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Resultados 1661-1670 de 5,137
Proof of concept for a model of light reflectance of plastics floating on natural waters
2018
Goddjin, Lonneke | Dufaur, Juvenal
Remote sensing of plastic littering natural waters is an emerging field of science with the potential to provide observations on local to global scales. We present the verification of a theoretical reflectance model of sunlight interacting with a water surface littered with buoyant plastic objects. We measured a few common litter items of different polymers as well as shapes, transparencies, and surface roughnesses. Spectral reflectance measurements in the field were backed up with measurements in the laboratory of coefficients of total and diffuse reflectance, transmittance and absorption. We evaluated a single-band algorithm for 850 nm wavelength and a dual-band algorithm using a second wavelength at a polymer absorption band between 1660 and 1730 nm. Both algorithms were plastic litter type specific. Our findings show that for interpreting spectral remote sensing of floating plastic, physical properties that control geometrical optics should complement information about the absorption spectra of the polymer.
Mostrar más [+] Menos [-]Highly efficient oil-in-water emulsion and oil layer/water mixture separation based on durably superhydrophobic sponge prepared via a facile route
2018
Wang, Jintao | Wang, Hongfei | Geng, Guihong
The fabrication of the materials with special wettability being capable of removing oil layer on water surface and oil droplets in oil-in-water emulsion is an important issue for water pollution. So far, it still remains challenging to explore a simple, facile, environmentally friendly approach for achieving this goal. Herein, inspired by the adhesion of marine mussels, the polydopamine (PDA) coating with hierarchical structure was directly fabricated onto the surface of melamine (MF) sponge by facile self-polymerization in dopamine solution. Then, a superhydrophobic and superoleophilic sponge was successfully obtained after the modification by dodecanethiol (DDT) at ambient temperature. The as-prepared sponge can selectively separate a series of oil droplets in oil-in-water emulsion with high efficiency (transparency: 76.6–93.8%) and absorb various oils or organic solvents up to 45.2–98.6 times of its own weight. Moreover, in conjunction with a vacuum system, great amounts of oils up to 20 times its own weight can be effectively separated from water surface within 1s by the sponge. Due to low cost, simple process, and easy accessibility, the as-prepared sponge has potential applications in oil-in-water emulsion separation and oil spill cleanup.
Mostrar más [+] Menos [-]Spatial and vertical distribution of radiocesium in seawater of the East China Sea
2018
Zhao, Lijun | Liu, Dantong | Wang, Jinlong | Du, Jinzhou | Hou, Xiaolin | Jiang, Yifei
The 137Cs activity in surface water of the East China Sea (ECS) was 0.66–1.36 Bq m−3 during May of 2011. The low activities were observed in the Changjiang Estuary and Zhejiang-Fujian coast and high activities were observed in the south offshore and Kuroshio Current pathway, suggesting that the influence from the current system in the ECS. The 134Cs were undetectable (<0.03 Bq m−3) and the contribution of the Fukushima accident to ECS is estimated to be below 3%; hence it is negligible during the investigation period. Using the vertical profiles of 137Cs in the ECS, the mass balance is obtained, which suggests that the oceanic input dominates the 137Cs source in the ECS. 137Cs is potentially useful to trace water mass movement in the ECS. Our study provides comprehensive baseline of 137Cs in the ECS for evaluation of the possible influence of the nuclear power plants in the future.
Mostrar más [+] Menos [-]A predictive approach to benthic marine habitat mapping: Efficacy and management implications
2018
(Riccardo),
The availability of marine habitats maps remains limited due to difficulty and cost of working at sea. Reduced light penetration in the water hampers the use of optical imagery, and acoustic methods require extensive sea-truth activities. Predictive spatial modelling may offer an alternative to produce benthic habitat maps based on complete acoustic coverage of the seafloor together with a comparatively low number of sea truths. This approach was applied to the coralligenous reefs of the Marine Protected Area of Tavolara - Punta Coda Cavallo (NE Sardinia, Italy). Fuzzy clustering, applied to a set of observations made by scuba diving and used as sea truth, allowed recognising five coralligenous habitats, all but one existing within EUNIS (European Nature Information System) types. Variable importance plots showed that the distribution of habitats was driven by distance from coast, depth, and lithotype, and allowed mapping their distribution over the MPA. Congruence between observed and predicted distributions and accuracy of the classification was high. Results allowed calculating the occurrence of the distinct coralligenous habitats in zones with different protection level. The five habitats are unequally protected since the protection regime was established when detailed marine habitat maps were not available. A SWOT (Strengths-Weaknesses-Opportunities-Threats) analysis was performed to identify critical points and potentialities of the method. The method developed proved to be reliable and the results obtained will be useful when modulating on-going and future management actions in the studied area and in other Mediterranean MPAs to develop conservation efforts at basin scale.
Mostrar más [+] Menos [-]Nutrient bioextraction and microalgae growth inhibition using submerged macrophyte Myriophyllum spicatum in a low salinity area of East China Sea
2018
Liu, Qiao | Sun, Bin | Huo, Yuanzi | Liu, Mengmeng | Shi, Jinting | Jiang, Ting | Zhang, Qi | Tang, Chunyu | Bi, Hongsheng | He, Peimin
Myriophyllum spicatum was cultivated in a low salinity area of Hangzhou Bay (salinity 5.8–6.5), from August to October in 2016, to evaluate the abilities of its nutrient bioextraction and microalgae growth inhibition. During the 72-day cultivation period, M. spicatum had a specific growth rate (SGR) of 6.23%day⁻¹ and increased 20-fold in biomass (wet weight). Tissue C, N and P assimilation quantities of M. spicatum were found to be 3279.39kg, 360.61kg and 26.97kg, respectively. The concentration of NH₄-N, NO₃-N, NO₂-N and PO₄-P after M. spicatum cultivation was decreased by 47.92%, 58.28%, 36.40% and 55.57%, respectively. The phytoplankton density was decreased from 1064.60×10⁴cellsL⁻¹ to 12.85×10⁴cellsL⁻¹. These results indicated that cultivation of M. spicatum can help in nutrient bioextraction and microalgae growth inhibition in low salinity marine water bodies.
Mostrar más [+] Menos [-]Distribution and speciation of phosphorus in foreshore sediments of the Thames estuary, UK
2018
Tye, Andrew M. | Rushton, Jeremy | Vane, Christopher H.
Estuarine sediments can be a source of Phosphorus (P) to coastal waters, contributing to nutrient budgets and geochemical cycles. In this work, the concentration and speciation of P in 47 cores were examined from the inter-tidal mud flats of the tidal river Thames (~120km). Results of P concentration and speciation were combined with published data relating to known sediment dynamics and water chemistry (salinity) within the estuary to produce a conceptual model of sediment-P behaviour. Results demonstrated significant P desorption occurring after sediment passed through the Estuarine Turbidity Maximum and when the salinity of the river water exceeded ~6ppt. It was found that organic P was desorbed to a greater extent than inorganic P in the lower estuary. Models were used to identify those geochemical parameters that contributed to the Total P (R²=0.80), oxalate extractable P (R²=0.80) and inorganic P (R²=0.76) concentrations within the Thames estuary.
Mostrar más [+] Menos [-]Ozone Production Efficiency in Highly Polluted Environments
2018
Wang, Junhua | Ge, Baozhu | Wang, Zifa
When developing ozone control strategies, the empirical kinetic modeling approach curve cannot easily be applied to practical problems. On this basis, the ozone production efficiency (OPE) is proposed as an indicator to represent the effects of NOₓ on ozone. The research results of the OPE are reviewed and include the definition and calculation of OPE, observations and model simulations, several factors affecting the OPE, and the application of OPE. The measurements and applications of the OPE have improved and become widespread after decades of development. OPE is mostly used to measure regional atmospheric oxidation characteristics, which play an important role when developing ozone control strategies (especially in highly polluted areas). However, there have been few studies on the advancement of chemical mechanisms in the OPE in recent years. In addition, there is no detailed interpretation of the strong linear correlation between ozone and NOz. The results may be significant for improving simulation results and understanding the formation of ozone.
Mostrar más [+] Menos [-]Underwater noise assessment outside harbor areas: The case of Port of Civitavecchia, northern Tyrrhenian Sea, Italy
2018
Cafaro, Valentina | Piazzolla, Daniele | Melchiorri, Cristiano | Burgio, Calogero | Fersini, Giorgio | Conversano, Francesca | Piermattei, Viviana | Marcelli, Marco
Underwater noise assessment is particularly important in coastal areas where a wide range of natural and anthropogenic sounds generate complex and variable soundscapes. In the last century, the number and size of noise sources has increased significantly, thereby increasing the ocean's background noise. Shipping is the main source of lower-frequency underwater noises (<500 Hz). This research aimed to provide an initial assessment of underwater noise levels in a coastal area of the northern Tyrrhenian Sea (Italy) using short-term recordings. Spatial and temporal variations in the noise level, and the type and number of ships sailing through the port were recorded. A significant correlation was found between ferry boats and sound pressure levels, indicating their role as a prevalent source of low frequency underwater noise in the project area. This research could provide the baseline for implementation of distribution and point-source underwater noise models that are required for sustainable coastal management.
Mostrar más [+] Menos [-]Experimental and modeled thermoregulatory costs of repeated sublethal oil exposure in the Double-crested Cormorant, Phalacrocorax auritus
2018
Mathewson, Paul D. | Hanson-Dorr, Katie C. | Porter, Warren P. | Bursian, Steven J. | Dean, Karen M. | Healy, Kate | Horak, Katherine | Link, Jane E. | Harr, K.E. | Dorr, Brian S.
To fully understand the impact of oil exposure, it is important to understand sublethal effects like how increased thermoregulatory costs may affect survival and reproduction. However, it is difficult and time-consuming to measure these effects in wild animals. We present a novel use of a bioenergetics model, Niche Mapper™, to estimate thermoregulatory impacts of oiling, using data from captive Double-crested Cormorants (Phalacrocorax auritus) experimentally exposed to oil. Oiled cormorants had significant increases in surface body temperatures following exposure. Niche Mapper accurately predicted surface temperatures and metabolic rates for unoiled and oiled cormorants and predicted 13–18% increased daily energetic demands due to increased thermoregulatory costs of oiling, consistent with increased food consumption observed in experimentally oiled cormorants. We show that Niche Mapper can provide valuable insight into sublethal oiling effects by quantifying the extent to which thermoregulatory costs divert energy resources away from important life processes like maintenance, reproduction and migration.
Mostrar más [+] Menos [-]Operational modelling of bigeye tuna (Thunnus obesus) spatial dynamics in the Indonesian region
2018
Lehodey, P. | Senina, I. | Wibawa, T.A. | Titaud, O. | Calmettes, B. | Conchon, A. | Tranchant, B. | Gaspar, P.
With INDESO, Indonesia has implemented a system for the monitoring and management of its tuna resources. Despite increasing catch, very few is known about the dynamics and real abundance of tuna species in the Indonesian waters and adjacent oceanic regions. The SEAPODYM model was implemented in an operational chain of production for the Indonesian region to simulate tuna spatial dynamics in realtime. This challenging objective imposed developing a global scale model at coarse resolution to provide initial and boundaries conditions of the regional model. A parameter optimization approach was used to provide the best solution fitting several hundreds of thousand catch observations, over a long historical simulation at coarse resolution. Then downscaling method and regional modelling at high resolution (1/12°x day) were validated to produce realtime and forecast on a weekly basis. The architecture of this application, the approach for its parameterization and some key results are presented and discussed.
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