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PubMed1990

Determination of intracellular buffer values after metabolic inhibition by fluoride and nitrilotriacetic acid.

Non-bicarbonate buffer values have been analysed in homogenates of squid mantle muscle and toad gastrocnemius muscle using the PCO2 equilibration technique. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid. After an initial change in the concentration of organic phosphates a new metabolic equilibrium was achieved which was insensitive to pH changes during PCO2 variations. Inaccurate measurements of homogenate buffer values could, thereby, be prevented. The accumulation of inorganic phosphate during the initial metabolic shift caused an increase in homogenate buffer values. Levels of unbound inorganic phosphate, which are effective in buffering, were estimated by enzymatic analysis in homogenate ultrafiltrates. Based on the evaluation of apparent dissociation constants pK', and buffer values for fluoride and inorganic phosphate, the non-bicarbonate, non-phosphatei (i: inorganic) buffer value of the tissue was calculated. The level of free inorganic phosphate in the resting tissue was considered for an estimate of the intracellular non-bicarbonate buffer value under control conditions.

Adenosine Diphosphate↗
PubMed2004

Evaluation of buffer materials by associating engineering and sorption properties.

To provide an overall functional evaluation of buffer materials, this study attempted to investigate the relationships among the engineering properties, plastic index (PI), compaction efficiency, sorption properties, and distribution ratio (Rd) for some buffer materials composed of quartz sand and bentonite. Th and U were nuclides of interest, and both synthetic groundwater (GW) and seawater (SW) were used for batch sorption experiments, while the deionized water (DIW) was used for engineering property tests. SW and GW were also used to evaluate the effects on PI. The results show that the maximum dry density was reached when bentonite content was 30% with the same compaction energy by the ASTM D698 method. PI and bentonite content of tested buffer materials consisting of bentonite and quartz sand demonstrated a linearly proportional relationship regardless of the solution used. The following sequence of PIDIW > PIGW > PISW is due to coagulation and flocculation effects. The buffer materials of lower PI value could decrease swelling potential and increase permeability. The Rd observed in GW and SW of U increased linearly with PI measured in DIW, although the Rd of Th remained relatively constant above a PI of 88. From the viewpoints of associated engineering and sorption properties, the buffer materials containing 30-50% bentonite are probably the most favorable choice. Another result shows that U has a better additivity with respect to Rd than Th in both synthetic GW and synthetic SW. These results will allow a determination of more effective buffer material composition, and improved estimates of the overall Rd of the buffer material mixture from the Rd of each mineral component.

Journal Article↗
PubMed2000

Monte carlo simulation of 3-D buffered Ca(2+) diffusion in neuroendocrine cells.

Buffered Ca(2+) diffusion in the cytosol of neuroendocrine cells is a plausible explanation for the slowness and latency in the secretion of hormones. We have developed a Monte Carlo simulation to treat the problem of 3-D diffusion and kinetic reactions of ions and buffers. The 3-D diffusion is modeled as a random walk process that follows the path of each ion and buffer molecule, combined locally with a stochastic treatment of the first-order kinetic reactions involved. Such modeling is able to predict [Ca(2+)] and buffer concentration time courses regardless of how low the calcium influx is, and it is therefore a convenient method for dealing with physiological calcium currents and concentrations. We study the effects of the diffusional and kinetic parameters of the model on the concentration time courses as well as on the local equilibrium of buffers with calcium. An in-mobile and fast endogenous buffer as described by, Biophys. J. 72:674-690) was able to reach local equilibrium with calcium; however, the exogenous buffers considered are displaced drastically from equilibrium at the start of the calcium pulse, particularly below the pores. The versatility of the method also allows the effect of different arrangements of calcium channels on submembrane gradients to be studied, including random distribution of calcium channels and channel clusters. The simulation shows how the particular distribution of channels or clusters can be of relevance for secretion in the case where the distribution of release granules is correlated with the channels or clusters.

Animals↗
PubMed2001

The effects of exogenous calcium buffers on the systolic calcium transient in rat ventricular myocytes.

The aim of this work was to characterize the effects that two commonly used "caged" calcium buffers (NP-EGTA and nitr-5) have on the amplitude and time course of decay of the calcium transient. We made quantitative measurements of both free and total calcium using the measured buffering properties of the cell. Intracellular calcium concentration ([Ca(2+)](i)) was measured with fluo-3 in rat ventricular myocytes. Incorporation of the buffer NP-EGTA decreased both the amplitude and rate of decay of the caffeine response. The slowing could be quantitatively accounted for by the measured increased buffering. These effects were removed by photolysis of NP-EGTA. Similar results were obtained with nitr-5 except that the effects were not completely removed by photolysis. This was shown to be due to the persistence of a component of the increased buffering after photolysis. Both buffers decreased the amplitude of the systolic calcium transient. However, although nitr-5 produced a simple slowing of the decay, NP-EGTA resulted in an initial rapid phase of decay. This rapid phase of decay is attributed to calcium binding to NP-EGTA. This work represents the first quantitative analysis of the effects that extra buffering by a fast and a slow calcium chelator may have on the calcium transient.

Aniline Compounds↗
PubMed1992

Spatial buffering of extracellular potassium by Müller (glial) cells in the toad retina.

We examined the role of Müller (glial) cells in buffering light-evoked changes in extracellular K+ concentration, [K+]o, in the isolated retina of the toad, Bufo marinus. We found evidence for two opposing Müller cell current loops that are generated by a light-evoked increase in [K+]o in the inner plexiform layer. These current loops, which are involved in the generation of the M-wave of the electroretinogram (ERG), prevent the accumulation of K+ in the inner plexiform layer by transporting K+ both to vitreous and to distal retina. In addition, under dark-adapted conditions, we found evidence for a Müller cell current loop that is generated by a light-evoked decrease in [K+]o in the receptor layer. This current loop, which is involved in the generation of the slow PIII component of the ERG, helps to buffer the light-evoked decrease in [K+]o throughout distal retina by transporting K+ from vitreous. The spatial buffering fluxes of K+ can be abolished by blocking Müller cell K+ conductance with 200 microM Ba2+. The separate contributions of the M-wave and slow PIII currents to Müller cell spatial buffering were isolated by various pharmacological treatments that were designed to enhance or suppress light-evoked activity in specific retinal neurons. Our results show that Müller cell K+ currents not only buffer light-evoked increases in [K+]o, but also buffer light-evoked decreases in [K+]o, and thereby diminish any deleterious effects upon neuronal function that could arise in response to large changes in [K+]o in the plexiform layers. Moreover, our results emphasize that spatial buffering currents generate many components of the electroretinogram.

Animals↗
PubMed2006

Antiparasitic effect of calcium and magnesium ion-free buffer treatments against a common monogenean Neobenedenia girellae.

This study investigated a new effective method for controlling the capsalid monogenean Neobenedenia girellae. We examined in vitro and in vivo the effect on the percentage survival of N. girellae in buffers containing different metallic ions. Decreased survival was observed in buffer solutions lacking two ions. In particular, the percentage survival of N. girellae was significantly decreased after 10 min exposure to buffer containing neither Ca(2+) nor Mg(2+). Transmission electron microscopic observations showed that treatment with this buffer disrupted intercellular junctions. This significant effect on percentage survival of N. girellae using Ca(2+)/Mg(2+)-free buffer was confirmed in an in vivo assay. Ca(2+)/Mg(2+)-free buffer had no effect on the condition of the host, spotted halibut Verasper variegates (Pleuronectidae). These results suggest that treatment with Ca(2+)/Mg(2+)-free buffer is a new effective control method, which could replace existing control methods.

Animals↗
PubMed2005

Influence of amine buffers on carbon tetrachloride reductive dechlorination by the iron oxide magnetite.

The influence of amine buffers on carbon tetrachloride (CCl4) reductive dechlorination by the iron oxide magnetite (FeIIFeIII2O4) was examined in batch reactors. A baseline was provided by monitoring the reaction in a magnetite suspension containing NaCl as a background electrolyte at pH 8.9. The baseline reaction rate constant was measured at 7.1 x 10(-5)+/-6.3 x 10(-6) L m(-2) h(-1). Carbon monoxide (CO) was the dominant reaction product at 82% followed by chloroform (CHCl3) at 5.2%. In the presence of 0.01 M tris-(deuteroxymethyl)aminomethane (TRISd), the reaction rate constant nearly tripled to 2.1 x 10(-4)+/-6.5 x 10(-6) L m(-2) h(-1) but only increased the CHCl3 yield to 11% and did not cause any statistically significant changes to the CO yield. Reactions in the presence of triethylammonium (TEAd) (0.01 M) increased the rate constant by 17% to 8.6 x 10(-5)+/-8.1 x 10(-6) L m(-2) h(-1) but only increased the CHCl3 yield to 8.8% while leaving the CO yield unchanged. The same concentration of N,N,N',N'-tetraethylethylenediamine (TEEN) increased the reaction rate constant by 18% to 8.7 x 10(-5)+/-4.8 x 10(-6) L m(-2) h(-1) but enhanced the CHCl3 yield to 34% at the expense of the CO yield that dropped to 35%. Previous work has shown that CHCl3 can be generated either through hydrogen abstraction by a trichloromethyl radical (radical CCl3), or through proton abstraction by the trichlorocarbanion (-:CCl3). These two possible hydrogenolysis pathways were examined in the presence of deuterated buffers. Deuterium tracking experiments revealed that proton abstraction by the trichlorocarbanion was the dominant hydrogenolysis mechanism in the magnetite-buffered TRISd and TEAd systems. The only buffer that had minimal influence on both the reaction rate and product distribution was TEAd. These results indicate that buffers should be prescreened and demonstrated to have minimal impact on reaction rates and product distributions prior to use. Alternatively, it may be preferable, to utilize the buffer capacity of the solids to avoid organic buffer interactions entirely.

Amines↗
PubMed2005

Hydroxyzine- and cetirizine-loaded liposomes: effect of duration of thin film hydration, freeze-thawing, and changing buffer pH on encapsulation and stability.

PURPOSE: To assess the effect of the duration of film hydration, freeze-thawing, and changing buffer pH on the extent of entrapment of hydroxyzine and cetirizine, H1-antihistamines with different polarity, into liposomes, and the stability of these liposomes. METHODS: Multilamellar vesicles (MLV) were prepared by thin-lipid film hydration using L-alpha-phosphatidylcholine (PC) and buffer containing 80 mg hydroxyzine at pH 7. For MLV containing hydroxyzine, the liposomes were subjected to 1) hydration for 1 h, 24 h, or 48 h for the control batch, batch B, or batch D respectively; and 2) hydration for 1 h, 24 h, or 48 h with freeze-thawing for 5-cycles for batch A, batch C, or batch E, respectively. These formulations were stored at 10 +/- 2 degrees C and 37 +/- 0.1 degrees C. Small unilamellar vesicles (SUV) and MLV were prepared using L-alpha-phosphatidylcholine (PC), and buffer at pH 5.0, 5.5, 6.0, 6.5, and 7.0, containing 80 mg hydroxyzine or 82 mg cetirizine by the ethanol injection and thin-lipid film hydration methods, respectively. These formulations were stored at 10 +/- 2 degrees C. Liposomes were evaluated immediately after preparation and after storage by determining percent entrapment of hydroxyzine (PETH) or of cetirizine (PEC) and by observing changes in the physical appearance (PA). Particle size (PSA) of the liposomes freshly prepared at pH=6.5 was measured from transmission electron micrographs (TEM). RESULTS: Increasing thin-film hydration time or repeated freeze-thawing did not affect the initial PETH or long-term stability of control, A, B, C, D, and E batches of MLV containing hydroxyzine stored at 10 +/- 2 degrees C. At 37 +/- 0.1 degrees C, PETH of all MLV batches decreased considerably after 1 month. This was more evident in batches B, C, and E exposed to freeze-thawing. The PETH of SUV increased markedly from 53.0% to 84.0% when the pH of the buffer was increased from 5.0 to 5.5. As pH increased from 6.0 to 7.0, PETH continued to increase from 84% to 94%. The initial PETH of MLV increased slightly from 82.0% to 94.0% as the buffer pH values increased from 5.0 to 7.0. There was no effect of pH on initial PEC, and stability of SUV or initial PEC of MLV, which ranged from 92% to 94%, as buffer pH values increased from 5.0 to 6.5. After storage at 10 +/- 2 degrees C PEC in MLV decreased from 94% to 74%. CONCLUSIONS: The freeze-thawing processes had some effect on the stability of liposomes stored at temperatures higher than ambient temperature, 37 +/- 0.1 degrees C. The effect of changing the buffer pH from 5.5 to 7.0, and from 5.0 to 6.5 on initial PETH and PEC, respectively, was minimal. After 24 months at l0 +/- 2 degrees C, pH had no effects on PETH; however, PEC of MLV decreased.

Cetirizine↗
PubMed2006

Social buffering: relief from stress and anxiety.

Communication is essential to members of a society not only for the expression of personal information, but also for the protection from environmental threats. Highly social mammals have a distinct characteristic: when conspecific animals are together, they show a better recovery from experiences of distress. This phenomenon, termed 'social buffering', has been found in rodents, birds, non-human primates and also in humans. This paper reviews classical findings on social buffering and focuses, in particular, on social buffering effects in relation to neuroendocrine stress responses. The social cues that transmit social buffering signals, the neural mechanisms of social buffering and a partner's efficacy with respect to social buffering are also detailed. Social contact appears to have a very positive influence on the psychological and the physiological aspects of social animals, including human beings. Research leading towards further understanding of the mechanisms of social buffering could provide alternative medical treatments based on the natural, individual characteristics of social animals, which could improve the quality of life.

Animals↗
PubMed2005

Dynamic neural-based buffer management for Queuing systems with self-similar characteristics.

Buffer management in queuing systems plays an important role in addressing the tradeoff between efficiency measured in terms of overall packet loss and fairness measured in terms of individual source packet loss. Complete partitioning (CP) of a buffer with the best fairness characteristic and complete sharing (CS) of a buffer with the best efficiency characteristic are at the opposite ends of the spectrum of buffer management techniques. Dynamic partitioning buffer management techniques aim at addressing the tradeoff between efficiency and fairness. Ease of implementation is the key issue when determining the practicality of a dynamic buffer management technique. In this paper, two novel dynamic buffer management techniques for queuing systems accommodating self-similar traffic patterns are introduced. The techniques take advantage of the adaptive learning power of perceptron neural networks when applied to arriving traffic patterns of queuing systems. Relying on the water-filling approach, our proposed techniques are capable of coping with the tradeoff between packet loss and fairness issues. Computer simulations reveal that both of the proposed techniques enjoy great efficiency and fairness characteristics as well as ease of implementation.

Algorithms↗
PubMed1981

Tris(hydroxymethyl)aminomethane buffer modification of Escherichia coli outer membrane permeability.

The effect of tris(hydroxymethyl)aminomethane (Tris) buffer on outer membrane permeability was examined in a smooth strain (D280) and in a heptose-deficient lipopolysaccharide strain (F515) of Escherichia coli O8. Tris buffer (pH 8.00) was found to increase outer membrane permeability on the basis of an increased Vo of whole-cell alkaline phosphatase activity and on the basis of sensitivity to lysozyme and altered localization pattern of alkaline phosphatase. The Tris buffer-mediated increase in outer membrane permeability was found to be dependent upon the extent of exposure to and concentration of the Tris buffer. The Tris buffer effects were demonstrated not to be due to allosteric activation of cell-associated alkaline phosphatase and were specific for Tris buffer. Exposure of cells to Tris resulted in the release of a limited amount of cell envelope component. Investigators utilizing Tris buffer are cautioned that Tris is not physiologically inert and that it may interact with the system under investigation.

Cell Membrane Permeability↗
PubMed1992

Use of ionic and zwitterionic (Tris/BisTris and HEPES) buffers in studies on hemoglobin function.

The functional characteristics of hemoglobin (Hb) depend on oxygenation-linked proton and anion binding and thus on solvent buffer groups and ionic composition. This study compares the oxygenation properties of human Hb in ionic [tris(hydroxymethyl)aminomethane (Tris) and BisTris] buffers with those in zwitterionic N-2-hydroxy-ethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer under strictly controlled chloride concentrations at different pH values, two temperatures, and in the absence and presence of the erythrocytic cofactor, 2,3-diphosphoglycerate (DPG). In contrast to earlier studies (carried out at the same or different chloride concentrations) it shows only small buffer effects that are manifested at low chloride concentration and high pH. These observations suggest chloride binding to the Tris buffers, which reduces the interaction with specific chloride binding sites in the Hb. The findings indicate that HEPES allows for more accurate assessment of Hb-oxygen affinity and its anion and temperature sensitivities than ionic buffers and advocates standard use of HEPES in studies on Hb function. Precise oxygen affinities of Hb dissolved in both buffers are defined under standard conditions.

Binding Sites↗
PubMed1998

Increased calcium buffering in basal forebrain neurons during aging.

Increased calcium buffering in basal forebrain neurons during aging. J. Neurophysiol. 80: 350-364, 1998. Alterations of neuronal calcium (Ca2+) homeostasis are thought to underlie many age-related changes in the nervous system. Basal forebrain neurons are susceptible to changes associated with aging and to related dysfunctions such as Alzheimer's disease. It recently was shown that neurons from the medial septum and nucleus of the diagonal band (MS/nDB) of aged (24-27 mo) F344 rats have an increased current influx through voltage-gated Ca2+ channels (VGCCs) relative to those of young (1-4. 5 mo) rats. Possible age-related changes in Ca2+ buffering in these neurons have been investigated using conventional whole cell and perforated-patch voltage clamp combined with fura-2 microfluorimetric techniques. Basal intracellular Ca2+ concentrations ([Ca2+]i), Ca2+ influx, Ca2+ transients (Delta[Ca2+]i), and time course of Delta[Ca2+]i were quantitated, and rapid Ca2+ buffering values were calculated in MS/nDB neurons from young and aged rats. The involvement of the smooth endoplasmic reticulum (SER) was examined with the SER Ca2+ uptake blocker, thapsigargin. An age-related increase in rapid Ca2+ buffering and Delta[Ca2+]i time course was observed, although basal [Ca2+]i was unchanged with age. The SER and endogenous diffusible buffering mechanisms were found to have roles in Ca2+ buffering, but they did not mediate the age-related changes. These findings suggest a model in which some aging central neurons could compensate for increased Ca2+ influx with greater Ca2+ buffering.

Aging↗
PubMed2003

Baroreflex buffering is reduced with age in healthy men.

BACKGROUND: Baroreflex buffering is an important mechanism in arterial blood pressure control. The effect of healthy (physiological) aging on tonic baroreflex buffering in humans is unknown. METHODS AND RESULTS: Baroreflex buffering was determined in 27 young (aged 25+/-1 years) and 16 older (aged 65+/-1 years) healthy normotensive men by measuring the potentiation of the systolic blood pressure (SBP) responses to a phenylephrine bolus (BRBbolus) and incremental infusion (BRBslope) during compared with before ganglionic blockade with trimethaphan. The SBP responses to phenylephrine either were not different or greater in the older men before ganglionic blockade, but smaller during ganglionic blockade. BRBbolus (2.1+/-0.4 versus 5.1+/-0.7, P<0.001) and BRBslope (1.6+/-0.2 versus 3.5+/-0.4, P<0.0001) were approximately 115% smaller in the older men. Baroreflex buffering was not consistently related to mean levels or variability of blood pressure or heart rate, or to cardiovagal baroreflex sensitivity, but correlated with muscle sympathetic nerve activity (BRBbolus: r=-0.55, BRBslope: r=-0.69, P<0.005) and the SBP responses to phenylephrine during ganglionic blockade (BRBbolus: r=0.53; BRBslope: r=0.98, P<0.0001). BRBbolus was also inversely related to the SBP response to phenylephrine before ganglionic blockade (r=-0.78, P<0.0001). CONCLUSIONS: Physiological aging in men is associated with a marked reduction in baroreflex buffering. The decrease in baroreflex buffering with aging is related to increases in basal sympathetic nerve activity and reductions in systemic alpha1-adrenergic vascular responsiveness. These findings are helpful for interpreting changes in baroreflex buffering in older patients with cardiovascular disease, as well as changes in responsiveness to vasoactive drugs with aging.

Adult↗
PubMedDate not supplied

Sediment retention in rangeland riparian buffers.

Controlling nonpoint-source sediment pollution is a common goal of riparian management, but there is little quantitative information about factors affecting performance of rangeland riparian buffers. This study evaluated the influence of vegetation characteristics, buffer width, slope, and stubble height on sediment retention in a Montana foothills meadow. Three vegetation types (sedge wetland, rush transition, bunchgrass upland) were compared using twenty-six 6- x 2-m plots spanning 2 to 20% slopes. Plots were clipped moderately (10-15 cm stubble) or severely (2-5 cm stubble). Sediment (silt + fine sand) was added to simulated overland runoff 6, 2, or 1 m above the bottom of each plot. Runoff was sampled at 15-s to > 5-min intervals until sediment concentrations approached background levels. Sediment retention was affected strongly by buffer width and moderately by vegetation type and slope, but was not affected by stubble height. Mean sediment retention ranged from 63 to > 99% for different combinations of buffer width and vegetation type, with 94 to 99% retention in 6-m-wide buffers regardless of vegetation type or slope. Results suggest that rangeland riparian buffers should be at least 6 m wide, with dense vegetation, to be effective and reliable. Narrower widths, steep slopes, and sparse vegetation increase risk of sediment delivery to streams. Vegetation characteristics such as biomass, cover, or density are more appropriate than stubble height for judging capacity to remove sediment from overland runoff, though stubble height may indirectly indicate livestock impacts that can affect buffer performance.

Biodegradation, Environmental↗
PubMedDate not supplied

Nitrous oxide emission and denitrification in chronically nitrate-loaded riparian buffer zones.

Riparian buffer zones are known to reduce diffuse N pollution of streams by removing and modifying N from agricultural runoff. Denitrification, often identified as the key N removal process, is also considered as a major source of the greenhouse gas nitrous oxide (N2O). The risks of high N2O emissions during nitrate mitigation and the environmental controls of emissions have been examined in relatively few riparian zones and the interactions between controls and emissions are still poorly understood. Our objectives were to assess the rates of N2O emission from riparian buffer zones that receive large loads of nitrate, and to evaluate various factors that are purported to control N emissions. Denitrification, nitrification, and N2O emissions were measured seasonally in grassland and forested buffer zones along first-order streams in The Netherlands. Lateral nitrate loading rates were high, up to 470 g N m(-2) yr(-1). Nitrogen process rates were determined using flux chamber measurements and incubation experiments. Nitrous oxide emissions were found to be significantly higher in the forested (20 kg N ha(-1) yr(-1)) compared with the grassland buffer zone (2-4 kg N ha(-1) yr(-1)), whereas denitrification rates were not significantly different. Higher rates of N2O emissions in the forested buffer zone were associated with higher nitrate concentrations in the ground water. We conclude that N transformation by nitrate-loaded buffer zones results in a significant increase of greenhouse gas emission. Considerable N2O fluxes measured in this study indicate that Intergovernmental Panel on Climate Change methodologies for quantifying indirect N2O emissions have to distinguish between agricultural uplands and riparian buffer zones in landscapes receiving large N inputs.

Agriculture↗
PubMedDate not supplied

Efficacy of vegetated buffer strips for retaining Cryptosporidium parvum.

Overland and shallow subsurface hydrologic transport of pathogenic Cryptosporidium parvum oocysts 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 x 1.1 m long x 0.3 m deep) were used to evaluate the ability of grass vegetated buffer strips to retain 2 x 10(8) spiked C. parvum oocysts 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/cm(3)) 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 x 10(6) to 23.9 x 10(6) oocysts. Observed overall mean log(10) reduction of total C. parvum flux 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 log(10) reduction 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 waterborne C. parvum attributable to extensive cattle grazing on annual grassland watersheds.

Animals↗
PubMed2002

Effect of a cold-climate buffer zone on minimising diffuse pollution from agriculture.

Vegetative buffer zones adjacent to streams can filter diffuse pollution from agriculture. Under Nordic climatic conditions, major runoff from agriculture occurs during winter and especially during snowmelt. Field experiments documenting runoff and retention processes in buffer zones during winter conditions are essential. Agricultural runoff and buffer zone retention of nutrients and particles during winter and summer are compared. The study is based upon 8 years of data collected from 5 to 10 m wide buffer zones compared to plots without buffer zones. Volume proportional samples were collected after each runoff episode. Results show that the difference between precipitation and runoff is much higher during summer than winter, due to higher evapotranspiration and infiltration during the summer. Over 90% of total particle and phosphorus runoff occurred during winter. There was no significant difference in retention of particles and particle-bound nutrients during winter compared to summer. Sedimentation is one of the most important retention processes in surface runoff buffer zones. High retention during winter is probably caused by higher surface runoff and erosion. High surface runoff and flow velocity could cause erosion of coarser particles, which were more easily trapped in the buffer zone. High particle concentration in the runoff water may also enhance the aggregation of fine particles.

Agriculture↗