Heavy metal pollution characteristics of soil around a copper-nickel mine tailings pond in the northwest arid area of China and evaluation of desert phytoremediation potential

Abstract

Phytoextraction and phytostabilization are two mechanisms used by plants to remove and stabilize heavy metals in soil. However, there has been little research on the extraction/stabilization of heavy metals by desert plants in arid areas. This study analyzed eight heavy metals (Cr, Ni, Cu, Zn, Cd, Pb, Mn, and As) in 10 desert plants and their growth matrices. In addition, the single factor pollution index and Nemerow comprehensive pollution index were used to evaluate soil pollution. Based on the biological accumulation factor and the biological concentration factor, the fuzzy evaluation method was used to evaluate plant extraction/stability potentials for heavy metals. The results showed that Cd, Cu, Ni, and Cr in the soil around the tailings pond were at the heavy pollution level, Mn and Pb pollution was moderate, and Zn and As pollution was light. The matrix factorization model showed that Cu and Ni came from industrial pollution; Cd and Cr came from atmospheric deposition and agricultural pollution; Pb came from traffic pollution; and Mn, Zn, and As came from natural sources. The metal contents of the desert plants exceeded the standard for normal plants, of which Cr contents in the Atriplex patens and Ammophila breviligulata Fernald aboveground parts were 35.63 and 53.77 mg/kg respectively, and the Ni contents in the Klasea centauroides subsp. polycephala (Iljin) L. Martins underground parts and the A. breviligulata Fernald aboveground parts were 102.67 and 101.67 mg/kg, respectively, exceeding the maximum toxicity threshold for Cr and Ni. Ammophila breviligulata Fernald had the highest plant comprehensive extraction coefficient (CEI) and plant comprehensive stability coefficient (CSI) at 0.81 and 0.83 respectively, indicating that it has strong heavy metal extraction and stabilization abilities. Therefore, A. breviligulata Fernald can be selected as a remediation species for heavy metal pollution in the soil around tailings reservoir areas.

Differences between total amount of heavy metals and their occurrence form contents in the wastelands of a molybdenum mine area

“…However, these results are not related to the high content of Pb in the crops in the study area. Approximately 90% of the Pb content in plants comes from the atmosphere rather than being absorbed from the soil by the roots (Shi et al 2013). Nevertheless, the soil Pb in the study area should be considered potentially harmful under reducing conditions.…”

“…Indeed, they are not easily absorbed by plants and are relatively safe for the environment. However, when they encounter acids, microorganisms, or chelating agents, residual heavy metals can re-enter the environment and threaten the ecosystem (Shi et al 2013).…”

“…However, such data cannot fully reflect the severity of soil heavy-metal pollution and the characteristics of the heavy-metal pollutants. Therefore, it is necessary to study the chemical speciation characteristics of heavy metals in soil (Shi 2010). Tessier proposed a continuous extraction method in 1979 to analyze the combination state of metals in soil or solid waste (Li et al 2021).…”

Addressing Heavy Metal Pollution in Nigeria: Evaluating Policies, Assessing Impacts, and Enhancing Remediation Strategies

“…Electrokinetic Remediation, involving low direct current or potential gradient applied to electrodes, can be integrated with various technologies (Reddy, 2013). Phytoremediation, microbial bioremediation, and biosurfactants are nature-based techniques that offer promising solutions for addressing heavy metal pollution with minimal secondary pollution (Ren et al, 2018;Oyedeji et al, 2022;Shi et al, 2022). Subsurface bioremediation has been recognized as an effective method for remediating shallow aquifers and ensuring safe groundwater.…”

“…Rhamnolipids, a type of biosurfactant, have demonstrated significant potential in soil remediation due to their ability to enhance the removal of heavy metals and organic contaminants from contaminated soils. Studies have shown that rhamnolipids can effectively stabilize and transport metal nanoparticles in porous media, indicating their potential for use in remediation strategies (Rahman et al, 2022;Shi et al, 2022;Lu et al, 2023). Rhizoremediation, a plantmicrobe symbiosis-based approach, has shown promise in the remediation of mixed-waste contaminated soil.…”