Assessment of the metal pollution, potential toxicity and speciation of sediment from Algeciras Bay (South of Spain) using chemometric tools

Occurrence, accumulation, ecological risk, and source identification of potentially toxic elements in multimedia in a subtropical bay, Southeast China

Potentially toxic elements (PTEs) in seawater and sediments may be amplified along the aquatic food chain, posing a health threat to humans. This study comprehensively analyzed the concentrations, distribution, potential sources, and health risk of 7 PTEs in multimedia (seawater, sediment and organism) in typical subtropical bays in southern China. The results indicated that Zn was the most abundant element in seawater, and the average concentration of Cd in sediment was 3.93 times higher than the background value. Except for As, the seasonal differences in surface seawater were not significant. The content of Zn in fishes, crustacea, and shellfish was the highest, while the contents of Hg and Cd were relatively low. Bioaccumulation factor indicated that Zn was a strongly bioaccumulated element in seawater, while Cd was more highly enriched by aquatic organisms in sediment. According to principal component analysis (PCA), and positive matrix factorization (PMF), the main sources of PTEs in Quanzhou Bay were of natural derivation, industrial sewage discharge, and agricultural inputs, each contributing 40.4 %, 24.2 %, and 35.4 %, respectively. This study provides fundamental and significant information for the prevention of PTEs contamination in subtropical bays, the promotion of ecological safety, and the assessment of human health risk from PTEs in seafood.

Origin and comprehensive risk assessment of heavy metals in surface sediments along the Caspian Sea

Metal concentrations (Cu, Zn, Cr, Fe, As, Pb, Ni, V, and Co) in surface sediments were determined in the southern Caspian Sea. Sediment pollution was investigated using geochemical index such as Enrichment Factor (EF) and ecological risk indices like modified Hazard Quotient (mHQ) and Toxic Risk Index (TRI). The highest calculated geochemical index was observed in sediments near the cities of Chalus and Ramsar, which are highly polluted due to human activities. The ecological potential indices indicated that Ni contents in all the studied stations would impose harmful effects on aquatic organisms, while other metals had a low risk. Principal component and cluster analyses suggested that As and Pb emanated from anthropogenic sources, and other metals probably originated from lithogenic sources.

Heavy metals contamination of seafood from the crude oil-impacted Niger Delta Region of Nigeria: A systematic review and meta-analysis

This study aims at computing the pooled mean estimate (PME) and health risks of heavy metals in seafood obtained from the Niger Delta Region of Nigeria (NDRN), using data from existing literatures. Pubmed, Scopus and Google Scholar were searched to retrieve articles that investigated the heavy metal contents of edible seafood from the NDRN. Search hits were screened against predetermined criteria following which relevant data were extracted from eligible articles. The PME for each metal was computed by performing a maximum likelihood random effect model meta-analysis using the R Studio Software. Outcome from the meta-analysis involving 58 studies and a total of 2983 seafood samples revealed the following PMEs (mg/kg dry wt seafood) for the investigated heavy metals: As (0.777), Cd (0.985), Co (4.039), Cr (2.26), Cu (11.45), Fe (143.39), Hg (0.0058), Mn (13.56), Ni (5.26), Pb (4.35), and Zn (29.32). The health risk assessment suggests that seafood from this region poses considerable carcinogenic and non-carcinogenic risks to human consumers. Our finding calls for urgent actions aimed at identifying and eliminating point sources of heavy metals pollution of the NDRN marine environment. Inhabitants of NDRN are encouraged to reduce seafood consumption while diversifying their protein sources to include non-seafood options.

An evaluation of spatial and seasonal distributions of dissolved trace metals in the water of the natural wetlands

The spatial and temporal distributions of trace metals in dissolved forms mainly result from anthropogenic and lithogenic contributions. Surface water samples (∼0.5 m) were collected monthly at respective stations from Setiu Wetland. In this study, the behaviour of trace metals in the dissolved phases along the water column from sampling sites in the Setiu Wetland, Malaysia was investigated. In addition, dissolved organic carbon (DOC) and physical parameters such as salinity, temperature, pH and dissolved oxygen (DO) of the surface water were measured in order to evaluate the relationship between trace metals fractionation with different water quality parameters. Size fractionation study of dissolved trace metals using ultrafiltration technique were also carried out and analysed using inductively coupled plasma mass spectrometry (ICP-MS). Correlation of trace metals with other measured parameters was made to furthermore understand the dynamics of trace metals and its fractionated components in this area. The concentration of dissolved trace metals was in the range of 0.001-0.16 μg/L for Cd, 0.12-2.81 μg/L for Cu, 0.01-1.84 μg/L for Pb, 3-17 μg/L for Fe and 1-34 μg/L for Zn, suggesting the input of anthropogenic sources for trace metals such as municipal, industrial, agricultural and domestic discharge. The periodic monitoring and evaluation of trace metals in wetlands and protected tropical areas is highly recommended.

Sport fishing and vessel pressure on the endangered cetacean Delphinus delphis. Towards an international agreement of micro-sanctuary for its conservation

Delphinus delphis Linnaeus 1758 is considered an endangered species in the Mediterranean. The species is resident in the Bay of Algeciras - Gibraltar (southern Spain; waters partially shared with Gibraltar, UK). This area is subject to strong anthropogenic pressure, but with an input of renewed waters in its central area. During three consecutive years (March 2017-March 2020), sightings were observed concentrated along the submarine canyon that runs north to south across the bay, forming a "specular S″ with a maximum depth of 460 m. The pods of Dd showed a continuous or semi-continuous spatial distribution along the vertical axis of the submarine canyon, where they feed, mate, breed and rear calves in a well-defined area that constitutes a critical habitat. This area has been cartographically delimited, choosing the area of maximum dolphin frequency as highly vulnerable due to the possibility of collisions with small vessels (<15 m) and interactions with sport fishing activities (popping, ballooning, trolling) which constitute the main threat counting the derived impacts from noise pollution. Spatio-temporal mapping has been developed to visualize the overlapping between the dolphin groups and small vessels. Mapping analysis has shown that an international Spanish-British micro-sanctuary urgently needs to be established in order to create a protected area specifically for the common dolphins, and for other species which inhabit/use the waters between Spain and Gibraltar. Coordinates and a delimited surface area have been proposed in this paper.

Speciation and risk assessment of Zn, Pb, and Cd in bottom sediments of two small upland dam reservoirs, Poland

Sediments of two small dam reservoirs in Poland, Zalew Zemborzycki (ZZ) and Brody Iłżeckie (BI), were studied. Sediments from both reservoirs were sampled at 17 sites in the transects perpendicular to the shoreline, at the river inflow and the frontal dam and analysed using the BCR procedure for speciation of zinc (Zn), lead (Pb) and cadmium (Cd). The risk assessment code (RAC) and the individual contamination factor (ICF) were determined. In BI, the sediments were removed from the considerable part of the reservoir, creating an opportunity to study the effect of dredging on the speciation of trace metals. Trace metals partitioning was differentiated according to the transect/site and in the case of BI sediments also on the transect location in the dredged or undredged part of the reservoir. Considering ZZ sediments, the order of fractions for Zn, Pb and Cd according to a decreasing overall mean percentage contribution to total metal content was the same: F4 (residual) >F3 (oxidisable) >F2 (reducible) >F1 (acid soluble). In sediments of ZZ at most sites, the RAC for Zn, Pb and Cd revealed low or medium risk and ICF low or moderate contamination. For BI sediments, the order of fractions for Pb was similar while for Zn and Cd quite the opposite compared to the sediments of ZZ and it was: Pb-F4>F3>F1>F2, Zn-F1>F3>F2>F4, Cd-F1>F2>F3>F4. For BI sediments, RAC values for Zn, on average, indicated high and very high ecological risk; for Pb low and moderate risk and for Cd - high risk in the initial part and dredged part and according to the average value in the reservoir, while a medium risk in undredged part sediments. The ICF index showed high contamination with Cd for all BI sediments. The sequential analysis showed that Pb is poorly mobile as in sediments of both reservoirs residual fractions accounted, on average, for about 60% of the total content.

Pollution assessment and mapping of potentially toxic elements (PTE) distribution in urban wastewater fed natural wetland, Kolkata, India

East Kolkata Wetland (EKW) is one of the largest sewage-fed wetlands in the world, which support the livelihood of thousands of peoples. However, at present, EKW system has become ecologically vulnerable due to the discharge of toxic waste through the sewage canal from the Kolkata metropolitan city. Hence, it becomes very important to understand the inflow and load of potentially toxic elements (PTE) in the sediment, water, and fish of sewage-fed wetland used for aquaculture activities. In this study, one of the polluted wetland from EKW, Sardar bherry, was selected as the study area. Sediment samples (45) were collected from 15 sites to characterize the PTEs concentrations levels utilizing inductively coupled plasma mass spectrometry, and their spatial distribution pattern and pollution quality indices were estimated. Water (45) and fish (7) samples were also analyzed to understand the distribution pattern of PTEs from sediment to water and water to fish. The geostatistical prediction map showed that the concentration range of Cr, Fe, Cu, Co, Zn, Cd, Ni, Pb, and Mn in sampling stations were 27.3-84.1 μg g^-1, 7281-30193 μg g^-1, 50.6-229.7 μg g^-1, 4.8-15.3 μg g^-1, 113.4-776.9 μg g^-1, 10.0-26.9 μg g^-1, 23.8-55.7 μg g^-1, 9.5-39.3 μg g^-1, and 188.6-448.5 μg g^-1 respectively. Pollution is alarming in sediment as all of the studied PTEs exceed the threshold effect level according to Sediment Quality Guidelines. Cd levels in sediments were found to be upper than the lowest effect level (LEL), probable effect level (PEL), threshold effect level (TEL), and severe effect level (SEL) for all sample locations. Several pollution assessment indexes (contamination factor, geo-accumulation index, ecological risk index, etc.) also showed that sediment samples were severely polluted by Cd. PTEs status in water and fish is within permissible limits. The study emphasizes that attention should be paid to controlling the excessive accumulation of PTEs in sediment that would further harm the ecological environment and ultimately human health.

Effects of biowaste-derived biochar on the dynamic behavior of cadmium fractions in soils

As a commonly used amendment to soil contaminated by heavy metals, biochar has attracted great attention and has been applied for decades due to the benefits to the soil. However, the effects of biochar on the dynamic behavior of soil properties and metal fractions are still unclear. Here, we used two biochars, derived from biowastes (reed and bamboo willow), to treat two cadmium (Cd)-contaminated soils, S1 (loamy sand) and S2 (sandy loam), and determined the dynamic effects. The incubation experiments were designed to investigate the effects of biochar on the dynamic behavior of soil pH, dissolved organic matter (DOM), bioavailable Cd, and the transformation of Cd fractions for 270 days. The results showed that the soil pH, DOM, and bioavailable Cd initially increased and then decreased with incubation time, and the soil pH and DOM were higher, but bioavailable Cd content was lower than the original value. The transformation of the metal fractions changed dynamically, and the exchangeable fraction of Cd decreased with incubation time. Furthermore, the correlation results showed that the DOM can directly control the redistribution of Cd fractions, while soil pH can control it indirectly by regulating the DOM. This study highlighted that biochar can affect soil pH and DOM, redistribute Cd fractions, decrease bioavailable Cd content, and lower the potential risk of heavy metals. This study suggests ways to immobilize heavy metals in contaminated soils using biochar.

Environmental Assessment of Potentially Toxic Elements Using Pollution Indices and Data-Driven Modeling in Surface Sediment of the Littoral Shelf of the Mediterranean Sea Coast and Gamasa Estuary, Egypt

Coastal environmental assessment techniques have evolved into one of the most important fields for the long-term development and management of coastal zones. So, the overall aim of the present investigation was to provide effective approaches for making informed decisions about the Gamasa coast sediment quality. Over a two-year investigation, sediment samples were meticulously collected from the Gamasa estuary and littoral shelf. The inductively coupled plasma mass spectra (ICP-MS) was used to the total concentrations of Al, Fe, Ti, Mg, Mn, Cu, P, V, Ba, Cr, Sr, Co, Ni, Zn, Pb, Zr, and Ce. Single elements environmental pollution indices including the geoaccumulation index (Igeo), contamination factor (CF), and enrichment factor (EF), as well as multi-elements pollution indices comprising the potential ecological risk index (RI), degree of contamination (Dc), and pollution load index (PLI) were used to assess the sediment and the various geo-environmental variables affecting the Mediterranean coastal system. Furthermore, the Dc, PLI, and RI were estimated using the random forest (RF) and Back-Propagation Neural Network (BPNN) depending on the selected elements. According to the Dc results, all the investigated sediment samples categories were considerably contaminated. Cr, Co, Ni, Cu, Zr, V, Zn, P, and Mn showed remarkable enrichment in sediment samples and were originated from anthropogenic sources based on the CF, EF, and Igeo data. Moreover, the RI findings revealed that all the samples tested pose a low ecologically risk. Meanwhile, based on PLI, 70% of the Gamasa estuary samples were polluted, while 93.75% of littoral shelf sediment was unpolluted. The BPNNs -PCs-CD-17 model performed the best and demonstrated a better association between exceptional qualities and CD. With R2 values of 1.00 for calibration (Cal.) and 1.00 for validation (Val.). The BPNNs -PCs-PLI-17 models performed the best in terms of measuring PLI with respective R2 values of 1.00 and 0.98 for the Cal. and Val. datasets. The findings showed that the RF and BPNN models may be used to precisely quantify the pollution indices (Dc, PLI, and RI) in calibration (Cal.) and validation (Val.) datasets utilizing potentially toxic elements of surface sediment.

Adsorption Characteristics of Modified Eucalyptus Sawdust for Cadmium and Arsenic and Its Potential for Soil Remediation

In order to explore the utilization of Eucalyptus sawdust (C) and develop its remediation potential in cadmium and arsenic contaminated soil, Eucalyptus sawdust were modified by FeCl₃ and NaOH coprecipitation (MC). Characterization technology and pot experiment were used to explore the adsorption mechanism of cadmium and arsenic by MC and the effect of soil remediation. The results showed that iron oxide was loaded on the surface of Eucalyptus sawdust and destroyed the semi fiber structure. The adsorption mechanisms of cadmium and arsenic included electrostatic attraction, precipitation, complexation, redox. The soil pH value reduced by 0.12-0.18 units with 0.25%-1% ratio of application rates of MC to soil weight treatment; The contents of available cadmium and arsenic were reduced by 18%-25% and 12%-18%; MC could promote the transformation of Cd and As from highly active formation to low active formation and had a good application prospect for Cd and As compound pollution remediation.

Geochemical assessment of trace element concentrations in the Farmington River, Connecticut, Northeastern, USA

The Farmington River, located in the northeastern USA, originates from Massachusetts and flows through several towns until it joins the Connecticut River in Windsor, Connecticut. Trace element concentrations within the drainage systems of the Farmington River are a growing concern, largely due to the presence of both historical and present land use activities along the river that include mining, farming, urbanization, industrialization, landfills, and shooting gun ranges. This study examined the impact of land use activities and geology on the chemical signature of major and trace elements within the Farmington River. A total of seventy-eight (78) stream sediment and corresponding water samples were collected and analyzed for twenty-one chemical elements (As, Be, Ca, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sr, Ti, Tl, V, and Zn) and basic river sediment parameters such as particle size distribution and organic matter contents. Results showed spatial variability in the concentration of elements along the river flow path, with the highest concentrations of As, Cd, Ni, Zn, and Pb determined at location FR31 due to various human activities within the surrounding environment. However, most sampling locations do not pose a major environmental concern. Multivariate statistical analysis showed inter-relationship among most elements, with a weak but significant positive relationship with fine particle sizes in sediment. Results of principal component analysis (PCA) suggested a combination of both geogenic and anthropogenic sources of trace elements to the Farmington River system.

Microbial adaptation to co-occurring vanadium and microplastics in marine and riverine environments

Vanadium (V) and microplastics have been respectively detected in environmental media, posing threats to ecosystem and human health. However, their co-existence situations in environment with microbial adaptation have been poorly understood. In this study, water and sediments collected from potential V polluted marine and riverine ecosystems were analyzed to reveal the distribution of V and microplastics with microbial responses. High concentrations of V (1.65-6.92 μg/L in water and 6.16-347.92 mg/kg in sediment) and microplastics (800-15600 item/m³ in water and 20-700 item/kg in sediment) co-occurred in aquatic environment. Less rich and diverse bacterial communities were colonized on microplastics compared to surrounding environment. Plastic-degrading taxa (e.g., Ralstonia, Rhodococcus) and V(V) reducers (e.g., Bacillus, Pseudomonas) were enriched in microplastic biofilms. Redundancy analysis showed that V, together with nutrients, ambient conditions and Cr, contributed significantly to the compositions of microbial community on microplastics. Besides directly acting on microbial community, V could also alter it by influencing environmental factors (e.g., pH), as indicated through structural equation model. This study advances understanding the previously ignored interactions of biogeochemical processes of V and microplastics in aquatic environment.

Assessing heavy metals in surface sediments of the Seomjin River Basin, South Korea, by statistical and geochemical analysis

We investigated particle size distribution and heavy metal concentrations in surface sediments of streams and lakes in the Seomjin River Basin by comparison with Sediment Quality Guidelines (SQGs). Origins were identified using statistical and geochemical approaches. Sand was prevalent in mean particle size of surface sediments (except lakes). Mean concentrations of Pb, Zn, Cd, and Hg were similar for the Seomjin and Boseong rivers, while those of Cu, As, Cr, and Ni were approximately 1.5-2.0 times higher in the Boseong. SQGs revealed no serious pollution in the basin's site concentrations, although As and Ni levels in the Boseong had some potential for benthos toxicity. Correlation and principal component/factor analysis showed that concentrations of Cu, As, Cr, and Ni were dominant from geological origins rather than anthropogenic. The reducible fraction bound to Fe and Mn-oxides was prevalent in Pb, while the water- and acid-soluble fractions were easily exchangeable or bound to high Cd carbonates. The fraction bound to the highest lattice in residual prevailed in Zn, Cu, Cr, and Ni, accounting for 64%, 65%, 87%, and 86%, respectively. Similarly, results indicated geological origins. Risk assessment to benthos based on labile fractions (F1 + F2 + F3) were Cd (72%) < Pb (66%) < Zn (36%) ≈ Cu (35%) < Ni (14%) ≈ Cr (13%). While Cd and Pb showed the highest risk, their concentrations were relatively lower. However, Cr and Ni showed the highest concentrations but low risk levels, suggesting their pollution is unlikely to have adverse effects on benthos.

Ecological and human health risk assessment of trace element pollution in sediments and five important commercial fishes of the Oman Sea

The distribution of trace elements in sediments and five commercially important fish species of the Oman Sea were assessed using an atomic absorption spectrometer to determine ecological and human health risk assessment. The ranges of trace elements concentration in sediments were: Cr: 5.42-68.94, Zn: 5.22-18.11, Cu: 1.44-4.87, As: 18.07-79.96, Cd: 0.10-1.27, Ni: 43.0-65.34 and Pb: 8.92-30.53 mg/kg dry weight. Cr, Zn, Cu, Cd and Pb were below the ERL (effects range low) and TEL (threshold effect level) values at all the sampling stations with rarely biological effects. Whereas, As and Ni were higher than ERL and TEL with occasionally biological effects. The patterns of trace elements bioaccumulation in the tissues of all species were: liver> skin> gill> muscle. A significant positive correlation suggests that trace elements accumulation in fish is determined by trace elements in sediments. Estimated Daily Intake (EDI) was significantly lower than the tolerable daily intake (TDI) value. Target Hazard quotient (THQ), total target hazard quotient (TTHQ) and target carcinogenic risk (TR) values indicated no hazard risk from fish consumption. Hence, the consumption of concerned species to people in the Oman Sea is safe.

Spatial-temporal dynamics, ecological risk assessment, source identification and interactions with internal nutrients release of heavy metals in surface sediments from a large Chinese shallow lake

The surface sediment concentrations of heavy metals (Cu, Zn, Pb, Cd, Cr, Hg, and As), major metals (Fe and Mn), and the nutrient concentrations in the interstitial water of Lake Houguan, a large eutrophic shallow lake, were surveyed for three years. The results showed that Cu, Zn, and Fe were significantly higher in the east lake parts, and Cd in November was significantly higher than April. 19% of Hg and all of As were larger than the probable effect concentrations (PECs) according to the consensus-based sediment quality guidelines (SQGs), and the geo-accumulation index (I_geo) indicated As, Hg, and Cd were slightly polluted to severely polluted. The RI value (average 704.2) of the potential ecological risk index (PERI) suggested that heavy metals posed very high ecological risks with most of the contributions induced by Cd and Hg. The consequence of hierarchical clustering analysis (HCA) and principle component analysis (PCA) identified Cd, As, and Pb might originate from urbanization, industrial pollution, and agricultural activity; Hg might be from atmospheric deposition and anthropogenic sources above; Cu, Zn, Cr, Fe, and Mn might be from both natural and anthropogenic sources. The Spearman correlation analysis indicated Pb and As were significantly positively correlated with total nitrogen, while Cd significantly negatively correlated with sulfate; As was significantly correlated with ammonia, sulfate, and nitrate in the interstitial water. These results suggested eutrophication might affect sedimental heavy metals by increasing organic matter or influencing the redox potentials in the sediment.

Assessment of bottom sediment quality in Niterói harbor (Brazil, South America) through ecological indexes concerning nutrients and trace metals

Bottom sediment quality from the Niterói harbor at Guanabara Bay (Rio de Janeiro, Brazil) was evaluated based on concentrations of organic phosphorus (OP) and inorganic phosphorus (IP) and bioavailability of trace metals through BCR fractionation analysis (Zn, Cu, Pb, Cr, Ni, Cd). The study area revealed elevated concentrations of fine sediments and organic matter (TOC: 2.26-7.31%). OP presented extremely elevated concentrations between 0.57 and 47.04 μmol/g, whereas IP reached a maximum concentration of 4.99 μmol/g. The anoxic bottom at the study area was confirmed by high TOC/OP values in most stations. Phosphorus enrichment index (PEI) varied between 0.07 and 2.57, pointing to ecological risk at some stations. Trace metals were mostly bonded to the bioavailable fractions (exchangeable, reducible, oxidizable), and decreasing order of mobility was Zn > Cu > Pb > Cr > Ni > Cd. The Risk Assessment Code (RAC) suggested a high risk of bioavailability for Zinc and a medium risk for the other metals. Overall, the Niterói harbor revealed poor sediment quality suggesting a strong anthropogenic pressure in the area.

Risk assessment of potentially toxic elements in stream sediments around granite quarries, barite mines, and cultivation areas, Southeastern Nigeria

This study assessed the contamination of streams with potentially toxic elements (PTEs) in sediments around mining, quarrying, and cultivation areas in Akamkpa and environs Southeastern Nigeria. Analysis done using ICP MS technique shows that barium (Ba) and lead (Pb) recorded mean concentrations above their average shale content (ASC) in stream sediments. Chromium (Cr) exceeded Canadian Interim Sediment Quality Guideline (ISQG) and US Environmental Protection Agency (USEPA) screening benchmark value. Pb exceeded Canadian ISQG value but tallies with USEPA benchmark value. Pearson's correlation exhibited significant correlation (p < 0.01) of molybdenum (Mo) with copper (Cu) and Pb; Cu with Pb, vanadium (V), and Ba; V with Cu, Pb, iron (Fe), Ba, and beryllium (Be); and Fe with Be and V. Principal component (PC 1) consists of Pb, Mo, cobalt (Co), Cu, arsenic (As), Cr, V, and nickel (Ni) and showed significant correlation. Geo accumulation index (I-geo) values for Mo, Cu, V, Pb, Zn, Ni, Co, Mn, and Ba fall under unpolluted (0) to moderately polluted (1-2) classes. Maximum enrichment factor (EF) values show extremely high and significant enrichment of Ba and Pb in few locations. Co, Cr, Cu, Mn, and Zn possess maximum EF values classified as moderate enrichment. Ni, Mo, As, and V obtained maximum EF values classified as depleted to minimal enrichment. Modified pollution index (MPI) values showed high PTEs contamination in mostly cultivation locations. Single element potential ecological risk (EⁱR) mean values trend EⁱR (As) > EⁱR (Pb) > EⁱR (Co) > EⁱR (Cr) > EⁱR (Cu) > EⁱR (V) > EⁱR (Ni) > EⁱR (Zn). Comprehensive potential ecological risk (RI) shows medium risk "B" and strong risk "C" levels in few locations. The use of multiple pollution indices such as I-geo, EF, EⁱR, and RI in pollution assessment indicated similar trend of PTEs contamination of stream sediments. Levels of PTEs contamination are elevated in cultivation areas more than in granite quarrying and mining areas. This study serves as a benchmark for conducting suitable environmental management strategies to scientists in Nigeria and other parts of the world.

Cadmium, Chromium, and Cobalt in the Organs of Glyceria maxima and Bottom Sediments of the Pisa River and Its Tributaries (Poland)

The aim of the presented article was to determine whether human activity significantly influenced the enrichment of Cd, Co, and Cr, in river sediments and Glyceria maxima, in the basin of the Pisa River, an underdeveloped area in Poland. In this study, the content and spatial distribution of Cd, Cr, and Co in the organs underground and above ground, (sequentially: root, stem, leaf) of Glyceria maxima and bottom sediments of the Pisa River and its tributaries (Pisza Woda, Wincenta, Turośl and Skroda River) were analyzed. The Potentially toxic elements (PTEs) were determined by ASA method (Atomic Absorption Spectrometry). The results showed that the average PTEs contents in the river sediments occurred in the following descending order of Cd < Co < Cr. The highest values of the Igeo, CF coefficients, i.e., the greatest impact of anthropogenic activities on the water environment of the Pisa River and its tributaries, were found especially in the case of Cd. The research on the plant material has shown that the highest content of Cr and Co occurs in the roots, then in the stems, and the least in the leaves of Glyceria maxima. However, the amounts of Cd in the examined parts of Glyceria maxima had similar values. The content of Cd, Cr, and Co in the roots and above-ground parts exceeded the physiological values. Glyceria maxima can be used as a biological indicator material. Statistical analyzes showed the movement of PTEs in the sediment-root-stem-leaf system and identified the sources of PTEs, i.e., municipal wastewater treatment plants, the local food industry, and surface runoff.

Spatial distribution, contamination assessment and potential ecological risk of some trace metals in the surface sediments of the Gulf of Tunis, North Tunisia

To evaluate the trace metals contamination status in the Gulf of Tunis, forty one sediment samples were analyzed using different approaches. According to certain contamination and ecological risk indices (Contamination Factor, Geoaccumulation index and Ecological risk index), Hg has the highest contamination level while pollution by Ni, Pb, Cd and Cr was absent. The highest concentrations of trace metals were found in sediments collected from the offshore and coastal areas located opposite the main exchange points with the gulf particularly, the Mejerda and Meliane Rivers, the Khalij Channel, Ghar El Melh and El Malah lagoons, Tunis Lake and Sebkhat Ariana. However, further ecological indices (Potential ecological risk index, Toxic unit and Mean effect-range median quotient) and comparison with sediment quality guidelines suggest that in addition to Mercury, Cr, Pb and Ni concentrations are detrimental to biota in both the offshore and areas near to the exchange points with the gulf. Moreover, in these areas the results from sequential extraction and individual contamination factor calculation pointed to the mobility and bioavailability of Cr, Pb and Ni.

Concentrations of arsenic and vanadium in environmental and biological samples collected in the neighborhood of petrochemical industries: A review of the scientific literature

Petrochemical facilities, including oil refineries, are emission sources of a wide range of environmental pollutants such as trace elements, volatile organic compounds, and polycyclic aromatic hydrocarbons, among others. Populations living near this kind of facilities may be potentially exposed to contaminants, which are, in turn, associated with a wide range of adverse effects. In our laboratory, we have shown that the environmental concentrations of trace elements near the petrochemical complex of Tarragona County (Spain), which is among the largest complexes in the European Union, should not be a relevant pollution source for these elements, with the exception of arsenic (As) and vanadium (V). Moreover, the International Agency for Research on Cancer (IARC) classified As and V as Group 1 and Group 2B, respectively. Based on it, the present paper was aimed at reviewing the available scientific information on the occurrence of As and V in the vicinity of petrochemical complexes worldwide, considering environmental matrices (air, dust, sediments, soil, and water), as well as biological samples (blood, hair, and urine). In general, levels of As and V in environmental matrices showed higher fluctuation throughout the world and was highly dependent on the samples zone while levels of both elements in urinary samples from subjects living near a petrochemical area were higher than those of population living further.

Assessment of trace inorganic contaminates in water and sediment to address its impact on common fish varieties along Kuwait Bay

The impact of the trace elements on selected marine fishes/crustacean in Kuwait (Sheam, Lobster, Speatty, and Nagroor) were investigated (As, Cd, Ni, Pb, and V) using the element concentrations in marine water and sediments. The toxic elements concentrations were measured in water samples (As, Cd, Cr, Cu, Hg, Ni, Pb, V, and Zn) for estimation of toxic levels, heavy metal evaluation index (84-360), and the degree of contamination (77-353). Similarly, sediment samples were analyzed for As, Cd, Cr, Cu, Ni, Pb, V and estimated for contamination factor, I_geo index, and ecological risk factor with respect to each element analyzed in the sample. The modified degree of contamination (0.25-3.67), risk index (6.5-282.27), metal pollution index (5.95-18.21), and pollution load index (0.27-1.2) were calculated for the samples. This study demonstrated that the water was medium to high contaminated with Cd, Hg, Pb, and V. The sediment analyses showed that most of the metals were within the toxic limits except for Cd, Cu, and Pb in few samples. Most samples were in between the effect range low-effect range medium and threshold effect level-probable effect level range of most metals, except for Cr, Cu, and Ni. Average trace elements concentration in fishes varieties investigated in this study indicated high As in all varieties irrespective of the season and high Ni in all fish during summer. The bioaccumulation factor showed that the trace elements in sediments contributed more to the fish than water. Concentrations of trace elements were greater in fish sampled in winter than that sampled in summer due to variations in the planktonic population in the sea. The estimated daily intake and the chronic daily intake for the Kuwaiti male and female were calculated. The hazards studied revealed that the consumption of Lobster and Speatty may lead to cancer and non-cancer hazards, in both male and female, Speatty having higher probability. The major sources of toxic elements contamination of Kuwait Bay water and sediment appear to be oil-based contamination, urban sewage, brine from desalination, and the trace elements released due to the natural oxidation-reduction processes.

Ciliates as model organisms for the ecotoxicological risk assessment of heavy metals: A meta-analysis

Ciliates are key components of aquatic ecosystems, significantly contributing to the decomposition of organic matter and energy transfer to higher trophic levels. They are considered good biological indicators of chemical pollution and relatively sensitive to heavy metal contamination. In this study, we performed a meta-analysis of the available toxicity data of heavy metals and ciliates to assess: (1) the sensitivity of freshwater ciliates to different heavy metals, (2) the relative sensitivity of ciliates in comparison to the standard test species used in ecotoxicological risk assessment, and (3) the difference in sensitivity across ciliate taxa. Our study shows that the tolerance of ciliates to heavy metals varies notably, which is partly influenced by differences in methodological conditions across studies. Ciliates are, in general, sensitive to Mercury > Cadmium > Copper > Zinc > Lead > Chromium. Also, this study shows that most ciliates are more tolerant to heavy metal pollution than the standard test species used in ecotoxicological risk assessments, i.e., Raphidocelis subcapitata, Daphnia magna, and Onchornyncus mykiss. Threshold concentrations derived from toxicity data for these species is expected to confer sufficient protection for the vast majority of ciliate species. Our data analysis also shows that the most commonly tested ciliate species, Paramecium caudatum and Tetrahymena thermophila, are not necessarily the most sensitive ones to heavy metal pollution. Finally, this study stresses the importance of developing standard toxicity test protocols for ciliates, which could lead to a better comprehension of the toxicological impact of heavy metals and other contaminants to ciliate species.

Bioaccumulation and health risk assessment of trace metals in fish from freshwater polyculture ponds in Chengdu, China

The freshwater polyculture pond culturing occupied an important position in the aquaculture industry. Accumulation of trace metals was investigated in water, sediments, and fish (Carassius auratus, Cyprinus carpio, Ctenopharyngodon idellus) from typical polyculture ponds in Chengdu, China. The results showed most of the pond water in Chengdu were safe for fish cultivation. The Cd and Cr concentrations in sediment samples from sites S3, S4, and S9 which were near the industrial park and road with a high traffic volume were higher than those of the other sites. Cu, Cr, Fe, Zn, Mn, Ni, and Pb in sediments were unpolluted, while Cd was unpolluted to moderately polluted due to anthropogenic activities. Cu, Cd, and Pb in fish pond sediment of Chengdu had higher potential mobility under normal environmental circumstances. The trace metal concentrations in liver of three fish species were all higher than those in muscle tissues. The order of bioaccumulation factor (BAF) values for trace metals was Cr > Cu > Pb > Zn > Cd > Ni > 20. The concentrations of Cu, Cd, Pb, Zn, and Cr in the muscle of three fish species were all below the local and international maximum permissible levels. The target hazard quotient (THQ) and hazard index (HI) of trace metals in aquaculture fish ponds in Chengdu were lower than 1, which indicated that the consumption of grass, crucian, and common carp cultivated in the aquaculture ponds of Chengdu pose no health risk to the residents.

Assessment of heavy metal pollution, distribution and quantitative source apportionment in surface sediments along a partially mixed estuary (Modaomen, China)

The aim of this study is to investigate the distribution, ecological risk and quantitative source apportionment of seven heavy metals in surface sediments along a partially mixed estuary (Modaomen, China). The study area was divided into three regions based on salt-freshwater mixing: a tidal river channel, weakly mixed zone and strongly mixed zone. The concentrations of Cu, Zn, Pb, Cd, Cr and Ni were significantly higher in the weakly mixed zone, while a higher Co content was found in the tidal river channel. From enrichment factor (EF) analyses, Cd was moderate to extreme severely enriched at most stations, and other heavy metals were minor enrichments. Adverse effects on aquatic biota may occur occasionally for all seven heavy metals based on the sediment quality guidelines (SQGs). The correlations between Al and heavy metals suggested that metals in sediments were mainly attributed to anthropogenic sources. Then Positive matrix factorization (PMF) and Geostatistic method were used to quantify the heavy metal sources and determine impacted regions. A mixed source from the inner Lingding Bay and West River contributed approximately 50% of the Cu, Zn, Pb, Cr and Ni. The electroplating industry accounted for about 57% of the Cd content, and the major contaminated area was concentrated at the confluence of the West River and its tributaries. The alloy industry contributed approximately 65% of the Co, most of which was near an industrial park.

Improved heavy metal mapping and pollution source apportionment in Shanghai City soils using auxiliary information

Soil heavy metal pollution can be a serious threat to human health and the environment. The accurate mapping of the spatial distribution of soil heavy metal pollutant concentrations enables the detection of high pollution areas and facilitates pollution source apportionment and control. To make full use of auxiliary soil properties information and show that they can improve mapping, a synthesis of the Bayesian Maximum Entropy (BME) theory and the Geographically Weighted Regression (GWR) model is proposed and implemented in the study of the Shanghai City soils (China). The results showed that, compared to traditional techniques, the proposed BME-GWR synthesis has certain important advantages: (a) it integrates heavy metal measurements and auxiliary information on a sound theoretical basis, and (b) it performs better in terms of both prediction accuracy and implementation flexibility (including the assimilation of multiple data sources). Based on the heavy metal concentration maps generated by BME-GWR, we found that the As, Cr and Pb concentration levels are high in the eastern part of Shanghai, whereas high Cd concentration levels were observed in the northwestern part of the city. Organic carbon and pH were significantly correlated with most of the heavy metals in Shanghai soils. We concluded that Cd pollution is mainly the result of agricultural activities, and that the Cr pollution is attributed to natural sources, whereas Pb and As have compound pollution sources. Future studies should investigate the implementation of BME-GWR in the case of space-time heavy metal mapping and its ability to integrate human activity information and soil category variables.

Bioavailability and Assessment of Metal Contamination in Surface Sediments of Rades-Hamam Lif Coast, around Meliane River (Gulf of Tunis, Tunisia, Mediterranean Sea)

The total concentration and the speciation of heavy metals (Pb, Cd, Cu, Zn, Ni, and Cr) in surface sediments of Rades-Hamam Lif coast were determined, with particular focus on the effect that urban and industrial waste in the Meliane river has on the estuary and coastal surface sediments of the Rades-Hamam Lif coast, off the Mediterranean Sea. Several geochemical indices were applied to assess the risk of contamination and the environmental risks of heavy metals on surface sediments. The total concentrations of these heavy metals are influenced by runoff, industrial, and urban wastewater. The Cd, Pb, Zn, and Ni are affected by anthropogenic sources, especially at the mouth of the Meliane river. The sequential extraction of Cd was presented dominantly in the exchangeable fraction and thus the high potential bioavailability. In contrast, Cr and Cu were mostly bound to the residual fraction indicating their low toxicity and bioavailability. The order of migration and transformation sequence was Cd > Pb > Ni > Zn > Cr > Cu, and the degree of pollution was Cd > Pb > Ni > Zn > Cr > Cu.

Metals Pollution and Ecological Risk Assessment of Sediments in the Poyang Lake, China

The concentrations of several metals and their geochemical species in surface sediment from Poyang Lake main channel and its tributary entrance were analyzed. Results showed that the concentrations of Cu (28.1-213 mg/kg), Zn (82.6-257 mg/kg), Pb (49.8-81.4 mg/kg) and Ni (33.5-56.0 mg/kg) were higher than the background values, while Cd (0.15-0.81 mg/kg) was lower. Zn, Cu and Ni were predominately bound to residual fraction. The content of Pb in the Fe-Mn oxides fractions was considerable. And Cd had highest concentration of exchangeable and carbonate fractions. The geoaccumulation index showed that the sediments were unpolluted with Cd, moderately polluted with Pb, Zn and Ni, while moderately to heavily polluted by Cu. Principal component analysis indicated that Ni was mainly lithogenic in origin and Cu, Pb, Zn and Cd were influenced by anthropogenic contamination. The concentrations of Cu, Pb and Zn were above the threshold effects level (TEL) but below the probable effects level (PEL), Cd was below TEL, whereas the contents of Ni were above PEL. The potential ecological risk index showed Cu posed moderate ecological risks, Cd, Ni, Pb and Zn posed low ecological risk. The general ecological risk belonged to the high risk.

Assessment of heavy metal contamination in surface sediments along the Mediterranean coast of Morocco

In this paper, heavy metal contamination in surface sediments along the Mediterranean coast of Morocco was investigated. Determining pollution degree as well as heavy metal origins were the main objectives of this investigation. For this reason, concentrations of nine heavy metals (Cd, Cu, Cr, Ni, Pb, Zn, Hg, Fe, and Mn) were analyzed at ten stations sampled during three different periods. The obtained concentrations showed significant variation between sampling periods, which was controlled by several environmental and chemical processes. According to contamination indices results using pollution load index (PLI), modified contamination degree (mC_d), geoaccumulation index (I_geo), enrichment factor (EF), and potential ecological risk index (RI), sampling stations were classified between uncontaminated and strongly contaminated without detecting any intense heavy metal pollution in surface sediment. Likewise, the EF values were comprised between no enrichment and moderate to severe enrichment. According to sediment quality guidelines, the calculated M-ERM-Q indicated that heavy metal mixtures have between 9 and 49% probability for being toxic. This result revealed lowest to medium-low potential of adverse effects to biota populations. Regarding heavy metal origins, multivariate statistical investigation showed that Cd, Cu, Hg, Pb, and Zn are derived mainly from anthropogenic activities, while Fe, Mn, Cr, and Ni were derived from natural sources. Despite Cd is considered as a typical anthropogenic metal, the very low concentrations obtained in this study support the involvement of natural factor in the enrichment with this metal. Therefore, the surface sediments contamination along the Mediterranean coasts of Morocco is particularly caused by a combination of anthropogenic and natural factors. As a result, the study area can be considered as not significantly enriched by human activities.

Spatial distribution and ecological risk assessment of the coastal surface sediments from the Red Sea, northwest Saudi Arabia

To assess the spatial distribution and ecological risk assessment along the Red Sea coast, Saudi Arabia, 30 samples were collected for aluminum, chromium, copper, zinc, cadmium, lead, mercury, iron, cobalt, nickel and organic matter analysis. The descending order of metal concentrations was Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Hg > Cd. Average values of enrichment factor of Hg, Cd, Cu, Co, Cr, Ni, Pb and Zn were higher than 2 (209.50, 25.52, 20.36, 9.62, 7.28, 6.52, 6.21 and 6.07 respectively), which means anthropogenic sources of these metals. The average levels most of the studied metals were lower than those of the background shale and the earth crust and those recorded along most worldwide coasts, while the average values of zinc, copper, cobalt and nickel were higher than the values recorded from the Red Sea coast, the Gulf of Aqaba and some Caspian Sea coasts. The Duba bulk plant-Saudi Aramco, Duba refinery station and the tourist resort were the possible anthropogenic sources of pollutants in the southern part of the study area; and the landfilling, cement factory and Duba port and shipment operations in the central part, while the landfilling resulting from construction of the green Duba power plant and crowded fish boats were the possible sources in the northern part.

Levels and ecological risk assessment of heavy metals in surface sediments of fishing grounds along Algerian coast

The level and the ecological risk assessment of heavy metals (Zn, Cu, Mn, Fe, Ni, Cr, V, As, Pb, Cd and Co) were evaluated in surface sediments from fifty-one stations along the Algerian coast. The main objective was to evaluate the risk that such metals may cause to the ecosystem, and thus the stations were choose in relation with the fishing trawlable areas of Algeria. The usual chemical indexes Geoaccumulation index (Igeo), Enrichment factor (EF) and Pollution Load Index (PLI) as well as potential ecological risk index reveal that the metal pollution along this coast is low, and is only related to As contents. Nevertheless, the concentrations of Ni, Cr and As exceed their respective ERL values (Effect range low) usually applied for Sediment Quality Guideline. However, Cr and Ni are mainly natural and cannot be related to anthropogenic inputs and their ecotoxicological levels as to be questioned.

Relation between different metal pollution criteria in sediments and its contribution on assessing toxicity

Several tools have been developed and applied to evaluate the metal pollution status of sediments and predict their potential ecological risk assessment. To date, a comprehensive relationship between the information given by these sediment tools for predicting metal bioavailability and the effective toxicity observed is lacking. In this work, the possible inter-correlations between the data outcoming from using several qualitative evaluation tools of the sediment contamination (contamination factor, CF, the enrichment factor, EF, or the geoaccumulation index, Igeo), metal speciation on sediments (evaluated by the modified BCR sequential extraction procedure) and free metal concentrations in pore waters were studied. It was also our aim to evaluate if these assessment tools could be used for predicting the pore waters toxicity data as toxicity proxy. Principal component analysis and cluster analysis revealed that two quality indices used (CF and EF) were highly correlatable with the more labile fractions from BCR sediment speciation. However, neither of these parameters did correlate with the toxicity of pore waters measured by the chronic toxicity (72 h) in Pseudokirchneriella subcapitata. In contrast, the toxic effects of the given total metal load in sediments were better evaluated by using an additive metal approach using pore water free metal concentrations.

Contamination and ecological risk assessment of heavy metals and metalloids in surface sediments of the Tajan River, Iran

This study's objectives were to evaluate the elements degree of contamination in the Tajan River and the status of contamination in this river for future ecotoxicology studies. Based on geo-accumulation index (I_geo) and contamination factor (CF) indices, Cr, Mn, Fe, Ci, Ni and Zn showed low contamination levels at all stations, while Se showed a very high degree of contamination. Potential ecological risk factor (E_rⁱ) and risk index (RI) indices values showed low ecological risk for the river, and this was confirmed by the pollution load index (PLI) results as well as a comparison of the concentrations of these elements with the mean values of the earth's crust and sediments worldwide. Overall, the results showed that the river cannot be regarded as a contaminated river with respect to the elements studied (with the exception of selenium and arsenic) for ecotoxicology studies, but can be considered a reference river.

Enrichment, spatial distribution of potential ecological and human health risk assessment via toxic metals in soil and surface water ingestion in the vicinity of Sewakht mines, district Chitral, Northern Pakistan

This study focuses on enrichment, spatial distribution, potential ecological risk index (PERI) and human health risk of various toxic metals taken via soil and surface water in the vicinity of Sewakht mines, Pakistan. The samples of soils (n = 54) of different fields and surface water (n = 38) were analyzed for toxic metals including cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn) and molybdenum (Mo). Soil pollution level was evaluated using pollution indices including geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (CD), enrichment factor (EF) and PERI. CF showed moderate contamination of soil with Cd, Co, Fe and Mo, while Igeo values indicated moderate accumulation of Cu. For Cd, EF> 1.5 was found in agricultural soils of the study area. PERI findings presented a very high ecological risk (PERI > 380) at two sites (4%), considerable ecological risk at four sites (7.4%). Non-carcinogenic risk from exposure to Fe in soil was higher than limit (HI > 1) for both children and adults. Moreover, carcinogenic risk postured by soil contaminants i.e. Cd, Cr, Co and Ni in children was higher than their limits (except Pb), while in adults only Co posed higher risk of cancer than the limit (10^-4) through soil exposure. Non-carcinogenic risks in children due to Cd, Co, Mo via surface water intake were higher than their safe limits (HQ > 1), while in adults the risk order was Cr > Cd > Cu > Pb > Co > Mo. Moreover, carcinogenic risk exposure due to Co > Cd > Cr > Ni from surface water (except Pb) was higher than the tolerable limit (1 × 10^-4) both for children and adults. However, Pb concentrations in both soil and surface water exposure were not likely to cause cancer risk in the local population.

Heavy Metal Contamination and Ecological Risk Assessment of Swine Manure Irrigated Vegetable Soils in Jiangxi Province, China

Heavy metal are often added to animal fodder and accumulate in the soils with swine manure. In this study, heavy metal (Cu, Pb, Cd, Zn, As and Cr) concentrations were determined in agricultural soils irrigated with swine manure in Jiangxi Province, China. Results showed that the average concentrations of Cu, Zn, As and Cr (32.8, 93.7, 21.3 and 75.8 mg/kg, respectively) were higher than the background values, while Pb and Cd (15.2 and 0.090 mg/kg, respectively) were lower than the background values. Contamination factors [Formula: see text] indicated that they were generally moderate for Cu, Zn, As and Cr and generally low for Pb and Cd. The contamination degree (C _d ) was calculated to be 7.5-10.0 indicating a moderate degree of contamination. The geoaccumulation index (I_geo) indicated that the soils were unpolluted with Zn, Cd and Pb, while unpolluted to moderately pollute with Cr, Cu and As. The single ecological risk factor [Formula: see text] revealed that the six heavy metals all belonged to low ecological risk. The ecological risk indices suggested that all the sampling sites were at low risk level.

Distribution and metal contamination in the coastal sediments of Dammam Al-Jubail area, Arabian Gulf, Saudi Arabia

Present work aims to document the distribution and metal contamination in the coastal sediments of the Dammam Al-Jubail area, Saudi Arabian Gulf. Twenty-six samples were collected for Al, V, Cr, Mn, Cu, Zn, Cd, Pb, Hg, Sr, As, Fe, Co and Ni analysis. Results of enrichment factor indicated that Sr, Cd, Cu, Hg, V, As, Ni, Cr and Zn gave enrichment factors higher than 2 (98.87, 40.28, 33.20, 27.87, 26.11, 14.10, 6.15, 3.72 and 2.62 respectively) implying anthropogenic sources, while Pb, Mn and Al have very low background level (1.37, 0.71, 0.124 respectively), probably originated from natural sources. Average concentrations of Sr, V, Hg, Cd and As were mostly higher than those from the background shale and the earth crust, the Caspian Sea, the Mediterranean Sea, the sediment quality guidelines, the Red Sea, the Gulf of Aqaba and the Gulf of Oman. The higher levels of the studied metals are mostly related samples with high Al and TOM content, as well as the visible anthropogenic pollutants along the studied coastline. The most recorded anthropogenic pollutants were sewage effluent, landfilling due to coastal infrastructure development, oil spills, petrochemical industries and desalination plants in Al-Jubail industrial city.

Spatial distributions, fractionation characteristics, and ecological risk assessment of trace elements in sediments of Chaohu Lake, a large eutrophic freshwater lake in eastern China

The concentrations, spatial distribution, fractionation characteristics, and potential ecological risks of trace elements (Cu, Pb, Zn, Cr, Ni, and Co) in the surface sediment samples collected from 32 sites in Chaohu Lake were investigated. The improved BCR sequential extraction procedure was applied to analyze the chemical forms of trace elements in sediments. The enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (PERI), and risk assessment code (RAC) were employed to evaluate the pollution levels and the potential ecological risks. The results found that the concentrations of Cu, Pb, Zn, Cr, Ni, and Co in the surface sediments were 78.59, 36.91, 161.84, 98.87, 38.92, and 10.09 mg kg^-1, respectively. The lower concentrations of Cu, Pb, Zn, Cr, and Ni were almost found in the middle part of the lake, while Co increased from the western toward the eastern parts of the lake. Cr, Ni, Co, and Zn predominantly existed in the residual fractions, with the average values of 76.35, 59.22, 45.60, and 44.30%, respectively. Cu and Pb were mainly combined with Fe/Mn oxides in reducible fraction, with the average values of 66.4 and 69.1%, respectively. The pollution levels were different among the selected elements. Cu had the highest potential ecological risk, while Cr had the lowest potential ecological risk.

Settling fluxes and ecotoxicological risk assessment of fine sedimentary metals in Tema Harbour (Ghana)

Sediment traps were deployed in the Tema Harbour to estimate the settling fluxes of silt-clay particles and associated metals (Fe, Mn, Pb, Cr, Cu, Zn, Ni, Hg, Sn and As) and characterise their potential ecotoxicological risks. The mean daily settling fluxes of the silt-clay particles and associated metals ranged from 42.7 to 85.0gm^-2d^-1 and 1.3×10^-2 to 49.4mgm^-2d^-1, respectively, and were characterised by large fluctuations at each station. The silt-clay and metal fluxes strongly correlated, indicating the important role of the silt-clay particles in metal transport and distribution in the harbour. Geochemical indices indicated anthropogenic influences on the harbour as the Pb, Cr, Zn, Hg, Sn and As content in the settling silt-clay particles exceeded their average crustal concentrations. Sediment quality guidelines indicated these metals pose appreciable ecotoxicological risks, particularly As. Increasing temporal trends in As necessitates increased pollution control efforts at the harbour.

Contamination assessment of mercury, lead, cadmium and arsenic in surface sediments of Chabahar Bay

This study aimed to investigate heavy metals content of mercury (Hg), lead (Pb), cadmium (Cd) and arsenic (As) in surface sediments of Chabahar Bay. Sediment samples were taken from 13 stations and then analyzed. The concentration of Hg, Pb, Cd and As ranged between 0.06 and 0.14ppm, 8 and 23ppm, 0.05 and 0.9ppm and 5 and 22ppm, respectively. Arsenic content was more than ERL at some stations. Statistical analyses indicated critical importance of organic matter and mud in metal dispersion. Also, positive correlation of Al with Pb, Hg and Cd probably implies their terrestrial origination. Average enrichment factor of Hg, Pb, Cd and As were 2.67±0.95, 0.77±0.28, 6.56±9.9, and 7.53±3.44, respectively. Most stations were classified as moderately polluted and non-polluted sites.

Spatial distribution and metal contamination in the coastal sediments of Al-Khafji area, Arabian Gulf, Saudi Arabia

To document the spatial distribution and metal contamination in the coastal sediments of the Al-Khafji area in the northern part of the Saudi Arabian Gulf, 27 samples were collected for Al, V, Cr, Mn, Cu, Zn, Cd, Pb, Hg, Sr, As, Fe, Co, and Ni analysis using inductively coupled plasma-mass spectrometer (ICP-MS). The results revealed the following descending order of the metal concentrations: Sr > Fe > Al > As > Mn > Ni > V > Zn > Cr > Cu > Pb > Co > Hg > Cd. Average levels of enrichment factor of Sr, As, Hg, Cd, Ni, V, Cu, Co, and Pb were higher than 2 (218.10, 128.50, 80.94, 41.50, 12.31, 5.66, 2.95, 2.90, and 2.85, respectively) and that means the anthropogenic sources of these metals, while Al, Zn, Cr and Mn have enrichment factor less than 2, which implies natural sources. Average values of Sr, Hg, Cd, Cr, Ni, and As in the coastal sediments of Al-Khafji area were mostly higher than the values recorded from the background shale and earth crust and from those results along coasts of the Caspian Sea and the Mediterranean Sea. The highest levels of Cu in the northern part of the studied coastline might be due to Al-Khafji desalination plant, while levels of Al, Ni, Cr, Fe, Mn, Pb, and Zn in the central part may be a result of landfilling and industrial sewage. The highest levels of As, Cd, Co, Cu, Hg, and V in the southern part seem to be due to oil pollutants from Khafji Joint Operations (KJO). The higher values of Sr in the studied sediments in general and particularly in locality 7 could relate to the hypersalinity and aragonitic composition of the scleractinian corals abundant in that area.

A scheme to scientifically and accurately assess cadmium pollution of river sediments, through consideration of bioavailability when assessing ecological risk

Evaluating heavy metal pollution status and ecological risk in river sediments is a complex task, requiring consideration of contaminant pollution levels, as well as effects of biological processes within the river system. There are currently no simple or low-cost approaches to heavy metal assessment in river sediments. Here, we introduce a system of assessment for pollution status of heavy metals in river sediments, using measurements of Cd in the Shaocun River sediments as a case study. This system can be used to identify high-risk zones of the river that should be given more attention. First, we evaluated the pollution status of Cd in the river sediments based on their total Cd content, and calculated a risk assessment, using local geochemical background values at various sites along the river. Using both acetic acid and ethylenediaminetetraacetic acid to extracted the fractions of Cd in sediments, and used DGT to evaluate the bioavailability of Cd. Thus, DGT provided a measure of potentially bioavailable concentrations of Cd concentrations in the sediments. Last, we measured Cd contents in plant tissue collected at the same site to compare with our other measures. A Pearson's correlation analysis showed that Cd-Plant correlated significantly with Cd-HAc, (r = 0.788, P < 0.01), Cd-EDTA (r = 0.925, P < 0.01), Cd-DGT (r = 0.976, P < 0.01), and Cd-Total (r = 0.635, P < 0.05). We demonstrate that this system of assessment is a useful means of assessing heavy metal pollution status and ecological risk in river sediments.

Distribution and assessment of heavy metal toxicity in sediment cores from Bizerte Lagoon, Tunisia

To examine the state of pollution of Bizerte Lagoon which is exposed to intense anthropogenic pressure, two sediment cores were taken at two sites, one undergoes the dual effects of both marine waters arriving from the Mediterranean Sea through the Channel, and also of freshwater from the Tinja River; the other core is located at the center of the lagoon where water depth is maximal (12 m). Heavy metal concentrations in the two cores were assessed, with calculated enrichment factors and geo-accumulation indexes. Core sediments were also studied for chemical speciation and their monosulfide contents were measured. Results from enrichment factors and geo-accumulation indexes show an accumulation of Cd, Zn, Cr, and Pb, while chemical speciation revealed a risk only from Cd and Mn. Comparison of sequential extraction values with those of acid volatile sulfides revealed that non-toxic effects may be caused by any of the studied metals in the sediment.

Preliminary evaluation of heavy metal contamination in the Zarrin-Gol River sediments, Iran

The major objectives of the study were to test the hypothesis of the Zarrin-Gol River as a reference site for ecotoxicological studies and to assess the contamination degree of heavy metals and metalloids in the river using four contamination indices. For these purposes, eleven heavy metal and metalloid concentrations were analyzed. The average concentrations (mgkg^-1) in the sediments were: 37.67 (chromium) 286.28 (manganese), 13,751.04 (iron), 8.79 (cobalt), 12.39 (nickel), 32.68 (zinc), 21.91 (arsenic), 40.59 (selenium), 2923.86 (aluminum), ND (silver) and 785.96 (magnesium). Contamination factor, enrichment factor, pollution load index, and geoaccumulation index were calculated to evaluate the contamination degree and influence of human activities on heavy metal levels. The contamination indices of the sediment samples showed that arsenic and selenium were the highest pollutants. The results indicated that the Zarrin-Gol River could not be used as a reference site at least for arsenic and selenium.

Assessing trace elements in striped dolphins from the Strait of Gibraltar: Clues to link the bioaccumulation in the westernmost Mediterranean Sea area and nearest Atlantic Ocean

Dolphins are considered sentinel species in the marine environment. The Strait of Gibraltar is the only passage between the Mediterranean Sea and the Atlantic Ocean, being the transitional region which connects these two basins and one of the most important routes of cetacean migration worldwide. In this work, eight trace elements (TE) were studied in 45 samples of liver, kidney and muscle, from 15 specimens stranded in this study area. The preliminary results show, among others, the patterns of distribution of the TE in the target organs studied, the influence of sex, length and developmental stage in these TE concentrations and the Se/Hg ratio. Subsequently, the results of TE concentrations in liver have being compared to previous data on S. coeruleoalba from the westernmost Mediterranean Sea and the nearest Atlantic Ocean. For some elements (e.g. for As), concentrations are similar to those obtained from Atlantic samples, despite in other cases (e.g. for Cd) results are lined up with those observed in Mediterranean studies. In addition, in the case of some TE (e.g. Se and Zn) the results are in the middle of those reported for both basins, reinforcing the idea of the Strait of Gibraltar being a transitional zone. Present study is the first research regarding this issue in this outstanding region, aiming to give insights of how this matchless area can help to link TE concentrations observed in these Atlantic and Mediterranean threatened species.

Characterization of heavy metal contamination in the soil and sediment of the Three Gorges Reservoir, China

This paper analyzes the concentration, distribution, bioavailability, and potential heavy metal contamination risk of Cu, Pb, Cd, Zn, and Cr in the soil and sediment of the Three Gorges Reservoir (TGR). In this paper, 14 stations that cover the upper reaches to the lower reaches of the TGR were selected. The spatial distribution of heavy metals in the TGR showed that the average concentrations of Cu, Pb, Cd, Zn, and Cr were higher in the upper and lower reaches than those in the middle reaches because of industrial and agricultural activities as well as natural processes (e.g., soil erosion, rock weathering). The results also indicated that multiple pollution sources and complex geomorphological, geochemical and biological processes resulted in remarkably higher heavy metal concentrations in the soils of the water-level-fluctuation zone (WLFZ) than in the soils of the banks. The Cu, Pb, Cd, Zn, and Cr concentrations in the soils of the TGR did not exceed their respective maximum allowable concentration (MAC) values for agricultural soils in China, indicating that the soil in the TGR was not seriously contaminated with Cu, Pb, Cd, Zn, or Cr. However, the mean concentrations of all the studied metals in the sediments were higher than the geochemical background values and much higher than those in the soils, thus indicating the effect of the pollution sources and the altered hydrologic conditions that occurred after the impoundment of the TGR. A geoaccumulation index analysis indicated that the TGR sediments were moderately polluted with Cu and Cd, unpolluted to moderately polluted with Pb and Cr, and unpolluted with Zn. Fractionation studies indicated that Cd was mainly present in the non-residual fractions and exhibited great instability and bioavailability; furthermore, the alternating wetting and drying of the WFLZ soils enhance the mobility and bioavailability of Cd. Thus, greater attention should be paid to Cd pollution in the TGR because of its higher risk assessment values and potentially adverse biological effects.

Geochemical speciation, bioavailability and source identification of selected metals in surface sediments of the Southern Caspian Sea

Geochemical speciation of As, Cd, Co, Cr, Cu, Ni, Pb, V and Zn were determined in the surface sediments of the southern Caspian Sea. A five-step sequential extraction technique was used to determine the chemical forms of metals. Mean concentrations (ppm) of heavy metals were (mean±S.D.) As: 9.94±1.71, Cd: 0.87±0.23, Co: 14.85±2.80, Cr: 72.29±19.48, Cu: 18.91±4.48, Ni: 32.87±5.25, Pb: 12.48±3.22, V: 86.07±20.71 and Zn: 66.85±10.11. Among the metals, Cu, As, Pb and Zn exhibited relatively higher mobility, while Cd, Co, Cr, Ni and V were found mainly in the residual fractions. Cu and As showed the highest percentages in the exchangeable phase while Co and Cr had the lowest percentages in the phase. The Risk Assessment Code (RAC) values indicated that As, Cu and V had medium risk at some sampling sites. According to pollution load index (PLI), sediments from some sampling sites were polluted.

Effects of anthropogenic activities on the heavy metal levels in the clams and sediments in a tropical river

The present study aimed to assess the effects of anthropogenic activities on the heavy metal levels in the Langat River by transplantation of Corbicula javanica. In addition, potential ecological risk indexes (PERI) of heavy metals in the surface sediments of the river were also investigated. The correlation analysis revealed that eight metals (As, Co, Cr, Fe, Mn, Ni, Pb and Zn) in total soft tissue (TST) while five metals (As, Cd, Cr, Fe and Mn) in shell have positively and significantly correlation with respective metal concentration in sediment, indicating the clams is a good biomonitor of the metal levels. Based on clustering patterns, the discharge of dam impoundment, agricultural activities and urban domestic waste were identified as three major contributors of the metals in Pangsun, Semenyih and Dusun Tua, and Kajang, respectively. Various geochemical indexes for a single metal pollutant (geoaccumulation index (I _geo), enrichment factors (EF), contamination factor (C _f) and ecological risk (Er)) all agreed that Cd, Co, Cr, Cu, Fe, Mn, Ni and Zn are not likely to cause adverse effect to the river ecosystem, but As and Pb could pose a potential ecological risk to the river ecosystem. All indexes (degree of contamination (C _d), combined pollution index (CPI) and PERI) showed that overall metal concentrations in the tropical river are still within safe limit. River metal pollution was investigated. Anthropogenic activities were contributors of the metal pollution. Geochemical indexes showed that metals are within the safe limit.

Assessment of heavy metal contamination in the surface sediments: A reexamination into the offshore environment in China

The contents of Cu, Pb, Zn, Cd, Cr, Hg and As in the surface sediments of over 668 sites were monitored in a comprehensive program for assessing the degree of heavy-metal pollution and adverse biological effects of the offshore sediments in China. The contamination factor and geoaccumulation index indicated that As and Pb might be two of the most influential pollution loading in these metals. Cluster analysis separated 19 areas in China's near seas into 7 groups with different pollution characteristic, where the sediments along Zhejiang coast were the most highly-contaminated. Based on biological adverse effects index and sediment quality guideline for As, nearly half of sites in China's near seas induced slight adverse biological effects. With correlation analysis, self-organizing map and factor analysis, different sources as well as various adsorption mechanisms/anthropogenic factors were suggested to be important roles in altering the concentration of heavy metals in the sediments.