细化搜索
结果 981-990 的 3,991
Distribution variation of heavy metals in maricultural sediments and their enrichment, ecological risk and possible source—A case study from Zhelin bay in Southern China
2016
Wang, Yi | Wei, Yaning | Guo, Pengran | Pan, Jiachuan | Wu, Qihang | Liu, Ning
The study characterized the enrichment, ecological risk and possible source of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in sediments from a typical mariculture bay. The concentrations of the metals were analyzed in sediments collected from Zhelin bay. The distribution variation was examined during the past decade, which had an increase tendency till 2011. The enrichment factor and geoaccumulation indices suggested Pb, As, Cu and Zn were minor enrichment and unpolluted to moderately polluted, and Ni at cage mariculture area was moderately-severe enrichment and strongly polluted. This area had medium to high ecological risk, especially at the northwest coastal area of semi-closed bay, with high-medium to high ecological risk. Correlation and principal component analyses indicated that most of heavy metals, especially for As, Pb and Ni, primarily resulted from the combustion of gasoline and diesel fuel and the ship protective layer.
显示更多 [+] 显示较少 [-]Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia
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.
显示更多 [+] 显示较少 [-]Evaluation of anthropogenic contamination using sterol markers in a tropical estuarine system of northeast Brazil
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.
显示更多 [+] 显示较少 [-]The effects of urbanization and household-related factors on residential direct CO2 emissions in Shanxi, China from 1995 to 2014: A decomposition analysis
2016
Zang, Xueling | Zhao, Tao | Wang, Juan | Guo, Fang.
Multiple household-related driving factors of residential direct carbon emissions (RDCE) in China at regional level have not yet been sufficiently addressed or quantified. In this paper, a logarithmic mean Divisia index (LMDI) decomposition analysis was employed to examine the factors (e.g., the number of households, per capita household income, household size, urbanization, energy intensity, energy structure and emission coefficient) impacting the changes in RDCE in Shanxi province of China from 1995 to 2014. The results showed that the increase in RDCE mainly attributed to the growing per capita household income and the increasing number of households. Additionally, the expansion of urbanization also contributed marginally to the increase in emissions. However, the shrinking household size was a main inhibitory factor and the decline in energy intensity was also responsible for the diminishing emissions. Based on the results, four emission reduction measures and strategies were identified: (i) using market economic mechanism to regulate household consumption behaviors towards environment protection and low carbon development, as well as encouraging the use of energy-efficiency domestic appliances and less energy-intensive lifestyles; (ii) setting strict divorce processes to lower divorce rates and encouraging people to live with their children and parents; (iii) realizing green transformation development of urbanization; (iv) promoting a shift to renewable and clean energy in people's daily life and power generation, e.g., wind, solar, hydro, nuclear and biogas.
显示更多 [+] 显示较少 [-]Waste production and regional growth of marine activities an econometric model
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.
显示更多 [+] 显示较少 [-]Spatial variations in annual cycles of body-size spectra of planktonic ciliates and their environmental drivers in marine ecosystems
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.
显示更多 [+] 显示较少 [-]Dry bulk cargo shipping — An overlooked threat to the marine environment?
2016
Grote, Matthias | Mazurek, Nicole | Gräbsch, Carolin | Zeilinger, Jana | Le Floch, Stéphane | Wahrendorf, Dierk-Steffen | Höfer, Thomas
Approximately 9.5billiontonnes of goods is transported over the world oceans annually with dry bulk representing the largest cargo group. This paper aims to analyse whether the transport and associated inputs of dry bulks into the sea create a risk for the marine environment. For this purpose, we analyse the international regulatory background concerning environmental protection (MARPOL), estimate quantities and identify inputs of such cargoes into the oceans (accidental and operational), and use available information for hazard assessment. Annually, more than 2.15milliontonnes of dry bulk cargoes are likely to enter the oceans, of which 100,000tonnes are potentially harmful to the marine environment according to the definition included in draft maritime regulation. The assessment of the threat to the marine environment is hampered by a lack of available information on chemical composition, bioavailability and toxicity. Perspectives for amendments of the unsatisfying pollution prevention regulations are discussed.
显示更多 [+] 显示较少 [-]Effects of sediment amended with Deepwater Horizon incident slick oil on the infaunal amphipod Leptocheirus plumulosus
2016
Lotufo, Guilherme R. | Farrar, J Daniel | Biedenbach, James M. | Laird, Jennifer G. | Krasnec, Michelle O. | Lay, Claire | Morris, Jeffrey M. | Gielazyn, Michel L.
Crude oil released from the Deepwater Horizon disaster into the Gulf of Mexico posed potential impacts to infaunal invertebrates inhabiting near shore habitats. The effects of sediment-associated weathered slick oil on the amphipod Leptocheirus plumulosus was assessed using 28-d exposures to total PAH sediment concentrations ranging from 0.3 to 24mg/kg (sum of 50 PAHs or tPAH50). Survival and growth rate were significantly decreased in the 2.6, 11.4 and 24.2mg/kg treatments, but only growth in 5.5mg/kg. Offspring production was dramatically decreased but was variable and significantly different only for 24.2mg/kg. The concentrations associated with 20% decreases relative to reference were 1.05 (95% CI=0–2.89) mg/kg tPAH50 for growth rate and 0.632 (95% CI=0.11–2.15) mg/kg tPAH50 for offspring production. The concentrations of PAHs affecting amphipods are within the range of concentrations measured in marsh areas reportedly impacted by DWH oil after its release.
显示更多 [+] 显示较少 [-]The value of offshore field experiments in oil spill technology development for Norwegian waters
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.
显示更多 [+] 显示较少 [-]Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations
2016
Jin, Peng | Gao, Kunshan
Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations ~700 to ~1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species' resilience to OA decreased after 2000 generations under high CO2 selection.
显示更多 [+] 显示较少 [-]