摘要
次潮带（HZ）是一个活跃的生物地球化学区，地下水和地表水在这里混合，是抗生素抗性基因（ARGs）的潜在库。本文研究了HZ介质中ARGs的相对丰度和空间分布，同时考虑了六种金属的五种形态和局部特征。西安市是中国西北地区具有代表性的城市，地表水、地下水和沉积物样品采集于西安市皂河-渭河。在271个与9种抗生素相关的ARGs中，检测到228个ARGs，总检测率为84%。磺酰胺类和氨基糖苷类ARGs是ARGs的主要类型。丰度最高的6个ARGs和可移动遗传元素（MGE）分别是tnpA-04、cepA、sul1、aadA2-03、sul2和intI1。主成分分析（PCA）结果表明，ARGs的分布特征与采样点无关，而是与环境介质有关。发现了水相的相似性以及水相和沉积物的显著差异。冗余分析（RDA）确定了控制ARG污染的关键因素，包括地表水中的溶解氧（DO）、地下水中的总氮（TN）和沉积物中的总有机碳（TOC）。在重金属形态方面，我们进一步揭示了ARGs与重金属之间的促进作用，尤其是Ni的残留部分。在水平转移机制方面，ARGs在水相中与tnpA-03和沉积物中与tnp A-04显著相关。在这三种介质中，intI1和ARGs都显示出显著的相关性。这些发现表明，低铼区对ARGs的分布和转移产生了瓶颈效应。
Abstract
The hyporheic zone (HZ) is an active biogeochemical region where groundwater and surface water mix and a potential reservoir for antibiotic resistance genes (ARGs). In this paper, the relative abundance and spatial distribution of ARGs in the HZ media were investigated, taking into consideration both the five speciation of six metals and the local characteristics. The samples of surface water, groundwater, and sediment were collected from Zaohe–Weihe Rivers of Xi’an City, which is a representative city with characteristics of the northwest region of China. Of 271 ARGs associated with 9 antibiotics, 228 ARGs were detected, with a total detection rate of 84%. Sulfonamide and aminoglycoside ARGs were the dominant types of ARGs. The top 6 ARGs and mobile genetic elements (MGEs) in terms of abundance were tnpA-04, cepA, sul1, aadA2-03, sul2 and intI1. The results of principal component analysis (PCA) showed that the distribution characteristics of ARGs were not associated with the sampling sites but with the environmental medias. Similarity in the water phases and significant differences in the water and sediment phases were found. The redundancy analysis (RDA) identified the key factors controlling ARG pollution, including dissolved oxygen (DO) in surface water, total nitrogen (TN) in groundwater, and total organic carbon (TOC) in sediment. In terms of the speciation of heavy metals, we further revealed the promotion effect between ARGs and heavy metals, especially the residual fraction of Ni. In terms of horizontal transfer mechanism, ARGs were significantly correlated with tnpA-03 in water phase and tnpA-04 in sediment. In the three media, intI1 and ARGs all show a significant correlation. These findings showed that hyporheic zone exerted a bottleneck effect on the distribution and transfer of ARGs.

https://link.springer.com/article/10.1007/s11356-022-18579-3