During the last few decades, sedimentary carbons gain great concerns of research interest among the scientific committee worldwide due to their adverse impact on aquatic chemistry, ecology, and hence human health along with global climate change. In the present study, we investigated the spatial distribution of mass concentration of sedimentary carbon (viz. black carbon: BC, and its components, char and soot) along with their burial fluxes in the surface sediments of the South Yellow Sea (SYS). The concentration of sedimentary carbon is measured by using an emerging method of thermal/optical reflectance. The observed BC concentration is found in the range of 0.02–1.02 mg g⁻¹ with a mean value of 0.49 ± 0.26 mg g⁻¹. The mean burial fluxes of BC, char, and soot also have a similar spatial variation to their concentration with the mean value along with relative standard deviation (in bracket) 22.43 ± 12.49 (~ 56%), 5.90 ± 3.99 (~ 68%), and 16.53 ± 10.67 (65%), respectively. Relatively lower value of char/soot ratio, i.e., 0.48 ± 0.22, indicates the dominance of soot in surface sediments that could be mainly derived from the fossil fuel combustion which is further confirmed from emission inventory data suggesting maximum contribution, i.e., ~ 66–80%, of the total BC emission emitted from residential and industrial emission sources. The back trajectories analysis revealed a significant impact of long-range transportation on BC concentration in the surface sediments of SYS. Further study of BC concentrations in sea sediments and their interaction with other organic/inorganic compounds in continental shelves is highly needed for a better understanding of the global carbon cycle.

Fluoride (F) and cadmium (Cd) are two common water pollutants. There is low information about their co-exposure in low doses. So, in this study, we evaluated the combination effects of non-toxic doses of F and Cd and the possible mechanism of their combined interaction. Male rats were exposed to non-toxic doses of sodium fluoride (30 mg/l) and/or cadmium chloride (40 mg/l) in drinking water for 6 weeks. Then, liver tissues were separated and several factors including oxidative stress, mitochondrial toxicity, inflammation, apoptosis, and biochemical and histopathological changes were evaluated. Cd and F alone did not induce any significant changes in evaluated factors compared to control group, while significant elevation in liver enzymes as well as histopathological changes were observed in rats treated with F+Cd. Also, a remarkable increase in oxidative stress markers including reactive oxygen species, lipid peroxidation, and protein carbonyl and also decreasing glutathione and superoxide dismutase levels were detected following co-exposure to F and Cd. Furthermore, a combination of F and Cd resulted in mitochondrial dysfunction, swelling, as well as a reduction in mitochondrial membrane potential in isolated liver mitochondria. On the other hand, TNF-α, IL-1β, and NF-kB inflammatory genes were upregulated in the liver after combined exposure to F and Cd compared to individual treatments. Also, F+Cd treatment increased the Bax expression but decreased the expression of Bcl-2 significantly. These findings suggest that Cd and F can potentiate their individual toxic effects on the liver tissue through disruption of the cellular redox status, inflammation, and apoptosis pathway.

Effective coastal aquifer management typically relies on numerical models to analyze the seawater intrusion (SI) process. Before using groundwater simulation models to predict the extent of SI in the future, preparing input data is an extremely necessary and important step. For precipitation and sea-level rise (SLR), which are two of the most influential factors for SI, it is difficult to precisely forecast their variations. Current studies of using numerical models to predict future SI often overlook the uncertainty of these two factors. This can result in compromised predictions of SI. In this study, a three-dimensional variable-density groundwater simulation model was established for a coastal area in Longkou, China. Then, the Monte Carlo method was applied to perform uncertainty analysis for the input data of precipitation and SLR of the SI model. In order to reduce the huge computational load brought by repeated invocation of the SI model during the process of Monte Carlo simulation, a surrogate model based on a multi-gene genetic programming (MGGP) method was developed to replace the SI simulation model for calculation. A comparison between the MGGP surrogate model and the Kriging surrogate model was carried out, and the results show that the MGGP surrogate model has a distinct advantage over the Kriging surrogate model in approximating the excitation-response relationship of the variable-density groundwater simulation model. Through statistical analysis of Monte Carlo simulation results, an object and reasonable risk assessment of SI for the study area was obtained. This study suggests that it is essential to take the uncertainty of precipitation and SLR into account when modeling and predicting the extent of SI.

The phenol removal by adsorption through the guava tree bark has been studied in this research. The surface characterizations of the guava tree bark were assessed through BET, FTIR, and SEM apparatus. The phenol removal percentage was investigated in batch experiments taking phenol content (30–150 mg/L), time (30–180 min), pH (4–9), adsorbent dose (1–6 g/L), and temperature (30–50 °C). The maximum percentage of phenol removal was obtained at 90.67% at the phenol concentration of 30 mg/L, the contact time of 120 min, pH of 7, adsorbent dose of 4 g/L, and temperature of 50 °C. The kinetic study indicated that the second-order was superior to the first order. The isotherm study exhibited that the Freundlich isotherm fitted best among the Langmuir, D-R (Dubinin-Radushkevich), and Temkin isotherms. The value of adsorption energy evaluated by the D-R isotherm supported physical adsorption; however, the mechanism seemed to be weaker since the correlation coefficient of the D-R model was found to be quite less than the correlation coefficients of other isotherm models. The adsorption mechanisms through film diffusion and chemisorption were well established as tested by the Reichenberg model, the Elovich model, the Fick model, the Furusawa and Smith model, and the Boyd model. The adsorption thermodynamics concluded that the adsorption method supported endothermic, random, and spontaneous. The scale-up design, the procedure for safe disposal of spent adsorbent, and the regeneration of the adsorbent were deliberated in this research. The research determined that the guava tree bark is suitable for the removal of phenol from wastewater.

This study investigated the potential of horizontal subsurface flow constructed wetlands (HSSF-CWs) and open raceway ponds (RWPs) operated under different regimes (plants, impregnated activated charcoal (IAC), and algae) for long-term nitrogen removal to control eutrophication problems. For experimental purposes, five mesocosms HSSF-CWs and two RWPs were set up in Wuxi, China, a temperate climate zone. Three HSSF-CW units were cultivated with different regions’ plant species including Nasturtium officinale, Juncus effusus, and Brassica juncea, whereas the one unit packed with IAC and the fifth was left as a control, while two species of algae (Spirogyra and C. pyrenoidosa) were cultured in RWPs. All the amendments tested in this study were almost equally effective for long-term nitrogen removal. The results demonstrated that more than 75.7, 88, and 66%, removal of TN, [Formula: see text]–N, and [Formula: see text]–N was achieved by the HSSF-CWs, packed with IAC and N. officinale. Concerning RWPs, both algal species showed almost similar results but slightly lower than others, which may be attributed to the less compatibility with the environment. It was observed that nitrogen removal performance was higher in the winter-spring (March–April) season as compared with winter (January–February). Moreover, all plants, particularly N. officinale growth, were quite steadier than others. The present study validates the impression that both treatment systems were potentially effective in long-term nitrogen removal from sewage and could be considered beneficial to control the eutrophication. Graphical Abstract

The food industry is considered to be one of the greatest sources of environmental contamination produced by dyes. Moreover, a large number of commercial food dyes and their by-products have been shown to be toxic, having chronic effects on human health. The search for efficient processes with which to treat these compounds is, therefore, necessary. In this work, the photo-peroxidation and photo-Fenton processes using UV-C and sunlight radiations were evaluated in order to degrade two synthetic dyes commonly found in food industry wastewater, sunset yellow and tartrazine, in an aqueous mixture. The preliminary results showed that the photo-Fenton/UV-C system was the most efficient. The ANOVA analysis results indicated a good fit of the model. The higher degradations were obtained using 50 mg L⁻¹ of [H₂O₂], 1 mg L⁻¹ of [Fe], a pH of 3.5, and a lower surface area/volume ratio (0.02 cm² mL⁻¹). In the kinetic study, a good fit was found for the kinetic model proposed by Chan and Chu. Degradations higher than 99% and 78% were obtained for the chromophore and aromatic groups, respectively, in 180 min. Toxicity tests showed that post-treatment samples did not interfere in the development of Lactuca sativa seeds and Escherichia coli and Salmonella enteritidis bacteria strains. The photo-Fenton/UV-C system can, therefore, be considered an efficient treatment for the degradation of the mixture of sunset yellow and tartrazine dyes under the conditions evaluated.

Oil pollution caused by heavy shipping traffic in the Baltic Sea could be removed by the help of highly porous aerogels made from the waste. These could be produced from environmentally friendly cellulose, e.g., from paper waste, but would have to be hydrophobized for oil sorption. Such a cellulose aerogel was investigated in this research work. Six types of aerogel with 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 wt% cellulose with porosities in the range of 96–98% stabilized by unsaturated polyester as cross-linker have been produced. Aerogel’s sorption capacity as well as its regeneration for sorption of crude oil, marine diesel oil, and biodiesel sorption from water surface and mechanical strength has been estimated. It was found out that crude oil sorption capacity reach 29.67 ± 0.39 g g⁻¹, biodiesel—29.07 ± 0.26 g g⁻¹, while marine diesel oil—26.26 ± 0.39 g g⁻¹. The aerogel with 0.5 wt% cellulose shows the best sorption properties after 10 cycles of the sorption.

The continuous exposure to conventional pesticides leads to severe health and environmental issues especially at prenatal stage during developmental period. Herein, we aimed to investigate the anomalies due to repeated exposure of pyriproxyfen in pregnant female mice and their neonates. Twenty-four pregnant female mice were repeatedly administered with pyriproxyfen at 30, 100, 300, and 1000 mg/kg by oral gauge from gestation day (GD) 7 to gestation day 17 and six females were given distilled water in the control group. All the live pups were euthanized at postnatal day (PND) 7 and their organs (heart, liver, kidney, and brain) were dissected out, weighed, and assessed for further histopathological examinations. The results exhibited a significant (P < 0.001) decrease in the body weight gain of all treated pregnant mice in comparison to the controls and a significant increase in the gestational length was observed in group IV (P < 0.01) and group V (P < 0.001). In addition, no live pups were born in groups IV and V and one pregnant female mouse was also found dead in both treatments. The body weights of the pups were significantly decreased in group II (P < 0.05) and group III (P < 0.001) and the relative organ (liver, heart, and kidney) weight of the pups was increased significantly (P < 0.001, P < 0.01, P < 0.05) due to prenatal exposure in group II as compared to group I. The relative brain weights of the pups were decreased significantly (P < 0.001) in groups II and III as compared to group I. The liver, kidney, heart, and brain sections exhibited various histological alterations in groups II and III by hematoxylin and eosin staining. Furthermore, immunohistochemical staining of the coronal sections of pup’s brain showed significant (P < 0.001) reduction in cortical radial thickness and total neural count in group II and III as compared to group I. Therefore, the prenatal exposure to pyriproxyfen provoked the damage to various organs in mice offspring and an increase in fetal death at higher doses.

A new eco-friendly compound was prepared for the treatment of textile wastewater containing mixed dyes with various ranges of toxicity. Porous silica was extracted from a black liquor by-product using a simple method and characterized by porous morphology (the pore size ranged between 12 and 41 nm). The silica is the main corrosive agent present in the black liquor; thus, the extraction of silica from the black liquor was considered detoxification process. The extracted porous silica was used as a precursor material to prepare the hybrid material based on polyvinyl alcohol (PVA) as a binder polymer and functionalized by nicotinic acid. The multifunction prepared hybrid was characterized by FT-IR, TGA, DTGA, SEM, and EDX. The porous size of the prepared hybrid varied from 96 nm to 620 nm and presents a high thermal stability in comparison with its parent materials. The adsorption of cationic and anionic dyes was carried out. The adsorption kinetics parameters were fitted with pseudo-first-order and pseudo-second-order kinetic models for methyl orange (MO) and methylene blue (MB), respectively. The adsorption parameters indicated that the Langmuir model is better to describe the adsorption of dyes on the hybrid material. The maximum adsorption capacity was 484 and 771 mg/g for MO and MB, respectively.

Due to the serious pollution and great harm of steel pickling waste liquor, the treatment of the waste liquor with high concentration of iron ion has been a problem in a lot of countries around the world. A simple electrochemical method is proposed for recovering iron from steel pickling waste liquor with graphite plates as electrodes. This study investigated the effects of reaction parameters on the concentration of residual total iron (TFe) in steel pickling waste liquor, including initial pH, reaction temperature, electrode distance, current density, and electrolytic time. Under the optimal reaction condition, the removal efficiency of TFe was 99.98%. The obtained precipitates were measured by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. It was found that the precipitates were high purity of Fe₃O₄ with small amount of γ-Fe₂O₃. This method will provide an effective and potential solution for resource recycling of steel pickling waste liquor.