Effect Range Median Research Articles

Environmental risks associated with trace elements in sediments from Cartagena Bay, an industrialized site at the Caribbean.

Cartagena Bay (CB) is an industrialized site in the Caribbean. The aim of this study was to evaluate contamination patterns by trace elements in sediments from CB. Sediment samples from twelve sites in CB, and three at the Grand Marsh of Santa Marta (GMSM), a reference site, were collected during dry and rainy seasons. Forty-four trace elements were evaluated employing ICP-MS, and mercury (Hg) was measured using a Hg analyzer. Most contaminated sites corresponded to stations related to repair and maintenance of ships, with high concentrations of Cr, Cu, As and Cd; as well as in areas where cargo transshipment centers and cruise ship terminals operate, which showed elevated levels of Ba. Stations receiving inputs from petrochemical and fertilizer plants displayed high content of Pb. At the station where an extinct chlor-alkali plant was located, a high total Hg level was found, highlighting its persistence. At least 70% of the samples presented Cr, Cu, and As concentrations that were ≥ Threshold Effect Level, < Probable Effect Level, ≥ Effects Range Low and < Effects Range Medium, suggesting adverse biological effects could occur occasionally. Potential Ecological risk values revealed that only Hg and Cd may generate deleterious effects to the aquatic life. However, with few exceptions, sediment samples from CB can be considered as moderately to heavily contaminated, as shown by the Igeo. In short, the principles of ecosystem-based management should be implemented along Cartagena Bay to guarantee safe levels of trace elements in sediments and a better quality of this estuary.

Assessment of trends and emission sources of heavy metals from the soil sediments near the Bohai Bay.

Anthropogenic emission sources (mainly vehicular and industrial emission) are one of the major emission sources of the heavy metals in aquatic ecosystems which have significant potential to perturb the marine geochemistry and ecosystem as well as human life also. In the present study, we tried to investigate the accumulation of heavy metals (Zn, Cr, Ni, Cu, Pb, Co, As, Cd, and Hg) at two sediment cores near the Bohai Bay in Southern Tianjin and reconstruct their historical trends over the last hundred years to understand the impacts of anthropogenic activities. The concentration of Zn and Cr is found maximum than the other studied heavy metals. Results suggest that in the mid-twentieth century, the maximum concentrations of Zn, Cr, Ni, Cu, and Pb are mainly because of the opening of Dagang Oilfield which emits a huge amount of heavy metals into the environment. Source apportionment analysis has been carried out using positive matrix factorization (PMF) model which suggests three major emission sectors of heavy metals, i.e., coal combustion, manufacturing, and smelting dust, having different contribution 32%, 40%, and 28% respectively to the total heavy metal burden. Industrial emissions are found to be the major sources of Cr, Ni, and Co while Pb is mainly originated from the coal combustion. The risk assessment analysis shows the value of mean effects range median (ERM) quotients ~ 0.17 for the two sediment cores which suggest nearly 21% toxicity of the studied metals indicating towards the policymakers for the mitigation of air pollution surrounding Tianjin.

Heavy metal contamination in representative surface sediments of mangrove habitats of Cochin, Southern India

Heavy metal contamination has threatened India’s biodiverse-rich coastal wetlands, backwaters, rivers, estuaries and mangroves due to unscientific industrial activities and urbanisation. Among the Indian states, the Cochin city is the commercial and economic hub of Kerala along the coastal belt of Arabian Sea. Mangroves located are on the backwater channels and along the banks of Cochin estuary are near victims of this commercialization. Therefore, a comprehensive analysis of the sediment quality focusing on heavy metal contamination and pollution problems are documented from the mangrove habitats of Cochin, considering their immense ecological services offered to the coastal communities with an insight for future restoration activities. Out of the 17 metals analysed, concentration of 6, largely exceeded NOAA effect range low (Cr (5.5–202), Cu (0.89–40.68), Cd (0–1.34), Hg (0–0.68)) and effect range medium (Ag (0–4.68), Ni (0.06–64.5)), which marks the probability of adverse biological effects on mangrove plants and animals. Enrichment factor analysis revealed extremely severe enrichment of Ag (EF = 133), Hg (18.8), Pb (17.8) and Cd (17) and was supported by PCA analysis, that clearly derived the anthropogenic influence of Ag, Cd and Hg in mangroves. Contamination factor, geoaccumulation index and pollution load index revealed that the mangrove sites of Cochin are nearly stressed due to contamination (CF = 66.8) and extreme pollution effects (Igeo = − 1.8–5.4) due to silver, and considerably contaminated (CF = 4.4) with Cd especially in Aroor and Vypin zones. However, Valanthakad zone was almost free from metal pollution having better sediment quality where mangrove vegetation had luxuriant growth.

Distribution, Geochemical Speciation, and Bioavailable Potencies of Cadmium, Copper, Lead, and Zinc in Sediments from Urban Coastal Environment in Osaka Bay, Japan

Due to proximity to the urban and industrial areas, coastal environments of the Osaka Bay have been continuously polluted with the human activities. Coastal sediments are known as large pool of contaminants including heavy metals. The Osaka Bay is no exception. However, recent information regarding the distributions, geochemical speciations, and risk evaluations of metals is limited for coastal sediments in the Bay. Therefore, we investigated the distributions, geochemical speciations, bioavailabilities, and conducted risk evaluations of the heavy metals, such as cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in sediments collected from 25 sites of the urban coastal environment of Osaka Bay, Japan. We observed high concentrations of Zn (76–967 mg/kg dry weight; DW) followed by Cu (not detected; ND-399 mg/kg DW), Pb (ND-73 mg/kg DW), and Cd (0.2–2.9 mg/kg DW). A considerable fraction of Cd was exchangeable (ND-0.4 mg/kg DW) and carbonate-bound (0.03–0.4 mg/kg DW). Cu occurred predominantly in the organic material-bound fraction (ND-348 mg/kg DW). Both Pb and Zn occurred predominantly in the Fe-Mn oxide fraction, with concentration ranges of ND-41 mg/kg DW and 24–277 mg/kg DW, respectively. Comparison with the effect range low (ERL) and effect range median (ERM) revealed that Cd, Cu, and Zn contribute potential biological toxicities to the sediments of Osaka Bay. High bioavailable concentrations of Cd and Zn may have ecotoxicological significance, because these metals are potentially highly available, especially to the benthic organisms.

Risk assessment and source apportionment of PAHs in surface sediments from Caofeidian Long Island, China

Sediment samples were collected from Caofeidian Long Island, China to investigate the contamination level and distribution pattern of 16 polycyclic aromatic hydrocarbons (PAHs). Source identification and risk assessment were also performed on these PAHs. The distribution patterns and source identification results indicated that the PAHs in the survey area originated from coal, biomass, and petroleum combustion as well as the combination of these three processes. Although the concentration of fluorene in the sediment exceeded the ERL level in some sampling sites, the effect range low–effect range median ratio implied a relatively low level of toxicity in these sediments. Meanwhile, the mean effects range–median quotient indicated that the 16 PAHs in sediments from Caofeidian Long Island pose a low ecological risk.

First report on probabilistic risk assessment of pesticide residues in a riverine ecosystem in South-South Nigeria

The present study evaluated the ecological and human health risk associated with concentrations of legacy organochlorine pesticide residues in Ikpoba River, a major River in the heart of Benin City, a Nigerian urban town located in Edo State. Standard methods were used to collect, extract and analyze samples, while risk assessment was carried out using standard models and indices. Results showed varying pesticide concentrations in both sediment and water samples with α-HCH (0.24 ± 0.11 μg L-l), predominant in water, whereas dieldrin (0.99 ± 0.33 μg kg-l) was the highest concentration in sediment. Compared to the Sediment Quality Guidelines (SQGs), this study concentrations of pesticides in sediments were below the values of effect range medium, effect range low, probable effect level and threshold effects level, suggesting low environmental hazard to benthic organisms. However, on exposure to contaminated sediments, probabilistic ecological risk assessment using Monte Carlo techniques showed potential risk to algae, daphnid and fish. Human health risk estimates using dermal and ingestion exposure deterministic and probabilistic routes revealed a potential risk to adults and children exposed to contaminated water and sediment. Estimates for detected pesticides exceeded the threshold level, indicating potential cancer effects for both children and adults who rely on the resources of the river. This study highlights the need for concerted efforts to curb the threat of pesticides and other contaminants in the aquatic environment by all relevant stakeholders in Nigeria and Africa as a whole.

Sediment characterisation and spatial distribution of heavy metals in the sediment of a tropical freshwater wetland of Indo-Burmese province

The sediment characterisation of wetlands belonging to the Northeastern Region of India particularly regarding the assessment of sediment carbon stock is very scanty. The presently available literature on the wetlands cannot be employed as a common model for managing the wetlands of the Northeastern Region of India as wetlands are a sensitive ecosystem with a different origin or endogenous interventions. Thereby, this research was conducted on Deepor Beel for investigating the spatial and seasonal variation of sediment parameters, the relationship between the parameters and pollution status of the wetland. Results revealed that the study area is of an acidic nature with a sandy clay loam type texture. Organic carbon, total nitrogen and available nitrogen were higher in sediments in the monsoon period. The mean stock of the sediment carbon pool of Deepor Beel is estimated to be 2.5 ± 0.7 kg m−2. The average non-residual fraction percentage (63.2%) of Pb was higher than the residual fraction. Zn content ∼490 mg kg−1 exceeding its effect range medium (ERM) was determined to suggest frequent biological adverse effects. Highest metal enrichment factor (EF) values were shown by Zn and Pb, which ranged between 78 and 255. Risk assessment code (RAC) values of Pb between 21 and 29% indicated its high bio-accessibility risk. Pearson's coefficient matrix revealed a low degree of positive correlation between organic carbon content and metal concentration. Principal component analysis revealed that the first component comprising of EC, basic cations and metals accounted for 62.3% of variance while the second component (OM, OC, TN, AN, AP) and the third component (pH) accounted for 21.8% and 7.0% of the variance, respectively. The present study revealed the adverse impact of human inputs on the Deepor Beel quality status.

Pollution status of arable soils and stream sediments in mining areas of Abakaliki, Lower Benue Trough, Nigeria

Geochemical assessment to determine the pollution status of arable soils and stream sediments of the lead–zinc mining areas of Abakaliki, Lower Benue Trough, was carried out. Major communities covered include Enyigba, Mkpuma Akpatakpa, Ameka, Amorie, Amanchara and Alibaruhu where active and abandoned mines are located, covering a total area of about 794.2 km2. One hundred and sixteen soil/stream sediments were collected in two seasons and analysed using Atomic Absorption Spectrophotometric method, and pedologic safety analytical tools including effect range low, effect range median, Multiple contamination, geoaccumulation index (Igeo), contamination factor (Cf), pollution load index and contamination degree were used to assess the impact level of mining activities in soils and sediments. Geological mapping and studies of rock types show that the area is underlain by shales, mudstone and thin beds of sandstone and limestone. Geochemical assessment shows high concentration of Cd, As, Pd, Cu and Zn especially in the mining sites, while pollution indices showed high pollution status for Ag < As < Pb < Hg < Cd in the area. Assessment of contamination degree shows a higher contamination degree for the Mkpuma Akpatakpa and Ameka areas than the for Enyigba and Amanchara areas. Arable soils around the mine sites and stream sediments of rivers which serve as disposal channels are not suitable for food crop production as biomagnification can occur in the food chain.

Vitória Bay Pollution Study in the Frame of the TAGUBAR Research Project: Geochemistry of the Sediments of Espírito Santo Bay

The Espírito SantoBay is located in Espírito Santo state in the eastern part of Brazil. It is surrounded by the city of Vitória on one side and by the Atlantic Ocean on the other. Superficial sediments of Espírito Santo Bay were analyzed at 12 (western shallow silt sediments) + 8 (eastern sandy sediments and relatively deep sampling stations) = 20 uniformly distributed sampling points, where geochemical analysis was performed. Nineteen elements were analyzed: Mo, Cu, Pb, Zn, Ag, Ni, Mn, Fe, As, U, Th, Sr, Cd, Sb, Bi, V, Cr, Ba, and Al. This selection was made based on the most representative heavy metals present in this area and according to the results obtained from the geochemical analysis. Their concentrations were compared with metal contamination benchmarks such asscreening quick reference tables (SQuiRTs), effects rangelow (ERL), effects range median (ERM), threshold effects levels (TELs), probable effects levels (PELs), and apparent effects thresholds (AETs). The results indicated that there was no particular pollution condition able to alter the condition of any part of this water body. The authors conclude that the Espírito Santo Bay is only moderately polluted, and some elements are virtually absent.

ExxonMobil and BASF Corporation demonstrate new solvent to decrease sulfur emissions

The sediment characterisation of wetlands belonging to the Northeastern Region of India particularly regarding the assessment of sediment carbon stock is very scanty. The presently available literature on the wetlands cannot be employed as a common model for managing the wetlands of the Northeastern Region of India as wetlands are a sensitive ecosystem with a different origin or endogenous interventions. Thereby, this research was conducted on Deepor Beel for investigating the spatial and seasonal variation of sediment parameters, the relationship between the parameters and pollution status of the wetland. Results revealed that the study area is of an acidic nature with a sandy clay loam type texture. Organic carbon, total nitrogen and available nitrogen were higher in sediments in the monsoon period. The mean stock of the sediment carbon pool of Deepor Beel is estimated to be 2.5 ± 0.7 kg m−2. The average non-residual fraction percentage (63.2%) of Pb was higher than the residual fraction. Zn content ∼490 mg kg−1 exceeding its effect range medium (ERM) was determined to suggest frequent biological adverse effects. Highest metal enrichment factor (EF) values were shown by Zn and Pb, which ranged between 78 and 255. Risk assessment code (RAC) values of Pb between 21 and 29% indicated its high bio-accessibility risk. Pearson's coefficient matrix revealed a low degree of positive correlation between organic carbon content and metal concentration. Principal component analysis revealed that the first component comprising of EC, basic cations and metals accounted for 62.3% of variance while the second component (OM, OC, TN, AN, AP) and the third component (pH) accounted for 21.8% and 7.0% of the variance, respectively. The present study revealed the adverse impact of human inputs on the Deepor Beel quality status.

Environmental significance and geochemical speciation of trace elements in Lower Baram River sediments

The geochemistry and distribution of major, trace and rare earth elements (REE's) was studied in the surface sediments of the Lower Baram River during two seasons: the Monsoon (MON) and Post – monsoon (POM). The major geochemical processes controlling the distribution and mobility of major, trace and REE's in the Lower Baram River surface sediments was revealed through factor analysis. The risk assessment of major and trace element levels was studied at three specific levels; i.e. the enrichment level [Contamination Factor (Cf), with the geo-accumulation index (Igeo)], the availability level [metals bound to different fractions, risk assessment code (RAC)], and the biological toxicity level [effect range low (ERL) and effect range medium (ERM)]. The results of all the indices indicate that Cu is the element of concern in the Lower Baram River sediments. The geochemical fractionation of major and trace elements were studied through sequential extraction and the results indicated a higher concentration of Mn in the exchangeable fraction. The element of concern, Cu, was found to be highly associated in the organic bound (F4) fraction during both seasons and a change in the redox, possibly due to storms or dredging activities may stimulate the release of Cu into the overlying waters of the Lower Baram River.

A comprehensive risk assessment of metals in riverine surface sediments across the rural-urban interface of a rapidly developing watershed

Metal contamination in aquatic environments is a severe global concern to human health and aquatic ecosystems. This study used several risk assessment indices, to evaluate metal (Cu, Zn, Pb, Cd and Cr) environmental risk of riverine surface sediments across the rural-urban interface of the rapidly developing Wen-Rui Tang River watershed in eastern China. Risk assessments were determined for 38 sites based on the potential ecological risk index (RI), consensus-based sediment quality guidelines (SQGs) and risk assessment code (RAC). Land-use cluster analysis showed that sediments were severely contaminated, especially for Cd, whose concentrations were ∼100 times higher than background levels and had a high proportion in the bioaccessible fraction. According to RI, ErCd was identified with extremely high risk potential, resulting in the highest ecological risk of Cluster 4 (industrial). Similarly, risk within Cluster 4 (industrial) was also ranked highest by SQGs assessment due to the high proportion of industrial land use. Zinc was determined with high risk due to its high concentration compared to its effect range medium (ERM) value. Discrepancies in predicting environmental risks from metals among the three indices were mainly attributed to the contrasting definitions of these metrics. Environmental risk uncertainty derived from spatial variation was further estimated by Monte Carlo simulation and ranked as: Zn > Cd > Cr > Pb > Cu. This comprehensive environmental risk assessment provides important information to guide remediation strategies for management of metal contamination at the watershed scale.

Assessment of Pb, Zn, As, Ni, Cu, Cr and Cd in Agricultural Soils around Settlements of Abandoned Lead-Zinc Mine in Mkpuma Ekwoku, South-eastern, Nigeria

This study was carried out to assess the level, distribution and the contamination status of Pb, Zn, As, Ni, Cu, Cr and Cd in agricultural soils around the settlements of Abandoned Lead-Zinc Mine in Nkpuma Ekwoku, Southeastern, Nigeria. The mean concentrations of the heavy metals, Pb, Zn, As, Ni, Cu, Cr and Cd are 109.55, 210, 1.83, 2.34, 8.24, 12.66 and 8.57 mg/kg respectively. The values obtained were compared with the established soil sediment standard by Canadian Council of Ministers of Environment (CCME). Generally most samples around the abandoned Pb/Zn mine show higher concentration of Pb, Zn, Cd, and Cr compare to individual Effect Range Low (ERL) values of the elements while Cu, and Ni were below both Effect Range Low (ERL) and Effect Range Medium values. However, Cd and Cr exceed the Effect Range Medium of the elements. Pollution Load Index (PLI) was found to be generally low in all the locations whereas the contamination factor (CF) values for metals like Pb, Zn and Cd are >1 while CF values of As, Cu, Cr and Ni are <1. The contamination is most probably resulted from the mineralized veins and mining of the ores. Keywords : heavy metals; soil contamination; lead-zinc; Mkpuma-Ekwoku

Sediment texture and metal contamination in the Venice Lagoon (Italy): A snapshot before the installation of the MOSE system

Sediments of the Venice Lagoon down to 50 cm depth were investigated to assess sediment texture and metal contamination status, before the construction and activation of the MOSE system, which is intended to prevent the periodical flood events affecting the lagoon and the city of Venice. 380 cores were collected in shallow-water areas of the lagoon, and analysed along their vertical profile to determine grain-size distribution and concentrations of some major and trace elements (Al, As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn), total carbon and organic carbon. Radionuclide analyses (137Cs, 210Pb) were performed on 15 cores in an attempt to establish sediment chronology and determine radionuclide inventories in erosional and depositional areas.On the whole-lagoon scale, strong depletion of particles <31 μm in diameter (from medium silt to clay fractions) was observed in sediments down to 10 cm depth in comparison to deeper layers. This depletion characterised both erosional and depositional areas, and may be caused by increased water dynamics and resuspension of sediment due to anthropogenic activities.The apparent sediment accumulation rate determined with 210Pbxs in depositional areas was estimated at 0.2–0.4 cm y−1. In the majority of cores, 210Pbxs inventories were lower than expected from atmospheric fallout, suggesting its export along with fine particles.The different sediment characteristics in terms of grain-size distribution and organic carbon content observed in the upper layer with respect to the deeper ones reflect the modification of the sedimentary balance in recent years. The loss of fine particles, even from sediments in depositional areas of the northern part of the lagoon, may herald changes in local sediment texture leading to a further depletion of morphodiversity, which in turn may lead to the reduction or loss of important lagoon habitats.On the whole-lagoon scale, the prevalently lithogenic elements (Al, As, Cr, Fe, Mn, Ni) decreased towards the top of the cores, reflecting the depletion of fine particles in the upper sediment layer due to winnowing in non-confined lagoon areas. In contrast, partly anthropogenic elements (Cu, Hg, Pb, Zn) increased up to the subsurface sediment layers (5–10 and/or 10–20 cm) as an effect of increasing pollutant inputs until a certain time in the past. Enrichment Factors (EF) were calculated from 9 cores, comparing concentrations in the “pre-industrial” (>100 years ago) and recent (surface layer, 0–5 cm) sediments. The mostly lithogenic elements were not enriched (EF ˜ 1), whereas the partly anthropogenic elements showed slight (Cu and Pb, EF ˜ 1.2) to significant (Hg and Zn, EF ˜ 2) enrichment. The shallow waters on the landward side (particularly close to freshwater inputs), the area nearby the industrial district of Porto Marghera and a small zone adjacent to the city of Chioggia were identified as the main pollutant accumulation sites. Mercury was the only element potentially harmful for aquatic life. Its concentration in the biologically active surface sediment layer (0–5 cm) exceeded the NOAA Effects Range-Median (ERM) value in 27% of samples, corresponding to 20% of the shallow-water surface area.The collected data set represents a valuable reference for monitoring the impact of the construction and operation of the MOSE system on the sediment features of the Venice Lagoon.

Distribution and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in sediments of different tropical water ecosystems in Niger Delta, Nigeria

Sediments are considered as suitable matrices to study the contamination levels of aquatic environment since they represent a sink for multiple contaminant sources. In this study, the influence of sediment characteristics on the distribution of polycyclic aromatic hydrocarbons (PAHs) and its potential risk in euryhaline, freshwater and humic aquatic bodies of Douglas/Stubbs creek, Ikpa River and Eniong River, respectively, were investigated. The level of PAHs in sediment was quantified using GC–MS, while sediment properties including total organic carbon (TOC) content and grain size were determined by the wet oxidation and hydrometer methods, respectively. The results revealed that the total levels of PAHs in sediment varied significantly between the euryhaline, freshwater and humic freshwater ecosystems. In Ikpa River freshwater ecosystem, a total PAHs load of 1055.2 ng/g was recorded with the suites concentration ranging from 13.0 ng/g (for acenaphthylene) to 161 ng/g (for pyrene). The humic ecosystem of Eniong River had a total PAH load of 11.06 ng/g, while the suites level recorded ranged from 0.04 ng/g for acenaphthene to 2.65 ng/g for chrysene. The total level of PAHs detected in the euryhaline Douglas/Stubbs creek was 14.47 ng/g, and suite concentrations varied between 4.27 ng/g for naphthalene and 5.13 ng/g for acenaphthylene. This shows variation in quantity and quality of PAH contaminants with the nature of ecosystems. It implies complex and diverse contamination sources as well as different capabilities to recover from PAH contamination. Correlation analysis has shown that sediment particle and TOC content influenced PAHs burden in bottom sediments, but the effects varied with the molecular weight of PAHs and the nature of the ecosystems. The TOC was the most significant determinant of PAHs load and distribution in sediment of the freshwater Ikpa River and euryhaline Douglas/Stubbs but had little or no influence in the humic sediment of Eniong River, while the influence of particle size was generally indefinite but slightly associated with PAHs accumulation in the euryhaline sediment. Generally, the total PAH levels (11.0–1055.2 ng/g) recorded were low and below the allowable limit for aquatic sediments. The ecological risk assessment revealed that these levels were lower than the effects range low and effects range medium values. This indicates no acute adverse biological effect although the accumulation of PAHs in freshwater ecosystem of Ikpa River may pose ecological risks as most of the carcinogenic PAH suites had relatively high pollution indices compared to other ecosystem types studied.

Distribution characteristics, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Haizhou Bay, China

ABSTRACTSixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography–mass spectrometry. Twenty samples were collected from the surface sediments of Haizhou Bay in this survey. This research aimed to identify the PAHs' contamination level, composition pattern, pollution sources, and assess the ecological risk of PAHs. The results showed that the sum of PAH concentrations ranged from 116.6 ng g−1 to 2414.9 ng g−1 (mean: 662.42 ng g−1), which is higher than the reported values for different wetlands worldwide. Three- and four-ring PAHs (accounts for more than 70% of the total PAH content) were predominant in the wetland sediment. The PAHs source distribution in the surface sediments were determined using diagnostic ratio and PCA/MLR. Consequently, multiple PAHs sources were found. Of the total PAH, 79.25% was derived from vehicular emission, 20.75% from coal combustion. The effect range low/effect range median (ERL/ERM) values indicated a low toxicity risk level. However, the fluoranthene concentrations exceeded the ERL level, and even the ERM level, in some stations. The mean effects range–median quotient (M-ERM-Q) suggests a low ecological risk for the PAHs in the sediments.

Assessment of streambed sediment contamination by heavy metals: The case of the Gabes Catchment, South-eastern Tunisia

This study deals with the assessment of the behaviour of seven heavy metals (Cd, Zn, Cu, Pb, Ni, Cr and As) in streambed sediments within the Gabes Catchment, located in South-eastern Tunisia. To understand the effect of intense human activities in the Gabes Basin on the quality of the environment, 22 sediment samples, spread all over the study basin, were taken and analyzed for heavy metals. Heavy metal concentrations were shown to vary in the following order: Zn > Pb > Cu > Cr > Ni > Cd > As. Sediment quality was assessed based on the evaluation of various indices. A total of 27% of the sampling stations are characterised by sediment Enrichment Factors (EF) exceeding 40, reflecting extremely severe pollution. This result was also confirmed by different indices, including Sediment Pollution Index (SPI), Pollution Load Index (PLI) and Geo-accumulation index. The calculation of Mean Effect Range-Median Quotient (M-ERM-Q) indicated that in stream discharge, all metals have a probability of 21% to be toxic. The ecological toxicity risk of heavy metals increases close to urban (traffic activity) and industrial activities (industrial complex of Gabes). Close to Gabes City, the situation and the degree of contamination that may be transferred into marine ecosystems is worrisome and requires immediate intervention.

Contamination levels and vertical distribution of trace metals with application of geochemical indices in the sediment cores of the Bizerte Lagoon-Ichkeul lake complex in northeastern Tunisia

The “Bizerte Lagoon-Ichkeul Lake complex” represents an ecosystem where the Tinja channel connected the Ichkeul Lake to the Bizerte lagoon. For a rigorous environmental assessment of pollution status, 17 core samples were collected in the complex area. The main purpose was to follow vertical distribution of trace metals and evaluate their potential contamination levels via an integrated geochemical approach. The collected samples were subjected to physicochemical characterization by several analytical techniques. Our results indicated that the mean concentrations of Cd, Cu, Pb, Mn, Zn, and Fe reached 2.31, 2.23, 33.22, 100.88, 40.79, and 605.05 mg/kg, respectively. They followed the order of Fe > Mn > Zn > Pb > Cd > Cu. The highest metal concentrations were found in samples close to industrial and urban areas transferred via the surrounding rivers. Those concentrations were lower than the effects range low (ERL), the effects range median (ERM), the threshold effect level (TEL), and the probable effect level (PEL), except for Cd and Pb. In addition, measured enrichment factor (EF), the geo-accumulation index (Igeo), and contamination factor (CF) proved the anthropogenic origin of all the potentially toxic metals studied. A low contamination for Cu, Mn, Zn, and Fe combined with very high contamination levels of Cd and Pb further confirmed the high anthropogenic input.

An ecological risk investigation of marine sediment from the northern Mediterranean coasts (Aegean Sea) using multiple methods of pollution determination.

The aim of this study is an assessment of metal pollution levels in Aegean Sea sediment. Sediment samples collected from 7 different locations (Yeniköy, Edremit, Ayvalık, Dikili, Aliağa, Hekimadası, and Ildır) along the northern Mediterranean region of Turkey were investigated for 11 elements (Cu, Fe, Zn, V, Cd, Ni, As, Pb, Mn, Co, and Cr). Graphite furnace atomic absorption spectrophotometry (GFAAS) and flame atomic absorption spectrophotometry (FAAS) were used for elemental analysis. The findings were evaluated with sediment assessment methods by taking two different values as a reference and then investigating the adverse biological effects of elemental profiles on living organisms. Pb, Mn, As, Cd, and Cr concentrations were within a moderate to significant range in terms of contamination factor [Formula: see text]), albeit varying according to reference and location. The most problematic region and elements regarding the enrichment factor (EF) was Ayvalık and As, Ni, Cu, Pb, Co, and Cd. However, according to the EF, the anthropogenic effect was not at an alarming level. This was further supported by the results of the geoaccumulation index (Igeo). The findings of the modified degree of contamination (mC d ) and the pollution load index (PLI) suggested that the accumulation was greatest in Ayvalık, and the least in Hekimadası and Ildır. The location with the highest elemental total toxic unit (ΣTU) was Edremit. The effect of the existing element profile on organisms was 21% in this location when the mean effect range-median quotient (m-ERM-q) was considered. As and Ni concentrations in all stations were found to be higher than threshold effect level (TEL) and Effect Range Low (ERL). Ni levels in Edremit exceeded the probable effect level (PEL) and Effect Range Median (ERM). Toxic unit (TU) values of these two elements in all stations ranged from 59.30 to 80.43%.

Quality Evaluation and Study of Ecological Toxicity of Heavy Metals in Shadegan Wetland

Wetlands hold a principal position in storing food for primary producers, so they are not able to bear the pressure. The slightest disturbance, hence, may harm wetlands and cause detrimental effects. The present study aims at monitoring heavy metals and evaluation of the sediment quality index of Shadegan wetland in Iran. Thus, a sampling of surface sediments of the wetland was performed at ten stations with three replications; after the preparation of samples with aqua regia, the concentrations of heavy metals were measured by atomic absorption spectroscopy. The quantification of sediment pollution using the contamination factor, contamination degree, pollution load index, ecological risk assessment index, and ecological toxicity of heavy metals in the region were all carried out. The results of Cf and Cd showed that the degree of zinc and copper contamination is low; however, the degree of lead contamination is moderate. Moreover, the obtained PLI was less than 1 indicating a lack of sediments contamination with heavy metals. The RI was less than 150 indicating a low risk of contamination. In addition, comparing the concentrations of elements with National Oceanic and Atmospheric Administration and Sediment Quality Guidelines showed slightly toxic and non-toxic sediments, respectively. Finally, based on a mixture of effect range median, all sediment samples are placed in the first category with less than 12% toxicity probability. Copyright © 2017 Journal of Contemporary Urban Affairs.