The fate of sulfonamides in microenvironments of rape and hot pepper rhizosphere soil system

Abstract

Sulfonamides (SAs) in agricultural soils can be degraded in rhizosphere, but can also be taken up by vegetables, which thereby poses human health and ecological risks. A glasshouse experiment was conducted using multi-interlayer rhizoboxes to investigate the fate of three SAs in rape and hot pepper rhizosphere soil systems to examine the relationship between the accumulation and their physicochemical processes. SAs mainly entered pepper shoots in which the accumulation ranged from 0.40 to 30.64 mg kg⁻¹, while SAs were found at high levels in rape roots ranged from 3.01 to 16.62 mg kg⁻¹. The BCF_{pepper shoot} exhibited a strong positive linear relationship with log D_ow, while such relationship was not observed between other bioconcentration factors (BCFs) and log D_ow. Other than lipophilicity, the dissociation of SAs may also influence the uptake and translocation process. Larger TF and positive correlation with log D_ow indicate preferential translocation of pepper SAs. There was a significant (p < 0.05) dissipation gradient of SAs observed away from the vegetable roots. In addition, pepper could uptake more SAs under solo exposure, while rape accumulated more SAs under combined exposure. When SAs applied in mixture, competition between SAs might occur to influence the translocation and dissipation patterns of SAs.

NOVELTY STATEMENT

The phloem and xylem structure of plants and the neutral and ionic partitioning of sulfonamides (SAs) influence the uptake and translocation of SAs.

A significant (p < 0.05) dissipation gradient of SAs was observed away from the vegetable roots.

Combined exposure could promote the correlation between log BCF and log D_ow.

Keywords:

• Sulfonamides (SAs)
• plant uptake
• bioaccumulation
• translocation
• dissipation gradients

Acknowledgments

This work is financially supported by the National Natural Science Foundation of China (Grant Nos. 41503109 and 21601094).

Additional information

Funding

This work is financially supported by the National Natural Science Foundation of China (Grant Nos. 41503109 and 21601094).