Heavy metal concentration in reef-associated surface sediments, Hare Island, Gulf of Mannar Marine Biosphere Reserve (southeast coast of India): The first report on pollution load and biological hazard assessment using geochemical normalization factors and hazard indices

Singapore's urbanised coral reefs: Changes in heavy metal pollution between 1994 and 2021

The heavy metal load in coral reefs of Singapore has not been comprehensively assessed since 1994. Here, we repeated the surveys conducted 27 years ago to quantify the levels of Cd, Cu, Cr, Fe, Pb, Ti, Zn in sediment and the sea urchin Diadema setosum from seven reefs. Cu and Cd showed significant reductions, Pb and Cr remained stable, while Fe, Ti and Zn had increased significantly. Overall, based on the Pollution Load Index (PLI), Singapore's reefs would not be considered polluted. Nevertheless, elevated concentrations of Cu, Pb and Zn were detected in sediment, with Cu and Pb exceeding the Threshold Effect Level. The spatial distribution of metal loads between sediment and sea urchin tissues were decoupled, underscoring the complexity of metal uptake and bioavailability. We reveal a mixed temporal trend among the heavy metals examined, each presenting different toxicity potentials and hence risks to local marine assemblages.

Bioaccumulation and health risk assessment of trace elements in Tilapia (Oreochromis mossambicus) from selected inland water bodies

The presence of toxic trace elements (TEs) has resulted in a worldwide deterioration in freshwater ecosystem quality. This study aimed to analyze the distribution of TEs, including chromium (Cr), nickel (Ni), arsenic (As), mercury (Hg), cadmium (Cd), and lead (Pb), in water, sediment, and organs of Tilapia (Oreochromis mossambicus) collected from selected inland water bodies in Tamil Nadu, India. The water samples exhibited a range of concentrations for TEs: Cr varied from 0.014 to 5.193 µg/L, Ni ranged from 0.283 to 11.133 µg/L, As ranged from 0.503 to 1.519 µg/L, Cd from 0.001 to 0.616 µg/L, and Pb ranged from non-detectable (ND) to 6.103 µg/L. The concentrations of TEs in sediment were found to vary within the following ranges: 5.259 to 32.621 mg/kg for Cr, 1.932 to 30.487 mg/kg for Ni, 0.129 to 0.563 mg/kg for As, 0.003 to 0.011 mg/kg for Cd, ND to 0.003 mg/kg for Hg, and 0.404 to 1.575 mg/kg for Pb. The study found that the accumulation pattern of TE in fishes across all selected areas was liver > bone > gill > muscle. The organs had TE concentrations of Cr (ND-0.769 mg/kg), Ni (ND-1.053 mg/kg), As (0.002-0.080 mg/kg), Pb (ND-0.411 mg/kg), and Hg (ND-0.067 mg/kg), which was below the maximum residual limit prescribed by EC and FSSAI. The bioconcentration factor (BCF) of TEs exhibited a greater magnitude in comparison with the biota-sediment accumulation factor due to the higher concentration of TEs in fish and lower level in water. The assessment of both carcinogenic and non-carcinogenic risks suggests that the consumption of Tilapia from the study region does not pose any significant risks.

Biomonitoring of mercury and selenium in commercially important shellfish: Distribution pattern, health benefit assessment and consumption advisories

This study aims to explore the concentrations of Se and Hg in shellfish along the Gulf of Mannar (GoM) coast (Southeast India) and to estimate related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in shrimp, crab, and cephalopods ranged from 0.256 to 0.275 mg kg-1, 0.182 to 0.553 mg kg-1, and 0.176 to 0.255 mg kg-1, respectively, whereas Hg concentrations differed from 0.009 to 0.014 mg kg-1, 0.022 to 0.042 mg kg-1 and 0.011 to 0.024 mg kg-1, respectively. Se and Hg content in bamboo shark (C. griseum) was 0.242 mg kg-1 and 0.082 mg kg-1, respectively. The lowest and highest Se concentrations were found in C. indicus (0.176 mg kg-1) and C. natator (0.553 mg kg-1), while Hg was found high in C. griseum (0.082 mg kg-1) and low in P. vannamei (0.009 mg kg-1). Se shellfishes were found in the following order: crabs > shrimp > shark > cephalopods, while that of Hg were shark > crabs > cephalopods > shrimp. Se in shellfish was negatively correlated with trophic level (TL) and size (length and weight), whereas Hg was positively correlated with TL and size. Hg concentrations in shellfish were below the maximum residual limits (MRL) of 0.5 mg kg-1 for crustaceans and cephalopods set by FSSAI, 0.5 mg kg-1 for crustaceans and 1.0 mg kg-1 for cephalopods and sharks prescribed by the European Commission (EC/1881/2006). Se risk-benefit analysis, the AI (actual intake):RDI (recommended daily intake) ratio was > 100%, and the AI:UL (upper limit) ratio was < 100%, indicating that all shellfish have sufficient level of Se to meet daily requirements without exceeding the upper limit (UL). The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of shellfish has no non-carcinogenic health impacts for all age groups. However, despite variations among the examined shellfish, it was consistently observed that they all exhibited a Se:Hg molar ratio > 1. This finding implies that the consumption of shellfish is generally safe in terms of Hg content. The health benefit indexes, Se-HBV and HBVse, consistently showed high positive values across all shellfish, further supporting the protective influence of Se against Hg toxicity and reinforcing the overall safety of shellfish consumption. Enhancing comprehension of food safety analysis, it is crucial to recognize that the elevated Se:Hg ratio in shellfish may be attributed to regular selenoprotein synthesis and the mitigation of Hg toxicity by substituting Se bound to Hg.

Selenium and mercury concentration, Se/Hg molar ratio and risk-benefit assessment of marine fish consumption: Human health risks and protective role of Se against Hg toxicity

This study aimed to explore the concentrations of Se and Hg in marine fish along the Gulf of Mannar (southeast coast of India) and to assess related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in pelagic and benthic fish ranged from 0.278 to 0.470 mg/kg and 0.203 to 0.294 mg/kg, respectively, whereas Hg concentrations ranged from 0.028 to 0.106 mg/kg and 0.026 to 0.097 mg/kg, respectively. Se and Hg contents in demersal fish (Nemipterus japonicus) were 0.282 and 0.039 mg/kg, respectively. The lowest and highest Hg concentrations in pelagic fish were found in Scomberomorus commersoni and Euthynnus affinis whereas the lowest and highest Se concentrations in benthic fish were found in Scarus ghobban and Siganus javus. Se concentrations in marine fishes were found in the following order: pelagic > demersal > benthic whereas Hg concentrations were found in the following order: pelagic > benthic > demersal. The presence of Se in fish was positively correlated with trophic level (TL) and size whereas that of Hg was weakly correlated with TL and habitat and negatively correlated with size. Se risk-benefit analysis, the AI/RDI (actual intake/recommended daily intake) ratio was > 100 % and the AI/UL (upper limit) ratio was < 100 %, indicating that all fish have sufficient levels of Se to meet daily requirements without exceeding the UL. Hg level was below the maximum residual limit (MRL) of 0.5 mg/kg for most fish but it was 1 mg/kg in E. affinis and Lethrinus lentjan. The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of fish poses no noncarcinogenic health risks. However, all examined fish had a mean Se/Hg molar ratio > 1, indicating that human intake of fishwas rather safe relative to Hg content. Health benefit indexes (Se-HBV and HBVse) with high positive values in all fish supported the protective effect of Se against Hg toxicity, suggesting the overall safety of fish consumption. The high Se/Hg ratio in fish could be attributed to the replacement of Se bound to Hg, thereby suppressing Hg toxicity and maintaining normal selenoprotein synthesis. This insight is useful for a better understanding of food safety analysis.

Influence of global warming and industrialization on coral reefs: A 600-year record of elemental changes in the Eastern Red Sea

The Red Sea has been recognized as a coral reef refugia, but it is vulnerable to warming and pollution. Here we investigated the spatial and temporal trends of 15 element concentrations in 9 coral reef sediment cores (aged from the 1460s to the 1980s AD) to study the influence of global warming and industrialization on the Eastern Red Sea coral reefs. We found Na, Ca, Cr, Fe, Co, Ni, and Sr concentrations were higher in the northern Red Sea (i.e., Yanbu), whereas Mg, P, S, Mn, and Cd concentrations were higher in the southern Red Sea (i.e., Thuwal & Al Lith) reef sediments. In the central (i.e., Thuwal) to southern (i.e., Al Lith) Red Sea, the study revealed diverse temporal trends in element concentrations. However, both reef sedimentation rates (-36.4 % and -80.5 %, respectively) and elemental accumulation rates (-49.4 % for Cd to -12.2 % for Zn in Thuwal, and -86.2 % for Co to -61.4 % for Cu in Al Lith) exhibited a declining pattern over time, possibly attributed to warming-induced thermal bleaching. In the central to northern Red Sea (i.e., Yanbu), the severity of thermal bleaching is low, while the reef sedimentation rates (187 %), element concentrations (6.7 % for S to 764 % for Co; except Na, Mg, Ca, Sr, and Cd), and all elemental accumulation rates (190 % for Mg to 2697 % for Co) exponentially increased from the 1970s, probably due the rapid industrialization in Yanbu. Our study also observed increased trace metal concentrations (e.g., Cu, Zn, and Ni) in the Thuwal and Al Lith coral reefs with severe bleaching histories, consistent with previous reports that trace metals might result in decreased resistance of corals to thermal stress under warming scenarios. Our study points to the urgent need to reduce the local discharge of trace metal pollutants to protect this biodiversity hotspot.

Trace metals in commercial seafood products (canned, pickled and smoked): Comparison, exposure and health risk assessment

This study used inductively coupled plasma and mass spectrometry, followed by microwave digestion, to assess the concentration of six trace metals (Cr, Ni, As, Cd, Hg, and Pb) in three canned products (tuna in oil [TIO], sardine in oil [SIO], and mackerel in oil [MIO]), two pickled products (prawn pickle [PP] and fish pickle [FP]), and one smoked product (masmin) collected from Tuticorin market, southern India. Trace metal (TM) levels in canned, pickled, and smoked fish varied from 0.01 to 1.48, 0.009 to 0.94, and 0.08 to 4.13 mg/kg, respectively. The concentration of TMs in the seafood was observed in the following order: As > Cr > Pb > Ni > Cd > Hg. Regarding their accumulation in the seafood products, masmin showed the highest levels followed by SIO, MIO, TIO, FP, and PP. The results revealed that smoked products showed higher TM concentrations, followed by canned and pickled products. The level of TMs in seafood products was below the maximum residue limit set by the European Commission (EC/1881/2006) and the Food Safety and Standards Authority of India (FSSAI). Risk assessment for consumer health implied that the evaluated target hazard quotient (THQ < 1), hazard index (HI < 1), and target cancer risk (TCR < 1.E-04) values did not exceed their guideline values and did not cause non-carcinogenic and carcinogenic health impacts through seafood product consumption. The pollution index (Pi) values of TMs in seafood products ranged from 0.01 to 0.7, with As and Cd showing the lowest and highest values, which were below 0.7, indicating their safety for consumption. The metal pollution index (MPI) for TMs in seafood ranged from 9.E-05 to 0.007, with the lowest and highest values associated with PP and TIO products. The MPI value for seafood products was below 1, signifying low TMs accumulation, suggesting the safety of seafood for consumption. The maximum seafood meal consumption limit (CRmm) was calculated, showing that adults can safely consume > 16 meals/month without chronic or acute toxicity. The results of this study suggest that the accumulation of TMs in the analyzed seafood product was below the health guidelines and pollution index values, making it suitable for smooth domestic and international export as well as safe consumption.

Potentially toxic metals in seawater, sediment and seaweeds: bioaccumulation, ecological and human health risk assessment

This study assesses the bioaccumulation, ecological, and health risks associated with potentially toxic metals (PTMs), including Pb, Hg, Cd, As, and Cr in Hare Island, Thoothukudi. The results revealed that the concentration of PTMs in sediment, seawater, and S. wightii ranged from 0.095 to 2.81 mg kg-1, 0.017 to 1.515 mg L-1, and 0.076 to 5.713 mg kg-1, respectively. The highest concentrations of PTMs were found in the S. wightii compared to seawater and sediment. The high bioaccumulation of Hg and As in S. wightii suggests that it can be used as a bioindicator for these elements in this region. The ecological risk indices, which include individual, complex, biological, and ecological pollution indices, suggest that Hare Island had moderate contamination with Hg and Cd. However, there are no human health risks associated with PTMs. This study examines the current ecological and health risks associated with PTMs and emphasizes the importance of regular monitoring.

De-novo exposure assessment of heavy metals in commercially important fresh and dried seafood: Safe for human consumption

The heavy metals (HMs) in seafood are alarming due to their biomagnification in the food chain. The concentrations of As, Cd, Hg, Pb, Cr, and Ni in both fresh and dried fish were quantified, and the potential exposure and safe intake levels for human consumption were assessed by the European Commission (EC) and the Food Safety Standard Authority of India (FSSAI). HMs concentrations ranged from 0.003 mg/kg (Cr) to 2.08 mg/kg for (As) and 0.007 mg/kg (Hg) to 2.76 mg/kg (As). Cd, Hg, and Pb levels in fresh and dried fish were below the maximum residue limits (MRLs) set by the EC and FSSAI, which were 0.1 mg/kg, 0.5 mg/kg, and 0.3 mg/kg, respectively. Cr and As concentrations were also below the MRLs of 12 mg/kg and 76 mg/kg for aquatic products specified by FSSAI. The concentration of HMs in fresh and dried fish was found in the order of As > Cr > Ni > Pb > Cd > Hg and As > Cd > Cr > Ni > Pb > Hg, while the fresh and dried fishes contained HMs in the following order: E. areolatus > S. longiceps > L.lentjen > S. barracuda > E. affinis > S. javus and DA > DS > DR > DB > DSF. The metal pollution index (MPI) validates seafood is HMs free, while the single (Pi) and Nemerow integrated pollution index (Pnw) indicate that concentrations of Cd and As in fresh and dried fish have exceeded the threshold value. The target hazard quotient (THQ<1), hazard index (HI < 1), and target cancer risk (TCR<10-4) indicate that there are no non-carcinogenic and carcinogenic risks through the consumption of seafood and seafood products collected from the Tuticorin coast and marketed at the domestic and international levels. The preliminary findings emphasize the importance of formulating domestic legislation/government initiatives to promote seafood and its consumption. The attainment of this objective shall be facilitated by examining the levels of persistent organic pollutants (POPs) in seafood and evaluating its potential risk to consumers.

Toxicological effect of endocrine disrupting heavy metal (Pb) on Mekong silurid Pangasius catfish, Pangasius hypophthalmus

The current study aimed to investigate the effects of lead nitrate exposure on the enzymatical, haematological, and histological changes in the gill, liver, and kidney of Pangasius hypophthalmus. The fish were divided into six groups and treated with different Pb concentrations. The LC50 value of Pb was 55.57 mg/L at 96 h for P. hypophthalmus, and sublethal toxicity was assessed for 45 days at 1/5th (11.47 mg/L) and 1/10th (5.57 mg/L) of LC50 concentration. Enzymes such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels, alkaline phosphate (ALP), and lactate dehydrogenase (LDH) content increased significantly during sublethal toxicity of Pb. The reduction of HCT and PCV indicates an anemic condition due to the toxicity of Pb. Differential leucocytes, lymphocytes, and monocytes and their % values significantly decreased, indicating Pb exposure. The main histological changes observed in the gills were the destruction of secondary lamellae, the fusion of adjacent gill lamellae, primary lamellae hypertrophy, and severe hyperplasia, while in kidney exposed to Pb showed melanomacrophages, increased periglomerular, peritubular space, vacuolation, shrunken glomerulus, destruction of tubular epithelium, and hypertrophy of distal convoluted segment. The liver showed severe necrosis and rupture of hepatic cells, hyper trepheoid bile duct, shifting of nuclei, and vascular hemorrhage, while in the brain, binucleus, mesoglea cells, vacuole, and ruptured nucleus were observed. In conclusion, P. hypophthalmus, which has been exposed to Pb has developed a number of toxicity markers. Consequently, prolonged exposure to higher Pb concentrations may be harmful to fish health. The findings strongly suggest that the lead had a detrimental impact on the P. hypophthalmus population, as well as on the water quality and non-target aquatic organisms.

Risk source identification and diffusion trends of metal(loid)s in stream sediments from an abandoned arsenic-containing mine

Stream sediments from mine area are a converging source of water and soil pollution. The risk and development trends of metal(loid)s pollution in sediments from an abandoned arsenic-containing mine were studied using modelling techniques. The results showed that the combined techniques of geographic information system (GIS), random forest (RF), and numerical simulation (NS) could identify risk sources and diffusion trends of metal(loid)s in mine sediments. The median values of As, Cd, Hg, and Sb in sediments were 5.01, 3.02, 5.67, and 3.20 times of the background values of stream sediments in China, respectively. As (14.09%) and Hg (18.64%) pollution in mine stream sediments were severe while As is the main potential risk source with a strong spatial correlation. High-risk blocks were concentrated in the landfill area, with the surrounding pollution shows a decreasing trend of "step-type" pollution. The risk correlation between Hg and As (55.37%) in the landfill area is high. As a case of arsenic, the diffusion capacity of As within 500m is strong and stabilizes at 1 km when driven by the flows of 0.05, 0.5, and 5 m³/s, respectively. With the worst-case scenario flow (86 m³/s), it would take only 147 days for the waters within 3 km to become highly polluted. The high pollution levels in a stream under forecast of different distance intervals (500, 1500, 2000 m) within 6.5 km is arrived at approximate 344, 357, and 384 days, respectively. The study suggested the combined technique of GIS, RF, and NS can serve the risk source identification of contaminated sites and risk forecast of toxic element diffusion in emergency situations.

Spatial distribution, ecological risk, and human health assessment of heavy metals in lake surface sections - a case study of Qinghai Lake, China

Qinghai Lake is the largest inland saltwater lake in China, with a drainage area of 29,661 km². This study sought to conduct an ecological and human health risk assessment of metals and heavy metals, including copper, as well as investigate their concentration, distribution, and source distribution. In terms of seasonal variation, the increases in Fe, Cr, As, Pb, and Hg were relatively large, and the spatial distribution of metals presented a three-level stepped distribution trend, gradually increasing from east to west. By further exploring the source and migration path of pollutants, our study found that the source of metals in the sediments of Qinghai Lake is mainly controlled by five rivers entering the lake. Enrichment factor (EF) calculations indicated that the metal accumulation or enrichment capacity of the three central points in Qinghai Lake Basin was strong. Interestingly, the enrichment capacity of Cu and Zn was the strongest among all metals but occurred at low and medium concentration levels, respectively. The Igeo and [Formula: see text] ecological risk assessment results indicated that the individual metals posed little to no ecological risks to the Qinghai Lake Basin. However, the multi-element environmental risk comprehensive index (RI) indicated that Hg (RI = 147.97) represented a slight ecological hazard, Mn (RI = 181.13) posed moderate ecological hazards, and Zn (RI = 386.66) posed strong ecological hazards. The human health risk assessment results showed that the heavy metals in the surface sediments of Qinghai Lake currently do not pose a threat to human health. This information may facilitate the implementation of more stringent monitoring programs in the aquatic ecosystem by the relevant regulatory authorities.

Bioaccumulation of organochlorine pesticide residues (OCPs) at different growth stages of pacific white leg shrimp (Penaeus vannamei): First report on ecotoxicological and human health risk assessment

Pesticide residues (PRs) in farmed shrimps are concerning food safety risks. Globally, India is a major exporter of pacific white leg shrimp (P. vannamei). This study was undertaken to analyze PRs in the water, sediments, shrimps, and feed at different growth stages to evaluate the ecotoxicological and human health risks. PRs in the seawater and sediments ranged from not detected (ND) to 0.027 μg/L and 0.006-12.39 μg/kg, and the concentrations were within the maximum residual limits (MRLs) and sediment quality guidelines prescribed by the World Health Organization and Canadian Environment Guidelines, respectively. PRs in shrimps at three growth stages viz. Postlarvae, juvenile, and adults, ranged from ND to 0.522 μg/kg, below the MRLs set by Codex Alimentarius Commission and European Commission. Most of the PRs in water, sediments, and shrimps did not vary significantly (p > 0.05) from days of culture (DOC-01) to DOC-90. The hazard quotient (HQ) and hazard ratio (HR) were found to be < 1, indicating that consumption of shrimps has no noncarcinogenic and carcinogenic risks. PRs in shrimp feed ranged from ND to 0.777 μg/kg and were found to be below the MRLs set by EC, which confirms that the feed fed is safe for aquaculture practices and does not biomagnify in animals. The risk quotient (RQ) and toxic unit (TU) ranged from insignificant level (ISL) to 0.509 and ISL to 0.022, indicating that PRs do not pose acute and chronic ecotoxicity to aquatic organisms. The study suggested no health risk due to PRs in shrimps cultured in India and exported to the USA, China, and Japan. However, regular monitoring of PRs is recommended to maintain a sustainable ecosystem.

Exopolysaccharides from marine microbes with prowess for environment cleanup

A variety of both small and large biologically intriguing compounds can be found abundantly in the marine environment. Researchers are particularly interested in marine bacteria because they can produce classes of bioactive secondary metabolites that are structurally diverse. The main secondary metabolites produced by marine bacteria are regarded as steroids, alkaloids, peptides, terpenoids, biopolymers, and polyketides. The global urbanization leads to the increased use of organic pollutants that are both persistent and toxic for humans, other life forms and tend to biomagnified in environment. The issue can be addressed, by using marine microbial biopolymers with ability for increased bioremediation. Amongst biopolymers, the exopolysaccharides (EPS) are the most prominent under adverse environmental stress conditions. The present review emphasizes the use of EPS as a bio-flocculent for wastewater treatment, as an adsorbent for the removal of textile dye and heavy metals from industrial effluents. The biofilm-forming ability of EPS helps with soil reclamation and reduces soil erosion. EPS are an obvious choice being environmentally friendly and cost-effective in processes for developing sustainable technology. However, a better understanding of EPS biosynthetic pathways and further developing novel sustainable technologies is desirable and certainly will pave the way for efficient usage of EPS for environment cleanup.

Accumulation potential of heavy metals at different growth stages of Pacific white leg shrimp, Penaeus vannamei farmed along the Southeast coast of Peninsular India: A report on ecotoxicology and human health risk assessment

This study compared the heavy metal concentration in water, sediment, and shrimp at different growth stages of culture and subsequently evaluated the ecotoxicological and human health risk status. Total trace element concentration in the water, sediment and shrimp ranged from not detected (ND) (Hg) to 91.05 (Fe) μg/L, 0.01 (Hg) to 19, 246.33 (Fe) mg/kg, and ND (Hg) to 13.98 (Fe) mg/kg, respectively. Toxic metals such as, Cd, Hg, and Pb in shrimps ranged from ND to 2.11 mg/kg, ND to 0.158 mg/kg, ND to 0.088 mg/kg, and ND to 0.469 mg/kg, respectively. Toxic heavy metals at all the growth stages of shrimps (days of culture (DOC)-01 to DOC-90) were found below the maximum residual limit (MRL) of 0.5 mg/kg set by the European Commission (EC). Similarly, Cu, Zn, and As concentrations in shrimp were also far below the MRLs of 30 mg/kg, 100 mg/kg, and 76 mg/kg set by the World Health Organization and Food Safety and Standard Authority of India, respectively. The concentration of heavy metals increased from DOC-01 to DOC-90 and was positively correlated with the length and weight of the shrimps (p < 0.05). The risk assessment was estimated for both Indians and Americans and found no carcinogenic (lifetime cancer risk (LCR) < 10-4) and non-carcinogenic (THQ and TTHQ<1) health risks through consumption of shrimp cultured in this region. The hazard quotient (HQdermal < 1), hazard index (HI < 1), and LCR (<10-4) values of the heavy metals indicated that the dermal absorption might not be a concern for the local fishermen and marine fish/shrimp farmworkers. Water and sediment quality indices were applied to assess the surface water and sediment quality, and their results were found nil to low levels of heavy metal contamination at all the sampling sites. All heavy metals studied in sediments were < effect range low (ERL) and < threshold effect level (TEL), indicating no adverse biological effects on aquatic organisms. Therefore, regular monitoring of the shrimp aquaculture system throughout the crop will provide evidence of heavy metals bioaccumulation in shrimps. This research will provide baseline data to help farmers establish the optimal aquaculture practices and regulatory authorities to formulate legislation and strategies to reduce heavy metal biomagnification in shrimps from farm to fork.

The influence of anthropogenic activities on heavy metal pollution of estuary sediment from the coastal East China Sea in the past nearly 50 years

Historical records of eight heavy metals (HMs: Cu, Zn, Cr, Ni, Pb, As, Hg and Cd) were analyzed in two dated sediment cores collected from the coastal East China Sea (Meishan Bay, MSB) to investigate the influence of anthropogenic activities on estuary sediment from 1972 to 2019. The sedimentary records of HMs in the two cores reflected the development of economy and change of energy consumption in China's east coastal areas. The contents of most HMs in sediments had no change or showed a downward trend before the 1980s. After the 1980s, the contents of HMs showed an increasing trend, mainly because of the rapid development of aquaculture, industry, and agriculture. The distribution of HMs outside the bay (OB) was mainly affected by industry, shipping, and agriculture (vegetable planting), while HMs in sediments inside the bay (IB) was affected by shipping, agriculture, and aquaculture. Principle component analysis (PCA) showed that Cd, Cr, and Ni could be attributed to industrial discharge, while As, Cu, Pb, and Zn were associated with shipping, agriculture, and aquaculture. Sediments were slightly polluted with Cd (I_geo:0.10-0.71, CF:1.90-7.74) and Ni (I_geo:0.08-0.92, CF:1.25-12.55), and seriously polluted with Hg (I_geo:0.95-1.76, CF:13.43-85.65). This study provides insights for the local governments to raise awareness of HM pollution in the coastal East China Sea and formulate corresponding pollution control measures.

Concentrations and risk assessment of metals and microplastics from antifouling paint particles in the coastal sediment of a marina in Simon's Town, South Africa

Maintenance of maritime vessels includes the removal of paint from hulls that are sources of metals, antifouling paint particles (APPs) and microplastics (MPs) that end up in the coastal environment. Simon's Town is a small urban town in False Bay, Cape Town, South Africa, where maritime activities take place (there is a naval harbour, marina and shipyard). The aim of this study was to measure metals, APPs and MPs in Simon's Town, to assess the impact of maritime activities and a storm water pipe in a sheltered marina. Sediment samples were collected from six sites during winter 2018. Sediment and extracted APPs were analysed for metal concentrations (Al, As, B, Ba, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sb, Sn, Sr, V and Zn) and MPs characterised based on type (shape and polymer), colour and size. Highest average metal concentrations in sediment for all sites were Fe (32228 ± SEM 4024), Al (12271 ± 1062) and Cu (1129 ± 407). Metals in paint particles were highest for Fe (80873 ± 19341), Cu (66762 ± 13082) and Zn (44910 ± 1400 µg/g). Metal and MP fragment concentrations were highest at the slipway of the shipyard, decreasing with increased distance from the slipway. MP filaments were highest close to the storm water outfall pipe. Our results suggest that shipyards are potential sources of metals and MP fragments (mainly APPs), with storm water pipes potential sources of MP filaments. Various indices applied to assess the potential impacts of metals and MPs suggest that these contaminants have the potential to adversely impact the intertidal ecosystem investigated.

Effect of household culinary processes on organochlorine pesticide residues (OCPs) in the seafood (Penaeus vannamei) and its associated human health risk assessment: Our vision and future scope

Food safety is crucial in today's competitive trading market, as it directly affects human health and promotes seafood exports. The effects of thermal processing (boiling, frying, grilling, and microwave cooking) on pesticide residues (PR) in P. vannamei were assessed. The PR in raw and processed shrimp ranged from 0.007 to 0.703 μg/kg for uncooked/raw, not detected (ND) to 0.917 μg/kg for boiled, ND to 0.506 μg/kg for fried, ND to 0.573 μg/kg for grilled and ND to 0.514 μg/kg for microwave cooked shrimps. The Endrin, endosulfan sulfate, and heptachlor were predominant PR found in the raw and processed shrimp. The PR content in raw and cooked shrimps were below the maximum residue limits (MRL) set by the Codex Alimentarius Commission (2021) and the European Commission (86/363/1986 and 57/2007). The estimated daily intake (EDI) of PR from raw and processed shrimps were below the ADI prescribed by CAC. The hazard quotient (HQ) and hazard ratio (HR) values were <1, indicating no non-carcinogenic or carcinogenic health implications through shrimp consumption. The estimated maximum allowable shrimp consumption rate (CRlim) suggests an adult can eat >100 shrimp meals/month, which is over the USEPA's (2000)recommendation of >16 meals/month without health issues. The Effect of thermal processing was detected in the following order: boiling < grilling < frying < microwave cooking. The processing factor (PF < 0.7), paired t-test (t < 0.05), Tukey post hoc (p < 0.05) test, Bray-Curtis similarity index, and matrix plot exhibited that all the four thermal processing methods have a considerable impact on pesticides in the processed shrimps. But frying (59.4%) and microwave cooking (60.3%) reduced PR far beyond boiling (48.8%) and grilling (51.3%). Hence, we recommend frying and microwave processing are better methods for minimizing PR in seafood than boiling or grilling.

Coastal macrophytes as bioindicators of trace metals in the Asia's largest lagoon ecosystem

Coastal trace metal contamination is of serious concern and the role of new bioindicator species in monitoring of trace metals is essential. The present study quantified the concentration of trace metals (Co, Cr, Cu, Mn, Ni, Pb and Zn) in the sediment and the macrophytes of Chilika lagoon, India, and investigated the bioindicator potential of the seagrasses, saltmarshes and macroalgae. The Igeo values for sediment indicated significant contamination of Cu and Zn in seagrass, Cu, Ni and Zn in saltmarsh and moderate contamination of Cr, Cu and Pb in macroalgal ecosystems. In general, the Bio-Sediment Accumulation Factor (BSAF) indicated that the macrophytes accumulated higher concentration of Mn and Ni from the sediments. The high concentration of trace metals in the sediment of the three macrophytes ecosystems did not result in higher accumulation of the same metals in the tissues of the respective macrophytes suggesting metal specific and species-specific behaviour.

Distribution and ecological risk assessment of heavy metals using geochemical normalization factors in the aquatic sediments

Thamirabharani river acquires a noticeable quantity of sewage and agriculture waste from local inhabitants. The distribution of heavy metals in the surface sediments of the Thamirabharani river was analyzed using Inductively Coupled Plasma- Mass Spectrometry (ICP-MS) to study the ecological risks. The heavy metal concentrations in the sediments ranged from 0.098 ± 0.03(Cd) to 159.181 ± 13.36 mg kg-1 (Fe). The Cd, Zn, Ni, Fe, and Mn concentrations in the sediments were above the US Environmental Protection Agency-Sediment Quality Guidelines. The fact that Cd, Co, and Cu concentrations at sites 4 and 5 exceeded the background values (BGVs) of 0.2, 13, and 32 mg kg-1 suggests anthropogenic activity, notably in the downstream of the river. The sediment contaminated with Cd is more evident, particularly in the estuarine region. The potential ecological risk index (150 Collapse

Key Words

• Degree of contamination
• Ecological risk co-efficient
• Enrichment factor
• Heavy metal pollution
• Pollution load index
• Sediment quality

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MESH Headings

• Ecosystem
• Environmental Monitoring
• Geologic Sediments
• Metals, Heavy/analysis
• Risk Assessment
• Water Pollutants, Chemical/analysis

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Affiliation(s)

Ulaganathan Arisekar Department of Fish Quality Assurance and Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Tuticorin, 628 008, Tamil Nadu, India.
Robinson Jeya Shakila Department of Fish Quality Assurance and Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Tuticorin, 628 008, Tamil Nadu, India.
Rajendren Shalini Department of Fish Quality Assurance and Management, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Tuticorin, 628 008, Tamil Nadu, India
Geevartnam Jeyasekaran Tamil Nadu Fisheries University Nagapattinam, 611 002, Tamil Nadu, India
Muruganantham Keerthana Department of Fisheries and Fishermen Welfare, Thoothukudi, 628 008, Tamil Nadu, India
Natarajan Arumugam Department of Chemistry, College of Science, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia
Abdulrahman I Almansour Department of Chemistry, College of Science, King Saud University, P.O Box 2455, Riyadh, 11451, Saudi Arabia
Karthikeyan Perumal Department of Chemistry and Biochemistry, The Ohio State University, 151 W. Woodruff Ave, Columbus, OH, 43210, USA

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Potentially toxic elements contamination and its removal by aquatic weeds in the riverine system: A comparative approach

Thamirabarani river acquires large untreated sewage effluents from the Tirunelveli and Thoothukudi districts of South Tamil Nadu. This study examined the concentration of trace elements in water, sediment, and phytoaccumulation potential of aquatic weeds viz., A. cristata, E. crassipes, S. natans, and P. stratiotes, growing along Srivaikundam dam of Thamirabarani river. The Pb, As, Hg, Cd, and Ni concentrations in water were slightly higher than the US Food and Drug Administration (USFDA) drinking water guidelines; however, their accumulation in sediment was below WHO's sediment quality guideline. This study concludes that the phytoaccumulation factor (PAF) and translocation factor (TF) was >1 in E. crassipes and A. cristata, representing them as hyperaccumulators, suitable for phytoremediation in polluted localities. E. crassipes, A. cristata, and S. natans accumulated (100-500 fold) higher trace elements concentrations than that present in the water. Also, the concentrations of trace elements found in the aquatic weeds were below the recommended levels for the critical plant range (CRP). These selected aquatic weeds are more suitable for plant hybridization to be modified as superbug plants.

Determination of heavy metal baseline levels and threshold values on marine sediments in the Bay of Biscay

Several international institutions have defined background or baseline levels to assess heavy metal concentrations on marine sediments in order to use these values as a reference for sediment quality indices. This criterion for marine sediment quality is applied to evaluate the potential risk of pollutants in aquatic ecosystems. However, those values were established using samples collected in large areas which present specific geochemical conditions. Then there may be a lack of accuracy in the results when using these parameters in other areas. In this context, 15 sediment cores (8 cm diameter; 2 m length) were recovered along the 400 km Asturian coastline, which is an area with representative lithological conditions for the Bay of Biscay, to determine more precise baseline levels for marine sediments from the Bay of Biscay. An evaluation of statistical and empirical methods was done to determine which method delivers the best results. Statistical methods such as mean±2SD and median±2* Median Absolut Deviation (MAD) are strongly influenced by outliers and data distributions which make these approaches less robust. Graphic techniques such as Cumulative Distribution Function (CDF) avoid the problems that asymmetrical data distributions may cause but introduce a certain level of subjectivity in the results due to the baseline values obtained depending on the researcher's experience. Finally, the Probability Curve (CP) method solves issues which may occur when using other techniques and allows one to establish baseline levels based on different percentiles. Regarding the features of the data analysed in this study, the baselines obtained via the CP method with the 95th percentile appear to be the most accurate for the Bay of Biscay. A wide variation has been found between the new baseline values and other international and national levels. Disparity between those levels and the baselines obtained in this study can be generated by granulometric and geological factors. The notable increase in Hg baseline values with respect to OSPAR Background Concentration values (BCs) (0.05 μg g^-1 and 0.6 μg g^-1 respectively) and the huge different with CEDEX levels and new threshold levels (0.35 μg g^-1 and 1.2 μg g^-1 respectively) emphasised the relevance of defining specific baselines and threshold levels, as the ones obtained in this study, not only to obtain more precise criteria for marine sediment quality to be used in environmental assessments, but also to propose new threshold levels for the evaluation of dredged material before dumping into ocean sites.