Potential Role of Combined Microbial Inoculants and Plant of Limnocharis flava on Eliminating Cadmium from Artificial Contaminated Soil
, Shaoxian Song 1,3, Bui Thi Ngoc Dung 4, Tran Ngoc Binh 5, Afshin Maleki 6, Kazem Godini 6 and Van Tai Tang 7,*
Round 1
Reviewer 1 Report
This paper presents interesting results on cadmium removal from soil using the combination of inoculants and L. flava plants. The work is very much useful for the researchers working in environmental science and agricultural science. The paper is original and well written. It is worth to publish.
In the discussion section, authors may address how to improve the removal rate of cadmium further.
Author Response
We thank the reviewers for providing us constructive suggestions. We have thoroughly checked the manuscript for grammatical mistake, sentence structure, consistency errors and modified the manuscript accordingly. Kindly find the responses below against the specific comments. All corrections have marked in yellow colour.
Authors’ response to the comments from the reviewers
Reviewer #1:
This paper presents interesting results on cadmium removal from soil using the combination of inoculants and L. flava plants. The work is very much useful for the researchers working in environmental science and agricultural science. The paper is original and well written. It is worth to publish
Comment 1: In the discussion section, authors may address how to improve the removal rate of cadmium further.
Author’s response: Thank you very much. As suggested, the content is added to the Results and discussion section, “It was found that an increase of plant biomass and the growth of fungi and microorganisms had close relationship to the Cd accumulation in the plant particle. Hence, the nutrient, moisture and pH need to be adjusted in their optimum value to fit on the development of plant, bacteria and fungi, thereby increasing removal Cd from in soil [15, 29, 30].”
Reviewer 2 Report
The manuscript Potential Role of Combined Microbial Inoculants and plant of Limnocharisflava on Eliminating Cadmium from Artificial Contaminated Soil aims to investigate the possibility of eliminating cadmium (Cd) from contaminated agricultural soil using the combination of microbial inoculants Penicillium chrysogenum fungus and Bacillus licheniformis with Limnocharisflava plants. Limnocharisflava and microbial inoculants at four Cd levels, including 2.05 (background), 5, 10 and 20 mg / kg.
It is an interesting proposal to solve the difficult problem of environmental contamination with heavy metals. It is a pity that these are not universal methods that can be used in every region of the world.
Accepts the content of the manuscript without content-related corrections.
Author Response
We thank the reviewers for providing us constructive suggestions. We have thoroughly checked the manuscript for grammatical mistake, sentence structure, consistency errors and modified the manuscript accordingly. Kindly find the responses below against the specific comments. All corrections have marked in yellow colour.
Reviewer 3 Report
Comments to the Author
In recent years, soil heavy metal cadmium pollution has increasingly become a research hotspot for researchers, and ecological restoration measures have also become one of the first restoration measures. Since heavy metal contamination has also been prevalent in Vietnam because of the dominance of agricultural activities. It was hypothesized that the combined microbial inoculants with L. flava plants might be effective on eliminating Cd from contaminated soil for safe crop production. Therefore, this is a work of great research significance. It is recommended to receive after minor revisions.
I addressed followings for your consideration after I read it carefully:
Don't see your scientific hypothesis and scientific question in the preface of your current paper? Please be more explicit.
The current M &M section is lack of detailed and clear information, e.g.
1) Line 155, Please explain what the numbers after the formula mean? I don't understand this formula.
2) L187, In the 2.4 Statistical analysis section, have the experimental data been tested for normal distribution and homogeneity? What methods were used? Please add in this section.
Results and discussion, e.g.
1) In this part, did not see how to deal with the plants after repairing heavy metal pollution? What should I do with the restored plants? please add in.
Author Response
We thank the reviewers for providing us constructive suggestions. We have thoroughly checked the manuscript for grammatical mistake, sentence structure, consistency errors and modified the manuscript accordingly. Kindly find the responses below against the specific comments. All corrections have marked in yellow colour.
Comment 1: Don't see your scientific hypothesis and scientific question in the preface of your current paper? Please be more explicit.
Author’s response: Thank you very much. As suggested, the content is added into Introduction, /to meet the require of Comment 1 from the reviewer: “Along with rapid economic development, the construction of concentrated industrial zones, medical facilities and the expansion of agricultural production areas produce huge quantities of wastes containing heavy metals and other hazardous substances [1]. Heavy metal compounds in untreated or poorly waste sources are gradually accumulated in soil [2]. The problem will become acute especially when agricultural lands are contaminated with heavy metals, which can pose a direct threat to human health [3].. Hence, Environmental protection and food safety are serious matters of urgency for each country [2, 3]. Many countries in the world are facing problems of toxic metal pollution in agricultural soil [1, 3]. Cadmium (Cd) in soil causes food contamination, thereby damag-ing human health through the food chain [1, 4]. Cd is a typical heavy metal that exhibits toxicity due to continuous accumulation in the environment. Cumulative tendency of this element in biomass and food chain poses a serious threat to plants, animals, and humans even at low concentrations [2]. Therefore, to maintain a safe food chain, and a healthy ag-ricultural ecosystem, the removal of Cd from agricultural soil is essential [2]. In practice, the treatment of soil contaminated with heavy metals, particularly at a large scale, is a very difficult, expensive and technically demanding procedure [2-4]. Therefore, The use of microorganisms or plants to treat heavy metals is a relatively cheap, safety and effective method [5, 6]. In this context, the combination of microorganisms, plants were used to restore the polluted environment to the original state [5]. In particular, the combination of plants and microor-ganisms is not only a means of promoting Cd removal [6], but also a way of increasing the activity and diversity of microorganisms in soil leading to a healthy ecosystem.
Comment 2: Line 155, Please explain what the numbers after the formula mean? I don't understand this formula.
Author’s response: Thank you very much for the suggestion. The formula was explained again as:
M (mg/kg) = (M1-M2) * 113/204 (1)
where, M is the amount of Cd to be added to the soil, M1 is the desired exprimental concentration of Cd in soil (5, 10, 20 mg/kg Cd) and M2 is the concentration of available Cd in the natural soil (Cd content of T1).
Comment 3: L187, In the 2.4 Statistical analysis section, have the experimental data been tested for normal distribution and homogeneity? What methods were used? Please add in this section
Author’s response: It should be pointed out that the comment by the reviewer is true. In our study, all of the variables like the initial concentration of the pollutant (Cd concentration) do not need to checked for distribution normality because the before and after conversations of the treatment are determined. And, in order to decline uncertainty, each experiment is repeated for three or four times. What’s more, it is very difficult to perform the test of distribution normality as, in this case, a lot of experiments will be needed that make it nearly impossible in terms of economic aspects. Yes; for dependent variables like the rate of stroke and smoking, analysis of variance or regression should be done and the data must follow the distribution normality. In our study, we only reported the means and showed the error bars on the diagrams. Of course, the statistical tests mentioned in the statistical section were applied to know that it was a significant difference between any variables like the initial concentration of Cd.
“The correlation matrix analysis revealed that ED was 0.95 positively correlated with IED. While, PH had negative -0.83 correlation with IED and -0.86 with ED, respectively. However, BM was observed negatively correlated -0.61 with IED and -0.62 with ED, whereas the positive correlation among BM was noted 0.93 with PH. It was observed that an increase of Cd containing by L. Flava had negative impact on ED and PH. The Cd ac-cu-mulation could effect on nutrient uptake and photosynthetic performance in L. Flava plant [36]. Sun et al. [36] indicated that the decrease of K+ concentration in Cucumis sativus stems was observed 7.4, 14.1, 26.9, 38.9 and 48.8% with application of 10, 25, 50, 100 and 200 µM Cd treatments. The Cd containing in IED and ED was possible to inhibit plant growth by decreasing the water-use efficiency and the net rate of photosynthesis in L. Fla-va. The results revealed that the Cd containing in L. flava was restricted the develop-ment of plant. Bahadur et al. [37] observed positive correlation among Cd content in maize shoot and Cd in heavily and low polluted soils.”
Author’s response: Thank you very much for the question.
Comment 4: In this part, did not see how to deal with the plants after repairing heavy metal pollution? What should I do with the restored plants? please add in
Author’s response: The authors agree with the reviewer’s comment. The following explanation was added:
“Cd accumulation in the edible parts of L. flava planting in soil containing heavy metal of T1 (2.05 mg/kg) and T2 (5 mg/kg) case was below the safety limit threshold under the QCVN 8-2: 2011/BYT and the FAO/WHO, which is safe for using in human food. In contrast, in the case of soil containing heavy metal of T3 (10 mg/kg), Cd accumulation in the edible parts of L. flava was weakly over the safety limit threshold, which can be used for animal consumption. In the T4 (20 mg/case) exprimetal case, Cd accumulation in the edible parts of L. flava exceeded the allowable limit more than 8 time that need be collected for centralized treatment or landfill, according to the processing procedure of enviroment government agencies.”.
