Effective metal concentrations in porewater and seawater labile metal concentrations associated with copper mine tailings disposal into the coastal waters of the Atacama region of northern Chile

Physiological responses of Humboldt current system diatoms to Fe and Cu co-limitation

Diatoms account for ∼20% of global primary production, often limited by the availability of Fe and other trace nutrients such as Cu. The present study examined the role of both metals in the physiology of two diatoms isolated from the Humboldt Currents System, the centric Chaetoceros c.f. dicipiens and the pennate Nitzschia c.f. draveillensis. Under Fe limitation, a decrease in specific growth rates and sizes of both species was observed, especially in Chaetoceros. However, regarding different photosynthetic parameters, Nitzschia was more impacted. The increase in Cu concentrations improved the physiology of both diatoms, mostly of Chaetoceros. When grown in mixed cultures and under co-limiting conditions, both species remained competive due to morphological advantages (i.e., lower cell size). These results may suggest that the increase of Cu under Fe limitation benefited C. c.f. dicipiens over N. c.f. draveillensis.

Elements in Mediterranean mussels from Istanbul and exposure assessment

In this study, concentrations of elements were determined in edible tissues of Mytilus galloprovincialis by means of inductively coupled plasma mass spectrometry (ICP-MS). The mean levels (mg kg^-1) of 0.67 for Cd, 6.9 for As, 0.79 for Pb, 2 for Ni, and 42.6 for Zn exceeded the maximum limits in the digestive glands. Also, the mean concentrations of Cd and As in muscle and of Cd and Ni in gills were above the maximum limits. The highest value was found for As in a digestive gland, with 65.4% of the Provisional Tolerable Weekly Intake. In addition, the lowest percentage belonged to Zn with 0.2% of PTWI in muscles and 0.3% of PTWI in gills of the mussels. Mercury concentrations were well below legal limits.

Assessment of heavy metal distribution in seawater of Kakinada Bay, a tropical mangrove-rich coastal environment

The main objective of the present study is to estimate the heavy metal concentrations and ecological risk index (ERI) in the seawater of Kakinada Bay. Turbidity, suspended particulate matter (SPM), pH, salinity, dissolved oxygen, along with heavy metals were recorded from twelve locations of the Bay to understand its hydrographical conditions. The distribution of environmental variables and heavy metal concentrations was noticed mostly from the south to north gradient. Significant positive correlations were detected in some pairs of metals such as Cu with Zn (R² = 0.515; p < 0.05), Pb with both Cr (R² = 0.810; p < 0.01) and Cd (R² = 0.511; p < 0.05), and Cr with Ni (R² = 0.573; p < 0.05) indicating their common origin. The ERI values (7.93-35.2) of seawater of Kakinada Bay in the present study were in the ecologically high-risk category. Industrial operations, domestic sewage, and natural processes are the major contaminant sources of Kakinada Bay leading its environment to a potential ecological concern.

Heavy metals and PAHs in mussels on the Serbian market and consumer exposure

The goal of the study was to investigate the concentration of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in 84 samples of mussels, collected from supermarkets and fish markets in Serbia. Lead, cadmium, mercury and arsenic concentrations were determined using an inductive coupled plasma mass spectrometry method. Sixteen PAHs were determined using a gas chromatography-mass spectrometry method. Heavy metals in the mussels were in the range (mg/kg) of 0.01-0.74 for lead, 0.01-0.38 for cadmium, 0.01-0.15 for mercury and 1.12-5.87 for arsenic. Metals and PAHs levels in all analysed samples were under the legal European and Serbian legislation limits. The provisional tolerable intake values were calculated on the base of the obtainable values of heavy metals. Mussels are considered to be safe for human consumption. However, one should take care of the amount and frequency of mussel consumption, primarily due to consumer's cadmium and mercury burden.

Spatial monitoring of metals and As in coastal sediments of northern Chile: An evaluation of background values for the analysis of local environmental conditions

To assess environmental conditions along the coast of northern Chile, 457 sediment samples were collected between 22° S and 28° S in order to evaluate the Cu, Zn, Pb, Ni, V, Cd, As and Al content as well as its corresponding relationship to nearby anthropogenic activities. In general, the results of most metals showed that bays without industrial activity accumulate lower concentrations of contaminant elements in the sediments and thus mostly represent natural conditions. The highest Cu, Pb and V levels were measured in coastal zones were different industrial mining activities have been developed during the last decades. Results of different indices of environmental evaluation and ecological impact suggest that, metal content of sediments from pollution-free zones characterized by similar oceanographic and geological conditions to those under study, would be the most appropriate background level for assessing the anthropogenic impact on coastal areas of northern Chile.

Geological, Mineralogical and Textural Impacts on the Distribution of Environmentally Toxic Trace Elements in Seafloor Massive Sulfide Occurrences

With mining of seafloor massive sulfides (SMS) coming closer to reality, it is vital that we have a good understanding of the geochemistry of these occurrences and the potential toxicity impact associated with mining them. In this study, SMS samples from seven hydrothermal fields from various tectonic settings were investigated by in-situ microanalysis (electron microprobe (EMPA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)) to highlight the distribution of potentially-toxic trace elements (Cu, Zn, Pb, Mn, Cd, As, Sb, Co, Ni, Bi, Ag and Hg) within the deposits, their minerals and textures. We demonstrate that a combination of mineralogy, trace element composition and texture characterisation of SMS from various geotectonic settings, when considered along with our current knowledge of oxidation rates and galvanic coupling, can be used to predict potential toxicity of deposit types and individual samples and highlight which may be of environmental concern. Although we cannot quantify toxicity, we observe that arc-related sulfide deposits have a high potential toxicity when compared with deposits from other tectonic settings based on their genetic association of a wide range of potentially toxic metals (As, Sb, Pb, Hg, Ag and Bi) that are incorporated into more reactive sulfosalts, galena and Fe-rich sphalerite. Thus, deposits such as these require special care when considered as mining targets. In contrast, the exclusive concern of ultra-mafic deposits is Cu, present in abundant, albeit less reactive chalcopyrite, but largely barren of other metals such as As, Pb, Sb, Cd and Hg. Whilst geological setting does dictate metal endowment, ultimately mineralogy is the largest control of trace element distribution and subsequent potential toxicity. Deposits containing abundant pyrrhotite (high-temperature deposits) and Fe-rich sphalerite (ubiquitous to all SMS deposits) as well as deposits with abundant colloform textures also pose a higher risk. This type of study can be combined with “bulk lethal toxicity” assessments and used throughout the stages of a mining project to help guide prospecting and legislation, focus exploitation and minimise environmental impact.

Assessment oxidative stress biomarkers and metal bioaccumulation in macroalgae from coastal areas with mining activities in Chile

The aim of this study was to evaluate the effect on seaweeds Scytosiphon lomentaria and Ulva rigida of coastal waters of sites with mining activity, using oxidative stress biomarkers and heavy metal determination both in water and in tissue. The greatest bioaccumulation factors in S. lomentaria and U. rigida were founded for iron and arsenic in Quintay. Bioaccumulation factor in S. lomentaria in descending order was Fe> Cu> Zn> Cd> Cr> As> Mo and in U. rigida, in descending order, was Fe> Cu> Cd> Zn> Cr> Mo> As. Both species had higher antioxidant activity levels in areas with high mining activities. The concentration of metals in waters such as copper and arsenic in S. lomentaria, and iron, arsenic, and cadmium in U. rigida were related with oxidative stress biomarkers measured in both species. The use of both species is proposed to monitor the bioavailability and oxidative damage in coastal areas with mining activity. This work will generate a significant knowledge about the impact of mining wastes on macroalgal community in the area of north-central Chile.

Trace metal variability in coastal waters of San Jorge Bay, Antofagasta, Chile: An environmental evaluation and statistical approach to propose local background levels

Between 2008 and 2011, twelve metals from 384 coastal waters samples from San Jorge Bay (Antofagasta, northern Chile) were collected and analyzed. The goal was to evaluate the quality of the bay's water bodies according to the current Chilean Quality Guideline and to establish background levels for these metals. The result suggests that the coastal waters of San Jorge Bay are of very good quality suitable for recreational activities involving human body contact. The natural background thresholds established for this bay were significantly lower than primary and secondary water quality guidelines. The distribution of Cu, Zn and Pb, along the bay's coastline provides evidence of the effects of industrial activity. Both situations suggest that the threshold indicated in the environmental guidelines of the Chilean legislation may be overestimated and do not represent pollution-free environments.

Oxidative stress in the mollusk Echinolittorina peruviana (Gasteropoda: Littorinidae, Lamarck, 1822) and trace metals in coastal sectors with mining activity

The aim of the study was to evaluate the effect of coastal waters of sites with mining activity in Echinolittorina peruviana, through oxidative stress biomarkers and heavy metals determination both in water and in tissue. Organisms were collected in the intertidal zone in areas with and without mining activity. Metal concentrations in the water and tissues, and also, the following biomarkers of oxidative stress: antioxidant enzyme activity, superoxide dismutase and catalase, non-enzymatic oxidative capacity (TRAP), oxidative damage to proteins (carbonyls) and TBARS, were measured The concentrations of accumulated metals had the following order Fe > Cu > Cd > Zn > Cr > Mo > As; the highest concentrations of metals in water and tissues were found in Caleta Palito and Chañaral. Results suggest that the coastal waters with mining activity and greatest concentrations of copper and iron induced the greater antioxidant response and oxidative damage to lipids in E. peruviana.

Toxic effect of metal cation binary mixtures to the seaweed Gracilaria domingensis (Gracilariales, Rhodophyta)

The macroalga Gracilaria domingensis is an important resource for the food, pharmaceutical, cosmetic, and biotechnology industries. G. domingensis is at a part of the food web foundation, providing nutrients and microelements to upper levels. As seaweed storage metals in the vacuoles, they are considered the main vectors to magnify these toxic elements. This work describes the evaluation of the toxicity of binary mixtures of available metal cations based on the growth rates of G. domingensis over a 48-h exposure. The interactive effects of each binary mixture were determined using a toxic unit (TU) concept that was the sum of the relative contribution of each toxicant and calculated using the ratio between the toxicant concentration and its endpoint. Mixtures of Cd(II)/Cu(II) and Zn(II)/Ca(II) demonstrated to be additive; Cu(II)/Zn(II), Cu(II)/Mg(II), Cu(II)/Ca(II), Zn(II)/Mg(II), and Ca(II)/Mg(II) mixtures were synergistic, and all interactions studied with Cd(II) were antagonistic. Hypotheses that explain the toxicity of binary mixtures at the molecular level are also suggested. These results represent the first effort to characterize the combined effect of available metal cations, based on the TU concept on seaweed in a total controlled medium. The results presented here are invaluable to the understanding of seaweed metal cation toxicity in the marine environment, the mechanism of toxicity action and how the tolerance of the organism.

Application of DGT to high pH environments: uptake efficiency of radionuclides of different oxidation states onto Chelex binding gel

The DGT Chelex binding phase has not been tested for binding efficiency over the extreme high pH range (i.e., 10 to 13). Here, we examined the uptake efficiency of the gel-encapsulated Chelex cation exchange resin binding phase when in direct contact with solutions of radionuclides of different oxidation states over the circumneutral to high pH range (∼7 to 13). Results show that the Chelex binding gel is suitable for Eu(3+) for circumneutral pH, for UO2(2+) up to at least pH 10.7 and for NpO2(+) up to at least pH 11.7. Application may be appropriate at higher pH values but testing of complete solution deployment units will be required. This work provides the framework to use DGT as a tool for the study of high pH radionuclide systems.

Impact of copper on the abundance and diversity of sulfate-reducing prokaryotes in two chilean marine sediments

We studied the abundance and diversity of the sulfate-reducing prokaryotes (SRPs) in two 30-cm marine chilean sediment cores, one with a long-term exposure to copper-mining residues, the other being a non-exposed reference sediment. The abundance of SRPs was quantified by qPCR of the dissimilatory sulfite reductase gene β-subunit (dsrB) and showed that SRPs are sensitive to high copper concentrations, as the mean number of SRPs all along the contaminated sediment was two orders of magnitude lower than in the reference sediment. SRP diversity was analyzed by using the dsrB-sequences-based PCR-DGGE method and constructing gene libraries for dsrB-sequences. Surprisingly, the diversity was comparable in both sediments, with dsrB sequences belonging to Desulfobacteraceae, Syntrophobacteraceae, and Desulfobulbaceae, SRP families previously described in marine sediments, and to a deep branching dsrAB lineage. The hypothesis of the presence of horizontal transfer of copper resistance genes in the microbial population of the polluted sediment is discussed.

Impact of a sacrificial anode as assessed by zinc accumulation in different organs of the oyster Crassostrea gigas: results from long- and short-term laboratory tests

Sacrificial anodes made of zinc are currently used in marine environments to mitigate marine corrosion as part of CP systems of immerged metallic structures. The aim of this work was to study zinc bioconcentration in the oyster Crassostrea gigas by performing two in vivo tests during different time periods and at different zinc concentrations. The first test was conducted during a period of 10 weeks at a concentration of 0.53 ± 0.04 mg Zn L(-1) to simulate long-term exposure, and a second test was conducted during a 168-hour period at a concentration of 10.2 ± 1.2 mg Zn L(-1) to reproduce short-term exposure. In these experiments, the zinc source was an electrochemical device that included a sacrificial anode to mimic the in situ conditions. During the first 14 days of the long-term experiment, digestive glands of C oysters exhibited bioaccumulation of zinc that varied according to the oysters' reproductive cycle. Both a bioconcentration factor (BCF) of ≤ 13,397 and a zinc accumulation percentage of +297% of zinc occurred in this organ after 10 weeks. The results obtained from the short-term test showed a lower BCF of 405 but a faster bioaccumulation of zinc (starting from the first day) in the same organ. No mortality was observed in long-term assay, but 81.8% of the oysters died at the end of the short-term assay. These results demonstrate the great capacity of C. gigas to accumulate zinc released from the anode, especially when low concentrations are released, as in the case of anode dissolution used as CP. This study confirmed the necessity to monitor this zinc-contamination source in marine environments in relation to the usual oyster consumption by humans (especially in France). No implication for human health of this zinc-contamination source was demonstrated until now, and this was not the purpose of this study; however, zinc remains one of the most abundant nutritionally essential elements in the human body that may affect the human immune system at high-level uptake.

Metal contents in coastal waters of San Jorge Bay, Antofagasta, northern Chile: a base line for establishing seawater quality guidelines

We measured the concentration of 12 metals in coastal waters of seven sites of San Jorge Bay in Antofagasta (northern Chile), in order to relate the presence of metals with the different uses of San Jorge Bay coastal border, and to evaluate the quality of the bay's bodies of water according to the proposed current Chilean Quality Guide for trace elements in seawater (CONAMA 2003). The results suggest that the coastal water of San Jorge Bay has very good quality according to the proposed regulation mentioned above. However, the distribution of metals such as Cu and Pb along the bay's coast line evidences a notorious effect of the industrial activity, which would involve different behavior patterns for some trace elements in some bodies of water, suggesting that the levels indicated in the environmental guideline of the Chilean legislation do not represent pollution-free environments.

Changes in epiphytic bacterial communities of intertidal seaweeds modulated by host, temporality, and copper enrichment

This study reports on the factors involved in regulating the composition and structure of bacterial communities epiphytic on intertidal macroalgae, exploring their temporal variability and the role of copper pollution. Culture-independent, molecular approaches were chosen for this purpose and three host species were used as models: the ephemeral Ulva spp. (Chlorophyceae) and Scytosiphon lomentaria (Phaeophyceae) and the long-living Lessonia nigrescens (Phaeophyceae). The algae were collected from two coastal areas in Northern Chile, where the main contrast was the concentration of copper in the seawater column resulting from copper-mine waste disposals. We found a clear and strong effect in the structure of the bacterial communities associated with the algal species serving as host. The structure of the bacterial communities also varied through time. The effect of copper on the structure of the epiphytic bacterial communities was significant in Ulva spp., but not on L. nigrescens. The use of 16S rRNA gene library analysis to compare bacterial communities in Ulva revealed that they were composed of five phyla and six classes, with approximately 35 bacterial species, dominated by members of Bacteroidetes (Cytophaga-Flavobacteria-Bacteroides) and α-Proteobacteria, in both non-polluted and polluted sites. Less common groups, such as the Verrucomicrobiae, were exclusively found in polluted sites. This work shows that the structure of bacterial communities epiphytic on macroalgae is hierarchically determined by algal species > temporal changes > copper levels.

An assessment of the impact of copper mine tailings disposal on meiofaunal assemblages using microcosm bioassays

Microcosms were used to assess the impact of copper mine tailings disposal on the littoral meiofaunal assemblages of the Atacama region of northern Chile. The specific purpose was to establish a cause and effect relationship between the elevated copper concentrations and altered meiofaunal assemblages observed at the study sites. Meiofaunal assemblages were exposed to a series of copper concentrations to assess general toxicity, both densities and taxa diversities decreased with increasing copper. Natural coarse sediments were mixed with a tailings substitute to assess the physical impact of the tailings dumping on meiofaunal assemblages. Meiofaunal assemblage densities increased with increasing amounts of tailings substitute, entirely due to an increase in surface utilising foraminiferans. However, taxa diversities decreased as the interstitial spaces became blocked. Finally, the microcosms were used to conduct bioassays of sediments and seawaters from the impacted sites. The sediments from the impacted sites proved to be toxic resulting in reduced meiofaunal densities and taxa diversities. Seawater samples did not prove to be significantly toxic. The use of microcosms has allowed the effects of the physical and chemical components of tailings to be assessed individually, which was not possible in the field. Additionally, it allowed a cause and effect relationship to be established between elevated concentrations of porewater copper observed in the field and the reduced densities and taxa diversities of the meiofaunal assemblages observed at the same sites.

A sediment quality triad assessment of the impact of copper mine tailings disposal on the littoral sedimentary environment in the Atacama region of northern Chile

A sediment quality triad (SQT) assessment was made of the impact of copper mine tailings disposal on littoral meiofaunal assemblages in the Atacama region of northern Chile. This situation is unusual in that the disposal is direct into the high-energy coastal system and not via a river estuary or other low-energy environment. This situation also allows for the examination of the impact of copper mine tailings in the absence of confounding effects from other pollutants. The three components of the SQT were: 1. an analysis of the bioavailable metals in both the sedimentary porewater and the adjacent seawater, 2. a microcosm bioassay of both sediments and seawaters using meiofaunal assemblages, and 3. quantitative field samples of the meiofaunal assemblages. Twelve study sites with varying degrees of impact were used, including three reference sites. The study identified that both the meiofaunal assemblage densities and taxa diversities decrease with increasing levels of bioavailable copper, that the Foraminifera and Harpacticoida are sensitive to copper, and that otoplanid Turbellaria are often characteristic of impacted sites; tailings also have both chemical and physical impacts on the environment. In some cases the physical impact of tailings is more important in excluding some organisms e.g. the interstitial polychaete, Saccocirrus sonomacus, from a site than is their chemical impact.

Biodiversity of rocky intertidal benthic communities associated with copper mine tailing discharges in northern Chile

Copper mine tailings have been discharged around the city of Chanaral, in northern Chile, for more than 60 years. This report summarizes a 17-month long monitoring study of species richness and biodiversity at five intertidal sites around the point of the tailing discharge. Total dissolved copper in sites close to the point of discharge varied between 8.72 microg/l and 34.15 microg/l, showing that there has not been a significant reduction since 1994. However, species richness has increased, suggesting a possible recovery of the system. While diversity of sessile organisms correlates negatively with dissolved copper, diversity of mobile invertebrates did not correlate with the metal concentration. To explain the observed results we discuss the role of algal turf interference on the distribution of mobile invertebrates at reference sites, a top-down effect caused by the absence of carnivores at impacted sites, and an avoidance strategy by some species to reduce their contact with contaminated seawater.

Effects of copper mine tailings disposal on littoral meiofaunal assemblages in the Atacama region of northern Chile

The effects of the disposal of copper mine tailings on the littoral meiofaunal assemblages of the Chañaral area of northern Chile were studied. Of the metals data collected, only in the case of copper was there a clear association with the tailings distribution in both the seawater and porewater samples, and it is assumed that the tailings on the beaches was the source of copper in the adjacent seawater. When compared to the reference sites, the meiofaunal assemblages at the impacted sites had significantly lower densities and taxa diversities; at the northern sites only the densities were lower. Otoplanid turbellarians were identified as characteristic of those beaches impacted by tailings. The combination of porewater copper and the amount of tailings present were identified as mostly responsible for the observed structure of the meiofaunal assemblages. It was also established that the variation in natural sediment grain size from beach to beach was not a significant factor in the observed differences in the meiofaunal assemblages. The two groups of meiofauna that proved to be most sensitive to the effects of tailings dumping were the foraminiferans and the harpacticoid copepods.

Metal speciation and environmental impact on sandy beaches due to El Salvador copper mine, Chile

Several coastal rocky shores in northern Chile have been affected by the discharges of copper mine tailings. The present study aims to analyze the chemical speciation of heavy metals in relation to the diversity of sessile species in the rocky intertidal benthic community on the northern Chilean coast, which is influenced by the presence of copper mine tailings. In particular, the chemical forms of Cd, Cu, Fe, Mn, Ni, Pb and Zn in beach sediment samples collected in the area influenced by El Salvador mine tailings were studied using a sequential chemical extraction method. In general, all the elements present a maximum concentration in the area near the actual discharge point (Caleta Palito). With regard to Cu and Mn, the concentrations range between 7.2-985 and 746-22,739 microg/g respectively, being lower than background levels only in the control site of Caleta Zenteno. Moreover, the correlation coefficients highlight that Fe, Mn and Ni correlate significantly and positively in the studied area, showing a possible common, natural origin, whilst Cu shows a negative correlation with Fe, Mn and Ni. It could be possible that Cu has an anthropogenic origin, coming from mining activity in the area. Cd, Fe, Mn, Ni, Pb and Zn are mostly associated with the residual phase, whilst Cu presents a different speciation pattern, as resulted from selective extractions. In fact, Cu is highly associated with organic and exchangeable phases in contaminated localities, whilst it is mainly bound to the residual phase in control sites. Moreover, our results, compared to local biological diversity, showed that those sites characterized by the highest metal concentrations in bioavailable phase had the lowest biodiversity.