Spectral characterization, degradation behavior, quenching, and semi-quantification of fluoroquinolone antibiotics in the antibiotic-humic mixture using fluorescence spectroscopy.

Antibiotics, one of the significant emerging contaminants, are intensifying their continual spread out into the environment and affecting human health and the ecosystem in the developing country Bangladesh. This study characterizes widely used fluoroquinolone (FQ) antibiotics, formulates the method to spectrally distinguish them from ubiquitous, and important reactive, adsorbent, and altering catalytic macromolecule humic substances (HS), and further quantifies them using fluorescence spectroscopy. The presence of identical fluorophore at Excitation/Emission = 225-230/285-295 nm wavelength, possession of fluorescence spectra at short emission wavelength (<350 nm) during 275 nm excitation, different emission maxima, and various fluorescing components in antibiotics identified through three-dimensional excitation-emission matrix (EEM) and parallel factor analysis (PARAFAC) models distinguished them from the humic substance as well as from each other. Stern-Volmer equation and its modified version were applied to identify quenching and binding capability, and fluorescence intensity quenching rate of antibiotics and humic in their mixture. Unlike poor and inconsistent quenching mechanisms of humic, FQ antibiotics reduced HS intensity throughout the entire photo-irradiation experiment affirming the functioning of the stable quenching methods. Static quenching of fluorophores was identified from the redshift of excited wavelength on the electronic ground state. Temperature differences during daylight and dark conditions played contrasting roles during the fluorescence quenching of FQ. Unique spectral response at emission wavelength < 350 nm during 275 nm excitation in FQ was considered as its least intensity in the antibiotic-humic mixture and was also used to formulate distinct spectral pattern of each FQ antibiotic. The study also identified the traces of FQ antibiotics with various intensities at different lakes in Bangladesh.

A comprehensive review on the fate and impact of antibiotic residues in the environment and public health: A special focus on the developing countries.

The widespread application of antibiotics in human and veterinary medicine has led to the pervasive presence of antibiotic residues in the environment, posing a potential hazard to public health. This comprehensive review aims to scrutinize the fate and impact of antibiotic residues, with a particular focus on the context of developing nations. The investigation delves into the diverse pathways facilitating the entry of antibiotics into the environment and meticulously examines their effects on human health. The review delineates the current state of antibiotic residues, evaluates their exposure in developing nations, and elucidates existing removal methodologies. Additionally, it probes into the factors contributing to the endurance and ecotoxicity of antibiotic residues, correlating these aspects with usage rates and associated mortalities in these nations. The study also investigates removal techniques for antibiotic residues, assessing their efficiency in environmental compartments. The concurrent emergence of antibiotic-resistant bacteria, engendered by antibiotic residues, and their adverse ecological threats underscore the necessity for enhanced regulations, vigilant surveillance programs, and the adoption of sustainable alternatives. The review underlines the pivotal role of public education and awareness campaigns in promoting responsible antibiotic use. The synthesis concludes with strategic recommendations, strengthening the imperative for further research encompassing comprehensive monitoring, ecotoxicological effects, alternative strategies, socio-economic considerations, and international collaborations, all aimed at mitigating the detrimental effects of antibiotic residues on human health and the environment. PRACTITIONER POINTS: Antibiotic residues are widely distributed in different environmental compartments. Developing countries use more antibiotics than developed countries. Human and veterinary wastes are one of the most responsible sources of antibiotic pollution. Antibiotics interact with biological systems and trigger pharmacological reactions at low doses. Antibiotics can be removed using modern biological, chemical, and physical-chemical techniques.

Bioaccumulation of microplastics in the edible tissues of fish collected from urban lakes of Bangladesh: a potential exposure to public health.

Microplastic (MP) pollution is an emerging environmental problem, due to its universal dispersion. In the present study, we determined the MP pollution in water, sediment, and fish samples of three different urban lakes of Bangladesh to assess the bioaccumulation of MPs from the lake environment to fish's edible (flesh) and inedible tissue (gut), ecological risk and consequent human exposure to MPs by fish consumption. A total of forty-three fishes were collected from Jahangirnagar Co-Operative Housing Society (JCHS), Dhanmondi Lake (DL), and Saturia Thana Lake (MST). The average MP concentration in sediment and water of the lakes is 7588 ± 4353 MPs/kg dry weights; 142 ± 22 MPs/L, respectively. MPs were identified in the edible (2.8-20.2 MPs/g) and inedible (2.27-20.93 MPs/g) tissue of all fish species. The highest number of MPs was observed in the flesh of Labeo bata of the JCHS Lake and in the gut of Catla catla of DL. The most dominant shape of MPs was fiber and fragment, 0.1-0.4 mm was the dominant size range, and blue, purple, and transparent were the dominant colors. The presence of six polymer types was revealed by FT-IR analysis, which were polystyrene, polypropylene, nitrile, ethylene vinyl acetate, high-density polyethylene, and nylon. The concentration of MPs in fish is found to increase with the increment in body weight. The bioconcentration factor (BCF) analysis reveals that among all the fish species, Labeo bata and Oreochromis mossambicus accumulate the highest number of MPs from the lake environment. The pollution load index of MPs indicates that the sampling sites were within hazard levels III-IV. Estimated annual intake reveals that humans will be exposed to the highest number of MPs if they consume the flesh of Labeo bata of DL and JCHS Lake.

Insights on applications of bentonite clays for the removal of dyes and heavy metals from wastewater: a review.

In recent decades, increased industrial, agricultural, and domestic activities have resulted in the release of various pollutants into the aquatic systems, which require a reliable and environmentally friendly method to remove them. Adsorption is one of the most cost-effective and sustainable wastewater treatment techniques. A plethora of low-cost bio-based adsorbents have been developed worldwide so far to supplant activated carbon and its high processing costs. Bentonite clays (BCs), whether in natural or modified form, have gained enormous potential in wastewater treatment and have been used successfully as a novel and cost-effective bio-sorbent for removing organic and inorganic pollutants from the liquid suspension. It has become a sustainable solution for wastewater treatment due to its variety of surface and structural properties, superior chemical stability, high capacity for cation exchange, elevated surface area due to its layered structure, non-toxicity, abundance, low cost, and high adsorption capacity compared to other clays. This review encompasses comprehensive literature about various modification techniques and adsorption mechanisms of BCs concerning dyes and heavy metal removal from wastewater. A critical overview of different parameters for optimizing adsorption capacity and regeneration via the desorption technique has also been presented here. Finally, a conclusion has been drawn with some future research recommendations based on technological challenges encountered in industrializing these materials.

Impact of landfill leachate contamination on surface and groundwater of Bangladesh: a systematic review and possible public health risks assessment.

Dumping of solid waste in the non-engineered landfill is very common in the developing countries. Among the different disadvantages of this kind of landfilling, leachate is the major concern to public health, which is a toxic byproduct generated from the landfill; and can percolate to the ground water and consequently migrate in surface water. Using systematic review on published data, the present study endeavors to compare the leachate contamination potential of four major landfills of Bangladesh, named Amin Bazar, Matuail, Mogla Bazar and Rowfabad; which are situated in 3 of the 6 big mega cities of Bangladesh and assessed the effects of leachate leakage on surrounding water body as well as on human health. This study, for the first time calculated the leachate pollution index (LPI) for the landfill sites of Bangladesh and found that the LPI of Matuail landfill site (19.81) is much higher which is comparable to some polluted landfill sites of India and Malaysia. The concentrations of several potentially toxic metals found in the surface and ground water in the vicinity of the landfill sites were above the maximum permissible limit values of department of Environment, Bangladesh and World Health Organization (WHO). The human health risk index for toxic heavy metals in different vegetables and rice grain showed high health risk potential for Pb, Cd, Ni, and Mn. The total carcinogenic risk for Ni and Pb are found very high in the edible plants near those landfill sites, suggesting the risk of Ni and Pb induced carcinogenesis by the consumption of those plants. The present conditions of surface, ground water and agriculture products near the landfill sites of Bangladesh are much frightening to the biota and local inhabitants. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13201-021-01431-3.

Abundance, characteristics and variation of microplastics in different freshwater fish species from Bangladesh.

Microplastic (MP) contamination in fish species is one of the emerging environmental problems due to the proliferation of plastic pollution in the environment. The occurrence of MPs in the freshwater of Bangladesh is currently unreported, and in contrast to other counties of the world, little is known about the occurrence of this contaminant in freshwater fishes. Hence, this study investigated the abundance, characteristics, and variation of MPs in different commercial freshwater fish species from Bangladesh. This country generates a considerable amount of plastic waste annually, and a significant portion of its remains uncollected. Forty eight fishes from eighteen taxa spanning different feeding zones were collected to observe the difference in MPs ingestion rate among various feeding zones. MPs were found in the gastrointestinal tracts (GIT) of 73.3% of all examined fish samples, which is relatively higher than previously reported studies in other regions. The abundance of MPs was found highest in Mystus vittatus among all of the fish species. Microscopic analyses (polarized light, SEM) revealed that MPs were dominated by fiber in shape and transparent in color. Fourier Transform Infrared analysis (FTIR) showed that polymers found in fish GIT were high density polyethylene, polypropylene-polyethylene copolymer and ethylene vinyl acetate. The results of this study show that demersal fishes presented a higher amount of MPs than registered in benthopelagic and pelagic fishes, indicating the ingestion of plastics in fish may relate to the feeding habitat. However, differences in body weight and length of the fishes were not found to influence the MPs ingestion. Our findings will help to aware people which freshwater fishes and fishes from which feeding zone are more contaminated with MPs to human consumption in Bangladesh.