Metal storage in reeds from an acid mine drainage contaminated field

Phragmites australis has been used to treat acid mine drainage (AMD)-contaminated soil. However, the mechanism about metal translocation in reeds was not widely reported. This study investigated metal (Fe, Al, and Mn) storage location in reeds grown in five different sampling sites of an AMD field. As expected, the more metals in soil, the more metals entered the belowground organs of plants. Reeds grown in soils with the highest levels of metals accumulated 0.16 ± 0.04 mg/g Mn, 16.29 ± 4.15 mg/g Fe, and 1.31 ± 0.22 mg/g Al in roots. Most of the iron was sequestered in the roots, while Al was transferred to the shoots. Histological staining found that most of the iron was sequestered in the exodermis, while Al extended the endodermis of roots. Al even entered the stele of roots grown in soil with higher Al levels. The epidermis, cortex, and central cylinder of rhizomes were the main tissues for Fe and Al storage. The more metals in rhizomes, the stronger intensity of the staining was observed around the vascular systems of rhizomes. No structural difference was observed among reeds collected from different sites. Further studies may be needed to enhance the transfer of metals in reeds and increase the phytoremediation efficiency.     

Evaluation of the Phytoextraction Potential at an Acid-Mine-Drainage-Impacted Site

Four plant species were found naturally growing at an acid mine drainage (AMD)-impacted site contaminated with 9430 mg kg^?1Al, 76,000 Fe mg kg^?1, ～150 mg kg^?1Mn, and 420 mg kg^?1 Mg: soybeans (Glycine max), cattails (Typha latifolia), goldenrods (Solidago sp.), and reed grass (Phragmites australis). The metal uptake selectivity was Fe?Mg～Mn>Al for cattails, Mg>Mn>Fe>Al for goldenrods, and Fe?Al>Mg>Mn for reeds. When metal translocation factors, shoot concentrations, and toxicity of the contaminants were correlated, cattails and reeds were more effective at the site than the soybeans or goldenrods. Cattails had a translocation factor of 3.71 for Al, 3.3 for Mg, 1.98 for Mn, and only 0.2 for Fe. The translocation factors for reeds were much higher for Fe (8.64) and Al (7.3). Cattails (1.11 mg Al g^?1 shoot) and reeds (3.4 mg g^?1 g shoot) were both able to hyperaccumulate Al. Additional research is warranted to ascertain if the uptake efficiencies can be enhanced by the use of chelators.     

Applicability of Heavy-Metal Phytoextraction in United Arab Emirates: An Investigation of Candidate Species

Phytoremediation of contaminated calcareous desert land in the United Arab Emirates has been investigated. Soils from 12 northern UAE sites, suspected of metal contamination, were acid-extracted and analyzed by ICP-OES for Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Twenty-two plants naturally growing at contaminated sites were sampled and analyzed for their uptake of Co, Cr, Cu, Mn, Ni, Pb, and Zn and eight commercially available plants, grown under controlled conditions, were also studied for their phytoextraction capabilities. The concentration of available Cr was found to be 1300 ± 150 mg/kg in the soil of the Ajman Industrial Zone and 80 ± 10 mg/kg of Pb was found at Bithna. Among the plants investigated, Portulaca oleracea and Iresine herbstii showed potential for Cr(VI) and Pb(II) accumulation, respectively, with bioconcentration factors (BCF) greater than unity. Atriplex halimus accumulated Co(II), Cr(III), and Cu(II) each with a BCF > 1.     

Portulaca grandiflora as green roof vegetation: Plant growth and phytoremediation experiments

Finding appropriate rooftop vegetation may improve the quality of runoff from green roofs. Portulaca grandiflora was examined as possible vegetation for green roofs. Green roof substrate was found to have low bulk density (360.7 kg/m³) and high water-holding capacity (49.4%), air-filled porosity (21.1%), and hydraulic conductivity (5270 mm/hour). The optimal substrate also supported the growth of P. grandiflora with biomass multiplication of 450.3% and relative growth rate of 0.038. Phytoextraction potential of P. grandiflora was evaluated using metal-spiked green roof substrate as a function of time and spiked substrate metal concentration. It was identified that P. grandiflora accumulated all metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, and Zn) from metal-spiked green roof substrate. At the end of 40 days, P. grandiflora accumulated 811 ± 26.7, 87.2 ± 3.59, 416 ± 15.8, 459 ± 15.6, 746 ± 20.9, 357 ± 18.5, 565 ± 6.8, and 596 ± 24.4 mg/kg of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn, respectively. Results also indicated that spiked substrate metal concentration strongly influenced metal accumulation property of P. grandiflora with metal uptake increased and accumulation factor decreased with increase in substrate metal concentration. P. grandiflora also showed potential to translocate all the examined metals with translocation factor greater than 1 for Al, Cu, Fe, and Zn, indicating hyperaccumulation property.     

Does radial oxygen loss and iron plaque formation on roots alter Cd and Pb uptake and distribution in rice plant tissues?

Background and Aims

Metal (e.g. Cd and Pb) pollution in agricultural soils and crops have aroused considerable attention in recent years. This study aimed to evaluate the effects of ROL and Fe plaque on Cd and Pb accumulation and distribution in the rice plant.

Methods

A rhizobag experiment was employed to investigate the correlations among radial oxygen loss (ROL), Fe plaque formation and uptake and distribution of Cd and Pb in 25 rice cultivars.

Results

Large differences between the cultivars were found in rates of ROL (1.55 to 6.88 mmol O₂ kg^?1 root d.w. h^?1), Fe plaque formation (Fe: 6,117–48,167 mg kg^?1; Mn: 127–1,089 mg kg^?1), heavy metals in shoot (Cd: 0.13–0.35 mg kg^?1; Pb: 4.8–8.1 mg kg^?1) and root tissues (Cd: 1.1–3.5 mg kg^?1; Pb: 45–199 mg kg^?1), and in Fe plaque (Cd: 0.54–2.6 mg kg^?1; Pb: 102–708 mg kg^?1). Rates of ROL were positively correlated with Fe plaque formation and metal deposition on root surfaces, but negatively correlated with metal transfer factors of root/plaque and distributions in shoot and root tissues.

Conclusions

ROL-induced Fe plaque promotes metal deposition on to root surfaces, leading to a limitation of Cd and Pb transfer and distribution in rice plant tissues.     

Are Metals Accumulated in Human Hair Affected by Naturally Occurring Asbestos Fiber Contamination? A Case Study from a Rural Area of China

Little is known about the link between metals accumulated in human and asbestos fiber contamination in the environment. Therefore, hair samples of 368 subjects (128 males and 240 females) from a rural area contaminated by crocidolite asbestos fibers were collected to investigate the distributions of 17 metals accumulated in human. The results showed that the mean concentrations of As, Al, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Na, Ni, Pb, Sr, and Zn in hair of the total subjects were 0.23, 23.36, 4.33, 0.11, 0.05, 0.70, 10.53, 29.74, 0.37, 241.57, 3.52, 0.08, 153.21, 0.72, 4.26, 10.96, and 113.35 mg/kg, respectively. Moreover, approximately 86.14, 52.17, 73.91, 85.05, 80.98, 74.46, and 53.80 % of the hair samples of the total subjects contained much higher concentrations of Al, Ba, Fe, Mg, Mn, Na, and Sr compared with the highest reference values, respectively. The mean concentrations of the determined metals (except for As, Co, Cr, Hg, and Mo) significantly varied among different age groups for both male and females. The results of correlation analysis and cluster analysis revealed that strong correlations were found between Al, Fe, Zn, Mg, and Na accumulated in human from the study area. These might suggest that Al, Ba, Fe, Mg, Mn, Na, and Sr were significantly derived from contamination of crocidolite asbestos fibers. Zn, Mg, and Na might also originate from diet. However, Cd, Mo, Co, As, Cr, Hg, Ni, Mn, Pb, and Ba accumulated in human seemed to be mainly derived from soil. It can be concluded that metals accumulated in human hair have a link with asbestos fiber contamination in the environment.     

Mineral composition variation in the shells of freshwater mussel Anodonta woodiana at different growth stages

The levels of mineral element Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Mo, Al, As, Ag, Cd, and Tl were quantified in the whole shells of the freshwater bivalve Anodonta woodiana at three different growth stages (i.e. J1 juveniles of 1 month old, J2 juveniles of 3.5 months old, and adults of 36 months old). The concentrations of Na and Al were different between different growth stages (p < 0.05). The highest Na concentrations (2715 ± 86 μg/g dry weight) were found in J2 juveniles. The highest Al concentrations (303.9 ± 5.95 μg/g dry weight) were found in J1 juveniles. Manganese concentrations (517.0 ± 47.98 μg/g dry weight) were significantly higher in J2 juveniles than in J1 juveniles (432.3 ± 9.87 μg/g dry weight) (p < 0.05). Copper concentrations (27.32 ± 0.15 μg/g dry weight) were significantly higher in J1 juveniles than in J2 juveniles (26.21 ± 0.86 μg/g dry weight) and adults (24.74 ± 1.43 μg/g dry weight) (p < 0.05). Burdens of Na, Ca, Mn, Fe, Co, Cu, Mo, Ag, and Tl were positively correlated with the shell length (p < 0.05). These findings can possibly contribute to an understanding of elemental requirements for shell growth and, hence, facilitate improvement of survival and growth rates during artificial mussel culture.     

Biosorption of heavy metals in a photo-rotating biological contactor—a batch process study

Metal removal potential of indigenous mining microorganisms from acid mine drainage (AMD) has been well recognised in situ at mine sites. However, their removal capacity requires to be investigated for AMD treatment. In the reported study, the capacity of an indigenous AMD microbial consortium dominated with Klebsormidium sp., immobilised in a photo-rotating biological contactor (PRBC), was investigated for removing various elements from a multi-ion synthetic AMD. The synthetic AMD was composed of major (Cu, Mn, Mg, Zn, Ca, Na, Ni) and trace elements (Fe, Al, Cr, Co, Se, Ag, Mo) at initial concentrations of 2 to 100 mg/L and 0.005 to 1 mg/L, respectively. The PRBC was operated for two 7-day batch periods under pH conditions of 3 and 5. The maximum removal was observed after 3 and 6 days at pH 3 and 5, respectively. Daily water analysis data demonstrated the ability of the algal–microbial biofilm to remove an overall average of 25–40 % of the major elements at pH 3 in the order of Na?>?Cu?>?Ca?>?Mg?>?Mn?>?Ni?>?Zn, whereas a higher removal (35–50 %) was observed at pH 5 in the order of Cu?>?Mn?>?Mg?>?Ca?>?Ni?>?Zn?>?Na. The removal efficiency of the system for trace elements varied extensively between 3 and 80 % at the both pH conditions. The batch data results demonstrated the ability for indigenous AMD algal–microbial biofilm for removing a variety of elements from AMD in a PRBC. The work presents the potential for further development and scale-up to use PBRC inoculated with AMD microorganisms at mine sites for first or secondary AMD treatment.     

Metal phytoremediation potential of naturally growing plants on fly ash dumpsite of Patratu thermal power station,Jharkhand, India

Three naturally growing plants Ipomoea carnea, Lantana camara, and Solanum surattense were found in fly ash dumpsite of Patratu thermal power station, Jharkhand, India. They were assessed for their metal uptake potential. The fly ash was slightly alkaline with very less nitrogen and organic carbon but enriched with phosphorus and heavy metals. Lantana camara and Ipomoea carnea showed good translocation from root to shoot for most of the metals except Mn and Pb. The order of metal accumulation in stem of both the plants were Fe(205mg/kg)>Mn(65mg/kg)>Cu(22.35mg/kg)>Pb(6.6mg/kg)>Cr(3.05mg/kg)>Ni(1 mg/kg)>Cd(0.5 mg/kg) and Fe(741 mg/kg)>Mn(154.05 mg/kg)>Cu(20.75 mg/kg)>Pb(6.75 mg/kg)>Ni(4.0 mg/kg)>Cr(3.3mg/kg)>Cd(0.05mg/kg), respectively. But Solanum surattense accumulated most of the metals in roots. The order was in the following order, Mn (382.2mg/kg) >Fe (264.1mg/kg) > Cu (25.35mg/kg) >Pb (5.95 mg/kg) > Ni (1.9 mg/kg) > Cr (1.8mg/kg) > Cd (0.55 mg/kg). The order of Bioconcentration factor (BCF) in root and shoot followed almost the same order as, Mn>Fe>Ni>Pb>Cu>Cr≈ Cd in all the three species. ANOVA showed significant variation in metal accumulation by root and stem between the species. Finally, it can be concluded that Solanum surattense can be used as phytostabilizer and other two species as phytoextractor of metal for fly ash dumpsite reclamation.     

Metal Contamination in Sediment of One of the Upper Reaches of the Yangtze River: Mianyuan River in Longmenshan Region,Southwest of China

Metal contamination in sediment of the Mianyuan River (one of the major upper reaches of the Yangtze River) in Longmenshan Region (China) was investigated in 2012. Means of metal concentrations in sediment (<74μm) were Cr: 59.93 ± 19.8% mg/kg; As: 7.21 ± 50.2% mg/kg; Se: 0.45 ± 66.3% mg/kg; Pb: 19.89 ± 29.3% mg/kg; Zn: 78.98 ± 31.9% mg/kg; Cd: 0.69 ± 28.3% mg/kg; Ba: 0.71 ± 34.0% g/kg; Mn: 0.55 ± 62.2% g/kg. This study suggested: (1) concentrations of Cd, As, Cr, and Pb in Mianyuan River sediment were lower than those of the middle and lower reaches of the Yangtze River; (2) the increase of metals during the period from 2006 to 2009 was probably related to the destruction of tailings piles by the Wen Chun earthquake in 2008; (3) organic materials decided the distribution of Cd, Se, As, Ba, and Mn in the upstream sediment, while the iron and manganese minerals controlled the distribution of Ba, Cr, and Zn in the downstream sediment; (4) sources of Cd, Se, and As were geogenic, while sources of Cr, Zn, Ba, and Mn were anthropogenic; (5) the source of Pb in the upstream sediment was probably automobile exhaust, but that of Pb in the downstream sediment was geogenic.     

Biotransformation of Heavy Metals from Soil in Synthetic Medium Enriched with Glucose and Shewanella sp. HN-41 at Various pH

The biotransformation of heavy metals from contaminated soil was examined using a facultative anaerobic bacterium Shewanella sp. HN-41. The experiments were carried out to assess the influence of glucose at various pH on the transformation of heavy metals from soil thorough solubilization. A preliminary study on the transformation of heavy metals from soil was first performed using a defined medium supplemented with glucose at 10, 20, and 30 mM to select the effective concentration. Among the three concentrations examined, glucose at 30 mM leached a highest level of metal ions. Therefore, 30 mM glucose was used as the representative carbon source for the subsequent experiments in a defined medium at various pH (5, 6, 7, 8, and 9). The organism HN-41 was not influenced by pH ranging from acidic to neutral and was able to metabolize all the metal elements from contaminated soil. The level of Fe, Cr, As, Mn, Pb, and Al solubilization ranged from 3 to 7664 mg kg^?1 at various initial pH. The rate of metal solubilization was found to be low at neutral pH compared with acidic and alkaline. These results are expected to assist in the development of heavy metal transformation processes for the decontamination of heavy metal-contaminated soil.     

Heavy Metals in Antarctic Notothenioid Fish from South Bay, Livingston Island, South Shetlands (Antarctica)

The Pb, Cd, Cu, Zn, and Mn contents of the liver, spleen, muscle, bones, scales, gills, and the whole body of 3- to 7-year-old notothenioid Antarctic cod (Notothenia coriiceps, Richardson, 1844) were measured. The highest heavy metal concentrations obtained are as follows: Cd in liver, the mean value was 1.36 ± 0.19 mg/kg dry weight (wt); Pb and Zn in spleen, the mean values were 3.33 ± 0.86 and 143.97 ± 16.17 mg/kg dry wt, respectively; Cu in gills, 3.76 ± 1.16 mg/kg dry wt; and Mn in scales, 14.80 ± 4.77 mg/kg dry wt. The comparison with the data reported up to now shows that the metal concentrations varied within relative wide ranges. These first data obtained could be used as a baseline to investigate further relationships among metal contents in fish, their diet, and habitat.     

Concentration Levels of Selected Metals in the Leaves of Different Species of Thyme (T. schimperi and T. vulgaris) Grown in Ethiopia

The contents of some selected metals Ca, Mg, Fe, Mn, Co, Cu, Zn, Ni, and Cd in different thyme leaf samples widely consumed in Ethiopia were determined by flame atomic absorption spectroscopy (FAAS) after acid digestion with 1:1 HNO₃/HClO₄ for 3 h at a temperature of 240°C by a Kjeldahl apparatus hot plate digester. The level of the nutrients in the four samples ranged from 1,239–2,517 μg/g, Ca; 1,524–1,786 μg/g, Mg; 728–2,517 μg/g, Fe; 37.7–114 μg/g, Mn; 2.59–4.3 μg/g, Co; 7.69–9.3 μg/g, Cu; 8.7–52 μg/g, Zn; and 9.83–14.2 μg/g, Ni; respectively. While the level of toxic metal Cd in the four samples ranged from 0.87–1.3 μg/g. The concentration of Ca was higher than the other metals in the three samples and Cd was the least of all the metals in the analyzed samples. The overall reproducibility of the method obtained from spiking experiment was within the range ±10%. This result will complement available data on food composition in Ethiopia.     

Aluminum,Fe, Ca,Mg, K,Mn, Cu,Zn and P in above- and belowground biomass. II. Pools and circulation in a subalpineAbies amabilis stand

Elemental concentrations of above- and belowground tissues were determined in anAbies amabilis stand in the Cascade Mountains, Washington, USA. These data were used to calculate the pools and circulation of trace elements and micronutrients on a stand level. For all elements except Al, a greater proportion (from 62 to 87%) was distributed in above- rather than belowground tissues. This contrasted sharply with the biocirculation of elements where 97% of the Al and Fe, 88% of the Cu and 67–84% of the Ca, P, and Mg of total detrital cycling was from the belowground components. Aboveground tissues, however, contributed 69% of the Zn, 65% of the K and 68% of the Mn found in annual detritus production. The proportion of total element pool circulated annually was the highest for Al (82%) and Fe (32%) followed by 13% and less for the remaining elements. Copper, Fe and Al were accumulated in root tissues, while Mn and Zn accumulated in foliage.We hypothesize that roots are an effective mechanism for avoiding Al toxicity in these subalpine ecosystems. The large root biomasses of these stands allow for high Al levels to be taken up and immobilized in roots; this is observed in the significantly higher Al accumulations in below- than aboveground tissues. The high root turnover in these stands is hypothesized to be a result of root senescence occurring in response to high Al accumulation. Furthermore, Al inputs into detritus production occur by soil horizon so that roots with high Al concentrations located in the Bhs horizon turnover and are retained within that horizon. These roots also decompose very slowly (99% decay = 456 years) due to the high Al and low Ca, Mn and Mg present in these tissues and therefore have very little impact on short-term elemental cycling.     

Bioaccumulation Potential and Physiological Responses of Aquatic Macrophytes to Pb Pollution

In view of their potential bioaccumulation of heavy metals, Ceratophyllum demersum and Myriophyllum spicatum was studied under hydroponic cultures enriched by different Pb concentrations (25, 50, 75 mg/l) for 1–7 days. Both species exerted remarkable capabilities to concentrate Pb in their tissues as compared to control. The highest accumulation value of Pb (164.26 mg/g.dw) was recorded in C. demersum and the most of metal (91.72 mg/g dw) accumulated after 1 d. Significant reduction in photosynthetic pigments and appearance of morphological symptoms such as chlorosis and fragmentation of leaves were evident after 7d at 75 mg/l. The activity of POX and APX, carotenoids and proline showed induction at lower concentration and duration followed by decline. Major re-shuffle in protein patterns appeared as a tolerant mechanism, which both species developed under Pb toxicity. Results suggest that both species responded positively to Pb concentration and accumulated high amount of metal. Due to metal accumulation coupled with detoxification potential, both species appear to have potential for use as phytoremediators and the developed responses can be used as reliable biomarkers for Pb water pollution.     

Potential of Spartina maritima in Restored Salt Marshes for Phytoremediation of Metals in a Highly Polluted Estuary

Sedimentary abiotic environment, and concentration and stock of nine metals were analyzed in vegetation and sediments to evaluate the phytoremediation capacity of restored Spartina maritima prairies in the highly polluted Odiel Marshes (SW Iberian Peninsula). Samples were collected in two 10 –m long rows parallel to the tidal line at two sediments depths (0–2 cm and 2–20 cm). Metal concentrations were measured by inductively coupled plasma spectroscopy. Iron, aluminum, copper, and zinc were the most concentrated metals. Every metal, except nickel, showed higher concentration in the root zone than at the sediment surface, with values as high as ca. 70 g Fe kg^–1. The highest metal concentrations in S. maritima tissues were recorded in its roots (maximum for iron in Spartina roots: 4160.2 ± 945.3 mg kg^–1). Concentrations of aluminum and iron in leaves and roots were higher than in superficial sediments. Rhizosediments showed higher concentrations of every metal than plant tissues, except for nickel. Sediment metal stock in the first 20 cm deep was ca. 170.89 t ha^–1. Restored S. maritima prairies, with relative cover of 62 ± 6%, accumulated ca. 22 kg metals ha^–1. Our results show S. maritima to be an useful biotool for phytoremediation projects in European salt marshes.     

The chelating effect of citric acid,oxalic acid,amino acids and Pseudomonas fluorescens bacteria on phytoremediation of Cu,Zn, and Cr from soil using Suaeda vera

Phytoextraction is a green technique for the removal of soil contaminants by plants uptake with the subsequent elimination of the generated biomass. The halophytic plant Suaeda vera Forssk. ex J.F.Gmel. is an native Mediterranean species able to tolerate and accumulate salts and heavy metals in their tissues. The objective of this study was to explore the potential use of S. vera for soil metal phytoextraction and to assess the impact of different chelating agents such as natural organic acids (oxalic acid [OA], citric acid [CA]), amino acids (AA) and Pseudomonas fluorescens bacteria (PFB) on the metal uptake and translocation. After 12 months, the highest accumulation of Cu was observed in the root/stem of PFB plots (17.62/8.19 mg/kg), in the root/stem of CA plots for Zn (31.16/23.52 mg/kg) and in the root of OA plots for Cr (10.53 mg/kg). The highest accumulation of metals occurred in the roots (27.33–50.76 mg/kg). Zn was the metal that accumulated at the highest rates in most cases. The phytoextraction percentages were higher for Cu and Zn (～2%) with respect to Cr (～1%). The percentages of metal removal from soil indicate the need to monitor soil properties, to recognize the influence of each treatment and to increase the concentration of bioavailable metals by the use of agricultural management practices aimed at promoting plant growth.     

Differences in hypericin synthesis between experimentally induced seedling shoot cultures of Hypericum hookerianum Wight & Arn.

During seed germination trials of Hypericum hookerianum, seedlings of Lake View accession from Palni hills of Southern India segregated into green- (97.44 %) and red-pigmented (2.56 %) types. Seedlings cultured in Murashige and Skoog (1962) basal medium developed into fast growing green and slow growing red plant types in 6 weeks, the latter showing increased concentrations of total phenols, anthocyanins and flavonoids and 19-fold higher concentration of hypericin. Hypocotyls/cotyledons of red seedlings cultured using 2.325 μM kinetin (KIN) produced hypericin-rich (4.38 ± 0.18 mg/g DW), stunted (0.5–1.2 cm) shoots which ceased to grow in 8 weeks. Segments (4–6 mm) of these shoots sub-cultured in the dark for 4 weeks followed by 2-week light exposure and repeated subculture enabled mass multiplication of productive (3.93 ± 0.06 mg hypericin/g DW) shoots. Green hypocotyls and cotyledons subjected to 4 + 2 weak dark–light treatment also produced 9.18 ± 2.44 and 4.25 ± 0.96 comparable hypericin-rich (3.73 ± 0.21 mg/g DW) shoots. Red and green seedling explants cultured in basal medium in the dark produced 6.82 ± 0.75 cm etiolated shoots with reduced leaves which synthesized 2.27 ± 0.15 mg hypericin/g DW on illumination. Green cotyledons cultured in the dark using 2.45 μM indole-3 butyric acid (IBA) formed calluses which on illumination formed 12.64 ± 3.8 productive (3.86 ± 0.31 mg hypericin/g DW) 0.5- to 1.5-cm-long shoot clusters. Phenotypic segregation of seedlings, the ability of both red and green seedling explants to multiply in the dark and produce hypericin on illumination, and IBA-induced indirect shoots producing significant amounts of metabolite compared to wild plants (0.35 ± 0.09 mg/g DW) and green shoot cultures (0.91 ± 0.03 mg/g DW) are new to Hypericum.     

Heavy metals extraction from municipal solid waste incineration fly ash using adapted metal tolerant Aspergillus niger

This study focused on the adaptation of Aspergillus niger tolerating high concentration of heavy metals for bioleaching of fly ash. The Plackett-Burman design indicated that Al and Fe inhibited the growth of A. niger (AS 3.879 and AS 3.40) significantly. The single metal (Al and Fe) and multi-metals adapted AS 3.879 strain tolerated up to 3500 mg/L Al, 700 mg/L Fe, and 3208.1mg/L multi-metals, respectively. The order of metal extraction yield in two-step bioleaching of 60 and 70 g/L fly ash using Al adapted, multi-metals adapted and un-adapted AS 3.879 strains was as follows: multi-metals adapted>Al adapted>un-adapted. The multi-metals adapted strain grew with up to 70 g/L fly ash and secreted 256 mmol/L organic acids after 288 h, where 87.4% Cd, 64.8% Mn, 49.4% Zn and 45.9% Pb were dissolved. The extracted metals in TCLP test of the bioleached fly ash by multi-metals adapted strain were under the regulated levels in China.