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- Effect of arsenic, lead and zinc on seed germination and plant growth in black nightshade (solanum nigrum l.) vs. clover (trifolium incarnatum l.)Publication . Marques, Ana P. G. C.; Rangel, António O. S. S.; Castro, Paula M. L.S. nigrum was found to proliferate in sediments with high levels of metal pollution. Toxicity tests were performed using seed germination, root elongation, shoot length and biomass as parameters for establishing growth inhibition of S. nigrum and T. incarnatum by arsenic, lead and zinc. All the elements had a higher inhibitory action on the ger-mination and growth of T. incarnatum – inhibition occur-ring at 3 mg element per kg of dry sand. S. nigrum presented germination and growth at higher concentrations of those elements - 7 mg Pb kg-1, 10 mg Zn kg-1 and 10 mg As kg-1. Although inhibitory concentrations for each plant were dif-ferent, increasing the elements concentration reduced seed germination, root elongation and shoot length in T. incar-natum, but not always in S. nigrum. For the latter, low con-centrations (3 mg kg-1 dry sand) of Zn and As seemed to have stimulatory effects on germination. The addition of nu-trients did not cause a significant (P < 0.05) difference in the germination of both plants, except for high metal/ metal-loid concentration in S. nigrum. Concerning growth char-acteristics, nutrient addition was only a differentiation factor for shoot length at low metal/metalloid concentrations. S. nigrum could be a promising plant to be used in further ex-periments concerning the potential of phytoremediation of metal contaminated sites, as long as an adequate planting strategy is followed.
- A genotype dependent-response to cadmium contamination in soil is displayed by Pinus pinaster in symbiosis with different mycorrhizal fungiPublication . Sousa, Nadine R.; Ramos, Miguel A.; Marques, Ana P. G. C.; Castro, Paula M. L.Soil contamination with Cd is of primary concern and beneficial soil restoration strategies urge. The aim of this work is to evaluate the response of two different genotypes of Pinus pinaster (wild and selected) to Cd contamination and to assess how inoculation with ectomycorrhizal fungi, Suillus bovinus and Rhizopogon roseolus, influenced each genotype. Seedlings were exposed to soil contaminated at 15 and 30 mg Cd kg−1. Plant growth, mycorrhizal traits and Cd accumulation in different tissues of the plant were determined at harvest. The fungal community was assessed by denaturing gradient gel electrophoresis. At 15 mg Cd kg−1 S. bovinus increased aboveground development in both genotypes. At 30 mg Cd kg−1 non-inoculated wild genotype accumulated more Cd in the shoots (1.7-fold) than the selected genotype; inoculation with R. roseolus decreased Cd concentration in the roots of the selected genotype whereas the opposite occurred in the wild genotype. Cd concentration in the root system was the parameter most influenced by the interaction between the three studied variables. The fungal community established was affected by the Cd concentration in the soil. Results show that different genotypes of P. pinaster react differently to Cd exposure depending on the mycorrhizal association. The importance of considering the combination between plant genotype and its symbiotic partners when aiming at the forestation of degraded land is highlighted.
- Plants indigenous to Esteiro De Estarreja - Potential for heavy metal phytoremediationPublication . Marques, Ana P. G. C.; Rangel, António O. S. S.; Castro, M. L.worldwide with substantial economic consequences. Heavy metals are an important health hazard, causing disturbances namely at the level of muscular coordination (Zn) and of the nervous system and kidneys (Pb), problems with reproduction, physiology and morphology (Hg) and even cancer (As). Phytoremediation - the use of plants to remove or immobilise contaminants - may offer a safe and low cost method for the remediation of metal contaminated soil. The search for plants adapted to metal-stressful field conditions may be an adequate approach to find plant species with the capacity to tolerate or accumulate metals and with the potential to be applicable in further phytoremediation strategies. The area of Estarreja, in northern Portugal, is surrounded by a large industrial complex, composed essentially by chemical facilities that for many years have discharged their solid residues in an improvised sediment basin in the surrounding area, and released its wastewaters into a nearby stream - “Esteiro de Estarreja”. Despite the high levels of metals in the sediments, the vegetation in the banks of the stream remains prolific, yet heterogeneously distributed with Solanum nigrum L., Rubus ulmifolius Schott and Phragmites australis (Cav.) Trin. ex Steudel being the main plant colonisers. These species have been recognized to accumulate some metals to levels above those considered as normal in plant tissues, especially Zn - 10 to 100 mg Zn kg-1, with
- Phytoremediation as a biotechnological tool for environmental restorationPublication . Marques, Ana P. G. C.; Rangel, António O. S. S.; Calheiros, Cristina S. C.; Oliveira, Rui S.; Franco, Albina R.; Vosatka, Miroslav; Dodd, John C.
- Bacteria immobilisation on hydroxyapatite surface for heavy metals removalPublication . Piccirillo, C.; Pereira, S. I. A.; Marques, A. P. G. C.; Pullar, R. C.; Tobaldi, D. M.; Pintado, M. E.; Castro, P. M. L.Selected bacterial strains were immobilised on the surface of hydroxyapatite (Ca-10(PO4)(6)(OH)(2) - HAp) of natural origin (fish bones). The capacity of the material, alone and in combination with the bacterial strains to act as heavy metal removers from aqueous streams was assessed. Pseudomonas fluorescens (S3X), Micro bacterium oxydans (EC29) and Cupriavidus sp. (1C2) were chosen based on their resistance to heavy metals and capacity of adsorbing the metals. These systems were tested using solutions of Zn(II), Cd(II) and in solutions containing both metals. A synergistic effect between the strains and HAp, which is effective in removing the target heavy metals on its own, was observed, as the combination of HAp with the bacterial strains led to higher adsorption capacity for both elements. For the solutions containing only one metal the synergistic effect was greater for higher metal concentrations; 1C2 and EC29 were the most effective strains for Zn(II) and Cd(II) respectively, while S3X was less effective. Overall, an almost four-fold increase was observed for the maximum adsorption capacity for Zn(II) when 10 was employed - 0.433 mmol/g in comparison of 0.121 mmol/g for the unmodified HAP. For Cd(II), on the other hand, an almost three-fold increase was registered with EC29 bacterial strain - 0.090 vs 0.036 mmol/g for the unmodified HAp. When the solutions containing both metals were tested, the effect was more marked for lower concentrations.
- Use of different types of plants for the uptake of contaminantsPublication . Calheiros, Cristina S.C.; Marques, Ana P. G. C.; Oliveira, Rui S.; Rangel, António O. S. S.; Castro, Paula M. L.
- Phytoextraction of Zn by Solanum nigrum: effect of chelating agents (EDTA and EDDS) addition and inoculation with arbuscular mycorrhizal fungiPublication . Marques, Ana P. G. C.; Oliveira, Rui S.; Rangel, António O. S. S.; Castro, Paula M. L.
- Treatment of wastewaters contaminated with heavy metals using aerobic granules in a sequencing batch reactorPublication . Marques, Ana P. G. C.; Duque, Anouk F.; Castro, Paula M. L.
- Removal of heavy metals using different polymer matrixes as support for bacterial immobilisationPublication . Pires, Carlos; Marques, Ana P. G. C.; Guerreiro, António; Magan, Naresh; Castro, Paula M.L.Great attention is focused on the microbial treatment of metal contaminated environments. Three bacterial strains, 1C2, 1ZP4 and EC30, belonging to genera Cupriavidus, Sphingobacterium and Alcaligenes, respectively, showing high tolerance to Zn and Cd, up to concentrations of 1000 ppm, were isolated from a contaminated area in Northern Portugal. Their contribution to Zn and Cd removal from aqueous streams using immobilised alginate, pectate and a synthetic cross-linked polymer was assessed. In most cases, matrices with immobilised bacteria showed better metal removal than the non-inoculated material alone. For the immobilisation with all the polymers, 1C2 was the strain that increased the removal of Zn the most, whereas EC30 was the most promising for Cd removal, especially when combined with the synthetic polymer with up to a ca. 11-fold increase in metal removal when compared to the polymer alone. Removal of individual metals from binary mixtures showed that there was differential immobilisation. There was greater removal of Cd than Zn (removals up to 40% higher than those showed for Zn). The results show that metal contaminated environments constitute a reservoir of microorganisms resistant/tolerant to heavy metals that have the capacity to be exploited in bioremediation strategies. Capsule immobilisation of bacteria in the naturally occurring alginate and pectate and in a synthetic cross-linked polymer increased the Zn and Cd removal abilities from single and binary contaminated waters; the applications with the synthetic polymer were the most promising for Cd and Zn removal in single and binary mixtures.
- Mine land valorization through energy maize production enhanced by the application of plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungiPublication . Moreira, Helena; Pereira, Sofia I. A.; Marques, Ana P. G. C.; Rangel, António O. S. S.; Castro, Paula M. L.The use of heavy metals (HM) contaminated soils to grow energy crops can diminish the negative impact of HM in the environment improving land restoration. The effect of two PGPR (B1—Chryseobacterium humi ECP37T and B2—Pseudomonas reactans EDP28) and an AMF (F—Rhizophagus irregularis) on growth, Cd and Zn accumulation, and nutritional status of energy maize plants grown in a soil collected from an area adjacent to a Portuguese mine was assessed in a greenhouse experiment. Both bacterial strains, especially when co-inoculated with the AMF, acted as plant growth-promoting inoculants, increasing root and shoot biomass as well as shoot elongation. Cadmium was not detected in the maize tissues and a decrease in Zn accumulation was observed for all microbial treatments in aboveground and belowground tissues—with inoculation of maize with AMF and strain B2 leading to maximum reductions in Zn shoot and root accumulation of up to 48 and 43 %, respectively. Although microbial single inoculation generally did not increase N and P levels in maize plants, co-inoculation of the PGPR and the AMF improved substantially P accumulation in roots. The DGGE analysis of the bacterial rhizosphere community showed that the samples inoculated with the AMF clustered apart of those without the AMF and the Shannon-Wiener Index (H′) increased over the course of the experiment when both inoculants were present. This work shows the benefits of combined inoculation of AMF and PGPR for the growth energy maize in metal contaminated soils and their potential for the application in phytomanagement strategies.