Ni In Sediments Research Articles

Pharmaceuticals and personal care products and heavy metals in the Ganga River, India: Distribution, ecological and human health risk assessment

In the present study, pharmaceuticals and personal care products (PPCPs), endocrine disrupting compounds (EDCs), and heavy metals (HMs), were measured in water and sediment of the Ganga River during summer and winter seasons for two consecutive years. Additionally, this study estimated the ecological and human health risks associated with PPCPs, EDCs, and HMs. HMs detected in the range of not detected (n.d.) to 23.59 μg/L and 0.01–391.44 μg/g in water and sediment samples, respectively. All studied HMs were within the permissible limits, except for As in water, and Cr and Ni in sediment. The geo-accumulation index (Igeo) indicated that Cr (0.71–5.98) and Pb (0.90–3.90) had high Igeo compared to other metals in sediment samples. Pb showed the highest ecological risk, followed by Cd, Co, Ni, Cu, Cr, As, and Zn. The maximum potential ecological risk index was observed at site G8. The hazard index (HI) value for water (0.08–0.89) and sediment (0.02–0.29) intake by adults remained within the acceptable limits, except at sites G8 (1.27) and G9 (1.34) for water intake. However, for children, the HI value was above the acceptable limit for water intake at sites G4 to G13 and for sediment at site G8. Among the studied compounds, metformin, triclosan, triclocarban, diclofenac, and methylparaben were the most abundant compounds present in the Ganga River. PPCPs and EDCs detected in the range of n.d. to 5850.04 ng/L and n.d. to 1080.41 ng/g in water and sediment samples, respectively. The environmental risk assessment identifies the maximum ecological risk in water exhibited by triclocarban followed by 17α-ethinylestradiol (EE2), diclofenac, and triclosan, while in sediment, the maximum ecological risk exhibited by triclocarban, followed by EE2, 17 β-estradiol (E2), triclosan, and diclofenac. However, none of the compounds showed human health risk, except for EE2, E2, and atenolol.

Connectivity of Geochemical Composition of Sediments and Soils in the Large Urban River Catchment

ABSTRACT This article aimed to identify sources and transport pathways of macro- and microelements in large urbanized rivers under significant anthropogenic pressure. To achieve the objective of this study, the geochemical characteristics of the sediments of the Sava and Danube Rivers and the soils flooded by the Kolubara River were determined. The high content of Mg indicates the dominant origin of the material from loess deposits. The significantly higher contents of Cr and Ni in sediment and soil samples from the Obrenovački Zabran (OZ) than in the samples from the Veliko Ratno Ostrvo (VRO) are the result of increased anthropogenic pressure. Sediments from the VRO show increased Sn and Sb contents. The increase in the content of chalcophile elements is the highest in the sediments from the OZ and ranges from 1.8 to 2.7 times, compared to their concentrations in the Earth’s crust. The soils from OZ and the sediments from the VRO show a decrease in the content of chalcophile elements compared to the sediments from the OZ so the increase is 1.2–1.5, and 0.9–2.3 times, respectively compared to the Earth’s crust. The obtained results revealed that the yield of sedimentary material that has higher concentrations of microelements decreases already at a distance of several km.

Spatial Distribution, Risk Index, and Correlation of Heavy Metals in the Chuhe River (Yangtze Tributary): Preliminary Research Analysis of Surface Water and Sediment Contamination

This comprehensive study aimed to evaluate the water quality and sediment contamination in the Chuhe River in Nanjing. The spatial assessment of 10 samples collected in September highlighted that, in surface water, Copper (Cu) > Nickel (Ni) > Zinc (Zn) > Chromium (Cr) > Lead (Pb) > Arsenic (As) > Cadmium (Cd) > Mercury (Hg), whereas in sediments, Zn > Cr > Cu > Pb > Ni > As > Cd > Hg. The coefficient of variation (CV) for Ni and Zn in surface water was >15, whereas As, Cu, Pb, and Ni had a CV that was higher than 15 in sediments, indicating variability in contamination sources. The Pollution Load Index values ranged between 2.16 and 3.05, reflecting varying contamination levels across samples. The Geoaccumulation Index data also showed moderate-to-considerable contamination, especially for elements such as Cd and Cu. Correlation analyses in water and sediments unearthed significant relationships, with notable links between Cu and Pb in the water and strong correlations between As and Cu and between Cr and Ni in sediments. In sediments, Total Nitrogen and Phosphorus were significantly correlated with As, Cu, Pb, and Ni. The Potential Ecological Response Index for sediments indicated that they are at medium to high risk (307.47 ± 33.17) and could be potentially detrimental to aquatic life in the tributary. The tributary, influenced by agricultural runoff, residential areas, and other anthropogenic activities, showed that despite Nemerow pollution index values for water samples being below 1, sediment analysis indicated areas of concern. Principal Component Analysis (PCA) was conducted to identify the potential sources of heavy metal contamination. In surface water, shared negative loadings on PC 1 (60.11%) indicated a unified influence, likely from agricultural runoff, while PC 2 (14.26%) revealed additional complexities. Sediments exhibited a unique signature on PC 1 (67.05%), associated with cumulative agricultural impacts, with PC 2 (18.08%) providing insights into nuanced factors, such as sediment composition and dynamic interactions. These findings offer a complete insight into the Chuhe River tributary’s condition, underlining the urgency for ongoing monitoring and potential remediation measures.

Heavy Metals in Surface Sediment of Plateau Lakes in Tibet, China: Occurrence, Risk Assessment, and Potential Sources.

Tibetan Plateau lakes have high ecological value and play a crucial role in maintaining ecological balance. This research aimed to study the pollution characteristics, ecological risk, and potential sources of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in the surface sediments of 12 Tibetan Plateau lakes. The results of the toxicity risk index (TRI) showed that only Gongzhu Tso (28.09) and La' ang Tso (20.25) had heavy metals that could pose a very high risk of toxicity to aquatic organisms. Hg posed the highest potential ecological risk to aquatic organisms. Based on the results of multiple analyses, we inferred that the contents of Cr, Cu, Hg, and Ni in sediments of Tibetan lakes were influenced by industrial and agricultural development; Cd, Pb, and Zn were influenced by transport and atmospheric transport; and As was derived from geothermal activity and rock weathering.

Metal bioavailability, bioaccumulation, and toxicity assessment through sediment and edible biota from intertidal regions of the Aghanashini Estuary, India

The sediment cores and edible biota from the intertidal regions of the Aghanashini Estuary were studied for the assessment of metal toxicity. The estuarine sediments received natural input of metals through the weathering of Dharwar and peninsular gneisses, and laterites. The sediments were enriched in Fe, Mn, Zn, Cu, Co and Ni than the upper crustal value. Also, the concentration of Fe, Zn, Cu, Co and Ni was more in the Aghanashini Estuary than other estuaries around the world. The Enrichment Factor (EF) revealed enrichment of Zn, Cu, Co and Ni in sediments, while the Geo-accumulation Index (Igeo) exhibited unpolluted-moderately-strongly polluted class of Fe, Zn, Cu, Co and Ni. The enrichment and pollution of metals in sediments was due to anthropogenic sources (domestic sewage, aquaculture and agricultural discharge) in the estuary. The presence of metals at a high concentration in the residual fraction and at a significant proportion in the bioavailable fractions construed both natural and anthropogenic sources of metal, and their bioavailability in the estuary. The physico-chemical factors (ionic composition, H+ ions, redox potential, and microbial activity) regulated the adsorption and desorption of metals in sediments. The Screening Quick Reference Table (SQUIRT) revealed level of bioavailable Mn and Co higher than the Apparent Effects Threshold (AET) and thus, indicated adverse toxic effects on biota. The Risk Assessment Code (RAC) indicated medium-high-very high risk of Mn, Zn, Co, Cu and Ni to biota. Also, the concentration of Fe, Mn, Zn, Cu and Ni in biota was in excess of permissible limit which pointed to their toxicity to biota and their consumers. The Target Hazard Quotient (THQ) value > 1, and Hazard Index (HI) value > 10 revealed risk of metal toxicity to humans.

Ecological risk assessment of trace metals in sediments and their effect on benthic organisms from the south coast of Zhejiang province, China

To explore the ecological risks of trace metals in sediments and their relationship with benthic organisms, 12 trace metals were analyzed and the macrobenthos were identified in the sediments collected from the south coast of Zhejiang province which belongs to the East China Sea. Spatially, the concentrations of most trace metals were high in the estuary, except for Ba and Sr. There was no obvious enrichment for trace metals, except that the concentration of Cd slightly exceeded the coastal background. The ecological risks calculated by the concentrations of Cr, Cd, Cu, Zn, Pb, and Ni in sediments showed that the methods based on sediment quality guidelines could judge the ecological risk more intuitively than the methods based on background value (PN, PLI, RI). The significant correlations between ecological risks and benthos density and biomass revealed the negative impact of trace metals at high concentrations on macrobenthic survival in sediments.

SPECIATION OF TRACE METALS IN SEDIMENT OF A TROPICAL RIVER

Concentrations and speciation of Pb, Cu, Cr, Cd, As, Ni in sediment from New Calabar River, Nigeria were assayed. Concentrations of the trace metals were determined using UNICAM solar 969 AAS. Speciation was done using five steps sequential extractions. Results revealed that for wet and dry seasons, concentrations (mg/kg) of the metals in the sediment ranged from 1.1E-2±1.0E-3 for As to 5.17±0.04 for Ni and that majority of the metals were bound to the residual fraction (F5), while Cu was mostly bound to the exchangeable fraction (F1). Overall trend of speciation indicated that Cr was higher in F5 and lower in fraction bound to organic matter (F4). It also indicated that Cu was higher in F5 and lower in F4 and that Pb was higher in F1 and lower in F4; Ni higher in F5 and lower in F4. The study has indeed provided data and information on the pollution status of the river.

An assessment of ecological and possible human health risks from Cr and Ni in sediments affected by the industrial marine area in Tuzla Aydinli Bay, Istanbul, Turkey between 2016–2020

An assessment of ecological and possible human health risks from Cr and Ni in sediments affected by the industrial marine area in Tuzla Aydinli Bay, Istanbul, Turkey between 2016–2020

Essential and non-essential metals in three lowland rivers of temperate South America (Argentina): Distribution and accumulation

BackgroundGeographic distribution of essential metals on earth is largely uneven. Therefore, regional specific approaches to assess metal contents in freshwater ecosystems are mandatory. Cd, Cu, Cr, Pb, Ni, Mn and Zn concentrations were measured in water, sediments and fish tocharacterize the partitioning of these essential and non-essential metals in three river ecosystems of the Pampean Plain==. MethodsWater, sediment and eight fish species were collected at three rivers from the Pampean Plain. After sample-specific pretreatments, Cd, Cr, Cu, Mn, Ni, Pb and Zn concentrations in water, sediment and muscle were determined in triplicate by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Contamination (Hakanson´s index) and bioconcentration factors were calculated to assess the degree of contamination and the relationship between the matrices, while the target hazard quotient was estimated to explore the risk to human health from fish consumption. ResultsWater metal concentration was below detection limit in all sampled rivers. Sediments were mostly enriched by Mn (186–474 mg kg−1) followed by Zn (36.8–40.3 mg kg−1), whereas in fish, the situation was the opposite, suggesting different biogeochemical pathways and uneven bioaccumulation of these elements. The largest concentrations for all explored metals were invariably recorded in fish from the Sauce Grande River, although only Cd, Cu and Ni in sediments were highest at this site. Indeed, the bioconcentration factor showed that Cd and Zn are actively accumulated by almost all species in all sampled rivers. The Targeted Hazard Quotient based on the muscle metal concentration tissue of the edible fish species (Odontesthes bonariensis) was less than 1. ConclusionNone metal seemed to pose a significant risk for humans. In some sites biota-sediment concentration factors of Cd and Zn and muscle Cd, Cr, Ni, Zn and Pb levels were highest in the silurid Pimelodella laticeps, suggesting that it may be used as a sentinel species for biomonitoring programs in Neotropical fish assemblages.

Spatial variation and ecological risk assessment for heavy metals in marsh sediments in Fuzhou reach of the Min River, Southeast China

To explore the pollution levels, sources and risks of heavy metals in sediments in Fuzhou reach of the Min River, the sediments involving in seven marsh types were sampled. Results showed that the concentrations of Pb, Zn and Cd in sediments declined from freshwater segment to estuarine segment. Higher levels of Cu, Cr and Ni in sediments generally occurred in estuarine segment. The highest levels of Pb and Cd were observed in bush swamp, while those of Cr, Ni, Zn and Cu occurred in mudflat. Cr, Cu, Zn and Ni probably shared common source, while Pb and Cd originated from another source. Pb and Cd were identified as heavy metals of primary concerns and the former showed high potential toxicity and high contributions to ΣTUs. Next step, the metal pollutions in sediments might be more serious if effective measures were not taken to control the loading of pollutants.

ASSESSMENT OF HEAVY METAL CONCENTRATIONS IN CRAB Sesarma angolense FROM BENIN RIVER, SOUTHERN NIGERIA

Heavy metals concentrations were determined in the crab (Sesarma angolense) and sediment of Benin River, Niger Delta Region, Southern Nigeria using Atomic Absorption Spectrometer. Except for Cd and Ni, other heavy metal concentrations differed insignificantly (p>0.05) among the stations. Thus Cd and Ni are the principal elements responsible for spatial variability in terms of heavy metal concentration in the sediment. Mean values of the heavy metals Fe, Zn, Mn, Cu, Cd, V, Cr, Pb and Ni in sediment from the three stations were 2.23, 0.39, 0.07, 0.08, 0.02, 0.04, 0.03, 0.06 and 0.12 respectively. Fe, Zn, Mn, Cu, Cd, V, Cr, Pb and Ni were observed to exhibit average values of 37.33, 8.85, 7.57, 2.29, 0.74, 1.92, 3.84, 0.86 and 4.05 mg/kg respectively in whole tissues of Sesarma angolense sampled which indicated that the metals were bioaccumulated. The concentration of Cd and Pb in the crab were relatively higher than FAO/WHO permissible limit for items made to be consumed by man, thus this rendered population of S. angolense from Benin River unsafe for consumption. This calls for constant monitoring of the Niger Delta ecosystem in order to minimize adverse health impacts heavy metals.

Immobilization of lead, copper, cadmium, nickel, and zinc in sediment by red mud: adsorption characteristics, mechanism, and effect of dosage on immobilization efficiency

The objective of this work was to determine the effect of dosage on the immobilization of lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), and zinc (Zn) in sediment by red mud (RM). To achieve this aim, the adsorption characteristics and mechanism of Pb, Cu, Cd, Ni, and Zn from aqueous solution on RM were studied at first, and then the influence of the RM dosage on the fractionation and leaching potential of Pb, Cu, Cd, Ni, and Zn in sediment was investigated. The results showed that RM possessed high adsorption capacities for Pb(II), Cu(II), Cd(II), Ni(II), and Zn(II) in aqueous solution. The maximum monolayer Pb(II), Cu(II), Cd(II), Ni(II), and Zn(II) adsorption capacities for RM derived from the Langmuir isotherm model were found to be 296, 39.2, 70.2, 46.0, and 50.7mg/g, respectively. The addition of RM into sediment could effectively reduce the toxicity characteristic leaching procedure (TCLP)-leachable concentrations of Pb, Cu, Cd, Ni, and Zn in the sediment. The added RM could effectively immobilize the mobile (exchangeable, reducible, and oxidizable fractions) Pb in sediment by the conversion of the exchangeable and reducible fractions into the residual fraction, and it could effectively immobilize the mobile Cu, Cd, Ni, and Zn in sediment by the conversion of the exchangeable fraction into the residual fraction. The quantities of mobile Pb, Cu, Cd, and Ni immobilized by RM had a good linear relationship with the added RM. The above results suggest that RM is a promising amendment for the immobilization of mobile Pb, Cu, Cd, Ni, and Zn in sediment, and the linear relationship between the RM dosage and the quantities of immobilized Pb, Cu, Cd, and Ni by RM can be employed to determine the RM dosage required for the immobilization of mobile Pb, Cu, Cd, and Ni in sediment.

Transfer and accumulation of trace elements in seawater, sediments, green turtle forage, and eggshells in the Xisha Islands, South China Sea.

Chemical pollutants present a substantial threat to the survival of the green turtle (Chelonia mydas). In this study, the concentrations of 12 trace elements (TEs) in seawater, sediments, and green turtle forage and eggshells from the Xisha Islands in the South China Sea, along with their patterns of transfer and accumulation, were identified. The results revealed that the median TE concentrations in seawater and sediments were lower than the first-grade limit values of the national standard in China, indicating a low ecological risk. The concentrations (μg·g-1) of TEs in forage ranged from 0.05-0.69, 3.43-14.4, 157-2391, 27.9-124, 2.05-9.39, 0.30-9.78, 2.01-80.50, 0.18-5.76, 0.06-0.98, 2.00-18.4, 0.02-0.24, and 0.01-0.09 for Cr, Mn, Sr, Fe, Ni, Cu, Zn, Se, Cd, As, Pb, and Hg, respectively. Seawater, sediments, turtle forage, and eggshells exhibited different TE profiles, which were driven by Hg, Sr, Cr, and Pb in seawater and sediments; Fe and Ni in sediments; Cd and As in forage; and Zn, Se, and Cu in eggshells. The contents of Cu, Zn, and Se increased slightly with trophic level, indicating that they were transferred through dietary pathways. Although Cd and As appeared to bioaccumulate in green turtle forage, it was not transferred to their eggshells, which may be related to the excretion and metabolism process in the mother's body. Thus, eggshells may be a poor bioindicator for the exposure of female green turtles to these toxic elements.

Accumulation of Trace Metal in Sediment and Soft Tissue of Strombus canarium in a Tropical Remote Island of Thailand

The present study determined the metal levels in surface sediment and in soft tissue of the Strombus canarium at Libong Island, Thailand, and estimated the possible risk from consuming the shellfish. The mean concentrations of the metals Fe, Cu, Co, Pb, Mn, and Ni in sediment were 2711.94 ± 1424.83, 0.47 ± 0.37, 0.11 ± 0.09, 1.32 ± 1.48, 40.41 ± 16.12, and 2.75 ± 4.04 µg/g, respectively, and are below the sediment quality guidelines. The enrichment factor (EF) and geoaccumulation index (Igeo) showed that the sediment conditions ranged from “no pollution” to “moderate contamination”. The mean concentrations in Strombus canarium had rank order Fe > Mn > Cu > Ni > Co > Pb. The bioaccumulation (BSAF) suggests that the Strombus canarium accumulated Cu and Co the most. The estimated daily intakes of these metals through shellfish consumption were below the oral reference dose (Rfd) and the calculated target hazard quotients (THQ) were less than 1. The results from this study inform about the background levels of metals in the sediment and in Strombus canarium species at Libong Island. In addition, these data might help ensure that the consumption of shellfish in this area remains safe.

A comparative evaluation of the effects of copper and nickel on the growth of the freshwater fish Cyprinus carpio and amelioration by Pistia stratiotes

The main objectives of this research were to identify if the presence of the aquatic weed Pistia stratiotes in the medium could influence the growth of the fish Cyprinus carpio when chronically exposed to sub-lethal concentrations of Cu (0.05 and 0.1 mg/L) and Ni (0.5 and 1.0 mg/L) in the presence of the weed and to compare between effects of Cu and Ni. Experiments were conducted in cement tanks for 90 days. Accumulation of Cu and Ni in water, sediment, fish and weed was determined by Atomic Absorption Spectrophotometer at the end of the experiments. The data were taken as factors to evaluate the interaction between the treatments of metals and weed and their impact on the growth of the fish. Multiple quadratic regression models followed by surface response plots were used to evaluate the interactions and their effects on the growth of C. carpio. The results indicated that the presence of the weed could reduce the accumulation of Cu and Ni in the sediment and fish and thus could ameliorate the ill effects of these metals on the growth of the fish. But there was a difference in growth response between the metals. By using the quadratic polynomial regression model and the surface response plot, it was revealed that Cu produced more deleterious effects on the growth of C. carpio than Ni. The weed interacted better with Cu than Ni, but for both the metals, the weed failed to prevent adverse effects on the growth of fish at a higher concentration of the metals used. The quadratic polynomial regression model followed by the surface response plot is a powerful tool to analyze the interaction between the weed and the treatments of metals and to compare the adverse effects of Cu and Ni on the growth of C. carpio.

Prediction of sediment quality based on the concentration of heavy metals Cu, Zn, and Ni in Jakarta Bay using the index analysis approach

The purpose of this study was to predict the concentration of heavy metals Cu, Zn, and Ni in sediments and to predict the sediment quality based on an index analysis approach (contamination factors, geo accumulation index, pollution load index, ecological risk index, and potential ecological risks index). The sediment sample taken by using a sediment grab in Jakarta Bay. Heavy metal content measured by using Atomic Absorption Spectrophotometer (AAS). The results showed that the Cu range from 14.79 to 55.36 µg.g−1 with an average of 33.178 µg.g−1, Zn range from 82.05 to 441.91 µg.g−1 with an average of 197.484 µg.g−1 and Ni range from 16.47 to 22.09 µg.g−1 with an average of 19.328 µg.g−1. The mean levels of Zn and Cu were still lower than the threshold value of sediment quality, i.e., 108 µg.g−1 for Cu, 271 µg.g−1 for Zn, while for Ni is higher, ie, 16 µg.g−1. The results of the index analysis showed that the average value of contamination factor (CF) of Cu, Zn, and Ni were 1.614, 2.018, Ni -0.138 respectively (1 < CF < 3, moderate contamination), the average of geo accumulation index values of Cu, Zn, and Ni were -0.136, -1.010, -0.138 ((Igeo < 0, unpolluted) respectively. The average Pollution Load Index value (PLI) is 1.637 (PLI > 1); based on the PLI index, sediments are categorized as polluted by Cu, Zn, and Ni. Based on ecological risk index (Er) and potential ecological risk index (RI), sediment includes low risk ecology (Er < 40) and low potential risk ecology (RI<150).

Types, occurrence, and distribution of microplastics and metals contamination in sediments from south west of Kerkennah archipelago, Tunisia.

Microplastics (MPs) are one of the most significant solid waste pollutants in the marine environment and accumulate in sediments around worldwide. In this study, the pollution level, the type, occurrence, and distribution of MPs in sediments from the southwestern Kerkennah archipelago, Tunisia, were investigated. Sediment samples were collected from 20 adjacent sites through three "lines L1, L2, and L3." MPs were separated from sediment by density flotation (NaCl, 1.2gcm-3) and characterized in terms of shape, size, and color using microscope. The accumulation of toxic chemicals such as trace metals on microplastics was measured by atomic absorption microwave-assisted acid extraction. Polymer types were identified using FTIR-ATR spectroscopy. This study showed that microplastics were found in all samples, which emphasized that their extensive distribution throughout three lines by an average abundance of "MPs" was 611 items/m2. Among the shape categories of plastic particles, fiber and fragment were the most dominant frequent shapes (94%). The more frequent colors found were white (52.7%) and transparent (35.1%). Regarding the sizes, the microplastics below 1mm were the most common accounting for 97% of all plastics. Results of trace metals Zn, Cu, Pb, Cr, and Ni in sediments with concentrations were reported as 3.48μg/g, 0.41μg/g, 0.38μg/g, 0.33μg/g, and 0.12μg/g, respectively. Graphical abstract.

Evaluation of the environment risk, fractions and mobilization of nickel (Ni) in sediments of the Jialing River by sediment quality guidelines, sequential extraction and Chelex-AgI gel DGT probe

The Jialing River is one of the largest tributaries of the Yangtze River and has the largest drainage area. Nickel (Ni) is a one of the most serious heavy metal contaminants in the downstream section of the Jialing River as a result of the prosperity of nearby chemical, electronic and mining industries. In the present work, sediment quality guidelines (SQGs), a Community Bureau of Reference (BCR) sequential extraction and the diffusive gradients in thin films (DGT) technique were applied to evaluate the environment risk, fractions and remobilization of Ni in the downstream Jialing River. The results indicated that the average total concentration of Ni (54.7 mg kg−1) at all sites was higher than the background values of soil in China and Sichuan (26.9 and 35.8 mg kg−1, respectively). Environment risk assessment with four types of SQG values found that at three sites, the Ni concentration was over two high guideline values (probable effect concentration, PEC; effect range median, ERM), indicating that Ni may frequently pose a threat to the local aquatic ecosystem. The DGT results showed that CDGT-Ni had an inverse variation trend with CDGT-Fe and presented a significant increasing trend at the bottom of the DGT probes. Flux results revealed that sediments at S1, S2 and S3 were the source for Ni release across the sediment-water interface (SWI), and only S4 was a sink for Ni. Two further studies found that CDGT-Ni presented a significant negative correlation with CDGT-Fe. In addition, the “hotspot” of CDGT-Ni at the bottom correlated well with the “dark area” of CDGT-S. These results indicated that Fe and S were factors that mitigated the release of Ni in the sediments.

Risk and Toxicity Assessments of Heavy Metals in Tympanotonus fuscatus and Sediments from Iko River, Akwa Ibom State, Nigeria

This study evaluates the physico-chemical parameters and heavy metals in water, sediments and Tympanotonus fuscatus obtained from three sample sites along Iko River in Eastern Obolo LGA, AkwaIbom State. The heavy metal analysis results on Pb, Cd and Ni in sediments and Tympanotonus fuscatus were used to estimate the human health and ecological risk assessment of the study area. The human health risk assessment tools utilized in this study were estimated dietary intake (EDI), total hazard quotient (THQ) and hazard index (HI) while sediment pollution parameters evaluated were contamination factor (CF), contamination degree (CD), pollution load index (PLI) and geoaccumulation index (Igeo). Results obtained showed that EDI of Cd in periwinkle in the study sites ranged from 0.2 – 6.4 µg/kg-bw/day and exceeded the provisional tolerable dietary intake (PTDI), while EDI for Pb (0.0004 – 2.6 µg/kg-bw/day) and Ni (0.32 – 2 µg/kg-bw/day) was within the limit for all sites, except Ni in site II (34 µg/kg-bw/day) which was higher than the PTDI of 5 µg/kg-bw/day. The THQ of Cd in all sites was greater than 1, while Pb and Ni generally recorded THQ &lt; 1. The hazard index (HI) was as follows: site I (2.36), sites II (24.44) and site III (6.5), highlighting a potential hazardous effect to humans as a result of the consumption of Tympanotonus fuscatus obtained from site II and III. The sediment pollution assessment revealed that the contamination factor (CF) and geoaccumulation index, Igeo of Cd were far above the permissible limits while Pb and Ni were mostly within limits. The estimated contamination degree (CD) and pollution load index (PLI) showed a high degree of pollution, which can be mainly attributed to the high degree of Cd contamination in the sediment. Therefore, the area under investigation is highly polluted and the periwinkle obtained from Iko river in the study area is unfit for human consumption.

Heavy Metal Accumulation and Anti-Oxidative Feedback as a Biomarker in Seagrass Cymodocea serrulata

The pursuit of a good candidate to biomonitor environmental pollutants has been on the increase. In this study, the concentrations of Fe, Mn, Cu, Zn, Cd, Cr, Pb and Ni in sediment, seawater and seagrass Cymodocea serrulata compartments and antioxidant enzymes activities in C. serrulata were determined. Our results revealed that bioconcentration factors for all the metals were less than 1 (BCF &lt; 1) and concentrations in seagrass compartments were in the order root &gt; leaf &gt; rhizome for Fe and Mn, leaf &gt; root &gt; rhizome for Cu, Zn, Pb and Ni, and root &gt; rhizome &gt; leaf for Cd and Cr. Effect range low concentrations (ER-L) revealed that Cu, Zn, Cd, Pb and Ni concentrations were above ER-L values and Cr concentration was below ER-L values while concentrations in seawater for all the heavy metals were above the estimate average element concentrations in seawater (ECS). Significant variation (p &lt; 0.05) was recorded for heavy metals in sediment, seawater, seagrass compartments and heavy metal concentrations across stations. Influence of heavy metals on antioxidant enzymes activities; catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST) and acetylcholinesterase (AChE) were recorded, and high activities of the antioxidants were recorded in station S8 corresponding to high concentrations of heavy metals in the same station. There is a need for the promotion of biomonitoring networks across the marine environment using C. serrulata and antioxidant enzymes as biomarkers of oxidative stress caused by environmental pollutants.