摘要

       牲畜废水富含营养物质，但可能含有抗生素和抗生素抗性基因 (ARG)。它们排放到水道或土壤中可能会导致 ARG 的增殖。用废水灌溉似乎是处理废水的最可行选择。在干旱地区使用的一种有效灌溉技术是交替犁沟灌溉 (AFI)，它通过长时间交替干燥植物根部的一部分以在生理上减少蒸腾作用而不影响产量。然而，含废水的 AFI 对抗生素浓度和 ARGs 在土壤中扩散的影响程度知之甚少。本文的目的是研究使用猪废水的 AFI 如何在不同灌溉率下改变抗生素动力学和 ARGs 丰度，使用胡椒作为模型植物。我们检查了三种 AFI 处理，它们使用了足够的传统沟灌中使用的水量的 50%、65% 和 80%。每个处理都有一个地下水灌溉控制。结果表明，土壤表层20cm的抗生素浓度和相对ARGs丰度没有随着灌溉量的增加而增加，尽管它们高于地下水灌溉的土壤。土壤中的相对 ARGs 丰度受灌溉量的调节，减少 AFI 中的灌溉量会减少 ARGs 仅在根际的分散。当土壤水分接近田间持水量时，根际 ARGs 比非根际更丰富，这可能是因为根际微生物丰富，灌溉率增加导致抗生素浓度增加有利于抗生素抗性微生物组竞争底物.然而，这些并没有反映在根中的相对 ARGs 丰度中。这些结果具有重要意义，因为它表明减少抗生素和 ARGs 进入土壤的 AFI 并不一定会减少 ARGs 增殖。

       Livestock wastewater is rich in nutrients but may contain antibiotics and antibiotic resistance genes (ARGs). Their discharge to watercourses or soil may result in proliferation of ARGs. Irrigation with wastewater appears to be the most feasible option of disposing of it. One efficient irrigation technology used in arid regions is alternate-furrow irrigation (AFI) by alternately drying part of the plant roots for a prolonged period to physiologically reduce transpiration without compromising yield. However, the extent to which AFI with wastewater influences the concentration of antibiotics and spread of ARGs in soil is poorly understood. The purpose of this paper is to investigate how AFI using swine wastewater alters antibiotic kinetics and ARGs abundance under different irrigation rates, using pepper as the model plant. We examined three AFI treatments using 50%, 65% and 80% of the amount of water employed in sufficient conventional furrow irrigation. Each treatment had a groundwater irrigation control. The results showed that antibiotic concentrations and relative ARGs abundance in the top 20 cm of soil did not increase with the irrigation amount, although they were higher than those in the groundwater-irrigated soils. The relative ARGs abundance in the soil was modulated by irrigation amount and reducing the irrigation amount in AFI reduced ARGs dispersion only in rhizosphere. When the soil moisture was close to field capacity, ARGs were more abundant in rhizosphere than in non-rhizosphere, possibly because the rhizosphere is rich in microbes and increasing antibiotic concentrations due to an increase in irrigation rate favors antibiotic-resistant microbiome in competing for substrates. These, however, were not mirrored in the relative ARGs abundance in the roots. These results have important implications as it revealed that reducing the input of antibiotics and ARGs into soil with AFI does not necessarily reduce ARGs proliferation.

https://www.sciencedirect.com/science/article/pii/S0048969718330651