Water, Air, & Soil Pollution最新文献

The long-term heavy dependence of human beings on petroleum products has led to a large amount of oily sludge discharge, and improper treatment of oily sludge will seriously pollute the environment and ultimately affect human health. However, the composition of oily sludge is too complex and difficult to treat. In this study, a new method for the joint treatment of oily sludge with surfactants and microorganisms was utilized, in which the organic matter in the oily sludge was eluted by the surfactants, and the residual organic matter, which was difficult to be eluted, was further degraded by microorganisms. This combined chemical-biological treatment method significantly improved the degradation efficiency of the oily sludge, and reduced the Total petroleum hydrocarbon (TPH) content of the oily sludge from 52,400 mg/kg to 4,190 mg/kg, with a TPH removal rate of 92%, and the residual oily sludge had a TPH content of 1.43%, which was already in compliance with the emission standards. The mechanistic analysis in this study also showed that the addition of appropriate amount of inorganic salt can promote the formation of surfactant micelles and significantly improve the elution effect of surfactant. This study will provide a useful reference for the efficient green treatment of oily sludge.

The increasing presence of microplastics (MPs) in aquatic ecosystems has raised concerns, mainly due to their adverse effects on aquatic organisms such as amphibians. This study evaluated the effects of exposure to naturally-aged polyethylene terephthalate (PET) microplastics on Physalaemus cuvieri tadpoles to investigate particle retention and toxicological impacts after cessation of exposure. The MPs were characterized through scanning electron microscopy and Raman spectroscopy analysis, and the weathering action was confirmed. Furthermore, our results indicated a significant increase in the mortality of tadpoles exposed to PET-MPs and partial retention of MPs after depuration. A higher Redox Balance Index (involving ROS levels and SOD and CAT activity) observed in the PET-MPs group at the end of the depuration period reveals a greater redox imbalance in these tadpoles. On the other hand, exposure to MPs induced neurochemical dysfunctions, such as reduced dopamine levels and increased AChE/BChE ratio, which were evident even after the end of exposure. Furthermore, the increase in total protein levels was observed throughout the experiment only in the control group. Finally, multivariate analyses (PCA and discriminant analysis) confirmed the occurrence of a phenomenon called the “legacy effect,” showing a clear separation between groups in the distinct phases of the experiment. In addition, multivariate linear regression analysis revealed a significant influence of MPs on the response of the animals only at the end of the exposure period, suggesting that the response observed at the end of depuration was cumulative, reflecting the damage induced during exposure. Thus, it is concluded that exposure to naturally-aged PET-MPs generates cumulative toxic effects in P. cuvieri, even after removing the pollutant, reinforcing the need for mitigation strategies to minimize the prolonged impacts of MPs on aquatic ecosystems.

The present research seeks to comprehend and evaluate the impact of varying concentrations of HCl acid solution on the compressibility and shear strength of silty clay. The compression test and the unconfined compressive strength test were conducted, and the SEM test was performed to analyze the microstructure of the soil with and without contamination. The results indicate that the contamination of silty clay soil with HCl acid caused a reduction in strength and an increase in the compression index and coefficient of consolidation; the more significant change in compressibility and strength was seen when the acid solution became more acidic. Concerning the SEM test, the images demonstrate the formation of macro pores between soil particles due to soil contamination. As the HCl acid solution concentration increased, more pores were formed and irregularly distributed across the whole soil surface. HCl acid solution contamination of soil causes the soil characteristics to degrade generally. Construction on this soil would consequently need to take into account the environment. Preparing the soil before building on it is suggested by adding materials that can increase the acid resistance of the soil.

Compared with a single pollutant, the comprehensive pollution index can reflect the degree of urban pollution more comprehensively. This article introduces the tax weighting method to calculate the comprehensive pollution index in the Yangtze River Delta (YRD). Based on the panel data of cities in the YRD from 2005 to 2017, the Spatial Durbin Model is utilized to empirically analyze the influencing factors and spatial spillover effects of the comprehensive pollution index. The results show: (1) The pollution of the cities in the YRD is unevenly distributed, and the eastern coastal areas are facing more serious pollution emissions than the western areas. (2) Changes in the urban industrial structure show an N-shaped curve impact on local industrial pollution emissions. The spatial spillover effect of the changes in industrial structure on the pollution emissions of surrounding cities presents an inverted N-shaped curve characteristic. (3) Economic openness and GDP per capita have a positive impact on pollution emissions. Government control can reduce pollution emissions. The impact of human capital and foreign direct investment on pollution emissions shows uncertainty over time and space. (4) The research results under the tax weighting method which can be proved to be applicable are consistent with the existing conclusions.

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.

Graphical Abstract

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.