Efforts to improve sludge resource utilization have become increasingly important. In this study, humic acid (HA) was extracted from sludge samples collected from a sewage treatment plant, and then used for the adsorption of heavy metals. We used two-dimensional correlation spectroscopy (2D-COS) integrated with Fourier-transform infrared spectroscopy (FTIR) to explore the adsorption between sludge HA (HA) and three metal ions (Cu, Ni, and Pb). The resulting adsorbing data conformed to the isotherm of Langmuir adsorption. The maximum capacity values (qₘ) were 5.34, 1.49, and 26.29.8 mg/g for Cu, Ni, and Pb, respectively. The data from 2D-FTIR-COS analysis showed that the susceptibility of the functional group followed the order 2300 → 1130 → 1330 → 1480 → 1580 cm⁻¹ for Cu(II) and Ni(II), and 2300 → 1130 → 1330 → 1480 → 1200 → 1580 cm⁻¹ for Pb(II). The sludge HA with Pb(II) showed more adsorption sites than sludge HA with Cu(II) and Ni(II), and these adsorption sites could preferentially bond with Pb(II) at × 1 compared with Cu(II) and Ni(II). Our findings indicate that 2D-FTIR-COS technology has great potential for application as a useful tool for understanding the adsorption mechanism between adsorbents with heavy metals.

The objective of this study was to investigate the concentration distribution of indoor air pollutants in taxis and ships (passengers) which are frequently used for public transportation and recreational activities in South Korea. In addition, it aimed to assess air quality factors to establish and evaluate the health risks of exposure to polluted indoor air. Particulate matter (PM₁₀) concentrations were not affected by the number of passengers, time of day, and driving characteristics because there were only a few passengers (2 to 4 people) and the space was confined. In the ships, indoor air pollutants responded more sensitively to the operation characteristics depending on the time of sailing (i.e., anchoring and departure, movement of vehicles on the ship, movement of passengers, combustion in the shop, and ventilation) than to the number of people boarding and alighting. The carbon dioxide concentrations in different ship rooms did not vary according to season and degree of congestion; however, there were differences between different ships. These differences may result from the size, type, and operating characteristics of the ships. Volatile organic compounds (VOCs) and aldehydes in new taxis exceeded the standard levels during summer. VOC concentrations in ships were particularly high during summer when the outdoor temperature was high. Similar observations were made for other means of transportation. The risk assessment depended on the means of transportation and demonstrated that mortality risks due to PM₁₀ and excess carcinogenic and non-carcinogenic risks from VOCs and aldehydes were within safety levels.

Saltwater intrusion into the surficial aquifer in coastal east-central Florida (USA) due to the effects of storm surges from tropical cyclones and continuous sea-level rise is a detrimental issue resulting in groundwater quality deterioration and bio-diverse ecosystem degradation. In this study, groundwater flow and salinity transport models using SEAWAT are developed for quantifying the “superposed” effects of storm surge (SS) from a Category 3 hurricane (Hurricane Jeanne which hit the Florida Atlantic coast on September 24–27, 2004) and continuous sea-level rise (SLR) on saltwater intrusion (SWI) into the surficial aquifer in coastal east-central Florida from the year of 2004 to 2024, and the simulated time-variant extent of SS- and SLR-induced landward migration of saline groundwater is compared for determination of whether the effects of SS from a Category 3 hurricane or continuous SLR on SWI are more significant. Results indicate that (1) the effects of SS are more significant than the effects of SLR within the first 12, 10, or 9 years after its occurrence date if sea level rises in low, mid, or high rate; (2) the effects of SS are more significant than the effects of SLR if SS occurs at least once within its return period (8–12 years); and (3) the maximum effects of SS are “equivalent” to the effects of the 95-year SLR, 45-year SLR, or 28-year SLR if sea level rises to 0.3 m in low, mid, or high rate. The outcome of this study warns public to pay more attention to the detrimental “superposed” effects of SS and SLR on SWI into the surficial aquifer in coastal east-central Florida.

The environmental Kuznets curve (EKC) hypothesis which was developed by Grossman and Krueger implies that clean environment demand increases over a certain level of income. Convergence of carbon emission can be considered an extension of EKC hypothesis, which emphasizes that the carbon emissions of countries will converge to a certain level. Convergence is important for the identification of the trend of carbon emission and to design emission abatement policies. This study investigates the stochastic convergence of per capita carbon emission in Organization for Economic Co-operation and Development (OECD) countries for 1960–2014 under cross-sectional dependence by using recently developed panel data methods. Empirical results are as follows: (i) per capita carbon emission is generally non-stationary according to the CADF test and the CIPS test. (ii) Panel KPSS test indicates that carbon emission per capita is overwhelmingly stationary in both country-specific and panel levels; (iii) Fourier panel KPSS test indicates that per capita carbon emission is overwhelmingly stationary at the country-specific level and non-stationary at the panel level. These findings are strongly in favor of convergence of per capita carbon emission among OECD countries. Consequently, it can be said that emission abatement policies aren’t essential among these countries.

Paraoxonase 1 (PON1) is an A-esterase calcium-dependent enzyme that is associated with high-density lipoprotein (HDL) and capable of hydrolyzing a wide variety of substrates, including organophosphate (OP) pesticides. The PON1 phenotype can be modulated by multiple internal and external factors, thereby affecting the catalytic capacity of the enzyme. The aim of this study was to evaluate factors that could modulate PON1 activity in a sample occupationally exposed to pesticides. A cross-sectional, descriptive, and analytical study was carried out with 240 workers. The participants were stratified according to their level of pesticide exposure as reference, moderate-exposure, and high-exposure groups. PON1 activities (arylesterase/AREase, CMPAase, and ssPONase (salt-stimulated)) were determined by spectrophotometry, and the Q192R and L55M PON1 genotypes by real-time PCR. The most frequent genotypes were heterozygous (QR) and homozygous (LL) for PON1Q192R and PON1L55M polymorphisms, respectively. The internal factors associated with the activity of PON1 were the PON1 genotypes (55 and 192) and biochemical parameters related to the lipid profile, in contrast, various external factors related to diet and harmful habits as well as with exposure to pesticides were associated with the activity of PON1. However, using a multivariate mixed ordinal regression model, we found a significant reduction of ssPONase activity in the high-exposure group compared with the reference group only in haplotypes QQLL and RRLL.

Chitosan/Co-Fe-layered double hydroxides (CS/LDHs) were prepared by coprecipitation method, which is a kind of composite material with excellent properties. The structure of CS/LDHs was characterized by SEM, FTIR, and XRD, which proved that chitosan (CS) was successfully induced into hydrotalcite and CS/LDHs still possess the structural characteristics of hydrotalcite. The adsorption of 2,4-dichlorophenol (2,4-DCP) was studied with CS/LDHs and LDHs as adsorbent separately. The activity of immobilized laccase (L-CS/LDHs) with CS/LDHs as carrier is significantly better than that of the one (L-LDHs) using LDHs as carrier. Under the optimum conditions (pH = 6, 55 °C, 48 h), L-CS/LDHs exhibited better removal performance for 2,4-DCP (81.53%, 100 mg/L) than LDHs (63.55%); the removal of 2,4-DCP by L-CS/LDHs is excellent, exceeding 97% as its initial concentration below 60 mg/L. It includes the catalytic action of laccase and dechlorination of Fe³⁺ and Co²⁺, and the adsorption can be ignored under the optimal conditions. After 5 cycles, it maintained 67% (L-CS/LDHs) and 54% (L-LDHs) of the original removal.

Early stages of ontogenesis determining subsequent growth, development, and productivity of crops can be affected by wastewater and sludge contaminated with pharmaceuticals. Diclofenac (DCF) and paracetamol (PCT; both 0.0001 to 10 mg/L) did not affect seed germination and primary root length of onion, lettuce, pea, and tomato. Conversely, 20-day-old pea and maize plants exhibited decrease in biomass production, leaf area (by approx. 40% in pea and 70% in maize under 10 mg/L DCF), or content of photosynthetic pigments (by 10% and 60% under 10 mg/L PCT). Quantum yields of photosystem II were reduced only in maize (FV/FM and ΦII by more than 40% under 10 mg/L of both pharmaceuticals). Contents of H₂O₂ and superoxide increased in roots of both species (more than four times under 10 mg/L PCT in pea). Activities of antioxidant enzymes were elevated in pea under DCF treatments, but decreased in maize under both pharmaceuticals. Oxidative injury of root cells expressed as lowered oxidoreductase activity (MTT assay, by 40% in pea and 80% in maize) and increase in malondialdehyde content (by 60% and 100%) together with the membrane integrity disruption (higher Evans Blue accumulation, by 100% in pea and 300% in maize) confirmed higher sensitivity of maize as a C4 monocot plant to both pharmaceuticals.

In this study, trisodium citrate was used as draw solute in forward osmosis (FO) due to its biodegradability and easy reuse after FO dilution. The effect of operating conditions on FO performance was investigated. The study focused on the long-term flux performance and membrane fouling when surface water was used as feed solution. A water flux of 9.8 LMH was observed using 0.5 M trisodium citrate as draw solution in PRO mode. In the long-term FO process, trisodium citrate showed a slight decrease in total flux loss (13.06%) after 20 h of operation. The membrane fouling was significantly reduced after a two-step physical cleaning. A considerable flux recovery (> 95%) of the fouled membrane was finally obtained. Therefore, this study proves the superiority of trisodium citrate as draw solution and paves a new way in applying FO directly for surface water reclamation.

The correct image of Figure 4 is shown in this paper. The original article has been corrected. Fig. 4: Scree plot of heavy metals in sediments. The graph shown in upper right corner shows the concentration of principle components variables in a loading plot.

In this study, the treatment of petroleum wastewater has been investigated by applying heterogeneous photocatalytic process using a recirculating annual reactor. An attempt has been made to study the effect of operating parameters such as TiO₂ load, initial concentration of the pollutant, emitted photonic flux, and pH of the solution. The degradation efficiency of toluene and benzene, as target molecules, was studied. In fact, result showed that the toluene is better degraded alone than when it is in a mixture. The rate of elimination of toluene separately was 89.5%, while it was 76.19 and 79.55% in the binary (toluene/benzene) and the ternary mixtures (toluene/benzene/xylene), respectively. Moreover, the mineralization of the solution decreased more rapidly when toluene was pure with a rate of 83.13% compared to binary and ternary mixtures. A mathematical model is proposed taking into account the parameters influencing the process performances. The mass transfer step, the degradation, and the mineralization kinetics of the pollutants were defined as model parameters. To build the model, mass balances are written in bulk region and catalyst phase (solid phase). The degradation mechanism on solid phase is divided in two stages. Firstly, the removal of toluene gives an equivalent intermediate (EI). Secondly, EI is oxidized into carbon dioxide (CO₂). This approach gives a good agreement between modeling and empirical data in terms of degradation and mineralization. It also allows for the simulation of toluene kinetics without knowing the plausible chemical pathway. A satisfactory fit with experimental data was obtained for the degradation and mineralization of toluene.