خيارات البحث
النتائج 2031 - 2040 من 6,558
The fungus Pestalotiopsis sp., isolated from Perna perna (Bivalvia:Mytilidae) cultured on marine farms in Southeastern Brazil and destined for human consumption النص الكامل
2020
dos Santos, Antonia Lúcia | de Medeiros, João Victor Ferreira | Grault, Carlos Eduardo | Santos, Manoel José Soares | Souza, André Luiz Almeida | de Carvalho, Raimundo Wilson
The Pestalotiopsis sp. genus comprises filamentous fungi whose species present both pathogenic and clinical-industrial importance. The cultivation and production of bivalve molluscs in regions of Rio de Janeiro is lucrative both artisanally and industrially, as the climate, geography and water quality favor the practice of this activity throughout the year at reduced costs, making the region competitive in the national market. The aim of this study was to isolate and identify filamentous fungi associated with the internal tissue anatomy of bivalve molluscs (Perna perna) from mariculture farms. Samples collected from BEMAR marine farms were dissected and transferred to 1% hypochlorite, washed in sterile distilled water and sown on Petri dishes containing potato dextrose agar (BDA). After four days, a white colony, displaying vigorous mycelium, cotton-like with abundant sporulation and black conidia masses was isolated. Observations concerning vegetative and reproductive structures were performed by microcultures stained with Amann's Lactophenol andCotton Blue. Micromorphology analyses indicated spindle and septated conidia, with two to three apical filiform appendages and a short basal pedicel. The result indicates that bivalve mollusks may be bioindicators for the presence of Pestalotiopsis sp; associated with water transport, possibly due to diluted sediments in the medium. No infectious processes or lesions in the processed material were observed. This is, to the best of our knowledge, the first report of Pestalotiopsis sp; in Perna perna mytilids.
اظهر المزيد [+] اقل [-]Monitoring the occurrence of microplastic ingestion in Otariids along the Peruvian and Chilean coasts النص الكامل
2020
Perez-Venegas, Diego J. | Toro-Valdivieso, Constanza | Ayala, Félix | Brito, Beatriz | Iturra, Lunna | Arriagada, Maite | Seguel, Mauricio | Barrios Corredera, Carmen | Sepúlveda, Maritza | Oliva, Doris | Cárdenas-Alayza, Susana | Urbina, Mauricio A. | Jorquera, Alberto | Castro-Nallar, Eduardo | Galbán-Malagón, Cristóbal
Repeated reports of microplastic pollution in the marine pinniped diet have emerged in the last years. However, only few studies address the drivers of microplastics presence and the potential implications for monitoring microplastic pollution in the ocean. This study monitored their in the scats (N = 205) of four pinniped species/subspecies at five different locations in the southern Pacific Ocean (Peru and Chile). Samples from all rookeries contained microplastics, and overall, 68% of the examined scats contained fragments/fibers, mostly blue colored. We confirmed that 81.5% of the fragments/fibers were anthropogenic in origin , but only 30% were polymers. Scats from Juan Fernández Archipelago presented higher microplastic concentrations than continental rookeries. Also, the common diet in each location may influence the levels found in the samples. This study presents a useful non-invasive technique to track plastic pollution in top predator diets as bioindicators for future surveillance/management plans applied to different location.
اظهر المزيد [+] اقل [-]Total and subcellular Ti distribution and detoxification processes in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil النص الكامل
2020
Monteiro, Fernanda | Lemos, Leila S. | de Moura, Jailson Fulgêncio | Rocha, Rafael Christian Chávez | Moreira, Isabel | Di Beneditto, Ana Paula M. | Kehrig, Helena A. | Bordon, Isabella C. | Siciliano, Salvatore | Saint'Pierre, Tatiana D. | Hauser-Davis, Rachel Ann
Titanium (Ti), used in many dailyuse products, such as shampoos and sunscreen filters, in the form of TiO₂ nanoparticles (NPs), may elicit adverse marine biota effects. Marine mammal Ti data is scarce, and subcellular distribution and detoxification information is non-existent. Ti concentrations and metalloprotein detoxification in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil were assessed. Metallothionein (MT) concentrations were determined spectrophotometrically, total and subcellular Ti, by ICP-MS and detoxification, by HPLC-ICP-MS. Ti detoxification occurred through MT complexation. Statistical Ti-MT associations were observed in S. bredanensis liver, indicating TiO₂ NPs contamination, as Ti binds to MT only as NPs. MT-Ti correlations were observed for both the coastal (P. blainvillei) and offshore (S. bredanensis) dolphins, evidencing oceanic TiO₂ diffusion. Ti detoxification through binding to reduced glutathione occurred in both species. Thermostable subcellular fractions are a valuable tool for cetacean Ti detoxification assessments and should be applied to conservation efforts.
اظهر المزيد [+] اقل [-]Phytoplankton biomarkers in surface sediments from Liaodong Bay and their potential as indicators of primary productivity النص الكامل
2020
Xiong, Wei | Mei, Xi | Meng, Xiangjun | Chen, Huijun | Yang, Hao
This paper reported the distribution of phytoplankton biomarkers in surface sediments of Liaodong Bay, Bohai Sea. The primary productivity indicated by biomarkers is consistent with the results from modern water column phytoplankton surveys, indicating that the biomarkers can be used to reconstruct the primary productivity. The productivity in the bay mouth is higher than in the shallow coast area, indicating that the main controlling factor is the turbidity rather than terrestrial nutrients. The high primary productivity near Juhua Island is mainly related to eutrophication caused by human culture and land-based sewage discharge. The relative proportion of biomarkers showed that diatom and dinoflagellate contributed more to the coastal area and were mainly related to the competitive advantage under the condition of high nutrient salts, while a high proportion of haptophytes was found in the middle, which corresponded to the high salinity water.
اظهر المزيد [+] اقل [-]Characterization of sediment contaminants in Arctic lagoons and estuaries النص الكامل
2020
Hartwell, S Ian | Lomax, Terri | Dasher, Doug
Baseline characterizations of estuarine sediments in Chukchi and Beaufort Seas, were conducted. Concentrations of 194 organic and elemental chemicals were analyzed in sediment and fish, plus stable isotopes of carbon and nitrogen. The estuaries are shallow embayments, with little shoreline relief. The water columns were turbid, high salinity, and not stratified. Concentrations of arsenic and nickel were elevated throughout the region. Arsenic in fish tissue was elevated. Concentrations of PAHs were relatively high for pristine locations, but did not include petroleum hydrocarbons. Characteristics of PAHs indicate large contributions of terrestrial organic matter. With the exception of Peard Bay, all the estuaries reflected the strong influence of terrestrial plant input with low δₒ/ₒₒ values for carbon and nitrogen. Chlorinated pesticides and PCBs were uniformly low, but detectable in fish tissue. PCB and cyclodiene concentrations were half that seen in southeast Bristol Bay. Hexachlorobenzene was detected in all fish samples.
اظهر المزيد [+] اقل [-]Hypoxia in autumn of the East China Sea النص الكامل
2020
Chen, Chung-Chi | Gong, Gwo-Ching | Chou, Wen-Chen | Shiah, Fuh-Kwo
Hypoxia (O₂ ≤ 2 mg L⁻¹) can severely threaten the survival of marine life and alter the biogeochemical cycles of coastal ecosystems. Its impacts are dependent on its duration. In the present study, hypoxia was observed in autumn at the end of October 2011. It may be one of the latest recorded annual hypoxic events in the East China Sea (ECS). In the hypoxic regions, a large amount of nutrients and dissolved inorganic carbon were observed to regenerate. Also, acidification (low pH) was observed. On the other hand, hypoxic dissipation may be due to the destratification caused by the upwelling of the hypoxic regions in the ECS. These results suggest that hypoxia may occur for longer periods of time than expected and, accordingly, the effects of hypoxia on the ECS ecosystems should be reconsidered and further evaluated.
اظهر المزيد [+] اقل [-]Recent Progress in Impacts of Mixing State on Optical Properties of Black Carbon Aerosol النص الكامل
2020
Wei, Xiaodong | Zhu, Yanhong | Hu, Jianlin | Liu, Chao | Ge, Xinlei | Guo, Song | Liu, Dantong | Liao, Hong | Wang, Huijun
Black carbon (BC) exerts profound impacts on air quality and climate because of its high-absorption cross section over a broad band of solar spectrum. Non-BC materials coated on BC could alter the mixing state of BC particles and can considerably enhance its mass absorption coefficient. Quantification of this absorption enhancement remains a challenge due to incomplete understanding of the complex physical and chemical properties related to mixing states. In this paper, we summarize the recent progress in measurement and modeling studies on the BC mixing state and their effects on optical properties. Laboratory and field-based observations have shown that the transformation of a mixing state from a highly fractal nature to a more compact shape exhibits a decrease in electric mobility diameter but an increase in fractal dimension and effective density. Meanwhile, the transition behavior is also obviously influenced by emission source which can determine the components of BC mixtures. Based on the empirically determined parameters, accurate numerical modeling shows great capability on calculating BC optical properties. However, considering the significant uncertainties related to BC microphysical properties, proper parameterization considering realistic BC aggregates and coating fraction can help to understand the progress from an externally to internally mixed state.
اظهر المزيد [+] اقل [-]Atmospheric Volatile Organic Compounds (VOCs) in China: a Review النص الكامل
2020
Mozaffar, Ahsan | Zhang, Yan-Lin
PURPOSE OF REVIEW: The purpose of this review is to summarize the current understandings of atmospheric VOC characteristics in China and put forward the methodological drawbacks of the VOC measurement that need to be resolved and the research gaps that need to be filled. RECENT FINDINGS: Whereas in recent investigations in the North China Plain (NCP) a reduction (20–66%) in total VOC concentration is noticed compared with the ones published before 2015, an increase (13–127%) is observed for the Yangtze River Delta (YRD) region. Aromatics and oxygenated VOCs are frequently appearing as the most abundant VOC group in recent investigations. Industry-related VOC sources are more dominant in the YRD regions while vehicle-related sources are more influential in the NCP, Central China, and Pearl River Delta regions. Benzene, 1,3,5-trimethylbenzene, ethylbenzene, naphthalene, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, chloroform, carbon tetrachloride, and 1,2-dibromoethane pose carcinogenic risk to exposed population in China and the most risk-prone areas are affected by the petrochemical industry, biomass burning, waste management, and vehicle emissions. Formaldehyde and toluene have relatively high concentrations among the different indoor VOCs observed and their concentrations noticed to be exceeded the national air quality standard. More investigations have to be performed on rarely studied health risk assessment of VOCs and characterization of indoor VOCs. BVOC studies are rarely conducted in China, which has to be performed on common plant species, different forest, and agricultural crops. VOC characterization in forest fire smokes and more process-specific emission characteristics in common industries need to be conducted.
اظهر المزيد [+] اقل [-]Organochlorine pesticides (HCH and DDT) in blubber of spotted seals (Phoca largha) from the western Sea of Japan النص الكامل
2020
Trukhin, Alexey M. | Boyarova, Margarita D.
In 2014–2019, a total of 31 blubber samples were collected from spotted seals (Phoca largha) in the western Sea of Japan. The samples were analyzed by gas chromatography to determine level of organochlorine pesticides (OCPs). The concentration of hexachlorocyclohexane and its isomers (∑HCH) ranged from 389 to 50,070 ng/g lipid weght; the concentration of dichlorodiphenyltrichloroethane and its metabolites (∑DDT), ranged from 62,720 to 1,110,930 ng/g lipid wt. Transfer of HCH and DDT from mother to pup during pregnancy and lactation was documented. The OCP concentration in blubber of spotted seals from the western Sea of Japan is one to two orders of magnitude higher than in spotted seals inhabiting waters off the Japan coast. Organochlorines detected in the western Sea of Japan likely come from some countries of Southeast Asia still using OCPs in the agriculture sector.
اظهر المزيد [+] اقل [-]Geo-environmental assessment of heavy metals in the bottom sediments of the Southern Corniche of Jeddah, Saudi Arabia النص الكامل
2020
Bantan, Rashad A. | Al-Dubai, Talha A. | Al-Zubieri, Aaid G.
The Southern Corniche of Jeddah (SCJ) is located on the centre of the eastern Red Sea coast, Saudi Arabia and is increasingly affected by many anthropogenic activities, making it vulnerable to pollution. Sixty-three sediments and water samples were examined in regard to environmental parameters (temperature, salinity, dissolved oxygen (DO) and pH), grain size, organic matter (OM) and carbonate content and metals concentrations (Fe, Mn, Cu, Pb, Cr, Zn, Ni, and Co) in order to assess the level of contamination in SCJ's bottom sediment. The results showed that the highest concentrations of heavy metals in the shoreline and Lagoon areas are mainly due to the influx of domestic and industrial wastewater into the area where they were correlated with mud, OM, salinity and pH. The contamination factor (CF) for Fe and Co in the bottom sediments exhibited higher values than the threshold 3 value, particularly in the Lagoon and Al-Budhai area. The pollution load index (PLI) values of sediment samples could be classified as contaminated samples, especially in the nearshore samples indicating an increase of metals accumulation with decreasing distance from the source area. PCA has shown that Fe and Mn are positively correlated with all heavy metals, probably due to their high adsorption capacity in the presence of DO. The metals were Normalized with Fe, it was found that the bottom sediments of the SCJ could be reported as metal contaminated and mainly affected by natural and human sources.
اظهر المزيد [+] اقل [-]