Horizontal subsurface flow constructed wetlands for mitigation of ametryn-contaminated water

Abstract

The feasibility of using constructed wetlands (CWs) for the mitigation of pesticide runoff has been studied in the last decade. However, a lack of related data was verified when subsurface flow constructed wetlands (SSF CWs) are considered for this purpose. In the present work, SSF CWs were submitted to continuous ametryn addition and evaluated during an 11-week period, with the aim of determining the feasibility of these systems for mitigation of contaminated water. Ametryn was not added to one CW cell in order to provide a control for the experiments. Monitoring of treatment performance was executed by standard water quality parameters, ametryn chromatography quantification and macrophyte (Typha latifolia L.) nutritional and agronomic property analysis. Results indicated that 39% of the total initially added amount of ametryn was removed, transferred or transformed. Herbicide metabolism and mineralisation were carried out by chemical and biological mechanisms. No statistic differences were observed in nutritional contents found in the T. latifolia crops of the CWs after the experimental period. Moreover, the biomass production (one valuable source of renewable energy) was equal to 3.3 t•ha -1 (dry matter) in wetland cells. It was concluded that constructed wetland systems are capable of mitigating water contaminated with ametryn, acting as buffer filters between the emission sources and the downstream superficial water bodies.

Evaluation of the main active species involved in the TiO2 photocatalytic degradation of ametryn herbicide and its by-products

“…Another important factor is that triazines are susceptible to leaching from the soils to waterbodies and appear in drinking water. This is favored by their physicochemical properties, including: (i) relatively high water solubility (185 mg L -1 , 20 o C [8]); (ii) low sorption coefficient (316 ~ 445 cm 3 g -1 [9]); (iii) high polarity (log Kow 2.7-3.1 [8]); or (iv) long half-life time (70-250 days, varying with type of soil and weather conditions [10]). In addition, these compounds can undergo slow degradation to water-soluble by-products [11].…”

Ametryn removal by Metarhizium brunneum: Biodegradation pathway proposal and metabolic background revealed

“…S-triazines are very stable compounds and this allows them to accumulate in the environment for several months to several years in soil or water sediments (Prosen 2012). Due to their physicochemical properties such as relatively high water solubility, low sorption coefficient or long half-life time, s-triazine pesticides are susceptible to leaching from the soil (Borges et al, 2009;Shah et al, 2011;Sandoval-Carrasco et al, 2013). Additionally, under environmental conditions these compounds can undergo slow degradation to water-soluble by-products.…”

“…Due to the adverse effects of striazines on the environment, the use of these herbicides in agriculture within the European Union (EU) has been bannedfor ametryn from the year of 2002 (Liu et al, 2014). Despite the withdrawal of these pesticides in EU countries, they are still present in water and soil samples, even in areas where their usage is limited or far from agricultural areas (Borges et al, 2009;Allan et al, 2017). Ametryn is a systemic s-triazine herbicide absorbed by plant roots and leaves and characterized as a photosynthesis inhibitor.…”