Phenanthrene Uptake Research Articles

Uptake and distribution of phenanthrene and pyrene in roots and shoots of maize (Zea mays L.).

Polycyclic aromatic hydrocarbons as byproducts of carbon-based fuel combustion are an important group of pollutants with wide distribution in the environment. Polycyclic aromatic hydrocarbons are known as toxic compounds for almost all organisms. Different plant species can uptake polycyclic aromatic hydrocarbons by roots and translocate them to various aerial parts. The aim of this study is to investigate the uptake, translocation, and accumulation of pyrene and phenanthrene in maize under controlled conditions. Seeds were cultivated in perlite containing 25, 50, 75, and 100 ppm of phenanthrene and pyrene, and their concentrations in the roots and shoots of the plants were measured using high-performance liquid chromatography technique after 7, 14, and 21 days. The results revealed that phenanthrene naturally existed in maize and its concentration showed a time-dependent decrease in shoots and roots. In contrast, the concentration of pyrene was increased in the roots and reduced in the shoots. Although pyrene had higher uptake than phenanthrene in roots of maize, the translocation factor value for pyrene was lower than for phenanthrene. According to these findings, phenanthrene could be metabolized in maize in the shoot and root tissues, but pyrene had more tendency to be accumulated in roots.

Comparison of phenanthrene removal by Aspergillus niger ATC 16404 (filamentous fungi) and Pseudomonas putida KT2442 (bacteria) in enriched nutrient-liquid medium

Polycyclic Aromatic Hydrocarbons (PAHs) is one of the persistent and carcinogenic pollutants that needs to be eliminated from the environment. The study on degradation of PAHs by bacteria is thoroughly discussed in literature. Many strains of bacteria were chosen in order to eliminate the PAHs compound in the environment. However, there are less study on the filamentous fungi although fungi appears to be an abundant population and as dominant group in PAHs contaminated soil habitats [1], [2]. This study was conducted to determine and compare the Phenanthrene (PHE) removal by fungi and bacteria in excessive nutrient-liquid culture. Then, the survival for both strains was investigated in the presence of PHE and finally, the analysis on the fungi-PHE interaction was carried out. In condition of excessive nutrient, the removal of PHE was evaluated for fungi and bacteria in batch experiment for 5 days. PHE removal for A.niger and P.putida were found to be 97% and 20% respectively after 5 days. The presence of PHE was negatively inhibits the grow of the bacteria and the fungus. The PHE uptake mechanism for A.niger was observed to be a passive transport mechanism with 45 μg per g fungus dry weight within 24 hr of incubation. As a conclusion, filamentous fungi have the potent role in the removal of PHE as well as bacteria but depending on the strains and the condition of the environment. Fungi is known to co-metabolize the PHE meanwhile, PHE can be used as sole carbon for bacteria. This preliminary result is significant in understanding the bacteria-fungi-PHE interaction to enhance the degradation of PAHs for co-culture study in the future.

Short-term influence of nutrient availability on the uptake and translocation of phenanthrene in mangrove seedlings

The uptake and distribution of phenanthrene, a typical polycyclic aromatic hydrocarbon, in plant tissues of Aegiceras corniculatum and Avicennia marina and the relationship with nutrient (nitrate, ammonium, and soluble reactive phosphorus) availability were investigated. After 12 h of exposure, enhancements in the concentration of nitrate and soluble reactive phosphorus markedly decreased the residual level of phenanthrene in roots, while the addition of ammonium significantly increased the residual concentration. Due to the similar enzymatic degradation potential between treatment groups, the variation of phenanthrene concentration in mangrove roots may result from the H+/phenanthrene cotransport at the root surface that was influenced by nutrient uptake. Moreover, both nitrate and soluble reactive phosphorus amendments significantly increased translocation of phenanthrene from roots to leaves, which likely resulted from the change of hydraulic conductivity in mangrove plants triggered by different nutrient availability.

Apoplastic and symplastic uptake of phenanthrene in wheat roots.

The contamination of agricultural crops by polycyclic aromatic hydrocarbons (PAHs) has drawn considerable attention due to their carcinogenicity, mutagenicity, and toxicity. However, the uptake process of PAHs in plant roots has not been clearly understood. In this work, we first study the radial uptake of phenanthrene in hydroculture wheat roots by vacuum-infiltration-centrifugation method. The concentration-dependent kinetics of apoplastic and symplastic uptake at phenanthrene concentrations of 0-6.72μM for 4h can be described with the Langmuir and Michaelis-Menten equations, respectively; whereas, their time-dependent kinetics at 5.60μM phenanthrene for 36h follow the Elovich equation. The apoplastic and symplastic uptake increases with temperature of 15-35°C. The apparent Arrhenius activation energies for apoplastic and symplastic uptake are 77.5 and 9.39KJmol-1, respectively. The symplastic uptake accounts for over 55% of total phenanthrene uptake, suggesting that symplast is the dominant pathway for wheat root phenanthrene uptake. Larger volume of symplast in roots and lower activation energy lead to the greater contribution of symplast to total uptake of phenanthrene. Our results provide not only novel insights into the mechanisms on the uptake of PAHs by plant roots, but also the help to optimize strategies for crop safety and phytoremediation of PAH-contaminated soil/water.

Evaluation of bacterial biodegradation and accumulation of phenanthrene in the presence of humic acid

This study evaluated the effect of humic acid (HA) on physicochemical properties of bacterial surfaces and on mass transfer of polycyclic aromatic hydrocarbons (PAHs) from aqueous phase into intracellular bacteria. Due to this process’ potential for bacterial degradation, using Sphingobium sp. PHE3, degradation of phenanthrene (PHE) was compared in HA and non-HA sets. The results showed that approximately 51.1% of PHE at a concentration of 102.0 mg L−1 was biodegraded in the non-HA sets, whereas almost all PHE was biodegraded with HA after 72 h. Interestingly, PHE that accumulated in the intracellular bacteria reached 3.80 mg L−1 for the HA sets, which was significantly higher than that of non-HA. Lipid inclusion bodies appeared when Sphingobium sp. PHE3 was treated with HA. The results were further confirmed by the enhanced bacterial surface sorption capacity for the HA sets. Therefore, we concluded that added HA not only act as carriers and biosurfactants facilitating PHE uptake but also adjust bacteria cell wall properties for internalizing PHE, which ultimately overcame the PHE bioavailability resulting in enhanced biodegradation.

Uptake of benzo[a]pyrene, but not of phenanthrene, is inhibited by fatty acids in intestinal brush border membrane vesicles of rainbow trout (Oncorhynchus mykiss)

Partial replacement of fish ingredients with vegetable ingredients has elevated levels of polycyclic aromatic hydrocarbons (PAHs) in Atlantic salmon reared on these feeds. PAH uptake in the intestinal tract is postulated to occur in association with lipid absorption and could well be affected by fatty acid composition. We therefore investigated the effects of a fish oil and vegetable oil fatty acid, eicosapentaenoic acid (EPA; 20:5n−3) and oleic acid (18:1n−9) respectively, on the uptake of benzo[a]pyrene (BaP) and phenanthrene (PHE) across the intestinal brush border membrane in the salmonid species rainbow trout (Oncorhynchus mykiss).BaP and PHE were solubilized in mixed micelles composed of either EPA or oleic acid and administrated to isolated brush border membrane vesicles (BBMV) derived from the pyloric caeca, proximal intestine and distal intestine. In the absence of free fatty acids (FFA) trans-membrane uptake of BaP and PHE was 2–7 times lower than the fraction associated to or in the membrane. In the presence of FFA, trans-membrane BaP uptake had decreased by 80 and 40% at the highest EPA and oleic acid concentration, respectively, whereas PHE uptake was virtually unaffected. In the presence of BaP, but not PHE, trans-membrane EPA uptake in BBMV had decreased.This study obtained evidence for PAH-dependent interactions with FFA uptake. We conclude that intestinal BaP uptake is reduced by luminal FFA contents whereas PHE uptake is not. A large fraction of the administrated BaP and PHE remains associated with the cellular membrane of enterocytes and may interfere with uptake of nutrients.

Tracking the route of phenanthrene uptake in mosses: An experimental trial

In recent decades, mosses have been used as native species or as transplants in monitoring a wide range of pollutants from inorganic (i.e. metals and metalloids) to organic contaminants (mainly polycyclic aromatic hydrocarbons-PAHs). To implement the use of mosses as biomonitors of PAHs, one important issue is the study of the interactions between these compounds and moss tissues. In this study we investigated the mode of phenanthrene uptake in four moss species (Amblystegium humile, Plagiomnium affine, Hypnum cupressiforme and a clone of Sphagnum palustre) and its movements from air to plant surface and within the biomonitors, using fluorescent and confocal microscopy. The target compound, partitioned between gas and particulate phase depending on air conditions, was selected since it is one of the most abundant PAHs released into the atmosphere. Our findings support the hypothesis that phenanthrene aggregates in particles and in this form it is chiefly intercepted and uptaken onto moss surfaces, albeit with different frequency in the four species, with S. palustre>H. cupressiforme>P. affine=A. humile. Phenanthrene enters the dead, empty hyalocysts of S. palustre. Specific surface area and composition, frequency and distribution of binding groups may also explain the different ability of phenanthrene uptake by the four moss species.

In situ determination of multiple polycyclic aromatic hydrocarbons uptake by crop leaf surfaces using multi-way models

Polycyclic aromatic hydrocarbons (PAHs) in the atmosphere can partition into agricultural crops, which poses a potential risk to human health through the food chain. In this study, controlled chamber experiments were conducted to investigate the kinetic uptake of anthracene (Ant), phenanthrene (Phe), fluoranthene (Fla) and pyrene (Pyr), individually or as a mixture, by the leaf surfaces of living soybean and corn seedlings using the excitation-emission matrix (EEM) coupled with three-way parallel factor analysis (PARAFAC) and n-way partial least squares (n-PLS). The four selected PAHs achieved equilibrium between the air and the two living crop leaf surfaces over the 15-day monitoring period. Inter-species and inter-chemical variability existed in terms of the time required to achieve equilibrium, mass transfer coefficients (kAL) and the equilibrated adsorption capacity (EAC), which was mainly attributed to the different lg KOA values among the four PAHs and the variable leaf-wax content between the soybean and corn species. Compared with when the PAHs existed singly, the time required to achieve adsorption equilibrium was longer while the EAC was reduced for each of the four PAHs in a mixture, which was attributed to competitive adsorption among the coexisting components. These findings prove that the novel analytical method provides a novel platform for the in situ characterization of the environmental behaviors of multiple PAHs, with their spectra overlapping, between the air and plant skin. The coexistence of multiple PAHs in the air inhibits their individual uptake capacity by crop leaf skin, but increases the total adsorption of PAHs, potentially reducing crop security and increasing human health risk via the terrestrial food web.

Rhizodegradation potential and tolerance of Avicennia marina (Forsk.) Vierh in phenanthrene and pyrene contaminated sediments

A pot experiment was conducted to investigate the dissipation of phenanthrene and pyrene in spiked sediments with presence of Avicennia marina (Forsk.) Vierh. The rhizosphere environment was set up using a self-design nylon rhizo-bag which divided the sediment into the rhizosphere and non-rhizosphere. Results showed that the dissipation of phenanthrene and pyrene were significantly enhanced in the rhizosphere compared with non-rhizosphere sediments. Plant roots promoted dissipation significantly greater than the contribution of direct plant uptake and accumulation of phenanthrene and pyrene. The activities of antioxidant and detoxification enzymes in roots and leaves significantly increased against oxidative stress with increasing PAH concentrations. Furthermore, a significant relationship (R2>0.91) between dissolved organic carbon (DOC) concentrations and the residual of PAHs in rhizosphere and non-rhizosphere sediments was observed after 120days planting. Results indicated that rhizome mediation with A. marina is a useful approach to promote the depletion of PAHs in contaminated mangrove sediments.

Adsorption of organic contaminants by graphene nanosheets, carbon nanotubes and granular activated carbons under natural organic matter preloading conditions

The effect of NOM preloading on the adsorption of phenanthrene (PNT) and trichloroethylene (TCE) by pristine graphene nanosheets (GNS) and graphene oxide nanosheet (GO) was investigated and compared with those of a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube (MWCNT), and two coal based granular activated carbons (GACs). PNT uptake was higher than TCE by all adsorbents on both mass and surface area bases. This was attributed to the hydrophobicity of PNT. The adsorption capacities of PNT and TCE depend on the accessibility of the organic molecules to the inner regions of the adsorbent which was influenced from the molecular size of OCs. The adsorption capacities of all adsorbents decreased as a result of NOM preloading due to site competition and/or pore/interstice blockage. However, among all adsorbents, GO was generally effected least from the NOM preloading for PNT, whereas there was not observed any trend of NOM competition with a specific adsorbent for TCE. In addition, SWCNT was generally affected most from the NOM preloading for TCE and there was not any trend for PNT. The overall results indicated that the fate and transport of organic contaminants by GNSs and CNTs type of nanoadsorbents and GACs in different natural systems will be affected by water quality parameters, characteristics of adsorbent, and properties of adsorbate.

Exogenous IAA treatment enhances phytoremediation of soil contaminated with phenanthrene by promoting soil enzyme activity and increasing microbial biomass.

In this study, we aimed to confirm that indole-3-acetic acid promotes plant uptake of phenanthrene (PHE), stimulates the activity of soil enzymes or microflora, and thereby accelerates the dissipation of PHE in soil. Four treatments were evaluated: PHE-contaminated soil planted with (1) ryegrass (T0), (2) ryegrass and supplemented with 1mgkg(-1) indole-3-acetic acid (IAA) (T1), (3) ryegrass and supplemented with 5mgkg(-1) IAA (T5), and (4) ryegrass and supplemented with 10mgkg(-1) IAA (T10). After 30days, PHE concentrations were lower for all treatments and the removal rate was 70.19, 89.17, 91.26, and 97.07% for T0, T1, T5, and T10, respectively. PHE was only detected in the roots and not in the shoots. IAA facilitated the accumulation of PHE in the roots, and plants subjected to the T10 treatment had the highest levels. Exogenous IAA stimulated soil peroxidase activity in a dose-dependent manner, whereas soil polyphenoloxidase activity was not significantly increased, except in T10. Soil microbial biomass also increased in response to IAA treatment, particularly in T10. Furthermore, phospholipid fatty acid analysis showed that IAA treatment increased microbial biomass and alleviated environmental stress. Gram-positive bacteria are largely responsible for polycyclic aromatic hydrocarbon degradation, and we found that the ratio of gram-positive to gram-negative bacteria in the soil significantly increased as the IAA concentrations increased (P < 0.05). Correlation analysis indicated that the increase in soil microbial biomass, enzyme activity, and plant uptake of PHE promotes removal of PHE from the soil.

Novel Phenanthrene-Degrading Bacteria Identified by DNA-Stable Isotope Probing.

Microorganisms responsible for the degradation of phenanthrene in a clean forest soil sample were identified by DNA-based stable isotope probing (SIP). The soil was artificially amended with either 12C- or 13C-labeled phenanthrene, and soil DNA was extracted on days 3, 6 and 9. Terminal restriction fragment length polymorphism (TRFLP) results revealed that the fragments of 219- and 241-bp in HaeIII digests were distributed throughout the gradient profile at three different sampling time points, and both fragments were more dominant in the heavy fractions of the samples exposed to the 13C-labeled contaminant. 16S rRNA sequencing of the 13C-enriched fraction suggested that Acidobacterium spp. within the class Acidobacteria, and Collimonas spp. within the class Betaproteobacteria, were directly involved in the uptake and degradation of phenanthrene at different times. To our knowledge, this is the first report that the genus Collimonas has the ability to degrade PAHs. Two PAH-RHDα genes were identified in 13C-labeled DNA. However, isolation of pure cultures indicated that strains of Staphylococcus sp. PHE-3, Pseudomonas sp. PHE-1, and Pseudomonas sp. PHE-2 in the soil had high phenanthrene-degrading ability. This emphasizes the role of a culture-independent method in the functional understanding of microbial communities in situ.

Cytoplasmic pH-Stat during Phenanthrene Uptake by Wheat Roots: A Mechanistic Consideration.

Dietary intake of plant-based foods is a major contribution to the total exposure of polycyclic aromatic hydrocarbons (PAHs). However, the mechanisms underlying PAH uptake by roots remain poorly understood. This is the first study, to our knowledge, to reveal cytoplasmic pH change and regulation in response to PAH uptake by wheat roots. An initial drop of cytoplasmic pH, which is concentration-dependent upon exposure to phenanthrene (a model PAH), was followed by a slow recovery, indicating the operation of a powerful cytoplasmic pH regulating system. Intracellular buffers are prevalent and act in the first few minutes of acidification. Phenanthrene activates plasmalemma and tonoplast H(+) pump. Cytolasmic acidification is also accompanied by vacuolar acidification. In addition, phenanthrene decreases the activity of phosphoenolpyruvate carboxylase and malate concentration. Moreover, phenanthrene stimulates nitrate reductase. Therefore, it is concluded that phenanthrene uptake induces cytoplasmic acidification, and cytoplasmic pH recovery is achieved via physicochemical buffering, proton transport outside cytoplasm into apoplast and vacuole, and malate decarboxylation along with nitrate reduction. Our results provide a novel insight into PAH uptake by wheat roots, which is relevant to strategies for reducing PAH accumulation in wheat for food safety and improving phytoremediation of PAH-contaminated soils or water by agronomic practices.

Fluorene and Phenanthrene Uptake and Accumulation by Wheat, Alfalfa and Sunflower from the Contaminated Soil

Polycyclic Aromatic Hydrocarbons (PAHs) are diverse organic contaminants released into the environment by both natural and anthropogenic activities. These compounds have negative impacts on plants growth and development. Although there are many reports on their existence in different parts of plant, their uptake and translocation pathways and mechanisms are not well understood yet. This paper highlights the uptake, translocation and accumulation of PAHs by wheat, sunflower and alfalfa through an experimental study under controlled conditions. Seeds were cultivated in a soil containing 50 mg/kg of phenanthrene and fluorene and their concentrations in plants roots and shoots were determined using a gas chromatograph after 7 and 14 days. The results showed that phenanthrene and fluorene concentrations in the treated plants were increased over the time. PAHs bioavailability was time and species dependent and generally, phenanthrene uptake and translocation was faster than that of fluorene, probably due to their higher Kow. Fluorene tended to accumulate in roots, but phenanthrene was transported to aerial parts of plants.

Impact of phenanthrene exposure on activities of nitrate reductase, phosphoenolpyruvate carboxylase, vacuolar H+-pyrophosphatase and plasma membrane H+-ATPase in roots of soybean, wheat and carrot

Crops differ in uptake of polycyclic aromatic hydrocarbons (PAHs). However, the physiological mechanism underlying the differences in PAH uptake among crop species is unclear. As PAH transport by H+-coupled symporters may affect cytosolic pH, and intracellular pH is precisely regulated for metabolism, four enzymes linked with cytosolic pH regulation in root cells were determined at different concentrations of phenanthrene (PHE) and pHs. Activity of nitrate reductase (NRase) is stimulated by PHE and follows the order: wheat>carrot>soybean. The optimum pH of NRase is 7.5 in wheat and carrot, while 6.5 in soybean. The activity of phosphoenolpyruvate carboxylase (PEPCase) is generally decreased by PHE and always lower in soybean than in wheat and carrot. PEPCase peaks its maximum activity at pH 7.0 and wheat shows the highest value with high PHE (1.2mgL−1) at pHs of 7.0 and 8.0 in comparison with carrot and soybean. Vacuolar H+-pyrophosphatase (V-H+-PPase) is promoted by PHE in wheat and carrot, while it does not change significantly in soybean (P>0.05). V-H+-PPase reaches its maximum value at pH 7.5 and follows the order of wheat>carrot>soybean at alkaline medium with high PHE. Plasma membrane (PM) H+-ATPase is enhanced by K+ and follows the order: wheat>soybean>carrot. The orders of activity of these enzymes are not consistent with that of PHE uptake, indicating their various functions. However, in soybean, PM H+-ATPase activity under high PHE and the uptake of PHE are always higher than those in wheat and carrot, suggesting that PM H+-ATPase plays an essential role in PHE uptake. Therefore, the changes of PM H+-ATPase activity seem to be a direct consequence responding to PHE stress and those of NRase, PEPCase and V-H+-PPase might be the downstream accidents regulated by cytosoilc pH. Our study provides insight into the roles of these enzymes in non-photosynthetic tissues and supports their importance in the physiological responses to PHE stress among different crops.

Response of uptake and translocation of phenanthrene to nitrogen form in lettuce and wheat seedlings.

Polycyclic aromatic hydrocarbons (PAHs) are widespread chemicals that are potentially carcinogenic and toxic to human due to dietary intake of food crops contaminated by PAHs. To date, the mechanisms underlying root uptake and acropetal translocation of PAHs in crops are poorly understood. Here we describe uptake and translocation of phenanthrene (a model PAH) in relation to nitrogen form and concentration in wheat and lettuce seedlings. At concentrations of 0-15 mM, phenanthrene uptake by roots is enhanced with an increase in ammonium and inhibited with an increment of nitrate. Phenanthrene concentration in shoots is much lower than in roots, suggesting that the direction of phenanthrene transport is acropetal. Ammonium reduces both phenanthrene accumulation and bioconcentration factor in shoots, as well as translocation factor, but nitrate elevates them. Phenanthrene uptake increases nutrient solution pH in the treatments with either nitrate or ammonium. Thus, it is concluded that the root uptake and acropetal translocation of phenanthrene in crops are associated with nitrogen form. Our results provide both a novel insight into the mechanism on PAH transport in higher plants and a promising agronomic strategy to minimize PAH contamination in crops or to improve phytoremediation of PAH-contaminated soils or water via nitrogen management.

A Hierarchic Method for Studying the Distribution of Phenanthrene in Eisenia fetida

The distribution of heavy metals in earthworms has been widely studied, highlighting the importance of the fate of these metals. However, little information is available on the distribution of hydrophobic organic contaminants (HOCs) within earthworms. The aim of this study was to propose a hierarchic method to study the distribution of phenanthrene (PHE), a typical HOC, in Eisenia fetida at several levels: sub-organism (pre-clitellum, clitellum and post-clitellum), tissue (body wall, gut and body fluid) and subcellular (intracellular and extracellular fractions). Earthworms were incubated in the soils amended with low (LC, 10 mg kg−1) and high concentrations (HC, 50 mg kg−1) of PHE and sampled at different time intervals. At the sub-organism level, the distribution of PHE was homogeneous among the sub-organism fractions in the LC treatment but heterogeneous in the HC treatment and gradually reached the following form of post-clitellum ≈ clitellum > pre-clitellum. The uptake and elimination kinetics of PHE in the sub-organism were well described by a one-compartment model. At the tissue level, the concentration of PHE followed the order of gut > body fluid > body wall; while at the subcellular level, the concentration of PHE in the extracellular fraction was 1.23 to 4.68 times higher than that in the intracellular fraction. Therefore, the simple circulatory system of earthworms may account for the PHE distribution at the sub-organism level. Partition pathways (passive diffusion) of PHE between the body wall, body fluid and gut as well as the processes of PHE entrance into the inner cellular compartment via passive diffusion were experimentally supported.

Phytoremediation of phenanthrene by transgenic plants transformed with a naphthalene dioxygenase system from Pseudomonas.

Genes from microbes for degrading polycyclic aromatic hydrocarbons (PAHs) are seldom used to improve the ability of plants to remediate the pollution because the initiation of the microbial degradation of PAHs is catalyzed by a multienzyme system. In this study, for the first time, we have successfully transferred the complex naphthalene dioxygenase system of Pseudomonas into Arabidopsis and rice, the model dicot and monocot plant. As in bacteria, all four genes of the naphthalene dioxygenase system can be simultaneously expressed and assembled to an active enzyme in transgenic plants. The naphthalene dioxygenase system can develop the capacity of plants to tolerate a high concentration of phenanthrene and metabolize phenanthrene in vivo. As a result, transgenic plants showed improved uptake of phenanthrene from the environment over wild-type plants. In addition, phenanthrene concentrations in shoots and roots of transgenic plants were generally lower than that of wild type plants. Transgenic plants with a naphthalene dioxygenase system bring the promise of an efficient and environmental-friendly technology for cleaning up PAHs contaminated soil and water.

Effects of metals on the uptake of polycyclic aromatic hydrocarbons by the cyanobacterium Microcystis aeruginosa

Effects of Cu2+, Zn2+, Cd2+, and Ag+ on the uptake of phenanthrene, pyrene, and benzo[a]pyrene by Microcystis aeruginosa were investigated. A biomimic passive sampler, triolein embedded cellulose acetate membrane (TECAM) was used to help to study the related mechanisms. The facilitation effects of the metals on the uptake of the PAHs by M. aeruginosa increased with the softness order of the metals (Zn2+≈Cd2+<Cu2+<Ag+) and the π donor strength of the PAHs (phenanthrene<pyrene<benzo[a]pyrene). The cation–π interactions between Cu2+, Ag+ and the PAHs increased the freely dissolved concentrations of the PAHs, and consequently their uptake by M. aeruginosa. The increase in aromaticity of dissolved organic matter (DOM) caused by Cu2+, and Ag+ also enhanced the uptake of the PAHs. The facilitation effects of Cu2+, and Ag+ exceeded their toxic effects, uptake of the PAHs was thereby enhanced. In the presence of Zn2+, and Cd2+, no cation–π interactions between Zn2+, Cd2+ and the PAHs formed in solutions. Aromaticity of DOM was reduced, the diffusive mass transfer of the PAHs was not enhanced. Uptake of the PAHs was thereby reduced. This study suggests that uptake of PAHs by phytoplankton can be significantly influenced by the properties of both metals and PAHs, which will help to understand the fate and risks of PAHs in eutrophic waters co-contaminated with metals.

Bioremediation of The Crude Oil Contamination of Soil by The Indigenous, Herbaceous Plant Salicorniaeuropea in Iran

Objectives: The aim of this study was to investigate the quantitative uptake of Phenanthrene ’ s (as one of the most important PAHs in crude oil) by Salicorniaeuropea and also the effectiveness of crude oil content on normal condition of this plant especially at various concentrations. Materials and Methods: Salicornia plantlets were taken from Eshtehard plant bank which is located in Karaj, Alborz, Iran. They were transplanted and exposed to various t concentrations of crude oil (4.5-16-27.5-32-36.5 g/kg soil). Spectrophotometery and Gas Chromatography-Mass Spectroscopy methods were used to determine and identify the phenanthrene uptake in roots and stalks, also the plants’ appearance were checked out. Results: The highest uptake was at eight mg crude oil, per 1 g of soil and the least uptake was at 13.75 mg crude oil, per 1 g of soil. It seems that physical characteristics of crude oil are the main reasons of damages to plant tissue. Conclusions: Concerning the ability of Salicorniaeuropea to survive in the contaminated areas, it might be suitable that endemic types of this plant would be cultivated in contaminated coast lines.