bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of a large ribosomal RNA multigene family in filamentous fungi: Birth and death of a concerted evolution paradigm
Authors: Rooney Alejandro P. , Ward Todd J.
Published: March 2005

In eukaryotes, the primary components of the ribosome are encoded by multicopy nuclear ribosomal RNA (rRNA) genes: 28/26S, 18S, 5.8S, and 5S. Copies of these genes are typically localized within tandem arrays and homogenized within a genome. As a result, nuclear rRNA gene families have become a paradigm of concerted evolution. In filamentous fungi of the subphylum Pezizomycotina, 5S rRNA genes exist as a large and dispersed multigene family, with between 50 and 100 copies per genome. To determine whether these genes defy the concerted evolution paradigm, we examined the patterns of evolution of these genes by using sequences from the complete genomes of four species. Analyses of these sequences revealed (
i
) multiple 5S gene types within a genome, (
ii
) interspecies clustering of gene types, (
iii
) multiple identical gene types shared among species, (
iv
) multiple pseudogenes within a genome, and (
v
) presence/absence variation of individual 5S copies in comparisons of closely related species. These results demonstrate that the 5S family in these species is characterized by birth-and-death evolution under strong purifying selection. Furthermore, our results suggest that birth-and-death evolution occurs at different rates in the genera examined, and that the multiplication and movement of 5S genes across the genome are highly dynamic. As such, we hypothesize that a mechanism resembling retroposition controls
5S
rRNA gene amplification, dispersal, and integration in the genomes of filamentous fungi.
DNA precursor asymmetries in mammalian tissue mitochondria and possible contribution to mutagenesis through reduced replication fidelity
Authors: Song Shiwei , Pursell Zachary F. , Copeland William C. , Longley Matthew J. , Kunkel Thomas A. , Mathews Christopher K.
Published: March 2005

The mutation rate of the mammalian mitochondrial genome is higher than that of the nuclear genome. Because mitochondrial and nuclear deoxyribonucleoside triphosphate (dNTP) pools are physically distinct and because dNTP concentrations influence replication fidelity, we asked whether mitochondrial dNTP pools are asymmetric with respect to each other. We report here that the concentrations of the four dNTPs are not equal in mitochondria isolated from several tissues of both young and old rats. In particular, in most tissues examined, mitochondrial dGTP concentrations are high relative to the other dNTPs. Moreover, in the presence of the biased dNTP concentrations measured in heart and skeletal muscle, the fidelity of DNA synthesis
in vitro
by normally highly accurate mtDNA polymerase γ is reduced, with error frequencies increased by as much as 3-fold, due to increased formation of template T·dGTP mismatches that are inefficiently corrected by proofreading. These data, plus some published data on specific mitochondrial mutations seen in human diseases, are consistent with the hypothesis that normal intramitochondrial dNTP pool asymmetries may contribute to spontaneous mutagenesis in the mammalian mitochondrial genome.
Effects of subthalamic nucleus deep brain stimulation and levodopa on energy production rate and substrate oxidation in Parkinson's disease
Authors: Perlemoine Caroline , Macia Frédéric , Tison François , Coman Isabelle , Guehl Dominique , Burbaud Pierre , Cuny Emmanuel , Baillet Laurence , Gin Henri , Rigalleau Vincent
Published: March 2005

Patients with Parkinson's disease (PD) often lose weight, but after subthalamic nucleus deep brain stimulation (STN-DBS), they gain weight. We compared daily energy intake (DEI), resting energy expenditure (REE) and substrate oxidation rates (measured by indirect calorimetry) in nineteen STN-DBS-treated patients (Group S), thirteen others on pharmacologic treatment by levodopa (Group L) and eight control subjects. We also determined the acute effects of STN-DBS and levodopa on REE and substrate oxidation rates. STN-DBS treated patients gained 9·7 (sem 7·1) kg after surgery, whereas patients on pharmacologic treatment lost 3·8 (sem 10·0) kg since diagnosis. In STN-DBS-treated patients, REE (−16·5 %;P<0·001), lipid oxidation (−27 %;P<0·05) and protein oxidation (−46 %;P<0·05) were decreased, whereas glucose oxidation was elevated (+81 %;P<0·05) as compared to patients on pharmacologic treatment. Levodopa acutely reduced REE (−8·3 %;P<0·05) and glucose oxidation (−37 %;P<0·01) with a slight hyperglycaemic effect (after levodopa challenge: 5·6 (sem 0·8)v.before levodopa challenge: 5·3 (sem 0·6) mmol/l;P<0·01). Switching ‘on’ STN-DBS acutely reduced REE (−17·5 %;P<0·01) and lipid oxidation (−24 %;P<0·001) 30 min after starting stimulation. Fasting glycaemia was slightly but significantly reduced (5·4 (sem 1·4)v.5·5 (sem 1·3) mmol/l;P<0·01). After STN-DBS, the normalization of REE and the reduction in lipid and protein oxidation contribute to the restoration of weight. As levodopa decreases glucose oxidation, the reduction in daily dose of levodopa in STN-DBS-treated patients helps prevent the effect of weight gain on glycaemia.
Vitamins A and E: metabolism, roles and transfer to offspring
Authors: Debier C. , Larondelle Y.
Published: March 2005

Vitamins A and E are essential, naturally occurring, fat-soluble nutrients that are involved in several important biological processes such as immunity, protection against tissue damage, reproduction, growth and development. They are extremely important during the early stages of life and must be transferred adequately to the young during gestation and lactation. The present article presents an overview of their biological functions, metabolism and dynamics of transfer to offspring in mammals. Among other topics, the review focuses on the biochemical aspects of their intestinal absorption, blood transport, tissue uptake, storage and catabolism. It also describes their different roles as well as their use as preventive and therapeutic agents. Finally, the mechanisms involved in their transfer during gestation and lactation are discussed.
The influence of moderate red wine consumption on antioxidant status and indices of oxidative stress associated with CHD in healthy volunteers
Authors: Tsang Catherine , Higgins Siobhan , Duthie Garry G. , Duthie Susan J. , Howie Moira , Mullen William , Lean Michael E. J. , Crozier Alan
Published: March 2005

The effects of moderate red wine consumption on the antioxidant status and indices of lipid peroxidation and oxidative stress associated with CHD were investigated. A randomised, controlled study was performed with twenty free-living healthy volunteers. Subjects in the red wine group consumed 375 ml red wine daily for 2 weeks. We measured the total concentration of phenolics and analysed the individual phenolics in the wine and plasma by HPLC with tandem MS. The antioxidant capacity of plasma was measured with electron spin resonance spectroscopy while homocysteine and fasting plasma lipids were also determined. The production of conjugated dienes and thiobarbituric acid-reactive substances (TBARS) were measured in Cu-oxidised LDL. Plasma total phenolic concentrations increased significantly after 2 weeks of daily red wine consumption (P≤0·001) and trace levels of metabolites, mainly glucuronides and methyl glucuronides of (+)-catechin and (−)-epicatechin, were detected in the plasma of the red wine group. These flavan-3-ol metabolites were not detected in plasma from the control group. The maximum concentrations of conjugated dienes and TBARS in Cu-oxidised LDL were reduced (P≤0·05) and HDL cholesterol concentrations increased (P≤0·05) following red wine consumption. The findings from the present study provide some evidence for potential protective effects of moderate consumption of red wine in healthy volunteers.
Partitioning of limiting protein and energy in the growing pig: description of the problem, possible rules and their qualitative evaluation
Authors: Sandberg Fredrik B. , Emmans Gerry C. , Kyriazakis Ilias
Published: March 2005

A core part of any animal growth model is how it predicts the partitioning of dietary protein and energy to protein and lipid retention for different genotypes at different degrees of maturity. Rules of partitioning need to be combined with protein and energy systems to make predictions. The animal needs describing in relation to its genotype, live weight and, possibly, body composition. Some existing partitioning rules will apply over rather narrow ranges of food composition, animal and environment. Ideally, a rule would apply over the whole of the possible experimental space (scope). The live weight range over which it will apply should at least extend beyond the ‘slaughter weight range’, and ideally would include the period from the start of feeding through to maturity. Solutions proposed in the literature to the partitioning problem are described in detail and criticised in relation to their scope, generality and economy of parameters. They all raise the issue, at least implicitly, of the factors that affect the net marginal efficiency of using absorbed dietary protein for protein retention. This is identified as the crucial problem to solve. A problem identified as important is whether the effects of animal and food composition variables are independent of each other or not. Of the rules in the literature, several could be rejected on qualitative grounds. Those rules that survived were taken forward for further critical and quantitative analysis in the companion paper. (Sandberget al.2005)
Partitioning of limiting protein and energy in the growing pig: testing quantitative rules against experimental data
Authors: Sandberg Fredrik B. , Emmans Gerry C. , Kyriazakis Ilias
Published: March 2005

Literature solutions to the problem of protein and energy partitioning in the growing pig are quantitatively examined. Possible effects of live weight, genotype and food composition on the marginal response in protein retention to protein and energy intakes, on protein and energy-limiting foods are quantified. No evidence was found that the marginal response in protein retention to ideal protein supply, when protein intake is limiting, is affected by live weight, genotype or environmental temperature. There was good evidence that live weight does not affect the marginal response in protein retention to energy intake when protein intake is not limiting. Limited data for different genotypes suggested no effects on this response. A general quantitative partitioning rule is proposed that has two key parameters;ep* (the maximum marginal efficiency for retaining the first limiting amino acid) andR* (the maximum value ofR, the energy to protein ratio of the food, MJ metabolisable energy (ME)/kg digestible crude protein (DCP), whenep* is just achieved). WhenR<R* the material efficiency of using ideal protein is (ep*/R*)×R. The value ofep* was determined to be 0·763 (se 0·0130). There was no good experimental evidence thatep* is different for different amino acids. The best estimate ofR* was 67·9 (se 1·65) MJ ME/kg DCP. Live weight, genotype and temperature did not affect the values of either parameter. A more general understanding of partitioning, including the effects of ‘stressors’ such as disease, may be achieved by using the preferred rule as a starting point.
TARGETING AND CONTEMPORARY AERIAL BOMBARDMENT
Authors: Roscini Marco
Published: March 2005

No place is safe-no place is at peace. There is no place where a woman and her daughter can hide and be at peace. The war comes through the air, bombs drop in the night. Quiet people go out in the morning, and see air-fleets passing overhead-dripping death-dripping death!1
A mathematical method for determining oxygen distribution in skeletal muscle with multiple capillaries and axial diffusion
Authors: Salathe Eric P
Published: March 2005

A mathematical method is presented for analysing oxygen transport in skeletal muscle that includes both the interaction of very large number of capillaries and the effect of axial diffusion in the tissue. The analysis takes into account differences in the blood flow velocity among the capillaries and in the oxygen concentration and haematocrit of the blood entering the capillaries at the arterial end. First, the oxygen concentration is determined within a functional unit consisting of a single capillary surrounded by a region of tissue, in which a flux is prescribed on the outer boundary of the region. The method of matched asymptotic expansions is used to include the effect of axial diffusion in the tissue. The flux that is prescribed on the boundary of the functional unit is a result of the interaction among all the capillaries comprising the vascular bed. These fluxes are found by matching the oxygen concentration along the boundaries of adjacent functional units. This leads to a system of ordinary differential equations for the capillary concentrations coupled with a system of algebraic equations for the fluxes. Results are presented for a two-dimensional array of capillaries when each capillary has a different blood flow velocity. Axial diffusion causes the oxygen concentration to drop more rapidly at the arterial end and remain below the level determined when axial diffusion is neglected. This difference decreases toward the venous end, because the excess oxygen that left the capillaries at the arterial end and diffused axially is available to the tissue there. In some cases a single capillary model, which neglects interaction, incorrectly indicates that portions of the tissue become anoxic, whereas including interaction shows that all of the tissue is in fact supplied with oxygen.
Background-matching and disruptive coloration, and the evolution of cryptic coloration
Authors: Merilaita Sami , Lind Johan
Published: March 2005

Cryptic prey coloration typically bears a resemblance to the habitat the prey uses. It has been suggested that coloration which visually matches a random sample of the background maximizes background matching. We studied this previously untested hypothesis, as well as another, little studied principle of concealment, disruptive coloration, and whether it could, acting in addition to background matching, provide another plausible means of achieving camouflage. We presented great tits (
Parus major
) with artificial background-matching and disruptive prey (DP), and measured detection times. First, we studied whether any random sample of a background produces equally good crypsis. This turned out to not be the case. Next, we compared the DP and the best background-matching prey and found that they were equally cryptic. We repeated the tests using prey with all the coloration elements being whole, instead of some of them being broken by the prey outline, but this did not change the result. We conclude that resemblance of the background is an important aspect of concealment, but that coloration matching a random visual sample of the background is neither sufficient nor necessary to minimize the probability of detection. Further, our study lends empirical support to the principle of disruptive coloration.
Modeling Water Resources: Have We Got it Right?
Authors: Havens Karl E.
Published: March 2005

Aquatic scientists generally recognize that controlled experiments are required to establish cause‐effect relationships (e.g., Havens and Aumen, 2000), and understanding ecological processes is key to accurately predicting complex ecosystem responses. However, resource managers may have at their disposal only a limited amount of observational data when faced with management decisions. Hence, there may be a tendency to use simple empirical models for decision making. An example of eutrophication management in lakes illustrates a pitfall of this approach when used independently of other scientific information.
Cytochromes P450, Oxygen, and Evolution
Authors: Lewis David F.V. , Sheridan Grainné
Published: March 2005

The role of the cytochrome P450 superfamily of heme-thiolate enzymes in oxidative metabolism is discussed in the context of evolutionary development. Concordances between the rise in atmospheric oxygen content, elaboration of the P450 phylogenetic tree and the accepted timescale for the emergence of animal phyla are described. The unique ability of the P450 monooxygenase system to activate molecular oxygen via the consecutive input of two reducing equivalents is explored, such that the possibility of oxygen radical generation and its toxic consequences can be explained in mechanistic terms, together with an appreciation of the ways in which this oxygen activating ability has been utilized by evolving biological systems in their adaptation to an increasing atmospheric oxygen concentration over the past two billon years.
Issues in System Boundary Definition for Substance Flow Analysis: The Case of Nitrogen Cycle Management in Catalonia
Authors: Bartrola Jordi , Martin Maria J. , Rigola Miquel
Published: March 2005

The great complexity of the nitrogen cycle, including anthropogenic contributions, makes it necessary to carry out local studies, which allow us to identify the specific cause-effect links in a particular society. Models of local societies that are based on methods such as Substance Flow Analysis (SFA), which study and characterise the performance of metabolic exchanges between human society and the environment, are a useful tools for directing local policy towards sustainable management of the nitrogen cycle. In this paper, the selection of geographical boundaries for SFA application is discussed. Data availability and accuracy, and the possibility of linking the results with instructions for decision making, are critical aspects for proper scale selection. The experience obtained in the construction of the model for Catalonia is used to draw attention to the difficulties found in regional studies.
Improving Nutrient Efficiency as a Strategy to Reduce Nutrient Surpluses on Dairy Farms
Authors: Ondersteijn C.J.M. , Lansink A.G.J.M. Oude , Giesen G.W.J. , Huirne R.B.M.
Published: March 2005

Dutch nutrient policy aims at reducing leaching of agricultural nutrients by internalizing the negative externalities associated with inefficient nutrient use. This is done by taxation of nitrogen and phosphate surpluses that exceed a hectare-based threshold of maximum-allowed surpluses. One management strategy farmers may use to reduce the nutrient surpluses on their farms is to improve the nutrient efficiency of the agricultural production process. This study employs Data Envelopment Analysis (DEA) to calculate nitrogen and phosphate efficiencies and an overall nutrient efficiency measure for a 3-year panel of 114 Dutch dairy farms. Subsequent analyses show the impact of both farm intensity and nutrient efficiency on the nitrogen and phosphate surpluses. It appears that farm intensity has a positive effect on efficiency, but efficiency and intensity exert opposite influences on nutrient surpluses. This is especially the case for nitrogen. The magnitude of a possible reduction of nitrogen surpluses through a strategy of efficiency improvement is therefore limited by the intensity of the farming system, unless the technology with which nutrients are used by the farming system can be further improved or input/output ratios will be altered.
An Assessment of Ammonia Emissions from Dairy Facilities in Pennsylvania
Authors: Ferguson James D. , Dou Zhengxia , Ramberg Charles F.
Published: March 2005

A survey of 715 Holstein dairy farms in Pennsylvania was used to construct demographics for the average Holstein dairy farm. The average Holstein dairy farm was composed of 69 lactating cows; 11 nonlactating, pregnant cows; 44 heifers; and 18 calves. Milk production averaged 27.3 kg (60.0 lb). Crop area averaged 73.6 ha. Milk production, crop area and type, average county yields, and herd animal groups were used to construct a typical feeding program for these farms. Typical rations were constructed for six feeding groups (three milk production groups, one nonlactating group, two heifer groups) to meet milk production, pregnancy, and growth requirements. Rations were constructed based on three forage qualities (excellent, average, and poor) typically observed on Pennsylvania dairy farms. Data for animal description (milk production, body weight, growth, and pregnancy status) and ration components and amounts consumed for each animal group were input into the excretion model of the Dairy Nutrient Planner computer program (DNP). Excretion of fecal N and dry matter (DM), urinary N, and total P and K were produced for each animal group and used to assess potential volatile losses of N. Work at the Marshak Dairy, New Bolton Center, indicates the majority of urinary N is rapidly lost as ammonia from dairy facilities. Based on this observation, the losses of N as ammonia were estimated to be 4.63, 4.62, and 4.28�tonne/year for the farm with excellent, average, and poor quality forages, respectively. Volatile losses of N may be reduced most by controlling levels of urea in urine. Urinary N may be reduced through dietary manipulation of protein and carbohydrate sources. Conversion of urea to ammonia may be reduced by altering the pH of barn floors and gutters. Entrapment of ammonia may be accomplished by acidification of manure slurry. Atmospheric ammonia contributes to acid rain, eutrophication of estuaries and lakes, and particulate air pollution. Reduction of ammonia emissions from dairy barns can significantly reduce atmospheric pollution and improve air and water quality.
Future Trends in Worldwide River Nitrogen Transport and Related Nitrous Oxide Emissions: A Scenario Analysis
Authors: Kroeze Carolien , Seitzinger Sybil P. , Domingues Rita
Published: March 2005

We analyze possible future trends in dissolved inorganic nitrogen (DIN) export by world rivers and associated emissions of nitrous oxide (N2O). Our scenarios either assume that current trends continue or that nitrogen (N) inputs to aquatic systems are reduced as a result of changes in agriculture practices and fuel combustion technologies. The results indicate that moderate changes in the human diet in North America and Europe, reducing worldwide fertilizer use by only 16%, relative to Business-as-Usual (BAU) levels, may reduce DIN export rates to the North Atlantic and European Seas by about one third and associated N2O emissions by 36 to 77%. We furthermore calculate that relatively large reductions in NOy deposition rates in Europe (of about 80%) may reduce DIN export by rivers by a moderate 8% or less, relative to BAU levels. The potential effect of reduced NOy deposition on riverine DIN export is moderate, because most N in European rivers stems from agriculture, and not from fuel combustion. Nevertheless, the calculated 9% reduction (relative to BAU) in DIN inputs to the North Sea as a potential side effect of air pollution control may help achieve the international policy targets for reduced N inputs to the North Sea.
Environmental Scenarios for the Future Nitrogen Policy in Flanders, Belgium
Authors: Overloop stijn M.M. , Van Gijseghem Dirk E.L.J. , Helming John F.M.
Published: March 2005

The agricultural sector accounts for two thirds of nitrogen losses in Flanders, Belgium. Since 1991 both the government and the farmers have been taking measures to reduce the nitrogen surplus. Initially, the manure policy was aimed at distributing the manure surplus equally across Flanders. At the same time, the growth of livestock was stopped by a strict licensing policy, which required “command and control” measures. In recent years, the policy has switched to the use of individual target commitments by farmers. The Flemish manure policy will be tightened even more as a result of international pressures. An ex ante evaluation of possible policy options was carried out using three different scenarios spread out until 2010 (Business As Usual, Additional Measures, and Sustainable Development). To do this, a sector-economic, regionalized, environmental, comparative static, partial equilibrium, mathematical programming model of the Flemish agriculture was developed. The nitrogen emission into the agricultural soil was calculated by means of a regional soil balance. European targets can only be reached with manure processing, reduced fertilizer usage, and a strong reduction of intensive livestock breeding activities. The atmospheric deposition of nitrogen compounds will strongly decrease in 2010 if additional measures are taken. This will also result in a strong reduction of nitrous oxide emissions.
Inorganic and Organic Losses of Nitrogen from Upland Regions of Britain: Concentrations and Fluxes
Authors: Chapman P.J. , Edwards A.C.
Published: March 2005

The nitrogen (N) composition of streams draining eight upland regions of Britain was compared using monthly samples collected between April 1997 and April 1998. Stream samples were analysed for total N (TN), particulate N (PN), nitrate (NO3), ammonium (NH4), and dissolved organic nitrogen (DON). Concentrations of TN were small, generally less than 1.5 mg N l�1, were dominated by dissolved forms of N, and varied significantly between regions. NO3 accounted for the majority of variability. Concentrations of DON also varied between regions but to a smaller extent than those of NO3. There were considerable variations in TN fluxes between upland regions, which ranged between 3.8 and 16.1 kg N ha�1 year�1. The majority of the variation was due to NO3 fluxes, which were largest in regions receiving largest inputs of atmospheric N deposition and ranged between 1.4 and 13.5 kg N ha�1 year�1. Fluxes of DON ranged between 1 and 3.5 kg N ha�1 year�1, while fluxes of PN were generally less than 0.5 kg N ha�1 year�11, and NH4 fluxes ranged between 0.1 and 0.4 kg N ha�1 year�11. NO3 was the dominant fraction (47�84%) of N exported from all upland regions except the Highlands, where DON accounted for 52% of the TN flux. This study has shown that the DON fraction is an important component of the total N transported by upland streams in Britain.
Gliricidia (Gliricidia sepium) Green Manures as a Potential Source of N for Maize Production in the Tropics
Authors: Bah Abdul R. , Rahman Zaharah A.
Published: March 2005

Use of cheap, N-rich, and environmentally benign legume green manures to correct N deficiency in infertile soils is a very attractive option in the humid tropics. Understanding the influence of management and climate on their effectiveness, and quantifying their contribution to crop productivity, is therefore crucial for technology adoption and adaptation. Mineral N buildup and the contribution to N uptake in maize were studied in an Ultisol amended with fresh Gliricidia leaves. Net mineral N accumulation was compared in mulched and incorporated treatments in a field incubation study. The 15N isotope dilution technique was used to quantify N supplied to maize by Gliricidia leaves in an alley cropping. Mineral N accumulation was slow, but was much greater after incorporation than after mulching. Also, N buildup was always higher in the topsoil (0 to 10 cm) than in the subsoil (10 to 20 cm). More NO3-N was leached than NH4-N, and the effect was greater in the incorporated treatment. Surface-applied Gliricidia leaves significantly increased N uptake by maize, and supplied >30% of the total N in the stover and >20% of that in the corn grain, even in the presence of hedgerows. Thus Gliricidia leaf mulch has immense potential to improve productivity in tropical soils.
Temporal Changes in Nitrogen Pollution in Northeastern Estonia
Authors: Liblik Valdo
Published: March 2005

During the last 5 decades the northeastern part of Estonia (the region where oil shale and the chemical industry are located) has been subjected to pollution with acidic compounds. In 1981–1988 the yearly mean nitrogen (N) deposition load was up to 11.1 kg ha–1. This N pollution level combined with the deposition of sulphur (S) could have seriously endangered the environment, but the simultaneous emission of strongly alkaline fly ash restrained acidification processes. After 1989–1991 the situation changed, and in 1994–1996 the N deposition load in northeastern Estonia remained within the range of 2.6 to 6.6 kg ha–1year–1and that of S within 2 to 50 kg ha–1year–1. Because the fly ash deposition is permanently decreasing, more sensitive lichens and mosses can be subjected to critical N+S loads in the future. The proportion of oil shale industry in total emission of NOxin Estonia from stationary sources equals approximately 65 to 75%. During 1996–2000 the yearly mean concentration of NO2in the air of towns increased from 9 to 12 to 16 to 29 μg m–3. The emission of N compounds was mainly caused by N oxides in flue gases from power plants, as well as ammonia and carbamide discharges from chemical plants. In 1988–1990 the estimated yearly total emission of NOx(as NO2equivalent) was about 18 to 18.6 thousand t and in 1994–2000, 9.9 to 11.8 thousand t.
Monitoring Nitrogen Leaching for the Evaluation of the Dutch Minerals Policy for Agriculture in Clay Regions
Authors: Fraters Dico , Boumans Leo J.M. , van Leeuwen Ton C. , de Hoop Wim D.
Published: March 2005

This paper presents the results of the Dutch monitoring program for agriculture in the clay regions for the period 1996–2000 and evaluates the monitoring strategy. A wide range of farms (25 to 85%) had a NO3–-N concentration in tile drainwater higher than the EU standard of 11.3 mg/l. The low figure is related to wet winters; the high, to dry winters. Arable farms are more prone to NO3–leaching than dairy farms. On arable farms, about 25% of the N surplus leached to groundwater and tile drainwater, on dairy farms this was about 15%. N in tile drainwater has shown to be the best indicator for monitoring the effects of farming practice changes in the clay regions. The average NO3–-N concentration in tile drainwater was 18.8 and 3.2 mg/l in borehole water on farms where both were monitored. It is known that N use has a relationship with NO3–in tile drainwater and not with NH4+and organic N. The presented results indicate that crop rotation and precipitation strongly influence NO3–concentration in tile drainwater.
Application of the ESRI Geostatistical Analyst for Determining the Adequacy and Sample Size Requirements of Ozone Distribution Models in the Carpathian and Sierra Nevada Mountains
Authors: Fraczek Witold , Bytnerowicz Andrzej , Arbaugh Michael J.
Published: March 2005

Models of O3distribution in two mountain ranges, the Carpathians in Central Europe and the Sierra Nevada in California were constructed using ArcGIS Geostatistical Analyst extension (ESRI, Redlands, CA) using kriging and cokriging methods. The adequacy of the spatially interpolated ozone (O3) concentrations and sample size requirements for ozone passive samplers was also examined. In case of the Carpathian Mountains, only a general surface of O3distribution could be obtained, partially due to a weak correlation between O3concentration and elevation, and partially due to small numbers of unevenly distributed sample sites. In the Sierra Nevada Mountains, the O3monitoring network was much denser and more evenly distributed, and additional climatologic information was available. As a result the estimated surfaces were more precise and reliable than those created for the Carpathians. The final maps of O3concentrations for Sierra Nevada were derived from cokriging algorithm based on two secondary variables — elevation and maximum temperature as well as the determined geographic trend. Evenly distributed and sufficient numbers of sample points are a key factor for model accuracy and reliability.
Nitrate in Polluted Mountainous Catchments with Mediterranean Climates
Authors: Meixner Thomas , Fenn Mark , Poth Mark
Published: March 2005

The mountains of southern California receive some of the highest rates of nitrogen (N) deposition in the world (~40 kg ha�1 year�1). These high rates of deposition have translated into consistently high levels of nitrate (NO3�) in some streams of the San Bernardino Mountains. However, not all streams are exhibiting these high levels of NO3�. Perennial streams have high NO3� concentrations (~200 [b.mu ]moles l�1) while ephemeral streams do not (~20 [b.mu ]moles l�1). This difference points to groundwater as the source of the NO3� observed in streams. Furthermore, the evidence indicates a differential impact of N deposition on terrestrial and aquatic systems in Mediterranean climates, with aquatic systems being impacted more quickly. The primary reason for this difference involves the asynchrony between the time that atmospheric deposition occurs (summer), the time period of maximum soil NO3� availability and leaching (winter), and the time of maximum plant N demand (spring). Our results indicate that semiarid Mediterranean climate systems behave differently from more humid systems in that, because of this asynchrony, aquatic systems may not be indicative of changes in terrestrial ecosystem response. These differences lead us to the conclusion that the extrapolation of impacts from humid to Mediterranean climates is problematic and the concept of N saturation may need to be revisited for semiarid and seasonally dry systems.
Global Pollution of Surface Waters from Point and Nonpoint Sources of Nitrogen
Authors: van Drecht G. , Bouwman A.F. , Knoop J.M. , Meinardi C. , Beusen A.
Published: March 2005

Global 0.5- by 0.5-degree resolution estimates are presented on the fate of nitrogen (N) stemming from point and nonpoint sources, including plant uptake, denitrification, leaching from the rooting zone, rapid flow through shallow groundwater, and slow flow through deep groundwater to riverine systems. Historical N inputs are used to describe the N flows in groundwater. For nonpoint N sources (agricultural and natural ecosystems), calculations are based on local hydrology, climate, geology, soils, climate and land use combined with data for 1995 on crop production, N inputs from N fertilizers and animal manure, and estimates for ammonia emissions, biological N fixation, and N deposition. For point sources, our estimates are based on population densities and human N emissions, sanitation, and treatment. The results provide a first insight into the magnitude of the N losses from soil-plant systems and point sources in various parts of the world, and the fate of N during transport in atmosphere, groundwater, and surface water. The contribution to the river N load by anthropogenic N pollution is dominant in many river basins in Europe, Asia, and North Africa. Our model results explain much of the variation in measured N export from different world river basins.
Regeneration of Mature Norway Spruce Stands: Early Effects of Selective Cutting and Clear Cutting on Seepage Water Quality and Soil Fertility
Authors: Weis Wendelin , Huber Christian , Gattlein Axel
Published: March 2005

The cutting of trees influences element turnover in the forest ecosystem. The reduction of plant uptake, as well as an increased mineralization and nitrification due to higher soil temperature and soil moisture, can lead to considerable losses of nutrients from the main rooting zone. This may result in a reduced soil fertility and a decrease in drinking water quality due to high nitrate concentrations in the seepage water. In Bavaria (Germany) selective cutting is preferred to clear cutting when initiating the regeneration of Norway spruce stands with European beech. This paper summarizes the early effects of both forest management practices on soil fertility and seepage water quality for three different sites. Shown are the concentrations of nitrogen and base cations in the seepage water as well as the water and ion fluxes during the first year after tree cut. Nutrient inputs decreased on thinned plots and even more at clear-cuts. Nitrate concentrations in the seepage water are hardly affected by moderate thinning; however, on clear-cuts, the nitrate concentration increases significantly, and base cations are lost from the upper mineral soil. This effect is less obvious at sites where a dense ground vegetation, which is able to take up excess nitrogen, exists.
Prevention and Control of Losses of Gaseous Nitrogen Compounds in Livestock Operations: A Review
Authors: Jongebreur A.A. , Monteny G.J.
Published: March 2005

Nitrogen (N) losses from livestock houses and manure storage facilities contribute greatly to the total loss of N from livestock farms. Volatilisation of ammonia (NH3) is the major process responsible for the loss of N in husbandry systems with slurry (where average dry matter content varies between 3 and 13%). Concerning this volatilisation of NH3, the process parameters of pH and air temperature are crucial. During a period of approximately 10 years, systematic measurements of NH3losses originating from a large variety of different livestock houses were made. One of the problems with NH3emissions is the large variation in the measured data due to the season, the production of the animals, the manure treatment, type of livestock house, and the manure storage. Generally speaking, prevention and control of NH3emission can be done by control of N content in the manure, moisture content, pH, and temperature[1]. In houses for growing pigs, a combination of simple housing measures can be taken to greatly reduce NH33 emissions[2]. In houses for laying hens, the control of the manure drying process determines the emission of NH3[1]. Monteny[3] has built an NH3production model with separate modules for the emission of the manure storage under the dairy house and the floor in the house. Manure spreading is also a major source of NH3emission and is dependent on slurry composition, environmental conditions, and farm management. The effects of these factors have been employed in a model[4]. Losses via NO, N2O, and N2are important in husbandry systems with solid manure and straw. The number of experimental data is, however, very limited. As N2O is an intermediate product of complex biochemical processes of nitrification and denitrification, optimal conditions are the key issues in N2O reduction strategies. We may expect that in the near future the emission of greenhouse gases will get the same attention from policy makers as NH3. Sustainable livestock production has to combine low emissions of gaseous N compounds with acceptable odour emissions, low emissions of greenhouse gases, and acceptable standards of animal welfare. For the entrepreneur, the strategy must be built on the regulations, the special conditions of his farm, and what is reasonably achievable.
Sampling Ozone Exposure of Canadian Forests at Different Scales: Some Case Studies
Authors: Cox R.M. , Malcolm J.W. , Hughes R.N. , Williams T.P.W.
Published: March 2005

The use of passive samplers in extensive monitoring, such as that used in national forest health monitoring plots, indicates that these devices are able to determine both spatial and temporal differences in ozone exposure of the plots. This allows for categorisation of the plots and the potential for cause-effect analysis of certain forest health responses. Forest exposure along a gradient of air pollution deposition demonstrates large variation in accumulated exposures. The efficacy of using passive samplers for in situ monitoring of forest canopy exposure was also demonstrated. The sampler data produced weak relationships with ozone values from the nearest �continuous� monitor, even though data from colocated samplers showed strong relationships. This spatial variation and the apparent effect of elevation on ozone exposure demonstrate the importance of topography and tree canopy characteristics in plant exposure on a regional scale. In addition, passive sampling may identify the effects of local pollutant gases, such as NO, which may scavenge ozone locally only to increase the production of this secondary pollutant downwind, as atmospheric reactions redress the equilibrium between concentrations of this precursor and those of the generated ozone. The use of passive samplers at the stand level is able to resolve vertical profiles within the stand and edge effects that are important in exposure of understorey and ground flora. Recent case studies using passive samplers to determine forest exposure to ozone indicate a great potential for the development of spatial models on a regional, landscape, and stand level scale.
Synchronizing N Release from Organic Residues: Opportunities for Integrated Management of N
Authors: Singh U. , Giller K.E. , Palm C.A. , Ladha J.K. , Breman H.
Published: March 2005

In intensive cropping systems, mineral nitrogen (N) fertilizers represent the largest component of the N cycle because the indigenous N supply is not adequate. The requirement for mineral fertilizer may be reduced with the use of organic nutrient sources. A more realistic use of organic matter, particularly in sub-Saharan Africa due to limited amounts and availability, is the combined use of organic nutrient sources and mineral fertilizers. The beneficial effects of integrated use of inorganic fertilizers and organic manures on improved nutrient recoveries, soil moisture retention, cation exchange capacity, and erosion control have been reported. However, there are as many reports indicating negligible benefits or even disadvantages of combining nutrient sources on crop production. This is not surprising given the combination of organic residue sources, soils, climatic, crops, and management factors that influence nutrient dynamics. The most widely accepted function of organic materials is improving the nutrient availability to crops by supplying N. The key to both improving efficiency of N use and reducing N losses is synchronization of N supply from soil, biological N2 fixation, organic residues, and inorganic fertilizers with the crop N demand. Organic materials are not magic; N losses also result from their use. Controlling N release from organic sources depends on their nutrient content and quality, soil properties, and the environmental and management factors. This paper will synthesize the information generated from integrated nutrient management trials in sub-Saharan Africa and the Philippines. Management strategies based on an organic resources database and a dynamic soil-crop simulation model are used to identify organic sources as N fertilizers or soil amendments. The decision support tools are also used to attain optimum synchrony between release from organic sources and soils with crop N demand.
Nutritional Methods to Decrease N Losses from Open-Dirt Feedlots in Nebraska
Authors: Erickson Galen E. , Klopfenstein Terry J.
Published: March 2005

Nitrogen (N) losses from cattle feedlots are of concern due to loss of valuable N and enrichment of the atmospheric N pool. Nutritional methods to decrease such losses would have economic and environmental benefits. One method to decrease N losses is by increasing carbon (C) on the pen surface. The most cost effective method of decreasing N losses with C may be feeding diets lower in digestibility compared to adding C directly to pens. Therefore, three experiments evaluated feeding corn bran (which is less digestible than corn) as either 0, 15, or 30% of the diet. The 15- and 30%-bran diets increase organic matter (OM) excretion by approximately 0.5 and 1.0 kg per steer per day, respectively. Compared with no bran, feeding 15 and 30% decreased feed efficiency by 7.8 and 10.4%, respectively. Nutrient balance was assessed in two trials from October through May and in one trial from June to September. During the trials from October to May, N losses were decreased by 14.5 and 20.7% for the 15- and 30%-bran diets compared with no bran. Feeding 15 or 30% bran did not influence N losses in the experiment from June to September. Increasing the C:N ratio of manure prior to cleaning open-dirt feedlots had variable results depending on time of year.
Increasing N Retention in Coastal Plain Agricultural Watersheds
Authors: Staver Kenneth W.
Published: March 2005

Historically, N availability has limited agricultural production as well as primary production in coastal waters. Prior to the middle of the last century, N available for grain production generally was limited to that supplied by previous legume crops, released from soil organic matter, or returned to the soil in animal wastes. The development of infrastructure to produce relatively low-cost inorganic N fertilizers eliminated the need to focus management of the entire agricultural system on increasing soil N availability. Increased N availability has contributed to dramatic increases in agricultural production but also has led to increased losses of both N and C from agricultural systems. N losses from cropland have been linked to increased algal production in the Chesapeake Bay, with N loss from cropland estimated to be the primary N input to the Bay from Coastal Plain regions of the watershed. The decade-long effort to reduce these losses has focused on reducing agricultural N use, but this strategy has yet to yield apparent reductions in N loadings to Coastal Plain tributaries. Although nitrate leaching losses are often attributed to inefficient use of N inputs, soil nitrate data indicate that both corn and soybeans can utilize nearly all available soil nitrate during periods of active growth. However, both crops tend to stop utilizing nitrate before mineralization has ceased, resulting in a late season buildup of root zone nitrate levels and significant leaching losses even when no N was applied. Reducing nitrate losses due to the inherent N inefficiency of summer annual grain crops will require the addition of winter annual crops to rotations or changes in weed management approaches that result in plant N uptake capacity being more closely matched to soil microbial N processes.
To Trade or Not To Trade? Criteria for Applying Cap and Trade
Authors: Benkovic Stephanie , Kruger Joseph
Published: March 2005

The use of emissions trading (cap and trade) is gaining worldwide recognition as an extremely effective policy tool. The U.S. Sulfur Dioxide (SO2) Emissions Trading Program has achieved an unprecedented level of environmental protection in a cost-effective manner. The successful results of the program have led domestic and foreign governments to consider the application of cap and trade to address other air quality issues. Certain analyses are particularly important in determining whether or not cap and trade is an appropriate policy tool. This paper offers a set of questions that can be used as criteria for determining whether or not cap and trade is the preferred policy approach to an environmental problem.