bluuebunny/crossref_metadata_2025 huggingface dataset:
Accumulation of Perchlorate in Aquatic and Terrestrial Plants at a Field Scale
Authors: Tan Kui , Anderson Todd A. , Jones Matthew W. , Smith Philip N. , Jackson W. Andrew
Published: June 2010

Previous laboratory‐scale studies have documented perchlorate ClO−4 uptake by different plant species, but less information is available at field scale, where ClO−4 uptake may be affected by environmental conditions, such as distance to streams or shallow water tables, exposure duration, and species. This study examined uptake of ClO−4 in smartweed (Polygonum spp.) and watercress (Nasturtium spp.) as well as more than forty trees, including ash (Fraxinus greggii A. Gray), chinaberry (Melia azedarach L.), elm (Ulmus parvifolia Jacq.), willow (Salix nigra Marshall), mulberry [Broussonetia papyrifera (L.) Vent.], and hackberry (Celtis laevigata Willd.) from multiple streams surrounding a perchlorate‐contaminated site. Results indicate a large potential for ClO−4 accumulation in aquatic and terrestrial plants, with ClO−4 concentration in plant tissues approximately 100 times higher than that in bulk water. Perchlorate accumulation in leaves of terrestrial plants was also dependent on species, with hackberry, willow, and elm having a strong potential to accumulate ClO−4 Generally, trees located closer to the stream had a higher ClO−4 accumulation than trees located farther away from the stream. Seasonal leaf sampling of terrestrial plants indicated that ClO−4 accumulation also was affected by exposure duration, with highest accumulation observed in the late growing cycle, although leaf concentrations for a given tree were highly variable. Perchlorate may be re‐released into the environment via leaching and rainfall as indicated by lower perchlorate concentrations in collected leaf litter. Information obtained from this study will be helpful to understand the fate of ClO−4 in macrophytes and natural systems.
Regional Analysis of Climate, Primary Production, and Livestock Density in Inner Mongolia
Authors: Yu Mei , Ellis James E. , Epstein Howard E.
Published: June 2010

Overstocking is believed to be one of the principal causes for grassland degradation in northern China. For this reason, quantification of overstocking and spatiotemporal analysis are needed for this area. In this study, the relationship between annual rainfall and grassland aboveground net primary production (ANPP) was analyzed using data from 1982 to 1991 in the Inner Mongolia Autonomous Region (IMAR), China. Subsequently, rainfall‐based livestock carrying capacity was estimated and combined with livestock density calculated from county‐level livestock data from 1982 to 1991 to determine spatial and temporal patterns of a stocking rate index and its relationship with climatic factors. The results indicate the following. First, there was a significant linear relationship between annual rainfall and ANPP in IMAR and the slope of ANPP versus rainfall was greater than those found in South America and Africa, indicating higher rain‐use efficiency. Second, temporally averaged livestock density showed overstocking in most of the rural counties except for those in the cold north, where human populations are low and transportation systems are poor. Third, the stocking rate index increased with temperature, from less than 1.0 in the north, to greater than 2.0 in most of the southern IMAR. Within the central IMAR, the index increased from west to east, along the gradient of increasing rainfall. Fourth, long‐term dynamics of livestock density depicted continuous overstocking, more than 20%, from 1982 to 1991 along the western part of the NorthEast China Transect (NECT) within IMAR. Spatial planning of livestock densities according to carrying capacities and improved pastoral management are needed in this area.
Environmental Fate of Triasulfuron in Soils Amended with Municipal Waste Compost
Authors: Said‐Pullicino Daniel , Gigliotti Giovanni , Vella Alfred J.
Published: June 2010

The amendment of soil with compost may significantly influence the mobility and persistence of pesticides and thus affect their environmental fate. Factors like adsorption, kinetics, and rate of degradation of pesticides could be altered in amended soils. The aim of this study was to determine the effects of the addition of compost made from source‐separated municipal waste and green waste, on the fate of triasulfuron [(2‐(2‐chloroethoxy)‐N‐[[4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)amino]carbonyl]benzenesulfonamide], a sulfonylurea herbicide used in postemergence treatment of cereals. Two native soils with low organic matter content were used. A series of analyses was performed to evaluate the adsorption and degradation of the herbicide in soil and in solution after the addition of compost and compost‐extracted organic fractions, namely humic acids (HA), fulvic acids (FA), and hydrophobic dissolved organic matter (HoDOM). Results have shown that the adsorption of triasulfuron to soil increases in the presence of compost, and that the HA and HoDOM fractions are mainly responsible for this increase. Hydrophobic dissolved organic matter applied to the soils underwent sorption reactions with the soils, and in the sorbed state, served to increase the adsorption capacity of the soil for triasulfuron. The rate of hydrolysis of triasulfuron in solution was significantly higher at acidic pH and the presence of organic matter fractions extracted from compost also slightly increased the rate of hydrolysis. The rate of degradation in amended and nonamended soils is explained by a two‐stage degradation kinetics. During the initial phase, although triasulfuron degradation was rapid with a half‐life of approximately 30 d, the presence of compost and HoDOM was found to slightly reduce the rate of degradation with respect to that in nonamended soil.
Distribution of Polychlorinated Biphenyls and Chlorinated Pesticide Residues in Trout in the Sierra Nevada
Authors: Ohyama Kazutoshi , Angermann Jeff , Dunlap Debra Y. , Matsumura Fumio
Published: June 2010

Organochlorine compounds are known to be atmospherically transported to long distances from their original sources. To understand the influence of California's Sierra Nevada range on the air transport and subsequent distribution pattern of some of these residues within the range, we have chosen salmonid fish as an indicator species. Fish were collected from 10 locations throughout the northern and central Sierra Nevada and polychlorinated biphenyl (PCB), toxaphene, chlordane, and DDT [1,1,1‐trichloro, 2,2′‐bis (p‐chlorophenyl) ethane] residues in muscle tissue were analyzed. Rainbow trout (Oncorhynchus mykiss) were found in all sampling locations, and therefore analyses mainly focused on this species. When similar‐sized rainbow trout samples from several similar oligotrophic, high‐altitude lakes and streams were compared, it became apparent that altitude is one of the factors affecting the residual levels of PCB (r2 = 0.882), but not for total DDT, toxaphene, or chlordane in trout. Analysis of correlations among these four organochlorine compound residue groups indicated that there are modest correlations in patterns of distribution between chlordane vs. toxaphene (r2 = 0.345), and chlordane vs. total DDT (r2 = 0.239), but toxaphene residues are not correlated with PCB or total DDT. In view of significant correlation to the altitude it is concluded that PCB residue in rainbow trout is a good monitoring tool for studying the effect of high‐altitude mountain ranges on the long‐range transport and distribution of those persistent pollutants.
Dissolution of Phosphate in a Phosphorus‐Enriched Ultisol as Affected by Microbial Reduction
Authors: Hutchison Kimberly J. , Hesterberg Dean
Published: June 2010

Phosphorus dissolution often increases as soils become more reduced, but the mechanisms are not fully understood. The objectives of this research were to determine rates and mechanisms of P dissolution during microbial reduction of a surface soil from the North Carolina Coastal Plain. Duplicate suspensions of silt + clay fractions from a Cape Fear sandy clay loam (fine, mixed, semiactive, thermic Typic Umbraquult) were reduced in a continuously stirred redox reactor for 40 d. We studied the effects of three treatments on P dissolution: (i) 2 g dextrose kg−1solids added as a microbial carbon source at time 0 d; (ii) 2 g dextrose kg−1solids split into three additions at 0, 12, and 26 d; and (iii) no added dextrose. After 40 d of reduction, concentrations of dissolved reactive phosphorus (DRP) were similar for all treatments and increased up to sevenfold from 1.5 to 10 mg L−1The initial rate of reduction and dissolution of DRP was significantly greater for the 0‐d treatment. A linear relationship (R2= 0.79) was found between DRP and dissolved organic carbon (DOC). Dissolved Fe and Al and pH increased, suggesting the formation of aqueous Fe– and Al–organic matter complexes. Separate batch experiments were performed to study the effects of increasing pH and citrate additions on PO4dissolution under aerobic conditions. Increasing additions of citrate increased concentrations of DRP, Fe, and Al, while increasing pH had no effect. Results indicated that increased dissolved organic matter (DOM) during soil reduction contributed to the increase in DRP, perhaps by competitive adsorption or formation of aqueous ternary DOM–Fe–PO4or DOM–Al–PO4complexes.
Nitrogen Fertilizer Form and Associated Nitrate Leaching from Cool‐Season Lawn Turf
Authors: Guillard Karl , Kopp Kelly L.
Published: June 2010

Various N fertilizer sources are available for lawn turf. Few field studies, however, have determined the losses of nitrate (NO3–N) from lawns receiving different formulations of N fertilizers. The objectives of this study were to determine the differences in NO3–N leaching losses among various N fertilizer sources and to ascertain when losses were most likely to occur. The field experiment was set out in a completely random design on a turf typical of the lawns in southern New England. Treatments consisted of four fertilizer sources with fast‐ and slow‐release N formulations: (i) ammonium nitrate (AN), (ii) polymer‐coated sulfur‐coated urea (PCSCU), (iii) organic product, and (iv) a nonfertilized control. The experiment was conducted across three years and fertilized to supply a total of 147 kg N ha−1 yr−1 Percolate was collected with zero‐tension lysimeters. Flow‐weighted NO3–N concentrations were 4.6, 0.57, 0.31, and 0.18 mg L−1 for AN, PCSCU, organic, and the control, respectively. After correcting for control losses, average annual NO3–N leaching losses as a percentage of N applied were 16.8% for AN, 1.7% for PCSCU, and 0.6% for organic. Results indicate that NO3–N leaching losses from lawn turf in southern New England occur primarily during the late fall through the early spring. To reduce the threat of NO3–N leaching losses, lawn turf fertilizers should be formulated with a larger percentage of slow‐release N than soluble N.
Dynamic Respiration Index as a Descriptor of the Biological Stability of Organic Wastes
Authors: Adani Fabrizio , Confalonieri Roberto , Tambone Fulvia
Published: June 2010

Analytical methods applicable to different organic wastes are needed to establish the extent to which readily biodegradable organic matter has decomposed (i.e., biological stability). The objective of this study was to test a new respirometric method for biological stability determination of organic wastes. Dynamic respiration index (DRI) measurements were performed on 16 organic wastes of different origin, composition, and biological stability degree to validate the test method and result expression, and to propose biological stability limits. In addition, theoretical DRI trends were obtained by using a mathematical model. Each test lasted 96 h in a 148‐L‐capacity respirometer apparatus, and DRI was monitored every hour. The biological stability was expressed as both single and cumulative DRI values. Results obtained indicated that DRI described biological stability in relation to waste typology and age well, revealing lower‐stability waste characterized by a well‐pronounced DRI profile (a marked peak was evident) that became practically flat for samples with higher biological stability. Fitting indices showed good model prediction compared with the experimental data, indicating that the method was able to reproduce the aerobic process, providing a reliable indication of the biological stability. The DRI can therefore be proposed as a useful method to measure the biological stability of organic wastes, and DRI values, calculated as a mean of 24 h of the highest microbial activity, of 1000 and 500 mg O2 kg−1 volatile solids (VS) h−1 are proposed to indicate medium (e.g., fresh compost) and high (e.g., mature compost) biological stabilities, respectively.
Alum Amendment Effects on Phosphorus Release and Distribution in Poultry Litter–Amended Sandy Soils
Authors: Staats Kristin E. , Arai Yuji , Sparks Donald L.
Published: June 2010

Increased poultry production has contributed to excess nutrient problems in Atlantic Coastal Plain soils due to land application of poultry litter (PL). Aluminum sulfate [alum, Al2(SO4)3·14H2O] amendment of PL effectively reduces soluble phosphorus (P) in the PL; however, the effects of these litters when added to acidic, sandy soils are not well understood. The objective of this study was to investigate the efficacy of alum‐amended poultry litter in reducing P release from three Delaware Coastal Plain soils: Evesboro loamy sand (Ev; excessively drained, mesic, coated Typic Quartzipsamments), Rumford loamy sand (Ru; well drained, coarse‐loamy, siliceous, subactive, thermic Typic Hapludults), and Pocomoke sandy loam (Pm; very poorly drained, coarse‐loamy, siliceous, active, thermic Typic Umbraquults). Long‐term (25 d) and short‐term (24 h) desorption studies were conducted, in addition to chemical extractions and kinetic modeling, to observe the changes that alum‐amended versus unamended PL caused in the soils. The Ev, Ru, and Pm soils were incubated with 9 Mg ha−1 of alum‐amended or unamended PL. Long‐term desorption (25 d) of the incubated material resulted in approximately 13.5% (Ev), 12.7% (Ru), and 13.3% (Pm) reductions in cumulative P desorbed when comparing soil treated with unamended and alum‐amended PL. In addition, the P release from the soil treated with alum‐amended litter was not significantly different from the control (soil alone). Short‐term desorption (24 h) showed 7.3% (Ev), 15.4% (Ru), and 20% (Pm) reductions. The overall implication from this study is that the use of alum as a PL amendment is useful in coarse‐textured soils of the Coastal Plain. With increased application of alum‐amended PL, more significant decreases may be possible with little or no effect on soil quality.
Sorption and Detoxification of Toxic Compounds by a Bifunctional Organoclay
Authors: Groisman Ludmila , Rav‐Acha Chaim , Gerstl Zev , Mingelgrin Uri
Published: June 2010

Organoclays are excellent sorbents for nonionic contaminants and therefore may have many environmental applications. A major limitation on the use of organoclays is that the contaminant merely changes its location from one environmental compartment to another while still remaining intact. In this study, a new type of organoclay, termed a bifunctional organoclay, has been prepared. It is able not only to sorb organophosphate pesticides, but also to catalyze their hydrolysis, and thereby detoxify them. The bifunctional organoclay prepared in this study is based on sodium montmorillonite, in which the inorganic counter ions are replaced by N‐decyl‐N,N‐dimethyl‐N‐(2‐aminoethyl) ammonium (DDMAEA). The detoxifying capacity of this organoclay for two organophosphate pesticides, methyl parathion [O,O‐dimethyl O‐(p‐nitrophenyl) thionophosphate] and tetrachlorvinphos [2‐chloro‐1‐(2,4,5‐trichlorophenyl)ethenyl dimethyl phosphate], was demonstrated. It was shown that although the sorption of these pesticides on the bifunctional organoclay is very similar to that on N‐decyl‐N,N,N‐trimethyl ammonium (DTMA) organoclay (the corresponding nonbifunctional organoclay), the hydrolysis of these pesticides is substantially enhanced only by the bifunctional organoclay. The half‐life for the hydrolysis of the investigated pesticides in the presence of the bifunctional organoclay is about 12 times less than for their spontaneous hydrolysis, and the enhancement is even more pronounced relative to the hydrolysis of these pesticides in the presence of the DTMA organoclay (which actually inhibits their hydrolysis). Based on kinetic measurements, the pKa of the ethylamino group of the bifunctional organoclay was estimated to be around 9.0. It is postulated that the catalytic effect of the bifunctional organoclay can be attributed to a nucleophilic attack of the unprotonated ethylamino group of the organoclay on the organophosphate ester.
Phosphorus Transfer in Surface Runoff from Intensive Pasture Systems at Various Scales
Authors: Dougherty Warwick J. , Fleming Nigel K. , Cox Jim W. , Chittleborough David J.
Published: June 2010

Phosphorus transfer in runoff from intensive pasture systems has been extensively researched at a range of scales. However, integration of data from the range of scales has been limited. This paper presents a conceptual model of P transfer that incorporates landscape effects and reviews the research relating to P transfer at a range of scales in light of this model. The contribution of inorganic P sources to P transfer is relatively well understood, but the contribution of organic P to P transfer is still relatively poorly defined. Phosphorus transfer has been studied at laboratory, profile, plot, field, and watershed scales. The majority of research investigating the processes of P transfer (as distinct from merely quantifying P transfer) has been undertaken at the plot scale. However, there is a growing need to integrate data gathered at a range of scales so that more effective strategies to reduce P transfer can be identified. This has been hindered by the lack of a clear conceptual framework to describe differences in the processes of P transfer at the various scales. The interaction of hydrological (transport) factors with P source factors, and their relationship to scale, require further examination. Runoff‐generating areas are highly variable, both temporally and spatially. Improvement in the understanding and identification of these areas will contribute to increased effectiveness of strategies aimed at reducing P transfers in runoff. A thorough consideration of scale effects using the conceptual model of P transfer outlined in this paper will facilitate the development of improved strategies for reducing P losses in runoff.
Trace Element Concentrations in Soil, Corn Leaves, and Grain after Cessation of Biosolids Applications
Authors: Granato Thomas C. , Pietz Richard I. , Knafl George J. , Carlson Carl R. , Tata Prakasam , Lue‐Hing Cecil
Published: June 2010

From 1974 to 1984, 543 Mg ha−1of biosolids were applied to portions of a land‐reclamation site in Fulton County, IL. Soil organic C increased to 5.1% then decreased significantly (p< 0.01) to 3.8% following cessation of biosolids applications (1985–1997). Metal concentrations in amended soils (1995–1997) were not significantly different (p> 0.05) (Ni and Zn) or were significantly lower (p< 0.05) (6.4% for Cd and 8.4% for Cu) than concentrations from 1985–1987. For the same biosolids‐amended fields, metal concentrations in corn (Zea maysL.) either remained the same (p> 0.05, grain Cu and Zn) or decreased (p< 0.05, grain Cd and Ni, leaf Cd, Cu, Ni, Zn) for plants grown in 1995–1997 compared with plants grown immediately following termination of biosolids applications (1985–1987). Biosolids application increased (p< 0.05) Cd and Zn concentrations in grain compared with unamended fields (0.01 to 0.10 mg kg−1for Cd and 23 to 28 mg kg−1for Zn) but had no effect (p> 0.05) on grain Ni concentrations. Biosolids reduced (p< 0.05) Cu concentration in grain compared with grain from unamended fields (1.9 to 1.5 mg kg−1). Biosolids increased (p< 0.05) Cd, Ni, and Zn concentrations in leaves compared with unamended fields (0.3 to 5.6 mg kg−1for Cd, 0.2 to 0.5 mg kg−1for Ni, and 32 to 87 mg kg−1for Zn), but had no significant effect (p> 0.05) on leaf Cu concentrations. Based on results from this field study, USEPA's Part 503 risk model overpredicted transfer of these metals from biosolids‐amended soil to corn.
Residual and Contact Herbicide Transport through Field Lysimeters via Preferential Flow
Authors: Malone R. W. , Shipitalo M. J. , Wauchope R. D. , Sumner H.
Published: June 2010

Usage of glyphosate [N‐(phosphonomethyl)‐glycine] and glufosinate [2‐amino‐4‐(hydroxy‐methylphosphinyl)butanoic acid] may reduce the environmental impact of agriculture because they are more strongly sorbed to soil and may be less toxic than many of the residual herbicides they replace. Preferential flow complicates the picture, because due to this process, even strongly sorbed chemicals can move quickly to ground water. Therefore, four monolith lysimeters (8.1 m2 by 2.4 m deep) were used to investigate leaching of contact and residual herbicides under a worst‐case scenario. Glufosinate, atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine), alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl) acetamide], and linuron (3‐3,4‐dichlorophenyl‐1‐methoxy‐1‐methylurea) were applied in 1999 before corn (Zea mays L.) planting and glyphosate, alachlor, and metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] were applied in 2000 before soybean [Glycine max (L.) Merr.] planting. A high‐intensity rainfall was applied shortly after herbicide application both years. Most alachlor, metribuzin, atrazine, and linuron losses occurred within 1.1 d of rainfall initiation and the peak concentration of the herbicides coincided (within 0.1 d of rainfall initiation in 2000). More of the applied metribuzin leached compared with alachlor during the first 1.1 d after rainfall initiation (2.2% vs. 0.035%, P < 0.05). In 1999, 10 of 24 discrete samples contained atrazine above the maximum contaminant level (atrazine maximum contaminant level [MCL] = 3 μg L−1) while only one discrete sample contained glufosinate (19 μg L−1, estimated MCL = 150 μg L−1). The results indicate that because of preferential flow, the breakthrough time of herbicides was independent of their sorptive properties but the transport amount was dependent on the herbicide properties. Even with preferential flow, glyphosate and glufosinate were not transported to 2.4 m at concentrations approaching environmental concern.
Effect of Combined Application of Methyl Isothiocyanate and Chloropicrin on Their Transformation
Authors: Zheng Wei , Yates Scott R. , Papiernik Sharon K. , Guo Mingxin
Published: June 2010

Combining several soil fumigants to increase the broad spectrum of pest control is a common fumigation practice in current production agriculture. In this study, we investigated the effect of combined application of chloropicrin and methyl isothiocyanate (MITC) on their transformations and persistence in the environment. In aqueous solution, no direct reaction between MITC and chloropicrin occurred and relatively slow rates of hydrolysis of these compounds were observed in aquatic environments free of suspended solids. The transformation of chloropicrin, however, was accelerated in aqueous solution with MITC because of a reduction reaction with bisulfide (HS−), which is a by‐product of MITC hydrolysis. In soil, when fumigants were applied simultaneously, the degradation of MITC was suppressed under the bi‐fumigant application due to the inhibition of soil microbial activity and a possible abiotic competition with chloropicrin for a limited number of reaction sites on the surface of soil particles. However, the degradation rate of chloropicrin was significantly enhanced in the bi‐fumigant soil system, which was primarily attributed to the reaction of chloropicrin and HS− Two sequential application approaches were developed to investigate the feasibility of the combined application of metam sodium (parent compound of MITC) and chloropicrin in soil and assess their potential effects on environmental fate. For both application sequences, the degradation of chloropicrin was accelerated and that of MITC, as a major breakdown product of metam sodium, was inhibited in soil.
Effects of Near‐Surface Hydraulic Gradients on Nitrate and Phosphorus Losses in Surface Runoff
Authors: Zheng Fen‐Li , Huang Chi‐Hua , Norton L. Darrell
Published: June 2010

Phosphorous (P) and nitrogen (N) in runoff from agricultural fields are key components of nonpoint‐source pollution and can accelerate eutrophication of surface waters. A laboratory study was designed to evaluate effects of near‐surface hydraulic gradients on P and N losses in surface runoff from soil pans at 5% slope under simulated rainfall. Experimental treatments included three rates of fertilizer input (control [no fertilizer input], low [40 kg P ha−1, 100 kg N ha−1], and high [80 kg P ha−1, 200 kg N ha−1]) and four near‐surface hydraulic gradients (free drainage [FD], saturation [Sa], artesian seepage without rain [Sp], and artesian seepage with rain [Sp + R]). Simulated rainfall of 50 mm h−1 was applied for 90 min. The results showed that near‐surface hydraulic gradients have dramatic effects on NO3–N and PO4–P losses and runoff water quality. Under the low fertilizer treatment, the average concentrations in surface runoff from FD, Sa, Sp, and Sp + R were 0.08, 2.20, 529.5, and 71.8 mg L−1 for NO3–N and 0.11, 0.54, 0.91, and 0.72 mg L−1 for PO4–P, respectively. Similar trends were observed for the concentrations of NO3–N and PO4–P under the high fertilizer treatment. The total NO3–N loss under the FD treatment was only 0.01% of the applied nitrogen, while under the Sp and Sp + R treatments, the total NO3–N loss was 11 to 16% of the applied nitrogen. These results show that artesian seepage could make a significant contribution to water quality problems.
Uncertainty Assessment of the Model RICEWQ in Northern Italy
Authors: Miao Zewei , Trevisan Marco , Capri Ettore , Padovani Laura , Del Re Attilio A. M.
Published: June 2010

Model predictions are often seriously affected by uncertainties arising from many sources. Ignoring the uncertainty associated with model predictions may result in misleading interpretations when the model is used by a decision‐maker for risk assessment. In this paper, an analysis of uncertainty was performed to estimate the uncertainty of model predictions and to screen out crucial variables using a Monte Carlo stochastic approach and a number of statistical methods, including ANOVA and stepwise multiple regression. The model studied was RICEWQ (Version 1.6.1), which was used to forecast pesticide fate in paddy fields. The results demonstrated that the paddy runoff concentration predicted by RICEWQ was in agreement with field measurements and the model can be applied to simulate pesticide fate at field scale. Model uncertainty was acceptable, runoff predictions conformed to a log‐normal distribution with a short right tail, and predictions were reliable at field scale due to the narrow spread of uncertainty distribution. The main contribution of input variables to model uncertainty resulted from spatial (sediment–water partition coefficient and mixing depth to allow direct partitioning to bed) and management (time and rate of application) parameters, and weather conditions. Therefore, these crucial parameters should be carefully parameterized or precisely determined in each site‐specific paddy field before the application of the model, since small errors of these parameters may induce large uncertainty of model outputs.
Efficacy of Vegetated Buffer Strips for RetainingCryptosporidium parvum
Authors: Tate Kenneth W. , Pereira Maria Das Gracas C. , Atwill Edward R.
Published: June 2010

Overland and shallow subsurface hydrologic transport of pathogenicCryptosporidium parvumoocysts from cattle feces into surface drinking water supplies is a major concern on annual grasslands in California's central and southern Sierra Nevada foothills. Soil boxes (0.5 m wide × 1.1 m long × 0.3 m deep) were used to evaluate the ability of grass vegetated buffer strips to retain 2 × 108spikedC. parvumoocysts in 200‐g fecal deposits during simulated rainfall intensities of 30 to 47.5 mm/h over 2 h. Buffers were comprised of Ahwahnee sandy loam (coarse‐loamy, mixed, active, thermic Mollic Haploxeralfs; 78:18:4 sand to silt to clay ratio; dry bulk density = 1.4 g/cm3) set at 5 to 20% land slope, and ≥95% grass cover (grass stubble height = 10 cm; biomass = 900 kg/ha dry weight). Total number of oocysts discharged from each soil box (combined overland and subsurface flow) during the 120‐min simulation ranged from 1.5 × 106to 23.9 × 106oocysts. Observed overall mean log10reduction of totalC. parvumflux per meter of vegetated buffer was 1.44, 1.19, and 1.18 for buffers at 5, 12, and 20% land slope, respectively. Rainfall application rate (mm/h) was strongly associated with oocyst flux from these vegetated buffers, resulting in a decrease of 2 to 4% in the log10reduction per meter buffer for every additional mm/h applied to the soil box. These results support the use of strategically placed vegetated buffers as one of several management strategies that can reduce the risk of waterborneC. parvumattributable to extensive cattle grazing on annual grassland watersheds.
Transport of Phosphate through Artificial Macropores during Film and Pulse Flow
Authors: Gjettermann Birgitte , Hansen Hans Christian B. , Jensen Henry E. , Hansen S⊘ren
Published: June 2010

Flow through artificial macropores may occur as a water film along the macropore walls (film flow) or as moving water segments separated by air bubbles (pulse flow). To investigate the effect of macropore flow pattern (i.e., film and pulse flow) on the interaction of solutes with macropore walls, we studied orthophosphate (P) transport and sorption in artificial macropores. The experimental setup consisted of a column (height = 20 cm, diameter = 20 cm) homogenously packed with glass beads and fitted at outflow with a vertical artificial macropore placed below the column. The artificial macropore consisted of ceramic tubes (3 or 8 mm i.d.; 31.5 cm long) coated on the inside with iron oxide serving as phosphate sorbents. An orthophosphate solution containing 0.04 mg P L−1 was applied at a rate of 9 to 12 mm h−1 to the column, eventually causing macropore flow. In the 8‐mm‐i.d. tubes only film flow occurred. Pulse flow was dominating in the 3‐mm‐i.d. tubes. Generally, the flow patterns were reproducible and seldom did pulse flow replaced film flow or vice versa. During film flow, a significantly larger decrease in macropore P concentration per tube was observed relative to that with pulse flow events. However, pulse and film flow lead to almost the same amounts of P sorbed per unit surface area when exposed to the same solute P concentration. Comparison with P sorption capacity experiments indicated that the sorption rate, rather than the sorption capacity, controls the amount of sorbed P during macropore flow in the studied system.
Simulating Urban Waste Compost Effects on Carbon and Nitrogen Dynamics Using a Biochemical Index
Authors: Gabrielle Benoît , Da‐Silveira Jeanne , Houot Sabine , Francou Cédric
Published: June 2010

Composting has emerged as a valuable route for the disposal of urban waste, with the prospect of applying composts on arable fields as organic amendments. Proper management of urban waste composts (UWCs) requires a capacity to predict their effects on carbon and nitrogen dynamics in the field, an issue in which simulation models are expected to play a prominent role. However, the parameterization of soil organic amendments within such models generally requires laboratory incubation data. Here, we evaluated the benefit of using a biochemical index based on Van Soest organic matter fractions to parameterize a deterministic model of soil C and N dynamics, NCSOIL, as compared with a standard alternative based on laboratory incubation data. The data included C mineralization and inorganic N dynamics in samples of a silt loam soil (Typic Hapludalf) mixed with various types of UWC and farmyard manure. NCSOIL successfully predicted the various nitrogen mineralization–immobilization patterns observed, but underestimated CO2 release by 10 to 30% with the less stable amendments. The parameterization based on the biochemical index achieved a prediction error significantly larger than the standard parameterization in only 10% of the tested cases, and provided an acceptable fit to experimental data. The decomposition rates and C to N ratios of compost organic matter varied chiefly according to the type of waste processed. However, 62 to 66% of their variance could be explained by the biochemical index. We thus suggest using the latter to parameterize organic amendments in C and N models as a substitute for time‐consuming laboratory incubations.
Denitrification in a Coastal Plain Riparian Zone Contiguous to a Heavily Loaded Swine Wastewater Spray Field
Authors: Hunt P. G. , Matheny T. A. , Stone K. C.
Published: June 2010

Riparian zones are recognized as landscape features that buffer streams from pollutants, particularly nitrogen. The objectives of this experiment were to (i) assess denitrification activity within a riparian zone and (ii) determine the influence of physical, chemical, and landscape features on denitrification. This experiment was conducted from 1994 to 1997 in North Carolina on a riparian zone contiguous to a spray field that was heavily loaded with swine lagoon wastewater. Denitrification enzyme activity (DEA) was measured on soils collected from (i) the soil surface, (ii) midway between the soil surface and water table, and (iii) above the water table. The DEA ranged from 3 to 1660 μg N2O‐N kg−1 soil h−1 The DEA was highest next to the stream and lowest next to the spray field. Nitrate was found to be the limiting factor for denitrification. The DEA generally decreased with soil depth; means for the surface, middle, and bottom depths were 147, 83, and 67 μg N2O‐N kg−1 soil h−1, respectively. These DEA values are higher than those reported for riparian zones adjoining cropland of the southeastern United States, but are lower than those reported for a constructed wetland used for treatment of swine wastewater. Regression analysis indicated that soil total nitrogen was the highest single factor correlated to DEA (r2 = 0.65). The inclusion of water table depth, soil depth, and distance from the spray field improved the R2 to 0.86. This riparian zone possessed sufficient soil area with high denitrifying conditions to be a significant factor in the removal of excess nitrogen in the ground water.
Interpreting Science in the Real World for Sustainable Land Application
Authors: Bastian Robert K.
Published: June 2010

Today's land application practices are designed to effectively treat wastes, and have evolved from earlier practices that centered on cheap disposal with less regard for environmental protection. The major objectives of this paper are to (i) review how current land application practices, and our understanding of them, have evolved over time and (ii) explore how science is used (and sometimes misused or ignored) in the development of design, regulation, and management of sustainable land application. Land treatment technologies have been used effectively for the treatment and recycling of many types of wastewaters and organic residuals for many years. Extensive research and demonstration efforts, as well as experience with pilot‐ and field‐scale projects, have provided the information about soil reactions with contaminants in wastewater and organic residuals needed to design and operate sustainable land application projects. Still, systematic research programs are as important today as ever to support studies aimed at producing information on how soil‐based treatment and recycling systems work, to address new areas of concerns as they arise, and continue to improve the overall design, performance, and reliability of land application systems as sustainable soil treatment and recycling systems.
Geochemical Partitioning of Copper, Lead, and Zinc in Benthic, Estuarine Sediment Profiles
Authors: Burton Edward D. , Phillips Ian R. , Hawker Darryl W.
Published: June 2010

The geochemical partitioning of copper (Cu), lead (Pb), and zinc (Zn) was examined in benthic sediment profiles (0‐ to 20‐cm depth interval) composed of relatively coarse (65–90% sand‐sized particles), noncohesive, suboxic material (Eh +120 to +260 mV). Total Cu, Pb, and Zn concentrations ranged from 8.3 to 194, 16.3 to 74.8, and 30.1 to 220 mg/kg, respectively, and were related to vertical trends in sediment texture. The observed distribution coefficients describing solid–solution partitioning were in the range of 100 to 1000 L/kg. The geochemical partitioning of solid‐phase Cu, Pb, and Zn between six operationally defined fractions was examined with a sequential extraction scheme. The association of Cu, Pb, and Zn with amorphous oxides, crystalline oxides, and organic matter was linearly dependent on the abundance of each respective phase. For retention by amorphous oxide minerals, the observed stoichiometry ranged from 5.2 to 23.7 mg/g for Cu, 12.8 to 21.5 mg/g for Pb, and 23.1 to 85.7 mg/g for Zn. Corresponding values for association with crystalline oxides were an order of magnitude less than those for amorphous oxides, indicating a lesser affinity of trace metals for crystalline oxides. The stoichiometric relationships describing association with organic matter ranged from 17.6 to 54.0 mg/g for Cu, 6.1 to 9.6 mg/g for Pb, and 6.4 to 16.4 mg/g for Zn. The results from this study provide an insight into processes controlling trace metal partitioning in coarse‐textured, suboxic, estuarine sediments.
Surface Biosolids Application: Effects on Infiltration, Erosion, and Soil Organic Carbon in Chihuahuan Desert Grasslands and Shrublands
Authors: Moffet C. A. , Zartman R. E. , Wester D. B. , Sosebee R. E.
Published: June 2010

Land application of biosolids is a beneficial‐use practice whose ecological effects depend in part on hydrological effects. Biosolids were surface‐applied to square 0.5‐m2plots at four rates (0, 7, 34, and 90 dry Mg ha−1) on each of three soil–cover combinations in Chihuahuan Desert grassland and shrubland. Infiltration and erosion were measured during two seasons for three biosolids post‐application ages. Infiltration was measured during eight periods of a 30‐min simulated rain. Biosolids application affected infiltration rate, cumulative infiltration, and erosion. Infiltration increased with increasing biosolids application rate. Application of biosolids at 90 dry Mg ha−1increased steady‐state infiltration rate by 1.9 to 7.9 cm h−1Most of the measured differences in runoff among biosolids application rates were too large to be the result of interception losses and/or increased hydraulic gradient due to increased roughness. Soil erosion was reduced by the application of biosolids; however, the extent of reduction in erosion depended on the initial erodibility of the site. Typically, the greatest marginal reductions in erosion were achieved at the lower biosolids application rates (7 and 34 dry Mg ha−1); the difference in erosion between 34 and 90 dry Mg ha−1biosolids application rates was not significant. Surface application of biosolids has important hydrological consequences on runoff and soil erosion in desert grasslands that depend on the rate of biosolids applied, and the site and biosolids characteristics.
Predicting Runoff and Associated Nitrogen Losses from Turfgrass using the Root Zone Water Quality Model (RZWQM)
Authors: Schwartz Liliana , Shuman Larry M.
Published: June 2010

Nitrogen fertilizers are used to maintain optimum turfgrass quality, but off‐site movement of this primary nutrient can affect water quality. We conducted a 4‐yr study (1998–2001) designed to measure nitrate N runoff from turfgrass, gathering data to be used in the model. The process‐based Root Zone Water Quality Model (RZWQM) was used to predict nitrate associated with runoff from turfgrass. The measurements were made on 12 sloped (5%), 25‐m2 plots of ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers.], managed as golf course fairways and exposed to natural and simulated rainfall. Surface runoff volume and nitrate N loads were monitored after applying simulated rainfall at an average intensity of 27.4 mm h−1 The irrigation occurred (25 or 50 mm) 4 through 168 h after treatment with various rates of N fertilizers for 1998–2001. RZWQM adequately simulated water runoff volumes (<19%; nonsignificant, paired t test) in the first three (normal or wet) years, but overpredicted (70%) in the fourth, dry year. RZWQM overpredicted nitrate N loads by a factor of 1.3 for the first three years (nonsignificant), and by a factor of almost 6 for the fourth year (highly significant). These overpredictions occurred when the runoff volumes and N loads were very small. The research has shown that refinements to RZWQM are needed for turfgrass management applications.
Tillage and Crop Residue Effects on Soil Carbon and Carbon Dioxide Emission in Corn–Soybean Rotations
Authors: Al‐Kaisi Mahdi M. , Yin Xinhua
Published: June 2010

Soil C change and CO2 emission due to different tillage systems need to be evaluated to encourage the adoption of conservation practices to sustain soil productivity and protect the environment. We hypothesize that soil C storage and CO2 emission respond to conservation tillage differently from conventional tillage because of their differential effects on soil properties. This study was conducted from 1998 through 2001 to evaluate tillage effects on soil C storage and CO2 emission in Clarion–Nicollet–Webster soil association in a corn [Zea mays L.]–soybean [Glycine max (L.) Merr.] rotation in Iowa. Treatments included no‐tillage with and without residue, strip‐tillage, deep rip, chisel plow, and moldboard plow. No‐tillage with residue and strip‐tillage significantly increased total soil organic C (TC) and mineral fraction C (MFC) at the 0‐ to 5‐ and 5‐ to 10‐cm soil depths compared with chisel plow after 3 yr of tillage practices. Soil CO2 emission was lower for less intensive tillage treatments compared with moldboard plow, with the greatest differences occurring immediately after tillage operations. Cumulative soil CO2 emission was 19 to 41% lower for less intensive tillage treatments than moldboard plow, and it was 24% less for no‐tillage with residue than without residue during the 480‐h measurement period. Estimated soil mineralizable C pool was reduced by 22 to 66% with less intensive tillage treatments compared with moldboard plow. Adopting less intensive tillage systems such as no‐tillage, strip‐tillage, deep rip, and chisel plow and better crop residue cover are effective in reducing CO2 emission and thus improving soil C sequestration in a corn–soybean rotation.
Removal of Selenate from Water by Zerovalent Iron
Authors: Zhang Yiqiang , Wang Juanfang , Amrhein Chris , Frankenberger William T.
Published: June 2010

Zerovalent iron (ZVI) has been widely used in the removal of environmental contaminants from water. In this study, ZVI was used to remove selenate [Se(VI)] at a level of 1000 μg L−1 in the presence of varying concentrations of Cl−, SO2−4, NO−3, HCO−3, and PO3−4 Results showed that Se(VI) was rapidly removed during the corrosion of ZVI to iron oxyhydroxides (FeOH). During the 16 h of the experiments, 100 and 56% of the added Se(VI) was removed in 10 mM Cl− and SO2−4 solutions under a closed contained system, respectively. Under an open condition, 100 and 93% of the added Se(VI) were removed in the Cl− and SO2−4 solutions, respectively. Analysis of Se species in ZVI–FeOH revealed that selenite [Se(IV)] and nonextractable Se increased during the first 2 to 4 h of reaction, with a decrease of Se(VI) in the Cl− experiment and no detection of Se(VI) in the SO2−4 experiment. Two mechanisms can be attributed to the rapid removal of Se(VI) from the solutions. One is the reduction of Se(VI) to Se(IV), followed by rapid adsorption of Se(IV) to FeOH The other is the adsorption of Se(VI) directly to FeOH, followed by its reduction to Se(IV). The results also show that there was little effect on Se(VI) removal in the presence of Cl− (5, 50, and 100 mM), NO−3 (1, 5, and 10 mM), SO2−4 (5 mM), HCO−3 (1 and 5 mM), or PO3−4 (1 mM) and only a slight effect in the presence of SO2−4 (50 and 100 mM), HCO−3 (10 mM), and PO3−4 (5 mM) during a 2‐d experiment, whereas 10 mM PO3−4 significantly inhibited Se(VI) removal. This work suggests that ZVI may be an effective agent to remove Se from Se‐contaminated agricultural drainage water.
Interactions of Organic Compounds with Wastewater Dissolved Organic Matter: Role of Hydrophobic Fractions
Authors: Ilani Talli , Schulz Elke , Chefetz Benny
Published: June 2010

The role of structural fractions of dissolved organic matter (DOM) from wastewater in the sorption process of hydrophobic organic compounds is still not clear. In this study, DOM from two wastewater treatment plants (Lachish and Netanya, Israel) was fractionated to hydrophobic acid (HoA) and hydrophobic neutral (HoN) fractions. The fractions were characterized and their sorptive capabilities for s‐triazine herbicides and polycyclic aromatic hydrocarbons (PAHs) were studied. For all sorbates, the binding to the HoN fractions was much higher than to HoA fractions. The HoA fractions were more polar than the HoN fractions, containing a higher level of carboxylic functionalities. However the higher binding coefficients of atrazine (2‐chloro‐4‐ethylamine‐6‐isopropylamino‐s‐triazine) and ametryn [2‐(ethylamino)‐4‐isopropylamino‐6‐methyl‐thio‐s‐triazine] obtained for the HoN fractions suggest that their sorption is governed by hydrophobic‐like interactions rather than H bonding. The values of binding coefficients of PAHs measured for the HoN fractions were within the range reported for humic acids and much higher than other fractions, suggesting that this fraction plays an important role in the overall sorption of these compounds by DOM. Higher sorption coefficients were measured for the Netanya DOM sample containing higher level of hydrophobic fractions (HoA + HoN) than the Lachish DOM, suggesting that the sorption of hydrophobic organic compounds by DOM is governed by the level of these structural substances. The evaluation of mobility of organic pollutants by wastewater irrigation requires not only assessment of the total carbon concentration but also, more importantly, the content of the hydrophobic fractions.
Phosphorus in Fresh and Dry Dung of Grazing Dairy Cattle, Deer, and Sheep
Authors: McDowell R. W. , Stewart I.
Published: June 2010

Knowledge of phosphorus (P) fractions in dung of animals (dairy cattle, deer, sheep) grazing pasture is important for soil fertility and the potential for P transport in runoff and subsequent surface water quality deterioration. We used sequential fractionation and 31P nuclear magnetic resonance (NMR) spectroscopy to determine P forms in fresh and air‐dried (to simulate field conditions during grazing) dung. Sheep dung was richest in P (8 g kg−1), and cattle dung poorest (5.5 g kg−1). Data for sequential fractionation indicated that most P was extractable by water (15–36%) and bicarbonate (36–45%) in fresh dung, and shifted toward recalcitrant, HCl (12–28%), and residual P forms (15–31%) with drying. Organic P concentration in dung was poor (maximum of 15% of total P), probably due to the poor concentration of phytate in pasture. The 31P NMR spectra of NaOH‐EDTA extracts supported this by detecting a low concentration of monoesters (9–19% of total P in extracts), of which phytate is a major component. The 31P NMR data also showed that changes in organic P concentration with drying could be due to the degradation of diesters. Data indicate the decreasing bioavailability of dairy cattle, deer, and sheep dung with drying and the need to consider this effect with respect to P returns for soil fertility and the potential for runoff.