خيارات البحث
النتائج 1071 - 1080 من 4,044
Growth effects of shading and sedimentation in two tropical seagrass species: Implications for port management and impact assessment النص الكامل
2016
Benham, Claudia F. | Beavis, Sara G. | Hendry, Rebecca A. | Jackson, Emma L.
Seagrass meadows in many parts of the globe are threatened by a range of processes including port development, dredging and land clearing in coastal catchments, which can reduce water clarity and increase sedimentation pressure. As rates of seagrass loss increase, there is an urgent need to understand the potential impacts of development on these critical species. This research compares the effects of shading and burial by fine sand on two seagrass species Zostera muelleri and Halophila ovalis in Port Curtis Bay, an industrial harbour located on the continental margin adjacent to the Great Barrier Reef Heritage Area, Australia. The research finds that shading in combination with burial causes a significant decline in growth rates in both species, but that burial ≥10mm reduces growth rates to a greater extent than shading. The paper concludes by discussing the implications of these findings for port management and impact assessment.
اظهر المزيد [+] اقل [-]Enhanced biodegradation of pyrene and indeno(1,2,3-cd)pyrene using bacteria immobilized in cinder beads in estuarine wetlands النص الكامل
2016
Huang, Ru-ying | Tian, Wei-jun | Liu, Qing | Yu, Hui-bo | Jin, Xin | Zhao, Yang-guo | Zhou, Yu-hang | Feng, Gong
Two strains (Pseudomonas taiwanensis PYR1 and Acinetobacter baumannii INP1) were isolated from PAH-contaminated Liaohe estuarine wetland using enrichment. The cells of PYR1 and INP1 were immobilized in cinder beads for pyrene and indeno(1,2,3-cd)pyrene biodegradation in wetland. Biodegradation of pyrene and indeno(1,2,3-cd)pyrene in soils from wetland was carried out in pots using free cells as well as those immobilized in cinder beads to ascertain the role of bioaugmentation. Supported by the cinder beads, the immobilized cells degraded 70.7% and 80.9% of pyrene and indeno(1,2,3-cd)pyrene respectively after 30days. While the free cells degraded only 58.2% and 55.3%. Additionally, microbial analysis with high-throughput sequencing revealed the changes of microbial communities in soil without and with cinder beads immobilized with strains. The result indicated that Gammaproteobacteria were dominant PAH-degrading groups during bioaugmentation. This effective approach can be used to treat other PAH-contaminated wetlands by immobilizing different species of bacteria in cinder beads.
اظهر المزيد [+] اقل [-]Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia النص الكامل
2016
van der Wulp, Simon A. | Damar, Ario | Ladwig, Norbert | Hesse, Karl-J.
The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377m3s−1 entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174tons and 14 to 60tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics.
اظهر المزيد [+] اقل [-]Evaluation of anthropogenic contamination using sterol markers in a tropical estuarine system of northeast Brazil النص الكامل
2016
Frena, Morgana | Souza, Michel R.R. | Damasceno, Flaviana C. | Madureira, Luiz A.S. | Alexandre, Marcelo R.
The São Francisco River estuarine system, located in the Northeast coast of Brazil, has great economic, tourist and social importance. Its waters are used for activities such as agriculture, aquaculture, navigation and fishery, which supplies the surrounding communities. In this study, sterols markers were determined in twenty-eight sediment samples from São Francisco River estuary by gas chromatography - mass spectrometry (GC–MS). Sterol analysis was useful to distinguish between anthropogenic and biogenic organic matter (OM) sources in the studied area. Six sterols were quantified, suggesting different sources. Concentrations of fecal sterol (coprostanol) were lower than 500ngg−1, suggesting no indicative of severe sewage contamination.However, two stations showed concentrations around 100ngg−1 and the values for the coprostanol/(coprostanol+cholestanol) and coprostanol/cholesterol ratios indicates sewage contamination. The results in this study may be considered as baseline concentrations to be used as future reference for monitoring programs to prevent anthropogenic impacts.
اظهر المزيد [+] اقل [-]The exposure of pedestrians, drivers and road transport passengers to nitrogen dioxide النص الكامل
2016
Żak, Magdalena | Melaniuk-Wolny, Edyta | Widziewicz, Kamila
People travelling by road transport are exposed to high levels of nitrogen oxides (NOx), that are considered to be one of the primary pollutants from motor vehicles. This study examines the exposure of drivers, passengers and pedestrians to NO2 during different trip scenarios: travelling by private or public means of transport, along the major commuter routes in one of the biggest Polish agglomerations - Silesia Agglomeration, and other important communication routes in Poland, as well as during walks in both city centers and residential areas. The NO2 samples were collected in cars, trucks and buses interiors, as well as in the ambient air by passive samplers and next NO2 concentrations were analyzed by means of the spectrophotometric technique. The obtained results indicate that travelling by cars through city centers is associated with the exposure to NO2 concentrations of about 15% higher than in the case of travelling suburban routes; 33% greater than travelling by bus in urban traffic; more than app. 60% higher than in the case of travelling by bus in suburban traffic or by foot in city centers and up to 80% higher than moving on foot near little-used roads. The exposure profile of six groups of road users exposed to NO2 was therefore determined in this study. The obtained results could be used by policy makers to minimize the exposure to transportation-related pollutants concentrations and for planning far-reaching changes in the field of urban road transport.
اظهر المزيد [+] اقل [-]Bioremediation of waste under ocean acidification: Reviewing the role of Mytilus edulis النص الكامل
2016
Broszeit, Stefanie | Hattam, Caroline | Beaumont, Nicola
Waste bioremediation is a key regulating ecosystem service, removing wastes from ecosystems through storage, burial and recycling. The bivalve Mytilus edulis is an important contributor to this service, and is used in managing eutrophic waters. Studies show that they are affected by changes in pH due to ocean acidification, reducing their growth. This is forecasted to lead to reductions in M. edulis biomass of up to 50% by 2100. Growth reduction will negatively affect the filtering capacity of each individual, potentially leading to a decrease in bioremediation of waste. This paper critically reviews the current state of knowledge of bioremediation of waste carried out by M. edulis, and the current knowledge of the resultant effect of ocean acidification on this key service. We show that the effects of ocean acidification on waste bioremediation could be a major issue and pave the way for empirical studies of the topic.
اظهر المزيد [+] اقل [-]Waste production and regional growth of marine activities an econometric model النص الكامل
2016
Bramati, Maria Caterina
Coastal regions are characterized by intense human activity and climatic pressures, often intensified by competing interests in the use of marine waters. To assess the effect of public spending on the regional economy, an econometric model is here proposed. Not only are the regional investment and the climatic risks included in the model, but also variables related to the anthropogenic pressure, such as population, economic activities and waste production. Feedback effects of economic and demographic expansion on the pollution of coastal areas are also considered. It is found that dangerous waste increases with growing shipping and transportation activities and with growing population density in non-touristic coastal areas. On the other hand, the amount of non-dangerous wastes increases with marine mining, defense and offshore energy production activities. However, lower waste production occurs in areas where aquaculture and touristic industry are more exploited, and accompanied by increasing regional investment in waste disposal.
اظهر المزيد [+] اقل [-]Spatial variations in annual cycles of body-size spectra of planktonic ciliates and their environmental drivers in marine ecosystems النص الكامل
2016
Xu, Henglong | Jiang, Yong | Xu, Guangjian
Body-size spectra has proved to be a useful taxon-free resolution to summarize a community structure for bioassessment. The spatial variations in annual cycles of body-size spectra of planktonic ciliates and their environmental drivers were studied based on an annual dataset. Samples were biweekly collected at five stations in a bay of the Yellow Sea, northern China during a 1-year cycle. Based on a multivariate approach, the second-stage analysis, it was shown that the annual cycles of the body-size spectra were significantly different among five sampling stations. Correlation analysis demonstrated that the spatial variations in the body-size spectra were significantly related to changes of environmental conditions, especially dissolved nitrogen, alone or in combination with salinity and dissolve oxygen. Based on results, it is suggested that the nutrients may be the environmental drivers to shape the spatial variations in annual cycles of planktonic ciliates in terms of body-size spectra in marine ecosystems.
اظهر المزيد [+] اقل [-]Effects of the urban environmental conditions on the physiology of lichen and moss النص الكامل
2016
Sujetovienė, Gintarė | Galinytė, Vilma
The lichen Evernia prunastri (L.) Ach. and the moss Ptilium crista-castrensis (Hedw.) DeNot were exposed in three different urban sites along with the different pollution loads in order to evaluate the environmental quality. Physiological changes after the exposition were assessed by evaluating the content of photosynthetic pigments, chlorophyll fluorescence, membrane lipid peroxidation and integrity of cell membranes. The differences in response of fluorescence, chlorophylls contents and injuries of cell membranes were observed between the two species and between the sites. E. prunastri showed a great capacity to sustain the photosynthesis processes in the urban environment, while this capacity was very low in the transplanted moss P. crista-castrensis. The levels of malondialdehyde (MDA) indicated a significantly higher oxidative stress in the transplants at urban and residential sites. The integrity of cell membranes in moss samples was also more damaged than in lichen.
اظهر المزيد [+] اقل [-]Historical economic and environmental policies influencing trace metal inputs in Montevideo Bay, Río de la Plata النص الكامل
2016
Bueno, C. | Brugnoli, E. | Figueira, R.C.L. | Muniz, P. | Ferreira, P.A.L. | García Rodríguez, F.
Montevideo Bay is located in the middle zone of the Rio de la Plata, and since the foundation of the city, several key economic and environmental policies affected the industry, and thus, metal inputs into this ecosystem. The aim of this study is to evaluate the sedimentary geochemical record of Montevideo Bay, in order to determine the historical inputs of anthropogenic metals to the system. In addition, environmental and economic policies of the country were taken into account to infer the relationship between them and the historic metal input. Concentrations of aluminum, chromium, copper, lead, scandium and zinc were analyzed and the EF and SPI indices were calculated. The analysis showed that since Montevideo foundation, metal concentrations increased in accordance with industry development, and the indices as well as the metal concentration represent a reliable footprint of the history of different economic and environmental policies influencing historical industrial activities.
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