Kingkan Kheawsaard. Utilization of two common fern species : Pteris tripartita and Pteris vittata to remediate copper and arsenic contaminated soils . Master's Degree(Technology of Environmental Management). Mahidol University. : Mahidol University, 2004.
Utilization of two common fern species : Pteris tripartita and Pteris vittata to remediate copper and arsenic contaminated soils
Abstract:
This research aimed to investigate possibility of utilizing two fern species: Pteris tripartita and
Pteris vittata in extracting copper and arsenic in contaminated soils, as well as spiked aqueous media.
Rate and extent of metal accumulation, as well as localization of copper and arsenic in different parts of
the tested fern were also examined. In addition, an observation on effects of a chelating agent EDTA to
copper and arsenic translocation in the tested ferns was conducted.
From the results, both fern species at 7-months old could grow well in a copper contaminated
soil up to 514 mg Cu/ kg soil without any apparent adverse effects. Since the tested soil was polluted
with pig manure, it was high in fertility with elevated total nitrogen content up to 1.48 g N/ 100 g soil,
20.06 % organic matter and 5,150 mg P/ kg soil. After 8 weeks of copper accumulating studies, 156 and
172 μg Cu/g dry weight were observed in the root part of P. tripartita and P. vittata, respectively.
However, only a small amount of copper were accumulated in other parts of the tested plants. For the
petiole and frond, only 17 and 19 μg Cu/ g dry weight, and 8 and 16 μg Cu/g dry weight were found,
respectively. Considering the dry biomass of both ferns, the uptake efficiency of P. tripartita was 369 μ
g/ plant almost 3-fold higher than that of 118 μg/ plant of P. vittata. For arsenic contaminated soil,
growth retardation was observed in both tested ferns. Soil collected from Ron Phibun district contained
high arsenic levels up to 14,761 mg As/kg soil. It was low in fertility with low total nitrogen content of
0.06 g N/ 100 g soil and 0.82 % organic matter. After 8 weeks of arsenic accumulating studies in
arsenic contaminated soil, P. tripartita stored arsenic in root, petiole and frond tissues at the
concentration of 662, 40 and 95 μg As/ g dry weight, respectively, while P. vittata accumulated high
arsenic in its frond at 7,920 μg As/ g dry weight. Arsenic was accumulated at 1,177 and 1,736 μg/ g dry
weight in root and petiole, respectively. The fern P. vittata could store arsenic up to 6,142 μg/ plant
compared to only 793 μg/ plant of P. tripartita.
In copper spiked liquid media, both ferns could tolerate up to 40 mg Cu/ l during the 3 weeks
experimental period. Copper was found mostly in the root of both ferns. For P. tripartita, 35,345 and
487 μg /g dry weight, for P. vittata 29,908 and 1,261 μg/ g dry weight were accumulated in root and
shoot, respectively. In the case of P. tripartita, EDTA could significantly enhance copper translocation
into the shoot. However, a similar result was not observed in P. vittata. The fern P. tripartita could
tolerate up to 5 mg As/ l. Arsenic was found to accumulate mostly in root tissues at 271 μg /g dry
weight and shoot at 131 μg/ g dry weight. Arsenic was less toxic to P. vittata. There was no apparent
toxic effect observed after 3 weeks exposure to 20 mg/l arsenic. Up to 2,412 and 1,774 μg/ g dry weight
could be observed in its shoot and root, respectively. EDTA could not stimulate translocation of arsenic
into shoot of P. tripartita, while it caused significant decrease of arsenic accumulation in shoot of P.
vittata.
The results indicated that both fern species could be utilized for remediation of copper and
arsenic contaminated soil, as well as for treating wastewater containing high copper and arsenic
concentrations. Due to elevated copper levels in the root of both ferns, when applied in the field, the
whole plant, including roots had to be harvested. The fern P. vittata evidently showed characteristics of
arsenic hyperaccumulator. Comparing to P. tripartita, it seemed to be more suitable for the purpose of
remediating arsenic contaminated soils despite smaller biomass.