bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Incidental Phosphorus Transfers from Grassland
Authors: Preedy Neil , McTiernan Kevin , Matthews Rachel , Heathwaite Louise , Haygarth Phil
Published: June 2010

In 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

Land 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

Soil 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

This 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

The 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.
Behavior of Cinosulfuron in Paddy Surface Waters, Sediments, and Ground Water
Authors: Ferrero A. , Vidotto F. , Gennari M. , Nègre M.
Published: June 2010

Cinosulfuron (3‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐1‐[2‐(2‐methoxyethoxy)‐phenylsulfonyl]‐urea) is a sulfonylurea herbicide used to control a wide range of broadleaf weeds in rice (Oryza sativa L.). A 2‐yr field study was conducted in northwest Italy to determine the effect of cinosulfuron on surface and subsoil waters in rice paddies. Cinosulfuron was applied at 70 g a.i. ha−1 on 35 ha of flooded rice. After the treatment, the change in herbicide concentration over time was studied by analyzing water and sediment samples in a test paddy field (2.16 ha, located in the treated area), water in a spring and a pond (both located near the test paddy), two wells (up‐ and downhill to the treated area), and two piezometers (along the test paddy levee). To better understand some of the field study results, cinosulfuron degradation was also evaluated in the laboratory in solutions buffered to different pH values. Two weeks after the treatment, the cinosulfuron concentration in the paddy water decreased by about 60%. No cinosulfuron was detected at about 2.5 mo after the treatment. The concentration in the sediment gradually increased after the treatment, reaching the highest value (13.53 μg kg−1) 3 wk later. The maximum cinosulfuron content in the spring and pond were 0.91 and 0.29 μg L−1, respectively, and these were detected 60 to 90 days after treatment (DAT). The water collected in the piezometers reached the highest concentration (0.99 μg L−1) 29 DAT. Cinosulfuron was never detected in the wells. In the degradation study at different pH values, cinosulfuron degraded rapidly at low pH values.
Bioavailability of Biosolids Molybdenum to Corn
Authors: O'Connor G.A. , Granato T.C. , Dowdy R.H.
Published: June 2010

This study was part of a larger effort to generate field data appropriate to the assessment of biosolids molybdenum (Mo) risk to ruminants. Corn (Zea mays L.) is an important component of cattle diet, and is a logical crop for biosolids amendment owing to its high N requirement. Paired soil and corn stover samples archived from two unique field experiments were analyzed to quantify the relationship (uptake coefficient, UC) between stover Mo and soil Mo load. Both studies used biosolids with total Mo concentrations typical of modern materials. Data from long‐term (continuous corn) plots in Fulton County, IL confirm expected low Mo accumulation by corn stover, even at very high biosolids loads and soil Mo loads estimated to be near 18 kg Mo ha−1 Uptake slopes were actually negative, but USEPA protocol would assign UC values of 0.001. Data from plots in Minnesota also suggested essentially no correlations between stover Mo and soil Mo loads for continuous corn. However, greater Mo accumulation in corn grown following soybean [Glycine max (L.) Merr.] suggests the possibility of enhanced Mo bioavailability to corn in corn–soybean rotations. Nevertheless, molybdenosis risk to cattle consuming corn stover produced on biosolids‐amended land is small as stover Mo concentrations were always low and stover Cu to Mo ratios exceeded 2:1, which avoids molybdenosis problems.
Modeling Pollutant Release from a Surface Source during Rainfall Runoff
Authors: Walter M. Todd , Parlange J.‐Y. , Walter M. F. , Xin X. , Scott C. A.
Published: June 2010

Though runoff from manure spread fields is recognized as an important mode of nonpoint‐source pollution, there are no models that mechanistically describe transport from a field‐spread manure–type source. A mechanistic, physically based model for pollutant release from a surface source, such as field‐spread manure, was hypothesized, laboratory tested, and field‐applied. The primary objective of this study was to demonstrate the potential applicability of a mechanistic model to pollutant release from surface sources. The laboratory investigation used stable sources and a conservative “pollutant” (KCl) so that the dynamic effects of source dissolution and chemical transformations could be ignored and transport processes isolated. The field investigation used runoff and soluble reactive phosphorus (SP) data collected from a dairy‐manure‐spread field in the Cannonsville watershed in the Catskills region of New York State. The model predictions corroborated well with observations of runoff and pollutant delivery in both the laboratory and the field. “Pollutant” release from surface sources was generally predicted within 11% of laboratory KCl measurements and field SP observations. Laboratory flume runoff predictions with 15 and 26% errors for 25 and 15 mm h−1 simulated rainfall intensity experiments, respectively, represented root mean square errors of less than 0.2 mL s−1 A 26% error was calculated for overland flow predictions in the field, which translated into approximately a 39 mL s−1 error. Results suggest that the hypothesized model satisfactorily represents the primary mechanisms in pollutant release from surface sources.
Artificial Recharge of Humic Ground Water
Authors: Alborzfar M. , Villumsen A. , Grøn C.
Published: June 2010

The purpose of this study was to investigate the efficiency of soil in removing natural organic matter from humic ground waters using artificial recharge. The study site, in western Denmark, was a 10 000 m2 football field of which 2000 m2 served as an infiltration field. The impact of the artificial recharge was studied by monitoring the water level and the quality of the underlying shallow aquifer. The humic ground water contained mainly humic acids with an organic carbon (OC) concentration of 100 to 200 mg C L−1. A total of 5000 m3 of humic ground water were sprinkled onto the infiltration field at an average rate of 4.25 mm h−1. This resulted in a rise in the water table of the shallow aquifer. The organic matter concentration of the water in the shallow aquifer, however, remained below 2.7 mg C L−1. The organic matter concentration of the pore water in the unsaturated zone was measured at the end of the experiment. The organic matter concentration of the pore water decreased from 105 mg C L−1 at 0.5 m to 20 mg C L−1 at 2.5 m under the infiltration field indicating that the soil removed the organic matter from the humic ground water. From these results we conclude that artificial recharge is a possible method for humic ground water treatment.
Fate of Atrazine in Sandy Soil Cropped with Sorghum
Authors: Mbuya O.S. , Nkedi‐Kizza P. , Boote K.J.
Published: June 2010

A field study was conducted to determine the fate of atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) within the root zone (0 to 90 cm) of a sandy soil cropped with sorghum [Sorghum bicolor (L.) Moench] in Gainesville, Florida. Atrazine was uniformly applied at a rate of 1.12 kg a.i. ha−1 to a sorghum crop under moderate irrigation, optimum irrigation, and no irrigation (rainfed), 2 d after crop emergence. Bromide as a tracer for water movement was applied to the soil as NaBr at a rate of 45 kg Br− ha−1, 3 d before atrazine application. Soil water content, atrazine, and Br− concentrations were determined as a function of time using soil samples taken from the root zone. Atrazine sorption coefficients and degradation rates were determined by depth for the entire root zone in the laboratory. Atrazine was strongly adsorbed within the upper 30 cm of soil and most of the atrazine recovered from the soil during the growing season was in that depth. The estimated half‐life for atrazine was 32 d in topsoil to 83 d in subsoil. Atrazine concentration within the root zone decreased from 0.44 kg a.i. ha−1 2 days after application (DAA) to 0.1 kg a.i. ha−1 26 DAA. Negligible amounts of atrazine (≈5 μg kg−1) were detected below the 60‐cm soil depth by 64 DAA. Most of the decrease in atrazine concentration in the root zone over time was attributed to degradation. In contrast, all applied bromide had leached past the 60‐cm soil depth during the same time interval.
Seasonal Hypoxia in the Bottom Water off the Mississippi River Delta
Authors: Rowe Gilbert T.
Published: June 2010

Hypoxia (oxygen concentration less than 2 mg L−1 or 62.5 mmol m−3) occurs on the Louisiana continental shelf during summer when the consumption of oxygen by sediment and water column respiration exceed resupply by photosynthesis and mixing. Biological processes that consume or produce oxygen have been summarized in a budget that can be used to quantify the degree to which consumption in deep water and in the sediments exceeds net production and thus the time it takes to reach hypoxic conditions following the spring onset of stratification. The net consumption rate by the sea floor biota (sediment oxygen consumption, SOC) is inversely related to oxygen concentration and directly related to temperature. Photosynthesis is of potential importance throughout the deep water column and on the sea floor when light is adequate. A non‐steady state, time‐dependent numerical simulation model is used to compare biological and physical processes with shipboard measurements and continuous near‐bottom records. The simulations illustrate possible variations in oxygen concentration on time scales of hours to months, and these in general match much of the variability in the direct observations at time scales of days to weeks. The frequently observed unremitting anoxia lasting weeks at some locations is not produced in the present simulations. A possible explanation is the chemical oxidation in the water column of reduced metabolic end‐products produced in the sediments by anaerobic metabolism. Direct measurements of biological processes could lead to better understanding of how extrinsic forcing functions can best be managed to improve water quality.
Additives to Reduce Ammonia and Odor Emissions from Livestock Wastes: A Review
Authors: McCrory D.F. , Hobbs P.J.
Published: June 2010

This paper reviews the use of additives to reduce odor and ammonia (NH3) emissions from livestock wastes. Reduction of NH3 volatilization has been shown to be possible, particularly with acidifying and adsorbent additives, and potential exists to develop further practical and cost‐effective additives in this area. Masking, disinfecting, and oxidizing agents can provide short‐term control of malodor, but as the capacity of these additives is finite, they require frequent reapplication. Microbial‐based digestive additives may offer a solution to this problem as they are regenerative, but they appear to have been developed without a thorough understanding of microbiological processes occurring in livestock wastes. Currently, their use to reduce odor or NH3 emissions cannot be recommend. If the potential of these types of additives is to be realized, research needs to shift from simply evaluating these unknown products to investigating known strains of bacteria or enzymes with known modes of action. To protect the farmers' interest, standard independent test procedures are required to evaluate efficacy. Such tests should be simple and quantify the capacity of the additive to perform as claimed. The principle use of additives needs to be identified and addressed during their development. Producers may not use effective additives in one area if they further compound other problems that they perceived to be more important. There is the potential to use additives to treat other problems associated with livestock wastes, particularly to improve handling properties, reduce pollution potential to watercourses, and reduce pathogenic bacteria. Further work is required in these areas.
Greenhouse Gases in Non‐Oxygenated and Artificially Oxygenated Eutrophied Lakes during Winter Stratification
Authors: Huttunen Jari T. , Hammar Taina , Alm Jukka , Silvola Jouko , Martikainen Pertti J.
Published: June 2010

Concentrations of dissolved methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) were measured in the water columns of non‐oxygenated and artificially oxygenated, ice‐covered eutrophied lakes in the mid‐boreal zone in Finland during late winter 1997 and 1999. Sampling was conducted during winter stratification, the critical period for oxygen (O2) deficiency in seasonally ice‐covered, thermally stratified lakes. Oxygen concentrations were maintained at least at a moderate level throughout the oxygenated water columns, whereas the non‐oxygenated columns suffered anoxic hypolimnia. The mean concentrations of dissolved CH4 exceeding the atmospheric equilibrium were greater in the non‐oxygenated water columns (20.6–154 μM) than in the oxygenated ones (0.01–1.41 μM). In contrast, the mean excess CO2 concentrations varied less between the non‐oxygenated and oxygenated sites (0.28–0.47 and 0.25–0.31 mM, respectively). Oxygenated water columns had greater mean excess concentrations of N2O (0.018–0.032 μM) than the non‐oxygenated ones (0.005–0.024 μM). If the accumulated greenhouse gas stores in the water columns during winter are assumed to be released to the atmosphere during the spring overturn, the global warming potentials (GWP, time horizon 100 yr) of these potential emissions at the non‐oxygenated, eutrophic study sites ranged from 177 to 654 g CO2 equivalent (CO2–e) m−2 compared with 144 to 173 g CO2–e m−2 at the oxygenated sites. The increase in the accumulation of CH4 was the main reason for the higher GWP of the non‐oxygenated sites. Anthropogenic eutrophication of lake ecosystems can generate increased CH4 emissions due to associated O2 depletion of their sediment and water column.
Removal of Herbicides from Liquid Media by Fungi Isolated from a Contaminated Soil
Authors: Bordjiba Ouahiba , Steiman Régine , Kadri Malika , Semadi Ammar , Guiraud Pascale
Published: June 2010

Fungi were isolated from soil samples corresponding to pesticide‐contaminated soil (CS) and noncontaminated soil (NCS) in the Annaba vicinity (Algeria) and identified. The number of isolates obtained from CS and NCS were 263 and 288, respectively. The most frequent species (Aspergillus fumigatus, A. niger, A. terreus, Absidia corymbifera, and Rhizopus microsporus var microsporus) were not sensitive to the pesticides. The growth of the genus Trichoderma was inhibited by the pesticides, while genera Absidia and Fusarium were stimulated. The 53 species isolated were assayed for their ability to remove metribuzin from liquid medium. Only Botrytis cinerea from NCS and Sordaria superba and Absidia fusca from CS removed more than 50% of the compound after 5 d. Metamitron was very resistant. Among the 21 species tested, only Alternaria solani (from NCS), Drechslera australiensis (from CS and NCS), and Absidia fusca (from CS) reduced the concentration in the medium more than 10% (10–16%). Twelve species were grown with linuron, seven of them were inefficient in removing this compound. The two strains of Sordaria macrospora yielded 22 to 25% depletion, while Botrytis cinerea depleted linuron almost completely. Among the 31 species assayed for their ability to eliminate metobromuron, Botrytis cinerea (from CS and NCS) depleted almost completely the chemical from the medium. Rhizopus oryzae and Absidia fusca from CS removed 40 and 47% of the compound, respectively. No systematic relationships were observed between the soil contamination and herbicide elimination capacities of soil fungi. Absidia fusca and Botrytis cinerea were particularly interesting for bioremediation purposes because they were able to transform efficiently three of the four compounds assayed.
Hardwood Seedling Root and Nutrient Parameters for a Model of Nutrient Uptake
Authors: Kelly J.M. , Scarbrough J.D. , Mays P.A.
Published: June 2010

Use of mechanistic models is an increasingly accepted way to evaluate complex processes. The Barber‐Cushman model provides a means to simulate nutrient uptake once information on root system characteristics, nutrient uptake, and soil nutrient supply are developed. Objectives of this study were to determine during a growing season: (i) root growth for 1‐yr‐old black cherry (Prunus serotinaEhrh.), northern red oak (Quercus rubraL.), and red maple (Acer rubrumL.) seedlings; (ii) net plant increase in N, P, K, Ca, and Mg; (iii) soil solution and solid phase nutrient concentrations; and (iv) the influence of root growth and soil nutrient supply changes on nutrient uptake using the Barber‐Cushman model. Seedlings were grown in pots containing A horizon soil from two forest sites. Measurements were made on five occasions during the growing season. Root growth averaged 41.5 cm d−1for red maple compared with 28.0 and 16.7 cm d−1for cherry and oak, respectively. Seventy‐five percent of root growth occurred at the end of the growing season. Total plant N showed the greatest change (25–58%) due to soil source. Model simulations underestimated observed uptake by 31 to 99%. A clear relationship between soil solution nutrient concentration and plant uptake, an important assumption of the model, was not observed. Results indicate care will need to be exercised in the development and use of root growth and nutrient supply values in mechanistic models.
Fractionation and Mobility of Copper, Lead, and Zinc in Soil Profiles in the Vicinity of a Copper Smelter
Authors: Kabala Cezary , Singh Bal Ram
Published: June 2010

Four soil profiles located near a copper smelter in Poland were investigated for the distribution and chemical fractions of Cu, Pb, and Zn and their mobility in relation to soil properties. Contamination with heavy metals was primarily restricted to surface horizons and the extent of contamination was 7‐ to 115‐fold for Cu, 30‐fold for Pb, and 6‐fold for Zn as compared with subsurface horizons. In the less‐contaminated fine‐textured soil, the metals were distributed in the order: residual >> Fe–Mn oxides occluded > organically complexed > exchangeable and specifically adsorbed, while the order for sandy soils was: residual > organically complexed > Fe–Mn oxides occluded > exchangeable and specifically adsorbed. The contaminated surface horizons of these profiles showed no consistent pattern of metal distribution. However, the common features of highly contaminated soils were very low percentage of residual fraction and the dominance of the NH4OAc extractable fraction. The sum of mobile metal fractions was generally <10% in subsurface horizons, while in the contaminated surface horizons these fractions made up 50% of the total metal contents. Soil properties contributed more to the relative distribution of the metal fractions in the studied profiles than did the distance and direction to the source of pollution. The amounts of metal extracted by 0.01 M CaCl2 accounted for only a small part of the same metals extracted by NH4OAc. The mobility indexes of metals correlated positively and significantly with the total content of metals and negatively with the clay content.
On the Interaction Mechanisms of Atrazine and Hydroxyatrazine with Humic Substances
Authors: Martin‐Neto Ladislau , Traghetta Dinis Gomes , Vaz Carlos M.P. , Crestana Silvio , Sposito Garrison
Published: June 2010

Atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) is retained against leaching losses in soils principally by sorption to organic matter, but the mechanism of sorption has been a matter of controversy. Conflicting evidence exists for proton transfer, electron transfer, and hydrophobic interactions between atrazine and soil humus, but no data are conclusive. In this paper we add to the database by investigating the role of (i) hydroxyatrazine (6‐hydroxy‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) and (ii) hydrophobicity in the sorption of atrazine by Brazilian soil humic substances. We demonstrate, apparently for the first time, that hydroxyatrazine readily forms electron‐transfer complexes with humic substances. These complexes probably are the cause of the well‐known strong adsorption by humic acids and they may be the undetected cause of apparent electron‐transfer complexes between soil organic matter and atrazine, whose transformation to the hydroxy form is facile. We also present evidence that supports the important contribution of hydrophobic interactions to the pH‐dependent sorption of atrazine by humic substances.
Particulate Phosphorus and Sediment in Surface Runoff and Drainflow from Clayey Soils
Authors: Uusitalo Risto , Turtola Eila , Kauppila Tommi , Lilja Taina
Published: June 2010

Recent work has shown that a significant portion of the total loss of phosphorus (P) from agricultural soils may occur via subsurface drainflow. The aim of this study was to compare the concentrations of different P forms in surface and subsurface runoff, and to assess the potential algal availability of particulate phosphorus (PP) in runoff waters. The material consisted of 91 water‐sample pairs (surface runoff vs. subsurface drainage waters) from two artificially drained clayey soils (a Typic Cryaquept and an Aeric Cryaquept) and was analyzed for total suspended solids (TSS), total phosphorus (TP), dissolved molybdate‐reactive phophorus (DRP), and anion exchange resin–extractable phosphorus (AER‐P). On the basis of these determinations, we calculated the concentrations of PP, desorbable particulate phosphorus (PPi), and particulate unavailable (nondesorbable) phosphorus (PUP). Some water samples and the soils were also analyzed for137Cs activity and particle‐size distribution. The major P fraction in the waters studied was PP and, on average, only 7% of it was desorbable by AER. However, a mean of 47% of potentially bioavailable P (AER‐P) consisted of PPi. The suspended soil material carried by drainflow contained as much PPi (47–79 mg kg−1) as did the surface runoff sediment (45–82 mg kg−1). The runoff sediments were enriched in clay‐sized particles and137Cs by a factor of about two relative to the surface soils. Our results show that desorbable PP derived from topsoil may be as important a contributor to potentially algal‐available P as DRP in both surface and subsurface runoff from clayey soils.
Stabilization of Composted Organic Matter after Application to a Humus‐Free Sandy Mining Soil
Authors: Leifeld Jens , Siebert Stefanie , Kögel‐Knabner Ingrid
Published: June 2010

The use of mining substrates for recultivation purposes is limited due to their low organic matter (OM) contents. In a 1‐yr laboratory experiment we evaluated the stabilization of biowaste compost added to a humus‐free sandy mining soil to examine the suitability of compost amendment for the formation of stable soil organic matter (SOM). The stabilization process was characterized by measuring enrichment of OM and nitrogen in particle size fractions obtained after dispersion with different amounts of energy (ultrasonication and shaking in water), carbon mineralization, and amount of dissolved organic carbon (DOC). During the experiment, 17.1% of the organic carbon (OC) was mineralized. Organic carbon enrichment in the <20‐μm particle size fraction at the beginning of the experiment was in the range of natural soils with similar texture. Within 12 mo, a distinct OC redistribution from coarse into fine fractions was found with both dispersion methods. The accumulation of OC was more pronounced for the size separates obtained by ultrasonication, where the carbon distribution between 0.45‐ to 20‐μm particle size fractions increased from 30% at the beginning to 71% at the end of the experiment. Dissolved organic carbon contents ranged between 50 and 68 g kg−1 OC and decreased during the incubation. In conclusion, the exponential decrease of carbon mineralization and the OC enrichment in the fine particle size fractions both indicated a distinct OM stabilization in the mining soil.
Nutrient Conversions by Photosynthetic Bacteria in a Concentrated Animal Feeding Operation Lagoon System
Authors: Sund J.L. , Evenson C.J. , Strevett K.A. , Nairn R.W. , Athay D. , Trawinski E.
Published: June 2010

A diurnal examination was conducted to determine the effect of photosynthetic bacteria on nutrient conversions in a two‐stage concentrated animal feeding operation (CAFO) lagoon system in west‐central Oklahoma. Changes in nutrients, microbial populations, and physical parameters were examined at three depths (0, 1.5, and 3.0 m) every 3 h over a 36‐h period. The south lagoon (SL) was anaerobic (dissolved oxygen [DO] = 0.09 ± 0.12 mg/L) while the north lagoon (NL) was facultative (DO ranged from 4.0–0.1 mg/L over 36‐h period). Negative sulfide–sulfate (−0.85) and bacteriochlorophyll a (bchl a)–sulfate (−0.83) correlations, as well as positive bchl a–sulfide (0.87) and light intensity (I)–bchl a (0.89) correlations revealed that the SL was dominated by sulfur conversions driven by the photosynthetic purple sulfur bacteria (PSB). The correlation data was supported by diurnal trends for sulfate, sulfide, and bchl a Both nitrogen and sulfur conversions played a role in the NL; however, nitrogen conversions appeared to dominate this system because of the activity of cyanobacteria. This was shown by positive chlorophyll a (chl a)–I (0.91) and chl a–nitrate (0.98) correlations and the negative correlation between ammonium and nitrite (−0.88). Correlation data was further supported by diurnal trends observed for chl a, DO, and ammonium. For both lagoons, the dominant photosynthetic microbial species determined which nutrient conversion processes were most important.
Aging Effects on Cadmium Transport in Undisturbed Contaminated Sandy Soil Columns
Authors: Seuntjens P. , Tirez K. , Šimůnek J. , van Genuchten M.Th. , Cornelis C. , Geuzens P.
Published: June 2010

Limited information is available on the effects of contaminant aging (i.e., the contact time of Cd with the soil) on Cd transport in soils. We conducted displacement experiments in which indigenous Cd and freshly applied Cd were leached simultaneously from undisturbed samples of three Spodosol horizons. Sorption of Cd was described using Freundlich isotherms, whereas transport was described as a convection–dispersion process. Parameter optimization analysis using a mobile–immobile transport model applied to nonsorbing tracer displacement data showed that 16 to 22% of the water in the columns was immobile. The low dimensionless mass transfer coefficients in the mobile–immobile model were indicative of diffusion‐limited transfer between mobile and immobile water, and hence physical nonequilibrium. A two‐site kinetic sorption model could be fitted closely to breakthrough curves of the non‐aged Cd for three soil horizons. No conclusive evidence was found that contaminant aging in soil affects cadmium transport. On the one hand, predictions of aged Cd leaching, using parameters estimated from displacement experiments with non‐aged Cd, differed from those for the aged Cd in the E horizon. On the other hand, no meaningful differences in transport behavior between aged and non‐aged Cd were found for the humus Bh and Bh/C horizons. The two‐site kinetic rate coefficient αc was found to depend on water flux, further indicating that mass transfer between sorption sites and the liquid is limited by diffusion rather than by kinetic sorption.
Off‐Site Movement of Endosulfan from Irrigated Cotton in New South Wales
Authors: Kennedy I.R. , Sánchez‐Bayo F. , Kimber S.W. , Hugo L. , Ahmad N.
Published: June 2010

The fate and transport of endosulfan (6,7,8,9,10,10‐hexachloro‐1,5,5a,6,9,9a‐hexahydro‐6,9‐methano‐2,4,3‐benzodioxathiepin 3‐oxide) applied to cotton (Gossypium hirsutum L.) fields were studied throughout three consecutive years on two selected locations in New South Wales (Australia). Rates of dissipation from foliage and soil, volatilization from the field, and transport of residues in irrigation and/or storm runoff waters were measured in order to estimate a total field balance. Dissipation of endosulfan from both foliage and soil is best explained by a two‐phase process rather than by a first‐order decay. Half‐lives of total endosulfan toxic residues (α‐ and β‐endosulfan and the sulfate product) in the first phase were 1.6 d in foliage and 7.1 d in soil, and could be explained by the rapid volatilization of the parent isomers in the first 5 d (up to 70% of endosulfan volatilizes). In the second phase, half‐lives were 9.5 d in foliage and 82 d in soil, mostly due to the persistence of the sulfate product. Concentration of endosulfan residues in runoff water varied from 45 to 2.5 μg L−1 depending on the residue levels present on field soil at the time of the irrigation or storm events. These in turn are related to the total amounts applied, the cotton canopy cover at application, and the time since last spraying. Most of the endosulfan in runoff was found in the water phase (80%), suggesting it was bound to colloidal matter. Total endosulfan residues in runoff for a whole season accounted for no more than 2% of the pesticide applied on‐field.
Simulating Endosulfan Transport in Runoff from Cotton Fields in Australia with the GLEAMS Model
Authors: Connolly R.D. , Kennedy I.R. , Silburn D.M. , Simpson B.W. , Freebairn D.M.
Published: June 2010

Endosulfan (6,7,8,9,10,10‐hexachloro‐1,5,5a,6,9,9a‐hexahydro‐6,9‐methano‐2,4,3‐benzodioxathiepin 3‐oxide), a pesticide that is highly toxic to aquatic organisms, is widely used in the cotton (Gossypium hirsutum L.) industry in Australia and is a risk to the downstream riverine environment. We used the GLEAMS model to evaluate the effectiveness of a range of management scenarios aimed at minimizing endosulfan transport in runoff at the field scale. The field management scenarios simulated were (i) Conventional, bare soil at the beginning of the cotton season and seven irrigations per season; (ii) Improved Irrigation, irrigation amounts reduced and frequency increased to reduce runoff from excess irrigation; (iii) Dryland, no irrigation; (iv) Stubble Retained, increased soil cover created by retaining residue from the previous crop or a specially planted winter cover crop; and (v) Reduced Sprays, a fewer number of sprays. Stubble Retained was the most effective scenario for minimizing endosulfan transport because infiltration was increased and erosion reduced, and the stubble intercepted and neutralized a proportion of the applied endosulfan. Reducing excess irrigation reduced annual export rates by 80 to 90%, but transport in larger storm events was still high. Reducing the number of pesticide applications only reduced transport when three or fewer sprays were applied. We conclude that endosulfan transport from cotton farms can be minimized with a combination of field management practices that reduce excess irrigation and concentration of pesticide on the soil at any point in time; however, discharges, probably with endosulfan concentrations exceeding guideline values, will still occur in storm events.
Fate and Toxicity of Endosulfan in Namoi River Water and Bottom Sediment
Authors: Leonard Alex W. , Hyne Ross V. , Lim Richard P. , Leigh Kellie A. , Le Jiawei , Beckett Ronald
Published: June 2010

Endosulfan (6,7,8,9,10,10,‐hexachloro‐1,5,5a,6,9,9a‐hexahydro‐6,9‐methano‐2,4,3‐benzodioxathiepine‐3‐oxide) sorption (standardized to 1% total organic carbon and dry weight) was significantly (P < 0.05) more concentrated on the large (>63 μm) particle fraction compared with smaller size fractions (<5 μm and 5–24 μm) of bottom sediments from the Namoi River, Australia. Following completion of the particle size fractionation (6 to 12 wk) and a sediment toxicity assessment (2 wk), the sediments showed large decreases in concentrations of α‐endosulfan that coincided with an increase in endosulfan sulfate concentrations and minimal changes in β‐endosulfan concentrations. In the Namoi River, similar patterns were observed in the composition of total endosulfan in monthly measurements of bottom sediments and in passive samplers placed in the water column following runoff from cotton (Gossypium hirsutum L.) fields. The toxicity of endosulfan sulfate in river water indicated by the nymphs of the epibenthic mayfly Jappa kutera, was more persistent than the α‐ and β‐endosulfan parent isomers due to its longer half‐life. This suggests that endosulfan sulfate would contribute most to previously observed changes in population densities of aquatic biota. Measured concentrations of total endosulfan in river water of up to 4 μg L−1 following storm runoff, exceed the range of the 96‐h median lethal concentration (LC50) values in river water for both α‐endosulfan (LC50 = 0.7 μg L−1; 95% confidence interval [CI] = 0.5 to 1.1) and endosulfan sulfate (LC50 = 1.2 μg L−1; 95% CI = 0.4 to 3.3). In contrast, the 10‐d LC50 value for total endosulfan in the sediment toxicity test (LC50 = 162 μg kg−1; 95% CI = 120 to 218 μg kg−1) was more than threefold higher than the highest measured concentration of total endosulfan in field samples of bottom sediment (48 μg kg−1). This suggests that pulse exposures of endosulfan in the water column following storm runoff may be more acutely toxic to riverine biota than in contaminated bottom sediment.
A Micrometeorological Technique to Monitor Total Hydrocarbon Emissions from Landfarms to the Atmosphere
Authors: Ausma Sandra , Edwards Grant C. , Wong Edwina K. , Gillespie Terry J. , Fitzgerald‐Hubble Colleen R. , Halfpenny‐Mitchell Laurie , Mortimer Wendy P.
Published: June 2010

Landfarming is used to treat petroleum hydrocarbon–contaminated soils and a variety of waste streams from industrial operations. Wastes are applied to a soil surface and indigenous soil microorganisms utilize the hydrocarbons in the applied waste as a carbon source for metabolism, thereby biodegrading the applied material. Concerns have been expressed that abiotic losses, such as volatilization, play a significant role in hydrocarbon reduction within the soil. To assist in better defining atmospheric releases of total hydrocarbons from landfarms treating petroleum hydrocarbons, a flux gradient micrometeorological approach was developed and integrated with a custom‐built total hydrocarbon detector, and a novel air sampling system and averaging algorithm. The micrometeorological technique offers unobtrusive spatially averaged real‐time continuous measurements, thereby providing a time history of emissions. This provides opportunities to investigate mechanisms controlling emissions and to evaluate landfarm management strategies. The versatility of the technique is illustrated through measurements performed at a remote landfarm used to treat diesel fuel–contaminated soil in northern Ontario and during routine operations at two active refinery landfarms in southwestern Ontario.
Effect of Land Use on Methane Flux from Soil
Authors: Chan A.S.K. , Parkin T.B.
Published: June 2010

The precise effects of natural and disturbed terrestrial systems on the atmospheric CH4pool are uncertain. This study was conducted to quantify and compare CH4fluxes from a variety of ecosystems in central Iowa. We investigated agricultural systems under different management practices, a hardwood forest site, native and restored prairies, and a municipal landfill. Flux measurements were obtained using a closed‐chamber method, and measurements were compiled by sampling over the 1993 and 1994 growing seasons. In 1993, most of the agricultural sites were net CH4producers with cumulative CH4fluxes ranging from −0.02 to 3.19 g m−2over the 258‐d sampling season, while the natural ecosystems were net CH4consumers, with cumulative seasonal fluxes ranging from −0.27 to −0.07 g m−2258 d−1In 1994, only the landfill and the agricultural site treated with broadcast liquid swine manure (LSM) were net CH4producers, while the remainder of the natural and agricultural ecosystems were net CH4consumers, with mean seasonal flux rates ranging from −0.43 to −0.008 g m−2271 d−1We hypothesize that the differences in CH4fluxes between the two years are due to differences in rainfall. To illustrate the integration between land use and CH4flux, we computed an area‐weighted soil CH4flux for the state of Iowa. Our calculations yielded a net average soil CH4flux of 139000 Mg CH4for 1993 and 1994.
Atrazine, Isoproturon, Mecoprop, 2,4‐D, and Bentazone Adsorption onto Iron Oxides
Authors: Clausen Liselotte , Fabricius Ida
Published: June 2010

Iron oxides are important components influencing the adsorption of various inorganic and organic compounds in soils and sediments. In this study the adsorption on iron oxides of nonionic and ionic pesticides was determined as a function of solution pH, ionic strength, and pesticide concentration. The investigated iron oxides included two‐line ferrihydrite, goethite, and lepidocrocite. Selected pesticides comprised atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine), isoproturon [3‐(4‐isopropylphenyl)‐1,1‐dimethylurea)], mecoprop [(RS)‐2‐(4‐chloro‐2‐methylphenoxy)propionic acid], 2,4‐D (2,4‐dichlorophenoxyacetic acid), and bentazone [3‐isopropyl‐1H‐2,1,3‐benzothiadiazin‐4‐(3H)‐one 2,2‐dioxide]. The adsorption of the nonionic pesticides (atrazine and isoproturon) was insignificant, whereas the adsorption of the acidic pesticides (mecoprop, 2,4‐D, and bentazone) was significant on all investigated iron oxides. The adsorption capacity increased with decreasing pH, with maximum adsorption reached close to the pKa values. The addition of CaCl2 in concentrations from 0.0025 to 0.01 M caused the adsorption capacity to diminish. The adsorption of bentazone was significantly lower than the adsorption of mecoprop and 2,4‐D, illustrating the importance of a carboxyl group in the pesticide structure. The adsorption capacity on the iron oxides increased in the order: lepidocrocite < goethite < two‐line ferrihydrite. The maximum adsorption capacities of mecoprop and 2,4‐D on goethite were found to be equivalent to the site density of singly coordinated hydroxyl groups on the faces of the dominant {110} form, suggesting that singly coordinated hydroxyl groups are responsible for adsorption. Differences in adsorption capacities between iron oxides can be explained by differences in the surface site density of singly coordinated hydroxyl groups. The maximum measured adsorption capacity of mecoprop on two‐line ferrihydrite was equivalent to 0.2 mol/mol Fe.
Photosynthesis, Chlorophyll Integrity, and Spectral Reflectance in Lichens Exposed to Air Pollution
Authors: Garty J. , Tamir O. , Hassid I. , Eshel A. , Cohen Y. , Karnieli A. , Orlovsky L.
Published: June 2010

The major objective of the present study was to identify the relationship of physiologial parameters of the photosynthetic system with the elemental content of the lichen Ramalina lacera (With.) J.R. Laund. Thalli of R. lacera were collected in an unpolluted site and transplanted in a national park and an industrial region in Israel for 8 mo. Analyses of photosynthetic activity, chlorophyll integrity, spectral reflectance, and amount of 11 metals were performed after this period of exposure. The normalized difference vegetation index (NDVI), indicative of the spectral reflectance response of the thallus, correlated with photosynthetic rate and chlorophyll and K content and correlated inversely with amounts of Ba, Cr, Cu, and Ni. The NDVI appears to enable the detection of early signs of pollutant‐induced stress before changes in other physiological parameters become apparent. Elevated amounts of Cr, Cu, Fe, Mn, Ni, and Zn in lichens transplanted to an industrial area and the correlation of Mn and Ni, Mn and V, Ni and V, Fe and Mn, Fe and V, and Fe and Zn point for the greater part to metal processing in a steel smelter. Correlations of Cr and Ni, Cu and Ni, Zn and Cu, Cu and Mn, and Zn and Ni could be related to metal processing in the industrial area but indicate also vehicular activity as a possible originator.