Trace Metal Profiles Research Articles

Assessment of bioaccumulation factors of trace metals for Upper Gangetic fish

The River Ganga basin is home to over 520 million people and 2500 species of flora and fauna, including several fish species. This study determines the bioaccumulation factors of fish for five trace metals, namely Cu, Fe, Zn, Mn, and Cr, in a stretch of the River Ganga in the upper Gangetic alluvial plain with limited industrial activities. The abundance of different trace metals in the water follows the order Fe > Zn > Mn > Cu > Cr. The concentrations in fish show a slightly different pattern and follow the relative quantitative order as Zn >≈ Fe >Mn > Cu >Cr. The trace metal levels in fish are well below the permissible limits set by various regulatory agencies. The bioaccumulation factor values are in order Zn>Cr>Mn>Cu>Fe. This stretch of the Ganga has not been extensively investigated for bioaccumulation by aquatic organisms. These values, therefore, represent site-specific baseline data for future anthropogenic activities that may affect the trace metal profile in this part of the Gangetic aquatic system. The study is also significant due to the presence of the Narora nuclear power plants, as the bioaccumulation factors of stable elements help predict the behavior of their radioactive counterparts and homologous elements in the environment.

Biogeochemistry of dissolved trace metals in the Bay of Bengal

The pronounced seasonal variation over the Bay of Bengal affects trace metals concentration and distribution. Trace metals distribution in the Bay of Bengal has been best characterized during spring and fall intermonsoon, while limited studies were conducted during the southwest monsoon. This study reports the full-depth profiles of trace metals, including dissolved iron, manganese, lead, cadmium, copper, and zinc (Fe, Mn, Pb, Cd, Cu, and Zn) in the Bay of Bengal (BoB) during southwest monsoon, from July to August 2013. At coastal and ocean scales, transect observations covering the entire water depth provided a comprehensive picture of the circulation and biogeochemical cycles of these elements in seawater during the southwest monsoon. Water samples were obtained from one station in the northeastern Indian Ocean (NR-1) and from three shallow coastal stations with maximum depths <60 m (BA-1, BA-3, and BA-5), as well as from three offshore stations with maximum depths exceeding 2000 m (MY-7, MY-9, and MY-11). In the surface layer (5 m depth), the trace metal concentrations at the shallow near-coastal station BA-5 were higher than those at the ocean station NR-1. Surface trace metal concentrations in offshore regions encompassing stations MY-11, MY-9, and MY-7 were relatively higher than those reported for other seasons in a similar salinity region, indicating seasonal variation associated with freshwater intrusion and coastal-derived input. Below the mixed layer depth, the trace metal/phosphate (P) ratio was higher than that previously reported in the eastern Indian Ocean, suggesting an input from continental margins and mildly reducing sediments, particularly for Fe, Mn, and Cu. Moreover, at intermediate depths (190–800 m), where the North Indian Central Water (NICW) is the main water mass, the Cd/P ratio (0.55 ± 0.11 nmol/μmol) deviated from the global trend (∼0.3 nmol/μmol) owing to oxygen-deficient conditions. Intriguingly, at some stations, specifically MY-9 and MY-7, the intermediate dFe concentrations were relatively higher than those at station NR-1 at the same depth. Continental margin sediment, water mass movement, and ventilation may control the transport of Fe from locations with high Fe concentrations, including near the continental shelf (station MY-11 in this study) and the Andaman Sea.

Health Risks from Intake and Contact with Toxic Metal-Contaminated Water from Pager River, Uganda.

Pollution of water resources is one of the major impediments to the realization of Sustainable Development Goals, especially in developing countries. The aim of this study was to investigate the physicochemical quality and potentially toxic element (lead and cadmium) concentrations in surface water sampled from Pager River, a tributary of the Nile River in Northern Uganda. Water samples (n = 18) were taken from six different points upstream (A, B, and C) and downstream (D, E, and F) of the river and analyzed following standard methods for their physiochemical properties. Atomic absorption spectroscopy was used to quantify lead and cadmium concentrations. Human health risks from ingestion and dermal contact with potentially toxic metal-contaminated water were calculated. The results obtained indicated that the mean temperature (27.7 ± 0.5-29.5 ± 0.8 °C), turbidity (40.7 ± 2.1-50.1 ± 1.1 NTU), lead (0.296 ± 0.030-0.576 ± 0.163 mg/L) and cadmium (0.278 ± 0.040-0.524 ± 0.040 mg/L) occurred at levels that surpassed their permissible limits as per World Health Organization guidelines for drinking water. Human health risk assessment showed that there are potential non-cancer risks from the ingestion of water from Pager River by adults, as the total hazard quotients were greater than one. These results emphasize the urgency to restrict the dumping of wastes into the river to minimize chances of impacting the Nile River, which flows northwards to the Mediterranean Sea. Further studies should perform routine monitoring of the river during both dry and wet seasons to establish the spatiotemporal variations of physicochemical, microbial, and trace metal profiles of the river and the associated health risks.

Nutrient and Trace Metal Profile of Smoked Notopterus afer from four Major Markets in Sierra Leone

The effects of smoking on the nutrient profile and trace metal levels in smoked knife fish ( Notopterus afer ) purchased from markets in four major districts of Sierra Leone was investigated. Concentrations of Cadmium (Cd), Lead (Pb), Zinc (Zn), Iron (Fe), Copper (Cu), and Manganese (Mn) in the smoked fish were determined. Fish samples were analyzed for proximate composition and heavy metal contents at the University of Ibadan, Nigeria. Proximate analysis was carried out using methods prescribed by AOAC while metal analysis was done using bulk scientific 200A atomic absorption spectrophotometer. Data was subjected to descriptive statistical analysis for easy understanding of results. ANOVA was used to test the multi interaction effect of locations, nutrients and metal levels. The Turkey’s post-hoc test (HSD) was used to determine differences in the assessed variables. All statistical calculations were performed with SPSS 20.0 version for windows. The results of nutrient profile for N. afer showed that the fish furnishes enough nutrients, especially the protein content, which ranged from 43.73 ± 5.06 to 53.26 ± 11.33. The levels of all metals in the fish were above the limits permitted by Food and Agriculture Organization of the United Nations and World Health Organization (FAO/WHO), European Community Regulation (EU) and European Commission (EC). Assessment of non-carcinogenic health hazard using Target Hazard Quotient (THQ) and Hazard Index (HI) suggested no concern from consumption of smoked N. afer bought from the selected markets. Cd level exhibited carcinogenic risk, while Fe and Zn showed significant health hazard risk (THQ &gt; 1). The estimated daily intake (EDI) of the metals through fish consumption was below the permissible tolerable daily intake. It can be concluded that there is no likely potential human health risk by consuming smoked fish from the selected markets. Keywords: Proximate composition , Trace metals, Notopterus afer , carcinogenic risk, hazard index, target hazard quotient. DOI: 10.7176/FSQM/115-05 Publication date: May 31 st 2022

Bioaccumulated trace metal profiles of Tympanotonus fuscatus, Periophthalmus barbarous and Guinearma (Sesarma) alberti collected from a perturbed freshwater mangrove swamp in Warri, Nigeria

Bio –concentrated levels of trace metals; Fe, Zn, Cu, Cd and Pb in three (3) freshwater mangrove fauna; Tympanotonus fuscatus (periwinkle), Periophthalmus barbarous (mudskipper) and Guinearma (Sesarma) alberti (West African Sesarmid Crab) was investigated utilizng atomic absorbance spectrophotometery. Faunal sampling was conducted at five (5) sites in the Falcorp wetland area of Warri, Delta State, once monthly for an eighteen (18) month period. Maximal mean Fe and Zn values; 349.7 9 µg/g, dried wt ±15.64 and 16.92 µg/g, dried wt ±1.65 were recorded for the respective mudskipper and crab samples while minimal mean Fe and Zn values; 124.14 µg/g, dried wt ±7.85 and 7.71 µg/g, dried wt ± 0.96 were documented for the digested periwinkle tissues. The differences in the mean Fe, Zn, Cu and Cd values was siginificantly different at different levels (P&lt;0.001, P &lt;0.01 and P&lt;0.05). The detection of significant bioconcentration of these metals especially Cd, is a possible indication of the wide reaching deletrious ecological effects of anthropogenic activities in the affected area.&#x0D; Keywords: Falcorp mangrove swamp, Bioaccumulation, Trace metal, benthic bio-indicator

Accumulation of trace metals in freshwater macroinvertebrates across metal contamination gradients.

Historical mining activities cause widespread, long-term trace metal contamination of freshwater ecosystems. However, measuring trace metal bioavailability has proven difficult, because it depends on many factors, not least concentrations in water, sediment and habitat. Simple tools are needed to assess bioavailabilities. The use of biomonitors has been widely advocated to provide a realistic measure. To date there have been few attempts to identify ubiquitous patterns of trace metal accumulation within and between freshwater biomonitors at geographical scales relevant to trace metal contamination. Here we address this through a nationwide collection of freshwater biomonitors (species of Gammarus, Leuctra, Baetis, Rhyacophila, Hydropsyche) from 99 English and Welsh stream sites spanning a gradient of high to low trace metal loading. The study tested for inter-biomonitor variation in trace metal body burden, and for congruence amongst accumulations of trace metals within taxa and between taxa across the gradient. In general, significant differences in trace metal body burden occurred between taxa: Gammarus sp. was the most different compared with insect biomonitors. Bivariate relationships between trace metals within biomonitors reflected trace metal profiles in the environment. Strong correlations between some trace metals suggested accumulation was also influenced by physiological pathways. Bivariate relationships between insect biomonitors for body burdens of As, Cu, Mn and Pb were highly consistent. Our data show that irrespective of taxonomic or ecological differences, there is a commonality of response amongst insect taxa, indicating one or more could provide consistent measures of trace metal bioavailability.

Bioaccumulation and changes of trace metals over the last two decades in marine organisms from Guangdong coastal regions, South China

Trace metal (Cr, Ni, Cu, Zn, Cd and Pb) exposures, distribution and bioaccumulation were investigated in marine organisms from Guangdong coastal regions, South China. The results showed that all of the selected metals were observed in marine organisms with a predomination of Cu and Zn. The metal exposure levels exhibited obvious variations between species with the decreasing order of crab>shellfish>shrimp>fish. The higher metals enrichment seen in shellfish and crab species primarily attributed to their living habits and the higher sediment background values of trace metals. Endpoint bioaccumulation factor (BAFfd) was used to characterize the bioaccumulation potentials of marine organisms to trace metals, of which Cu and Zn were the most accumulated elements. The exposure of trace metals in the cultured organisms was far lower than those in wild marine organisms, which is probably due to the effect of growth dilution. Comparisons with previous studies demonstrated that the concentration profiles of most trace metals declined over the last one to two decades, except Cu, that increased indistinctively.

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Trace metal (Cr, Ni, Cu, Zn, Cd and Pb) exposures, distribution and bioaccumulation were investigated in marine organisms from Guangdong coastal regions, South China. The results showed that all of the selected metals were observed in marine organisms with a predomination of Cu and Zn. The metal exposure levels exhibited obvious variations between species with the decreasing order of crab>shellfish>shrimp>fish. The higher metals enrichment seen in shellfish and crab species primarily attributed to their living habits and the higher sediment background values of trace metals. Endpoint bioaccumulation factor (BAFfd) was used to characterize the bioaccumulation potentials of marine organisms to trace metals, of which Cu and Zn were the most accumulated elements. The exposure of trace metals in the cultured organisms was far lower than those in wild marine organisms, which is probably due to the effect of growth dilution. Comparisons with previous studies demonstrated that the concentration profiles of most trace metals declined over the last one to two decades, except Cu, that increased indistinctively.

Health risk-oriented source apportionment of PM2.5-associated trace metals

In health-oriented air pollution control, it is vital to rank the contributions of different emission sources to the health risks posed by hazardous components in airborne fine particulate matters (PM2.5), such as trace metals. Towards this end, we investigated the PM2.5-associated metals in two densely populated regions of China, the Yangtze River Delta (YRD) and Pearl River Delta (PRD) regions, across land-use gradients. Using the positive matrix factorization (PMF) model, we performed an integrated source apportionment to quantify the contributions of the major source categories underlying metal-induced health risks with information on the bioaccessibility (using simulated lung fluid) and speciation (using synchrotron-based techniques) of metals. The results showed that the particulate trace metal profiles reflected the land-use gradient within each region, with the highest concentrations of anthropogenically enriched metals at the industrial sites in the study regions. The resulting carcinogenic risk that these elements posed was higher in the YRD than in the PRD. Chromium was the dominant contributor to the total excessive cancer risks posed by metals while manganese accounted for a large proportion of non-carcinogenic risks. An elevated contribution from industrial emissions was found in the YRD, while traffic emissions and non-traffic combustion (the burning of coal/waste/biomass) were the common dominant sources of cancer and non-cancer risks posed by metals in both regions. Moreover, the risk-oriented source apportionment of metals did not mirror the mass concentration-based one, suggesting the insufficiency of the latter to inform emission mitigation in favor of public health. While providing region-specific insights into the quantitative contribution of major source categories to the health risks of PM2.5-associated trace metals, our study highlighted the need to consider the health protection goal-based source apportionment and emission mitigation in supplement to the current mass concentration-based framework.

Trace Metal Profiles of Human Hair and Nail Samples Collected from Urban and Rural Areas of Zonguldak, Turkey

Hair and nail samples were collected during a period of October to December 2012 from 63 healthy subjects who have been living in Zonguldak for at least ten consecutive years. The subjects aged over 30 years and having no serious health problems were participated in the study. The methodology involved the collection, ultrasonic cleaning and microwave digestion of samples. The measurements of trace metals (As, Cu, Zn, Se, Cd, Pb, Cr, Fe and Ni) in samples were performed with inductively coupled plasma-mass spectrometry. The predominant metals determined in the both hair and nail samples were the essential metals with the decreasing concentrations in the order of Zn&amp;gt;Fe&amp;gt;Cu. Other metals determined in the hair samples followed the concentration order of Pb&amp;gt;Se&amp;gt;Ni&amp;gt;Cr&amp;gt;As&amp;gt;Cd, whereas in the nail samples, the order was Se&amp;gt;Ni&amp;gt;Cr&amp;gt;Pb&amp;gt;As&amp;gt;Cd. Subgroups were formed according to location and gender. Hair Se and Fe concentrations were significantly higher in urban residents. With regard to nail samples, the rural residents exhibited more elevated Fe levels significantly. Gender had a significant influence on the concentration of Zn and Cu in hair samples with females presenting higher values. However, the effect of gender on the trace metal concentrations in nail samples was negligible. The metal concentrations obtained for Zonguldak were within or below the values reported worldwide.

Dynamics and diagenesis of trace metals in sediments of the Changjiang Estuary

The seasonal dynamics and diagenesis of trace metals at two contrasting coastal sites were studied to determine the mechanism that drove the diffusive release of trace metals from sediments in the Changjiang Estuary. Porewater trace metal concentrations were 53.4–4829 nM for Zn, 11.0–344 nM for Cu, 7.75–221 nM for Cr, 2.71–61.1 nM for Co, 0.822–42.7 nM for Pb and 0.037–4.22 nM for Cd. The concentrations and profiles of trace metals in the porewater and solid phase displayed obvious regional and seasonal variations. This variation was mainly reflected in the surface layer and the depth of the suboxic and anoxic layers. Regionally, surface porewater trace metal concentrations in the seasonal hypoxic region were higher than those in the aerobic region due to changes in the redox conditions being beneficial to the release of trace metals. Seasonally, surface porewater trace metal concentrations decreased in summer compared to spring due to their removal by forming metal sulfides in summer. Solid profiles of the trace metals supported their dynamic variations in the porewater. The partition coefficient suggested that the formation of Fe/Mn (hydr)oxides was effective for the removal of trace metal in oxidizing condition, while the formation of sulfides was conducive to the removal of trace metals in reducing condition. The combination of porewater with solid phase data suggested that the dynamics of Cu, Zn, Cr and Co were mainly controlled by Fe and Mn diagenesis, the dynamics of Cd were affected by S cycling, and the dynamics of Pb were disturbed by anthropogenic inputs and benthic organism activities. Estimation of benthic fluxes indicated that sediments were an important source of trace metals in the water column. The contributions of trace metals by sediments to the water column of the Changjiang Estuary were only one order of magnitude lower than those by riverine fluxes.

Trace metal and isotopic depth profiles through the Abitibi cratonic mantle

Geophysical imaging of trans-lithospheric structures provide a spatial link between ore deposits in the crust and the underlying cratonic mantle. However, the deep lithosphere's role in ore deposit genesis remains poorly understood because remotely acquired datasets do not provide any direct constraints on the behaviour of ore elements within these mantle-roots. The abundance and behaviour of ore elements governs the metallic endowment of the cratonic mantle and the economic potential of mantle-derived magmas. Herein we present in situ electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) geochemical datasets for clinopyroxene and olivine mantle xenocrysts from the Jurassic Kirkland Lake kimberlite field, Abitibi greenstone belt, Canada. We specifically focus on unconventional trace elements, including ore elements with chalcophile and/or siderophile affinities (Ag-As-Au-Bi-Cu-Mo-Pb-Pt-Pd-Sb-Se-Sn-Te-W-Zn). Robust principal component analysis suggests that low-T, large-ion lithophile element alteration (Ba-Sr), which likely occurred during kimberlite emplacement, represents the largest source of variance for the xenocryst dataset. PT-dependent element partitioning during sub-solidus equilibration represents the second most important control on olivine and clinopyroxene chemistry. We demonstrate that least-altered, high-PT mantle silicates are, in fact, a significant mineral host for a range of ore elements (Cu-Zn ± Ag ± As ± Se ± Sn ± Mo) within equilibrated, garnet peridotite at depth (70–190 km). Statistical analysis of the raw, individual mass sweeps for each LA-ICP-MS signal suggest that the most abundant ore elements (Cu-Zn) occur predominantly as PT-dependent substitution reactions with the dominant mineral-forming elements, rather than as inclusions. A subset of high-PT olivine (160–180 km) yields Fe-Ni-S-poor and Na (Au ± Pt ± Pd)-rich compositions, which may reflect metasomatism, sulphide segregation and trapping of precious metal-bearing fluids at the base of the lithosphere. These anomalous mantle fragments possibly represent the first, direct sampling of precious metal-modified mantle peridotite beneath the Abitibi. Mid-PT olivine xenocrysts (70–120 km), which yield Mg-rich and high field-strength element-poor compositions, document a highly melt-depleted segment of mantle peridotite coincident with and below a shallow-dipping, low-seismic-velocity anomaly and conductive feature of the Kirkland Lake mid-lithosphere at 70–100 km. We speculate that the trace element signature of mid-PT xenocrysts documents the re-distribution of high-charge and incompatible elements from refractory garnet peridotite to phlogopite- and/or amphibole-bearing peridotite with conductive metasomatic up-flow zones. The rapid, sub-solidus diffusion of elements at high-T suggest that these processes likely occurred during, and/or immediately preceding, kimberlite volcanism. New in situ Pb isotope analyses of clinopyroxene xenocrysts sampled from metasomatized, low-Al garnet peridotite, however, also document ancient metasomatic events that likely pre-date Jurassic kimberlitic volcanism by at least one billion years.

Full-scale agricultural biogas plant metal content and process parameters in relation to bacterial and archaeal microbial communities over 2.5 year span

A start-up of 4 MW agricultural biogas plant in Vučja vas, Slovenia, was monitored from 2011 to 2014. The start-up was carried out in 3 weeks with the intake of biomass from three operating full-scale 1–2 MW donor agricultural biogas plants. The samples were taken from donor digesters and from two serial digesters during the start-up over the course of 2.5 years. Bacterial and Archaeal microbial communities progressively diverged from the composition of donor digesters during the start-up phase. The rate of change of Bacterial community decreased exponentially over the first 2.5 years as dynamics within the first 70 days was comparable to that of the next 1.5 years, whereas approximately constant rate was observed for Archaea. Despite rearrangements, the microbial communities remained functionally stable and produced biogas throughout the whole 2.5 years of observation. All systems parameters measured were ordered according to their Kernel density (Gaussian function) ranging from the most dispersed (substrate categories used as cosubstrates, quantities of each cosubstrate, substate dry and volatile matter, process parameters) towards progressively least dispersed (trace metal and ion profiles, aromatic-polyphenolic compounds, biogas plant functional output (energy)). No deficiency was detected in trace metal content as the distribution of metals and elements fluctuated within the suggested limits for biogas over 2.5 year observation. In contrast to the recorded process variables, Bacterial and Archaeal microbial communities exhibited directed changes oriented in time. Variation partitioning showed that a large fraction of variability in the Bacterial and Archaeal microbial communities (55% and 61%, respectively) remained unexplained despite numerous measured variables (n = 44) and stable biogas production. Our results show that the observed reorganization of microbial communities was not directly associated with impact on the full-scale biogas reactor performance. Novel parameters need to be determined to elucidate the variables directly associated with the reorganization of microbial communities and those relevant for sustained function such as the more in-depth interaction between TSOC, trace metal profiles, aromatic-polyphenolic compounds and ionic strength (e.g. electrical conductivity).

Chronology of anthropogenic impacts reconstructed from sediment records of trace metals and Pb isotopes in Todos os Santos Bay (NE Brazil)

The evolution of the impacts of anthropogenic activities in Todos os Santos Bay was evaluated by profiles of trace metals and Pb isotopes determined in sediment cores. Fluxes of metals increased up to 12, 4 and 2 times for Cu, Pb, and Zn, respectively, compared to those recorded in the beginning of the 20th century. Stable Pb isotopes identified a decommissioned lead smelter and burning of fossil fuels as the main sources of Pb. Most metals showed minor to moderate enrichment factors (EF<4), but Cu and Pb were highly enriched (EF=28 and 6, respectively) at the Aratu harbor. Temporal changes in sediments were associated to different activities, namely Pb smelting, burning of fossil fuels, maritime traffic, petroleum related activities, inputs of domestic effluents, and changes in land uses. The effects of the implementation of environmental policies to improve the waters of the bay could not be identified in the evaluated cores.

High-resolution profiles of trace metals assessed by DGT techniques in lake sediment porewaters

The technique of diffusive gradients in thin films (DGT) was applied to obtain high-resolution vertical profiles of trace metals in sediment porewater of a eutrophic lake, Lake Chaohu. All sampling sediments were under anaerobic conditions with Eh values below 0, the redox potential profile in M4 was relatively stable, and higher Eh values in M4 than that in M1 were observed due to hydrodynamic effects. Fe, Mn and As exhibited closely corresponding profiles due to the co-release of Fe and Mn oxides and the reduction of As. Higher Fe and Mn concentrations and lower As concentrations were observed in M1 of the western half-lake than those in M4 of the eastern half-lake due to different sources and metal contamination levels in the two regions. Cu and Zn showed increasing concentrations similar to Mn and Fe at 1–2 cm depth of sediments, while DGT measured Co, Ni, Cd and Pb concentrations decreased down to 3–4 cm in the profiles. Co, Ni, Cu, Zn, Cd and Pb showed insignificant regional concentration variances in the western and eastern half-lakes. According to the R(CDGT/Ccentrifugation) values, the rank order of metal labilities decrease as follows: Fe (>1) > Cu, Pb, Zn (>0.9) > Co, Ni, Cd (>0.3) > Mn, As (>0.1).

Ambient PM2.5 in the residential area near industrial complexes: Spatiotemporal variation, source apportionment, and health impact

This study systemically investigated the ambient PM2.5 (n=108) with comprehensive analyses of the chemical composition, identification of the potential contributors, and estimation of the resultant respiratory physician visits in the residential regions near energy-consuming and high-polluting industries in central Taiwan. The positive matrix fraction (PMF) model with chemical profiles of trace metals, water-soluble ions, and organic/elemental carbons (OC/EC) was applied to quantify the potential sources of PM2.5. The influences of local sources were also explored using the conditional probability function (CPF). Associations between the daily PM2.5 concentration and the risk of respiratory physician visits for the elderly (≥65years of age) were estimated using time-series analysis. A seasonal variation, with higher concentrations of PM2.5, metals (As, Cd, Sb, and Pb), OC/EC and ions (i.e., NO3−, SO42− and NH4+) in the winter than in the spring and summer, was observed. Overall, an increase of 10μgm−3 in the same-day PM2.5 was associated with an ~2% (95% CI: 1.5%–2.5%) increase in respiratory physician visits. Considering the health benefits of an effective reduction, we suggest that the emission from coal combustion (23.5%), iron ore and steel industry (17.1%), and non-ferrous metallurgy (14.4%), accounting for ~70% of the primary PM2.5 in the winter are prioritized to control.

Geochemical distribution, fractionation and contamination assessment of heavy metals in marine sediments of the Asaluyeh port, Persian Gulf

In this study, total concentration and speciation of heavy metals in sediments of the Asaluyeh, one of the Iran's largest commercial ports, are investigated. 48 sediment samples were collected and analyzed for trace and major elements. Sediment quality guidelines along with calculated enrichment factors and trace metal profiles indicate that Asaluyeh port is threated by contamination, especially with respect to Hg and Cu. Normalization to Sc indicated high enrichment factors in the sediments following the decreasing order of: Hg>Cu>As>Ni>Zn>Pb≈Cr≈Mn>Co≈V≈Fe≈Al. Hg displayed the greatest potential ecological risk factor among sampling stations. The results of sequential extraction procedure revealed that in some stations >50% of Mn, V, Cu and Zn occur in potentially mobile phases and therefore are more readily mobilized in the sediments of the study area.

The Dynamics of Benthic Respiration at a Mid-Shelf Station Off Oregon

Mid-shelf sediments off the Oregon coast are characterized as fine sands that trap and remineralize phytodetritus leading to the consumption of significant quantities of dissolved oxygen. Sediment oxygen consumption (SOC) can be delayed from seasonal organic matter inputs because of a transient buildup of reduced constituents during periods of quiescent physical processes. Between 2009 and 2013, benthic oxygen exchange rates were measured using the noninvasive eddy covariance (EC) method five separate times at a single 80-m station. Ancillary measurements included in situ microprofiles of oxygen at the sediment–water interface, and concentration profiles of pore water nutrients and trace metals, and solid-phase organic C and sulfide minerals from cores. Sediment cores were also incubated to derive anaerobic respiration rates. The EC measurements were made during spring, summer, and fall conditions, and they produced average benthic oxygen flux estimates that varied between −2 and −15 mmol m−2 d−1. The EC oxygen fluxes were most highly correlated with bottom-sensed, significant wave heights (Hs). The relationship with Hs was used with an annual record of deepwater swell heights to predict an integrated oxygen consumption rate for the mid-shelf of 1.5 mol m−2 for the upwelling season (May–September) and 6.8 mol m−2 y−1. The annual prediction requires that SOC rates are enhanced in the winter because of sand filtering and pore water advection under large waves, and it counters budgets that assume a dominance of organic matter export from the shelf. Refined budgets will require winter flux measurements and observations from cross-shelf transects over multiple years.

TRACE METAL PROFILE OF SOME FOODSTUFFS SOLD IN OZORO MARKETS, DELTA STATE, NIGERIA

An assessment was carried out in 2014 in two markets at Ozoro in Delta State, Nigeria on the trace metal profile of some foodstuffs: cassava (Manihot esculentus Crantz.), maize (Zea mays L.), okra (Abelmoschus esculentus L.) and sweet potatoes (Ipomoea batatas L.) with a view to establishing baseline information on their metal index. The results showed that lead, copper, arsenic, zinc and cadmium were present in the foodstuffs. Arsenic was the lowest while cadmium was the highest especially in okra, and copper in sweet potato. Based on the recommendation given by standard bodies like FAO and WHO, the amounts observed were below the tolerable limits recommended, which suggests sub-lethal toxicity in humans. With a gradual and steady bioaccumulation of these non-biodegradable elements, a risk of their rise to lethal levels with their inherent health risk could be envisaged; hence there is a need for monitoring metals in foodstuff. The study has great implication in food safety and environmental management.

The impact of urban expansion and agricultural legacies on trace metal accumulation in fluvial and lacustrine sediments of the lower Chesapeake Bay basin, USA

The progressively declining ecological condition of the Chesapeake Bay is attributed to the influx of contaminants associated with sediment loads supplied by its largest tributaries. The continued urban expansion in the suburbs of Virginia cities, modern agricultural activities in the Shenandoah Valley, the anthropogenic and climate driven changes in fluvial system hydrodynamics and their potential associated impacts on trace metals enrichment in the bay's tributaries necessitate constant environmental monitoring of these important water bodies. Eight 210Pb and 137Cs dated sediment cores and seventy two sediment grab samples were used to analyze the spatial and temporal distributions of Al, Ca, Mg, Cr, Cd, As, Se, Pb, Cu, Zn, Mn, and Fe in the waterways of the Virginia portion of the Chesapeake Bay basin. The sediment cores for trace metal historical fluctuation analysis were obtained in lower fluvial-estuarine environments and reservoirs in the upper reaches of the basin. The trace metal profiles revealed high basal enrichment factors (EF) of between 0.05 and 40.24, which are interpreted to represent early nineteenth century agricultural activity and primary resource extraction. Surficial enrichment factors on both cores and surface grab samples ranged from 0.01 (Cu) to 1421 (Cd), with Pb, Cu, Zn, and Cd enrichments a plausible consequence of modern urban expansion and industrial development along major transportation corridors. Contemporary surficial enrichments of As, Se, and Cr also ranged between 0 and 137, with the higher values likely influenced by lithological and atmospheric sources. Pearson correlation analyses suggest mining and agricultural legacies, coupled with aerosol deposition, are responsible for high metal concentrations in western lakes and headwater reaches of fluvial systems, while metal accumulation in estuarine reaches of the major rivers can be attributed to urban effluence and the remobilization of legacy sediments.