Water, Air, & Soil Pollution最新文献

Chromite ore processing residue (COPR) is a hazardous waste retaining relic Cr(VI). Large amounts are generated during the high-lime production of leather tanning salts in the region of Kanpur, India. Here, COPR is often deposited on open and uncontrolled landfills, leading to severe groundwater contamination. This study aimed at elucidating how ageing under these ambient conditions alters COPR properties and Cr(VI) mobility. For this, aged COPR obtained from surface and subsurface horizons of a visibly weathered open dumpsite was systematically compared to fresh high-lime COPR collected at two tanning salt factories. Elemental composition of the samples was characterized using X-ray fluorescence analysis while Cr(VI) mobility was assessed photometrically in alkaline and aqueous batch extracts. Mineralogical composition of the COPR was studied using X-ray powder diffractometry, scanning electron microscopy and thermogravimetry–mass spectrometry. The fresh COPR were highly alkaline and contained characteristic Cr(VI) host phases like calcium aluminum chromate hydroxide (CAC) and katoite. These were absent in the aged samples due to their lower pH of ~ 9. The pH drop was likely caused by uptake of atmospheric CO₂, which was corroborated by elevated carbon and calcite levels. This carbonation coincided with vertical translocation of Cr(VI) to the subsurface of the landfill, where leachate concentrations in excess of 1.6 g · L⁻¹ and chromatite (CaCrO₄) precipitations were found. The results highlight the importance of carbonation as a key ageing process which will likely exacerbate Cr(VI) groundwater contamination at open COPR dumpsites.

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The prevalence of fecal indicator bacteria in relation to physical parameters were observed twice a year in selected points of the Indus River. Eight representative sampling locations were selected, and samples were collected twice a year, i.e., in the dry and wet seasons, for a total of 16 samples. The fecal coliform (FC) to fecal streptococci (FS) ratio was used to identify the source of fecal contamination. Results showed severe fecal contamination levels exceeding the allowable limits of WHO and Pak-EPA. Except for pH and TDS, the physical parameters were also not found within allowable limits at various sampling locations. The comparison of dry and wet seasons reveals higher microbial loads in the wet season. The FC/FS ratio linked polluted waters to human sources (37.5%), animal sources (25%), mixed pollution with the dominance of human pollution (25%), and mixed pollution with the dominance of domestic pollution (12.5%) in dry and human sources (25%), animal sources (25%), mixed pollution with the dominance of human pollution (37.5%) and mixed pollution with the dominance of domestic pollution (12.5%) in wet season. Pearson’s correlation test showed a strong positive correlation (r = 0.71 to 0.99) between TDS and salinity in both dry and wet seasons, and a moderately strong correlation (r = 0.41 to 0.70) between various microbial and physical parameters. It is strongly advised that careless municipal wastewater disposal into rivers be prohibited. To prevent contaminated water from mixing with river water, an appropriate sewage and drainage system should be implemented.

Radioactive waste liquids and their derivatives have gradually become a potential threat to mankind. In this study, the FA-Fe-illite was prepared by using fulvic acid to modify the material for the adsorption of Eu(III) after with illite as the matrix and via ferric nitrate as the iron-based donor source. The results showed that the adsorption efficiency of FA-Fe-illite for Eu(III) was significantly better than that of raw illite and iron-column supported illite(Fe-illite). When the pH was 6 , the temperature was 298 K, the time was 60 minutes, and the dosage was 1.2 g/L, the removal rate of europium the removal rate of FA-Fe-illite reached 88.13%. The adsorption process followed the quasi-secondary kinetic model and Langmuir isotherm. Moreover, the thermodynamic parameters also indicated that the adsorption of Eu(III) was an entropy-increasing process with spontaneous heat absorption. Ion exchange, electrostatic adsorption, and surface functional group trapping (-COOH, -OH) played important roles in the adsorption of Eu(III) by FA-Fe-illite. Even after five adsorption-desorption cycles, the removal rate still maintained at 75%. These findings provide insights for the removal of Eu(III) in radioactive pollution control.

Adequate wastewater treatment is essential for safeguarding public health and the environment by removing harmful contaminants and pollutants. This study experimentally investigated the synergistic effects of hydrodynamic cavitation (HC) and gas injection (air, oxygen, and ozone) on reducing the chemical oxygen demand (COD) of synthetic wastewater with an initial COD concentration of 8100 mg/L. The HC system was optimized at an inlet pressure of 3 bar, with gas injected into three distinct locations: the tank, the venturi throat, and the high-pressure zone before the venturi. The Results revealed that gas injection, mainly ozone, significantly enhanced COD reduction. Unlike tank injection, injection into the high-pressure zone and venturi throat achieved superior COD reductions. The highest COD reduction of 56.2% was achieved with ozone injection at 5 g/h into the venturi throat, followed by 46.3% with oxygen injection into the high-pressure zone at 10 l/min and 22.9% with air injection into the high-pressure zone at 15 l/min. Additionally, injecting gas at a distance of 40 diameters before the venturi was identified as the most effective location, ensuring adequate mixing and maximizing COD reduction. These findings underscore the critical role of strategic gas injection locations and proper mixing lengths in enhancing HC system performance and their potential to significantly improve the efficiency of wastewater treatment processes.

We investigated the mercury (Hg) concentration of the full range of needle age classes (NACs) in two conifers, nine NACs in Picea abies and fourteen in Abies pinsapo var. marocana, as well as three leaf age classes (LACs) in two broadleaved evergreen species, Trochodendron aralioides and Rhododendron catawbiense. Additionally, the Hg concentration of the wooden branch segments to which the NACs were attached in the two conifers was studied. Picea abies showed a continued Hg accumulation over all NACs, but with an age-dependent decline in the accumulation rate. In Abies pinsapo var. marocana, maximum needle concentrations of Hg were reached after eight years. The concentration remained constant for NACs 9–14, indicating that needles had become saturated with Hg. The Hg concentrations of the branch segments were much lower than those of the needles in the older NACs. Over the three LACs of Trochodendron aralioides and Rhododendron catawbiense there was a steady increase in concentration with a weak indication of a declining Hg uptake rate in older leaves. The average needle/leaf lifetime Hg uptake rate per year was only half that of broadleaved species across all NACs and LACs. We conclude that in conifers maintaining a larger number of NACs there is a decline of the Hg accumulation rate in older NACs. In future biogeochemical research (empirical and modelling) and biomonitoring studies, the age of sampled leaves needs to be considered to account for the age dependence of leaf Hg concentration and accumulation rate.

Marine debris is defined as any persistent, manufactured, or processed solid material that is intentionally or unintentionally disposed of or allowed to float into the marine environment. This debris can be of natural or artificial origin and includes a wide variety of materials, such as chemically treated wood. Fine woody debris (FWD), small particles with diameters ranging from 1 to 10 cm, can have natural and anthropogenic origin, which is often overlooked in coastal environments. In this study, we investigated FWD across multiple sites along the central Moroccan Atlantic coastline and identified 2068 FWD elements with an average density of 49.23 ± 38.07 items/m². Site 2, near a river, stood out for its notably greater density, in contrast to the lower densities observed at the other sites. Chemical characterization of the FWD surfaces revealed mechanical abrasions, along with traces of heavy metals (HMs) such as Cu and Ti, plastics (including PS, PP, PE, PA, and PVC), and pharmaceuticals (periciazine, dipyridamole, and canthaxanthin). These findings underscore the role of FWD as a reservoir and transporter of environmental contaminants such as microfibers, and HMs, which can leach into surrounding waters and be taken up by marine organisms. The presence of these contaminants highlights potential disruptions to marine biodiversity and ecological processes, including bioaccumulation and toxicity in aquatic food webs, habitat degradation, and altered nutrient cycling. Moreover, the global significance of these findings lies in their implications for biodiversity management and conservation strategies. Anthropogenic FWD not only represents a source of pollution but also a vector for spreading harmful substances, emphasizing the urgent need for effective management strategies. These include regular monitoring and targeted cleanup efforts to mitigate potential hazards, preserve ecosystem integrity, and enhance recreational experiences in dynamic coastal environments.

The impact of advanced oxidation processes (AOPs) integration with hydrodynamic cavitation (HC) along with energy-economics, has been studied towards the sustainable degradation of the organophosphate (OP) pesticide-contaminated agrochemical wastewater. Initially, the geometric interpretations of HC have been studied by hydrodynamic analysis towards selection of an optimal orifice device. The independent and integrated effects of AOPs were investigated for degradation. The optimal operational parameters for HC along with the degradation kinetics have been established. The reduction in total organic carbon (TOC) obtained by different approaches for 240 minutes of treatment time is reported. Treatment with HC alone resulted in 71% reduction, HC + H₂O₂ achieved 82%, HC + O₃ reached 79%, HC + H₂O₂ + O₃ resulted in 80% reduction. Among all combinations, based on energy-economics and kinetic-studies, the case of ozonation(O₃) given as pretreatment to HC has shown the highest degradation with 95% TOC reduction. In comparison to the simultaneous integration of O₃ with HC, the operational time required for TOC reduction of 90% was found to be 1.24 times lower with ozone pretreatment followed by HC operation, moreover the cost of operation drastically reduced by 14-fold. The byproduct analysis also shows that independent O₃ treatment for degradation, leads to the formation of secondary contaminants. However, the standalone HC process is found to be the most cost-effective, with 21-fold lesser operational costs as compared to the integrated processes but has a higher operational time. Therefore, the integrated process of O₃ pretreatment + HC was found to be a promising technology for OP degradation in terms of operational time and costs, while not generating any byproducts.

Large amounts of volatile organic compounds are released into the environment, and most have been shown to be harmful to humans. Dongting Lake is one of the important freshwater lakes in China, but there are few studies on the existence, distribution and risk assessment of volatile organic compounds in its water. This study investigated the emergence of volatile organic compounds (VOCs) within the surface water of Dongting Lake. A total of 15 different VOCs concentrations were measured in water samples from 21 sampling points. Fifteen kinds of VOCs have been detected; the one with the highest mean concentration is 1, 2-dichlorobenzene (1.039 μg/L), and the lowest is 1, 3, 5-trimethylbenzene (0.0034 μg/L). Of these, seven VOCs had a detection frequency of 100%. The total concentration of volatile organic compounds in the Nanzui waters was the highest among all the test sites. The Risk quotients (RQ) model has been adopted for evaluating the VOCs ecological risk, the RQ_total values of five sampling sites were higher than 1.0, indicating that the target compounds were at high risk or medium risk for related sensitive aquatic organisms. In addition, the carcinogenic risk of benzene is 2.45 × 10^–6, and the environmental exposure of benzene has a certain risk to human body but is within an acceptable range.The non-carcinogenic risks of toluene, benzene, ethylbenzene as well as xylene (BTEX) have been all less than 1.0, so it can be considered that there is no non-carcinogenic risk of BTEX to human body. Therefore, VOCs in Dongting Lake will not cause serious impact on human body, but it will pose a threat to aquatic organisms in some water areas.

Tri-metallic SnAlFeO nanoparticles with surface functionalization were synthesized utilizing an easy and facial technique. For the analysis of the surface functionalization, shape, elemental ratio, crystal lattice, and functional group of these nanoparticles, a variety of analytical methods were employed. The nanoparticles displayed rice shape structure, according to SEM images. These rice-shaped nanoparticles were used to remove bromophenol blue (BPB) dye, a hazardous organic contaminant, from an aqueous solution. An incubator orbital shaker was utilized for shaking 0 to 120 min in pH tests in the range of pH 3 to 11.0. 50 to 200 mg of different adsorbent doses were used to investigate their effects. Many different adsorption isotherms (Langmuir, Freundlich, Temkin, etc.) and rate kinetics studies were used to investigate the adsorption of BPB dye using SnAlFeO nanoparticles. Pseudo-second-order kinetics model and Freundlich isotherms were found best fitted for the adsorption study of SnAlFeO nanoparticles. The exothermic phase includes mechanical forces according to the BPB dye adsorption. The n values of the model parameters were, respectively, n = 0.999, 0.967, and 0.944 at 298, 308, and 318 K. As a result, numerous horizontal molecule orientations were thought to be involved in the interactions between the active sites of BPB and SnAlFeO nanoparticles. Q_sat had values of 216.35, 9.241, and 1.642 mg/g at 298, 308, and 318 K, respectively. Q_sat results demonstrate that BPB molecules and SnAlFeO nanoparticles infrequently come into touch with one another as the temperature rises. Using an adsorption approach, this adsorbent demonstrated strong adsorption in industrial wastewater and has a lot of promise.

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Large volumes of polluted industrial wastewater discharges had made it imperative to continue on the development of adsorbent materials with improved adsorptive properties yet economically feasible. Agricultural waste such as date palm biomass offers an interesting solution as raw material due to its abundance and availability throughout the year. Biochar and hydrochar produced from date palm biomass were reported as a potent adsorbent to remove pollutants such as dyes from aqueous environment. However, very few studies had reported on the mechanism of dye removal by these types of adsorbents. Therefore, this study aimed to evaluate the methylene blue (MB) removal capacity of biochar (DPSB) and hydrochar (DPSH) produced from date palm seeds (DPS). This was followed by molecular dynamics studies (density functional theory, DFT) which was targeted to propose the geometry of the adsorbents as well as the interaction between MB and functional groups present on DPSB and DPSH. Finding from this molecular dynamics studies acted as the direct contribution of new knowledge for the interaction between DSP-based adsorbents and MB. DPSB and DPSH were produced from DPS samples that were collected from the Kingdom of Saudi Arabia's Hail region. FTIR analysis showed the presence of C = C, C = O, CO, and OH on both DPSB and DPSH while SEM micrographs reveal a highly porous structure with open pores and sharp edges in both samples. Thermogravimetric analysis (TGA) revealed a total weight loss of 20.79% for both samples. The maximum methylene blue (MB) removal of 85.6% (DPSB) and 89.4% (DPSH) was achieved at initial MB concentration of 10 mg L⁻¹, 2 g of adsorbent and equilibrium time of 45 min. Kinetic parameters (pseudo-first order and pseudo-second order interaction) were also used to evaluate the MB removal capacity. From the Density Functional Theory (DFT) analysis, all of the DPSH peaks exhibited an increase in intensity in the Band Gap of the hydrochar spectrum (-0.02102), indicating its resistant to chemicals and environmental degradation. To conclude, DPS were successfully demonstrated to be a useful alternative as raw material to produce biochar and hydrochar with good pollutant (MB) removal capacity. Nevertheless, more studies need to be carried out to ensure smooth transition of this type of adsorbent prior to any attempts for actual on-site application.