Evaluation of sediment contamination with heavy metals: the importance of determining appropriate background content and suitable element for normalization

Defining the quality of sediment in the context of the WFD monitoring plans: metal enrichment in two catchments from the north of Portugal

Purpose

Riverbed sediment geochemistry provides useful information regarding metal contamination. To integrate sediment quality in river monitoring, within the WFD, the report of sediment quality to water quality managers must be expeditious. This study revisits the metal enrichment concept, applied to sediments from two mountain catchments, as a useful technique in river monitoring.

Methods

Riverbed sediment samples, collected at the end of the Dry and Wet Periods (DP, WP) were analysed for Cd, Cu, Pb, Zn, and Fe in fractions < 2 mm and < 63 µm. The metal enrichment factors (EFs) were referenced to distinct background values: average shale (AS), world rivers suspended sediments (WRSS) and Geochemical Atlas of Portugal (GAP).

Results

Cd, Cu, Pb and Zn contents are higher in the fraction < 63 µm, and at DP. The ranges of variation in fraction < 63 µm are (mg kg-1): a) River Vilariça, Cd (5-18 DP; 0.3 WP); Cu (103-341 DP; 22-218 WP); Pb -(24-55 DP; 11-42 WP); Zn (107-241 DP; 54-103 WP); b) River Vizela, -Cd (13-44 DP; 8-41 WP); Cu (267-444 DP; 18-168 WP); Pb -(44-132 DP; 20-42 WP); Zn (141-801 DP; 36-181 WP). Variations in metal contents are influenced by lithological, geomorphological, and microclimatic features, and anthropogenic pressures. EFs are higher when referenced to AS. In the River Vizela, the EFs reveal an enrichment of Cu, Pb and Zn relative to WRSS; Cd registers an enrichment relative to GAP.

Conclusion

Local/regional background, and EFs, are relevant when assessing environmental risks in freshwater systems: low EFs, when associated to natural enrichments, originate values of concern in terms of quality guidelines; high EFs may not imply risk to the fluvial environment. Using the fraction < 63 µm in river monitoring is considered adequate. In dynamic mountain streams, recent sediments and associated contaminants are retained, providing information on possible pollution sources. Identifying metals contamination (or natural enrichment) can help decision-makers to provide solutions for pollution sources.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11368-025-03963-6.

Spatial distribution of heavy metal assessment in beach sediment due to bauxite mining in Kuantan, Pahang, Peninsular Malaysia

The effect of open-pit bauxite mining on beach sediment contamination in the urban coastal environment of Kuantan City, Malaysia, was investigated. The contents of 11 heavy metals (Pb, Cd, Al, Mn, Cu, Zn, Fe, As, Ni, Cr, and Ag) in 30 samples from Kuantan beach sediment zones (supratidal, intertidal, and subtidal) were determined using inductively coupled plasma optical emission spectrometry followed by contamination indexes, Pearson's correlation analysis, and principal component analysis (PCA). The results indicated that Cd, As, Ni, and Ag values in beach sediment zones were significantly higher compared to background values. Contamination indexes suggest that Cd, As, Ni, and Ag were highly contaminated, and moderate to extremely enriched near the Kuantan Port. However, these heavy metal concentrations are lower compared to previous studies in the region. Sediment quality guidelines highlighted the occasional presence of Cd and Ag. Based on Pearson's correlation analysis, PCA, and cluster analysis, sources of these heavy metals in beach sediments were likely from agricultural runoff, uncontrolled industrial and residential discharge, and unprotected mine waste near the Kuantan Port. Furthermore, effective management of mining practices and ongoing monitoring are essential to reduce contamination risks.

Luminescent Metal-Organic Frameworks for Electrochemiluminescent Detection of Water Pollutants

The modern lifestyle has increased our utilization of pollutants such as heavy metals, aromatic compounds, and contaminants that are of rising concern, involving pharmaceutical and personal products and other materials that may have an important environmental impact. In particular, the ultimate results of the intense use of highly stable materials, such as heavy metals and chemical restudies, are that they turn into waste materials, which, when discharged, accumulate in environmental water bodies. In this context, the present review presents the application of metal-organic frameworks (MOFs) in electrochemiluminescent (ECL) sensing for water pollutant detection. MOF composites applied as innovative luminophore or luminophore carriers, materials for electrode modification, and the enhancement of co-reaction in ECL sensors have enabled the sensitive monitoring of some of the most common contaminants of emerging concern such as heavy metals, volatile organic compounds, pharmaceuticals, industrial chemicals, and cyanotoxins. Moreover, we provide future trends and prospects associated with ECL MOF composites for environmental sensing.

Accumulation of metal trace elements in different body parts of terrestrial Roman snail Helix pomatia L., 1758 on three polluted sites in Serbia

Atmospheric pollution remains one of the growing concerns in the twenty-first century, with particular focus on metal trace elements (MTE) from anthropogenic sources, due to their adverse effects on biota. The concentration and type of MTE in the atmosphere and in the soil are diverse, depending on the origin of pollutants, which can cause diverse detrimental effects on organisms living in the nearby environment. Three sites in Central Serbia with different origins of MTE pollution (urban contamination, smelting, and fly ash area) were assessed, using terrestrial Roman snails (Helix pomatia) as biomarker organisms. These snails are sentinel organisms and are known for their capacities for accumulation of MTE. Snails were sampled and their body was divided in three parts: viscera, foot, and shell and concentrations of MTE were determined in each of these body parts using inductively coupled plasma optical spectrometry. Results showed contrasting MTE accumulation patterns in body parts of the snails. Of three studied sites, snails sampled in the vicinity of fly ash containment had lower concentrations of MTE compared to other two polluted sites.

Assessment of heavy metal pollution in marine sediments from southwest of Mallorca island, Spain

Anthropogenic activities in urban, agrarian, or industrial areas are the main cause of heavy metals in sediments worldwide. Since the 1960s, there have been submarine discharges through outfalls of poorly treated or untreated wastewater on the south coast of Mallorca island (Mediterranean Sea). In this study, the pollution of marine sediments is analyzed at a great number of points on the south of the seacoast. Heavy metal concentrations of As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn, total inorganic carbon (TIC), sulfur, mineralogy, and grain size were analyzed. The objective is to evaluate the concentrations of toxic substances and their spatial distribution and ranges that can negatively affect marine ecosystems and human health. In addition, the results obtained have been compared with standardized indices for marine sediments, and a regional index has been developed with the background values of heavy metals obtained in the sediments of the study area. To obtain consistent conclusions, concentrations of heavy metals were classified with the Igeo Index. The concentrations of heavy metals obtained show that a great number of samples exceeded the limits considered for uncontaminated sediments according to the index applied. Elements such as Hg, Ba, Pb, and Cu showed high concentrations close to the outfalls and lower concentrations in zones far from these points. To support the assessment, chemical processes such as dissolution or chemical precipitation have been studied. The results also show that marine sediments can be a good trap for chemical elements and a good proxy to analyze the impact of anthropogenic activities in areas heavily pressured by humans, and the risk to the environment and human health.

Impacts of Fishing Vessels on the Heavy Metal Contamination in Sediments: A Case Study of Qianzhen Fishing Port in Southern Taiwan

Routine maintenance of fishing vessels and wastewater discharges are primary sources of heavy metals in fishing ports. Sediment pollution assessment is necessary in fishing port management, including sediment dredging and disposal, sewage treatment facility construction, and pollution source control. In this study, sediment heavy metal contents in Qianzhen Fishing Port, the largest pelagic fishery port in Taiwan, were investigated to assess the contamination levels and related potential ecological risks using multiple sediment pollution indices. Normalization methods were applied to identify the potential sources of heavy metals in fishing port sediments. Results showed that Cu, Zn, Pb, and Cr contents in the sediments of the inner fishing port (averages of 276, 742, 113, and 221 mg/kg, respectively) were 3–5 times greater compared to those along the port entrance and outside, indicating the strong impacts of anthropogenic pollution (EFCu: 5.6–12.5; EFZn: 2.8–4.3; EFPb: 2.4–5.4; EFCr: 1.1–3.2). Copper pollution was more severe, with high maxima contamination factor (CFCu: 15.1–24.8), probably contributed by copper-based antifouling paints used in fishing vessels. The sediments in the inner fishing port are categorized as having considerable ecological risk and toxicity (mERMq: 0.61–0.91; ΣTU: 7.5–11.7) that can potentially cause adverse effects on benthic organisms. Qianzhen Fishing Port sediments can be characterized as high Cu/Fe and Pb/Fe, moderate Zn/Fe, and high total grease content, indicating that the potential sources of heavy metals are primarily antifouling paints and oil spills from the fishing vessels. This study provides valuable data for pollution control, remediation, and environmental management of fishing ports.

The fate and contamination of trace metals in soils exposed to a railroad used by Diesel Multiple Units: Assessment of the railroad contribution with multi-tool source tracking

Soil samples from cut slopes from lightly loaded railway lines used by Diesel Multiple Units for 5 years in Gdansk (Poland) were collected and analyzed for trace metals (TMs): Zn, Pb, Cd, Ni, Cr, Cu, and Fe. The main aim was to assess soil enrichment, contamination status, and distribution of TMs relative to the distance from the railway track. Extensive source tracking analyses were performed using cluster analysis (CA) and the Pb isotope ratios approach (²⁰⁶Pb, ²⁰⁷Pb, and ²⁰⁸Pb). Soil samples were affected by Cr, Cu, Pb, and Zn (max values in mg/kg d.w.: 31.1, 145, 80.5, and 115, respectively). The Enrichment Factor showed moderate (Cr, Zn, Pb) to very severe (Cu) enrichment. CA allowed TMs to be divided into two general groups: a) containing Zn, Pb, Cd with slight interaction with Cu; and b) containing Fe and Ni with slight interaction with Cr. Correlation analyses indicated Cr as an outlying TM delivered from a separate source associated with the specificity of the construction of railroad 248, where alloys containing Cr were used to counteract increasing wear-and-tear of the rails. Pb isotopic ratios in the ranges of 1.16-1.20 (²⁰⁶Pb/²⁰⁷Pb) and 2.05-2.10 (²⁰⁸Pb/²⁰⁶Pb) corresponded to anthropogenic supplementation (coal combustion, road vehicles, and railroad transport) of Pb and Pb-correlated TMs (Zn, Cd, and partly Cu). Despite the research focus on the impact of the railroad contribution, a comparison with other forms of transport indicated that road transport appeared to have a higher contributing factor to TM pollution at the investigated site. This general conclusion again emphasizes the lower environmental footprint exhibited by railway transport in comparison to road transport.

Spatial distribution and level of contamination of potentially toxic elements in sediments and soils of a biological reserve wetland, northern Amazon region of Ecuador

This study quantifies the degree of pollution and assess the ecological risk of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, V and Zn in sediments and soils of the Limoncocha Biological Reserve (Ecuador), identified as a Ramsar site with high ecological and socioeconomic value. The hydrologic system of the Reserve is mainly formed by two rivers that drain into the Limoncocha lagoon, which occupies only five percent of the protected area but support a high anthropic influence. Local statistical baseline of studied potentially toxic elements is established using cumulative frequency method, and Al is selected as reference element due to the good correlation with the studied elements. The grade of pollution and the potential ecological risk are evaluated applying three individual (Contamination Factor, Geo-accumulation Index and Enrichment Factor) and six integrated (Degree and modified degree of contamination, Pollution Load Index, Nemerow and modified Nemerow pollution indexes and potential ecological risk index) indices. Results analysis are based on the combined application of traditional statistics, multivariate data analysis and self organizing maps. Outcomes suggest to classify sediments and soils as "moderate contamination and enrichment" due mainly to the concentrations of Cu (66.4-110 mg/kg) and Cd (0.0262-0.808 mg/kg), derived from domestic wastewaters and agricultural activities, and in a lesser extent due to Mo (0.822-4.37 mg/kg), Ni (10.3-25.8 mg/kg), Co (7.27-24.8 mg/kg) and V (60.3-178 mg/kg), derived from oil field drilling activities. The distributions of As (0.328-8.83 mg/kg), Ba (143-1100 mg/kg), Pb (7.20-26.5 mg/kg), Zn (60.1-276 mg/kg) and Cr (10.1-48.6 mg/kg) are heterogeneous in the studied sampling sites. Sediments located next to the pier and at the central area of the Limoncocha lagoon, show moderate potential risk and according to sediment quality guidelines, the calculated mean Effect Range Median quotient (mERMq) classify the sites as medium-low priority risk level. A three-level classification of a mean quotient based on soil quality and soil potential uses is proposed. Soil sites with high anthropogenic activities show low to moderate potential ecological risk being classified as poor soil quality sites but with all potential soil uses allowed according to the legal limits for land uses in Ecuador.

Impact of anthropogenic activities on an urban river through a comprehensive analysis of water and sediments

The aim of this study was to assess the impact of urban and industrial areas on an urban river through a comprehensive analysis of water and sediments. Six different sites along the San Luis River, Argentina, were characterized by measuring 12 physical-chemical parameters and nine heavy metals according to standard protocols. Metal pollution in sediment samples was evaluated with several indices. Cluster analysis was applied to standardized experimental data in order to study spatial variability. As, Cu, Cr, Mn, Pb, and Zn were the main contributors to sediment pollution, and the industrial zone studied showed moderate enrichment of Co, Cu, and Zn, probably due to anthropogenic activities. Cluster analysis allowed the grouping of the sites: sediment samples were classified into two clusters according to the metal content; water samples were arranged into three groups according to organic matter content. The results were compared with sediment and water quality guidelines. They indicated progressive deterioration of water and sediment quality compared with the background area, mainly in the sites following the industrial park and domestic discharge areas. Moreover, the results showed that the analysis of both water and sediment should be considered to achieve a watershed contamination profile.

Effect of quarry activities on selected biological resources around quarry site within Onigambari forest plantation, Oyo State, Nigeria

Quarry activities are creating diverse stress on biological resources in the rural areas where most of them are located globally. In this study, the effect of quarry activities on elephant grass (Pennisetum purpureum) leaves and soils around Onigambari Forest Reserve, Oyo State, Nigeria, were investigated. Soil and samples of elephant grass (Pennisetum purpureum) leaves were collected from two different distances from the quarry plant. Samples used as control were collected within the boundary of Cocoa Research Institute of Nigeria (CRIN), Oyo State, Nigeria estate. Samples were analysed using proton-induced X-ray emission, to determine the elements. The physiochemical parameters were also analysed in both soil and leaves samples. The mean concentration of the elements in the soil sample from Site 1 was higher in Mg, Cl, Ca, Ti, Cr, Mn, Fe, Zn and Zr than Site 2 and the control site. While in leaves, similar trend was observed. Cd and Ag were highly enriched.

Distribution, contamination status and bioavailability of trace metals in surface sediments along the southwest coast of India

This study investigates the influence of upwelling induced seasonal hypoxia in the sediment-water interface on the distribution, bioavailability and geochemical partitioning of selected trace metals in surficial sediments along the southwest coast of India based on two successive cruises. The first cruise was during the southwest monsoon (SWM) season when coastal waters exhibited intermittent bottom hypoxia due to upwelling. The second cruise during the northeast monsoon (NEM) season was characterised by a uniformly warm and well-oxygenated water column in the study region. The results showed that grain size, organic carbon and Fe are the major factors influencing the distribution of trace metals in the surface sediments. Based on the geochemical indices (contamination factor, enrichment factor and geo-accumulation factor), the study region appears to be moderately contaminated by Ni, Cr, and Pb. Based on the ecological risk assessment criteria, the enrichment of Pb, Cr and Ni may cause adverse effects on the benthic organisms. The fractionation studies demonstrated that the major pathway of metal deposition in the sediment is lithogenic. The data also showed that labile and organic fractions are the second dominant forms, while other fractions (exchangeable and carbonate) are insignificant. The consistency in the reactive Fe concentrations during SWM and NEM could be due to the absence of Fe dissolution in sediments under mild reducing condition (intermittent hypoxia). In addition to the above, an enrichment of organic matter also leads to increased deposition of trace metals in sediments. Conversely, the secondary phase enrichment factor and risk assessment code calculated based on the metal fractionation data indicated low risk and contamination along the southwest coast of India except for Zn that showed moderate contamination in some transects. The study provides the need for regular geochemical assessment to control metal pollution in the coastal environment, which is a major resource of the fishery.

Sediment information on natural and anthropogenic-induced change of connected water systems in Chagan Lake, North China

This study discusses changes in connected water systems in Chagan Lake induced by the interference of natural and human activities, based on the analysis of sediment characteristics. In this study, the following sediment characteristics were investigated in the lake area, the natural supply area, and the lake drainage area: mineral composition; particle size distribution; magnetic susceptibility; nutrient content; content of isotopes δ¹³C_org and δ¹⁵N; and content of heavy metals and of metallic oxides. The results showed that silicate minerals quartz, orthoclase, and anorthose were abundant in the whole lake water system. Quartz accumulated more easily in the lake area, while carbonate masses in the lake mainly came from the Huolinhe River. Moving from the lake area to the water diversion and drainage areas, fine particles clearly decreased, while coarse particles significantly increased due to the increase in hydraulic erosion. The main sources of nutrients and of organic matter are: the residual of the drainage from the Qianguo irrigated areas; the surrounding villages and the tourist area; and the decomposition of aquatic organisms. A large number of anthropogenic heavy metals, such as Hg, Cu, and As, were accumulated in the artificial water diversion area and in the farmland drainage area. This study indicates that recovering the original connected water system during the wet season, while at the same time enhancing water supply during the dry season could improve the ecological quality of Chagan Lake.

Spatial Distribution of Minor Elements in the Tazlău River Sediments: Source Identification and Evaluation of Ecological Risk

Minor elements received more attention in recent years due to their contamination susceptibility and environmental impact. Surface sediment samples were collected from 29 sites and total contents of eight minor elements (Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) were investigated in order to determine the geostatistical distribution and to predict ecological implications. The relationship between metals and ecological implications was analyzed by using the geochemical normalization approach and ecological prediction indicators such as the enrichment factor (EF), the contamination degree (CD), the environmental toxicity quotient (ETQ), and the health risk assessment. Based on the studied toxic metals, it was observed that the most toxic element in Tazlău River sediments is Cr. The assessment results of carcinogenic and non-carcinogenic risks via dermal contact indicate that the study area shows no human health risk. The correlation matrix and principal component analysis (PCA) provide an overview of the major sources, anthropogenic versus geogenic, where Cr and Cd mainly originate from anthropogenic sources, while Pb is derived from a geogenic source. The approaches used in this study will provide a baseline regarding the accumulation of minor elements in the sediment and will be useful for other studies to easily identify the major contaminates and to estimate the health human risk.

Zirconium as a suitable reference element for estimating potentially toxic element enrichment in treated wastewater discharge vicinity

The suitability of a reference element or normalizer used in assessing soil contamination levels using enrichment factor (EF) is important for soil quality assessment and monitoring. This study evaluated the results of using three reference elements Ti, Fe, and Zr for EF determination of Rb and Sr in soils within treated wastewater discharge vicinity, Central Botswana. The upper continental crust (UCC), world average values (WAV), and the local background values (LBV) were used in EF assessment of eight pedons. The elemental concentrations of the soils were determined with portable X-ray fluorescence (pXRF) analyzer. Relationships between the elements were strongly significant between Rb and Ti (r = 0.600, p < 0.01), Rb and Fe (r = 0.735, p < 0.01), Sr and Ti (r = 0.545, p < 0.01), and Sr and Fe (r = 0.841, p < 0.01). Second-level correlation analysis between contamination factor (CF) and EF levels showed Zr as the best reference element for Rb and Sr in the soils. Results from this study provide baseline knowledge necessary for contamination assessment and monitoring of soils with similar environmental conditions.

Distribution and risk assessment of trace metals in multifarious matrices of Vembanad Lake system, Peninsular India

Trace metal contamination in aquatic ecosystems is of significant concern in countries like India having a recent industrial history. The present study mainly focuses on the spatial and temporal distribution, occurrence and toxicity of five trace metals (Hg, Cd, Zn, Cu and Pb) in water and sediment matrix of Vembanad Lake system (VLS), India. Mercury analysis was done by using Cold Vapor Atomic Fluorescence Spectrometer, and the other metals were analysed using Volta metric-Trace metal analyser. The spatial distribution of trace metals in the study area showed the following trends, Zn > Pb > Cu > Cd > Hg, Zn > Pb > Cu > Hg > Cd for surface water and bottom water respectively. Health risk assessment on human population associated with trace metals was also calculated to predict their health impacts on human through non-dietary exposure. The trace metals contamination in water and sediments of VLS are potential to cause cancer on human population associated with the system. Ecological risk indices showed that the northern portion of VLS is more contaminated with trace metal than the other part of the system.

Seasonal and spatial contamination statuses and ecological risk of sediment cores highly contaminated by heavy metals and metalloids in the Xiangjiang River

To reveal seasonal and spatial variations of heavy metals and metalloids (HMMs) in sediment of the Xiangjiang River, a total of 24 water and 649 sediment samples were collected from six sampling stations in the Songbai section of the river which had been polluted by HMMs for 100 years. Their contamination statuses and ecological risk were determined by enrichment factor (EF), geo-accumulation index (I_geo), pollution load index (PLI), and mean probable effect concentration quotients (mPECQs) analyses. The results revealed a unique seasonal distribution of metals in the sampling stations: The highest concentrations were revealed in the dry seasons (autumn and winter) and the lowest during the wet seasons (spring and summer). It exhibited a greater seasonal variation in the estuary sediment cores (sites ME and MW) than in the cores of other sites. Moreover, the highest concentrations of the tested metals were also found in the estuary sediment cores in the dry seasons (autumn and winter). The highest vertical concentrations of Pb, Zn, Cu, Ni, As, Fe, and Mn were observed at the depths of 16-36 cm in all of the sampled sediment cores. The EF, I_geo, PLI, and mPECQs values of all samples in autumn were higher than in summer. Cd posed the highest ecological risk in all seasons, although its concentrations were lower compared to other studied elements. Our results will benefit to develop feasible sediment quality guidelines for government monitor and remediate the local sediments in the Xiangjiang River.

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.

Assessment of geogenic input into Bilina stream sediments (Czech Republic)

Over the past 100 years, the area along the River Bílina has been influenced by open-cast brown-coal mining, coal processing, petroleum refineries, and chemical plants. As a result, the extensive industrial activity has changed the overall character as well as the morphology of the landscape. A survey was underway to investigate the occurrence and distribution of various elements in the sediments of the River Bílina-a tributary of the River Elbe, a watercourse running through the Czech Republic and Germany-in order to discern the natural background from anthropogenic pollution. The study evaluated the content of selected elements (As, Zn, Pb, Cr, Ni, V, and Cu) in stream sediments of the River Bílina. Samples were taken at 20 sampling sites throughout the 82-km-long watercourse. For all the samples, the content of the elements was determined using ICP-MS after each of the sample was digested using HF and HNO₃. The results of analyses of elemental composition of stream sediments were compared with those found through such analyses made within the surrounding geological units-more specifically, Proterozoic crystalline, Tertiary volcanic, Quaternary loess, Neogene sediments, and Neogene coal. All the samples of the stream sediments examined revealed increased amounts of As, V, Ni, Cr, and Pb. Using the enrichment factor established on the basis of the regional geological background values proved that elevated levels of elements in stream sediments are not always the result of industrial contamination.

Mercury contamination of stream sediments in the North Bohemian Coal District (Czech Republic): Mercury speciation and the role of organic matter

Industrial expansion in the North Bohemian Coal District over the past decades has had an adverse effect not only on stream sediments but also on the freshwater system. So far mercury occurrence has not been properly investigated in the area. In response to this situation, the present study applies mercury quantification and speciation in order to predict the possible mobility of mercury. The enrichment factor (EF) and sediment quality guidelines (SQGs) were used to calculate the degree of mercury contamination. An automatic mercury analyser was employed to detect the total mercury content (Hg-T) and Thermal Desorption technique was used to identify mercury species. All the sediment samples were assessed with the contamination degree which increased to very severe in stream sediments in the middle section of the river course. Mercury species identified were chiefly the insoluble forms Hg-FeS₂ and HgS. Lignite components and combustion residues were identified as the primary source of Hg contamination in the area.

Source apportionment of heavy metals and their ecological risk in a tropical river basin system

Surface water and sediment samples were collected from Ajay River basin to appraise the behavior of heavy metals with surrounding environments and their inter-elemental relationships. Parameters like pH and organic carbon are having a minimal role in heavy metal distribution while some elements like Fe and Cu showed great affinity for organic matter based on linear regression analysis (LRA). Ficklin diagram justified that river basin is not contaminated through acidic pollutants. The river basin is highly enriched with Cu, Cd, Pb, and Ni which were much higher than world average values, average shale standard, effect range low (ERL), and threshold effect level (TEL). PCA and LRA verified that Cu, Cd, Pb, and Ni were mainly derived from anthropogenic inputs, and others like Fe, Mn, Zn, and Co came from geogenic sources. Pollution indices revealed that river basin is moderately to highly contaminated by Cu, Cd, and Ni. Furthermore, Ajay River basin is under strong potential ecological risk based on the obtained value of risk index and probable effect level/effect range median quotient index. However, river basin is strongly influenced by lithological properties, diversified hydrogeological settings, mineralization and mobilization of subsurface materials, and urban and industrial effluents which are controlling the heavy metals.

Importance of background values in assessing the impact of heavy metals in river ecosystems: case study of Tisza River, Serbia

The main objective of this paper is to evaluate how a choice of different background values may affect assessing the anthropogenic heavy metal pollution in sediments from Tisza River (Serbia). The second objective of this paper is to underline significance of using geochemical background values when establishing quality criteria for sediment. Enrichment factor (EF), geoaccumulation index (I _geo), pollution load index (PLI), and potential ecological risk index (PERI) were calculated using different background values. Three geochemical (average metal concentrations in continental crust, average metal concentrations in shale, and average metal concentrations in non-contaminated core sediment samples) and two statistical methods (delineation method and principal component analyses) were used for calculating background values. It can be concluded that obtained information of pollution status can be more dependent on the use of background values than the index/factor chosen. The best option to assess the potential river sediment contamination is to compare obtained concentrations of analyzed elements with concentrations of mineralogically and texturally comparable, uncontaminated core sediment samples. Geochemical background values should be taken into account when establishing quality criteria for soils, sediments, and waters. Due to complexity of the local lithology, it is recommended that environmental monitoring and assessment include selection of an appropriate background values to gain understanding of the geochemistry and potential source of pollution in a given environment.

Geochemical fractionation and pollution assessment of Zn, Cu, and Fe in surface sediments from Shadegan Wildlife Refuge, southwest of Iran

This research focuses on the fractionation and distribution patterns of heavy metals (Zn, Cu, and Fe) in surficial sediments collected from Shadegan Wildlife Refuge, the biggest wetland in southern part of Iran, to provide an overall classification for the sources of metals in the study area using a sequential extraction method. For this purpose, a four-step sequential extraction technique was applied to define the partitioning of the metals into different geochemical phases of the sediment. The results illustrated that the average total level of Zn, Cu, and Fe in surface sediments were 55.20 ± 16.04, 22.86 ± 5.68, and 25,979.01 ± 6917.91 μg/g dw, respectively. On the average, the chemical partitioning of all metals in most stations was in the order of residual >oxidizable-organic > acid-reducible > exchangeable. In the same way, the results of calculated geochemical indices revealed that Cu, Zn, and Fe concentrations are mainly influenced by lithogenic origins. Compared with consensus-based SQGs, Cu was likely to result in occasionally harmful biological effects on the biota.

Geochemical partitioning and pollution assessment of Ni and V as indicator of oil pollution in surface sediments from Shadegan wildlife refuge, Iran

The total concentrations and chemical partitioning of Ni, V and Fe have been assessed in surface sediments from 160 sites along the Shadegan wildlife refuge. The results showed that the average total level of Ni, V and Fe in surface sediments were 45.08±12.09, 25.25±20.8 and 25,979.01±6917.91μg/g dw, respectively. On the average, the chemical speciation of Ni, V and Fe in most stations were in the order of residual>oxidisable-organic>acid-reducible>exchangeable. In all fractions, the residual was accounted the highest proportion for the metals analyzed. Among the non-residual phases, the proportion of heavy metals in organic matter fraction was higher than other phases collected from all locations. The comparison between measured values in this study and some fresh water sediment quality guidelines indicated that the levels of nickel would be expected to sporadically cause harmful biological impacts on biota in the Shadegan wildlife refuge.

Aquatic sediments pollution estimate using the metal fractionation, secondary phase enrichment factor calculation, and used statistical methods

The sequential extraction procedure of the European Community Bureau of Reference (BCR) was applied for the fractionation of Cd, Cr, Cu, Ni, Pb, Zn, Fe, Mn, and V in the Serbian river sediments. The aim of this paper was to describe a new approach in detection of anthropogenic elements in sediments, related to the Serbian river courses in order to assess their metal contamination. For sediment pollution evaluation, the risk assessment code (RAC) and the secondary phase enrichment factor (KSPEF) were used. Metal fractionation showed more easily mobilized forms predominant for copper, zinc, cadmium, manganese, and lead, which can be one of the indicators for anthropogenic source input. Chromium, nickel, iron, and vanadium found in the residual fraction indicate these metals may be an indicator for natural sources input. Based on RAC classification, results of sediments show no risk (Cr and V), low risk (Ni, Pb, and Fe), medium risk (Cu), high risk (Cd and Zn), and very high risk (Mn). The mean values of KSPEF were Cd > Cu > Zn > Ni > Mn > Pb > Fe > Cr > V, decreasing scale of no to moderately severe enrichment. The sediments were found to be contaminated by heavy metals to various extents, mostly Cd, Cu, and Zn. Research has shown the importance of KSPEF in quantifying degree of metal enrichment in sediments using results of sequential extraction. With the application of this factor, which is not frequently used in the scientific literature, the results obtained with sequential extraction can be used not only for assessment of mobility but also to quantify the metal pollution.

Spatial monitoring of heavy metals in the inland waters of Serbia: a multispecies approach based on commercial fish

The study monitored the contamination of fish muscle tissue by elements Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn at 17 sampling sites, in order to assess the pollution status of the main rivers in Serbia. Of the six commercially important fish species included in the study (pikeperch Sander lucioperca, catfish Silurus glanis, bream Abramis brama, barbel Barbus barbus, chub Squalius cephalus, nase Chondrostoma nasus), the bioconcentration factor (BCF) indicated that benthivore bream and barbel and predatory catfish have the highest tendency toward the accumulation of elements. This study achieved its primary objective and produced a contamination map of Serbia as a basis for further research. The estimated metal pollution index (MPI) showed the Tisa River to be unaffected by direct pollution (with an MPI value of 0.31) and the West Morava and Pek rivers to be affected (with MPI values of 1.92 and 0.73 for the WM1 and WM2 sampling sites and 0.65 for the Pek sampling site). Over the past two decades, Serbia has not expanded its industrial activity, which has resulted in the barely noticeable anthropogenic input of heavy metals in the rivers close to industry, and the main rivers are mostly unaffected and slightly affected. We assumed that pollution by heavy metals in the 1990s was trapped in the sediment, thus showing an increased concentration of elements in the species that live and feed on the bottom. Hg concentrations exceeded the maximum permitted concentrations (MPCs) only in catfish samples (0.62 mg kg(-1)) from the Danube (D3 sampling site) and barbel (0.78 mg kg(-1)) from the West Morava (WM1 sampling site), while Cd concentrations exceeded the MPC in catfish samples (0.09 mg kg(-1)) from the Danube (D1 sampling site) and chub samples (0.1 mg kg(-1)) from the South Morava (SM2 sampling site). The average concentrations of Pb exceeded the MPC in chub and barbel samples (0.32 and 0.82 mg kg(-1), respectively) from the West Morava (WM1 sampling site); chub, barbel, and nase samples (0.35, 0.32, 0.31 mg kg(-1), respectively) from the West Morava (WM2 sampling site); chub and barbel samples (0.35 and 0.3 mg kg(-1), respectively) from the Ibar; chub samples (0.39 mg kg(-1)) from the Drina; chub and barbel samples (0.59 and 0.4 mg kg(-1), respectively) from the Great Timok; and nase samples (0.33 mg kg(-1)) from the Pek. These results demonstrate that there is a need for future studies that would involve similar analyses and focus especially on smaller rivers that have been neglected so far.