The occurrence of 22 antibiotics in water samples, sediments, fish and shellfish in aquaculture area of the Pearl River Estuary (Zhuhai and Daya Bay) was studied, using ultrasonic extraction combined with ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The main pollutants detected in aquaculture area of the Pearl River Estuary are quinolones such as norfloxacin, ofloxacin, ciprofloxacin and flumequine. Higher Σantibiotics were observed in Zhuhai Bay in water and sediments compared with Daya Bay. The concentrations of antibiotics in water samples, ranging from 0.13 (sulfamethoxazole) to 4.68 (spectinomycin) ng/L on average, were strongly affected by precipitation. The concentrations of antibiotics in sediments, ranging from 0.02 (isochlortetracycline) to 8.77 (spectinomycin) ng/g (dry weight) on average, accumulated over time. The concentrations of antibiotics in seafood ranged from 0.06 (sulfamerazine) to 46.75 (norfloxacin) ng/g (dry weight). The concentration levels of antibiotics in shellfish and fish were similar and did not show any significant difference. The correlation analysis showed that the concentration levels of antibiotics among sediments were the same; for most seafood, it was same; and for water samples, the difference was great.
A fast and simple method for simultaneous determination of fifteen antibiotics (sulfadiazine, ciprofloxacin, penicillin, spechromycin and roxithromycin) in mussels using ultrasound extraction, solid phase extraction purification and ultra performance liquid chromatography-tandem mass spectrometric was established. The mussel samples were extracted by ultrasonic extraction, followed by solid-phase extraction (SPE) as the cleanup procedure. Ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS) was used for identification and quantification of antibiotics. The performance of two kinds of SPE cartridges, Oasis HLB and Oasis PRiME HLB, was compared, with the latter showing better results. Recoveries ranged from 64% to 121% at spiking levels of 50 ng/g, with RSD being 0.5%–19%, and from 67% to 117% at spiking levels of 100 ng/g, with RSD being 1%–9%. Limits of detection (LODs) ranged from 0.004 to 0.5 ng/g (dry weight) and limits of quantification (LOQs) ranged from 0.013 to 1.67 ng/g (dry weight). The recoveries were reasonable and the detection limit was low. Finally, the method was successfully applied to the determination of the target antibiotics in mussel samples (Hyriopsis cumingii) collected from Poyang Lake. 9 out of 15 selected antibiotics were detected in the collected mussel tissues. The concentration and detection frequency of trimethoprim in mussels were the highest. The concentration of trimethoprim was 78.8 ng/g, followed by spectinmycin (41.2 ng/g) and ciprofloxacin (39.8 ng/g).
Using one kind of main mercury methylation iron reducing bacteria of Geobacter sulphurreducens PCA strains as targeting bacteria, two kinds of quinolones ciprofloxacin and ofloxacin were chosen to study the influence of antibiotics on PCA strains and its ability to methylate mercury in combined pollution. The experiment results showed that a promoting effect of antibiotics on growth PCA was found under the low concentration. Through the detection of the concentration of antibiotic and the figure of ESI scan, it was found that Geobacter sulphurreducens PCA could metabolize ofloxacin, but ciprofloxacin could not be degraded by Geobacter sulphurreducens PCA. Methylation of mercury was promoted by the presence of two kinds of antibiotics, the methyl-mercury conversion rate of ofloxacin to Geobacter sulphurreducens PCA was 4.21 times higher than that of the control group, ciprofloxacin was 2.27 times, and the addition of two mixed kinds of antibiotics was nearly 2 times respectively. In the mixed solution, there is no superimposed effect of methyl-mercury.
Based on the theory of man-land relationship area system, following the research ideas, which were factors to express the feature and features to group the type and types to guide the models and models to improve factors, the social economic factors and natural environment factors of rural settlement were defined clearly. The characteristics of the inequality of rural industry-labor structure, the livability of rural living environment and the intensity of rural residential land were analyzed quantitatively by the coordination coefficient model and multifactor comprehensive evaluation method. Qualitative coupling method of elements and characteristics were used to classify the rural settlements as eight types in the same county, and eleven rural residential consolidation models were proposed from the three aspects of resources allocation, structure optimization and space reconstruction in the light of the limiting factors of different rural settlement type. The empirical results show that the difference is significant in the aspect of rural settlements elements and regional characteristics in Pinggu district, Beijing. There are more restrictive factors for rural residential area sustainable utilization. 55.64% villages are imbalance in the aspect of industry-labor structure, 52% villages are unfavorable relatively in the aspect of housing conditions, 44.36% villages are less intensive in the aspect of land use, and the formation of the imbalance-not livable-height intensity is too much in the whole region. Single factor special consolidation and multi-factor comprehensive consolidation, which include upgrading of rural industrial structure, transferring of surplus labor force, renewal and reorganization of rural living environment factors, reconstruction of the urban and rural system and spatial agglomeration, are the core contents of rural residential land consolidation and rich and beautiful countryside construction.
To fulfill the need of studying the deuterium retention in nuclear materials, the authors set up an NRA to analyze device with three channel detecting system based on 4.5 MV electrostatic accelerator in Peking University, and developed a multi-energies NRA method for quantitative depth profiling deuterium. With the simultaneous energy spectra of p and 4He created by the D (3He, p) 4He nuclear reaction, by adopting several different incident 3He+ energies (0.8?3.6 MeV), a reasonable better depth resolution and higher sensitivity in a larger analyzing depth could be obtained. The authors also measured differential cross-section of the 3He-D reaction at 135°. The relative accuracy of these data was better than ±3.9%. The initial measurement of concentration and depth profiles of D was carried out, using targets of implanted PC-W samples, as well as CMSIIW samples from a W-coated outer divertor tile of TOKAMAK AUG near the strike points. A ~6 μm analyzed depth could be obtained with a depth resolution less than 1.5 μm throughout the whole detecting range and a ~20 nm minimal resolution at the sample surfaces. The detection limit was around 5×1019 D/m2. Apart from the statistical and fitting error of NRA spectra, the NRA system had an experimental error of ±7.5% from the parameter measurement.
Based on research progress on economic value of ecosystem services, taking the plain afforestation data in Beijing as the study area, this paper explores the ecosystem service value evaluation of the 6.67×104 hm2 plain afforestation area. Shadow engineering method, opportunity cost method and opportunity cost method are used. The results show that, the total plain afforestation ecosystem service value is about 325.89×108Yuan. The importance of each ecological service function, in descending order: climate regulation function, air purification function, function of fixing carbon and releasing oxygen, solid soil fertilizer function, reduce the noise function, the function of water conservation. The results provide reference for further promoting the Beijing plain afforestation project construction and the ecological compensation policy and determine the ecological compensation standard.
