Removal of diuron and hexazinone from guarany aquifer groundwater

Abstract

-The economy of many communities in southeastern Brazil is based on agroindustry, particularly the sugarcane industry. Recent studies have found increased use of herbicides in this type of agriculture, among which diuron and hexazinone are the most widely used. The water supply for some communities is derived entirely from the Guarany Aquifer (the world's largest transborder underground freshwater system), and some wells are located in recharge zones, which makes the groundwater more vulnerable to contamination. In this study, we monitored some of the wells located in the recharge area. We studied the removal of diuron and hexazinone from synthetic water prepared in the laboratory by preoxidation with chlorine and chlorine dioxide, as well as adsorption with granular activated carbon (GAC). The saturation time of GAC in tests with preoxidation with both oxidants was shorter than the saturation time in the test without preoxidation, possibly due to the formation of by-products that competed for the adsorption of the herbicides. The conclusion was that the use of activated carbon is important for removing the herbicides in question, as well as the by-products produced by these oxidants.

Assisted attenuation of a soil contaminated by diuron using hydroxypropyl-β-cyclodextrin and organic amendments

“…Diuron is one such herbicides and it is the one that is most frequently detected in groundwater (Di Bernardo et al, 2011;Giaccomazzi and Cochet, 2004). Moreover, this herbicide is included in the list of priority hazardous substances of the European Union (Malato et al, 2003), and is subjected to emission controls and quality standards to achieve "progressive reduction of discharges, emissions and losses".…”

Contamination of fee-fishing ponds with agrochemicals used in sugarcane crops

“…Studies have confirmed that the intense use of pesticides in crops, associated with the molecule physicochemical characteristics, has impacted negatively the hydrographic networks [52][53][54][55][56]. These researches corroborate with the results found, because the solubility values of the detected herbicides range between 35 and 33.000 mg L −1 (Table 6), classifying them as low to high solubility, with the exception of ametryn and atrazine, classified as moderate to low solubility which is related to the lower concentrations of these herbicides in the evaluated fee-fishing ponds samples [51].…”

Multivariate analysis reveals significant diuron-related changes in the soil composition of different Brazilian regions

“…The half-life of diuron in soils can reach 30 to 150 days 7,8 (moderate persistent), but a half-life of 330 days for this herbicide has been reported in the literature 9 . Additionally, in sandy soil, this herbicide demonstrates high mobility, and after the occurrence of rainfall or irrigation, this herbicide can contaminate groundwater resources 10 . For example, researchers have already identified the presence of diuron in rivers and groundwater in different Brazilian states 11,12 .…”