Evaluation of copper bioaccumulation and translocation in Jatropha curcas grown in a contaminated soil

Phytoremediation of highly contaminated mining soils by Jatropha curcas L. and production of catalytic carbons from the generated biomass

This paper deals with the removal of heavy metals from marginal soil mixtures from the Cobre Las Cruces and Aznalcóllar mining areas containing high concentrations of metals (Cr, Fe, Ni, Cu, Zn, Cd, Hg, Pb and As) by means of phytoremediation using Jatropha curcas L., and the subsequent production of biocatalysts from the plant biomass. First, J. curcas L. was sowed in eight mixtures of these mining soils to study its adaption to these high-contaminated soils and its growth during 60 days in a greenhouse under conditions simulating the South of Spain's spring climate. Later, the most suitable soil mixtures for plant growth were used for 120-day phytoremediation under the same conditions. Heavy metal concentration in soils, roots, stems and leaves were measured by ICP-OES at the beginning, at the middle and at the end of the phytoremediation period, thus calculating the translocation and bioaccumulation factors. J. curcas L. was found to absorb great amounts of Fe (>3000 mg kg^-1 plant) as well as notable amounts of Pb, Zn, Cu, Cr and Ni, and traces of As. Other metals with lower initial concentrations such as Cd, Hg and Sn were completely removed from soils. Finally, the plant biomass was subjected to pyrolysis to obtain catalytic biocarbons, assessing the optimal temperature for the pyrolytic process by means of thermogravimetric analysis and Raman spectroscopy.

Growth, biochemical response and nutritional status of Angico-Vermelho (Parapiptadenia rigida (Bentham) Brenan) under the application of soil amendment in Cu-contaminated soil

Forest species Angico-Vermelho (Parapiptadenia rigida (Bentham) Brenan) is an alternative for the revegetation of areas contaminated with high levels of heavy metals such as copper (Cu). However, excess Cu may cause toxicity to plants, which is why the use of soil amendments can facilitate cultivation by reducing the availability of Cu in the soil. The aim of this study was to assess how the use of amendment can contribute to growth and nutritional status as well as reduce oxidative stress in Angico-Vermelho grown in Cu-contaminated soil. Samples of a Typic Hapludalf soil containing high Cu content were used for the application of four amendments (limestone, organic compost, Ca silicate and zeolite), in addition to a control treatment. The treatments were arranged in a completely randomized design, with four replicates. The use of amendments decreased Cu content available in soil and contributed to improve both plant nutritional status and its antioxidant response expressed by enzymatic activity. The application of the amendments, especially zeolite and Ca silicate, increased dry matter yield of Angico-Vermelho. Thus, the results presented here suggest that the use of amendments contributes to improving Cu-contaminated soils and favors revegetation with Angico-Vermelho.

Domestication and Breeding of Jatropha curcas L

Jatropha curcas L. (jatropha) has a high, untapped potential to contribute towards sustainable production of food and bioenergy, rehabilitation of degraded land, and reduction of atmospheric carbon dioxide. Tremendous progress in jatropha domestication and breeding has been achieved during the past decade. This review: (i) summarizes current knowledge about the domestication and breeding of jatropha; (ii) identifies and prioritizes areas for further research; and (iii) proposes strategies to exploit the full genetic potential of this plant species. Altogether, the outlook is promising for accelerating the domestication of jatropha by applying modern scientific methods and novel technologies developed in plant breeding.

Amelioration of iron mine soils with biosolids: Effects on plant tissue metal content and earthworms

The achievement of environmentally sound and economically feasible disposal strategies for biosolids is a major issue in the wastewater treatment industry around the world, including Swaziland. Currently, an iron ore mine site, which is located within a wildlife sanctuary, is being considered as a suitable place where controlled disposal of biosolids may be practiced. Therefore, this study was conducted to investigate the effects of urban biosolids on iron mine soils with regard to plant metal content and ecotoxicological effects on earthworms. This was done through chemical analysis of plants grown in biosolid-amended mine soil. Earthworm behaviour, reproduction and bioaccumulation tests were also conducted on biosolid-amended mine soil. According to the results obtained, the use of biosolids led to creation of soil conditions that were generally favourable to earthworms. However, plants were found to have accumulated Zn up to 346 mg kg^-1 (in shoots) and 462 mg kg^-1 (in roots). This was more than double the normal Zn content of plants. It was concluded that while biosolids can be beneficial to mine soils and earthworms, they can also lead to elevated metal content in plant tissues, which might be a concern to plant-dependant wildlife species. Nonetheless, it was not possible to satisfactorily estimate risks to forage quality since animal feeding tests with hyperaccumulator plants have not been reported. Quite possibly, there may be no cause for alarm since the uptake of metals from soil is greater in plants grown in pots in the greenhouse than from the same soil in the field since pot studies fail to mimic field conditions where the soil is heterogeneous and where the root system possesses a complex topology. It was thought that further field trials might assist in arriving at more satisfactory conclusions.