Speciation and ecological risk of heavy metals in intertidal sediments of Quanzhou Bay, China

The chemical speciation of nine heavy metals in intertidal sediments from Quanzhou Bay was determined using a modified sequential extraction procedure, proposed by the Commission of the European Community Bureau of Reference. The results show that Mn presents the highest percentage in the acid-soluble fraction, and Pb and Cu present the highest percentages in the reducible fraction. The highest percentages of Fe, V, Cr, Ni, Zn, and Co were found in the residual fraction. The mobility order of the heavy metals studied on the basis of the nonresidual content of the elements is Mn > Pb > Cu > Co > Zn > Ni > Cr > V > Fe. The assessment on potential ecological risk indices of some heavy metals indicates that Zn, Ni, and Cr show moderate contamination, while Cu and Pb show slighter contamination. On the whole, the comprehensive potential ecological risk index of Cu, Zn, Ni, Cr, and Pb in the sediments presents moderate degree.     

Distribution and accumulation of heavy metals in the sediments of Akkaya Dam,Nigde, Turkey

Twenty-one surface sediment samples were collected from Akkaya Dam. Heavy metal concentrations (Mo, Cu, Pb, Zn, Ni, Co, Mn, Fe, Cr, As, V and Cd), grain size, organic carbon and carbonate contents were studied in order to assess the extent of environmental pollution and to discuss the origin of these contaminants in sediments of dam. The sediments in the study area are mostly very fine sands. However, mud was observed in the northeast of the dam. Sediment pollution assessment was carried out using enrichment factor. The calculation of enrichment factors showed that Mo is depleted by 1.0 whereas Cu, Pb, Zn, Ni, Co, Mn, As, V, Cr and Cd are enriched by 3, 5.4, 7, 2.7, 2.2, 3.4, 42.3, 2.1, 1.8 and 7.2, respectively. Relatively high concentrations heavy metals occurred in north (textile industry area) and east (Karasu River) due to enrichment controlled by anthropogenic wastes. The results of correlation analysis show low–medium positive and negative correlations among metals, grain size, carbonate contents and organic carbon and indicate that heavy metals in sediments of the Akkaya Dam have different anthropogenic sources.     

Assessment of trace metal pollution in surface sediments of Nemrut Bay, Aegean Sea

Surface sediments collected from nine stations in Nemrut Bay, Aegean Sea were analyzed for trace metals (Hg, Cd, Pb, Cr, Cu, Zn, Mn, Ni, Fe, As, and Mg) and grain sizes. The results were compared with the numerical sediment guidelines used in North America as well as literature values reported for similar studies conducted in Izmit Bay and Izmir Bay. The metal levels were also evaluated according to the enrichment factor and contamination factor analyses. The analyses revealed significant anthropogenic pollution of Hg, Pb, Zn, and As in the surficial sediments of Nemrut Bay.     

Heavy metal concentrations in water, suspended matter, and sediment from Gökova Bay, Turkey

The contents of heavy metals (Fe, Mn, Pb, Cu, Cd, and Hg) dissolved in water and suspended solids of Gökova Bay—partly and fully sampled in 2005 and 2006, respectively—are quite higher than the average values encountered in uncontaminated sea water. The high concentrations are associated with terrestrial inputs from the mining zones and anthropogenic (domestic + industrial) sources. Moreover, the distribution of Fe and Cu is affected by primary production because these elements function as nutrients in biological activities. The Cr, Ni, and Fe concentrations of surface sediments are above the shale average. The Cr and Ni contents of surface sediments representative of river mouths strongly correlate with total phosphorus contents. In a sulfide-poor environment, Pb and Cu were concentrated at a higher ratio in surface sediments than Cd, probably due to higher stabilities of their surface complexes with amorphous iron oxides and clay minerals existing as major components in the sediments. The exceptional enrichment of Zn may be attributed to double oxide formation with amorphous iron oxides in sediments. The high metal values are most probably caused by terrestrial inputs from anthropogenic sources and the mining zones at the southeast part of the bay. The Al, Mn, Pb, Cu, Zn, and Hg contents are below the shale average. The low values have possibly originated from the coarse-grained sandy sediments having a low affinity for metals. There are no distinct differences in the metal distributions in water and suspended matter between the years 2005 and 2006 in the bay, probably due to low sedimentation rates.     

Impact of anthropogenic input on physicochemical parameters and trace metals in marine surface sediments of Bay of Bengal off Chennai, India

The study of heavy metal distribution in coastal surface sediments is an important component in understanding the exogenic cycling as well as in assessing the effect of anthropogenic influences on the marine ecosystem. In this study, surface sediment samples were collected from five different traverses along the innershelf of Bay of Bengal, off Chennai, India during pre- and post-monsoon seasons. The results of Spearmen correlation matrix, factor and cluster analysis, enrichment and contamination factor analysis, and geoaccumulation index of the heavy metals analyzed in the collected surface sediment were discussed. The level of both enrichment and contamination factor are shown in following order Cd > Cu > Cr > Ni > Pb > Co > Zn > Mn > Fe > Hg. The geoaccumulation index suggests that Cd and Cu are strongly to extremely pollute the sediments in both seasons. The results strongly indict anthropogenic sources for moderate input of Cd and Cu in to the innershelf of Chennai coast.     

Heavy metals partitioning in sediments of the Kabini River in South India

Cu, Cr, Fe, Mn, Ni, Pb, and Zn in the sediments of the Kabini River, Karnataka, India was studied to determine the association of metal with various geochemical phases by sequential extraction. The variations of heavy metal concentration depend on the lithology of the river basin and partly on anthropogenic activities. The Kabini River sediments are dominated by Sargur supracrustals with amphibolites, gneisses, carbonates, and ultrabasic rocks weathering into gneissic and serpentine soils carrying a natural load of cationic heavy metals. The source of heavy metals in the Kabini riverbed sediments is normally envisaged as additional inputs from anthropogenic over and above natural and lithogenic sources. Geochemical study indicates the metals under study were present mostly in the least mobilizable fraction in the overlying water and it is concluded that heavy metals in these sediments are to a great extent derived from multisource anthropogenic inputs besides geochemical background contributions The results show that lead and chromium have higher potential for mobilization from the sediment due to higher concentration at the exchangeable ion and sulfide ion bounded, also Cu and Pb have the greatest percentage of carbonate fraction, it means that the study area received inputs from urban and industrial effluents. Association of the Fe with organic matter fraction can be explained by the high affinity of these elements for the humic substances. Further, Zn and Ni reveal a significant enrichment in sediment and it is due to release of industrial wastewater into the river. These trace metals are possible contaminants to enter into aquatic and food chain.     

The impact of an industrial complex on freshly deposited sediments, Chener Rahdar river case study, Shiraz, Iran

Concentrations of elements (As, Co, Cu, Ni, Mo, Pb, V, and Zn) are studied in the sediments of two adjacent stretches of Chenar Rahdar river. The first stretch (S1) is influenced by urban and arable land wastewater, and the second (S2) is mainly loaded with industrial effluents. The average abundance order of heavy metals content in S1 sediments is Ni > V > Zn > Cu > Co > As > Pb > Mo and in S2 sediments is Ni > Zn > V > Cu > Mo > Pb > Co > As. The maximum average concentration for these heavy metals (except for As) occurs in the S2 sediments. The contamination factor (CF) base of background in S1 for eight analyzed elements is moderate. The CF for Cu, Zn, and Pb in S2 sediments is considerable. The highest CF in S1 and S2 sediments is observed for Mo (CF = 10.95 and 12.41) and indicates very high contamination. The application of modified degree of contamination values (mC_d) indicates low and high degree of contamination (1.89–4.15) in S1 and S2, respectively. Calculated enrichment factors (EF) reveal enrichment of Mo and As in S1 and Zn, Cu, Mo, and Pb in S2 compared to the average abundances of background level. The maximum EF for Mo is 7.61 (significant enrichment), while Pb, Zn, and Cu with maximum EF between 2 and 5 indicate moderate contamination. Principal component analysis (PCA) shows distinctly different elemental associations in S1 and S2 sediments. The strong association of Zn, Co, Ni, Sc, Cu, Al and Fe in S1 suggests a similar source. The results of PCA for Zn, Pb, Mo and Cu in S2 (componente2) indicate that these metals are influenced by anthropogenic activity. Also, high loading heavy metals with OC (0.97) indicate that organic carbon plays a significant role in the distribution and sorption of these heavy metals in the sediments. Factor analysis indicates that As and Mo behave differently in sediment samples.     

Investigation of heavy metal content in the suspended particulate matter and sediments of inner Gokova Bay and creeks

The Bay of Gokova in Southeastern Aegean Sea (Turkey) is important by the potential of agricultural, municipal, and tourism activities. In addition, there is no industrial plant within the area in the Aegean Sea. Kad?n Creek (Azmak) and Ak?ap?nar Creek (Azmak) flowing into the inner Gokova Bay are one of the important factors in determining the character of the inner Gokova Bay. In this study, nine stations were selected in the inner Gokova Bay, Kad?n Creek, and Akcap?nar Creek. The concentrations of Cd, Cu, Fe, Pb, and Zn were measured in suspended particulate matter (SPM) and sediments. The samples of sediments and SPM were collected in between February 2008 and September 2008. The aim of the study is searching the change of concentrations of Cd, Cu, Fe, Pb, and Zn in suspended particulate matter and sediments in the inner Gokova bay, Kad?n Creek, and Ak?ap?nar Creek. It has been identified that the metal concentrations in the creeks are higher than the metal concentrations in the marine environment. It has also been observed that the concentrations of Pb, Cd, and Cu in summer season have been higher than in the winter season, but the concentrations of Fe and Zn have not shown a significant difference between in summer and winter seasons. The obtained results show that the some heavy metals are caused by the agricultural, municipal, and tourism activities operating in the coastal areas and terrestrial environment, and they are transported from the creeks to the Gokova Bay by suspended particulate matter.     

Chemometric study on the trace metal accumulation in the sediments of the Cochin Estuary―Southwest coast of India

The distribution and accumulation of trace metals in the sediments of the Cochin estuary during the pre-monsoon, monsoon and post-monsoon periods were investigated. Sediment samples from 14 locations were collected and analysed for the metal contents (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb), organic carbon, total nitrogen, total sulphur and grain size. The data were processed using statistical tools like correlation, factor and cluster analysis. The study revealed an enrichment of Cd and Zn in the study area particularly at station 2, which is confirmed by enrichment factor, contamination factor and geoaccumulation index. The factor analysis revealed that the source of Cd and Zn may be same. The study indicated that the spatial variation for the metals like Mg, Cr, Fe, Co, Ni, Cu, Zn, Cd and Pb were predominant unlike Mn which shows a temporal variation. The strong association of trace metals with Fe and Mn hydroxides and oxides are prominent along the Cochin estuary. The anthropogenic inputs of industrial effluents mainly control the trace metals enrichment in the Cochin estuary.     

Total and Leachable Heavy Metals in Muddy and Sandy Sediments of Egyptian Coast Along Mediterranean Sea

The assessment of marine pollution due to metals was made for surficial sediments sampled from 20 sites along Mediterranean coast of Egypt. The samples were dried, acid digested and analyzed for leachable and total heavy metal contents (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) by flame atomic absorption spectrophotometer (air–acetylene) with deuterium background correction. Evaluation of the heavy metals pollution status was carried out using enrichment factors (EFs), the effect range-low (ERL) and the effect range-median (ERM). The study showed high concentrations of Cd, Co, Pb, Ni and moderate concentrations of Cr, Cu and Mn were contaminated in the sediments of studied sites. The results of Spearman correlation, factor and cluster analysis of the heavy metals analyzed in the collected sediment were discussed. The main source of contamination is the offshore oil field and industrial wastes, which arise due to the ineffective and inefficient operation equipments, illegal discharge and lack of supervision and prosecution of offenders.     

长江南京段近岸沉积物和土壤中重金属分布特征分析

通过测定沉积物和土壤中Cd、Pb、Cr、Zn、Cu、Ni 6种重金属元素的平均含量,计算其富集因子,分析长江南京段近岸沉积物和土壤中重金属的空间分布特征,结果表明,几种重金属在沉积物中的富集次序为:CdPbCr1NiCuZn,在土壤中为:CdZnCu1CrPbNi,除Zn和Cu外,其他几种金属在沉积物中的富集程度高于土壤,同时Cd的含量超过土壤环境质量三级标准。以Cd和Pb为例分析了重金属含量与沉积物粒级之间的关系,回归分析显示,Cd、Pb的含量与颗粒物的粒级呈显著的相关性,与细颗粒物的含量有密切关系,细颗粒携带的重金属,在长江水力分选作用下到达下游,成为沉积物中重金属的主要来源。     

Distribution and chemical partitioning of heavy metals in marine near-shore sediment cores: a case study from the Xugou, Lianyungang, China

The concentrations and chemical partitioning of heavy metals (Co, Cr, Ni, Zn, Cu, and Pb) in the marine near-shore sediment cores were investigated. Typically, the mean concentrations from Core B sediment samples were 98.6, 21.1, 47.0, 46.4, 107.6, and 31.9 mg kg^???1 for Cr, Co, Ni, Cu, Zn, and Pb, respectively. The heavy metal concentrations were normalized to commonly used reference elements Al, Li, Sc, and total organic carbon. Based on Pearson coefficients, Li was found to be a good normalizer for Co (r?= 0.974), Cr (r?= 0.967), Ni (r?= 0.898), and Zn (r?= 0.929) in 80 sediment samples from three sampling sites. However, the correlation coefficients between Li and Cu, and Li and Pb were relatively low. Multivariate statistic approaches (Principal Component Analysis and Cluster Analysis) were adopted for data treatment, allowing the identification of two main factors controlling the heavy metal variability in the sediments. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. The results showed that the residual, Fe/Mn oxides and Organic/sulfide fractions were dominant geochemical phases in the enriched sections, indicating low bioavailability of heavy metals in sediments.     

Vertical distribution of heavy metals in soil profile in a seasonally waterlogging agriculture field in Eastern Ganges Basin

The accumulation of heavy metals in soil and water is a serious concern due to their persistence and toxicity. This study investigated the vertical distribution of heavy metals, possible sources and their relation with soil texture in a soil profile from seasonally waterlogged agriculture fields of Eastern Ganges basin. Fifteen samples were collected at ～0.90-m interval during drilling of 13.11 mbgl and analysed for physical parameters (moisture content and grain size parameters: sand, silt, clay ratio) and heavy metals (Fe, Mn, Cr, Cu, Pb, Zn, Co, Ni and Cd). The average metal content was in the decreasing order of Fe?>?Mn?>?Cr?>?Zn?>?Ni?>?Cu?>?Co?>?Pb?>?Cd. Vertical distribution of Fe, Mn, Zn and Ni shows more or less similar trends, and clay zone records high concentration of heavy metals. The enrichment of heavy metals in clay zone with alkaline pH strongly implies that the heavy metal distributions in the study site are effectively regulated by soil texture and reductive dissolution of Fe and Mn oxy-hydroxides. Correlation coefficient analysis indicates that most of the metals correlate with Fe, Mn and soil texture (clay and silt). Soil quality assessment was carried out using geoaccumulation index (I _geo), enrichment factor (EF) and contamination factor (CF). The enrichment factor values were ranged between 0.66 (Mn) and 2.34 (Co) for the studied metals, and the contamination factor values varied between 0.79 (Mn) and 2.55 (Co). Results suggest that the elements such as Cu and Co are categorized as moderate to moderately severe contamination, which are further confirmed by I _geo values (0.69 for Cu and 0.78 for Co). The concentration of Ni exceeded the effects-range median values, and the biological adverse effect of this metal is 87 %. The average concentration of heavy metals was compared with published data such as concentration of heavy metals in Ganga River sediments, Ganga Delta sediments and upper continental crust (UCC), which apparently revealed that heavy metals such as Fe, Mn, Cr, Pb, Zn and Cd are influenced by the dynamic nature of flood plain deposits. Agricultural practice and domestic sewage are also influenced on the heavy metal content in the study area.     

Assessment of Cu, Pb, and Zn contamination in sediment of north western Peninsular Malaysia by using sediment quality values and different geochemical indices

Surface sediments were collected from the north western aquatic area (13 intertidal sites and 5 river drainages) of Peninsular Malaysia, which were suspected to have received different anthropogenic sources. These sites included town areas, ports, fishing village, industrial areas, highway sides, jetties and some relatively unpolluted sites. The present study revealed that 4.79-32.91 μg/g dry weight for Cu, 15.85-61.56 μg/g dry weight for Pb, and 33.6-317.4 μg/g dry weight for Zn based on 13 intertidal surface sediments while those based on 5 river drainage surface sediments were 10.24-119.6 μg/g dry weight for Cu, 26.7-125.7 μg/g dry weight for Pb and 88.7-484.1 μg/g dry weight for Zn. In general, the metal levels in the drainage sediments are higher than in the intertidal sediments, suggesting dilution factor in the intertidal sediment and direct effluent from point sources in the drainage sediment. In particular, the total concentrations of Cu, Pb, and Zn for the sampling site at Kuala Kurau Town exceeded the Effect Range Median values for Cu, Pb, and Zn for assessments of sediment quality values for freshwater sediment as proposed by MacDonald et al. (Arch Environ Contam Toxicol 39:20-31, 2000), thus adverse biological effects would be observed above this level. Assessment using enrichment factor (using Fe as a normalizer) and geoaccumulation index showed that the three metals at Kuala Kurau Town and Juru Industry drainage were evidenced as having more enrichment and mostly due to non-natural sources. However, caution should be exercised that the interpretation can only become valid when the ratios, indices, and sediment quality values are combined. This is due to the fact that not all the established indices are applicable and, to a certain extent, some of them should be further revised and improved to suit a different metal for Malaysian sediment. Undoubtedly, sites near drainages at Kuala Kurau Town and Juru River Basin need greater attention to mitigate the heavy metal pollution in the future.     

Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca

Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8–156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.     

Spatial, temporal, and speciation variations of heavy metals in sediments of Nan'ao Island, a representative mariculture base in Guangdong coast, China

Heavy metals in sediments from Baisha Bay, Nan'ao Island, one of Guangdong Province's largest mariculture bases in Southern China, were investigated. The results display that the concentrations of 6 heavy metals from surface sediments were 0.040-0.220 (Cd), 24.22-39.61 (Pb), 25.30-42.66 (Cr), 10.83-19.54 (Ni), 15.06-39.24 (Cu) and 55.12-141.73 mg kg(-1) (Zn), respectively. The highest concentrations and the greatest increasing rates of heavy metals were found in a sediment core in a fish cage culture area due to receiving sewage discharge, uneaten fish bait, and boat gasoline combustion. Cd was preferentially associated with the acid-soluble fraction and Pb mainly with the reducible fraction in surface sediments. Meanwhile, Cd and Pb displayed greatest labile fractions, indicating anthropogenic origin. A principal component analysis (PCA) revealed three groupings (Cd; Cr, Ni and Cu; Pb and Zn) that mainly result from different distributions of the metals in the various fractions. The ecological risk of the polluted sediments stemmed mainly from Cd, and from Pb and Cu to a lesser degree. It is suggested that the density of fish-stocking be controlled, periodic movement of rafts (cages) be introduced, and the total numbers of net-cages and human activities in the mariculture zones be restricted. in order to facilitate the recovery of the polluted sediment.     

An assessment of metal contamination risk in sediments of Hara Biosphere Reserve,southern Iran with a focus on application of pollution indicators

The aim of this study was to assess the pollution status of metals in sediments of Hara Biosphere Reserve using pollution indicators. For this purpose, sediment samples from nine locations were collected and characterized for metal content (Pb, Cr, Zn, Cu, and Fe) using the total digestion technique. Comparison of metal concentrations with that of sediment quality guidelines (SQGs) demonstrated no association with negative biological effects for Cu and Zn, while the values of Pb and Cr mainly illustrated to have association with negative biological effects. The results of the geo-accumulation index (I _geo) indicated no contamination for Cr, Cu, Zn, and Fe, while the values of Pb demonstrated to have moderate contamination based on I _geo values. The analysis of the enrichment factor (EF) showed no enrichment for Cu and Zn and minor enrichment for Pb and Cr. Similar results were also found for quantification of contamination (QoC) analysis, where the values of Cu and Zn demonstrated to have a geogenic source of contamination, while the values of Pb and Cr mainly illustrated to have an anthropogenic source of contamination. According to EF and QoC calculations, the values of Cu and Zn were derived mainly from natural processes and exposure of material from the earth’s crust, while the values for Pb and Cr were enriched by anthropogenic activities. The results of the contamination factor (C _f ⁱ ) demonstrated low contamination levels for Fe, Cr, Zn, and Cu and moderate contamination levels for Pb. The pollution load index (PLI), showing the overall contamination of metals, demonstrated moderate pollution status in the study area.     

Heavy metal assessment using geochemical and statistical tools in the surface sediments of Vembanad Lake, Southwest Coast of India

The geochemical distribution and enrichment of ten heavy metals in the surface sediments of Vembanad Lake, southwest coast of India was evaluated. Sediment samples from 47 stations in the Lake were collected during dry and wet seasons in 2008 and examined for heavy metal content (Al, Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co, Cd), organic carbon, and sediment texture. Statistically significant spatial variation was observed among all sediment variables, but negligible significant seasonal variation was observed. Correlation analysis showed that the metal content of sediments was mainly regulated by organic carbon, Fe oxy-hydroxides, and grain size. Principal component analysis was used to reduce the 14 sediment variables into three factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Pollution intensity of the Vembanad Lake was measured using the enrichment factor and the pollution load index. Severe and moderately severe enrichment of Cd and Zn in the north estuary with minor enrichment of Pb and Cr were observed, which reflects the intensity of the anthropogenic inputs related to industrial discharge into this system. The results of pollution load index reveal that the sediment was heavily polluted in northern arm and moderately polluted in the extreme end and port region of the southern arm of the lake. A comparison with sediment quality guideline quotient was also made, indicating that there may be some ecotoxicological risk to benthic organisms in these sediments.     

An assessment of heavy metal contamination in soils of fresh water aquifer system and evaluation of eco-toxicity by lithogenic implications

The chemistry of heavy metals in sediments with respect to bio-availability and chemical reactivity is regulated by pH, texture, and organic matter contents of the sediments and specific binding form and coupled reactivity of the metals within. To focus on the metal distribution (Fe, Mn, Pb, Cd, Zn, Co, Cu, and Cr) and behavior in a fresh water aquifer system along with the ecological toxicity parameters, a four-step sequential extraction method was applied on 18 Eastern Ghats’ type sediments from fluorosis-hit Nayagarh district, India. Geo-accumulation index of metals in the sediments indicates that they are practically uncontaminated and/or less contaminated with and Fe, Mn, and Cu; contaminated to moderately contaminated with Pb, Zn, and Cr; and strongly contaminated with Cd. Rather, more than 80 % recovered Cd metal concentration in sediments constitute the labile fractions. Temporal clustering of metal fractions indicates transition metal fraction distribution claiming the sediment pH regulation. Similarly, base metal distribution accounts for organic carbon and soil conductivity due to their greater availability in exchangeable and sulfide fractions. Correlation analysis and factor analysis scores demonstrate lack of inter-relationship between transition group and base metal fractions. High fluoride concentration in ground water is associated with high sodium-bicarbonate-iron affinity with elevated pH values (i.e., >7.0) and high positive factor score with the total iron concentration in ground water.     

Assessment of sediment quality in the Mediterranean Sea–Boughrara lagoon exchange areas (southeastern Tunisia): GIS approach-based chemometric methods

Concentrations of selected heavy metals (Cd, Pb, Zn, Cu, Mn, and Fe) in surface sediments from 66 sites in both northern and eastern Mediterranean Sea–Boughrara lagoon exchange areas (southeastern Tunisia) were studied in order to understand current metal contamination due to the urbanization and economic development of nearby several coastal regions of the Gulf of Gabès. Multiple approaches were applied for the sediment quality assessment. These approaches were based on GIS coupled with chemometric methods (enrichment factors, geoaccumulation index, principal component analysis, and cluster analysis). Enrichment factors and principal component analysis revealed two distinct groups of metals. The first group corresponded to Fe and Mn derived from natural sources, and the second group contained Cd, Pb, Zn, and Cu originated from man-made sources. For these latter metals, cluster analysis showed two distinct distributions in the selected areas. They were attributed to temporal and spatial variations of contaminant sources input. The geoaccumulation index (I _geo) values explained that only Cd, Pb, and Cu can be considered as moderate to extreme pollutants in the studied sediments.