Phytoaccumulation

It is a common practice for farmers in India to use soils in municipal waste dump sites as fertile soil for the cultivation of a variety of leafy vegetables and the soils are also used as ‘compost’ by farmers without regards for the probable health hazards the heavy metal contents of such soils may purpose. This was the case of formers using the deserted dumpsite soil at Baxibandh municipal waste for their livelihood. It was concern that prompted the determination of heavy metals in the soil and control planting on Sheila Dhar Institute of Soil Science farm and that of the Makoy (Solenum nigrum L.) plant used to inactivate metals in dump soil. The concentration of heavy metal in the edible part of Spinach vegetable from the dump site and control: Pb (12.4-1.2 mg kg-1); Cd (0.65-0.26 mg kg-1) Zn (44.8-24.6 mg kg-1); Cu (24.2-11.8 mg kg-1) and Cr (0.08-0.04mg kg-1), respectively. The concentration of heavy metals in Makoy (Solenumnigrum L.) plant is Pb (45.6mg kg-1); Cd (1.44 mg kg-1) Zn (92.6mg kg-1); Cu (28.8 mg kg-1) and Cr (0.81mg kg-1) in Buxibandh dumpsite soil. The levels of heavy metals in the dumpsite soil and the soil after harvesting the makoy (Solenum nigrum L.) plant are Pb (116.4 -50.64mg kg-1); Cd (3.26-1.86 mg kg-1) Cr (2.24-1.72mg kg-1); Zn (184.4-108.6 mg kg-1) and Cu (58.2-24.24mg kg-1), respectively. The spinach species from the dump soil accumulates more heavy metals than that of the control. The level of heavy metals in dump soil decreases rapidly after harvesting the makoy (Solenum nigrum L.) plant.

Najas graminea Delile, known as ricefield water nymph is a species of underwater plant found in freshwater habitats, especially in calm or slow-moving waters such as ponds and rice fields. This opportunistic aquatic plant is becoming more and more common, including coastal lakes in Southeastern Europe. Individuals studied aquariums with filtered freshwater supplemented with different concentrations of CuSO4. Water samples were analyzed for pH, dissolved oxygen and electrical conductivity. Copper content was determined by atomic absorption spectrometry, flame technique. Photosynthetic pigments concentrations and final biomass were alo determined, as indicators of plant health. The results obtained in terms of oxygen, assimilation pigments concentration and dry biomass, indicates the existence of moderate stress induced by copper phytotoxicity, but without direct effects on plant biomass, indicating tolerance to selected copper concentrations. Following this experiment, it can be stated that the potential use of Najas graminea Delile species as a bioaccumulating aquatic plant requires further investigations.

The natural bioaccumulation potential of some transitional metals, such us copper, zinc and manganese, was assessed in eight herbaceous species commonly growing on the Black Sea coastal area of Constanta County, Romania, Argusia sibirica (L.) Dandy, Echium italicum L., Atriplex sagittata Borkh., Conium maculatum L., Malva sylvestris L., Onopordum acanthium L., Plantago lanceolata L. and Rumex crispus L. Aboveground plants organs and afferent soil samples were digested and analysed by Atomic Absorption Spectrometry method, for selected metal concentration values, using HR-CS AAS ContrAA 700, Analytik Jena AG, Germany, acetylene flame technique, at the specific wavelengths, 324 nm (Cu), 213 nm (Zn) and 279 nm (Mn). To assess the phytoaccumulation potential, the Biological Accumulation Coefficients (BAC) were calculated. While, A. sibirica, M. sylvestris (for Cu) and R. crispus (Cu and Zn) had constantly above average concentrations, none of the selected species were hyper accumulators, considering the established minimum concentration thresholds. All studied herbaceous species were manganese excluders. A. sibirica, A. sagittata, O. acanthium, R. crispus, P. lanceolata had average BAC > 1 for Cu (constantly high in A. sibirica and A. sagit-tata). A. sibirica, E. italicum, P. lanceolata showed BAC > 1 for Zn (constantly, in A. sibirica). The obtained results emphasise an increased potential for phytostabilisation of copper and zinc rich soils and open the way for heavy metals phytoextraction studies on the Black Sea coastal area.

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),

Flavoparmelia caperata L. Hale (common greenshield lichen) is an Ascomycete, foliose lichen usually growing on tree bark in most mesophytic-forested habitats in Romania. Lichen samples were collected from three stations in Romania (Craiova, Timișoara, Hoia-Baciu Forest, Cluj) and extracted in 96% ethanol. Both dry lichen tissue powder and extracts were analyzed by UV-Vis spectrophotometry for determining photosynthetic pigment concentrations (chlorophylls a and b and total carotenoids). Dry tissue samples had chlorophyll a concentrations of 95.12-109.59 mg/kg DW, chlorophyll b concentrations of 88.53-110.98 mg/kg and total carotenoids 88.89-102.85 mg/kg. Alcoholic extracts of fresh lichen tissue showed an extreme variability, with 715.97-10331.50 mg/kg chlorophyll a, 527.77-8124.20 mg/kg chlorophyll b, 1125.72-8714.90 mg/kg carotenoids pigments, with the highest values in samples from Craiova. A lower variability was observed in flavonoid contents, with 461.78-966.02 mg/kg DW in dry powder and 815.56-2734.135 mg/kg in ethanolic extracts. Extracts of lichens from Craiova had a decreased content of total flavonoids compared with the other two lichens ethanol extracts.