Luís A. B. Novo

Phytoremediation of amended copper mine tailings with Brassica juncea

Mine tailings remain a major concern to the mining industry and the environment. This study evaluates the potential of Brassica juncea for phytoremediation of copper mine tailings treated with technosol (TE) and compost (CO) and the effect of these amendments in the process. Ecophysiological and biochemical results reveal the capacity of B. juncea to grow and develop under the influence of both amendments, and aspects like its soil-covering ability, vigorous seedling growth, tolerance to metal toxicity and potential immobilisation of excluded trace metals in the rhizosphere, denote the species aptitude for phytostabilisation. Moreover, B. juncea also exhibits fitness for the uptake of Cu and Zn, due to its high biomass production and striking translocation and bioconcentration ratios for these metals, thus qualifying this species as a good candidate for phytoextraction in similar mine tailings. The treatments depict different effects on the phytoremediation process, with TE favouring phytostabilisation and CO enhancing phytoextraction.

The Potential of Salvia verbenaca for Phytoremediation of Copper Mine Tailings Amended with Technosol and Compost

Unreclaimed mine tailings sites are a worldwide problem. This study evaluates the potential of Salvia verbenaca for phytoremediation of copper mine tailings treated with technosol and compost. Ecophysiological results reveal the species ability to thrive in the assessed range of conditions, while the hydrogen peroxide assays exhibit the plant’s capacity to successfully respond to metal toxicity, supporting literature reports about its antioxidant capabilities. Furthermore, the results suggest a selective antioxidant response of S. verbenaca towards Cd, indicative of a protection mechanism against high concentrations of this element. Moderate concentrations of Cu in the roots, adequate translocation and bioconcentration factors, tolerance to metal toxicity, and ecophysiological characteristics classify S. verbenaca as a promising candidate for phytostabilization of mine tailings. The importance of the amendments in order to improve the overall phytostabilization performance is highlighted by the elevated correlations between the treatment properties and the extractable concentrations of trace metals.

Effect of Salinity on Zinc uptake by Brassica juncea

Salinity is a major worldwide problem that affects agricultural soils and limits the reclamation of contaminated sites. Despite the large number of research papers published about salt tolerance in Brassica juncea L., there are very few accounts concerning the influence of salinity on the uptake of trace metals. In this study, B. juncea plants divided through soil sets comprising 0, 900 and 1800 mg Zn kg−1, were treated with solutions containing 0, 60 and 120 mmol L−1 of NaCl, with the purpose of observing the effect of salt on Zn uptake, and some physiological responses throughout the 90 days experiment. Increasing concentrations of NaCl and Zn produced a decline in the ecophysiological and biochemical properties of the plants, with observable synergistic effects on parameters like shoot dry weight, leaf area, or photochemical efficiency. Nevertheless, plants treated with 60 mmol L−1 of NaCl accumulated striking harvestable amounts of Zn per plant that largely exceed those reported for Thlaspi caerulescens. It was concluded that salinity could play an important role on the uptake of Zn by B. juncea. The potential mechanisms behind these results are discussed, as well as the implications for phytoremediation of Zn on saline and non-saline soils.

Genome Editing Weds CRISPR: What Is in It for Phytoremediation?

The arrival of sequence-specific endonucleases that allow genome editing has shaken the pillars of basic and applied plant biology. Clustered regularly interspaced palindromic repeats (CRISPR) is a revolutionary genome-engineering tool that enables the enhancement of targeted traits in plants. Numerous plants, including energy crops, known for their potential to tolerate, immobilize, and stabilize inorganic and organic pollutants, have already been edited using different CRISPR systems. Moreover, a large array of genes responsible for increased metal tolerance, metal uptake and hyperaccumulation have already been identified. Thus, the CRISPR-mediated genome reprogramming of plants, including its use in gene expression regulation through transcriptional repression or activation (CRISPRi and CRISPRa), could be of paramount importance for phytoremediation. The simplicity, inexpensiveness, and capabilities of this gene editing technique could soon be used to enhance plants and bacteria involved in phytotechnologies, such as phystabilization, phytoextraction, phytomining, phytovolatilization, and bio-energy generation. In this brief viewpoint piece, we posit some of the potential benefits of CRISPR for phytoremediation.

Phytomining of Rare and Valuable Metals

The exponential growth of low-grade mining ores and metal-polluted soils around the world during the last decades is expected to continue at a higher rate in the foreseeable future. Yet, the strategic and commercial importance of some elements found in those sub-economic ores and soils, their elevated market prices, and the corresponding environmental concerns have opened a window of opportunity for phytomining. This phytoextraction-based technology uses the ability of certain plants to uptake valuable metals, producing a bio-ore from the harvested biomass that allows metal recovery through smelting. Once applied at large scale, phytomining may either function as a standalone operation to retrieve the desired element or jointly with phytoremediation, financing the costs of the latter. This chapter reviews the advances of phytomining since its inception in the 1990s, focusing on the results obtained to date, with gold, nickel, thallium, and rhenium.

Could Sci-Hub become a quicksand for authors?

Sci-Hub has shaken the pillars of scholarly publishing, providing free access to millions of paywall-protected scientific articles. Along the way, it has also challenged the hegemony of major publishers and a system propelled by scientometrics. Here we posit a scenario in which the myriad of papers offered by Sci-Hub could trigger a sudden flip to gold open-access, dragging authors into an even more restricting paywall.

Germination and Early Growth of Brassica juncea in Copper Mine Tailings Amended with Technosol and Compost

Mine tailings represent a serious threat to the environment and human health; thus their restoration has become a major concern. In this study, the interactions between Brassica juncea and different mine soil treatments were evaluated in order to understand their effect on germination and early growth. Three soil treatments containing 25% and 50% of technosol and 30% of compost were prepared. Germination and early growth were assessed in soil and pore water extracts from the treatments. Unlike the untreated mine soil, the three treatments allowed germination and growth, achieving levels comparable to those of seedlings from the same species developed in normal conditions. The seedlings grown in 50% of technosol and 30% of compost exhibited greater germination percentages, higher growth, and more efficient mechanisms against oxidative stress, ascribed to the organic matter and nutrients content of these treatments. Considering the unequivocal ability of B. juncea for phytoremediation, the results suggest that technosol and compost may be an auspicious solution to allow the germination and early growth of this species in mine tailings.

Metal Bioaccumulation by Plants in Roadside Soils: Perspectives for Bioindication and Phytoremediation

Traffic-related metal pollution is a serious worldwide concern. Roadside soils are constantly subjected to the deposition of metals released by tailpipe gases, vehicle parts, and road infrastructure components. These metals, including platinum group elements from catalytic converters, constitute a threat to surrounding ecosystems that frequently comprise pasture and agricultural lands. Due to the capacity of plants to tolerate and accumulate metals, the study of the vegetation growing in soils adjacent to roads is important to understand their role as bioindicators of traffic-related metal pollution and infer their potential for the phytoremediation of roadside areas. This chapter reviews the main sources of metals in roadside soils and dusts, and the bioaccumulation of metals in plants growing alongside roads presenting different traffic loads and climatic conditions. The pertaining literature is discussed with a particular emphasis on the suitability of the assessed plant species to indicate and mitigate traffic-related metal pollution.

State of the Art of Phytoremediation in Brazil—Review and Perspectives

The pollution of terrestrial and aquatic environments with heavy metals is a serious concern on a worldwide scale. Trace elements can be highly toxic and carcinogenic for human health while also detrimental to animal and plant life of ecosystems surrounding contamination hotspots. Phytoremediation is a low-cost and environment-friendly plant-based technique to alleviate polluted areas, which constitutes a viable alternative to other complex, costly, and often harmful traditional methods. Phytoremediation is particularly interesting for Brazil, given the country’s rich biodiversity and climate. This mini-review covers some of the most important results in phytoremediation studies carried out in Brazil to date, with a particular focus on the potential of the Brazilian flora for phytostabilization and phytoextraction, the two main subcategories of phytoremediation. Moreover, it includes data from two previously unpublished trials about phytoremediation of metal-polluted soil and water with vetiver grass and four wetland macrophytes (water hyacinth, creeping river grass, alligator weed, and water lettuce).

Distribution, Transport and Fate of Pollutants

Abstract Soil is a complex dynamic system of critical importance for life on Earth. As natural and anthropogenic processes continuously use soil as sink or pathway to potentially toxic elements (PTEs) and organic pollutants (OPs), it is crucial to understand their distribution, transport, and fate. This chapter provides a brief and focused overview about the migration of PTEs and OPs in soil. The physical, chemical, and biological mechanisms of soil were analyzed and discussed, due to the influence that exert on the pollutants behavior (form, availability, and toxicity), as well as in the release and retention processes that affect their migration. Thus, the fate of these pollutants is outlined by the pollutants intrinsic characteristics and by the action of soil abiotic and biotic mechanisms. Modeling pollutants in soil is a key tool to the study and understanding of the complex leaching and transport processes involved on this.