Phytoaccumulation of metals in three plants species of the Asteraceae family sampled along a highway

The aim of this study was to determine the ability of roots and above-ground parts of three plant species of the Asteraceae family (Matricaria inodora L., Achillea millefolium L., Crepis setosa Haller fill.) for bioaccumulation and translocation of eight metals (Ca, Mg, Fe, Mn, Cu, Zn, Pb, Cr). Those plants were sampled directly along the lanes of the highway at the entrance into the City of Kragujevac, Republic of Serbia. The investigated metals are emitted into the air from road traffic and are deposited in the surrounding soil. Many of them are toxic to the living organism, and it is, therefore, necessary to apply effective, economical, sustainable methods for their removal from the environment. An example of such a method is as phytoremediation, based on the use of metal hyperaccumulator plants. The results of this research showed the species studied differ in the absorption, translocation and accumulation of investigated metals. They also showed that species M. inodora and A. millefolium (leaves) can be used for the phytoextraction of Ca, Mg, Fe, Mn, Cu, Zn and Cr, species C. setosa (leaves) for Ca, Mg and Cu species M. inodora (stem) for Cr. The results further indicate that all three species absorb Zn from the soil and translocate it to the stems and leaves. All three of the studied species are suitable for phytostabilization of soils loaded with Zn, but only the species M. inodora and C. setosa can be applied in phytoremediation of this metal.

Use of machine learning to establish limits in the classification of hyperaccumulator plants growing on serpentine, gypsum and dolomite soils

The so-called hyperaccumulator plants are capable of storing hundred or thousand times bigger quantities of heavy metals than normal plants, which makes hyperaccumulators very useful in fields such as phytoremediation and phytomining. Among these plants there are many serpentinophytes, i.e., plants that grow exclusively on ultramafic rocks which produce soils with a great proportion of heavy metals. Even though there are multiple classifications, the lack of consensus regarding which parameters to use to determine whether a plant is a hyperaccumulator, as well as the arbitrariness of stablished thresholds, bring about the need to propose more objective criteria. To this end, plant mineral composition data from different vegetal species were analysed using machine learning techniques. Three complementary case studies were established. Firstly, plants were classified in three types of soils: dolomite, gypsum and serpentine. Secondly, data about normal and hyperaccumulator plant Ni composition were analysed with machine learning to find differentiated subgroups. Lastly, association studies were carried out using data about mineral composition and soil type. Results in the classification task reach a success rate over 75%. Clustering of plants by Ni concentration in parts per million (ppm) resulted in four groups with cut-off points in 2.25, 100 (accumulators) and 3000 ppm (hyperaccumulators). Associations with a confidence level above 90% were found between high Ni levels and serpentine soils, as well as between high Ni and Zn levels and the same type of soil. Overall, this work demonstrates the potential of machine learning to analyse data about plant mineral composition. Finally, after consulting the red list of the IUCN and those of countries with high richness in hyperaccumulator species, it is evident that a greater effort should be made to establish the conservation status of this type of flora.

Phytoremediation of Heavy Metals Contaminated Soil in Artisanal Gold Mining at Selogiri, Wonogiri District, Central Java, Indonesia

Artisanal gold mining (ASGM) is commonly found in Indonesia, particularly in Wonogiri District, Central Java. One of the impacts of ASGM activity is soil contamination influence by mining waste. The objective of this study to investigate the potential use of Amaranthus spinosus L. and Jatropha curcas for remediation of Pb and As in contaminated soil. Phytoremediation experiment was conducted by using Amaranthus spinosus L. and Jatropha curcas and evaluate the effectiveness of both plants as a hyperaccumulator. The result shows that the higher Pb and As concentration was found in roots rather than shoots in both plants, however, the use of Jatropha curcas seems more effective on reducing Pb and As concentrations more than Amaranthus spinosus L in both shoots and roots. Generally, the use of both hyperaccumulator plants was more effective in Pb remediation compared to As. This phytoremediation experiment revealed that the use of both hyperaccumulator plants reduces the concentrations of Pb and As in contaminated soil, which of the critical point leading to the entry of Pb and As into the food chain.

Rview of phytoremediation of soil contaminated by vanadium

Vanadium is a nontrivial multi-valent metallic element, which has been increasingly used in modern society. The widespread application of vanadium promotes the rapid and sound development of the economy and society, simultaneously brings out increasingly prominent environmental problems, e.g., soil vanadium pollution. Therefore, the remediation problem of vanadium-contaminated soil has been received growing attention. Phytoremediation has become a significant constituent in vanadium-contaminated soil remediation attributable to its veritable merits such as cleanness, esthetics, cost-effectiveness, convenience, and sustainability. Phytoremediation is mainly dependent on hyperaccumulator plants, even though the actuality that the vast majority of hyperaccumulator plants are characterized by low biomass yield and slow-growing. Consequently, the intensity in screening the undiscovered hyperaccumulators should be strengthened. Meanwhile, it is imperative to further explore the vanadium accumulation and translocation characteristics of some non-hyperaccumulative but tolerant plants with moderate biomass to remediate the soil contaminated with vanadium. Taken together, further comprehensive researches of tolerance mechanisms of remedial plants against vanadium are quite necessary to decontaminate soils contaminated by vanadium efficiently.

Phytoremediation

This chapter includes the sources of cadmium and chromium contamination of soil and various detrimental effects on plants and animals. Ecofriendly approach of soil clean up by phytoremediation is the main focus of the author. Heavy metal-induced oxidative stress of plants and their detoxification potentiality has been discussed here to create a wholesome idea about the basic and acute need of phytoremediation. Both enzymatic and non-enzymatic antioxidative defense mechanisms and various other biochemical parameters of metal hyperaccumulator plants are mentioned.