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The green synthesis of nanoparticles has been a vital aspect in the search for novel antimicrobial agents. This research aimed at biosynthesis, characterization and preliminary evaluation of the antibacterial properties of silver nanoparticles (AgNPs) from the back extract of Annona senegalensisis. The bark of Annona senegalensis was scraped from the stem, washed, air-dried, pulverised and extracted. Four millilitre (4 ​ml) of the extract was pipetted into 36 ​mL (36 ​ml) of silver nitrate solution (5 ​mM AgNO3) in a conical flask. The resulting solution was subjected to magnetic stirring at room temperature (28 ​°C ​± ​2) till AgNPs were formed. The synthesized AgNPs were filtered, washed with deionized water and dried in oven at 40 ​°C. Fourier transform infrared (FTIR) analysis was carried out on the synthesized AgNPs. The AgNPs synthesized was also characterized with UV–visible spectrophotometer (UV), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy to ascertain the physico-chemical and morphological properties of the AgNPs. The antimicrobial investigation was carried out following standard method. The observation of colour change (pale yellow to dark brown) during the synthesis and maximum absorbance at wavelength 431.19 ​nm in the UV spectrum confirmed the formation of AgNPs. The FTIR analysis showed that the biomolecules responsible for the reduction of silver ion contain O–H functional groups. The electron microscopy studies indicated that the AgNPS are spherical in shape with nanoparticles sizes of 11–24.76 ​nm. EDX analysis showed that the AgNPs contain high amount of silver and few other elements. The antimicrobial study showed high zones of inhibition 22.75–33.75 against tested bacteria. The simplicity of the synthesis of AgNPs from the extract of the stem bark of Annona senegalensisis and relatively high zones of inhibitions shown by the AgNPs are strong evidences of the possible application of Annona senegalensisis in the synthesis of novel therapeutic agent against infections from bacteria and fungi.

This study conducts a comparative assessment of two dumpsites (abandoned and active dumpsite) around Osogbo metropolis Osun State Nigeria. Ten selected heavy metals (HMs) such as arsenic, copper, cobalt, cadmium, chromium, iron, nickel, manganese, lead and zinc were determined. The soil samples were collected, at strategic points to revealed variation in samples. The concentrations of HMs were quantitatively determined using atomic absorption spectroscopy. The results indicated that all the HMs determined were found between below detection limit (bdl) to 0.611 mg/kg and bdl ���0.880 mg/kg for abandoned and active dumpsites, respectively. The concentration factor and geo-accumulation intensity revealed no contamination to strong contamination and from uncontaminated to strong contamina?tion intensity, respectively. The concentrations for some of the HMs were below the tolerable recommendation level by National Environmental Standards and Regulation Enforcement Agency and Food and Agriculture Organization/World Health Organization in soil samples. This study recommends periodic monitoring and that possi?ble decontamination of the dumpsite are crucial because these dump?sites were currently in use for crops cultivation such as maize, vegetable bananas, and some other arable plants. Also, HM concentra?tions in crops should be investigated and monitored at these dump?sites regularly in order to avert detrimental effects of HM pollution, which could manifest many years after exposure, as they are recalci?trant in the environment.

The quest for safe water due to exponential population growth and climate change has stressed the existing available water source. It is crucial to establish the present pollution level of the Asa River and the health risk it may pose to the people. Samples were collected along the Asa River, Ilorin, Kwara State, Nigeria, and treated using standard methods as stipulated by United States Environmental Protection Agency. The treated samples were analyzed and quantified for dieldrin, endrin, dichlorodiphenyltrichloroethane metabolites, mirex, hexachlorocyclohexane, hexachlorobenzene, and triclosan using the gas chromatography-mass spectrometry. The result showed that the levels of organochlorine pesticides (OCPs) ranged from 0.0045-0.947 μg/kg, 0.0036-0.093 μg/kg, and 0.001-0.007 μg/L in sediment, soil, and water samples, respectively. While the mean concentration of triclosan is 3.78 μg/kg, 2.995 μg/kg, and 0.064 μg/L in sediment, soil, and water samples, respectively. The levels of OCPs were lower than the limits in drinking water as set by World Health Organization and European Union. Health risk assessment for both children and adults was evaluated using non-carcinogenic and carcinogenic risk with the hazard quotient (HQ) and was found to be greater than unity ( 1) in children for the targeted OCPs. Associated cancer risk for OCPs ranged from low cancer risk to moderate risk for humans. The adverse ecological effects of OCPs showed to be very rare to occur and frequent effects may not likely occur except for HCH.

This study focuses on the sorption efficiency of porewater–sediment of eight selected polychlorinated biphenyls (PCBs) most monitored in the environment as recommended by the Environmental Protection Agency. Five river sediment samples were collected along the Umgeni River of KwaZulu-Natal province of South Africa that contained different soil contents. The Walkley–Black method was employed for the determination of soil organic matter in the sediments, while sediment mineralogy and morphology, as well as elemental composition, were evaluated using powder X-ray diffraction and scanning electron microscopy equipped with energy-disperse X-ray, respectively. The sorption studies between porewater and sediment systems were carried out using batch adsorption experiments. The results showed that sediment samples containing high clay and silt content (13.90%, 30.43% and 18.58%, 19.93%) (site AWW and IDI) have the highest sorption percentage between 65.86–89.81% and 61.39–70.43%, respectively, for all the PCBs, while sites IDO and BL with high sand content (86.29% and 85.20%) sorbed the least amount of PCBs (32.32–53.06% and 43.23–59.77%, respectively). Among the sediment physicochemical parameters, soil organic matter was observed to correlate positively and play an important role in the sorption of PCBs. Also, a decrease in the ratio of Si:(Al + Fe) was noticed to have a positive impact on the sorption of PCBs. This is the first study done on this river to critically evaluate the porewater–sediment distribution and transportation of PCBs. Sorption efficiency of sediments of known physicochemical properties similar to this study area can be predicted by the sorption results of the present study.

In this study, the pollution levels, sources, and ecological risks associated with five selected heavy metals (chromium, copper, iron, lead, and zinc)were evaluated in surface water, soil, and sedi?ment systems along the Isipingo River, KwaZulu-Natal, South Africa. The surface water, soil and sediment samples collected along the river, were preserved, transported, and stored followed the stan?dard procedures. Soil and sediment samples were digested for heavy metal determination using a microwave digestion system. The digested samples were quantitatively analysed using an induc?tively coupled plasma optical emission spectrometer (ICP-OES). The results demonstrate that majority of the targeted heavy metals were found below the detection limits in surface water except for iron (Fe), which was found within the concentration range of 9.54 to 46.76 ��g/L. Lead was found below the detection limit in water, soil, and sediment samples, while other heavy metals were within the range not detected(ND)to 0.222 ��g/kg dry weight and 0.212 ��g/kg dry weight in soil and sediment respectively. The ecological risk assessment of the studied metals in soil and sediment systems from this riversignified that water from this river had less probable potential adverse effects on both animals and humans as well as benthic organisms.

Background and objective: Plant-based fermented foods containing favorable micro-organisms have been used to improve diets. Starter microorganisms may produce toxic compounds that are hazardous to consumers. Brine shrimp lethality test is a convenient and appropriate assay to check toxicity of samples. The aim of this study was to investigate toxicity of pasteurized coconut beverages at 70°C, 80°C and 90°C for 25, 15 and 5 min, respectively, and unpasteurized coconut beverages fermented by Lactococcus lactis against Artemia salina nauplii. Material and methods: After extraction of coconut beverages fermented by Lactococcus lactis using methanol, cytotoxicity was assessed using (lethality concentration). Newly 10 hatched Artemia salina nauplii were transferred into various concentrations (in replicates) of the fermented sample extracts. After 24 h, survived Artemia salina nauplii were counted and lethality concentration was assessed. The brine shrimp lethality test was used to investigate sample toxicity at various doses from 1 to 500 µg ml-1 at various time intervals. Results and conclusion: The fermented extracts included low larvicidal potential against Artemia salina nauplii. Correlations were reported between the extract doses and percentage mortality of nauplli brine shrimp. The pasteurized fermented extracts were less toxic and cheaper. Interestingly, starter culture, fermentation, thermal treatment and time contributed to breaking down of hydrolysable tannins and larger polyphenolic compounds, producing smaller compounds with lower toxicity responses in brine shrimp lethality test. The four probiotics beverage extracts included non-cytotoxic activity as presented by low mortalities in brine shrimp lethality test. In conclusion, these extracts can be used to justify probiotic production of beverages. Conflict of interest: The authors declare no conflict of interest.

The concentration levels of selected trace metals in coal sam-ples collected from three different locations, namely Okaba coal deposit Kogi State, Onyeama coal deposit and Ribadu both in Enugu state, were investigated in this study.Method: The representative coal samples were analysed for the presence of trace metals such as Cadmium, Chromium, Lead and Copper using an Atomic Absorption Spectrophotometer.Result: The mean concentrations of 0.043 �� 0.007, 0.020 �� 0.006, 0.032 �� 0.006 and 7.245 �� 0.557 (mg/kg) were observed for the selected metals. The concentration of the selected metals investigated with the exception of Lead was found to be above detection limit for EPA ��� NBS standard and compared to the previous work done globally.Conclusion: The emission of coal has been attributed to the release of critical heavy metals such as Cadmium, Chromium, Lead and Copper, into the environment thereby posing a threat to human health and endangering the ecosystem

The significance of soil mineral properties and secondary environmental conditions such as pH, temperature, ionic strength and time in the partitioning of eight selected polychlorinated biphenyl (PCB) congeners between aqueous solution and soil particles with different grain sizes was studied. The mineral properties of a model soil sample were determined, and Brunauer-Emmett-Teller (BET) adsorption-desorption isotherms were employed to observe the surface characteristics of the individual modeled soil particles. Batch adsorption experiments were conducted to determine the sorption of PCBs onto soil particles of different sizes. The results revealed that the sorption of PCB congeners onto the soil was dependent on the amount of soil organic matter, surface area, and pore size distribution of the various individual soil particles. Low pH favored the sorption of PCBs, with maximum sorption occurring between pH6.5 and 7.5 with an equilibration period of 8hr. Changes in the ionic strength were found to be less significant. Low temperature favored the sorption of PCBs onto the soil compared to high temperatures. Thermodynamic studies showed that the partition coefficient (Kd) decreased with increasing temperature, and negative and low values of ΔH° indicated an exothermic physisorption process. The data generated is critical and will help in further understanding remediation and cleanup strategies for polluted water.

Triclosan (TCS) and triclocarban (TCC) are antimicrobial agents that have been used in personal care and consumer products in the past decades. In this study, influent, effluent, and sludge samples collected in selected wastewater treatment plants across the Durban metropolis were qualitatively and quantitatively investigated. It was revealed that the concentration of TCS ranged from 1.906 to 73.462 µg/L, from 1.732 to 6.980 µg/L, and from 0.138 to 2.455 µg/kg in influent, effluent, and sludge samples, respectively. The concentrations of TCC were found to be between 0.320 and 45.261 µg/L

The role of initial aqueous humic acid concentrations (dose), as well as secondary environmental conditions on the sorption of PCB congeners PCB 28, 52, 77, 101, 105, 138, 153, and 180 onto soil particle grain sizes, was investigated in this study. Scanning electron microscopy equipped with energy dispersive X-ray and Fourier transform infrared spectroscopy were used for the internal morphology and qualitative elemental analysis, as well as identification of possible functional groups found in commercial HA. Batch adsorption experiments were used for sorption studies. The results showed that the sorption of PCBs onto soil decreased with an increase in the aqueous HA concentrations. The adsorption of the selected PCBs onto the soils was found to decrease with an increase in the solution pH of humic acid. Thermodynamic studies showed that the partition coefficient values increased with an increase in solution temperature. All the standard free energy were negative indicating the spontaneity and feasibility of the sorption process with positive and high enthalpy and entropy values of the system. The sorption was best fitted with the Freundlich isotherm with the intensity parameter 1/n found to be greater than 1. The outcome of this study revealed that secondary pollution of river water may possibly be altered depending on variations in the environmental conditions such as pH and temperature. The presence of organic pollutants in alkaline soils having less organic matter content could increase the chances of leaching of organic pollutants causing groundwater contamination.

Organochlorinated pesticide (OCP) concentrations were evaluated in sediment, soil and surface water of the Msunduzi River as well as the influent, effluent and biosolids from the Darvill wastewater treatment plant (WWTP) of Pietermaritzburg, South Africa. Samples were extracted with dichloromethane using an ultra-sonication method, and cleaned up using multilayered silica gel and analysed using gas chromatography-mass spectrometry. The results showed that all 13 selected OCPs were detected in all the environmental media as well as in the wastewater treatment plant samples. The results revealed that the OCP concentrations along the sites varied based on the anthropogenic activities of the area. The influent of the Darvill WWTP and Du Toit (DUT) site were found to be the most polluted sites. The results from the winter sampling showed highest concentrations of OCPs compared to the spring season. Sediment was found to contain significant amounts of all the selected OCPs with water samples containing the lowest concentrations for both winter and spring seasons. Among the OCPs evaluated, dichlorodiphenyltrichloroethane (DDT) and its metabolites were predominant in all.

The lack of information and the need for knowledge on the organic pollutants within the area of KwaZulu-Natal together with the global problem of water supply have prompted our investigation into the analyses of eight polychlorinated biphenyl (PCB) congeners in the Msunduzi River of KwaZulu-Natal, South Africa. Soil, sediment, and water samples were collected at ten different sites along the river during winter and spring seasons. Soil and sediment samples were extracted using ultra sonication with dichloromethane while water samples were liquid-liquid extracted using dichloromethane. All sample extracts were cleaned-up using a multi-layer silica gel column and analyzed with gas chromatography-mass spectrometry. Quality assurance measures were also determined. The percentage recoveries for water were 53–128 for all the PCBs analyzed, while sediment recoveries ranged between 69 and 105%. The highest total concentrations of the PCBs in sediment were 214.21–610.45 ng/g dw at the Du Toit sampling site and 30.86–444.43 ng/g dw basis at the wastewater treatment inlet for winter and spring, respectively. Soil PCB concentrations were 76.53–397.75 ng/g dw at the Msunduzi Town sampling site and 20.84–443.49 ng/g (dry weight) at the Du Toit sampling site for winter and spring, respectively. In addition, high PCB concentrations were found in effluent of the wastewater treatment inlet compared to other sampling sites, which ranged between 0.68–22.37 and 2.53–35.69 ng/mL for winter and spring seasons, respectively. In all the sampling sites selected for this study, Du Toit afforded the highest PCB concentration levels and the lowest was after chlorination at the Darvill wastewater treatment plant. The results presented are new and it is the first study of organic pollutants such as PCBs that has been carried out on this river.