This study on the accumulation of heavy metals in Centella asiatica in metal-contaminated soils is comprehensive and well-conducted. The researchers provided detailed methods and results, including tables with clear and organized data presentation. The study effectively establishes the potential of C. asiatica as a biomonitoring plant for heavy metal pollution, highlighting its ability to accumulate heavy metals in different plant parts.
The findings regarding the distribution of heavy metals in roots, stems, and leaves of C. asiatica provide valuable insights into the plant's physiological processes and behavior in polluted environments. Additionally, the discussion on metal accumulation strategies and the factors influencing absorption and accumulation in plant tissues adds depth to the study.
The study's implications for phytoremediation and environmental monitoring are significant, as C. asiatica shows promise as a bioaccumulator of heavy metals. The potential for using the plant in biomonitoring work to assess changes in heavy metal contamination over time is particularly noteworthy.
Overall, this study contributes valuable information to the field of phytoremediation and environmental science, and the thoroughness of the research methodology and data analysis enhances the credibility and reliability of the findings. Further studies building on this research could yield even more valuable insights into the use of C. asiatica in addressing heavy metal pollution.
This study investigates the effects of metal-contaminated soils on the accumulation of heavy metals in different parts of Centella asiatica, a medicinal plant widely used in Malaysia and other parts of the world. The researchers conducted a laboratory study to determine the growth and uptake of heavy metals by C. asiatica exposed to different treatments of metal-contaminated soils. The study found that the metal uptake capacity followed the order: roots > stems > leaves. Additionally, a close positive relationship was established between the concentrations of metal accumulated in different parts of the plant and the metal levels in the most contaminated soil. The researchers suggest that C. asiatica has the potential to as a biomonitoring plant for heavy metal pollution in polluted soils.
The main points of the provided information are:
1. Centella asiatica (L.), also known as Pegaga, is an important medicinal plant with various therapeutic properties, including antileprotic, antistress, antitumor, antiulcerogenic, antibacterial, antifungal, and wound healing properties. It is native to India, China, Indonesia, Sri Lanka, Australia, Madagascar, Southern and Central Africa, and is used as a tonic in Ayurvedic formulations.
2. The plant possesses long string-shaped stolons with roots at each node and can reproduce both through vegetative and sexual means. There is no study on heavy metals in C. asiatica, so the objective of the study was to determine the accumulation of heavy metals in different parts of C. asiatica exposed to different treatments with polluted soil under laboratory conditions.
3. The study was conducted in a greenhouse using healthy plants uniform in size and color, which were placed in polystyrene pots filled with a garden soil mixture (loam soil: fertilizer: sand) in the ratio 32:1. The soil treatment followed the modified method of Monise and2006), and three replicates for each treatment were used. The plants were watered once every two days and care was taken to avoid leaching of water from the pots by keeping a plastic tube below each pot to collect the leachates, which were again returned to the experimental pots. The plants were harvested after 8 weeks for metal analysis.
4. The easily, freely, leachable or exchangeable fraction (ELFE) of heavy metal concentrations were determined using the procedure described by Badri and Aston (1983). The soil samples were dried at 105°C for at least 16 hours until constant dry weights, crushed by using a pestle and mortar to a size that can pass through a 63 μm stainless steel sieve under vigorously shaking to produce a homogeneous sample. In order to determine the ELFE, 10 of dried samples were continuously shaken at 200 rpm for 3 hours with 50 ml 1.0 M ammonium acetate (NH4CHCOO), pH 7.0 at room temperature. Then, it was filtered through a Whatman No 1 filter paper into an acid-washed pill box. Erlenmeyer flask was washed with 20 ml double de-ionized water and filtered with filter paper (Whatman No 1.) into the box.
5. The plants were washed with distilled water and carefully dissected into roots, stems, and leaves. The separated parts were then dried in the oven for 72 hours at 105°C until constant dry weights. The weighted dried plant parts were placed in digestion tubes and 10 mL of concentrated HNO3 (AnalaR grade, BDH 69%) was added. The tubes were put onto a hot block digester at 40°C for 1 hour and the contents were fully digested at 140°C for 3 hours and then were filtered through a Whatman No.1 filter paper in a funnel. The filtered solution was collected in an acid-washed pill box. All the prepared samples were determined for heavy metals by using an air-acetylene flame Atomic Absorption Spectrophotometer (AAS) (Perki 1-Elimer A.Analyst 800). The data were presented in dry weight basis. Certified Reference Materials for Soil (International Atomic Energy Agency, Soil-5, Vienno, Austria) were also run, and the recoveries for Cd, Cu, Fe, Ni, Pb, and Zn were satisfactory (90-105%).
6. The One-way ANOVA based on Turkey HSD multiple homogeneous subset was performed by using SPSS version 12.
7. From Table 2, it can be seen that the highest levels of Cd, Cu, Fe, Ni, Pb, and Zn were found in the soil of Treatment D. As expected, Treatment D (100% contaminated soils) had higher metal levels when compared to Treatment C (50% contaminated soil) and Treatments B (25% contaminated soil). This result indicated that Treatment D with 100% contaminated soil is the most metal-polluted soils among all the treatments investigated.
The main points from the provided information are as follows:
1. Heavy metal concentrations in the EFLE fractions of soils from different treatments are listed in TABLE2. The mean concentrations of heavy metals, along with their standard errors, are provided for each treatment (T-A, T-B, T-C, and T-D) for Cd, Cu, Fe, Ni, Pb, and Zn.
2. The heavy metal concentrations in the roots, stems, and leaves of Centella asiatica are given in TABLE3, TABLE4, and TABLE5, respectively. Treatment D was found to have the highest levels of Cd, Cu, Fe, Ni, Pb, and Zn in the roots, stems, and leaves compared to the other treatments.
3. For Zn concentrations, only treatments C and D showed the highest levels in the roots. This indicates that, in general, roots had higher concentrations of heavy metals compared to the stems and leaves.
4. Metal redistribution in polluted treatments was observed. For example, Cd concentrations were redistributed in Treatment D, where leaves had higher Cd levels than the roots and stems. Similarly, for Cu, the stem had higher levels than the leaves in Treatment D.
5. From TABLE6, the concentrations of Cu, Fe, and Ni were found to be the highest in the roots for all four different treatments. On the other hand, the concentrations of Cd and Pb were found to be the highest in the roots for two out of four treatments.
6. TABLE3 and TABLE4 provide the mean concentrations of heavy metals in the roots and stems of Centella asiatica for all treatments after 8 weeks. Different letters in the same column indicate significant differences at the 0.05 level according to the protected Tukey HSD Multiple Homogeneous Subset test.
Based on the provided tables and notes, here are the main points:
1. Heavy metal concentrations in Centella asiatica leaves after 8 weeks:
* Different letters in the same column indicate significant differences at the 0.05 level according to the protected Tukey HSD Multiple Homogeneous Subset.
* BDL stands for Below Detection Limit.
2. Mean concentrations of heavy metals in the leaves of Centella asiatica for all treatments after 8 weeks:
* A: Cd - $0.79^{2}$, Cu - $4.88^{\circ }$, Fe - $509.3^{2}$, Ni - $BDL^{a}$, Pb - $7.21^{2}$, Zn - $144^{a}$
* B: Cd - $1.25^{\circ }$, Cu - $16.2^{h}$, Fe - $1282^{d}$, Ni - $BDL^{=}$
* C: Cd - $1.24^{\circ }$, Cu - $13.5^{h}$, Fe - $915 BDL: $11.0^{\circ }$, Ni - $284^{\circ }$, Pb - $8.01^{2}$, Zn - $19.9^{\circ }$, Hg - $674^{h}$, BDL - $20.9^{4}$, Ni - $383^{d}$
3. Order of different parts based on metal concentrations of Centella asiatica for all treatments after 8 weeks:
* A: Cd - Roots> Stems> Leaves, Cu - Roots> Leaves> Stems, Fe - Roots> Leaves> Stems, Ni - Roots> Stems> Leaves, Pb - Roots> Stems> Leaves, Zn - Roots> Leaves> Stems
* B: Cd - Roots> Leaves> Stems, Cu - Roots> Stems> Leaves, Fe - Roots> Leaves> Stems, Ni - Roots> Stems> Leaves, Pb - Roots> Stems> Leaves, Roots> Leaves> Stems
* C: Cd - Roots> Leaves> Stems, Cu - Roots> Stems> Leaves, Fe - Roots> Leaves> Stems, Ni - Roots> Stems> Leaves, Pb - Roots> Stems> Leaves, Zn - Roots> Leaves> Stems
* D: Cd - Roots> Stems> Leaves, Cu - Roots> Leaves> Stems, Fe - Roots> Leaves> Stems, Ni - Roots> Stems> Leaves, Pb - Roots> Stems> Leaves, Zn - Roots> Stems> Leaves
In summary, the tables and notes provide information on the mean concentrations of heavy metals in the leaves of Centella asiatica for different treatments after 8 weeks. The order of different parts based on metal concentrations is also provided.
The main points of the provided information are:
1. C. asiatica can be used as a biomonitoring plant for heavy metal pollution in polluted soils due to its ability to accumulate heavy metals in its different plant parts.
2. Heavy metals tend to accumulate more in the roots of C. asiatica compared to stems and leaves, making the roots the primary entry point for heavy metals affecting various physiological processes.
3. The accumulation strategy involves physiological processes that maintain intra-cellular heavy metal ions in non-toxic forms, and stored heavy metal ion complexes may be removed by leaf fall.
4. Essential metals like Cu, Fe, and Zn are highly accumulated in the roots, followed by stems and leaves of C. asiatica.
5. The stems of C. asiatica accumulate a high level of Fe, which is easily soluble and plants may take up a very large amount of Fe.
6. The absorption and accumulation of heavy metals in plant tissues depend upon many factors, such as temperature, moisture, organic matter, pH, and nutrient availability.
7. The high potential of metal accumulation by C. asiatica in polluted soils indicates that the plant is a good source for bioaccumulation of heavy metals and therefore suitable for phytoremediation.
8. The study using C. asiatica as a biomonitor provides important baseline information which can be used to monitor changes in heavy metal contamination and bioavailability.
9. Further studies by using the plant parts and their growth for biomonitoring work are useful and should be conducted regularly.
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