Bioaccumulation of heavy metals in living organisms

The present study investigates and models the effect of laser ablated silver nanoparticles (AgNPs) on the development of the aquatic macrophyte Lemna minor. Toxic effects of five different AgNP concentrations (8, 16, 32, 96 and 128 μg L(-1)) on L. minor were recorded over seven days under simulated natural conditions. Biosorption of AgNPs by L. minor was modeled using four sorption isotherms, and the sorption behavior was found to agree most closely with the Langmuir-Freundlich model (R(2)=0.997). While toxic effects of AgNPs could be observed in all models and concentrations, the greatest increase in toxicity was in the 8-32 μg L(-1) range. Dry weight- and frond number-based inhibition experiments suggest that growth inhibition does not necessarily scale with AgNP concentration, and that slight fluctuations in inhibition rates exist over certain concentration ranges. Very close fits (R(2)=0.999) were obtained for all removal models, suggesting that the fluctuations are not caused b...

The main objective of this study was to identify and isolate arsenic resistant bacteria that can be used for removing arsenic from the contaminated environment. Here we report a soil borne bacterium, B1-CDA that can serve this purpose. B1-CDA was isolated from the soil of a cultivated land in Chuadanga district located in the southwest region of Bangladesh. The morphological, biochemical and 16S rRNA analysis suggested that the isolate belongs to Lysinibacillus sphaericus. The minimum inhibitory concentration (MIC) value of the isolate is 500 mM (As) as arsenate. TOF-SIMS and ICP-MS analysis confirmed intracellular accumulation and removal of arsenics. Arsenic accumulation in cells amounted to 5.0 mg g-1 of the cells dry biomass and thus reduced the arsenic concentration in the contaminated liquid medium by as much as 50%. These results indicate that B1-CDA has the potential for remediation of arsenic from the contaminated water. We believe the benefits of implementing this bacterium to efficiently reduce arsenic exposure will not only help to remove one aspect of human arsenic poisoning but will also benefit livestock and native animal species. Therefore, the outcome of this research will be highly significant for people in the affected area and also for human populations in other countries that have credible health concerns as a consequence of arsenic-contaminated water.

Seedlings of Sinapis alba L. species (white/yellow mustard) were grown in nutrient solution containing different concentrations 50, 100, 250 and 500 mg/kg Cu for 10 days. Seedlings were measured and weighed at the end of the experiment. Leaf pigment concentration (chlorophylls a and b and carotenoids), tissular copper concentration and Biological Accumulation Coefficients (BAC) were determined. Copper content in Sinapis alba L. tissues reached 74.54 171.20 mg/kg dry mass, with highest values at high ambient concentration. BAC reached 1.49 at 50 mg/kg and was subunitary at higher concentrations, between 0.75 0.34. Shoot length and biomass emphasize a significant decrease at high ambient copper levels, while photosynthetic pigment concentrations did not decrease. These results indicate a limited tolerance of white mustard to high copper concentrations and a limited bioaccumulation potential of this metal.

In this study, cadmium (Cd), nickel (Ni), and lead (Pb) contents were analyzed in sixteen banana composite samples from different commercial establishments from eleven Ecuadorian production provinces using graphite furnace atomic absorption spectrophotometry. The concentrations (fresh weight) in the samples collected (9.3–47.3 μg·kg−1 for Cd, 16.1–105.6 μg·kg−1 for Ni, and 36.9–538.0 μg·kg−1 for Pb) were used to calculate the estimated daily intake (EDI), target hazard quotient (THQ), and target carcinogenic risk (CR) associated with dietary exposure to these potentially toxic metals. Cd and Ni results showed that every sample had EDIs lower than the oral reference dose and THQ values lower than 1, demonstrating that there was no non-carcinogenic risk related to the exposure to Cd and Ni. In the case of Pb, two EDIs results were higher than the reference dose, also their corresponding THQ values were higher than 1. The lead CR in all samples was less than 1 × 10−4, the upper limit u...

Ecotourism originated in the 1980s, at the dawn of sustainable development, as a means of directing tourism revenues into conservation and development. At both local and national levels ecotourism is seen as a potential vehicle to provide environmental, socio-economic and cultural benefits. Ecotourism is now the fastest growing tourism sector, generating more than $ 28 billion in annual revenue for developing countries. Ecotourism addresses both social and environmental goals, and it can benefit biodiversity conservation in many ways which were reviewed in this paper.

The study, which measured the concentrations of Zn, Cu, Pb and Cd, in muscle tissue of 5 commercially important crustacean species (Penaeus monodon, Penaeus indicus, Penaeus semisulcatus, Penaeus marguensis and Metapenaeus brevicornis) collected from the UNESCO declared world heritage site Indian Sundarbans. The Indian Sundarbans at the apex of Bay of Bengal is recognized as one of the most diversified and productive ecosystems in the world located at the confluence of Hooghli-Matla estuarine ...

The natural Cu, Cr, Zn and Mn phytoaccumulation potential was screened for three widespread species, in the Constanta coastal area, Romania: Brassica rapa, Crambe maritima and Lepidium draba. Samples of aboveground organs and soil were taken for each species and analyzed for heavy metal concentration values. The Biological Accumulation Coefficients (BAC) was determined, in order to evaluate the phytoaccumulation potential. None of the three species surpassed the widely-accepted minimal thresholds for Cu, Cr, Zn and Mn hyperaccumulators. The highest average values, such as 42.7 ppm, for Cu (L. draba), 40 ppm, for Cr (Brassica rapa) 147.9 ppm, for Zn (C. maritima) and 26.9 ppm, for Mn (C. maritima) were registered. However, C. maritima and L. draba had BAC above 1 for Cu and Zn (L. draba, also for Cr), while B. rapa had a BAC of 2.75 for Cu and 2.73 for Cr showing a significant potential for metal accumulation. Heavy metals are not only important for Global industry, but they cause significant environmental and agricultural concern. Polluted soils make crops less productive or, even, unsafe for human consumption. These are the reasons why, during the past decades, much attention was given to phytoaccumulation and potential heavy metal hyperaccumulators. Heavy metals are toxic to plants. If excessive concentrations are present, metals accumulate in root cells, causing serious damage. However, many species have strategies to limit toxicity. One of them is exclusion of metal ions, meaning either a limitation of root uptake or a sequestration in root tissue, to prevent metal translocation to sensitive photosynthetic tissues. The other strategy is accumulation, with its extreme version, hyperaccumulation: metals are translocated and distributed across both underground and aboveground organs [1, 2]. Only around 0.2% of known plant species can be defined as hyperaccumulators (with metal concentrations 100-1,000 times higher than the average). However, their potential applications make them of great interest. Phytoextraction (metal extraction using plants) may have two main purposes: phytoremediation-removing heavy metals from polluted soils, through cropping and harvesting accumulator plants-and phytomining-generating revenue from exploiting otherwise sub-economic metal deposits [1, 2]. This is why finding potential hyperaccumulators in the native vegetation of each region is of great importance. The Brassicaceae family is very important from this point of view, many of the species with remarkable metal accumulating abilities belonging to this group: Thalaspi sp., Alyssum sp., Arabidopsis halleri, Streptanthus polygaloides, Brassica juncaea etc. [1]. The purpose of the current research was to determine the metals accumulation abilities of three Brassicaceae species, commonly growing in Romanian Black Sea coastal areas, as a part of a wider screening research for potential metal hyperaccumulators in this region. Brassica rapa L. subsp. oleifera (field mustard) is a well-known oleaginous plant (a source of canola oil) that is relatively often found growing spontaneously on the slopes bordering sandy beaches on the Romanian seaside. Crambe maritima L. (sea kale) is a halophile plant which grows on sandy beaches throughout temperate areas of Europe. Perennial, deciduous, it has a fleshy, massive, root system, thick stems and large glaucous leaves with crisped edges. White flowers are grouped in large inflorescences. The globulous seeds are easily dispersed by wind or water and vegetative reproduction can occur throught stem or root fragments. It is edible, cultivated as a garden vegetable in certain parts of the world [3]. Lepidium draba L. (syn. Cardaria draba; whitetop, or hoary cress), is a medium-sized perennial herb (10-80 cm tall), with an extensive horizontal root system, allowing vegetative reproduction. It has simple, toothed and alternating leaves. Small white flowers are grouped in compound corymb clusters, while silicles are small and heart-or egg-shaped. It is used for medicinal purposes in some regions, seed and leaf infusions having expectorant and purgative properties [4]. Experimental part Vegetal raw material (aboveground organs: shoots and leaves) was collected in June 2014 from the Trei Papuci and Modern beaches and surrounding areas, in Constanta county, Romania. The three plant species samples were taken from three different locations along this area. Also, from the same locations, a soil sample for each plant, was taken. Small pieces of vegetal organs and soil samples, were mineralized according to Shanker et al. and Burada et al. [5, 6]. Samples were oven dried at 80 o C for 3 days. 0.25 g of each sample were taken for analysis, digested overnight in 5 mL of HNO 3 67% concentration and boiled one hour at 150 o C. After cooling, 2 mL H 2 O 2 p.a. were added, followed by boiling at 150 o C for 2 h. Resulting solutions were diluted at 50 mL and NH 4 Cl 2% respective CaCl 2 0.5% were added, in order to reduce interference. Digested samples were analyzed using a HR-CS Atomic Absorption Spectrometer ContrAA700, Analytik Jena AG, Germany, with acetylene flame (acetylene-nitrous oxide flame, for Cr) at specific wavelengths for copper (324 nm),

This study documents changes in contamination over time at seasonal, interannual, and decadal time scales for sport fish collected in San Francisco Bay. Samples from seven fish species were prepared according to common consumption practices (muscle fillets either with or without skin) and analyzed for trace metals (mercury and selenium) and trace organochlorine contaminants (PCBs, DDTs, chlordanes, and dieldrin). In 2000, sport fish samples exceeded human health screening values for mercury, PCBs, DDTs, selenium, and dieldrin but did not exceed screening values for chlordanes. On a seasonal time scale, white croaker (Genyonemus lineatus) exhibited significantly lower PCB and lipid concentrations in spring, and a general increase in concentrations in other seasons. When monitoring data were compared among 1994, 1997, and 2000, analysis of variance indicated that concentrations of mercury, PCBs, DDTs, and chlordanes varied significantly among years for several fish species. Interannual variation in DDTs often correlated to changes in sampled fish size or lipid content among years. Interannual variation in mercury and PCBs was evident in striped bass (Morone saxatilis) but absent in shiner surfperch (Cymatogaster aggregata), leopard shark (Triakis semifasciata), and white croaker. The higher interannual variability of striped bass contaminant concentrations may result from migratory behavior and wide home ranges. Chlordanes significantly declined between 1994 and 2000 in white croaker and striped bass. Of the historical data analyzed (1986–2000), only DDT concentrations in white sturgeon (Acipenser transmontanus) showed evidence of a significant decline. Neither PCBs nor selenium showed evidence of a trend in white sturgeon. Between 1970 and 2000, mercury concentrations in striped bass showed no evidence of a trend. The absence of recent trends in mercury may result from the presence of widespread and historic sources, with use reductions occurring in the early 20th century. In contrast to mercury, apparent recent declines in fish tissue DDT and chlordane concentrations may result from use curtailment in the 1970s and 1980s.

A small and genetically isolated bottlenose dolphin (Tursiops truncatus) population resides year-round in the Bocas del Toro Archipelago-Panama (BDT). Photo-identification and genetic data showed that this dolphin population is highly phylopatric and is formed exclusively by individuals of the “inshore form”. This study aimed to investigate the trophic ecology and mercury concentrations of bottlenose dolphins in BDT to assess their coastal habits. We collected muscle samples (n = 175) of 11 potential fish prey species, and skin samples from free-ranging dolphins in BDT (n = 37) and La Guajira-Colombia (n = 7) to compare isotopic niche width. Results showed that BDT dolphins have a coastal feeding habit, belong to the “inshore form” (δ13C = −13.05 ± 1.89‰), and have low mercury concentrations (mean = 1637 ± 1387 ng g−1dw). However, this element is biomagnified in the BDT food chain, showing a marginal dolphins health risk (RQ = 1.00). We call for a monitoring pollutant program and conservation strategies aimed to protect the dolphin population at BDT.

Three freshwater fishes (Tilapia zilli, Oreochomis niloticus and Schilbe mystus were caught from Cross River system between the period of February to April, 2012. The bone, liver and gills from the three species were carefully dissected for the determination of heavy metals. Levels of heavy metals were determined using Perkin-Elmer Analyst 300 Atomic Absorption spectrophotometer (AAS). The maximum concentration of heavy metals studied was observed in the liver tissues, while bone tissues had the least concentration. The highest concentration of copper was observed in O. niloticus, while Schilbe mystus show the least. For cobalt concentration, the maximum was obtained in Schilbe mystus and the minimum in T. zilli and O. niloticus. High levels of Lead (Pb), Iron (Fe), and Cobalt (Co) were found in the liver tissues of T. zilli and O. niloticus, while Schilbe mystus had the least concentrations. Variations in the parameters determined were found to be statistically significant (P< 0...

This study analyzed the levels of cadmium (Cd), copper (Cu), and zinc (Zn) by the flame atomic absorption spectrophotometer (FAAS), in the muscle tissues, exoskeletons, and gills from freshwater prawn (Macrobrachium rosenbergii) (n = 20) harvested from natural habitat in Kerang River, Malaysia on 25th November 2015. Significant increase of the metals level in muscle tissue and gill (r > 0.70, p < 0.05) were observed with increase in length except for Cu in gills. No relationship was found between metals level in exoskeleton and length. The concentrations of Cd, Cu and Zn were significantly higher (p < 0.05) in males (muscle tissues and exoskeleton) except for Cd in exoskeleton. In gills, only Cu was significantly higher (p < 0.05) in female than male. All samples contained metals below the permissible limit for human consumption (i.e., Cd < 2.00 mg/kg; Cu < 30.00 mg/kg; Zn < 150 mg/kg). Annual metals monitoring in prawn and environmental samples is recommended t...

Three freshwater fishes (Tilapia zilli, Oreochomis niloticus and Schilbe mystus were caught from Cross River system between the period of February to April, 2012. The bone, liver and gills from the three species were carefully dissected for the determination of heavy metals. Levels of heavy metals were determined using Perkin-Elmer Analyst 300 Atomic Absorption spectrophotometer (AAS). The maximum concentration of heavy metals studied was observed in the liver tissues, while bone tissues had the least concentration. The highest concentration of copper was observed in O. niloticus, while Schilbe mystus show the least. For cobalt concentration, the maximum was obtained in Schilbe mystus and the minimum in T. zilli and O. niloticus. High levels of Lead (Pb), Iron (Fe), and Cobalt (Co) were found in the liver tissues of T. zilli and O. niloticus, while Schilbe mystus had the least concentrations. Variations in the parameters determined were found to be statistically significant (P< 0...

Seedlings of Sinapis alba L. species (white/yellow mustard) were grown in nutrient solution containing different concentrations 50, 100, 250 and 500 mg/kg Cu for 10 days. Seedlings were measured and weighed at the end of the experiment. Leaf pigment concentration (chlorophylls a and b and carotenoids), tissular copper concentration and Biological Accumulation Coefficients (BAC) were determined. Copper content in Sinapis alba L. tissues reached 74.54 171.20 mg/kg dry mass, with highest values at high ambient concentration. BAC reached 1.49 at 50 mg/kg and was subunitary at higher concentrations, between 0.75 0.34. Shoot length and biomass emphasize a significant decrease at high ambient copper levels, while photosynthetic pigment concentrations did not decrease. These results indicate a limited tolerance of white mustard to high copper concentrations and a limited bioaccumulation potential of this metal.

Seedlings of Sinapis alba L. species (white/yellow mustard) were grown in nutrient solution containing different concentrations 50, 100, 250 and 500 mg/kg Cu for 10 days. Seedlings were measured and weighed at the end of the experiment. Leaf pigment concentration (chlorophylls a and b and carotenoids), tissular copper concentration and Biological Accumulation Coefficients (BAC) were determined. Copper content in Sinapis alba L. tissues reached 74.54 171.20 mg/kg dry mass, with highest values at high ambient concentration. BAC reached 1.49 at 50 mg/kg and was subunitary at higher concentrations, between 0.75 0.34. Shoot length and biomass emphasize a significant decrease at high ambient copper levels, while photosynthetic pigment concentrations did not decrease. These results indicate a limited tolerance of white mustard to high copper concentrations and a limited bioaccumulation potential of this metal.

Nineteen species belonging to four coral forms of the recent coral reefs were identified and studied in an area of high sedimentation stress. The trace metal contents were measured in the hard skeleton of the different species. The massive forms recorded the highest content of Cu, Fe, Mn and Ni, while the branching forms recorded the highest content of Pb and Zn relative to their relative abundance. The highest Fe, Mn and Pb contents in the different species are strongly attributed to the landfilling and the different anthropogenic impacts in the locality. The mechanism of the heavy metals bioaccumulation within the structure lattice of the coral skeletons is attributed to the biominerlization process and the residual oxides inside the pore spaces of the coral frameworks.

Objective To determine the quality of water, heavy metal content of edible muscles of a piscivorous fish (Protopterus annectens) and assess the health risks associated with using water and consumption of P. annectens from Nyabarongo and Nyabugogo rivers of Rwanda. Results All the water quality parameters were within World Health Organization’s acceptable limits except total nitrogen, iron, manganese and lead levels. Edible muscles of Protopterus annectens contained 272.8 ± 0.36, 292.2 ± 0.25, 8.8 ± 0.36, 135.2 ± 0.15, 148.0 ± 0.21 and 432. 0 ± 0.50 mg/kg of iron, manganese, copper, zinc, chromium and lead at Ruliba station and 336.0 ± 0.70, 302.6 ± 1.22, 6.4 ± 0.26, 44.7 ± 0.20, 138.2 ± 0.17 and 302.4 ± 1.50 mg/kg of iron, manganese, copper, zinc, chromium and lead at Kirinda bridge of Nyabarongo river. Health risk assessments indicated that though ingestion and dermal contact with heavy metals in water from the rivers may not cause obvious health effects, consumption of Protopterus...

Seedlings of Sinapis alba L. species (white/yellow mustard) were grown in nutrient solution containing different concentrations 50, 100, 250 and 500 mg/kg Cu for 10 days. Seedlings were measured and weighed at the end of the experiment. Leaf pigment concentration (chlorophylls a and b and carotenoids), tissular copper concentration and Biological Accumulation Coefficients (BAC) were determined. Copper content in Sinapis alba L. tissues reached 74.54-171.20 mg/kg dry mass, with highest values at high ambient concentration. BAC reached 1.49 at 50 mg/kg and was subunitary at higher concentrations, between 0.75-0.34. Shoot length and biomass emphasize a significant decrease at high ambient copper levels, while photosynthetic pigment concentrations did not decrease. These results indicate a limited tolerance of white mustard to high copper concentrations and a limited bioaccumulation potential of this metal.

Copper, manganese and zinc bioaccumulation potential was screened for three common Poaceae species, Hordeum murinum ssp. murinum L., Leymus racemosus ssp. sabulosus (M. Bieb.) Tzvelev and Lollium perenne L., abundantly growing along the Romanian Black Sea Coastal area, Constanta County. The concentration of the selected heavy metals was analyzed though atomic absorption spectrometry in samples of aboveground plant organs and soils. To assess the potential for phytoaccumulation, the Biological Accumulation Coefficients (BAC) were calculated. Considering the minimal thresholds widely accepted in literature for Cu, Mn and Zn hyperaccumulators, none of the selected species can fit in this category. The highest average copper concentration was found in Hordeum murinum ssp. murinum L. (5.45 mg/kg). For manganese, the highest value was found in Lollium perenne L. (104.08 mg/kg), while for zinc, the maximum was reached in Leymus racemosus ssp. sabulosus (M. Bieb.) Tzvelev, tissue (62.95 mg/kg). BAC values showed that all species are manganese excluders, with a remarkable maximum value of 0.55 in Lollium perenne. L. All species had average BAC above 1 for Cu and Zn, with a maximum in Leymus racemosus ssp. sabulosus (M. Bieb.) Tzvelev (4.85 and 2.98, respectively). However, there was a significant variation among individuals, usually, a high metal content in plant tissue being associated with low metal concentration in soil. The exception was Lollium perenne L., with BAC constantly above 1 (average BAC of 2.27 for Cu and 1.69 for Zn). These results emphasize a significant potential for phytostabilization of copper-and zinc-rich soils and open the way for heavy metals phytoextraction capacity studies of the Poaceae species along Romanian littoral.

-Heavy metal in Algae:
A- In Wadi Kandil region:
In Jania Genus: the Zinc concentration is ranged between (16.97 &116.36) μg/g, and
Lead between (0.287 & 0.896) μg/g, and Cadmium is increase from 0.08 to
0.211μg/g, Arsenic is ranged between 0.195 and 8.16μg/g.
IN another algae: the Zinc concentration is ranged between 11.98μg/g in Padina, and
189.85μg/g in Enteromorph, Lead is ranged between 0.007μg/g in Enteromorph till
2.374μg/g in Stypopodium, and Cadimium concentration is ranged between 0.002
μg/g in Galaxora & Sargassium till 0.53 it is recorded in Sargassium, the recorded
concentration of Arsenic is ranged between 0.013μg/g in Padina, till 8.39μg/g in
Stypopodium.
B- In Almina Altigary region:
1-in ULVA Genus: the Zinc concentration is ranged between(20.223 & 243) μg/g,
and the Lead concentration is low to May (0.85 &0.098) μg/g, and Cadmium
concentration is ranged between (0.069 & 0.915) μg/g, and Arsenic is ranged
between 0.499 and 16.58μg/g.
2-in Enteromorpha: which usually appears in march 2003 in this region, and the
Lead concentration is 0.869μg/g, and Zinc is reached to 50.3μg/g.

This study aimed to examine the mercury (Hg), lead (Pb), and nitrate (NO3) accumulation on Macrobrachium rosenbergii (shrimps) of Iponan River. The samples were analyzed using Cold Vapor Atomic Absorption Spectroscopy (CVAAS) for the heavy metals (Hg & Pb) and Bruccine Colorometric Method (BCM) for nitrate. One-way Analysis of Variance (ANOVA) and Standard Deviation analysis were used to test the significant difference in the concentration of the analytes on shrimps between sampling periods. Statistically, based on the results, there is significant difference on the concentration of lead, mercury and nitrates among sampling periods. M. rosenbergii contained high measured values of nitrate (NO3) analyte within two (2) sampling periods with concentrations of 120>32.8 ppm and 842>32.8 ppm respectively which exceeded the EPA standards. Lead concentration exceeds the BFAR standard (1.36>0.5) ppm during the second sampling while Hg content is present within specified standards. Results suggest that M. rosenbergii is a bioaccumulator of mercury

The rapid pace of urbanization and industrialization associated with intensive mining, processing and using
of metals has led to a significant raise of metal concentrations in the natural environment. Contamination of the soils,
hydrosphere and atmosphere with heavy metals is accompanied by an increased influence of these pollutants on plant
communities that are inherent part of any terrestrial or aquatic ecosystem. Several heavy metals (Cu, Fe, Mn, Mo, Ni,
Zn) are essential micronutrients necessary for plant growth and development; some others, such as Cd, Hg, Pb, are not
involved in metabolic processes, being considered as nonessential metals. The metals of both groups at high concentrations
can adversely affect plant growth and metabolic processes.
An excess of heavy metals in agricultural soils causes a decrease in crops yield, worsening the quality of vegetable
production and poses potential risk to human health. On the other hand, an important issue is the lack or limited bioavailability
of some trace metals in the soils, leading to slower growth of plants and increasing their vulnerability to
phytopathogens. Lack of essential metals in the tissues of plants growing on these soils may be associated with the development
of human microelementoses. Almost one third of the world’s population suffers from Fe and Zn deficiencies
due to low bioavailability of these elements in alkaline soils. The purpose of this paper is to analyze the factors that affect
the bioavailability of metals, the processes of their absorption and accumulation in plants, toxicity in plant cells, and
defense mechanisms that protect plants from heavy metal phytotoxicity.
Bioavailability of metals in the soils is known to determine the level of their absorption in plant root. It depends
on chemical form of metals and is largely governed by their presence in the soil solution in the form of ions that can
be transported through the plasma membrane of root cells. However, most of the essential metals occur in soil in insoluble
form, making them unavailable for uptake in the cells of the root system. Chemical and biological processes
in the rhizosphere and on the root surface are known to increase the content of soluble forms of metals in the environment
of plant growth. Organic chelators are important factors that enhance the processes of metal uptake by plants.
Excessive accumulation of metals in plant tissues may be accompanied by toxic effects that reduce plant viability
and productivity. The phytotoxic effects of metals are greatly dependent on their ability to induce the production of reactive
oxygen species (ROS) and development of oxidative stress in plant cells. Therefore antioxidant status maintained
by specific enzymes and non-enzymatic antioxidant molecules plays an important role in plant defense system against
oxidative damage. Besides that, the defense strategy of plants includes the binding of metal cations by the components
of plant cell walls, metal sequestration in vacuoles, as well as their complexation with thiol-containing peptides,
in cluding phytochelatins, glutathione and metallothioneins.
Many plants that grow on metal-polluted soils, have evolved the unique mechanisms providing high tolerance to
metal load and the ability to accumulate metals in their tissues at high concentrations without manifestation of toxicity.
The study of heavy metal hyperaccumulating plants is essential for their practical application in the processes of phytoremediation
of contaminated soil and aquatories, as well as for waste water treatment. On the other hand, elucidation
of mechanisms of plant metallotolerance is required for development the biofortified crops to prevent micronutrient
deficiency in human population.

In the San Francisco Estuary, management actions including tidal marsh restoration could change fish mercury (Hg) concentrations. From 2005 to 2007, small forage fish were collected and analyzed to identify spatial and interannual variation in biotic methylmercury (MeHg) exposure. The average whole body total Hg concentration was 0.052 μg g−1 (wet-weight) for 457 composite samples representing 13 fish species. MeHg constituted 94% of total Hg. At a given length, Hg concentrations were higher in nearshore mudflat and wetland species (Clevelandia ios, Menidia audens, and Ilypnus gilberti), compared to species that move offshore (e.g., Atherinops affinis and Lepidogobius lepidus). Gut content analysis indicated similar diets between Atherinops affinis and Menidia audens, when sampled at the same locations. Hg concentrations were higher in sites closest to the Guadalupe River, which drains a watershed impacted by historic Hg mining. Results demonstrate that despite differences among years and fish species, nearshore forage fish exhibit consistent Hg spatial gradients.

Total Reflection X-Ray Fluorescence (TXRF) has been applied for the first time to evaluate the kinetic behavior of the Cr(VI) bioaccumulation process that the recently isolated bacterium, named ANCR (Acinetobacter beijerinckii type), presents. First, a qualitative study of the bacterium elemental profile detected by TXRF has been carried out. Second, detection limits and the uncertainty of the technique were evaluated for this case. Finally, an experiment was designed to evaluate the behavior of the chromium content by two ways: in the cultured medium of the experiment, evaluating its decrease, and bioaccumulated in the bacteria, evaluating its increase. The results demonstrate that this new strain of Acinetobacter bacterium is able to reduce the chromium present in the culture medium. As a consequence, it can be used as a promising microorganism for Cr(VI) bioremediation from polluted wastewaters. Finally, TXRF has shown its versatility, potential and sensitivity for the analytical evaluation of toxic metals in this kind of microbiological system.

Metal levels (Cd, Cr, Cu, Fe, Mn, Pb and Zn) in the gill, hepatopancreas, ovary, testis and mantle of male and female
cuttlefish Sepia officinalis in İskenderun Bay were investigated. All elements differ in accumulation in tissues and sex
significantly (p<0.05). Concentrations of Cd in the tissues of male and female cuttlefish samples ranged between 0.12-34.7
mg/kg. Cr levels in tissues of males and females ranged between 0.59-1.26 mg/kg. Cu concentrations in all tissues were found
and ranged between 8.83 and 1296 mg/kg. Fe concentrations in the mantle of female and male samples were found 0.35 and
0.36 mg/kg, respectively. Pb concentrations in the mantles of female and male samples were found between 1.74-1.79 mg/kg.
The highest Zn concentrations in hepatopancreas of male and female samples were found 181 mg/kg and 272 mg/kg
respectively (P<0.05). In the mantle tissue of S. officinalis, metal levels independent of sex were in the following order:
Cu>Zn>Cd>Pb>Cr>Mn>Fe. In accordance with limit values, the present study found out that the mantle tissue of cuttlefish,
S. officinalis, was overlimited with Cd and Pb

This study documents changes in contamination over time at seasonal, interannual, and decadal time scales for sport fish collected in San Francisco Bay. Samples from seven fish species were prepared according to common consumption practices (muscle fillets either with or without skin) and analyzed for trace metals (mercury and selenium) and trace organochlorine contaminants (PCBs, DDTs, chlordanes, and dieldrin). In 2000, sport fish samples exceeded human health screening values for mercury, PCBs, DDTs, selenium, and dieldrin but did not exceed screening values for chlordanes. On a seasonal time scale, white croaker (Genyonemus lineatus) exhibited significantly lower PCB and lipid concentrations in spring, and a general increase in concentrations in other seasons. When monitoring data were compared among 1994, 1997, and 2000, analysis of variance indicated that concentrations of mercury, PCBs, DDTs, and chlordanes varied significantly among years for several fish species. Interannual variation in DDTs often correlated to changes in sampled fish size or lipid content among years. Interannual variation in mercury and PCBs was evident in striped bass (Morone saxatilis) but absent in shiner surfperch (Cymatogaster aggregata), leopard shark (Triakis semifasciata), and white croaker. The higher interannual variability of striped bass contaminant concentrations may result from migratory behavior and wide home ranges. Chlordanes significantly declined between 1994 and 2000 in white croaker and striped bass. Of the historical data analyzed (1986–2000), only DDT concentrations in white sturgeon (Acipenser transmontanus) showed evidence of a significant decline. Neither PCBs nor selenium showed evidence of a trend in white sturgeon. Between 1970 and 2000, mercury concentrations in striped bass showed no evidence of a trend. The absence of recent trends in mercury may result from the presence of widespread and historic sources, with use reductions occurring in the early 20th century. In contrast to mercury, apparent recent declines in fish tissue DDT and chlordane concentrations may result from use curtailment in the 1970s and 1980s.