Heavy Metal Concentrations In Sediments Research Articles

Spatiotemporal distribution dynamics of heavy metals in water, sediment, and zoobenthos in mainstream sections of the middle and lower Changjiang River

Water, sediment, and zoobenthos are crucial carriers and storage media for heavy metal migration and transformation. The distribution characteristics of heavy metals in water, sediment, and zoobenthos can reflect their pollution status and potential influences on the health of aquatic ecosystems. On the basis of monitoring data related to Cu, Zn, Pb, Cd, Ni, Mn, Hg, and As in mainstream water, surface sediment, and zoobenthos at eight sections—from Wuhan to Shanghai—of the Changjiang River (also known as the Yangtze River) and historical monitoring data on heavy metal distributions in different environmental media of the Changjiang River since the 1980s, this study undertook systematically analyzed the spatiotemporal distribution dynamics, pollution levels, and corresponding environmental risks related to heavy metals in water, sediment, and biota, and examined the effects of pollution source variations and water and sediment regimes on heavy metal distribution. Heavy metal concentrations in the waters were much lower than the water quality threshold of Grade III of the Chinese Surface Water Environmental Quality Standard (GB3838-2002); the concentrations of different heavy metals were irregularly distributed and varied significantly along the river mainstream; Cu, Cd, Zn, and Pb concentrations in sediment all exceeded their respective critical effect concentrations and exposed the ecosystem to pollution risks; the pollution levels of and ecosystem health risks posed by Zn and Cu in zoobenthos were high, with pollution concentrations ranked as shrimp > snails > crabs. In general, heavy metal concentrations in the three environmental mediums were ranked as sediment > zoobenthos > water. Finally, comparison with historical monitoring data revealed increasing Cd and Hg concentrations, with the average heavy metal concentration in sediment reaching its maximum value in the 2000s in the middle and lower reaches of the Changjiang River, which are subjected to the combined effect of pollutant emissions and changing water and sediment regimes.

Occurrence Relationship Between Microplastics and Heavy Metals Pollutants in the Estuarine Sediments of Poyang Lake and the Yangtze River

Heavy metals are typical pollutants in the environment and microplastics are relatively newly recognized environmental pollutants, with their coexistence potentially compounding pollution and ecological risks. In this study, we investigate the contents and morphological characteristics of microplastics and heavy metals (Cu, Cd, Pb, Zn, and Cr) in the estuarine sediments of Poyang Lake and the Yangtze River as a means of exploring the relationship between them. The results showed that the abundance of microplastics ranged from 356 n·kg-1 to 1452 n·kg-1, with an average abundance of 982.33 n·kg-1 in the dry sediments. Microplastics were identified as being of three main types:fragments, fibers, and films, whereby fragments were the most dominant type found and accounted for 48.23% of the total microplastics in the sediments. The main color of microplastics in the sediments was chromatic, and the particle size of most microplastics was<1 mm. The major polymer components were polyethylene (PE), low density polyethylene (LDPE), and polyethylene (PP). Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) results indicated that the surfaces of microplastics were rough, porous, cracked, and torn, and that the five heavy metals were found on the surfaces of different microplastics. These heavy metals accumulated to different degrees in the estuarine sediments, and redundancy analysis indicated that environmental factors[including the total organic carbon (TOC), pH, electrical conductivity (EC), and sediment particle size] and the occurrence of microplastics all had significant (P<0.05) effects on the distribution of heavy metal concentrations in sediments. Variation partitioning analysis (VPA) showed that the contribution rates of environmental factors and microplastics to the bioavailability of heavy metals were 37.70% and 0.70% respectively, but the combined effect was 49.60%. We conclude that microplastics in sediments may act as carriers of heavy metals and activate their bioavailability, hence posing a potential threat to the ecological security of estuaries and wetlands.

Heavy metal concentrations in sediments and Cyprinus carpio from Maqalika Reservoir –Maseru, Lesotho: An analysis of potential health risks to Fish consumers

The determination of heavy metal contaminants in fish is very important in monitoring health risks to humans who consume them. This study assessed the concentration of heavy metals (As, Pb and Zn) in sediments and gills of Common Carp fish (Cyprinus carpio) from Maqalika Reservoir in Maseru, Lesotho and their potential health risks to such fish consumers. Sediment and Cyprinus carpio samples were collected from upstream, midstream and downstream sites of Maqalika Reservoir and examined for As, Pb and Zn using atomic absorption spectrometer. Potential health risks were based on comparing the derived metal concentrations in gills of Cyprinus carpio with the World Health Organization (WHO) permissible limits for human consumption. The mean concentration levels of Zn, As and Pb in sediment were in the order: 78.5; 2.34; and 0.29 mg/kg respectively. In the gills of Cyprinus carpio the mean concentration levels were in the order 7.85; 1.29; and 0.33 mg/kg for Zn, As and Pb respectively. The magnitude of concentration of Zn, As and Pb by location in the reservoir varied spatially in the order of downstream > midstream > upstream in both sediment and gills of Cyprinus carpio. Significant differences (p < 0.05) in metal concentrations between upstream and downstream sites of the reservoir were observed. The metals concentration in gills of Cyprinus carpio were lower than those in sediments, but positively and significantly correlated (P < 0.05). As and Pb concentration levels in the gills of Cyprinus carpio were higher than the WHO permissible limits recommended for fish consumption of 1 mg/kg and 0.2 mg/kg respectively, suggesting that residents could experience significant health risks from the intake of individual metals through fish consumption. Measures should be taken to reduce heavy metal concentrations in sediment and Cyprinus carpio exposure in the general population in order to minimize the risk of human health adverse effects.

Assessment of nutrient and heavy metal concentrations in sediments and macrophytes of the Oroma wetland, Nigeria

Assessment of nutrient and heavy metal concentrations in sediments and macrophytes of the Oroma wetland, Nigeria

Risk Assessment of Heavy Metal Concentrations in Sediments of Matang Mangrove Forest Reserve

Matang Mangrove Forest Reserve (MMFR) is one of the most productive and managed forests in the world. On the other hand, it has become a concern whether MMFR is being degraded as a result of exposure to industrial pollution. Industries located around MMFR dispose effluents contaminated by heavy metals. This study was conducted to analyze heavy metal contamination and risk assessment status in MMFR sediments. Sediment samples from six compartments were collected based on age and location of the mangrove plantation. Total metal digestion and modified sequential extraction were performed to estimate the concentration of heavy metals. Based on the estimation, risk assessment code, geo-accumulation index, pollution load index, and contamination factor were computed to classify the compartments according to their contamination and pollution levels. Organic matter and sediment texture (silt, clay, and sand content) were also analyzed to find its correlation with heavy metals. According to the results, high concentrations for Copper, Nickel, and Cadmium were observed in Compartment 42, while Compartment 18 and Compartment 74 showed higher concentrations for Zinc and Lead. Heavy metals showed weak positive correlation with clay and silt, but weak negative correlation with sand. For organic matter, only Zinc showed statistically significant but weak negative correlation. Risk assessment code, geo-accumulation index, pollution load index, and contamination factor categorized the compartments into unpolluted to moderately polluted. Based on the study outcomes, it can be concluded that MMFR, although acquiring industrial discharge, is not with a high risk of heavy metal contamination.

Assessment of Ecologic Quality in Terms of Heavy Metal Concentrations in Sediment and Fish on Sakarya River and Dam Lakes, Turkey

ABSTRACTSakarya River with a length of 824 km is one of the most important lothic ecosystems of Turkey. Sarıyar, Gökçekaya and Yenice Dams were constructed on the Sararya River for the purpose of electric supply and utility water for agricultural and fishery activities. In this study, sediment samples were collected from 14 stations selected on areas seasonally (2015–2016). Also, cyprinidae species (Carassius gibelio (Bloch, 1782), Capoeta baliki Turan, Kottelat, Ekmekçi & Imamoglu 2006) were caught from Dam Lakes and Sakarya River. Cr, Ni, Cu, Zn, Pb levels in sediment samples and in tissues (liver, gill and muscle) of fish were analyzed in samples by Analytic Jena ContrAA 700 (high-resolution continuum source atomic absorption spectrometer). The data observed were evaluated with national and international quality criteria. According to the data in the study results, heavy metal accumulations in the gill and liver of fish were determined higher than muscle. Zn levels in muscle of C. gibelio caught from Yenice Dam Lake were higher than the permissible limit stated by Turkish legislation and FAO. Also, Cr and Ni levels in sediment samples especially during rainy seasons were higher to dry seasons and Cr and Ni levels were detected higher than sediment quality guidelines.

Changes in the heavy metals and petroleum hydrocarbon contents in seawater and surface sediment in the year following artificial reef construction in the Pearl River Estuary, China.

Marine pollution is an important driver of ocean biodiversity loss, which can be mitigated by the construction of artificial reefs (ARs). Many studies have explored how ARs affect marine organisms, but our understanding of the changes in heavy metals and petroleum hydrocarbons after AR construction is limited. In the current study, we assessed the heavy metal and petroleum hydrocarbon contents of the seawater (surface and bottom seawater) and surface sediment before and after AR construction in AR habitat and in nearby non-reef control habitat in the Pearl River Estuary, China. AR construction tended to decrease the contents of Cu, Pb, Cd, and Hg but tended to increase Zn content in seawater and in surface sediment. Petroleum hydrocarbon content changed irregularly in seawater and surface sediment. Effects of AR construction were similar in the nearby non-reef habitat vs. the AR habitat. Seawater heavy metal and petroleum hydrocarbon contents were correlated with the seawater physicochemical properties (mainly temperature, inorganic nitrogen, chemical oxygen demand, available phosphate, and suspended particulate organic matter), and sediment heavy metal content was correlated with sediment organic matter content. Additional studies over longer time periods and at larger spatial scales are needed to clarify how AR construction affects heavy metal and petroleum hydrocarbon contents in marine environments.

Potential bioremediation effects of seaweed Gracilaria lemaneiformis on heavy metals in coastal sediment from a typical mariculture zone.

Seaweeds are good bio-monitors of heavy metals pollution in coastal seawater. In the present study, the potential bioremediation effects of cultivated Gracilaria lemaneiformis on heavy metals in Nan'ao coastal sediment from a typical mariculture zone, South China were evaluated. Sediment samples were collected from five different zones (Gracilaria cultivation zone, G; Fish culture zone, F; Shellfish culture zone, S; Transition zone, T; Control zone, C) from December 2014 to July 2015. The concentrations of Cd, Pb, Cu, and Zn in the sediments were significantly different among the various types of mariculture areas. The concentrations varied widely: Cd (0.04-1.02) μg g-1; Cu (1.19-37.70) μg g-1; Pb (8.45-74.45) μg g-1; Zn (36.80-201.24) μg g-1. The lowest heavy metal concentrations in the sediment were occurred at Gracilaria cultivation zone, while higher concentrations occurred at control zones and fish culture zones. The pollution load index, principal components and cluster analysis showed that heavy metal concentrations were the highest at fish culture zone, while the concentrations were the lowest at Gracilaria cultivation zone, and Gracilaria cultivation affects the heavy metals in the sediments. Gracilaria had strong adsorption capacities for heavy metals from seawater, showing the highest heavy metal Bioconcentration Factors in May (higher seaweed biomass period). Consequently, the results suggested that Gracilaria cultivation influences the heavy metal concentrations in sediments from the typical coastal mariculture zone. Gracilaria cultivation has the potential to bioremediate heavy metals in the coastal sediments. Therefore, Gracilaria cultivation can add environmental advantages and ecological values to coastal mariculture zones.

Assessment of heavy metals in benthic macroinvertebrates, water and sediments in River Isiukhu, Kenya.

A major ecological challenge facing freshwater resources such as rivers is the influx of chemical contaminants from anthropogenic sources. A report on the levels of heavy metals, namely Zn, Cu, Cr, Cd and Pb in benthic macroinvertebrates, sediments and water along River Isiukhu, within Lake Victoria catchment area in Kenya is presented. Families of benthic macroinvertebrates that were investigated included Gerridae, Baetidae and Unionidae. Samples were digested using the appropriate acid combination and analysed using Spectra AAS Varian 200. Physicochemical parameters were measured on-site using mobile Hydrolab Quanta. Pearson's correlation matrix and post hoc Tukey's test were used to show the relationship between metal concentrations in the various matrices at significant differences accepted at p ≤ 0.05. Positive correlations were obtained for heavy metal concentrations in sediments and benthic macroinvertebrates with significant correlations observed for Zn (r = 0.655, p = 0.029) and Cu (r = 0.641, p = 0.034). Sediments presented the highest range of heavy metal concentrations compared to water and benthic macroinvertebrates and presented the only matrix with quantifiable Pb levels. The range in heavy metal concentration in benthic macroinvertebrates samples were as follows: Zn, 30.73-46.64, 21.93-38.17, and 26.85-41.69 mg/kg, Cu, 1.17-6.54, 1.11-3.87 and 1.15-5.79 mg/kg, Cr, 0.47-1.61, 0.22-0.74 and 0.25-0.92 mg/kg, for families Unionidae, Baetidae and Gerridae respectively. Heavy metal concentration profile along the river indicated an influx of pollutants from anthropogenic sources due to rapid urbanization along the river.

Spatial and vertical distribution analysis of heavy metals in urban retention tanks sediments: a case study of Strzyza Stream

Concentrations of seven heavy metals (HMs): Zn, Cu, Pb, Cd, Ni, Cr, and Fe in core samples of bottom sediments from four retention tanks (RTs) located along the Strzyza Stream in northern Poland (Gdansk) were measured to obtain a general view of sediment quality. The recognition of contamination and potential environmental impacts is the main aim of this paper. A total of 96 sediment samples were collected from eight sampling sites at depths of 0–2 cm, 8–10 cm, 16–18 cm, 24–26 cm. Concentrations of Cu, Zn, Pb, Fe, Ni, and Cr were measured with AAS while Cd concentration was measured with ICP-MS. Granulometric analyses with normalized sieve apertures were carried out. Geochemical indices: enrichment factor, anthropogenic factor, and modified degree of contamination (mCd) were used to assess the contamination level. Concentrations of HMs in sediments changed in the range: Cu (3.24–119 mg/kg d.w.), Zn (12.5–584 mg/kg d.w.), Pb (4.91–309 mg/kg d.w.), Cd (0.003–0.716 mg/kg d.w.), Ni (1.57–25.8 mg/kg d.w.), Cr (2.45–74.5 mg/kg d.w.), and Fe (3993–63817 mg/kg d.w.). The sequential extraction verified the bonding of HMs with non-mobile fractions. Geochemical indices showed widespread pollution by Cu, Pb, Cd, and Zn. Cluster and factor analysis distinguished three related subgroups of HMs: Pb, Ni–Cr, and Fe–Cd–Cu–Zn, suggesting possible common source of each subgroup. Strongly contaminated sediments were distinguished in sediment cores in two middle stream RTs characterized by intense urbanization in their direct catchments.

Spatial variations and periodic changes in heavy metals in surface water and sediments of the Three Gorges Reservoir, China

Substantial changes have occurred in hydrological situation of the Three Gorges Reservoir (TGR) after the operation of the Three Gorges project, as have the heavy metals (HMs) pollution characteristics. In this study, concentrations of Cu, Zn, Pb, Cr, and Cd in surface water and sediments of the TGR were determined during the water impoundment period (December 2015) and water drawdown period (June 2016). The index of geoaccumulation, principal component analysis (PCA), and correlation analysis were used to analyze HMs pollution characteristics. Results showed that HMs concentrations in surface water were much lower than the quality standards for drinking water and surface water of China. The pollution levels of HMs in sediments were nonpolluted for Cr, nonpolluted to moderately polluted for Cu, Zn, Pb, and moderately polluted for Cd. In the fluctuating backflow zone, HMs concentrations in sediments during the water drawdown period were lower than those during the water impoundment period, which was attributed to that faster flow velocity during the water drawdown period resulted in less deposition of suspended solids and faster release of HMs pollutants from sediments to water. HMs concentrations of sediments at sites M14 and M17 showed similar periodic changes to those at the fluctuating backflow zone, which might be attributed to the density-stratified flow in the adjacent upstream tributaries (Meixi River and Qinggan River, respectively). Correlation analysis and PCA analysis results showed that for the sediments, Cr came from natural sources, while Cu, Zn, Pb, and Cd mainly came from anthropogenic sources.

Sources of elevated heavy metal concentrations in sediments and benthic marine invertebrates of the western Antarctic Peninsula

Antarctica is one of the least anthropogenically-impacted areas of the world. Metal sources to the marine environment include localised activities of research stations and glacial meltwater containing metals of lithogenic origin. In this study, concentrations of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were examined in three species of benthic invertebrates collected from four locations near Rothera Research Station on the western Antarctic Peninsula: Laternula elliptica (mudclam, filter feeder), Nacella concinna (limpet, grazer) and Odontaster validus (seastar, predator and scavenger). In addition, metals were evaluated in sediments at the same locations. Metal concentrations in different body tissues of invertebrates were equivalent to values recorded in industrialized non-polar sites and were attributed to natural sources including sediment input resulting from glacial erosion of local granodioritic rocks. Anthropogenic activities at Rothera Research Station appeared to have some impact on metal concentrations in the sampled invertebrates, with concentrations of several metals higher in L. elliptica near the runway and aircraft activities, but this was not a trend that was detected in the other species. Sediment analysis from two sites near the station showed lower metal concentrations than the control site 5 km distant and was attributed to differences in bedrock metal content. Differences in metal concentrations between organisms were attributed to feeding mechanisms and habitat, as well as depuration routes. L. elliptica kidneys showed significantly higher concentrations of eight metals, with some an order of magnitude greater than other organs, and the internal structure of O. validus had significantly higher Ni. This study supports previous assessments of N. concinna and L. elliptica as good biomonitors of metal concentrations and suggests O. validus as an additional biomonitor for use in future Antarctic metal monitoring programs.

Heavy metal accumulation and phytoremediation potential by transplants of the seagrass Zostera marina in the polluted bay systems.

Although seagrasses can incorporate heavy metals from the marine environment, few studies have been conducted on heavy metal uptake and phytoremediation potential by seagrass transplants in the heavy metal contaminated sediments. Zostera marina shoots were transplanted in two polluted bay systems on Korean coasts to evaluate the heavy metal contaminations in sediments and the possibility of using Z. marina transplants as a bioindicator and phytoremediation agent. The major concentrated metals in sediments were As, Cu, Fe, and Pb in Jaran Bay, and Cd, Co, Zn, and Hg in Onsan Bay. The Co, Zn, Pb, and Hg concentrations in Z. marina tissues reflected the sediment heavy metal concentrations, and thus the tissue heavy metal concentrations may be used as bio-indicators of the metal contaminations. Since Z. marina transplants accumulated a great amount of heavy metals in their tissues, they may have the phytoremediation potential for the heavy metal contaminated sediments.

Priority Pollutants in Water and Sediments of a River for Control Basing on Benthic Macroinvertebrate Community Structure

Understanding the drivers of macroinvertebrate community structure is fundamental for adequately controlling pollutants and managing ecosystems under global change. In this study, the abundance and diversity of benthic macroinvertebrates, as well as their chemical parameters, were investigated quarterly from August 2014 to April 2015 in four reaches of the Huai River basin (HRB). The self-organizing map (SOM) algorithm and canonical correspondence analysis (CCA) were simultaneously applied to identify the main factors structuring the benthic community. The results showed that the benthic community structure was always dominated by gastropoda and insecta over seasons and presented obvious spatial and temporal heterogeneity along different pollution levels. The insects were always the top contributors to number density of the benthic community, except for the summer, and the biomass was mainly characterized by mollusca in all seasons. Statistical analysis indicated that TN and NH3-N in water, as well as Hg, As, Cd, and Zn in sediments, were the dominant factors structuring the community, which determined the importance of sediment heavy metal concentrations in explaining the benthic community composition in comparison with other factors. These major factors should be given priority in the process of river pollutant control, which might be rated as a promising way to scientifically improve river health management and ecological restoration.

Distribution pattern and pollution status by analysis of selected heavy metal amounts in coastal sediments from the southern Caspian Sea

Amounts of heavy metal elements (Zn, Cd, Pb, Cu, Ni, Co, Mn, and Fe) in surficial sediments at four regions (coastline, estuaries, rivers discharging into the sea, and Gorgan Bay) along the southern coastline of the Caspian Sea were investigated in summer 2015. Collected data was applied to appraise the sediment contamination degree and the origin of pollutants based on the Geo-accumulation Index. Pollution status was assessed via the Enrichment Factor (EF) and the Potential Ecological Risk Index (PERI, the Hakanson index). Heavy metal contents in sediments in mgg-1dw varied from 3000 to 39,500 for Fe, 166.66 to 2000 for Mn, 11 to 4198 for Zn, not detected (ND) to 822.83 for Pb, ND to 40.66 for Cd, 6.16 to 37.16 for Cu, 11.66 to 69 for Ni, and 6.33 to 33.00 for Co. Higher amounts of Cd, Pb, Cu, Mn, and Fe were determined in rivers discharging sediments into the sea. In Gorgan Bay, Zn, Ni, and Co were highest. Greater potential ecological risk levels were detected along the coastline as well as rivers discharging into the sea. Among heavy metals considered, Zn and Cd had the highest enrichment factors. The Geo-accumulation Index proved that the investigated region could be classified as Zn- and Cd-polluted area.

Ecological risk by heavy metal contents in sediments within the Wei River Basin, China

The Wei River is the largest tributary of the Huang River, which is the second largest river in China. This study aimed to determine pollution and risk assessment of heavy metals, including chromium (Cr), lead (Pb), zinc (Zn), arsenic (As), mercury (Hg), and cadmium (Cd), in 12 selected stations of the Wei River Basin, Northwest China. Results indicated that the pollution and potential risk in Weijiabao are more severe than the other 11 cross sections. The concentrations and potential ecological risk of Pb and Hg and Cr, Pb, Zn, As, and Hg were observed in moderately contaminated and considerable risk levels given industrial wastewater discharge, correspondingly. For the single element, the relative contaminated status and potential risk levels for Cr, Pb, Zn, As, and Hg were Zn > Hg > Cr > Pb > As and Hg > Pb > As > Cr > Zn, respectively. The Cr in sediments may derive from agricultural activities given the utilization of chemical fertilizers, whereas Pb, Zn, and As may derive from industrial wastewater and sewage sludge. Metal melting wastewater in the upper reach and paper mill and textile process wastewater in the middle reach of the Wei River should be disposed of and should satisfy the corresponding criteria of the Integrated Wastewater Discharge Standard (GB8978-2002). Furthermore, a scientific application of chemical fertilizers in the Jing and Beiluo Rivers should be implemented in the reach.

SPATIAL AND TEMPORAL EFFECTS ON FRESHWATER BENTHIC INVERTEBRATES DIVERSITY IN SOME LOCALITIES OF MENOUFIA GOVERNORATE, EGYPT

Freshwater zoobenthos (macro-invertebrates) are organisms that live on, in, or near the bottoms of the freshwater. Their presence, abundance and species diversity are affected by numerous factors. This study was designed to evaluate temporal and spatial changes of benthic invertebrates’ diversity in the light of ecological conditions at the selected sites. Three sites at Menoufia governorate were selected as follows: site one and two are located at Bahr Shebeen El-Koom, Milig and Tanta branches, respectively. However, site three is located at Gezay Village, Menouf. Monthly samples were collected during one year from March, 2017 till February, 2018. Ecological parameters such as temperature, pH, total dissolved solids (TDS), electrical conductivity (EC)…etc., and heavy metals (Al, Ca, Cu, Fe and Pb) concentrations in sediment and tissues of the collected molluscs were measured. Environmental parameters showed variations in values from one season to another. The highest abundance of zoobenthos in all seasons was recorded at site three (42 %) followed by site one (32 %) and then site two (26 %). Three phyla were recorded during the present study; Annelida, Arthropoda and Mollusca. Diversity, variety and evenness indiceswere maximum at site three followed by site one then site two. Heavy metals concentrations in sediments and tissues of mlousca were maximum at site two followed by site one and finally site three. It is concluded that, the population density, species diversity and communities of freshwater benthic invertebrates were fluctuated in numbers and distribution mostly under the effect of the habitat they live in (spatially) than under the effect of season (temporally) in the present investigation.

SPATIAL AND TEMPORAL EFFECTS ON FRESHWATER BENTHIC INVERTEBRATES DIVERSITY IN SOME LOCALITIES OF MENOUFIA GOVERNORATE, EGYPT

Freshwater zoobenthos (macro-invertebrates) are organisms that live on, in, or near the bottoms of the freshwater. Their presence, abundance and species diversity are affected by numerous factors. This study was designed to evaluate temporal and spatial changes of benthic invertebrates’ diversity in the light of ecological conditions at the selected sites. Three sites at Menoufia governorate were selected as follows: site one and two are located at Bahr Shebeen El-Koom, Milig and Tanta branches, respectively. However, site three is located at Gezay Village, Menouf. Monthly samples were collected during one year from March, 2017 till February, 2018. Ecological parameters such as temperature, pH, total dissolved solids (TDS), electrical conductivity (EC)…etc., and heavy metals (Al, Ca, Cu, Fe and Pb) concentrations in sediment and tissues of the collected molluscs were measured. Environmental parameters showed variations in values from one season to another. The highest abundance of zoobenthos in all seasons was recorded at site three (42 %) followed by site one (32 %) and then site two (26 %). Three phyla were recorded during the present study; Annelida, Arthropoda and Mollusca. Diversity, variety and evenness indiceswere maximum at site three followed by site one then site two. Heavy metals concentrations in sediments and tissues of mlousca were maximum at site two followed by site one and finally site three. It is concluded that, the population density, species diversity and communities of freshwater benthic invertebrates were fluctuated in numbers and distribution mostly under the effect of the habitat they live in (spatially) than under the effect of season (temporally) in the present investigation.

Comparative study of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in corals, surrounding sediments and surface water at the Dazhou Island, China

This study investigated polycyclic aromatic hydrocarbons (PAHs) content in corals (Acropora sp.), surficial sediments, and surface seawater, and heavy metals (HMs) contents in corals and sediments from Dazhou Island, Hainan, China. Concentrations of PAHs in seawater and sediment seasonally ranged from 191.5 ng L−1 to 587.7 ng L−1, and from 37.9 ng g−1 to 233 ng g−1, while levels in corals were higher (185.2–545.0 ng g−1) compared to those found in sediments, demonstrating bioaccumulation of PAHs by corals. A similar seasonally variation of PAHs was observed in water/sediments and corals, and the proportions of low molecular weight PAHs (LPAHs) in seawater and corals were higher. Pyrolytic and petrogenic contaminations were identified to be the main sources of PAHs. Lower HMs concentrations were detected in corals (9.8–39.4 μg g−1) than in sediments (65.0–83.3 μg g−1), but HMs bioaccumulation still occurs in corals. Higher concentrations of HMs in sediment and corals were detected in March and December, especially Mn and Zn. Application of an enrichment factor showed that Cu in corals was delivered from non-crustal materials, and anthropogenic inputs were possibly the main sources. According to Biota Sediment Accumulation Factor, corals could strongly bioaccumulate LPAHs and Cd, and PAHs at a higher (p < 0.05) rate than HMs. There was a lack of correlation between the accumulation of PAHs and HMs in corals based on the cluster analysis. Dual hierarchical clustering analysis result revealed that feeding, instead of symbiosis, might be the main process responsible for the bioaccumulation of PAHs and HMs.

Hydrochemistry and heavy metals concentrations in sediment of Woji creek and Bonny estuary, Niger Delta, Nigeria

Physicochemical characteristics of the surface water and heavy metals levels in sediment of Woji creek and upper reaches of the Bonny estuary, Niger Delta, Nigeria were investigated between October, 2012 and September, 2014. Ten sampling stations were established along the main creek course based on accessibility and proximity gradient from expected pollution sources. Water and sediment samples were collected monthly at each sampling station for twenty four months, using Hydrobios Water Sampler and Van-veen grab respectively. Water samples were analysed in the laboratory following standard procedures. Heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb) levels in sediment were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The surface water temperature showed seasonal changes, pH (6.68 ± 0.7) showed spatio-temporal uniformity throughout the study period and Total Organic Carbon (TOC) was generally low (0.23 ± 0.06). There was no seasonal variation in Biochemical oxygen demand (BOD5). Salinity showed a positive correlation with pH and conductivity but negative correlation with temperature. Physicochemical properties of the water body were however, within Federal Ministry of Environment set limits for coastal water. The levels of heavy metals in sediments were in the order: Fe > Mn > Cu > Ni > Co > Zn > As > Cr > Pb > Cd. Sediments were found to have low levels enrichment of heavy metals from anthropogenic sources. This could be as a result of high tidal flushing in the study area. Pollution load index (PLI) and the degree of contamination (Cd) evaluated showed that sediment of the study area has low level of contamination from heavy metals and can be said to be relatively unpolluted.