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In this study, the phytoremediation capacity ofAzolla filiculoidesLam. for the water resources contaminated with petroleum hydrocarbons was investigated. The plants were grown in nitrogen-free Hoagland nutrient solution containing 0.005%, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% crude oil under greenhouse conditions for 15 days. Although the growth rate of the plants were not negatively influenced by the presence of crude oil in the media for the concentration of 0.005% and 0.01% v/v, a gradual impeding effect of crude oil in the growth media has been observed at concentrations 0.05–0.1%. More than 0.1% crude oil in the growth medium ostensibly retarded the growth. For example, 0.2% oil in the media reduced growth approximately 50% relative to the control, and the presence of crude oil at concentrations 0.3% or more were lethal. The data about the percentage of plant growth, fresh weight increase and root growth clearly indicated that the tolerance level ofA. filiculoidesplants to crude oil ranges between 0.1% and 0.2%. In comparison to control samples, the biodegradation rate of total aliphatic and aromatic (phenathrene) hydrocarbons at 0.05–0.2% oil concentrations, was 94–73% and 81–77%, respectively. On the other hand, in case of further increases in oil concentration in media, i.e.; 0.3–0.5%, the biodegradation rate was still higher in the experimental samples, respectively 71–63% and 75–71%. The high biodegradation rates of petroleum hydrocarbons in the experimental samples suggested thatA. filiculoidesplants could be a promising candidate to be used for the phytoremediation of low crude oil contaminated precious freshwater resources. [ABSTRACT FROM PUBLISHER]

Phytoremediation of freshwater contaminated with crude oil is a technology that can restore damaged freshwater areas. Lemna minor is a small vascular plant that reproduces rapidly, is sensitive to a wide variety of pollutants, and is easy to culture. This study aimed to evaluate the phytoremediation capacity of L. minor in crude oil spiked cultures. Cultivation was carried out for 7 days in a greenhouse with a natural photoperiod and in nutrient solutions containing 0.5%, 1%, 2%, and 3% crude oil. Extracts were analyzed using GC/MS and synchronous UV fluorescence spectroscopy. After a week of cultivation, the fresh weight of plants in the control medium increased by 117%. The presence of crude oil up to 0.5% v/v reduced growth as much as 50% relative to the control plants. C17/ Pr and C18/Ph ratios decreased especially in the presence of 0.5% to 2% v/v crude oil in the growth media. In 0.5% oil concentrations, both unplanted control samples and plant samples contained no 1-4 ring polycyclic aromatic hydrocarbons. However, at oil applications of 0.5% and 1%, the plant samples contained 5 ring polycyclic aromatic hydrocarbons; their intensity was approximately two times lower than that of the unplanted control samples. It can be concluded that the biodegradation potential of L. minor strongly depends on the concentration of crude oil contaminants. Finally, the phytoremediative capacity of L. minor is only suitable for cleaning of freshwater resources containing small amounts of oil contaminants. [ABSTRACT FROM AUTHOR]

In this study, the potential of Landoltia punctata for petroleum phytoremediation was evaluated. L. punctata was treated with different concentrations of Batman crude oil (BCO). The plants were grown in nutrient solutions containing 0.5%, 1%, 2%, and 3% BCO by volume in a growth chamber for 7 days. The fresh weight of the plants in the presence of BCO at a concentration of 0.5% v/v increased by 60% relative to the initial fresh weight. Furthermore, in comparison to the control, plant growth was retarded by 72% and 91% at concentrations of 2% and 3%, respectively. When plants were grown in media containing 0.5% BCO, more than 90% of C15-C25 n-alkane compounds were removed compared to the unplanted control (medium plus 0.5% BCO without plants). Pristane (Pr) and phytane (Ph) were both present in all samples, except in the experimental medium of 0.5% BCO application. On the other hand, Pr/Ph values obtained from all oil applications were not statistically different from those of the control samples. As a result, L. punctata could be used for the phytoremediation of fresh water resources contaminated with up to 1% crude oil. [ABSTRACT FROM AUTHOR]

Phytoremediation of petroleum hydrocarbons from soil is a promising approach because of its low cost and environmentally friendly nature. This work intends to con- tribute to this area by investigating the potentials of common forage legumes, red clover (Trifolium pratense L.) and white clover (Trifolium repens L.), for petroleum oil phytoremediation. Five different cultivars of red clover (Namuq, 79, 818, Lakeland, 1881) and 3 cultivars of white clover (361, 453, 455) were used to evaluate intra- and interspecific variability in terms of their phytoremediative potential. The seeds were germinated in soil mixed with 1, 5 and 7% (v/v) Siberian light crude oil (SBL), and the seedlings were grown for 30 days at the same media. Germination ratio (%), stem length, number and width of leaves were used as physiological parameters for pre- evaluation of plantlets for oil tolerance. It was shown that white clover is not tolerant to oil contamination, whereas red clover can prevail up to 7% of crude oil application despite the significant decrease in the biomass. The most tolerant cultivar of red clover was Lakeland. Aliphatic hydrocarbon fingerprints observed in the GC-MS chromatograms of leaf extracts pointed out this cultivar as a valuable source of information for understanding the tolerance mechanism of plants to hydrocarbons. [ABSTRACT FROM AUTHOR]

Heavy metals are significant inorganic environmental pollutants. Brassica juncea, frequently used as model for phytoremediation studies, can (hyper)accumulate some heavy metals with well-developed root system. Even though the elucidation of the differentially expressed genes in response to heavy metals is important for the improvement of phytoremediation capacity of plants, there has been limited number of reports about detailed functional characterization of these genes. In this study, 50 μM Pb(NO 3 ) 2 and 25 μM CdSO 4 were applied separately to 31 days-old Brassica juncea (var. P78) plants for 24 h to identify the putative genes associated with lead (Pb) and cadmium (Cd) stress. The metal content analyses indicated that B. juncea (var. P78) is lead and cadmium hyperaccumulator. To reveal molecular mechanisms responsible for metal metabolism, the differentially expressed genes in the roots of Pb-treated plants were investigated by using the microarray chips of Arabidopsis thaliana probes (Affymetrix-The GeneChip ® Arabidopsis ATH1 Genome Array). Out of 183 differentially expressed genes in response to Pb stress, only 20 of the up-regulated and 18 of the down-regulated genes were statistically significant at p < 0.05. Since most of 38 genes differentially expressed under Pb stress were interspecifically very well conserved, we concluded that the use of interspecific hybridization approaches for global gene expression profiling would be limited. The interspecific usability of the probes was further tested by determining the level of conservation between Arabidopsis microarray oligo and Brassica spp. sequences. The microarray results were validated by quantifying the level of expression of six important genes, which are likely to play a role in Pb metabolism, through quantitative RT-PCR. To further pinpoint the possible role of Pb stress-response genes, the expression of these genes at different tissues of the plants after Pb and Cd treatments were measured. In conclusion, the described genes are likely to be associated with Pb and Cd stress metabolism and provide potential targets for the improvement of phytoremediation capacity in plants. [ABSTRACT FROM AUTHOR]