1. Nickel mining poses a serious environmental problem due to run-offs and tailings.
2. Current techniques for remediation include excavation, chemical stabilization, and soil flushing, but they are costly and impractical.
3. Phytoremediation is an ecologically acceptable and cost-effective method using hyper-accumulator plants to remediate contaminated soils.
4. Centella asiatica (gotu kola) is a plant with the potential to thrive in moist soils with domestic effluents and accumulate heavy metals like copper, lead, and zinc.
5. The study aimed to evaluate the phyto-remediation potential of Centella asiatica in nickel-rich bio-ore contaminated soils from the Carrascal Nickel Mining Site in Surigao del Sur, Philippines.
6. The results showed that Centella asiatica has the potential to survive in nickel-contaminated conditions, as indicated by relative growth close to 1.
7. Atomic Absorption Spectrometer (AAS) results demonstrated a greater decrease in soil nickel content and an increase in nickel accumulation in the plant samples in nickel-ore contaminated soils compared to control soils.
8. Contamination factor values indicated very high contamination for both soil and plant samples (CF > 6).
9. SHAPE software analysis revealed no variations in leaf shape between control and treatment setups, suggesting the tolerance-accumulating mechanism of Centella asiatica.
10. These results suggest that Centella asiatica may exhibit phyto-remediation potential for nickel-ore contaminated soils.
1. The plant species C. asiatica is being studied for its potential in phytoremediation, specifically in the accumulation of copper, lead, and zinc in contaminated media.
2. The study focuses on assessing the plant's ability to survive and accumulate nickel in contaminated soil.
3. Two sites were selected for the study: a nickel mining site in Carrascal, Surigao del Sur, Philippines, and natural dwelling soils of C. asiatica in Iligan City, Philippines.
4. Relative growth assessment was conducted to evaluate the plant's ability to survive in nickel-contaminated soil and initial nickel toxicity.
5. Soil samples were collected from both sites and air-dried for analysis.
6. After 21 days of exposure to contaminants, C. asiatica plants were harvested, washed, and prepared for analysis.
7. The bioaccumulation capacity of nickel was assessed using Atomic Absorption Spectrometer (AAS) on soil and plant samples.
In summary, the study aims to investigate the potential of C. asiatica in accumulating heavy metals like copper, lead, zinc, and nickel in contaminated media through phytoremediation techniques.
1. Soil sample drying and analysis: 100g of soil samples were dried in an oven at 105°C for 6 hours, then crushed and analyzed for nickel (Ni) concentration using calibration curves of standard solutions.
2. Contour information and Elliptic Fourier Descriptors (EFDs): The contours of objects were described using chain code, which was then transformed into a Normalized Elliptic Fourier file with Che2Nef using 20 harmonics. EFDs, originally proposed by Kuhl & Giardina (1982), can delineate any type of shape with a closed two-dimensional contour.
3. Contamination Factor (CF) evaluation: The CF was used to assess soil contamination by comparing concentrations in the surface layer to background values. The expression for CF is $CF = \frac{C_a}{C_b}$, where $C_a$ is the mean concentration of individual metals from all test sites and $C_b$ is the baseline or background concentration of the individual metal. CF was categorized into four categories: low contamination factor (CF < 1), moderate contamination factor (1 < CF < 3), considerable contamination factor (3 < CF < 6), and very high contamination factor (6 < CF).
4. Shape analysis: The outline of leaf samples from nickel-ore contaminated soils and background soils was analyzed using the chain coding technique with the software package SHAPE v.1.3 (Iwata & Ukai, 2002). Relative plant growth was evaluated as a parameter to assess the plant's ability to survive in heavy-metal contaminated conditions.
5. Principal Component Analysis (PCA) and Multivariate Analysis of Variance (MANOVA)/Canonical Variate Analysis (CV A): PCA was performed on the variance-covariance matrix of normalized coefficients (elliptic Fourier descriptors) using Prin Comp to obtain a graphical output of the average shape and standard deviation. MANOVA/CVA was conducted using PAST ver.1.91 as a platform to determine if populations differ significantly based on shell shape, with Wilks' lambda, Pillai trace values, and p-values obtained.
In summary, the main points involve soil sample drying and analysis for nickel concentration, utilizing Elliptic Fourier Descriptors for contour information, evaluating Contamination Factor for soil contamination assessment, conducting shape analysis on leaf samples from contaminated and background soils, performing Principal Component Analysis on normalized coefficients, and applying Multivariate Analysis of Variance/Canonical Variate Analysis to determine population differences based on shell shape.
1. The experiment involves studying the growth and nickel accumulation of Centella asiatica plants in nickel-contaminated and background soils. The plants' relative growth rates are close to 1, indicating their ability to survive in both contaminated and background soil conditions.
2. Table 1 presents the initial and final wet weights of C. asiatica new shoots after exposure to nickel-contaminated soils for 7, 14, and 21 days. The computed relative growth rates for different replicates (R1, R2, R3) in nickel-ore contaminated soils are 1.30, 1.47, and 1.15 respectively.
3. Table 2 shows the initial and final nickel concentrations in soil samples after treatment with C. asiatica plants in both nickel-ore contaminated soils and background soils (control). The computed difference between initial and final nickel soil content is higher in nickel-ore contaminated soils compared to background soils.
4. Table 3 presents the nickel content in C. asiatica after treatment with different replicates (R1, R2, R3) in both nickel-ore contaminated soils and background soils (control). The mean nickel content is significantly higher in plants grown in nickel-ore contaminated soils compared to those grown in background soils.
5. Table 4 provides the Contamination Factor (CF) for plant and soil samples based on their respective nickel contents.
6. MANOVA results from Table 5 indicate that there is no significant difference between the two populations of C. asiatica based on their significant relative warp (RW).
7. Overall, the study suggests that C. asiatica has potential for use as a phytoremediation system plant due to its ability to accumulate acceptable amounts of metals while surviving in contaminated conditions.
8. The elevated levels of nickel present in the treatment soil indicate successful phytoremediation by C. asiatica as mentioned by Quian et al., Garbisu et al., Ghosh et al., Mokhtar et al., Aurangzeb et al., J Bio Env Sci (2018), which supports its suitability as a control or reference site for environmental remediation efforts.
1. The study demonstrates the bioaccumulation activity of C. asiatica when introduced in nickel-ore contaminated soils, as evidenced by a substantial reduction of 798 mg/kg in soil nickel content compared to a slight decrease in control soils (9.1 mg/kg).
2. The range of nickel accumulation in plant samples was higher in treatment soils than in control soils, with the highest concentration of Ni (432.0 mg/kg) found in C. asiatica harvested from nickel-ore contaminated soils.
3. The higher nickel removal at greater concentrations of Ni in soils is attributed to the loading effect, where sorption sites are saturated by nickel at the highest concentration (Mokhtar et al., 2011a, b).
4. The metal concentration in plants is proportional to the extractability of the metal in the soil, as stated by Robinson (1997).
5. Nickel toxicities occur in woody plants if tissue levels exceed 80-120 ppm, and sensitive plants like tomato may exhibit toxicities above 10 ppm in their tissues.
6. Plants can achieve heavy metal resistance through avoidance and tolerance mechanisms. Avoidance prevents metal ions from entering cellular cytoplasm, while tolerance detoxifies metal ions that have crossed plasma membrane or internal organelle bio membranes (Mehis-Smith et al., 2013).
7. Strategies used by plants in metalliferous soils fall into three categories: metal immobilization, chelation, and compartmentalization (Wei et al., 2005).
1. C. asiatica exhibits high levels of nickel tolerance, allowing it to survive in nickel-contaminated soil.
2. The plant utilizes an accumulating physiological strategy by accumulating nickel in its harvestable biomass.
3. Vegetation covers like C. asiatica can be established on highly contaminated landfills and tailings, as stated by Favas et al. (2014).
4. Shape analysis using SHAPE v.1.3 software by Iwata & Ukai (2002) revealed ten significant principal components (PCs) that defined shape differences between the two populations.
5. Contamination Factors (CF) were calculated for both plant and soil samples, indicating very high contamination factors (6 < CF) for both soil and plant samples.
6. The obtained value (p = 0.155 at α = 0.05) indicates no significant difference in terms of C. asiatica leaf sample shapes after being planted in two conditions: nickel ore contaminated soils and background soils.
In summary, the information above highlights the nickel tolerance of C. asiatica, its ability to accumulate nickel in its biomass, and its establishment on highly contaminated landfills and tailings. Additionally, shape analysis using principal components revealed significant differences between the two populations, while contamination factors indicated high levels of contamination in both soil and plant samples. Finally, there was no significant difference observed in leaf sample shapes when planted in different conditions with varying levels of nickel contamination.
Write a brief Critique using the information given above
The study on the phytoremediation potential of Centella asiatica in nickel-ore contaminated soils provides valuable insights into the plant's ability to survive and accumulate heavy metals. The research design was thorough, incorporating various techniques like soil sample analysis, shape analysis, and contamination factor evaluation. The results suggest that C. asiatica shows promise in remediation efforts due to its ability to tolerate and accumulate nickel in contaminated soils.
One area for improvement could be the discussion of potential limitations or challenges faced during the study. Additionally, further research could focus on long-term effects of nickel accumulation in C. asiatica, as well as potential impacts on surrounding ecosystems. Overall, the study contributes valuable information to the field of phytoremediation and highlights the potential of C. asiatica as a viable solution for remediation of nickel-contaminated soils.
Bot GPT 3.5