M, 1.4–3.5 m) of a Thatuna silt loam (fine‐silty, mixed, mesic Xeric Argialbolls) were characterized for their physical, chemical, and microbiological effects on adsorption, desorption, and mineralization of 2,4‐D, carbofuran, and metribuzin. Organic carbon (OC) contents decreased for soil materials in the order A (1.22%) > Bt‐M (0.36%) > Bt (0.25%) = E (0.20%), and were correlated with the number of soil microbial colony forming units (log CFU) that decreased in the order A (7.4) > Bt‐M (6.1) > E (5.6) = Bt (5.4). Percent macroporosity (pores 2–5 mm diam.) decreased in the order Bt (1.1%) > A (0.7%) > E (0.6%), which is the same order for decreases in saturated hydraulic conductivity (log m s−1), namely; Bt (−6) > A (−6.2) > E (−7.0). Freundlich adsorption partition coefficients (Kf− L kg−1) for A horizon soil with 2,4‐D (1.1), carbofuran (1.0), and metribuzin (1.6) were significantly greater than in subsurface E or Bt matrix material. Sorption Kf values in macropore linings with carbofuran (1.1) and metribuzin (2.0) were comparable to or greater than their respective values of 1.0 and 1.6 in A horizon material. Percent mineralization in the A horizon after 139 d for [U‐14C] 2,4‐D (81.8%) and carbofuran (14.7%) was significantly greater than in all subsurface soil materials. Mineralization in Bt macropore linings for 2,4‐D (17.0%) and carbofuran (8.4%) was significantly greater than in other subsurface soil materials. Mineralization of [U‐14C] metribuzin was negligible (<3%) in all soil materials after 139 d.
Accumulation of Airborne Elements from Vehicles in Transplanted Lichens in Urban Sites
Authors: Garty J. , Kauppi M. , Kauppi A.
Published: July 2010

The objective of the current study is to compare the short‐term accumulation capacity of two epiphytic lichens characterized by a different type of thallus. The lichens Hypogymnia physodes (L.) Nyl. and Usnea hirta (L.) Weber em. Mot. were transplanted either to the vicinity of streets of low volume and slow traffic or to the vicinity of a highway in the city of Oulu, N. Finland, for a period of 45 d. Eleven elements were analyzed before and after transplantation. The two lichen species were found to possess a similar accumulating capacity for K and Mn. Hypogynmia physodes manifests a higher accumumulating capacity than U. hirta for Na, Fe, and Cu, whereas the more sensitive lichen U. hirta exhibits a higher accumulating capacity for Mg, despite a higher primary concentration of these elements in the thallus of H. physodes. Our findings show a relative high concentration of K, Fe, Mg, Zn, Mn, Pb, and Cu in thalli of H. physodes and Mg, Zn, Pb, Cu, and Cd in U. hirta in material transplanted to streets of low volume and slow traffic, over and above the concentration found in thalli retrieved from the vicinity of the highway. This may be explained by the higher rate of abrasion of car engines running idle near traffic lights and by the lesser ventilation near the close‐clustered streets of the inner city.
Mineralization of Hydrocarbons in Soils under Decreasing Oxygen Availability
Authors: Freijer Jan I.
Published: July 2010

Techniques for remediation of soils contaminated with hydrocarbons (HCs) can be improved when the factors that control the decomposition rate are identified. In this study, the effect of O2 availability on the decomposition rate of hydrocarbons in soils is examined. A kinetic second‐order model with the O2 concentration and biomass concentration as rate‐controlling variables is used to quantify HC decomposition, O2 consumption, and CO2 production. Concentrations of O2 and CO2 are calculated analytically as a function of time in a three‐phase closed system. These calculations are compared with measurements of repetitive O2‐depletion experiments in closed jars containing a layer of soil contaminated with HCs. About 80% of the HC decrease could be attributed to mineralization, while the other 20% was assumed to be converted into biomass and metabolites. After calibration, model calculations agree with the experimental results, which makes the concept of O2 concentration and biomass concentration as rate‐controlling variables plausible. The parameter values that are obtained by calibration have a clear biochemical significance. It is concluded that attention has to be paid to the O2 supply in closed‐jar experiments to avoid erroneous interpretation of the results.
Historical Changes in Connecticut Lakes Over a 55‐Year Period
Authors: Siver Peter A. , Canavan Richard W. , Field Cathryn K. , Marsicano Laurence J. , Lott Anne‐Marie
Published: July 2010

Changes in the chemical and physical conditions of 42 Connecticut lakes are compared between three time periods, the late 1930s, the mid‐ to late 1970s and the early 1990s. On average, lakes have decreased in Secchi disk depth by 1.2 m and doubled in total phosphorus concentration, many in a unidirectional manner. As a result, the suite of lakes can be characterized as having shifted from an oligo‐mesotrophic condition (1930s) to a late mesotrophic condition (1990s). Since the 1970s, lakes have increased in base cation concentrations an average of 70 μeq/L, many as the result of an increase in sodium. Increases in sodium were generally coupled with increases in chloride ions. Many of the lakes positioned in watersheds that have become more residential since the 1930s and/or 1970s have also increased in alkalinity. Despite the overall increase in base cations, chloride, and alkalinity, about 25% of the waterbodies that have remained situated in primarily forested watersheds in crystalline rock regions have decreased in total cation concentrations; about half of these lakes have also significantly decreased in alkalinity since the 1930s. The changes are discussed in relation to the degree of urbanization of the watersheds over the same time period.
Statewide GIS/Census Data Assessment of Nitrogen Loadings from Septic Systems in Pennsylvania
Authors: Nizeyimana Egide , Petersen G. W. , Anderson M. C. , Evans B. M. , Hamlett J. M. , Baumer G. M.
Published: July 2010

Despite the role of septic systems in surface and groundwater N contamination, little statewide information has been collected or is available on the amount of N pollution from septic systems. This study reports on the development of a methodology to assess N released from septic systems at the state level and presents results of N loading estimates in Pennsylvania watersheds. The methodology describes steps to compute N loadings per watershed unit area within a Geographic Information System (GIS) framework based on (i) information on septic systems and population from the 1990 Census data, (ii) soil limitations to proper purification of septic system effluent acquired from the State Soil Geographic (STATSGO) data base, and (iii) daily N estimates per capita in septic system effluent from the literature. In this study, watersheds were ranked from 1 to 104 and grouped into three significantly different classes (high, medium, and low) according to their N loadings. The N loading ranges corresponding to these classes were 1.16 to 0.71 kg ha−1 yr−1, 0.66 to 0.41 kg ha−1 yr−1, and 0.38 to 0.03 kg ha−1 yr−1, respectively. High‐producing watersheds were generally located in suburbs adjacent to larger metropolitan areas. The watershed ranking, groups, and N loading results provided by this methodology can be combined with similar information from agriculture, atmospheric deposition, etc. in the attempt to account for all sources of nonpoint N pollution in a state or region.
Chemical Composition of Municipal Leaf Waste and Hand‐Collected Urban Leaf Litter
Authors: Heckman J. R. , Kluchinski D.
Published: July 2010

Municipal leaf waste delivered to New Jersey farms was sampled to evaluate its chemical composition and suitability for land application. Freshly fallen leaf litter samples were also collected and analyzed from seven different urban landscape tree species. Municipal leaf waste data from 100 samples in this study was summarized using frequency distributions to characterize its variability in composition. The chemical composition of municipal leaf waste was found to be quite variable. The minimum‐maximum and median values were as follows: (g kg−1) C, 363 to 516, 480; N, 6.6 to 16.2, 9.4; P, 0.2 to 2.9, 1.0; K, 0.9 to 8.8, 3.6; Ca 1.3 to 30.4, 17.3; Mg, 0.2 to 4.6, 2.4; S, 0.1 to 2.1, 1.1; (mg kg−1) B, 7 to 72, 38; Fe, 46 to 9800, 733; Al, 58 to 10554, 602; Mn, 19 to 1845, 406; Zn, 22 to 392, 67; Na, 36 to 325, 90; Cl, 68 to 3995, 1083; Cu, 2.8 to 31.5, 8.1; Co, 0.9 to 10.9, 2.7; Cd, 0.1 to 6.8, 1.3; Pb, 3 to 400, 18; Ni, 1 to 58, 5; Cr, 0.9 to 35.1, 6.6; Ba, 4.2 to 142.0, 49.4. Although municipal leaf waste contains significant amounts of valuable plant nutrients, the high C/N ratio (range: 26.8–71.8; median: 48.5) suggests that heavy applications are likely to cause immobilization of available soil N. Concentrations of Fe, Al, Pb, and Cd were generally higher and more variable in municipal leaf waste than in hand‐collected leaf litter. This suggests that contamination with urban soil during collection contributes to elevated Pb and Cd concentrations in municipal leaf waste. Given careful attention to N‐fertilizer practice, municipal leaf waste is a suitable material for application to farm land.
Resuspension and Diffusive Flux of Nitrogen and Phosphorus in a Hypereutrophic Lake
Authors: Reddy K. R. , Fisher M. M. , Ivanoff D.
Published: July 2010

Bottom sediments in shallow lakes can play a major role in releasing nutrients to the overlying water column during wind induced sediment resuspension or by constant flux due to diffusion. Internal nutrient loads due to these processes may be equal to or higher than external loads. Laboratory and field experiments were conducted on Lake Apopka, a shallow, hypereutrophic subtropical lake located in central Florida. Ammonium (NH+4) and soluble reactive P (SRP) flux during sediment resuspension were measured under laboratory conditions using intact sediment cores. Ammonium N and SRP flux due soley to diffusion were assessed using in situ porewater concentrations. Average diffusive flux from sediment to the overlying water was estimated to be 25 mg NH4‐N m−2 d−1 and 1 mg P m−1 d−2. Resuspension fluxes of NH+4 and SRP were higher than diffusive flux. Soluble reactive P profiles of porewater showed distinct profile differentiation, with the surface 0 to 8 cm sediment depth acting as a P‐depletion zone, and the underlying sediment displaying steep gradients in porewater SRP. These results suggest that dissolved NH+4 and SRP transport from the surface 8 cm of sediment was due to sediment resuspension, while below this depth, upward mobility of NH+4 and SRP was regulated by diffusion. Although dissolved N and P flux is upwards (from sediment to water column), during extended periods (annual cycle) the lake is functioning as a net sink for N and P by transforming inorganic pools of nutrients into organic forms and depositing them on the sediment surface.
Well Water Quality, Well Vulnerability, and Agricultural Contamination in the Midwestern United States
Authors: Richards R. Peter , Baker David B. , Creamer Nancy L. , Kramer Jack W. , Ewing D. Ellen , Merryfield Barbara J. , Wallrabenstein Laura K.
Published: July 2010

The Heidelberg College Cooperative Private Well Testing Program is designed to evaluate water quality in private rural wells. The program inexpensively provides large datasets that reflect relationships between well contamination and associated factors, and support local groundwater protection and education programs. Nearly 35 000 wells have been tested in Ohio, Indiana, Illinois, West Virginia, and Kentucky. Median nitrate concentration was 0.07 mg/L; 3.4% of wells exceeded the drinking water standard of 10 mg/L; 23% exceeded 1 mg/L. Triazines were detected in 4.9% of 12 362 samples; the atrazine MCL of 3.0 µg/L was exceeded in 0.1% of samples. Acetanilides were detected in 9.7% of 10 967 samples; 1.1% exceeded the alachlor MCL of 2.0 µg/L. Many acetanilide detections, and most higher concentrations, are due to an alachlor breakdown product and involve little or no alachlor. Information supplied by well owners was used to examine the impact of cultural and geological factors on well water quality. Concentrations are higher in wells that are shallower, older, dug, or driven; located close to cropland, feedlots, or chemical mixing sites; or located in sandy soils. Where wells combine the most vulnerable alternative for two or three factors, the probability of contamination increases dramatically. Mapping sometimes reveals spatial patterns of contamination that reflect geological influences. River valley aquifers, sandy soils with high water tables, karst areas, and reef structures with surficial expressions are all reflected in county maps of the data.
GIS‐Based Solute Transport Modeling Applications: Scale Effects of Soil and Climate Data Input
Authors: Wilson John P. , Inskeep William P. , Wraith Jon M. , Snyder Robert D.
Published: July 2010

The Weather Generator (WGEN) and Chemical Movement through Layered Soils (CMLS) computer models were modified and combined with two sets of soil and climate inputs to evaluate the impact of input data map resolution on model predictions. The basic soil and climate inputs required by WGEN and CMLS were acquired from either: (i) the USDA‐NRCS State Soil Geographic Database (STATSGO) database; (ii) the USDA‐NRCS (County) Soil Survey Geographic (SSURGO) database; (iii) the Montana Agricultural Potential System (MAPS) database (which divides Montana into approximately 18 000 twenty square kilometer cells and stores more than 200 different land and climate characteristics for each of these cells); and (iv) a series of fine‐scale monthly climate surfaces developed by the authors (0.55 km2 cell size) using thin‐plate splines, published climate station records, and USGS Digital Elevation Models (DEMs). Fifteen years of daily precipitation and evapotranspiration (ET) values were generated and combined with soil and pesticide inputs in CMLS to estimate the depth of picloram (4‐amino‐3,5,6‐trichloro‐2‐pyridinecarboxylic acid) movement at the end of the growing season for every unique combination (polygon) of soil and climate in a 320 km2 area in Teton County, Montana. Results indicate that: (i) the mean depths of picloram movement predicted for the study area with the SSURGO (county) soils and MAPS (coarse‐scale) climate information and the two model runs using the fine‐scale climate data were significantly different from the values predicted with the STATSGO (state) soils and MAPS climate data (based on a new variable containing the differences between the depths of leaching predicted with the different input data by soil/climate map unit and testing whether the mean difference was significantly different from zero at the 0.01 significance level); and (ii) CMLS identified numerous (small) areas where the mean center of the picloram solute front was likely to leach beyond the root zone when the county soils information was used. This last measure may help to identify areas where potential chemical applications are likely to contaminate groundwaters.
Physiological Responses of Two Soybean Cultivars to Cadmium
Authors: Marchiol L. , Leita L. , Martin M. , Peressotti A. , Zerbi G.
Published: July 2010

Anthropogenic activities are increasing cadmium (Cd) concentrations in agricultural soils. Cadmium can be absorbed by plant roots and modify the physiology of the plant. Carbon exchange rate (CER) and leaf conductance to water vapor (gs) were measured on the fifth leaf of two soybean (Glycine max [L.] Merr.) cultivars (Illini insensitive and Richland sensitive) for 6 consecutive days; Cd(NO3)2 was added to the hydroponic solution to achieve a final concentration of 50 µmol. At the end of the experiment, stomata length and width, mesophyll limitation to photosynthesis, root hydraulic conductance, relative water content (RWC), and Cd concentration in leaves, stems, and roots were measured on treated and control plants. Cadmium progressively reduced CER and gs to about 50% after 6 d of treatment. This was more evident in Richland than in Illini and was not linked with leaf RWC and mesophyll limitation to photosynthesis. After 6 d, the apparent root hydraulic water conductivity was 67% lower in the Cd‐treated plants than in controls. The primary mechanism affected by Cd‐induced stress in soybean is root water uptake, and this reduction is consistent with the decrease in stomatal opening and conductance, and therefore, in photosynthesis.
An Enclosure Technique for Measuring Nonmethane Organic Compound Emissions from Grasslands
Authors: Fukui Yoshiko , Doskey Paul V.
Published: July 2010

A static chamber technique for measuring emissions of nonmethane organic compounds (NMOCs) from soil surfaces and herbaceous vegetation in a natural setting has been developed. The technique involves the insertion of a polymethyl methacrylate frame into the ground. A polycarbonate chamber is placed in a water‐containing trough on the frame to seal the chamber to the surface. The soil surface and vegetation are covered for various lengths of time, and samples of the chamber air are passively collected in preevacuated stainless steel canisters. The samples are analyzed in the laboratory by a whole‐air cryogenic‐preconcentration/high‐resolution gas chromatographic technique with flame ionization detection. Changes in the concentrations of the NMOCs with time in the chamber are used to derive emission rates. The technique is sensitive and precise, but the occasional observation of nonlinear changes in NMOC concentrations in the chamber with the length of the covering period limits the accuracy of emission rates derived by this technique. Despite this limitation, the method is effective for identifying NMOC emissions and investigating seasonal variations of emission rates.
Effect of Elevated Atmospheric Carbon Dioxide and Open‐top Chambers on Transpiration in a Tallgrass Prairie
Authors: Bremer Dale J. , Ham Jay M. , Owensby Clenton E.
Published: July 2010

Increasing concentrations of atmospheric carbon dioxide (CO2) may influence plant‐water relations in natural and agricultural ecosystems. A tallgrass prairie near Manhattan, KS, was exposed to elevated atmospheric CO2 using open‐top chambers (OTCs). Heat balance sap flow gauges were used to measure transpiration in ironweed [Vernonia baldwini var. interior (Small) Schub.], a C3 forb, and on individual grass culms of big bluestem (Andropogon gerardii Vitman) and indiangrass [Sorghastrum nutans (L.) Nash], both C4 grasses, in each of three treatments: (i) CE (chamber enriched, 2× ambient CO2); (ii) CA (chamber ambient, no CO2 enrichment); and (iii) NC (no chamber, no CO2 enrichment). Sap flow data were coupled with measurements of stomatal conductance, plant/canopy resistance, and whole‐chamber evapotranspiration (ET) to determine the effect of elevated CO2 on water use at different scales. Because of frequent rainfall during the study, all data were collected under well‐watered conditions. Comparisons of CE and CA showed that sap flow was reduced by 33% in ironweed, 18% in big bluestem, and 22% in indiangrass under CO2 enrichment. Whole‐chamber ET was reduced by 23 to 27% under CO2 enrichment. Comparisons of CA and NC showed that the environmental effect of the OTCs caused a 21 to 24% reduction in transpiration. Stomatal conductance decreased from 7.9 to 3.6 mm s−1 in big bluestem and from 5.3 to 3.2 mm s−1 in indiangrass under CO2 enrichment. Soil water was consistently highest under elevated CO2, reflecting the large reductions in transpiration. During sap flow measurements, whole‐plant stomatal resistance to water vapor flux in big bluestem increased from 103 to 194 s m−1 under elevated CO2.
Acidification of Agricultural Evaporation Ponds: Effects on Trace Element Chemistry in Sediment‐Water Core Microcosms
Authors: Herbel Mitchell J. , Tanji Kenneth K. , Dahlgren Randy A. , Gao Suduan
Published: July 2010

Accumulation of potentially toxic trace elements in agricultural evaporation ponds in California's San Joaquin Valley poses a hazard to wildlife. Some evaporation pond cells have evapoconcentrated Se resulting in reduced reproduction and deformity of waterbirds. One option to reduce toxicity hazards to waterbirds is to break the aquatic food chain by acidification of pond waters. Effects of pond water acidification on trace element chemistry and chlorophyll‐a concentrations in sediment‐pond water cores from three representative pond facilities were studied using pH stat experiments. Three acid treatments were investigated during the 4‐mo experiment: HS4, HS5, and FS4, the latter oxidizing ferrous iron (FeII) to ferric iron (FeIII) which released protons. Changes in trace element speciation due to acidification were examined using a revised version of SOLMINEQ.88. FS4 treatments were the most effective in terms of requiring the smallest number of additions to maintain the pH and reducing aqueous concentrations of many trace elements. Arsenic, Mo, and Se concentrations significantly decreased in the water column for FS4 treatments. Iron and Mn concentrations increased for all treatments, and Al, B, Cu, and Zn concentrations either were relatively static or were too low in concentration to discern any effect. Chlorophyll‐a concentrations (an index of pond water productivity) showed decreases for all treatments in Pond 1, but were variable in Ponds 2 and 3. An economic analysis indicated a high cost for the initial acidification, which may inhibit implementation of acidification as a method to reduce contaminant hazards to wildlife.
Extractable Potassium and Soluble Calcium, Magnesium, Sodium, and Potassium in Two Whey‐Treated Calcareous Soils
Authors: Robbins C. W. , Hansen C. L. , Roginske M. F. , Sorensen D. L.
Published: July 2010

Cheese whey contains 1.0 to 1.4 g K kg−1 and 5.0 to 10.0 g total salts kg−1 (electrical conductivity [EC] of 7 to 15 dS m−1) and has a pH of 3.3 to 4.6. Much of the 38 × 109 L of whey produced in the USA each year is applied to soils. Whey application effect on the K and salinity status of irrigated calcareous soils has not been documented. Objectives of this study were to measure soil pH, sodium adsorption ratio (SAR), saturation paste extract (ECe), and extractable Ca, Mg, Na, and K changes due to whey application to irrigated calcareous soils at different whey rates and different times of the year. Whey was applied to two calcareous Portneuf silt loam (coarse‐silty, mixed, mesic, Durixerollic Calciorthids) soils and a calcareous Nibley silty clay loam (fine, mixes, mesic Aquic Argiustolls) soil at rates up to 2200 m3 ha−1. These treatments added up to 1050 kg Ca, 200 kg Mg, 790 kg Na, and 2200 kg K ha−1 during winter‐time, growing season, or year‐round whey application. Soil bicarbonate‐extractable K increased to more than 500 mg K kg−1 in the surface 0.3 m at the highest whey rates and may induce grass tetany in livestock grazed on high whey‐treated pastures. Soil K did not increase below 0.6 m in any treatment. Soil pH and SAR were not affected sufficiently to be of concern under these conditions. The ECe increased to nearly 2.0 dS m−1 in the surface 0.3 m under the highest whey rates and would likely affect salt‐sensitive crop yields. After a 1‐yr whey application rest period under irrigated alfalfa (Medicago sativa L.), the ECe levels returned to background levels.
Plant Species for Revegetation of a Saline Flue Gas Desulfurization Sludge Pond
Authors: Salo L. F. , Artiola J. F. , Goodrich‐Mahoney J. W.
Published: July 2010

Codisposing saline wastewater from electrical generating stations with flue gas desulfurization (FGD) scrubber sludge simplifies waste disposal but produces a saline waste that will later require revegetation. This waste is low in macronutrients, contains high levels of salts and B, and has a fine texture. This study identified plants, based on germination test results, that show promise for sowing at an evaporation pond in eastern Arizona where scrubber sludge and wastewater are codisposed. Forty‐four grass, forb, and shrub accessions germinated on filter paper in saline water from the disposal pond. Dilutions of disposal pond water with untreated well water from the site ranged in EC from 0.17 to 3.03 S m−1. Our criteria for evaluating plants to be used in revegetating saline FGD sludge were: (i) ability to germinate in increasing levels of disposal pond water and (ii) ease of establishment from seed. The percentage of pond water that would reduce germination to 50% that of well‐water controls (P50) ranged as high as >100 for the most tolerant plants. Accessions that show promise for sowing at these types of saline waste disposal sites include: Elytrigia pontica ‘Jose’ and ‘Largo’, Atriplex gardneri, Puccinellia airoides, P. distans ‘Fults’, Festuca arundinacea ‘Alta’ and ‘Fawn’, Krascheninnikovia lanata, Kochia prostrata ‘Immigrant’, Panicum virgatum ‘Nebraska 28’, Sporobolus airoides ‘Saltalk’, Leymus angustus ‘Praireland’ and Elymus trachycaulus ‘Pryor’.
Effect of Soil Properties and Surfactant on Primisulfuron Sorption
Authors: Werkheiser Wendy O. , Anderson Sharon J.
Published: July 2010

Soil properties affect the environmental fate of herbicides. Little is known about how soil organic matter and pH affect sorption and fate of the sulfonylurea primisulfuron (2‐[3‐(4,6‐bis(difluoromethoxy)‐pyrimidin‐2‐yl]‐benzoic acid methyl ester). Primisulfuron sorption and desorption by six soils with different organic carbon (OC), iron oxide, and clay contents were investigated using batch reaction at controlled pH. Sorption was measured at a soil/solution ratio of 1:2 with 0.01 M CaCl2 as a background electrolyte. Sorption and desorption isotherms were linear. When pH was adjusted to values between 4 and 6.5, sorption coefficients decreased with increasing pH. At pH 4.5, sorption coefficients increased with increasing OC and ranged from 0.6 for a soil with 0.2% OC to 15.5 for a soil with 48% OC. Surfactant (Triton X‐77, 0.25%, v v−1) caused primisulfuron sorption to increase in a low OC soil but caused decreased sorption in a soil with 1.7% OC. Sorption coefficients were correlated with dithionite‐extractable iron in soils with <1% OC, but not in soils with greater OC. Desorption coefficients at native soil pH were up to five times greater than were sorption coefficients; about 50% of sorbed primisulfuron did not desorb during a single 24‐h batch desorption reaction. Primisulfuron is most likely to leach in soils with high pH or low organic matter contents.
DDT Persistence and Volatility as Affected by Management Practices after 23 Years
Authors: Spencer W. F. , Singh G. , Taylor C. D. , LeMert R. A. , Cliath M. M. , Farmer W. J.
Published: July 2010

In 1971, an experiment was conducted in a field containing high amounts of residual DDT (dichlorodiphenyltrichloroethane) to evaluate deep plowing, followed by flooding, with and without organic matter applications, as soil and water management tools to reduce total DDT residues and preferentially degrade the residual DDT to DDD [1,1‐dichloro‐2,2‐bis (p‐chlorophenyl) ethane]. The experimental site was revisited in 1994 to determine residual soil concentrations of DDT isomers and their metabolites in soil, soil dust, and the atmosphere. Also, volatilization flux measurements were made to evaluate rates of movement into the atmosphere. Soil concentrations of all DDT isomers and metabolites had decreased in all plots, with p,p′‐DDE[1,1‐dichloro‐2,2‐bis (p‐chlorophenyl) ethylene] the major component of the total remaining residues (DDTR). The total DDTR residues in the surface 75 cm varied from 10 to 28% of their amounts in 1971. The highest concentrations were found in the deep plowed, unflooded plots with DDTR decreasing from 4 mg kg−1 at 0 to15 cm to 0.3 mg kg−1 at 60 to 75 cm. Deep plowing evidently increased DDT persistence by placing it deeper into the soil profile, which protected it from degradation and volatilization. Concentrations of all isomers were lower in the previously flooded plots. Degrading DDT under reducing conditions brought about by flooding lessened or prevented the formation of DDE in the soil thus ultimately reducing its redistribution into the environment. Significant concentrations of both o,p′ and p,p′‐DDE and DDT were detected in the atmosphere above the plots. Measurable volatilization fluxes were observed over 48‐h periods in February and September. Irrigating the soil with 20 mm water dramatically increased the volatilization flux of all the DDT isomers and metabolites, particularly p,p′‐DDE. The finding that DDT isomers continue to volatilize from the soil surface has implications for long‐range transport of DDT and contaminating forage or foodstuff. The possible health implications from exposure to humans or animals through the air route is unknown.
Modification of Snowmelt Chemistry by Forest Floor and Mineral Soil, Northern Michigan
Authors: Stottlemyer Robert , Toczydlowski David
Published: July 2010

Precipitation, snowpack, snowmelt, forest floor percolate, soil water, and streamwater chemistry were studied throughout winter for 7 yr in a small (176 ha) Northern Michigan watershed vegetated by northern hardwoods. The objective was to see how precipitation and snowmelt chemistry is modified before it reaches the stream. Intermittent snowmelt occurred throughout winter, and 65 to 78% of total snowpack loss of H+, NH+4, NO−3, and SO2−4 occurred before peak snowpack and snowmelt. From 70 to 95% of snowmelt H+, NH6+4, and NO−3 was retained in the forest floor and shallow mineral soil by exchange, adsorption, or biological uptake. Snowmelt SO2−4 concentration was enriched in forest floor percolate and shallow soil water probably by organic mineralization, low adsorption, and perhaps desorption. The significant relationship between dissolved organic carbon (DOC) and SO2−4 concentration in forest floor percolate and shallow soil water indicates organics may contribute to reduced SO2−4 adsorption. Sulfate and organic anions were major contributors to base cation (CB) flux in the forest floor while SO2−4 was related to CB flux in shallow soils. A decline in mineral soil and streamwater DOC concentration and increase in streamwater HCO−3 relative to concentrations in forest floor percolate suggests the relative importance of organic decomposition decreased and soil mineral weathering increased with soil depth. High streamwater Ca2+, Mg2+, and HCO−3 concentrations indicated that soil mineral weathering was a major process altering snowmelt chemistry at the watershed level.
Adsorption of Mercury(II) by Soil: Effects of pH, Chloride, and Organic Matter
Authors: Yin Yujun , Allen Herbert E. , Li Yimin , Huang C. P. , Sanders Paul F.
Published: July 2010

Effects of pH, Cl−, and organic matter on Hg(II) adsorption from 10−7 M solution by 15 New Jersey soils were examined to understand the factors responsible for Hg partitioning to soils under different environmental conditions. Maximum adsorption ranged from 86 to 98% of added Hg and occurred at pH 3 to 5. Further increasing the pH significantly decreased adsorption of the added Hg, for example, from 89 ± 8% at pH 4.0 to 39 ± 11% at pH 8.5. An important factor was the complexation of Hg by dissolved organic matter whose concentration increased with increasing pH. When organic matter was removed from the soil samples, adsorption decreased under acidic conditions, but increased under alkaline conditions. The effect of Cl− on Hg(II) adsorption by soil depended on both pH and the soil organic matter content. At circumneutral and higher pH, addition of Cl− did not affect adsorption by any soil. The standard deviation of Hg adsorption for all soils was <4% for Cl− concentrations from about 1 × 10−6 to 1 × 10−2 M. At about pH 3, the effect of Cl− on Hg(II) adsorption by soil depended on the soil organic matter content. When the Cl− concentration increased from about 1 × 10−6 to 1 × 10−2 M, adsorption by the lowest organic matter soil (1.2 g C kg−1) decreased from 93 to 40%, whereas the measured adsorption by the largest organic matter soil (49.9 g C kg−1) decreased only from 95 to 91%.
Trace Element Concentrations of Selected Soils and Fertilizers in Saskatchewan, Canada
Authors: Mermut A. R. , Jain J. C. , Song Li , Kerrich R. , Kozak L. , Jana S.
Published: July 2010

Limited information is available on the trace element contents of soils and crops in Saskatchewan. Trace elements, to a large extent, are derived from soil parent materials and partially from anthropogenic activities, such as agricultural application of fertilizers. The objective of this study was to establish levels of trace element concentrations of the surface horizons and parent materials of selected soils, fertilizers, and durum wheat (Triticum durum Desf.). Inductively coupled plasma mass spectrometry (ICP‐MS) having the capacity to determine 60 elements simultaneously at very low detection levels was used. Trace elements for this work are among the most frequently reported in the recent literature. We found a positive relationship between the total contents of trace elements and percent of clays in the soils, except Se. This suggests that the major part of the elements studied are associated with the clay minerals in soils. In two Regina heavy clay soils, total Cu, Zn, Se, and Pb were higher in the surface soil than the subsoil, but this increase was statistically not significant. All the elements, except Zn, Cd, and Pb, were depleted in soils that have lower clay content in the surface horizon than the parent material. Soils having similar clay contents in the surface horizon and subsoil, total V, Cr, Co, Ni, Zn, Cd, Sn, Sb, Tl, and Pb concentrations were higher in the surface horizon, relative to parent material. Only Zn and Cd increases were significant. Enrichment of elements in the surface horizons was, in part, attributed to anthropogenic additions. Experiments with EDTA and DTPA extraction techniques showed that almost half of Co, As and Cd, and other elements in fertilizers were between 4 and 50% in somewhat available form for plants indicating their potential for soil pollution.
Effect of Calcium and Dibasic Acids on Selected Strains of Neutrophilic Sulfur‐Oxidizing Bacteria
Authors: Miller Kathleen W.
Published: July 2010

During inhibited flue gas desulfurization (FGD), thiosulfate is added to the limestone sorbent slurry in order to inhibit oxidation of CaSO3, the product of SO2 capture. Since bio‐oxidation of reduced sulfur produces H2SO4, stabilization of dissolved sulfur prior to environmental release is desirable. Three neutrophilic autotrophic strains of sulfur‐oxidizing bacteria, Thiobacillus neapolitanus ATCC 23641, ATCC 23639, and the strain TQ were tested for the ability to oxidize thiosulfate in the supernatant of a spent slurry from an inhibited FGD process that employs dibasic acids (DBA). Strain TQ, an unidentified isolate from a slurry pond, lowered [S2O2−3] from 540 mg L−1 to <25 mg L−1 within 50 h, while ATCC 23641 and ATCC 23639 were inactive during this time. Experiments using defined media showed for all strains that adipic or glutaric acid at 200 mg L−1 or [Ca2+] up to 10 g L−1 failed to prevent thiosulfate oxidation; however, the combined effect of adipic acid along with ≥ 1.5 g L−1 [Ca2+] or glutaric acid along with ≥10 g L−1 [Ca2+] prevented thiosulfate oxidation by ATCC 23639. Similarly, adipic or glutaric acid along with ≥5 g L−1 [Ca2+] prevented thiosulfate oxidation by ATCC 23641. Magnesium concentrations ≤2.5 g L−1 had little or no ameliorating effect. In contrast, neither dibasic acid along with the highest [Ca2+] tested, 10 g L−1, affected thiosulfate oxidation by strain TQ. Greater resistance to the combined effect of Ca2+ and dibasic acids probably contributes to the ability of strain TQ to oxidize thiosulfate in the slurry supernatant.
Monitoring Fluoride with Honey Bees in the Upper Snake River Plain of Idaho
Authors: Bromenshenk Jerry J. , Cronn Richard C. , Nugent John J.
Published: July 2010

Based on residue concentrations in honey bees (Apis mellifera L.), we mapped the spatial distribution of fluoride across much of the upper Snake River Plain in southeastern Idaho. Our results suggest that facilities at the Idaho National Engineering Laboratory (INEL) intermittently release this chemical. These emissions affect localized areas on the INEL and probably contribute little fluoride to the surrounding region. Phosphate ore processing near Pocatello, ID, is a recurrent fluoride source and influences a wide area, possibly even the INEL. These results are reviewed with respect to anthropogenic and natural sources of fluoride. We also compare bee fluoride concentrations to those reported for lichens, vegetation, and soils in southern Idaho.
Respirable‐Dust Production from Agricultural Operations in the Sacramento Valley, California
Authors: Clausnitzer H. , Singer M. J.
Published: July 2010

Air quality in California's intensively farmed Central Valley violates regulatory particulate matter limits nearly year‐round. Little is known about the amount of fugitive dust produced by individual agronomic operations. This study measured the respirable fraction, covering particles ≤4 µm in aerodynamic diameter and the influences of climate, soil, and implement conditions on dust production. Respirable dust was collected at the implement from 18 cultural operations for a complete annual crop cycle on 22, 4097‐m2 plots, 11 km west of Davis, CA. Plots included conventional and organic corn (Zea mays L.) and tomato [Lycopersicon lycopersicum (L.) Karsten] fields as well as fields with a winter cover crop or fallow plots followed by wheat (Triticum aestivum L.). The 266 samples were collected with standard cyclone samplers mounted directly on each implement as the dust source (average height of 94 cm above ground). Sampling near the dust source measured the relative respirable‐particulate‐matter production from each operation. The highest average respirable‐dust concentration was 10.3 mg/m3 air from soil ripping and land planing, carried out on dry surface soil. The lowest dust concentration was from disking of corn stubble (0.3 mg/m3) into soil during the wet season. Approximately 64% of all operations were performed during hot and dry weather, producing 83% of the annual respirable dust for this three‐crop system. Among the measured environmental and implement conditions, air temperature, soil moisture, wind speed, and tractor speed were significantly correlated with the dust concentration in an exponential model.
Prediction of Methyl Bromide Flux from Area Sources Using the ISCST Model
Authors: Ross L. J. , Johnson B. , Kim K. D. , Hsu J.
Published: July 2010

Growing concern about atmospheric exposure of humans to pesticides has led to increased air monitoring in California. Air monitoring data typically consist of measurements made downwind from point or area sources. The utility of monitoring at fixed stations is limited for establishing buffer zones to protect neighboring populations from pesticide exposure. A modeling approach designed to use these data would provide the flexibility needed to establish buffer zones. The Industrial Source Complex Short Term (ISCST) model is a gaussian plume dispersion model that predicts air concentrations around point or area sources using emission rates (flux) and meteorological conditions as model inputs. The flux data, however, are typically not collected in the field nor available in the literature. In order to use the field data currently available, we developed a procedure using methyl bromide (MeBr) concentrations around two area sources and the ISCST model, to back‐calculate flux. In addition, MeBr flux was measured concurrently by cooperators conducting an independent study. Air concentrations, together with actual meteorological data, were used as inputs to the ISCST model. Flux of MeBr was then back‐calculated using a two step process: (i) an arbitrary flux value of 100 µg m−2 s−1 was used as an initial input value. Resultant air concentrations predicted by the model were then regressed on air concentrations measured offsite and (ii) the resultant regression coefficient was then used to adjust the arbitrary flux to a back‐calculated flux. Using another regression analysis, back‐calculated and measured flux rates were found to be significantly correlated, indicating this approach may be suitable for indirect estimation of flux. Implications for the use of this method in establishing buffer zones designed to protect human health are discussed.