Vertical distribution and contamination assessment of heavy metals in sediment cores of ship breaking area of Bangladesh

Mapping trace metal footprints: Distribution, sources, and risk assessment in coastal sediments near a heavy industrial zone in Bangladesh

This study investigated nine trace metals (Cr, Co, Cu, Cd, Ni, Mn, Fe, Zn, and Pb) concentrations of coastal sediments adjacent to a heavily industrialized area of Bangladesh using AAS. The most prevalent metals were zinc, with lesser amounts of Cd and Co. Pb, and Cd levels were higher than world standards, with a considerable enrichment of Pb at station 9. Ecological risk assessments showed moderate to high contamination, particularly by Pb and Cd. The Nemerow integrated pollution index demonstrated that overall pollution was low, but the levels about Cd were still concerning. All stations had hazard indices below 1 but chronic exposure to Ni, presents grounds for concern. Industry, urbanization, traffic, and agricultural runoff along with lithogenic sources have been identified to be the main sources of pollution using receptor modeling. The outcomes underscore the urgency that management measures must be taken to safeguard ecosystem and public health.

Spatial distribution of heavy metal in sands and sediments of Parki Beach, Chattogram, Bangladesh

To assess the sources, levels, spatial distributions and exposure to human health, the concentration of heavy metals Pb, Cu, Mn, Zn, and Fe in the sand/sediment of the Parki Beach area of Anowara, Chattogram, Bangladesh are determined using Atomic Absorption Spectroscopy (AAS) for the first time. A total of 40 surface and subsurface sand and sediment samples were collected from 20 different sampling points along the 15 km long Parki Beach area, Bangladesh. Average concentrations of Pb, Cu, Mn, Zn and Fe in surface samples are 14.60, 10.10, 283, 407 and 25,256 mg/kg respectively and 9.95, 4.20, 193, 156.6 and 24,404 mg/kg for sub-surface samples, respectively, which shows that the values are higher in surface samples than those in sub-surface samples. According to the Consensus-Based Sediment Quality Guidelines (CBSQG), the northern part of the beach becomes moderately polluted by Mn and Fe, and a smaller area of the southern part is highly polluted by Zn. The average Contamination Factor (CF) of Zn was greater than 1(CF > 1), while the CF of other metals was less than 1(CF < 1). CF of Zn in some sampling points was exceptionally high. Geo-accumulation Index (Igeo) also shows that Zn slightly pollutes some sampling points. The enrichment Factor (EF) of Fe and Mn in samples in the northern part of the study area is quite high and the study reveals that high values of Fe and Mn are mainly derived from geogenic sources. Ecological risk factor (Er) indicates low ecological risk for all sampling points. The Pollution Load Index (PLI) was measured at all sampling stations, and the results showed that the overall level of heavy metal pollution is low. The health quotient (HQ), health index (HI), total health index (THI) and incremental life time cancer risk (ILCR values suggest that adults are safe from any health risk while children may experience non carcinogenic health risk due to the combined effect of the metals. Reduction of heavy metal in the beach is possible with the adaptation of multiple strategies. This data can be used by policymakers to develop strategies to reduce the potential impacts of soil contamination on the environment and public health.

Historical trends of heavy metals applying radio-dating and neutron activation analysis (NAA) in sediment cores, Burullus Lagoon, Egypt

Burullus lagoon is part of Egypt's protected area network. The lagoon serves as a reservoir for drainage water discharged from agricultural areas, and the lake's sediments provide a unique opportunity to record environmental behavior and reconstruct of the heavy metal contamination history. In the present study, the sediment chronology, sedimentation rates, and metal accumulation fluxes were estimated in four sediment cores using 210Pb dating models to evaluate how human activities have affected the coastal environment. Using the radioisotopes 210Pb and 137Cs, radiometric dating was carried out using gamma-ray spectrometry. At the Egypt Second Research Reactor (ETRR-2), the element concentrations were determined using the instrumented neutron activation analysis (INAA- k0 method). Our findings show that the constant rate of supply (CRS), which has been verified with the peak of artificial radionuclide 137Cs, is the best model performed for the chronology of Burullus Lagoon. The average sedimentation rate, according to 210Pb dating models, is 0.85 cm/year. The large variation in sedimentation rates, especially after the 1990s, is consistent with an increase in the anthropogenic flux of heavy metals. This may be led into a significant environmental problem such as reducing the size of the lake and degrading the quality the water in Burullus Lagoon. Enrichment factor (EF) of the studied elements displayed the following order: Cl > Ca > Na > Br > Zn > Ta > Ti > V > Cr > Sc > Mg > Mn > Fe > Hf which is higher than unity. Furthermore, the Nemerow pollution index (PI Nemerow) revealed that pollution was increasing in the direction of the drains and slightly polluted. Consequently, pollutant indices showed that urbanization and industrial development may have increased the depositional fluxes of the metals in sediments over time.

Source-specific geochemical and health risk assessment of anthropogenically induced metals in a tropical urban waterway

Thorough deliberation is necessary to safeguard the tropical urban streams near the shoreline from human interference, as it is becoming a notable environmental danger. Consequently, an in-depth study was carried out on a significant urban waterway located on the southern seashore of Bangladesh, which is positioned in the Bengal delta, renowned as the largest delta in the globe. The current investigation assesses the potential health hazards associated with trace metals (Hg, Cu, As, Pb, Ni, Zn, Cd, Cr, Fe, and Mn) and uses chemometric analysis to determine where they originate. Likewise geochemical methods are used to analyze the levels of trace metal enrichment and pollution in the sediments of the river. Almost all of the elements' mean concentrations were observed to be within the standard limits. The findings not only demonstrate the extent of trace metal contamination but also the health threats that it poses to the public (male, female, and children) by polluting the sediment. For all age groups of people, the hazard index was <1, suggesting there was no non-carcinogenic threat. Regardless of age and sex, exposure occurred in descending order: ingestion > dermal > inhalation. Total carcinogenic risk (TCR) values for males, females, and children were 1.45E-05, 1.56E-05, and 1.34E-04, respectively, recommending that children are at greater vulnerability than adults. The geochemical approach and chemometric analysis corroborate the human-induced impact of trace metal loading in the sediment of the waterway, which is predominantly caused by the oil industry, domestic garbage, and untreated waste discharge.

Assessing metal(loid)s-Induced long-term spatiotemporal health risks in Coastal Regions, Bay of Bengal: A chemometric study

Despite sporadic and irregular studies on heavy metal(loid)s health risks in water, fish, and soil in the coastal areas of the Bay of Bengal, no chemometric approaches have been applied to assess the human health risks comprehensively. This review aims to employ chemometric analysis to evaluate the long-term spatiotemporal health risks of metal(loid)s e.g., Fe, Mn, Zn, Cd, As, Cr, Pb, Cu, and Ni in coastal water, fish, and soils from 2003 to 2023. Across coastal parts, studies on metal(loid)s were distributed with 40% in the southeast, 28% in the south-central, and 32% in the southwest regions. The southeastern area exhibited the highest contamination levels, primarily due to elevated Zn content (156.8 to 147.2 mg/L for Mn in water, 15.3 to 13.2 mg/kg for Cu in fish, and 50.6 to 46.4 mg/kg for Ni in soil), except for a few sites in the south-central region. Health risks associated with the ingestion of Fe, As, and Cd (water), Ni, Cr, and Pb (fish), and Cd, Cr, and Pb (soil) were identified, with non-carcinogenic risks existing exclusively through this route. Moreover, As, Cr, and Ni pose cancer risks for adults and children via ingestion in the southeastern region. Overall non-carcinogenic risks emphasized a significantly higher risk for children compared to adults, with six, two-, and six-times higher health risks through ingestion of water, fish, and soils along the southeastern coast. The study offers innovative sustainable management strategies and remediation policies aimed at reducing metal(loid)s contamination in various environmental media along coastal Bangladesh.

Origin, spatial distribution, sediment contamination, ecological and health risk evaluation of trace metals in sediments of ship breaking area of Bangladesh

Eleven trace metals (Cd, Cr, Fe, Mn, Cu, Ni, Co, Zn, As, Pb, and Ag) in sediments of Bangladesh's ship breaking area were measured by an atomic absorption spectrometer to determine origin, contamination extent, spatial distributions, and associated ecological and human health hazards. This study found considerable quantities of Pb, Cd, Mn, Zn, and Cu when compared with standards and high levels of Pb, Cd, Zn, Cu, As, and Ag contamination according to pollution evaluation indices. Different indices indicate most of the sampling sites were highly polluted. However, spatial distribution maps indicate that trace metals were predominantly deposited in the northern and southern region. The ecological risk index revealed that Cd has the highest while Pb and As had moderate risk. Based on the health index values, Zn for both adults and children were higher than the safe limit while Mn, Pb, Cr, As, Fe, Cu, Ni, and Co for children were close to the threshold. The mean total carcinogenic risk values of Cr, As, and Ni for children and Ni for adults exceeded the permissible threshold. The cancer risk possibilities were further assessed using Monte Carlo simulation. Most trace metals have anthropogenic origins, which were attributed to ship breaking activities.

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.

Vertical distribution and trace element contamination in sediment cores affected by gold mining in Colombia

The vertical distribution, level of contamination, potential ecological risks, and historical fluxes of trace elements (Pb, As, and Hg) were evaluated from 210Pb-dated sediment cores in three different areas with gold mining impacts in northern Colombia: the Atrato River (AR), the Delicias Marsh (DM) and the Encaramada Marsh (EM). All cores spanned ∼100 years; the mass accumulation rates followed the order AR > DM > EM. The average trace elements concentrations in the sediment cores were: Pb 2.41 ± 0.72, As 0.65 ± 0.32, Hg 0.07 ± 0.02 μg g-1 in the Atrato River; Pb 23.49 ± 2.59, As 2.46 ± 0.88, Hg 0.10 ± 0.02 μg g-1 in the Delicias Marsh; and Pb 9.76 ± 4.18, As 2.44 ± 1.26, Hg 0.17 ± 0.06 μg g-1 in the Encaramada Marsh. Sediments are classified according to the contamination factor (CF) and geoaccumulation index (Igeo) as low to very highly contaminated. The Pollution load index (PLI) indicates environmental deterioration (PLI> 1), and the Sediment quality guidelines (SQGs) indicate that only Hg may produce adverse biological effects in the EM core. This study is an example of the reconstruction of temporal changes in pollution levels and impacts of potentially toxic elements caused by gold mining in remote ecosystems, which can be reproduced in other areas where environmental monitoring is scarce or non-existent.

Comparative analysis of temporal variation of heavy metal accumulation by two sea urchin species from a harbour region, including pre and post COVID 19 lock down period

Sea urchins are marine invertebrates belonging to phylum Echinodermata, recognized as relevant biological tool for assessing environmental pollution. In the present study, we assessed the bioaccumulation potential of different heavy metals by two sea urchin species, Stomopneustes variolaris Lamarck, 1816 and Echinothrix diadema Linnaeus, 1758, collected from a harbour region, along the south west coast of India, during four different sampling periods for 2 years, from the same sea urchin bed. Heavy metals like Pb, Cr, As, Cd, Co, Se, Cu, Zn, Mn and Ni were analysed from water, sediment and different body parts of sea urchins, such as shell, spine, tooth, gut and gonad. The sampling periods also included the pre and post COVID 19 lockdown period during which the harbour activities were closed. The bio-water accumulation factor (BWAF), bio-sediment accumulation factor (BSAF) and the metal content/test weight index (MTWI) were calculated, in order to compare the bioaccumulation of metals by both the species. The results showed that S. variolaris had higher bioaccumulation potential than E. diadema, for metals like Pb, As, Cr, Co and Cd especially in the soft body parts like gut and gonad. The hard parts of S. variolaris like shell, spine, and tooth also accumulated more Pb, Cu, Ni and Mn than E. diadema. Following the lockdown period, there was a decline in the concentration of all heavy metals in water, whereas in sediment, Pb, Cr, and Cu levels were reduced. The gut and gonad tissues of both the urchins showed a decrease in the concentration of most of the heavy metals following the lockdown phase and no significant reduction was observed in the hard parts. This study reveals the use of S. variolaris as an excellent bioindicator of heavy metal contamination in the marine environment which can be employed for coastal monitoring programs.

Assessment of potential ecological risk based on the vertical characteristics of potential toxic elements in sediments from a high-density cage culture reservoir in China

The pollution of sediments around Lu Ban Island is a serious environmental issue that is threatening human health. The concentration of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn at 73 layer points were investigated, vertical distribution characteristics, correlation among potential toxic elements and potential ecological risks of sediments at different depth were analyzed. The following results were obtained, (1) the hypothesis that there was a linear relationship between concentration of potential toxic elements and the reciprocal of deep was reasonable. Based on hypothesis, the ultimate value of concentration by making depth go to infinity was regarded as the background concentration. The background concentration of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn are respectively 4.94 mg/kg, 0.20 mg/kg, 15.48 mg/kg, 58.41 mg/kg, 0.062 mg/kg, 26.96 mg/kg, 20.29 mg/kg, and 53.31 mg/kg. (2) But correlation between Ni and As was relatively weak, high degree of correlation among other potential toxic elements were found. Based on their correlation, eight potential toxic elements were classified into three groups. First group included Ni and Cr, mainly releasing by coal burning; Cu, Pb, Zn, Hg, and Cd were grouped together, possibly due to their shared source of fish cage culture; Arsenic with relatively weak correlation with other potential toxic elements was classified as a separate class, which was usually one important mineral resource associated with phosphate. (3) Potential ecological risk index (PERI) of sediment above - 0.40 m belonged to moderate risk, the PERI of sediment in - 0.10 m, - 0.20 m, and - 0.40 m were 289.06, 254.33, and 201.44, respectively. Sediment below - 0.40 m belonged to low risk with average PERI value 112.82, with no significant changes in PERI values. The order of contribution to PERI was Hg > Cd > As > Cu > Pb > Ni > Cr > Zn. (4) According to result of cluster analysis and potential ecological risk, the potential ecological risk of sediment above - 0.40 m mainly contributed by potential toxic elements of Cu, Cd, Hg, Pb, and Zn sharing source of fish cage culture.

Pollution trends and ecological risks of heavy metal(loid)s in coastal zones of Bangladesh: A chemometric review

Heavy metal(loid)s inputs contribute to human and environmental stresses in the coastal zones of Bangladesh. Several studies have been conducted on metal(loid)s pollution in sediment, soil, and water in the coastal zones. However, they are sporadic, and no attempt has been made in coastal zones from the standpoint of chemometric review. The current work aims to provide a chemometric assessment of the pollution trend of metal(loid)s, namely arsenic (As), chromium (Cr), cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) in sediments, soils, and water across the coastal zones from 2015 to 2022. The findings showed that 45.7, 15.2, and 39.1 % of studies on heavy metal(loid)s were concentrated in the eastern, central, and western zones of coastal Bangladesh. The obtained data were further modeled using chemometric approaches, such as the contamination factor, pollution load index, geoaccumulation index, degree of contamination, Nemerow's pollution index, and ecological risk index. The results revealed that metal(loid)s, primarily Cd, have severely polluted the sediments (contamination factor, CF = 5.20) and soils (CF = 9.35) of coastal regions. Water was moderately polluted (Nemerow's pollution index, P_N=5.22 ± 6.26) in the coastal area. The eastern zone was the most polluted compared to other zones, except for a few observations in the central zone. The overall ecological risks posed by metal(loid)s highlighted the significant ecological risk in sediments (ecological risk index, RI = 123.50) and soils (RI = 238.93) along the eastern coast. The coastal zone may have higher pollution levels due to the proximity of industrial effluent, residential sewage discharge, agricultural activities, sea transport, metallurgical industries, shipbreaking and recycling operations, and seaport activities, which are the major sources of metal(loid)s. This study will provide useful information to the relevant authorities and serve as the foundation for future management and policy decisions to reduce metal(loid) pollution in the coastal zones of southern Bangladesh.

Trace metal exposure and human health consequences through consumption of market-available Oreochromis niloticus (L.) in Bangladesh

Using Oreochromis niloticus (L.), commonly known as tilapia, as a model, this study evaluated the exposure of trace metal and their risk assessment on human health. In addition, the status of amino acids, fatty acids, vital elements, and their benefits is also studied. Estimating the nutrient composition of fish muscle is necessary to ensure that it meets the requirements for human health, food regulations, and commercial specifications. The species examined contained appreciable concentrations of amino acids, fatty acid content, and minerals, suggesting that the fish species could be a good source of protein, fat, and minerals. Hazardous heavy metals were found to be lower compared to their corresponding maximum tolerable limits. The order of trace metals is Zn (22,709 µg/kg) > Fe (19,878 µg/kg) > Cu (1261 µg /kg) > Mn (1228 µg/kg) > Cr (474 µg/kg) > Ni (152 µg/kg) As (318 µg /kg) > Pb (281 µg/kg) > Co (24 µg /kg) > Cd (13 µg/kg) > Hg (5 µg/kg); a number of health-related indices, including estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI), as well as carcinogenic risk (CR) indices for adult and children, were calculated to evaluate the human health hazard of the heavy metals. The THQ and HI of heavy metals for tilapia are lower than 1, posing a non-carcinogenic threat to human health due to the biomagnifications of these deadly poisonous metals. Principal component, cluster, and correlation analyses delineated the common probabilistic sources of metal contamination origin and significant inter-parameter associations. Although no human health risks for the consumption of tilapia was found, more attention must be paid for the monitoring of Oreochromis niloticus before entering the market.

Spatial distribution, water quality, human health risk assessment, and origin of heavy metals in groundwater and seawater around the ship-breaking area of Bangladesh

The concentrations of eleven heavy metals (Pb, Cd, Cr, Fe, Mn, Zn, Cu, Ni, Co, As, and Ag) were assessed in both groundwater and seawater collected from the ship-breaking industrial area of Bangladesh using an atomic absorption spectrometer. The investigation aimed to estimate the water quality and pollution level employing several indices, and its associated health risks for the first time in that area. This study found that Cd, Cr, Fe, Pb, Mn, and Ni were higher in both groundwater and seawater compared with WHO standards. Based on the WQI (water quality index) and EWQI (entropy water quality index) classifications, the quality of most of the groundwater is extremely poor or unsuitable for drinking purposes. Furthermore, the HPI (heavy metal pollution index), HEI (heavy metal evaluation index), and CD (degree of contamination) values of most groundwater and all seawater samples exhibit a higher degree of pollution. In addition, the results of NI (Nemerow pollution index) come to an end that both groundwater and seawater in the study area are mostly polluted by Fe, Mn, Pb, Cr, and Cd. Although the HI (hazard quotient index) values of almost all studied heavy metals in both cases of adults and children are within the safe limit, the HI value of Cr for an adult is near the threshold limit and the maximum HI value of Cr for children exceeds this limit. The carcinogenic risk reveals that Cr, Pb, As, and Cd produce detrimental effects on local people through the direct ingestion of groundwater. The pollution source is identified using principal component analysis and a Pearson correlation matrix as being primarily anthropogenic and attributed to intensive ship-breaking activities or other industries in the area.

Assessment of Metal Contamination in Water of Freshwater Aquaculture Farms from a South Asian Tropical Coastal Area

Heavy metal accumulation in aquaculture farms has become a major problem due to the widespread use of artificial feed to enhance fish productivity. To estimate the contamination level and identify metal sources, we investigated the amounts of seven heavy metals (Cu, Zn, Pb, Cd, Cr, Ni, and Mn) in the surface water of commercial fresh water aquaculture farms in a south Asian tropical coastal area. Atomic absorption spectrometry (AAS) was used to analyze 36 water samples from 12 commercial fish farms. The results demonstrated that the range of three heavy metals were detected in a decreasing order of Mn (0.0574−0.4100 mg.L−1) > Zn (0.0125−0.3250 mg.L−1) > Cu (0.0275−0.085 mg.L−1). In all samples, the remaining four heavy metals (Pb, Cd, Cr, and Ni) were below the detectable level (BDL). Except for Mn, the amounts of the metals examined were below WHO and USEPA guideline values. According to the findings, the levels were found to be safe for drinking, agriculture production, and aquaculture. There was no significant correlation (p > 0.05) between heavy metal concentrations and water quality parameters, indicating that pollution came from diverse sources and that no single factor was controlling their levels. Furthermore, Analysis of Variance (ANOVA) revealed no significant differences in the mean metal values among the fish farms (p > 0.05). Multivariate analyses (CA and PCA) demonstrated the association and sources of metal in the study area. Although metal levels were not beyond the threshold limit, it is recommended that suitable measures and continuous monitoring should be undertaken to reduce heavy metal pollution in aquaculture farms and prevent water quality degradation.