Significant Accumulation Of Pb Research Articles

Native plant species growing on the abandoned Zaida lead/zinc mine site in Morocco: Phytoremediation potential for biomonitoring perspective.

This study aims to assess the level of metal contamination and the ecological risk index at the abandoned Zaida Pb/Zn mining site in eastern Morocco and identify native plant species found on the site that can be used in site rehabilitation through phytoremediation strategies. Samples from seven native and abundant plant species at the site, along with their rhizospheric soils, were collected and analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to determine the concentrations of various metal(loid)s, including As, Cu, Ni, Cd, Sb, Zn, and Pb. Indicators of soil pollution and ecological risks were also assessed, including the enrichment factor (EF), pollution index (PI), and ecological risk index (ERI). The Biological Accumulation Coefficient (BAC), Translocation Factor (TF), and Biological Concentration Factor (BCF) of plant samples were calculated. The results reveal polymetallic soil contamination, with notably higher concentrations of Pb, Cu and Zn, reaching respectively 5568 mg kg-1 DW, 152 mg kg-1 DW, and 148 mg kg-1 DW, indicating a significant potential ecological risk. The enrichment factor (EF) was also assessed for each metal(loid)s, and the results indicated that the metal contamination was of anthropogenic origin and linked to intensive mining activities in Zaida. These findings are supported by the pollution index (PI) ranging from 1.6 to 10.01, which reveals an extremely high metal(loid)s pollution level. None of the plant species exhibited a hyperaccumulation of metal(loid)s. However, Artemisia herba alba demonstrated a strong capacity to accumulate Pb in its aboveground parts, with a concentration of 468 mg kg-1 DW. Stipa tenacissima, Retama spherocarpa, and Astragalus armatus, showed a significant Pb accumulation in their roots reaching 280, 260, and 256 mg kg-1 DW.respectively. Based on BAC, TF, and BCF, Stipa tenacissima exhibited potential for Ni and Cd phytostabilization, as well as the ability for Zn phytoextraction. Additionally, Artemisia herba alba displayed the capability to phytoextract Cd and had a high propensity to translocate all the studied metal(loid)s. Astragalus armatus has the potential to be used in the phytostabilization of Zn and Ni, as well as for the phytoextraction of As and Sb. These native species from the Zaida site, although not hyperaccumulators, have the potential to contribute significantly to the phytoextraction or phytostabilization of potentially toxic elements (PTEs). Moreover, they can serve as vegetative cover to mitigate the erosion and dispersion of metal(loid)s.

Impact of Varied Lead Concentrations on Lead Accumulation in the Body, Heart and Gill Damage of Milkfish (Chanos chanos)

Milkfish (Chanos chanos) is valued in aquaculture for its affordability and nutritional richness. However, conventional farming techniques frequently result in suboptimal yields due to lead (Pb) contamination. Traditional milkfish ponds are typically situated near coastal areas, river waters, estuaries, ports, and industrial zones, rendering them susceptible to contamination, particularly from heavy metals, like Pb. This study aimed to analyze Pb accumulation in the body of milkfish juvenile, identify liver and gills damage, and examine the growth rate and survival of milkfish exposed to Pb at various concentrations. Juvenile milkfish were exposed to various concentrations of PbNO3, namely 0 mL.L-1, 0.08 mL.L-1, 0.8 mL.L-1, and 8 mL.L-1, including the non-exposed control group. The metal content of the fish bodies was measured using an AA spectrophotometer. Histological analysis of the liver and gills of the fish was performed to evaluate organ damage. The results showed significant Pb accumulation has been observed in milkfish exposed to high Pb concentrations. The control treatments showed a decrease in metal content, whereas treatments with high concentrations showed a significant increase. Exposure to Pb within 30 d can cause organ damage, such as inflammatory cells, secondary lamella fusion, and necrosis that occurs in the gills. In the liver, there is damage such as the accumulation of inflammatory cells, necrosis, and hydrofic degeneration. Pb exposure rapidly damages and disrupts milkfish's biological functions, influencing survival and growth. Pb exposure with doses 8 mL.L-1 significantly affected juvenile milkfish within approximately 60 min.

Anti-apoptotic properties of N-Acetyl cysteine and its effects on of Liver X receptor and Sirtuin 1 expression in the liver of rats exposed to Lead

BackgroundThis study aimed to evaluate the expression of Liver X receptor (Lxr), Sirtuin 1 (Sirt1), apoptotic-related genes, and the protective role of N-acetylcysteine (NAC) in the liver of rats treated with Lead (Pb). MethodsRats were randomly divided into 5 groups, including G1 (control), G2 (single dose of Pb), G3 (continuous dose of Pb), G4 (single dose of Pb + NAC), and G5 (continuous dose of Pb + NAC). Lipid profiles and liver specific enzymes were assessed. Expression of Lxr, Sirt1, Bax and Caspase-3 genes was considered using RT-PCR. ResultsExposure to Pb caused a significant accumulation of Pb in the blood and liver tissue, increase in serum AST, ALT and ALP enzymes, as well as lipid profiles. Chronic exposure to Pb caused a significant decrease in Lxr (3.15-fold; p < 0.001) and Sirt1 (2.78-fold; p = 0.009), but significant increase in expression of Bax (4.49-fold; p < 0.001) and Caspase-3 (4.10-fold; p < 0.001) genes when compared to the control. Combined therapy with Pb + NAC in rats caused a significant decrease in AST, ALT and ALP values (28.93%, 20.80% and 28.86%, respectively) in the blood as compared to rats treated with Pb alone. Co-treated with Pb + NAC significantly increased the expression of Lxr (1.72-fold; p = 0.043) and Sirt1 (2.45-fold; p = 0.008), but decreased the expression of Bax (1.96-fold; p = 0.03) and Caspase 3 (2.22-fold; p = 0.029) genes when compared to rats treated with Pb alone. ConclusionChronic exposure to Pb is strongly associated with accumulation of Pb in the blood and liver, hepatic cells apoptosis, down-expression of Lxr and Sirt1 genes and consequently liver injury and abnormal lipid profiles. NAC reversed the Pb-induced toxicity on the liver tissue.

Insight into the magnetic properties of Pb-dopped iron oxide nanoparticles during Fe(III) bio-reduction by Shewanella oneidensis MR-1

Anthropogenic activities have led to a significant accumulation of Pb in the environment, posing a threat to ecosystems. Iron oxides that display magnetic properties are ubiquitous in the environment and Pb partitioning onto these minerals is considered one of the most critical geochemical processes controlling its environmental fate. In anoxic environments, iron oxides undergo redox cycling due to biotic and abiotic routes, resulting in their transformation/dissolution and evolution of their magnetic characteristics. However, there is still a lack of knowledge on the impact of Pb on the dynamic of iron oxides bioreduction. Furthermore, there is little information available regarding the nature of biogenic minerals and their magnetic signatures.Here we incubated Pb-bearing ferrihydrites (Fh_Pb) with various Pb/(Fe + Pb) molar ratios (i.e., 0, 2 and 5%) with the iron-reducing bacterium Shewanella oneidensis MR-1, for 21 days.XRD analyses of the initial Fh_Pb displayed characteristic features of Fh and a decrease of magnetization in the presence of Pb. During the bio-reduction process, Pb doping led to a drop in the rate and extent of reduction. At the end of the incubation period, the analysis of the aqueous solutions revealed a minor proportion of Pb in solution, indicating that a significant proportion of the Pb is sorbed onto the biogenic minerals. Magnetite (95%) and siderite (5%) formed during the bioreduction of Fh, while magnetite (~80%) and goethite (~20%) precipitated in the presence of Pb as revealed by transmission Mössbauer spectroscopy. Furthermore, the size of the magnetite particles decreased from about 11 nm in absence of Pb to 6 nm with 2% of Pb-bearing, while 5% of Pb led to particles too small to be quantified with our TEM measurements. The combined effect of the decrease in particle size of magnetite, substitution of Pb and the precipitation of goethite in the Pb-dopped assay led to a significant decrease of magnetization at room temperature. Overall, this study highlights the effect of Pb on iron oxides bio-reduction and transformation processes and the sensitivity of magnetism to serve as a monitoring method.

Pb-Bearing Ferrihydrite Bioreduction and Secondary-Mineral Precipitation during Fe Redox Cycling

The significant accumulation of Pb from anthropogenic activities threatens environmental ecosystems. In the environment, iron oxides are one of the main carriers of Pb. Thus, the redox cycling of iron oxides, which is due to biotic and abiotic pathways, and which leads to their dissolution or transformation, controls the fate of Pb. However, a knowledge gap exists on the bioreduction in Pb-bearing ferrihydrites, secondary-mineral precipitation, and Pb partitioning during the bioreduction/oxidation/bioreduction cycle. In this study, Pb-bearing ferrihydrite (Fh_Pb) with various Pb/(Fe+Pb) molar ratios (i.e., 0, 2, and 5%) were incubated with the iron-reducing bacterium Shewanella oneidensis MR-1 for 7 days, oxidized for 7 days (atmospheric O2), and bioreduced a second time for 7 days. Pb doping led to a drop in the rate and the extent of the reduction. Lepidocrocite (23–56%) and goethite (44–77%) formed during the first reduction period. Magnetite (72–84%) formed during the second reduction. The extremely-low-dissolved and bioavailable Pb concentrations were measured during the redox cycles, which indicates that the Pb significantly sorbed onto the minerals that were formed. Overall, this study highlights the influence of Pb and redox cycling on the bioreduction of Pb-bearing iron oxides, as well as on the nature of the secondary minerals that are formed.

Effects of forest fires on soil lead elemental contents and isotopic ratios

This study described the behavior of Pb and its isotopes in forest soils affected by different temperature wildfires. We collected samples of burned (and unburned) soil and ash in Abiul, central Portugal, in areas affected by different temperatures. The different soil burned severities were assessed in situ.The high-temperature fires consumed all organic matter in the topsoil (down to 5 cm), while lower temperatures did not. All the soil and ash samples were analyzed for their lead (Pb) contents and Pb isotopic compositions using inductively coupled plasma mass spectrometry.The average Pb elemental concentration in the unburned topsoils was 10.7 mg kg−1, and the isotopic composition ranged from 206Pb/207Pb = 1.167 to 1.178. No significant accumulation of Pb was observed in the topsoil (and ash) affected by the high-temperature fire, but their respective ratios increased (soil 206Pb/207Pb = 1.197; ash 206Pb/207Pb = 1.180). However, there was a significant accumulation of Pb (15.3 mg kg−1) in the topsoil and especially in the ash (Pb avg. = 21.8 mg kg−1), affected by the low-temperature fire. The soil 206Pb/207Pb isotopic ratios remained stable but decreased in the ash (206Pb/207Pb = 1.174 and 1.166, respectively).According to the isotopic composition, Pb in the topsoils was of mixed origin (natural and anthropogenic). We assumed that lithogenic Pb (206Pb/207Pb > 1.19) occurred in stable mineral forms while anthropogenic Pb mainly originated from leaded gasoline (206Pb/207Pb < 1.16). Anthropogenic Pb was more easily mobilized due to the volatile nature of the emitted compounds of vehicular Pb (oxyhalogenides). Hence, during the high-temperature burning of the soil, Pb with a lower isotopic signature would be preferentially released from the soil Pb pool. Consequently, resulting soils and ash exhibited an increase in 206Pb/207Pb isotopic ratios. However, ash and soils affected by low temperatures, which did not volatilize anthropogenic Pb, retained their isotopic signatures.This work suggests that it may be possible to determine the temperature of a forest fire from the Pb isotopic signatures of the burned materials.

Distribution and Characterization of Heavy Metal and Pollution Indices in Landfill Soil for Its Rehabilitation by Phytoremediation

Population growth associated with urban development in African cities is a key environmental concern in development programs. Indeed, urban areas are strongly impacted by the production of municipal waste, the management of which remains problematic and is only stored in open dumps. This is the case in the city of Bonoua, a small town located 59 km east of Abidjan in the South Comoé region of Côte d’Ivoire. The management of municipal waste in this town is crucial because all the mineral water sources are concentrated in this town. The objective of this study is to characterize and map the distribution of trace metal elements in the largest urban landfill in the city in order to propose an efficient strategy for rehabilitation into an urban park. Soil samples were collected from the entire site (landfill and surrounding soil) and from a control site. The total content of trace metals (Pb, Cd, Cr, and Zn) in the soil was analyzed by X-ray fluorescence spectrometry (XRF). Soil pollution was evaluated through enrichment factors, geoaccumulation indices and pollution indices. The results show that the calculated geoaccumulation indices and their distribution maps indicate a pollution of the site in these elements. The values of the PI higher than the unit reveal a pollution of the site in several elements. The levels of Pb, Cd, Cr and Zn are higher than the levels in the upper continental crust and in the control soil. The spatial distribution shows a significant accumulation of Pb, Cr and Zn on the landfill while Cd is concentrated in the surrounding soils. The calculated enrichment factors suggest an anthropogenic origin of the heavy metal at the study site. These results indicate polymetallic pollution by metals that can persist in the environment and affect human health.

Assessment of air pollution at the indoor environment of a shooting range using lichens as biomonitors

ABSTRACT The aim of the study was to examine the changes in ecophysiological parameters and accumulation of heavy metals in lichens transplanted to a shooting-range environment. Thalli of the epiphytic lichen were transplanted from an unpolluted site to a shooting range. Chlorophyll a fluorescence, thiobarbituric acid reactive substances (TBARS), and damage to cell membranes in the lichen Evernia prunastri and Ramalina farinacea thalli were determined after 3 months exposure period indoors in a shooting range. The concentrations of some heavy metals including cadmium, copper, iron, manganese, nickel, lead, antimony, and zinc were measured in lichens as indicators of the levels of air pollution in the studied environment. Thalli of the lichens transplanted to the shooting-range environment showed stress symptoms where the presence of metal pollutants produced a loss of integrity of lichen cell membranes and induced oxidative stress as evidenced by increased levels of TBARS. The response of lichens transplanted to indoors of shooting range demonstrated a significant accumulation of Pb indicating potential increased metal exposure and consequent adverse health effects.

Metal Contamination and Resistance of Superficial Sediment’s Prokaryotic Flora in Extreme Environments: Case of Sfax Solar Saltern (Tunisia)

The current study focuses on the distribution of heavy metals in 17 superficial sediments of Sfax solar saltern ponds (Tunisia) and their impacts in prokaryotic flora. The results showed significant accumulation of Pb, Zn, Cu, Ni, and Cd in sediments. Maxima of Cd, Pb, and Ni concentrations were respectively more than 500, 70 and 3 times higher than those recorded in the most worldwide heavy metals contaminated solars. Complementary statistical approaches based on correlation matrix, principal component analysis (PCA), hierarchical cluster analysis (HCA) and multiple linear regression models highlight the relationship between the Bacteria and extremely halophilic Archaea and the other studied parameters (salinity, heavy metals and TOC). It was demonstrated that Bacteria and Archaea have different behaviors toward these parameters. Only, Archaea seemed to be sensitive to selected heavy metal concentrations. Their inter-pond variability rates were mainly conditioned by ‘Pb, Ni and TOC’ variability rates. The increase rate of Archaea was associated with an increase of Pb, Ni and TOC rates (and vice versa). However, Bacteria's variability rate dosent shows any dependence to all studied parameters. One could presume a good resistance of Archaea to Pb and Ni, probably reinforced by organic matter. Archaeal strains isolated from the most contaminated ponds were shown tolerant to high concentrations of Pb, Ni and Cd up to 2.5–4.5 mM. For Cu and Zn, the Archaea resistance levels were not, however, exceeded 1 mM.

Risk assessment and biophysiochemical responses of spinach to foliar application of lead oxide nanoparticles: A multivariate analysis

Despite extensive research progress in the recent past, the data regarding foliar uptake of heavy metals, associated biophysiochemical changes inside plants and possible health hazards are limited. This study determined the effect of foliar application of lead oxide nanoparticles (PbO-NPs) on lead (Pb) accumulation, physiological and biochemical changes inside spinach plants and associated health risks. A green method was used to prepare PbO-NPs using coconut water. Scanning electron microscopy (SEM) showed the preparation of smooth, unwrinkled, granular and spherical PbO-NPs. Spinach leaves were exposed via foliar application to three concentrations of PbO-NPs (0, 10 and 50 mg/plant). Foliar PbO-NPs application resulted in a significant accumulation of Pb in leaves (42.25μgg-1), with limited translocation towards root tissues (4.46μgg-1). This revealed that spinach can accumulate considerable amount of Pb via foliar uptake. Lead accumulation inside spinach caused a significant decrease in pigment contents (38%) and dry weight (67%). After foliar uptake, Pb caused several-fold increase in the activities of catalase and peroxidase. However, foliar PbO-NPs did not induce significant changes in H2O2 production, lipid peroxidation and superoxide dismutase activity. Application of PbO-NPs (50 mg/plant) showed possible health risks (non-carcinogenic) due to ingesting Pb-contaminated leaves of spinach. It is proposed that atmospheric contamination and foliar deposition of metal-PM can seriously affect vegetable growth and can provoke health issues due to ingestion of metal-enriched vegetables. Therefore, atmospheric levels of heavy metals need to be monitored on a regular basis to avoid their food chain contamination and possible human exposure.

Inhalation bioaccessibility of Cd, Cu, Pb and Zn and speciation of Pb in particulate matter fractions from areas with different pollution characteristics in Henan Province, China

Windowsill particulate matter (PM) samples were collected from an area near large lead-smelting facilities in Jiyuan (JP), the urban area of Jiyuan (JU) and the peri-urban area of Mianchi (MC) in Henan, China to investigate the concentration and inhalation bioaccessibility of Cd, Cu, Pb and Zn. The <10 μm portions of the samples were extracted with simulated lung fluid to assess the in vitro inhalation bioaccessibility. Lower concentrations of heavy metals were found in the MC samples than in the JP and the JU samples. The average concentrations of Pb, Cd and Cu in the portions of the same size are in the order of JP samples > JU samples > MC samples. For Pb, Cd and Zn, the maximum inhalation bioaccessibility fraction values are all found in the MC samples, which ranged 3.87–8.79%, while those of the JP and the JU samples are <2%. The Pb speciation analysis with X-ray absorption spectrometry indicate mineral bound Pb, PbS and Pb3(PO4)2 are the predominant Pb species in the JP samples; for the JU sample, organic bound Pb is the predominant Pb species in the 45–125 μm portion, while mineral bound Pb is the predominant Pb species in the 10–45 μm portion; for the MC samples, organic bound Pb is the predominant Pb species, followed by PbS. The results indicate that there is significant accumulation of Pb, Cd, Cu and Zn associated with PM in the area near the lead smelter and in the urban area of Jiyuan, especially Pb and Cd, however, the inhalation bioaccessibility of these metals in samples from the lead smelting impacted area is low, this may be due to the higher proportion of less soluble species of the metals in the samples from this area. However, organic matter bound Pb found in some samples has higher bioaccessibility than other Pb species.

Effects of exogenously applied salicylic acid and putrescine alone and in combination with rhizobacteria on the phytoremediation of heavy metals and chickpea growth in sandy soil

ABSTRACTThe present attempt was made to study the role of exogenously applied salicylic acid (SA) and putrescine (Put) on the phytoremediation of heavy metals and on the growth parameters of chickpea grown in sandy soil. The SA and Put were applied alone as well as in combination with plant growth promoting rhizobacteria (PGPR). The PGPRs, isolated from the rhizosphere of chickpea, were characterized on the basis of colony morphology and biochemical traits through gram staining, catalase and oxidase tests, and identified by 16S-rRNA gene sequencing as Bacillus subtilis, Bacillus thuringiensis and Bacillus megaterium. The chickpea seeds were soaked in 24 h old fresh cultures of isolates for 2–3 h prior to sowing. The growth regulators (PGRs), SA and Put (150 mg/L), were applied to the seedlings as foliar spray at three-leaf stage. The result revealed that plants treated with SA and Put alone or in combination with PGPRs, significantly enhanced the accumulation of heavy metals in plant shoot. PGPR induces Ni accumulation in sensitive variety and Pb in both the varieties, the PGR in combination augment the bioremediation effects of PGPR and both sensitive and tolerant variety showed significant accumulation of Ni, Cd, and Pb. SA was more effective in accumulating Ni and Cd whereas, significant accumulation of Pb was recorded in Put. PGPRs further augmented the PGRs induced accumulation of heavy metals and macronutrients in chickpea shoot and in rhizosphere. SA increased the proline content of tolerant variety while decreasing the lipid peroxidation and proline content of the sensitive variety but decreased the stimulating effect of PGPR in proline production. Interactive effects of PGPR and PGRs are recommended for inducing phytoremediation in chickpea plants under drought stress.

Heavy metals in aquatic organisms of different trophic levels and their potential human health risk in Bohai Bay, China.

Fourteen aquatic organism samples were collected from Bohai Bay, and concentrations of five heavy metals were measured to evaluate the pollution levels in aquatic organisms and the potential risk to human health. The concentrations of Zn and Cu were much higher than those of Cd, Cr, and Pb in all the organisms. In general, the heavy metal concentration levels were in the order phytoplankton < zooplankton < fish < shrimp < shellfish. Heavy metal concentrations in higher trophic-level aquatic organisms in Bohai Bay were compared to those in the organisms from other worldwide coastal waters. The concentration levels of most heavy metals were higher than the 75th percentile, except that Pb concentration was between the 25th and 50th percentiles. The calculated bioconcentration factors (BCF) of Cr, Cu, and Pb for phytoplankton were less than 100, indicating no accumulation in primary producers. The bioaccumulation factor (BAF) of Pb for zooplankton was the highest, indicating significant Pb accumulation in zooplankton. For higher trophic-level aquatic organisms, the order of BAF values was fish < shrimp < shellfish for most metals except for Pb. The human health risk assessment suggests that strict abatement measures of heavy metals must be taken to decrease the health risk caused by consuming aquatic products.

Kinetic study of phytotoxicity induced by foliar lead uptake for vegetables exposed to fine particles and implications for sustainable urban agriculture

At the global scale, foliar metal transfer occurs for consumed vegetables cultivated in numerous urban or industrial areas with a polluted atmosphere. However, the kinetics of metal uptake, translocation and involved phytotoxicity was never jointly studied with vegetables exposed to micronic and sub-micronic particles (PM). Different leafy vegetables (lettuces and cabbages) cultivated in RHIZOtest® devices were, therefore, exposed in a greenhouse for 5, 10 and 15days to various PbO PM doses. The kinetics of transfer and phytotoxicity was assessed in relation to lead concentration and exposure duration. A significant Pb accumulation in leaves (up to 7392mg/kg dry weight (DW) in lettuce) with translocation to roots was observed. Lead foliar exposure resulted in significant phytotoxicity, lipid composition change, a decrease of plant shoot growth (up to 68.2% in lettuce) and net photosynthesis (up to 58% in lettuce). The phytotoxicity results indicated plant adaptation to Pb and a higher sensitivity of lettuce in comparison with cabbage. Air quality needs, therefore, to be considered for the health and quality of vegetables grown in polluted areas, such as certain megacities (in China, Pakistan, Europe, etc.) and furthermore, to assess the health risks associated with their consumption.

Comparative assessment of the effects of salinomycin and monensin on the biodistribution of lead and some essential metal ions in mice, subjected to subacute lead intoxication

In this study, we present a comparative assessment of the effects of two polyether ionophorous antibiotics (monensin and salinomycin) on the concentrations of lead (Pb), cooper (Cu), zinc (Zn) and iron (Fe) in the kidneys, spleen, liver and brain of Pb-intoxicated animals. Our data demonstrated that the intoxication of ICR male mice with Pb salt resulted in a significant accumulation of Pb in all studied organs of the mice compared to the untreated control animals. The biodistribution of the toxic metal was in the order kidneys>spleen>liver>brain. The treatment of the Pb-intoxicated animals with tetraethylammonium salts of monensic and salinomycinic acids significantly decreased the concentration of the toxic metal ion compared to the toxic control. The effect varied in the interval 38% (for kidneys) to 52% (for brain) compared to the toxic control group (Pb). The tetraethylammonium salt of salinomycinic acid was more effective in reducing the Pb concentration in the brain of the Pb-treated mice compared to monensin. Pb-intoxication did not affect significantly the Zn endogenous concentration compared to the normal values. The treatment of ICR male mice with Pb-salt decreased the Cu concentration in the spleen and increased the Cu concentration in the liver compared to the untreated control animals. The detoxification of the Pb-intoxicated mice with tetraethylammonium salts of salinomycinic and monensic acids restored the Cu concentration in the spleen, but did not affect the Cu levels in the liver. The Pb-intoxication of the ICR mice resulted in a significant decrease of the Fe-concentration in the spleen and liver compared to the untreated control animals. The administration of the tetraethylammonium salts of salinomycinic and monensic acids to the Pb-treated animals restored the levels of Fe in both organs.

Tolerance of Portulaca grandiflora to individual and combined application of Ni, Pb and Zn.

In the present study, metal accumulation capacity and tolerance of Portulaca grandiflora were investigated. Plants were grown under greenhouse conditions in pots on soil amended with Ni, Pb and Zn to the final concentration of 2 mmol kg(-1) for each metal. Results show considerable accumulating capacity and translocation of Ni and Zn, as well as significant accumulation of Pb in roots. A slight decrease of biomass with Zn and of chlorophyll content with Zn and Ni were observed, as well as an increase of proline content with each of the metals. Combinations of metals revealed mutual interference affecting both the uptake and translocation of the metals and their impact on physiological parameters. Results suggest that Portulaca grandiflora, although not a hyperaccumulator, shows a good tolerance and accumulation capacity for Ni, Pb and Zn, but, for the purposes of remediation, interference of the metals must be taken into account.

Transport and Partitioning of Lead in Indian Mustard (Brassica juncea) and Wheat (Triticum aestivum)

ABSTRACTLead (Pb) contamination in soils is a serious concern because it can be taken up by crops and then transferred through the food chain, posing a potential risk to human health. Indian mustard (Brassica juncea) and wheat (Triticum aestivum) are important crop species known to accumulate heavy metals in their tissues. This study aimed at understanding the transport and accumulation of Pb in these two species and the risk associated with consumption of these foods, which would help us in mitigating accumulation of Pb in edible tissues. The plants were grown at different Pb concentrations for the entire life cycle, and the partitioning of the metal to different tissues was examined. The results showed that plant species differ widely in their ability to transport and accumulate Pb in different tissues. In B. juncea, there was significant accumulation of Pb in both siliques and seeds, whereas most of the Pb in wheat was concentrated in the vegetative tissues and less to the flag leaf and reproductive tissues. In both species, although seed Pb concentrations exceeded acceptable limits, dietary intake did not exceed acceptable limits in most treatments, indicating that more studies on Pb transport and redistribution in crop species is necessary.

Influence of compost addition on lead and arsenic bioavailability in reclaimed orchard soil assessed using Porcellio scaber bioaccumulation test

Long-term application of lead arsenate in orchards has led to a significant accumulation of Pb and As in the topsoil. Reclamation of old orchards for agricultural purposes entails the exposure of humans to Pb and As, which can be reduced by adequate remediation actions. In this study, we assessed the remediation efficiency of compost addition, commonly used as a sustainable agricultural practice, in decreasing the human exposure Pb and As by direct ingestion. The remediation was evaluated based on Pb and As bioavailability, assessed by means of a selective non-exhaustive chemical extraction (modified Morgan extraction, MME), with a physiologically based extraction test (PBET) for the assessment of Pb and As bioavailability in ingested soils and with a novel in vivo bioaccumulation test with isopods (Porcellio scaber). All the tests showed that compost addition consistently reduced Pb, but increased As potential bioavailability. The bioaccumulation test with P. scaber was sensitive to changes in Pb and As bioavailability in test soils. However, the results indicate that the bioavailability of As could be under- or overestimated using solely chemical extraction tests. Indirect assessment of trace metal bioavailability with bioaccumulation in isopods can be used as complementary source of data to the existing in vitro chemical extraction test approach for the estimation of human exposure to trace elements in polluted and remediated soil. This is the first report on the use of As accumulation in P. scaber as a tool for the assessment of As bioavailability in contaminated orchard soil.

Lead (Pb) accumulation, oxidative stress and DNA damage induced by dietary Pb in tilapia (Oreochromis niloticus)

With the increasing occurrence of dietary lead (Pb) contamination in aquaculture, a better understanding of the toxic effects of dietary Pb on aquatic animals is needed. Tilapia (Oreochromis niloticus) were exposed to dietary Pb at concentrations of 0, 100, 400 and 800 μg g−1 dry weight for 60 days, and Pb accumulation in tissues and blood, oxidative stress in posterior kidney and DNA damage in peripheral blood cells were investigated. The results showed that dietary Pb exposure resulted in significant Pb accumulation in tissues and blood, which increased with the dietary Pb concentrations. Pb accumulated in sampled tissues in the following order: posterior kidney>bone>liver>gill>spleen>testis>muscle>brain. Dietary Pb caused a significant increase in the malondialdehyde level and a significant decrease in the total antioxidant capacity content when compared with the control group (P<0.05), accompanied by concentration-dependent decreases in the glutathione content, glutathione peroxidase and superoxide dismutase activities. Pb dose-dependent DNA damage was observed in peripheral blood cells of tilapia exposed to dietary Pb. The results suggest that dietary Pb exposure can induce significant Pb accumulation in tissues and blood, followed by oxidative stress in posterior kidney and DNA damage in peripheral blood cells of tilapia.

Temporal changes of polyphenols and enzyme activities in seedlings of Kandelia obovata under lead and manganese stresses

The temporal responses of peroxidase (POD), superoxide dismutase (SOD), total polyphenols (TP), extractable condensed tannins (ECT) to different levels of lead (Pb) or manganese (Mn) stress, as well as the metal accumulation, in seedlings of Kandelia obovata were investigated. Both stress time and stress intensity had significant effects with significant accumulation of Pb and Mn in roots at Day 1. Pb and Mn showed no significant effects on root or leaf TP and ECT at Day 1. Prolonged exposure to metals caused significant drops of root TP and ECT but increased in leaves at Days 7 and 49. POD activities decreased in both roots and leaves at Day 1, while POD and SOD both increased under moderate levels of Pb and Mn at Day 7. The present study showed that antioxidative enzyme activities were more sensitive indicators to Pb or Mn stresses than phenolic compounds.