Trends of pH and aerosols in the precipitation at Srinagar, Mohanbari, Allahabad, Jodhpur, Nagpur and Minicoy during the period 1981-2001

Nature of Precipitation - alkaline or acidic depends upon the concentration of major water soluble inorganic gaseous and soil derived particulates dissolved in it. If the concentration of cations is higher than that of anions the precipitations becomes alkaline and vice versa. pH is the main parameter indicating the nature of precipitation. If pH of rainwater <5.65 it is acidic and >5.65, it is alkaline ,both in the pH scale ranging between 0 and 14. In this paper average ionic concentration (mg/lit) and their trends have been analyzed. Srinagar, Mohanbari, Jodhpur, Allahabad, Nagpur and Minicoy have been selected for the study of chemical precipitation during the period 1981-2001. Trends of different aerosols have been analyzed at the intervals 1981-87, 1988-94 and 1995-2001. It has been observed that percentage of anions has increased which results in the increase of acidic character of the precipitation. During the interval 1995-2001, Nagpur and Mohanbari had pH values 5.16 and 5.47 respectively which were in acidic range.

Role of aerosols in deciding pH of rainwater

Nature of precipitation – alkaline or acidic – depends upon the concentration of major water soluble inorganic gaseous and soil derived particulates dissolved in it. If concentration of cations is higher than that of anions, the precipitation becomes alkaline and vise-a-versa. pH is the main parameter indicating the nature of precipitation. If pH of the solution is < 5.65, it is acidic and > 5.65, alkaline, in the pH scale ranging between 0 & 14. Difference in the chemical composition of rainwater having pH in the alkaline range and acidic range has been studied in this paper. For this purpose, precipitation chemistry data of Allahabad, Jodhpur, Mohanbari and Nagpur for the period 1988-97 have been considered. APWM & S.D. have been worked out. Precipitation chemistry data considering APWM values in acidic range and in alkaline range have been separated and compared. Coefficients of correlation have been calculated in possible cation-anion combinations. It is seen that the lowest pH values (monthly mean) have been recorded during 1997 – MHB (3.77), NGP (4.12), both in acidic range. % Frequency of occurrences of pH values in acidic range was the highest at Mohanbari (66%) in the study period. Jodhpur recorded all pH values in alkaline range indicating influence of soil derived alkaline particulates. Among cations Ca+² has shown its dominance over all cations. Jodhpur has recorded the highest APWM value of Ca+² (9.27mg/lit) in 1997. Data have also been compared with WMO Laboratory simulated acid rain sample analysis data and other non-departmental data. Results are discussed in the paper.

Bio-Hydrogen Production Using Landfill Leachate Considering Different Photo-Fermentation Processes

Recently, it has become imperative to find new sustainable and renewable sources of energy, in order to avoid dependence on non-renewable traditional energy resources. This would help to overcome the depleting of natural resources for energy production. Hydrogen gas production using biological processes is one of the most attractive solutions in this regard, due to its high energy content and ecofriendly nature. Production of hydrogen using single photo-fermentation process and landfill leachate as substrate was carried out in this paper, by utilizing batch bio-reactor and anaerobic conditions. The pH value and temperature, play an essential role in a bio-hydrogen production process. Thus, in this study, the pH values considered were 6, 6.5, and 7.2, respectively, at a controlled temperature of 37 ± 1°C. This study investigated various schemes that have the possibility of producing hydrogen using; landfill leachate alone, with leachate and addition of inoculum such as sewage sludge, and with substrate such as sucrose and glucose. All experiments were conducted with and without mixing, for effective comparative study. Heat and pH pretreatment were applied in each experiment with the objectives of decreasing the activities of methane-producing bacteria and enhancing the activities of hydrogen-producing bacteria. The hydraulic retention time used in this study was 48 h, in order to obtain optimal performance of the schemes employed. Analysis of liquid leachate was performed for each experiment, and based on the obtained results, the maximum yield of hydrogen produced was 5,754 ml H2/L, with a medium pH scale of 6.0, fermentation temperature of 37 ± 1°C and constant mixing speed of 100 rpm.

HO- and OH-, Reason and Tradition

Writing OH- is so widespread that one hardly notices that there no logical reason, apart from being accustomed to so, not to write HO- instead. Scientists should be educated to spot irregularities, since often they mean something. Chemistry professors, in particularly at graduate level, when teaching pH, should make their students notice such discrepancy. Albeit pH is not a complex topic it is intriguing the number of misconceptions, and even plain errors, associated. For example, the limits of the pH scale, it is not uncommon to find students (and not just undergrads) believing pH values cannot be lower than 1 or higher than 14, or that negative pH values do not exist. Herein, it is addressed the odd exception of writing OH- instead of the most logical form of HO-. It is fascinating that chemists are so accustomed to see OH- that they do not longer find it to be an oddity. First, it is important to highlight why it is a nomenclature exception, i.e., the lack of reason to write OH-.

Toward Unified pH of Saline Solutions

Fluctuations of pH in coastal systems are generally surveyed through potentiometric pH measurements. A new concept of a unified pH scale was introduced with the great advantage of enabling comparability of absolute values, pHabs, pertaining to any medium. Using water as an anchor solvent, yielding pHabsH2O, enables referencing the pHabs values to the conventional aqueous pH scale. The current work aims at contributing to implement pHabsH2O to saline solutions. To this purpose, differential potentiometric measurements, with a salt bridge of ionic liquid [N2225][NTf2], were carried out aiming at overcoming problems related to residual liquid junction potentials that affect the quality of such measurements. The ability to measure pHabsH2O with acceptable uncertainty was evaluated using Tris-Tris·HCl standard buffer solutions prepared in a background matrix close to the characteristics of estuarine systems (salinity of 20) as well as with NaCl solutions with ionic strength between 0.005 and 0.8 mol kg−1. The present study shows that for high ionic strength solutions, such as seawater, challenges remain when addressing the assessment and quantification of ocean acidification in relation to climate change. Improvements are envisaged from the eventual selection of a more adequate ionic liquid.

Anthocyanin Color Stabilization by Host-Guest Complexation with p-Sulfonatocalix[n]arenes

Flavylium-based compounds in their acidic and cationic form bring color to aqueous solutions, while under slightly acidic or neutral conditions they commonly bring discoloration. Selective host-guest complexation between water-soluble p-sulfonatocalix[n]arenes (SCn) macrocycles and the flavylium cationic species can increase the stability of the colored form, expanding its domain over the pH scale. The association constants between SCn and the cationic (acid) and neutral basic forms of flavylium-based compounds were determined through UV-Vis host-guest titrations at different pH values. The affinity of the hosts for synthetic chromophore was found to be higher than for a natural anthocyanin (Oenin). The higher affinity of SC4 for the synthetic flavylium was confirmed by 1H NMR showing a preferential interaction of the flavylium phenyl ring with the host cavity. In contrast with its synthetic counterpart, the flavylium substitution pattern in the anthocyanin seems to limit the inclusion of the guest in the host’s binding pocket. In this case, the higher affinity was observed for the octamer (SC8) likely due to its larger cavity and higher number of negatively charged sulfonate groups.

A unified pH scale for all solvents: part I – intention and reasoning (IUPAC Technical Report)

The definition of pH, its measurement and standard buffers, is well developed in aqueous solutions. Its definition in solvents other than water has been elaborated for a couple of solvents and their mixtures with water. However, the definition of a universal pH scale spanning all solvents and phases, not to mention standard procedures of measurement, is still a largely uncharted territory. UnipHied is a European collaboration and has the goal of putting the theoretical concept of an earlier introduced (2010) unified pHabs scale on a metrologically well-founded basis into practice. The pHabs scale enables the comparability of acidity between different phases. This article draws the connection of the concepts of unified acidity and secondary pH measurement.

Adsorption of Hexavalent Chromium by Sodium Alginate Fiber Biochar Loaded with Lanthanum

Lanthanun oxide (La2O3) is a lanthanum chemical compound incorporates a sensible anionic complexing ability; however, it lacks stability at a low pH scale. Biochar fibers will give the benefit of their massive space and plethoric uses on the surface to support a metal chemical compound. Herein, wet spinning technology was used to load La3+ onto sodium alginate fiber, and to convert La3+ into La2O3 through carbonization. The La2O3-modified biochar (La-BC) fiber was characterized by SEM, XRD and XPS, etc. An adsorption experiment proved that La-BC showed an excellent adsorption capacity for chromates, and its saturation adsorption capacity was about 104.9 mg/g. The information suggested that the adsorption was in step with both the Langmuir and Freundlich models, following pseudo-second-order surface assimilation mechanics, which showed that the Cr (VI) adsorption was characterized by single-phase and polyphase adsorption, mainly chemical adsorption. The thermodynamic parameters proved that the adsorption process was spontaneous and endothermic. The mechanistic investigation revealed that the mechanism of the adsorption of Cr (VI) by La-BC may include electrostatic interaction, ligand exchange, or complexation. Moreover, the co-existing anions and regeneration experiments proved that the La-BC is recyclable and has good prospects in the field of chrome-containing wastewater removal.

The anthropogenic environmental impacts and changes in the tropical Atlantic - a high resolution Cuban coral time series over 154 years

&lt;p&gt;Changes in the surface ocean pH and temperature caused by the uptake of anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; are posing a threat to calcifying marine organisms. Recent studies have observed significant impacts on coral reef ecosystems with impaired carbonate skeletal growth and decreased calcification due to acidifying oceans. In situ measurements from buoys, ships, and remote observations by satellite of sea surface temperature, salinity, and ocean&amp;#8217;s carbonate chemistry are sparse and only date back a few decades. The current coverage of observations for the northwestern Cuban coastal waters provides hence an incomplete picture of natural climate variability over interannual to interdecadal timescales, showing the need for high resolution climate archives.&lt;/p&gt;&lt;p&gt;Cuba is situated between densely populated landmasses of North and South America offering a unique environment to study multiple aspects of anthropogenic activity across the region as well as their interconnectivity.&lt;/p&gt;&lt;p&gt;A massive coral, &lt;em&gt;Siderastrea siderea&lt;/em&gt;, from Cuba&amp;#8217;s northwestern coast, was used as a natural archive to reconstruct bimonthly changes in SST, and carbonate chemistry through a multi-proxy approach since preindustrial times.&lt;/p&gt;&lt;p&gt;Preliminary results indicate a decrease in &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O of 0.32 &amp;#8240; over 154 years since 1852,&amp;#160; indicating warming and/or freshening of the surface water over this period. Over the same time period, the &amp;#948;&lt;sup&gt;11&lt;/sup&gt;B ratio decreased by ca. 1.6 &amp;#8240;, translating into a decrease of 0.1 on the pH scale, reflecting the acidification of the northwestern Cuban coastal waters. Furthermore, an accelerating decrease of coral &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C from the 1850s to 2005 of 1.5 &amp;#8240; demonstrates the anthropogenic imprint due to increased fossil fuel combustion. Further investigation and the comparison to trace elements indicate possible baseline shifts in regional seawater carbonate chemistry that have been affected by anthropogenic activity.&lt;/p&gt;