Effects of soil texture and drought stress on the uptake of antibiotics and the internalization of Salmonella in lettuce following wastewater irrigation

Yuping Zhang; J Brett Sallach; Laurie Hodges; Daniel D Snow; Shannon L Bartelt-Hunt; Kent M Eskridge; Xu Li

doi:10.1016/j.envpol.2015.10.025

Effects of soil texture and drought stress on the uptake of antibiotics and the internalization of Salmonella in lettuce following wastewater irrigation

Environ Pollut. 2016 Jan;208(Pt B):523-31. doi: 10.1016/j.envpol.2015.10.025. Epub 2015 Nov 6.

Authors

Yuping Zhang¹, J Brett Sallach¹, Laurie Hodges², Daniel D Snow³, Shannon L Bartelt-Hunt¹, Kent M Eskridge⁴, Xu Li⁵

Affiliations

¹ Department of Civil Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA.
² Department of Agronomy & Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA.
³ Nebraska Water Center, University of Nebraska-Lincoln, Lincoln, NE, USA; School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, USA.
⁴ Department of Statistics, University of Nebraska-Lincoln, Lincoln, NE, USA.
⁵ Department of Civil Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA. Electronic address: xuli@unl.edu.

PMID: 26552531
DOI: 10.1016/j.envpol.2015.10.025

Abstract

Treated wastewater is expected to be increasingly used as an alternative source of irrigation water in areas facing fresh water scarcity. Understanding the behaviors of contaminants from wastewater in soil and plants following irrigation is critical to assess and manage the risks associated with wastewater irrigation. The objective of this study was to evaluate the effects of soil texture and drought stress on the uptake of antibiotics and the internalization of human pathogens into lettuce through root uptake following wastewater irrigation. Lettuce grown in three soils with variability in soil texture (loam, sandy loam, and sand) and under different levels of water stress (no drought control, mild drought, and severe drought) were irrigated with synthetic wastewater containing three antibiotics (sulfamethoxazole, lincomycin and oxytetracycline) and one Salmonella strain a single time prior to harvest. Antibiotic uptake in lettuce was compound-specific and generally low. Only sulfamethoxazole was detected in lettuce with increasing uptake corresponding to increasing sand content in soil. Increased drought stress resulted in increased uptake of lincomycin and decreased uptake of oxytetracycline and sulfamethoxazole. The internalization of Salmonella was highly dependent on the concentration of the pathogen in irrigation water. Irrigation water containing 5 Log CFU/mL Salmonella resulted in limited incidence of internalization. When irrigation water contained 8 Log CFU/mL Salmonella, the internalization frequency was significantly higher in lettuce grown in sand than in loam (p = 0.009), and was significantly higher in lettuce exposed to severe drought than in unstressed lettuce (p = 0.049). This work demonstrated how environmental factors affected the risk of contaminant uptake by food crops following wastewater irrigation.

Keywords: Antibiotic; Drought stress; Salmonella; Soil texture; Wastewater irrigation.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Agricultural Irrigation / methods*
Anti-Bacterial Agents / analysis
Anti-Bacterial Agents / metabolism*
Droughts*
Humans
Lactuca / microbiology
Lactuca / physiology*
Plant Roots
Salmonella / growth & development*
Soil / chemistry*
Soil Microbiology*
Stress, Physiological*
Waste Disposal, Fluid / methods
Wastewater / chemistry
Wastewater / microbiology
Water Pollutants, Chemical / analysis
Water Pollutants, Chemical / metabolism*

Substances

Anti-Bacterial Agents
Soil
Waste Water
Water Pollutants, Chemical