خيارات البحث
النتائج 761 - 770 من 2,513
A temporal and spatial assessment of TBT concentrations at dredged material disposal sites around the coast of England and Wales النص الكامل
2014
Bolam, Thi | Barry, Jon | Law, Robin J. | James, David | Thomas, Boby | Bolam, Stefan G.
Despite legislative interventions since the 1980s, contemporary concentrations of organotin compounds in marine sediments still impose restrictions on the disposal of dredged material in the UK. Here, we analyse temporal and spatial data to assess the effectiveness of the ban on the use of TBT paints in reducing concentrations at disposal sites.At a national scale, there was a statistically significant increase in the proportion of samples in which the concentration was below the limit of detection (LOD) from 1998 to 2010. This was observed for sediments both inside and outside the disposal sites. However, this temporal decline in organotin concentration is disposal site-specific. Of the four sites studied in detail, two displayed significant increases in proportion of samples below LOD over time. We argue that site-specificity in the effectiveness of the TBT ban results from variations in historical practices at source and unique environmental characteristics of each site.
اظهر المزيد [+] اقل [-]Regulation of solid waste management at Brazilian ports: Analysis and proposals for Brazil in light of the European experience النص الكامل
2014
Jaccoud, Cristiane | Magrini, Alessandra
With a coastline of 8500km, Brazil has 34 public ports and various private terminals, which together in 2012 handled 809 million tonnes of goods. The solid wastes produced (from port activities, ships and cargoes) pose a highly relevant problem, both due to the quantity and diversity, requiring a complex and integrated set of practices resulting from legal requirements and proactive initiatives. The main Brazilian law on solid waste management is recent (Law 12,305/2010) and the specific rules on solid waste in ports are badly in need of revision to meet the challenges caused by expansion of the sector and to harmonize them with the best global practices. This paper analyzes the current legal/regulatory framework for solid waste management at Brazilian ports and compares this structure with the practice in Europe. At the end, we suggest initiatives to improve the regulation of solid wastes at Brazilian ports.
اظهر المزيد [+] اقل [-]Behavioural and biochemical stress responses of Palinurus elephas after exposure to boat noise pollution in tank النص الكامل
2014
Filiciotto, Francesco | Vazzana, Mirella | Celi, Monica | Maccarrone, Vincenzo | Ceraulo, Maria | Buffa, Gaspare | Stefano, Vincenzo Di | Mazzola, Salvatore | Buscaino, Giuseppa
This study examined the effects of boat noise on the behavioural and biochemical parameters of the Mediterranean spiny lobster (Palinurus elephas).The experiment was conducted in a tank equipped with a video and audio recording system. 18 experimental trials, assigned to boat noise and control conditions, were performed using lobsters in single and group of 4 specimens. After a 1h habituation period, we audio- and video-recorded the lobsters for 1h. During the experimental phase, the animals assigned to the boat groups were exposed to boat noise pollution (a random sequence of boat noises). Exposure to the noise produced significant variations in locomotor behaviours and haemolymphatic parameters. Our results indicate that the lobsters exposed to boat noises increased significantly their locomotor activities and haemolymphatic bioindicator of stressful conditions such as glucose, total proteins, Hsp70 expression and THC when tested both singly and in groups.
اظهر المزيد [+] اقل [-]Oil sorbents with high sorption capacity, oil/water selectivity and reusability for oil spill cleanup النص الكامل
2014
Wu, Daxiong | Fang, Linlin | Qin, Yanmin | Wu, Wenjuan | Mao, Changming | Zhu, Haitao
A sorbent for oil spill cleanup was prepared through a novel strategy by treating polyurethane sponges with silica sol and gasoline successively. The oil sorption capacity, oil/water selectivity, reusability and sorption mechanism of prepared sorbent were studied. The results showed that the prepared sorbent exhibited high sorption capacity and excellent oil/water selectivity. 1g of the prepared sorbent could adsorb more than 100g of motor oil, while it only picks up less than 0.1g of water from an oil–water interface under both static and dynamic conditions. More than 70% of the sorption capacity remained after 15 successive sorption–squeezing cycles, which suggests an extraordinary high reusability. The prepared sorbent is a better alternative of the commercial polypropylene sorbent which are being used nowadays.
اظهر المزيد [+] اقل [-]The role of dispersants’ dynamic interfacial tension in effective crude oil spill dispersion النص الكامل
2014
Riehm, David A. | McCormick, Alon V.
The dispersion effectiveness of dispersants containing Tween 80, Span 80, and dioctyl sodium sulfosuccinate (DOSS) was characterized using a modified Swirling Flask test, and was correlated with both initial and dynamic interfacial tension produced by those dispersants at an oil–water interface. Compositional trends in effectiveness were shown to be governed by: (1) initial oil–water interfacial tension observed upon dispersant–oil–saltwater contact; (2) rate of increase (or decrease) from the initial interfacial tension as DOSS was rapidly lost to the aqueous phase; and (3) gradually slowing kinetics of dispersant adsorption to the oil–water interface as Span 80 concentration was increased, which ultimately diminished dispersion effectiveness considerably even as dynamic interfacial tension remained <10−3mN/m. It is proposed that this third phenomenon results not only from the hydrophobicity of Span 80, but also from the dependence of mixed Tween–Span–DOSS reverse micelles’ stability in crude oil on dispersant composition.
اظهر المزيد [+] اقل [-]Eutrophication threatens Caribbean seagrasses – An example from Curaçao and Bonaire النص الكامل
2014
Govers, Laura L. | Lamers, Leon P.M. | Bouma, Tjeerd J. | de Brouwer, Jan H.F. | van Katwijk, Marieke M.
Seagrass beds are globally declining due to human activities in coastal areas. We here aimed to identify threats from eutrophication to the valuable seagrass beds of Curaçao and Bonaire in the Caribbean, which function as nursery habitats for commercial fish species. We documented surface- and porewater nutrient concentrations, and seagrass nutrient concentrations in 6 bays varying in nutrient loads. Water measurements only provided a momentary snapshot, due to timing, tidal stage, etc., but Thalassia testudinum nutrient concentrations indicated long-term nutrient loads. Nutrient levels in most bays did not raise any concern, but high leaf % P values of Thalassia in Piscadera Bay (∼0.31%) and Spanish Water Bay (∼0.21%) showed that seagrasses may be threatened by eutrophication, due to emergency overflow of waste water and coastal housing. We thus showed that seagrasses may be threatened and measures should be taken to prevent loss of these important nursery areas due to eutrophication.
اظهر المزيد [+] اقل [-]Temporal pattern in the bloom-forming macroalgae Chaetomorpha linum and Ulva pertusa in seagrass beds, Swan Lake lagoon, North China النص الكامل
2014
Zhang, Xiaomei | Zhou, Yi | Liu, Peng | Wang, Feng | Liu, Bingjian | Liu, Xujia | Xu, Qiang | Yang, Hongsheng
Seagrasses that are distributed over a large area of the Swan Lake, Weihai, China, support a productive ecosystem. In recent years, however, frequent macroalgal blooms have changed the ecosystem structure and threatened the seagrasses. To understand the bloom-forming macroalgae we conducted a yearly field survey of Swan Lake. Results indicated that the macroalgae Chaetomorpha linum and Ulva pertusa both exhibited a much higher productivity and attained a greater maximum biomass (of 1712±780gDWm−2 and 1511±555gDWm−2, respectively) than was the case for the seagrasses. The mean annual atomic ratios of C/N, C/P and N/P in C. linum were 14.31±4.45, 402.82±130.25, and 28.12±2.08, respectively. The δ15N values (11.09±0.91‰ for C. linum; 9.27±2.83‰ for U. pertusa) indicated a land-based source of N enrichment to the macroalgal blooms. High concentrations of nitrogen and phosphorus in the lagoon, particularly near the river mouth, supported the blooms.
اظهر المزيد [+] اقل [-]Polycyclic aromatic hydrocarbon concentrations across the Florida Panhandle continental shelf and slope after the BP MC 252 well failure النص الكامل
2014
Snyder, Richard A. | Ederington-Hagy, Melissa | Hileman, Fredrick | Moss, Joseph A. | Amick, Lauren | Carruth, Rebecca | Head, Marie | Marks, Joel | Tominack, Sarah | Jeffrey, Wade H.
The Florida Panhandle continental shelf environment was exposed to oil from the BP oil well failure in the Gulf of Mexico during 2010. Floating mats of oil were documented by satellite, but the distribution of dissolved components of the oil in this region was unknown. Shipek® grab samples of sediments were taken during repeated cruises between June 2010 and June 2012 to test for selected polycyclic aromatic hydrocarbons (PAHs) as indicators of this contamination. Sediments were collected as composite samples, extracted using standard techniques, and PAHs were quantified by GC/MS-SIM. PAHs in samples from the continental slope in May 2011 were highest near to the failed well site and were reduced in samples taken one year later. PAHs from continental shelf sediments during the spill (June 2010) ranged from 10 to 165ngg−1. Subsequent cruises yielded variable and reduced amounts of PAHs across the shelf. The data suggest that PAHs were distributed widely across the shelf, and their subsequent loss to background levels suggests these compounds were of oil spill origin. PAH half-life estimates by regression were 70–122days for slope and 201days for shelf stations.
اظهر المزيد [+] اقل [-]The effect of suspended sediment on fertilization success in the urchin Evechinus chloroticus: Analysis of experimental data using hierarchical Bayesian methods النص الكامل
2014
Miller, S.L. | Richardson, K. | Edwards, P.A.
Terrestrial sediments are a significant stressor on coastal ecosystems, with both suspended and deposited sediment having adverse effects on aquatic organisms. However, information on the effect of suspended sediments on fertilization success for urchin species is lacking. Using sediment levels similar to those encountered in situ, a controlled experiment was conducted to test whether suspended sediment affects fertilization success in the urchin Evechinus chloroticus. Analyses used generalized linear mixed models (GLMMs) and hierarchical Bayesian (HB) regression. Both approaches showed a significant decrease in fertilization success with increased suspended sediment levels. Uncertainties in estimates were narrower for HB models, suggesting that this approach has advantages over GLMMs for sparse data problems sometimes encountered in laboratory experiments. Given future global change scenarios, this work is important for predicting the effects of stressors such as sedimentation that may ultimately impact marine populations.
اظهر المزيد [+] اقل [-]Observations of air quality on the outskirts of an urban agglomeration during the implementation of pollution reduction measures النص الكامل
2014
Sun, Yang | Zhang, Junke | Pan, Yuepeng | Wang, Yuesi | Liao, Tingting | Song, Tao
Based on observations at Heshan, a boundary area in the city agglomeration of the Pearl River Delta region in China, atmospheric pollutants such as PM2.5, O3, CO, SO2, NOZ, NO2 and NO were monitored between the 12th and 29th November, 2010. Meteorological parameters, including temperature, humidity, dew point, air pressure, ultraviolet light, wind direction, and wind speed were also measured. By combining the meteorological parameters with the atmospheric pollutant data, we performed Positive Matrix Factorization (PMF) and ozone production efficiency (OPE) analysis to objectively understand the interrelations among the pollutants, as well as between the pollutants and the meteorological factors. During the observation period, there were various meteorological changes such as rainfall, cold air transit, and sunshine that created conditions for the formation or dispersal of pollutants. The study period coincided with the 16th Asian Games, during which time the government adopted strict measures to reduce the discharge of pollutants around the Pearl River Delta area. However, we still observed serious pollution of PM2.5 and O3, of which the highest value of PM2.5 was 210 μg m−3 and the highest value of O3 reached 117 ppb. At the same time, the high concentrations of CO, NO, NO2, NOZ, and SO2 could not be cleared away with rainfall in such a short period of time. On the basis of PMF analysis, we found that three factors influence the air quality of this region: local biomass burning, secondary pollutants of regional transport, and high industrial pollutant emissions. According to OPE analysis, the O3 pollution was mostly found to be VOC–sensitive but occasionally NOX–sensitive for OPE values greater than 10.
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