Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Vertical migration of ARGs at water-sediment interface under the influence of salinity and Ph
LI Xin1, LIU Shuguang1,2, LOU Sha1,2#, Radnaeva Larisa Dorzhievna3, Nikitina Elena 3, Makhinov Aleksei Nikolavich4, Araruna JoséTavares5.
1. College of civil engineering, Tongji University, shanghai, China；
2.Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, shanghai, China；
3.Laboratory of chemistry of natural systems, Baikal Institute of Nature Management of Siberian branch of the Russian Academy of sciences,
Republic of Buryatia, Russian, Republic of Buryatia；
4. Institute of Water and Ecology Problems, Far East Branch, Russian Academy of Sciences, Khabarovsk, Russia；
5. Pontifical Catholic University of Rio de Janeiro, Brazil, Rio de Janeiro

ABSTRACT

plants, farms and hospitals is an important source of ARGs in theenvironment. The transfer of ARGs at the water-sediment interface
plays a crucial role in their transmission. Currently, most of the studies
on resistance gene transfer and its patterns have been conducted
through bacterial culture tests and soil column simulation tests.

Due to the widespread utilization of antibiotics, antibiotic resistancegenes (ARGs) are found to be existing in water environment, andmigrate between the water column and sediments. Based on soilcolumn experiments, the vertical transport mechanism of ARGs atwater-sediment interface was studied in this paper. It aims to reveal theeffects of physicochemical factors (salinity and pH) on the migration offour ARGs: sul(I), tet(A), tet(X), tet(M) and Class I integron (intI1) atwater-sediment interface. It was found that salinity and pH both canaffect the migration of ARGs between sediment and water. Salinity
weakened the vertical migrations of sul(I), and tet(A), and tet(X), while
the effect of salinity on tet(M) was opposite. The vertical migrations ofsul(I), tet(A), intI1 and 16s were decreased under the acidic conditions(pH=4), while they were enhanced under the alkaline conditions(pH=9.18). For tet(X) and tet(M), both of acidic conditions (pH=4) andalkaline conditions (pH=9.18) weakened the vertical migration.

Some scholars have investigated the transfer pattern of ARGs under the
influence of different external factors through bacterial culture
experiments. For example, zinc ions cause cell lysis and thus release
DNA leading to a decrease in the abundance of ARGs, while zinc
nanoparticles can promote the entry of ARGs in plasmids into bacteria,with changes in bacterial colonies, nanomaterial content, and plasmid
concentration affecting the transfer of resistance gene dissemination(Guo, 2019). Biochar can increase the adsorption capacity of soil tohygromycin, reduce hygromycin as well as ARGs in soil, and affect thedistribution of ARGs in soil (Duan, 2017). Liu (2018) used sul(I), thedominant gene in sulfonamide ARGs, as the target gene, and did astudy on water quality physicochemical factors and transfer
propagation of ARGs using experimental simulations to investigate theeffects of pH, salinity, humic acid, sulfonamide antibiotics, totalammonia nitrogen, heavy metals, and sulfonamide antibiotics together
with heavy metals on the transfer propagation of sul(I).

KEY WORDS: ARGs; Soil column experiment; water-sedimentinterface; salinity and pH.
INTRODUCTION
Antibiotics are widely used in medical and livestock farming. However,large amounts of antibiotics enter the environment, causing a series ofproblems such as drug-resistant bacteria and ARGs (Pruden, Arabi andStorteboom, 2012). ARGs, as a novel contaminant, can enter the humanbody through the food chain enrichment. Due to heritability, it has
great danger to human health. Since Pruden (2006) identified ARGs as
an emerging contaminant, there has been an increasing interest inantibiotics as well as ARGs. In 2000, the World Health Organization
defined the problem of antibiotic resistance, i.e., ARGs, as one of themost serious challenges facing humanity in the 21st century.

Some scholars also have conducted studies on the transmission processof ARGs in soil. Two experiments (Zhang, 2018; Liu, 2019) were
designed to investigate the horizontal transmission pattern ofintracellular and extracellular ARGs, of which have the intracellularARGs were studied by culturing bacteria, and extracellular resistancegene transfer was done by constructing expression plasmids. Althougha lot of research has been done on the characteristics of resistance genefugacity in water and sediment in aquatic ecosystems, the vertical
distribution and exchange at the water-sediment interface as well as thevertical transfer pattern of ARGs have not been studied clearly in detail.

Studies have shown that aquatic ecosystems are an enriched reservoirof ARGs (Jiang, 2013). Wastewater discharged from sewage treatment

In this study, soil columns experiments were constructed to investigate

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