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. 2021 Apr 28;18(9):4682.
doi: 10.3390/ijerph18094682.

Invasive Weed Asystasia gangetica as a Potential Biomonitor and a Phytoremediator of Potentially Toxic Metals: A Case Study in Peninsular Malaysia

Chee Kong Yap  1 , Weiyun Chew  1 , Khalid Awadh Al-Mutairi  2 , Salman Abdo Al-Shami  3 , Rosimah Nulit  1 , Mohd Hafiz Ibrahim  1 , Koe Wei Wong  1 , Alireza Riyahi Bakhtiari  4 , Moslem Sharifinia  5 , Wan Hee Cheng  6 , Hideo Okamura  7 , Mohamad Saupi Ismail  8 , Muhammad Saleem  9
Affiliations

Invasive Weed Asystasia gangetica as a Potential Biomonitor and a Phytoremediator of Potentially Toxic Metals: A Case Study in Peninsular Malaysia

Chee Kong Yap et al. Int J Environ Res Public Health. .

Abstract

The invasive weed Asystasia gangetica was investigated for its potential as a biomonitor and as a phytoremediator of potentially toxic metals (PTMs) (Cd, Cu, Ni, Pb, and Zn) in Peninsular Malaysia owing to its ecological resistance towards unfavourable environments. The biomonitoring potential of PTMs was determined based on the correlation analysis of the metals in the different parts of the plant (leaves, stems, and roots) and its habitat topsoils. In the roots, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 2.18, 9.22 to 139, 0.63 to 5.47, 2.43 to 10.5, and 50.7 to 300, respectively. In the leaves, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 1.16, 7.94 to 20.2, 0.03 to 6.13, 2.10 to 21.8, and 18.8 to 160, respectively. In the stems, the concentrations (mg/kg dry weight) of Cd, Cu, Ni, Pb, and Zn ranged from 0.03 to 1.25, 5.57 to 11.8, 0.23 to 3.69, 0.01 to 7.79, and 26.4 to 246, respectively. On the other hand, the phytoremediation potential of the five metals was estimated based on the bioconcentration factor (BCF) and the translocation factor (TF) values. Correlation analysis revealed that the roots and stems could be used as biomonitors of Cu, the stems as biomonitors of Ni, the roots and leaves as biomonitors of Pb, and all three parts of the plant as biomonitors of Zn. According to the BCF values, in the topsoil, the "easily, freely, leachable, or exchangeable" geochemical fractions of the five metals could be more easily transferred to the roots, leaves, and stems when compared with total concentrations. Based on the TF values of Cd, Ni, and Pb, the metal transfer to the stems (or leaves) from the roots was efficient (>1.0) at most sampling sites. The results of BCF and TF showed that A. gangetica was a good phytoextractor for Cd and Ni, and a good phytostabilizer for Cu, Pb, and Zn. Therefore, A. gangetica is a good candidate as a biomonitor and a phytoremediator of Ni, Pb, and Zn for sustainable contaminant remediation subject to suitable field management strategies.

Keywords: biomonitoring; invasive weeds; phytoremediation; potentially toxic metals.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Sampling sites in Peninsular Malaysia (list of sampling sites as in Table 1).
Figure 2
Figure 2
Mean concentrations (mg/kg dry weight) of Cd in the plant parts (Y-axes) and topsoils (total concentration (AR), and geochemical easily, freely, leachable, or exchangeable (EFLE) fractions; ecological risk index (ERI)) in all 23 sampling sites (X-axes). Y-axes for EFLE and AR are drawn based on a logarithmic scale.
Figure 3
Figure 3
Mean concentrations (mg/kg dry weight) of Cu in the plant parts (Y-axes) and topsoils (total concentration (AR), and geochemical easily, freely, leachable, or exchangeable (EFLE) fractions; ecological risk index (ERI)) in all 23 sampling sites (X-axes). Y-axes for EFLE and AR are drawn based on a logarithmic scale.
Figure 4
Figure 4
Mean concentrations (mg/kg dry weight) of Ni in the plant parts (Y-axes) and topsoils (total concentration (AR), and geochemical easily, freely, leachable, or exchangeable (EFLE) fractions; ecological risk index (ERI)) in all 23 sampling sites (X-axes). Y-axes for EFLE and AR are drawn based on a logarithmic scale.
Figure 5
Figure 5
Mean concentrations (mg/kg dry weight) of Pb in the plant parts (Y-axes) and topsoils (total concentration (AR), and geochemical easily, freely, leachable, or exchangeable (EFLE) fractions; ecological risk index (ERI)) in all 23 sampling sites (X-axes). Y-axes for EFLE and AR are drawn based on a logarithmic scale.
Figure 6
Figure 6
Mean concentrations (mg/kg dry weight) of Zn in the plant parts (Y-axes) and topsoils (total concentration (AR), and geochemical easily, freely, leachable, or exchangeable (EFLE) fractions; ecological risk index (ERI)) in all 23 sampling sites (X-axes). Y-axes for EFLE and AR are drawn based on a logarithmic scale.
Figure 7
Figure 7
Bioaccumulation factors (BCFs) and translocation factors (TFs) (y-axis) of Cd in all sampling sites (x-axis). Note: BCF (Root) = BCF-1root; BCF (Root EFLE) = BCF-2root; BCF (Leaf) = BCF-1leaf; BCF (Leaf EFLE) = BCF-2leaf; BCF (Stem) = BCF-1stem; BCF (Stem EFLE) = BCF-2stem; TF (Stem/Root) = TF-1; TF (Leaf/Root) = TF-2.
Figure 8
Figure 8
Bioaccumulation factors (BCFs) and translocation factors (TFs) (Y-axes) of Cu in all sampling sites (X-axes). Note: All Y-axes are drawn based on logarithmic scale. BCF (Root) = BCF-1root; BCF (Root EFLE) = BCF-2root; BCF (Leaf) = BCF-1leaf; BCF (Leaf EFLE) = BCF-2leaf; BCF (Stem) = BCF-1stem; BCF (Stem EFLE) = BCF-2stem; TF (Stem/Root) = TF-1; TF (Leaf/Root) = TF-2.
Figure 9
Figure 9
Bioaccumulation factors (BCFs) and translocation factors (TFs) (Y-axes) of Ni in all sampling sites (X-axes). Note: All Y-axes are drawn based on logarithmic scale. BCF (Root) = BCF-1root; BCF (Root EFLE) = BCF-2root; BCF (Leaf) = BCF-1leaf; BCF (Leaf EFLE) = BCF-2leaf; BCF (Stem) = BCF-1stem; BCF (Stem EFLE) = BCF-2stem; TF (Stem/Root) = TF-1; TF (Leaf/Root) = TF-2.
Figure 10
Figure 10
Bioaccumulation factors (BCFs) and translocation factors (TFs) (Y-axes) of Pb in all sampling sites (X-axes). Note: All Y-axes are drawn based on logarithmic scale. N = 23. BCF (Root) = BCF-1root; BCF (Root EFLE) = BCF-2root; BCF (Leaf) = BCF-1leaf; BCF (Leaf EFLE) = BCF-2leaf; BCF (Stem) = BCF-1stem; BCF (Stem EFLE) = BCF-2stem.
Figure 11
Figure 11
Bioaccumulation factors (BCFs) and translocation factors (TFs) (Y-axes) of Zn in all sampling sites (X-axes). Note: All Y-axes are drawn based on logarithmic scale. BCF (Root) = BCF-1root; BCF (Root EFLE) = BCF-2root; BCF (Leaf) = BCF-1leaf; BCF (Leaf EFLE) = BCF-2leaf; BCF (Stem) = BCF-1stem; BCF (Stem EFLE) = BCF-2stem.
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