Ferns, accumulation

Cleaning up arsenic-contaminated soil and water poses a significant problem. One approach is to find plants that will leach arsenic from the soil. Such a plant, the brake fern, recently has been shown to have a voracious appetite for arsenic. Research led by Lenna Ma, a chemist at the University of Florida in Gainesville, has shown that the brake fern accumulates arsenic at a rate 200... 

Benaroya, R.O., Tzin, V., Tel-Or, E., and Zamski, E., Lead accumulation in the aquatic fern Azollafilicu-loides, Plant Physiology and Biochemistry, 42, 639-645, 2004. 

Singh, S.M. and P.N. Ferns. 1978. Accumulation of heavy metals in rainbow trout Salmo gairdneri (Richardson) maintained on a diet containing activated sewage sludge. Jour. Fish Biol. 13 277-286. 

The list we have presented is far from complete, and is developing as our knowledge of the plant kingdom increases. A recent exciting discovery has been Ma et al. s (2001) description of the fern Pteris vittata, which hyper-accumulates arsenic, and thus may be developed as a phytoremediation technology for this particularly dangerous pollutant. 

Ferns GA, Raines EW, Sprugel KH, Motani AS, Reidy MA, Ross R. Inhibition of neointimal smooth muscle accumulation after angioplasty by an antibody to PDGF Science 1991 253(5024)4 129-1 132. 

Another illustration of the potential in harnessing plant life for soil remediation is the finding20 that the fern, Pier is vittata, when grown in soil containing 6 ppm arsenic, hyper-accumulated 755 ppm of this metalloid in its fronds in only two weeks. When Pier is vittata was grown in artificially contaminated soil (1500 ppm As), the fronds took in 15,861 ppm As in the same two-week time frame. Similarly, research in both the United States and the United Kingdom has demonstrated the potential of using plants from the family Brassicacae in the remediation of soils heavily contaminated with zinc, cadmium, nickel, lead, and selenium.21... 

Luongo, T. and Ma, L.Q. 2005. Characteristics of arsenic accumulation by Pteris and non-Pteris ferns. Plant and Soil, 277 117-26. 

Meharg, A.A. 2003. Variation in arsenic accumulation-hyperaccumulation in ferns and their allies. New Phytology, 157 25-31. 

It must be settled whether this approach is sensitive or insensitive towards nonphysiological distributions and amounts of heavy metals, not the least for the sake of biomonitoring. There are data on heavy metal (Zn, Cd, Cu, Pb) accumulation in litter and different soil layers and in plants of some oak woodland next to a metal smelter (Avonmouth near River Severn) in Great Britain (Martin and Bullock 1994). The concentrations in the litter layer are (in xg/kg) Cd 60, Cu about 170, Pb and Zn around 3,000. As usual for these metals except of Zn, where BCF 1 is a normal value, the concentrations of the four metals in photosynthetic organs of oak Quercus robur, other trees and scrubs and the fern Dryopteris are considerably lower than in supporting soils. In this restricted set of metal data, there are pairs of identical soil-leaf BCF only for Quercus robur (Zn, Cd BCF = 0.045) and Dryopteris spp. (Cd, Cu BCF about 0.13) the former corresponds to Ej (L) = -0.28 V, the latter to very similar -0.29 V. 

The term hyperaccumulators was first used by Brooks et al. [113] to describe the plants that take up and accumulate more than 1000 pmoles As/g dry weight. A report about an arsenic-hyperaccumulating fern species additionally discussed the ph)Poremediation potentials of such plants [114]. Recent investigation has shown that the arsenic compounds in terrestrial and aquatic plants, fimgi, and lichen species are also interesting natural products [115, 116]. 

Ma, L. Q., Komar, K. M., Tu, C., Zhang, W. H., Cai, Y., and Kennel ley, E. D. (2001). A fern that hyper-accumulates aisenic a hardy, versatile, fast-growing plant helps to remove arsenic from contaminated soils. Nature 409(6820), 579. 

Webb SM, Gailiard J-F, Ma LQ and Tu C (2003) XAS speciation of arsenic in a hyper-accumulating fern. Environ Sci Technol 37 754-760. 

Rosmarinic acid (a-O-ca ffeoy i-3.4-di hydroxy phenyl act ic acid) (Figure 1) is an example of a caffeic acid ester occurring in plants. Rosmarinic acid is mainly found In species of the Boraginaceae and Lamiaceae families, but can also be detected in other families (i.e. Apiaceae), ferns and homworts (Table I) (3,d). This suggests that the ability to synthesize this cafTeoyl ester may actually be widespread as evidenced by rosmarinic acid accumulation in a range of species (Table I) (5). 

Some plants are able to accumulate exceedingly high concentrations of arsenic (in the order of 1% dry mass). Such arsenic hyperaccumulators were first reported in 1975 (126), and there have been several subsequent reports (127,128,118,119). Recent work has shown that arsenic-hyperaccumulating ferns store their high arsenic burden primarily in the fronds as arsenite (118,119). Arsenite is generally thought to be the most toxic of the arsenic species the physiological processes at play in the fern are of considerable interest. 

An arsenic hyper-accumulating fern has been developed by Lena Q. Ma, Kenneth M. Komar, Cong Tu, Weihua Zhang, Yong Cai, and Elizabeth D. Kennelley Business Week, February 12, 2001). This fern not only cleans up soil contaminated with arsenic but can locate arsenic hot spots, such as those where arsenical shells are buried. It will grow faster in high levels of arsenic. 

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