bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Stochastic Empirical Model for Regional Heavy‐Metal Balances in Agroecosystems
Authors: Keller A. , von Steiger B. , van der Zee S.E.A.T.M. , Schulin R. 
Published: June 2010

ABSTRACTMass flux balancing provides essential information for preventive strategies against heavy‐metal accumulation in agricultural soils that may result from atmospheric deposition and application of fertilizers and pesticides. In this paper we present the empirical stochastic balance model, PROTERRA‐S, that estimates heavy‐metal and phosphorus accumulation in agricultural soils on the regional level. The basic units of these balances are land use systems defined by livestock production and cultivated crops. The model is designed to use available databases, such as regional agricultural statistics and soil information systems. In a case study, we assessed the phosphorus, cadmium, and zinc balances for the Sundgau region, Switzerland. The regional P requirements of crops were mainly supplied by animal manure (56%) and commercial fertilizers (40%). Net cadmium fluxes of the land use systems ranged from 1.0 g ha−1 yr−1 (dairy and mixed farm types) to 17.8 g ha−1 yr−1 (animal husbandry systems), whereas the regional net cadmium flux was only 1.4 g ha−1 yr−1 The regional net zinc flux was 605 g ha−1 yr−1 The smallest net zinc flux of 101 g ha−1 yr−1 was found for an arable farm type, whereas for animal husbandry systems fluxes up to 39.8 kg ha−1 yr−1 were estimated. Comparison of model results with reported metal balances of experimental farms shows that identification of agricultural land with high risks of heavy‐metal accumulation benefits from stratification of heavy‐metal balances according to land use systems while accounting for their P fertilization plans. Consequently, the model may support sustainable management of heavy‐metal cycles in agricultural soils.
Biogeochemistry of a Treeline Watershed, Northwestern Alaska
Authors: Stottlemyer Robert 
Published: June 2010

ABSTRACTSince 1950, mean annual temperatures in northwestern Alaska have increased. Change in forest floor and soil temperature or moisture could alter N mineralization rates, production of dissolved organic carbon (DOC) and organic nitrogen (DON), and their export to the aquatic ecosystem. In 1990, we began study of nutrient cycles in the 800‐ha Asik watershed, located at treeline in the Noatak National Preserve, northwestern Alaska. This paper summarizes relationships between topographic aspect, soil temperature and moisture, inorganic and organic N pools, C pools, CO2 efflux, growing season net N mineralization rates, and stream water chemistry. Forest floor (O2) C/N ratios, C pools, temperature, and moisture were greater on south aspects. More rapid melt of the soil active layer (zone of annual freeze–thaw) and permafrost accounted for the higher moisture. The O2 C and N content were correlated with moisture, inorganic N pools, CO2 efflux, and inversely with temperature. Inorganic N pools were correlated with temperature and CO2 efflux. Net N mineralization rates were positive in early summer, and correlated with O2 moisture, temperature, and C and N pools. Net nitrification rates were inversely correlated with moisture, total C and N. The CO2 efflux increased with temperature and moisture, and was greater on south aspects. Stream ion concentrations declined and DOC increased with discharge. Stream inorganic nitrogen (DIN) output exceeded input by 70%. Alpine stream water nitrate (NO−3) and DOC concentrations indicated substantial contributions to the watershed DIN and DOC budgets.
Differential Effects of Surface and Peat Fire on Soil Constituents in a Degraded Wetland of the Northern Florida Everglades
Authors: Smith Stephen M. , Newman Susan , Garrett Patrick B. , Leeds Jennifer A. 
Published: June 2010

ABSTRACTThe effects of surface (aboveground) and peat (belowground) fire on a number of soil constituents were examined within a hydrologically altered marsh in the northern Florida Everglades. Peat fire resulted in losses of total carbon (TC), total nitrogen (TN), and organic phosphorus (Po), while inorganic phosphorus (Pi) and total calcium (TCa) concentrations increased. In addition, peat fire led to a more pronounced vertical gradient in constituent concentrations between upper and lower soil layers. Surface fire also affected soil constituents, but impacts were small relative to peat fire. The effects of physical versus chemical processes during burning were assessed using ratios of constituent to TCa concentrations. This measure indicated that increases in the levels of total phosphorus (TP) in peat‐burned areas were due primarily to the physical reduction of soil, while decreases in TN and TC were the result of volatilization. Increases in concentrations of Pifractions arose from both chemically and physically mediated processes. In an ecological context, the observed soil transformations may encourage the growth of invasive plant species, such as southern narrow‐leaved cattail (Typha domingensisPers.), which exhibits high growth rates in response to increased P availability.
Organochlorine Compounds in a Brazilian Watershed with Sugarcane and Intense Sediment Redistribution
Authors: Sparovek Gerd , Anisimova Marina A. , Kolb Marit , Bahadir Müfit , Wehage Hubert , Schnug Ewald 
Published: June 2010

ABSTRACTUntil 1985 persistent organochlorine compounds such as aldrin [(1α,4α,4aβ,5α,8α,8aβ)‐1,2,3,4,10,10‐hexachloro‐1,4,4a,5,8,8a‐hexahydro‐1,4:5,8‐dimethanonaphthalene] and heptachlor (1,4,5,6,7,8,8‐heptachloro‐3a,4,7,7a‐tetrahydro‐4,7‐methano‐1H‐indene) were recommended and used as insecticides on a large scale in sugarcane (Saccharum officinarum L.) cropping in Brazil. The environmental impact of these applications was not investigated in the past neither prior to nor after their restriction of use in Brazil. In a case study conducted during 1999, organochlorine insecticides were investigated in soils, colluviums, submerged sediments, and organisms in a watershed located in a traditional sugarcane‐growing region in the southeastern region of Brazil. The results indicated that past applications of organochlorine insecticides (prior to 1985) do not represent an environmental threat at the present time. Most insecticides applied in the past were not detected or were present only in amounts that were below the detection limit. The organochlorine compounds lindane [(1α,2α,3β,4α,5α,6β)‐1,2,3,4,5,6‐hexachlorocyclohexane] and heptachlor that remained on the market after 1985 for purposes other than for soil application were still detectable in significant amounts in soils, sediments, and soil organisms (heptachlor in form of the epoxide metabolites). This may suggest that these residues were originated from applications after 1985. These compounds showed a capacity for accumulation in sediments and soil organisms. The enrichment ratio from soils to sediments was 2 to 3 times and from soils to organisms up to 20 times.
Evaluation of the Phosphorus Index in Watersheds at the Regional Scale
Authors: Birr A. S. , Mulla D. J. 
Published: June 2010

ABSTRACTAgricultural losses of phosphorus (P) in runoff are a primary cause of eutrophication in many freshwater systems. A modified version of the P Index originally developed jointly by the USDA (Agricultural Research Service [ARS], Cooperative State Research, Education, and Extension Service [CSREES], and Natural Resources Conservation Service [NRCS]) was used to prioritize P loss vulnerability at the regional scale from 60 watersheds located within Minnesota using readily available data related to the transport and sources of P. This modified version of the P Index was created for a regionally based analysis of the index. Validation of the P Index rating was conducted using long‐term water quality monitoring data consisting of total P concentrations collected from watersheds and lakes. The modified version of the P Index produced a strong correlation between P Index rating and total P stream monitoring data in watersheds (r2 = 0.70) excluding the Red River Basin. An equally strong relationship was observed between P Index rating and lake water quality (r2 = 0.68) using the modified P Index. The P Index ratings for the Red River Basin showed good correlation with observed total P stream monitoring data (r2 = 0.51); however, the P Index ratings were smaller than in other basins. The results of this study suggest that, with certain limitations, the P Index can be used at the regional scale to prioritize P loss vulnerability using state and national databases. Regional P Index ratings represent the average risk for agricultural land within the entire watershed.
Kinetics and Mechanism of Chlorobenzene Degradation in Aqueous Samples Using Advanced Oxidation Processes
Authors: Dilmeghani Mine , Zahir K. Omar 
Published: June 2010

ABSTRACTDegradation of chlorobenzene using various photoinduced oxidation processes such as direct ultraviolet light–induced photolysis (UV), UV–H2O2, UV–O3, and UV–H2O2–O3 was investigated under aerobic and anaerobic conditions. Kinetics and mechanisms of the degradation process were studied using high performance liquid chromatorgraphy (HPLC) and gas chromatorgraphy–mass spectrometry (GC–MS). In all cases, loss of chlorobenzene followed first‐order kinetics. For UV‐induced degradation of chlorobenzene, the observed pseudo first‐order rate constant, kobs, ranged from 1.8 × 10−4 s−1 under anaerobic conditions to 6.4 × 10−4 s−1 for oxygen‐saturated solution. Among the four systems studied, under identical conditions, the degradation rates for UV–H2O2 and UV–H2O2–O3 were very similar and were an order of magnitude higher than the one observed for UV. For the UV–H2O2 system, the observed pseudo first‐order rate constant varied linearly with [H2O2] and followed the rate expression , where kOH is the observed second‐order rate constant for the reaction of OH radical with cholorbenzene. A plot of kobs vs. [H2O2] gave a value of 0.17 ± 0.02 M−1 s−1 for kOH Both HPLC and GC–MS studies showed that depending upon the time of photolysis and the advanced oxidation processes (AOP) method employed, various intermediates were formed during the degradation process. For the UV process, these intermediates were identified as phenol, biphenyl, chlorobiphenyl isomers, and benzaldehyde. For the other three systems, chlorophenol, and various isomers of chlorobiphenyl and dichlorobiphenyl, were observed as the intermediates. The initial pH of the solution decreased from 5.8 to 3.5, showing the release of chlorine from cholobenzene. The HPLC results also showed that at longer times, the subsequent degradation of the intermediates also took place. Carbon dioxide and water are suspected to be the likely end products. Mechanistic schemes for the formation of such intermediates are proposed.
Persistence of Estrogenic Hormones in Agricultural Soils: I. 17β‐Estradiol and Estrone
Authors: Colucci Michael S. , Bork Henry , Topp Edward 
Published: June 2010

ABSTRACTThe persistence and pathways of dissipation of 17β‐estradiol and estrone in soil were established in laboratory microcosm incubations. [4‐14C]‐17β‐Estradiol dissipation and mineralization rates were determined over a range of temperatures and moistures, and this compound was rapidly removed in soil conditions typical of a temperate growing season. 17β‐Estradiol was oxidized to estrone in both autoclaved and nonsterile loam, silt loam, and sandy loam soils, suggesting an abiological transformation. In contrast, estrone was stable in autoclaved soil, suggesting that its removal was microbially mediated. Both [4‐14C]‐17β‐estradiol and [4‐14C]‐estrone formed non‐extractable residues, and soil‐bound residues were only slowly mineralized, suggesting that their bioavailability was low. Determination of total estrogenicity in soil extracts by means of a recombinant yeast assay indicated that there were no other estrogenic compounds produced during 17β‐estradiol dissipation, and that total estrogenicity was rapidly dissipated below the detection limit. We suggest that environmental studies evaluating the movement and persistence of estrogenic hormones from animal wastes should include estrone in their analyses.
Phytosiderophores Influence on Cadmium Mobilization and Uptake by Wheat and Barley Plants
Authors: Shenker M. , Fan T.W.‐M. , Crowley D.E. 
Published: June 2010

ABSTRACTA constant anthropogenic release of cadmium to the environment has resulted in a continuous buildup of Cd in soils. Uptake and accumulation of Cd in plant tissue and in grains may lead to food chain transfer to humans. Application of synthetic chelates was suggested to increase metal mobilization and facilitate phytoextraction as a means for the remediation of metal‐polluted soils. However, most of the chelate‐extracted metal may be leached rather than mobilized to plant roots. In contrast to the synthetic chelates added to soils, plant‐produced chelators called phytosiderophores (PS) are excreted directly to the rhizosphere. Previous studies have shown that PS facilitate uptake of Zn and Fe by graminaceous plants. In this study, a two‐step PS mediation of Cd uptake was hypothesized: (i) extraction and chelation in the soil solution, and (ii) delivery of the chelated Cd to the uptake system of the plant. We examined Cd extraction by PS, the synthetic chelate HEDTA [N‐(2‐hydroxyethyl)‐ethylenediamine‐triacetic acid], and a fungal siderophore rhizoferrin from solid‐phase Cd phosphate at pH 7.3 with and without Fe competition in the presence of Ca and Mg as additional competing metals. While rhizoferrin did not extract Cd, PS and HEDTA did extract Cd even in the presence of Fe. Yet, uptake of Cd by wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) plants was not significantly influenced by Fe stress, but instead was controlled primarily by Cd2+ activity in solution. These results suggest that even though Cd may be mobilized by PS, there is no significant uptake of the Cd–PS complex by the plant roots.
Soil Organic Carbon Pools and Sequestration Rates in Reclaimed Minesoils in Ohio
Authors: Akala V. A. , Lal R. 
Published: June 2010

ABSTRACTA chronosequence of reclaimed minelands under two land uses was studied to determine the potential of minesoil reclamation to sequester carbon (C). Effects of four treatments, consisting of pasture and forest with and without topsoil application, were assessed on temporal changes in soil C pool. The control sites were a 70‐yr‐old marginal agricultural land under pasture and a 65‐yr‐old reclaimed forest land. The soil organic carbon (SOC) pool of pasture treatment with topsoil application increased from 9.2 to 55.4 Mg ha−1 after 25 yr for the 0‐ to 15‐cm depth and from 7.8 to 37.8 Mg ha−1 for the 15‐ to 30‐cm depth. The rate of SOC sequestration in the pasture treatment ranged from 0.5 to 3.1 Mg ha−1 yr−1 for the 0‐ to 15‐cm depth, and from 0.4 to 1.9 Mg ha−1 yr−1 for the 15‐ to 30‐cm depth over the 25‐yr period. The SOC pool of forest treatment with topsoil application increased from 14 to 48.4 Mg ha−1 in 21 yr for the 0‐ to 15‐cm depth, and from 8.4 to 14.5 Mg ha−1 for the 15‐ to 30‐cm depth. The rate of SOC sequestration in the forest treatment ranged from 0.7 to 2.3 Mg ha−1 yr−1 for the 0‐ to 15‐cm depth and from 0.3 to 0.4 Mg ha−1 yr−1 for the 15‐ to 30‐cm depth over the 21‐yr period. The pasture and forest treatments without topsoil application were a minimum of 30 yr old and hence, the SOC pools were almost constant ranging between 60 and 70 Mg ha−1 for the 0‐ to 15‐cm depth and 30 and 40 Mg ha−1 for the 15‐ to 30‐cm depth.
Rapid Incidental Phosphorus Transfers from Grassland
Authors: Preedy Neil , McTiernan Kevin , Matthews Rachel , Heathwaite Louise , Haygarth Phil 
Published: June 2010

ABSTRACTIn Britain, frequent rainfall means that there is a high potential for rapid, direct (incidental) losses of phosphorus (P) to occur after fertilizer or manure application. However, despite the known contribution of P to the eutrophication of water bodies in Britain, such incidental transfers have received little experimental attention. To rectify this, we used lysimeter plots (each 3 × 10 m) to investigate incidental transfers in a composite of overland and lateral subsurface flow (0–27 cm) following the application of different P sources. The treatments used were triple super phosphate (TSP), dairy slurry (Slurry), an equal mix of TSP plus slurry (TSP + Slurry), and no P (Zero P). The treatments were applied to wet soil at a rate of 29 kg ha−1 In the following 169 h, 48.8 mm rainfall (intensity ≤3 mm h−1) resulted in total phosphorus (TP) exports between 1.8 and 2.3 kg ha−1 A single 4‐h period (with overland flow) accounted for 33 to 46% of overall loads from the P‐amended treatments. Concentrations in discharge from TSP + Slurry and TSP peaked at 11000 μg TP L−1 (67–68% as reactive P < 0.45 μm [RP<0.45]). Slurry peaked at 7000 μg TP L−1, 66% as particulate TP (>0.45 μm) and 20% as RP<0.45 Even in subsurface flow, concentrations exceeded 3000 μg TP L−1 for all P‐amended treatments. Incidental TP concentrations in plot discharge were up to 110‐fold higher than those considered eutrophic in inland waters. We suggest that targeting short‐term management decisions for P applications is the most immediately viable method to mitigate P loss and benefit the environment.
Viral and Chemical Tracer Movement through Contrasting Soils
Authors: McLeod Malcolm , Aislabie Jacqueline , Smith James , Fraser Rhonda , Roberts Alexandra , Taylor Matthew 
Published: June 2010

ABSTRACTLand treatment of animal or human waste can result in chemical and microbial contamination of shallow ground water and/or waterways. We investigated the fate of a host‐specific Salmonella bacteriophage and a nonreactive chemical (Br−) tracer when applied to large intact lysimeter soil cores (500 mm diam. by 700 mm high). The soils included a poorly drained Gley Soil and well‐drained Pumice, Allophanic, and Recent Soils. A depth of 30 mm of water containing the bacteriophage and Br− was applied to the soil at a rate of 5 mm h−1 followed by up to about 1.8 pore volumes of simulated rainfall. Resulting leachates, collected continuously over at least one pore volume were analyzed for the bacteriophage and bromide (Br−) tracers. Bromide moved uniformly through the Pumice and Allophanic Soils with peak concentrations at about 1 pore volume, while the bacteriophage was detected only at trace levels or not at all. In contrast, both Br− and bacteriophage tracers moved rapidly through Gley and Recent Soils, appearing early in the leachate and then tailing off. Such flow patterns in the Gley and Recent Soils are indicative of bypass flow. Coarse soil structure in the Gley Soil, and finger‐flow due to water repellency in the sandy Recent Soil are considered responsible for the observed bypass flow in these two soils. Allophanic and Pumice Soils have finer, more porous soil structure leading to a predominance of matrix flow over bypass flow. This study suggests vertical movement of viruses varies significantly with soil type.
Soil Phosphorus Variability in Pastures: Implications for Sampling and Environmental Management Strategies
Authors: Daniels Michael B. , Delaune Paul , Moore Phillip A. , Mauromoustakos Andy , Chapman Stan L. , Langston John M. 
Published: June 2010

ABSTRACTSoil phosphorus (P) is an increasingly important consideration in the development of P‐based nutrient management strategies. The objectives of this study were to (i) obtain baseline information on soil P variability in pastures amended with animal waste, (ii) examine if current sampling recommendations related to the number of subsamples adequately reduce uncertainty to acceptable limits, and (iii) examine the implications of uncertainty in soil P estimates on implementing a soil P threshold of 150 mg kg−1 Grid soil samples were collected from 12 pastures. Soil P was determined using Mehlich 3 extractant and an inductively coupled argon plasma spectrometer. The arithmetic mean of soil P ranged from 7 mg kg−1 in a pasture never amended with animal manure to 437 mg kg−1 in a pasture that had been annually treated long term with poultry litter. Variance of soil P generally increased with mean soil P. The mean standard deviation of all pastures was one‐third of the 150 mg kg−1 threshold. This study points out that smaller variances associated with mean soil P values that approach, but do not exceed, the threshold can influence estimates of soil P. In turn, management decisions could inappropriately change. When a uniform acceptance criteria (within 15 mg kg−1) with respect to measured means was used, the required minimum number of subsamples increased with measured standard deviation. The results of this study imply that following soil‐sampling recommendations is critical to obtaining trustworthy measures of central tendency, especially in pastures approaching but not exceeding the 150 mg kg−1 threshold.
Bioremediation of Residual Fertilizer Nitrate
Authors: Ugwuegbu Benjamin U. , Prasher Shiv O. , Ahmad Darakhshan 
Published: June 2010

ABSTRACTThis exploratory laboratory study was undertaken to develop and test an in situ bioremediation system intended to point the way toward a possible field application. The proposed method uses a water table management (WTM) system to deliver nutrients or other amendments to subsoil microorganisms for biostimulation and subsequent biodegradation of pollutants in the saturated and unsaturated zones of the soil. The study was carried out on packed soil columns and bioremediation of residual fertilizer nitrate was attempted. Different levels of organic carbon supplement (glucose C) were introduced into these columns via subirrigation in order to supplement the readily available organic carbon levels in the soil. The study was carried out in two experimental setups. The first setup investigated (i) the effect of addition of a high (970 mg L−1) and a low (120 mg L−1) glucose C level and (ii) the efficacy of using the subirrigation system as a method for nutrient delivery in bioremediation of leached nitrate. This setup was monitored with time, depth, and with reference to the nitrate residue in the soil solution. Leached nitrate was denitrified to less than 10 mg L−1 nitrate N at both glucose levels. The second setup investigated the effect of a range of low levels of glucose C on nitrate decontamination, soil pH, and total microbial count in order to find out an optimal glucose C level that reduced the most nitrate and maintained the pH homeostasis of soil.
Bioremediation of Residual Fertilizer Nitrate
Authors: Ugwuegbu Benjamin U. , Prasher Shiv O. , Ahmad Darakhshan , Dutilleul Pierre 
Published: June 2010

ABSTRACTThe prospect of using wastewater containing high loads of soluble organic matter (OM) for removing residual agricultural chemicals (fertilizer, pesticide, or herbicide) in farm soil, although promising, could have adverse effects on soil agricultural quality as a result of development of redoximorphic features in the soil profile. In this study, the effect of organic carbon supplement for bioremediation of residual fertilizer nitrate on soil properties, redox potential (Eh), pH, and metal ion mobilization was studied using sandy soils packed in columns. The study was included in a general project, described elsewhere (Ugwuegbu et al., 2000), undertaken to evaluate use of controlled water table management (WTM) systems to supply organic carbon for creating a reduced environment conducive to denitrification of residual fertilizer nitrate leaching from the farm to subsurface water. The columns were subjected to subirrigation with water containing soluble organic carbon in the form of glucose. The work was carried out in two experimental setups and the long‐term effect of a range of glucose concentrations on the Eh, pH, and soluble levels of Fe and Mn was investigated. From the results obtained, it could be concluded that excessive organic carbon supplement to soil can have adverse effects on soil quality and that Eh and soluble Fe are the two most practical parameters for monitoring soil health during treatment of farm chemicals.