Mineralogy and Acid Neutralisation Mechanisms in Inland Acid Sulfate Environments

Soils and sediments containing iron sulfides or the products of sulfide oxidation are known as acid sulfate soils (ASS). These soils possess significant environmental risks due to their potential capacity to produce copious amounts of sulfuric acid (H2SO4) on their exposure to atmosphere. The accumulation of large deposits of sulfidic material has been identified in the past 10 to 12 years in saline-inland wetlands in Australia. Extended periods of natural as well as human-induced drying events in many of these wetlands have resulted in highly saline conditions (e.g. dominated by NaCl and sulfate containing salts) and the exposure (oxidation) of sulfidic material. The oxidation of sulfidic material results in the release of H2SO4 and the precipitation of a range of secondary iron minerals (e.g. goethite, ferrihydrite, schwertmannite. Under highly acidic conditions (pH < 4) found in sulfuric material of the ASS, dissolution of layer silicates or phyllosilicate minerals is the only realistic process that can provide a long-term acid neutralisation in these soils; particularly in many Australian soils which have small quantities of weatherable primary minerals and carbonates. It is vital to investigate the mineralogical composition and dissolution mechanisms of layer silicates or phyllosilicate minerals existing in these ASS environments to develop effective management strategies for these soils. The dissolution rate of illite, a common phyllosilicate mineral in Australian soil, was determined using flow-through reactors at 25 ± 1°C, in solutions with two different ionic strengths of 0.25 M and 0.01 M (maintained using NaCl), and pH ranging from 1–4.25 (H2SO4). The results from the illite dissolution experiments showed a rapid release of cations at the onset of the experiments and a relatively slower release at the steady state. Close to stoichiometric dissolution of illite was obtained at pH 1–4 in the higher ionic strength solutions and at pH 1–3 in the lower ionic strength solutions. The experiment at pH 4.25 in the lower ionic strength solution exhibited RAl < RSi, resulting from a possible adsorption of dissolved Al on the illite surface. Illite dissolution rates showed strong pH dependence, with decreased dissolution rates with increasing pH. The proton reaction orders obtained for dissolution in the higher and lower ionic strength solutions were 0.32 and 0.36, respectively. From the relative cation release data, it was concluded that the dissolution of illite proceeded with the removal of interlayer K followed by the dissolution of octahedral cations, whereas the dissolution of Si was the rate limiting step in the dissolution process. The dissolution rate of illite, kaolinite and montmorillonite was compared in flow-through reactors at 25 ± 1°C and at the two ionic strengths, as described earlier. Kaolinite dissolution rates were close to stoichiometric at pH 1 and 2 in the higher ionic strength solutions and at pH 1–4 in the lower ionic strength solutions. RAl values greater than RSi were obtained for kaolinite dissolution experiments at pH 3 and 4 in the higher ionic strength solutions. Kaolinite dissolution rates were strongly dependent on pH at pH ≤ 3, whereas kaolinite rates showed a little pH dependence at pH 3–4.25, and the point of zero charge (PZC) of the mineral appears to have affected the dissolution rate at these pH values. Kaolinite dissolution rates at pH 1 and 2 (H2SO4) in this study were greater than the previously reported rates in HCl and HClO4 solutions, which was ascribed to the complexation of Al by sulfate ions in the solutions. For montmorillonite dissolution, RAl values greater than RSi were obtained in the higher ionic strength solutions at pH 1–4, whereas an opposite trend was observed in the lower ionic strength solutions at pH 2–4. A reduced RAl in the lower ionic strength solutions from montmorillonite dissolution resulted from (apparent) adsorption of dissolved Al on mineral exchange sites, possibly due to the availability of more interlayer exchange sites for Al re-adsorption and a decreased cation (Na+) competition for exchange sites in these systems. The dissolution rate of the clay fraction of soil cores from an inland ASS at Bottle Bend (BB) in south-western New South Wales (NSW, Australia) was determined under similar experimental conditions to pure minerals described earlier. Clay dissolution experiments were also conducted at 35 and 45°C at pH 1 and 4 to determine the effect of temperature on dissolution rates. The clay sample comprised of smectite (40 %), illite (27 %), kaolinite (26 %) and quartz (6 %), with a minor impurity of anatase (1 %). Clay dissolution rates decreased with an increasing pH and a decreasing temperature. A strong reduction in the initial Al release resulted from clay dissolution in the lower ionic strength solutions at pH 2 to 4, whereas a preferential initial Al release was obtained in the higher ionic strength solutions. A slight increase in the RSi values was observed at the lower ionic strength across the pH range investigated, whereas a significant decrease in RAl was found at pH 4 with a decrease in the ionic strength, at all temperatures. An apparent activation energy value of 18.3 kcal mol–1 was calculated at pH 1 that decreased to 9.0 kcal mol–1 at pH 4. The individual mineral dissolution rates estimated from bulk release rate of Al and Si showed fastest dissolution rates for kaolinite followed by illite and smectite. Smectite dissolution rates obtained for soil clay showed close similarity to pure montmorillonite rates obtained under similar conditions. The acid neutralisation capacity (ANC) of the clay sample was calculated from the release rates of cations (Al, Fe, K, Mg). The ANC values of 44.4 and 13.1 kg H2SO4/tonne of clay sample were estimated from the cation release over a period of 22 and 62 days at pH 1 and 4, respectively. An enhanced release of Al from phyllosilicate dissolution in the highly saline-acidic systems could possibly be a contributing factor to the ecological disturbance caused by increased Al concentrations in the soil and water systems. Morphology of the oxidised surface (5 cm) sediments collected from a highly saline inland ASS at the BB site was characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy (STEM-EDS). Halite (NaCl), gypsum (CaSO4.2H2O) and akaganéite (β-FeOOH) were identified as the major phases with minor amounts of K-jarosite in some sediment samples. Akaganéite is rarely found in the soil environments and mainly forms as a product of corrosion of iron in chloride-rich environment. The precipitation of akaganéite at the study site resulted from the natural occurrence of the unique solution conditions (in situ pH as low as 2 and EC as high as 216 dS/m) at the site. The chemical analysis of the akaganéite found in these sediments revealed an average Fe/Cl mole ratio of 6.7 and a structural formula of Fe8O8(OH)6.8(Cl)1.2 which is consistent with the composition of pure akaganéite. Saline-acidic conditions with significantly higher chloride over sulfate levels provided the necessary conditions for akaganéite formation at the study site. The precipitation of akaganéite in the ASS environment necessitates detailed investigation to determine the competitive formation and stability of this mineral relative to stable secondary iron minerals commonly precipitated in ASS environments

The horns of dilemma: Life or sovereignty

Death and dying are the bitter truth that is faced by every person inevitably. Paying respect to the decision of a patient in a hospital setting is always a challenging task. In eastern countries, family plays an important role in decision making. But it always overrides the preferences and wishes of the patient and this leads to violation of ethical principles such as autonomy, informed consent and veracity. Looking a situation from different paradigms and deciding the best solution on the ground of ethical principles should be the utmost priority of the healthcare provider

Assessment of Knowledge and practice about needle stick injury among nurses at nishtar hospital in Multan; A hospital based cross-sectional study

Background: Needlestick injuries pose a risk to Health Care Workers and patients with whom they interact. These sharp injuries put nursing staff at high risk for occupational exposure to bloodborne pathogens (such as HBV, HCV, and HIV), which is continually adding to the burden of chronic liver disease in our country. HCWs must have comprehensive training in NSI prevention and management to avoid the spread of these infections. As nurses are most at risk for needle stick injuries, our goal was to evaluate and compare the degree of knowledge regarding safety measures to prevent needle stick injuries among nurses. Methods: This study design was cross-sectional and conducted between March and August 2022. The 360 female registered nurses engaged in direct patient care at Nishtar Teaching Hospital in Multan, were selected by using a simple random selection procedure. Data were gathered using a quantitative manipulative questionnaire. Data analysis was performed using SPSS 20.0. Nurses' needle-stick knowledge and safety procedures were correlated using the Chi-square test. The significance (p. value) was selected as 0.05. Results: In regard to needle stick injuries, the results indicated that 48.9% of nurses had enough knowledge, whereas 46.8% agreed with current practice. The majority of nurses (76.6%) know that a needle stick accident is a percutaneous injury, but only 57.8% recognize that it poses a danger for the spread of blood-borne diseases. Roughly half of the nursing workforce believes that needle stick casualties are inevitable. Questions such, as "Do needlestick injuries cause the spread of pathogens?" have a high Chi-square value because of the strong correlation between nursing expertise and age. The best category for knowledge and practice was found among nurses with 6-10 years of experience, suggesting that nurses' length of service to an organization shapes their expertise. Conclusion: The frequency of needle and sharp injuries may be decreased by educating people on how to avoid them by utilizing personal protective equipment while handling contaminated needles and sharp objects that contain blood or other bodily fluids

Nanoparticulate Iron Oxide Minerals for Arsenic Removal from Contaminated Water

Groundwater contamination with arsenic (As) is a global environmental and human health problem affecting over 200 million people worldwide, with low to high concentrations of As via drinking well water. Therefore, remediation of As-contaminated water has been under discussion over the last 3 to 4 decades given its highly toxic and carcinogenic properties of As compounds, particularly inorganic arsenite and arsenate species. Several types of sorption techniques have been used to remove As from water such as clay minerals, biochars, metal oxides (e.g., iron oxide minerals), microbes and algae. This chapter provides: (1) insights on the significance of nanoparticulate iron (Fe) oxide minerals (such as nano-ferrihydrite, nano-goethite, nano-magnetite) for their efficiency in the removal of As from contaminated water; (2) develops critical understanding for several As removal methods, compares their potential for As remediation, and critically examines the properties and effectiveness of nanoparticulate Fe oxide minerals to remove As in drinking water or wastewater; and (3) implication of the nanotechnology in remediation of As-rich water. This chapter also elucidated the mechanism of As removal using Fe-oxide nanoparticles in detail

Arsenic speciation and biotransformation pathways in the aquatic ecosystem: The significance of algae

© 2020 Elsevier B.V. The contamination of aquatic systems with arsenic (As) is considered to be an internationally-important health and environmental issue, affecting over 115 countries globally. Arsenic contamination of aquatic ecosystems is a global threat as it can enter the food chain from As-rich water and cause harmful impacts on the humans and other living organisms. Although different factors (e.g., pH, redox potential, iron/manganese oxides, and microbes) control As biogeochemical cycling and speciation in water systems, the significance of algal species in biotransformation of As is poorly understood. The overarching attribute of this review is to briefly elaborate various As sources and its distribution in water bodies and factors affecting As biogeochemical behavior in aqueous ecosystems. This review elucidates the intriguing role of algae in biotransformation/volatilization of As in water bodies under environmentally-relevant conditions. Also, we critically delineate As sorption, uptake, oxidation and reduction pathways of As by algae and their possible role in bioremediation of As-contaminated water (e.g., drinking water, wastewater). The current review provides the updated and useful framework for government and water treatment agencies to implement algae in As remediation programs globally

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

SummaryBackground Azithromycin has been proposed as a treatment for COVID-19 on the basis of its immunomodulatoryactions. We aimed to evaluate the safety and efficacy of azithromycin in patients admitted to hospital with COVID-19.Methods In this randomised, controlled, open-label, adaptive platform trial (Randomised Evaluation of COVID-19Therapy [RECOVERY]), several possible treatments were compared with usual care in patients admitted to hospitalwith COVID-19 in the UK. The trial is underway at 176 hospitals in the UK. Eligible and consenting patients wererandomly allocated to either usual standard of care alone or usual standard of care plus azithromycin 500 mg once perday by mouth or intravenously for 10 days or until discharge (or allocation to one of the other RECOVERY treatmentgroups). Patients were assigned via web-based simple (unstratified) randomisation with allocation concealment andwere twice as likely to be randomly assigned to usual care than to any of the active treatment groups. Participants andlocal study staff were not masked to the allocated treatment, but all others involved in the trial were masked to theoutcome data during the trial. The primary outcome was 28-day all-cause mortality, assessed in the intention-to-treatpopulation. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936.Findings Between April 7 and Nov 27, 2020, of 16 442 patients enrolled in the RECOVERY trial, 9433 (57%) wereeligible and 7763 were included in the assessment of azithromycin. The mean age of these study participants was65·3 years (SD 15·7) and approximately a third were women (2944 [38%] of 7763). 2582 patients were randomlyallocated to receive azithromycin and 5181 patients were randomly allocated to usual care alone. Overall,561 (22%) patients allocated to azithromycin and 1162 (22%) patients allocated to usual care died within 28 days(rate ratio 0·97, 95% CI 0·87–1·07; p=0·50). No significant difference was seen in duration of hospital stay (median10 days [IQR 5 to >28] vs 11 days [5 to >28]) or the proportion of patients discharged from hospital alive within 28 days(rate ratio 1·04, 95% CI 0·98–1·10; p=0·19). Among those not on invasive mechanical ventilation at baseline, nosignificant difference was seen in the proportion meeting the composite endpoint of invasive mechanical ventilationor death (risk ratio 0·95, 95% CI 0·87–1·03; p=0·24).Interpretation In patients admitted to hospital with COVID-19, azithromycin did not improve survival or otherprespecified clinical outcomes. Azithromycin use in patients admitted to hospital with COVID-19 should be restrictedto patients in whom there is a clear antimicrobial indication

Enhancing patient well-being: Applying environmental theory in nursing practice

Theoretical framework always guides nursing practice and nurses follow this unconsciously. This paper highlights the work of Florence nightingale who, identified the application of environmental theory in nursing practice. Nightingale has defined 13 canons of environment and explained each aspect in detail. Her major canons include: ventilation, noise, cleanliness of walls/rooms, light, bed and bedding, personal cleanliness, and taking food. Nightingale has beautifully described the effect of application of her theory. The theory when applied, yields a positive impact on patient’s health. The learning outcomes of this research will help the people in medical science to understand the correlation between environmental theory and nursing practices for the wellbeing of patients. And if one is failed to apply all of the concepts in clinical area then it can lead to delayed recovery of the patient

Epidemiology of rabies in Pakistan: A review of literature

Objective: This literature review aims to explore the risk factors, preventive measures and treatment options for people with rabies especially in Pakistan. Introduction: It is suggested that nearly 2,000 to 5,000 deaths been reported annually due to rabies, in Pakistan. It is estimated that above 30,000 people die each year because of rabies in Asia. One Asian expires every 15 minutes where 15% are probable to be the children under 15 years.Methods: Comprehensive and systematic literature search was undertaken by using various electronic research databases. Studies were eligible for this review if they were published in last twenty years in english language and focused on epidemiology, risk factors, consequences, prevention and treatment of rabies especially in Pakistan.Results: Rabies is a prevalent disease and there are so many barriers especially in Pakistan which led this issue to persist. Lack of awareness and improper vaccination of dogs are the major leading issues which are increasing the number of patients affected by rabies day by day.Conclusion: Results suggest that rabies is one of the common diseases in Asia and the root cause of which is lack of awareness and stray dogs especially in developing countries like Pakistan. Since this overlooked illness can lead to serious complications, the issue should be addressed to promote public health

Dissolution kinetics of soil clays in sulfuric acid solutions: ionic strength and temperature effects

Significant amounts of sulfuric acid (H2SO4) rich saline water can be produced by the oxidation of sulfide minerals contained in inland acid sulfate soils (IASS). In the absence of carbonate minerals, the dissolution of phyllosilicate minerals is one of very few processes that can provide long-term acid neutralisation. It is therefore important to understand the acid dissolution behavior of naturally occurring clay minerals from IASS under saline–acidic solutions. The objective of this study was to investigate the dissolution of a natural clay-rich sample under saline–acidic conditions (pH 1–4; ionic strengths = 0.01 and 0.25 M; 25 C) and over a range of temperatures (25–45 C; pH 1 and pH 4). The clay-rich sample referred to as Bottle Bend clay (BB clay) used was from an IASS (Bottle Bend lagoon) in south-western New South Wales (Australia) and contained smectite (40%), illite (27%), kaolinite (26%) and quartz (6%). Acid dissolution of the BB clay was initially rapid, as indicated by the fast release of cations (Si, Al, K, Fe, Mg). Relatively higher Al (pH 4) and K (pH 2–4) release was obtained from BB clay dissolution in higher ionic strength solutions compared to the lower ionic strength solutions. The steady state dissolution rate (as determined from Si, Al and Fe release rates; RSi, RAl, RFe) increased with decreasing solution pH and increasing temperature. For example, the highest log RSi value was obtained at pH 1 and 45 C (9.07 mol g1 s1 ), while the lowest log RSi value was obtained at pH 4 and 25 C (11.20 mol g1 s1 ). A comparison of these results with pure mineral dissolution rates from the literature suggests that the BB clay dissolved at a much faster rate compared to the pure mineral samples. Apparent activation energies calculated for the clay sample varied over the range 76.6 kJ mol1 (pH 1) to 37.7 kJ mol1 (pH 4) which compare very well with the activation energy values for acidic dissolution of monomineralic samples e.g. montmorillonite from previous studies. The acid neutralisation capacity (ANC) of the clay sample was calculated from the release of all structural cations except Si (i.e. Al, Fe, K, Mg). According to these calculations an ANC of 1.11 kg H2SO4/tonne clay/day was provided by clay dissolution at pH 1 (I = 0.25 M, 25 C) compared to an ANC of 0.21 kg H2SO4/tonne clay/day at pH 4 (I = 0.25 M, 25 C). The highest ANC of 6.91 kg H2SO4/tonne clay/day was provided by clay dissolution at pH 1 and at 45 C (I = 0.25 M), which is more than three times higher than the ANC provided under the similar solution conditions at 25 C. In wetlands with little solid phase buffering available apart from clay minerals, it is imperative to consider the potential ANC provided by the dissolution of abundantly occurring phyllosilicate minerals in devising rehabilitation schemes