خيارات البحث
النتائج 1311 - 1320 من 3,991
Rapid assessment of target species: Byssate bivalves in a large tropical port
2016
Rapid assessment sampling for target species is a fast cost-effective method aimed at determining the presence, abundance and distribution of alien and native harmful aquatic organisms and pathogens that may have been introduced by shipping. In this study, the method was applied within a large tropical port expected to have a high species diversity. The port of Kaohsiung was sampled for bivalve molluscan species that attach using a byssus. Such species, due to their biological traits, are spread by ships to ports worldwide. We estimated the abundance and distribution range of one dreissenid (Mytilopsis sallei) and four mytilids (Brachidontes variabilis, Arcuatula senhousa, Mytilus galloprovincialis, Perna viridis) known to be successful invaders and identified as potential pests, or high-risk harmful native or non-native species. We conclude that a rapid assessment of their abundance and distribution within a port, and its vicinity, is efficient and can provide sufficient information for decision making by port managers where IMO port exemptions may be sought.
اظهر المزيد [+] اقل [-]Pollutant levels in discarded fish species by Spanish trawlers operating in the Great Sole Bank and the Atlantic coast of the Iberian Peninsula
2016
Organic and inorganic pollutant levels were determined for the most discarded species from trawlers operating in Great Sole and Spanish coastal fishing grounds. Results for heavy metals indicated that Cd can reach values higher than legal limits for some species and tissues, while Hg and Pb concentrations are below established values. No significant variation was noticed with fishing grounds, but both season influences in the case of Pb and interspecies variation for Hg and Cd have been detected. Valorization recommendations could be therefore established according to the levels found in the different species.
اظهر المزيد [+] اقل [-]Pollution from EOLV dismantling and the corresponding countermeasures
2016
Zhang, Hu
There are problems associated with dismantling vessels that have reached the end of their life, when pollution problems associated with the process need to be addressed. The first problem in “end-of-life vessels” (EOLV) is to define their legal frameworks. The second problem is their dismantlement for recycling of ships. In order to reduce the effects of pollution caused by EOLV dismantling, the International Maritime Organization (IMO) adopted the Hong Kong Convention on 15 May 2009. While preparing for implementing the obligations under the Hong Kong Convention, China shall make effort on five aspects: (i) establish an ISRT for the safe and environmentally sound recycling of ships, (ii) improve the competitiveness of ship dismantling plants, (iii) strengthen international exchanges, (iv) amend the domestic laws and regulations, and (v) support from the China Classification Society.
اظهر المزيد [+] اقل [-]Natural and man-made radionuclides in sediments of an inlet in Rio de Janeiro State, Brazil
2016
Carvalho, Franciane Martins de | Lauria, Dejanira da Costa | Ribeiro, Fernando Carlos Araújo | Fonseca, Rafael Tonelli | Peres, Sueli da Silva | Martins, Nádia Soido Falcão
The distribution of natural radionuclides 226Ra, 228Ra, 40K and man-made radionuclides (54Mn, 60Co and 137 Cs) in the surface sediments of an inlet of Ribeira Bay were investigated. Sediment samples were collected and analyzed for radionuclides, organic matter, carbonate, sulfate, cationic exchange capacity and grain size composition. The natural radionuclide concentrations ranged from 4.4 to 45, from 10 to 93, from 66 to 1347Bq·kg−1 dry weight for 226Ra, 228Ra and 40K, respectively. Natural radionuclide concentrations tend to be higher in the silt fraction, which determines their pattern distributions. Only one sample presented measurable concentration for 137Cs, while 54Mn was detected in two samples and 60Co in four sediment samples. Man-made radionuclides present a maximum value of dose external four times lower than the normal background and the potential risk due to the presence of man-made radionuclides in sediments is lower than the risk provided by the natural radionuclides.
اظهر المزيد [+] اقل [-]Temporal and spatial changes in persistent organic pollutants in Vietnamese coastal waters detected from plastic resin pellets
2016
Le, Dung Quang | Takada, Hideshige | Yamashita, Rei | Mizukawa, Kaoruko | Hosoda, Junki | Tuyet, Dao Anh
Plastic resin pellets collected at Minh Chau island and Ba Lat estuary between 2007 and 2014 in Vietnam were analyzed for dichloro-diphenyl-trichloroethanes (DDTs), polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs). The study was carried out as part of the International Pellet Watch program for monitoring the global distribution of persistent organic pollutants (POPs). Higher levels of DDTs compared to PCBs indicated agricultural inputs rather than industrial discharges in the region. Most POP concentrations on both beaches decreased over the period, with the exception of HCH isomers. Though the concentration of DDTs showed a drastic decline on both beaches between 2007/2008 and 2014, DDTs accounted for 60–80% of total DDTs, suggesting that there is still a fresh input of these chemicals in the region. This study strongly recommends further investigations to track temporal and spatial patterns of POP levels in the marine environment using plastic resin pellets.
اظهر المزيد [+] اقل [-]The development of a preliminary rock reef fish multimetric index for assessing thermal and urban impacts in a tropical bay
2016
Teixeira-Neves, Tatiana Pires | Neves, Leonardo Mitrano | Araújo, Francisco Gerson
We developed a multimetric index for assessing ecological conditions in rocky reefs areas to evaluate thermal and urban influences on fish community. Eight metrics were selected to assess thermal influence: (1) total number of species; (2) number of water column species; (3) number of transient species; (4) density of individuals with low resilience; (5) density of omnivores; (6) density of carnivores; (7) number of cryptic species; (8) density of herbivores. For urban influence, six metrics were selected: (1) total density; (2) ratio between the number of rare species and the total number of species; (3) density of individuals with heavy fishing pressure; (4) number of resident species; (5) number of cryptic species; (6) density of herbivores. This preliminary index succeed in discriminating control/impacted sites and proved to be an important tool to assess impacts that alter fish community and have potential to be used in tropical rock reef coastal areas.
اظهر المزيد [+] اقل [-]Responses of bacterial and archaeal communities to nitrate stimulation after oil pollution in mangrove sediment revealed by Illumina sequencing
2016
Wang, Lei | Huang, Xu | Zheng, Tian-Ling
This study aimed to investigate microbial responses to nitrate stimulation in oiled mangrove mesocosm. Both supplementary oil and nitrate changed the water and sediment chemical properties contributing to the shift of microbial communities. Denitrifying genes nirS and nirK were increased several times by the interaction of oil spiking and nitrate addition. Bacterial chao1 was reduced by oil spiking and further by nitrate stimulation, whereas archaeal chao1 was only inhibited by oil pollution on early time. Sampling depth explained most of variation and significantly impacted bacterial and archaeal communities, while oil pollution only significantly impacted bacterial communities (p<0.05). Despite explaining less variation, nitrate addition coupled with oil spiking enhanced the growth of hydrocarbon degraders in mangrove. The findings demonstrate the impacts of environmental factors and their interactions in shaping microbial communities during nitrate stimulation. Our study suggests introducing genera Desulfotignum and Marinobacter into oiled mangrove for bioaugmentation.
اظهر المزيد [+] اقل [-]Investigation of fungal volatile organic compounds in hospital air
2016
Pantoja, Lydia Dayanne Maia | do Nascimento, Ronaldo Ferreira | de Araújo Nunes, Ana Barbara
Fungal growth within the structure of buildings or in ventilation filters generates “hidden contamination”, which cannot be detected only through visual inspection. At the beginning of development, the fungi release fungal volatile organic compounds (FVOCs) into the atmosphere, which can originate from metabolic pathways or from the enzymatic degradation of materials. This study analyzed the air quality of a public referral hospital in Fortaleza, Ceará, Brazil in terms of FVOCs, to establish ways to improve methods of monitoring and control of specific sectors in the hospital. For that, we created and validated a protocol for detection of FVOCs, using GC/MS, while fungal samples were identified by analysis of macro and micromorphology. In total, 48 samples (60.5% positive) were analyzed for FVOCs; 7 were detected in at least one of the sectors analyzed, with 2-heptanone (179.5 μg/m3) and 2-methyl-1-propanol (121.5 μg/m3) as the most abundant. With respect to fungal findings, 24 samples were analyzed, with a high number of colony-forming units per cubic meter (CFU/m3) observed in all sectors. The airborne fungal spectrum revealed the existence of 19 genera, composed predominantly by hyaline filamentous deuteromycetes. Analysis with periodic monitoring is still needed to allow improvement in the data quality. Also, further discussion on the subject in the academic and legislative environment is needed to contribute to the systematic study of aerobiology.
اظهر المزيد [+] اقل [-]Heavy metal accumulation in tissues of two sea cucumbers, Holothuria leucospilota and Holothuria scabra in the northern part of Qeshm Island, Persian Gulf
2016
Mohammadizadeh, Maria | Bastami, Kazem Darvish | Ehsanpour, Maryam | Afkhami, Majid | Mohammadizadeh, Flora | Esmaeilzadeh, Marjan
The concentrations of some heavy metals (Cd, Cu, Zn andPb) were investigated in the sediments and the two species of sea cucumber (Holothuria leucospilota and Holothuria scabra) from northern part of Qeshm Island, Persian Gulf. The levels of Cu, Zn and Pb in sediment varied significantly among sampling sites (p<0.05). The highest levels of Zn and Pb in H. leucospilota were recorded in body wall whereas the highest contents of Zn and Pb in H. scabra were measured in respiratory tree organ, respectively. Cu and Cd were the most abundant elements in gonads of H. leucospilota while highest levels of Cd and Cu in H. scabra were measured in the gonad and derm, respectively. Cu and Zn concentrations were below permissible limits for human consumption while Cd and Pb were above permissible limits for human consumption.
اظهر المزيد [+] اقل [-]Reducing spatial variation in environmental assessment of marine benthic fauna
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 [-]