Acid Neutralizing Capacity

Antacids are chemical substances which neutralizing the acid that causes heartburn. By reducing the
acidity, the acid is less able to irritate the esophagus. The effect of antacids on the stomach is due to
partial neutralisation of gastric hydrochloric acid and inhibition of the proteolytic enzyme, pepsin. There
are commonly used self-prescribed medications. Antacids are available many forms such as suspensions,
chewable tablets and liquid gels. They consist of calcium carbonate and magnesium and aluminum salts
in various compounds or combinations. Antacids are used for gastric and duodenal ulcers, gastrooesophageal
reflux disease, stress gastritis, pancreatic insufficiency, non-ulcer dyspepsia, biliary reflux,
bile acid mediated diarrhoea, constipation, osteoporosis, urinary alkalinisation and chronic renal failure
as a dietary phosphate binder.

Acidic deposition is comprised of sulfuric and nitric acids and ammonium derived from atmospheric emissions of sulfur dioxide, nitrogen oxides, and ammonia, respectively. Acidic deposition has altered soil through depletion of labile pools of nutrient cations (ie calcium, magnesium), ...

pH is one of the key parameters that determines heavy metal mobility in soils, sediments and waste materials. In many respects leaching behaviour as reflected by the pH(stat) leaching tests provide a better means of assessing environmental impact than analysis of total elemental composition. This paper discusses the use of pH(stat) leaching tests as a tool to assess the potential mobilisation of trace metals from soils, sediments and waste materials. The possibilities of pH(stat) leaching tests are illustrated by means of different examples. The mathematical fitting of metal leaching behaviour from soils and sediments enabled a distinction between 5 groups of elements with a different leaching behaviour, which could be related to 'pools' with different reactivity. Contrary to single and sequential extractions, where pH is difficult to control, the reactivity and mobility of metals at a user-defined pH can be investigated. Moreover, the potential buffering capacity of the sample and its sensitivity to pH changes as a result of external stresses (e.g. soil acidification, liming) can be estimated. A multidisciplinary approach combining mineralogical analysis (X-ray diffraction) with chemical analysis, pH(stat) leaching tests and geochemical modelling (MINTEQA2) can provide information on the solid-phase speciation and reactivity of heavy metals in soils, sediments and waste materials. Besides the influence of pH on heavy metal leaching behaviour, additional information on heavy metal leachability and retention by the solid matrix was obtained from the kinetics of metal release during a pH(stat) test.

Relative percent difference (RPD) and relative standard deviation (RSD) statistics show the variation within individual labs and among the group of labs. Fe, Al, Se, Zn and Acidity exhibited the greatest variability in results across all rock samples and labs. RPD's usually exceeded 30% for ...

Abstract. In this study, chemical composition of the rain water in Mugla was investigated from February to April 2002. Rain water samples were obtained from Mugla, a small city in south western Turkey. The Yatagan Power Plant is located 30 km northwest of Mugla city. The values of ...

This study assessed chemical effects and microbial response after Fenton's treatment of pendimethalin contaminated soils. The efficiency of the rapid chemical transformation of pendimethalin varied from 25% to greater than 90%. The highest efficiency was associated with a soil having comparatively low organic matter and low acid neutralizing capacity. This is consistent with the role of organic matter as a free radical scavenger and the optimum formation of free radicals at low pH. Potential heterotrophic activity, as measured by glucose mineralization, decreased with increasing pendimethalin concentration, but this inhibitory effect was removed after Fenton's treatment. Treatment also released BOD, COD, TOC, and nitrate into solution. The organic matter released into solution was biodegradable and served as a substrate for subsequent microbial growth. Analysis of the microbial population growing in the Fenton's treated soil leachates showed an overall decrease in (culturable) heterotrophic diversity, but an increase in the concentration of Pseudomonas species. These results suggest that Fenton's treatment of pendimethalin contaminated soil created favorable conditions for microorganisms desirable for bioremediation.

In the tropics, warm temperatures and high rainfall contribute to acidic soil formation because of the significant leaching of base cations (K+, Ca2+, Mg2+, and Na+), followed by the replacement of the base cations with Al3+, Fe2+, and H+ ions at the soil adsorption sites. The pH buffering capacity of highly weathered acid soils is generally low because of their low pH which negatively impacts soil and crop productivity. Thus, there is a need to amend these soils with the right amount of inorganic liming materials which have relatively high neutralizing values and reactivity to overcome the aforementioned problems. Soil leaching and the pH buffering capacity studies were conducted to determine whether the co-application or co-amendment of a calcium carbonate product (Calciprill) and sodium silicate can improve soil nutrient retention and pH buffering capacity of the Bekenu series (Typic Paleudults). A 30 day soil leaching experiment was carried out using a completely randomized desi...

High-biomass tree species holds promise for a clean up of metal contaminated soils. Root and fungal activities modify soil characteristics that are important factors for the phytoextraction process (metal availability and toxic- ity). In a rhizobox experiment, two clones of Salix × rubens derived from contaminated and non-contaminated sites were tested for growth performance and metal (Cd, Pb and Zn)

A new aerobic bacterium was isolated from the sediment of a freshwater pond close to a contaminated site at Amponville (France). It was enriched in a fixed-bed reactor fed with 2,6-dichlorophenol (2,6-DCP)as the sole carbon and energy source at pH 7.5 and room temperature. The degradation of 2,6-DCP followed Monod kinetics at low initial concentrations. At concentrations above 300 microM (50 mg.liter-1), 2,6-DCP increasingly inhibited its own degradation. The base sequence of the 16S ribosomal DNA allowed us to assign the bacterium to the genus Ralstonia (formerly Alcaligenes). The substrate spectrum of the bacterium includes toluene, benzene, chlorobenzene, phenol, and all four ortho- and para-substituted mono- and dichlorophenol isomers. Substituents other than chlorine prevented degradation. The capacity to degrade 2,6-DCP was examined in two fixed-bed reactors. The microbial population grew on and completely mineralized 2,6-DCP at 2,6-DCP concentrations up to 740 microM in conti...