细化搜索
结果 171-180 的 3,207
Succession of microbial functional communities in response to a pilot-scale ethanol-blended fuel release throughout the plume life cycle 全文
2015
Ma, Jie | Deng, Ye | Yuan, Tong | Zhou, Jizhong | Alvarez, Pedro J.J.
GeoChip, a comprehensive gene microarray, was used to examine changes in microbial functional gene structure throughout the 4-year life cycle of a pilot-scale ethanol blend plume, including 2-year continuous released followed by plume disappearance after source removal. Canonical correlation analysis (CCA) and Mantel tests showed that dissolved O2 (which was depleted within 5 days of initiating the release and rebounded 194 days after source removal) was the most influential environmental factor on community structure. Initially, the abundance of anaerobic BTEX degradation genes increased significantly while that of aerobic BTEX degradation genes decreased. Gene abundance for N fixation, nitrification, P utilization, sulfate reduction and S oxidation also increased, potentially changing associated biogeochemical cycle dynamics. After plume disappearance, most genes returned to pre-release abundance levels, but the final functional structure significantly differed from pre-release conditions. Overall, observed successions of functional structure reflected adaptive responses that were conducive to biodegradation of ethanol-blend releases.
显示更多 [+] 显示较少 [-]Can we improve pollen season definitions by using the symptom load index in addition to pollen counts? 全文
2015
Bastl, Katharina | Kmenta, Maximilian | Geller-Bernstein, Carmi | Berger, Uwe | Jäger, Siegfried
Airborne pollen measurements are the foundation of aerobiological research and provide essential raw data for various disciplines. Pollen itself should be considered a relevant factor in air quality. Symptom data shed light on the relationship of pollen allergy and pollination. The aim of this study is to assess the spatial variation of local, regional and national symptom datasets. Ten pollen season definitions are used to calculate the symptom load index for the birch and grass pollen seasons (2013–2014) in Austria. (1) Local, (2) regional and (3) national symptom datasets are used to examine spatial variations and a consistent pattern was found. In conclusion, national datasets are suitable for first insights where no sufficient local or regional dataset is available and season definitions based on percentages provide a practical solution, as they can be applied in regions with different pollen loads and produce more constant results.
显示更多 [+] 显示较少 [-]Isotopic fractionation during the uptake and elimination of inorganic mercury by a marine fish 全文
2015
Xu, Xiaoyu | Wang, Wen-Xiong
This study investigated the mass dependent (MDF) and independent fractionation (MIF) of stable mercury isotopes in fish during the uptake and elimination of inorganic species. Mercury accumulation during the exposure led to re-equilibration of organ isotopic compositions with the external sources, and elimination terminated the equilibrating with isotope ratios moving back to the original values. Generally, the isotopic behaviors corresponded to the changes of Hg accumulation in the muscle and liver, causing by the internal transportation, organ redistribution, and mixing of different sources. A small degree of MDF caused by biotransformation of Hg in the liver was documented during the elimination, whereas MIF was not observed. The absence of MIF during geochemical and metabolic processes suggested that mercury isotopes can be used as source tracers. Additionally, fish liver is a more responsive organ than muscle to track Hg source when it is mainly composed of inorganic species.
显示更多 [+] 显示较少 [-]Studies on the treatment efficiency of sediment phosphorus with a combined technology of PCFM and submerged macrophytes 全文
2015
Zhang, Yi | He, Feng | Xia, Shibin | Zhou, Qiaohong | Wu, Zhenbin
The removal efficiency of sediment phosphorus (P) in all fractions with a combined technology of porous ceramic filter media (PCFM) and submerged macrophytes was studied in Donghu Lake, Wuhan, China. The adsorption kinetic models of the sediment P in all fractions on PCFM could be described well by a power function equations (Qt = k · ta, 0 < a < 1). The P removal capacity of the combination of PCFM and Potamogeton crispus, a submerged macrophyte, was higher for all P forms than that of the combination of PCFM and another macrophyte, Vallisneria spiralis. This study suggested that the combination of PCFM and macrophytes could achieve a synergetic sediment P removal because the removal rates of the combinations were higher than the sum of that of PCFM and macrophytes used separately. The combined technology could be further applied to treat internal P loading in eutrophic waters.
显示更多 [+] 显示较少 [-]Cyhalofop-butyl has the potential to induce developmental toxicity, oxidative stress and apoptosis in early life stage of zebrafish (Danio rerio) 全文
2015
Zhu, Lizhen | Mu, Xiyan | Wang, Kai | Chai, Tingting | Yang, Yang | Qiu, Lihong | Wang, Chengju
Cyhalofop-butyl is a selective herbicide widely employed in paddy field, which can transfer into aquatic environments. However, details of the environmental risk and aquatic toxicity of cyhalofop-butyl have not been fully investigated. In this study, zebrafish (Danio rerio) embryos were exposed to a range of cyhalofop-butyl until 120 hour post-fertilization (hpf) to assess embryonic toxicity of the chemical. Our results demonstrated that cyhalofop-butyl was highly toxic to zebrafish embryos, with concentration-dependent negative effects in embryonic development. In addition, exposure to cyhalofop-butyl resulted in significant increases in reactive oxygen species (ROS) production and cell apoptosis in heart area. The mRNA levels of the genes related to oxidative stress and apoptosis were also altered significantly after cyhalofop-butyl exposure. Moreover, the activity of capspase-9 and caspase-3 were significantly increased. Therefore, we speculated that oxidative stress-induced apoptosis should be responsible for abnormal development during embryogenesis after cyhalofop-butyl exposure.
显示更多 [+] 显示较少 [-]Iron-coupled inactivation of phosphorus in sediments by macrozoobenthos (chironomid larvae) bioturbation: Evidences from high-resolution dynamic measurements 全文
2015
Chen, Musong | Ding, Shiming | Liu, Ling | Xu, Di | Han, Chao | Zhang, Chaosheng
The effects of chironomid larvae bioturbation on the lability of phosphorus (P) in sediments were investigated through sediment incubation for 140 days. High-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) techniques were applied to obtain soluble and labile P/Fe profiles at a millimeter resolution, respectively. The larvae bioturbation decreased concentrations of soluble/labile P and Fe by up to over half of the control at the sediment depths of influence up to 70 and 90 mm respectively. These effects continued over 116 days and disappeared on the 140th days due to eclosion of chironomid larvae. Labile P was highly correlated with labile Fe, while a weak correlation was observed between soluble P and soluble Fe. It was concluded that Fe(II) oxidation and its enhanced adsorption were the major mechanisms responsible for the decreases of soluble and labile P.
显示更多 [+] 显示较少 [-]Positive relationship detected between soil bioaccessible organic pollutants and antibiotic resistance genes at dairy farms in Nanjing, Eastern China 全文
2015
Sun, Mingming | Ye, Mao | Wu, Jun | Feng, Yanfang | Wan, Jinzhong | Tian, Da | Shen, Fangyuan | Liu, Kuan | Hu, Feng | Li, Huixin | Jiang, Xin | Yang, Linzhang | Kengara, Fredrick Orori
Co-contaminated soils by organic pollutants (OPs), antibiotics and antibiotic resistance genes (ARGs) have been becoming an emerging problem. However, it is unclear if an interaction exists between mixed pollutants and ARG abundance. Therefore, the potential relationship between OP contents and ARG and class 1 integron-integrase gene (intI1) abundance was investigated from seven dairy farms in Nanjing, Eastern China. Phenanthrene, pentachlorophenol, sulfadiazine, roxithromycin, associated ARG genes, and intI1 had the highest detection frequencies. Correlation analysis suggested a stronger positive relationship between the ARG abundance and the bioaccessible OP content than the total OP content. Additionally, the significant correlation between the bioaccessible mixed pollutant contents and ARG/intI1 abundance suggested a direct/indirect impact of the bioaccessible mixed pollutants on soil ARG dissemination. This study provided a preliminary understanding of the interaction between mixed pollutants and ARGs in co-contaminated soils.
显示更多 [+] 显示较少 [-]Tenax as sorption sink for in vitro bioaccessibility measurement of polycyclic aromatic hydrocarbons in soils 全文
2015
Li, Chao | Cui, Xin−Yi | Fan, Ying−Ying | Teng, Ying | Nan, Zhong−Ren | Ma, Lena Q.
Physiologically based in vitro methods have been developed to measure bioaccessibility of organic contaminants in soils. However, bioaccessibility of hydrophobic organic contaminants (HOCs) can be underestimated by in vitro tests if gastrointestinal (GI) solution fails to provide sufficient sorption sink for HOCs. To circumvent this drawback, Tenax was included in GI solution as sorption sink to trap mobilized HOCs and maintain the desorption gradient between soil and GI solution. Polycyclic aromatic hydrocarbons (PAHs) were selected as target HOCs, and physiologically based extraction test (PBET) was selected as the in vitro method. Inclusion of Tenax in GI solution increased bioaccessibility of PAHs in five spiked soils from 8.25–20.8% to 55.7–65.9% and the bioaccessibility of PAHs in a field contaminated soil from 3.70–6.92% to 16.3–31.0%. Our results demonstrated the effectiveness of Tenax as sorption sink to enhance PAH mobilization in bioaccessibility measurement in soils.
显示更多 [+] 显示较少 [-]Environmentally realistic concentrations of the antibiotic Trimethoprim affect haemocyte parameters but not antioxidant enzyme activities in the clam Ruditapes philippinarum 全文
2015
Matozzo, Valerio | De Notaris, Chiara | Finos, Livio | Filippini, Raffaella | Piovan, Anna
Several biomarkers were measured to evaluate the effects of Trimethoprim (TMP; 300, 600 and 900 ng/L) in the clam Ruditapes philippinarum after exposure for 1, 3 and 7 days. The actual TMP concentrations were also measured in the experimental tanks. The total haemocyte count significantly increased in 7 day-exposed clams, whereas alterations in haemocyte volume were observed after 1 and 3 days of exposure. Haemocyte proliferation was increased significantly in animals exposed for 1 and 7 days, whereas haemocyte lysate lysozyme activity decreased significantly after 1 and 3 days. In addition, TMP significantly increased haemolymph lactate dehydrogenase activity after 3 and 7 days. Regarding antioxidant enzymes, only a significant time-dependent effect on CAT activity was recorded. This study demonstrated that environmentally realistic concentrations of TMP affect haemocyte parameters in clams, suggesting that haemocytes are a useful cellular model for the assessment of the impact of TMP on bivalves.
显示更多 [+] 显示较少 [-]Biological effects of decabromodiphenyl ether (BDE209) and Pb on earthworm (Eisenia fetida) in a soil system 全文
2015
Li, Jing | Zhang, Wei | Chen, Lin | Liang, Jun | Lin, Kuangfei
BDE209 and Pb are ubiquitous contaminants at e-waste recycling sites (EWRSs). This study aimed to determine acute and sub-acute toxicity to earthworm Eisenia fetida induced by BDE209 and Pb in natural soil. Results demonstrated that the inhibition of Pb on growth and reproduction of earthworms followed a dose-dependent pattern. Earthworms exposed to 100 mg kg−1 of BDE209 displayed avoidance responses, while the soil indicated a more obvious decline of habitat function with the increase of Pb level. Comet assay suggested that increasing concentrations of Pb exposure resulted in a gradual increase in the tail length and olive tail moment, which meant that the degree of DNA damage was promoted. BDE209 addition could reduce the damage; therefore the joint effects of both chemicals showed antagonistic. These results revealed that joint exposure (BDE209-Pb) could elicit pronounced biochemical and physiological responses in earthworms, and the DNA damage might be potential molecular biomarker of the two pollutants.
显示更多 [+] 显示较少 [-]