Contaminant Concentrations Research Articles

Sub-lethal exposures to bifenthrin impact stress responses and behavior of juvenile Chinook Salmon.

Juvenile Chinook Salmon (Oncorhynchus tshawytscha) populations have decreased substantially in the Sacramento-San Joaquin Delta (Delta) over the past decades, so considerably that two of the four genetically distinct runs are now listed in the Endangered Species Act. One factor responsible for this decline is the presence of contaminants in the Delta. Insecticides, used globally in agricultural, industrial, and household settings, have the potential to contaminate nearby aquatic systems through spray drift, runoff, and direct wastewater discharge. Chinook Salmon are therefore exposed, as they out-migrate through the Delta, to insecticides that have been associated with adverse biological effects in aquatic species, ranging from sub-lethal impairments to lethality. The goal of this study was to assess whether bifenthrin, a ubiquitous pyrethroid insecticide in the Delta, impacts thermal tolerance, hypoxia tolerance and behavior of juvenile Chinook Salmon. Fish were exposed for 10 days to environmentally relevant (125 ng/L, associated with resulting body residues in wild-caught fish) and sub-lethal bifenthrin concentrations (500 and 1000 ng/L). Juvenile Chinook Salmon exposed to bifenthrin were tolerant to increases in hypoxia but not temperature. Fish exposed to bifenthrin showed dose-dependent behavior changes: hypoactivity at 125 ng/L, hyperactivity at 1000 ng/L, and reduced anxiety-like behavior, including lower thigmotaxis and decreased social interaction. The results revealed that exposure to sublethal concentrations of bifenthrin, leading to environmentally relevant body burden residues, significantly altered upper thermal tolerance and caused non-linear behavioral changes. The study suggests the existence of behavioral effect thresholds in wild-caught fish and emphasizes that higher concentrations of contaminants may impair Chinook Salmon's ability to avoid predators in natural environments.

Hydrogeochemical characterization of shallow and deep groundwater for drinking and irrigation water quality index of Kathmandu Valley, Nepal.

A comprehensive hydrogeochemical analysis of 156 groundwater samples (106 shallow and 50 deep) was conducted in the Kathmandu Valley, Nepal. This study addresses a significant research gap by focusing on the hydro-geochemical composition and contamination of groundwater in the Kathmandu Valley, an area with limited detailed assessments. The novelty of this work lies in its comprehensive analysis of both shallow and deep groundwater, particularly concerning the high concentration of contaminants like arsenic, microbial pathogens, and ammonium, which are critical for public health. The results indicate that the mean concentration of turbidity, iron (Fe), and total coliform (TC) was exceeded the permissible range by National Drinking Water Quality Standards (NDWQS). Hydro-geochemical analysis using the Piper and Chadha diagrams showed the Ca2⁺-Mg2⁺-HCO₃ dominance, suggesting carbonate rock weathering and ion exchange as primary processes. Gibbs and mixing diagrams further supported these findings. The Water Quality Index ranged from 3.93 to 442.11 (mean: 66.87) for shallow water while 8.07 to 252.87 (mean: 79.24) with turbidity, iron, and ammonia significantly contributing to the overall index. Salinity hazard assessment considering total dissolved solids, sodium adsorption ratio, sodium percentage, magnesium adsorption ratio, and Kelly ratios, indicated that shallow and deep groundwater samples are suitable for irrigation, as confirmed by Wilcox diagrams. This study provides valuable insights into the groundwater quality of Kathmandu Valley and highlights the need for effective management strategies to ensure sustainable use of this vital resource, providing a nuanced understanding of groundwater quality and its implications for water management in the region. The findings can inform water treatment practices, policy-making, and future research, ultimately aiding in the development of safer and more sustainable groundwater management practices for the region.

NP-bioTech: a circular economy approach to catalyst-based biostabilization of citrus processing waste.

Biowaste accounts for about 40% of total waste. Food-industry waste is one major biowaste stream. The available technological approaches to biowaste treatment are expensive, not circular, unsustainable, and they require pre-treatments such as dehydration, extraction of inhibitors, pH correction, or the addition of other organic matrices. The NP-bioTech process uses a biocatalyst adsorbed onto an inert material enabling accelerated fermentation of critical biomass without pre-treatments, transforming it into biostabilized and pasteurized material, and converting waste into new usable products rapidly. Biocatalysts consist of naturally fortified selections of microbial colonies, enzymes, and fungi that are resistant to the action of d-limonene and other fermentation inhibitors. The NP-bioTech process was able to activate vigorous fermentation of citrus waste without any of the pre-treatments required by other available biowaste-treatment technologies. The horticultural use of the biostabilized output of such process for greenhouse crops was verified. The addition of such output to the growth media was beneficial for plants and did not show negative effects on quality and yield of tomatoes (Lycopersicon esculentum L.). The concentration of Ca, K, Zn, Fe, and polyphenol increased; the average number of berries per plant was improved; the concentration of Pb and Cd contaminants decreased. The NP-bioTech process emits no odors or pollutants. It does not generate leachate, and its output can be used in agriculture. It is capable of reconciling compliance with strict environmental restrictions, industrial feasibility, and economic sustainability. Its potential impact thus aligns well with the circular economy model. © 2025 Society of Chemical Industry.

Characterizing the heterogeneous contamination of commercial paper and board food packaging at different scales

Assessing the contamination of paper and board (P&B) food packaging materials poses significant challenges due to the sensitivity limits of analytical methods and the low precision of sampling processes. This study aims to enhance the understanding of P&B food packaging contamination by investigating the distribution of contaminants at different scales using a combination of chromatographic and spectroscopic techniques. A total of 36 substances were targeted, including phthalates, photoinitiators, and bisphenol A. Key findings reveal that intra-packaging variability can lead to concentration variations by a factor of 2–7. Recycled materials generally exhibit higher contamination levels, with concentrations of certain contaminants reaching up to 700 mg/kg. Microscopy, including confocal laser scanning microscopy (CLSM) and Raman micro-spectroscopy, enabled the identification and differentiation of contaminants, highlighting specific marker molecules and characteristic Raman bands. The study underscores the necessity of comprehensive sampling strategies, advocating for the grinding of entire packaging to obtain representative samples. The introduction of contamination "fingerprints," based on occurrences and correlations between concentrations, offers a promising approach for hazard identification and risk assessment. Overall, the findings contribute to the development of safer and more sustainable food packaging solutions, emphasizing the need for improved analytical techniques and standardized sampling methods in the context of increasing use of recycled materials.

A new approach for assessing the radioecological risk associated with the legacy discharge of oil derived natural radioactivity in the UK North Sea.

Although oil and gas (O&G) derived produced waters and drill cuttings are known to contain enhanced levels of naturally occurring radium-228 (228Ra) and radium-226 (226Ra), most relevant ecological impact assessments have excluded radiological hazards and focus on other important contaminants, such as hydrocarbons and metals. Also, due to restricted access to the delimiting safety zone around operational O&G platforms, the few previous radioecological risk assessment studies have been conducted using seawater samples collected far from the main discharge point and applying default dilution and transfer factors to estimate concentrations of contaminants in biota. In this case study, sediment cores were collected close to a former O&G platform, Northwest Hutton (NWH), that used to be in the UK North Sea (61.11N, 1.31E). The sediment materials were analysed by gamma spectrometry and ICP-MS to confirm the presence of particles enriched in natural radioactivity. Benthic macrofaunal assemblages in the surrounding seabed were also characterised and one of the dominant species was selected for additional nano-hard X-Ray Fluorescence (nano-XRF) imaging to confirm the exposure pathways and refine the radioecological risk assessment using the ERICA tool. This novel approach for estimating dose rates was found to be less conservative than more traditional approaches using the ERICA default concentration ratio for 228Ra and 226Ra. The dose rate estimations were confirmed to be significantly lower than the ERICA screening level of 10μGy/h, in agreement with findings from previous studies.

Spatial and temporal (annual and decadal) trends of metal(loid) concentrations and loads in an acid mine drainage-affected river.

Acid mine drainage (AMD) is a worldwide problem that degrades river systems and is difficult and expensive to remediate. To protect affected catchments, it is vital to understand the behaviour of AMD-related metal(loid) contaminants as a function of space and time. To address this, the sources, loads and transport mechanisms of arsenic (As), copper (Cu), zinc (Zn), iron (Fe) and sulfur (S) in a representative AMD-affected catchment (the Carnon River in Cornwall, UK) were determined over a 12-month sampling period and with 22years of monitoring data collected by the Environment Agency (England) (EA). The main source of metal(loid)s to the Carnon River was the County Adit which drains AMD from approximately 60km of underground historical mine workings. Maximum aqueous concentrations of Fe, Cu and Zn occurred immediately downstream of the County Adit confluence with the Carnon River, whereas maximum As and S concentrations occurred further downstream, suggesting the presence of diffuse sources. Discharge and concentration relationships suggested that discharge drove Cu and Zn release, whereas pH and Eh influenced Fe, S, and As mobility. Total loads (represented by unfiltered sample contaminant concentrations) to the coastal zone were high, ranging from 183 to 354kg/month As, 307-742kg/month Cu, 189-1960kg/month Fe, 53,400-125,000kg/monthS and 1280-3320kg/month Zn. The longevity and increasing amounts of contaminant discharge were confirmed with 22years of EA monitoring data. This study highlights the complex and multifaceted behaviour of contaminant metal(loid)s within AMD-affected riverine systems and the fact that point and diffuse sources can constitute significant long-term liabilities for such environments.

Modelling Backward Trajectories of Air Masses for Identifying Sources of Particulate Matter Originating from Coal Combustion in a Combined Heat and Power Plant

The paper analyzes the processes of emission and dispersion of particulate contaminants from a large point source emitter: a hard coal-fired power plant. Reference is made to the European Green Deal and its main objective of reducing anthropogenic particulate and greenhouse gas emissions. CHPP, Krakow Combined Heat and Power Plant, Poland, as described in the article, has a strong impact on the mechanisms that shape the microclimatic factors of the Krakow agglomeration. This combined heat and power plant provides heat and electricity for the city, while simultaneously emitting significant amounts of suspended particulate matter into the atmosphere. Due to the adverse impact of non-conventional energy sources on the natural environment and the increasing effects of climate warming, radical changes need to be implemented. The HYSPLIT (Hybrid Single-Particles Lagrangian Integrated Trajectories) model was used to track the movement of contaminated air masses. A 5-day episode of increased hourly concentrations of PM2.5 particulate matter contamination was selected to analyze the backward trajectories of air mass displacement. From 15 August 2022 to 19 August 2022, high 24-h particulate matter concentrations were recorded, measuring around 20 µg/m3. The HYSPLIT model, a unique tool in the precise identification of point sources of pollution and their impact on the air quality of the region, was used to analyze the influx of polluted air masses. A 5-day episode of increased hourly concentrations of PM2.5 pollutants was selected for the study, with values of approximately 20 µg/m3. It was found that low-pressure systems over the North Atlantic brought wet and variable weather conditions, while high-pressure systems in southern and eastern Europe, including Poland, provided stable and dry weather conditions. The simulation results were verified by analyzing synoptic maps of the study area. The image of the displacement of contaminated air masses obtained from the HYSPLIT model was found to be consistent with the synoptic maps, confirming the accuracy of the applied model. This means that the HYSPLIT model can be used to create maps of contaminant dispersion directions. Consequently, it was confirmed that modeling using the HYSPLIT model is an effective method for predicting the displacement directions of particulate contamination originating from coal combustion in a combined heat and power plant. Identifying circulation patterns and front zones during episodes of increased contaminant concentrations is strategic for effective weather monitoring, air quality management, and alerting the public to episodes of increased health risk in a large agglomeration.

Analysis and future trends of cyclodextrins as adsorbents in wastewater treatment

Cyclodextrins, derived from starch, are introduced as promising adsorbents capable of sequestering various pollutants, including heavy metals and dyes, although their solubility in water poses challenges for their removal after use. In this paper a bibliometric analysis is conducted using the Scopus database, yielding 649 relevant documents. Analysis indicates that the use of cyclodextrins in wastewater treatment is still in the early stages of growth and maturity, with most studies focusing on their application as adsorbents for dyes and heavy metals. However, the influence of other wastewater constituents on their effectiveness remains underexplored. By means of an S-growth model, it can be stated that this technology requires at least another 10 years to reach maturity as a treatment process. The geographic performance analysis indicates that China is the leading contributor to research on cyclodextrins in wastewater treatment, accounting for 40% of total publications, followed by the United States. Finally, the performance and operating conditions of cyclodextrins as adsorbents have been analysed. It is discussed the variations in adsorption capacity and the challenges in comparing studies due to differing initial contaminant concentrations. The results suggest that in the future it will be necessary to carry out experiments with real wastewater in pilot-scale plants.

Terrestrial nanoparticles and geospatial optics: Implications for environmental impact from anthropogenic contaminants in the Caribbean region.

Atmospheric contaminants from natural processes and anthropogenic activities pose a major problem to the environment. Here we analyze the dynamics of atmospheric and terrestrial contaminant concentrations in sediments containing chemical elements, such as nanoparticles (NPs) and ultrafine particles in hydrological sources of the Caribbean region of Colombia. Terrestrial sediments were collected from 2022 to 2024, and quantified for major chemical elements in the form of NPs and ultrafine particles in runoff receiving areas along the banks of Colombia's Ciénaga Grande in Santa Marta Bay, on the Isla de Salamanca. Additionally, atmospheric carbon monoxide (CO) and nitrogen dioxide (NO2) levels were detected using TROPOMI, coupled with the Sentinel-5P satellite, from 2019 to 2024. Sampling was performed during both summer and winter, focusing on the Sierra Nevada de Santa Marta National Park, Isla de Salamanca, and the cities of Santa Marta and Barranquilla. Sediment samples were collected from 25 fixed sites on Isla de Salamanca and analyzed in the laboratory. The CO and NO2 concentrations were detected at 122 "collection points," with a spatial resolution of 7km×3.5km, an average normalization of 0.83μg/mg, and a maximum error of 6.62%. The results revealed abundant Fe particles containing Cr, Ti, Zn, and Zr (1-2.5μm in size), with nanohematite (iron oxide) particles containing C, As, and S detected via EDS. The CO concentrations peaked in Barranquilla and Santa Marta (up to 0.042mol/m2), while NO2 concentrations reached 2.4×10-5 mol/m2, similar to the levels in Sierra Nevada de Santa Marta National Park and Ciénaga Grande de Santa Marta. These findings highlight the impact of forest fires on air quality in the region and support the development of new public policies to mitigate pollution and to protect ecosystems in this ecologically relevant area.

Distribution and bioconcentration of semivolatile organic compounds (SVOCs) in soils and vascular plant Colobanthus quitensis from Sub-Antarctic and Antarctic regions.

Semi-volatile organic compounds (SVOCs) are widely distributed across the globe, including polar regions. This study investigates the distribution and bioconcentration of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in soils and Colobanthus quitensis, while also estimating potential emission sources. Results indicated high concentrations of PAHs in soils and plants from the Sub-Antarctic region, while OCPs and PCBs were more prevalent in the Antarctic region, with higher contaminant concentrations found in soils than in plant tissues. Hexachlorobenzene (HCB) and dichlorodiphenyldichloroethylene (p,p'-DDE) were significantly higher in the Antarctic region, suggesting historical dichlorodiphenyltrichloroethane (DDT) use, while PCB 153 and 180 were the most representative PCBs in the Antarctic region. Phenanthrene (Phe) was the dominant PAH in both regions. The bioconcentration factor analysis from soils (BCFSoils) revealed potential anthropogenic influences for certain contaminants, including γ-hexachlorocyclohexane (γ-HCH) and PCB 9 in the Sub-Antarctic region, and HCB, p,p'-DDE, PCB 9, and benzo-naphtho-thiophene in the Antarctic region. However, compounds with higher hydrophobicity showed lower Bioconcentration factor (BCFSoils) values, indicating a tendency to accumulate in soil rather than plant tissues. This was consistent with the inverse relationship found between BCFSoils and the octanol-water partition coefficient (Log KOW). Diagnostic ratios of PAHs revealed a predominantly pyrogenic source in the Sub-Antarctic region, while a mixture of sources was observed in the Antarctic region.

Coupled model for one-dimensional large-strain nonlinear consolidation and contaminant transport in underlying clay liner of a dredged sludge dumping site considering different initial effective stress distributions.

To study the contaminant transport behavior in the underlying clay liner of a dredged sludge dumping site, a one-dimensional large strain nonlinear consolidation and contaminant transport coupled model is established, and the corresponding numerical solutions for the proposed coupled model is obtained. The numerical results are compared and investigated with the existing theoretical model to verify the correctness of the coupled model. Furthermore, the effects of dredged sludge landfill method and initial effective stress distribution on the contaminant transport behavior in the underlying clay liner and the breakthrough time of the underlying clay liner are investigated. The results show that the consolidation behavior of the underlying clay liner varies considerably with different dredged sludge landfill methods, resulting in a change in the distribution behavior of contaminant concentrations. Differences in the distribution of the initial effective stress along depth can have a large impact on the changes in void ratio, flow velocity and diffusion coefficient, which can alter the distribution of contaminant concentrations. The time for the underlying clay liner to be penetrated by contaminants is shortest for instantaneous landfill of dredged sludge and longest for single-stage linear landfill of dredged sludge.

Benefits of Immobilized Bacteria in Bioremediation of Sites Contaminated with Toxic Organic Compounds.

Although bioremediation is considered the most environmentally friendly and sustainable technique for remediating contaminated soil and water, it is most effective when combined with physicochemical methods, which allow for the preliminary removal of large quantities of pollutants. This allows microorganisms to efficiently eliminate the remaining contaminants. In addition to requiring the necessary genes and degradation pathways for specific substrates, as well as tolerance to adverse environmental conditions, microorganisms may perform below expectations. One typical reason for this is the high toxicity of xenobiotics present in large concentrations, stemming from the vulnerability of bacteria introduced to a contaminated site. This is especially true for planktonic bacteria, whereas bacteria within biofilms or microcolonies have significant advantages over their planktonic counterparts. A physical matrix is essential for the formation, maintenance, and survival of bacterial biofilms. By providing such a matrix for bacterial immobilization, the formation of biofilms can be facilitated and accelerated. Therefore, bioremediation combined with bacterial immobilization offers a comprehensive solution for environmental cleanup by harnessing the specialized metabolic activities of microorganisms while ensuring their retention and efficacy at target sites. In many cases, such bioremediation can also eliminate the need for physicochemical methods that are otherwise required to initially reduce contaminant concentrations. Then, it will be possible to use microorganisms for the remediation of higher concentrations of xenobiotics, significantly reducing costs while maintaining a rapid rate of remediation processes. This review explores the benefits of bacterial immobilization, highlighting materials and processes for developing an optimal immobilization matrix. It focuses on the following four key areas: (i) the types of organic pollutants impacting environmental and human health, (ii) the bacterial strains used in bioremediation processes, (iii) the types and benefits of immobilization, and (iv) the immobilization of bacterial cells on various carriers for targeted pollutant degradation.

Mathematical advection-diffusion model of primary and secondary pollutants emitted from the point source with mesoscale wind and removal mechanisms

A numerical model is represented to study the effect of gravitational settling velocity and leakage velocity on the concentration distribution of primary and secondary pollutants emitted from the point source in an urban area with mesoscale wind. The point source characterizes pollutants emission from industrial process stacks and fuel combustion facility stacks. The article deals with the dispersion of primary and secondary pollutants emitted from point source with mesoscale wind along with large scale wind. The Crank-Nicolson's implicit finite difference method is adopted for solving partial differential equations of contaminant with wind velocity and eddy diffusivity profiles. Pollutants concentration been analysed for various removal mechanisms under stable as well as neutral condition of atmosphere. The results reveal decrease in the concentration of primary and secondary air contaminant by increasing the various removal mechanisms. In neutral condition the magnitude of concentration is less for the pollutants as compared with stable condition of atmosphere.

Adsorption Performance and Mechanistic Pathways of Raw Powdered Pine Cone Toward the Removal of Dye and Cr(VI)

ABSTRACTThis work aims to valorize pine cones powder (PCP), an agricultural waste, as a bioadsorbent for the removal of a cationic dye, Rhodamine B (RhB), and hexavalent chromium Cr(VI) from an aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier‐transformed infrared (FTIR), and X‐ray diffractometer (XRD) spectroscopy. Adsorption studies were carried out in a batch mode under different operating parameters like initial solution pH (2–11), adsorbent dosage (0.025–0.6 g), initial contaminant concentration (20–100 mg/L), temperature (283–328K), contact time (0–120 min), and ionic strength (NaCl, MgCl2, CuSO4, Na2SO4, and FeCl3). The optimum conditions for adsorption for Cr(VI) were; ([Cr(VI)] = 30 mg/L, pH = 2, adsorbent dose = 1.5 g/L, T = 25°C), and for RhB: ([RhB] = 30 mg/L, pH = 4.6, adsorbent dose = 4 g/L, T = 25°C). Under these conditions, the maximum adsorption capacities reached were 19.861 and 6.565 mg/g, for Cr(VI) and RhB, respectively. The inhibiting effect of the studied salts on RhB dye and metal ion removal is as follows: FeCl3 > CuSO4> MgCl2> Na2SO4> NaCl. The Freundlich isotherm described the best the adsorption of Cr (VI) and RhB onto PCP, since it gave the highest R2 values (R2 ≥ 0.983) associated with the lowest error values (χ2, RMSE, and Δq). The calculated Dubinin–Radushkevich mean energy (E) is less than 8 kJ/mol. It is 3.391 kJ/mol for Cr(VI) and 2.310 kJ/mol for RhB sorption, respectively, confirming the physical character of adsorption onto PCP sorbent. Experimental data for Cr(VI) and RhB ion adsorption onto PCP, fitted well the pseudo‐second‐order kinetic model (R2 ≥ 0.997). According to the thermodynamic analysis, the retention of Cr(VI) and RhB followed a physisorption, endothermic, and spontaneous process at all temperatures for Cr(VI), and at higher temperatures for RhB dye. These results suggest that raw PCP may be envisaged as a promising biosorbent for water remediation without the need of costly heat and activation processes as a cheap and sustainable adsorption process.

Dynamic coupling of qualitative–quantitative models for operation of water resources based on environmental criteria

Concerning issues include the distribution of scarce water resources, the quality of utilized water, environmental repercussions, and regulations for the sustainable use of water resources. In the management of water resources, optimal qualitative–quantitative exploitation of surface water bodies is regarded as a desirable strategy. The Dez River surface water system from the Dez regulatory dam to Band-e-Ghir is selected in the current paper to create a qualitative–quantitative model that can determine the best exploitation strategies. A dynamic linkage between qualitative and quantitative models is built in order to simulate the current exploitation conditions under the umbrella of the best-case scenario. In this coupled system, hydraulic relationships are established between all of the system’s components. The available data are shared between two models in this structure to simulate the qualitative and quantitative effects of surface water. Then, a new structure is produced to derive the best policies for exploiting the dam and the river by connecting the multi-objective particle swarm optimization algorithm with the qualitative–quantitative coupled model body. The monthly river environmental demand is one of the decision variables in the ideal scenario, and the goals include boosting the percentage of supply demands and minimizing the violation of quality standards. The best-case scenario’s implementation increases the likelihood that all plain demands will be met, regardless of priority. Furthermore, in comparison with the reference scenario, the results of the optimal scenario show that not only are the concentrations of contaminants and qualitative parameters increased, but there are also only minimal violations of the quality and pollution standards of the river water in the majority of river points, particularly in the locations of agricultural withdrawals. The findings demonstrate that using the qualitative–quantitative dynamic relationship between water resources and the development of the coupled model using the NSGA-II algorithm allows us to better plan for the appropriate use of existing water resources by taking into account all stakeholders in such a way that, in addition to meeting needs, maintains the river quality close to standard limits throughout the exploitation period. By using this strategy, users will be informed of the negative effects of their actions, as well as the encroachment on river boundaries and associated consequences.

Enhanced remediation of naphthalene from aqueous solutions using synthesized organoclay: characterization, mechanisms, and isotherms.

Water contamination by polycyclic aromatic hydrocarbons (PAHs), particularly naphthalene, is a serious environmental concern due to its persistence, bioaccumulation, and toxicity. This study explores the adsorption behavior of naphthalene using organobentonite (OBt), synthesized by intercalating cetyltrimethylammonium bromide (CTAB) into sodium bentonite (SBt) with varying cation exchange capacities (CECs). The effectiveness of OBt in naphthalene adsorption was evaluated by analyzing key parameters, including CEC, contaminant concentration, and contact time. The morphological and structural properties of all adsorbents were characterized before and after the adsorption process. The results demonstrated a significant improvement in the adsorption capacity of OBt compared to SBt, with a maximum naphthalene adsorption capacity of 14.08mg/g at 2.0 CEC, versus 5.22mg/g for SBt. The Freundlich isotherm model provided the best fit for adsorption data (R2 > 0.97), indicating that the partitioning mechanism primarily governed the process. CTAB-modified OBt showed enhanced hydrophobicity, larger basal spacing, and faster adsorption kinetics, with most naphthalene removal occurring within the first 15min. These findings indicated that OBt, due to its improved adsorption efficiency, rapid kinetics, and cost-effectiveness, is a promising adsorbent that can enhance the remediation of hydrophobic organic pollutants from contaminated water.

Widespread presence of metallic compounds and organic contaminants across Pacific coral reef fish.

Coral reef fishes represent an invaluable source of macro- and micro-nutrients for tropical coastal populations. However, several potentially toxic compounds may jeopardize their contribution to food security. Concentrations of metallic compounds and trace elements (MTEs), and persistent organic pollutants (POPs, including pesticides and polychlorobiphenyls PCBs), totalizing 36 contaminants, were measured in coral reef fish from several Pacific islands. The objective of this study was to describe the spatial distribution of these compounds and contaminants in order to identify potential variables explaining their distribution at a Pacific-wide scale. To achieve this, we applied Boosted Regression Trees to model species-specific and community-level contaminant and inorganic compound concentrations at the scale of the tropical Pacific Ocean. Overall, using 15 easily accessible explanatory variables, we successfully explained between 60 and 87% of the global variation, with fish body size being the most important correlate of MTEs and POPs concentrations in reef fish. Our modeling approach allowed us to estimate and map the distribution of the community-level concentration of 19 contaminants and inorganic compounds at the scale of the equatorial and south Pacific Ocean. Spatial patterns varied significantly depending on the compound, with modeled quantities per 100g of fish flesh generally being higher in the central and southwest Pacific than in the eastern part of the basin. These patterns were influenced by a combination of biological, environmental, anthropogenic and biogeographical variables. Overall, this approach represents an important step toward the estimation of concentrations of the main compounds on the basis of species identity and fishing location. Our results enhance our understanding of the extent of contamination in the Pacific while underscoring the urgent need for long-term and large-scale spatial monitoring of diverse compounds in this region.

The occurrence and persistence of surface water contaminants across different landscapes

Surface water contaminants, including both conventional contaminants (e.g., nutrients, trace elements) and emerging contaminants (e.g., pesticides, pharmaceuticals) are heavily influenced by urban and rural land use practices. The goal of the study was to characterize the influence of watershed land use practices on surface water quality. Specific objectives were to (1) identify and quantify the type and concentration of nutrients, trace elements, pesticides, pharmaceuticals and personal care products in four watersheds and (2) understand potential sources of contamination based on the watershed's land cover and land use characteristics (i.e., oil and gas, urban, mining, agriculture). Monthly polar organic chemical integrative samples and water grab samples were collected from March–October 2022. The results showed that surface water quality varied by location, season, and flood condition Specifically, aluminum (mean = 758 μg L−1) and iron (mean = 1130 μg L−1) exceeded chronic aquatic life water quality criteria in the agricultural watershed, while imidacloprid exceeded the chronic criteria limit for freshwater invertebrates in both the urban (mean = 5.96 ng L−1) and agricultural (mean = 4.72 ng L−1) watersheds. Sulfate concentrations (mean = 666 mg L−1) also exceeded ambient water quality criteria in the watershed with a high activity of mining. This study provides important steps for developing a comprehensive understanding of land use impacts on contaminant presence and concentration in surface waters, improved understanding of the implications to non-target species, and necessary water treatment processes to ensure a safe water supply.

Fatty acid carbon isotopes as tracers of trophic structure and contaminant biomagnification in Arctic marine food webs.

Mercury (Hg) and persistent organic pollutant (POP) accumulation among species and biomagnification through food webs is typically assessed using stable isotopes of nitrogen (δ15N) and carbon (δ13C) in bulk (whole) tissues. Yet, bulk isotopic approaches have limitations, notably from the potential overlap of isotope values from different dietary sources and from spatial variation in source (baseline) signals. Here, we explore the potential of fatty acid carbon isotopes (FA δ13C) to (1) evaluate the trophic structure of a marine food web, (2) distinguish feeding patterns among four marine mammal consumers, (3) trace contaminant biomagnification through a food web, and (4) explain interspecific variation in contaminants among high-trophic position predators. In the Cumberland Sound (CS) food web of Nunavut, Canada, ranging from zooplankton to Greenland shark (Somniosus microcephalus), FA δ13C values for the monounsaturated FAs, 20:1 and 22:1 isomers, did not vary across the food web, while the long-chain polyunsaturated FA, 22:6n3 showed δ13C values that were enriched by ~1.5‰ with each trophic position. Values of δ13C for shorter-chain and saturated FAs varied widely across this food web. In East Greenland (EG) marine mammals, FA δ13C values were significantly higher in migratory sub-Arctic species relative to Arctic residents. Linear models using FA δ13C as explanatory variables for contaminant concentrations demonstrated that baseline-corrected δ13C values of certain dietary FAs explained more variation in POP concentrations than did bulk stable isotopes in EG marine mammals. However, bulk δ15N better explained Hg variation in the CS food web. This study details the FA δ13C instrumental methods, such that other researchers can test this novel approach on other species, locations, and food webs to further evaluate whether the δ13C values of certain diet-derived FAs consistently show limited or predictable trophic fractionation and may therefore be useful for assessing the accumulation and biomagnification of lipophilic contaminants.

Computational analysis of ternary hybrid nanofluids mass transport and Bodewadt flow across a rotating disk driven by waste discharge concentration

The amount of substance found in the environment (such as water, soil, and air) relates to the concentration of pollutants. Pollutant concentration analysis is a helpful tool for evaluating how effectively procedures for waste treatment and regulatory constraints reduce contamination concentrations. Because of this, the Bodewadt flow of ternary hybrid nanofluid movement over a stretched disk in the existence of a porous medium and a concentration of pollutants is examined in the current investigation. The present analysis mainly focuses on the impact of external pollution sources on the concentration of pollutants. By applying the appropriate similarity variables, the governing equations for the flow and concentrations, which are in the form of partial differential equations (PDEs), are converted into a system of ordinary differential equations (ODEs). Utilizing graphs, various significant non-dimensional parameters and some engineering coefficient influences will be explained. local pollutant external source parameter and the Lewis number impact on the concentration profile is evaluated. The concentration of the fluid motion improves as the local pollutant external source parameter escalates while reduction of concentration is seen in the case of Lewis number. Enhancement in the volume fraction upsurges the concentration of the fluid motion and drops the velocity of the fluid motion. Raise in the stretching strength parameter, drop the Sherwood number and rises the skin friction coefficient.