Bioaccumulation of Heavy Metals in Water, Sediments, and Tissues and Their Histopathological Effects on Anodonta cygnea (Linea, 1876) in Kabul River, Khyber Pakhtunkhwa, Pakistan

Reconnaissance Survey of Organic Contaminants of Emerging Concern in the Kabul and Swat Rivers of Pakistan

The Swat and Kabul rivers of northern Pakistan are within an important regional watershed that supports river-based livelihoods and is impacted by untreated effluent discharges and municipal solid waste. Evidence indicates that fish populations are decreasing in these rivers. One potential cause of poor aquatic health is pollution; therefore, we investigated the presence of contaminants of emerging concern (CECs) in the river systems. Water samples were collected in the Kabul River (n = 9) and Swat River (n = 10) during seasons of high (summer 2018) and low (winter 2019) river flow. Agrochemicals, pharmaceuticals, plasticizers, chemicals in personal care products, and hormones were quantified via liquid chromatography high-resolution mass spectrometry. In the Swat River, caffeine (18-8452 ng/L), N,N-diethyl-meta-toluamide (DEET; 16-56 ng/L), and plasticizers (13-7379 ng/L) were detected at all sites during both seasons, while butachlor (16-98 ng/L) was detected only during high flow. In the Kabul River, caffeine (12-2081 ng/L) and several plasticizers (91-722 ng/L) were detected at all sites during both seasons, while DEET (up to 97 ng/L) was detected only during high flow. During low flow, pharmaceuticals (analgesics and nonsteroidal anti-inflammatory drugs) were quantified in both rivers (up to 823 ng/L), with detection frequencies from 70% to 100% and 0% to 78% in the Swat and Kabul Rivers, respectively. Intermittent-use and natural seasonal processes (increased runoff and dilution from rainfall and snowmelt) yielded higher agrochemical concentrations and lower concentrations of continuous-use compounds (e.g., caffeine) during high flow. The present study provides the first insight into CEC concentrations in the Swat River, additional insight into the Kabul River stressors, and, overall, contaminant risks to aquatic life. Environ Toxicol Chem 2023;42:2599-2613. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Metal transportation mechanism by rainfall runoff as a contribution to the bioaccumulation in seafood

Trace metal transport mechanism via rainfall runoff from soil to the water body in the context of the bioaccumulation in seafood was unprecedentedly investigated. Instead of a conventional simulation experiment at a laboratory, the twelve soil sampling sites were selected in the region (Windar Valley, Balochistan-Pakistan) reported with high trace metal content, and Threadfin Sea Catfish and Belanger's Croaker were caught from the adjacent coastal water body. The Pb, Cd, Ni, and Zn in soil samples were high in proportion; the average concentrations were 2793.8, 622.44, 331.33, and 440 in mg kg^-1, respectively, as per expectations. Using ArcGIS, the soil sample results were extensively illustrated by the spatial distribution in the sampling regions. The Zn > Pb > Ni > Cd was found in pre- and post-rainfall fish flesh samples. Trace metals were higher in post-rain fish flesh samples than pre-rainfall samples, indicating that rainwater runoff could be the significant source for trace metal transport except for Zn. The Pb, Cd, Ni, and Zn elevated results were 0.80828 ± 0.17752, 0.12102 ± 0.03027, 0.71064 ± 0.24188, and 6.49223 ± 3.65094 in mg kg^-1, respectively, in post-rainfall fish flesh samples. Appling chemometric tools revealed that Zn content depends on Zn-protein interaction, and Pb, Cd, and Ni contents significantly pertain to the rainwater runoff. Other probable transport routes for trace metals to the water body could be less responsible. The soil sampling region's NOAA HYSPLIT backward air trajectory showed that the air direction was mostly from ocean to land.

An integrated approach to address the temporal variation of geochemistry in groundwater of an arid region

Kuwait is characterized with an arid climate and scarce freshwater sources. Variation in groundwater quality with space and time leads to sustainable development of the region. Evaluating the chemical properties of groundwater is of prime importance to ensure the longevity of this important source of water. In this study, the geochemical data for the years 2004 and 2018 were examined for 6 wells in the freshwater zones of Northern Kuwait. The aim of this study is to examine the geochemical variations, if any that occurred on the only existing freshwater aquifer in Kuwait. The chemical properties examined in this study include total dissolved solids, chloride, nitrate, bicarbonate, calcium, electric conductivity, sulfate, sodium, potassium, magnesium, and pH. The variation of the electrical conductivity in this region indicates an improvement in three wells located in the northern to central region of the study area as values decreased from 1210 to 956 (μS/cm); however, the electrical conductivity has deteriorated in the remaining three wells located in the central to southern part of the study area as values increased from 791 to 1401 (μS/cm). The geochemical facies of the groundwater were determined, indicating a migration of the groundwater facies towards more chloride dominant field in 2018. The saturation states of carbonates like aragonite, calcite, dolomite, and magnesite and those of sulfates like gypsum and anhydrite were determined. The increase in calcium in most of the wells facilitated the saturation index of calcium sulfates relatively more than calcium carbonate minerals. The principal component analysis was conducted for the data of 2004 and 2018; it extracted two main components accounting for the variability of the data; the main components indicate geogenic influences and anthropogenic pollution such as agriculture. The study indicates that there is no major variation observed in groundwater chemistry during the 15 years, as the chemical changes which occurred are minimal and do not require immediate remediation measures. Hence, if the current groundwater extraction rate remained with no extensive land use development, it would sustain the water quality of the region.

Sediment-associated heavy metal contamination and potential ecological risk along an urban river in South Africa

Sediment contamination by heavy metals poses one of the worst environmental risks to aquatic ecosystems worldwide. The study explored sediment-associated heavy metal contamination and potential ecological risk along the Molopo River in Mahikeng, South Africa. Total concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) were analysed using inductively coupled plasma mass spectrometry. Various indices were applied to assess the level of contamination and ecological risk. Most heavy metal concentrations at selected upstream and downstream sites were below average shale, except Cr, Cu, Hg, Pb, and Zn. The contamination factor (CF) indicates that the level of contamination was low (CF < 1) at most sampling sites, except Cr, Cu, Pb and Zn, which varied from moderate (1 CF < 3) to considerable (3 ≤ CF < 6) contamination. The enrichment factor (EF) shows that Cd, Cr, Cu, and Zn were moderate (2 EF < 5) to significantly enriched (5 EF < 20) at the affected sites. The results suggest anthropogenic enrichment (EF > 2) of Cd, Cr, Cu, and Zn. The threshold effect concentration and probable effect concentration sediment quality guidelines predicted that Cr, Cu, and Ni concentrations were more likely to have harmful effects on bottom-dwelling organisms. Pearson correlation and principal component analysis reveal that Cd, Cr, Cu, Ni, Pb, and Zn had a common anthropogenic source. We attribute the source to industrial and wastewater effluent, vehicle traffic, and runoff from various urban surfaces in the city. The study provides baseline data for heavy metal monitoring in the study area. Future research and monitoring should focus on heavy metals that cause concern because of their concentrations (Cr, Cu, Pb, and Zn) and potential ecological risk (Cr, Cu, and Ni).

Water quality and health risk assessment of trace elements in surface water at Punjnad Headworks, Punjab, Pakistan

Pollution of the aquatic ecosystem due to different trace elements has become a global concern which has raised health-related issues for both aquatic and human life. Industrial and agricultural water run-off drained into the rivers and deposit trace elements in water, sediments and planktons. This study was designed to calculate the burden of trace elements such as aluminium (Al), arsenic (As), barium (Ba), and lead (Pb) in the river water of Punjnad Headworks, Bahawalpur, Punjab, Pakistan. Samples were collected from surface water, bed sediments and planktons during autumn, winter and spring seasons (September 2018 to May 2019). The results showed that the concentration of Pb was highest in surface water (453.87 mg L^-1), while that of Al was highest in sediments (370.24 µg g^-1) and plankton (315.05 µg g^-1). A significant difference was found in metal concentrations among surface water, bed sediments and plankton at different sampling stations during various seasons. Importantly, the Exp_ing (0.71, 1.23^-3, 0.34, 0.02 for Pb, As, Al, and Ba, respectively) and Exp_derm (7.09^-8, 1.23¹⁰, 3.42^-8, and 2.48^-9 for Pb, As, Al, and Ba, respectively) for trace elements were below 1.0 suggesting non-significant adverse effects of trace elements on human health. This study provided better understanding of various pollutants and their concentrations in water sources at the studied location.

Toxicological Evaluation of Acetylsalicylic Acid in Non-Target Organisms: Chronic Exposure on Mytilus galloprovincialis (Lamarck, 1819)

Pharmaceuticals are now considered to be established contaminants, and their presence in water poses a real risk not only to the marine ecosystem, as they may adversely affect non-target organisms that are exposed to them, but also indirectly to humans. This is particularly true for the model organism considered in this work, Mytilus galloprovincialis (Lamarck, 1819), a suspensivore and bioaccumulating organism that enters the human food chain. Among the most commonly used over-the-counter medicines, anti-inflammatory drugs certainly feature prominently, with acetylsalicylic acid (ASA) at the top. In this work, M. galloprovincialis specimens were exposed to two concentrations of ASA (10 and 100 μg/L) for 10 and 20 days to evaluate possible alterations in the decrease in regulatory volume (RVD) in digestive gland cells and cell viability of both these cells and hemocytes. In addition, the histopathological condition index of the gills and digestive gland was evaluated. The data obtained showed that chronic exposure to ASA did not alter the cell viability of hemocytes and digestive gland cells but alters the physiological mechanisms of volume regulation in the digestive gland and, in addition, a time-dose reaction to ASA in the gills and digestive gland showing numerous alterations such as lipofuscin deposits and hemocyte infiltration was found. These results confirm the potential toxicity to the marine biota, highlighting the necessity to deepen the knowledge regarding the link between over-the-counter pharmaceuticals and non-target organisms.

Groundwater-Based Drinking Water Supply in Sri Lanka: Status and Perspectives

Drinking water is largely from groundwater in Sri Lanka, so quality management is of great concern. In order to achieve the 6th goal of United Nations (UN) Sustainable Development Goals (SDG), more efforts are being undertaken to secure drinking water quality. In this paper, the current status, challenges and opportunities of groundwater quality management and improvement in Sri Lanka were reviewed and discussed, based on previous studies. There are Ca-HCO3 type, Ca–Mg-HCO3 type and Na–SO4–Cl type groundwater dominated in the wet zone, intermediate and the dry zone, respectively. Elevated levels of hardness, fluoride, DOC, and alkalinity, and salinity are reported in the groundwater in the dry zone controlled by geology and arid climate. Although groundwater in some regions contain significant levels of nitrates, arsenic, cadmium and lead, the majority remain at acceptable levels for drinking purposes. As for treatment technologies, existing membrane-based drinking water treatment technologies such as RO (Reverse Osmosis) stations can produce safe and clean drinking water to the community, but this has still a limited coverage. To achieve a safe drinking water supply for all, especially in rural communities of Sri Lanka under the 6th goal of the UN SDG, more efforts in building up the infrastructure and man power are needed to monitor and assess groundwater quality regularly so as to develop management strategies. Research and development can be directed towards more cost-effective water treatment technologies. Protection of groundwater from being polluted, and educational and awareness programs for the stakeholders are also essential tasks in the future.

Accumulation and Distribution of Nanoparticles (Al2O3, CuO, and TiO2) in Tissues of Freshwater Mussel (Unio tigridis)

Freshwater mussels are used as an effective bioindicator of metal pollution. There is no data on the accumulation of any metal-oxide nanoparticles (NPs) in tissues of Unio tigridis. Thus, this study was undertaken to investigate accumulation of Al₂O₃, CuO, and TiO₂ NPs following exposure to different concentrations (0, 1, 3, and 9 mg/L) of NPs for 14 days. Metal concentrations in tissues were determined by ICP-MS, while NP presence was demonstrated by transmission electron microscope (TEM) images. During the experiments, mussels were fed with cultured algae (Chlorella vulgaris). TEM images demonstrated the presence of NPs in digestive gland and muscle. TEM images also suggested that NPs were taken via the lysosomes or endosomes. Highest mean concentrations (µg/g d.w.) of aluminium (76.51), copper (111.63) and titanium (113.83) occurred in the gills and followed by the digestive glands and muscles. Algae consumption of mussels did not significantly differ among controls and NP-exposed groups.

Food Contamination: An Unexplored Possible Link between Dietary Habits and Parkinson’s Disease

Importance of a healthy lifestyle in maintaining the population’s well-being and health, especially in terms of balanced nutrition, is well known. Food choice of and dieting habits could impact disease management, which is especially true for Parkinson’s disease (PD). However, nowadays, it is not that simple to maintain a balance in nutrition, and the idea of a healthy diet tends to fade as the consequence of a western lifestyle. This should not only be dealt with in the context of food choice, but also from an environmental point of view. What we put into our bodies is strictly related to the quality of ecosystems we live in. For these reasons, attention should be directed to all the pollutants, which in many cases, we unknowingly ingest. It will be necessary to explore the interaction between food and environment, since human activity also influences the raw materials destined for consumption. This awareness can be achieved by means of an innovative scientific approach, which involves the use of new models, in order to overcome the traditional scientific investigations included in the study of Parkinson’s disease.

Changes in the contour of karyology and histoarchitecture of the primary respiratory organ in the fish Oreochromis mossambicus (Peters, 1852) inhabiting the polluted estuarine ecosystem

The wetland ecosystem (WE) is subject to pollution by many anthropogenic activities, including domestic and industrial effluents. These effluents may contain toxic heavy metals that can interact within the aquatic ecosystem and have a capacity to disturb the metabolic activities, histological profile, and genetic structure and functions in aquatic species inhabiting the environment. The present study observed the karyological and histological alterations in gills of the freshwater fish, Mozambique tilapia, Oreochromis mossambicus in two different sublethal concentrations (1% and 3%) of heavy metals in 7, 15, and 30 days of experimental periods. The heavy metals induced various structural damages such as ring chromosome, sister chromatid exchange, acrocentric association region, condensed chromosomal morphology, heterochromatin region, and nucleolar organizer region in the chromosomes of O. mossambicus treated with 1% and 3% sublethal concentrations of water sample collected from Pallikaranai wetland ecosystem. Gills exposed to 1% and 3% effluent exhibited several variations in the respiratory surfaces of gill arches or lamellae in the light and scanning microscopical study. The gills exposed to 1% concentration for 30 days showed marked necrosis, and the secondary lamellae showed the lamellar membrane's dissolution. Exposure of gills to raw effluent in the field condition was observed in the presence of Cd, Pb, Cr, Cu, and Zn. Thus, this present study shows the environmental deterioration by heavy metal pollution on the structure of the gills in tilapia.

Silver Nanoparticles Grown on Cross-Linked Poly (Methacrylic Acid) Microspheres: Synthesis, Characterization, and Antifungal Activity Evaluation

Silver nanoparticles (AgNPs) exert profound physicochemical, biological, and antimicrobial properties, therefore, they have been extensively studied for a variety of applications such as food packaging and cultural heritage protection. However, restrictions in their stability, aggregation phenomena, and toxicity limit their extensive use. Hence, the use of functional substrates that promote the silver nanoparticles’ growth and allow the formation of uniform-sized, evenly distributed, as well as stable nanoparticles, has been suggested. This study reports on the fabrication and the characterization of hydrophilic polymer spheres including nanoparticles with intrinsic antifungal properties. Poly (methacrylic acid) microspheres were synthesized, employing the distillation precipitation method, to provide monodisperse spherical substrates for the growth of silver nanoparticles, utilizing the co-precipitation of silver nitrate in aqueous media. The growth and the aggregation potential of the silver nanoparticles were studied, whereas the antifungal activity of the produced nanostructures was evaluated against the black mold-causing fungus Aspergillus niger. The produced structures exhibit dose-dependent antifungal activity. Therefore, they could potentially be employed for the protection and preservation of cultural heritage artifacts and considered as new agents for food protection from fungal contamination during storage.

MicroRNA-mediated stress response in bivalve species

Bivalve mollusks are important aquatic organisms, which are used for biological monitoring because of their abundance, ubiquitous nature, and abilities to adapt to different environments. MicroRNAs (miRNAs) are small noncoding RNAs, which typically silence the expression of target genes; however, certain miRNAs directly or indirectly upregulate their target genes. They are rapidly modulated and play an essential role in shaping the response of organisms to stresses. Based on the regulatory function and rapid alteration of miRNAs, they could act as biomarkers for biotic and abiotic stress, including environmental stresses and contaminations. Moreover, mollusk, particularly hemocytes, rapidly respond to environmental changes, such as pollution, salinity changes, and desiccation, which makes them an attractive model for this purpose. Thus, bivalve mollusks could be considered a good animal model to examine a system's response to different environmental conditions and stressors. miRNAs have been reported to adjust the adaptation and physiological functions of bivalves during endogenous and environmental stressors. In this review, we aimed to discuss the potential mechanisms underlying the response of bivalves to stressors and how miRNAs orchestrate this process; however, if necessary, other organisms' response is included to explain specific processes.

Individual and combined toxicogenetic effects of microplastics and heavy metals (Cd, Pb, and Zn) perturb gut microbiota homeostasis and gonadal development in marine medaka (Oryzias melastigma)

Currently, microplastics (MPs) attracted increased attention for their ubiquity and toxic properties. In this study, marine medaka was used to explore the individual and combined toxicity of heavy metals (HMs) and MPs on intestinal bacteria and gonadal development. After exposure to environmentally relevant concentrations of MPs and HMs, significant alterations of intestinal microbiota were found. The MPs treatment reduced the diversity and abundance of intestinal microbiota, while the HMs and MPs-HMs treatments increased them, which were confirmed by the abundance changes of Proteobacteria. According to the KEGG analysis, the metabolism and environmental information processing (EIP) pathways in the microbial community were significantly affected. This study showed that the MPs-HMs treatment caused a higher pollution load on the gut of the marine medaka, and triggered more significant changes of specific bacterial species and gut function in the males. However, during the gonadal development, HMs and MPs-HMs treatments resulted in empty follicles (EF) and follicular atresia (FA), and altered the gene expression levels related to hypothalamic-pituitary-gonadal (HPG) axis. In short, this study demonstrated that the reproductive disturbance was mainly due to HMs, but the combination of MPs and HMs did not strengthen the risk to the gonad development of the marine medaka.

Environmental and socioeconomic factors induced blood lead in children: an investigation from Kashmir, India

Blood lead toxicity has been prominently related to vehicular emissions. The lead is a carcinogenic metal systematically damages bones and central nervous system. The present investigation is focused on likely impacts of environmental and socioeconomic factors on the concentration of blood lead levels in children. The findings of the study show that the highest blood lead levels were observed in the age group of 4-8 years (5.46 μg/dl) with mother's education having an inverse proportionality with the blood lead levels of children. Furthermore, children belonging to families with income (> 100,000) exhibited the highest blood lead levels (5.52 μg/dl) than the rest of the categories which was further advocated by lower blood lead levels in children residing in better residential conditions. High proximity of school to highway distance seemed to play a vital role in the concentration of lead in children while the traffic flow density was observed to have proportionality effect on the blood lead levels. From the study, it is concluded that 28% of the children in the sample population were having lead levels above the permissible limits as per Centre for Disease Control and Prevention. The study reflects the alarming toxicity of lead in children residing in a non-industrial region which further gives rise to concerns about the health of the children residing in industrialized regions of the world with high lead levels in the environment.