The research paper on phytoremediation of heavy metals by Trifolium alexandrinum is well-written and informative. The authors have successfully demonstrated the effectiveness of using this plant species to extract heavy metals from contaminated soil. The methods used in the study were clear and well-detailed, making it easy to understand the process of phytoextraction.
One strength of the paper is the thorough analysis of the bioconcentration and translocation factors, providing quantitative data to support their conclusions. Additionally, the discussion of the limitations of phytoextraction, such as limited translocation of heavy metals from roots to shoots, shows a thoughtful consideration of the challenges faced in this remediation technique.
In terms of weaknesses, it would have been beneficial to include a discussion on the potential impacts of heavy metal accumulation in the plant tissues on animal or human health if these plants were to enter the food chain. Additionally, further research on how to improve the translocation of heavy metals in plants for more efficient remediation could be a valuable addition to the paper.
Overall, this paper aligns well with our group's research topic on phytoremediation and the use of plants to clean up contaminated sites. It provides valuable insights into the potential of Trifolium alexandrinum as a candidate species for phytoremediation efforts and encourages further exploration in this field.
eavy metals in inorganic form is a highly toxic to the natural environment and living organisms
including human.
Since industrialization and exploring of the natural resource like gold, coal, copper, petroleum
and natural gas, it has exposed many heavy metals to the natural environment.
Heavy metals are essentially non-biodegradable and therefore accumulate in the environment
and subsequently find their way into the food chains.
Contamination of food chains by toxic heavy metals is an unwanted outcome for industrialization
and an approach to unsustainable development.
This contamination is a serious risk to the health of all organisms. The entrance of toxic heavy
metals (through absorption, inhalation and ingestion) into the human body beyond threshold
limits causes many diseases and health abnormalities.
There, are many remediation techniques used to remove the heavy metals on the contaminated
sites, however, phytoremediation is considered to date the cheapest and easy technique with
plant in the contaminated sites to mitigate heavy metals.
The present study reports that phytoremediation of Cd, Pb, Cu, and Zn by Trifolium alexandrinum
is a suitable candidate plant species for this purpose. T. alexandrinum was grown in a simulated
heavy metal-contaminated soil.
Root Bioconcentration factor values of T. alexandrinum for the given heavy metals.Mining of severe valuable earths elements (gold and copper leads to
exposing of other heavy metals that contaminates the natural
environment.
As a result, these pollutants are accumulated by living organisms in
their bodies and subsequently biomagnified as they pass from one
trophic level to the next. Since man also is at the top of food chain, he
is vulnerable to heavy metal pollution.
Heavy metals comes in two forms; Essential heavy metals are those,
needed by living organisms for their growth, development and
physiological functions (Mn, Fe, Ni, Cu and Zn). And non-essential
heavy metals are not needed by living organisms for any physiological
functions like Cd, Pb, Hg and As.
Source: Google, Trifodium alexandrium
Hence, decontamination of contaminated soils is very vital for maintenance of environmental health and
ecological restoration.
Different methods (Physical & Chemical) are used and these methods are generally considered as destructive,
expensive, labor-intensive and causes secondary problems. However, Phytoextraction is the uptake of elements (heavy metals) or compounds (xenobiotic) from growth
media by plant roots and their translocation to the aerial parts (stem and leaves).
Phytoremediation is a novel, less expensive, efficient, environment- and eco-friendly remediation strategy
with good public acceptance. Phytoremediation technology is being established recently.
There are different techniques of phytoremediation; phytoextraction, phytofiltration, phytostabilization,
phytovolatilization and phytodegradation.
It is the best approach to remove contaminants primarily from soil and isolate them without destroying the
soil structure and its fertility.
In phytoremediation, two approaches are used:
(1) The application of hyperaccumulators (such as Thlaspi caerulescens or Alyssum bertolonii) producing a
relatively low amount of above ground biomass but accumulating high amounts of one or more elements.
(2) The application of high biomass producing plants characterized by lower ability to accumulate target elements
where total uptake of elements is comparable to that of hyperaccumulators due to high yield of above-ground
biomass.
Therefore, the author of the article presently investigate the phytoextraction of four selected heavy metals
(Cd, Pb, Cu and Zn) from simulated polluted soil by Trifolium alexandrinum, which is an herb belonging to the
family Fabaceae. It is cultivated as a fodder crop for cattle. It was selected because it is fast-growing, resistant
to pollution loads, produces high biomass and above all offers multiple harvests in a single growth period. According to the study, T. alexandrinum seeds were obtained from the local market for phytoextraction of Cd,
Pb, Cu and Zn. The methods followed were as follows;
Phytoextraction Experiments
Phytoextraction experiments were carried out in pots in greenhouse.
The contaminant soil samples were passes via 1 mm sieve and 6.5kg of
each contaminated are put in to the five pots and label accordingly as;
Cd contaminated, PB contaminated, Cu contaminated, Zn contaminated
and control were no contaminated were added.
The metals were added to the soil as their water-soluble salts in the
form of their aqueous solutions.
The concentration of metals added was 100 mg metal per kg of soil (100 ppm). Ten seeds of T.
alexandrinum were put into each pot. After 98 days, the mature plants were uprooted and separated into
roots, stem and leaves. These parts i.e., roots, stem, and leaves were used for the analysis of accumulated
heavy metals. The Analysis of Heavy Metals in Plants
Each plant part sampled were thoroughly washed with tap
water and then with distilled water in order to remove dust and
soil particles.
The clean plant parts were dried in an oven at 80°C for 48 hours.
0.5 g sample of the plant part was taken into a 100 mL beaker. 5
mL concentrated (65%) HNO3 and 2 mL HClO4 were added to it
and heated on hot plate until the digest became clear.
The digest was allowed to cool and then filtered through a
Whatman filter paper. The filtrate was collected in a 50 mL
volumetric flask and diluted to the mark with distilled water.
The filtrate was used for the analysis of heavy metals (Cd, Pb,
Cu, and Zn) by Atomic Absorption Spectrophotometer (AAS-700,
Perkin-Elmer, USA) using acetylene/air as gas mixture. The lamp
wavelength (λ) for Cd, Pb, Cu, and Zn was 228.8 nm, 283.3 nm,
324.8 nm, and 213.9 nm respectively. Calculation of Bioconcentration and Translocation Factors
Bioconcentration factor (BCF) indicates the efficiency of a plant in up-taking heavy metals from soil and
accumulating them into its tissues. It is a ratio of the heavy metal concentration in the plant tissue (root,
stem or leaves) to that in soil. Formula Used to calculate;
1. Bioconcentration factor (BCF)
BCF = Charvested tissue/Csoil
Where; Charvested tissue refers to the concentration of the target metal in the plant harvested tissue (roots, stem
or leaves) and Csoilrefers to the concentration of the same metal in soil.
1. Bioconcentration factor in percentage
BCF (%) = ( Cplant tissue/Ccoil ) x 100%
1. Translocation Factor
TF + Cshoots/Croots
NOTE: these formulae helps to determine how much metals is being accumulated in plant tissues relative to
the soil concentration.In conclusion, the authors aim was achieved that the T. alexandrinum effectively extracted the selected heavy
metals from the simulated heavy metal-contaminated soil as evident from the difference of heavy metal
concentration values between control and experimental plants. This is also clear from BCFroot values, which
are 4.242, 1.544, 1.071, and 0.604 for Zn, Pb, Cu, and Cd respectively. However, they mentioned that the
translocation of the accumulated heavy metals from roots to shoots was limited as seen from TF values for
these metals, which are less than 1 in all cases. This is one of the limitations usually encountered in
phytoremediation of toxic heavy metals. Hence, this limitation can be overcome by considering uprooting the
plants in which case the accumulated heavy metals in the roots are removed from the soil. Using T.
alexandrinum for phytoremediation has many advantages. One significant example given was as, it produces
considerable biomass, has a relatively short life cycle, is resistant to prevailing environmental and climatic
conditions and above all offers multiple harvests in a single growth period. Thus, the authors have strongly
agreed that this candidate species can be used for phytoremediation of toxic heavy metals.
The group must also provide a brief critique, general comment or reflection on the paper.
That is comment on the strength or weakness of the paper, if they like the paper or not
and why.
The comment on how the research paper relates to their group
research topics they have chosen.
1 answer