Sorption of testosterone on partially-dispersed soil particles of different size fractions: Methodology and implications

Abstract

Sorption of hormones to soil particles of different size fractions (DSFs) has been studied to understand their fate and transport (F/T) in soils. Conventional studies fractionated the soil particles into DSFs by using the high speed stirring method and/or adding surfactants to fully disperse the bulk soil. However, the natural processes (e.g., soil erosion, irrigation) often are relatively mild, and many soil particles may be still in the aggregate form. In this study, a method was developed for conducting the sorption test of a representative hormone (i.e., testosterone) to bulk soils first and then analyzing the results against DSFs. Results indicated the particle size distribution (PSD) of the two representative soils tested with partially-dispersed and fully-dispersed methods was significantly different due to the attachment of clay particles on sand and silt. Testosterone was sorbed mainly by the dominant aggregates even though they might have relatively lower sorption affinity than that of clays. However, the small particles (<2000 nm), even with ∼5% mass of the bulk soil, contributed more than 30% of sorbed testosterone in the "whole" soils. The partially-dispersed soil particles of DSFs should be used to understand the transport of hormone in runoff, because using the fully-dispersed soil particles will overestimate while the whole soil method will underestimate the transport potential. With the methodology developed in this study, the sorption tests will not compromise soil's original properties (e.g., aggregates) or the competition (e.g., sorption) among soil particles, and the contribution of DSFs (particularly the partially-dispersed aggregates) to the sorption of the "whole" soil can be determined.

Transport of manure-borne testosterone in soils affected by artificial rainfall events

“…The radiolabeled testosterone was used successfully to analyze the testosterone concentration in the samples in the literatures (Casey et al, 2004;Sangsupan et al, 2006) and our previous studies (Qi et al, 2014;Qi and Zhang, 2015a). In this study, the testosterone concentrations of the collected samples in runoff and leachate of each time interval were detected before and after centrifugation of 4000 rpm for 45 min, which could be used to determine the distribution of testosterone in the dissolved-and particle-associated phase (Qi and Zhang, 2015b). After centrifugation, 1 mL of the sample supernatant was pipetted to a 20 mL counting vial (Wheaton Millville, New Jersey, USA) with 10 mL cocktail (#6013179, Ultima…”

“…The PSD of soil particles taken away in runoff was also evaluated through the fullydispersed methods [i.e., adding sodium hexametaphosphate (NaPO 3 ) 6 and high-speed stirring to separate the soil particles to their primary states] (Qi and Zhang 2015b). The results showed that the effective diameter evaluated through the fully-dispersed method was much smaller than that of the partially-dispersed method (Qi and Zhang, 2015b), indicating that part of the fine particles were taken away in an aggregate form. This conclusion is consistent with the previous study, i.e., many soil aggregates are stable under the force of erosion (Young 1980).…”

“…The partition coefficient K d, runoff was calculated for each of the samples, as shown in Table S3. The K d, runoff ranges from 6 to 20 L/kg for all the runoff samples, while the linear sorption coefficient of the bulk soil in batch tests, K d was 79.9 L/kg (Qi and Zhang, 2015b).…”

“…Then, the PSD of the soil slurry supernatant was analyzed with a particle size analyzer (NanoBrook 90Plus/BI-MAS, Brookhaven Instrument Co. Holtsville, NY). The PSD of the soil slurry was evaluated with both fully-and partially-dispersed methods as per the procedures shown in previous study (Qi and Zhang 2015b). All of the radioactivity detections were based on three blank samples (without hormone) of centrifuge tubes that had the same analytical conditions (e.g., sample, cocktail volume) as testing tubes.…”

Multiple Grammars and the Logic of Learnability in Second Language Acquisition

“…Such issues interact with V2. Consider the environments where exhaustivity arises (see Schulz et al, 2015 ) for a refined discussion). Although it is not clearly universal (French and Mallayalam are reported to be exceptions), clefts imply exhaustivity in English (See Kiss, 1998 ; Heizmann, 2012 ) which children do not initially grasp:…”