New and legacy pesticidal persistent organic pollutants in the agricultural region of the Sultanate of Oman

Comprehensive air and surface soil monitoring was conducted for new and legacy organochlorine pesticides (OCPs) to fill the knowledge and data gap on the sources and fate of pesticidal persistent organic pollutants (POPs) in the Sultanate of Oman. DDTs in agricultural soil samples ranged from 0.013 to 95.80 ng/g (mean: 8.4 ± 25.06 ng/g), with a median value of 0.07 ng/g. The highest concentration was observed at Shinas, where intensive agricultural practice is prevalent. The dominance of p,p'-DDT in soil and air reflected technical DDT formulation usage in Oman. Among newly enlisted POPs, pentachlorobenzene had the maximum detection frequency in air (47%) and soil (41%). Over 90% of sites reflected extensive past use of hexachlorobenzene. Major OCP isomers and metabolites showed net volatilisation from the agricultural soil, thereby indicating concurrent emission and re-emission processes from the soil of Oman. However, the cleansing effect of oceanic air mass is the possible reason for relatively lower atmospheric OCP levels from a previous study. Although DDT displayed maximum cancer risk, the level is below the permissible limit. DDT primarily stemmed from obsolete stock and inadequate management practices. Hence, we suggest there is a need for DDT regulation in Oman.

Heavy metals in five commonly consumed fish species from River Swat, Pakistan, and their implications for human health using multiple risk assessment approaches

This study analyzed the levels of heavy metals bioaccumulation in commonly consumed riverine fish species, including G. cavia, T. macrolepis, G. gotyla, S. plagiostomus, and M. armatus from River Swat in Pakistan, and quantify their potential risk to children and adults in general and fisherfolk communities using multiple pollution and risk assessment approaches. The highest metal detected by inductive coupled plasma mass spectrometry (ICP-MS) was Zn, which ranged from 49.61 to 116.83 mg/kg, followed by Fe (19.25-101.33 mg/kg) > Mn (5.25-40.35 mg/kg) > Cr (3.05-14.59 mg/kg) > Ni (4.26-11.80 mg/kg) > Al (1.59-12.25 mg/kg) > Cu (1.24-8.59 mg/kg) > Pb (0.29-1.95 mg/kg) > Co (0.08-0.46 mg/kg) > Cd (0.01-0.29 mg/kg), demonstrating consistent fluctuation with the safe recommendations of global regulatory bodies. The average bioaccumulation factor (BAF) values in the examined fish species were high (BAF > 5000) for Pb, Zn, Mn, Cu, Cr, Ni, and Cd, bioaccumulate (1000 > BAF < 5000) for Co, and probable accumulative (BAF <1000) for Fe, and Al, while the overall ∑heavy metals pollution index (MPI) values were greater than one (MPI > 1) indicating sever heavy metals toxicity in G. cavia, followed by S. plagiostomus, M. armatus, G. gotyla, and T. macrolepis. The multivariate Pearson's correlation analysis identified the correlation coefficients between heavy metal pairs (NiCr, CuCr, PbCr, AlCo, CuNi, and PbNi), the hierarchical cluster analysis (CA) determined the origin by categorizing heavy metal accumulation into Cluster-A, Cluster-B, and Cluster-C, and the principal component analysis (PCA) discerned nearby weathering, mining, industrial, municipal, and agricultural activities as the potential sources of heavy metals bioaccumulation in riverine fish. As per human risk perspective, S.plagiostomus contributed significantly to the estimated daily intake (EDI) of heavy metals, followed by G.cavia > M.armatus > G.gotyla > T.macrolepis in dependent children and adults of the fisherfolk followed by the general population. The non-carcinogenic target hazard quotient (THQ) and hazard index (HI) values for heavy metal intake through fish exposure were < 1, while the carcinogenic risk (CR) for individual metal intake and the total carcinogenic risk (TCR) for cumulative Cr, Cd, and Pb intake were within the risk threshold of 10-6-10-4, suggesting an acceptable to high non-carcinogenic and carcinogenic risk for both children and adults in the fisherfolk, followed by the general population.

A global review on perfluoroalkyl acids (PFAAs) in the riverine systems: Environmental behaviours and risks implications

This review provides a comprehensive global overview of the occurrences, distribution, emissions, and associated risks of perfluoroalkyl acids (PFAAs) in riverine systems across both developed and developing countries including the United States (US), Spain, France, Netherlands, Germany, Pakistan, China, Korea, Vietnam, Italy, and Japan. Data for this review were systematically gathered through a comprehensive and structured search process using various databases, search engines, and academic repositories to identify relevant literature and studies. Human health risks were assessed using recommended United States Environmental Protection Agency (USEPA) models, including estimated daily intake (EDI), hazard risk (HR), and hazard index (HI) for each reported PFAA compound in the studied countries. The overall results revealed significant variability in PFAAs contamination from the 1950s to 2023, reflecting extensive industrial usage and increasing environmental concerns, with levels often exceeding the permissible limits set by environmental quality standards established by national or international regulatory authorities, agencies, and organizations. Among the studied countries, Italy exhibited the highest average sum of PFAA compounds (∑PFAAs) concentration in riverine water, ranging from 4.07 to 140.61 ng/L, with an average of 41.37 ng/L, followed by the Netherlands, China, Japan, the US, Pakistan, Spain, France, Germany, Korea, and Vietnam. Similarly, Germany showed the highest average ∑PFAAs concentration in riverine sediments, ranging from 40.25 to 213.00 ng/g, with an average of 126.63 ng/g, followed by China, Spain, the US, Pakistan, Vietnam, and Korea. Whereas, in riverine fish, Spain had the highest average ∑PFAAs concentration, ranging from 0.05 to 144.97 ng/g, with a mean of 15.94 ng/g, followed by Korea, Vietnam, and the US. From a human risk perspective, the highest average EDI of ∑PFAAs via riverine water consumption was observed in the dependent population of Italy (2.02 × 10-3 ng/L/day), followed by the Netherlands (8.24 × 10-4 ng/L/day), the US (5.56 × 10-4 ng/L/day), Pakistan (3.99 × 10-4 ng/L/day), Japan (3.69 × 10-4 ng/L/day), France (3.42 × 10-4 ng/L/day), China (2.58 × 10-4 ng/L/day), Spain (2.43 × 10-4 ng/L/day), Germany (1.17 × 10-4 ng/L/day), Korea (6.01 × 10-5 ng/L/day), and Vietnam (1.28 × 10-5 ng/L/day). For fish consumption, Spain recorded the highest average EDI of ∑PFAAs (9.92 × 100 ng/g/day) in its dependent population, followed by the US (3.44 × 100 ng/g/day), Korea (8.13 × 10-1 ng/g/day), and Vietnam (4.99 × 10-1 ng/g/day). The non-carcinogenic HR values for individual PFAA compounds via riverine water intake in the dependent populations of both developed and developing countries were within acceptable limits (<1). However, the HI values for ∑PFAAs intake via riverine fish consumption in the dependent population exceeded the threshold (>1) in the developed countries, the US and Spain, indicating higher potential risks associated with fish consumption in these countries. Given the inadequate wastewater treatment facilities in many regions, coupled with untreated runoff from urban areas and agricultural fields draining directly into rivers, this study underscores the urgent need for integrated prevention and control measures to mitigate PFAAs contamination in riverine systems and reduce associated risks. Ultimately, stricter regulations, improved monitoring, and enhanced water treatment technologies are crucial to reducing PFAAs contamination and safeguarding public health.

Spatial distribution and health risks assessment of heavy metals in e-waste dumping sites from Pakistan

The present study focused on to determine the concentration and health risk of heavy metals (Cu, Pb, Zn, Cd, Hg, Cr) in e-waste contaminated soils collected from different provinces of Pakistan. Further, the impact of heavy metals on soil enzyme activities and microbial community was also investigated. The concentration (mg/kg) of Hg, Zn, Fe, Cu, Pb, Cd, and Cr ranged between 0-0.258, 2.284-6.587, 3.005-40.72, 8.67-36.88, 12.05-35.03, 1.03-2.43, and 33.13-60.05, respectively. The results revealed that Lahore site of Punjab province indicated more concentration of heavy metals as compared to other sites. The level of Cr at all sites whereas Hg at only two sites exceeds the World Health Organization standards (WHO) for soil. Soil enzyme activity exhibited dynamic trend among the sites. Maximum enzyme activity was observed for urease followed by phosphatase and catalase. Contamination factor (Cf), Pollution load index (PLI), and geo-accumulation index (Igeo) results showed that all the sites are highly contaminated with Cu, Cd, and Pb. Hazard index (HI) was less than 1 for children and adults suggesting non-carcinogenic health risk. Principle component analysis results depicted relation among Cr, Fr, catalase, and actinomycetes; Cd, OM, urease, and bacteria, and Pb, Cu, Zn, Hg, and phosphatase, suggesting soil enzymes and microbial community profiles were influenced by e-waste pollution. Therefore, there is a dire need to introduce sustainable e-waste recycling techniques as well as to make stringent e-waste management policies to reduce further environmental contamination.

Population exposure to emerging perfluoroalkyl acids (PFAAs) via drinking water resources: Application of multivariate statistics and risk assessment models

This study assessed the occurrence, origins, and potential risks of emerging perfluoroalkyl acids (PFAAs) for the first time in drinking water resources of Khyber Pakhtunkhwa, Pakistan. In total, 13 perfluoroalkyl carboxylic acids (PFCAs) with carbon (C) chains C4-C18 and 4 perfluoroalkyl sulfonates (PFSAs) with C chains C4-C10 were tested in both surface and ground drinking water samples using a high-performance liquid chromatography system (HPLC) equipped with an Agilent 6460 Triple Quadrupole liquid chromatography-mass spectrometry (LC-MS) system. The concentrations of ∑PFCAs, ∑PFSAs, and ∑PFAAs in drinking water ranged from 1.46 to 72.85, 0.30-8.03, and 1.76-80.88 ng/L, respectively. Perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), and perfluoropentanoic acid (PFPeA) were the dominant analytes in surface water followed by ground water, while the concentration of perfluorobutane sulfonate (PFBS), perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), and perfluorododecanoic acid (PFDoDA) were greater than long-chain PFOA and PFOS. The correlation statistics, which showed a strong correlation (p < 0.05) between the PFAA analytes, potentially indicated the fate of PFAAs in the area's drinking water sources, whereas the hierarchical cluster analysis (HCA) and principal component analysis (PCA) statistics identified industrial, domestic, agricultural, and commercial applications as potential point and non-point sources of PFAA contamination in the area. From risk perspectives, the overall PFAA toxicity in water resources was within the ecological health risk thresholds, where for the human population the hazard quotient (HQ) values of individual PFAAs were < 1, indicating no risk from the drinking water sources; however, the hazard index (HI) from the ∑PFAAs should not be underestimated, as it may significantly result in potential chronic toxicity to exposed adults, followed by children.

Pathways and risk analysis of arsenic and heavy metal pollution in riverine water: Application of multivariate statistics and USEPA-recommended risk assessment models

This study analyzed surface water from the River Swat, Pakistan, using inductively coupled plasma mass spectrometry, multivariate statistical techniques, and US-EPA risk assessment models to evaluate the concentrations, distribution, pathways, and potential risks of arsenic (As) and heavy metals, including chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg), and lead (Pb). The results revealed significant correlations (p ≤ 0.01) among metals that indicated common pollution sources, likely influenced by anthropogenic point and non-point activities. Along the monitored sites (S1-S10), the mass flow of ∑metals showed a dynamic pattern: progressively increasing downstream, decreasing at S6-S7, rising again at S7-S8, and then steadily declining toward S10, with Ni being the most abundant metal, followed by Cr > As> Cu > Mn > Co > Zn > Hg > Cd > Pb. The As and Heavy Metal Pollution Index (HPI), As and Heavy Metal Evaluation Index (HEI), and Pollution Index (PI) revealed variations in pollution levels, ranking the metals in the orders of Co > As> Cr > Cd > Mn > Hg > Ni > Pb > Cu > Zn, As> Cr > Ni > Hg > Cd > Co > Mn > Cu > Zn > Pb, and Hg > Ni > As> Co > Cu > Cd > Mn > Zn > Pb, respectively. However, according to the risk assessment, overall individual metal contamination in the River Swat water was below the ecological risk threshold (ERI 〈110). Where, the Chronic Daily Intakes (CDIs), Hazard Quotients (HQs), Hazard Indices (HIs), Cancer Risks (CRs), and Total Cancer Risks (TCRs) of Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Hg, and Pb associated with daily river water intake and dermal contact indicate that long-term exposure to untreated river water may pose both carcinogenic and non-carcinogenic health risks to residents.

Nano round polycrystalline adsorbent of chicken bones origin for Congo red dye adsorption

Nano round polycrystalline adsorbent (NRPA) of chicken bones origin was utilize as effective adsorbent in Congo red dye removal via aqueous media. The NRPA adsorbent was prepared via thermal decomposition and its structure was investigated with the aids of Transmission Electron Microscopy, Fourier Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy, Energy Dispersive X-ray Analysis (EDX), and X-ray Diffractometer (XRD). A monophasic apatite phase was confirmed from XRD investigation, while functional groups analysis showed that NRPA possessed CO32-, PO43- and OH- absorption bands. The maximum adsorption capacities derived from Langmuir isotherm is 98.216 mg g-1. From the combined values of n from Freundlich and separation factor (RL) of Langmuir models, the adsorption of CR by NRPA is favourable. Thermodynamic values of 5.280 kJ mol-1 and 16.403 kJ mol-1 K-1 were found for ΔH° and ΔS° respectively. The entire values of ΔG° which ranges from - 35.248 to - 459.68 kJ mol-1 were all negative at different temperatures. Thus, nano polycrystalline adsorbent of chicken bone origin can serve as excellent adsorbent in Congo red dye removal from waste water.

Deoxygenation turns the coastal Red Sea lagoons into sources of nitrous oxide

Direct measurements of dissolved N₂O concentrations, fluxes and saturation percentages undertaken for the first time in two coastal lagoons - Al-Shabab and Al-Arbaeen, along the east coast of the Red Sea, revealed the region as a significant source of N₂O to the atmosphere. The exacerbated dissolved inorganic nitrogen (DIN) from various anthropogenic sources led to substantial oxygen depletion in both the lagoons, which turned to bottom anoxia at Al-Arbaeen lagoon during the spring season. We assume that the accumulation of N₂O is caused by nitrifier-denitrification in the hypoxic/anoxic boundaries. In fact, the results indicated that oxygen-depleted bottom waters favoured denitrification when the oxygenated surface waters recorded nitrification signals. Overall, the N₂O concentration ranged from 109.4 to 788.6 nM (40.6-325.6 nM) in spring and 58.7 to 209.8 nM (35.8-89.9 nM) in winter in the Al-Arbaeen (Al-Shabab) lagoon. The N₂O flux ranged from 647.1 to 1763.2 μmol m^-2 day^-1 (85.9 to 160.2 μmol m^-2 day^-1) and 112.5 to 150.8 μmol m^-2 day^-1 (76.1 to 88.7 μmol m^-2 day^-1) in the spring and winter respectively, in the Al-Arbaeen (Al-Shabab) lagoons. The ongoing developmental activities may worsen the current situation of hypoxia and associated biogeochemical feedbacks; therefore, the present results underline the need for continuous monitoring of both lagoons to restrict more severe oxygen depletion in future.

A review of heavy metals pollution in riverine sediment from various Asian and European countries: Distribution, sources, and environmental risk

Riverine sediments are important reservoirs of heavy metals, representing both historical and contemporary anthropogenic activity within the watershed. This review has been conducted to examine the distribution of heavy metals in the surface sediment of 52 riverine systems from various Asian and European countries, as well as to determine their sources and environmental risks. The results revealed significant variability in heavy metal contamination in the world's riverine systems, with certain hotspots exhibiting concentrations that exceeded the permissible limits set by environmental quality standards. Among the studied countries, India has the highest levels of chromium (Cr), cobalt (Co), manganese (Mn), nickel (Ni), zinc (Zn), cadmium (Cd), copper (Cu), and lead (Pb) contamination in its riverine systems, followed by Iran > Turkey > Spain > Vietnam > Pakistan > Malaysia > Taiwan > China > Nigeria > Bangladesh > Japan. Heavy metal pollution in the world's riverine systems was quantified using pollution evaluation indices. The Contamination Factor (CF) revealed moderate contamination (1 ≤ CF < 3) throughout the geological units, with the exception of Pb, Cd, and Cu. The Contamination Degree (CD) classifies the contamination level into different categories: Low degree of contamination (CD < 6), moderate degree of contamination (6 ≤ CD < 12), considerable degree of contamination (12 ≤ CD < 24), and a very high degree of contamination (CD ≥ 24), while the Pollution Load Index (PLI) estimate the total amount of heavy metal pollution in riverine sediments, with Turkey having the highest PLI value of 6.512, followed by Spain, Vietnam, Taiwan, Pakistan, Bangladesh, China, India, Japan, Malaysia, Iran, and Nigeria. In applied multivariate statistics, correlation analysis determined the fate and distribution of heavy metals in riverine systems, while Principal Component Analysis (PCA) elucidated the potential sources, including industrial, agrochemical, mining, and domestic wastewater discharges, lubricant leakages, multiple geogenic inputs, erosion of mafic and ultramafic rocks, and minimal atmospheric deposition. As per Potential Ecological Risk Index (PERI) perspectives, Vietnam, Spain, and Turkey have the highest ecological risk, followed by Nigeria > Pakistan > Bangladesh > China > Taiwan > Japan and Iron, while the potential risks of ∑non-carcinogenic Pb, Cr, Ni, Cu, Cd, Co, Zn, and Mn for exposed human children and adults through ingestion and dermal contact were significantly influenced between acceptable to high risk, necessitating special attention from pollution control agencies.

Bioactivity properties of hydroxyapatite/clay nanocomposites

The need for bioactive and non-toxic biomaterials is on a high demand in tissue engineering applications nowadays. Hydroxyapatite (HAp) is the chief constituent of teeth and bones in mammas. One of the major challenges with the use of HAp in engineering application is its brittleness and to overcome this, it's important to react it with a material that can enhanced it's fragility. To this end, HAp and HAp/clay nanocomposites were developed via wet chemical process to mimic natural HAp and to equally confer special properties such as mechanical properties, high surface area, crystallinity, high porosity, and biocompatibility on the biomaterial. The functional groups properties of the as-prepared nanocomposites analyzed by FT-IR showed that the HAp and clay posed reactive centers such as Al-Al-OH, Si-Si-OH, Si-O, PO43-, -OH, and Si-O-Al. The XRD results confirmed the formation of HAp/clay nanocomposite, while SEM and TEM images showed the morphologies of the prepared nanocomposites to be round shape particles. Besides, EDX result revealed the Ca/P ratio of HAp and HAp-C to be lower than that of stoichiometric ratio (1.67) which implies the presence of K, Na, Ca, Mg, Si and Al in the HAp/clay nanocomposite. The mechanical properties of the apatite were greatly enhanced by the addition of clay. The physiological behaviour of the fabricated apatite composites in saline solution showed steady increase in the values of the saline pH of the various biomolecules until day 5 and became fairly constant at day 7 with pH range of 7.30-7.38. Though the saline solution was acidic at the beginning due to dissolved carbon dioxide, the pH of the saline solution containing the nanocomposites gradually became neutral and fairly alkaline over time as a result of the presence of Lewis basis structures in the composites which helps in neutralizing the acidic solution. Furthermore, proliferation of apatites particles onto the surface of the nanocomposites was observed after treatment with simulated body fluids (SBF) media for 7 days. Thus, HAp/clay nanocomposites can be useful biomaterials in bone tissue engineering.

The assessment of environmental parameter along the desalination plants in the Kingdom of Saudi Arabia

The Kingdom of Saudi Arabia obtains the most desalination water from the Red Sea. In Saudi Arabia, 14 desalination plants receive water from the Red Sea, and three are located in the country’s east and rely on the Arabian Gulf. The study has observed 16 desalination plants out of 17 desalination plants in the kingdom. Most of the desalination plants in Saudi Arabia currently use the advanced technologies to produce potable water with less impact on the surrounding environment. The current study examined the variation of hydrographic parameters along all available desalination plants in Saudi Arabia. This is the first inter-annual database of hydrographic parameters in the last 4 years. The peak salinity was measured at the Duba desalination plant in 2020, and it was 67.2 ppt. During 2018, the Azizia desalination plant reported the lowest value of 36.8 ppt. The maximum temperature recorded at the Qunfudah desalination plant in 2019 was 34.6°C. In 2017, the minimum temperature was 19.1°C at the Jubail desalination plant. The level of dissolved oxygen and pH were likewise not significantly changed along the brine outflow and in the outfall, in contrast to temperature and salinity. On the basis of 4 years’ of data from observed desalination facilities, the current study sheds light on the less environmental impact with regard to hydrographic factors.

Polychlorinated biphenyls induced toxicities upon cell lines and stem cells: a review

Polychlorinated biphenyls (PCBs) are persistent organic pollutants emitted during e-waste activities. Upon release into the environment, PCBs can pose harmful effects to the humans and environment. The present review focused on the effects of PCBs on cell proliferation, apoptosis, functional and developmental toxicity and potential possible molecular mechanisms upon cells and stem cells. The review also highlights the effects of low- and high-chlorinated, and dioxin and non-dioxin PCBs. The review suggested that high chlorinated and dioxin like PCBs at higher concentrations posed more toxic effects to cells and stem cells. PCBs at higher levels induced hepatotoxicity, carcinogenicity, reproductive toxicity, neurotoxicity and lung cell toxicity. PCBs triggered reactive oxygen species which actives mitogen activated pathways, nuclear factor and cytochrome pathway for cell proliferation and apoptosis. Further, review highlights PCBs induced toxicity in stem cells with the focus on developmental and functional toxicity. The review could be useful to understand the PCBs toxicities and mechanisms and will guide to policy makers to design policies for e-waste pollutant.