Influence of moisture on the availability and persistence of clotrimazole and fluconazole in sludge‐amended soil

Abstract

Applying sewage sludge to soil is a common practice in many parts of the world. Thus, pharmaceutical compounds, such as azoles, can be released into the environment after sludge is applied to soil. To understand the fate of clotrimazole and fluconazole (pharmaceuticals used as antifungals in humans) in soil after its amendment with sludge, a reliable and sensitive method has been developed to determine these compounds in the solid and aqueous phases of soil. Desorption of clotrimazole from soil amended with sludge was negligible, whereas a rapid desorption of fluconazole was observed. Dissipation rates of these azoles were determined in amended soil incubated at 25°C with moisture contents ranging from 4.5 to 20%. Clotrimazole was more persistent than fluconazole in dry soil, whereas the contrary occurred in wet soil. Partitioning soil:soil solution of these azoles varied with time and moisture contents. Clotrimazole was found in soil with negligible amounts in soil solution, whereas fluconazole was approximately partitioned 50:50 during the assay time (60 d) at any soil moisture content. Occasional rainfall coupled with a relatively low binding soil capacity can result in the contamination of surface and groundwaters by fluconazole, whereas clotrimazole will remain in the soil.

Occurrence and dissipation of three azole biocides climbazole, clotrimazole and miconazole in biosolid-amended soils

“…However, to date no previous field dissipation data have been reported for climbazole and clotrimazole. Previous laboratory studies have reported the dissipation half-lives of 29-126 days for clotrimazole (Garcia-Valcarcel and Tadeo, 2012;Sabourin et al, 2011), which were much lower than 365 days in the present study. Thus laboratory experimental data may overestimate field dissipation rates and inaccurately predict the field dissipation patterns.…”

“…Furthermore, the Zhejiang site was a flooding paddy field, which led to relatively higher dissipation of the biocides. Soil moisture can enhance the biological and abiotic degradation of these biocides (Garcia-Valcarcel and Tadeo, 2012) and biocide leaching. However the laboratory study (Garcia-Valcarcel and Tadeo, 2012) also showed strong adsorption and little desorption of azole biocides in the soils, which is consistent with their high log K ow values (Table 1).…”

“…Soil moisture can enhance the biological and abiotic degradation of these biocides (Garcia-Valcarcel and Tadeo, 2012) and biocide leaching. However the laboratory study (Garcia-Valcarcel and Tadeo, 2012) also showed strong adsorption and little desorption of azole biocides in the soils, which is consistent with their high log K ow values (Table 1). The present study also found good correlations between the concentration and soil properties such as TOC (Fig.…”

“…As part of the program, the fate of organic contaminants including azole biocides in biosolidamended soils has been investigated in addition to inorganic contaminants (Li et al, 2012). Limited previous studies showed the persistence of the azole biocides such as clotrimazole in soils under laboratory conditions (Garcia-Valcarcel and Tadeo, 2012;Sabourin et al, 2011). Dissipation behavior of organic contaminants under field conditions can be very different to that under laboratory conditions (Langdon et al, 2012).…”

Photodegradation of the azole fungicide fluconazole in aqueous solution under UV-254: Kinetics, mechanistic investigations and toxicity evaluation

“…Fluconazole has a water solubility of approximately 1.39 g/L (Wishart et al, 2008), and log K ow and vapor pressure values of 0.25e0.4 and 3.89 Â 10 À7 Pa, respectively (Garcia-Valcarcel and Tadeo, 2012), indicating its hydrophilic nature. After application, fluconazole enters into wastewater treatment plants (WWTPs), and then reaches the receiving environment.…”