Reduction of environmental pollution incurred from pesticide use is very important. Zeolite is a natural mineral capable of removing certain chemical contaminants from water. This study was carried out to test the effect of zeolite treatment on pesticide residue alleviation in surface water. Ten surface water samples were treated with natural zeolite by filtering through. An EPA method was used to extract pesticide residue from the water samples and the surfactant used to modify the net charge on the zeolite was hexadecyltrimethylammonium chloride (HDTMA-Cl). Gas chromatography-mass spectrometry was used to analyze water samples. Alleviation was achieved in all the 10 water samples that were filtered through zeolite. The highest removal of pesticides from water with zeolite included 100% of bifenthrin in sample CLC, atrazine in BPH, CDG and LBT; metolachlor in CLC, LBT, BCH, TRH2 and BPI; acetolachlor in BBH and BCH; azoxystrobin in BBH; desethylatrazine in BCH and BPI; metribuzin in BCH, TRH2 and BPI; and both clomazone and bromacil in sample BDC. A minimum reduction of 10.9% was found for metolachlor in sample BRH. Further reduction of pesticide residues up to 50% was recorded in the SMZ treatment as the concentrations of 4 out of 8 pesticide residues were reduced. This study confirms the potential of both the natural zeolite-Clinoptilolite, and SMZ of alleviating pesticide residues in water.
A clean environment is required for maintaining good health and agricultural sustainability. Regular use of pesticides in modern day agriculture demands the need to devise a means of removing or reducing possible pesticide residues from our environment. Waters that are available in the environment where pesticides are used are of high risk of harboring pesticide residues. Leaching enhances environmental pollution as chemicals drain from the treated region to non-tar- geted environments. Therefore, surface waters have the potential of getting contaminated when irrigation water that has passed over pesticide-treated environment leaches into the surface waters [
Due to its unique attributes, zeolite is a mineral with the potential of removing chemical contaminants from water as earlier published [
Ten surface water samples were collected from different locations in Louisiana. These were sourced from the pool of samples from the Pesticide Laboratory of the Agricultural Chemistry department, Louisiana State University through the Louisiana State Department of Agriculture and Forestry (LDAF). Water samples and their sources were as listed in
Water | Source |
---|---|
BPH | Bayou Pierre, Hwy 1 S of Powha (*WM-S-A-01) |
CLC | Chatlin Lake Canal, Hwy 457 T2N (WM-S-A-04) |
CDG | Coulee Des Grues, hwy 115-SW (WM-S-A-05) |
BCH | Big Creek Hwy 80 at Holly Ridge (WM-S-M-03) |
LBT | Lake Bruin T12N R12E S29 (WM-S-M-06) |
TRH2 | Tensas River Hwy 15 at Clayon (WM-S-M-07) |
BPI | Bayou Portage I-10 at Henderson (WM-S-O-07) |
BDC | Bayou De Cannes, Hwy 98 2 MI, W (WM-S-C-03) |
BBH | Black Bayou, Hwy 530 2 MI. E. of Foley AL 36535 (WM-S-S-01) |
BRH | Boeuf River, Hwy 2 T2 IN R8E S25 Eunice LA (WM-S-M-01) |
*WM = Water monitoring.
source by abbreviating the name of the source. For instance, sample BPH was obtained from Bayou Pierre, Hwy 1 S of Powha. All water samples were stored at 4˚C until each was analyzed.
The method used for pesticide residue extraction in surface water is same as earlier described [
Ten water samples―BPH, CLC, CDG, BBH, BRH, BCH, LBT, TRH, BPI, and BDC, were selected from the original pool of 35 samples of surface water studied for detection of pesticide residues. The criterion used in selecting those 10 samples was the water samples that had the most pesticide residues based on the results from a similar study [
As earlier described [
swirl until all surfactant dissolved, solution was poured into 100 ml graduated cylinder and milliQ water added up to 80.5 ml final volume. Twenty gram of natural zeolite was dispersed in the 80.5 ml of 0.056 M surfactant for 2 hours. The supernatant was drained away after 2 hours and the surface-modified zeolite (SMZ) was spread out on a clean aluminum foil to air dry overnight.
The water sample BRH was selected based on its highest volume of pesticide residue content. The filtration system for SMZ consisted of 3 columns in layers. The upper layer was empty followed by a middle layer of natural zeolite and base layer of HDTMA-Cl-SMZ.
As listed in
GC-MS analysis was the same as earlier described [
Statistical analytical system (SAS) was employed to run paired student T-test in
Sample | pH | Origin | Reduction | Pesti Resid | Before | After | % Reduction |
---|---|---|---|---|---|---|---|
BPH | 7.7 | 2 | 2 | Atrazine | 0.2 | ND | 100 |
Metolachlor | 0.16 | 0.12 | 25 | ||||
CLC | 7.7 | 4 | 4 | Atrazine | 6.48 | 0.06 | 99.1 |
Desethatz | 0.74 | 0.55 | 25.7 | ||||
Metolachlor | 1.08 | ND | 100 | ||||
Bifenthrin | 0.02 | 0 | 100 | ||||
CDG | 7.2 | 2 | 2 | Atrazine | 0.68 | ND | 100 |
Metolachlor | 0.84 | 0.73 | 13.1 | ||||
BBH | 7.2 | 4 | 4 | Atrazine | 1.78 | 1.26 | 29.2 |
Metolachlor | 1.16 | 1.01 | 12.9 | ||||
Acetolachlor | 0.06 | ND | 100 | ||||
Azoxystrobin | 0.02 | ND | 100 | ||||
BRH | 7.3 | 8 | 8 | Atrazine | 6.2 | 0.64 | 89.7 |
Clomazone | 2.4 | 1.54 | 35.8 | ||||
Desethatz | 0.62 | 0.38 | 38.7 | ||||
Metribuzin | 0.34 | 0.17 | 50 | ||||
Metolachlor | 17.2 | 15.32 | 10.9 | ||||
Propanil | 0.08 | 0.03 | 62.5 | ||||
Metalaxyl | 0.08 | 0.06 | 25 | ||||
Dimethenamid | 0.16 | 0.12 | 25 | ||||
LBT | 7.7 | 5 | 3 | Desethatz | 0.22 | 0.17 | 22.7 |
Atrazine | 0.6 | ND | 100 | ||||
Metolachlor | 0.36 | ND | 100 | ||||
Glyphosate | ND | ND | ND | ||||
AMPA | ND | ND | ND | ||||
BCH | 7.1 | 6 | 5 | Atrazine | 6.24 | 1.4 | 77.6 |
Desethatz | 0.54 | ND | 100 | ||||
Acetolachlor | 0.28 | ND | 100 | ||||
Metribuzin | 0.36 | ND | 100 | ||||
Metolachlor | 3.9 | ND | 100 | ||||
Clomazone | 0.04 | ND | ND | ||||
TRH2 | 7.2 | 6 | 5 | Atrazine | 0.38 | 0.16 | 57.9 |
Desethatz | 0.26 | 0.06 | 76.9 | ||||
Metribuzin | 0.3 | ND | 100 | ||||
Metolachlor | 3.4 | ND | 100 | ||||
Clomazone | 0.18 | ND | ND | ||||
Azoxystrobin | 0.06 | 0.02 | 66.7 | ||||
BPI | 7.2 | 7 | 6 | Atrazine | 0.72 | 0.22 | 69.4 |
Desthatz | 0.2 | ND | 100 | ||||
Metribuzin | 0.28 | ND | 100 | ||||
Metolachlor | 0.74 | ND | 100 |
Metalaxyl | 0.12 | 0.1 | 16.7 | ||||
---|---|---|---|---|---|---|---|
Clomazone | 0.04 | ND | ND | ||||
Azoxystrobin | 0.06 | 0.04 | 33.3 | ||||
BDC | 6.8 | 5 | 2 | Clomazone | 0.3 | ND | 100 |
Bromacil | 0.42 | ND | 100 | ||||
Metalaxyl | 0.04 | ND | ND | ||||
Metolachlor | 0.06 | ND | ND | ||||
Propiconazole | 0.12 | ND | ND |
Origin = original pesticide residue in surface water; Reduction = reduced amount of pesticide residue in surface water; Pesti resid = pesticide residue; Desethatz = Desethylatrazine; before = pesticide residue (ppb) in water sample before filtration through zeolite; 1st and 2nd = First and second pesticide residue quantitation reading after filtration through zeolite; PR = pesticide residue; ND = non-detected.
Compund | tR (min) | Qion (m/z) | Compound | tR (min) | Qion (m/z) |
---|---|---|---|---|---|
Acetochlor | 6.87 | 223 | Hexazinone | 9.01 | 171 |
Alachlor | 6.95 | 188 | Malathion | 7.2 | 173 |
Atrazine | 6.5 | 200 | MB45950fm | 7.29 | 420 |
Azoxystrobin | 11.51 | 344 | MB46136fm | 7.8 | 383 |
Bifenthrin | 8.57 | 181 | MB46513,Fip. met. | 6.76 | 388 |
Bromacil | 7.5 | 207 | Metalaxyl | 7.1 | 249 |
Captan | 7.8 | 79 | Methyl Parathion | 7.16 | 263 |
Captan deg. | 5.67 | 79 | Metolachlor | 7.22 | 162 |
Carbofuran | 6.65 | 164 | Metribuzin | 7.18 | 198 |
Carbofuran deg. | 4.08 | 164 | Molinate (Ordram) | 5.57 | 126 |
Chlorpyrifos | 7.26 | 197 | Norflurazon | 8.76 | 303 |
Clomazone | 6.53 | 125 | Pendameth | 7.5 | 252 |
Cyanazine | 7.57 | 225 | Prometone | 6.34 | 225 |
Cyfluthrin 1 | 9.69 | 206 | Propicon1 | 8.56 | 259 |
Cyfluthrin 3 | 9.76 | 206 | Propicon2 | 8.59 | 259 |
Cypermet1 | 9.88 | 181 | Prometryn | 7.05 | 241 |
Cypermet2 | 9.95 | 181 | Propanil | 7.1 | 161 |
Desethylatrazine | 6.24 | 172 | Tebupirimiphos | 6.42 | 261 |
DesIsopropylatz | 6.28 | 173 | Tefluthrin | 6.17 | 177 |
Diazinon | 6.4 | 137 | Terbacil | 6.93 | 161 |
Dimethenamid | 6.91 | 154 | Terbufos | 6.4 | 231 |
Eptam | 4.24 | 128 | Thimet | 6.17 | 75 |
Esfenvalera1 | 10.36 | 167 | Trifluralin | 5.6 | 306 |
Esfenvalerate | 10.45 | 167 | λ-cyhalot1 | 8.91 | 181 |
Etridiazole | 5.04 | 183 | λ-cyhalot | 8.99 | 197 |
Fipronil | 7.35 | 367 |
λ = lambda; DesIsopropylAtz = desisopropylatrazine; MB46136fm = MB46136, Fip. met.; MB45950 = MB45950, Fip. met. Pendameth = Pendamethalin; Propicon2 = Propiconazole 2; Propicon1 = Propiconazole 1; λ-cyhalot1 = Lambda-cyhalothrin 1; λ-cyhalot = Lambda-cyhalothrin; Cypermethrin 1 = Cypermet1; Cypermethrin 2 = Cypermet2; Esfenvalerate 1 = Esfenvalera1.
order to compare the concentration of pesticide residues in the water samples before and after zeolite treatments. The alpha value was set at P = 0.05. That is, when the calculated P-value is less than 0.05 then a statistical difference can be declared.
Reduction in pesticide residues was observed in the 10 zeolite-filtered surface waters analyzed (
As shown in
Statistics of the means comparison for the pesticide residues found before and after filtering water through natural zeolite using a paired student t-test is as shown in
As summarized in
Greater reduction of pesticide residues was recorded (
Sample | PR | Before | After | Means ± SD | Pr > |t| | Sig. |
---|---|---|---|---|---|---|
BPH | Metolachlor | 0.16 | 0.12 | 0.04 ± 0.03 | 0.3 | NS |
CLC | Atrazine | 6.48 | 0.06 | 6.42 ± 0.00 | 0.0001 | *** |
Desethatz | 0.74 | 0.55 | 0.10 ± 0.14 | 0.5 | NS | |
CDG | Metolachlor | 0.84 | 0.73 | 0.11 ± 0.01 | 0.06 | NS |
BBH | Atrazine | 1.78 | 1.26 | 0.52 ± 0.11 | 0.1 | NS |
Metolachlor | 1.16 | 1.01 | 0.15 ± 0.0.13 | 0.34 | NS | |
BRH | Atrazine | 6.2 | 0.64 | 5.56 ± 0.31 | 0.03 | * |
Desethatz | 0.62 | 0.38 | 0.10 ± 0.50 | 0.83 | NS | |
LBT | Desethatz | 0.22 | 0.17 | 0.13 ± 0.01 | 0.05 | NS |
BCH | Atrazine | 6.24 | 1.4 | 4.84 ± 1.84 | 0.01 | ** |
TRH2 | Atrazine | 0.38 | 0.16 | 0.29 ± 0.04 | 0.07 | NS |
BPI | Atrazine | 0.72 | ND | NA | NA | NA |
BDC | Metolachlor | 0.06 | ND | NA | NA | NA |
Sig. = Significance; NS = no significant difference found among the pesticide residue levels recorded before and after treatment with natural zeolite clinoptilolite; * & *** = significant difference and highly significant difference respectively found among the pesticide residue levels recorded before and after treatment with natural zeolite clinoptilolite; SD = standard deviation; SE = standard error; PR = pesticide residue; df (degree of freedom) = 1; Pr > |t| = calculated P value by SAS; Alpha = 0.05 (critical P value); NA = not applicable.
Sample | Pesticide Residue (ppb) | ||||
---|---|---|---|---|---|
Before | After | Mean ± SD | |||
1st | 2nd | ||||
BRH | Atrazine | 6.2 | 0.34 | 0.28 | 0.31 ± 0.04 |
Clomazone | 2.4 | 1.12 | 0.84 | 0.98 ± 0.20 | |
Desethylatrazine | 0.62 | 0.5 | 0.34 | 0.42 ± 0.01 | |
Metribuzin | 0.34 | 0.24 | 0.22 | 0.23 ± 0.01 | |
Metolachlor | 17.2 | 10.16 | 7.82 | 8.99 ± 1.66 | |
Metalaxyl | 0.08 | 0.04 | 0.04 | 0.04 ± 0.00 | |
Propanil | 0.08 | ND | ND | NA | |
Dimethenamid | 0.16 | ND | ND | NA |
SD = standard deviation; ND = not detected.
Sample | PR | BZ | AZ | ASMZ | % Zeolite reduction | % SMZ reduction |
---|---|---|---|---|---|---|
BRH | Atrazine | 6.2 | 0.64 | 0.31 | 89.7 | 95 |
Clomazone | 2.4 | 1.54 | 0.98 | 35.8 | 59.2 | |
Desethylatrazine | 0.62 | 0.38 | 0.42 | 38.7 | 32.3 | |
Metribuzin | 0.34 | 0.17 | 0.23 | 50 | 32.4 | |
Metolachlor | 17.2 | 15.32 | 8.99 | 10.9 | 47.7 | |
Metalaxyl | 0.08 | 0.06 | 0.04 | 25 | 50 |
BZ = before zeolite treatment; AZ = after zeolite treatment; ASMZ = after surface-modified-zeolite; SMZ = surface-modified-zeolite; PR = pesticide residue.
filtration through SMZ. The 4 compounds that were reduced by SMZ compared to filtration through natural zeolite included atrazine @ 95% compared to 89.7% reduction with natural zeolite (NZ); 59.2% clomazone compared with 35.8% with NZ; 47.7% metolachlor compared with 10.9% with NZ and 50% metalaxyl compared with 25% with NZ.
As outlined in
Further paired t-test comparison of pesticide levels was conducted between the levels recorded after treatment with natural zeolite and the levels recorded after treatment with surfactant-modified-zeolite. The outcome of this as outlined in
Sample | PR | Mean ± SD | Pr > |t| | Sig. |
---|---|---|---|---|
BRH | Atrazine | 5.89 ± 0.04 | 0.003 | *** |
Clomazone | 1.42 ± 0.20 | 0.06 | NS | |
Desethatz | 0.20 ± 0.11 | 0.24 | NS | |
Metribuzin | 0.11 ± 0.01 | 0.06 | NS | |
Metolachlor | 8.21 ± 1.66 | 0.09 | NS | |
Metalaxyl | 0.04 ± 0.00 | <0.0001 | *** |
*Sig. = Significance; NS = no significant difference found among the pesticide residue levels recorded before and after treatment with Hexa decyl trimethyl chloride surfactant-modified-zeolite clinoptilolite; ** = very significant difference found between the pesticide residue levels recorded before and after treatment with HDTM-Cl SMZ; SD = standard deviation; SE = standard error; PR = pesticide residue; df (degree of freedom) = 1; Pr > |t| = calculated p value by SAS; Alpha = 0.05 (critical p value).
Sample | PR | Mean ± SD | Pr > |t| | Sig |
---|---|---|---|---|
BRH | Atrazine | 0.33 ± 0.04 | 0.06 | NS |
Clomazone | 0.56 ± 0.20 | 0.16 | NS | |
Desethatz | neg0.04 ± 0.11 | 0.71 | NS | |
Metribuzin | neg0.06 ± 0.01 | 0.11 | NS | |
Metolachlor | 6.33 ± 1.66 | 0.12 | NS | |
Metalaxyl | 0.02 ± 0.00 | <0.0001 | *** |
Sig. = Significance; NS = no significant difference found among the pesticide residue levels recorded between zeolite treated and SMZ treated sample BRH; *** = highly suignificant difference found among the pesticide residue levels recorded between zeolite treated and SMZ treated sample BRH; SD = standard deviation; SE = standard error; PR = pesticide residue; df = degree of freedom; Pr > |t| = calculated p value by SAS; Alpha = 0.05 (critical p value).
served was highly significant (Pcalc < 0.0001). No statistical difference between treatment was observed for atrazine, clomazone, desethylatrazine, metribuzin and metolachlor. However, negative mean value and t value computed for desethylatrazine and metribuzin showed a negative trend because the levels recorded after filtration through the SMZ was higher than the levels after filtration through the natural zeolite. As outlined in
As obtained in this study, adsorption of metalaxyl using zeolite has been earlier reported [
Results obtained in the reduction of atrazine, metolachlor, bifenthrin, clomazone, desethylatrzine, metribuzin, propanil and metalaxyl are good to build upon as modern scientists aspire to provide a permanent solution to pesticide residues in surface water. This could be a basis for a large scale pesticide reduction in other forms of water like ground water and potable water as time goes on. Development of an industrial scale filtration system that could utilize zeolite as water filtration medium will be required in order to put the results obtained in this study into the effective use that will impact communities, national and international boundaries. Simplicity of this method with its low cost filtration system, coupled with the fact that it is free of any form of health risk will enhance its practical use and eventually lead to a global adoption of this methodology.
Adeniyi, O., Hernandez, A., LeBlanc, M., King, J.M. and Janes, M. (2017) Alleviation of Pesticide Re- sidue in Surface Water. Journal of Water Resource and Protection, 9, 523-535. https://doi.org/10.4236/jwarp.2017.95034