Crop‐Residue‐Derived Char Influences Sorption, Desorption and Bioavailability of Atrazine in Soils

Abstract

The bioavailability of pesticides in soils is affected by the addition of crop‐residue‐derived char, which alters the sorption and desorption characteristics of the soils. Sorption, desorption, and biodegradation experiments were performed using atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] as the target compound in two soils (Hartsells and Grady) with and without a wheat (Triticum aestivum L.) char, and the char alone. The sorption isotherms for both soils were highly linear, whereas the isotherms for 1% char‐amended soils showed an increased sorption capacity and isotherm nonlinearity. The amount of atrazine sorbed by the char alone was 800 to 3800 times greater than sorbed by the soils. Successive desorption experiments showed that char‐amended soils contained higher nondesorbable fractions of atrazine than soils without char amendment. Pseudomonas sp. strain ADP capable of rapidly mineralizing atrazine was used to evaluate atrazine bioavailability. The presence of char reduced 14CO2 production by 11 and 20% in the char‐amended soils and char, respectively. The two‐step successive desorption experiments appeared to be able to predict the bioavailabilty of atrazine in char‐amended soils. This study shows that the presence of char in soils significantly influences the sorption and desorption processes and, ultimately, the bioavailability of atrazine.

Impacts of Biochar (Black Carbon) Additions on the Sorption and Efficacy of Herbicides

“…For the herbicide atrazine, Loganathan et al (2009) reported a decrease in mineralization of the herbicide in the 1% (w/w) wheat char amended soils as compared to the soils slurries, attributing the atrazine bioavailability decrease to the increase in sorption of the herbicide on the char amendment. Guo et al (1991) suggested that atrazine and alachlor degradation could be inhibited by the presence of waste activated carbon, and stimulated by other uncharred amendments, such as municipal sewage sludge and manure.…”

“…Wang & Xing (2007) hypothesized that the sorption of organic compounds to un-charred biomass is dominated by absorption mechanisms, whereas adsorption becomes the dominant process with charred materials, largely due to the newly created atomic surfaces and micropores. In the case of wheat char and atrazine, one of the herbicides most used worldwide, the K f value sorption on the amendment was 2012 (Loganathan et al, 2009), and the K f increased by a factor of 5 in a sandy loam soil and of 4.3 in a clay loam soil, when both soils were amended with 1% (w/w) of wheat char. Sorption of pentachlorophenol, an organochlorine compound used as herbicide, insecticide, fungicide, algaecide, and disinfectant, was studied on three soils with different amendments (char, humic acids and peat), by Li et al (2009).…”

“…A pesticide that is sorbed to soil particles has to be desorbed to be available for transport and degradation. Desorption of atrazine in one step, successive steps and followed by solvent extraction for soil, char and char amended soil was performed by Loganathan et al (2009). The multiple steps desorption was more efficient than the one step process, showing hysteresis in the sandy loam and clay loam soils and the amended soils.…”

Biochar‐mediated reductive transformation of nitro herbicides and explosives

“…Chen et al [19] showed that nonpolar and polar aromatic compounds could sorb to the surface of pine needle biochar through partition and/or adsorption depending on the pyrolysis temperature. Loganathan et al [20] reported that application of biochar to soil can significantly increase the sorption of atrazine and, hence, decrease its bioavailability. Chun et al [17] suggested that the relatively high affinity of biochar for polar aromatic compounds (e.g., nitrobenzene) could be attributed to the functional groups (acidity/basicity) on the biochar surface.…”

Lixiviação do hexazinone e da mistura hexazinone + diuron em colunas de solos com texturas distintas.

“…C.V. = 20,62%. (YANG e SHENG, 2003;LOGANATHAN et al, 2009). O diuron é pouco móvel no solo, atingindo no máximo a camada de 0-20 cm de profundidade em campo (EL IMACHE et al, 2009) e em coluna (LANDRY et al, 2004), devido ao elevado K oc (145-917 L kg -1 ) (LIYANAGE et al, 2006).…”