Background Concentrations Of Cu Research Articles

Chilean regulations on metal-polluted soils: The need to advance from adapting foreign laws towards developing sovereign legislation

Chile as a major international Cu producer faces serious soil contamination issues in mining areas. Currently Chile does not have any specific law governing the maximum permissible concentrations of metals in soils to protect ecosystems and human health. Chile heavily relies on the use of environmental laws of 14 foreign countries; the choice of the country depends on the similarity of its environmental conditions with those in Chile. In this study, we used an online database to compare the similarity of Chilean rocks to those in foreign countries. Likewise, we performed soil sampling and determined the background concentrations of Cu, As, Pb, and Zn in soils of the Aconcagua basin, the largest river basin in the Valparaiso Region of central Chile. The results showed that geochemical patterns in Chile have the greatest resemblance to New Zealand, Mexico, and Italy. The background Cu concentration in the Aconcagua basin (134 mg kg−1) exceeded the legislated limits of New Zealand (100 mg kg−1) and Italy (120 mg kg−1), whereas the background Zn concentration (200 mg kg−1) exceeded the legislated limit of Italy (150 mg kg−1). Due to the elevated natural abundance of Cu and Zn in Chile, international laws should not be applied in Chile for the assessment of soil contamination. In addition, we assessed ecological risk using the results of our previous studies obtained by analyzing native field-contaminated soils of the Valparaiso region. In the Aconcagua basin, Cu posed high risk for plants in 11% of the samples, whereas As posed high risk for earthworms in 48% of the samples. We suggest that future studies are required to search for other organisms that can serve as biomarkers of metal toxicity because our previous studies were limited to plants and earthworms. Importantly, As posed high risk to human health in 25% of the samples in our study. There is a need for future studies to demonstrate empirically an association between soil As and children's blood As in order to establish the national threshold values of soil As to protect human health. We conclude that there is an urgent need in Chile to advance from the current approach of adapting foreign laws to developing Chilean sovereign environmental legislation.

Advanced determination of the spatial gradient of human health risk and ecological risk from exposure to As, Cu, Pb, and Zn in soils near the Ventanas Industrial Complex (Puchuncaví, Chile)

The townships of Puchuncaví and Quintero, on the coast of central Chile, have soils contaminated by atmospheric deposition of sulfur dioxide and trace elements from the nearby Ventanas Industrial Complex. The purpose of this study was to evaluate potential human health and ecological risks, by determining the spatial distribution of soil total concentrations arsenic (As), copper (Cu), lead (Pb), and zinc (Zn) in these townships. Total concentrations of these elements were determined in 245 topsoil samples, used to generate continuous distribution maps. The background concentrations of Cu, As, Pb, and Zn in the studied soils were 100, 16, 35, and 122 mg kg−1, respectively. The concentrations of Cu, As, and Pb were positively correlated with each other, suggesting that their source is the Ventanas copper smelter. On the other hand, correlations for Zn were weaker than for other trace elements, suggesting low impact of the Ventanas copper smelter on spatial distribution of Zn. Indeed, only 6% of the study area exhibited Zn concentrations above the background level. In contrast, 77, 32 and 35% of the study area presented Cu, As, and Pb concentrations, respectively, above the background level. The carcinogenic risk due to exposure to As was above the threshold value of 10−04 in the population of young children (1–5 years old) on 27% of the study area. These risk values are classified as unacceptable, which require specific intervention by the Chilean government. Based on the estimated concentrations of exchangeable Cu, 10, 15, and 75% of the study area exhibited high, medium, and low phytotoxicity risk, respectively.

Heavy metal enrichment in roadside soils in the eastern Tibetan Plateau.

The effects of human activities on heavy metal pollution in soil have been less investigated on the Tibetan Plateau. The present study was designed to assess the effects of highway traffic on Cu, Zn, Pb, and Cd enrichments in the 0-60-cm soil profile in the eastern Tibetan Plateau. Soils were sampled at four transects (with an altitude range of 2643-2911m) across the G212 highway and five transects (3163-3563m) across the G213 highway. Background concentrations of Cu, Zn, Pb, and Cd to the 60-cm soil depth (measured at each transect 400m away from highways) varied greatly among transects and between highways. However, this spatial variation in the heavy metal concentrations was not related to the altitude of the investigated areas. On each the left and right sides of G212 or G213, Cu, Zn, and Pb concentrations to the 60-cm depth, at 5, 10, 20, and 50m away from the highway, were all generally greater than the respective metal background concentrations. Cd concentrations to the 20cm on G212 or 60-cm soil depth on G213 increased prominently within a distance of 20m away from the highways, compared to background values in different depths. From the curb to 400m away from highways, concentrations of Cu, Zn, Pb, and Cd were generally higher in the upper than in the lower soil layers. This may suggest that other factors such as atmospheric deposition were also contributable to the accumulation of heavy metals in soil. The contamination factor (C f ) calculation showed that roadside soils to the 60-cm depth, within a distance of 50m from the curbs of both G212 and G213, were moderately (1 ≤ C f < 3) contaminated with Cu, Zn, and Pb. The contamination from Cd mainly occurred (1 ≤ C f < 8) in the top 20cm soil with a closer distance from the highways. Our results indicated that traffic effects in enriching heavy metals reached 60-cm depth in roadside soils on the eastern Tibetan Plateau. For assessment of heavy metal pollutions in soil in mountainous areas, it is necessary to in situ identify the background values.

Trace metals and organic carbon in sediments of the northeastern Chukchi Sea

Concentrations of Al, Fe and selected trace metals (As, Ba, Be, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V, Zn) in surface sediments from the northeastern Chukchi Sea (NECS) varied considerably as a function of sediment texture (i.e., grain size); however, essentially all metals, when normalized to Al, were present at natural, background values. Total organic carbon content ranged from 0.06–1.56% with a marine origin for at least two-thirds of the organic matter at each station based on δ13C values and C/N ratios. Recent sedimentation rates from 137Cs and 210Pb dating were 0.03–0.14cmyr−1. Corresponding vertical distributions for most metals in age-dated sediment cores showed >100-yr records of uniform metal/Al ratios, including Pb and Hg. Concentrations of As, Mn and Cd were modified in surface sediments at a few stations by early chemical diagenesis. Surveys around two exploratory oil and gas drilling sites that were occupied in 1989 showed that Ba concentrations were as high as 10,000µgg−1 within 200m of one drilling site relative to background values of ~700µgg−1. Barium enrichment was from barite, a drilling mud additive that was discharged to the seafloor. Above background concentrations of Cu, Hg, Pb and Zn also were found in sediments from 3–4 stations within 200m of the two drilling sites. At present, sediments in the NECS are essentially pristine with respect to trace metals of anthropogenic origin, excluding small areas around drilling sites. These data should be of value for detecting and tracking future chemical changes in the sediments of the NECS, particularly in light of planned oil and gas exploration and production as well as environmental changes that may be associated with climate change.

10.1007/s11179-008-1008-1

The concentrations of metals, viz., Fe, Mn, Cu, Zn, Cd, Pb, and Ni, were investigated in brown algae of the genus Sargassum collected in the coastal waters of Nha Trang Bay (South China Sea). Metal concentrations in algae growing in the zone of influence of the city of Nha Trang were higher than those in macrophytes collected to the south and north of the city. Similar levels of Cu and Fe concentrations were observed in macrophytes from the urbanized coastal areas of Nha Trang Bay and in algae from the Peter the Great Bay (Sea of Japan). This is suggestive of comparable metal inputs from the anthropogenic sources of the cities of Nha Trang and Vladivostok (Peter the Great Bay). However, the concentrations of Pb, Ni, and Cd in algae from the coastal waters of Nha Trang Bay were lower than in macrophytes from the inshore zone of Vladivostok. The high level of pollution of sea water with Zn compounds near Nha Trang was local. The metal levels in macrophytes from background areas reflect the geochemical features of the environment. Sargassum algae from Nha Trang Bay had lower concentrations of Zn, Cd, and Ni and higher concentrations of Mn than algae from Peter the Great Bay. The background concentrations of Cu, Pb, and Fe in macrophytes from both bays were virtually the same.

Fine Root Decomposition and Cycling of Cu, Ni, Pb, and Zn at Forest Sites Near Smelters in Sudbury, ON, and Rouyn-Noranda, QU, Canada

ABSTRACT This study determined rates of in situ fine root decomposition and changes in trace metals concentration during decomposition at sites in Sudbury, ON, and Rouyn-Noranda, QU, with elevated or background concentrations of Cu, Ni, Pb, and/or Zn in the soil, and correlated the depth gradients of Cu, Ni, Pb, and Zn for soils and roots at the same sites. Fine roots were extracted from soil cores within root traps several times over 12 months; biomass and metal concentrations were measured. Live roots were collected from 30-cm soil cores, separated into three depths. Elevated soil metal concentrations did not necessarily reduce fine root decomposition, and effects on decomposition were similar to those previously reported for surface foliar litter at the same sites. Decomposing roots at only the high metal sites demonstrated increased metal concentrations with time. Root tissue concentrations of Cu, Ni, and Zn, but not Pb, at lower soil depths were generally higher than expected from soil metal concentrations. This could be explained by reallocation of essential metals, although these metals were likely also more available for uptake at depth due to lower DOC concentrations. This study means that for risk assessment, separate determinations of altered decomposition for roots and leaf litter are likely not necessary for predicting ecosystem effects, a pragmatically useful conclusion given the labor intensity of the fine root studies. This study also suggests that for risk assessment of plant community exposure to metals, prediction of exposure to metals should probably consider soil layers that do not have substantially elevated metal concentrations, as their soil characteristics, or plant processes, may result in unexpected exposure.

Metal concentrations in Sargassum algae from coastal waters of Nha Trang Bay (South China Sea)

The concentrations of metals, viz., Fe, Mn, Cu, Zn, Cd, Pb, and Ni, were investigated in brown algae of the genus Sargassum collected in the coastal waters of Nha Trang Bay (South China Sea). Metal concentrations in algae growing in the zone of influence of the city of Nha Trang were higher than those in macrophytes collected to the south and north of the city. Similar levels of Cu and Fe concentrations were observed in macrophytes from the urbanized coastal areas of Nha Trang Bay and in algae from the Peter the Great Bay (Sea of Japan). This is suggestive of comparable metal inputs from the anthropogenic sources of the cities of Nha Trang and Vladivostok (Peter the Great Bay). However, the concentrations of Pb, Ni, and Cd in algae from the coastal waters of Nha Trang Bay were lower than in macrophytes from the inshore zone of Vladivostok. The high level of pollution of sea water with Zn compounds near Nha Trang was local. The metal levels in macrophytes from background areas reflect the geochemical features of the environment. Sargassum algae from Nha Trang Bay had lower concentrations of Zn, Cd, and Ni and higher concentrations of Mn than algae from Peter the Great Bay. The background concentrations of Cu, Pb, and Fe in macrophytes from both bays were virtually the same.

The effect of metal diffusion and supply limitations on conditional stability constants determined for durum wheat roots

Conditional stability constants (log K), and binding site densities (Γmax) for dissolved metals and biota are important input parameters for the Biotic Ligand Model. However, determination of these binding parameters is likely to be influenced by solution kinetics because roots have a large metal-binding capacity and can accumulate metals rapidly. The aim of this study was to determine if the rate of free metal ion diffusion to the root surface, and amount of metal in the bulk solution, is sufficient to accommodate the maximum root–metal accumulation capacity. The extent to which these kinetic limitations affect the magnitude of log K and Γmax values was also assessed. Seven day old hydroponically grown durum wheat (Triticum turgidum L. var durum, cv ‘Arcola’) were exposed to solutions with p{Cu2+}s ranging from 10.54 to 2.26 (~20 °C, pH = 6.0, ionic strength = 0.03 M). Exposure solutions were prepared with and without the metal buffer nitrilotriacetic acid (NTA) so that the total amount of metal in the exposure solution, and net flux of metal to the root, could be varied. The results demonstrate that NTA enhances Cu accumulation at exposure p{Cu2+}s between 10 and 6. Comparison of the diffusive flux to the root with the metal flux into the root, for (−NTA) and (+NTA) Cu exposures, showed that the flux of the un-buffered free metal ion to the root was not large enough to accommodate the maximum Cu binding capacity between 10 and 6 p{Cu2+} in solution. The total amount of Cu in solution may have limited uptake for exposure p{Cu2+}s of 10.01 and 9.01, but the background concentrations of Cu in the control plants prevented definitive conclusions from being made within this exposure range. Similar results were found for Mn and Ni. For Cd, which had lower background concentrations in the roots, the amount of metal in solution did not limit uptake until a p{Cd2+} of 10.01. Limiting the supply of Cu2+ to the root (i.e. low {Cu2+}s with no NTA) caused only a moderate bias in Γmax values, but suppressed the log K value by 3.44 log units. The log K values for Cd, Mn and Ni, in the absence of NTA, were more similar than expected, which suggests that the kinetics of free ion re-supply to the root surface limited metal uptake, as it did for Cu.

Effect of the nitrogen status on copper accumulation and pools of metal-binding peptides in the planktonic diatom Thalassiosira pseudonana

Effects of the algal cellular nitrogen status on the defence against copper toxicity were studied in batch cultures of the coastal diatom Thalassiosira pseudonana, grown in coastal seawater (Oosterschelde, SW Netherlands; 30‰ salinity). The media represented nutrient-poor (summer) and nutrient-rich (winter) conditions, both without and with additional nitrate, respectively. In the summer series, initial inorganic N:P ratios were 1.5 and 7.1. In the winter series, N:P ratios were 12.2 and 18.4. Cu was added at five levels (0–315 nM). We expected a low cellular nitrogen status to limit the synthesis of metal-binding peptides (phytochelatins). In N-enriched summer media phytochelatins were detectable (HPLC) only at the upper Cu level. In N-enriched winter media phytochelatins were detectable (14.6 μM SH) even without additional Cu (pCu∼14; pZn∼8), whilst in low-nitrate winter media, phytochelatins were induced at somewhat higher Cu additions; cellular Cu concentrations were similar in both cases (∼25 μM). In general, cells accumulated more Cu, Mn and Zn (summer and winter series) in N-enriched media, compared to low-nitrate media. In the low N:P media (summer) division rates were hardly affected by Cu. At N:P 12.2 and N:P 18.4, at cellular metal levels identical to those in low N:P media, T. pseudonana proved to be more Cu sensitive. In these nitrogen-rich winter conditions, phosphorus deficiency could have played a role. It was discussed that a P limitation might result in an impaired exclusion/export of copper. Phytochelatins appeared in T. pseudonana at cellular atomic C:N ratios lower than ∼15, and at ambient inorganic N:P ratios higher than the Redfield ratio (∼16). Phytochelatins indicate metal toxicity (sensitivity) rather than available metal concentrations in the coastal marine environment, and will not be detectable at natural background concentrations of Cu and Zn under a nitrogen limitation.

Baseline concentrations of copper and zinc in shoot tissues of a range of Salix species

Background concentrations of Cu and Zn in bark, leaves, twigs and wood of eight species of Salix (willow) growing on the same soil type were investigated. It was found that the concentrations of Cu and Zn varied between plant parts and between species. There was no consistent pattern of metal concentration. Copper concentrations decreased in the order twigs > leaves > wood > bark, and those of Zn in the order leaves > bark > twigs > wood. The eight species did not show a common uptake pattern for the two metals. S. × sericans and S. cinerea had high concentrations of both metals; S. purpurea had high concentrations of Zn but low concentrations of Cu, whilst S. fragilis and S. viminalis had low concentrations of both metals. Concentration factors for both elements in shoot tissues were consistent, despite the variations in associated metal concentrations. A general trend of exclusion of Cu and concentration of Zn was evident. More Cu than Zn was fixed in woody tissue.