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Resultados 1111-1120 de 4,044
Water flux management and phytoplankton communities in a Mediterranean coastal lagoon. Part I: How to promote dinoflagellate dominance? Texto completo
2016
Garrido, M. | Cecchi, P. | Collos, Y. | Agostini, S. | Pasqualini, V.
The Biguglia lagoon is a shallow Mediterranean coastal ecosystem where eutrophication is increasing for years. A channel supplying freshwater was cleared in 2009 to enhance lagoon water circulation and alleviate dystrophic crises. Monthly monitoring was started in 2010 to document the impacts of this action on abiotic characteristics and phytoplankton communities. Three stations were surveyed (by microscopy and HPLC). Evidence suggests that this operation had an unexpected outcome. Salinity footprints indicated the succession of three main hydrological sequences that depended on rainfall and circulation pattern. Diatoms and dinoflagellates dominated the first sequence, characterized by heavy rainfall, while Prorocentrum minimum became progressively the dominant species in the second period (increasing salinities) with extensive bloom over the whole lagoon (5.93×10-5cells·L−1) during the third period. These phytoplankton successions and community structures underline the risk of pernicious effects arising from remediation efforts, in the present case based on increasing freshwater inputs.
Mostrar más [+] Menos [-]Paralytic shellfish toxin production by the dinoflagellate Alexandrium pacificum (Chinhae Bay, Korea) in axenic, nutrient-limited chemostat cultures and nutrient-enriched batch cultures Texto completo
2016
Han, Myungsoo | Lee, Haeok | Anderson, Donald M. | Kim, Baikho
Blooms of Alexandrium pacificum (formerly Alexandrium tamarense) are common in Chinhae Bay (Korea), presumably linked to anthropogenic eutrophication. Here we examine PSP toxin content and composition in axenic chemostat and batch cultures of A. pacificum using growth conditions that differed according to dilution rate, nutrient limitations, and enrichments. Phosphate (P)-limited cells in chemostat cultures had higher toxin content and a toxin composition that differed from that of nitrogen (N)-limited cells at the highest growth rates. Therefore, toxin composition changes do occur in axenic cultures of A. pacificum following extended growth under steady state conditions. In nutrient-limited batch cultures that received N and P enrichment, the N-enriched cultures showed a more diverse toxin profile than the P-enriched cells; the toxin content of N-enriched cells was lower than in the P-enriched cultures. We infer the following order for the biosynthesis of individual toxins: C1, C2>GTX3>GTX1>neoSTX.
Mostrar más [+] Menos [-]Assessment of metal enrichment and their bioavailability in sediment and bioaccumulation by mangrove plant pneumatophores in a tropical (Zuari) estuary, west coast of India Texto completo
2016
Noronha-D'Mello, Cheryl A. | Nayak, G.N.
Sediment collected from the estuarine mangroves of the Zuari estuary and Cumbharjua canal were analyzed to assess the concentration, contamination and bioavailability of metals. Mangrove pneumatophores were also analyzed to understand the metal bioaccumulation in mangrove plants. The results indicated the variation of metal concentrations in sediment along the estuary was attributed to changing hydrodynamic conditions, type of sediment and metal sources. Further, speciation studies revealed that Fe, Cr, Co, Ni, Cu and Zn were mainly of lithogenic origin and less bioavailable while high Mn content in the sediment raised concerns over its potential mobility, bioavailability and subsequent toxicity. The mangrove plants exhibited difference in metal accumulation due to variations in sediment parameters and metal availability, in addition to difference in plant species and tissue physiology that affect metal uptake. Moreover, the mangrove plants reflected the quality of the underlying sediment and can be used as a potential bio-indicator tool.
Mostrar más [+] Menos [-]Comparison of heavy metal contamination during the last decade along the coastal sediment of Pakistan: Multiple pollution indices approach Texto completo
2016
Saher, Noor Us | Siddiqui, Asmat Saleem
Heavy metals concentrations (Fe, Cu, Zn, Ni, Cr, Co, Pb, and Cd) were scrutinized during two monitoring years (2001 and 2011) in the coastal sediment of Pakistan. The status of metal contamination in coastal sediment was interpreted using sediment quality guidelines, and single and combined metal pollution indices. Ni, Cr, and Cd were recognized for their significant (p<0.05) intensification in the sediment during the last decade. Sediment quality guidelines recognized the frequent adverse biological effect of Ni and the occasional adverse biological effect of Cu, Cr, Pb and Cd. Single metal pollution indices (Igeo, EF, CF, and ER) revealed that sediment pollution is predominantly caused by Pb and Cd. Low to moderate contamination was appraised along the coast by multi-metal pollution indices (CD and PERI). Correlation study specifies that heavy metals were presented diverse affiliations and carriers for distribution in the sediment during the last decade.
Mostrar más [+] Menos [-]First comprehensive screening of lipophilic organic contaminants in surface waters of the megacity Jakarta, Indonesia Texto completo
2016
Dsikowitzky, L. | Sträter, M. | Dwiyitno, | Ariyani, F. | Irianto, H.E. | Schwarzbauer, J.
Jakarta is an Indonesian coastal megacity with over 10 million inhabitants. The rivers flowing through the city receive enormous amounts of untreated wastewaters and discharge their pollutant loads into Jakarta Bay. We utilized a screening approach to identify those site-specific compounds that represent the major contamination of the cities' water resources, and detected a total number of 71 organic contaminants in Jakarta river water samples. Especially contaminants originating from municipal wastewater discharges were detected in high concentrations, including flame retardants, personal care products and pharmaceutical drugs.A flame retardant, a synthetic fragrance and caffeine were used as marker compounds to trace the riverine transport of municipal wastewaters into Jakarta Bay. These markers are also appropriate to trace municipal wastewater discharges to other tropical coastal ecosystems. This application is in particular useful to evaluate wastewater inputs from land-based sources to habitats which are sensitive to changing water quality, like coral reefs.
Mostrar más [+] Menos [-]PCDD/Fs in soil and air and their possible sources in the vicinity of municipal solid waste incinerators in northeastern China Texto completo
2016
Meng, Bo | Ma, Wanli | Liu, Li-Yan | Zhu, Ning-Zheng | Song, Wei-Wei | Lo, Ching Yee | Li, James | Kannan, Kurunthachalam | Li, Yi-Fan
Fly ash, flue gas, ambient air, and soil samples were collected to investigate concentrations, profiles, gas–particle partitioning, and air–soil exchange of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the vicinity of two municipal solid waste incinerators (MSWIs) in Harbin in northeastern China. The PCDD/F concentrations were 11 600–12 300 pg g−1 (597–615 pg WHO-TEQ g−1) in fly ash and 873–1120 fg m−3 (51.2–61.9 fg WHO-TEQ m−3) in air. The results of gas–particle partitioning possibly indicated the equilibrium state of PCDD/F during sampling period. For soil samples, both Enzyme-linked immuno-sorbent assay (ELISA) and high-resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) were used. Significant correlations between the results from these two methods indicated that both methods are useful for PCDD/Fs analysis in soil. PCDD/Fs concentrations in soil samples ranged from 17.2 to 157 pg g−1 (0.59–8.81 pg WHO-TEQ g−1). Both Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) suggested the sources of the emission from MSWIs and the historical emission from a petroleum refinery to PCDD/Fs in adjacent soils. The air–soil exchange analysis showed a net flux of PCDD/F from air to soil at all soil-sampling sites.
Mostrar más [+] Menos [-]Bioremediation technologies for polluted seawater sampled after an oil-spill in Taranto Gulf (Italy): A comparison of biostimulation, bioaugmentation and use of a washing agent in microcosm studies Texto completo
2016
Crisafi, F. | Genovese, M. | Smedile, F. | Russo, D. | Catalfamo, M. | Yakimov, M. | Giuliano, L. | Denaro, R.
One of the main challenges of bioremediation is to define efficient protocols having a low environmental impact. We have investigated the effect of three treatments in oily-seawater after a real oil-spill occurred in the Gulf of Taranto (Italy). Biostimulation with inorganic nutrients allowed the biodegradation of the 73±2.4% of hydrocarbons, bioaugmentation with a selected hydrocarbonoclastic consortium consisting of Alcanivorax borkumensis, Alcanivorax dieselolei, Marinobacter hydrocarbonoclasticus, Cycloclasticus sp. 78-ME and Thalassolituus oleivorans degraded 79±3.2%, while the addition of nutrients and a washing agent has allowed the degradation of the 69±2.6%. On the other hand, microbial community was severely affected by the addition of the washing agent and the same product seemed to inhibit the growth of the majority of strains composing the selected consortium at the tested concentration. The use of dispersant should be accurately evaluated also considering its effect on the principal actors of biodegradation.
Mostrar más [+] Menos [-]The monetary valuation of acute respiratory illness from air pollution in Turkey Texto completo
2016
Ara, Shihomi | Tekeşin, Cem
A contingent valuation study is conducted in three locations in Turkey using a total of 1362 observations to elicit willingness to pay (WTP) to avoid the acute respiratory illness (three days of severe coughing and throat pain). This is the first research of this kind in Turkey, and also one of a few studies conducted in developing countries. Median WTPs are estimated as 65, 51, and 83 PPP-adjusted 2012 USD for Afsin-Elbistan, Kutahya-Tavsanli and Ankara, respectively. Income elasticities of WTP are derived as 0.8 for Afsin-Elbistan and tested statistically indifferent from 1.0 for Kutahya-Tavsanli, and Ankara, and are found to be greater than the cases in existing studies conducted both in developed and developing countries. We also find that 60 to 90 percent of WTP are devoted for avoiding pain and discomfort/restricted activity days, and much less weights are given for avoiding possible financial losses. As for the determinants of WTP, university graduates, those who have experienced coughing within one month, have spent out-of-pocket medical expenses and actually lost some part of their income due the last experienced minor symptoms are willing to pay more to avoid the future acute respiratory illness while women and the household using coal as the main source of home-heating are willing to pay less in one or more study areas. New air quality standard for PM10 (transition from 150 μg/m3 to 40 μg/m3 by 2019) causes the reductions in minor respiratory symptoms by 11, 8, and 4.4 per person, and the resulting welfare gains are calculated as 157 million, 123 million, and 1464 million PPP-adjusted 2012 USD for Afsin-Elbistan, Kutahya-Tavsanli and Ankara, respectively.
Mostrar más [+] Menos [-]Islands in the oil: Quantifying salt marsh shoreline erosion after the Deepwater Horizon oiling Texto completo
2016
Turner, R Eugene | McClenachan, Giovanna | Tweel, Andrew W.
Qualitative inferences and sparse bay-wide measurements suggest that shoreline erosion increased after the 2010 BP Deepwater Horizon (DWH) disaster, but quantifying the impacts has been elusive at the landscape scale. We quantified the shoreline erosion of 46 islands for before and after the DWH oil spill to determine how much shoreline was lost, if the losses were temporary, and if recovery/restoration occurred. The erosion rates at the oiled islands increased to 275% in the first six months after the oiling, were 200% of that of the unoiled islands for the first 2.5years after the oiling, and twelve times the average land loss in the deltaic plain of 0.4%y−1 from 1988 to 2011. These results support the hypothesis that oiling compromised the belowground biomass of the emergent vegetation. The islands are, in effect, sentinels of marsh stability already in decline before the oil spill.
Mostrar más [+] Menos [-]Effects of hypoxia caused by mussel farming on benthic foraminifera in semi-closed Gamak Bay, South Korea Texto completo
2016
Lee, Yeon Gyu | Jeong, Da Un | Lee, Jung Sick | Choi, Yang Ho | Lee, Moon-ok
Seawater monitoring and geochemical and benthic foraminiferal analysis of sediments were conducted to identify the effects of hypoxia created by a mussel farm on benthic foraminifera in a semi-closed bay. Extremely polluted reductive conditions with a high content of organic matter (OM) at >12.0% and oxygen minimum zones (OMZs) with dissolved oxygen (DO) <0.4mg∙L–1 were formed below the mussel farm in the northwest area of Gamak Bay, and gradually diffused toward the south. Highly similar patterns of variation were observed in species diversity, abundance frequency, and benthic foraminiferal assemblage distributed from Elphidium subarcticum–Ammonia beccarii in the northwest area through E. subarcticum–A. beccarii–Trochammina hadai, E. subarcticum–A. beccarii–Elphidiumclavatum, and E. clavatum–Ammonia ketienziensis in the southern area. These phenomena were caused by hydrodynamics in the current water mass. It was thought that E. subarcticum is a bioindicator of organic pollution caused by the mussel farm.
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