Metal Bioaccumulation Potential Research Articles

Metal-Tolerant Bioinoculant Pseudomonas putida KNP9 Mediated Enhancement of Soybean Growth under Heavy Metal Stress Suitable for Biofuel Production at the Metal-Contaminated Site

The contamination of agricultural land with heavy metals is a global concern. Agricultural products produced in heavy metal-contaminated soil are prone to metal accumulation, and thus, are less fitted for consumption due to food safety issues. The cultivation of biofuel crops in contaminated soil would provide immediate economic benefit to the landholders while simultaneously reclaiming contaminated sites in the long run. The use of edible soybean for biodiesel production is discouraged due to the negative impact on food security. However, soybean produced in metal-contaminated soil would be suitable for biodiesel production. In this study, the tolerance and metal bioaccumulation potential of Pseudomonas putida KNP9 for Pb and Cd is investigated, and KNP9 is tested for soybean growth enhancement in cadmium and lead-amended soil. The maximum metal tolerance for the Pb and Cd in KNP9 was 1580 µM and 546 µM, respectively. KNP9 was found to be effective in removing both Pb and Cd from the solution. SEM-EDX revealed that KNP9 bioaccumulates both Pb and Cd. In pot trial studies, KNP9 was found to be effective in enhancing soybean growth with respect to untreated control under lead and cadmium stress. Thus, KNP9 inoculation protects soybean plants from the detrimental effects of cadmium and lead stress. Therefore, metal bioaccumulating bacterium P. putida KNP9 inoculation in soybean is a promising strategy for soybean growth enhancement, which could be utilized for enhanced biodiesel production from soybean at metal-contaminated sites.

Myco-Barriers as Sustainable Tool for Port Seawater Decontamination from Metals

Several inputs of metal contamination can affect port seawater, such as industries and sludges. Despite the urge of developing new techniques to face this problem, most of the studies focus on traditional methods of remediation. Bioremediation by fungi represents an innovative and sustainable tool to efficiently remove metals from seawaters. The study’s aim is to develop a new green technology using fungi (myco-barriers) to maintain a good standard for water quality in port areas. A large commercial port (Port of Genoa) and a small marina (Port of Cavo) in Italy were chosen as pilot sites. Myco-barriers were realised by inoculating sterile straw and sawdust with mycelium of macro- and microfungi. After the incubation, myco-barriers were placed in the ports and sampled after 15 and 30 days to verify metal bioaccumulation. Myco-barriers with macrofungi showed the tendency to bioaccumulate more efficiently after 15 treatment days (Zn 7.0 mg kg−1, Cu 6.5 mg kg−1, Pb 1.2 mg kg−1), while myco-barriers with microfungi showed higher bioaccumulation after 30 days (Ni 0.6 mg kg−1, Pb 0.6 mg kg−1, Cu 5 mg kg−1). Results showed that myco-barriers have metal bioaccumulation potential and can represent a significant alternative to traditional techniques of remediation (chemical–physical).

Metal bioaccumulation potential of the seaweed Kappaphycus alvarezii

Kappaphycus alvarezii is one of the two main species of seaweed commodities cultivated in Indonesia. K. alvarezii more popularly known as Eucheuma cottonii, is belongs to the red algae. This seaweed is one of the most important commercial sources of carrageenans, a family of gel-forming, viscosifying polysaccharides. Carrageenans are used as gelling, thickening, and stabilizing agents in a variety of commercial applications, especially in food products such as frozen desserts, chocolate milk, cottage cheese, whipped cream, instant products, yoghurt, jellies, pet foods, and sauces. Aside from these functions, carrageenans are used in pharmaceutical formulations, cosmetics, and industrial applications such as mining. This study aimed to analyse the metal bioaccumulation potential of the seaweed K. alvarezii. This study was conducted in three sea areas around South Sulawesi, namely the Gulf of Bone, Flores Sea and the Makassar Strait. Seaweed samples were collected from seaweed cultivation locations in four locations (Regency of Jeneponto in two locations, Takalar and Pangkep). The metal concentrations analysed were Copper (Cu), Cadmium (Cd), and Lead (Pb). The concentration in Cu, Cd, and Pb in the seaweed K. alvarezii was higher than the concentration in ambient sea water. The seaweed K. alvarezii has a potential as a bioaccumulator, but the accumulation were not consistent. The Cu, Cd, and Pb probably can be accumulated or released back. This is good in terms of food safety because heavy metals can be released during post-harvest processing and carrageenan powder processing. The results of this study indicate that K. alvarezii has the potential for bioaccumulation, but not permanent accumulation, so it is safe for human health.

A comparative analysis of heavy metal bioaccumulation and functional gene annotation towards multiple metal resistant potential by Ochrobactrum intermedium BPS-20 and Ochrobactrum ciceri BPS-26

The present study describes the heavy metal bioaccumulation potential of Ochrobactrum intermedium BPS-20 and Ochrobactrum ciceri BPS-26. A total of 27 isolates were retrieved from the soils of industrial areas and these two were selected based on their maximum metal tolerance. They can resist up to 2400 mg/L and 2000 mg/L of Lead and 850 mg/L and 1200 mg/L of Nickel respectively. The atomic absorption spectroscopic analysis showed considerably good bioaccumulation by O. intermedium BPS-20 (85.34% and 74.87%) and O. ciceri BPS-26 (71.20% and 88.48%) for Lead and Nickel respectively. The growth rate studies also demonstrated no inhibitory effects of heavy metals in the medium. Further the SEM analysis showed the presence of extracellular polymeric substances around bacterial cells. Moreover, the functional gene annotation confirmed the presence of ATPase, ABC, and HoxN/HupN/NixA families of transporters. Thus, both the isolates provide a better solution for the removal of metal pollutants.

Bioaccumulation of metals in juvenile rainbow trout (oncorhynchus mykiss) via dietary exposure to blue mussels

The potential for metals to bioaccumulate in aquatic species, such as fish, via trophic level transfer was investigated. An in vivo experiment was set up in a flow-through system in which juvenile rainbow trout were fed blue mussels collected from a Class A pristine site and an effluent-impacted river estuary, over a period of 28 days. Selected elements (As, Cd, Cr, Co, Cu, Fe, Pb, Mn, Mo, Ni, Se, Sn, V, Zn) were determined in the mussels and fish tissues (muscle and skin) collected at 0, 14 and 28 days. This study reveals the occurrence of metals in mussels sampled in the Irish marine environment and highlights the bioaccumulation potential of metals in fish tissues via trophic transfer. All 14 monitored metals were determined in the mussels collected from both sites and mussels collected from the effluent-impacted site contained three times more Co, Mo, Sn and V than the mussels collected from the Class A site. Following a 28-day dietary exposure, concentrations of As and Se (fish muscle), and Pb, Se and Zn (fish skin), were significantly greater in fish feeding on contaminated mussels compared to those with a regular fish feed diet. The significance of metal detection and bioaccumulation in the mussel and fish tissues, highlights the potential for metal exposure to humans through the food chain. As fish are recommended as a healthy and nutritious food source, it is important to fully understand metal bioaccumulation in commercially important aquatic species and ensure the safety of human consumers.

Antioxidative Responses of Microalgae to Heavy Metals

Abstract Microalgae are unicellular free living entities and therefore their responses to excess of heavy metals must be faster and more efficient than those in vascular plants protected by various types of tissues. Up to date, numerous studies reported metal bioaccumulation potential of algae but metabolic responses have relatively rarely been monitored. Here I provide basic overview of quantitative changes of ascorbic acid (AA), reduced glutathione (GSH), phytochelatins (PCs) and selected related enzymes (ascorbate peroxidase and glutathione reductase) in some common microalgae exposed to various metals (cadmium mainly). Despite various culture and exposure conditions, some common signs of metal toxicity (including e.g. enhancement of phytochelatin biosynthesis) are clearly identifiable in algae. Other metal chelators such as organic acids are also briefly mentioned. Comparison with macroalgae, mosses and vascular plants is discussed in terms of basal values and evolutionary similarities.

Histopathological effects of the herbicide atrazine on gills of the Brazilian endemic bivalve Diplodon expansus

ABSTRACTDue to their benthic filter-feeding habits and high bioaccumulation potential of metals and organic compounds, bivalve molluscs have been widely used in studies in the field and laboratory to assess the toxic effects of several compounds discharged in rivers, oceans and estuaries. However, most ecotoxicological studies use invasive exotic species, while the response of native species is poorly known. The Brazilian endemic species Diplodon expansus occurs in rivers near areas of intense agricultural activity, and atrazine is currently one of the main residues of pesticides found in water bodies of the Brazilian territory. This study was aimed at examining the toxicity of different atrazine concentrations to a Brazilian native mollusc by analysing the histology, histochemistry and ultrastructure of its gill filaments. The cells that comprise the frontal and intermediary regions of gill filaments were the most affected by the herbicide and responses associated with damage and protection were observed. The response of tissues and cells were dose-dependent. Higher concentrations of herbicide caused more severe alterations in large areas of the gills. The persistence of the alterations observed might result in severe functional problems in the gills of these animals, negatively affecting their performance and health.

Quantification of the role of organisms in the geochemical migration of trace metals in the ocean

The contribution of biological processes to the geochemical migration of trace metals (Fe, Mn, Ni, Co, Cu, Zn, Cd, Pb, and As) was quantified for three geochemically distinctive areas of the ocean: continent—ocean boundary (marginal filter), euphotic zone of the open ocean, and deep-sea hydrothermal vent fields of the Mid-Atlantic Ridge. A new term “trace metal bioaccumulation potential” is introduced to compare the bioaccumulation intensity of different organisms. The bioaccumulation potential accounts for the ability of living matter to produce biomass. The bioaccumulation potential is calculated on the basis of mean whole-body concentrations of trace metals in the dominant communities and the biomass per unit area of the biotope. The results showed that the highest bioaccumulation potential is recorded in chemosynthesis-based benthic biota from deep-sea hydrothermal vent fields. At the same time, Fe, an essential heavy metal controlling a number of biochemical processes in organisms, was found to have the highest bioaccumulation potential, while Hg, a toxic heavy metal, has the lowest bioaccumulation potential. The bioaccumulation potential in the marginal filter and euphotic zone decreases in the following order Fe > Zn > Mn > Cu, whereas in deep-sea hydrothermal fields, the bioaccumulation potential of Mn is considerably lower, close to those of Pb, Co, Cr, and Cd. The order of trace metals bioaccumulation potential in biota is broadly similar in all three geochemically different regions. This implies that the bioaccumulation function of the biota is characterized by a geochemical resemblance in different parts of the ocean.

The potential of selected macroalgal species for treatment of AMD at different pH ranges in temperate regions

The metal bioaccumulation potential of selected macroalgae species at different pH ranges was study for usage as part of a possible secondary passive acid mine drainage (AMD) treatment technology in algae ponds. Two separate studies were conducted to determine the suitability of macroalgae for passive treatment when metabolic processes in macrophytes and microorganisms in constructed wetlands decrease during winter months. In the field study, the bioconcentration of metals (mg/kg dry weight) measured in the benthic macroalgae mats was in the following order: site 1. Oedogonium crassum Al > Fe > Mn > Zn; site 2. Klebsormidium klebsii, Al > Fe > Mn > Zn; site 3. Microspora tumidula, Fe > Al > Mn > Zn and site 4. M. tumidula, Fe > Mn > Al > Zn. In the laboratory study, cultured macroalgae K. klebsii, O. crassum and M. tumidula isolated from the field sampling sites were exposed to three different pH values (3, 5 and 7), while bioaccumulation of the metals, Al, Fe, Mn and Zn and glutathione S-transferase (GST) activity were measured in the different selected algae species at a constant water temperature of 14 °C. Bioaccumulation of Al was the highest for O. crassum followed by K. klebsii and M. tumidula (p < 0.0001). From the study it was evident that the highest metal bioaccumulation occurred in the macroalgae O. crassum at all three tested pH values under constant low water temperature.

Assessing metal bioaccumulation from estuarine sediments: comparative experimental results for the polychaete Arenicola marina

The purpose of this paper is to compare three approaches for providing information on the bioaccumulation potential of metals from contaminated sediments to the deposit-feeding polychaete Arenicola marina. We present metal (Ag, As, Cd, Cu, Pb and Zn) bioaccumulation results from field-collected sediments quantified through direct measurements of bioaccumulated concentrations in A. marina over a period of 30 days under controlled laboratory exposures and compare these results with bioaccumulated metal concentrations in field-collected organisms from the same sites of collection of the sediments used in the laboratory exposures. For the metals for which model parameters are available (Ag, As, Cd and Zn), we also compare these results with biodynamic model predictions. We considered three UK estuaries characterised by a well-reported history of trace metal contamination and bioavailability in addition to the (control) site of collection of the worms. The results from laboratory-exposed organisms showed that the standard 28-day exposure duration may be adequate to identify the potential for metal bioaccumulation in this polychaete at the sites considered here. However, the time course of bioaccumulated concentrations and the comparison with measured concentrations in field-collected worms show that a steady state has not been reached, confirming the need for extended exposure periods. The worms showed symptoms of stress in feeding and growth during the initial 10 days of exposure and subsequent partial recovery during the following 20 days, suggesting that stress was not always caused by sediment contamination but that it was likely associated with handling and acclimation. At this last stage of the exposure, a generalised biodynamic model was used to provide estimates of bioaccumulated metal concentrations and net accumulation rates in worms. The results of this study highlight the number of factors that should be considered for the interpretation of bioaccumulated metal concentrations in A. marina under laboratory exposures for contaminated sediment assessment, factors that appear to be common to most deposit-feeding polychaetes. A general biodynamic model proved to be a cost-effective method for an initial estimation of the extent and pattern of metal bioaccumulation under specified exposure conditions.

Dominance of Algae in Ganga Water Polluted Through Fly-Ash Leaching: Metal Bioaccumulation Potential of Selected Algal Species

Dominance of Algae in Ganga Water Polluted Through Fly-Ash Leaching: Metal Bioaccumulation Potential of Selected Algal Species

Effects of salinity, temperature and food type on the uptake and elimination rates of cd, cr, and zn in the asiatic clamcorbicula fluminea

Laboratory radiotracer experiments were conducted to determine assimilation efficiencies (AE) from ingested algal food and oxic sediment particles, uptake rates from the dissolved phase, and the efflux rates of Cd, Cr and Zn in the Asiatic clamCorbicula fluminea. Among three elements, AE from both algal and sediment food was greatest for Cd, followed by Zn and Cr. The AEs of tested elements from algal food(Phaeodactylum tricornutum) were consistently higher than those from sediments at a given salinity and temperature. The influence of salinity (0, 4 and 8 psu) and temperature (5, 13 and 21¼) on the metal AEs was not evident for most tested elements, except Cd AEs from sediment. The rate constant of metal uptake from the dissolved phase (ku was greatest for Cd, followed by Zn and Cr in freshwater media. However, in saline water, theku of Zn were greater than those of Cd. The influx rate of all tested metals increased with temperature. The efflux rate constant was greatest for Cr (0.02 d-1), followed by Zn (0.010~0.017 d-1) and Cd (0.006 d-1). The efflux rate constant for Zn in clam tissues depurated in 0 psu (0.017 d-1) was faster than that in 8 psu (0.010 d-1). Overall results showed that the variation of salinity and temperature in estuarine systems can considerably influence the metal bioaccumulation potential in the estuarine clamC. fluminea. The relatively high Cd accumulation capacity ofC. fluminea characterized by the high AE, high dissolved influx rate and low efflux rate, suggested that this clam species can be used as an efficient biomonitor for the Cd contamination in freshwater and estuarine environments.

Metal Removal Potential by Three Aquatic Plants in an Acid Mine Drainage Wetland

This study was conducted to gauge the metal bioaccumulation potential of hydrophytic vegetation in a wetland constructed in McCreary County, Kentucky, USA, to treat a cole mine effluent averaging 787 mg/L Fe, 12.6 mg/L Al, 10.9 mg/L Mn, and 2,244 mg/L acidity. Three dominant plant species, cattail (Typha latifolia), bulrush (Scirpus validus), and tickseed sunflower (Bidens aristosa), were sampled and analyzed for Al, Fe, and Mn, so that relationships could be drawn about their capability to bioaccumulate metals from the wastewater. Results showed that Al and Fe were retained-mainly in the roots of the plants, while Mn was more mobile throughout the plant. Iron bioaccumulation was similar for all three plant species at high metal concentration gradients, but somewhat reduced in T. latifolia at low concentration gradients. Scirpus validus appeared to be the most Al-tolerant species, considering its greater Al bioaccumulation potential at high metal concentration gradients. In spite of the high metal load and acidity of the water, there were no visible toxicity effects, but B. aristosa and to a lesser extent S. validus seemed to prefer low-mental concentration environments. All plants bioaccumulated some Al, Fe, and Mn, but their concentrations were fairly miniscule compared to overall metal retention by the wetland substrate. This suggests that the main plant contribution is through substrate stabilization, microbial attachment, and rhizosphere oxidation rather than phytoremediation. Therefore, plant selection criteria for high metal load wetlands should mainly be based on metal tolerance and rhizosphere surface area rather than metal bioaccumulation potential.

The Challenges of Hazard Identification and Classification of Insoluble Metals and Metal Substances for the Aquatic Environment

The OECD is currently harmonizing procedures for aquatic hazard identification of substances. Such a system already exists in Europe where it is recognized that special consideration must be given to sparingly soluble metals and metal compounds (SSMMCs) because standard hazard testing procedures designed for organic chemicals do not accommodate the characteristics of SSMMCs. Current aquatic hazard identification procedures are based on persistence, bioaccumulation, and toxicity (PBT) measurements. Persistence measurements typically used for organic substances (biodegradation) do not apply to metals. Alternative measurements such as complexation and precipitation are more appropriate. Metal bioaccumulation is important in terms of nutritional sufficiency and potential food chain transfer and toxicity. Unlike organic substances, metal bioaccumulation potential cannot be estimated using log octanol-water partition coefficients. Further, bioaccumulation and bioconcentration factors are often inversely related to exposure concentration for most metals and organisms, and hence are not reliable predictors of chronic toxicity or food chain accumulation. Metal toxicity is due predominately to the free metal ion in solution. In order to assess the toxicity of SSMMCs, the rate and extent of transformation to a soluble form must be measured.