Toxicity of polychlorinated biphenyls in aquatic environments - A review.

The assessment of polychlorinated biphenyls (PCBs) and their congeners resulting from the pollution of all environmental media is inherently related to its persistence and ubiquitous nature. In principle, determination of this class of contaminants are limited to the determination of their concentrations in the various environmental matrices. For solving many problems in this context, knowledge of the emission sources of PCBs, transport pathways, and sites of contamination and biomagnification is of great benefit to scientists and researchers, as well as many regulatory organizations. By far the largest amounts of PCBs, regardless of their discharged points, end up in the soil, sediment and finally in different aquatic environments. By reviewing relevant published materials, the source of origin of PCBs in the environment particularly from different pollution point sources, it is possible to obtain useful information on the nature of different materials that are sources of PCBs, or their concentrations and their toxicity or health effects and how they can be removed from contaminated media. This review focuses on the sources of PCBs in aquatic environments and critically reviews the toxicity of PCBs in aquatic animals and plants. The review also assesses the toxicity equivalency factors (TEFs) of PCBs providing valuable knowledge to other scientists and researchers that enables regulatory laws to be formulated based on selective determination of concentrations regarding their maximum permissible limits (MPLs) allowed. This review also supplies a pool of valuable information useful for designing decontamination technologies for PCBs in media like soil, sediment, and wastewaters.

Phytochemical profile of seeds from 21 Bambara groundnut landraces via UPLC-qTOF-MS.

Bambara groundnut is one of the under-utilized African legume crops, valued for its nutritional and health benefits, and for which ongoing studies will help to distinguish its many landraces and select the promising one for breeding programs. To describe the polar metabolome of the seed from 21 Bambara groundnut landraces, untargeted metabolomics approach using UPLC-qTOF-MS (Ultra performance liquid chromatography-Quadrupole time of flight mass spectrometry) was performed. Metabolites belonging to varied compound classes were detected and identified. The total phenolic, flavonoid and anthocyanin contents varied from 0.75 to 17.71 mg GAE.g-1, 0.01 to 2.51 mg QUE.g-1 and 0.03 to 1.31 mg CYE.g-1, respectively. Unsupervised statistics highlighted differences in the metabolome of different landraces. Principal component analysis revealed that caffeic and catechin conjugates are the most decisive marker compounds discriminating the landraces. This study provides the most complete map of metabolites in Bambara groundnut seeds and demonstrates that UPLC-qTOF-MS coupled with chemometric is an excellent tool for differentiation between landraces. These findings highlight the potential of Bambara groundnuts as an economic source of natural antioxidants for human consumption and food industries, and therefore open horizons to the industrial use of Bambara groundnut flours in the development of functional food and feed products.

Surface and adsorptive properties of Moringa oleifera bark for removal of V(V) from aqueous solutions.

The bark of Moringa oleifera, a cheap and readily available natural biopolymeric resource material, found to significantly reduce coliform load and turbidity in contaminated water is investigated in this paper. Its surface and adsorptive properties are investigated to explore its adsorptive potential in removing V(V) from aqueous solutions. Surface properties were investigated using FTIR, HRSEM/EDS, IC, and BET-N2 adsorption techniques. Adsorptive properties were investigated by optimizing adsorption parameters such as pH, temperature, initial metal concentration, and adsorbent dosage, using V(V) as an adsorbate. The adsorption-desorption isotherms are typical of type II with a H3 hysteresis loop and is characteristic of a largely macroporous material. Bottle ink pores are observed, which can provide good accessibility of the active sites, even though the internal BET surface area is typically low (1.79 g/m2). Solution pH significantly influences the adsorptive potential of the material. The low surface area negatively impacts on the adsorption capacity, but is compensated for by the exchangeable anions (Cl-, F-, PO43-, NO3-, and SO42-) and cations (Ca2+, K+, Mg2+, and Al3+) at the surface and the accessibility of the active sites. Adsorption isotherm modeling show that the surface is largely heterogeneous with complex multiple sites and adsorption is not limited to monolayer.