As carbon emissions are one of the major problems of an emission-generating firm (EGF), there is a dire need to reduce them, and so this study fills this gap in the literature by considering the optimal behavior of environmental policies. This research develops policy measures under a duopoly game model such as carbon emission tax (CET) and subsidy on green investment (SGI). Additionally, we formulate a simulation model to measure the optimal behavior of CET, SGI, and production quantity to maximize profit and carbon emission reduction. The findings indicate that when green investment decreases, the EGFs are better able to pay CET and the government is also capable of providing SGI. Moreover, a lower unit production cost reduces more carbon emissions versus a higher unit production cost. In this way, the government receives revenue due to CET implementation and an EGF obtains revenue due to SGI. Both parties gain benefits at the same time and play important roles in cutting carbon emissions to make the environment clean. This study helps governments in finding their own optimal CET and SGI. An optimal SGI assists decision-makers at reducing carbon emissions and targeting profit maximization.

Ulcerative colitis (UC) is a chronic autoimmune inflammatory disease associated with extensive mucosal damage. Prodigiosins (PGs) are natural bacterial pigments with well-known antioxidant and immunosuppressive properties. In the current study, we examined the possible protective effect of PGs loaded with selenium nanoparticles (PGs-SeNPs) against acetic acid (AcOH)-induced UC in rats. Thirty-five rats were separated into five equal groups with seven animals/group: control, UC, PGs (300 mg/kg), sodium selenite (Na₂SeO₃, 2 mg/kg), PGs-SeNPs (0.5 mg/kg), and 5-aminosalicylates (5-ASA, 200 mg/kg). Interestingly, PGs-SeNPs administration lessened colon inflammation and mucosal damage as indicated by inhibiting inflammatory markers upon AcOH injection. Furthermore, PGs-SeNPs improved the colonic antioxidant capacity and prevented oxidative insults as evidenced by the upregulation of Nrf2- and its downstream antioxidants along with the decreased pro-oxidants [reactive oxygen species (ROS), carbonyl protein, malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), and nitric oxide (NO] in the colon tissue. Furthermore, PGs-SeNPs protected intestinal cell loss through blockade apoptotic cascade by decreasing pro-apoptotic proteins [Bcl-2-associated X protein (Bax) and caspase-3] and increasing anti-apoptotic protein, B cell lymphoma 2 (Bcl2). Collectively, PGs-SeNPs could be used as an alternative anti-colitic option due to their strong anti-inflammatory, antioxidant, and anti-apoptotic activities.

This research aimed to develop a novel composite as a low-cost adsorbent for the removal of nitrate ion from aqueous solutions. The characterization of this composite (composition of red mud with dimethyldioctadecylammonium bromide (DDAB)) was performed by XRF, XRD, FTIR, and BET analyses. The most influential variables on nitrate adsorption, including contact time, solution acidity, adsorbent amount, and temperature were studied. The maximum amount of nitrate adsorbed onto the prepared adsorbent was obtained at pH 5.5 and contact time 30 min. The heterogeneous adsorption occurred during the uptake of nitrate. The results of kinetic study revealed that intra-particle diffusion was the major limitation for nitrate adsorption rate. The values of thermodynamic parameters illustrate the non-spontaneous, associative, and exothermic adsorption process. Increasing the temperature enhances the tendency of the process to non-spontaneously. Research on fixed-bed column has been done under different initial nitrate concentrations. The adsorption capacity of nitrate was increased with an increase in the initial concentration of nitrate. The results of column data were successfully explained using the Thomas and Yoon–Nelson models.

The water in sludge is trapped within the extracellular polymeric substance (EPS) with gelatinous structure, greatly challenging the sludge deep dewatering. In this paper, the effect of the EPS viscoelasticity and the structural characteristics of sludge flocs on water distribution was revealed to provide a highly efficient approach in research on sludge dewatering. After biological, and physical method conditioning, the change of viscoelasticity and sludge network structure before/after EPS extraction was comprehensively explored, together with the sludge dewaterability and water distribution. The results suggested the proportion of capillary water and adsorption water carried in soluble EPS (S-EPS) was 59.17% and 40.83%, and that in tightly bound EPS (TB-EPS) was 54.77% and 45.23%, respectively. By contrast, the capillary water in loosely bound EPS (LB-EPS) accounted for as high as 99.99%. In comparison with raw sludge, adsorption water proportion in TB-EPS and S-EPS was reduced after lysozyme (LZM) or freezing-thaw conditioning, which was ascribed to reduction of EPS viscosity and the weakness of water adsorption capacity. Additionally, the sludge yield stress (τy) value first reduced and then increased with the extraction of EPS. Meanwhile, the consistency coefficient (k) also decreased from 4.23 Pa·sⁿ to 0.006 Pa·sⁿ and then slightly increased after LZM conditioning. This observation indicated the sludge system became sensitive to shearing, and its network structural strength as well as colloid elasticity first weakened and then slightly strengthened. In addition, after LZM or freezing-thaw conditioning, the sludge particle size significantly increased after TB-EPS extraction, while the sludge particle more easily absorbed water molecules, thereby increasing adsorption water and capillary water within the sludge flocs. This phenomenon also resulted in an increasing trend of capillary suction time (CST) after TB-EPS extraction, indicating the deterioration of sludge filtration performance.

The occurrence of ten target pharmaceuticals was investigated in drinking water sources and tap water in a city in the middle reaches of the Yangtze River, including erythromycin (ERY), roxithromycin (RTM), ciprofloxacin (CPX), ofloxacin (OFX), sulfadiazine (SDZ), sulfamethoxazole (SMX), oxytetracycline (OTC), tetracycline (TC), ibuprofen (IBF), and naproxen (NPX). And the corresponding ecological risk for three classes of aquatic organisms and human health risk for different life stages were estimated. Results demonstrated that nine pharmaceuticals except for TC were detected with the frequencies of 20–100% and the concentrations of <LOQ–118.60 ng/L in drinking water sources. Only SMX and IBF were detected quantitatively with the highest concentrations of 0.69 ng/L and 1.28 ng/L in tap water, respectively. The concentrations of the target pharmaceuticals were lower than or comparable with those in other drinking water systems. The spatiotemporal variations of the target pharmaceuticals might be mainly attributed to their usage object, emission amount, and natural attenuation. The overall discrepancy of concentrations between drinking water sources and tap water might indicate the purification effect of drinking water treatment system. Individual pharmaceutical in drinking water resources posed negligible risks to invertebrate and fish; however, ERY, CPX, OFX, and SMX posed high risk to algae. Moreover, pharmaceutical exposure by tap water caused no risk to human health. Nevertheless, the long-term, chronic, and mixed risks of pharmaceuticals and the potential risk of antibiotic-resistant genes should be concerned. This study enriches environmental monitoring data of pharmaceuticals in drinking water sources and tap water, and provides scientific information for emerging pollutants management in drinking water system.

Due to its toxicity and corrosiveness, removal of hydrogen sulfide (H₂S) from landfill biogas is essential in terms of environmental impacts and biogas valorization. This study evaluates the performance of a chemical-biological oxidation process for the purification of biogas. The treatment process consists of two separate phases. The first phase targets the elimination of 50 ppmv H₂S concentration from the gaseous stream by ferric sulfate solution in the chemical absorption/oxidation reactor. This technique was 100% efficient for removing the H₂S at 15 g L⁻¹ ferric iron concentration and empty bed residence time of 7 min. The model validation indicated that the mass transfer limitation is the rate-determining phase in the chemical treatment process. Then, in the second phase, biological oxidation of the produced ferrous sulfate into ferric sulfate took place. The oxidation rates of up to 1 g Fe²⁺ L⁻¹ h⁻¹ and 0.8 g Fe²⁺ L⁻¹.h⁻¹ were achieved in the biological oxidation process with and without adding 0.1% w/v glucose, respectively.

This study aimed to determine seasonal (summer vs. winter) and spatial distribution of the selected heavy elements (HEs) (As, Cd, Co, Cr, Cu, Ni, and Pb) in soil samples collected from a typical Central European town, Novi Sad, Serbia. The highest Pb concentrations were observed in summer because of intensive ground-flushing, whereas Cu had its highest concentration in winter, which may be attributed to traffic emissions. Source characterization and spatial distribution were carried out using cluster analysis (CA), principal component analysis (PCA), variogram calculation and theoretical model fitting, GIS-based geostatistical methods, and positive matrix factorization (PMF) data processing tools. Environmental impact of HEs found in different functional areas demonstrated that the quantified concentrations of Pb, As, Co, and Cu ranked soil as unpolluted to moderately polluted, while the presence of Co, Ni, and Cr classified urban soil as moderately polluted. Pollution load index (PLI) suggested a significant HEs enrichment while the new modified approach to Nemerow integrated risk index (NIRI) indicated high risk, being extreme for some selected locations. Machine learning classifiers were used for the first time to identify the differences between urban soil and dust samples in situations when simultaneous analysis of both matrices was carried out, as well as for temporal distribution (summer versus winter), based on the obtained concentration of HEs. Variogram calculation suggested that the pattern in spatial variability within the system emerged from the combined action of key structural factors (e.g., the parent soil material, landforms and topography, and climate) and random factors related to human activities. The estimated human health risk for two segments of the population revealed that ingestion is the primary route of exposure to HEs for children and adults.

Wetland provides a wide range of ecosystem services with immense value. However, methane (CH₄) emissions adversely affect ecosystem services, and it requires fixation cost. The objective of the present study was to estimate CH₄ emissions and ecosystem services value (ESV) and how much the fixation cost of CH₄ reduces the ESV. Since rice cultivation is a very common practice here, the paddy fields were also incorporated in this study. CH₄ flux and satellite data were employed for estimating the emissions with the help of two-factor (temperature and water availability) model. Global coefficients of ecosystem service value (ESV) that is defined as the monetary valuation of materialistic and non-materialistic services were adapted for estimating the ecosystem service of the CH₄ emitting sources. Results show that during the boro season (pre-monsoon summer paddy cultivation season), average monthly emissions of paddy fields are equal to the wetlands which are 0.16 t/km². During amon season (monsoon paddy cultivation season), this emissions is 0.7 t/km² and 0.53 t/km², respectively, from wetlands and paddy fields. Both wetlands and paddy fields emit a greater amount of CH₄ during amon season than boro season. Behind this seasonal variation, water availability in terms of precipitation-evaporation ratio plays a more vital role than temperature. Total estimated ESV is 928.51 million US$, and CH₄ fixation cost is 6.64 million US$ which is only 0.71% to total ESV. So, considering such huge net ESV, emphasis on wetland conservation and restoration are necessary.

This study addresses the seasonal distribution of phytoplankton marker pigments (PMP) and the ratios (indicating freshness and fate) from water and surface sediments from the coastal port ecosystem (Paradip port, Odisha, east coast of India) and its utility in understanding phytoplankton pelagic-benthic linkages. Chlorophyll and PMP (for different groups and degradation) distribution revealed distinct seasonality, but the seasonal trend was different for water and sediments. High and low values were observed in the water column during inter-monsoons (fall/spring) and monsoons (southwest/northeast), respectively, whereas, in sediments, the reverse was recorded. However, the contribution of group-specific PMP was different: fucoxanthin > chlorophyll b > zeaxanthin > alloxanthin > peridinin dominated in water and chlorophyll b > zeaxanthin > fucoxanthin > alloxanthin > peridinin in sediment. Selective grazing and stability of sedimentary PMP (fucoxanthin, diatoms PMP, is least stable than other groups) could contribute to such differences. Relatively high chlorophyll:pheopigment ratios in the water and low pheophorbide: pheophytin in sediments indicated the dominance of actively growing microalgae and chlorophyll degradation via chlorophyllidae pathway in the water but not in sediments. These findings suggest that (i) much of the phytoplankton (primarily diatoms) is lost due to herbivory before reaching bottom sediments, and (ii) pigment contribution is determined by selective grazing in water and PMP decay constants in sediments. Documenting such information will give new insights into ecosystem assessment and algal bloom research.

Human activities have significantly increased the release of thallium (Tl) to the environment. However, the study of the relationship between maternal Tl exposure during pregnancy and the risk of preterm birth (PTB) is scarce so far. We aimed to investigate the association between Tl exposure in early pregnancy and the risk of PTB. A total of 2104 pregnant women from the Tongji Maternal and Child Health Cohort (TMCHC) in Wuhan, China were enrolled in the analysis. We collected the urine samples in early pregnancy (< 20 weeks) and inductively coupled plasma mass spectrometry (ICP-MS) was used to detect urinary Tl levels. The association between Tl levels and the risk of PTB was evaluated by an unconditional logistic regression. The median and geometric mean values of Tl levels were 0.35 μg/L (0.47 μg/g creatinine) and 0.33 μg/L (0.47 μg/g creatinine), respectively. Compared with the lowest tertile of Tl levels (≤ 0.37 μg/g creatinine), the highest tertile (> 0.57 μg/g creatinine) was associated with an increased risk of PTB with an adjusted odds ratio (OR) of 2.11 (95% confidence interval (CI): 1.08, 4.12). Stratified analyses showed an elevated risk of PTB related to the highest tertile of Tl levels for male newborns. After excluding women with miss covariate information, gestational diabetes mellitus, pregnancy-induced hypertension, reporting fish intake, or exposed to smoke, the association remained stable. Our results suggested that maternal Tl exposure during early pregnancy was positively associated with the risk of PTB, and Tl exposure may have a sex-specific effect on PTB.