Bioavailable Nickel and Zinc in Polluted Soil Alter the Growth of Non-pioneer Trees in the Brazilian Atlantic Forest

Background and aimsThe Brazilian Atlantic forest has been affected by the deposition of Ni and Zn, among other heavy metals adsorbed from atmospheric particles, which can be incorporated into the soil. If available in the soil, they can be absorbed by plant roots. The study aimed at testing experimentally the hypotheses: 1) Ni and Zn depositions increase their bioavailable fractions in the soil; 2) pioneer tree species demonstrate a greater potential to absorb Ni and Zn from the soil and less growth changes than non-pioneer species.MethodsThe experiment was carried out with six pioneer and non-pioneer species native to the Atlantic Forest, grown for 90 days in soil from an urban fragment of the Atlantic Forest, according to the treatments: soil with balanced fertilization (control) and soil enriched with Ni, Zn and Ni+Zn. At the end, the concentrations of Ni and Zn were determined in four soil fractions (F1: soluble; F2: linked oxides/hydroxides; F3: organic matter: F4: residual metals) and in leaves, stems/branches and roots. Mobility factors in soil, concentration ratios between treatments and respective controls, translocation index and relative growth rate in height, leaf number and total biomass were also calculated.ResultsThe results showed that Ni and Zn concentrations increased significantly in the bioavailable soil fractions (F1, F2). The absolute content of Ni and Zn in the plants directly reflected the soil level in the available forms.ConclusionsThe metal accumulation in the species occurred regardless of the successional group to which they belonged. Non-pioneer species showed greater susceptibility to the metals.

Growth, tolerance and zinc accumulation in Senna multijuga and Erythrina crista-galli seedlings

ABSTRACT Zinc (Zn) is a micronutrient that is reaching toxic levels in the soil, with the intensification of agricultural and industrial activities. The objective of this study was to evaluate the growth, accumulation and tolerance of Erythrina crista-galli and Senna multijuga seedlings in soil with addition of increasing Zn levels. The study was conducted in a greenhouse for 120 days, using a completely randomized design in a 2 x 6 factorial arrangement, corresponding to two tree species (S. multijuga and E. crista-galli) and six doses of zinc in the soil (0, 200, 400, 600, 800 and 1000 mg kg-1) with six replicates. E. crista-galli and S. multijuga seedlings decreased root and shoot dry weight with increasing Zn doses. E. crista-galli and S. multijuga have low Zn translocation index and are capable to phytostabilize Zn in the roots. E. crista-galli had greater tolerance to Zn compared with S. multijuga. The species have potential for Zn phytostabilization programs in contaminated soil.

The Effect ofTrichodermaon Heavy Metal Mobility and Uptake byMiscanthus giganteus,Salixsp.,Phalaris arundinacea, andPanicum virgatum

The effect of land application of biomaterials based on two strains ofTrichodermafungus on phytoremediation processes was studied. Six metals (Cd, Cr, Cu, Pb, Zn, and Ni) were analysed in soil and soil leachate as well as in plant tissues. The translocation index (Ti) and metal bioconcentration factors (BCF) calculated for the inoculated plants were increased compared to the noninoculated control, except for Pb andSalixsp. Simultaneously, the mobilisation of metals in soil solution as an effect of biomaterials was noted. The highest values ofTi—339% (for Cr), 190% (for Ni), and 110% (for Cu)—were achieved for the combinationMiscanteus giganteusandTrichodermaMSO1. The results indicated that the application of fungus has positive effects on increasing the biomass, soil parameters (C, N, and P), and solubility of heavy metals in soil and therefore in enhancing phytoextraction forMiscanthus giganteusL.,Panicum virgatumL.,Phalaris arundinaceaL., andSalixsp.

Uptake-related parameters as indices of phytoremediation potential

Phytoremediation is emerging as an alternative agriculture-based technology because remediation of metalpolluted sites can be brought about utilizing the ability of plants to uptake and store contaminants in them. A field study was conducted to assess the role of Indian mustard in phytoremediation of chromium-contaminated substrata. Uptake parameters, namely, bio-concentration factor, translocation index, Cr distribution within plant, and tolerance index were used in determining the remediation potential of the crop. A significant increase in Cr accumulation (0.64–4.19 mg g−1 DW, stem; and 0.77–1.1 mg Cr g−1 DW, root), coupled with high tolerance indices, was observed in response to Cr stress, thus showing that Indian mustard is a potential hyperaccumulator. Movement and subsequent distribution of metal ions in the plant were assessed by studying the translocation index which showed a consistent increase (27–87% at T5) with time, and bioconcentration factor, where also an increase over a time period was observed in stem (1.3–11.4, T1) and root (1.96–5.56, T1), thereby, depicting the strong ability of Indian mustard for phytoextraction. A significant decline, however, was observed in the bioconcentration factor with increase in the dose of Cr application.

Effect of selenium, molybdenum and zinc on seedling growth and frequency of grain weevil (Sitophilus granarius) in triticale grains

The effects of different doses (0, 90, 270, 810 kg/ha) of selenium, molybdenum and zinc microelements on their translocation and accumulation in grains, seedling growth and grain infestation were examined under field conditions on a calcareous chernozem soil. Thirteen years after the application of selenium, molybdenum and zinc, significant translocation and accumulation of these elements in the grain were established, indicating a long-term effect of these microelements on triticale plants. The highest degree of accumulation in grains and seedling shoots was found for selenium, then molybdenum, while the detected amounts of zinc were significantly lower. The degree of accumulation of all three microelements in the grain and seedling shoot increased as doses increased. Translocation index from shoot to grain at the grain-filling phase was the highest when zinc was used, then selenium, and the lowest when molybdenum was applied. The highest translocation index from the grain during germination into seedling shoots was obtained with zinc, then molybdenum and selenium. Translocation indexes of the investigated elements significantly decreased as the doses of elements increased. Dry weight of seedling shoots decreased as molybdenum and zinc in grain increased. High selenium concentration moderately stimulated seedling development, pointing out a high tolerance of triticale to higher concentration of this microelement at initial development stages. Infestatation with grain weevil was provoked by high concentrations of these microelements in the grain. High concentrations of zinc and selenium, in particular, significantly decreased the percentage of damaged grains, while molybdenum moderately increased their numbers. The effect of zinc and molybdenum may be attributed to their chemical effect, while selenium effect may also be referred to a negative effect of the volatile selenium compound. The effect of selenium, molybdenum and zinc contamination of grains on the seedling growth and frequency of grain weevil was different, and the emphasis was on selenium.