خيارات البحث
النتائج 1081 - 1090 من 4,043
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.
اظهر المزيد [+] اقل [-]Reducing spatial variation in environmental assessment of marine benthic fauna النص الكامل
2016
Leonardsson, Kjell | Blomqvist, Mats | Rosenberg, Rutger
The Benthic Quality Index, BQI, is widely used for benthic quality assessment. Here, we investigated if spatial variation in the BQI can be reduced by accounting for the environmental factors instead of having different boundaries for different salinity regimes between status classes in the EU Water Framework Directive and Marine Strategy Framework Directive. For this purpose we tested salinity, sediment structure, and depth in a regression model to test their contribution to variations in BQI. The spatial variation in BQI was better explained by depth than by salinity or sediment structure. The proposed assessment method uses the residuals from the regression model between BQI and depth. With this method the variance in BQI between samples was reduced by 50% to 75% in the majority of situations. A method to establish the boundary between good and moderate status and how to derive EQR-values according to the WFD is presented.
اظهر المزيد [+] اقل [-]Contribution of fungal spores to organic carbon in ambient aerosols in Beijing, China النص الكامل
2016
Liang, Linlin | Engling, Guenter | Du, Zhenyu | Duan, Fengkui | Cheng, Yuan | Liu, Xuyan | He, Kebin
Fungal spores are ubiquitous components of atmospheric aerosols and contributors to the organic carbon (OC) component in ambient aerosols. In order to better understand the role of fungal spores and their impact on atmospheric processes, this study was conducted to investigate the contribution of fungal spores to OC at urban and rural sites in Beijing, China. Ambient concentrations of a molecular tracer for fungal spores, i.e., mannitol in PM10 and PM2.5 samples were measured at an urban site (Tsinghua University, THU) during an entire year, while the observations in PM10 at a rural site (Miyun, MY) were conducted during late spring and summer. Combined with the factor representing the average content of mannitol per spore (0.49 ± 0.20 pg) obtained at the same urban site in Beijing, the year-round number concentrations of fungal spores were obtained. Using a conversion factor of 13 pg C spore−1, the annual average concentrations of spore-OC in PM2.5 and PM10 at the THU site were observed at 0.3 ± 0.2 μgC m−3 and 0.8 ± 0.7 μgC m−3, while the respective contributions of spore-OC to total OC were 1.2 ± 0.7% and 3.5 ± 3.7%, respectively. The contributions of fungal spores to OC in the two size fractions had the following seasonal trend (from highest to the lowest levels): summer, autumn, winter and spring. During the summer sampling season, the contribution of fungal spores to OC was observed at a higher level at the rural site (14.1 ± 10.5%), compared to the urban site (7.3 ± 3.3%). It can be concluded that fungi are a non-negligible source of carbonaceous aerosol even at urban locations such as Beijing, China. Thus, more studies are needed to better understand the spatial, temporal and size distributions of fungal OC contributions to atmospheric aerosols in populated areas.
اظهر المزيد [+] اقل [-]The value of offshore field experiments in oil spill technology development for Norwegian waters النص الكامل
2016
Faksness, Liv-Guri | Brandvik, Per Johan | Daling, Per S. | Singsaas, Ivar | Sørstrøm, Stein Erik
The blowout on the Ekofisk field in the North Sea in 1977 initiated R&D efforts in Norway focusing on improving oil spill contingency in general and more specifically on weathering processes and modeling drift and spreading of oil spills. Since 1978, approximately 40 experimental oil spills have been performed under controlled conditions in open and ice covered waters in Norway. The importance of these experimental oil spills for understanding oil spill behavior, development of oil spill and response models, and response technologies are discussed here. The large progress within oil spill R&D in Norway since the Ekofisk blowout has been possible through a combination of laboratory testing, basin studies, and experimental oil spills. However, it is the authors' recommendation that experimental oil spills still play an important role as a final validation for the extensive R&D presently going on in Norway, e.g. deep-water releases of oil and gas.
اظهر المزيد [+] اقل [-]Determination of the concentrations of alternative antifouling agents on the Korean coast النص الكامل
2016
Lee, Seongeon | Lee, Yong-Woo
Since the ban on tributyltin (TBT) in 2008, dozens of alternative antifouling agents have been used instead. Unfortunately, these alternative antifouling agents contain diverse toxic components, which have contaminated the coasts. From 2006 to 2013, the concentration of chlorothalonil, dichlofluanid, and Irgarol 1051 were monitored continuously, and their mean concentrations increased due to the increase in maritime cargo and consequent increase in the incoming and outgoing ships in harbors. An analysis of the sampling points according to harbor type showed that the contamination was more severe in fishing and big harbors, where there are more incoming and outgoing ships. A correlation analysis indicated a high correlation between chlorothalonil and dichlofluanid. Unlike Irgarol 1051, which is only used as an antifouling agent, the other two substances are used as agricultural chemicals as well, which could explain the high correlation. This study suggests that these alternative antifouling agents should be tracked continuously.
اظهر المزيد [+] اقل [-]Inferring sources of polycyclic aromatic hydrocarbons (PAHs) in sediments from the western Taiwan Strait through end-member mixing analysis النص الكامل
2016
Li, Tao | Sun, Guihua | Ma, Shengzhong | Liang, Kai | Yang, Chupeng | Li, Bo | Luo, Weidong
Concentration, spatial distribution, composition and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated based on measurements of 16 PAH compounds in surface sediments of the western Taiwan Strait. Total PAH concentrations ranged from 2.41 to 218.54ngg−1. Cluster analysis identified three site clusters representing the northern, central and southern regions. Sedimentary PAHs mainly originated from a mixture of pyrolytic and petrogenic in the north, from pyrolytic in the central, and from petrogenic in the south. An end-member mixing model was performed using PAH compound data to estimate mixing proportions for unknown end-members (i.e., extreme-value sample points) proposed by principal component analysis (PCA). The results showed that the analyzed samples can be expressed as mixtures of three end-members, and the mixing of different end-members was strongly related to the transport pathway controlled by two currents, which alternately prevail in the Taiwan Strait during different seasons.
اظهر المزيد [+] اقل [-]A reduced form model for ozone based on two decades of CMAQ simulations for the continental United States النص الكامل
2016
Porter, P Steven | Rao, S.T. | Hogrefe, Christian | Mathur, Rohit
A Reduced Form Model (RFM) is a mathematical relationship between the inputs and outputs of an air quality model, permitting estimation of additional modeling without costly new regional-scale simulations. A 21-year Community Multiscale Air Quality (CMAQ) simulation for the continental United States provided the basis for the RFM developed in this study. Predictors included the principal component scores (PCS) of emissions and meteorological variables, while the predictand was the monthly mean of daily maximum 8-h CMAQ ozone for the ozone season at each model grid. The PCS form an orthogonal basis for RFM inputs. A few PCS incorporate most of the variability of emissions and meteorology, thereby reducing the dimensionality of the source-receptor problem. Stochastic kriging was used to estimate the model.The RFM was used to separate the effects of emissions and meteorology on ozone concentrations. By running the RFM with emissions constant (ozone dependent on meteorology), or constant meteorology (ozone dependent on emissions). Years with ozone-conducive meteorology were identified, and meteorological variables best explaining meteorology-dependent ozone were identified. Meteorology accounted for 19%–55% of ozone variability in the eastern US, and 39%–92% in the western US. Temporal trends estimated for original CMAQ ozone data and emission-dependent ozone were mostly negative, but the confidence intervals for emission-dependent ozone are much narrower. Emission-driven changes in monthly mean ozone levels for the period 2000–2010 ranged from 6.4 to 10.9 ppb for the eastern US and from 1.4 to 2.5 ppb for the western US.
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