Precipitation pH Values Research Articles

Effect of acidic deposition on forested andisols in the Tama Hill region of Japan

Acid deposition and its effect on Andisols was investigated in the forest experimental station, the Rolling Land Laboratory, the Tama Hill region, central Japan. The annual volume-weighted mean pH value of open bulk precipitation was 4·8. The acidity of stemflow from coniferous trees was attributed to dry deposition of air pollutants. The acidic stemflow affected the chemical composition of the soil solution and the pH of soils around the coniferous trees. The concentration of aluminum in the soil solution was accompanied by nitrate which was provided by nitrification in the low soil pH range. The concentration of aluminum in the soil solution, which ranged from 0·02 to 0·12 mmol c liter −1 is similar to the critical levels for the roots of the trees. Andisols in the surface horizon are acidified due to the atmospheric acid deposition, even though seepage from the catchment is still neutral.

Concentration Changes of Acidic Ions in Winter Precipitation in Tohkamachi, Japan

Chemical studies of the winter precipitation were conducted in Tohkamachi city. The relationships between the chemical property of winter precipitation and the weather condition were studied.Samples of daily precipitation were collected in Tohkamachi during winter periods from December 24, 1990 to April 9, 1991, from December 17, 1991 to April 10, 1992 and from December 15, 1992 to April 10, 1993.The samples were filtered, and conductivity and pH were measured with a conductivity meter and pH meter, respectively. Anions and cations were determined by an ion chromatography (Dionex 2020 i/SP).The ratios of Cl-/Na+ and Mg2+/Na+ in all samples of winter precipitation are nearly equal to those in the sea water. This result suggests that the origin of Na+, Mg2+ and Cl- in the winter precipitation is sea water. The origin of NO3- and NH4+ in the winter precipitation is considered to be non sea salt. The origins of SO42- and Ca2+ are both sea water and non sea salt. NO3- and nssSO42- are the acidic materials and decline pH value of the winter precipitation. NH4+ and nssCa2+ are the neutralization materials of acid precipitation.Weighted average pH of precipitation is 4.46 for 1991 winter, 4.16 for 1992 winter and 4.22 for 1993 winter. pH values of all samples are less than 5.2. winter precipitation in Tohkamachi shows acidity, and pH of winter rain shows more acidic than that of solid precipitation.The synoptic weather conditions affect chemical properties of winter precipitation. Sea salt materials are dominated in the precipitation formed under the winter monsoon pressure pattern. On the other hand, non sea salt materials are dominated in precipitation formed by a low pressure systems on the Sea of Japan or on the Pacific Ocean. The larger ratio of acidic materials in precipitation indicates the stronger acidity of precipitation formed by a low pressure systems on the Pacific Ocean.

The recovery of the hepatitis B virus surface antigen (HBsAg) from a recombinant P. pastoris strain disruption and precipitation studies

AbstractCell disruption studies for the extraction of HBsAg from a recombinant P. pastoris strain (r‐HBsAg) were done using a bead mill disintegrator. Three sequential passages (4 min retention time each) were enough to disrupt the cells and extract most of the r‐HBsAg and soluble proteins. An acid precipitation step was performed just after cell disruption to precipitate proteins together with the cell debris. Different precipitation pH values (2.5 to 6.0) were investigated. A pH value of 4.2 was selected as a compromise between recovery and improvement of specific activity. A 6 to 8‐fold enhancement of the specific activity was obtained, having a r‐HBsAg overall yield of about 80%. The influencing presence of a chaotropic salt (potassium thiocyanate) during the acid precipitation step was also studied.

Chemical characteristics of snow in the region along the Sea of Japan

The amount of acidity in precipitation has been measured in heavy-snowfall regions facing the Sea of Japan. The average pH value of precipitation measured throughout the year at Nagaoka was 4.80 during 4.5 years, 1987–92. During winter the pH value is lower and electric conductivity higher. The spatial distribution of chemical components in new-fallen snow was studied along a 55 km-long sampling route. Results from four surveys showed that acidic snows have average pH values of 4.63–4.90. From the distribution of anion and cation concentration in new-fallen snow, it is concluded that strong northwest monsoons during winter bring an abundance of snow with salt components and many non-salt components from the Sea of Japan and also, possibly, from the Asian continent.

Chemical characteristics of snow in the region along the Sea of Japan

The amount of acidity in precipitation has been measured in heavy-snowfall regions facing the Sea of Japan. The average pH value of precipitation measured throughout the year at Nagaoka was 4.80 during 4.5 years, 1987–92. During winter the pH value is lower and electric conductivity higher. The spatial distribution of chemical components in new-fallen snow was studied along a 55 km-long sampling route. Results from four surveys showed that acidic snows have average pH values of 4.63–4.90. From the distribution of anion and cation concentration in new-fallen snow, it is concluded that strong northwest monsoons during winter bring an abundance of snow with salt components and many non-salt components from the Sea of Japan and also, possibly, from the Asian continent.

Rain and throughfall chemistry in a Norway spruce forest in the Western Prealps

From January 1987 to December 1989 precipitation was collected in an open field in a forested area of the Western Prealps. The site faces the intensely industrialized area of the Po Valley. In a Norway spruce plantation, next to the open field sampler, throughfall was collected from January 1987 to August 1989 for a period of 32 months. In the common sampling period median pH values of the open field precipitation and throughfall were 4·28 and 4·19 respectively. Open field precipitation has yearly deposition rates of acidity, Ca, S, and N of 0·81, 9·82, 24·83 and 32·81 kg/ha −1 respectively. The throughfall showed significant increases in the deposition rates for Ca, Mg, K, N and S, due to abundant dry deposition and, probably, to nutrient leaching contributed by the canopies of the spruce. On the basis of available data, an initial approach to atmospher— canopy interaction was made.

Tree pollen viability in areas subject to high pollutant deposition

The wet deposition process, including fog, is a major pathway of acidic pollutants from the atmosphere to the biosphere. Pollen grains are known to be sensitive biological indicators of pollution at this interface. In southern Quebec, pollen viability of three hardwood species (sugar maple, white and yellow birch), was significantly reduced above the mean cloud base height (≈600 m) for two successive years (1987–1988) at two mountain sites (Roundtop and Tremblant). Ozone concentrations, fog water and precipitation pH values over the sampling periods are discussed.

Preparation and characterization of nearly domain free 123-oxide showing a superconducting transition width of ∼1.1K

YBa 2Cu 3O 7− ∂ has been prepared by coprecipitation of the corresponding metal ions by hydroxy-carbonate method. A nearly stoichiometric 123-oxide is obtained after a single firing step in flowing O 2. This oxide shows a zerotransition temperature of 92.6 K and a transition width of ∼1.1 K. The oxides prepared at 1173 K and 12 hours of heating in flowing oxygen yield nearly twin-domain-free superconductor showing no other defect structure. We have investigated the preparation of this oxide under various preparative conditions including different pH values of precipitation.

Studies of Hydroxy‐aluminum Phosphates Obtained from Pentahydroxy‐dialuminum Chloride and Monosodium Phosphate

Structural studies of hydroxy-aluminum phosphates with antacid application are performed. The antacid properties of the products depend on their chemical composition and way of preparation. Scanning electron microscope, X-ray- and IR-spectroscopy have evidenced the formation of a one-phase product. The IR-spectra indicate an Al-PO4 containing compound with an Al-PO4 bond. The high-temp. exothermic effect at 730-780 degrees C exhibited by the DTA curves of the hydroxy aluminum phosphates studies are due to polymorphic conversions which are not found with the sample having the best antacid properties. On the basis of these results it is not easy to prove that the higher acid-binding ability of this sample is due to the more favourable position of its acid-binding groups and the absence of phases undergoing polymorphic transformations at high temp. Probably the low pH value of precipitation favours the acid-binding ability. Toxicologic investigations on aluminum ion absorption in blood plasma have shown an admissible aluminium level.

Fabrication and characterization of zirconia-toughened alumina obtained by inorganic and organic precursors

In zirconia-toughened alumina (ZTA) the martensitic transformation of zirconia (tetragonal→ monoclinic) is at the origin of toughening. If the zirconia particles have a mean grain size less thand’c, they remain tetragonal; if their size is betweend’c anddc (dc>d’c), they are stress-induced transformed into the monoclinic form; if their size is larger thandc, particles are transformed. We prepared ZTA using different precursors and compared their microstructures. The coprecipitation of aluminium and zirconium chlorides gives an hydroxide mixture. Thus the zirconium hydrate is amorphous, and the aluminium hydroxide structure varies with the precipitation temperature and pH values at the end of the neutralization. Alumina is mixed with zirconia obtained by gas-phase reaction. Zirconia is prepared by vaporization of zirconium chloride in an oxygen-hydrogen flame. Alumina powder is impregnated by a zirconium acetate solution. Zirconium acetate is thermally decomposed in a spray-dryer, then by calcination. The cohydrolysis of II Al-butoxide and IV Zr-propoxide was carried out in an alkaline solution. The hydrolysis pH (10 or 12) changes the grain size of the oxide powders. Mechanical property measurements and microstructural analysis allow a comparison of the different composites. The mean grain-size evolution differs according to the preparative route, and may be varied by different elaboration parameters. Fine microstructures were always observed. The mean grain size of dispersed zirconia being very small (neard’c), we observed a little influence of transformation toughening. We noticed a large increase in rupture strength, while toughness was not noticeably improved.

Precipitation incidence of the lanthanoid(III) hydroxides: II. Precipitation from chloride and perchlorate solutions

The precipitation pH values of the lanthanoid(III) hydroxides from chloride and perchlorate solutions were determined at 25.0 °C by electrolytic hydroxide formation together with the optical scattering method of detecting precipitate, and compared with those obtained previously from the nitrate solutions. The pH values ranged from 7.58 to 5.85 and from 7.64 to 5.50 between lanthanum and lutetium for chloride and perchlorate solutions respectively. The latter values are appreciably lower than those reported by Meloche and Krátný ( Anal. Chim. Acta, 20 (1959) 415). Discussions are made in connection with the ionic radii of the tervalent lanthanoid ions of six, eight, and nine coordination, as well as the apparent discrepancies among the anionic species employed.

Use of light scattering techniques to study the kinetics of precipitation of mineral acid casein from skim milk

SummaryTwo light scattering methods for monitoring the precipitation of casein from skim milk (9% w/w) with mineral acid are presented. Experiments were carried out at precipitation temperatures in the range 25–53 °C and precipitation pH values in the range 3·9–5·1. The initial stages of precipitation were explored using a light fibre optics system attached to a closed-loop acid/milk mixing system. The later stages of particle formation and growth were examined using a laser doppler anemometer attached to an open-pipe flow system. It was found that there was a lag initially, followed by a period of rapid particle growth. During a third phase a dynamic equilibrium between particle growth, break-up and shrinkage was established. A model for isoelectric casein precipitation based on these observations is proposed and discussed.

Preparation and investigation of dry aluminum phosphate gels with antacid properties.

AbstractDry aluminium phosphate gels with a high‐acid‐binding ability have been obtained by a new method using precipitation processes between hydroxoaluminate solutions and ortho‐phosphoric acid, no chlorides and sulphates being present in both the initial substances and the products. A linear correlation is established between the acid‐binding ability of the gels and the pH value of precipitation over the range investigated: at pH<3.80 no aluminium phosphate with antacid properties was formed. A relationship between the P2O3/Al2O3 ratio and the pH value during the precipitation process is obtained and found to pass through a maximum. An optimum precipitation is attained at pH = 5.60 where the P2O5 concentration in the antacid preparation is sufficiently high. Formation of a xerogel free from microbial contamination is observed after drying for no less than 12 h at 105°C.

Precipitation incidence of the lanthanoid(III) hydroxides

The precipitation pH values of fourteen lanthanoid (III) hydroxides were determined. The hydroxide ion was supplied electrolytically in aqueous solutions of potassium nitrate, and the formation of the insoluble hydroxide was detected through the optical scattering method. The precipitation pH values ranged from 7.47 to 5.74 between lanthanum and lutetium. Discussions are made in connection with some inherent values of the lanthanoid metal ions.

Investigation of dry and wet deposition of air pollution in a rural area

The inorganic composition of dry and wet atmospheric depositions is reported from a rural sampling site near the city of Rome. Cellulose filter paper impregnated with an alkaline solution, and acetate cellulose pre-filters were used for the collection of SO 2 and suspended particulate matter, respectively. A rain-activated wet/dry precipitation collector was utilized. A seasonal trend of SO 2 was observed and analysis of particulate for H +, SO 4 2−, NO 3 − and NH 4 + revealed that a significant amount of free strong acidity was present on particles. Fifty percent of precipitation pH values were below 5.6. On an annual basis the data show that dry acid deposition is more important for the area investigated.

A Computer Simulation Model for Soil Genesis Applications

AbstractA two horizon computer model was developed to simulate leaching and acidification processes occurring in the solid phase of soils of humid, temperate climates. The model used linear equations to describe processes of sulfate adsorption, cation exchange, mineral weathering, and precipitation and dissolution of sesquioxides within the soil. Standard soil characterization and precipitation chemistry data were used as inputs to quantitatively predict changes in soil properties over time. T‐test analysis showed no significant difference at the 0.01 level between field values and those predicted by the model for base saturation, pH, and exchangeable cations. Two examples illustrated the application of the simulation model for soil genesis investigations. In the first example, acidic soils with low buffer capacities reached 60% base saturation (Ultic Hapludalfs) and 35% base saturation (Typic Hapludults) sooner than more basic soils. Using regression analysis (excluding soils with high amounts of exchangeable bases), base saturation decreased at a rate of 0.01%/yr under deciduous forest, and 0.02%/yr under coniferous forest at precipitation pH 4.1. At precipitation pH 5.5, the rate of change was much slower. In the second example, a change in soil pH over time was predicted at precipitation pH values of 4.1 and 5.5 under deciduous and coniferous forest vegetation. In all simulations, a “steady state” soil pH level was predicted, with soils under coniferous forest reaching this level sooner than those under deciduous forest. The steady state pH was lower under precipitation pH 4.1 than under pH 5.5.

Effects of airborne particulate matter on the acidity of precipitation in Central Missouri

The pH of rainfall in central Missouri was monitored at four sites during the fall of 1983. Several pH values were well above 5.6, the theoretical pH of pure water in equilibrium with ambient levels of CO 2. Most of the higher pHs were measured on rainfall of short duration or rainfall collected during the first few hours of extended rainfall events. Furthermore, the rainfall associated with storm events lasting several days exhibited a trend of decreasing pH with time approaching values as low as 4.0 during the late stages of rainfall. Precipitation pH values above 5.6 apparently reflect neutralization reactions between wet precipitation and various components of airborne dust, especially clays and carbonates. During extended rainfalls, the neutralization effects gradually diminish as suspended dust is washed from the atmosphere yielding more accurate values of the wet precipitation pH. The results of this study suggest that airborne particulate matter generated from the dust bowl region of the U.S. may affect the chemistry of precipitation in areas hundreds of km downwind.

Studies on the Separation of Cadmium from Solutions by Foam Separation. II. Precipitate Flotation of Cadmium Hydroxide

Abstract Foam separation of cadmium in relation to pH from solutions of different metal concentrations was carried out by means of lauryl sulfate. The effect of inert salt on the removal of cadmium hydroxide and cadmium cations by adsorbing colloid floation was also studied. The precipitate flotation results reflect the precipitation of the metal in the form of a hydroxide. The precipitation pH values calculated are approximately those at which cadmium removal over 50% is obtained. The presence of electrolyte has a negative effect on the results of precipitate flotation of cadmium hydroxide and adsorbing colloid flotation of cadmium cations with lauryl sulfate.

Precipitation chemistry at Turrialba, Costa Rica

Bulk precipitation samples were collected weekly at Turrialba, Costa Rica, from March 1979 through March 1981 and analyzed for pH, conductivity, major cations and anions, nutrient (N and P) species, and 12 trace metals. Results indicated that Costa Rican precipitation contains relatively low levels of acidity, nutrients, and minerals. For example, during the precipitation years March 1979 to March 1980 and April 1980 to April 1981, volume‐weighted mean specific conductances were 4.88 and 4.82 μS/cm, respectively. Precipitation pH values ranged from 4.81 to 6.35 and the volume‐weighted mean pH was 5.34 over the 2‐year study. On the basis of equivalent ratios, excess [SO42−] was found to be the principal acidic anion, with only small possible contributions from excess [Cl−] or NO3−. Marine‐ derived aerosol accounted for virtually all of the Na+, Mg2− and Cl− deposited in Turrialba rain and was a minor contributor (3–15%) to the K+, Ca2+, and SO42− loadings. Excess [SO42−] comprised 85% of the total SO42− and may arise in Costa Rican precipitation due to long‐range transport, biogenic sources, or local volcanic emissions. Highest concentrations of minerals and nutrients were observed during the low rainfall period of early spring, which coincided with increased agricultural activities. Very low levels of trace metals were observed in the precipitation.

Verifying the effect of acid precipitation on soil leachates: A comparison between published records and model predictions

Abstract A model for predicting the effects of acid precipitation on the acid (H + + Al 3+ + Fe 3+ - and base (Na + + K + Ca 2+ + mg 2+ )-cation losses from soils via leaching as function of time was verified by examining published results for one indoor and five outdoor lysimeter studies (with precipitation pH-values ranging from 2 to 6), and five watershed studies. In each case the predictions of the model were in acceptable (but not perfect) agreement with the observed acid and base cation losses. These studies were selected from other relevant studies because they nearly met the information requirements of the model. The prediction of the acid cation content of soil leachates is important for considering the generally negative effects of such cations (especially the dominating Al 3+ -ions) on plant growth and ground-, stream- and later water quality.