Acid Buffering Capacity Research Articles

Extractives, acidity, buffering capacity, ash and inorganic elements of black locust wood and bark of different clones and origin

Chemical properties of black locust wood and bark from Greece, Bulgaria and Hungary (clones NY, U and J) were investigated. Disks at breast height were taken from 25 black locust trees (five trees per origin and clone) and were divided into separate biomass components (juvenile heartwood, mature heartwood, sapwood and bark). Hot water soluble (HWSE) and dichloromethane soluble extractives (DSE), acidity (pH), buffering capacity, ash content and inorganic elements were determined according to standard laboratory techniques. Bark had the highest extractive content for both HWSE (9.25–13.49%) and DSE (3.09–4.03%). Differences of extractive contents in wood were found to exist between trees of different origin and between the three clones and ranged in heartwood between 5.04–10.10% for HWSE and 0.53–1.83% for DSE and in sapwood between 3.33–6.76% for HWSE and 0.48–1.47% for DSE. The higher values of pH occurred in sapwood (4.92–5.35), while the differences between bark (4.44–5.12) and heartwood (4.35–4.92) were small. Acid (ABC) and base (BBC) buffering capacities from the initial to pH 10 for ABC and to pH 3 for BBC were greater in bark (ABC 0.0172–0.0219 ml/ml and BBC 0.0079–0.0141 ml/ml) than in the other wood components (for heartwood ABC 0.0069–0.0159 ml/ml and BBC 0.0022–0.0096 ml/ml and for sapwood ABC 0.00330.0066 ml/ml and BBC 0.00330.0049 ml/ml). The total ash content was greater in bark (7.24–8.56%) than in other biomass components (for heartwood 0.34–0.89% and for sapwood 0.72–1.24%). The content of the main inorganic elements (Ca, K, Mg, Na, P) were also found to be much higher in bark while sapwood values were greater than heartwood.

DEVELOPMENT OF MUSCLE DIVING PHYSIOLOGY IN MARINE MAMMALS

Pinniped muscle development tracks life history such that species with short maternal dependency periods attain greater proportions of adult myoglobin levels earlier in life than species with protracted dependency periods. To determine if a similar pattern exists for mammals that develop at sea, the development of muscle myoglobin and acid buffering capacity due to non‐bicarbonate buffers was measured in the longissimus dorsi of harbor porpoise (Phocoena phocoena) and compared to data from bottlenose dolphins (Tursiops truncatus). The life history patterns of these species differ, with weaning occurring at 1 and 2.5–5 year(s) postpartum for porpoise and dolphins, respectively. Similar to dolphins, porpoise calves (n = 3) had significantly lower myoglobin content (0.8 ± 0.1 g myoglobin/100 g wet muscle mass) and acid buffering capacity (52.5 ± 0.1 slykes) than adult (n = 4) conspecifics (myoglobin: t = 4.9, P = 0.005; acid buffering capacity: t = 3.8, P = 0.013). However, the level of muscle maturity in porpoise and dolphin calves that were proportionally the same relative to adult length (50%) varied. Porpoise calves had 33% and 72% of mature myoglobin content and acid buffering capacity, respectively compared to only 10% and 65%, respectively for dolphin calves. Like pinnipeds, interspecific differences in muscle maturation in cetaceans track maternal dependency periods. Funded by NOAA NWFSC.

Effect of Weak Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions

AbstractElectrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90°C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric acids.Results show that the CR of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and Picric acids showed a slightly higher CR, and Acetic acid maintained the CR of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions.Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

A whey-predominant formula induces fecal microbiota similar to that found in breast-fed infants

To compare the effects of a whey-predominant infant formula and breast milk on the gut microbiota, growth, and tolerance of infants, we conducted an open, prospective, parallel-group study in healthy newborn infants. A total of 60 infants were enrolled, and 55 completed the study. Of the 55 infants, 21 were breast-fed and 34 were fed a whey-predominant study formula that had low phosphate concentration (31 mg/100 kcal), was reduced in protein (1.8 g/100 kcal or 0.43 g/kJ), had lactose as the sole carbohydrate source, and had an amino acid profile and buffering capacity similar to that of human milk. At 30 and 60 days of age, fecal bacterial counts were determined using fluorescence in situ hybridization and culture plating, and growth and digestive tolerance were evaluated. There were no differences in fecal bacterial counts between formula-fed and breast-fed infants at either 30 or 60 days. Fecal counts of bifidobacteria, lactobacilli, clostridia, enterococci, and Enterobacteriacea were similar in the 2 groups using both bacterial enumeration methods. Growth and digestive tolerance were also similar in the 2 groups. Thus, this whey-predominant infant formula is safe and well tolerated, and it affects infants' microbiota in a similar manner as observed with breast milk.

Measurement of wood and bark particles acidity and their impact on the curing of urea formaldehyde resin during the hot pressing of mixed panels

In the manufacture of panels, pH value is an important property to measure, especially when a pH-dependent resin like urea-formaldehyde (UF) is used. It has been proven that UF cures very well and faster in an acidic environment. In this study the acidity (pH value and buffering capacity) of both outer and inner white birch bark particles as well as that of wood particles or fibres used together with those barks as reinforcement for the manufacture of three layers particleboards was measured. The results show a significant difference between the acidity of white birch bark and wood. Barks have a lower pH as well as higher acid and alkaline buffering capacities. It was also found that the pH value of inner white birch bark is lower than that of the outer part. The significant differences observed enabled to realize that inner bark should be separated from outer bark and used separately in mixed panels manufacture. The platen temperature should be reduced when the outer bark is used in the surface of mixed panels to avoid pre-cure or over-cure. This study confirms the linear relationship between the pH and the absolute and relative buffering capacities.

Sensitivity to Acidification of Forest Soils in Two Watersheds with Contrasting Hydrological Regimes in the Oil Sands Region of Alberta

Input of large amounts of N and S compounds into forest ecosystems through atmospheric deposition is a significant risk for soil acidification in the oil sands region of Alberta. We evaluated the sensitivity of forest soils to acidification in two watersheds (Lake 287 and Lake 185) with contrasting hydrological regimes as a part of a larger project assessing the role of N and S cycling in soil acidification in forest ecosystems. Fifty six forest soil samples were collected from the two watersheds by horizon from 10 monitoring plots dominated by either jack pine ( Pinus banksiana) or aspen ( Populus tremuloides). Soils in the two watersheds were extremely to moderately acidic with pH (CaCl 2) ranging from 2.83 to 4.91. Soil acid-base chemistry variables such as pH, base saturation, Al saturation, and acid-buffering capacity measured using the acetic acid equilibrium procedure indicated that soils in Lake 287 were more acidified than those in Lake 185. Acid-buffering capacity decreased in the order of forest floor > subsurface mineral soil > surface mineral soil. The most dramatic differences in percent Ca and Al saturations between the two watersheds were found in the surface mineral soil horizon. Percent Ca and Al saturation in the surface mineral soil in Lake 287 were 15% and 70%, respectively; the percent Ca saturation value fell within a critical range proposed in the literature that indicates soil acidification. Our results suggest that the soils in the two watersheds have low acid buffering capacity and would be sensitive to increased acidic deposition in the region.

Tropical Soils–Acid Mine Drainage Interactions: Breakthrough Curves and Some Transport Parameters

The interactions between acid mine drainage (AMD) and three tropical clayey soils have been studied through hydraulic conductivity and batch sorption/dissolution testing. After 19–24 pore volumes of AMD flow through the soils, the measured final hydraulic conductivity ranged between 1.1× 10−11 and 3.3× 10−11 m∕s . The pH, electrical conductivity, and solute breakthrough curves obtained suggested the soils had low acid-buffering capacities. Also, several chemical species were released from the soils due to AMD attack of soil grains and mineral. The batch tests revealed high dissolution of species such as sodium, cobalt, and sulfate from the soils by AMD. The results also indicated dissolution of metals from soil constituents, desorption of chemical species, and transformation and dissolution of soil minerals due to AMD attack. The results of the study showed that, in general, the soils were not effective in attenuating contaminants present in the AMD. Thus, they may not be used alone to construct liners fo...

Immobilization of lead in shooting range soils by means of cement, quicklime, and phosphate amendments

Lead (Pb) contamination at shooting range sites is increasingly under environmental concern. Controlling Pb leachability from shooting range soil media is an important step to minimize Pb exposure to the surrounding environment. This study investigated stabilization of Pb in shooting range soils treated with cement, quicklime, and phosphate. Two soils were used and collected from two shooting ranges, referred to as SR1 and SR2. The treatment additives were applied to the soils at rates from 2.5% to 10% (w/w). The effectiveness of each treatment was evaluated by Pb (w/w). The effectiveness of each treatment was evaluated by Pb leachability, measured by the Toxicity Characteristic Leaching Procedure (TCLP). The possible mechanisms for Pb immobilization were elucidated using X-ray powder diffraction (XRPD). Cement and quicklime treatments were effective in immobilizing Pb in SR1 soil, with reduction of Pb concentration in TCLP leachate (TCLP-Pb) to be below the U.S. EPA non-hazardous regulatory limit of 5 mg L(-1) at application rates of > or =5% and 28-d incubation. By contrast, cement and quicklime amendments were less effective for Pb stabilization in SR2 soil because the TCLP-Pb levels in the treated soil were still higher than the limit of 5 mg L(-1) at all application rates, although they were significantly reduced in comparison with the untreated soil. Phosphate application was most effective in reducing Pb leach ing in both soils. Even at an application rate as low as 5% and 1-d incubation, phosphate could reduce TCLP-Pb to be below the limit of 5 mg L(-1) in both soils. Immobilization of Pb in the SR1 soil amended with cement and quicklime was attributed to the formation of pozzolanic minerals (e.g., calcium silicate hydrate C-S-H and ettringite) that could encapsulate soil Pb. The pozzolanic reaction was limited in the SR2 soil upon the application of cement and quicklime. Reduction of the TCLP-Pb might result from complexation of Pb on the surface of the formed calcite. Phosphate-induced Pb immobilization was mainly attributed to formation of less soluble PbHPO4. The results indicate that effectiveness of cementitious treatments (cement and quicklime) in immobilizing Pb varies in two soils, being effective in SR1 soil but less in SR2 soil. For one given soil, no difference was observed of the effeciveness between cement and quicklime treatments, whereas phosphate amendment emerges as a most effective treatment means for stabilizing Pb in both two soils, and it also shows a faster immobilization process and little effect on the soil acid buffering capacity. Recommendations and Perspectives. Overall, our study reveals that immobilizing Pb can be one of the best management practices for Pb contamination at shooting range sites. Phosphate amendment is most effective in immobilizing Pb in any kind of the soil ranges to minimize negative Pb impacts on the shooting range sites.

Preliminary Study on Evaluation of Effects of Acid Deposition on Forested Ecosystem in East Tanzawa Mountains Estimated from Chemical Characteristics of Stream Waters

It has been reported that the nitrate concentration in stream water in the mountainside on Mt. Oyama (1252 m a.s.l), which is located at the western part of Kanagawa Prefecture, is higher than that in stream water in other regions, indicating that nitrogen saturation is occurring in the forested ecosystem. However, there has been no report on nitrogen saturation across the Tanzawa mountains, except Mt. Oyama. We investigated the current status of the stream water chemistry and the effect of acid deposition on the stream water chemistry across the East Tanzawa mountains. Thirty-eight samples were collected in nine mountain streams in this region. The mean pH and alkalinity in stream water in this region were 7.315 and 650 μeq/L, respectively. There was no symptom of stream-water acidification by acid deposition in East Tanzawa, probably because of the high acid buffering capacity by the weathering of carbonate and silicate minerals. Nitrate concentrations in the stream water ranged from 27.6 to 87.8 μeq/L and NH4+ was detected. High nitrate concentration in stream water suggests that nitrogen saturation is occurring in the forested ecosystem in East Tanzawa mountains. We divided our sampling sites into southeast (SE), southwest (SW), and north (N) regions by the ridge line of Mt. Tanzawa - Mt. Tonodake - Shindainichi - Mt. Sannoto - Mt. Takenodai - Mt. Oyama - Mt. Mitsumine. The stream water pH was lower and the concentrations of Na+ and NO3− were higher in south regions. There were high correlations between the concentrations of Na+ (r = −0.854), Cl− (r = −0.815) and NO3− (r = −0.922) and the distance from the coast of Odawara City, Oisomachi, and Ninomiyamachi. In addition, a high correlation between the NO3− and Cl− concentrations (r = 0.741), which is an indicator of atmospheric deposition, in stream water was observed. Our preliminary investigation indicates that the runoff of nitrate, originated from atmospheric deposition, might occur in the forested ecosystem in the southern regions in East Tanzawa.

On the Acid−Base Properties of Humic Acid in Soil

Humic acid was isolated from three contrasting organic-rich soils and acid-base titrations performed over a range of ionic strengths. Results obtained were unlike most humic acid data sets; they showed a greater ionic strength dependency at low pH than at high pH. Forward- and back-titrations with the base and acid revealed hysteresis, particularly at low pH. Previous authors attributed this type of hysteresis to humic acid aggregates-created during the isolation procedure-being redissolved during titration as the pH increased and regarded the results as artificial. However, forward- and back-titrations with organic-rich soils also demonstrated a similar hysteretic behavior. These observations indicate (i) that titrations of humic acid in aggregated form (as opposed to the more usual dissolved form) are more representative of the acid-base properties of humic acid in soil and (ii) that the ionic strength dependency of proton binding in humic acid is related to its degree of aggregation. Thus, the current use of models based on data from dissolved humic substances to predictthe acid-base properties of humic acid in soil under environmental conditions may be flawed and could substantially overestimate their acid buffering capacity.

Rain acid buffer capacities of alpine forest soils in central Taiwan

The subtropical alpine forest ecosystem is vulnerable to acid rain deposited through the forest soils. Soil pH buffer capacity is a common index and plays an important role in buffering acidification. In this study, the pH buffer capacity of forest soils along an elevation sequence in central Taiwan was investigated and evaluated through conventional titration and mathematical calculation of proton affinity methods. High pH, cation exchangeable capacity, base saturation were observed in the low elevation site. Three phases of pH buffer capacity (pHBC) were proposed and well described the titration curve through linear fitting. The pHBCs showed no significant differences from the titration curves of various pedons and horizons. However, mathematical calculation of proton affinity potentials showed the highest correlation at the lower elevation site with soil pH ( r = 0.90 ⁎⁎), cation exchangeable capacity (CEC) ( r = 0.91 ⁎⁎), base saturation ( r = 0.97 ⁎⁎), and X-ray non-crystalline sesquioxides ( r = 0.68 ⁎⁎). It is important to evaluate the alpine forest soil pH buffer capacity by combining its proton consumption potentials.

Effects of vegetation history on distribution of Al in surface soils of suburban forests in Aichi Prefecture, Japan

This study examined the distribution of water-extractable Al in soils from forest sites near Nagoya in Aichi Prefecture. The mean concentrations of water-extractable Al in surface soils varied markedly among sites, with the values at site FGB (126mg/kg) higher than those at sites FG (11.8mg/kg) and FCB (33.8mg/kg). Comparisons of the acid buffer capacity of vegetation at the sites revealed that forest cover has a higher capacity for neutralization than the denuded state. We found that the effects of acidic accumulation in the surface soils of suburban forests might depend on vegetation history, and that forest soils that once had no vegetation cover accumulated labile Al due to acidification. The phenomenon was particularly distinct on granite bedrock.

Study on acidity and acidic buffering capacity of particulate matter over Chinese eastern coastal areas in spring

The analytical results of the acidity and buffering capacity of particulate matter sampled by aircraft over Chinese eastern coastal areas in March and early April 2002 are presented. The flight region covered the coastal areas from Zhuhai, Guangdong province, to Dalian, Liaoning province, and the northeastern coastal areas around Dalian, Liaoning province, with the later being the key flight areas. The results show that total suspended particles (TSP) generally appear to be acidic, having no buffering capacity for acidification; the acidity of TSP in northern areas is lower than that in southern areas, whereas the acidity of TSP in the bordering region of the northern areas and the southern areas is relatively high, the discrimination of the acidity of TSP in different areas could be up to more than 100 times. The acidity of particulate matter increases as its diameter decreases, indicating that fine particles have strong acidity. Both in northern areas and in southern areas, particulate matter with diameters larger than 11 μm has acidic buffering capacity, but particulate matter with diameters smaller than 2.1 μm appears to be acidic, having no buffering capacity. Although the pollution level of particulate matter at high altitudes is lower, its acidification is stronger than that at ground level. The regional acidification of particulate matter at high altitudes is an important reason why some areas in China suffer acidic precipitation.

Electrokinetic Remediation of Contaminated Dredged Sediment

Abstract This paper investigates the feasibility of electrokinetic remediation of contaminated sediment at Indiana Harbor, Indiana. The sediment is a fine-grained material with high moisture content of 78 % and high organic content of 19 % and it is contaminated with a wide range of polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Four bench-scale electrokinetic experiments were conducted at 2.0 VDC/cm of constant voltage gradient using two surfactants (5 % Igepal CA-720 and 3 % Tween 80), a cosolvent (20 % n-butylamine), and a cyclodextrin (10 % HP-β-CD) as flushing solutions for the solubilization/desorption of PAHs. The mobility and removal of heavy metals was also investigated while flushing these solutions. The experimental results show that 20 % n-butylamine and 5 % Igepal 720 systems are effective for the partial solubilization of the PAHs in the sediments; however, both 3 % Tween 80 and 10 % HP-β-CD systems are found to be ineffective for desorption/solubilization of PAHs in the sediment. None of the selected flushing agents is found to be effective for the removal of heavy metals from the contaminated sediment. The low removal of PAHs and heavy metals is attributed to the high organic content and high acid buffering capacity of the sediment.

Buffering effects of plaque solid, Streptococcus mutans and glucans

To investigate the buffer capacity of insoluble plaque mass including bacteria and glucans matrix. Plaque samples (starved or incubated 1 h with 10% sucrose), Streptococcus mutans (S. mutans) mass, and insoluble/soluble glucans were titrated with 1 mmol/L HCl. Meanwhile, the density of bacteria was counted and related to buffer capacity. The bacteria density had significant effects on acid buffer capacity in dental plaque, but the effect reduced with consuming sugar. S. mutans mass with no sucrose incubating contributed to the buffer capacity of (0.609 +/- 0.202) mmol/L, and S. mutans mass with 2% sucrose had only the buffer capacity of (0.099 +/- 0.047) mmol/L. In the mean time, glucans had no effect on acid buffering (0.028 - 0.032 mmol/L). The bacteria including S. mutans may be the main contributor to acid buffering in plaque solid.

Experiences with liming in European countries - results of long-term experiments

Liming was and still is carried out in many European forests since the beginning of the 1980s. Main objectives of compensation liming is to neutralize actual acidic deposition in order to prevent further soil acidification, to increase base saturation and acid buffering capacity of the soil. This paper evaluates results from long-term liming experiments throughout Europe using different amounts and forms of liming materials. Differences in forest ecosystem reaction to liming can be caused by amount, form and frequency of the application, and by the solubility, reaction kinetics, contents and composition of the material used. Furthermore, other factors like climate, site history, management, environmental conditions (e.g. actual and historical deposition rates), humus form, C/N ratio, nitrogen stores, and the soil chemical properties (e.g. pH, base saturation, CEC) may strongly influence the effects of liming treatments. Element budgets of forested ecosystems on a plot or watershed scale provide a very useful tool to integrate the various effects of additional Mg inputs via liming/fertilization.

Effect of soil chemical properties on the remediation of phenanthrene-contaminated soil by electrokinetic-Fenton process

The electrokinetic-Fenton (EK-Fenton) remediation of soil contaminated with phenanthrene was studied. Two different soils were chosen to investigate the effects of chemical properties, such as Fe oxide contents and acid soil buffer capacity. The H 2O 2 concentrations in pore water, the electrical potential distributions and the electrical currents were monitored to assess the electrochemical effect in relation to the soil properties. Hadong caly had high acid buffer capacity, and thus the amount of electroosmotic flow was lager in the experiment with Hadong clay than with EPK kaolin. The major mechanism of phenanthrene removal was a degradation in the experiment with EPK Kaolin, while it was a simple transport away from the system in experiment with Hadong clay. It was mainly because of the lower acid buffering capacity and better H 2O 2 stability in case with EPK Kaolin than with Hadong clay.

An evaluation of acid deposition on cation leaching and weathering rates of an Andosol and a Cambisol

An evaluation of the response of an Andosol and a Cambisol to acid deposition and weathering rates was studied by using a controlled laboratory leaching experiment. Both soils where derived from mafic parent material, a Histic Andosol from Western Iceland and a Cambisol from North East Scotland. De-ionized water and water acidified with H 2SO 4 (pH 3) was leached through reconstructed soil columns to simulate 34 years of precipitation. Acidic input increased cation leaching and weathering rates in both soil types and reduced pH levels. The Andosol proved generally to have higher weathering rates, leaching potential, ion exchange and acid-buffering capacity as well as maintaining a relatively steady pH despite intense acidic input. This was due to differences in parent material and mineral composition. The Andosol was developed from basaltic volcanic tephra, which had higher dissolution rates due to its amorphous mineral structures. The Cambisol was developed from gabbro with more stable mineral structures.

Lacustrine Fossil Preservation in Acidic Environments: Implications of Experimental and Field Studies for the Cretaceous–Paleogene Boundary Acid Rain Trauma

Abstract The effects of acidification on the preservation of buried lacustrine microfossils were evaluated using experimental tanks to simulate pH, depth, duration of acidification, and buffering conditions below the sediment/water interface of a hypothetical acidified lake. The taphonomic data provided from these experiments suggest that buffering by the host catchment (i.e., the CaCO3 content of the soils and outcrops that underlie the lake and drainage basin) is the primary factor promoting calcareous-fossil preservation under conditions of moderate and severe acidification. Global acid-rain fallout was a likely environmental consequence of the Chicxulub impact event at the Cretaceous– Paleogene boundary, and may have been important at other times in Earth history. Fossil preservation at the K/Pg boundary may have been affected by acidic groundwater leaching. Whereas the duration and intensity of the acid-rain fallout is poorly constrained, acid rain would have had varying effects on the acidity of lacustrine and fluvial environments with different acid-buffering capacities. Variations in acid-buffering capacities of lacustrine and fluvial catchments also may be a factor in the apparent extinction selectivity of non-marine aquatic fauna at the K/Pg boundary. Last appearances of taxa can result from poor preservation conditions or extinction—both of which may result from acidification. Last appearances observed at the species level, but not in higher taxa, may be the result of regional heterogeneities in catchment geology. Understanding local buffering conditions may be important for interpreting the continental fossil record at the K/Pg boundary.

Differentiating dilution and retention processes in mine effluent remediation within a natural wetland on the Zambian Copperbelt

The use of wetlands to treat mine effluent has grown in popularity over the past two decades, although the processes by which the natural systems function are often poorly understood. This field-scale investigation utilises daily data over a 9-month period in assessing the processes leading to the remediation of mine effluent within a natural wetland on the Zambian Copperbelt. The study differentiates effluent remediation through dilution from pollutant retention. Decreased wetland outflow concentrations of SO 4 and Na are due to dilution only, while Co (50%) and especially Cu (83%) are retained within the wetland. Retention was linked to adsorption onto new or primed surfaces during an initial period of effluent release into the system and to processes related to pH buffering to 7.5. The wetland’s acid buffering capacity was largely the result of carbonate-rich groundwater discharge into the wetland. Although this buffering capacity likely shows little seasonal fluctuation (20–80 kmol/day), the impact of acidic effluent input on the wetland itself probably varies markedly between seasons, owing to the temporal and spatial characteristics of discharge from the catchment’s aquifers. Assessment of other natural wetlands in the region indicated that some (circa 15%) showed similar catchment size, hydrochemical and hydrogeological characteristics as those of the New Dam wetland, likely demonstrating a similar effluent remediation potential as that described here.