Cytotoxicity and Genotoxicity evaluation of municipal wastewater discharged into the head of Blue Nile River using the Allium Cepa test

Cyto-genotoxic effects predict ecotoxicity in plant bioassays and the aquatic organism Artemia salina L.: a case study from a sewage treatment plant

This study evaluated the toxicological and mutagenic potential of water samples from a Wastewater Treatment Plant (WWTP) in Lavras, Minas Gerais, Brazil. Samples were taken from four sites: upstream in the stream (P1), downstream (P2), at the entrance of the treatment station (P3), and at the exit (P4). We conducted physicochemical analyses in water, phytotoxicity tests on plants (Triticum aestivum, Pennisetum glaucum, Lactuca sativa, Raphanus sativus), cytogenotoxicity tests using onion roots (Allium cepa), and Artemia salina immobilization tests. Elevated Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), anionic surfactants, and ammoniacal nitrogen were found at P3 and P4. While germination rates were generally unaffected, P4 inhibited the germination speed of R. sativus. The growth of L. sativa increased in P3 and P4, and of R. sativus in P2, due to more nitrogen and phosphorus. T. aestivum and P. glaucum, however, had their growth inhibited at P4 due to surfactant toxicity. Cytogenotoxicity tests revealed the highest frequencies of micronuclei and nuclear buds in cells exposed to P3 and P4. Additionally, P3 caused 87.5% immobilization of A. salina. These findings suggest that the WWTP is not fully efficient, and its effluent discharge may contribute to eutrophication and genetic mutations in exposed organisms.

Bioassay of toxicity of acid mine drainage treated and untreated with lime ash using the bioindicator Pisum sativum L

Acid mine drainage (AMD) is an important source of environmental pollution that affects water quality and biodiversity in areas near mining activities. This study evaluated the efficiency of the treatment of AMD with lime ash, through physicochemical analysis and toxicity tests on the bioindicator Pisum sativum L. Samples of AMD were collected in a mining area of Norte de Santander and characterized physicochemically in terms of Al, Cu, Fe, Mn, Zn, and Pb concentrations, as well as pH. The AMD was treated with lime ash to evaluate its ability to neutralize pH (2.3 ± 0.1-7.2 ± 0.7) and remove metals. Toxicity tests showed that the lime ash treatment was able to neutralize pH and significantly reduce metal concentrations, with removal efficiencies greater than 97.2%. In addition, P. sativum showed improved germination, root growth, mitotic index, and a reduction in the frequency of chromosomal abnormalities after treatment. This approach proves to be an effective strategy to reduce AMD contamination, improving physicochemical parameters and decreasing toxicity in model organisms. Further long-term studies are recommended to optimize the process and ensure its effectiveness in the restoration of ecosystems affected by mining.

Hydroxyapatite/L-Lysine Composite Coating as Glassy Carbon Electrode Modifier for the Analysis and Detection of Nile Blue A

An amperometric sensor was developed by depositing a film coating of hydroxyapatite (HA)/L-lysine (Lys) composite material on a glassy carbon electrode (GCE). It was applied for the detection of Nile blue A (NBA). Hydroxyapatite was obtained from snail shells and its structural properties before and after its combination with Lys were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analyses. The coupling of Lys to HA was attributed to favorable interaction between negatively charged -COO^- groups of Lys and divalent ions Ca²⁺ of HA. Electrochemical investigations pointed out the improvement in sensitivity of the GCE/Lys/HA sensor towards the detection of NBA in solution. The dependence of the peak current and potential on the pH, scan rate, and NBA concentration was also investigated. Under optimal conditions, the GCE/Lys/HA sensor showed a good reproducibility, selectivity, and a NBA low detection limit of 5.07 × 10^-8 mol L^-1. The developed HA/Lys-modified electrode was successfully applied for the detection of NBA in various water samples.