Toxic Effects Of Heavy Metals Research Articles

Toxicity identification and evaluation for the effluent from a nonmetallic mineral mining facility in Korea using D. magna.

Industrial wastewater has attracted increasing attention in recent years because of its impact on ecosystems and human health. Whole-effluent tests are generally used to monitor toxicities of unknown chemicals and conventional pollutants from industrial effluent discharges. This study described identification evaluation (TIE) procedures to determine the acute toxicity of a nonmetallic mineral mining facility effluent that was toxic to Daphnia magna. In the characterization step (TIE phase I), toxic effects of heavy metals, organic compounds, oxidants, volatile organic compounds, suspended solids, and ammonia were screened. Results revealed that the source of toxicity was beyond these toxicants. Chemical analysis (TIE phase II) of total dissolved solid showed that the concentration of chloride ion (15,302.5 mg/L) was substantially higher than the predicted EC50 value for D. magna. Chemical analysis for heavy metal and ionic materials used ion chromatography and induced coupled plasma-optic emission spectroscopy. In the confirmation step (TIE phase III), using spiking and deletion approaches, it was demonstrated that chloride ion was the main toxicant in this effluent. Concentrations of potassium (317.5 mg/L), magnesium (970.5 mg/L), sodium (8595.3 mg/L), and sulfate (2854.3 mg/L) were not high enough to cause toxicity to D. magna. Finally, we concluded that chloride was the main toxicant in the nonmetallic mineral mining facility effluent. Based on these results, advanced treatment processes such as ion exchange and reverse osmosis technology are recommended to treat wastewater in this and similar situations. Further research is needed to provide technical support for toxin identification and evaluation of various types of wastewater treatment plant discharge.

The decline in kidney function with chromium exposure is exacerbated with co-exposure to lead and cadmium

Environmental factors contribute significantly to the pathogenesis of chronic kidney disease. However, these factors, and particularly the toxic effects of heavy metals, have not been completely evaluated. Chromium is a widespread industrial contaminant that has been linked to nephrotoxicity in animal and occupational population studies. Nevertheless, its role in population renal health and its potential interactions with other nephrotoxic metals, such as lead and cadmium, remain unknown. We assessed the association between exposure to chromium, lead, and cadmium with renal function using estimated glomerular filtration rate (eGFR) in an analysis of 360 Taiwanese adults aged 19-84 years from the National Nutrition and Health Survey in Taiwan (2005-2008). Doubling of urinary chromium or lead decreased the eGFR by -5.99 mL/min/1.73 m2 (95% confidence interval -9.70, -2.27) and -6.61 (-9.71, -3.51), respectively, after adjusting for age, sex, body mass index, hypertension, diabetes, cigarette smoking, sodium intake, education, urinary volume, and other metals. For those in the highest tertile of cadmium exposure, the eGFR decreased by -12.68 mL/min/1.73 m2 (95% confidence interval -20.44, -4.93) and -11.22 mL/min/1.73 m2 (-17.01, -5.44), as urinary chromium or lead levels doubled, respectively. Thus, there is a significant and independent association between chromium exposure and decreased renal function. Furthermore, co-exposure to chromium with lead and cadmium is potentially associated with additional decline in the glomerular filtration rate in Taiwanese adults.

Post-dredging effect assessment based on sediment chemical quality in urban rivers of Yangzhou.

Deteriorating of urban river environment in Yangzhou is gradually serious in recent years. Treatment measures including pollution source control, sewage interception, and sludge dredging have been carried out in recent years, but urban river environment is still poor. In order to ascertain the causes, post-dredging effects were assessed based on sediment chemical quality in urban rivers of Yangzhou. Results indicate that post-dredging effects are not ideal because of backward dredging technique and incomplete pollution control. Eutrophication degree is still relatively high for most of them and pollution degree of nutrients is total phosphorus (TP)>total nitrogen (TN)>organic matter (OM). Although the pollution of heavy metals is not serious, the major pollution factors Cd and Hg should still be monitored intensively in the sludge dredging for the toxic effect of heavy metals.

DIMINUTION OF HEAVY METALS IN INDUSTRIAL SOLID WASTE BY AN AMALGAMATION OF MYCO AND VERMI REMEDIATION

Due to the development of Industrialization and urbanization, a wide variety of industrial and consumer products, by products and solid waste has been produced. The solid waste generated constitutes the hazardous substance which possesses certain impacts on humans and their environment. In that heavy metal pollution from industries are the serious environmental problems. Rapid development in industries in the last few decades resulted in the strenuous task for finding to manage the waste generated. These hazardous solid wastes have been formulated into reusable end product by the process of bioremediation. Bioremediation is a natural process, which involves the use of organism to remove or neutralize the toxic pollutant from the contamination site. This review focus on the toxic effects of heavy metals on the environment and on the human health as well as the possible bioremediation method of these metals using fungus and earthworm. In order to conserve the environment and resources, the biological remediation by both fungus and earthworm for heavy metals and their efficiency have been summarised in detail.

Protective potential of Lactobacillus species in lead toxicity model in broiler chickens

To alleviate adverse effects of heavy metal toxicity, diverse range of removing methods have been suggested, that is usage of algae, agricultural by-products and microorganisms. Here, we investigated lead (Pb) biosorption efficacy by two lactic acid bacteria species (LABs) in broiler chickens. In an in vitro study, Pb was added to culture medium of LABs (Lactobacillus pentosus ITA23 and Lactobacillus acidipiscis ITA44) in the form of lead acetate. Results showed that these LABs were able to absorb more than 90% of Pb from the culture medium. In follow-up in vivo study, LABs mixture was added to diet of broiler chickens contained lead acetate (200 mg/kg). Pb exposure significantly increased lipid peroxidation and decreased antioxidant activity in liver. The changes were recovered back to normal level upon LABs supplementation. Moreover, addition of LABs eliminated the liver tissue lesion and the suppressed performance in Pb-exposed chicks. Analysis of liver and serum samples indicated 48% and 28% reduction in Pb accumulation, respectively. In conclusion, results of this study showed that L. pentosus ITA23 and L. acidipiscis ITA44 effectively biosorb and expel dietary Pb from gastrointestinal tract of chickens.

Soluble Silica as a Boon for Alleviating Toxic Effects of Heavy Metals on Vigna Radiata Grown Hydroponically in Sewage

Soluble Silica as a Boon for Alleviating Toxic Effects of Heavy Metals on Vigna Radiata Grown Hydroponically in Sewage

Assessment on cadmium and lead in soil based on a rhizosphere microbial community.

The soil ecosystem is easily polluted by heavy metals. Cadmium (Cd) and lead (Pb), as the main pollutants of heavy metals, cause much harm to the soil ecosystem. However, the impact of the two chemicals on rhizosphere microorganisms remains almost unknown. The change of catalase (CAT) activity was consistent with the microbial biomass. 16S rRNA gene sequencing was performed on soil samples to study the toxic effect of heavy metals. On performing sequence analysis at the phylum and family taxonomic levels, 32 identified phyla and 303 families were observed. The dominant phylum was Proteobacteria followed by Bacteroidetes, Acidobacteria, and Actinobacteria. The relative abundance of the dominant phyla was obviously changed under the stress of Cd and Pb, suggesting that the heavy metal input had affected the microbial community structure. At the Order and Family levels, there was different variation of richness and diversity in Cd and Pb group as compared to those in the control group. Furthermore, abundance and similarity analysis showed the differences between Cd and Pb, indicating different toxicology effect on rhizosphere microbial communities because of the unique properties. This study provided a novel insight into the composition of microbial communities of rhizosphere, which could be used to evaluate the soil environment.

Features of free oxidation in liver homogenates of rats in combined action of copper and subtoxic level of stearate potassium and sodium

Toxic effects of heavy metals on animals and humans is aggravating the presence of surfactants. The aim of our research was to identify the peculiarities of free radical oxidation and antioxidant protection in the use of drinking water with subtoxic doses of potassium and sodium stearates in combination with copper on the body of warmblooded animals, such as the liver of experimental rats. Analysis of indicators allows asserting that in experimental rats liver homogenate observed activation of free radical oxidation, the intensity of which depended on the concentration of stearates in water. More pronounced changes were in animals that consumed water with potassium stearate.The action of potassium stearate observed inhibition of antioxidant systems while under the influence of sodium stearate – its activation. Changes in performance were more pronounced in combination stearates with copper.

Overlapping toxic effect of long term thallium exposure on white mustard (Sinapis alba L.) photosynthetic activity.

BackgroundHeavy metal exposure affect plant productivity by interfering, directly and indirectly, with photosynthetic reactions. The toxic effect of heavy metals on photosynthetic reactions has been reported in wide-ranging studies, however there is paucity of data in the literature concerning thallium (Tl) toxicity. Thallium is ubiquitous natural trace element and is considered the most toxic of heavy metals; however, some plant species, such as white mustard (Sinapis alba L.) are able to accumulate thallium at very high concentrations. In this study we identified the main sites of the photosynthetic process inhibited either directly or indirectly by thallium, and elucidated possible detoxification mechanisms in S. alba.ResultsWe studied the toxicity of thallium in white mustard (S. alba) growing plants and demonstrated that tolerance of plants to thallium (the root test) decreased with the increasing Tl(I) ions concentration in culture media. The root growth of plants exposed to Tl at 100 μg L−1 for 4 weeks was similar to that in control plants, while in plants grown with Tl at 1,000 μg L−1 root growth was strongly inhibited. In leaves, toxic effect became gradually visible in response to increasing concentration of Tl (100 − 1,000 μg L−1) with discoloration spreading around main vascular bundles of the leaf blade; whereas leaf margins remained green. Subsequent structural analyses using chlorophyll fluorescence, microscopy, and pigment and protein analysis have revealed different effects of varying Tl concentrations on leaf tissue. At lower concentration partial rearrangement of the photosynthetic complexes was observed without significant changes in the chloroplast structure and the pigment and protein levels. At higher concentrations, the decrease of PSI and PSII quantum yields and massive oxidation of pigments was observed in discolored leaf areas, which contained high amount of Tl. Substantial decline of the photosystem core proteins and disorder of the photosynthetic complexes were responsible for disappearance of the chloroplast grana.ConclusionsBased on the presented results we postulate two phases of thallium toxicity on photosynthesis: the non-destructive phase at early stages of toxicant accumulation and the destructive phase that is restricted to the discolored leaf areas containing high toxicant content. There was no distinct border between the two phases of thallium toxicity in leaves and the degree of toxicity was proportional to the migration rate of the toxicant outside the vascular bundles. The three-fold (nearly linear) increase of Tl(I) concentration was observed in damaged tissue and the damage appears to be associated with the presence of the oxidized form of thallium − Tl(III).Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0883-4) contains supplementary material, which is available to authorized users.

Effect of Heavy Metals on Seed Germination of Trigonella foenum-graceum L

Effect of Heavy Metals on Seed Germination of Trigonella foenum-graceum L

Unicellular cyanobacteria Synechocystis accommodate heterotrophic bacteria with varied enzymatic and metal resistance properties.

The interactions between heterotrophic bacteria and primary producers have a profound impact on the functioning of marine ecosystem. We characterized the enzymatic and metal resistance properties of fourteen heterotrophic bacteria isolated from a unicellular cyanobacterium Synechocystis sp. that came from a heavy metal contaminated region of Cochin estuary, southwest coast of India. Based on 16S rRNA gene sequence similarities, the heterotrophic bacteria were grouped into three phyla: namely Actinobacteria, Firmicute, and Proteobacteria. Overall Proteobacteria showed a higher level of enzyme expression while Actinobacteria and Firmicutes showed higher tolerance to heavy metals. Among Proteobacteria, an isolate of Marinobacter hydrocarbonoclasticus (MMRF-584) showed highest activities of β-glucosidase (1.58 ± 0.2 μMml(-1) min(-1) ) and laminarinase (1170.17 ± 95.4 μgml(-1) min(-1) ), while other two isolates of M. hydrocarbonoclasticus, MMRF-578 and 581, showed highest phosphatase (44.71 ± 0.2 μMml(-1) min(-1) ) and aminopeptidase (33.22 ± 0 μMml(-1) min(-1) ) activities respectively. Among Firmicutes, the Virgibacillus sp. MMRF-571 showed exceptional resistance against the toxic heavy metals Cd (180 mM), Pb (150 mM), and Hg (0.5 mM). Bacillus cereus, MMRF-575, showed resistance to the highest concentrations of Co (250 mM), Cd (150 mM), Pb (180 mM), Hg (0.5 mM), Ni (280 mM), and Zn (250 mM) tested. Our results show that heterotrophic bacteria with varied enzymatic and metal resistance properties are associated with Synechocystis sp. Further studies to delineate the role of these heterotrophic bacteria in protecting primary producers from toxic effects of heavy metals and their potential application in bioremediation will be appreciated.

Alcaligenes sp.의 생장과 인 제거에 미치는 이종 중금속 혼합의 독성 효과

BACKGROUND: This study was initiated to quantitatively evaluate the effects of five heavy metals on the growth and P removal efficiencies of Alcaligenes sp., known as the Phosphorus Accumulating Organisms (PAOs). It was cultivated in the batch system with five heavy metals, such as Cd, Cu, Zn, Pb and Ni, added in single and binary mixtures, respectively. METHODS AND RESULTS: IC50 (half of inhibition concentration of bacterial growth) and EC50 (half of effective concentration of phosphorus removal Efficiencies) were used to quantitatively evaluate the effects of heavy metals on the growth and phosphorus removal Efficiencies of Alcaligenes sp. In addition, Additive Index Value (A.I.V.) method was used to evaluate the interactive effects between Alcaligenes sp. and heavy metals. As a result, as the five heavy metals were singly added to Alcaligenes sp., the greatest inhibitory effects on the growth and P removal efficiencies of each bacteria was observed in the cadmium (Cd). In the binary mixture treatments of heavy metals, the treatments of lowest IC50 and EC50 were the Cd + Cu treatment. Based on the IC50 and EC50 of the binary mixtures of heavy metals treatments, most interactive effects between the heavy metals were found to be antagonistic. CONCLUSION: Based on the results obtained from this study, it appears that they could provide the basic information about the toxic effects of the respective treatments of single and binary mixtures of heavy metals on the growth and P removal efficiencies of Alcaligenes sp. through further study about the characterization of functional proteins involved in toxic effects of heavy metals.

Cytoprotective and Antioxidant Effects of an Edible Herb, Enhydra fluctuans Lour. (Asteraceae), against Experimentally Induced Lead Acetate Intoxication.

BackgroundEnhydra fluctuans Lour. (Asteraceae), an edible aquatic herb, is traditionally employed against toxic effects of heavy metals in India. The present study was planned to discover the protective effect of edible extract of E. fluctuans (AEEF) against Pb toxicity.MethodsThe cytoprotective role of AEEF was determined on murine hepatocytes employing MTT assay and Hoechst staining. The effects on lipid peroxidation, protein carbonylation, endogenous redox systems and the transcription levels of apoptotic proteins were studied after incubating the hepatocytes with AEEF (400 μg/ml) + Pb-acetate (6.8 μM). The defensive role of AEEF (100 mg/kg) against Pb-acetate (5 mg/kg) intoxication was measured in mice by in vivo assays. Biochemical, haematological and histological parameters, intracellular Pb burden and redox status were measured.ResultsAEEF exhibited a concentration dependent cytoprotective effect against Pb-induced cytotoxicity in vitro. Pb-acetate incubation significantly (p < 0.01) altered the extents of ROS production ↑, protein carbonylation ↑, lipid peroxidation ↑, endogenous antioxidant enzymes ↓ and GSH ↓ in vitro. Besides, Pb-acetate significantly (p < 0.01) induced apoptosis in the hepatocytes apparent from the altered expressions of apoptotic proteins viz. Apaf-1 ↑, Bad ↑, Bcl-2 ↓, Cyt C ↑, cleaved caspases↑, Bid ↑ and Fas ↑. However, AEEF (400 μg/ml) could significantly (p < 0.05–0.01) attenuate the Pb-acetate mediated toxic manifestation in vitro. In in vivo assay, Pb-acetate (5 mg/kg) treated mice exhibited significantly (p < 0.01) high intracellular Pb content. A high Pb-burden within the tissues caused significant (p < 0.05–0.01) patho-physiological alterations viz. ROS production ↑, protein carbonylation↑, lipid peroxidation ↑, DNA fragmentation ↑, ATP formation ↑, mitochondrial co-enzymes Q ↓, endogenous antioxidant enzymes ↓ and GSH ↓ within the selected tissues. The haematological and serum biochemical parameters were significantly (p < 0.05–0.01) different in the Pb-acetate treated mice. Finally, histological assessment imposed significant toxic occurrence within the organs of Pb-intoxicated animals. However, concurrent administration of AEEF (100 mg/kg) could significantly (p < 0.05–0.01) reinstate the Pb-acetate mediated toxicity.ConclusionPresence of metal chelators and phyto-antioxidants within AEEF would offer overall protection through promoting Pb clearance coupled with restoring redox balance.

A kinetic analysis of oxidation of the antioxidant N-acetyl-l-cysteine (NAC) by Pt(IV) complexes

N-acetyl-l-cysteine (NAC) is an antioxidant and a supplement and has been demonstrated to have protective effects for a variety of toxic effects of heavy metals. Although previous works have shown that NAC can ameliorate the severe toxic effects of cisplatin, there is a lack of understanding of the interactions between NAC and Pt(IV)-based prodrugs. In this work, the oxidation of NAC by a cisplatin prodrug (cis-[Pt(NH3)2Cl4]), by a prototype of Pt(IV) anticancer drug ormaplatin ([Pt(dach)Cl4]) and by a model compound (trans-[PtCl2(CN)4]2–) was characterized in detail. NAC was oxidized to NAC-disulfide as identified by mass spectrometric analysis. Time-resolved spectral and stopped-flow kinetic measurements were carried out over a wide pH range, demonstrating that the oxidation followed overall second-order kinetics. The observed second-order rate constants k′ versus pH profiles were established. A reaction mechanism was deduced, involving three parallel rate-determining steps; conceivable transition states were also proposed for these steps. Rate constants of the rate-determining steps, obtained from the simulations of rate equation to the k′–pH profiles, were largely correlated with the electron density on the sulfur atom in NAC. The Pt(IV) prodrugs can execute oxidative stress in the biological systems of the human body by direct oxidation of relevant molecules, similar to HOCl/OCl− and chloroamines. Instead, the oxidative stress involved in the severe toxic effects of cisplatin is produced via a different mode. NAC could be a chemoprotecting agent also for the Pt(IV) anticancer drugs if recent drug delivery technologies are used.

Effect of Chitosan Powder Prepared from Snail Shells to Remove Lead (II) Ion and Nickel (II) Ion from Aqueous Solution and Its Adsorption Isotherm Model

The toxic effects of heavy metals have remained a major source of concern globally because of their non-biodegradable nature which makes heavy metal pollution a serious environmental problem. The extents of removal for two heavy metals were investigated on adsorbent dose, temperature, pH, contact time and initial metals ion concentration. Maximum adsorption was obtained at pH 5 for Pb²⁺ ion and pH 7 for Ni²⁺ ion with 82.1% and 68.28%, at maximum adsorption temperature 335K and 355K for both metal ions with 87% and 80% metal removal respectively. The study shows that initial metal ion concentration and adsorbent dose on metals adsorption increases for both metal ions having a maximum adsorption dose at 99.93% and 70.58% removal at 180mins contact time for both metal ions with 99.83% and 70.37%. FTIR spectrum of raw chitosan showed the following peaks; 3263cm^-1, 3109.25cm^-1, 1627cm^-1 and 2854cm^-1 denoting –NH₂/-NH asymmetric stretching,-OH stretching,-C=O stretching and –CH group showing that binding process for both metal ions onto chitosan bands at 3109.25cm^-1 and 2854cm^-1 in the spectrum. The spectra indicated –NH group was involved in the binding process due to substantial changes in absorption intensity of –NH stretching after adsorption and peak 1627cm^-1 assigned to C=O occurred before the binding process. The two peaks in the 2800-2900 cm^-1 region was observed in Pb²⁺ ion which disappear in the Ni²⁺ ion laden spectrum, the spectrum for Ni²⁺ ion has only one peak observed in this region while the Pb²⁺ ion has two and in the finger print region, 600-1000 cm^-1, the spectra of Ni²⁺ ion and Pb²⁺ exhibited two and one peaks respectively. This supported the higher sorption capacity of Pb²⁺ ion over Ni²⁺ ion. The data were evaluated using Langmuir, Frieundlich and Temkin isotherms, the data complied with Frieundlich isotherm with high R² values 0.984 and 0.971 for both metal ions while Temkin isotherm shows high R² values 0.991 and 0.981 for both Pb²⁺ and Ni²⁺ ions respectively.

엽록소형광분석을 이용한 담수산 클로렐라(Chlorella vulgaris)에 미치는 중금속의 영향 평가

Abstract The response of the freshwater microalga, Chlorella vulgaris , to heavy metal stress was examined based on chlorophyll fluorescence analysis to assess the toxic effects of heavy metals in freshwater ecosystems. When toxic effects were analyzed using regular chlorophyll fluorescence analysis, photosystem II activity(F v /F m ) decreased significantly when exposed to Cu 2+ and Hg 2+ for 12 h, and decreased in the order of Hg 2+ > Cu 2+ > Cd 2+ > Ni 2+ when exposed for 24h. The effective photochemical quantum yield(Φ′ PSII ), chlorophyll fluorescence decrease ratio(R Fd ), minimal fluorescence yield(F o ), and non-photochemical quenching(NPQ), but not photochemical quenching(qP), responded sensitively to Hg 2+ , Cu 2+ , and Cd 2+ . These results suggest that F v /F m , as well as Φ′ PSII , R Fd , F o , and NPQ could be used to assess the effects of heavy metal ions in freshwater ecosystems. However, because many types of heavy metal ions and toxic compounds co-occur under natural conditions, it is difficult to assess heavy metal toxicity in freshwater ecosystems. When

In vitro toxic effects of heavy metals on fungal growth and phosphate-solubilising abilities of isolates obtained from Phragmites australis rhizosphere

ABSTRACT In this research, we evaluated the toxic effect of metal ions on mycelial growth and phosphate-solubilising activity of soil-borne micromycetes isolated from the Phragmites australis rhizosphere using Pikovskaya-agar plates supplemented with four metal concentrations. The diameter growth rate (DGR) decreased as the metal concentration rise for all tested fungi. Trichoderma atroviride had the fastest growth rate (1.48 cm2 day−1) and was the least susceptible to Al3+, Cd2+, Cr3+, Cu2+ and Pb2+ with a median effective concentration (MEC50) of 12.19, 0.48, 4.51, 11.44 and 50.05 mM, respectively. Aspergillus japonicus was the most tolerant to Co2+, Ni2+ and Zn2+, with MEC50 values of 3.36, 1.095 and 2.34 mM, respectively. Penicillium italicum was the most tolerant to Cr6+ (MEC50 = 0.677 mM). The ability to solubilise phosphate remained, despite the decrease in the DGR, and P. italicum and Penicillium dipodomyicola had the highest Phosphate Solubilisation Indexes (PSIs) at 1.97 and 2.12, respectively. In particular, P. italicum recorded the highest PSI of all the studied isolates at 0.62 mM Cr3+ (PSI = 4.74). A. japonicus and T. atroviride were the most tolerant isolates to all tested metals, which suggests that these isolates are promising candidates for further study with regard to mycoremediation and biofertilisation of metal-polluted soils.

Performance of rose scented geranium (Pelargonium graveolens) in heavy metal polluted soil vis-à-vis phytoaccumulation of metals

ABSTRACTAn investigation was carried out to evaluate the effect of heavy metal toxicity on growth, herb, oil yield and quality and metal accumulation in rose scented geranium (Pelargonium graveolens) grown in heavy metal enriched soils. Four heavy metals (Cd, Ni, Cr, and Pb) each at two levels (10 and 20 mg kg–1 soil) were tested on geranium. Results indicated that Cr concentration in soil at 20 mg kg–1 reduced leaves, stem and root yield by 70, 83, and 45%, respectively, over control. Root growth was significantly affected in Cr stressed soil. Nickel, Cr, and Cd concentration and accumulation in plant increased with higher application of these metals. Chromium, nickel and cadmium uptake was observed to be higher in leaves than in stem and roots. Essential oil constituents were generally not significantly affected by heavy metals except Pb at 10 and 20 ppm, which significantly increased the content of citronellol and Ni at 20 ppm increased the content of geraniol. Looking in to the higher accumulation of toxic metals by geranium and the minimal impact of heavy metals on quality of essential oil, geranium can be commercially cultivated in heavy metal polluted soil for production of high value essential oil.

Bioaccumulation of heavy metals in Mbaa River and the impact on aquatic ecosystem.

The bioaccumulation and toxic effects of heavy metals have caused ecological damage to aquatic ecosystem. In this study, concentration of heavy metals including zinc, lead, cadmium, iron, and copper were determined in the sediment and water as well as in the muscle, gill, and intestine of two fish species (Pelmatochromis guentheri and Pelmatochromis pulcher) of Mbaa River in Southeastern Nigeria. Samples were collected at three different spots from the river, and the level of heavy metals specified above were determined by atomic absorption spectroscopy (AAS) after a modified wet digestion process. The results indicated that sediment had the highest concentration of the heavy metals investigated while water had the lowest concentration. Fish tissues showed appreciable bioaccumulation of these metals as evidenced by a higher concentration profile when compared with that of water. Furthermore, the concentration of these heavy metals in water and their bioconcentration factor in the fish were above the recommended limit by WHO and FEPA, indicating that Mbaa River along Inyishi may not be suitable for drinking nor the fish safe for human consumption. The study also reveals the use of fish as bioindicator of aquatic environment.

Effect of bacterial inoculation of strains of pseudomonas aeruginosa, alcaligenes feacalis and bacillus subtilis on germination, growth and heavy metal (cd, cr, and ni) uptake of brassica juncea

ABSTRACTBacterial inoculation may influence Brassica juncea growth and heavy metal (Ni, Cr, and Cd) accumulation. Three metal tolerant bacterial isolates (BCr3, BCd33, and BNi11) recovered from mine tailings, identified as Pseudomonas aeruginosa KP717554, Alcaligenes feacalis KP717561, and Bacillus subtilis KP717559 were used. The isolates exhibited multiple plant growth beneficial characteristics including the production of indole-3-acetic acid, hydrogen cyanide, ammonia, insoluble phosphate solubilization together with the potential to protect plants against fungal pathogens. Bacterial inoculation improved seeds germination of B. juncea plant in the presence of 0.1 mM Cr, Cd, and Ni, as compared to the control treatment. Compared with control treatment, soil inoculation with bacterial isolates significantly increased the amount of soluble heavy metals in soil by 51% (Cr), 50% (Cd), and 44% (Ni) respectively. Pot experiment of B. juncea grown in soil spiked with 100 mg kg−1 of NiCl2, 100 mg kg−1 of CdCl2, and 150 mg kg−1 of K2Cr2O7, revealed that inoculation with metal tolerant bacteria not only protected plants against the toxic effects of heavy metals, but also increased growth and metal accumulation of plants significantly. These findings suggest that such metal tolerant, plant growth promoting bacteria are valuable tools which could be used to develop bio-inoculants for enhancing the efficiency of phytoextraction.