Employment of associative bacteria for the inoculation of barley plants cultivated in soil contaminated with lead and cadmium

In laboratory experiments, the rhizobacteria Azospirillum lipoferum 137, Arthrobacter mysorens 7, Agrobacterium radiobacter 10, and Flavobacterium sp. L30 were found to have a relatively high resistance to the toxic heavy metals lead and cadmium (except that strain L30 was found to be sensitive to Cd). When introduced by means of seed bacterization, the heavy metal-resistant strains actively colonized the rhizosphere of barley plants cultivated in uncontaminated and contaminated soils. In both pot and field experiments, seed bacterization improved the growth of barley plants and the uptake of nutrient elements from soil contaminated with Pb and Cd. The bacterization also prevented the accumulation of Pb and Cd in barley plants, thereby mitigating the toxic effect of these heavy metals on the plants.     

Heavy Metal Phytotoxicity to Radish (Raphanus sativus L.) in a Digested Sludge-amended Gangetic Alluvium

A limiting factor in land application of sewage sludge is the resultant heavy metal accumulation in soils followed by biomagnification in the food chain, posing a potential hazard to animal and human health. In view of this fact, pot experiments were conducted to evaluate the effect of digested sludge application to soil on phytotoxicity of heavy metals such as Cd, Cr, Ni, and Pb to radish (Raphanus sativus L.) plants. Increasing sludge levels resulted in increased levels of DTPA-extractable heavy metals in the soil. Cadmium was the dominant metal extracted by DTPA followed by Ni, Pb, and Cr. The extractability of metals by DTPA tended to decrease from the first to the second crop. Dry matter yield of radish increased significantly as a function of increasing sludge treatments. Soil application of sludge raised the concentration of one or more heavy metals in plants. Shoots contained higher concentrations of Cd, Cr, and Ni than the roots of radish plants. Shoot concentrations of Cd, Cr, Ni, and Pb were within the tolerance levels of this crop at all rates of sludge application. Shoot as well as root concentration of Cd was above 0.5 mg kg^?1, considered toxic for human and animal consumption. The levels of DTPA-extractable Cd and Ni were less correlated while those of Cr and Pb were more correlated with their respective shoot and root contents. The results emphasize that accumulation of potentially toxic heavy metals in soil and their build-up in vegetable crops should not be ignored when sludge is applied as an amendment to land.     

Soil Nitrogen Fertilization Effects on Phytoextraction of Cadmium and Lead by Tobacco (Nicotiana tabacum L.)

A greenhouse experiment using 24 plastic pots filled with 6 kg of Pb- and Cd-contaminated soil was carried out. In all 24 pots, soils were heavy metal–contaminated with 10 mg Cd kg^?1 soil and 500 mg of Pb kg^?1 soil by using CdCl and PbNO₃. Two-month-old tobacco (Nicotiana tabacum L.) plants were used to extract these heavy metals. Results showed that tobacco is able to remove Cd and Pb from contaminated soils and concentrate them in its harvestable part, that is, it could be very useful in phytoextraction of these heavy metals. Increasing additions of ammonium nitrate to soil (50, 100, and 150 mg N kg^?1 soil) significantly (p ≤ .05) increased aboveground Cd and Pb accumulation during a 50-day experimental period, whereas increasing additions of urea to soil (50 and 100 mg N kg^?1 soil) did not show these effects at the same significance levels. Increasing additions of ammonium nitrate to soil shows as dry matter increases, both accumulated Cd and accumulated Pb also increase when tobacco plants are growing under Pb- and Cd-contaminated soil conditions. Higher Pb concentrations depress Cd/Pb ratios for concentrations and accumulations, suggesting that Pb negatively affects Cd concentration and/or accumulation.     

EFFECTS OF INOCULATION WITH ARBUSCULAR MYCORRHIZAL FUNGI ON MAIZE GROWN IN MULTI-METAL CONTAMINATED SOILS

Pot culture experiments were established to determine the effects of colonization by arbuscular mycorrhizal fungi (AMF) (Glomus mosseae and G. sp) on maize (Zea mays L.) grown in Pb, Zn, and Cd complex contaminated soils. AMF and non-AMF inoculated maize were grown in sterilized substrates and subjected to different soil heavy metal (Pb, Zn, Cd) concentrations. The root and shoot biomasses of inoculated maize were significantly higher than those of non-inoculated maize. Pb, Zn, and Cd concentrations in roots were significantly higher than those in shoots in both the inoculated and non-inoculated maize, indicating the heavy metals mostly accumulated in the roots of maize. The translocation rates of Pb, Zn, and Cd from roots to shoots were not significantly difference between inoculated and non-inoculated maize. However, at high soil heavy metal concentrations, Pb, Zn, and Cd in the shoots and Pb in the roots of inoculated maize were significantly reduced by about 50% compared to the non-inoculated maize. These results indicated that AMF could promote maize growth and decrease the uptake of these heavy metals at higher soil concentrations, thus protecting their hosts from the toxicity of heavy metals in Pb, Zn, and Cd complex contaminated soils.     

Distribution of Cadmium,Lead, Nickel,and Strontium in Imbibing Maize Caryopses

Seed germination is tolerant to heavy metals apparently because the seed coat is impermeable to metal ions. However, it is not clear whether the seed coat is a universal barrier for all metals. In addition, depending on their physical and chemical properties, a distribution of various metals may differ within an imbibing caryopsis, and therefore they produce dissimilar effects on seed germination. The toxic effects of Cd(NO₃)₂, Pb(NO₃)₂, Ni(NO₃)₂, and Sr(NO₃)₂ were estimated from the germination rates of maize (Zea mays L.) caryopses following two-day incubation with these salts. The distribution of heavy metals and Sr was studied by histochemical methods based on the formation of colored complexes with dithizone (Cd and Pb), dimethylglyoxyme (Ni), and sodium rhodizonate (Sr). Although the metals under study did not affect maize radicle protrusion, they inhibited seed germination in the following order: Cd > Ni ≈ Pb > Sr. Cd and Pb accumulated mainly in the seed coat cells, but Sr and Ni in the embryo cells and in the cells of endosperm (Sr) and scutellum (Ni). Although Cd was found only in the seed coat, it was the strongest inhibitor of seed germination. Apparently, due to high toxicity, Cd exerted its inhibitory effect at the concentrations too low for histochemical assay. In spite of easy translocation across the seed coat of imbibing caryopses, Sr did not considerably inhibit radicle protrusion and seed germination, apparently because of its low toxicity and predominant localization in the apoplast of embryo and endosperm cells.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 635–640.Original Russian Text Copyright © 2005 by Seregin, Kozhevnikova.     

Heavy metals contamination and accumulation in submerged macrophytes in an urban river in China

Deteriorating urban water quality has attracted considerable attention in China. We investigated the contamination levels and distribution of heavy metals (As, Cd, Cu, Ni, Pb, and Zn) in Yuxi River water and sediments, and assessed the heavy metal accumulation capability of five species of submerged macrophytes: Vallisneria natans (Lour.) Hara, Potamogeton pectinatus L., Hydrilla verticillata (L. f.) Royle, Myriophyllum spicatum L., and Potamogeton crispus L. Samples were collected from upstream and downstream locations in different season. The results showed that the levels of heavy metals in the downstream areas were higher than in the upstream areas. Heavy metal concentrations in the river water during the dry seasons were higher than those during the rainy seasons, and the opposite results appeared in sediments and submerged macrophytes. In general, the river was slightly contaminated by heavy metals, and the concentrations of Pb and Ni in this river should serve as a warning, while Cd and Zn pollution in the sediments desperately needs to be removed. Furthermore, Potamogeton pectinatus L. showed a higher accumulation capacity for these metals among the five native submerged macrophytes and could be defined as a hyperaccumulator for Cd. Therefore, the potential use of native aquatic plants in contaminated rivers is worth further exploration.     

Assessment of heavy metal induced stress responses in pea (Pisum sativum L.)

Exposure of plants to heavy metals severely affects their growth and physiological processes. Nevertheless, different plants show variable responses to different heavy metals, generally in a concentration-dependent manner. In this study, phytotoxic effects of cadmium (Cd), cobalt (Co) and lead (Pb) applied as chlorides at concentration 500, 750, 1000 and 1250 ppm were evaluated on seed germination, early seedling growth and dry biomass of pea (Pisum sativum L.). A lower concentration (500 ppm) of Pb promoted seed germination but declined other growth parameters. Higher concentration had a phytotoxic influence on the pea. Cd and Co severely affected germination and seedling growth of pea resulting in complete failure of germination and seedling growth at higher metal concentration. Tolerance index (TI) calculated for seed germination and dry biomass indicated that tested plant had zero tolerance to 1250 ppm of Cd as well as 750 ppm and higher concentrations of Co. The order of heavy metals for their phytotoxic effects was Co > Cd > Pb. The study suggests that P. sativum is relatively tolerant to Pb but highly sensitive to Co and Cd.     

EDTA enhanced heavy metal phytoextraction: metal accumulation,leaching and toxicity

Synthetic chelates such as ethylene diamine tetraacetic acid (EDTA) have been shown to enhance phytoextraction of some heavy metals from contaminated soil. In a soil column study, we examined the effect of EDTA on the uptake of Pb, Zn and Cd by Chinese cabbage (Brassica rapa), mobilization and leaching of heavy metals and the toxicity effects of EDTA additions on plants. The most effective was a single dose of 10 mmol EDTA kg^–1 soil where we detected Pb, Zn and Cd concentrations that were 104.6, 3.2 and 2.3-times higher in the aboveground plant biomass compared to the control treatments. The same EDTA addition decreased the concentration of Pb, Zn and Cd in roots of tested plants by 41, 71 and 69%, respectively compared to concentrations in the roots of control plants. In columns treated with 10 mmol kg^–1 EDTA, up to 37.9, 10.4 and 56.3% of initial total Pb, Zn and Cd in soil were leached down the soil profile, suggesting high solubility of heavy metals-EDTA complexes. EDTA treatment had a strong phytotoxic effect on the red clover (Trifolium pratense) in bioassay experiment. Moreover, the high dose EDTA additions inhibited the development of arbuscular mycorrhiza. The results of phospholipid fatty acid analyses indicated toxic effects of EDTA on soil fungi and increased environmental stress of soil microfauna.     

Lead,cadmium and nickel removal efficiency of white-rot fungus Phlebia brevispora

Widespread of heavy metals contamination has led to several environmental problems. Some biological methods to remove heavy metals from contaminated wastewater are being widely explored. In the present study, the efficiency of a white-rot fungus, Phlebia brevispora to remove different metals (Pb, Cd and Ni) has been evaluated. Atomic absorption spectroscopy of treated and untreated metal containing water revealed that all the metals were efficiently removed by the fungus. Among all the used metals, cadmium was the most toxic metal for fungal growth. Phlebia brevispora removed maximum Pb (97·5%) from 100 mmol l⁻¹ Pb solution, which was closely followed by Cd (91·6%) and Ni (72·7%). Scanning electron microscopic images revealed that the presence of metal altered the morphology and fine texture of fungal hyphae. However, the attachment of metal on mycelia surface was not observed during energy-dispersive X-ray analysis, which points towards the intracellular compartmentation of metals in vacuoles. Thus, the study demonstrated an application of P. brevispora for efficient removal of Pb, Cd and Ni from the metal contaminated water, which can further be applied for bioremediation of heavy metals present in the industrial effluent.     

Pb和Cd对森林土壤细菌功能多样性及群落结构的影响

重金属的毒性系数（The Toxic Factor,TF）是评价重金属潜在生态风险指数（potential ecological risk index,RI）的关键参数。为了探究基于Hakanson提出的TF值是否适用于重金属对土壤微生物的生态风险评估,以TF值为5和30的铅（Pb）和镉（Cd）构建土壤微宇宙试验,构建不同的RI水平（100、200和400）,通过Biolog-ECO板和高通量测序技术分析了Pb和Cd分别对细菌功能多样性及群落结构的影响。结果表明,对照处理（CK）的细菌丰度、功能多样性（Shannon指数,Simpson指数和McIntosh指数）和基因多样性（ACE和Chao1指数）均大于Pb、Cd污染的土壤,随着RI水平的升高,Pb和Cd污染土壤中细菌的丰度、功能多样性（Shannon指数和McIntosh指数）和基因多样性（Chao1指数和ACE指数）呈下降趋势。相同RI水平下,Pb污染土壤中细菌群落的丰度、平均颜色变化率（AWCD）、功能多样性指数、OTUs数和基因多样性指数均显著大于Cd污染（P<0.05）;6大类碳源利用率及主成分（PCA）分析表明,Pb污染土壤中细菌对糖类和羧酸的利用率均显著大于Cd污染（P<0.05）,在不同RI水平和重金属比例下,碳源利用模式而有所不同。同一RI水平下,相对于Pb污染,Cd污染土壤中变形菌门的相对丰度较为丰富,而绿弯菌门的相对丰度稀少;Pb和Cd污染土壤中慢生根瘤菌属、鞘脂单胞菌属、链霉菌属和norank_f__Roseiflexaceae等不同属细菌相对丰度表现出差异性。上述结果表明Hakanson提出的TF值并不适用于评估重金属Pb和Cd对土壤微生物的潜在生态风险。     

Bioaccumulation of mercury,arsenic, cadmium,and lead in plants grown on coal mine soil

Mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) are the major toxic metals released by coal mining activities in the surrounding environment. These metals get accumulated in the soils. The plants grown on the contaminated soil uptake these toxic metals in their roots and aerial parts. This study monitored the bioaccumulation of Hg and other three toxic metals in coal mine soil. The pot study of Hg accumulation in Brassica juncea showed that the extent of Hg uptake by roots and shoots of the plants grown on was high in the mature plant and Hg content in root was higher than the shoot. In the soil of unreclaimed overburden (OB) dump, the toxic metal content was higher than that of reclaimed OB dump which posed high ecological risk in the soil of unreclaimed OB dump. Bioaccumulation coefficient (BAC) value showed that Hg was not accumulated in the leaves of Dalbergia sissoo L., Gmelina arborea, Peltaphorum inerme L., Cassia seamea L, and Acacia mangium L grown on coal mine soil.     

Heavy metals accumulation and distribution in durum wheat and barley grown in contaminated soils under Mediterranean field conditions

Abstract

In the framework of a phytoremediation project in the Apulia region (Italy) a field experiment was carried out in multi-metal contaminated soils. The accumulation and distribution of metals in different plant parts of durum wheat and barley were studied. Further, the application of Bacillus licheniformis strain BLMB1 to soil was evaluated as a means to enhance metal accumulation in plants. The translocation and the bioconcentration factors indicated that wheat and barley do not act as metal accumulators in the field conditions tested, thus phytoextraction by these species would not be recommended as a soil remediation alternative. Application of B. licheniformis improved the accumulation of all metals in roots of wheat and barley, and increased Cd, Cr, and Pb contents in the shoots of barley. Low health risk for humans and animals was evaluated to exist if straw and grain from both cereal crops grown in these contaminated sites are consumed.     

Assessment of heavy metals accumulation by spontaneous vegetation: Screening for new accumulator plant species grown in Kettara mine-Marrakech,Southern Morocco

The present paper aims to perform a screening of native plants growing in Kettara mine-Marrakech (Southern Morocco) for its phytoremediation. Plants and soil samples were collected and analyzed for Pb, Zn, Cu and Cd concentrations at several sites in the mine. The results showed that the soil in the vicinity of Kettara mine is deficient in major elements and contain toxic levels of metals. Spontaneously growing native plants were botanically identified and then classified into 21 species and 14 families. Significant difference was observed among the average concentrations of four heavy metals (Pb, Zn, Cu and Cd) in plants (p ≤ 0.05). Six plants of 21 species namely Hammada scoparia (Pomel) Iljin, Hirschfeldia incana (L.) Lagreze-Fossat, Lamarckia aurea (L.) Moench, Calendula algeriensis Boiss. & Reuter, Aizoon hispanicum L. and Melilotus sulcata Desf. were considered as the best-performing specimens due to their high ability to accumulate multiple metals in their shoots and roots without sustaining toxicity. This was confirmed by the transfer factors generally higher than 1. Using the most common criteria to classify the hyperaccumulator plants, these species can be classified as new accumulator plants of many heavy metals and be potentially used as remediation tools of metal-contaminated sites.     

Effect of EDTA and Tannic Acid on the Removal of Cd,Ni, Pb and Cu from Artificially Contaminated Soil by Althaea rosea Cavan

In this study an ornamental plant of Althaea rosea Cavan was investigated for its potential use in the removal of Cd, Ni, Pb and Cu from an artificially contaminated soil. Effect of two different chelating agents on the removal has also been studied by using EDTA (ethylenediaminetetracetic acid) and TA (tannic acid). Both EDTA and TA have led to higher heavy metal concentration in shoots and leaves compared to control plants. However EDTA is generally known as an effective agent in metal solubilisation of soil, in this study, TA was found more effective to induce metal accumulation in Althaea rosea Cavan under the studied conditions. In addition to this, EDTA is toxic to some species and restraining the growth of the plants. The higher BCF (Bio Concentration Factor) and TF (Translocation Factor) values obtained from stems and leaves by the effects of the chemical enhancers (EDTA and TA) show that Althaea rosea Cavan is a hyper accumulator for the studied metals and may be cultivated to clean the contaminated soils.     

佛山城市典型森林群落土壤重金属分布、流通及枯落物富集特征

富集重金属的枯落物分解可能提高重金属暴露率,增加人体接触健康风险。为了解南方城市土壤重金属在森林生态系统中的分布及流转情况,通过调查研究了佛山市8个典型森林群落土壤及枯落物重金属含量,分析了各森林群落枯落物对不同重金属的富集效应及重金属随枯落物回归土壤流通量。结果表明：1）城市森林各土壤重金属含量在不同典型群落间差异显著（P<0.05）,差异最大为Pb、Cr、Zn,As、Cu、Ni次之,Hg、Cd最小;土层深度（0-20,20-40,40-60 cm）对重金属含量影响显著（P<0.05）,差异最大为Cd、Hg,其次为As、Cu,最小为Zn、Ni、Pb、Cr。整体上,Cd、Hg、As、Pb、Zn在0-20 cm最高,表层富集特征明显,Cr和Ni在40-60 cm最高。2）8个森林群落中阴香-白楸-醉香含笑群落（CMMC）枯落物对8种重金属的综合富集系数（TBCF,66.76）最高,其中以Cd的富集效果最突出,富集系数为44.45,且对Pb、Cu、Zn也相对富集;最低的为黧蒴锥-香椿-樟树群落（CTCC）,综合富集系数（TBCF）为8.09,仅对Cd、Cr、Cu相对富集,对其余重金属富集效应不明显。3）相关分析显示,群落重金属枯落物流通量与0-60 cm土壤重金属平均含量（Cr和Ni除外）无显著相关性。本研究对城市森林建设管理及筛选重金属富集植物及群落具有较强理论及实践意义。     

Phytoremediation of heavy metal contaminated soil potential by woody plants on Tonglushan ancient copper spoil heap in China

Fast-growing metal-accumulating woody plants are considered potential candidates for phytoremediation of metals. Tonglushan mining, one of the biggest Cu production bases in China, presents an important source of the pollution of environment. The sample was collected at Tonglushan ancient copper spoil heap. The aims were to measure the content of heavy metal in the soil and woody plants and to elucidate the phytoremediation potential of the plants. The result showed that soil Cu, Cd and Pb were the main contamination, the mean contents of which were 3166.73 mg/kg, 3.66 mg/kg and 137.06 mg/kg respectively, which belonged to severe contamination. Fourteen species from 14 genera of 13 families were collected and investigated; except for Ligutrum lucidum, the other 13 woody plants species were newly recorded in this area. In addition, to assess the ability of metal accumulation of these trees, we proposed accumulation index. Data suggested that Platanus × acerilolia, Broussonetia papyrifera, Ligutrum lucidum, Viburnum awabuki, Firmiana simplex, Robina pseudoacacia, Melia azedarach and Osmanthus fragrans exhibited high accumulated capacity and strong tolerance to heavy metals. Therefore, Platanus × acerilolia and Broussonetia papyrifera can be planted in Pb contaminated areas; Viburnum awabuki, Firmiana simplex, Robina pseudoacacia and Melia azedarach are the suitable trees for Cd contaminated areas; Viburnum awabuki, Melia azedarach, Ligutrum lucidum, Firmiana simplex, Osmanthus fragrans and Robina pseudoacacia are appropriate to Cu, Pb and Cd multi-metal contaminated areas.     

Removal of Heavy Metals from Soil Polluted with Effluents from a Paint Industry Using Helianthus annuus L. and Tithonia diversifolia (Hemsl.) as Influenced by Fertilizer Applications

Contamination of soils by effluents from industries is on the increase. There is the possibility of remediating these contaminated soils through the use of certain plants. This work investigated the remediating ability of Helianthus annuus and Tithonia diversifolia on the soil polluted with effluents from a paint industry in Ibadan, Nigeria. The experiment consisted of three treatments (H. annuus, T. diversifolia, and control) each replicated three times in a factorial combination of four different fertility managements, viz mineral fertilizer (MF); Grade A organomineral fertilizer (OMF); control₁, plants without fertilizer application; and control₂, where no fertilizer and no crop was planted using randomized complete block design. A total of 12 plots of 2 × 4 m² each per phytoplant were obtained. Each plot was planted with the viable seeds of the phytoplant at a spacing of 60 × 30 cm² and at the seed rate of four seeds per hole. The seedlings were thinned to two stands per hole 2 weeks after planting (WAP) and also weeded two times (2 and 5 WAP). After in situ second successive cultivation, percentage removal of heavy metals by Helianthus annuus with MF and OMF, respectively, were Cu 32.5 and 41.6; Pb 30.3 and 42.8; and Cd 44.5 and 56.7. Tithonia diversifolia, similarly, removed, respectively, Cu 16.9 and 23.4; Pb 36.9 and 43.7; and Cd 20.1 and 35.1. Lower percentages were removed in the controls where no fertilizer was applied. In the shoot of H. annuus with OMF, significantly (p< .05) higher values of 0.27, 1.72, and 0.11 mg kg^?1 of Cu, Pb, and Cd, respectively, were removed and stored at second cultivation as against 0.21, 3.39 and 0.08 mg kg^?1 in the shoot of T diversifolia. Lower values of Cu, Pb, and Cd were removed with MF, and also at first cultivation with OMF and MF. This study therefore recommends the use of sunflower plants, whether hybrids or wild-types along with the application of OMF for the effective remediation of soils contaminated with heavy metals, particularly in tropical climate.     

Bioefficacy of cadmium and lead on cotton leafworm Spodoptera littoralis (Lepidoptera: Noctuidae) larvae

The sensitivity of Spodoptera littoralis second and fourth instar larvae to the heavy metals cadmium (Cd) and lead (Pb) was investigated under laboratory conditions. Both Cd and Pb, even, at very low concentrations, had relatively high toxic effects on S. littoralis larvae. Cd was more toxic to S. littoralis larvae than Pb. In addition, the mean percentage feeding deterrence (FDI%) of Cd and Pb was concentration-dependent. The nutritional indices (consumption index, growth rate, efficiency of converted ingested and digested food, and approximate digestibility) of S. littoralis second and fourth instar larvae were more affected in Cd-treatments compared with those of Pb-treatments. Therefore, the presence of such heavy metals in the environment would exert an adverse impact on S. littoralis larvae and their development.     

Effects of Cu,Pb and Zn on two Potamogeton species grown under field conditions

Two common macrophyte species, Potamogeton perfoliatus L. and Potamogeton pectinatus L. were grown for 12 weeks at shallow depths in sediments contaminated with 1250 or 2500 g Pb or Cu and/or Zn (gDW sediment)^-1. Control experiments were run at background levels of 4, 13, and 38 g Pb, Cu and Zn (gDW sediment)^-1, respectively. Effects of heavy metals on biomass production and metal uptake and distribution in plants are presented in relation to total amount and plant-available fraction of metals in the sediment.All three studied metals gave reduced biomass production, and the toxicity of the metals decreased in the order Zn>Cu>Pb. The root/shoot biomass ratio increased for P. pectinatus, but decreased for P. perfoliatus with metal treatment. The content of any single metal was higher in shoots than in roots of plants grown on sediments not contaminated with that specific metal, but addition of that metal increased the proportion in roots. The uptake by plants of any of the heavy metals increased with increased metal addition. The magnitude of the plant-available fraction of metals of untreated sediment was Zn>Cu>Pb, and increased in contaminated sediments. Addition of Cu decreased both the plant-available fraction and the total concentration of Zn in the sediment, while increased the uptake of Zn by the plants. The opposite was found for Cu when Zn was added. P. pectinatus accumulated about twice as much Cu as P. perfoliatus. On the other hand, the concentration of Pb was higher in P. perfoliatus than in P. pectinatus, and was negligible in P. pectinatus when cultivated in untreated sediments.     

Effect of Compost and Biochar on Heavy Metals Phytostabilization by the Halophytic Plant Old Man Saltbush [Atriplex Nummularia Lindl]

Remediation of soils is vital to mitigate the negative effects of heavy metals in ecosystems. There is little information available about the metals’ phytostabilization potential of old man saltbush plants [Atriplex nummularia]. A pot experiment in a randomized complete block design was conducted to study the accumulation of heavy metals by old man saltbush plants, as affected by the application of compost and biochar. The cultivation of A. nummularia is an effective tool in immobilizing metals in the contaminated soils. The cultivation of metal-contaminated soil with A. nummularia reduced the availability of Zn, Cu, Cd, and Pb by 20%, 4%, 21%, and 28%, respectively, in comparison to the non-cultivated soil. Zn, Cu, Cd, and Pb concentrations in the aboveground parts of old man saltbush plants were 70–100, 50–80, 4–5, and 50–90 mg/kg of dry biomass. The higher Zn, Cu, Cd, and Pb concentrations were accumulated in the roots, and the lower concentrations were transferred to the shoots of old man saltbush plants. Compost reduced the concentration of Zn, Cu, Cd, and Pb in the shoots by 10%, 19%, 20%, and 6%, respectively, compared to the control soil. Biochar reduced the concentrations of Zn, Cu, and Pb in the shoots by 30%, 38%, and 44%, respectively, compared to the control. Compost had a lower effect in reducing the metals uptake as biochar. Biochar reduced the uptake of Zn, Cu, and Pb in the shoots of the tested plant by 22%, 23%, and 41%, respectively, in comparison to compost. Based on the obtained results, old man saltbush has good characteristics to be a promising candidate for phytostabilization strategies of metal-contaminated soils. Moreover, biochar is a good tool to enhance metals’ phytostablization.