Increase of antibiotic resistance genes via horizontal transfer in single- and two-chamber microbial electrolysis cells.

Microbial electrolysis cells (MECs) have been applied for antibiotic degradation but simultaneously induced antibiotic resistance genes (ARGs), thus representing a risk to disseminate antibiotic resistance. However, few studies were on the potential and risk of ARGs transmission in the MECs. This work assessed conjugative transfer of ARGs under three tested conditions (voltages, cell concentration, and donor/recipient ratio) in both single- and two-chamber MECs. The results indicated that voltages (> 0.9 V) facilitated the horizontal frequency of ARGs in the single-chamber MECs and anode chamber of two-chamber MECs. The donor cell number (donor/recipient ratio was 2:1) increased the transfer frequency of ARGs. Furthermore, voltages ranged from 0.9 to 2.5 V increased reactive oxygen species (ROS) production and cell membrane permeability in MECs. These findings offer new insights into the roles of ARG transfer under different applied voltages in the MECs, which should not be ignored for horizontal transfer of antibiotic resistance.

[Quantitative remote sensing retrieval for algae in inland waters].

Chlorophyll is a very important indictor for the eutrophication status of lake water body. Using remotely sensed data to achieve real-time dynamic monitoring of the spatial distribution of chlorophyll has great importance. This paper aims to find the best band for the hyperspectral ratio model of chlorophyll-a, and take advantage of this model to implement remote sensing retrieval of algae in Taihu Lake. By the analysis of the spectral reflectance and water quality sampling data of the surface water body, the regression model between the ratio of reflectance and chlorophyll-a was built, and it was showed that the ratio model between the wavelengths around 700 and 625 nm had a relatively high coefficient value of determination (R2), while the ratio model constructed with 710 nm and visible wavelengths showed a descended R2 following with the increment of the visible wavelengths. Combined with in-situ water samplings analysis and spectral reflectance measurement, the results showed that it's possible to retrieve algae water body using the MODIS green index (GI). The spatial distributions of chlorophyll-a and algae in Taihu Lake were extracted successfully using MODIS data with the algorithm developed in this paper.

[Chemical Constitution and Carbon Isotopic Compositions of PM2.5 in the Northern Suburb of Nanjing in Spring].

PM2.5 is an important atmospheric pollution component and has a complicated composition. The chemical constitution of PM2.5 in Nanjing northern region during March 2016 was analyzed using the Dinoex ICS-3000 and ICS-2000 ion chromatograph and DRI Model 2001A thermal/optical carbon analyzer, and the carbon isotopic compositions were analyzed using EA-IRMS from Thermo Scientific in order to explore pollution behaviors and source apportionment of PM2.5. The results showed that the mean concentration of atmospheric PM2.5 was (106.16±48.70) µg·m-3, which equated with heavy pollution. Meanwhile, 88% of the samples exhibited the presence of the secondary organic pollutants. The average concentration of secondary organic carbon (SOC) was (3.58±2.78) µg·m-3 and this high concentration was attributed to the reaction of O3 with atmospheric hydrocarbons under ultraviolet light on sunny days. In addition, δ13CTC in PM2.5 ranged from -26.56‰ to -23.75‰ and the mean was (-25.47‰±0.63‰). Combining the various analyses, we concluded that atmospheric PM2.5 for the study area was mainly derived from coal combustion, vehicle exhaust, geology (natural sources) and biomass burning.

[Sulfur Sources and Oxidation Pathways in Summer Aerosols from Nanjing Northern Suburbs Using S and O Isotopes].

The sulfur and oxygen isotopic compositions of sulfate in PM2.5 were determined by EA-IRMS to study the sulfur sources and oxidation formation pathways of sulfates in PM2.5 from Nanjing northern suburbs during July 2014. The results indicated that δ34 S values of sulfate ranged from 1.7‰ to 4.8‰ with an average of 3.2‰±1.0‰, while δ18O values ranged from 7.5‰ to 12.9‰ with an average of 9.3‰±1.7‰. Comparing the δ34 S values of aerosol sulfate and potential pollution sources, we concluded that the sulfur source of PM2.5 was mainly local coal combustion and vehicle exhaust. In addition, the secondary sulfate was dominant in PM2.5, and 59.3% of the formation of the secondary sulfate was caused by SO2 homogeneous oxidation. In addition, the heterogeneous oxidation of SO2 in the atmosphere was dominated by ferrous iron oxidation in excess O2. The main mechanisms of homogeneous oxidation include oxidation in the presence of electric discharge (presumably forming O3) and NO2.

[Applicability of established drought index in Huang-Huai-Hai region based on actual evapotranspiration.] / åŸºäºŽå®žé™ è’¸æ•£æž„å»ºçš„å¹²æ—±æŒ‡æ•°åœ¨é»„æ·®æµ·åœ°åŒºçš„é€‚ç”¨æ€§.

Based on the modeled products of actual evapotranspiration with NOAH land surface model, the temporal and spatial variations of actual evapotranspiration were analyzed for the Huang-Huai-Hai region in 2002-2010. In the meantime, the agricultural drought index, namely, drought severity index (DSI) was constructed, incorporated with products of MOD17 potential evapotranspiration and MOD13 NDVI. Furthermore, the applicability of established DSI in this region in the whole year of 2002 was investigated based on the Palmer drought severity index (PDSI), the yield reduction rate of winter wheat, and drought severity data. The results showed that the annual average actual evapotranspiration within the survey region increased from the northwest to the southeast, with the maximum of 800-900 mm in the southeast and the minimum less than 300 mm in the northwest. The DSI and PDSI had positive correlation (R2=0.61) and high concordance in change trend. They all got the low point (-0.61 and -1.33) in 2002 and reached the peak (0.81 and 0.92) in 2003. The correlation between DSI and yield reduction rate of winter wheat (R2=0.43) was more significant than that between PDSI and yield reduction rate of winter wheat (R2=0.06). So, the DSI reflected a high spatial resolution of drought pattern and could reflect the region agricultural drought severity and intensity more accurately.

[Investigations on Sulfur and Carbon Isotopic Compositions of Potential Polluted Sources in Atmospheric PM2.5 in Nanjing Region].

Potential pollution sources of atmospheric PM2.5 in Nanjing region were collected, and sulfur and carbon isotopic compositions were determined by EA-IRMS synchronously. The results showed that δ³4S and δ¹³C values ranged from 1.8‰-3.7‰ and -25.50‰- -23.57‰ in coal soot particles; 4.6‰-9.7‰ and -26.32‰- -23.57‰ in vehicle exhaust; 5.2‰-9.9‰ and -19.30‰- -30.42‰ in straw soot particles, respectively. Besides, the δ¹³C value of dust was -13.45‰. It can be observed that sulfur isotopic compositions in coal soot were lower, while the carbon isotopic composition in dust was higher. Comparing with δ³4S and δ¹³C values in domestic and foreign polluted sources, we found that sulfur and carbon isotopes in atmospheric PM2.5 in Nanjing region presented an obvious regional characteristics. Therefore, the source spectrum of sulfur and carbon isotopic compositions in Nanjing region might provide an insight into source apportionment of atmospheric PM2.5.

[Nitrogen Removal and the Characteristics of Denitrification Bacteria Using NUA-DAS Ecofilter].

A small-scale combined ecofilter was constructed using neutralized-used acid residue (NUA) and dewatered alum sludge (DAS), and the nitrogen removal for wastewater treatment and characteristics of denitrification bacteria using the NUA-DAS ecofilter were studied. After the system was stabilized, the average removal rates of COD, TN, NO3--N in the final effluents were 60%, 70% and 95%, respectively, and the range of NO3--N concentration in the effluents was only 0.02-0.55 mg·L-1. Furthermore, the richness and similarity of three types of functional genes (nirS, nirK and nosZ) for denitrification in different substrates during the operation period were analyzed using PCR-DGGE method. These results showed that the richness of all denitrification bacteria at NUA and DAS increased remarkably after operation for 30 and 60 days compared to that in fresh substrate, and the richness was basically the same for the same kind of gene at the identical substrate regardless of depth gradient and operation period. The richness of nirS, nirK and nosZ detected in the NUA and DAS followed the order of nosZ > nirK > nirS. It was also revealed that spatial location had an apparent influence on the community structure of denitrifying bacteria (nirS, nirK and nosZ) but operation time had no obvious effect. Finally, nirK might be the most suitable for the environment in the system, and the adaptive capacity of denitrification bacteria (nirS, nirK and nosZ) in NUA could be superior to that in DAS.

[Characteristics and sources apportionment of OC and EC in PM1.1 from Nanjing].

The concentrations of OC and EC in PM1.1 collected from Nanshi (NS) and Nanhua (NH) in 2011 were analyzed using DRI Model 2001A Thermal Optical Carbon Analyzer. In addition, source apportionment was simultaneously evaluated. The results showed that the annual average concentrations of OC and EC in PM1.1 were 10. 10 µg x m(-3) and 2.52 µg x m(-3) in NS area, and 11.22 µg x m(-3) and 3.12 µg x m(-3) in NH area, respectively. This result indicated that OC and EC pollution in NH was more serious than that in NS area. Meanwhile, the concentrations of OC and EC in winter and spring were obviously higher compared to those in summer in these two sampling sites, which was mainly ascribed to the increased coal combustion and the unfavorable emission condition of air pollutants in summer and spring. We noted that the SOC/TOC value was the highest in summer and the lowest in winter. In addition, the SOC concentration was observed to show a positive correlation with ozone concentrations, which indicated that the photochemical reaction was a main way of SOC formation in autumn.

[Tracing Sources of Sulfate Aerosol in Nanjing Northern Suburb Using Sulfur and Oxygen Isotopes].

Abstract: To trace the sources of sulfate contributing to atmospheric aerosol, PM2.5 samples for isotopic analysis were collected in Nanjing northern suburb during January 2014. The sulfur and oxygen isotopic compositions of sulfate from these samples were determined by EA-IRMS. Source identification and apportionment were carried out using stable isotopic and chemical evidences, combined with absolute principal component analysis (APCA) method. The Δ34S values of aerosol sulfate ranged from 2.7 per thousand to 6.4 per thousand, with an average of 5.0 per thousand ± 0.9 per thousand, while the Δ18O values ranged from 10.6 per thousand to 16.1 per thousand, with an average of 12.5 per thousand ± 1.37 per thousand. In conjunction with air mass trajectories, the results suggested that aerosol sulfates were controlled by a dominance of local anthropogenic sulfate, followed by the contributions of long-distance transported sulfate. There was a minor effect of some other low-Δ34S valued sulfates, which might be expected from biogenic sources. Absolute principal component analysis results showed that the contributions of anthropogenic sulfate and long-distance transported sulfate were 46.74% and 31.54%, respectively.

[Radiolytic Decomposition of Ciprofloxacin Hydrochloride in Aqueous Solution Using γ Irradiation].

Effects of initial concentrations, pH values, different additives and composite pollutants on ciprofloxacin hydrochloride removal using γ irradiation were investigated. The experiments results showed γ irradiation could effectively remove ciprofloxacin hydrochloride; low initial concentration and strongly acidic condition were favorable for CIP removal using γ irradiation; the degradation of CIP was inhibited upon the addition of CO3(2-) and methanol, which indicated that the degradation of CIP might be mainly ascribed to *OH oxidation and the direct decomposition of CIP molecules induced by irradiation. BrO3- showed a synergistic effect with CIP in degradation of the composite pollutants when mixed together with CIP for γ irradiation, and the removal rates of both pollutants were improved. At an absorbed dose of 400 Gy, the removal rates of CIP and BrO3- were increased by 18.74% and 1.81%, respectively. The removal rates of TOC and COD were 15.22% and 61.44%, respectively, when the 100 mg x L(-1) CIP was degraded by γ irradiation at the absorbed dose of 6 000 Gy.

[Size distributions of organic carbon and elemental carbon in Nanjing aerosol particles].

The concentrations and size distributions of organic carbon (OC) and elemental carbon (EC) in particles collected in Nanjing Normal University representing urban area and in Nanjing College of Chemical Technology standing for industrial area were analyzed using Model 2001A Thermal Optical Carbon Analyzer. The mass concentrations were the highest with the size below 0.43 microm in urban and industrial area. OC accounted for 20.9%, 21.9%, 29.6%, 27.9% respectively and those were 24.0%, 23.5%, 31.4%, 22.6% respectively for EC in the four seasons in urban area. In the industrial area, OC accounted for 18.6%, 45.8%, 26.6%, 25.9% respectively and the proportions of EC were 16.7%, 60.9%, 26.3%, 24.3% respectively. Overall, OC and EC were enriched in fine particles below 2.1 microm and they accounted for the highest proportion in summer in urban area while it did not show significant seasonal variation for industrial area. SOC in fine particles achieved high values in summer while the unobvious seasonal variation in coarse particles might be attributed to the contribution of different pollution sources and meteorological factors. Correlations and OC/EC ratio method implied that OC and EC mainly came from vehicles exhaust and coal combustion in fine particles while they were also related to biomass combustion and cooking in coarse particles.

[Stable carbon isotopic composition in PM 2.1 in Nanjing Region].

Stable carbon isotopes (delta13C) in aerosol fine particles (PM2.1) collected in Nanjing Normal University representing urban area, and in Nanjing College of Chemical Technology standing for suburban industrial area, were analyzed using EA-IRMS. Besides, sources of carbonaceous contents were studied and the pollution characteristics of total carbon (TC) were evaluated. The annual average concentrations of TC in urban area and suburban industrial area were 15.94 microg.m-3 and 17.17 microg.m-3, respectively. The proportions for TC in PM2.1 were 17.18% and 16. 40% , indicating that carbonaceous pollution was more serious and the pollutants were more complex in suburban industrial area. The average delta13C for winter, spring, summer and autumn were -24. 42 per thousand +/- 1. 12 per thousand, -25. 19 per thousand +/- 1. 92% per thousand, - 25.79 per thousand +/- 0.45 per thousand and - 25.58 per thousand + 0. 65 per thousand, respectively in urban area and - 25.34 per thousand +/- 1. 18 per thousand, -25. 55 per thousand +/- 1. 50 per thousand, -25. 31 per thousand +/- 0. 55%o and -25. 38 per thousand +/- 0. 82 per thousand, respectively in suburban area. Correlation analysis and isotopic signatures of potential sources suggested that carbonaceous contents mainly came from gasoline vehicles exhaust in urban area, and might be attributed to the vehicle exhaust emissions and industrial emissions in suburban area. In addition, coal combustion,biomass burning and geological sources might have important contribution to aerosols in winter and spring. Back trajectory analysis implied that the long-range transport had considerable contribution to the carbonaceous aerosol in winter and spring. However, the major sources might be attributed to local emissions in the other two seasons.