Ecological risk assessment of microplastics and mesoplastics in six common fishes from the Bay of Bengal Coast.

Plastic particles have emerged as a growing threat to both ecosystems and human well-being, as they are being ingested and accumulate at different trophic levels. However, microplastic and mesoplastic contamination and its risk to coastal and marine water fish have not been well studied, particularly in the northern Bay of Bengal. In this study, the presence of small-scale plastic particles (micro- and meso-sized) in the gastrointestinal tract (GIT) and muscles of six edible fish species from the northern Bay of Bengal Coast were identified and analyzed. The overall range of microplastics was 1.74 ± 0.23-3.79 ± 2.03items/g in muscle and 0.54 ± 0.22-5.96 ± 3.16 items/g in the GIT, with 16.38 ± 8.08-31.88 ± 12.09 items/individual. No mesoplastics were found in muscle tissue, but they were present in the GIT at concentrations ranging from 0.33 ± 0.27 to 0.03 ± 0.02 items/g and from 0.51 ± 0.05to 1.38 ± 1.01 items/individual. Lepturacanthus savala accumulated the most microplastics in muscle, and Harpadon nehereus had the least. In addition, the highest levels of mesoplastics were detected in the GIT of Polynemus paradiseus and the lowest was detected in the GIT of Lutjenus sanguineus. Omnivorous fish showed higher plastic concentrations than carnivorous fish, which was linked to dietary habits, feeding strategies and digestive processes. Plastic material predominantly accumulated in the GIT rather than in the muscle. The majority of ingested plastic particles were fibres (95.18 %), were violet in color (34 %), and were < 0.5 mm in size (87 %). The dominant microplastic polymers included 38 % PE, 15 % PP, 33 % PU, and 14 % CES. In contrast, the prevalent mesoplastic polymers comprised 45 % PE, 19 % PP, 13 % PS, 16 % PA, and 7 % PET. Subsequently, a hazard analysis using the polymer hazard index (PHI) revealed that plastic contamination was of distinct hazard categories for different polymer types, ranging from grade I (<1) to grade IV (100-1000). The assessment of the contamination factor (1 < CF < 3) and pollution load index (PLI > 1) indicated moderate contamination of fish by the ingestion of plastic debris. This study provides the foremost evidence for the presence of mesoplastics and microplastics in coastal and marine fish in the study region, paving the way for future investigations and policy implementation.

Heavy metals in afforested mangrove sediment from the world's largest delta: Distributional mapping, contamination status, risk assessment and source tracing.

This study aims to assess seasonal and spatial variations, contamination status, ecological risks, and metal sources (Ni, Pb, Cr, Cu, Mn, and Zn) in human-afforested mangrove sediments in a deltaic region. Five sampling locations were sampled during dry and wet seasons. Heavy metal concentrations followed the order: Mn > Zn > Ni > Cr > Cu > Pb. Metal loads, except Cu and Pb, were higher during the dry season, aligning with national and international recommendations. Sediment quality guidelines, contamination factor, geoaccumulation index, enrichment factors, and pollution load index indicated uncontaminated sediment in both seasons. Potential ecological risk assessment showed low risk conditions in all sites. However, modified hazard quotient indicated moderate pollution risk from all metals except Pb. Analysis suggests anthropogenic sources, particularly evident near shipbreaking yards in Sitakunda. While initially uncontaminated, ongoing metal influx poses a potential risk to mangrove ecosystems.

The contribution of homestead pond fish culture to household food security and dietary diversity in central coast of a developing country.

Fish farming in homestead ponds help alleviate poverty, provide animal source food, micronutrients, and indirect income and various jobs in developing nations. This study investigated the impact of homestead pond fish farming on dietary diversity (HDDS and MDD-W), food security (HFIAS and ELCSA), income, and women's engagement. A total of 185 households were selected randomly for data collection through well-structured questionnaire interviews in the central coast of Bangladesh. HDDS revealed significant dietary diversity (73.3%) among beneficiary farmers, surpassing controls and nearly doubling that of non-aquaculture farmers (41.1%). Additionally, this study found that 86.7% and 74.3% of women in beneficiary and homestead pond farmers exhibited high dietary diversity (MDD-W ≥ 5), whereas 48.6% of women in non-aquaculture farmers' households had low dietary diversity (MDD-W ≥ 5). Based on both ELCSA and HFIAS, higher prevalence of food security was observed among the beneficiary farmers that was about 60% and 63.3%, respectively compared with the control farmers. Most non-aquaculture farmers (62.9%) indicated their family consumed fish for one week before the research. More than half of the homestead pond culture (55.7%) and more than 90% of the beneficiary farmers, aquaculture farmers and non-aquaculture farmers had gross income (<$ 500). Pertaining to women's participation in homestead pond was positively correlated to productivity while male dominated tasks was negatively correlated with productivity. The results offer insights into how homestead pond fish farming can enhance food security by supplying direct animal protein, addressing protein and micronutrient deficiencies, and boosting income. The study emphasizes the urgent necessity for training and promoting homestead pond culture, increasing female participation, and advocating comprehensive support from governmental organizations (GOs) and non-governmental organizations (NGOs) to optimize production, improve micronutrient adequacy, and guarantee household food security. Keywords: Fish farming, food security, dietary diversity, women's participation.

Minerals and fatty acid profile of small indigenous fish species from homestead ponds within a Sub-tropical coastal region.

Malnutrition has emerged as a noticeable obstruction to the socio-economic advancement of rural areas along the coastal regions of Bangladesh. Small indigenous fish species (SIS) have the potential to alleviate the malnutrition issue because of having higher nutritional compositions. However, prior research has overlooked the detailed nutritional value of SIS originating from coastal regions. Consequently, the current investigation sought to analyze the mineral and fatty acid composition of twelve SIS obtained from coastal homestead ponds. The findings indicated that the mineral composition in SIS exhibited the following descending order: calcium (Ca) > phosphorus (P) > potassium (K) > magnesium (Mg) > iron (Fe) > zinc (Zn). Furthermore, when considering the overall mineral content in SIS, it ranked in the following decreasing order: A. testudineus, M. tengara, C. punctatus, N. nandus, P. sophore, C. fasciatus, A. mola, C. batrachus, H. fossilis, P. sarana, M. aculeatus, and O. pabda. The analysis of the fatty acid profile further revealed that SIS is a rich source of palmitic acid, linoleic acid, oleic acid, stearic acid, myristic acid, palmitoleic acid, and linolenic acid. The saturated fatty acid content of the SIS varied between 42.66 % and 63.37 %, and the highest content was found in A. mola whereas the lowest was in A. testudineus. On the other hand, the total monounsaturated fatty acid content of the SIS ranged from 26.49 % (A. mola) to 46.12 % (P. sarana), and the total PUFAs contents among the fish species ranged from 5.7 % (A. mola) to 16.54 % (H. fossilis). Therefore, SIS could be a key source of minerals and essential fatty acids for human well-being. This can help fulfill nutrient requirements and reduce malnutrition among coastal populations. It can be said that, if these fishes are introduced in the culture systems, it will be used for consumption as well as support the livelihood of coastal people.

Quantification, characterization and risk assessment of microplastics from five major estuaries along the northern Bay of Bengal coast.

Microplastics (MPs) as hazardous contaminants has drawn the rapid attention of the general public due to their omnipresence and adverse impacts on ecosystems and human health. Despite this, understanding of MPs contamination levels in the estuarine ecosystems along the Bay of Bengal coast remains very limited. This research focused on the presence, spatial distribution, morpho-chemical characteristics and ecological implications of MPs in water and sediment from five key estuaries (Meghna, Karnaphuli, Matamuhuri, Bakkhali, and Naf rivers) within the Bengal delta. Out of the five estuaries, the Meghna exhibited the least amount of MPs in both surface water (150.00 ± 65.62 items/m3) and sediment (30.56 ± 9.34 items/kg). In contrast, the highest occurrence of MPs was recorded in Karnaphuli river water (350.00 ± 69.22 items/m3) and Matamuhuri river sediment (118.33 ± 26.81 items/kg). ANOVA indicated a statistically significant distinction (p < 0.01) among the examined estuaries. Most identified MPs were fibers and < 0.5 mm in size in both water and sediment samples. Transparent MPs were dominant in both water (42.28%) and sediment (45.22%). Besides violet, red, blue, pink and green colored MPs were also observed. Various polymer types, including PE, PP, PET, PS, Nylon, EVA, and ABS, were detected, with PE being the dominant one. Based on the polymer risk index (PHI), the estuaries were classified as hazard level V, signifying a severe level of MP contamination. However, the potential ecological hazardous index (PHI), potential ecological risk index (RI), and pollution load index (PLI) indicated moderate pollution levels. This study offers initial insights into the pollution caused by MPs in major estuaries of Bengal delta, which policymakers can utilize to implement suitable management strategies.

Trace metals in transboundary (India-Myanmar-Bangladesh) anadromous fish Tenualosa ilisha and its consequences on human health.

Hilsa shad (Tenualosa ilisha, Hamilton, 1822), the highly coveted table fish within the Indian subcontinent, is Bangladesh's most significant single-species fishery. To assess the risk that toxic metals pose to human health, certain health risk indices-estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ), and target cancer risk (TR)-were calculated. The hierarchy of toxic metals (µg/g-ww) in Hilsa shad of the bay showed as Zn (13.64 ± 2.18) > Fe (9.25 ± 1.47) > Mn (2.98 ± 0.75) > Cu (0.57 ± 0.18) > Cr (0.23 ± 0.06) > Pb (0.22 ± 0.04) > As (0.08 ± 0.02) > Ni (0.06 ± 0.02) > Co (0.04 ± 0.01) > Cd (0.01 ± 0.003) in the wet season and Zn (11.45 ± 1.97) > Fe (10.51 ± 1.38) > Mn (3.80 ± 0.75) > Cu (0.73 ± 0.17) > Pb (0.30 ± 0.03) > Cr (0.20 ± 0.05) > As (0.09 ± 0.01) > Ni (0.08 ± 0.02) > Co (0.07 ± 0.02) > Cd (0.02 ± 0.004) in the dry season. The EDI of all the examined trace metals indicated no risk to human health from consuming Hilsa fish. The estimation of THQ and TTHQ suggested that the ingestion of both individual and combined trace metals through Hilsa shad consumption was safe from the perspective of human health. Also, there was no evidence of carcinogenic risk for consumers based on the evaluation of the TR value of metals (As, Pb, Cd, and Ni) due to Hilsa shad consumption.

Heavy metals in wild and cultured shrimp, supplied feeds, and their habitats: Assessing public health risk.

The contamination and risk assessment of heavy metals (HMs) in highly priced tiger shrimp and its associated ecosystems and farming conditions (hatcheries and commercial grow-out ponds) were scarcely investigated in South Asian countries. In this study, we determined the five HMs (Cu, Zn, Pb, Cd, and Cr) concentrations in PL14 (fourteen days of Post-Larva) of Penaeus monodon, commercial diets, surface water, and sediments from hatcheries, farms, rivers using ICP-MS for two years. The results revealed that surface sediments of rivers and hatcheries had the highest amounts of Cr (65.85 ± 0.82 and 72.50 ± 0.42 mg/kg), Cu (18.82 ± 3.96 and 19.26 ± 4.61 mg/kg), and Zn (63.74 ± 11.14 and 87.42 ± 17.96 mg/kg), whereas commercial farms had the greatest levels of Cd (0.09 ± 0.05 mg/kg). Pb was significantly higher in sediment of hatcheries and farms than in other sites. Except for Zn in surface waters, all metals were found above the recommended limit. In case of supplied feed, all values were in the safe limit excepting Cr (3.39 ± 1.45 to 108.92 ± 3.49 mg/kg). On the other hand, among the metals, only Cr (VI) ranging from 1.75 ± 1.39 mg/kg in P. monodon samples exceeded the suggested international guidelines. The Igeo values of all the metals were Igeo <0, indicating that the study areas were practically unpolluted. PLI values in every station were found to be below 1 which indicates the perfection of the sediment. The Potential Risk Index (PERI) values were less than 150 suggesting low risk of metals in sediments. The public health risk assessment estimated through the calculated daily intake (EDI), target hazard quotient (THQ) and hazard index (HI) has shown that the shrimp was safe for consumers except for Cd and Cr. The THQ for Cd and Cr were higher than the threshold (>1) indicating potential health hazards. The low CR values for Cd, Cr Pb were 3.1 × 10-4, 3.7 × 10-4 and 1.6 × 10-4, respectively indicates no cancer risks upon consuming P. monodon.

Distribution, characterization and contamination risk assessment of microplastics in the sediment from the world's top sediment-laden estuary.

Microplastics (MPs) have gained a serious attention as an emerging contaminant throughout the world because of their persistence and possible risks to aquatic ecosystems and human well-being. However, knowledge on MPs contamination from sub-tropical coastal systems is limited, and no study has been conducted on the MPs contamination in sediment from one of the highest sediment-laden estuaries, Meghna River, in the world. This is the first study to examine the quantity, morpho-chemical characteristics and contamination risk level of MPs from this large scale river. MPs were extracted from the sediment samples of 10 stations along the banks of the estuary by density separation, and then characterized using a stereomicroscope and Fourier Transform Infrared (FTIR) spectroscopy. The incidence of MPs varied from 12.5 to 55 item/kg dry sediment with an average of 28.67 ± 10.80 item/kg. The majority (78.5%) of the MPs were under 0.5 mm in size, with fibers being the most (74.1%) prevalent MPs type. Polypropylene (PP) was found to be the predominant polymer (53.4%), followed by polyethylene (PE, 20%), polystyrene (PS, 13.3%), and polyvinyl chloride (PVC, 13.3%). The highest occurrence of PP indicted the MPs in the estuary might be originated from clothing and dying industries, fishing nets, food packages, and pulp industries. The sampling stations were contaminated with MPs as shown by the contamination factor (CF) values and pollutant load index (PLI), both of which were >1. This study exposed new insights on the status of MPs in the sediments of the Meghna River, laying the groundwork for future research. The findings will contribute to estimate the global share of MPs to the marine environment.

Microplastics in aquatic environments: A comprehensive review of toxicity, removal, and remediation strategies.

The occurrence of microplastics (MPs) in aquatic environments has been a global concern because they are toxic and persistent and may serve as a vector for many legacies and emerging pollutants. MPs are discharged to aquatic environments from different sources, especially from wastewater plants (WWPs), causing severe impacts on aquatic organisms. This study mainly aims to review the Toxicity of MPs along with plastic additives in aquatic organisms at various trophic compartments and available remediation methods/strategies for MPs in aquatic environments. Occurrences of oxidative stress, neurotoxicity, and alterations in enzyme activity, growth, and feeding performance were identical in fish due to MPs toxicity. On the other hand, growth inhibition and ROS formation were observed in most of the microalgae species. In zooplankton, potential impacts were acceleration of premature molting, growth retardation, mortality increase, feeding behaviour, lipid accumulation, and decreased reproduction activity. MPs togather with additive contaminants could also exert some toxicological impacts on polychaete, including neurotoxicity, destabilization of the cytoskeleton, reduced feeding rate, growth, survivability and burrowing ability, weight loss, and high rate of mRNA transcription. Among different chemical and biological treatments for MPs, high removal rates have been reported for coagulation and filtration (>86.5 %), electrocoagulation (>90 %), advanced oxidation process (AOPs) (30 % to 95 %), primary sedimentation/Grit chamber (16.5 % to 58.84 %), adsorption removal technique (>95 %), magnetic filtration (78 % to 93 %), oil film extraction (>95 %), and density separation (95 % to 100 %). However, desirable extraction methods are required for large-scale research in MPs removal from aquatic environments.

Microplastics in surface water from a mighty subtropical estuary: First observations on occurrence, characterization, and contamination assessment.

Estuarine contamination by Microplastics (MPs) is a mater of serious concern since these areas offer the society valuable ecosystem, economic, and recreational services such as breeding and feeding ground for fish, carbon fixation, nutrients recycling and port development. The Meghna estuary, located along the Bengal delta coast, provides livelihoods for thousands of peoples in Bangladesh, and served as breeding ground for national fish, Hilsha shad. Therefore, knowledge and understanding on any kind of pollution including MPs of this estuary is essential. In this study, the abundance, characteristics and contamination assessment of MPs from the surface water of a Meghna estuary were investigated for the first time. The results demonstrated that MPs were present in all samples and the abundance ranged from 33.33 to 316.67 item/m3 with a mean value of 128.89 ± 67.94 item/m3. Morphological analyses resulted in four types of MPs such as fibers (87%), fragments (6%), foam (4%), and films (3%) with the majority of these being colored (62%) and smaller (<0.5 mm) in size (88%). On the other hand, FTIR analysis for chemical characteristics confirmed five types of polymers, including polythene (PE), polystyrene (PS), polythene terephthalate (PET), polypropylene (PP), and polyvinyl chloride (PVC). The area was determined to be moderately to severely contaminated with MPs based on contamination factor (CF) values (6.18 ± 2.08 to 2.50 ± 1.0) and the pollutant load index (PLI) value (1.94 ± 0.33) as these values were > 3-6 for CF, and >1 for PLI. These results can be utilized to develop policy for the protection of this important environment.

Vertical distribution, contamination status and ecological risk assessment of heavy metals in core sediments from a mangrove-dominated tropical river.

Understanding the vertical distribution of heavy metals aids in tracing the contamination history, however, it is limited for mangrove-dominated river. Thus, this study aimed to assess the vertical distribution of nine heavy metals and their possible ecological risk in several layers of core sediments from a mangrove-dominated river inside the Sundarban mangrove forest (World heritage and Ramsar site), Bangladesh. 45 core samples from five stations were analyzed using Flame Atomic Absorption Spectrophotometer (FAAS). The findings showed that, with the exception of Fe, Ni, and Cu, which suggested increased metal release in recent times, higher metal levels were recorded in the surface layer (0-10 cm), followed by the middle layer (10-20 cm), and inner layer (20-30 cm) of sediment cores. When compared to non-industrial forest sediment, core sediment from industrial sites contained noticeably more metals (p < 0.05). Overall, the mean metal concentration (mg/kg) followed the increasing order of Cd < As < Pb < Cu < Cr < Zn < Ni < Mn < Fe. Among the studied metals, the levels of Cd and Ni exceeded the average shale value. Contamination indices such as enrichment factor (EF), contamination factor (CF), and geo-accumulation index (Igeo) showed that the studied sediments were only contaminated by Cd. Ecological risk assessed by ecological risk factor (Eri) and risk index (RI) suggested that the analyzed heavy metals, with the exception of Cd, posed no significant ecological threats. All of the heavy metals analyzed might have originated from similar anthropogenic sources, according to the correlation matrix, cluster analysis (CA), and principal component analysis (PCA).

Contamination status and associated ecological risk assessment of heavy metals in different wetland sediments from an urbanized estuarine ecosystem.

Sediment samples of different wetland types (saltmarsh, mangrove, tidal pool, mudflat and sandflat) from an urbanized estuary were analyzed to evaluate the contamination level and ecological risks of five heavy metals (Pb, Fe, Zn, Ni and Cr). The findings showed that the mean concentration (mg/kg) of heavy metals followed the order of Fe > Zn > Ni > Pb > Cr, while Pb and Fe concentrations exceeded the recommended guidelines. Heavy metals levels were highest in saltmarsh and mudflats. Contamination assessment indices e.g., contamination factor (CF), degree of contamination (CD), enrichment factor (EF), and geo-accumulation index (Igeo) revealed that the studied wetlands had low to moderate levels of pollution, meaning these sites receive medium levels of anthropogenic contamination compared with background values. For some of the studied metals, such as Pb, Zn, Fe, and Ni, the EF value was >1 in certain types of wetland, indicating anthropogenic sources, while Cr was <1 indicating natural sources. The pollution load index (PLI) value was determined to be <1, indicating perfection of soil, and was in the following order: mudflat> saltmarsh> tidal pool> mangrove > sandflat. The ecological risk (RI) value was the highest for saltmarsh and the lowest for sandflats. However, the RI value for Cr, Zn, Ni, and Pb was <30 suggesting that these metals pose a low risk in the local ecosystem. Cluster analysis (CA), principal component analysis (PCA), and Pearson's correlation specified that anthropogenic sources of metals.

Microplastic contamination in processed and unprocessed sea salts from a developing country and potential risk assessment.

In aquatic environments, microplastics (MPs) are pervasive which could have a considerable negative impact on the environment, organisms and pose a risk to human health. However, knowledge about the exposure and ecological risk of MPs in the coastal ecosystems of developing countries is limited. In this study, we analyzed salt samples from five commonly consumed processed and unprocessed sea salts of different commercial brands originated from 15 salt pans in Bangladesh to assess the abundance, characteristics and potential risks of MPs. The quantities of MPs in unprocessed salts (average 195 ± 56 item/kg) were higher than those in the processed salts (average 157 ± 34 item/kg). One-way analysis of variance (ANOVA) showed significant (p < 0.05) differences among the average numbers of MPs in both processed and unprocessed salts. MP levels in this study were 2-3 times higher than those reported from some other countries. Fiber-shaped and transparent MPs were dominant in both cases. MPs less than 0.5 mm in size were the most abundant in both unprocessed (58.2%) and processed (62.2%) salts. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed five types of polymers, including polyethylene terephthalate (PET-35%), polypropylene (PP-27.5%), polyethylene (PE-25%), polystyrene (PS-10%), and Nylon (2.5%) in the studied salts. The sea salts were classified as potential hazard index (PHI) levels IV to V, indicating serious MP contamination, whereas potential ecological risk factor (Ei), potential ecological risk index (RI), and pollutant load index (PLI) indicated moderate levels of pollution of MPs. Domestic and municipal wastewater effluents to Bay of Bengal and fishing activities may attributed to presence of MPs in the sea salt. These findings can be used by consumers, salt industries and policy makers to reduce MPs levels during consumption, production and policymaking.

A comprehensive review of heavy metal pollution in the coastal areas of Bangladesh: abundance, bioaccumulation, health implications, and challenges.

The coastal zone of Bangladesh, with a population density of 1278 people per square kilometer, is under serious threat due to heavy metal pollution. To date, many studies have been conducted on the heavy metal contamination in soils, water, aquatic animals, and plants in the coastal zone of Bangladesh; however, the available information is dispersed. In this study, previous findings on the contamination levels, distributions, risks, and sources of heavy metals in sediments and organisms were summarized for the first time to present the overall status of heavy metal pollution along coastal regions. Earlier research found that the concentrations of various heavy metals (HMs), particularly Co, Cd, Pb, Cu, Cr, Mn, Fe, and Ni in water, sediment, and fish in most coastal locations, were above their permissible limits. High concentrations of HMs were observed in sediments and water, like Cr of 55 mg/kg and 86.93 mg/l in the ship-breaking areas and Karnaphuli River, respectively, in coastal regions of Bangladesh. Heavy metals severely contaminated the Karnaphuli River estuary and ship-breaking area on the Sitakundu coast, where sediments were the ultimate sink of high concentrations of metals. Sedentary or bottom-dwelling organisms like gastropods and shrimp had higher levels of heavy metals than other organisms. As a result, the modified PRISMA review method was used to look at the critical research gap about heavy metal pollution in Bangladesh's coastal areas by analyzing the current research trends and bottlenecks.

Heavy Metal Accumulation and Phytoremediation Potentiality of Some Selected Mangrove Species from the World's Largest Mangrove Forest.

Toxic metal pollution is a global issue, and the use of metal-accumulating plants to clean contaminated ecosystems is one of the most rapidly growing ecologically beneficial and cost-effective technologies. In this study, samples of sediment and three mangrove species (Excoecaria agallocha, Avicennia officinalis, Sonneratia apetala) were collected from the world's largest mangrove forest (along the Northern Bay of Bengal Coast) with the aim of evaluating metal concentrations, contamination degrees, and phytoremediation potentiality of those plants. Overall, the heavy metals concentration in sediment ranged from Cu: 72.41−95.89 mg/kg; Zn: 51.28−71.20 mg/kg; Fe: 22,760−27,470 mg/kg; Mn: 80.37−116.37 mg/kg; Sr: 167.92−221.44 mg/kg. In mangrove plants, the mean concentrations were in the order of E. agallocha > A. officinalis > S. apetala. The mean (± SD) concentration of each metal in the plant tissue (root) was found following the descending order of Fe (737.37 ± 153.06) > Mn (151.13 ± 34.26) > Sr (20.98 ± 6.97) > Cu (16.12 ± 4.34) > Zn (11.3 ± 2.39) mg/kg, whereas, in the leaf part, the mean concentration (mg/kg) of each metal found in the order of Fe (598.75 ± 410.65) > Mn (297.27 ± 148.11) > Sr (21.40 ± 8.71) > Cu (14.25 ± 2.51) > Zn (12.56 ± 2.13). The contamination factor (CF) values for the studied metals were in the descending order of Cu > Sr > Zn > Fe > Mn. The values of Igeo (Geo-accumulation index) and CF showed that the area was unpolluted to moderately polluted by Zn, Fe, Mn, Cu and Sr. Enrichment factor (EF) values in both sampling stations portrayed moderate to minimum enrichment. Phytoremediation potentiality of the species was assessed by bio-concentration factor (BCF) and translocation factor (TF). BCF values showed less accumulation for most of the heavy metals (<1) except Mn which was highly accumulated in all mangrove plants. The translocation factor (TF) values depicted that most of the heavy metals were strongly accumulated in plant tissues (>1). However, the BCF value depicts that Mn was highly bioconcentrated in E. agallocha, but the translocation on leaves tissue were minimum, which reveals that E. agallocha is phytoextractor for Mn, and accumulated in root tissues. All the examined plants can be used as phytoextractors as they have bioconcentration factors <1 and translocation factors >1. However, A. officinalis is clearly more suitable for metal extraction than S. apetala and E. agallocha in terms of hyper-metabolizing capabilities.

Spatial distribution and risk assessments due to the microplastics pollution in sediments of Karnaphuli River Estuary, Bangladesh.

Microplastics (MPs) have become an emerging global pollutant due to their widespread dispersion and potential threats to marine ecosystems. However, studies on MPs in estuarine and coastal ecosystems of Bangladesh are very limited. Here, we conducted the first study on abundance, distribution, characteristics, and risk assessment of microplastics in the sediment of Karnaphuli River estuary, Bangladesh. Microplastic particles were extracted from sediments of 30 stations along the estuary by density separation and then enumerated and characterized using a stereomicroscope and Fourier Transform Infrared (FT-IR) spectroscopy. In the collected sediment of the Karnaphuli River estuary, the number of MPs varied from 22.29 to 59.5 items kg-1 of dry weight. The mean abundance was higher in the downstream and left banks of the estuary, whereas the predominant shape, colour, and size of MPs were films (35%), and white (19%), and 1-5 mm (30.38%), respectively. Major polymer types were polyethylene terephthalate, polystyrene, polyethylene, cellulose, and nylon. MPs were found to pose risks (low to high) in the sediment of the estuary, with the highest risk occurring at one station near a sewage outlet, according to the results of risk analyses using the pollution risk index, polymer risk index (H), contamination factors, and pollution load index (PLI). The single value index, PLI, clearly demonstrated that all sampling sites were considerably polluted with microplastics (PLI > 1). H values showed toxic polymers, even in lower proportions, possess higher polymeric hazard scores and vice versa. This investigation uncovered new insights on the status of MPs in the sediments of the Karnaphuli River estuary, laying the groundwork for future research and control of microplastic pollution and management.

Bioaccumulation and potential human health risks of metals in commercially important fishes and shellfishes from Hangzhou Bay, China.

Hangzhou Bay is facing severe anthropogenic perturbation because of its geographic position. We studied species-specific bioaccumulation of metals in commercially important fishes and shellfishes, and calculated the potential human health hazards through their consumption, which has not been reported earlier from this area. The hierarchy of metal concentration in organisms was in the decreasing order of Zn (10.32 ± 7.13) > Cu (2.40 ± 2.66) > As (0.42 ± 0.26) > Cr (0.11 ± 0.08) > Cd (0.07 ± 0.07) > Pb (0.05 ± 0.02) > Hg (0.012 ± 0.009). Except for Cd and As concentrations in fishes, metal concentrations have not exceeded the national and international guideline values. P. laevis and P. trituberculatus were the most bioaccumulative of the species studied. According to the non-carcinogenic risk assessment, children were more susceptible to metal contamination than adults. The carcinogenic risk (CR) values indicated that children were likely to experience carcinogenic threats for taking cancer-causing agents As and Cd through fish consumption. In terms of organisms, intake of two crab species, P. trituberculatus and E. sinensis, as well as the oyster species P. laevis, could be detrimental to consumers.

Ecological risk evaluation in bottom-surface sediments and sub-surface water in the subtropical Meghna estuarine system.

Assessment of elemental contamination is emerging research in the present world. Metals are hazardous to the environment and people's health when metals concentration might exceed the tolerable level. In this research, 12 elements (i.e., Mn, Ni, Cu, Zn, As, Se, Sr, Co, Pb, Fe, Rb, and Ti) were assessed using the energy dispersive X-ray fluorescence (EDXRF) method in water and sediment samples in four (4) different spawning grounds of Tenualosha ilisha at the confluence of the Meghna River in Bangladesh. A comparative analysis was performed for the first time among four sampling spots, i.e., Chandpur, Bhola, Sandwip, and Hatiya, assessed all possible risk indices-it is a unique thing. Several risk indices were solved to determine the degree of sediment pollution for all 12 elements, e.g., degree of contamination (Cd):6.5-7.01, the modified degree of contamination (mCd): approximately 0.7, the pollution load index (PLI): 0.45-0.51, etc. where all the indices' results showed low or baseline levels of pollution. According to the enrichment factor (EF) computation, slight enrichment of examined metals except Pb and Zn was found. In addition to these, the ecological risk factor (Er) found in the following order (pollution level: low): Cu > Pb > Zn among the four stations. Moreover, a spatial incline of metal accumulation was observed among the four spots: Bhola < Sandwip < Hatiya < Chandpur based on the risk index (RI) set value. However, a strong positive correlation (p < 0.05) between Ca and Fe, Ti and Fe, Ti and Mn, Mn and Fe, Fe and Sr were observed while Ca, and Co were strongly negatively correlated (r = minus (-)0.60, p < 0.05). The cluster analysis was performed and got an asymmetrical cluster among the sampling stations. This study recommends assessing the heavy metal concentration in biological samples, particularly in Hilsha fish.