bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Cadmium Flux in Sweden with Special Emphasis on Landfill Leachate
Authors: Flyhammar Peter 
Published: July 2010

AbstractCadmium (Cd) fluxes and sinks in Sweden have been analyzed. Emphasis was focused on landfills since they contain large amounts of Cd and constitute one of the biggest potential environmental future risks. Today, the Cd content of Sweden is reduced because of large export of Cd in zinc (Zn) concentrate (approximately 800 Mg Cd yr−1). Another large anthropogenic flow is the import of various secondary and consumer goods (approximately 100 Mg Cd yr−1). Today, the atmospheric deposition (16 Mg Cd yr−1) is nearly the same as diffuse consumption emissions (14 Mg Cd yr−1). Other anthropogenic discharges, such as industrial emissions to air and water, leachate from landfills, waste and storm water, have been reduced approximately one order of magnitude, since the late 1960s and early 1970s. The use of Cd and Cd‐contaminated primary goods (ores, metal concentrate, scrap etc.) have resulted in two large sinks within the Swedish society, one short‐term sink (Cd in serviceable products) and one long‐term sink (Cd accumulated in landfills). Since Cd outflows from existing landfills are much smaller than the inflows, the stored Cd is increased rapidly. Presently, these emissions are small on a regional scale, but the effects may be severe on the immediate surroundings.
Effects of Ozone and Water Deficit on Field‐Grown Soybean: II. Leaflet Nonstructural Carbohydrates
Authors: Miller Joseph E. , Vozzo Steven F. , Patterson Robert P. , Pursley Walter A. , Heagle Allen S. 
Published: July 2010

AbstractOzone (O3) and water deficit can suppress photosynthesis, growth, and yield of crops, and both may alter plant carbohydrate status. Little is known, however, concerning the combined effects of these stresses on C assimilation and nonstructural carbohydrate reserves in field‐grown plants. Soybean [Glycine max (L.) Merr. ‘Young’] plants were subjected to two soil moisture regimes (providing well‐watered and periodically water‐deficient conditions) and three levels of O3 in open‐top field chambers throughout the growing season. The O3 concentrations were 0.018, 0.059, and 0.085 µL L−1 (seasonal mean 12 h d−1 concentration). Leaflet carbohydrate concentrations were measured periodically during the growing season. Total soluble carbohydrates (TSCs) (sucrose and hexose) and starch were measured in the center leaflet of the sixth trifoliolate from the apex. Ozone stress suppressed leaflet concentrations of TSCs and starch on most sampling dates. Impacts of water deficit were less consistent, but starch concentrations usually increased when effects were significant. Interactions between the two stresses occurred infrequently, although water stress reduced the negative effects of O3 on sucrose and TSCs when the data were analyzed over the season. Ozone treatment also slightly increased the proportion of sucrose compared to starch in the total nonstructural carbohydrate (TNC) pool. The response of seasonal mean TNC concentrations, seasonal mean NCER, and seed yield to O3 followed similar patterns, although TNCs were suppressed more on a relative basis than NCER or yield.
Free‐Air Carbon Dioxide Enrichment of Cotton: Root Morphological Characteristics
Authors: Prior S. A. , Rogers H. H. , Runion G. B. , Kimball B. A. , Mauney J. R. , Lewin K. F. , Nagy J. , Hendrey G. R. 
Published: July 2010

AbstractThe response of plants to rising global CO2 concentration is of critical research interest but one neglected aspect is its effect on roots. Root morphological changes in cotton [Gossypium hirsutum (L.) ‘Delta Pine 77’] were examined in a 2‐yr field study. The test crop was grown under two water regimes (wet, 100% of evapotranspiration [ET] replaced and dry, 75% [1990] and 67% [1991] of ET replaced) and two atmospheric CO2 concentrations (ambient = 370 µmol mol−1 and free‐air CO2 enrichment [FACE] = 550 µmol mol−1). A FACE technique that allows for CO2 exposure under field conditions with minimal alteration of plant microclimate was used. Excavated root systems were partitioned into taproot and lateral roots at two growth phases (vegetative and reproductive). Vertical root‐pulling resistance was determined at the second sampling; this measure was higher because of CO2 enrichment but was unaffected by water stress. Water stress affected root variables only at the second sampling; water stress reduced taproot variables more than lateral variables. The larger diameter taproots seen at all sample dates under FACE exhibited large increases in dry weight and volume. FACE often increased lateral root number and lateral dry weights were higher at all sample dates. The development of more robust taproot systems in CO2‐enriched environments may allow for greater carbohydrate storage for utilization during periods such as boll filling and to ensure root growth for continued exploration of the soil profile to meet nutrient and water demands during peak demand periods.
Late Fall Site‐Specific Soil Nitrate Upper Limits for Groundwater Protection Purposes
Authors: Van Der Ploeg R. R. , Ringe H. , Machulla Galina 
Published: July 2010

AbstractFor temperate regions, such as Germany, a simple management model is developed, with which NO3 seepage losses during winter can be estimated, when the amount and distribution of soil NO3 in late fall are known. The semi‐analytical, one‐dimensional model is developed for homogeneous soils. The model is derived for steady‐state flow conditions at a constant soil water content (field capacity). Essential part of the model is a solute transport equation based on mixing‐cell theory. Sample calculations show that when the height Δz of the mixing‐cells is chosen such that Δz = 2D/v, where D is the soil dispersion coefficient and v is the pore water flow velocity, mixing‐cell model results compare well with results from convective‐dispersive models. The advantage of mixing‐cell models compared with convective‐dispersive models is that mixing‐cell model solutions frequently appear as simple mathematical expressions. With the model sample calculations concerning NO3 seepage losses during winter were carried out for a variety of site conditions. The calculations show that NO3 seepage losses vary considerably, even when the initial amount and the distribution of the soil NO3‐N are the same. The calculations also show that if a limit is set for the total amount of tolerable NO3 seepage losses during winter, site‐specific late fall upper limits for soil NO3‐N can be derived. A table of such values, for a wide range of site‐conditions, is presented.
Soil and Phosphorus Loss from Conservation and Conventional Tillage in Corn Production
Authors: Gaynor J. D. , Findlay W. I. 
Published: July 2010

AbstractConservation tillage is encouraged in southwestern Ontario by concern for soil erosion and compaction. The contribution of agriculture to eutrophication of the Great Lakes by P is also at issue. Soil loss and ortho‐P transport were measured from a conventional and two conservation tillage treatments (zero and ridge tillage) from January 1988 to 30 Sept. 1990 to evaluate their impact on meeting Great Lakes water quality objectives for P. Sediment concentration from the poorly drained, Brookston clay loam (clayey, mixed, mesic Typic Haplaquolls), cropped to corn (Zea mays L.) was 2.1 times larger in surface runoff than tile discharge (0.20 g L−1) but tile discharge contributed 44 to 65% of the soil loss probably from preferential flow. Conservation tillage reduced average soil loss 49% from conventional tillage (899 kg ha−1). Conservation tillage increased ortho‐P concentrations in runoff 2.2 times from conventional tillage (0.25 mg L−1). Orthophosphate transport decreased in the order zero>ridge>conventional tillage. Average ortho‐P loss was 1.7 to 2.7 times greater from conservation than conventional tillage (559 g ha−1 yr−1). Subsurface drainage accounted for 55 to 68% of the ortho‐P transported. Transport of total soluble P and total P (sum of sediment‐attached P and soluble P, only measured in 1990) increased 2.2 and 2.0 times, respectively, with conservation than conventional tillage. Dissolved P accounted for 84 to 93% of the P transported from the three tillage treatments. Sediment‐attached P constituted 7 to 16% of total P loss. Conservation tillage effectively reduced soil erosion but increased P loss.
Device for Sampling Unconsolidated Soft‐Bottom Sediments in Moderately Deep Waters
Authors: Doyle E. F. , van Dokkum H. P. , Vermulst C. J. W. , Anderson D. L. , Mossa J. 
Published: July 2010

AbstractSampling unconsolidated soft‐bottom sediments in shallow to moderately deep canals is difficult. A sediment core sampler was constructed from commercially available parts, utilizing a readily removable plastic liner. The removable prefit liner facilitates easy removal, transport, and storage of the core, and reduces the likelihood of core contamination from sample to sample. The device also consists of a transparent polycarbonate tube with a removable stainless‐steel cutting head. Soft‐bottom core samples up to 30‐cm in length were taken in water as deep as 8 m. The device is relatively lightweight and can be used from a small boat.
Sorption of Manganese, Uranium, and Radium by Highly Weathered Soils
Authors: Willett I. R. , Bond W. J. 
Published: July 2010

AbstractLarge concentrations of Mn, 238U, and 226Ra are present in U mine waste waters in comparison with those in surrounding natural waters. Excess mine waste water is being disposed by irrigation of bushland near Ranger Uranium Mine, Northern Territory, Australia. We report the sorption properties of highly weathered and sandy soils (Utric Acruustox, Grossameric Kandiustalf, and Typic Fragiumbrept), near the mine for Mn, U, and 226Ra as determined by batch sorption experiments, and competitive sorption between U and Mn. Manganese sorption was small in comparison with loads expected to be applied to the soils, and Mn was expected to be mobile within the soils. In contrast with Mn, U sorption by the soils was very much greater than the amount that may be applied. Simultaneous additions of U and Mn reduced sorption of both, but the effect of U on Mn sorption was far greater than that of Mn on U. Uranium also caused the displacement of Mn from the soil in the absence of added Mn. The U additions favored the mobility of Mn. Radium−226 at trace levels was strongly sorbed by the soil and <1% of the sorbed 226Ra was displaced during the desorption step. Uranium and 226Ra applied as mine waste water will be retained in surface soil, but Mn was expected to be relatively mobile, particularly in the sandiest soils and when applied in waters that also contain U.
Siderite Weathering in Acidic Solutions under Carbon Dioxide, Air, and Oxygen
Authors: Frisbee N. M. , Hossner L. R. 
Published: July 2010

AbstractSiderite (FeCO3) is found in coal overburden, and is commonly subjected to acidic environments in reclaimed minelands. Manganese commonly substitutes for Fe, and can be present in significant concentrations in the mineral. Siderite was incubated in a solution of either potassium hydrogen phthalate (KHP) or sulfuric acid with an initial pH of 3.0 in environments of CO2, air, or O2. Iron and Mn release from siderite under varying gaseous environments decreased in the following order: CO2 > air > O2. Weathering zones developed that were from 0.39 to 0.85 mm thick. Iron oxides precipitated in the weathering zone and slowed iron release from siderite samples incubated in H2SO4 under all three gaseous atmospheres. Iron oxides did not precipitate in the weathering zone for samples reacted in KHP solution. The release of Fe and Mn to solution followed a zero order reaction rate.
Uptake of a Hydrologic Tracer (Bromide) by Ryegrass from Well and Poorly‐Drained Soils
Authors: Schnabel R. R. , Stout W. L. , Shaffer J. A. 
Published: July 2010

AbstractRyegrass (Lolium perenne L.) accumulated an average 32% of applied bromide (Br−) in aboveground biomass. Bromide uptake was greater on a well‐drained soil (38%) than a poorly drained soil (27%). Uptake was also affected by an interaction between season and N fertility. Bromide concentration of ryegrass was affected by interactions between soil drainage and season, and between soil drainage and N fertility. The magnitude of uptake shows Br− to be quite biologically reactive in the soil root zone. The impact of interactions between common experimental variables on Br− uptake makes it difficult to select settings where Br− uptake will be low. Consequently, the amount and pattern of uptake among common experimental variables greatly restricts the settings in which Br− is an appropriate hydrologic tracer.
Identifying Sites Vulnerable to Phosphorus Loss in Agricultural Runoff
Authors: Sharpley Andrew 
Published: July 2010

AbstractThe continual application of more phosphorus (P) in fertilizer and manure to agricultural systems than removed in harvested crops can lead to surface soil accumulation of P. As a result, soil P has become of environmental rather than agronomic concern in areas of intensive crop and livestock production where P enrichment of runoff can promote eutrophication. To target cost‐effective remedial measures, sites vulnerable to P loss in runoff must be identified. Site identification by traditional field trials and computer simulations can be time consuming, costly, and data intensive. The Lemunyon and Gilbert field index was used to rank the vulnerability for P loss from 30 unfertilized and P‐fertilized, grassed, and cropped watersheds in the Southern Plains. Watershed vulnerability to P loss in runoff was closely related (r2 = 0.70**) to actual losses measured over the last 16 yr (0.1–5 kg P ha−1 yr−1). Vulnerability to P loss decreased in the order: conventionally tilled wheat (Triticum aestivum L.); no‐till wheat; native grass; and set‐aside grass. Also, erosive gully remediation by shaping, sprigging with Midland bermudagrass [Cynodon dactylon (L.) Pers.] reduced vulnerability from medium to low. The P index is a valuable tool to identify P sources within a watershed that will require more intensive management to minimize P loss in runoff while maintaining crop productivity.
Nitrous Oxide Loss from Poultry Manure‐Amended Soil after Rain
Authors: Coyne M. S. , Villalba A. , Blevins R. L. 
Published: July 2010

AbstractLand application of poultry wastes in Kentucky will increase as the broiler industry grows. If poultry manure stimulates N2O loss from soil it will reduce the fertilizer N value of this waste. In contrast, stimulated N2O loss in grass filter strips receiving the runoff from manured fields could help reduce contamination of surface water by NO−3. Our objectives were to determine (i) if poultry manure stimulated N2O loss in soil after rainfall and (ii) if there was an edge‐of‐field effect on N2O loss in grass filters intercepting runoff from amended soil. Soil covers were used to measure N2O loss from a well‐drained, poultry manure‐amended, silt loam soil immediately after simulated rainfall and were also used to measure N2O loss from grass filters intercepting their surface runoff. Nitrous oxide loss from manure‐amended soil was greater than from unamended controls and ranged from 5 to 13 mg N2O‐N m−2 h−1. The maximum N2O loss was equivalent to 3.2 kg N2O‐N ha−1 d−1. Nitrous oxide loss from grass filters intercepting runoff ranged from 0.1 to 1.4 mg N2O‐N m−2 h−1 and was significantly greater than portions of the grass filters that did not intercept runoff. Nitrous oxide loss from poultry manure‐amended soils was greater than N2O loss typically measured from waste‐amended agricultural soils. However, it only represented up to 0.7% of the total N in the applied manure.
Effects of Liming on Soils and Streamwaters in a Deciduous Forest: Comparison of Field Results and Simulations
Authors: Johnson Dale W. , Swank Wayne T. , Vose James M. 
Published: July 2010

AbstractSoil and stream chemical responses to liming in a deciduous forest watershed at Coweeta, NC, are compared with simulation results using the Nutrient Cycling Model (NuCM). Field comparisons of limed and unlimed soils after 23 yr indicated substantial net retention of applied Ca2+ and Mg2+ in upper soil horizons, even in black locust (Robinia pseudoacacia L.) sites where NO−3 leaching was elevated. We hypothesized that NuCM simulations would also show that (i) retention of most applied Ca2+ and Mg2+ in the upper horizons and (ii) increased Ca2+ and Mg2+ retention with increased cation exchange capacity (CEC) and exchangeable H+ (simulating pH‐dependent CEC). Both hypotheses were supported by simulation results for Ca2+, but not for Mg2+. Most applied Mg2+ in the simulations was retained in the BC horizon, where the largest pool of exchangeable Mg2+ was initially located. Increasing CEC and exchangeable H+ did result in increased retention of applied Ca2+ and Mg2+ in surface horizons. However, increasing CEC caused lower Mg2+ retention in the BC horizon, which offset the surface horizon increases and resulted in lower total retention of applied Mg2+. Simulated BC horizon soil solution concentrations mimicked the general patterns in streamwater NO−3, Mg2+, Na+, Cl−, SO2−4, and K+ between 1971 (12 yr after liming) and 1979. NuCM simulations did not, nor was it possible to simulate the observed effects of an insect outbreak on streamwater NO−3.
Assessing Colloidal Forms of Phosphorus and Iron in the Tualatin River Basin
Authors: Mayer T. D. , Jarrell W. M. 
Published: July 2010

AbstractAlthough colloids can affect the transport and chemistry of trace constituents in some aquatic systems, there are few estimates of the mass of given constituents in colloidal forms. The existence, variability, and origin of colloidal Fe oxide, and its effect on P chemistry, was evaluated in the Tualatin River Basin of northwestern Oregon. Watershed streams were regularly sampled during 1992 and 1993. The concentrations of P and Fe in the colloidal size class (0.05–1.0 µm) were determined by filtration. Elemental composition of the suspended material was assessed using scanning electron microscopy/energy‐dispersive spectroscopy (SEM/EDS). Colloidal P and Fe ranged from 0 to 48% and 2 to 77% of the total P and total Fe, respectively. Since filtration underestimates colloidal concentrations, these are conservative estimates. Concentrations of P and Fe in colloidal form were correlated (r2 = 0.83; P < 0.001) but total P, total Fe, and total suspended sediments were not correlated. SEM/EDS analysis showed that, in addition to P and Fe, the colloids contained Si, Al, and Ca. The colloids were enriched with P and Fe relative to Al and Si. Evidence suggests that the colloidal P and Fe particles form as groundwater‐ or sediment‐released Fe(II) is oxidized to Fe(III), which associates with P, either as coatings on the surface of colloidal clays and organics or as homogeneous particles.
Influence of Organic Amendments on Biodegradation of Atrazine as a Nitrogen Source
Authors: Alvey S. , Crowley D. E. 
Published: July 2010

AbstractCarbon and N dynamics may be particularly important for selective enrichment of microorganisms that are capable of using xenobiotics as sources of N for growth. To investigate this hypothesis in relation to s‐triazines, a soil microcosm study was performed to determine the effect of organic amendments differing in complexity and C/N ratio, and the effects of inorganic N addition on atrazine mineralization in a soil having a 15‐yr history of prior exposure to this herbicide. When the soil was spiked with 100 mg/kg of atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) in the absence of organic amendments, 73% of the atrazine was mineralized after 11 wk. Soils amended with rice hulls, starch, and compost yielded mineralization rates of 88, 75, and 59% in the same period, respectively. In contrast, <10% of the atrazine was mineralized in soils amended with glucose, Sudan hay, or sodium citrate. All treatments receiving supplemental inorganic N had a considerably lower rate of atrazine mineralization than corresponding treatments without N addition. However, the different effects of the organic matter supplements suggested there was no relationship between the C/N ratio of the soil and atrazine mineralization. An atrazine‐degrading consortium was subsequently isolated for further characterization. The results demonstrate that while atrazine mineralization is suppressed under high N conditions in this soil, the mineralization rate also is influenced by poorly understood population dynamics related to the nutrient composition and complexity of specific organic amendments.
Effect of Concentration on Persistence of Alachlor in Soil
Authors: Gan J. , Koskinen W. C. , Becker R. L. , Buhler D. D. 
Published: July 2010

AbstractTo determine the behavior of alachlor [2‐chloro‐N‐(methoxymethyl)‐N‐(2,6‐diethylphenyl)‐acetamide] at concentrations common with spill and waste disposal sites, alachlor degradation was determined over a concentration range of 10 to 10 000 mg kg−1 in a Webster clay loam (fine loamy, mixed, mesic Typic Haplaquoll) and an Estherville sandy loam (sandy, mixed, mesic Typic Hapludoll) in laboratory incubation experiments. Effect of concentration on the overall behavior of alachlor was similar in both soils. Based on percent of applied chemical, persistence of alachlor increased with increasing concentration. Mineralization and formation of degradation products and bound residues decreased at higher concentrations. At 10 000 mg kg−1, alachlor was extremely persistent, with estimated 50% dissipation times (DT50) of 12.6 and 13.5 yr in the Webster and Estherville soil, respectively. Although the DT50 increased with increasing concentration, significant amounts of alachlor, in absolute mass, degraded at higher concentration. However, mineralization at 1000 and 10 000 mg kg−1 was similar to that at 100 mg kg−1. Specific alachlor biodegradation mechanisms, limited water solubility, and kinetics of dissolution of precipitated alachlor and alachlor desorption are postulated as the rate‐limiting factors for the degradation of alachlor at elevated levels. A field experiment also indicated alachlor dissipation at high concentration was extremely slow over the first 6 mo after application. Degradation and leaching increased by the following spring. It would appear that an effective remediation means to detoxify alachlor‐contaminated soil would be to land‐spread the soil, thereby diluting the concentration of alachlor in the soil to <100 mg kg−1.