Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

Abstract

Zirconium (Zr) is a transition metal that has both stable and radioactive isotopes.This metal has gained significant attention as a major pollutant of concern, partly because it has been prominent in the debate concerning the growing anthropogenic pressure on the environment. Its numerous past and present uses have induced significant soil and water pollution. Zr is generally considered to have low mobility in soils. The behavior of Zr particularly depends on the characteristics of the media in which it exists, and even its presence in the biosphere as a contaminate may affect its behavior. In this chapter, we describe the relationship between the behavior of Zrand its speciation in soils, its uptake and accumulation by plants, its translocation and toxicity inside plants, and mechanisms by which plants detoxify it.Zr is abundant and occurs naturally in the earth's crust. Zr emissions to the atmosphere are increasing from anthropogenic activities such as its use in industry and nuclear reactors. Zr forms various complexes with soil components, which reduces its soil mobility and phytoavailabilty. The mobility and phytoavailabilty of Zr in soil depend on its speciation and the physicochemical properties of soil that include soil pH, texture, and organic contents. Despite having low soil mobility and phytoavailability,amounts of Zr are absorbed by plants, mainly through the root system and can thereby enter the food chain.After plant uptake, Zr mainly accumulates in root cells. Zr does not have any known essential function in plant or animal metabolism. Although little published data are available, we conclude that the phytotoxicity of Zr is generally low.Notwithstanding, Zr can significantly reduce plant growth and can affect plantenzyme activity. When exposed to Zr-induced toxicity, plants possess numerous defense mechanisms to cope with the toxicity. Such strategies include Zr sequestration in plant roots and activation of various antioxidants. Because Zr may have impact on the biosphere, we believe it deserves to be evaluated in supplementary studies that will enhance the understanding of its behavior in soil-plant systems.

Alleviation of chromium toxicity by glycinebetaine is related to elevated antioxidant enzymes and suppressed chromium uptake and oxidative stress in wheat (Triticum aestivum L.)

“…Larger Cr concentration in roots has also been observed in many plant species such as barley and Brassica napus (Gill et al 2015). Increased Cr sequestration in roots may be due to precipitation of Cr as insoluble salts or due to immobilization with other molecules such as sugar, pectins, celluloses, and hemicelluloses as proposed by Shahid et al (2013) or due to compartmentalization in vacuoles of root cell .…”

Antimony bioavailability: Knowledge and research perspectives for sustainable agricultures

“…Therefore, total soil metal concentration is not considered a good proxy to estimate metal bioavailability and toxicity in living organisms [17,19]. Antimony is also reported to exist in different chemical forms (organic and inorganic) in soil.…”

“…The bioavailable part of a metal can be taken up by plants and other living organisms. Bioavailability of Sb in soil is controlled by several processes, such as adsorption/desorption, precipitation/dissolution, and Sb-ligand complex formation [19]. These processes depend mainly on soil characteristics, such as cation exchange capacity, soil pH, soil texture, biological and microbial conditions, amount of metals, organic and inorganic ligands, and competing cations [45].…”

Cadmium Bioavailability, Uptake, Toxicity and Detoxification in Soil-Plant System

“…Overproduction of ROS may cause cell death due to oxidative processes such as DNA and RNA damage, enzyme inhibition, protein oxidation and membrane lipid peroxidation (Tian et al 2011;Shahid et al 2013aShahid et al , 2014a. To minimize Cd-induced ROS formation, plants possess several defense strategies, including sequestration of the metal within vacuoles and chelation by organic molecules (Hossain et al 2012).…”