Multivariate analysis of elements in Chinese brake fern as determined using neutron activation analysis

Arsenic-induced nutrient uptake in As-hyperaccumulator Pteris vittata and their potential role to enhance plant growth

It is known that arsenic (As) promotes growth of As-hyperaccumulator Pteris vittata (PV), however, the associated mechanisms are unclear. Here we examined As-induced nutrient uptake in P. vittata and their potential role to enhance plant growth in sterile agar by excluding microbial effects. As-hyperaccumulator P. multifida (PM) and non-hyperaccumulator P. ensiformis (PE) belonging to the Pteris genus were used as comparisons. The results showed that, after 40 d of growth, As induced biomass increase in hyperaccumulators PV and PM by 5.2-9.4 fold whereas it caused 63% decline in PE. The data suggested that As played a beneficial role in promoting hyperaccumulator growth. In addition, hyperaccumulators PV and PM accumulated 7.5-13, 1.4-3.6, and 1.8-4.4 fold more As, Fe, and P than the non-hyperaccumulator PE. In addition, nutrient contents such as K and Zn were also increased while Ca, Mg, and Mn decreased or unaffected under As treatment. This study demonstrated that As promoted growth in hyperaccumulators and enhanced Fe, P, K, and Zn uptake. Different plant growth responses to As among hyperaccumulators PV and PM and non-hyperaccumulator PE may help to better understand why hyperaccumulators grow better under As-stress.

Arsenic, antimony, and bismuth uptake and accumulation by plants in an old antimony mine, China

Arsenic (As), antimony (Sb), and bismuth (Bi) are metalloids that share similar chemical properties, the objective of this study was to characterize the uptake and accumulation of these metalloids by plants colonized on heavy contaminated sites in an old Sb mine. Sixty-five plant samples from seven species as well as the associated soil samples were collected at ten sites of Xikuangshan (XKS), Hunan province, China. Concentrations of As, Sb, and Bi in plants and soils were measured. As, Sb, and Bi were found to be evidently elevated due to the long history and intensive mining and smelting activities; the respective ranges for the levels of As, Sb, and Bi at the sites were 40.02-400.2 mg kg(-1) As, 610-54,221 mg kg(-1) Sb, and n.d. to 1,672 mg kg(-1) Bi. No correlation was found between As and Sb at the sites, while Bi was found to be positively correlated with As whereas negative with Sb at the sites. In general, the contents in the plants in XKS were in the order of As > Sb > Bi, and the contents of As was positively correlated with Sb and Bi in plants. The highest contents of As and Sb recorded was 607.8 mg kg(-1) As in Pteris vittata and 90.98 mg kg(-1) Sb in Hippochcaete ramosissima, while the highest Bi content as 2.877 mg kg(-1) Bi was measured in Buddleja davidii. Bioconcentration factors defined as the ratios of metalloids in shoots of plants to those in soils for various plants were lower than 1. The results showed plants colonized at the heavy contaminated sites in XKS had great tolerance to As, Sb, and Bi, and demonstrated similarities in plant uptake and accumulation of these three elements.

Leaching potential of arsenic from Pteris vittata L. under field conditions

Foliar leaching might be an important process in the biogeochemical cycle of elements, but the leaching behaviors of As remain unclear. This study examined As leaching from foliage of an As-hyperaccumulator, Pteris vittata L. in the field. Results indicated that substantial amounts of As can be leached from the foliage by precipitation. Arsenic concentrations in the foliar leachate ranged from 4.06 to 519 microgL(-1), and the percentages of As(III) with respect to total As in leachate ranged from 5% to 10%. A positive linear relationship existed between As concentrations of the foliar leachate and the amounts of As accumulated in the plant. The rate of As leaching from the leaves was accelerated by an increase of rainfall and time in a simulated precipitation experiment. Water-soluble As distributed within the cuticle and apoplast of the plant was speculated as the main source of the leached As. The As leaching is an important process of within-ecosystem As cycling in phytoremediation and it deserves further investigation.

Pteris vittata - revisited: uptake of As and its speciation, impact of P, role of phytochelatins and S

Pteris vittata is known to hyperaccumulate As but the mechanism is poorly understood. We found an increase of As concentration with increasing soil solution As concentrations, but P application had no impact, although plant P concentrations responded to different rates of P supply. As in fronds was dominantly (82-89%) present in the form of AsIII. In roots we detected 45% as AsIII which is higher than reported in previous studies and supports substantial As-reduction to take place in roots. We detected PC2/3GS-AsIII, PC2-GS-AsIII and (PC2)2-AsIII in increasing amounts with application of As. The total amount of PC was in the range reported previously and far too small to assign a significant role in As detoxification to PCs. The close correlation between S and As in fronds and the lack of data on sulphur uptake and metabolism indicates the need for a detailed investigation on sulphur nutritional status and As metabolism in P. vittata.