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结果 1711-1720 的 4,367
Bioaccumulation of heavy metals by shrimp (Litopenaeus schmitti): A dose–response approach for coastal resources management 全文
2017
Nascimento, Juliana Ribeiro | Sabadini-Santos, Elisamara | Carvalho, Cassia | Keunecke, Karina Annes | César, Ricardo | Bidone, Edison D.
We reveal a dose–response relationship for bioaccumulation of Zn, Cu and Cr in shrimp Litopenaeus schmitti from Sepetiba Bay, Rio de Janeiro, Brazil. Our model estimates the current risk (AD50 was 70% of the legal limit) and the daily metal uptake rate for each metal. It can also evaluate the relative reliability of predictions for tissue concentrations reaching the legal limits for human consumption (approximately 1year) and predictions related to asymptotic length, arising from (i) direct regression of the metal concentration (MeC) versus total length (TL) and age (duration of exposure), and (ii) correlation of the incorporation rate (IR=MeC/TL) with age. Metal incorporation rates (IR), i.e. a kinetic proxy for absorption during growth up to attainment of asymptotic length, decrease with age, reflecting a slow-down in metal absorption. This pattern mitigates the high initial concentrations observed for juveniles.
显示更多 [+] 显示较少 [-]ARIMA analysis of the effect of land surface coverage on PM10 concentrations in a high-altitude megacity 全文
2017
Zafra, Carlos | Ángel, Yenifer | Torres, Eliana
This paper uses ARIMA models for daily temporal analysis of the effect of land surface coverage (LSC) on PM10 concentrations in a high-altitude megacity. Bogota, the capital of Colombia, is the urban center with the greatest population density and third-highest air pollution levels in Latin America. Six automatic monitoring stations were used; they were equipped with measurement instruments for PM10, temperature and solar radiation as well as wind speed and wind direction. The duration of the sampling period was 6 years. The hourly PM10 sampling system included continuous-monitoring equipment that used beta ray attenuation. We analyzed atmospheric stability and the spatial distribution of LSC (vegetated, non-vegetated, impervious and water bodies) before applying the iterative process of Box-Jenkins for ARIMA models. ARIMA analysis indicates greater persistence in PM10 pollution in the presence of increased vegetated LSC (trees and grasslands); persistence decreased in the presence of more impervious LSC (roofs, pavements and footpaths). PM10 persistence is found to be 2 days (48 h). The best distance to demonstrate these findings is between 50 and 100 m, with respect to the monitoring stations' physical location. Urban areas with a predominance of vegetated LSC register lower PM10 concentrations than urban areas with a predominance of impervious LSC (average daily difference = 42.7%). This study's findings serve as a reference point for the development of differentiated strategies for air pollution control in line with urban LSC.
显示更多 [+] 显示较少 [-]Chemical monitoring of Swedish coastal waters indicates common exceedances of environmental thresholds, both for individual substances as well as their mixtures 全文
2017
Gustavsson, B Mikael | Magnér, Jörgen | Carney Almroth, Bethanie | Eriksson, Martin K. | Sturve, Joachim | Backhaus, Thomas
Chemical pollution was monitored and assessed along the Swedish west coast. 62 of 172 analyzed organic chemicals were detected in the water phase of at least one of five monitored sites. A Concentration Addition based screening-level risk assessment indicates that all sites are put at risk from chemical contamination, with total risk quotients between 2 and 9. Only at one site did none of the individual chemicals exceeded its corresponding environmental threshold (PNEC, EQS). The monitoring data thus demonstrate a widespread blanket of diffuse pollution, with no clear trends among sites. Further issues critical for the environmental chemical risk assessment include the challenges to achieve sufficiently low levels of detection, especially for hormones and cypermethrin (a pyrethroid insecticide), the appropriate consideration of non-detects and the limited availability of reliable PNECs and EQS values.
显示更多 [+] 显示较少 [-]Aerobic denitrification and biomineralization by a novel heterotrophic bacterium, Acinetobacter sp. H36 全文
2017
Su, Jun feng | Shi, Jing xin | Ma, Fang
A novel aerobic denitrification and biomineralization strain H36 was isolated from the Qu Jiang artificial lake. Based on phylogenetic characteristics, the isolated strain was identified as Acinetobacter species. Strain H36 was confirmed to have the ability to perform simultaneous denitrification and biomineralization. Results showed the strain H36 had the capability to completely reduce 96.29% of NO3−–N and 78.59% of Ca2+ over 112h under aerobic condition. Response surface methodology (RSM) analysis demonstrated the highest removal ratio of Ca2+ was 74.24% with hardness concentration of 350mg/L, pH of 8.5, organic concentration of 0.75g/L and inoculum size of 15%. The highest removal ratio of nitrate was 77.00% with hardness concentration of 350mg/L, pH of 7.5, organic concentration of 0.75g/L and inoculum size of 10%. Besides, X-ray diffraction (XRD) analysis showed calcium carbonate could be formed in the process of biomineralization.
显示更多 [+] 显示较少 [-]Quality index of the surface water of Amazonian rivers in industrial areas in Pará, Brazil 全文
2017
Medeiros, Adaelson Campelo | Faial, Kleber Raimundo Freitas | do Carmo Freitas Faial, Kelson | da Silva Lopes, Iris Danielly | de Oliveira Lima, Marcelo | Guimarães, Raphael Mendonça | Mendonça, Neyson Martins
In this study was to evaluate the waters quality of the Murucupi River, located in urban agglomerate area and intense industrial activity in Barcarena City, Pará State. The Arapiranga River in Abaetetuba City was used as control area (Background), next to Barcarena. Was used the Water Quality Index (WQI) based on nine variables analized. Waters quality of the Arapiranga and Murucupi rivers were regular to good and bad to good, respectively. Anthropogenic influence on the Murucupi River was higher, mainly by the disposal of domestic effluents from the urban agglomerate and of the industrial waste tailing basins upstream of this river. Due to its less inhabited environment and further away from the area urban and industrial, the Arapiranga River was more preserved. Waters pollution of around these area is increasingly intense, and restricted its uses for various purposes.
显示更多 [+] 显示较少 [-]Spatial and temporal analysis of the risks posed by total petroleum hydrocarbon and trace element contaminants in coastal waters of Kuwait 全文
2017
Nicolaus, E.E.M. | Wright, S.R. | Barry, J. | Bolam, T.P.C. | Ghareeb, K. | Ghaloom, M. | Al-Kanderi, N. | Harley, B.F.M. | Le Quesne, W.J.F. | Devlin, M.J. | Lyons, B.P.
Nine trace elements including As, Cd, Cu, Fe, Hg, Ni, Pb, V and Zn, and total petroleum hydrocarbons were analysed from water samples collected from 23 stations since 1984 from Kuwaiti coastal waters. Here it was investigated whether concentrations of these determinants are at levels above Kuwaiti and internationally established assessment criteria (AC). The results indicate that Cu and Cd had the most Kuwaiti AC breaches over time. Comparing the data of the last sampled year to the least stringent international AC, then Cu and Cd showed breaches at all stations. The trends for trace metals are significantly downwards, especially for Cd and Hg. No determinant measured showed a significant upward trend, indicating that water pollution for these contaminants is not a worsening situation. However, further sampling should be carried out to confirm these findings, especially at shoreline locations, where routine monitoring ceased in 2011 to investigate any recent changes.
显示更多 [+] 显示较少 [-]Size and dynamics of microplastic in gastrointestinal tracts of Northern Fulmars (Fulmarus glacialis) and Sooty Shearwaters (Ardenna grisea) 全文
2017
Terepocki, Alicia K. | Brush, Alex T. | Kleine, Lydia U. | Shugart, Gary W. | Hodum, Peter
We found microplastic in 89.5% of 143 Northern Fulmars from 2008 to 2013 and 64% of 25 Sooty Shearwaters in 2011–2012 that were found dead or stranded on Oregon and Washington beaches. Average plastic loads were 19.5 pieces and 0.461g for fulmars and 13.3 pieces and 0.335g for shearwaters. Pre-manufactured plastic pellets accounted for 8.5% of fulmar and 33% of shearwater plastic pieces. In both species, plastic in proventriculi averaged 2–3mm larger in greatest dimension than in ventriculi. Intestinal plastic in fulmars averaged 1mm less in greatest dimension than ventricular plastic. There was no significant reduction in pieces or mass of plastic in 33 fulmars held for a median of seven days in a plastic-free environment. Three fulmars that survived to be released from rehabilitation regurgitated plastic, which provided an alternative outlet for elimination of plastic and requires reassessment of the dynamics of plastic in seabird gastrointestinal tracts.
显示更多 [+] 显示较少 [-]Temporal variations in physiological responses of Kandelia obovata seedlings exposed to multiple heavy metals 全文
2017
Cheng, Shanshan | Tam, Nora Fung Yee | Li, Ruili | Shen, Xiaoxue | Niu, Zhiyuan | Chai, Minwei | Qiu, Guo Yu
A study was conducted to quantify temporal variations in physiological responses of Kandelia obovata under multiple heavy metal stress. The results showed that plant growth was not significantly affected by multiple heavy metal stress during the 120-days experiment. At the start, levels of net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) showed effects of “low-promotion, high-inhibition”, but Pn and Gs reduced with increasing heavy metal stress at the end. Temporary lipid oxidation was shown by high levels of malondialdehyde (MDA) under high heavy metal stress at the start but was unaffected at the end of the experiment. MDA negatively correlated with biomass and photosynthetic parameters and acted as a sensitive indicator. Proline also shared similar trend and indicated its temporary role in osmotic adjustment. Negative correlations between osmotic adjustment matter and photosynthetic parameters further confirmed the significant role of osmotic adjustment under heavy metal stress.
显示更多 [+] 显示较少 [-]Relative sensitivity of Arctic species to physically and chemically dispersed oil determined from three hydrocarbon measures of aquatic toxicity 全文
2017
Bejarano, Adriana C. | Gardiner, William W. | Barron, Mace G. | Word, Jack Q.
The risks to Arctic species from oil releases is a global concern, but their sensitivity to chemically dispersed oil has not been assessed using a curated and standardized dataset from spiked declining tests. Species sensitivity to dispersed oil was determined by their position within species sensitivity distributions (SSDs) using three measures of hydrocarbon toxicity: total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbon (PAHs), and naphthalenes. Comparisons of SSDs with Arctic/sub-Arctic versus non-Arctic species, and across SSDs of compositionally similar oils, showed that Arctic and non-Arctic species have comparable sensitivities even with the variability introduced by combining data across studies and oils. Regardless of hydrocarbon measure, hazard concentrations across SSDs were protective of sensitive Arctic species. While the sensitivities of Arctic species to oil exposures resemble those of commonly tested species, PAH-based toxicity data are needed for a greater species diversity including sensitive Arctic species.
显示更多 [+] 显示较少 [-]Adsorption of 17 α-ethyl estradiol with the competition of bisphenol A on the marine sediment of Hong Kong 全文
2017
Fei, Ying-heng | Leung, Kenneth M.Y. | Li, Xiao-yan
The present experimental study was to characterize the adsorption behavior of 17 α-ethyl estradiol (EE2) onto marine sediment in both the single and binary solute systems. Stepwise spiking was innovatively performed to better understand the competition effects. Adsorption of EE2 on the marine sediment can be well fitted by the Freundlich model with an affinity coefficient (KF) varying from 15.8 to 39.8L/kg. It was significantly influenced by SOM and the particle properties. Co-presence of BPA brought about a significant competition effect on the adsorption of EE2, leading to a reduced EE2 adsorption. The competitive effect imposed by EE2 to BPA, however, was even more serious owing probably to the large molecular structure and high hydrophobicity of EE2. The sediment sample with the highest SOM and SSA presented a mild competition effect, while the sediment with the lowest SOM and largest particle size exhibited the most serious competition effect.
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