Uptake and Distribution of Mercury within Higher Plants

Abstract

The uptake and distribution of inorganic mercury (HgCl2) within higher plants (Pisum sativum and Mentha spicata) was examined using solution culture and radiotracer techniques. Plants were found to tolerate an external level of 1 mgHg/kg of solution but both physiological and biochemical processes were affected at 5 mgHg/kg and 10 mgHg/kg. The uptake of Hg into plants grown in hydroponic solution was a function of external concentration. Over the concentration range considered the accumulation of Hg in the roots was linear on a log‐log basis although the uptake of the element into the shoots appeared to be two‐phased. The distribution of Hg in plants was asymmetrical with much greater amounts of the element in the roots than the shoots. Although the level of Hg increased generally in plant tissues with increasing external levels, the proportion retained in the roots, relative to the shoots, was constant (approximately 95%). Two binding characteristics of the Hg within plant tissue were detected. A major proportion of Hg was tightly bound, being unaffected by treatment with ethanol and hydrochloric acid. The remaining Hg in the tissue was removed by either water or hydrochloric acid treatment. Cell fractionation indicated that the major binding component of Hg in plant tissues was the cell wall.

Physiological responses of Eichhornia crassipes [Mart.] Solms to the combined exposure to excess nutrients and Hg

“…As frequently reported in the literature (Beauford et al, 1977;di Toppi et al, 2003;Greger et al, 2005), Hg accumulates mainly in roots; however, the extraordinary Hg-tolerance and accumulation capacity displayed by E. crassipes in laboratory trials contrasts with results obtained in field surveys. This discrepancy can probably be attributed to two main factors: (i) the sum of all stress acting in natural environments or constructed wetlands (e.g.…”

The impact of sewage irrigation on the uptake of mercury in corn plants (Zea mays) from suburban Beijing

“…Wang et al, 2001;Yu et al, 2004). However, uptake of Hg within plants may be stifled by the barrier effect of the roots (Beauford et al, 1977;Cavallini et al, 1999;Greger et al, 2005;Lindberg et al, 1979), as non-essential and/or toxic elements are not readily translocated (Streit and Stumm, 1993).…”

Growth of selected plant species in biosolids-amended mine tailings

“…In addition, Hg does not have any known biological function (Beauford et al, 1977). This may explain why any Hg-hyperaccumulating plant has yet to be identified.…”

“…Limited uptake of Hg has been shown in mosses, lichens, fungi and in wetland, woody and crop plants (Patra and Sharma, 2000). Other studies on the phytoremediation of mercury in contaminated soils have been reported using different plant species such as Atriplex canescens (saltbush ) (Patra and Sharma, 2000), Rumex induratus and Marrubium vulgare (common horehound) (MorenoJiménez et al, 2006), white lupin (Ximenez-Embun et al, 2001), Tritcum aestivum (wheat) (Cavallini et al, 1999), Pisum sativum (pea) (Beauford et al, 1977;Godbold and Huttermann, 1986), Sorghum bicolor (sorghum) (Patra and Sharma, 2000), Chrysopogon zizanioides (vetiver grass) (Wong, 2003), Azolla caroliniana (an aquatic fern) (Bennicelli et al, 2004), and Oryza sativa (rice) (Du et al, 2005). Few studies however, have been carried out on biosolids phytoremediation and Hg was found mainly in the roots of the nine plant species tested with very low translocation to the shoot (Lomonte et al, 2010a).…”