细化搜索
结果 721-730 的 4,029
The fate of phosphorus in sediments after the full operation of the Three Gorges Reservoir, China
2016
Wu, Yanhong | Wang, Xiaoxiao | Zhou, Jun | Bing, Haijian | Sun, Hongyang | Wang, Jipeng
The hydro-dynamic conditions have been changed after the impoundment of Three Gorges Reservoir (TGR), which result in changes of phosphorus (P) distribution in sediments. To investigate the variation and storage of P in the surface sediments of the TGR, continuously and intermittently submerged sediment samples were collected from 14 sites in 2014, and P fractions were analyzed using a modified Hedley sequential extraction method. The results showed that the concentrations of total P (TP) (904 ± 105 mg/kg) in the sediments did not exhibit an apparent spatial trend. A decreasing trend of bioavailable P (Bio-P) concentration in the continuously submerged sediment (177 ± 29 mg/kg) was observed from Fuling to Zigui, while an opposite trend appeared in the intermittently submerged sediment (139 ± 49 mg/kg) from Jiangjin to Zigui. The water depth and sediment grain size had important implications for the variation of the Bio-P in the sediments along the TGR. After the full operation of the TGR, the concentration of TP in the intermittently submerged sediment from Fengjie to Zigui was significantly higher in 2014 compared with that in 2009. The continuously submerged sediment is a major P pool of the TGR with an annual Bio-P deposition flux of 2.14 × 104 t/a, of which 87% was retained in the reaches from Fuling to Zigui. Considering the slow release of P from the sediment (0.16–2.75 t/a), the sediment has been a P “sink” since the full operation of the TGR in 2010.
显示更多 [+] 显示较少 [-]Semen phthalate metabolites, semen quality parameters and serum reproductive hormones: A cross-sectional study in China
2016
Wang, Yi-Xin | Zeng, Qiang | Sun, Yang | Yang, Pan | Wang, Peng | Li, Jin | Huang, Zhen | You, Ling | Huang, Yue-Hui | Wang, Cheng | Li, Yu-Feng | Lu, Wen-Qing
Exposure to phthalates has been found to have adverse effects on male reproductive function in animals. However, the findings from human studies are inconsistent. Here we examined the associations of phthalate exposure with semen quality and reproductive hormones in a Chinese population using phthalate metabolite concentrations measured in semen as biomarkers. Semen (n = 687) and blood samples (n = 342) were collected from the male partners of sub-fertile couples who presented to the Reproductive Center of Tongji Hospital in Wuhan, China. Semen quality parameters and serum reproductive hormone levels were determined. Semen concentrations of 8 phthalate metabolites were assessed using high-performance liquid chromatography and tandem mass spectrometry. Associations of the semen phthalate metabolites with semen quality parameters and serum reproductive hormones were assessed using confounder-adjusted linear and logistic regression models. Semen phthalate metabolites were significantly associated with decreases in semen volume [mono-n-butyl phthalate (MBP), mono-(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP)], sperm curvilinear velocity [monobenzyl phthalate (MBzP), MEHP, the percentage of di-(2-ethylhexyl)-phthalate metabolites excreted as MEHP (%MEHP)], and straight-line velocity (MBzP, MEHP, %MEHP), and also associated with an increased percentage of abnormal heads and tails (MBzP) (all p for trend <0.05). These associations remained suggestive or significant after adjustment for multiple testing. There were no significant associations between semen phthalate metabolites and serum reproductive hormones. Our findings suggest that environmental exposure to phthalates may impair human semen quality.
显示更多 [+] 显示较少 [-]Ecotoxicity and genotoxicity of cadmium in different marine trophic levels
2016
Pavlaki, Maria D. | Araújo, Mário J. | Cardoso, Diogo N. | Silva, Ana Rita R. | Cruz, Andréia | Mendo, Sónia | Soares, Amadeu M.V.M. | Calado, Ricardo | Loureiro, Susana
Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems – the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggs < P. varians post-larvae < P. varians zoea I < S. senegalensis larvae < A. tonsa eggs < A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.
显示更多 [+] 显示较少 [-]Estimation of anthropogenic heat emissions in urban Taiwan and their spatial patterns
2016
Koralegedara, Suranjith Bandara | Lin, Chuan-Yao | Sheng, Yang-Fan | Kuo, Ching-Huei
High energy consumption in the urban environment impacts the urban surface energy budget and causes the emission of anthropogenic heat fluxes (AHFs) into the atmosphere. AHFs vary over time and space. Thus, a reliable estimation of AHF is needed for mesoscale meteorological modeling. This study used a statistical regression method to estimate the annual mean gridded AHF with high spatial (1-km) resolution. Compared with current methods for AHF estimation, the statistical regression method is straightforward and can be easily incorporated with meteorological modeling. AHF of the highly populated urban areas in Taiwan were estimated using data from the anthropogenic pollutant emission inventory of CO and NOx for year 2010. Over 40% of the total AHF values in Taiwan main island fell within the range of 10–40 Wm−2. When the study domain was confined to urban land, the percentage contributions from AHF values were increased, with over 68% of the total AHF values within the range of 10–40 Wm−2. AHF values > 40 Wm−2 were more abundant in the Southern region, followed by the Central and Northern regions. An assessment of the heat emissions by the large scale urban consumption of energy (LUCY) model revealed that the mean AHFs are reasonably close to those produced while the maximum AHFs are underestimated. The results obtained evidence the impact of spatial distribution of land use types, particularly population densities, main highways and industries on AHF generation in Taiwan.
显示更多 [+] 显示较少 [-]Novel speciation method based on Diffusive Gradients in Thin Films for in situ measurement of uranium in the vicinity of the former uranium mining sites
2016
Drozdzak, Jagoda | Leermakers, Martine | Gao, Yue | Phrommavanh, Vannapha | Descostes, Michael
The Diffusive Gradients in Thin Films (DGT) technique using PIWBA resin (The Dow Chemical Company) was developed and validated for the measurement of uranium (U) concentration in natural and uranium mining influenced waters. The U uptake on the PIWBA resin gel was 97.3 ± 0.4% (batch method; Vsol = 5 mL; [U] = 20 μg L−1; 0.01 M NaNO3; pH = 7.0 ± 0.2). The optimal eluent was found to be HNO3conc/70 °C with an elution efficiency of 88.9 ± 1.4%. The laboratory DGT investigation demonstrated that the PIWBA resin gel exhibits a very good performance across a wide range of pH (3–9) and ionic strength (0.001–0.7 M NaNO3) at different time intervals. Neither effect of PO43− (up to 1.72 × 10−4 M), nor of HCO3− (up to 8.20 × 10−3 M) on the quantitative measurement of uranium by DGT-PIWBA method were observed. Only at very high Ca2+ (2.66 × 10−4 M), and SO42− (5.55 × 10−4 M) concentration, the U uptake on DGT-PIWBA was appreciably lessened. In-situ DGT field evaluation was carried out in the vicinity of three former uranium mining sites in France (Loire-Atlantique and Herault departments), which employ different water treatment technologies and have different natural geochemical characteristics. There was a similar or inferior U uptake on DGT-Chelex®-100 in comparison with the U accumulation on a DGT-PIWBA sampler. Most likely, the performance of Chelex®-100 was negatively affected by a highly complex matrix of mining waters. The high concentration and identity of co-accumulating analytes, typical for the mining environment, did not have a substantial impact on the quantitative uptake of labile U species on DGT- PIWBA.The use of the polyphenol impregnated anion exchange resin leads to a significant advancement in the application and development of the DGT technique for determination of U in the vicinity of the former uranium mining sites.
显示更多 [+] 显示较少 [-]Occurrence, distribution and seasonal variation of organophosphate flame retardants and plasticizers in urban surface water in Beijing, China
2016
Shi, Yali | Gao, Lihong | Li, Wenhui | Wang, Yuan | Liu, Jiemin | Cai, Yaqi
The occurrence, spatial distribution and seasonal variation of 14 organophosphate esters (OPEs) were investigated in urban surface water (river and lake water) from July 2013 to June 2014 in Beijing, China. Sewage influent and effluent samples, as well as rainwater and road runoff samples were also analyzed as the potential sources of OPEs in surface water. Tris(2-chloro-1-methylethyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) were the most abundant OPEs with the average concentrations of 291 ng L⁻¹ and 219 ng L⁻¹, respectively. Relatively high concentrations of OPEs were detected in rivers located at southern and eastern urban of Beijing, which was probably attributed to the treated and untreated sewage discharge. Besides, higher levels of OPEs were observed in urban surface water in the summer, and the wet deposition (rainfall) was confirmed to be an important factor for this observation. Risk assessment showed low or medium risk of OPEs for the organisms (algae, crustacean and fish).
显示更多 [+] 显示较少 [-]Plant community and litter composition in temperate deciduous woodlots along two field gradients of soil Ni, Cu and Co concentrations
2016
Hale, Beverley | Robertson, Paul
Perennial plant communities in the proximity of metal smelters and refineries may receive substantial inputs of base metal particulate as well as sulphate from the co-emission of sulphur dioxide. The Ni refinery at Port Colborne (Canada) operated by Inco (now Vale Canada Ltd.) emitted Ni, Co and Cu, along with sulphur dioxide, between 1918 and 1984. The objectives were to determine if vascular plant community composition, including standing litter, in twenty-one woodlots on clay or organic soil, were related to soil Ni concentration which decreased in concentration with distance from the Ni refinery. The soil Ni concentration in the clay woodlots ranged from 16 to 4130 mg Ni/kg, and in the organic woodlots, ranged from 98 to 22,700 mg Ni/kg. The concentrations of Co and Cu in the soils were also elevated, and highly correlated with soil Ni concentration. In consequence, each series of woodlots constituted a ‘fixed ratio ray’ of metal mixture exposure. For each of the woodlots, there were 16 independent measurements of ‘woodlot status’ which were correlated with elevated soil Ni concentration. Of the 32 combinations, there were eight linear correlations with soil Ni concentration, considerably more than would be expected by chance alone at a p-value of 0.05. With the exception of mean crown rating for shrubs at the clay sites, the correlations were consistent with the hypothesis that increased soil metal concentrations would be correlated with decreased diversity, plant community health or fitness, and increased accumulation of litter. Only five of the eight linear correlations were from the organic woodlots, suggesting that the observations were not confounded with soil type nor range in soil metal concentrations.
显示更多 [+] 显示较少 [-]Influence of different types of coals and stoves on the emissions of parent and oxygenated PAHs from residential coal combustion in China
2016
Wang, Yan | Xu, Yue | Chen, Yingjun | Tian, Chongguo | Feng, Yanli | Chen, Tian | Li, Jun | Zhang, Gan
To evaluate the influence of coal property and stove efficiency on the emissions of parent polycyclic aromatic hydrocarbons (pPAHs) and oxygenated PAHs (oPAHs) during the combustion, fifteen coal/stove combinations were tested in this study, including five coals of different geological maturities in briquette and chunk forms burned in two residential stoves. The emission factors (EFs) of pPAHs and oPAHs were in the range of 0.129–16.7 mg/kg and 0.059–0.882 mg/kg, respectively. The geological maturity of coal significantly affected the emissions of pPAHs and oPAHs with the lower maturity coals yielding the higher emissions. The chunk-to-briquette transformation of coal dramatically increased the emissions of pPAHs and oPAHs during the combustion of anthracite, whereas this transformation only elevated the emissions of high molecular weight PAHs for bituminous coals. The influence of stove type on the emissions of pPAHs and oPAHs was also geological-maturity-dependent. High efficiency stove significantly reduced the emissions of PAHs from those relatively high-maturity coals, but its influences on low-maturity coals were inconstant.
显示更多 [+] 显示较少 [-]Mercury dilution by autochthonous organic matter in a fertilized mangrove wetland
2016
Machado, Wilson | Sanders, Christian J. | Santos, Isaac R. | Sanders, Luciana M. | Silva-Filho, Emmanoel V. | Luiz-Silva, Wanilson
A dated sediment core from a highly-fertilized mangrove wetland located in Cubatão (SE Brazil) presented a negative correlation between mercury (Hg) and organic carbon contents. This is an unusual result for a metal with well-known affinity to organic matter. A dilution of Hg concentrations by autochthonous organic matter explained this observation, as revealed by carbon stable isotopes signatures (δ13C). Mercury dilution by the predominant mangrove-derived organic matter counterbalanced the positive influences of algal-derived organic matter and clay contents on Hg levels, suggesting that deleterious effects of Hg may be attenuated. Considering the current paradigm on the positive effect of organic matter on Hg concentrations in coastal sediments and the expected increase in mangrove organic matter burial due to natural and anthropogenic stimulations of primary production, predictions on the influences of organic matter on Hg accumulation in mangrove wetlands deserve caution.
显示更多 [+] 显示较少 [-]Tracking the conversion of nitrogen during pyrolysis of antibiotic mycelial fermentation residues using XPS and TG-FTIR-MS technology
2016
Zhu, Xiangdong | Yang, Shijun | Wang, Liang | Liu, Yuchen | Qian, Feng | Yao, Wenqing | Zhang, Shicheng | Chen, Jianmin
Antibiotic mycelial fermentation residues (AMFRs), which are emerging solid pollutants, have been recognized as hazardous waste in China since 2008. Nitrogen (N), which is an environmental sensitivity element, is largely retained in AMFR samples derived from fermentation substrates. Pyrolysis is a promising technology for the treatment of solid waste. However, the outcomes of N element during the pyrolysis of AMFRs are still unknown. In this study, the conversion of N element during the pyrolysis of AMFRs was tracked using XPS (X-ray photoelectron spectroscopy) and online TG-FTIR-MS (Thermogravimetry-Fourier transform infrared-Mass spectrometry) technology. In the AMFR sample, organic amine-N, pyrrolic-N, protein-N, pyridinic-N, was the main N-containing species. XPS results indicated that pyrrolic-N and pyridinic-N were retained in the AMFR-derived pyrolysis char. More stable species, such as N-oxide and quaternary-N, were also produced in the char. TG-FTIR-MS results indicated that NH3 and HCN were the main gaseous species, and their contents were closely related to the contents of amine-N and protein-N, and pyrrolic-N and pyridinic-N of AMFRs, respectively. Increases in heating rate enhanced the amounts of NH3 and HCN, but had less of an effect on the degradation degree of AMFRs. N-containing organic compounds, including amine-N, nitrile-N and heterocyclic-N, were discerned from the AMFR pyrolysis process. Their release range was extended with increasing of heating rate and carbon content of AMFR sample. This work will help to take appropriate measure to reduce secondary pollution from the treatment of AMFRs.
显示更多 [+] 显示较少 [-]