An Efficient Method for Detoxification of Organophosphorous Pesticide-Contaminated Soil with Ozonation in Fluidized Bed Reactor
, Radosław Józefczyk 2 and Karolina Kowalczyk 1
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsLine 90:
Please, add the information how have you conducted the pesticide application, the rate, the method and etc.
Line 129:
Extraction of pesticides and GC-MS analysis
Detection limit, calibration over which ranges, mass spectrometry settings, mode, parent and daughter ion species.
Line 162:
Why you didn’t use OECD Tests for Eisenia foetida (№ 207 and 222)?
Line 184:
«Fiures»
Line 186:
Please, add the standard deviations.
Line 204:
It is absolutely mandatory to add the standard deviations to the half-life times presented in Table 1. The absence of this information greatly weakens the results of the study because it makes it more difficult to interpret the data. Since the authors specify that the dissipation studies of the compounds studied all follow first-order kinetics, it is necessary to change Half-life time by t1/2 in Table 1.
Line 259:
Add the caption to Fig.5
Author Response
Line 90:
Please, add the information how have you conducted the pesticide
application, the rate, the method and etc.
Action taken: the description of soil spiking with pesticide was provided in section: 2.3. Soil matrix preparation
“The soil was spiked with pesticide solution in acetone. The solution was mixed within the soil sample and it was allowed to dry before the experiment.”
Line 129:
Extraction of pesticides and GC-MS analysis
Detection limit, calibration over which ranges, mass spectrometry
settings, mode, parent and daughter ion species.
Action taken: new comments were introduced in sections: 2.5.1. Extraction of pesticides and GC-MS analysis, and 2.5.2. Detector calibration
“During the analysis the electron ionization method, 70 eV, full scan mode in the range of 5-500 m/z was used.”.
“The estimated limit of quantification (LOQ) was 1 mg/kg, and the limit of detection (LOD) was 0.03 mg/kg”
Line 162:
Why you didn’t use OECD Tests for Eisenia foetida (№ 207 and 222)?
Action taken: new comments were introduced in section: 2.7. Toxicity tests:
“In this study the authors utilized acute and chronic toxicity tests based on (OECD 207 I 222 with modification proposed by Józefczyk 2022).”
Line 184:
«Fiures»
Action taken: Section 3.2. Kinetics of pesticide degradation, spelling was corrected
Line 186:
Please, add the standard deviations.
Action taken: please notice that in Figures 1a and 1b and Figures 2a and 2b, the SD was mentioned and is present in the Figures
Line 204:
It is absolutely mandatory to add the standard deviations to the
half-life times presented in Table 1. The absence of this information
greatly weakens the results of the study because it makes it more
difficult to interpret the data. Since the authors specify that the
dissipation studies of the compounds studied all follow first-order
kinetics, it is necessary to change Half-life time by t1/2 in Table 1.
Action taken:
As mentioned above in Figures 1a and 1b and Figures 2a and 2b, the SD is present in the Figures.
Also new comments were added in (Table 1): the values t ½ (h) and t ½ (weeks).
Line 259:
Add the caption to Fig.5
Action taken: New comments were added in section 3.4. Toxicity tests
“Figure 4a-d. Chronic and acute toxicity results on physical and biochemical parameters of earthworms exposed on the chlorfenvinphos in soil before and after ozonation.”
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript concerns the method of decontamination of soils contaminated with organophosphorus insecticide chlorfenvinphos via ozonation. The topic is potentially interesting, although it is the fourth study of the authors on the same topic. In previous studies authors performed ozonation of simazine (ref. 3), DDT (ref. 3), and linuron (ref 9). Therefore, in my opinion, the authors should demonstrate what progress has been made in ozonation methodology compared to previous studies, and what is efficiency of ozonation of chlorfenvinphos in comparison to other compounds. An introduction is very general. Authors should add details concerning chemical structure of the insecticide and details concerning its adsorption and degradation in soils. Also information concerning the effect of ozonation on soil microbiota should be provided, as well as information on the changes in chemical structure of humic substances caused by ozonation. The pathways of microbial degradation of chlorfenvinphos, and its photodegradation, were also not mentioned in the introduction. Moreover, the Materials and Methods section is too general. For example, the only information concerning the used laboratory reactor was that its cross section was 15 cm. Moreover, details concerning technical scale were omitted. The only information concerning technical scale was “The ratio of the beads weight to the sieve surface was similar, i.e., 10 and 11, for laboratory and technical scale fluidized bed reactors.”(lines 158-159). What with other details? The details presented in the Materials and Methods section should be sufficiently detailed to allow for the replication of the experiments.
The authors examined degradation kinetics but for determination of kinetics parameters they used “pseudo-first order kinetic model” (lines 199-200) and as parameter of goodness of fit they used “correlation indicator R2” (line 201). I suggest that before correcting the manuscript, the authors read the basic information on chemical reaction kinetics, as well as the basic information on regression analysis. The data presented in Table 1 indicate that the authors used the other degradation kinetics model (even though they did not know its name) and provided the correct values for the R2 parameter for this model as well as the correct t½ values.
The authors did not discuss the results concerning chemical degradation mechanism (in lines 208-238 only one reference is provided). This part should be deepened. Are the authors sure that studies on ozonation of chlorfenvinphos (or similar compounds) were not conducted by other authors? Taking into account the structure of the compound it can be supposed that similar degradation products should be obtained during microbial degradation and photodegradation. Why the fate of phosphate was not mentioned?
I see the lag-phase after 26 h in Figure 1a, after 20 h in Figure 1b, after 15 h in Figure 2a, and after 9 h in Figure 2b. Why this phenomenon wasn’t discussed? Taking this into account, was the used “pseudo-first order kinetic model” suitable for the observed data?
My most important reservation, however, concerns the soil used. Namely, the authors used artificial soil used for comparative purposes in biological studies. Chlorfenvinphos is applied directly to the soil, therefore in my opinion the soils recommended in OECD guideline 306 should be used for the study as representative for agricultural soils. I suppose that ozonation results are to some extent dependent on adsorption of chlorfenvinphos in soils. Therefore, obtained results may be different for native soils. Such soils should be sterilised before chlorfenvinphos addition, and next ozonation should be performed. Why the artificial soil was used?
Last concerns. There are no descriptions for Figures 3-5. Furthermore, the data in Lines 287-313 are not completed.
For the above reasons the present version of the manuscript is not suitable for publication.
Author Response
The manuscript concerns the method of decontamination of soils
contaminated with organophosphorus insecticide chlorfenvinphos via
ozonation. The topic is potentially interesting, although it is the
fourth study of the authors on the same topic. In previous studies
authors performed ozonation of simazine (ref. 3), DDT (ref. 3), and
linuron (ref 9). Therefore, in my opinion, the authors should
demonstrate what progress has been made in ozonation methodology
compared to previous studies, and what is efficiency of ozonation of
chlorfenvinphos in comparison to other compounds.
Action taken: new comment in section: 3.3. Discussion of the results of chlorfenvinphos degradation in the soil matrix were added:
“Crucial from the scientific point of view is not only the determination of the degradation kinetic parameters, but also the susceptibility of organophosphorus pesticides to the degradation method and the determination of pathways for their potential deg-radation. Particularly important is the discovery of the stereoselectivity of the process, which clearly shows that the limiting step in the process is the attack on the unsatu-rated bond, which determines the occurrence of the Z and E isomers of chlorphen-vinphos. On the basis of the analysis of the degradation products, it was found that the ester bonds that occur directly at the phosphorus atom are also susceptible to the deg-radation process, which may be useful in predicting the susceptibility to degradation of other compounds belonging to this group. Previously prepared work had failed to dis-cover these phenomena (Józefczyk et al., 2022).”
An introduction is
very general. Authors should add details concerning chemical structure
of the insecticide and details concerning its adsorption and degradation
in soils.
Action taken: Introduction new comments were added in section 1. (see below).
“Chlorfenvinphos was mainly used to control pests on plantations and horticul-tures, but it could also be utilized for control of vector-born diseases in areas of high population density. Insecticides from this group were used both in agriculture and in veterinary for the control of the population of insects such as flies, fleas and mites in livestock and house animals (Biziuk 2001).”
(…)
“Chlorfenvinphos toxicity is based on the attack on the nervous system i.e., by inhibit-ing the activity of acetylcholinesterase. Human may be affected by contact with contami-nated environmental media, consumption of food or contact with animals fur (National Registration Authority 2000). It enters the environment through runoff and leaching from hazardous waste sites. Then, it can be present in the soil within the underground water. Furthermore, it can be transported to surface water (Dorsey and Kueberuwa 1997; National Registration Author-ity 2000). Chlorfenvinphos in soil was reported to have a half-life ranging from 28 to 210 days (Beynon., et al. 1973). It is mainly degraded by microorganisms. The efficacy of this pro-cess can be improved by adding organic fertilizers, for example, pig slurry, cow manure, municipal waste or mushroom cultivation composts. Such a treatment causes an increase in the insecticide degradation rate, which could be observed by comparison of the half-life of chlorfenvinphos with and without the addition of various fertilizers (National Registra-tion Authority, 2000). Other transformations of chlorfenvinphos can occur due to hydroly-sis. This can be catalyzed by H+, Ca2+, Na+, and K+, mono-ionic kaolinite and bentonite present in clays. However, it was indicated that the chlorfenvinphos hydrolysis process is less important (National Registration Authority, 2000). This observation is a result of the experiments conducted under natural conditions in the loamy sands (pH 7.2; 1.6% of or-ganic carbon) and the fertile layer (pH 6.5; 27.8% of organic carbon) (National Registration Authority 2000). Chlorfenvinphos is degraded in soil to trichloroacetophenone, 2,4-dichloroacetophenone, α-(chloromethyl)-2,4-dichlorobenzyl alcohol, and 1-(2',4'-dichlorophenyl)-ethan-1-ol (chlorfen toxicity). Also, 2,4-dichlorobenzoic acid, 2-hydroxy-4-chlorobenzoic acid, and 2,4-dihydroxybenzoic acid were identified as me-tabolites of this compound. All of the mentioned degradation products do not possess the initial properties of their mother compound. The main degradation product of chlorfen-vinphos is trichloroacetophenone. This metabolite can undergo further transformation and, as a result of hydrolysis, oxidation, and decarboxylation, 2,4-dichlorobenzoic acid is generated. Another transformation of trichloroacetophenone is based on its reduction to α-(chloromethyl)-2,4-dichlorobenzyl alcohol. During that process chlorine atom is re-placed with hydrogen atom and two products: 2,4-dichloroacetophenone and 1(-2',4'-dichlorophenyl)-ethan-1-ol are generated. Transformation of trichloroacetophe-none on this pathway is a slow process. Other chlorfenvinphos metabolites, such as 2-hydroxy-4-chlorobenzoic acid and 2,4-dihydroxybenzoic acid, are generated by replac-ing chlorine atoms with hydroxyl groups in 2,4-dichlorobenzoic acid (National Registra-tion Authority 2000).”
(…)
“There is a literature gap on remediation of chlorfenvinphos contaminated soil with ozone.”
Also information concerning the effect of ozonation on soil
microbiota should be provided, as well as information on the changes in
chemical structure of humic substances caused by ozonation. The pathways
of microbial degradation of chlorfenvinphos, and its photodegradation,
were also not mentioned in the introduction.
Action taken: new comments were added in section 1 see above.
Moreover, the Materials and
Methods section is too general. For example, the only information
concerning the used laboratory reactor was that its cross section was 15
cm. Moreover, details concerning technical scale were omitted. The only
information concerning technical scale was “The ratio of the beads
weight to the sieve surface was similar, i.e., 10 and 11, for laboratory
and technical scale fluidized bed reactors.”(lines 158-159). What with
other details? The details presented in the Materials and Methods
section should be sufficiently detailed to allow for the replication of
the experiments.
Action taken: new comments were added in section 2.4. Quarter-Technical-scale fluidized bed reactor: “The capacity of the reactors was 200g for laboratory and 3kg for quarter technical scale reactor. A more detailed description can be found elsewhere (Józefczyk et al., 2022).”
The authors examined degradation kinetics but for determination of
kinetics parameters they used “pseudo-first order kinetic model” (lines
199-200) and as parameter of goodness of fit they used “correlation
indicator R2” (line 201). I suggest that before correcting the
manuscript, the authors read the basic information on chemical reaction
kinetics, as well as the basic information on regression analysis. The
data presented in Table 1 indicate that the authors used the other
degradation kinetics model (even though they did not know its name) and
provided the correct values for the R2 parameter for this model as
well as the correct t½ values.
We used the R2 correlation parameter for proving the linear relation of the ln C/C0
Action taken: new comments were added in section 3.2. Kinetics of pesticide degradation
(In particular changes in Table 1 such as description of t1/2 and lnC/C0.
The authors did not discuss the results concerning chemical degradation
mechanism (in lines 208-238 only one reference is provided).
This part should be deepened. Are the authors sure that studies on ozonation of
chlorfenvinphos (or similar compounds) were not conducted by other
authors? Taking into account the structure of the compound it can be
supposed that similar degradation products should be obtained during
microbial degradation and photodegradation. Why the fate of phosphate
was not mentioned?
We confirm the lack of comprehensive research on utilizing ozone for removal of chlorfenvinphos pesticide from the soil matrix
Action taken new comments in section 3.3. Discussion of the results of chlorfenvinphos degradation in the soil matrix were added:
“Uygun observed similar chlorfenvinphos degradation pathways during the storage of carrot (Uygun 1997). It should be noted that some of the microorganisms, especially fungi, could generate very active enzymatic systems like ligninolytic enzymes, which can degrade very persistent compounds includsing organophosphorus pesticides uti-lizing Fenton-like reagents (Wu et al., 2023).). Fenton-like reagents generate hydroxyl radicals that can react with organic compounds giving analogous degradation prod-ucts as can be detected during ozonation. The ozonation method however, provides fast, safe and residue free procedure. Furthermore, its much faster the bioremediation procedures.”
I see the lag-phase after 26 h in Figure 1a, after 20 h in Figure 1b,
after 15 h in Figure 2a, and after 9 h in Figure 2b. Why this phenomenon
wasn’t discussed? Taking this into account, was the used “pseudo-first
order kinetic model” suitable for the observed data?
Action taken new comments were added in section 3.3. Discussion of the results of chlorfenvinphos degradation in the soil matrix:
“It should be noted that the maximum degradation level achieved is less than 100% . This is due to the fact that ozone access in the fluid phase is favored over chlorfenvinphos particles on the surface of soil particles. As a heterogeneous material, the soil may consist of highly viscous liquids that absorb chlorfenvinphos, thus limiting ozone access. This phenomenon can be observed by slowing down the reaction in minutes.”
My most important reservation, however, concerns the soil used. Namely,
the authors used artificial soil used for comparative purposes in
biological studies. Chlorfenvinphos is applied directly to the soil,
therefore in my opinion the soils recommended in OECD guideline 306
should be used for the study as representative for agricultural soils. I
suppose that ozonation results are to some extent dependent on
adsorption of chlorfenvinphos in soils. Therefore, obtained results may
be different for native soils. Such soils should be sterilised before
chlorfenvinphos addition, and next ozonation should be performed. Why
the artificial soil was used?
Action taken
new comments were added in section 2.7. Toxicity tests:
“The use of artificial soil was dictated by the fact that the necessary proportions of mineral and organic fractions could be selected in a controlled manner, mimicking the natural habitat of soil organisms. The use of native soils was not advisable because their composition is unstable and site-dependent, which would have made it difficult to standardise the tests. In particular, the selection of the soil matrix was mainly based on the OECD recommendations allowing bioassays to be carried out.”
Last concerns. There are no descriptions for Figures 3-5.
Action taken: the description of the figures was added
Furthermore,
the data in Lines 287-313 are not completed.
Action taken: Lacking data was provided
For the above reasons the present version of the manuscript is not
suitable for publication.
Reviewer 3 Report
Comments and Suggestions for AuthorsAuthors should revise the paper the study is not clear
Unattractive title
The methodology is unclear
Author Response
Authors should revise the paper the study is not clear
Action taken: The manuscript was improved by correction of English and some paragraphs were reworked.
Unattractive title
Action taken: the title as rewritten
The methodology is unclear
Action taken: The paragraphs concerning methodology were reworked.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe revised version of the manuscript on the method of decontamination of soils contaminated with organophosphorus insecticide chlorfenvinphos via ozonation was substantially improved in comparison to the original version.
However, I still have reservation to the name of the used model, i.e. “pseudo-first order model”. In fact, the authors used the simple first-order model (SFO). Please, compare the used model with the SFO model on page 51 of https://esdac.jrc.ec.europa.eu/public_path/projects_data/focus/dk/docs/finalreportFOCDegKinetics.pdf
It is impossible to use the pseudo-first order model for description of the degradation kinetics because this model is used for description of adsorption kinetics. In the cited study of Quan et al 2005 there is an error concerning the model name.
Moreover, I still see the incorrect definition of R2 as “correlation indicator” (similarly as in Quan et al 2005). The basic measure of the goodness of fit in the regression analysis is the determination coefficient (R2 or r2). See pages 96-98 in the abovementioned FOCUS guidance document. The more correct option is using the Chi-square (χ2) test (see pages 86-93).
Therefore, in my opinion the manuscript will be suitable for publication after correction of the above errors.
Author Response
Comments and Suggestions for Authors
The revised version of the manuscript on the method of decontamination of soils contaminated with organophosphorus insecticide chlorfenvinphos via ozonation was substantially improved in comparison to the original version.
However, I still have reservation to the name of the used model, i.e. “pseudo-first order model”. In fact, the authors used the simple first-order model (SFO). Please, compare the used model with the SFO model on page 51 of https://esdac.jrc.ec.europa.eu/public_path/projects_data/focus/dk/docs/finalreportFOCDegKinetics.pdf
It is impossible to use the pseudo-first order model for description of the degradation kinetics because this model is used for description of adsorption kinetics. In the cited study of Quan et al 2005 there is an error concerning the model name.
Response
Action taken:
Section Results and discussion (3.2. Kinetics of pesticide degradation), the name of kinetics model was changed according to reviewers suggestion from pseudo first order into simple first order kinetics.
Moreover, I still see the incorrect definition of R2 as “correlation indicator” (similarly as in Quan et al 2005). The basic measure of the goodness of fit in the regression analysis is the determination coefficient (R2 or r2). See pages 96-98 in the abovementioned FOCUS guidance document. The more correct option is using the Chi-square (χ2) test (see pages 86-93).
Therefore, in my opinion the manuscript will be suitable for publication after correction of the above errors.
Response
Action taken:
Sections: Materials and methods (2.5.2. Detector calibration) and Results and discussion (3.2. Kinetics of pesticide degradation), the correct name of the determination coefficient was used.
