The occurrence of microplastics in the aquatic environment has been reported around the world; however, their effects on freshwater oligochaetes are unknown. In this research, we investigated the toxic effects of polyethylene microplastics (MP), size between 40 and 48 μm, on the aquatic worm Allonais inaequalis. We applied the bioassays considering 24 °C as standard temperature and thermal stress of 19 °C and 29 °C, associated with the presence and absence of sediment in short-term and chronic exposures (96 h and 240 h, respectively). MP did not cause significant mortality in short-term exposures and did not affect the reproduction of worms. In addition, when we analyzed whether thermal stress, as well as substrate availability, would have an additional impact on MP toxicity, there were no significant effects. At 29 °C, the individuals reached the highest reproduction rates, whereas at 19 °C the offspring significantly reduced. Moreover, the lack of sediment substantially reduced survival rates after 96 h under 24 °C (p = 0.018). This paper also records for the first time, the ability of microplastic ingestion by a freshwater naidid. Due to its capacity to respond in a short period, adaptation to laboratory cultivation, and representativeness among freshwater aquatic invertebrates, A. inaequalis is presented as a tropical test organism for toxic effect analysis of microplastics, either in conventional exposures or simulated environmental disturbances.

The rapid and efficient determination of heavy metal content in food crops is essential for human health and environmental protection. The use of hyperspectral data has become a popular way to predict heavy metal content in plants; however, many challenges remain. One challenge is that lab conditions differ from actual agricultural production conditions. Another challenge is that spectral data characteristics are not universally applicable to all situations. Therefore, in this study, the field test method was adopted to conduct experiments during the full growth period of wheat, and the spectrum data of wheat canopy were processed by the first derivative method to screen-sensitive spectral bands as the basis for the prediction model of the copper content in wheat. The results showed that the copper content increased with an increase in the soil copper content, and there were dissimilar subtle differences in the spectral reflectance of wheat canopy under different stressed soil copper concentrations; sensitive spectral indices and wavelengths were screened based on good correlation with the copper content in the wheat canopy. Different optimal predicting models in different periods were built and verified. The established linear regression models, which were based on NDVI/SIPI and W728, were the most suitable predicting models during the tillering stage with R² = 0.669 and 0.818; Rg, W741, and multiple bands were the most suitable predicting models during the jointing stage with R² = 0.548, 0.830, and 0.868; the optimal model during the heading stage was based on W480 (R² = 0.625). This study demonstrated that the constructed models had good potential for estimating the copper content in wheat leaves during full growth periods, and this method had the potential to be applied to the actual agricultural production process.

This study examined behavioural intention to dispose of unused medicines using a comprehensive model integrating the theory of planned behaviour (TPB), with knowledge as a driver of personal norms; attitudes, personal norms, and perceived busyness as additional drivers of behavioural intention; and perceived convenience as a moderator. The model was tested with data collected from 204 respondents using the partial least squares technique. Knowledge about the proper disposal of unused medicines was recognized as a strong predictor of personal norms and attitudes towards proper disposal of waste medications. The results showed that attitudes, personal norms, perceived busyness, and perceived behavioural control have significant effects on intention to dispose of unused medicines. Furthermore, perceived convenience moderates the impacts of attitude, personal norms, and perceived behavioural control on intention to dispose of unused medicines. The extended TPB explained 55.7% of the variance of intention to dispose of unused medicines properly. Our results indicate the importance of integrating additional variables into the TPB to enhance its explanatory power in predicting behavioural intention. The results suggest to governments that in order to implement planned programs for proper collection and destruction of waste medication, a plan is needed to enhance public knowledge on the impacts of improper medication waste disposal on the environment, and also that collection points should become accessible for anyone.

The uptake of organic pollutants by agricultural plants and their accumulation in edible parts cause serious health problems to animals and humans. In this study, we used carbon-rich materials, such as biochar (BC), hydrochar (HC), and green compost (GC), to reduce the absorption and accumulation of three pesticides, imidacloprid (IMI), boscalid (BOS), and metribuzin (MET) and two endocrine disruptors, 4-tert-octylphenol (OP) and bisphenol A (BPA), in rocket salad plants (Eruca vesicaria L.). After an experimental period of 35 days, compared to unamended soil, the addition of BC, HC, and GC significantly reduced chemical phytotoxicity, increasing the elongation of the aerial plant parts by 26, 25, and 39%, respectively, whereas GC increased the fresh biomass by 21%. The assessment of residual chemicals in both soil and plant tissues indicated that any amendment was very effective in enhancing the retention of all compounds in soil, thus reducing their uptake by plants. Averagely for the five compounds, the reduction of plant absorption followed the trend BC > HC > GC. In particular, the presence of BC decreased the chemical residues in the plants from a minimum of 71% (IMI) to a maximum of 91% (OP). The overall results obtained encourage the incorporation in soil of C-rich materials, especially BC, to protect leafy food plants from the absorption and toxicity of organic pollutants of a wide range of hydrophobicity, with relevant benefits for consumers.

Nepal’s efforts to reduce manufacturing-related water pollution have faltered because they rely on traditional methods and regulation. We employed an environmentally extended input–output model to establish direct and indirect relations between water pollution and production in 19 Nepalese manufacturing sectors. We identify which are chief emitters of biochemical oxygen demand and total suspended solids. We categorize three sectors as pollution abatement industries (heavy polluters that portend relatively low clean-up costs) and three as pollution prevention industries (polluters responsible for accelerating pollution by inducing the release of pollutants from other linked sectors). We then draw upon statistical analysis to recommend appropriate pollution-reducing incentives or penalties for both categories. We find that incentives to meet discharge standards are effective for pollution abatement industries and that penalties (e.g., polluter pay) are effective in pollution prevention industries because they underpin Nepal’s economy. If these policies do not succeed as desired, emission control policies are warranted.

The objectives of this research were to evaluate the maintenance of water quality when using chitosan foam filters in water recirculation systems during the cultivation of Nile tilapia and to verify the zootechnical performance and the hepatic and branchial histopathological changes, in comparison with the use of biological filter with bioballs. Two Nile tilapia cultivation trials were carried out (trial 1: 35-L tanks; trial 2: 130-L tanks), using six individual water recirculation systems, consisting of a culture tank, decantation tank, submerged pump for recirculation, aeration and external filter. The physical and chemical parameters related to water quality were evaluated every 48 h. At the end of each trial, the fish biometrics was performed to obtain final weight, feed conversion, and survival. In trial 2, the histopathological analysis of the hepatopancreas and gills was performed and the organ index was calculated. The daily averages of the physical and chemical parameters of the water quality, the zootechnical performance of the fish, and the organ indexes of the treatments of trials 1 and 2 were compared by the t test (p ≤ 5%). There were no significant differences in final weight, feed conversion, survival, or organ indexes between treatments (p > 0.05) in relation to the two trials. It was observed that the use of the filter with chitosan foam in the water recirculation systems resulted in lower or equal concentrations of total ammonia, nitrate, and dissolved orthophosphate, and maintained the same or higher alkalinity than in tanks with bioball biological filter. It is recommended to change the chitosan foam every 30 days of cultivation. The use of water recirculation systems with treatment using filters filled with chitosan foam during the cultivation of Nile tilapia is equally effective or better than the use of a biological filter with bioballs.

In this work, an aqueous solution containing industrial dyes consisting of methylene blue (MB), and methyl red (MR) was treated with bio-oxidize grape marc entrapped or not in calcium alginate hydrogels. Experiments were carried out in batch, a room temperature using different concentration of adsorbents and dyes. When dyes were evaluated separately, non-immobilized grape marc hydrogel was unable to remove any MR, whereas when the bioadsorbent was immobilized in calcium alginate beads the removal of MR was around 88%. Contrarily, 98% of MB was removed with both, non-entrapped or entrapped grape marc. Regarding binary mixtures, it was observed that the adsorption of MR was not affected by the presence of MB, whereas the adsorption of MB decreased in high extend on non-entrapped grape marc when MR was present.Adsorption conditions were optimized for binary mixtures using a Box-Behnken factorial design, obtaining theoretical equations that allowed to calculate the removal percentage and capacity of calcium alginate-grape marc hydrogel depending on the concentration of dyes (40–100 mg/L), ratio between bioadsorbent and water stream (0.6–1.2) and adsorption time (10–60 min). The equations obtained revealed that grape marc hydrogel is able to remove 100.0–93.3% of MB and 78.72–57.80% of MR in 10 min in the range of dye and bioadsorbent stablished in the experimental design, being the extraction time the less significant variable. Additionally, the kinetic study showed that pseudo-second-order was the model that better explained the bioadsorption process for both dyes in binary mixtures onto grape marc hydrogel.

Plant species diversity could enhance plant productivity and pollutant removal efficiency in constructed wetlands (CWs). However, the potential importance of plant density for ecosystem functioning has largely been neglected. In this study, we conducted a factorial experiment in which three common plant species were planted in a gradient of species richness (one, two, and three) and seven species compositions at two densities (six and twelve individuals per microcosm). Plant total biomass and total organic carbon (TOC) and total inorganic nitrogen (TIN) removal efficiency were measured to explore the effect of plant species diversity and density on the ecosystem functioning of CWs. Results showed that (1) plant species richness had no significant effect on plant total biomass and TOC and TIN removal efficiency under high and low plant density. (2) There were significant differences in TIN removal efficiency among seven species compositions under low plant density; especially, the presence of Canna indica reduced the TIN removal efficiency. In contrast, species composition and species identity had no significant effect on ecosystem functioning under high plant density. (3) High plant density increased plant total biomass of C. indica monocultures, and also enhanced TIN removal efficiency in mixtures of two species. These results indicated C. indica alone may not be an ideal species for enhancing pollutant removal in constructed wetlands but planting at high density could mitigate its negative effect on ecosystem functioning.

The use of sewage water as an irrigation source can be beneficial in agricultural practices, however, it may result in human health risks due to the consumption of heavy metal(loid)–contaminated food. This study evaluated the suitability of using sewage water (SW), freshwater (FW), and groundwater (GW) for vegetable irrigation in District Vehari. Spinach (Spinacia oleracea) plants were grown in pots irrigated with FW, GW, and SW in different proportions and combinations. The results indicated the substantial lesser buildup of heavy metal(loid)s (As (− 0.8%), Cd (− 38%), Cr (− 6.2%), Cu (− 20%), Fe (− 9.2%), Mn (− 13%), Ni (− 16%), Pb (− 19%), and Zn (−15%)) in soil after S. oleracea cultivation compared to unirrigated soil possibly due to high metal(loid) uptake by S. oleracea. Irrigation with all types of waters resulted in metal(loid) accumulation in S. oleracea predominantly in roots. The combinations of FW, GW, and SW resulted in high metal(loid) accumulation (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the edible S. oleracea leaves than their alone application. Owing to high metal(loid) buildup, plants showed a linear trend in physiological imbalance in terms of reduced pigment content, induction of peroxidation, and oxidation of lipids. The severe oxidative stress was observed in S. oleracea plants under FW and GW irrigation due to high metal(loid) accumulation. The risk indices showed possible carcinogenic risk (CR > 0.0001) and non-carcinogenic risk (HI > 1) from the consumption of metal(loid)-contaminated S. oleracea leaves. Results revealed unsuitability of all waters and their combinations for S. oleracea irrigation. Moreover, this study does not encourage the use of mixed water for vegetable irrigation in Vehari District. Therefore, it is of utmost importance to monitor the quality of irrigation waters to ensure food safety and prevent chronic health risks to the exposed population.

Catalytic desulfurization is favored for its ability to desulfurize low concentrations of SO₂ by generating sulfur without the need for flue gas conditioning or additives. Maintaining reaction efficiency at a low temperature would justify the industrial scale use of this method. To that end, in this study, we modified a previously reported highly efficient CuO-ZrSnO₄ catalyst and investigated its desulfurization performance. The non-thermal plasma (NTP) method was used to enhance the low-temperature efficiency of the catalyst. The desulfurization rate was significantly improved without generating excess heat or by-products in the low-output mode of post-plasma-catalysis-type (PPC-type) dielectric barrier discharge (DBD). In addition, we studied the physicochemical properties of the catalyst (pore structure, physical structure, morphology, electronic properties, and chemical state) under plasma enhancement conditions. The catalyst loaded with 20 wt% Cu and aged at 40 °C exhibited optimum desulfurization performance. This study provides a theoretical foundation for the analysis of plasma-enhanced catalytic desulfurization under low-temperature conditions. Graphical abstract