Study of the Photocatalytic Degradation of Highly Abundant Pesticides in Agricultural Soils

Abstract

Organic pesticides are major sources of soil pollution in agricultural lands. Most of these pesticides are persistent and tend to bio accumulate in humans upon consumption of contaminated plants. In this study, we investigate different natural soil samples that were collected from agricultural lands. The samples revealed the presence of 18 pesticides that belong to four different groups including organochlorines (OCP), organophosphorus (OPP), carbamates (Carb), and pyrethroids (Pyrth). The photocatalytic degradation of the five most abundant pesticides was studied in the presence and absence of 1% TiO2 or ZnO photocatalysts under UV irradiation at a wavelength of 306 nm. The five abundant pesticides were Atrazine (OCP), Chlorpyrifos methyl (OPP), Dimethoate (OPP), Heptachlor (OCP), and Methomyl (Carb). The results showed that photolysis of all pesticides was complete under UV radiation for irradiation times between 64–100 h. However, both photocatalysts enhanced photocatalytic degradation of the pesticides in comparison with photolysis. The pesticides were photocatalytically degraded completely within 20–24 h of irradiation. The TiO2 photocatalyst showed higher activity compared to ZnO. The organochlorine heptachlor, which is very toxic and persistent, was completely degraded within 30 h using TiO2 photocatalyst for the first time in soil. The mechanism of photocatalytic degradation of the pesticides was explained and the effects of different factors on the degradation process in the soil were discussed.

Evaluation of DNA Damage, Biomarkers of Oxidative Stress, and Status of Antioxidant Enzymes in Freshwater Fish (Labeo rohita) Exposed to Pyriproxyfen

“…The majority of pesticides and insecticides are not biodegradable, and they tend to remain in the soil and water bodies for years [7]. Various chemicals from multiple sources directly and quickly enter into the body of several animals through contaminated water and food products, ultimately inducing different disorders in normal physiological status [1,8,9].…”

Commercial photocatalyst changes the behavior of Formica pratensis and Formica polyctena

“…In this way, a low-cost, low-energy input method is available to degrade organic pollutants, such as dyes, 6 pesticides, 7 pharmaceuticals, 8 hormones 9 and other potentially dangerous organic pollutants. 10 The most important photocatalyst is titanium dioxide, which is currently applied in self-cleaning surfaces, 11 paints, 12 antimicrobial coatings, 13 solar photocatalytic reactors, 14,15 and for water cleaning.…”

“…In this way, a low-cost, low-energy input method is available to degrade organic pollutants, such as dyes, 6 pesticides, 7 pharmaceuticals, 8 hormones 9 and other potentially dangerous organic pollutants. 10…”

Mobility and Degradation of Pesticides in Soil-Risk to Groundwater Contamination

“…As far as the microbial transformation of various pesticides is concerned, it is expected that the chemical compounds can be present in the soil, water and plant, and toxicity may be more or less than the soil pollution in agricultural lands. Most of these pesticides are persistent and tend to bio accumulate in humans upon consumption of contaminated plants (El-Saeid et al, 2022). Pesticide degradation is a fundamental process for pesticide residue attenuation (Guo et al, 2000) and is governed by biotic and abiotic factors, viz., microbial interactions, soil composition, pesticide property, environmental conditions, etc.…”