Antimicrobial Resistance of Escherichia coli From Aquaculture Farms and Their Environment in Zhanjiang, China

Antimicrobial resistance (AMR) has become a major concern worldwide. To evaluate the AMR of Escherichia coli in aquaculture farms of Zhanjiang, China, a total of 90 samples from the water, soil, and sediment of three aquaculture farms (farms I, II, and III) in Zhanjiang were collected, and 90 strains of E. coli were isolated for drug resistance analysis and AMR gene detection. The results indicated that the isolated 90 strains of E. coli have high resistance rates to penicillin, amoxicillin, ampicillin, tetracycline, compound sulfamethoxazole, sulfisoxazole, chloramphenicol, florfenicol, and rifampin (≥70%). Among these antimicrobial drugs, the resistance rate to rifampicin is as high as 100%. Among the isolated 90 strains of E. coli, all of them were resistant to more than two kinds of antimicrobial drugs, the number of strains resistant to nine kinds of drugs was the largest (19 strains), and the most resistant strain showed resistance to 16 kinds of antibacterial drugs. Regarding the AMR genes, among the three aquaculture farms, the most resistance genes were detected in farm II (28 species). The detection rate of blaTEM, blaCIT, blaNDM, floR, OptrA, cmlA, aphA1, Sul2, oqxA, and qnrS in 90 isolates of E. coli was high (≥50%). The detection rate of carbapenem-resistant genes, such as blaKPC, blaIMP, and cfr, was relatively lower ( ≤ 30%), and the detection rate of mcr2 was the lowest (0). At least four AMR genes were detected for each strain, and 15 AMR genes were detected at most. Among them, the number of strains that carried 10 AMR genes was the largest (15 strains). Finally, a correlation analysis found that the AMR genes including blaTEM, blaCIT, floR, OptrA, cmlA, aac(3)-II, Sul2, ereA, ermB, oqxB, qnrA, mcr1, and mcr2 had a high correlation rate with drug resistance (≥50%). To summarize, the 90 strains of E. coli isolated from water, surrounding soil, and sediment samples showed resistance to multi-antimicrobial drugs and carried various antimicrobial resistance genes. Thus, it is essential to strengthen the rational use of antimicrobial drugs, especially the amide alcohol drugs, and control the AMR in the aquaculture industry of Zhanjiang, China.

Sorption Processes in Soils and Sediments

Sorption processes at the mineral–water interface are fundamental to the chemical functioning of soils, and impact the biogeochemical cycling of both trace and major elements in soil and sediment environments [...]

Tracking Recent DDT Contamination in a Northern New England Watershed

Research on declines in loon populations at Squam Lake, New Hampshire, U.S.A., point to multiple potential causes since 2005, including dichlorodiphenyltrichloroethane (DDT). This study narrows down sources of DDT in a small sub-watershed by focusing mainly on collecting and analyzing soil and sediment samples, achieving rapid source area determination of DDT. We find presence of p,p’ isomers of DDT and DDE in the Bennett Brook sub-watershed arising from long-term soil and sediment storage of applications 60 years ago, plus a concentrated and current source area at a former barn. Highest concentrations, 723 μg/kg p,p’-DDT and 721 μg/kg p,p’-DDE, occur in the soils adjacent to the barn’s foundation remnants. DDT exceeds that of the metabolite, DDE, in many soils around Bennett Brook, including but not limited to the barn site. In soils where DDT>DDE, we infer mechanisms that delayed breakdown of DDT over the last 60 years. A Pb-210 dated lake sediment core, collected near the outlet of Bennet Brook, shows continuous accumulation of p,p’-DDE and p,p-DDD after 1951. These residuals likely derived from multiple sources within the sub-watershed, including orchard soils, the barn site, and from mobilized sediment deposits following extreme floods in the watershed. Although the DDT residues fall below mandatory soil remediation levels for the State of New Hampshire, Bennett Brook sediments exceed sediment quality guidelines for protection of aquatic life. Crayfish collected in Bennett Brook have significantly higher concentrations of p,p’-DDE than crayfish collected elsewhere in Squam Lake.

A Study on the Effect of Soil and Sediment Types on the Fugacity Based Multimedia Partitioning of a Contact Fungicide Fluopyram: An Equilibrium Quality Criterion (EQC) Level 1 Approach

Equilibrium Quality Criterion (EQC) Level I calculations have been performed with Standard Equilibrium Quality Criterion (EQC) environment to study the environmental partitioning of a fungicide Fluopyram. Equilibrium Quality Criterion (EQC) Level I calculation assumes no degradation of the chemical, steady-state, and equilibrium conditions between the environmental compartments. The results reveal that the concentration of Fluopyram is expected to be maximum in the sediment compartment, followed by soil and water compartments. The effect of soil and sediment types on partitioning has been studied by systematically varying the densities of these two compartments. In the sediment compartment, the Fluopyram concentration is predicted to be highest if the sediment type is ‘sandy’ and the soil type is ‘clay’.

Synergetic CT, XRF and Geoelectric Imaging for Non-Destructive Soil and Sediment Stratigraphic Study

This paper presents the application of three non-destructive techniques in the study of an agricultural area on the west coast of Peloponnese, Greece. The applied methods include (a) electromagnetic geophysical research using a handheld EM profiler (EMP-400 GSSI), (b) computed tomography (CT) with coring data, and (c) X-ray Fluorescence (XRF) scanning. As electrical conductivity is mainly influenced by the bulk soil, including water content, clay content and mineralogy, organic matter, and bulk density, a comparison of the three applied techniques indicates the same soil stratification and same soil properties with depth. Moreover, the ground-truthing by the undisturbed soil and sediments core retrieved in the centre of the site as well as the laboratory analyses of soil and sediment properties confirm the reliability of the geophysical research and the revealed soil/sediment stratification.