Toxic metal pollution and ecological risk assessment in water and sediment at ship breaking sites in the Bay of Bengal Coast, Bangladesh

Impact of shipbreaking industries on the Sitakunda coastal environment, Chattogram by analyzing water quality parameters

Shipbreaking is an extremely profitable business; however, it simultaneously destroys the surrounding environment. The discharge of toxic chemicals and materials containing wastes is contaminating surrounding water. However, there is still no sufficient published information particularly focusing on shipbreaking yard (SBY) water quality. Therefore, this research was carried out by questionnaire survey among the workers following simple random sampling and purposive simple random sampling for water samples collection from SBY. Results showed that young energetic, experienced and courageous workers (20-35 years) generally work in SBY. Most of the workers are illiterate except for a few graduate officials. The workers are provided in-yard small-scale treatment facilities for injuries which is not sufficient. The tested water parameters were as turbidity (276-640 JTU), pH (6.3-6.7) and EC (1850-3636 μs/cm), while TSS (1925-4005), TDS (921-2150), chloride (543-1023), ferrous (1.4-34), DO (5.3-6.5), BOD (4.3-7.3), oil (30-7375), NH3 (0.75-2.27), lead (55-107), copper (29-58), cadmium (0.2-0.7), mercury (0.01-0.12), zinc (71-128), chromium (18-107) and arsenic (0.02-5.3) in mg/l unit in SBY. These findings indicate the potential water contamination by shipbreaking activities. Statistical analysis showed big F-value with small p-value in all studied water parameters, indicating significantly different. In addition, the water parameters in most of the sampling points in SBY crossed the Department of Environment (DoE) standards. Therefore, regular monitoring of DoE and strengthened government regulations with sufficient technical support to shipbreaking industries are recommended for mitigating water pollution and protecting the surrounding ecosystem.

Exploration and impact of Metlaoui-Gafsa phosphate rock amendment: the role of Serratia plymuthica BMA1 in phosphate solubilization, heavy metal rhizoaccumulation, and enhanced nutrition in Vicia faba L

The geochemical analysis of Gafsa rock phosphate (GRP) revealed relatively high concentrations of essential plant minerals and trace heavy metals (HMs). Environmental contamination factors indicated moderate to very strong HM contamination due to GRP soil amendment. The potential use of the Serratia plymuthica BMA1 strain, which is known for its ability to solubilize GRP, to enhance mineral nutrition in Vicia faba L. and its role in HM rhizoaccumulation from GRP were explored. Pot experiments revealed that bacterization with S. plymuthica BMA1 in V. faba grown in sand supplemented with GRP as the sole source of phosphorus significantly increased the potassium concentration by 64% in roots and 40% in shoots, iron by 20% in roots and 10% in shoots, and manganese by 27% in roots and 20% in shoots compared to that in V. faba not inoculated with S. plymuthica BMA1. The total dry biomass of V. faba increased by approximately 85%, while the accumulation of cadmium (Cd), copper (Cu), zinc (Zn), and lead (Pb) in the roots increased by 114%, 30%, 37%, and 44%, respectively. However, in the shoots, they increased by 35%, 10%, 85%, and 25%, respectively, for Cd, Cu, Zn, and Pb compared to those in the non-inoculated V. faba. The evaluation of the HM translocation factor, bioaccumulation factor, and bioconcentration factor with GRP highlighted the key role of S. plymuthica BMA1 in preventing the mobility of toxic HMs from reaching the aerial parts of plants. These findings suggest that S. plymuthica BMA1 has the potential to enhance mineral nutrition in V. faba and facilitate the rhizoaccumulation of toxic HMs, which has implications for plant cultivation and human consumption.

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.

Impact of anthropogenic activities and the associated heavy metal pollution in Sundarbans waterways: threats to commercial fish and human health

The exposure of fish to heavy metals is a significant concern for human health and natural ecosystems. Despite being a critical issue, the extent of contamination in tropical fish from developing countries like Bangladesh remains somewhat unexplored. In this study, ten economically vital fish species (Osteogeneiosus militaris, Arius gagora, Harpadon nehereus, Mugil ephalus, Pseudapocryptes elongates, Apocryptes bato, Labeo bata, Tenualosa toil, Notopterus notopterus, and Pampus chinensis) from the Pasur River, Bangladesh, were analyzed by atomic absorption spectrometer for the concentrations of four concerned heavy metals, viz., As, Cr, Cd, and Pb, and the associated human health risks. The mean concentrations (mg/kg) followed the order of As (3.30 ± 1.43) > Pb (2.32 ± 0.73) > Cr (0.63 ± 0.29) > Cd (0.37 ± 0.24). Additionally, the bioaccumulation factor of the metals in the investigated fish species followed a decreasing trend of As (824.75) > Cr (781.25) > Cd (744) > Pb (385.83). While most species fell below the minimum bioaccumulation line, a few exceptions were noted for some species specific to metals. Health risk assessments indicated no significant carcinogenic and non-carcinogenic risks for both children and adults, although children exhibited greater vulnerability to both types of health effects. Multivariate analysis and local perceptions supported the conclusion that heavy metals primarily originated from anthropogenic sources related to development activities adjacent to the riverine areas.

A Copula-based spatiotemporal probabilistic model for heavy metal pollution incidents in drinking water sources

Water pollution incidents pose a significant threat to the safety of drinking water supplies and directly impact the quality of life of the residents when multiple pollutants contaminate drinking water sources. The majority of drinking water sources in China are derived from rivers and lakes that are often significantly impacted by water pollution incidents. To tackle the internal mechanisms between water quality and quantity, in this study, a Copula-based spatiotemporal probabilistic model for drinking water sources at the watershed scale is proposed. A spatiotemporal distribution simulation model was constructed to predict the spatiotemporal variations for water discharge and pollution to each drinking water source. This method was then applied to the joint probabilistic assessment for the entire Yangtze River downstream watershed in Nanjing City. The results demonstrated a significant negative correlation between water discharge and pollutant concentration following a water emergency. The water quantity-quality joint probability distribution reached the highest value (0.8523) after 14 hours of exposure during the flood season, much higher than it was (0.4460) during the dry season. As for the Yangtze River downstream watershed, five key risk sources (N1-N5) and two high-exposure drinking water sources (W3-W4; AEI=1) should be paid more attention. Overall, this research highlights a comprehensive mode between water quantity and quality for drinking water sources to cope with accidental water pollution.

Heavy Metals Assessment and Health Risk to Consumers of Two Commercial Fish Species from Polyculture Fishponds in El-Sharkia and Kafr El-Sheikh, Egypt: Physiological and Biochemical Study

Metal pollution is a major environmental concern worldwide, especially in Egypt. The aquaculture industry uses widespread artificial feeds to stimulate fish production, leading to metal accumulation in the aquatic environment. Heavy metal concentrations (HMCs) in sediments, water, and tissues were studied to study the effect of pollution levels on heamatological, and biochemical, immunological aspects of farmed fish as well as on human health. Results declared that the HMC levels in the water and sediment were significantly different between El-Sharkia and Kafr El-Sheikh fishponds (T-test, p < 0.05). This was supported by the metal pollution index in the water and sediment, indicating that El-Sharkia fishponds (ES fishponds) were more contaminated than Kafr El-Sheikh fishponds (KES fishponds). Also, HMCs in fish tissues were significantly increased in fish cultivated in ES fishponds than in KES fishponds. Haematological, immunological, and biochemical alterations of Bolti (Oreochromis niloticus) and Topara (Chelon ramada) fish were significantly different within the different fish species as well as the different fishponds. From the human health perspective, the THQ-HMC and HI-HMC associated with the consumption of muscle suggest a safe non-carcinogenic risk to human health. In contrast, cadmium poses a cancer risk to children who consume the muscular tissue of Bolti fish from ES fishponds, which should be regarded as a warning sign based on data indices and a human health perspective. In order to minimise HMC pollution in the aquaculture sector, it is advisable to take possible assessments and carry out continuous monitoring considering international WHO/FAO assessments.

Metal pollution assessment in the surface sediments of a river system in Türkiye: Integrating toxicological risk assessment and source identification

This study investigates potentially toxic elements (PTEs) in the surface sediments of the Abdal River system, a critical water source for Samsun province, Türkiye, due to the presence of the Çakmak Dam. PTE concentrations, measured in mg/kg, show significant variability: Hg (0.03) < Cd (0.26) < As (10.98) < Pb (13.88) < Cu (48.61) < Ni (62.45) < Zn (70.97) < Cr (96.28) < Mn (1015) < Fe (38357). Seasonal variations were observed, in particular increased concentrations of As, Cd and Pb in summer (p < 0.05). Contamination and ecological risk indices (mHQ, EF, Igeo, CF, PLI, Eri, mCd, NPI, PERI, MPI, and TRI) indicate moderate to low levels of contamination, suggesting potential ecological effects. Health risk assessments suggest minimal risks to human health from sediment PTEs. Statistical analyses (PCC, PCA and HCA) improve the understanding of the sediment environment and contamination sources, while the coefficient of variation assists in source identification.

Appraisal of metallic accumulation in the surface sediment of a fish breeding dam in Türkiye: A stochastical approach to ecotoxicological risk assessment

This study examines the levels and patterns of potentially toxic elements (PTEs) in surface sediment of Almus Dam Lake (ADL), a key fish breeding site in Türkiye. PTE concentrations in sediment were ranked: Hg (0.05 ± 0.01) < Cd (0.16 ± 0.01) < Pb (9.34 ± 1.42) < As (18.75 ± 15.65) < Cu (63.30 ± 15.17) < Ni (72.64 ± 20.54) < Zn (86.66 ± 11.95) < Cr (108.35 ± 36.40) < Mn (1008 ± 151) < Fe (53,998 ± 6468), with no significant seasonal or spatial differences. Ecological risk indices (mHQ, EF, Igeo, CF, PLI, Eri, mCd, NPI, PERI, MPI, and TRI) showed low contamination levels. Health risk assessments, including LCR, HQ, and THI, indicated minimal risks to humans from sediment PTEs. Statistical analyses (PCA, HCA, SCC) identified natural, transportation, and anthropogenic PTE sources, with slight impacts from agriculture and fish farming. This research underlines contamination status of ADL and emphasizes the need for targeted management strategies, offering critical insights for environmental safeguarding.

Spatial distribution and pollution assessment of metals in sediments along the industrialized coast of East Java, Indonesia

The eastern coastline of Gresik, located in East Java, Indonesia, experienced significant industrialization, leading to the development of numerous diverse sectors. These diverse industrial activities, in addition to other human activities, result in the contamination of sediment across the eastern coast of Gresik with a variety of metals. Metals like arsenic (As), cadmium (Cd), copper (Cu), and zinc (Zn) have exceeded the international standards for sediment quality, potentially causing significant harm to the aquatic ecosystem in this coastal region. The results of the multivariate analysis indicate that the metals found in the sediment are related to a combination of anthropogenic inputs, specifically those originating from industrial effluents in the area under study. Based on the assessment of enrichment factor, contamination factor, geo-accumulation index, degree of contamination, ecological risk index, and pollution load index, it can be concluded that the metals examined displayed different degrees of sediment contamination, ranging from minimal to severely contaminated.

Geospatial quality assessment of locally available ice for heavy metals and metalloids and their potential risks for human health in Karachi, Pakistan

Extreme hot conditions during summers, high poverty rate and continuous electricity load shedding affect commercial manufacturing and sale of ice in many countries. The vendors prepared ice using untreated piped water, tanker water and ground water. These waters may contain hazardous pollutants and ice made from them will pose a potential human health risk. Thus, it is important to regularly monitor the chemical composition of water sources and the quality of the manufactured ice. A contemporary examination was carried out to evaluate the physico-chemical properties and heavy metals and metalloids in the ice sold in all the districts of Karachi, Pakistan. This pioneering study was an innovative effort to assess the ice quality in relation to potential pollutant hazards to human health; with concomitant geospatial information. The geospatial distribution of ice quality and major constituents were among the measured parameters; carefully associated with further geospatial information, determined using GIS (Geographic Information Systems) and PCA (Principal Component Analysis) techniques. Interestingly, the physico-chemical analyses revealed that the ice quality was marginally adequate and the total mean metal-metalloid contents were in the sequence of Pb > Ni > Zn > Fe > Cr > As. The concentrations of these metals were above the upper allowable limits with reference to the recommended WHO guidelines. We observed that 57.1% and 35.7% ice samples had good physico-chemical properties assessed using the Ice Quality Index (IQI). Conversely, the IQI for metals showed that the ice was unsafe for human consumption. In terms of health risk assessment, the overall mean CDI (Chronic Daily Intake) and HQ (Hazard Quotient) values were in the order of Pb () > Ni (3.2) > Zn (2.3) > Fe (2.1) > Cr (1.6) > As (0.5) and Pb (7.4) > As (1.7) > Cr (0.5) > Ni (0.4 > Zn (0.008) > Fe (0.003), respectively. This study highlighted that routine monitoring of the water supplies available for making ice is required to protect public health.

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.

Uncovering the impact of mega-scale shipbreaking yards on soil and crop quality in Bangladesh: A spatiotemporal dynamics and associated health risks of metal/loid contamination

The uncontrolled release of harmful metal/loids from mega-scale shipbreaking activities in Bangladesh is a significant concern. This study investigated the impact of shipbreaking activities on soil and crop quality and human health in relation to metal/loid contamination. This work covered an area of 1221 km2 surrounding the shipbreaking yards in Chittagong during the wet and dry seasons between 2019 and 2020. Amongst the sixteen elements measured, the concentrations of Pb, Cd, As, V, Cr, Mn, Cu, Zn, Fe, Co, Ni, and Sn in the soil, rice, and vegetables from the four exposure sites were significantly higher compared to the control site in both seasons. Soil pollution indices indicated moderate to higher contamination levels of Pb, Zn, Cd, As, and Se in 30-50% of soil, supporting their accumulation in food crops. Source apportionment analysis identified uncontrolled shipwrecking operations as the primary anthropogenic activity mainly contributing to metal/loid pollution. Health risk analysis showed inorganic arsenic (estimated), Cd, and Pb in food crops could pose potential health threats to the general population. Spinach leaf and gourd were identified as the highest-risk contributing vegetables in the dry and wet seasons. These findings help to inform management strategies to protect agroecosystems and public health.

Trace element levels in the muscles of three tern species (Aves: Laridae) from the western Arabian Gulf: environmental assessment and implications for conservation

In the Arabian Gulf (called also Persian Gulf; hereafter 'the Gulf'), Jana and Karan Islands are recognized as one of the most Important Bird Areas in the region. Many migratory breeding seabirds, like the Greater Crested Tern Thalasseus bergii, White-cheeked Tern Sterna repressa and Bridled Tern Onychoprion anaethetus, depend on these islands during the breeding season. However, these aquatic wildlife species are suffering from intensified urban and industrial coastal development and various contamination events including wars and related oil spills. In this study, we used these three piscivorous top predator birds to analyse the levels of 19 trace elements (TEs; i.e. Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sr, V and Zn) in 15 muscular tissue samples from Jana and Karan Islands. PERMANOVA analysis showed no difference in contamination profile between sites nor between species probably due to their spatial and ecological proximity and therefore similar levels of exposure to TEs. Comparing these levels with existing literature, our results showed no particular concern for all elements, except for Al (maximum values recorded = 116.5 µg g-1 d.w.) and, in two samples, Ba (33.67 µg g-1 d.w.) and Pb (5.6 µg g-1 d.w.). The results can be considered as an initial step for supplementary evaluations with a larger number of samples and specified time intervals for the collection of specimens. This study provided baseline information on the pollution status of these two ecologically important sites which require a continuous biomonitoring programme.

Toxicity risks associated with heavy metals to fish species in the Transboundary River - Linked Ramsar Conservation Site of Tanguar Haor, Bangladesh

The presence of trace metals in aquatic ecosystems can have detrimental effects on fish survival. The Tanguar haor, a Ramsar conservation wetland, receives sediment and water from multiple transboundary rivers. However, there have been limited studies on the metal concentrations in fish species in this sediment-rich wetland. This study aimed to analyze the concentrations of iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in water, sediment, and fish tissues. Higher concentrations of Cd and Pb were found in the water and sediment. All these metals were detected in eight fish species, including benthic and pelagic species. Among them, Systomus sarana, a pelagic fish that also consumes benthic organisms, exhibited a higher metal pollution index than other fish, particularly benthic species. The release of higher metal concentrations from sediment into the water has the potential to impact the accumulation of metals in fish. SYNOPSIS: This study on metal concentrations in fish species will aid policymaking on ecotoxicology research for transboundary river-connected wetlands.

Managing the invisible threat of microplastics in marine ecosystems: Lessons from coast of the Bay of Bengal

Invisible microplastics (MP) have become a significant problem worldwide in recent years. Although many studies have highlighted the sources, effects, and fate of MPs pollution on various ecosystems in developed countries, there is limited information on MPs in the marine ecosystem along the northeastern coast of the Bay of Bengal (BoB). Coastal ecosystems along the BoB coasts are critical to a biodiverse ecology that supports human survival and resource extraction. However, the multi-environmental hotspots, ecotoxicity effects, transport mechanisms, fates, and intervention measures to control MP pollution initiatives along the BoB coasts have received little attention. Therefore, this review aims to highlight the multi-environmental hotspots, ecotoxicity effects, sources, fates, and intervention measures of MP in the northeastern BoB to understand how MP spreads in the nearshore marine ecosystem. This study critically evaluates the hotspots and ecotoxic effects of pollution from MP on the coastal multi-environment, e.g., soil, sediment, salt, water, and fish, as well as current intervention measures and additional mitigation recommendations. This study identified the northeastern part of the BoB as a hotspot for MP. In addition, the transport mechanisms and fate of MP in different environmental compartments are highlighted, as are research gaps and potential future research areas. Research on the ecotoxic effects of MP on BoB marine ecosystems must be a top priority, given the increasing use of plastics and the presence of significant marine products worldwide. The knowledge gained from this study would inform decision-makers and stakeholders in a way that could reduce the impact of the legacy of micro- and nanoplastics in the area. This study also proposes structural and non-structural measures to mitigate the effects of MPs and promote sustainable management.

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.

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.

Differences in bacterial community composition, structure and function between sediments in waterways and non-navigable channels in a plain river network area

Bacterial communities greatly help maintain the balance of river ecosystems and are highly sensitive to changes in environmental conditions. Plain river network areas (PRNs) are characterized by dense river networks, low-lying terrain, and slow water flow, where the bottom sediment is frequently disturbed by ship navigation due to the limited water depth and width of waterways, providing a unique ecological niche for bacterial growth. Hence, understanding how bacterial communities in PRNs respond to changes in hydrodynamic conditions, physicochemical parameters, and pollutants under ship navigation is essential to maintaining the stability of inland waterway ecosystems. The Taihu Lake Basin, a typical PRN, was selected to explore the differences in bacterial community composition, structure and function between sediments in waterways (WS) and non-navigable channels (NS). The results indicate that the sediment from NS possessed more diverse and complex bacterial communities than WS. NMDS and ANOSIM analyses further verified the significant differences in bacterial community structure between WS and NS. Combined with LEfSe, we observed the highly differential taxonomy between WS and NS from phylum to order. Moreover, a comparison of beta diversity dissimilarity indices revealed that although species replacement dominated both the WS and NS beta-diversity patterns, species loss caused the differences in the overall beta diversity between them. Variance partitioning analysis revealed that physicochemical parameters (clay content, pH, ORP, and others) and ship traffic volume (STV) were the main driving factors for bacterial community distribution between WS and NS, while pollutants (heavy metals, perfluoroalkyl acids, and others) had a relatively minor influence. PICRUSt2 analysis revealed that the changes in pH, ORP, and STV under ship navigation might inhibit the bacterial ability to metabolize carbohydrates. The results reveal the comprehensive effects of ship navigation disturbance on sediment bacterial communities in the PRN and contribute to further understanding of inland waterway ecosystems.

Evidence that offshore wind farms might affect marine sediment quality and microbial communities

Offshore wind power is a typical example of clean energy production and plays a critical role in achieving carbon neutrality. Offshore wind farms can have an impact on the marine environment, especially sedimentary environments, but their influence on sediments remain largely unknown. This study, which uses the control-impact principle to define different areas, investigated the characteristics of marine sediments under the Putidao offshore wind farm in Bohai Bay, China. We used chemical and microbiological observations to evaluate sediment quality and microbial community structure. According to both the geo-accumulation index (I_geo) and contamination factor (CF) indexes, copper, chromium and zinc were the major contaminants in the offshore wind farm sediments. The pollution load index (PLI) index showed that the various sites on the wind farm were only lightly polluted compared with baseline values. Closer to the wind farm's center, the metal concentrations started to rise. The physicochemical features of the sediments could better explain changes in the microorganisms present, and screening the microbiomes showed a correlation with heavy metal levels, linking the relative abundance of microorganisms to the sediment quality index. This comprehensive study fills a knowledge gap in China and adds to our understanding of how to assess the sedimentary environments of offshore wind farms.

Trace metals in urbanized coasts: The central Atlantic of Morocco as a case study

This study describes the contamination, accumulation, and ecological risk assessment of five trace metals (Cd, Pb, Cu, Zn, and Cr) in sediments of an urbanized beach in the central Atlantic coastline of Morocco. The two-year investigation (2018 and 2019) included six sampling sites along a 6 km coastal reach. In both years, none of the studied trace metals exceeded the background or the sediment quality guidelines (SQGs). The eco-toxicological indices revealed low degree of contamination, unpolluted ecosystem, and low ecological risk of metals. However, Cd exceeded the background value and some SQGs following the increase of anthropogenic activities in 2019. Likewise, it indicated unpolluted to moderately polluted sediment as well as moderate ecological risk. Overall, it is highly recommended to mitigate the avoidable anthropogenic activities (marine litter generation, sewage discharge, intense urbanization, and vehicle traffic on the beach) that lead to the elevation of metal pollution in the study area.

Effects of shipwrecks on spatiotemporal dynamics of metal/loids in sediments and seafood safety in the Bay of Bengal

Metal/loid pollution from shipwrecking activities has drawn significant concern due to their persistent threat to the marine ecosystem and human health. We investigated the spatiotemporal distribution, pollution characteristics, risks, sources, and potential impact of metal/loids in the sediments and seafood in the Bay of Bengal at nearby open beaching shipwrecking yards in Bangladesh. We collected 78 sediments and 208 seafood samples from the exposed and control sites from 2018 to 2020 during the dry and wet seasons. The concentrations of 16 elements, including cadmium, arsenic, lead, chromium, manganese, copper, zinc, iron, tin, antimony, nickel, cobalt, molybdenum, vanadium, selenium, and thallium were measured using validated inductively coupled plasma-mass spectrometry (ICP-MS) methods. Based on the pollution indices (enrichment factor, geoaccumulation index, pollution index, and pollution load index), lead, arsenic, cadmium, selenium, copper, zinc, and tin from the dry season showed higher contaminations compared to the wet and their concentrations were increased from 2018 to 2020 with seasonal fluctuations. Sediment cadmium and arsenic posed relatively higher and moderate ecological risks. Health risk analysis indicated that lead, cadmium, and inorganic arsenic (estimated) in seafood species pose a possible health threat to the general population. Further, there were possible ecological and health risks for the metal/loids in combination based on the ecological risk index in sediment and the hazard index in seafood, respectively. Source apportionment suggested that anthropogenic activities through uncontrolled shipwrecking operations over the last four decades were the largest polluting dominator, contributing 55-77% of the metal/loid concentrations. Therefore, the data may inform mitigation strategies for emission control at the shipwrecking yards to protect marine ecosystems and their local population.

Spatial distribution and pollution assessment of heavy metals in sediments from the Brahmaputra River watershed in Bangladesh

Spatial distribution and pollution assessment of selected heavy metals such as barium (Ba), chromium (Cr), nickel (Ni), lead (Pb), vanadium (V), arsenic (As), zinc (Zn), and copper (Cu) in sediments of the Brahmaputra River watershed in Bangladesh was investigated. The mean abundances (ppm) of heavy metals in sediment samples were in decreasing order Ba (375.60) > V (67.60) > Cr (54.10) > Zn (48.20) > Ni (22.28) > Pb (20.25) > Cu (7.59) > As (4.21). Concentrations of Pb and As in the sediments are enriched relative to the average upper continental crust composition, while Ba, V, Cr, Zn, Ni, and Cu decrease considerably. A higher concentration of Pb and Ni indicates that Brahmaputra River watershed samples receive a significant contribution from anthropogenic sources of heavy metals. Chromium displays marked positive correlation with V (r = 0.91, p =  < 0.01), inferring a similar source materials input into the watershed. The geo-accumulation index (Igeo) values suggest that the sediments were uncontaminated to moderately contaminated by Ni, Zn, Pb, V, and Cr, whereas moderate to heavily contaminated by As and Cu. The contamination factor (CF) confirmed that sediments in the watershed were moderate to highly contaminated by As, Cu, and Cr. The pollution load index (PLI) values for most of the samples were over one (> 1), indicating an advanced decline in the watershed sediment quality. The overall results of a multivariate statistical analysis suggest that Ba, V, Cr, and Zn contents were all-natural sources, and Pb, Ni, As, and Cu were derived from both natural and anthropogenic sources.

Potentially hazardous metals in the sediment of a subtropical bay in South China: Spatial variability, contamination assessment and source apportionment

Potentially hazardous metals (PHMs) in the coastal environment have become a great concern due to their easy bioaccumulation, poor biodegradability and high toxicity. Surface sediment samples were collected in a subtropical bay in South China to analyse the spatial variations, contamination level and potential sources of PHMs. The results indicated that the order of average contents of PHMs in Qinzhou Bay sediment was Zn > Pb > Cr > Cu > As > Hg > Cd. The most important potential ecological risk factor was Hg pollution in the Qinzhou Bay sediments. The positive matrix factorization (PMF) model results indicated that Cu, Pb, Zn, Cd and Cr mainly originated from natural sources while Hg and As were related to coal fired industrial inputs and petroleum production activities. The results could provide a basis for marine management to formulate relevant pollution prevention and control measures.

Assessment of anthropogenic metals in shipyard sediment in the Amazon delta estuary in northern Brazil

Shipyard activities have contributed to the release of anthropogenic metals in sediment in the Amazon delta estuary, but no studies of the issue have been carried out in northern Brazil. This study evaluated the sediment that is under the influence of shipyard activities in the Guajará Bay and in the channel of the Maguari River, in Belém, Pará (PA) state, northern Brazil. Sediment samples were collected in the vicinity of the shipyards, while samples of paint and metal fragments were collected from hulls of abandoned vessels. Metals under analysis were Cu, Zn, Pb, Ni, Cr, Ba, V, Li, Fe and Al. Mean Cu concentrations found in the sediment in two shipyards - 28.3 mg kg^-1 and 41.0 mg kg^-1 - were above the threshold effect level (TEL) for the amphipod Hyalella azteca. The highest concentrations of metals found in paint fragments from abandoned vessels were 29,588 mg kg^-1 Ba, 9,350 mg kg^-1 Zn, 1,097 mg kg^-1 Pb and 548 mg kg^-1 Cr. This fact suggests that vessel abandonment is a major source of contamination in shipyard areas. The principal component analysis (PCA) showed that most metals under study are closely related to sediment contamination in the shipyards. Geoaccumulation index and screening concentrations of inorganic contaminants for metals in freshwater ecosystems confirmed that a shipyard was contaminated by copper. Results may support further studies of contamination and application of waste management to shipyards and vessel graveyards around the world.

Assessment of the effects of COVID-19 lockdown period on groundwater quality of a significant rice land in an urban area of Türkiye

In the current research, the impact of the COVID-19 lockdown period on groundwater quality of Lower Meriç Plain (Thrace Region of Türkiye) was evaluated. Some significant nutrient characteristics (NO₃^-, NO₂^-, and PO₄^3-), salinity characteristics (EC, TDS, and salinity), and physical characteristics (temperature, DO, pH, and turbidity) were investigated in groundwater samples collected from 45 sampling points in pre-lockdown and lockdown periods. Water quality index (WQI) and nutrient pollution index (NPI), Pearson correlation index (PCI), cluster analysis (CA), one-way ANOVA test (OWAT), and factor analysis (FA) were applied to assess ecological risk. Excluding recorded statistical differences in temperature and DO due to climatic conditions (p < 0.05), levels of all the investigated water quality parameters show no statistically significant differences and no significant reduction in pollutants measured in the lockdown period. On the contrary, the WQI and NPI scores have increased between the rates of 4.76-27.10% during the lockdown period. In the lockdown period, although the reduction of industry or limited production of many industrial facilities reduced the inorganic contaminant releases to the environment, ongoing agricultural activities and domestic wastes caused to prevent the reduction of organic pollutants in groundwater of the region during the lockdown period.

Spatial distribution of potentially harmful trace elements and ecological risk assessment in Zhanjiang mangrove wetland, South China

Global mangrove wetlands face increasing anthropogenic impacts along the coast. The Zhanjiang mangrove wetland is the largest and adjacent to the most developed bay area in China. Surface sediments were collected in different plant transit and used for potentially harmful trace elements (PHTEs) measurement. Mean contents of Hg, Cr, Ni, Cu, Zn, As, Cd and Pb were 0.01 mg/kg, 56.16 mg/kg, 10.06 mg/kg, 9.61 mg/kg, 43.58 mg/kg, 8.76 mg/kg, 0.25 mg/kg, 28.12 mg/kg. Most of the PHTEs were slightly enriched but the Cd pollution is significant, and the potential ecological risk is moderate. The risk of the mangrove wetland is larger than the grassland and the farmland. The PCA and PMF indicate Hg, Ni, Cu, Zn, As, and Pb mainly originated from local anthropogenic activities, Cr originated from the natural geological process, and Cd mainly originated from atmospheric deposition of regional industrial pollution. In view of the impact of surrounding industry and agriculture and the signs of PHTEs pollution, it is necessary to implement the wetland protection law more strictly to truly realize the construction of ecological civilization. This provides a valid reference for the wetland conservation and management in coastal cities.

Towards Sustainable Management of Urban Ecological Space: A Zoning Approach Hybridized by Ecosystem Service Value and Ecological Risk Assessment

Massive growth is posing threat to the ecological security and sustainability of cities. Ecosystem service value (ESV) and ecological risk index (ERI) assessment can be conducted to enhance urban ecosystem management through the enhanced recognition of these values and risks in decision-making. This paper aimed to measure spatiotemporal ESV and ERI for Shizuishan City located in central China, and, based on this, how to zone urban ecological space using land cover data (for the years 2010, 2015, and 2020). The management options of different zones were suggested to mitigate and manage any potential negative impacts on urban ecological security. Results show that: (1) The spatial distribution characteristic of ESV is “high in the south and low in the north”. The total ESV exhibited an upward tendency from 2010 to 2020. (2) The high-ERI areas were distributed in the peripheral region, while the low-ERI areas were concentrated in the central region. The ERI of water was in decline continuously, whereas the ERI of wetland maintained a high level. (3) The zoning approach integrating ESV and ERI assessment can truly reflect the status of the environment and better clarify the direction of ecological development for different areas. Among four different ecological zones, the high-ESV and low-ERI areas (I) have abundant ecological resources, and they are set as “Priority Development Areas”. The low-ESV and low-ERI areas (II) are set as “Ecological Improvement Areas” because the area of ecological lands are confined. The low-ESV and high-ERI areas (III) have a fragile ecological environment, and they are set as “Exploitation-Prohibited Areas”. The high-ESV and high-ERI areas (IV) are mainly distributed near water and wetland, and they are set as “Research-focused Areas”.

Seasonal behavior and accumulation of some toxic metals in commercial fishes from Kirtankhola tidal river of Bangladesh - A health risk taxation

Contamination of fish with heavy metals (Heavy metals) is one of the most severe environmental and human health issues. However, the contamination levels in tropical fishes from Bangladesh are still unknown. To this end, the evaluated concentrations of arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in 12 different commercially important fish species (Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Glossogobius giuris, Pseudeutropius atherinoides, Polynemus paradiseus, Sillaginopsis panijus, Corica soborna, Amblypharyngodon mola, Trichogaster fasciata, and Wallago attu) were collected from the Kirtankhola River assess human health risk for the consumers, both in the summer and winter seasons. Toxic metals surpassed the acceptable international limits in P. atherinoides, P. paradiseus, S. panijus, C. soborna, and W. attu. The target hazard quotient (THQ) revealed that non-carcinogenic health effects (HI < 1) for children and adults, and the carcinogenic risk (CR) indicated safety. Results show that children are more susceptible to carcinogenic and non-carcinogenic hazards from higher As. The multivariate analysis justified that heavy metals were from anthropogenic actions. The lessening of toxic metals might need strict rules and regulations as metal enrichment would continue to increase in this tidal river from both the anthropogenic and natural sources.