Chlorination in a drinking water treatment plant is the critical process for controlling harmful pathogens. However, the reaction of chlorine with organic matter forms undesirable, harmful, and halogenated disinfection by-products. Carbonaceous disinfection by-products, such as trihalomethanes (THMs) and haloacetic acids (HAAs), are genotoxic or carcinogenic and are reported at high concentration in drinking water. This study is aimed at developing a mathematical model for predicting concentration levels of THMs and HAAs in drinking water treatment plants in South Korea because no previous attempts to do so have been reported for the country. The THMs concentration levels ranged from 29 to 39 μg/L, and those for the HAAs from 6 to 7 μg/L. Multiple regression models, i.e., both linear and nonlinear, for THMs and HAAs were developed to predict their concentration levels in water treatment plants using datasets (January 2015 to December 2016) from three treatment plants located in Seoul, South Korea. The constructed models incorporated principal factors and interactive and higher-order variables. The principal factor variables used were dissolved organic carbon, ultraviolet absorbance, residual chlorine, bromide, contact time, chlorine dose and temperature for treated water, and pH for both raw and treated water at the plant. The linear models for both THMs and HAAs were found to give acceptable fits with measured values from the water treatment plants and predictability values were found to be 0.915 and 0.772, respectively. The models developed were validated with a later dataset (January 2017 to July 2017) from the same water treatment plants. In addition, the models were applied to two different water treatment plants. Application and validation results of the constructed model showed no significant differences between predicted and observed values.

The environment is seriously affected by the release of hazardous heavy metals from the industries. The transformation of aquatic weeds into valuable nanosorbent has been considered as effective and efficient material in the wastewater treatment process. The aim of the study is to analyze the potential of nano-EC and nano-LM for the removal of chromium(VI) and nickel(II) ions. The characteristics of nanosorbent were analyzed using Fourier transform infrared spectroscopy (FTIR), Brunauer Emmett-Teller analysis (BET), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and thermo gravimetric analysis (TGA), respectively. Adsorptive performance of nanosorbent was studied with respect to pH, contact time, nano adsorbent dosage, and metal ion concentration. The maximum monolayer adsorption capacity of Cr(VI) and Ni(II) with respect to nano-EC was found to be 79.04 mgg⁻¹ and 85.09 mgg⁻¹, respectively. Adsorption isotherm and kinetic studies were performed and it was reported that adsorption isotherm follows Langmuir model with regression coefficient R² > 0.9 for nano-EC and nano-LM respectively. The pseudo-second order model was found to fit well with experimental data. Experimental results suggested that nano-EC can be considered as a suitable nanosorbent for the removal of Cr(VI) and Ni(II) ions from effluents.

Powdered activated carbon (PAC) has been utilized for sorptive remediation of environmental sites contaminated with various organic chemicals. In the present study, time-dependent sorption/desorption characteristics of the α- and β-isomers and a sulfate-metabolite of endosulfan (ED) were investigated in PAC-amended soils to determine the optimal PAC amendment dosage. Subsequently, ED phytoavailability to soybean (Glycine max Merr.) plants were examined in the presence or absence of PAC under restricted laboratory conditions. Based on the results of sorption/desorption tests, the optimal dosage of PAC amendment for ED-contaminated soils was determined as 1% (w/w), and at this dosage, all ED residues were sorbed completely onto the PAC-amended soils without any desorption. In soil amended with 1% PAC, the extents of ED accumulated by soybean plants were reduced by 89.4–100.0% within 20 days compared to those extents observed in unamended controls. Moreover, PAC treatment precluded the formation of the toxic metabolite ED-sulfate in either the soil or soybean plants. Therefore, PAC amendment in ED-contaminated soils could be highly effective for limiting uptake of ED into plants from contaminated soil and may be useful as an alternative method to produce safe food resources from contaminated arable soils.

Here, Box-Behnken design (BBD) approaches were utilised to optimise synthesis methodology for the chitosan-calcite rich adsorbent (CCM) made from fishery-food waste material (crab carapace), using low-temperature activation and potassium hydroxide (KOH). The effect of activation temperature, activation time and impregnation ratio was studied. The final adsorbent material was evaluated for its phosphorus (P) removal efficiency from liquid phase. Results showed that impregnation ratio was the most significant individual factor as this acted to increase surface deacetylation of the chitin (to chitosan) and increased the number of amine groups (–NH₂) in the chitosan chain. P removal efficiency approached 75.89% (at initial P concentration of 20 mg/L) under optimised experimental conditions, i.e. where the impregnation ratio for KOH:carapace (g/g) was 1:1, the activation temperature was 105 °C and the activation time was 150 min. Predicted responses were in good agreement with the experimental data. Additionally, the pristine and CCM material were further analysed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Brunauer-Emmett-Teller technique (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Characterisation showed enhancements in surface chemistry (introducing positively charged amine groups), textural properties and thermal stability of the CCM.

Naphthalene (NAP) is found as a pollutant in water, soil, and air, and adsorption is the most prominent removal process of this compound, among the methods studied. A study concerning the types of adsorbents and the parameters with the greatest influence on the adsorption process is interesting to direct future works on new adsorbents. The use of multivariate data analysis tools becomes an appealing way to compile data obtained from bibliographic reviews and to establish a behavior in NAP adsorption. This work aims to evaluate the parameters with greater influence on NAP adsorption process regarding adsorption capacity (qeₑₓₚ) with the principal component analysis (PCA), and to group common NAP adsorbents by chemical characteristics through hierarchical cluster analysis (HCA). The variables qeₑₓₚ, S, [NAP]₀, T, CT, and [Ads] were used to perform PCA with correlation matrix. For the HCA, the variables S, [NAP]₀, T, CT, and [Ads] with average linkage method (UPGMA) and Euclidean distance were used. Through PCA, it is possible to infer that S and [NAP]₀ are the factors with greater influence in qeₑₓₚ of NAP, while T, CT, and [Ads] have little correlation. PCA also shows that activated charcoal is the adsorbent with higher qeₑₓₚ. HCA grouped the adsorbents into four groups by their chemical classes, except group A. Both PCA and HCA methods show themselves as potential tools to evaluate a data set of NAP adsorption processes.

The freshwater mollusk, Melanoides tuberculata, contains bioconcentration trace metals in its tissues from the surrounding area. M. tuberculata was used as a bioindicator for pollution with seven trace metals (Mn, Fe, Ni, Cu, Zn, Cd, and Pb) accumulated in snail soft tissues near Bahr El-Baqar and El-Serw agricultural drains of industrial activities in Port Said and Damietta, respectively. The biota sediment accumulation factors (BSAF) in this study reveals that all the soft tissues of the M. tuberculata snails were macro-concentrators with the exception of Ni; it was deconcentrated, and thus provides that the selective tissues as good biomonitors. The bioconcentration factor (BCF) showed the highest concentrations of Fe and Cu in the soft tissues of the M. tuberculata snail, which has the potential to be used as a biomonitoring agent for Fe and Cu contamination of the water.

Natural halloysite nanotubes (HNTs) with a hollow lumen have been widely applied in many fields, such as water purification, drug carriers, cosmetics, antibacterial, and scaffolds for tissue engineering. However, their in vivo toxicity is still largely unclear. The aim of this study is to evaluate sub-chronic oral toxicity of HNTs in the small intestine of mice. The results demonstrated that oral HNTs at low dose (5 mg/kg) for 30 days promoted mouse growth with no obvious adverse effect on the small intestine. The promotive effect on mouse growth disappeared after cessation of oral administration of HNTs. Oral HNTs at high dose (50 mg/kg) for 30 days induced aluminum (Al) and silicon (Si) accumulation and oxidative stress in the small intestine, which caused significant increases in the levels of cyclooxygenase-2 (COX-2) and nitric oxide synthase (iNOS) and inflammatory response and iNOS-mediated damages in the organ. Oral HNTs-induced changes in the small intestine at high dose were not observed after a 30-day recovery period. These findings provided the first evidence that oral HNTs-induced sub-chronic toxicity in the small intestine was reversible. The results suggest that HNTs at low concentration in environments have no adverse effect on mice, while there are health risks to mice under severe contamination by HNTs.

Pardosa pseudoannulata (Araneae: Lycosidae), as an important predator of crop pests, has served as a strong driver for ecological regulation of pests. Cadmium (Cd) is a toxic heavy metal widely distributed in the soil in China, which not only seriously pollutes the ecological environment, but also poses a great threat to the survival of organisms. Palpal bulbs are the genital organs of male spiders, playing an important role in reproductive physiology. However, the effects of long-term Cd stress on the genital organ of the primary pest predator were poorly understood. Therefore, we investigated the Cd effect on the male palpal organ of P. pseudoannulata at morphological and gene expression levels. The results showed that no obvious difference in the morphology between the Cd-treated and control groups was observed, but cell adhesion was affected at molecular level. Transcriptome sequencing analysis revealed that under long-term Cd stress, the biological processes including cell-cell adhesion via plasma-membrane adhesion molecules, cell-cell adhesion, and homophilic cell adhesion via plasma membrane adhesion molecules were the top three differentially expressed terms (p-adj < 0.001), and 51 unigenes were annotated into cadherin-related proteins, such as protocadherin, cadherin-87A, and cadherin-96Ca, among which, 18 unigenes were significantly upregulated under the Cd stress. Our outcomes indicate that the differentially expressed genes involved in cell adhesion may explain the negative effects of Cd stress on the spider genital organ, and the comprehensive transcriptome dataset will also provide a profound molecular information of the genital organ of P. pseudoannulata.

Land use/land cover (LULC) changes impact the structure and functioning of ecosystems, which consequently influences the provisioning of a range of ecosystem services (ES). There is a growing consensus regarding the merit of integrating the evaluation of ES into regional policy planning. The Yangtze River is the world’s third longest and supports more than 6% of its population. However, assessing the potential impacts of different resource management policies upon ES is complicated in the Yangtze basin. To remedy this, here we designed a scenario analysis-based approach that used remotely sensed data and GIS (geographic information system) to analyze the relationships between ES (i.e., water flow regulation, water purification) and policies envisioned to improve human welfare in the Chongqing municipality, in the upper reaches of the Three Gorges Reservoir Area (TGRA) in the Yangtze basin. This watershed area has high population density and suffers from severe flood hazard and critical pollution issues. The GEOMOD modeling technique was used to predict LULC changes according to policy planning alternatives, producing scenarios by 2050 for the TGRA watershed. The GIS-based ES model (InVEST model) was developed as a tool to inform the decision-making process with the intention of aligning conservation measures with economic development. We examine policy effectiveness by comparing three scenarios for 2050: scenario-1 maintains the current policy, with no considerations of ES; scenario-2 integrates ES into policy planning; and scenario-3 integrates ES into policy planning considering the needs of local people. Our scenario-based LULC change analysis showed that the land with large increases in water flow regulation (i.e., values ≤–3000 × 10³ m³ km⁻²) were scattered over the entire study area, while phosphorus reduction (i.e., values ≤ –30 kg km⁻²) were located mainly along rivers in all scenarios. Scenario-2 and scenario-3 are based on policies aiming at enhancing ES provisioning; for these, the projected ecological risks of water pollution are significantly reduced (39.97% and 37.58%, respectively). Total net changes of the investigated ES under scenario-2 or scenario-3 were almost double that occurring under scenario-1. Although scenario-2 and scenario-3 showed a near-equal total net change, water purification under scenario-2 was the greatest relative to forest expansion. However, scenario-3 offered the best future environmental development scenario, as it accounted for the demand and supply characteristics of water yield and purification in different regions. The water purification service made the greatest contribution to positive and negative effects (26%–47% and -7%, respectively) on ES provisioning. Linking water purification service to policy planning would effectively improve the overall ES. These scenario forecasting results will help the Three Gorges Dam to gain more ecological benefits via improvements to water flow regulation and the effective alleviation of degraded water quality in heavily populated regions in the Yangtze basin.

The optimal allocation of sediment resources needs to balance three objectives including ecological, economic, and social benefits so as to realize sustainable development of sediment resources. This study aims to apply fuzzy programming and bargaining approaches to solve the problem of optimal allocation of sediment resources. Firstly, Pareto-optimal solutions of multi-objective optimization were introduced, and the multi-objective optimal allocation model of sediment resources and fuzzy programming model was constructed. Then, from the perspective of multiplayer cooperation, the optimal allocation model of sediment resources was transformed into a game model by using Nash bargaining, and Nash bargaining solution was obtained as the optimal equilibrium strategy. Finally, the influence of different disagreement utility points and bargaining weights on the results was discussed, and the results of Nash bargaining and fuzzy programming methods were compared and analyzed. Results corroborate that Nash bargaining can achieve the cooperative optimization of multiple objectives with competitive relationship and obtain satisfactory scheme. Disagreement utility points and bargaining weights have a certain impact on the optimization results. The solution of fuzzy programming is close to that of Nash bargaining, which provides different ideas for multi-objective optimization problem.