Antibiotic resistance gene (ARG) residues and the mode of transmission in marine environments remain unclear. The sulfonamide (SAs) concentrations, different genes and total bacterial abundance in seawater and sediment of the Northern Yellow Sea were analyzed. Results showed the genes sul I and sul II were present at relatively high concentrations in all samples, whereas the gene sul III was detected fewer. The ARGs concentrations in the sediment were 103 times higher than those in water, which indicated sediment was essential ARG reservoir. Statistical analysis revealed the total antibiotic concentration was positively correlated with the relative abundance of the gene sul I and sul II. The relative abundances of the gene sul I and the gene sul II were also correlated positively with those of the gene int1. This correlation demonstrated that SAs exerted selective pressure on these ARGs, whereas the gene int1 could be implicated in the propagation of the genes sul I and sul II in marine environments.

The Cunha Canal watershed, which is located in the municipality of Rio de Janeiro, suffered severe environmental degradation in recent decades due to rapid urban population growth. However, this substantial growth did not result in social development; instead, it exacerbated existing environmental and social problems. This study aimed to evaluate the pollution of the Canal do Cunha and Guanabara Bay, using GIS for mapping based on the result of the heavy metal concentrations obtained by spectrometry (ICP-OES). The analyzed data were monitored at five collection points. Five heavy metals (Cd, Pb, Cu, Ni and Zn) were evaluated. The results showed that the waters of the Cunha Canal watershed and the west side of Guanabara Bay have been altered and degraded. The concentration of heavy metals in the water was lower than the concentration in the sediments. The behaviors of the studied metals differed during the rainy and dry periods.

We assessed the effects of 17α-ethinylestradiol (EE2) on spawning and reproductive behavior of the brackish medaka Oryzias melastigma at environmental concentrations. Breeding pairs were exposed to EE2 at either lower concentrations (0, 1, and 10ng/L) or higher concentrations (0, 50, and 100ng/L) for 14days. Swimming performance and reproductive behavior (following, dancing, and copulation) of the males were analyzed at the end of exposure. Additionally, gonad histology was conducted in the males in the higher EE2 experiment. We found that spawning was significantly inhibited in the 50–100ng/L EE2 groups. Swimming performance was not affected in all groups. Dancing and copulation were significantly suppressed in the 50–100ng/L groups. No effect was observed in testis histology in the 50–100ng/L groups. Our data suggests that reproductive behavior of O. melastigma can be utilized as a behavioral endpoint for ecotoxicology studies of endocrine disruptors in estuarine/marine environments.

The Guaxindiba Estuarine System is located in the northeast portion of Guanabara Bay. Despite the location inside an environmental protection zone, the main affluent of the river runs through the extremely urbanized area of the cities of Niterói and São Gonçalo. In order to understand the contamination levels of the estuary, 35 surface sediment samples were collected along the river and estuarine area and analyzed for the presence of heavy metals, PAHs, organochlorated pesticides, polychlorinated biphenyl and other contaminants. The analyzed data revealed a greatly affected environment with respect to most of these substances. The results suggested propitious deposits of contaminants, with high concentrations of organic matter and fine sediment. The levels of heavy metal in the entire estuarine system were high compared with the local background. The total mean concentrations of As, Cd, Pb, Cu, Zn, Hg, Cr and Ni in the surface sediments were: 3.74; 0.03; 19.3; 15.0; 99.0; n.d.; 29.0; and 22.0mg/kg, respectively, confirming, in certain cases, the high capacity of the environment to concentrate pollution.

Median enterococci counts of beach water samples gradually increased at statistically significant levels (χ2: 26.53, df: 4; p<0.0001) with increasing proximity to river influx. The difference in proportion of antibiotic resistant enterococci in beach water and river water samples was statistically significant (p<0.05) for the tested antibiotics with river isolates generally presenting higher resistance frequencies. Virulence genes cyl, esp, gelE and asa were detected at varying frequencies (7.32%, 21.95%, 100% and 63.41% respectively) among river isolates. On the other hand, the prevalence of these genes was lower (0%, 20%, 67.27% and 41.82% respectively) among beach water isolates. Multi-Locus-Sequence-Typing analysis of Enterococcusfaecalis presented four sequence types (ST) one of which shared six out of seven tested loci with ST6, a member of the clonal complex of multi-drug resistant strains associated with hospital outbreaks.

The occurrence and distribution of five groups of antibiotics were investigated in the surface sediments of the Yangtze Estuary over four seasons. Four tetracyclines (TCs), sulfaquinoxaline (SQ), enrofloxacin (EFC) and thiamphenicol (TAP) were detected in all the samples, while sulfamerazine (SM) and sulfathiazole (ST) showed the lowest detection frequency. The detection frequencies and antibiotic concentrations were generally higher in January and May, indicating that low flow conditions and low temperature might enhance the persistence of antibiotics in sediment. Antibiotic levels varied with location, with the highest concentrations being observed around river discharges and sewage outfalls. Furthermore, a positive correlation between the concentration of quinolones and TOC revealed the significant role played by TOC. The concentration of quinolones at Wusongkou exceeded the trigger value (0.10mgkg−1) of the Steering Committee of the Veterinary International Committee on Harmonization (VICH), which should be paid attention to in future studies.

A recent study demonstrated that 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) may have an adverse effect on the reproduction in marine medaka (Oryzias melastigma), but the molecular mechanisms remain largely unknown. In this study, we investigated the protein expression profiles of male and female gonads of O. melastigma exposed to dietary BDE-47 at two dosages (0.65 and 1.30μg/g/day, respectively) for 21days. Extracted proteins were labeled with iTRAQ and analyzed on a MALDI TOF/TOF analyzer, as results, 133 and 144 unique proteins were identified in testis and ovary, respective, and they exerted dose- and sex-dependent expression patterns. In testis, among the 42 differentially expressed proteins; down-regulation of histone variants and parvalbumins implicated BDE-47 may disrupt the spermatogenesis and induce sterility in fishes. In ovary, 38 proteins were differentially expressed; the elevation of vitellogenins and apolipoprotein A–I expression indicated BDE-47 acts as an estrogen-mimicking compound and led to reproductive impairment in O. melastigma.

Metro rail has been introduced in Delhi in 2002 to provide alternative mode of public transportation. The introduction of metro rail has resulted in passenger ridership shift from road based transport to metro rail. In order to estimate the emissions (CO, HC, NOx, PM and CO2), metro rail ridership has been converted to equivalent number of on–road vehicles which otherwise would have been playing in the absence of mass rapid transit system. The emission estimation for the year 2006 and 2011 corresponding to the completion of phase I and phase II of Delhi metro rail has been made using emission and deterioration factor(s) for different category and vintage of vehicles. The sensitivity analysis has been carried out to assess the influence of different combination of input parameters such as modal shift, engine technology, and fuel type on emissions. In addition, CO2 emissions saved due to shifting of motor vehicle ridership to metro rail has been estimated and compared with the CO2 produced (off–site) due to electricity consumption by Delhi metro rail for its various operations. The findings indicate that present modal shift scenario does not yield CO2 benefits. However, it is expected that with the increase in metro ridership, changes in modal shift and energy conservation initiatives by Delhi metro, CO2 emission saving could be possible.

Hypoxia alters the oxidation–reduction balance and the biogeochemical processes in sediments, but little is known about its impacts on the microbial community that is responsible for such processes. In this study, we investigated the effects of hypoxia and the ubiquitously dispersed flame-retardant BDE47 on the bacterial communities in marine surface sediments during a 28-days microcosm experiment. Both hypoxia and BDE47 alone significantly altered the bacterial community and reduced the species and genetic diversity. UniFrac analysis revealed that BDE47 selected certain bacterial species and resulted in major community shifts, whereas hypoxia changed the relative abundances of taxa, suggesting slower but nonetheless significant community shifts. These two stressors targeted mostly different taxa, but they both favored Bacteroidetes and suppressed Gammaproteobacteria. Importantly, the impacts of BDE47 on bacterial communities were different under hypoxic and normoxic conditions, highlighting the need to consider risk assessments for BDE47 in a broader context of interaction with hypoxia.