bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local Climate Influences on Precipitation, Cloud Water, and Dry Deposition to an Adirondack Subalpine Forest: Insights from Observations 1986–1996
Authors: Miller Eric K. , Friedland Andrew J. 
Published: July 2010

AbstractFew studies of total atmospheric deposition (dry deposition, cloud droplet capture, rainfall, and snowfall) of major elements (S, N, Ca, Mg, and K) have been conducted in high‐elevation forests. This paper presents the results of the first long‐term observations (1986–1996) of total atmospheric deposition (wet + dry + cloud water) to a subalpine forest in the northeastern USA. Total atmospheric deposition of N to a forest at 1050 m elevation on Whiteface Mountain, NY, averaged 17.2 kg ha−1 yr−1, with 6.5 kg ha−1 yr−1 deposited as NH4 and 10.8 kg ha−1 yr−1 as NO3. Total S deposition averaged 18.3 kg ha−1 yr−1. Orographic effects both enhanced rainfall and increased interannual variance of ion concentrations and wet deposition compared to nearby low‐elevation monitoring stations. Cloud droplet capture by the forest canopy varied substantially from year‐to‐year in response to changing meteorological conditions, contributing between 6 and 31% of total annual water inputs, which averaged 156.1 cm yr−1. Cloud water deposition was responsible for approximately 50%, and dry deposition approximately 10% of total annual N and S deposition. The signal from known decadal trends in atmospheric concentrations and fluxes of S in the northeastern USA was partially masked by high‐frequency (intra‐ and inter‐annual) variance associated with local climatic effects on precipitation and cloud water fluxes at this high‐elevation site. These observations suggest that atmospheric deposition rates to high‐elevation forests may be more responsive to climatic fluctuations and less responsive to recent and expected changes in atmospheric chemical burdens than in surrounding low‐elevation ecosystems.
Evaluation of Dissipation Mechanisms for Benzo[a]pyrene in the Rhizosphere of Tall Fescue
Authors: Banks M. K. , Lee E. , Schwab A. P. 
Published: July 2010

AbstractAlthough polycyclic aromatic hydrocarbons are common contaminants in soil and are potentially carcinogenic and mutagenic, little is known about their fate in the soil/root environment. The impact of tall fescue (Festuca arundinacea Schreber) on chemical and biological transformations of benzo[a]pyrene in soil was investigated in a greenhouse experiment in which 14C‐benzo[a]pyrene was added to soil and placed in sealed chambers with and without plants. The distribution of 14C in soil, plant tissue, and CO2 was quantified. Dissipation due to mineralization and volatilization accounted for <2% of the total 14C added in both planted and unplanted chambers and was greater in the presence of plants. Plant uptake of 14C was <0.12%. Residual benzo[a]pyrene was lower in soil with plants (44%) than in the absence of plants (53%). The majority of the 14C label was associated with the soil matrix. The presence of plants enhance the degradation of highly adsorbed, recalcitrant benzo[a]pyrene in soil.
Biological Selenium Volatilization: Method of Measurement under Field Conditions
Authors: Lin Z.‐Q. , Hansen D. , Zayed A. , Terry N. 
Published: July 2010

AbstractAn open‐flow chamber sampling system was developed for measurements of selenium (Se) volatilization from soil and vegetated areas under field conditions. This paper provides detailed information on the design, construction, and calibration of the chamber sampling system. Volatile Se was collected using a Plexiglas collection chamber, 0.71 m long, 0.71 m wide, and 0.76 in high; the chamber provided an internal volume of 0.38 m3 and enclosed a ground area of 0.5 m2. Volatile Se produced inside the collection chamber was trapped by activated carbon filters from the air leaving the chamber. The trapped Se was extracted from the charcoal filters in alkaline‐peroxide solution. The system has a maximum measurement capacity of 10 mg Se m−2 over a sampling period of 24 h at an air flow rate of 0.43 m3 h−1. Measurements of Se volatilization from the soil‐halophyte system in central California were carried out to demonstrate the efficiency of this sampling system under field conditions.
Role of Groundwater Flow in Tile Drain Discharge
Authors: Vaughan Peter J. , Suarez Donald L. , Simunek Jirka , Corwin Dennis L. , Rhoades James D. 
Published: July 2010

AbstractTile systems drain water applied to agricultural fields as irrigation and precipitation but also may intercept regional groundwater flow. Identification and characterization of the potential sources of tile water is essential for informed management of salinity and contaminants. Factors influencing tile discharge including depth of water applied, evapotranspiration, water storage, drain blockage, and interception of regional groundwater flow were evaluated to determine which may be related to a fivefold variation in cumulative tile discharge among six sumps located 100 km west of Fresno, CA. Cumulative depths drained were calculated for 5 yr of weekly irrigation, precipitation, and discharge data. Evapotranspiration and water storage were estimated using the UnsatchemGeo variably‐saturated water flow model. Well water levels measured on 19 dates were spatially‐averaged providing spatial variation of depth‐to‐water among the drained areas. Variability in depth of water drained (0.18–0.95 m) was large and was not correlated with either water applied (3.26–4.58 m, r2 = 0.03) or with computed water flux from the bottom of the soil column (0.05–0.31 m, r2 = 0.00). Groundwater interception by tile drains was a factor because depth‐to‐water was negatively correlated with discharge (r2 = 0.42) and drawdown of groundwater levels by drains was relatively larger for those drained areas encountered first during regional groundwater flow. For all six sumps, drained water is likely derived from locally applied water and interception of regional groundwater flow implying that standard two‐dimensional models of flow to drains, representing only water applied locally, would not be applicable to modeling of drain flows or drain‐water solute concentrations.
Predicting Land Use Impacts on Regional Scale Groundwater Recharge and Discharge
Authors: Salama Ramsis , Hatton Tom , Dawes Warrick 
Published: July 2010

AbstractThe paper presents the development and evaluation of methods that estimate recharge and discharge, water flow, and salt fluxes in rivers. The methods in combination provide an inferential framework to predict dryland salinity and the selection of the appropriate management scenarios. Hydrogeomorphic Analysis of Regional Spatial Data (HARSD) was used for delineating hydrogeologically homogenous units, and to translate limited hydrological data into hydraulic head surfaces and ultimately a steady state flow net representing recharge‐discharge relationships. A complex, physically based water, energy, and carbon model (WAVES) was developed and tested to provide recharge estimates required for the flow net simulations. Remote sensing imagery and analysis techniques involving airborne, advanced very high resolution reflectance (A VHRR) and LANDSAT‐Thematic Mapper (TM) data were used to infer the temporal and spatial patterns of leaf area index (LA1) and land‐cover type. The techniques were applied in 22 subcatchments in the Loddon and Campaspe and for the two major catchments. Modeled recharge was consistent with local estimates based on inverse methods and with subcatchment‐scale estimates based on stream salt loads under a steady‐state assumption. The calibrated flow nets for each of the subcatchment have been used to test the sensitivity of this system to changes in recharge resulting from land use change. It is shown, for example, that the Upper Campaspe subcatchment would require the reforestation of key recharge areas totaling 45% of the subcatchment to reduce salt loads from approximately 25 000 Mg yr−1 down to 18 000 Mg yr−1 under steady state assumption.
Efficient Calculation of Solute Transport in Heterogeneous Soils Exhibiting Non‐Richards‐Type Unsaturated Flow
Authors: de Rooij Gerrit H. , de Vries Peter 
Published: July 2010

AbstractSoil heterogeneity hampers our ability to calculate field‐scale solute leaching. Many of the existing field‐scale modeling attempts are laborious, time consuming, and computationally demanding. Non‐Richards‐type flows (e.g., fingering) cannot be handled by methods based solely on the heterogeneity of the soil hydraulic properties. We developed a time‐ and cost‐effective approach that starts with a plot‐scale solute transport model that must incorporate any special flow features in the field of interest. The field was modeled as an ensemble of plotscale columns with random properties. The computational demand was reduced by: (i) simplifying the plot‐scale model; (ii) keeping the most influential parameters stochastic; (iii) replacing a full Monte Carlo simulation by systematic parameter sampling; and (iv) transforming the model output for one column to that of another where possible. The method was demonstrated for a field exhibiting fingered flow in the topsoil. A recently developed model to calculate solute leaching from a single finger served as the column‐scale model. Three parameters appeared to be key for solute leaching to the groundwater. For two of them, the breakthrough curve for one value of the parameter could be transformed to approximate the curve for all other values. Consequently, field‐scale solute leaching could be computed with <20 model runs.
A Groundwater Exposure Assessment. for Cloransulam‐Methyl in the U.S. Soybean Market
Authors: van Wesenbeeck Ian J. , Havens Patrick L. 
Published: July 2010

AbstractA study was conducted to examine the leaching potential for cloransulam‐methyl, a new soybean herbicide, in the U.S. soybean market. Expected environmental concentrations (EECs) of cloransulam‐methyl in groundwater were simulated in 60 soils in the use area using the PRZM2 model executed within the PATRIOT shell using conservative soil, weather, and chemical inputs. Modeling results suggested that cloransulam‐methyl is potentially mobile in coarse‐textured soils with <1.5% organic matter (OM) and not mobile in finer‐textured soils. The maximum predicted EEC in groundwater for the most vulnerable soil modeled was 2.7 µg L−1 (ppb), more than two orders of magnitude below the USEPA defined health level of 1000 µg L−1, based on toxicological data. Comparison of EEC distributions in groundwater and EC25 distributions for nontarget terrestrial plants obtained from conservative Tier 2 phytotoxicity studies suggest adequate safety, if shallow groundwater was used as a source of irrigation water on nontarget terrestrial plants. A GIS assessment of coarse textured soils with OM <1.5% and GW <1.83 m deep showed that <2, 3, and 1% of the soils in any given state in the Midwest, Eastern, or Southern soybean markets, respectively, contained soils meeting those criteria for vulnerability (based on modeling). Results of this modeling and exposure assessment are consistent with the rapid dissipation and low mobility of cloransulam‐methyl observed in four terrestrial field dissipation studies conducted in the U.S. soybean market, and suggest that potential mobility of cloransulam‐methyl should have no significant environmental impact.
Nitrogen Mineralization and Nitrification in Suburban and Undeveloped Atlantic White Cedar Wetlands
Authors: Zhu Wei‐Xing , Ehrenfeld Joan G. 
Published: July 2010

AbstractThe presence of urban and suburban lands adjacent to wetlands may cause changes in nutrient‐cycling processes, due to changes in the quality of the ground‐ and surface waters that drain from the developed uplands into the wetland. We studied N‐cycling processes in Atlantic white cedar [Chamaecyparis thyoides (L.)] swamps in the New Jersey Pinelands to determine their sensitivity to the development of adjoining uplands. We conducted a 19‐wk aerobic incubation to measure N mineralization and nitrification potentials in wetland soils from both developed and undeveloped watersheds. The cumulative inorganic N mineralized during the incubation was two to three times higher in soils from developed sites than from the undeveloped sites. There was virtually no nitrification in undeveloped wetlands, while in developed wetlands, most N mineralized was further nitrified. In developed sites, there was also more nitrification in hollow soils than in hummock soils. Both nitrification and the fraction of soil organic matter mineralized were highly correlated with pH and with soil ash content. These results suggest that increases in ash content of peats attributable to sediment transported and deposited in urban runoff, causes increases in pH, which in turn allows large populations of nitrifiers to develop. Excess mineral N generated within the wetlands through changes in microbial function thus may be as important as N inputs in drainage water in affecting plant community composition, and may cause wetlands to become sources of N to downstream ecosystems rather than serving as regional sinks.
Mangrove Soils in Removing Pollutants from Municipal Wastewater of Different Salinities
Authors: Tam N. F. Y. , Wong Y. S. 
Published: July 2010

AbstractSoil leaching experiments were conducted to assess the capacity of mangrove soils in purifying synthetic wastewater containing pollutant concentrations four times of that found in local municipal sewage and of two salinities (fresh vs. saline water). Results on leachate nutrient and heavy metal concentrations reveal that the mangrove soils were capable of removing certain amount of pollutants from wastewater, and the removal efficiency varied between pollutants. The soils were most effective in retaining heavy metals such as Cu but were less effective for Mn and Zn. Similarly, the wastewater‐borne NH+4 was more easily leached than P. The soil data show that most pollutants were accumulated in the top layer (0–1.5 cm) of the soil tray, with little downward migration. Differences between treated and control soil nutrient and heavy metal concentrations were not found in the soil masses below the surface 1.5 cm. In the surface layer, the mangrove soils treated with wastewater had significantly higher concentrations of NH+4‐N, total and extractable P, total and extractable Cu, Cd, Zn and Mn. On the other hand, there was no significant elevation in total nitrogen content in mangrove softs treated with wastewater when compared with the control. Soils receiving wastewater prepared in deionized water (fresh) had slightly higher pollutant concentrations, and larger enrichment factors than that treated with saline wastewater (containing 1.5% salinity). These results suggest that mangrove soils could retain pollutants from wastewater but its efficiency would slightly be affected by salinity.
A Study of Suspended and Colloidal Matter in the Leachate from Lysimeters and its Role in Pesticide Transport
Authors: Worrall F. , Parker A. , Rae J. E. , Johnson A. C. 
Published: July 2010

AbstractThe relative importance of suspended (>0.45 µm) and organic colloidal (<0.45 µm) matter in the transport of pesticide through and across a soil was studied by monitoring suspended and colloidal matter from lysimeters over a winter (1994–1995) and relating it to the leaching of pesticides. The major results were: (i) The organic colloidal matter and suspended sediment appeared at different times in the leachate. (ii) The suspended sediment was enriched in total organic carbon (TOC). (iii) The leaching of pesticide occurred largely in first few samples following rainfall, coinciding with the occurrence of the colloidal matter. (iv) Modelling the distribution of pesticide between the colloids, suspended matter, and pure solution suggests that negligible amounts of isoproturon are carried on suspended sediment and the organic colloids are more important. The importance of organic colloids may be even more significant for compounds more hydrophobic than those studied here: this has implications for the management of soils and pesticides in relation to the release of organic colloids into solution.
Amelioration of Subsoil Acidity through Surface Application of Organic Manures
Authors: Hue N. V. , Licudine D. L. 
Published: July 2010

AbstractSubsoil acidity is a serious constraint to crop production, and is difficult to correct by conventional liming practices. Thus, different approaches to ameliorating acid subsoils are needed. A column leaching study was conducted to compare the effects of chicken manure and sewage sludge amendments, each at 20 g kg−1, with CaSO4 and CaCO3, each at 5.56 cmol (½Ca2+) kg−1, on Al and Ca concentrations in the subsoil of an Ultisol having pH 4.4, 80% Al saturation and 2.78 cmolc kg−1 exchangeable Al. Treatments were incubated moist for 14 d with the top 5 cm soil of 50 cm long soil columns, then leached with 37.8 cm of water in 5 d. The soil columns were then cut into four equal segments for chemical analysis. Results showed that the manures were effective in increasing soil‐solution pH and Ca, and decreasing soil‐solution Al and percentage of Al saturation in the subsoil, particularly below the 15 cm depth. Soil‐solution C, nearly constant through the soil profile, averaged 2.8 mM in the CaSO4 treatment and 7.6 mM in the chicken manure treatment. A subsequent solution experiment on the competitive complexation of Al and Ca with model organic ligands supported the contention that (i) manure‐derived organic molecules facilitated the downward movement of Ca as Ca complexes, and (ii) along their downward path, these Ca complexes reacted with Al, releasing Ca that would become plant‐available, and forming complexed Al that may be nonphytotoxic.
Microbial Responses to Coal Fly Ash under Field Conditions
Authors: Schutter Mary E. , Fuhrmann Jeffry J. 
Published: July 2010

AbstractCoal fly ash may be a valuable soil amendment because it contains plant nutrients and liming agents and has a silty texture that can improve the water‐holding capacities of sandy, drought‐prone soils. Short‐term laboratory studies have indicated that addition of unweathered fly ash to soil can stress microbial populations and their activities, but effects of fly ash addition at the field scale are not known. In this study, field plots received 0 or 505 Mg fly ash ha−1 (incorporated by conventional tillage to a depth of 40 cm) and were subsequently cropped to a fallow‐corn (Zea mays L.)‐wheat (Triticum aestivum L.) rotation or continuous fescue (Festuca arundinacea Schreb.). Twenty months later, during the wheat phase of the rotation, the plots were sampled (0–15 cm) and assayed for activity of soil enzymes (dehydrogenase, alkaline phosphatase, arylsulfatase, and denitrifying enzymes); numbers of aerobic heterotrophs, ammonium oxidizers, denitrifiers, and bradyrhizobia; and N mineralization, nitrification, and denitrification potentials. Nitrification potentials doubled in fly ash‐amended soils, and numbers of denitrifiers were 200‐fold higher in fescue‐cropped, fly ash‐amended soils relative to fescue‐cropped, non‐amended soils. No other large differences in microbial populations or activities were found. The lack of detrimental effects on microorganisms in the field was possibly due to reductions in fly ash's soluble salt and trace element concentrations with time, the mild alkalinity of the fly ash used in this study, and the positive responses of crops to fly ash amendment.
Influence of Daily Carbon Dioxide Exposure Duration and Root Environment on Soybean Response to Elevated Carbon Dioxide
Authors: Heagle A. S. , Booker F. L. , Miller J. E. , Pursley W. A. , Stefanski L. A. 
Published: July 2010

AbstractLittle is known about effects of daily CO2 enrichment duration and root environment on plant response to elevated CO2. Two experiments were performed with Essex soybean (Glycine max L. Merr.) in open‐top field chambers to address these questions. In one experiment, effects of 12 and 24 h d−1 exposures to double‐ambient CO2 were compared for plants grown in 14 L pots that were either insulated to moderate soil temperature or not insulated. Although never significant statistically, trends at some growth stages suggested that nighttime CO2 enrichment contributed to growth and yield. Plants grew and yielded more in insulated than noninsulated pots, but there were no significant CO2 enrichment × insulation interactions. In the second experiment, response to approximately 1.3, 1.6, and 1.9 times ambient CO2 was compared for plants grown in the ground or 14 L pots. Enhancement of photosynthesis, growth, and yield by CO2 enrichment was similar in pots and in the ground. Linear responses to different CO2 concentrations were significant for all yield components in both root environments, whereas quadratic responses were significant for plants in pots but not for plants in the ground. Tests of proportionality of response for yield components showed no evidence of significant differences between plants in pots and in the ground except weight per 100 seeds. Seed yield enhancement at 1.9 times ambient CO2 was 36% for plants in pots and 33% for plants in the ground. Overall, proportional response of soybean to CO2 enrichment was relatively uniform in spite of large differences in baseline growth and yield.
Microcosm Studies on the Volatility of Pesticides from Soil Surfaces
Authors: Lembrich D. , Beese F. , Scheunert I. 
Published: July 2010

AbstractA laboratory model was developed to investigate pesticide volatilization from soil surfaces under various boundary conditions. Carbon‐14‐1abeled terbutylazine (2‐chloro‐4‐ethylamino‐6‐t‐butylamino‐1,3,5‐triazine) was applied to the surface of different soils in doses commonly used in agriculture. The experimental setup was designed to study the dynamics of the volatilization process. Short sampling intervals give information about temporal changes in loss rates, which allows to quantify the influence of the application mode. Drop application, for example, leads to volatilization kinetics different from those by spraying, especially in the initial phase. Another aim of the experiments is to describe soil matrix effects on pesticide volatility. After a test period of 10 d the cumulative vapor loss ranged from minimum 6.9% (loamy sand) to maximum 23.1% (weakly loamy sand) of the applied 14C‐terbutylazine. In the case of a silty loam it was shown that soil moisture had a strong effect on terbutylazine volatilization. Rising the soil water suction resulted in a drastic decline in volatility.