Significant tipping points of sediment microeukaryotes forewarn increasing antibiotic pollution

Antibiotic pollution imposes urgent threats to public health and microbial-mediated ecological processes.Existing studies have primarily focused on bacterial responses to antibiotic pollution,but they ignored the microeukaryotic counterpart,though microeukaryotes are functionally important(e.g.,predators and saprophytes)in microbial ecology.Herein,we explored how the assembly of sediment microeukaryotes was affected by increasing antibiotic pollution at the inlet(control)and across the outlet sites along a shrimpwastewater discharge channel.The structures of sedimentmicroeukaryotic community were substantially altered by the increasing nutrient and antibiotic pollutions,whichwere primarily controlled by the direct effects of phosphate and ammonium(−0.645 and 0.507,respectively).In addition,tetracyclines exerted a large effect(0.209),including direct effect(0.326)and indirect effect(−0.117),on the microeukaryotic assembly.On the contrary,the fungal subcommunity was relatively resistant to antibiotic pollution.Segmented analysis depicted nonlinear responses of microeukaryotic genera to the antibiotic pollution gradient,as supported by the significant tipping points.We screened 30 antibiotic concentration-discriminatory taxa of microeukaryotes,which can quantitatively and accurately predict(98.7%accuracy)the in-situ antibiotic concentration.Sediment microeukaryotic(except fungal)community is sensitive to antibiotic pollution,and the identified bioindicators could be used for antibiotic pollution diagnosis.

Inconsistent seasonal variation of antibiotics between surface water and groundwater in the Jianghan Plain:Risks and linkage to land uses

Antibiotics are widely used in humans and animals,but their transformation from surface water to groundwater and the impact of land uses on them remain unclear.In this study,14 antibioticswere systematically surveyed in a complex agricultural area in Central China.Results indicated that the selected antibiotic concentrations in surface waters were higher in winter(average:32.7 ng/L)than in summer(average:17.9 ng/L),while the seasonal variation in groundwaters showed an opposite trend(2.2 ng/L in dry winter vs.8.0 ng/L in summer).Macrolides were the predominant antibiotics in this area,with a detected frequency of over 90%.A significant correlation between surface water and groundwater antibiotics was only observed in winter(R^(2)=0.58).This study further confirmed the impact of land uses on these contaminants,with optimal buffer radii of 2500 m in winter and 500 m in summer.Risk assessment indicated that clarithromycin posed high risks in this area.Overall,this study identified the spatiotemporal variability of antibiotics in a typical agricultural area in Central China and revealed the impact of land uses on antibiotic pollution in aquatic environments.

Preliminary studies on occurrence of monensin antibiotic in Bosque River Watershed

Water quality impact due to excessive nutrients has been extensively studied. In recent years, however, micro-pollutants such as pharmaceuticals and hormonal products used in animal agriculture have added an additional impact to overall water quality. Pharmaceuticals used in the poultry, swine, beef, and dairy industries have been detected in various environmental matrices such as, soil, groundwater and surface water. In this study, 26 surface water samples were collected throughout the Bosque River Watershed （BRW） with samples representing a range of land use conditions and locations of major dairy operations. Samples were analyzed using commercially available Enzyme-Linked Immunosorbent Assay test. Of the 26 samples, three samples consistently tested positive for monensin antibiotic with concentration ranging from 0.30 to 3.41 μg/L. These three samples were collected from sites that received varying amount of agriculture wastes （11.7% to 31.3%） and located downstream from sites associated with moderate levels of animal agriculture. The preliminary results suggest that there is a potential for monensin occurrence in the BRW, although initial findings indicate only very low levels.