خيارات البحث
النتائج 1321 - 1330 من 3,991
Towards an integrated approach to marine benthic monitoring
2016
Barrio Froján, Christopher R.S. | Cooper, Keith M. | Bolam, Stefan G.
In the UK, most marine benthic monitoring is carried out in a piecemeal fashion, funded by different sectors of industry that utilise the marine environment under licence. Monitoring requirements are imposed by licence conditions, which can vary considerably between licences. The UK Government also conducts marine environmental surveys in support of its legislative commitments. The present investigation reviews these different monitoring approaches to highlight whether synergies between them could be developed into an integrated approach to marine benthic monitoring. An integrated approach would have ecological benefits, as greater consistency in sampling and analytical protocols would reduce uncertainty in the predictions of impact, and facilitate the assessment of Good Environmental Status under the Marine Strategy Framework Directive. The same approach would also be of financial benefit, as spatio-temporal duplication in sampling would be reduced, and the value of acquired data would be maximised, resulting in a more efficient and cost-effective approach.
اظهر المزيد [+] اقل [-]De- facto marine protection from a Navy bombing range: Farallon De Medinilla, Mariana Archipelago, 1997 to 2012
2016
Smith, Stephen H. | Marx, Donald E.
Fourteen surveys were conducted at Farallon De Medinilla (a U.S. Department of Defense bombing range in the Mariana Archipelago) between 1997 and 2012; annual surveys were conducted from 1999 through 2012. There was no evidence that the condition of the biological resources assessed had changed, or been adversely impacted to a significant degree by the training activities being conducted there. Restricted access has resulted in a de-facto preserve effect and outweighs minor negative impacts from training. The health, abundance and biomass of fishes, corals and other marine resources are comparable to or superior to those in similar habitats at other locations within the Mariana Archipelago. Our research suggests that the greatest threat to FDM's marine resources is from fishermen, not military training activities.
اظهر المزيد [+] اقل [-]Anthropogenic influences on aerosols at Ny-Ålesund in the summer Arctic
2016
Zhan, Jianqiong | Li, Wei | Chen, Liqi | Lin, Qi | Gao, Yuan
The Arctic atmosphere has been disturbed by human activities. To improve the understanding of anthropogenic influences, major ionic species and carbonaceous components were measured at Ny-Ålesund in July 2012. The results suggested that Na+ and Cl− are the dominant water soluble inorganic species, accounting for 57 ± 17% of the mass of measured ionic species, and 61% of the variance in organic carbon can be explained by oceanic emissions. Aerosols in this area were found to be altered by secondary production involving oxides of sulfur, nitrogen and ammonia from anthropogenic activities, resulting in relative high concentrations of secondary inorganic aerosols (SIA) (such as non-sea salt (nss)-SO42−, NO3− and NH4+), with a mean concentration of 158 ng m−3. SIAs were featured by a mean [NH4+]/[nss-SO42−] ratio of 0.57 and a neutralization ratio (NR) of 0.074, indicating a deficit of NH4+. Thus, the production of particulate NH4 NO3 was strongly limited and SIAs were likely to remain in more acidic forms, NH4HSO4 or H2SO4 rather than as (NH4)2SO4. Chloride depletion of 11%–22% occurred in the samples with high concentrations of excess acidic species (defined as [nss-SO42− + NO3− − NH4+]) and high sea salts. The formation of SIAs and chloride depletion appeared to produce acidic aerosols with a mean pH of 4.51 and high free [H] concentrations of 3.06 ± 0.75 nmol m−3 in aerosols, accounting for 77% of the total [H] concentration. This implies that anthropogenic species could be engaged efficiently in modifying of the properties of aerosols at Ny-Ålesund.
اظهر المزيد [+] اقل [-]Investigation on VOC Emissions from Automobile Sources by Means of Online Mass Spectrometry
2016
Inomata, Satoshi | Yamada, Hiroyuki | Tanimoto, Hiroshi
This study reviews recent research on volatile organic compound (VOC) emissions from motorized vehicle sources by means of online mass spectrometry. Chemical ionization is a powerful tool that usually permits soft ionization of chemical species and it allows the time-resolved measurement of multiple VOCs, even in complex samples where many kinds of VOCs coexist. The vehicular exhaust gasses are investigated using H₃O⁺, NO⁺, Hg⁺, and CH₃C(O)O⁻ as a reagent ion in online chemical ionization mass spectrometry. The proton transfer using H₃O⁺ as a reagent ion was used for the detection of nitro-organic compounds such as nitromethane and nitrophenol. The time-resolved measurement of the nitro-organic compounds in the laboratory experiments with a chassis dynamometer system revealed their emission properties, such as the dependence of the emissions as a function of vehicular velocity and acceleration/deceleration, as well as the effect of various types of exhaust gas treatment. The data regarding the nitromethane and nitrophenol emissions obtained in the field measurements were consistent with the results of the laboratory experiments done with a chassis dynamometer system. In the experiments involving evaporative emissions from gasoline-powered cars, NO⁺ was used as a reagent ion. Online measurements showed that the adsorption of hydrocarbons in a sealed housing evaporative determination unit could result in emissions being underestimated, if the concentrations are monitored only before and after a diurnal breathing loss test. The composition analysis gave an estimated ozone formation potential (OFP) approximately 20 % higher for breakthrough emissions and refueling emissions than for the gasoline that was tested, but the OFP for the permeation emissions was almost the same as the OFP for the test fuel.
اظهر المزيد [+] اقل [-]A combined input–output and sensitivity analysis of CO2 emissions in the high energy-consuming industries: A case study of China
2016
Yuan, Rong | Zhao, Tao
This paper employed an input–output approach combined with a sensitivity analysis to explore the impact of technological changes on CO2 emissions in the high energy-consuming industries. In contrast to most papers in the literature, which focused on the changes between two input–output tables in two different periods, this study analyzed the sensitivity of variations in the quantity of emissions caused by small changes in technical coefficients. An indicator, namely TCE (technical coefficient elasticity), was established to identify the transactions between economic sectors which lead to a large impact on CO2 emissions in the high energy-consuming industries. Additionally, by analyzing factors affecting TCE, this paper divided TCE into structure-relevant TCE and technology-relevant TCE. Sectors have a higher structural TCE value because their products are much demanded by other sectors. Sectors have a higher technological TCE value because they have a large propensity to consume inputs which require many products of the high energy-consuming industries. Our results show that technical coefficients with a higher TCE value correspond to the direct requirements by the high energy-consuming industries themselves. However, the impacts of technological changes in the non-high energy-consuming industries on high energy-consuming industries cannot be overlooked, especially in Transportation industry, Construction industry and manufacturing industries. Several industries have a higher structural TCE value, thus, their influence on CO2 emissions in the high energy-consuming industries is related to a high level of demand of their respective products. However, several industries have a higher technological TCE value, thus, technology innovation will be more effective to decrease CO2 emissions. Therefore, different measures should be adopted for reducing CO2 emissions in the high energy-consuming industries according to different conditions.
اظهر المزيد [+] اقل [-]Diazo-coupling spectrophotometric determination of nitrogen oxides in the air
2016
Huang, Yingying | Shi, Wenjian | Zhang, Caihong | Li, Liang | Wen, Haifeng
A new accurate, sensitive, rapid and convenient measurement for the determination of nitrogen oxides in the air was established. After being oxidized by chromium trioxide (CrO3), nitrogen oxides in the air existed in the form of NO2, then forming nitrite and nitrate after being absorbed by the alkaline aqueous solution. Under acidic condition, the diazo reaction is specific to the nitrite and primary aromatic amine. In this paper, the structure of diazo and coupling compounds were selected and tested through the experiments. The relationship between the azo compound's molecular structure and the sensitivity of the method as well as the electronic flow direction in the conjugated system of azo compounds were studied. A theory that conjugated system's electron cloud in azo compound's molecule flowed from coupling compounds to diazo compounds through nitrogen and nitrogen double bond was proposed. This theory had a guiding function for exploiting highly sensitive chromogenic agents. Furthermore, the conditions and methods of diazo reaction and coupling chromogenic reaction were investigated. A spectrophotometry that p-aminobenzenesulfonic acid as diazo compound and 2-amino-5-naphthol-7-sulfonic acid (J acid) as coupling compound for the determination of nitrogen oxides in the air was established. The maximum absorption wavelength of p-aminobenzenesulfonic acid-J acid azo compound was at 480 nm. And the molar absorptivity was 4.01 × 104 L mol−1 cm−1 with recovery of 98.5%–100.9% and R.S.D. of 1.82%. In addition, the determination limit of measurement was 0.017 mg m−3 nitrogen oxides and the determination range was 0.027–2.0 mg m−3 nitrogen oxides. This method can be easily applied to the determination of the nitrogen oxides in the air.
اظهر المزيد [+] اقل [-]Edward D. Goldberg's proposal of “the Mussel Watch”: Reflections after 40years
2016
Farrington, John W. | Tripp, Bruce W. | Tanabe, Shinsuke | Subramanian, Annamalai | Sericano, José L. | Wade, Terry L. | Knap, Anthony H.
We chronicle the extensive influence over the past forty years of Professor Edward D. Goldberg and his call in 1975 for a “Mussel Watch” or bivalve sentinel organism approach to assess geographic status and temporal trends of several chemicals of environmental concern in the coastal ocean. Examples of local, regional, national and international programs are discussed briefly as are examples of interesting useful findings and limitations to the Mussel Watch concept. Mussel Watch continues to provide useful data about status and trends of chemical contamination in coastal ecosystems.
اظهر المزيد [+] اقل [-]Distribution, sources and ecological risk assessment of PAHs in surface sediments from the Luan River Estuary, China
2016
Zhang, Daolai | Liu, Jinqing | Jiang, Xuejun | Cao, Ke | Yin, Ping | Zhang, Xunhua
The distribution, sources and risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) of surface sediments in the Luan River Estuary, China, have been investigated in the research. The results indicated that the total concentrations of 16 PAHs in surface sediments of the Luan River Estuary ranged from 5.1 to 545.1ngg−1dw with a mean value of 120.8ngg−1dw, which is relatively low in comparison with other estuaries around the world. The PAHs in the study area were mainly originated from pyrogenic sources. Besides, PAHs may be contaminated by petrogenic PAHs as indicated by the selected ratios of PAHs, the 2-tailed Pearson correlation analysis and principal components analysis at different sites. The result of the ecological risk assessment shows little negative effect for most individual PAHs in surface sediments of the Luan River Estuary, China.
اظهر المزيد [+] اقل [-]Living oysters and their shells as sites of nitrification and denitrification
2016
Caffrey, Jane M. | Hollibaugh, James T. | Mortazavi, Behzad
Oysters provide a critical habitat, are a food resource for higher trophic levels and support important commercial fisheries throughout the world. Oyster reefs can improve water quality by removing phytoplankton. While sediment denitrification may be enhanced adjacent to oyster reefs, little is known about nitrification and denitrification associated with living oysters and their shells. We measured nitrification and denitrification in living oysters (Crassostrea virginica and Crassostrea gigas) and empty oyster shells. Nitrification was similar between live oysters and empty oyster shells, however, denitrification was enhanced significantly on living oysters compared to shells. This is the first demonstration of nitrification and denitrification associated with living oysters and their shells. Our data suggest that loss of historic oyster reefs has likely affected the resilience of estuaries to eutrophication. The additional benefit of oyster mediated denitrification should be considered in restoration of oyster reefs as a tool for managing eutrophication.
اظهر المزيد [+] اقل [-]Use of baited remote underwater video (BRUV) and motion analysis for studying the impacts of underwater noise upon free ranging fish and implications for marine energy management
2016
Roberts, Louise | Pérez-Dominguez, Rafael | Elliott, Michael
Free-ranging individual fish were observed using a baited remote underwater video (BRUV) system during sound playback experiments. This paper reports on test trials exploring BRUV design parameters, image analysis and practical experimental designs. Three marine species were exposed to playback noise, provided as examples of behavioural responses to impulsive sound at 163–171dB re 1μPa (peak-to-peak SPL) and continuous sound of 142.7dB re 1μPa (RMS, SPL), exhibiting directional changes and accelerations. The methods described here indicate the efficacy of BRUV to examine behaviour of free-ranging species to noise playback, rather than using confinement. Given the increasing concern about the effects of water-borne noise, for example its inclusion within the EU Marine Strategy Framework Directive, and the lack of empirical evidence in setting thresholds, this paper discusses the use of BRUV, and short term behavioural changes, in supporting population level marine noise management.
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