Soil Acidification, Mineral Neoformation and Heavy Metal Contamination Driven by Weathering of Sulphide Wastes in a Ramsar Wetland

Past waste disposal practices have left large volumes of sulphidic material stockpiled in a Ramsar wetland site on the Atlantic coast of southwestern Spain, leading to severe land degradation. With the aim of addressing this legacy issue, soil core samples were collected along two transects extending from the abandoned stockpiles to the adjacent marshland and subjected to XRD, SEM-EDS, ICP-OES and ICP-MS analyses. Sulphide oxidation has been shown to be a major driver of acid generation and metal leaching into the environment. The marsh soil receiving acid discharges from the sulphide wastes contains elevated levels (in mg kg−1) of Pb (up to 9838), As (up to 1538), Zn (up to 1486), Cu (up to 705), Sb (up to 225) and Tl (up to 13), which are retained both in relatively insoluble secondary minerals (mainly metal sulphates and oxides) and in easily soluble hydrated salts that serve as a transitory pool of acidity and available metals. By using a number of enrichment calculation methods that relate the metal concentrations in soil and their baseline concentrations and regulatory thresholds, there is enough evidence to conclude that these pollutants may pose an unacceptable risk to human and ecological receptors.

Synthesis of CoFe2O4 Nanoparticles: The Effect of Ionic Strength, Concentration, and Precursor Type on Morphology and Magnetic Properties

The present study highlights the effect of metal precursor types (SO42¯, Cl¯, and NO3¯), their concentration, and the influence of ionic strength of reaction environment on the morphology, surface, and magnetic properties of CoFe2O4 particles. The magnetic nanoparticles were obtained by chemical coprecipitation in alkaline medium at increasing metal concentration in the range of 0.0425 mol·dm-3 to 0.17 mol·dm-3 and calcination temperature from 400°C to 800°C. It was found that the chemistry of precursors can be directly correlated with magnetic properties. The CoFe2O4 particles from metal sulphate precursors showed the highest saturation magnetization and the lowest coercivity. The adjustment of ionic strength in the range of 1.25–5 M was achieved by adding an appropriate quantity of metal sulphates into aqueous solutions at a constant pH or by adding an appropriate quantity of NaClO5 under similar conditions. The average hydrodynamic size of CoFe2O4 increased from 46 nm to 54 nm with increasing metal concentration and ionic strength. An explanation of magnetic properties, caused by ionic strength and metal concentration, is given based mainly on the reduction in repulsive forces at the particle interface and compensation of the double electric layer in the presence of anions. The observed coercivity was lower for the particles obtained in solutions with the highest ionic strength, whereas the concentration of metals and calcination temperature affected the saturation magnetization and morphology of the obtained cobalt ferrite particles.

The Enhancing Effect of Plants Growth Biostimulants in Garlic Cultivation on the Chemical Composition and Level of Bioactive Compounds in the Garlic Leaves, Stems and Bulbs

The aim of the study was to evaluate the effect of biostimulants enhancing plant growth and development, i.e. organic stimulator based on metal sulphates, Bacillus subtilis, humic acids, on the chemical composition and level of bioactive compounds in garlic leaves, stems, and bulbs. The study was conducted in three growing seasons on the ‘Ornak’ winter garlic cultivar. The propagating material was treated in solutions of the biostimulants and after emergence the plants were sprayed with the products three times. The most valuable edible organ proved to be the leaves, which contained the most protein, fat, and mineral components expressed as ash, were the richest source of fibre, vitamin C, and polyphenols, and also had the highest antioxidant activity among the organs tested. The nutritional value of the stems was comparable to that of the bulbs, and the level of polyphenols and antioxidant activity were even higher. The use of the growth and development biostimulants influenced the chemical composition of the garlic, but the effect was modified by the course of weather in different years of the research and also depended on edible organ. On average for years and organs all biostimulants increased the level of protein, minerals expressed as ash and enhanced antioxidant activity, whereas decreased the level of total carbohydrates.

Coordination polymers built with transition metal sulphates and angular 2,5-bis(imidazol-1-yl)thiophene (thim2): synthesis, structure and photoluminescent properties

Six new CPs, based on thim2 and metal sulphates have been synthesised. The photoluminescence properties of CPs 1 and 3 have been investigated.