Refinar búsqueda
Resultados 1491-1500 de 4,309
Taiwanese marine microbenthic algal communities remain similar yet chlorophyll a concentrations rise in mesocosms with elevated CO2 and temperature Texto completo
2017
Tew, K.S. | Siao, Y.J. | Liu, P.J. | Lo, W.T. | Meng, P.J.
The effects of increasing CO2 concentrations and temperature on microalgal assemblages were examined in Taiwan using mesocosms that simulate coral reef ecosystem. We assessed changes in abundance and diversity of benthic algae grown at 25°C and 28°C, under ambient (~400μatm) and at high CO2 conditions (800–1000μatm). Total alkalinity, pCO2, and the aragonite saturation state, were all significantly different between control and high CO2 treatments in both temperature treatments. Chl a concentration increased significantly in CO2-treated groups at 25°C, but benthic microalgal abundance was not significantly different. The number of microalgal species and the microalgal community structure did not differ between control and CO2-treated groups at both temperatures. Our results suggest that increasing CO2 may boost benthic microalgal primary productivity if sufficient nutrients are available, although site-specific responses are difficult to predict.
Mostrar más [+] Menos [-]Nano-Particle-Mediated Wastewater Treatment: a Review Texto completo
2017
Ghosh, Ankita | Nayak, Ashish Kumar | Pal, Anjali
Nowadays, due to increase in worldwide population and rapid urbanization, water demand in the region is increasing fast while water quality is deteriorating. The physical, chemical, and biological characteristics are changing in a fast way due to the accumulation of contaminants such as heavy metals, synthetic dyes, and organic and inorganic materials. This makes the water harmful for the biotic and abiotic components of the ecosystem. Various noble approaches have been employed by the researchers in order to replace the traditional wastewater treatment methods. In this regard, nano-technology has occupied a central position in the areas of research. The term “nano-technology” is a branch of science which acknowledges the manipulation of materials at nano-scale. These materials may have large specific surface area, high reactivity, degree of functionalization, size-dependent properties, etc., which make them suitable for execution in water purification and wastewater treatment. This paper briefly reviews the current advances and application of nano-materials for wastewater treatment. Here, various types of nano-materials such as carbon nano-tubes, MnO₂ nano-sheets, graphene composites, metal oxides, antimicrobial nano-materials, and photocatalysts, which are employed in the field of wastewater treatment, have been dissertated.
Mostrar más [+] Menos [-]Evaluation of Soil Function Following Remediation of Petroleum Hydrocarbons—a Review of Current Remediation Techniques Texto completo
2017
O’Brien, Peter L. | DeSutter, Thomas M. | Casey, Francis X. M. | Wick, Abbey F. | Khan, Eakalak
PURPOSE OF REVIEW: Management of lands contaminated by petroleum hydrocarbons (PHC) continues to evolve, as project goals may be shifting from contaminant reduction to ecosystem restoration. Restoring soil function is vital to overall ecosystem recovery, as soils perform numerous processes that are inhibited by PHC contamination. The purpose of this review is to summarize the effects of various remediation strategies on soil properties and evaluate how those effects relate to soil functions. RECENT FINDINGS: All remediation techniques alter soil function, and the extent of alteration is based on project-specific operational parameters. Broadly, most techniques alter soil organic matter (SOM) content and soil pH, which are important variables associated with many soil processes. Additionally, recent technological advances have made the characterization of soil microbial communities and activities more accessible, so the field continues to gain knowledge on how remediation strategies affect soil microorganisms that are vital in nutrient cycling and waste management. This review identified soil properties and functions that are likely to be affected by each strategy and that should be monitored following successful remediation. The extent of changes in soil properties is dictated by specific implementation of remediation methods, so general comparisons between methods may not be appropriate. While important variables like SOM and pH are valuable indicators of soil function, the dynamic relationships between all soil properties should not be overlooked following soil remediation. Thus, future research on soil remediation should strive to assess changes in how soils function, in addition to contaminant removal efficiency.
Mostrar más [+] Menos [-]Citizen scientists reveal: Marine litter pollutes Arctic beaches and affects wild life Texto completo
2017
Bergmann, Melanie | Lutz, Birgit | Tekman, Mine B. | Gutow, Lars
Citizen scientists reveal: Marine litter pollutes Arctic beaches and affects wild life Texto completo
2017
Bergmann, Melanie | Lutz, Birgit | Tekman, Mine B. | Gutow, Lars
Recent data indicate accumulation areas of marine litter in Arctic waters and significant increases over time. Beaches on remote Arctic islands may be sinks for marine litter and reflect pollution levels of the surrounding waters particularly well. We provide the first quantitative data from surveys carried out by citizen scientists on six beaches of Svalbard. Litter quantities recorded by cruise tourists varied from 9–524gm−2 and were similar to those from densely populated areas. Plastics accounted for >80% of the overall litter, most of which originated from fisheries. Photographs provided by citizens show deleterious effects of beach litter on Arctic wildlife, which is already under strong pressure from global climate change. Our study highlights the potential of citizen scientists to provide scientifically valuable data on the pollution of sensitive remote ecosystems. The results stress once more that current legislative frameworks are insufficient to tackle the pollution of Arctic ecosystems.
Mostrar más [+] Menos [-]Marine Litter quantities on six Beaches of northern Svalbard in 2016 determined by citizen scientists Texto completo
2017
Bergmann, Melanie | Gutow, Lars
Beaches on remote Arctic islands may be sinks for marine litter and reflect pollution levels of the surrounding waters particularly well. We provide the first quantitative data from surveys carried out by citizen scientists on six beaches of northern Svalbard. Litter quantities recorded by cruise tourists varied from 9-524 g m-2 and were similar to those from densely populated areas. Plastics accounted for >80% of the overall litter, most of which originated from fisheries. Our study highlights the potential of citizen scientists to provide scientifically valuable data on the pollution of sensitive remote ecosystems. The results stress once more that current legislative frameworks are insufficient to tackle the pollution of Arctic ecosystems.
Mostrar más [+] Menos [-]Distinguishing globally-driven changes from regional- and local-scale impacts: The case for long-term and broad-scale studies of recovery from pollution Texto completo
2017
Hawkins, S.J. | Evans, A.J. | Mieszkowska, N. | Adams, L.C. | Bray, S. | Burrows, M.T. | Firth, L.B. | Genner, M.J. | Leung, K.M.Y. | Moore, P.J. | Pack, K. | Schuster, H. | Sims, D.W. | Whittington, M. | Southward, E.C.
Marine ecosystems are subject to anthropogenic change at global, regional and local scales. Global drivers interact with regional- and local-scale impacts of both a chronic and acute nature. Natural fluctuations and those driven by climate change need to be understood to diagnose local- and regional-scale impacts, and to inform assessments of recovery. Three case studies are used to illustrate the need for long-term studies: (i) separation of the influence of fishing pressure from climate change on bottom fish in the English Channel; (ii) recovery of rocky shore assemblages from the Torrey Canyon oil spill in the southwest of England; (iii) interaction of climate change and chronic Tributyltin pollution affecting recovery of rocky shore populations following the Torrey Canyon oil spill. We emphasize that “baselines” or “reference states” are better viewed as envelopes that are dependent on the time window of observation. Recommendations are made for adaptive management in a rapidly changing world.
Mostrar más [+] Menos [-]Comparison of phytoremediation potential capacity of Spartina densiflora and Sarcocornia perennis for metal polluted soils Texto completo
2017
Idaszkin, Yanina L. | Lancelotti, Julio L. | Pollicelli, María P. | Marcovecchio, Jorge E. | Bouza, Pablo J.
Phytoremediation is considered the most appropriate technique to restore metal polluted soil, given its low cost, high efficiency and low environmental impact. Spartina densiflora and Sarcocornia perennis are perennial halophytes growing under similar environmental conditions in San Antonio marsh (Patagonia Argentina), therefore it is interesting to compare their phytoremediation potential capacity. To this end, we compared concentrations of Pb, Zn, Cu, and Fe in soils and in below- and above-ground structures of S. perennis and S. densiflora. It was concluded that both species are able to inhabit Pb, Zn, and Cu polluted soils. Although Sarcocornia translocated more metals to the aerial structures than Spartina, both species translocated only when they were growing in soils with low metal concentrations. It seems that the plants translocate only a certain proportion of the metal contained in the soil. These results suggest that both species could be considered candidates to phytostabilize these metals in polluted soils.
Mostrar más [+] Menos [-]Cryptosporidium species from common edible bivalves in Manila Bay, Philippines Texto completo
2017
Pagoso, Edison Jay A. | Rivera, Windell L.
Manila Bay is one of the major propagation sites of edible bivalves in the Philippines. Studies have shown that bivalves might be contaminated with human pathogens like the protozoan parasite Cryptosporidium, one of the major causes of gastroenteritis in the world. In this study, Cryptosporidium from four species of edible bivalves were isolated using a combination of sucrose flotation and immunomagnetic separation. Using direct fluorescent antibody test, Cryptosporidium oocysts were found in 67 out of 144 samples collected. DNA sequence analysis of the 18S rRNA gene of the isolates detected C. parvum and C. hominis (major causes of human cryptosporidiosis) and C. meleagridis (causes infection in avian species). Analysis of the 60kDa glycoprotein gene further confirmed the genotypes of the Cryptosporidium isolates. This study is the first to provide baseline information on Cryptosporidium contamination of Manila Bay where bivalves are commonly cultured.
Mostrar más [+] Menos [-]Uncovering hidden heterogeneity: Geo-statistical models illuminate the fine scale effects of boating infrastructure on sediment characteristics and contaminants Texto completo
2017
Hedge, L.H. | Dafforn, K.A. | Simpson, S.L. | Johnston, E.L.
Infrastructure associated with coastal communities is likely to not only directly displace natural systems, but also leave environmental footprints' that stretch over multiple scales. Some coastal infrastructure will, there- fore, generate a hidden layer of habitat heterogeneity in sediment systems that is not immediately observable in classical impact assessment frameworks. We examine the hidden heterogeneity associated with one of the most ubiquitous coastal modifications; dense swing moorings fields. Using a model based geo-statistical framework we highlight the variation in sedimentology throughout mooring fields and reference locations. Moorings were correlated with patches of sediment with larger particle sizes, and associated metal(loid) concentrations in these patches were depressed. Our work highlights two important ideas i) mooring fields create a mosaic of habitat in which contamination decreases and grain sizes increase close to moorings, and ii) model- based frameworks provide an information rich, easy-to-interpret way to communicate complex analyses to stakeholders.
Mostrar más [+] Menos [-]Newly discovered reefs in the southern Abrolhos Bank, Brazil: Anthropogenic impacts and urgent conservation needs Texto completo
2017
Mazzei, E.F. | Bertoncini, A.A. | Pinheiro, H.T. | Machado, L.F. | Vilar, C.C. | Guabiroba, H.C. | Costa, T.J.F. | Bueno, L.S. | Santos, L.N. | Francini-Filho, R.B. | Hostim-Silva, M. | Joyeux, J.-C.
The Abrolhos Bank is an area of high ecological, socio-economic importance and harbour the richest and most-extensive coral reefs in the South Atlantic. Here we report the discovery of shallow (12–25m depth) reef complex with ten large biogenic structures, intermediate between the typical mushroom-shaped pinnacles of the northern Abrolhos Bank (17°–18° S) and the small patch reefs found on the central/southern coast of the Espírito Santo State (19°–20° S). The newly discovered reefs harbour a relatively rich and abundant reef community, with 73 fish and 14 benthic cnidarian species, including endangered and commercially important ones. We discuss on urgent needs of properly mapping and understanding the ecological functioning of this reef system. Information provided here is a baseline for future impact evaluations, particularly considering the recent worst environmental disaster of Brazil from a dam collapse in Doce river that affected the region.
Mostrar más [+] Menos [-]Extremely high sulfate reduction, sediment oxygen demand and benthic nutrient flux associated with a large-scale artificial dyke and its implication to benthic-pelagic coupling in the Yeongsan River estuary, Yellow Sea Texto completo
2017
Kim, Sŭng-han | Lee, Jae-seong | Hyun, Jung-Ho
We investigated environmental impact of large-scale dyke on the sediment geochemistry, sulfate reduction rates (SRRs), sediment oxygen demand (SOD) and potential contribution of benthic nutrient flux (BNF) to primary production in the Yeongsan River estuary, Yellow Sea. The sediment near the dyke (YE1) with high organic carbon (Corg) content (>4%, dry wt.) was characterized by extremely high SOD (327mmolm−2d−1) and SRRs (91–140mmolm−2d−1). The sulfate reduction accounted for 73% of Corg oxidation, and was responsible for strikingly high concentrations of NH4+ (7.7mM), PO43− (67μM) and HS− (487μM) in pore water. The BNF at YE1 accounted for approximately 200% of N and P required for primary production in the water column. The results present one of the most extreme cases that the construction of an artificial dyke may have profound impacts on the biogeochemical and ecological processes in coastal ecosystems.
Mostrar más [+] Menos [-]