Phytoextraction of Lead: Its Feasibility, Constraints and Concerns

Aims: With lead being one of the most common soil contaminants and phytoextraction has been reported as a prospective method for remediation of lead-contaminated soil, this review aims to examine the feasibility of lead phytoextraction as well as its constraints and concerns. Study Design: This is a literature review. Methodology: Peer-reviewed papers were sourced from scholarly databases. The papers included in the review were mainly those about phytoextraction of lead, particularly with the shoot, soil and root concentrations of lead mentioned as well as the bioconcentration and translocation factors stated. Besides, papers discussing the limits, for instance, the duration of lead phytoextraction, and concerns of the approach were also included. Results: This review found only 11 plants have been reported to accumulate lead in shoots at nominal threshold of near or above 1,000 mg Pb/kg dry weight and in certain cases, soil amendment was required to achieve this. Only two of the plants had bioconcentration factor > 1 and another two had translocation factor > 1. None of the plants fulfilled all three criteria of a successful hyperaccumulator, indicating the constraints and a lack of feasibility of lead phytoextraction. Besides, lead phytoextraction has been predicted to require significant amount of time, hence increasing the risk of exposure to lead. Conclusion: This review highlights that lead phytoextraction may not be feasible for the remediation of lead-contaminated soil. It recommends phytostabilization as a more viable alternative to immobilize lead in rhizosphere and reduce lead exposure.

Exploring distribution of potentially toxic elements in soil profiles to assess the geochemical background and contamination extent in soils of a metallurgical and industrial area in Kosovo

This geochemical study explored the distribution of potentially toxic elements (PTEs), such as As, Cd, Co, Cr, Cu, Ni, Pb, Sb, Tl, U, and Zn, along soil profiles of a metallurgical and industrial area in Kosovo, with the aim of assessing geochemical background and contamination threshold of PTEs in soil, and defining surface and vertical level and extent of soil contamination by PTEs. The geochemical background was assessed by exploratory data analysis of PTE concentrations in soil profiles. The upper limit of geochemical background (contamination threshold) was used as reference value to calculate the single pollution index and establish the PTE contamination level. Cadmium, Pb, Sb, Zn were the primary soil contaminants and As, Cu, Tl the secondary ones. The main sources of soil contaminants were the Zvecan smelter for Pb, Sb, As, Cu, Tl, and the Trepca industrial complex for Cd and Zn. The highest levels of Pb and Sb contamination were found up to depths between 30 and 60 cm in soil profiles within 5 km north and south-east of the Zvecan smelter. Contamination by Pb and Sb decreased with depth and affected the whole thickness of soil profiles closer the smelter. Cadmium and Zn contamination declined with distance from the Trepca industrial complex and decreased with depth, extending down to depths of 40–90 cm and 30–70 cm, respectively. Anomalous natural concentrations of Co, Cr, and Ni were found in soils collected in the northern part of the study area, where the geology consists mainly of ultrabasic and basic magmatic rocks.

Soil Remediation Applications of Nanotechnology

With the growth of urbanization, the anthropogenic activities have increased and thus increase occurrence of soil contaminants. In order to eliminate the contaminants in soil environment, the application of nanotechnology for soil remediation has become a great concern in the world. This review will discuss about the fate of contaminants in soil environment; the mechanisms of nanotechnology with various types of nanomaterials for the soil remediation; the advantages and disadvantage of nanomaterials towards the terrestrial organisms, human health as well as the soil environment; and the challenges of using nanotechnology for soil remediation.

Determination of Sulfites in Fruit Juices and Meals for Infants and Toddlers

Plants possess various intrinsic mechanisms necessary to accumulate and either sequester or detoxify soil contaminants, including radionuclides. The aim of this study was to determine the bioconcentration factor of two fast growing plants Salvia offlicinalis L. (sage) and Ocimum basillicum L. (basil) that were cultivated in pH neutral soils artificially contaminated with three different concentrations of uranium (211, 352 and 470 mg/kg). The efficiency of citric acid was evaluated with respect to the enhancement of the phytoextraction process. The results showed that the bioconcentration factor did not differ significantly between the selected species (0.01 - 0.03). Citric acid was added in doses (50 mL, 30 mM) until the first effects of uranium phytotoxicity appeared. After four doses of citric acid, the bioconcentration factor reached 0.05 for both plants. The increase of uranium content taken up by the respective plants was more pronounced. Thus, the uranium content of sage grown in contaminated soil (470 mg/kg) increased from 6.03 to 21.28 mg/kg in citric acid-treated soil. The data obtained confirmed the efficiency of citric acid in enhancing phytoextraction of uranium and further suggest that even plants of a rather small biomass can be useful in phytoremediation given the appropriate treatment through induced phytoextraction with appropriate chemical agents.

Biochar: A Sustainable Approach for Improving Soil Health and Environment

Current agriculture faces multiple challenges due to boom in food demand and environmental concerns. Biochar is increasingly being recognized by scientists and policy makers for its potential role in carbon sequestration, reducing greenhouse gas emissions, renewable energy, waste mitigation and as a soil amendment. The purpose of this review is to provide a balanced perspective on the agronomic and environmental impacts of biochar amendment to soil. Application of biochar to soil can play a significant role in the alteration of nutrients dynamics, soil contaminants as well as microbial functions. Therefore, strategic biochar application to soil may provide agronomic, environmental and economic benefits. Recent findings also supported that in order to enhance crop yield, improve soil quality and soil health, biochar has proven significant role as fertilizer and soil conditioner respectively.

Exploring heavy element distribution in soil profiles to assess the geochemical background and contamination extent in soils of a metallurgical and industrial area in Kosovo

This paper reports the results of a geochemical study focused on the distribution of heavy elements (As, Cd, Co, Cr, Cu, Ni, Pb, Sb, Tl, U, Zn) in soil profiles, with the aim of defining their geochemical background, contamination threshold, surface and vertical extent of contamination in soils of a metallurgical and industrial area in Kosovo. The geochemical background of heavy elements in soil was assessed by exploratory data analysis of their concentrations in soil profiles, and the contamination threshold was used as reference value to quantify their anthropogenic enrichment. Cadmium, Pb, Sb, Zn were the primary soil contaminants, As, Cu, Tl the secondary ones. The main sources of soil contaminants were the Zvecan smelter for Pb, Sb, As, Cu, Tl, and the Trepca industrial complex for Cd and Zn. The highest levels of Pb and Sb contamination were found up to depths between 30 and 60 cm in soil profiles within 5 km north and south-east of the Zvecan smelter. Contamination by Pb and Sb decreased with depth in soil profiles and affected the whole thickness of soils closer the metallurgical plant. Cadmium and Zn contamination declined with distance from the Trepca industrial complex and decreased with depth, generally extending down to depths of 40–90 cm and 30–70 cm, respectively. Cobalt, Cr, Ni, U were geogenic heavy elements. Anomalous natural concentrations of Co, Cr, Ni were found in soils collected in the northern part of the study area, where the geology consists mainly of ultrabasic and basic magmatic rocks.

Whole-Cell Microbial Bioreporter for Soil Contaminants Detection

Anthropogenic activities have released various contaminants into soil that pose a serious threat to the ecosystem and human well-being. Compared to conventional analytical methodologies, microbial cell-based bioreporters are offering a flexible, rapid, and cost-effective strategy to assess the environmental risks. This review aims to summarize the recent progress in the application of bioreporters in soil contamination detection and provide insight into the challenges and current strategies. The biosensing principles and genetic circuit engineering are introduced. Developments of bioreporters to detect and quantify heavy metal and organic contaminants in soil are reviewed. Moreover, future opportunities of whole-cell bioreporters for soil contamination monitoring are discussed.