The upper reaches of the Crocodile River (West) system are located in the western basin of the Witwatersrand mountain chain, an area heavily influenced by gold mining. After the spill of highly acidic and contaminated mining-influenced water into the river system in 2002, chemical water treatment was implemented to compensate for the consequences of acid mine drainage. Some studies thereafter have shown metal concentrations of concern in the system, but never considered longer periods of time. For this study, we investigated water and sediments over a period of 13 months from 7 sampling sites in the system. In addition to physico-chemical parameters such as temperature, pH, and electrical conductivity, a multi-element analysis was conducted. We used various versions of atomic-absorption-spectroscopy, total reflection x-ray fluorescence spectroscopy, and inductively coupled plasma mass spectrometry in filtered and acidified water samples as well as sediment leachates. Concentrations of Ni, Zn, As, Pb, and U in the sediment were clearly elevated at the site closest to the mine as well as further downstream, some of them far exceeding quality guidelines. Moreover, dissolved Mn, Fe, Ni, Zn and U occurred irregularly in concentrations of concern at the site of mining-influenced water inflow. Our findings clearly indicate a risk of further and chronic mobilization of toxic elements from this site and a possible threat to the connected river system.

This study reports the impact of margarine-representative ingredients on its oxidative stability and green tea extract as a promising antioxidant in margarine. Oil-in-water emulsions received much attention regarding factors that influence their oxidative stability, however, water-in-oil emulsions have only been scarcely investigated. Margarine, a widely consumed water-in-oil emulsion, consists of 80–90% fat and is thermally treated when used for baking. As different types of margarine contain varying additives, their impact on the oxidative stability of margarine during processing is of pressing importance. Thus, the influence of different ingredients, such as emulsifiers, antioxidants, citric acid, β-carotene and NaCl on the oxidative stability of margarine, heated at 80 °C for 1 h to accelerate lipid oxidation, was analyzed by the peroxide value and oxidation induction time. We found that monoglycerides influenced lipid oxidation depending on their fatty acyl chain. α-Tocopheryl acetate promoted lipid oxidation, while rosemary and green tea extract led to the opposite. Whereas green tea extract alone showed the most prominent antioxidant effect, combinations of green tea extract with citric acid, β-carotene or NaCl increased lipid oxidation in margarine. Complementary, NMR data suggested that polyphenols in green tea extracts might decrease lipid mobility at the surface of the water droplets, which might lead to chelating of transition metals at the interface and decreasing lipid oxidation.

The task-specific ionic liquid trihexyltetradecylphosphonium 3-hydroxy-2-naphthoate, [P ₆₆₆₁₄ ][HNA], was successfully used to extract Ce, Nd and Lu from aqueous solutions. High nitrate concentrations had a strong positive impact on extraction.

Lamproglena clariae , a gill parasite of Clarias gariepinus has previously been identified as a valuable indicator of effect for organic and metal pollution. The current study evaluates it as a bioindicator of metal accumulation by recording the concentration (mg/kg) of Mn, Fe, Zn, Se, and Sr in adult females and eggs collected at six sites along the Vaal River, South Africa. The data are compared to the metal concentrations recorded in water and sediment, and with infection variables calculated for L. clariae collected from C. gariepinus in March 2017 and October 2018. Metal concentrations in parasite samples were measured utilizing total reflection X‐ray fluorescence spectroscopy. This was the first time this method was used to measure metal concentration in L. clariae . Manganese, Fe, Cu, Se, and Sr concentrations differed between adult females and egg specimens and between the six sampling sites, following the difference in the metal concentrations in the water and sediment samples. More polluted sites had low prevalence and low abundance of L. clariae . In adult females, Mn, Fe, Cu, Zn, Se, and Sr had higher concentrations than the water at the more polluted sites. Metal concentration (Mn, Zn, Cu, and Se) was higher in adult females compared to eggs. However, the Fe concentrations were higher in eggs than in adult females. Metal concentrations in L. clariae females were generally higher than levels recorded in water and sediment samples, indicating biomagnification, and supporting the viability of L. clariae as an accumulation indicator. High concentrations of Fe in eggs suggest that Fe elimination may occur via vitellin maternal transfer to larvae. Practitioner Points: Fish ectoparasites have not received sufficient evaluation as indicators of pollution. Lamproglena clariae bioaccumulates metals in polluted environments. Lamproglena clariae eggs accumulate Fe to higher concentrations than the females that produce them.

The consequences of acid mine drainage (AMD) are apparent in water and sediment of the upper reaches of the Crocodile River (West) system, which is located in the western basin of the Witwatersrand mountain chain in South Africa. Another significant indicator for metal and metalloid pollution in aquatic systems is biota. In particular, in the case of AMD-impacted areas, which occur worldwide, biota could serve as an important bioindicator of contamination and also be useful in terms of remediation of pollutants. We investigated the content of Fe, Ni, Cu, Zn, As, Se, Ag, Cd, Hg, and Pb in the liver and muscle tissue of 4 fish species (Oreochromis mossambicus, Labeobarbus polylepis, Labeobarbus marequensis, and Clarias gariepinus) and in roots and stems of macrophytes Pontederia crassipes, Typha sp. and Phragmites australis taken from selected sites in the system. Metals and metalloids were analyzed in freeze-dried and acid-digested samples using graphite furnace atomic absorption spectroscopy, cold vapor atomic absorption spectroscopy, and total reflection X-ray fluorescence spectroscopy. We determined that the mean levels of Fe, Ni and Cu were increased in the roots of Typha sp. and P. crassipes at sites influenced by AMD. Both macrophytes could also be used for phytoremediation of Ni, Cu and Cd, with bioaccumulation factors above 1 at all study sites ranging from 1.1 (Cu) to 21 (Cd) for Typha sp. and 2.7 (Ni) to 25 (Cd) for P. crassipes. Plants were found to be better bioindicators for AMD than fish due to homeostatic regulation of Ni, Cu, and Zn in fish at chronic low-level pollution. An exception was the liver tissue of O. mossambicus, which accumulated high levels of Ni (2.98 ± 1.24 mg kg⁻¹ dw), Cu (184 ± 124 mg kg⁻¹ dw) and Ag (2.01 ± 0.51 mg kg⁻¹ dw), demonstrating its bioindicative potential for these metals. Our study allowed a detailed look at an AMD influenced river system, revealing results that clearly demonstrate the consequences of chronic low-level pollution, although water melioration is in place.