Danijela Arsenov

Phytoextraction of Heavy Metals by Fast-Growing Trees: A Review

Phytoextraction, as the most commonly used technique in phytoremediation, involves the utilization of plant-hyperaccumulators for the absorption pollutants (primarily heavy metals) from the environment, their transport, and concentration in the biomass of harvestable organs. This in situ, cost-effective technology could improve the quality of moderately contaminated lands and waters within realistic time scales. For a successful implementation of phytoextraction, the main prerequisite is to identify native plants which are able to extract (absorb), degrade, or sequester hazardous contaminants from growing media and develop strategies for making hybrids and genetically modified plants which are good candidates for phytoextraction. Because of their rapid growth rate and high biomass yield, their adaptability to different ecological conditions and genetic variability is outstanding. Willows and poplars from the Salicaceae family are valuable resources for the use of phytoremediation. Also, species like the eucalypt, black locust, birch, and paulownia are defined by numerous researchers as good candidates for phytoextraction due to their high metal bioconcentration ability and high yield. There have been numerous studies confirming that species with a role in phytoextraction developed a complex network of homeostatic metabolic mechanisms in order to control metal uptake, accumulation, (re)distribution, and detoxification.

Drought Impact Is Alleviated in Sugar Beets (Beta vulgaris L.) by Foliar Application of Fullerenol Nanoparticles

Over the past few years, significant efforts have been made to decrease the effects of drought stress on plant productivity and quality. We propose that fullerenol nanoparticles (FNPs, molecular formula C60(OH)24) may help alleviate drought stress by serving as an additional intercellular water supply. Specifically, FNPs are able to penetrate plant leaf and root tissues, where they bind water in various cell compartments. This hydroscopic activity suggests that FNPs could be beneficial in plants. The aim of the present study was to analyse the influence of FNPs on sugar beet plants exposed to drought stress. Our results indicate that intracellular water metabolism can be modified by foliar application of FNPs in drought exposed plants. Drought stress induced a significant increase in the compatible osmolyte proline in both the leaves and roots of control plants, but not in FNP treated plants. These results indicate that FNPs could act as intracellular binders of water, creating an additional water reserve, and enabling adaptation to drought stress. Moreover, analysis of plant antioxidant enzyme activities (CAT, APx and GPx), MDA and GSH content indicate that fullerenol foliar application could have some beneficial effect on alleviating oxidative effects of drought stress, depending on the concentration of nanoparticles applied. Although further studies are necessary to elucidate the biochemical impact of FNPs on plants; the present results could directly impact agricultural practice, where available water supplies are often a limiting factor in plant bioproductivity.

Hydroponic screening of black locust families for heavy metal tolerance and accumulation.

abstract Present work examines phytoextraction potential of four black locust families (half-sibs 54, 56, 115, and 135) grown hydroponically. Plants were treated with 6 ppm of cadmium (Cd), 100 ppm of nickel (Ni), and 40 ppm of lead (Pb) added in Hoagland nutrient solution, accompanying with simultaneously applied all three metals. Responses to metals exposure among families were different, ranging from severe to slight reduction of root and shoot biomass production of treated plants. Calculated tolerance indices are indicating tested families as highly tolerant (Ti > 60). Family 135 had the lowest tolerance index, pointing that it was highly susceptible to applied metals. Comparing photosynthetic activities of tested families it has been noticed that they were highly sensitive to stress induced by heavy metals. Net photosynthetic rate of nickel treated plants was the most affected by applied concentration. Cadmium and nickel concentrations in stems and leaves of black locust families exceeded 100 mg Cd kg−1 and 1000 mg Ni kg−1, in both single and multipollution context. On the contrary, accumulation of lead in above ground biomass was highly affected by multipollution treatment. Tf and BCF significantly varied between investigated treatments and families of black locust. Concerning obtained results of heavy metals accumulation and tolerance of black locust families can be concluded that tested families might be a promising tool for phytoextraction purposes, but it takes to be further confirmed in field trials.

Responses of Wheat (Triticum Aestivum L.) and Maize (Zea Mays L.) Plants to Cadmium Toxicity in Relation to Magnesium Nutrition

Abstract The influence of cadmium (Cd) on physiological processes in wheat (Triticum aestivum L.) and maize (Zea mays L.) plants exposed to either optimal mineral nutrition or the absence of magnesium (Mg) as well as the accumulation of cadmium and magnesium in plant organs were studied using the method of water culture in a greenhouse. Cd treatment reduced shoot fresh mass more strongly in Mg-supplied than in Mg-deficient plants. Negative effect of Cd on photosynthetic activity was more pronounced in T. aestivum than in Z. mays plants. Cd treatment decreased leaf chlorophyll and carotenoid concentration in both Z. mays and T. aestivum, irrespective of the Mg supply. Cd was preferentially accumulated in the roots of both species. Catalase activity in T. aestivum leaves and roots was unaffected by Cd and Mg supply. Cd treatment did not affect Fe accumulation in the leaves of either species, while in the roots a considerable increase occurred, irrespective of the Mg nutrition. Higher tolerance of Z. mays and T. aestivum plants to Cd toxicity exposed to Mg deficiency could partly be ascribed to the preservation of Fe nutrition.

Heavy metal contamination of vegetables from green markets in Novi Sad

Vegetables are valuable source of vitamins, minerals and fibers important for healthy human nutrition. However, an increased level of heavy metals in vegetables has been noticed in recent years. This study was conducted with an aim to analyze content of heavy metals, cadmium (Cd), lead (Pb), and chromium (Cr) in 11 vegetable species which are the most common in human diet. Vegetables were collected from three green markets (Limanska, Futoška and Riblja pijaca) in Novi Sad, during September and October, from 2009 to 2011. Heavy metal contents were analyzed in edible parts of tomato, potato, spinach, onion, beetroot, parsley, parsnip, carrot, cauliflower, pepper and broccoli using atomic absorption spectrophotometer (Varian, AAS 240FS). The results showed statistically significant differences in element concentrations among analyzed vegetables. In general, the highest metal pollution was observed in the year of 2011. Spinach was found to contain the highest metals content – 0.89 μg/g for Cd, 5.81 μg/g for Pb, and 3.67 μg/g for Cr. According to Serbian official regulations, 18.18% of all analyzed species exceeded maximum permissible level for Cd, 9.09% for Pb, while for Cr these limits are not defined. Elevated content of heavy metals in vegetables might be related to soil contamination, atmospheric depositions during transportation and marketing. Thus, a continuous monitoring of vegetables on markets should be performed in order to prevent potential health risks to consumers.

Comparative assessment of mineral elements and heavy metals accumulation in vegetable species

The heavy metal (cadmium, lead, nickel, chromium) and mineral element (potassium, phosphorus, calcium, magnesium) levels in edible parts of tomato, potato, spinach, beetroot, parsley, parsnip, carrot, cauliflower, pepper and broccoli were determined by atomic absorption spectrophotometry. Six samples for each species originating from different localities were collected from green markets. The heavy metal concentrations ranged from calcium > phosphorus > magnesium. The highest mean levels of the heavy metals, as well as of potassium, calcium and magnesium, were found in spinach. A large number of samples containing high levels of toxic heavy metals, especially of cadmium and lead, impose the necessity for strict regulative guidelines concerning individual vegetable crops production, harvest, handling and storing, in order to diminish possibility of contamination.

Mine Site Restoration Using Silvicultural Approach

Abstract Tree plantations remain to be a viable option for reclamation of abandoned mine lands, either as a use-only method or as a polishing procedure to be used as an add-up technology at already restored sites. It permits restoration of sites by conserving and improving basic soil biological and physical properties. At the same time it is cost-effective and can even bring some economical return through commercial valorization of obtained biomass and both aesthetic and environmental recovery of the landscape. Its application should be advised more for moderate to low contaminated sites, otherwise the period of restoration could last for decades. This technology is in continuous development providing new possibilities but also some important restrictions in its potential applications. Careful selection of tree species, control of already existing plant and microbial flora, analyzes of soil properties, nutrients, prediction of further development of herbaceous, and microbial communities, along with possibility of amendment and herbicide applications is essential for successful mine site restoration using trees.

Insights and Lessons Learned From the Long-Term Rehabilitation of Abandoned Mine Lands—A Plant Based Approach

Abstract Despite the fact that mining activities cause a significant soil, ground water, and air pollution, detrimental effects mostly occur on natural flora and fauna, leading thereby to the destruction of natural view of land and loss of visual landscape values. Rehabilitation of abandoned mine lands (AMLs) is a very complex process, which in the end must lead to the much more than the presence of vegetation on the site. Quality and functionality of soil system must be confirmed comparing with similar undisturbed ecosystem, mostly by evaluation of several parameters including microbial activity, plant–fungi associations, and soil enzymes activities. Likewise, it is very important to set the revegetation objectives, which should meet the postclosure land use that has been agreed for the specific site. In the end, setting the self-sustaining system might lead to the successful rehabilitation of AMLs.