Aqueous extracts of Mozambican plants as alternative and environmentally safe acid-base indicators

Indicators are substances that change color as the pH of the medium. Many of these substances are dyes of synthetic origin. The mulala plant (Euclea natalensis), which roots are commonly used by rural communities for their oral hygiene, and roseira (Hibiscus rosa-sinensis), an ornamental plant, are abundant in Mozambique. Currently, synthetic acid-base indicators are most commonly used but have environmental implications and, on the other hand, are expensive products, so the demand for natural indicators started. This study investigated the applicability of aqueous extracts of H. rosa-sinensis and E. natalensis as acid-base indicators. Ground on this work, the extracts can be used as acid-base indicators. On the basis of the absorption spectroscopy in both the UV-Vis region and previous studies, it was possible to preliminarily pinpoint anthocyanins and naphthoquinones as responsible for the shifting of colors depending on the pH range of aqueous extracts of H. rosa-sinensis and E. natalensis. These natural indicators are easily accessible, inexpensive, easy to extract, environmentally safe, and locally available.     

Characterisation of particulate matter emissions from the Zimbabwe Mining and Smelting Company (ZIMASCO) Kwekwe Division (Zimbabwe): a ferrochrome smelter

Particulate matter emissions from stack number 2 of a majorferrochrome smelter, Zimbabwe Mining and Smelting Company(ZIMASCO) were characterized and the rates at which the elementsCr, Fe, Cu and Zn and total ferrochrome dust are emitted into theatmosphere were determined. The extent of soil contamination bythe dust deposited around the smelter in the generally prevailingsoutheasterly wind direction around the smelter was carried out.The highest concentrations of Cr and Fe occurred in the fineparticulates of sizes less than 59 m whilst that of Cu and Znoccurred in the coarse particulates of size range 70-100 m.The emission rates from stack 2 were; total ferrochromeparticulates 62.17 kg h^-1, Cr 6.217 kg h^-1, Fe 2.423 kg h^-1, Zn42 mg h^-1 and 6 mg h^-1 for Cu. Particulate matter was emitted at arate of 289 mg m^-3 from stack number 2. This value exceeds thelegal limit of 200 mg m^-3. Chromium and iron are the metalsin the largest amounts. The particles that constitute the largestproportion of the dust were in the range of 58-107.5 m. Thisis a characteristic feature of the particulate matter emissionsfrom ZIMASCO. Soils in the downwind direction from the smelterwere polluted with Cr up to a distance of about 700 m outward fromthe perimeter of the boundary of the smelter.     

Interactions of secondary amines with bentonite clay and humic materials in dilute aqueous systems

The speciation of dimethylamine, diethylamine, dibutylamine, and diethanolamine on bentonite clay saturated with 1) Na and Ca cations, 2) dodecyltrimethylammonium cation, and 3) tannic acid, and on humic acid and peat, has been studied. Adsorption isotherms were determined and the effect of ionic strength and pH on the adsorption were studied. The results show that the amines react with the particulates by ion exchange mechanisms. Hydrogen bonding seems to also contribute to the binding of dibutylamine.     

Empowering Indigenous natural hazards management in northern Australia

Northern Australia is prone to recurring severe natural hazards, especially frequent cyclones, flooding, and extensive wildfires. The region is sparsely populated (≪ 0.5 persons km⁻²), with Indigenous (Aboriginal) residents comprising 14% of the population, and typically the majority in remote regions. Despite national policy committed to addressing emergency management (EM) in vulnerable Indigenous communities, implementation remains unfunded. We synthesise participatory intercultural research conducted over seven years exploring core challenges, opportunities and potential solutions towards developing effective EM partnerships. Similar EM engagement and empowerment issues face First Nations and local communities in many international settings. In search of solutions, we explore developing effective partnership arrangements between EM agencies and culturally diverse Indigenous communities. Observing that government already provides substantial investment in cultural and natural resource management programmes conducted by over 150 Indigenous Ranger Groups (IRGs) nationally, we demonstrate that expansion of IRG roles to incorporate EM community engagement and service delivery can provide multiple cost-effective community and business development benefits for many remote communities.