Trace Element Contamination Research Articles

Functional diversity of ectomycorrhizal fungal communities is reduced by trace element contamination

Trait-based approaches are useful tools to explain ecological assembly rules and ecosystem functioning. However, their use for soil microbiota has not been explored in depth yet. We explored trait-based functional changes of ectomycorrhizal (ECM) fungal communities associated with holm oak (Quercus ilex subsp. ballota) in a trace element contaminated area.We found a variation in ECM fungal species composition determined by soil C, Ca and trace elements; however, taxonomic diversity was not dependant on contamination level. Mean trait values of ECM fungal communities showed less rhizomorph and emanating hyphae production when increasing contamination, and the community converged towards species developing rhizomorphs less frequently. We suggest that trace elements in soils acted as the main environmental filter of trait diversity of ECM fungal communities. The effect of soil nutrients, i.e. soil C, affected the community mean trait values of emanating hyphae but did not cause a convergence in its distribution.In summary, we found a reduction in the functional diversity of ECM fungal communities due to trace element contamination with potential to affect ecosystem functioning. This finding supports the potential of trait-based approaches to assess changes in the functional diversity of soil microbial communities.

Seasonal dynamics of trace elements in sediment and seagrass tissues in the largest Zostera japonica habitat, the Yellow River Estuary, northern China

Trace element accumulation is an anthropogenic threat to seagrass ecosystems, which in turn may affect the health of humans who depend on these ecosystems. Trace element accumulation in seagrass meadows may vary temporally due to, e.g., seasonal patterns in sediment discharge from upstream areas. In addition, when several trace elements are present in sufficiently high concentrations, the risk of seagrass loss due to the cumulative impact of these trace elements is increased. To assess the seasonal variation and cumulative risk of trace element contamination to seagrass meadows, trace element (As, Cd, Cr, Cu, Pb, Hg, Mn and Zn) levels in surface sediment and seagrass tissues were measured in the largest Chinese Zostera japonica habitat, located in the Yellow River Estuary, at three sites and three seasons (fall, spring and summer) in 2014–2015. In all three seasons, trace element accumulation in the sediment exceeded background levels for Cd and Hg. Cumulative risk to Z. japonica habitat in the Yellow River Estuary, from all trace elements together, was assessed as “moderate” in all three seasons examined. Bioaccumulation of trace elements by seagrass tissues was highly variable between seasons and between above-ground and below-ground biomass. The variation in trace element concentration of seagrass tissues was much higher than the variation in trace element concentration of the sediment. In addition, for trace elements which tended to accumulate more in above-ground biomass than below-ground biomass (Cd and Mn), the ratio of above-ground to below-ground trace element concentration peaked at times corresponding to high water discharge and high sediment loads in the Yellow River Estuary. Overall, our results suggest that trace element accumulation in the sediment may not vary between seasons, but bioaccumulation in seagrass tissues is highly variable and may respond directly to trace elements in the water column.

Contrasting mobilization of elements in contact with sediment from Lake Roosevelt and the Upper Columbia River, Washington, USA

Trace element contamination is known to be widely present in sediment of Lake Roosevelt and the riverine reach of the Columbia River in Washington State, USA due to discharges from several smelters and numerous mines dating back to the mid-1800's. In this study, the concentrations of aqueous elements in contact with bed sediment from the lake and river were examined under varying degrees of physical mixing and time scales. Contrasting geochemical processes affecting aqueous concentrations were inferred from the release of major ions (Ca and Si), elements enriched in metallurgical smelter slag (Cu and Sb), and redox-sensitive species (Fe, Mn, Mo and U). Releases of major ions reflect the contrasting sediment substrates along the length of the river and large reservoir. Calcium released from carbonate minerals and slag particles was most pronounced in regions of carbonate bedrock and near sediment deposits with a large component of slag material, while Si released from unconsolidated glacial/fluvial sediment increased with increasing distance downstream. Sb release was a consistent indicator of slag presence and weathering, possibly because its anionic nature inhibits readsorption onto metal oxides. In contrast, Cu release was quite variable, likely due to varying degrees of copper readsorption or co-precipitation onto metal oxides. The release of Mo and U appeared to be affected by redox conditions, which were assessed using aqueous Fe and Mn concentrations.

Application of multivariate analysis to investigate the trace element contamination in top soil of coal mining district in Jorong, South Kalimantan, Indonesia

Multivariate analysis is applied to investigate geochemistry of several trace elements in top soils and their relation with the contamination source as the influence of coal mines in Jorong, South Kalimantan. Total concentration of Cd, V, Co, Ni, Cr, Zn, As, Pb, Sb, Cu and Ba was determined in 20 soil samples by the bulk analysis. Pearson correlation is applied to specify the linear correlation among the elements. Principal Component Analysis (PCA) and Cluster Analysis (CA) were applied to observe the classification of trace elements and contamination sources. The results suggest that contamination loading is contributed by Cr, Cu, Ni, Zn, As, and Pb. The elemental loading mostly affects the non-coal mining area, for instances the area near settlement and agricultural land use. Moreover, the contamination source is classified into the areas that are influenced by the coal mining activity, the agricultural types, and the river mixing zone. Multivariate analysis could elucidate the elemental loading and the contamination sources of trace elements in the vicinity of coal mine area.

Trace element dynamics of biosolids-derived microbeads

This study focused on quantifying and characterising microbeads in biosolids (i.e., treated sewage sludge), and in examining interactions of microbeads with trace elements when biosolids are added to soil. Under laboratory conditions, batch experiments were conducted to investigate the adsorption of Cu onto pure and surface modified microbeads suspended in soil. The ecotoxicity of microbead-metal complexes to soil microbial activities was also investigated by monitoring basal respiration and dehydrogenase activity. Concentrations of the microbeads were 352, 146, 324, and 174 particles kg−1 biosolids for ≤50, 50–100, 100–250, 250–1000 μm size fractions, respectively. The Scanning Electron Microscope (SEM) images illustrated wrinkled and fractured surfaces due to degradation. The adsorption of dissolved organic matter onto microbeads was confirmed through FT-IR microscopy, while using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) the presence of trace metals including Cd (2.34 ng g−1), Cu (180.64 ng g−1), Ni (12.69 ng g−1), Pb (1.17 ng g−1), Sb (14.43 ng g−1), and Zn (178.03 ng g−1) was revealed. Surface modified microbeads were capable of adsorbing Cu compared to the pure microbeads, which may be attributed to the complexation of Cu with dissolved organic matter associated with the microbeads in the matrix. It was further revealed that the biosolids derived microbead-metal complexes decreased soil respiration (up to ∼ 26%) and dehydrogenase activity (up to ∼ 39%). Hence, microbeads reaching biosolids during wastewater treatment are likely to serve as a vector for trace element contamination, transportation, and toxicity when biosolids are applied to soil.

Seasonal assessment of metal trace element contamination by PCA in Seybouse wadi (Algeria)

Abstract The seasonal assessment of trace metallic elements in Seybouse wadi waters and sediments is performed by principal component analysis (PCA). This wadi is the second of Algeria considering its length and vast basin, and opens into the coastline of Annaba in the Mediterranean Sea. Monitoring mineral micropollutants showed that waters are primarily contaminated by aluminum Al, selenium Se, zinc Zn, copper Cu, chromium Cr, lead Pb, cadmium Cd and arsenic As, whereas sediments are essentially soiled by arsenic As, chromium Cr and nickel Ni. PCA shows a clear relation between the season and the type of metallic contamination, and it also helps in understanding its origins.

Evaluation of glyphosate drift and anthropogenic atmospheric trace elements contamination by means of lichen transplants in a southern Italian agricultural district

Ecophysiological biomarkers and atmospheric contamination due to glyphosate and trace elements were monitored in a southern Italian agricultural district by means of transplanted thalli of the lichen Pseudevernia furfuracea. Glyphosate exhibited a significant geographical pattern (east side > west side) and a drift source area equal to 32% of the monitoring sites. Moreover, based on the surface area of the study area and a wind quantitative relationship (WQR) with glyphosate thalli concentrations, our data support the idea that pesticide drift extends over an area of several square kilometers. Of the eight elements preliminarily classified as enriched, four were considered prevalently of geogenic origin (Al, Ti, Ni, Co) and four of anthropogenic origin (Cu, Mn, Sn, Sb), although only Sb and Cu passed rigorous statistical testing supporting a real difference from pre-exposure levels. The contribution of local sources was evaluated based on the relative increase of Cu, Mn, Sb, and Sn versus Ti. Cu and Mn were associated mainly with a biomass power plant (BPP), with Cu showing extremely high levels of contamination involving 20% of the monitoring sites. Sb and Sn were associated with spatial variation of the traffic rate. The mycobiont and photobiont showed an evident zonation of the levels of their physiological parameters, with oxidative stress being significantly associated with both the biomass power plant and Cu/Ti. Our results suggest that croplands are potentially exposed to various hazards: over-exposure to pesticides due to drift processes, diffuse low traffic levels promoting Sb enrichment, and acute Cu pollution affected by BPP emissions.

The great egret (Ardea alba) as a bioindicator of trace element contamination in the São Paulo Metropolitan Region, Brazil

To investigate great egret as a possible bioindicator of trace element contamination, the concentrations of Br, Cd, Co, Cs, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Se and Zn were determined in livers of great egrets (Ardea alba) by the methods of Instrumental Neutron Activation Analysis and Atomic Absorption Spectrometry. It was observed that the levels of trace elements found in their livers may indicate contamination of the studied region. Thus, the livers of this species can be considered as a suitable bioindicator of contamination of the aquatic systems in the Sao Paulo Metropolitan Region.

Seasonal assessment of trace element contamination in intertidal sediments of the meso-macrotidal Hooghly (Ganges) River Estuary with a note on mercury speciation

The spatial and seasonal distribution of trace elements (TEs) (n=16) in surficial sediment were examined along the Hooghly River Estuary (~175km), India. A synchronous elevation of majority of TEs concentration (mgkg−1) was encountered during monsoon with the following descending order: Al (67070); Fe (31300); Cd (5.73); Cr (71.17); Cu (29.09); Mn (658.74); Ni (35.89). An overall low and homogeneous concentration of total Hg (THg=17.85±4.98ngg−1) was recorded in which methyl mercury (MeHg) shared minor fraction (8–31%) of the THg. Sediment pollution indices, viz. geo-accumulation index (Igeo) and enrichment factor (EF) for Cd (Igeo=1.92–3.67; EF=13.83–31.17) and Ba (Igeo=0.79–5.03; EF=5.79–108.94) suggested high contamination from anthropogenic sources. From factor analysis it was inferred that TEs primarily originated from lithogenic sources. This study would provide the latest benchmark of TE pollution along with the first record of MeHg in this fluvial system which recommends reliable monitoring to safeguard geochemical health of this stressed environment.

Quality of water resources in the Niger basin and in the region of Lagos (Nigeria)

Abstract Water quality studies in Nigeria are usually conducted at local scales and limited to a restricted number of chemical contaminants, while reliable data on trace metal concentrations (including arsenic) are relatively scarce. This study focuses on the quality of available renewable water resources in terms of major ion and trace element concentrations at selected sampling locations in the Lower River Niger basin and part of the Lagos region. A screening of water contamination by arsenic and heavy metals was carried out through water sampling at selected locations using in situ measurement and laboratory testing to estimate heavy metal concentrations and water type. The analysis reveals moderate trace element contamination of the water resources, with the exception of Pb, while Mn and, to a lesser extent, Al exceeded WHO quality standards, but the Arsenic concentrations are within drinking water quality standards and are safe for consumption and irrigation, while the water type is Bicarbonate.

Spatiotemporal variation and exposure risk to human health of potential toxic elements in suburban vegetable soils of a megacity, SW China, 2012-2016.

Trace element contamination in soils of vegetable fields can threat public health. Seven potential toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) in suburban vegetable soils of Chengdu city, Southwest China, in 2012 and 2016, were analyzed to identify their sources with the spatiotemporal variation and assess their contamination and health risk for residents. The results showed that the concentrations of soil elements did not increase significantly in 2016 compared with that in 2012, whereas their spatial distributions altered markedly. The hot spots of soil As, Cd, and Pb as well as Cu and Zn in 2016 revealed the anthropogenic sources including agricultural activities, industrial emissions, road dust with heavy traffic, and open burning of solid waste. The apparent spatial difference of anthropogenic elements was related to the layout of land use surrounding the vegetable field. The contamination of soil elements decreased in the order of Cd > As ≈ Zn > Cu ≈ Pb > Cr ≈ Ni in 2012 and Cd > Zn > As ≈ Cu ≈ Pb > Cr ≈ Ni in 2016, and the vegetable soils were slightly to moderately contaminated by these elements through integrated contamination index. The sites affected by thetrace elements did not increase in 2016 than in 2012, whereas the sites with relatively high contamination increased markedly. The non-carcinogenic risk of trace elements was generally acceptable, and children showed higher health risk than adults. The As carcinogenic risk for children varied between 5.48 × 10-5 and 1.59 × 10-4 in 2012 and between 4.40 × 10-5 and 1.82 × 10-4 in 2016, and the sites above acceptable levels (> 10-4) reached 60.6% and 48.5% in 2012 and 2016, respectively. The health risk of As in the vegetable soils should be paid more attention due to its high toxicity.

Trace elements in a Mediterranean scorpaenid fish: Bioaccumulation processes and spatial variations

The black scorpionfish Scorpaena porcus, a carnivorous sedentary species, was studied as an indicator of local trace element (TE) contamination of coastal fish species in the northwestern Mediterranean Sea. Fish were collected in seagrass meadows in winter 2012 at four sampling sites: three were located near Marseille, a highly urbanized and industrial area that is subjected to various types of contaminant inputs, and one was located near Hyères, a less urbanized area. Size, sex, age and diet of fish were determined before stable isotope and TE analyses. C and N isotopic compositions and concentrations of nine TEs (As, Ba, Cd, Cu, Cr, T-Hg, Ni, Pb, and Zn) were determined in dorsal white muscle. Most TEs did not bioaccumulate in S. porcus, as no increase in TE concentrations with increasing size, age or trophic level of fish was evident. Total mercury (T-Hg) was the only element to bioaccumulate and biomagnify, displaying strong positive correlations of its concentration with age (r = 0.88, p < 0.01), length (r = 0.84, p < 0.01) and δ15N value (r = 0.68, p < 0.01). Compared with the reference site, higher concentrations of As, Ba, Cd, T-Hg, Pb, and Zn were recorded in fish collected at one or all of the Marseille site. In contrast, no difference was observed for Cr, Cu, and Ni concentrations with site. Spatial differences in TE concentrations in S. porcus were related to differences in isotopic composition and to the primary environmental characteristics and human activities prevailing at each site. Concentrations of Cd, T-Hg and Pb in fish muscle (priority substances for monitoring) were all below the maximum permitted European values.

Background levels of some trace elements in calcareous soils of the Hamedan Province, Iran

Natural concentrations of trace elements are necessary for assessing trace elements contamination affected by anthropogenic activities in soils. This study was conducted to establish background concentrations of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in 50 unpolluted native soils with a total of 100 soil samples (surface and subsurface soil layers) in Hamedan province of Iran. Different methods have been used for the evaluation of background limits, and the relationships between soil properties and trace elements concentrations and among trace element concentrations have been analyzed. Values from Geometric Mean (GM) procedure had the lowest background limit, while the GM×GSD2 (geometric standard deviation) method produces the highest background limits. The percentage of outliers in Median+2MAD (median absolute deviation) ranged from 4.0 to 16.0% for natural data and from 0.0 to 12% for log-transformed data. The smallest outlier percentage was for Cd and Cr, and it was higher for Co, Cu, and Zn. The obtained geochemical baseline concentrations (mgkg−1) based on Median+2MAD were (log-transformed data) Cd 1.36, Co 15.42, Cr (natural data) 36.69, Cu 29.99, Fe 25.79 (gkg−1), Mn 368.68, Ni (natural data) 53.59, Pb 39.60, Zn 103.80. Carbonate calcium had significant negative correlations with Co, Cr, Cu, Fe, and Mn, indicating that trace elements are not included in the crystal structure of secondary carbonate minerals; consequently, accumulation of CaCO3 causes a dilution effect in the soils. The content of clay, silt and organic matter had significant role in the accumulation of Mn, Ni, and Pb in the soils of the studied area. Significant correlation was found among Co, Cr, Cu, Fe, Mn, and Ni and between Zn with Cd, Cr, Cu, Mn, and Ni. Factor analysis of trace elements explored six factors attributing 64.1% of the total variability. According to the results found by upper whisker method, correlation analysis and factor analysis, studied trace elements contaminated none of the soil samples, natural accumulation processes influenced their contents in soils and origin of trace elements may be lithogenic, but their sources may be different.

Metal bioaccumulation and oxidative stress profiles in Ruditapes philippinarum – insights towards its suitability as bioindicator of estuarine metal contamination

The Manila clam Ruditapes philippinarum is an invasive bivalve in Europe, widely distributed, with a great ability to tolerate a broad range of environmental conditions. Despite the ability to reflect contamination, its suitability as bioindicator is not consensual. This study provided clarification on this issue by evaluating the ability of R. philippinarum to signalise trace element contamination in an estuary chronically impacted by metals and metalloids (Tagus estuary, Portugal). A multidimensional approach was carried out in two differently contaminated sites (Barreiro – BAR; Alcochete – ALC) in warm and cold periods, combining sediment contamination, bioaccumulation of trace elements (As, Cd, Pb and Hg), and a battery of oxidative stress biomarkers in two R. philippinarum organs (digestive gland and gills). Sediments from BAR exhibited higher concentrations of all the elements than those from ALC, in line with the anthropogenic pressures identified for both estuarine areas. Likewise, clams from BAR showed higher concentrations of As and Pb in the digestive gland (cold period) and Pb in the gills (warm and cold periods) in comparison with ALC. These results suggest the capacity of R. philippinarum to reflect external levels of exposure to those elements into tissue loads. However, an opposite spatial variation was consistently found for Hg accumulation in the digestive gland and gills in both periods, as well as for Cd in the gills in the warm season. The results reinforce the idea that trace element accumulation patterns depend not only on the external bioavailability, but also on the toxicokinetics that is trace element-specific. Despite the two contrasting patterns found for bioaccumulation in R. philippinarum (mainly Pb vs. Hg), oxidative stress parameters were able to signalise BAR as the most impacted area. In fact, the digestive gland of BAR clams exhibited higher GST activity and GSHt levels (in both sampling periods) and SOD activity (warm season), presumably to cope with the enhanced accumulation of Pb and As. Moreover, variations of gills’ CAT and SOD activities (warm period) agreed with the elevated accumulation of Pb at BAR. Overall, the characteristics of this invasive species could lead to a biased interpretation of the environmental quality status, particularly when based on trace element bioaccumulation only, reinforcing the need to adopt a multi-level/-species approach on environmental assessment studies.

Soil geochemical mapping of the central part of Prague, Czech Republic

New geochemical mapping results from the central part of Prague agglomeration are presented. The study is part of the EuroGeoSurveys Geochemistry Expert Group's ‘Urban Geochemistry’ (URGE) project. The aim of the project is to study and compare the level of potential hazardous trace element contamination in the topsoil of European cities. For such a comparison, standardised sampling, sample preparation and analytical methodologies were used in almost all URGE project surveys.Topsoil samples were collected at 194 sites from the Prague city centre. Concentrations of elements in samples taken at different distances from busy roads were evaluated, and a group of traffic related elements (Ag, Au, Ba, Cd, Cr, Cu, Mo, Nb, Pb, Pd, Pt, Sb, Sr, Sn, W and Zn) was distinguished. Element relationships, based on land use (traffic affected areas, parks, residential and other urban facilities) were studied. The traffic related element group trend is manifested most significantly in the traffic affected, residential and other urban facilities categories. Another significant trend in element concentrations from a different source is from the burning of fossil fuel (As, Be, Co, Cr, Cs, Fe, Ga, K, Mg, Ni, U, Ti and V).Concentration of elements in the topsoil of the city's parks are compared with grazing land soil in the Czech Republic, using the results from the EuroGeoSurveys project of geochemical mapping of agricultural and grazing land soil (GEMAS). Three basic groups of elements were distinguished. The first group includes elements with concentrations that are higher in Prague parks compared to grazing land soil (Ag, As, B, Ba, Be, Bi, Ca, Cd, Cu, Hg, Mo, Na, Nb, Ni, P, Pb, S, Sb, Sn, Sr, W, Zn); the second group has comparable concentrations in both soil types (Co, Cr, Fe, K, Mn, Sc, Se, Ti, U, V, Y), and the third has lower concentrations in Prague parks soil (Al, Ce, Cs, Ga, Hf, In, La, Li, Mg, Rb, Te, Th).It is concluded that there are elevated concentrations of potential harmful elements in the topsoil of the central part of the city of Prague, and their bioavailability should be studied.

Evidence for contrasting accumulation pattern of cadmium in relation to other elements in Senilia senilis and Tagelus adansoni from the Bijagós archipelago, Guinea-Bissau.

Shellfish harvesting in intertidal areas is a widespread and economically important activity in many countries across West Africa. However, in some areas, there is virtually no information concerning the levels of contaminants (and other elements related to nutritional aspects) in the harvested species. We collected sediments and several individuals of the West African bloody cockle Senilia senilis and of the razor clam Tagelus adansoni during the dry season of 2015 nearby three islands in the Bijagós archipelago, Guinea-Bissau. Aluminium, Ca, Fe, Mg, As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn were determined in sediments and whole soft tissues of the two bivalves. Sediments showed uniformly low trace element concentrations, pointing to an ecosystem with low levels of trace element contamination. T. adansoni presented higher concentrations of most elements than S. senilis, with the exception of Cd that showed up to 40 times higher values in S. senilis than in T. adansoni from the same sites. Furthermore, Cd concentrations (25±8.7mgkg-1, dw) in S. senilis are clearly above the maximum level established for human consumption. Future studies should clarify whether biological factors are the major responsible for this unusual situation.

Tracking trace elements into complex coral reef trophic networks

The integration, accumulation and transfer of trace elements across the main tropic levels of many food webs are poorly documented. This is notably the case for the complex trophic webs of coral reef ecosystems. Our results show that in the south-west lagoon of New Caledonia both abiotic (i.e. sediments) and biotic (i.e. primary producers, consumers and predators) compartments are contaminated by trace elements. However, our analyses revealed different contamination patterns from the sources of organic matter to the predators. The trophic levels involved in the sedimentary benthic food web (S-BFW, based on the sedimentary organic matter) and to a lesser extent in the reef benthic food web (R-BFW, based on algal turf) were mainly contaminated by trace elements that originate from mining activities like Ni and associated trace elements (Co, Cr, Fe, and Mn). Trace elements linked to agro-industrial (As, Hg, and Zn) and urban (Ag, Cd, Cu, Pb, Se, and V) activities were also integrated into the S-BFW, but preferentially into the R-BFW, and to a lesser extent into the detrital benthic food web (D-BFW, supplied by sea-grass plants). Most of the trace elements were biodiminished with increasing trophic levels along food webs. However, a marked biomagnification was observed for Hg, and suspected for Se and Zn. These results provide important baseline information to better interpret trace element contamination in the different organisms and trophic levels in a highly diversified coral reef lagoon.

Photochemical features and trace element substituted chlorophylls as early detection biomarkers of metal exposure in the model diatom Phaeodactylum tricornutum

Establishing marine species equipped with efficient biomarkers of trace element stress is a major requirement for the assessment of trace element contamination in marine ecosystems. This study investigates PS II overall activity and efficiency during light harvesting, electron transport chain (ETC) behaviour, OJIP-transient light curves, and pigment profiles, in the model marine diatom species Phaeodactylum tricornutum exposed to Cr, Co, Ni, Cu, Zn, Cd, Hg, Pb and to a mixture of all elements combined (Mix). OJIP-test parameters and trace element substituted chlorophylls were investigated as potential biomarkers of stress induced by trace elements. Hg-exposed cells showed a shift in balance towards PS I activity, promoted by increase in the electron transport from PQH2 to the reduction of PS I end electron acceptors. Other elements had more limited effects, mostly affecting energy dissipation and pigment levels to various degrees. Decoupling of PS II antennae connectivity was found in Co exposed cells. Chromium induced negative effects on PS I, but had no influence at the Oxygen Evolving Complexes (OECs) level. Copper caused a shift in the equilibrium between PS towards the PS I by reducing the PS II efficiency. Cadmium induced damage in OECs of the PS II donor side, but had no effect on the energy transduction pathway, maintaining energy processing efficiency. Lead had no significant effect on the energy transduction pathway, but produced changes at pigment level, leading to an increase in the chlorophyll and diadinoxanthin. In contrast, Ni had a beneficial role in P. tricornutum photochemistry, leading to increased number of available RC and oxidized quinone pool size, possibly because concentrations used were not able to induce severe cell damage. Copper, Cd and Zn led to substitution of Mg in chlorophyll a molecules, with the formation of less efficient CuChl a, CdChl a and ZnChl a. The biomarkers used evidenced the damaging effect of Co, Cu, Cr, Pb, Hg and all trace elements combined (Mix), pointing to Hg as the most harmful element. These physiological changes highlight P. tricornutum as a promising sentinel species for trace element contamination and the proposed photochemical features suitable as an efficient battery of biomarkers for trace element stress early detection in marine systems.

Assessment of potentially toxic trace elements contamination in groundwater resources of the coal mining area of the Korba Coalfield, Central India

Exploiting coal by open-cast mining often poses a threat to groundwater chemistry due to leachate of contaminants from the mine drainage water. In order to assess this, groundwater, river water and mine water samples were collected from Korba Coalfield and analysed for potentially toxic trace elements (PTEs) along with in situ parameters. Thereby, an integrated approach of pollution evaluation indices [heavy metal pollution index (HPI), heavy metal evaluation index (HEI) and contamination index (C d)] and statistical techniques are applied to the results. Paired-sample t tests reveal that the PTE concentrations of the pre-monsoon samples are higher than those of the post-monsoon samples. At a few locations, the concentration of Fe (56%), As (56%), Al (26%), Mn (19%) in pre-monsoon and Mn (46%), Ni (15%), Ba (15%), Pb (8%) in post-monsoon seasons exceeds the acceptable limit of Indian drinking standards. However, HPI values are below the critical pollution index value of 100 in both seasons in spite of an excess of these elements. The pollution indices evaluated by the multiple of the mean values approach reveal that 100, 94, 87% of the pre-monsoon and 92, 92, 85% of the post-monsoon samples belong to the “low-to-medium” category with respect to the HPI, HEI and C d indices. The thematic map depicting the spatial distribution of the contamination index (C d) testifies the role of a “dilution effect” that results in lower pollution loads in the post-monsoon samples than the pre-monsoon ones. The results of cluster analysis confirm that the quality of the water is mainly controlled by geogenic processes and anthropogenic inputs, besides dilution effects.

Contamination and ecological risk assessment of trace elements in sediments of the rivers of Sundarban mangrove forest, Bangladesh

In this study, total concentrations of 16 trace elements (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, Pb, Th and U) in sediments of the rivers of the Sundarban mangrove forest, after the catastrophic oil spill accident in the Sela river of Sundarban, were determined. The overall mean concentrations of V, Cr, Fe and Cd in surface sediments of the Sundarban are remarkably higher than available literature data of those elements. Trace element contamination assessment, using different environmental contamination indices, reveals that As, Sb, Th and U are low to moderately contaminated while Cd is moderately to severely contaminated in the sediments of this area. The multivariate statistical analyses were applied to reveal the origin and behavior of the elements during their transport in the mangrove ecosystem. High Cr, Ni, Cu and As concentrations suggest the risk of potentially adverse biological effects in the ecosystem.