Уточнить поиск
Результаты 761-770 из 1,273
Persistence profile of polyaromatic hydrocarbons in shallow and deep Gulf waters and sediments: Effect of water temperature and sediment–water partitioning characteristics
2011
Tansel, B. | Fuentes, C. | Sánchez, M. | Predoi, K. | Acevedo, M.
Persistence profiles of selected polyaromatic hydrocarbons (PAHs) were analyzed depending on temperature variations in the water column and water–sediment interactions in the Gulf of Mexico. The PAHs studied include anthracene, fluoranthene, pyrene, and chrysene. The half-lives of PAHs in the deep waters (over 1000m) are about twice as long as those in the shallow areas (100–150m), and almost 2.5 times as long as those in the top layer (0–10m) of the water column. The half-lives of the PAHs in the sediments are significantly longer. Among the PAHs studied, chrysene is the most persistent in the water column, and pyrene is the most persistent in the sediments. The half-life of chrysene in the shallow and deep waters is over 2.5 and about 5years, respectively. For pyrene, the half-life in the shallow and deep sediments is about 9 and 16years, respectively.
Показать больше [+] Меньше [-]Effects of the 2003 European heatwave on the benthic community of a severe transitional ecosystem (Comacchio Saltworks, Italy)
2011
Munari, Cristina
The summer of 2003 was the warmest summer in Europe since the 16th century. Its consequences on the fauna of a transitional ecosystem were studied through biodiversity, functional and ecological indicators, from summer 2002 to winter 2005. The heatwave caused considerable changes in the benthic community structure and relative composition, persisting in 2005. Animal assemblages switched from mollusc- to annelida-dominated. Biodiversity and functional indicators captured changes in community structure and composition, proving to be powerful tools to detect responses related to global warming. Ecological indicators rendered a monotonic response oscillating between bad and poor ecological status across the study period. The resilience of mollusc biocoenosis resulted limited with respect to other taxa, posing concerns about their conservation if, as predicted, the frequency of summers as hot as that of 2003 will progressively increase to become the norm at the end of this century.
Показать больше [+] Меньше [-]Occurrence of polycyclic aromatic hydrocarbons (PAHs) in seawater from the Western Taiwan Strait, China
2011
Wu, Yu-Ling | Wang, Xin-Hong | Li, Yong-Yu | Hong, Hua-Sheng
Seawater samples (including surface water and bottom water) were collected from the Western Taiwan Strait (WTS) during June 24–25, 2009; polycyclic aromatic hydrocarbons (PAHs) in dissolved phase and particulate phase were analyzed, respectively. The results showed that the total concentrations of PAHs in the dissolved phase and particulate phase were ranged from 12.3 to 58.0ngL⁻¹, and 10.3–45.5ngL⁻¹, which showed a low-middle contamination level in the China Seas. The spatial variability of PAHs may be related to the complicated currents of WTS, especially the Min-Zhe coastal current. PAHs diagnostic ratios suggested that PAHs mainly originated from the inputs of pyrolytic (combustion) sources, which might be contributed to land-based atmospheric deposition. The particle-water partition coefficients of individual PAH showed that partitions were not correlated with suspended particulate matter content, dissolved organic carbon or salinity, similar to the Yangtze coastal area.
Показать больше [+] Меньше [-]Long-term temporal trends (1992–2008) of imposex status associated with organotin contamination in the dogwhelk Nucella lapillus along the Icelandic coast
2011
Guðmundsdóttir, Lovísa Ó | Ho, Kevin K.Y. | Lam, James C.W. | Jörundur Svavarsson, | Leung, Kenneth M.Y.
Using the dogwhelk Nucella lapillus as a biomonitor, we evaluated the organotin contamination along the Icelandic coast over nearly two decades. In 2008, adult dogwhelks collected from 30 locations were examined for imposex status. In 2009, tissue concentrations of six organotin species in dogwhelks from 16 of the 30 locations were analysed using gas chromatography–mass spectrometry. Tributyltin was the most predominant residue ranging from 2.07 to 70.38μgkg⁻¹ dw, while triphenyltin was also detected at concentrations up to 22.79μgkg⁻¹ dw. Higher total organotin concentrations and imposex indices were observed at locations near large harbours (Reykjavík and Hafnarfjörður). By comparing the current imposex results with those of previous surveys (1992–2003), we found that recovery was slow near the large harbours, but more apparent near the smaller harbours. We also observed a notable increase in imposex at several northwest sites implying incessant input of organotins.
Показать больше [+] Меньше [-]Stable isotope-guided analysis of biomagnification profiles of arsenic species in a tropical mangrove ecosystem
2011
Tu, Nguyen Phuc Cam | Agusa, Tetsuro | Ha, Nguyen Ngoc | Tuyen, Bui Cach | Tanabe, Shinsuke | Takeuchi, Ichirō
We performed stable carbon and nitrogen-guided analyses of biomagnification profiles of arsenic (As) species, including total As, lipid-soluble As, eight water-soluble As compounds (arsenobetaine (AB), arsenocholine (AC), tetramethylarsonium ion (TETRA), trimethylarsine oxide (TMAO), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenate (As[V]), and arsenite (As[III])), and non-extracted As in a tropical mangrove ecosystem in the Ba Ria Vung Tau, South Vietnam. Arsenobetaine was the predominant As species (65–96% of water-soluble As). Simple linear regression slopes of log-transformed concentrations of total As, As fractions or individual As compounds on stable nitrogen isotopic ratio (δ¹⁵N) values are regarded as indices of biomagnification. In this ecosystem, lipid-soluble As (slope, 0.130) and AB (slope, 0.108) were significantly biomagnified through the food web; total As and other water-soluble As compounds were not. To our knowledge, this is one of the first reports on biomagnification profiles of As compounds from a tropical mangrove ecosystem.
Показать больше [+] Меньше [-]Evaluation of heavy metals and arsenic speciation discharged by the industrial activity on the Tinto-Odiel estuary, SW Spain
2011
Pérez López, Rafael | Nieto, José Miguel | López-Cascajosa, M José | Díaz-Blanco, M Jesús | Sarmiento, Aguasanta M. | Oliveira, Vanesa | Sánchez-Rodas, Daniel
This study reports the annual amount of heavy metals discharged by industrial activity into the estuary of the Ría of Huelva (SW Spain). The findings showed that the discharged metals found in highest amounts were Fe (11ty⁻¹), Zn (3.4ty⁻¹) and Mo (0.88ty⁻¹). There were other metals with high pollutant charge, such as Ti (232kgy⁻¹), As (228kgy⁻¹), Ni (195kgy⁻¹), Pb (100kgy⁻¹), Cr (39kgy⁻¹) and Cd (33kgy⁻¹). These results were compared with pollutants transported via the Tinto and Odiel rivers from abandoned mining activities in the Iberian Pyrite Belt (IPB), and it was deduced that the amounts spilled exclusively by industries were less than 1% in relation to the total discharge. Hence, the treatment of residues from the IPB should be the priority goal to improve water quality in the estuary.
Показать больше [+] Меньше [-]Characterization of marine debris in North Carolina salt marshes
2011
Viehman, Shay | Vander Pluym, Jenny L. | Schellinger, Jennifer
Marine debris composition, density, abundance, and accumulation were evaluated in salt marshes in Carteret County, North Carolina seasonally between 2007 and 2009. We assessed relationships between human use patterns and debris type. Wave effects on marine debris density were examined using a GIS-based forecasting tool. We assessed the influence of site wave exposure, period, and height on debris quantity. Presence and abundance of debris were related to wave exposure, vegetation type and proximity of the strata to human population and human use patterns. Plastic pieces accounted for the majority of all debris. Small debris (0–5cm) was primarily composed of foam pieces and was frequently affiliated with natural wrack. Large debris (>100cm) was encountered in all marsh habitat types surveyed and was primarily composed of anthropogenic wood and derelict fishing gear. Marsh cleanup efforts should be targeted to specific habitat types or debris types to minimize further damage to sensitive habitats.
Показать больше [+] Меньше [-]Evaluation of the contamination of platinum in estuarine and coastal sediments (Tagus Estuary and Prodelta, Portugal)
2011
Cobelo-García, Antonio | Neira, Patricia | Mil-Homens, Mário | Caetano, Miguel
Platinum contamination in estuarine and coastal sediments has been evaluated in three cores collected from the Tagus Estuary and Prodelta shelf sediments. Elevated concentrations, up to 25-fold enrichment compared to background values, were found in the upper layers of the estuarine sediments. The degree of Pt enrichment in the estuarine sediments varied depending on the proximity to vehicular traffic sources, with a maximum concentration of 9.5ngg⁻¹. A considerable decrease of Pt concentrations with depth indicated the absence of significant contamination before the introduction of catalytic converters in automobiles. Platinum distribution in the Tagus Prodelta shelf sediment core showed no surface enrichment; instead a sub-surface maximum at the base of the mixed layer suggested the possibility of post-depositional mobility, thereby blurring the traffic-borne contamination signature in coastal sediments.
Показать больше [+] Меньше [-]Metal enrichment in beach sediments from Chennai Metropolis, SE coast of India
2011
Santhiya, G. | Lakshumanan, C. | Jonathan, M.P. | Roy, P.D. | Navarrete-Lopez, M. | Srinivasalu, S. | Uma-Maheswari, B. | Krishnakumar, P.
A survey on the Partially Extracted Trace Metals (PETMs) concentration (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) in beach sediments is reported for the first time from 57 different locations in Chennai Metropolitan City of Southeast coast of India. The concentration of PETMs suggests that they are mainly concentrated with organic matter in the crowded part of the industrial regions in the beaches from the northern part rather than the tourist beaches in the southern part of the city. The comparison on enrichment of trace metals indicates higher values of Pb, Ni in the beaches than lowest effect level (LEL) and effects range low (ERL) than the tourist beaches.
Показать больше [+] Меньше [-]Temporal and spatial biomonitoring of heavy metals in eastern Aegean coastal waters using Amphibalanus amphitrite
2011
Aydin Onen, S. | Kucuksezgin, F. | Kocak, F.
This biomonitoring study presents the spatial and temporal distributions of heavy metals in the soft tissues of a major fouling species Amphibalanus amphitrite living on hard substrate at different sites along the eastern Aegean coast. A. amphitrite has been chosen as a strong candidate for monitoring heavy metals. Sediment and seawater samples were also collected to detect their metal contents in order to gain more information on the environmental conditions and possible bioaccumulation patterns. The physico-chemical characteristics of sampling stations have been measured in order to characterize the sampling area. The order of metal concentrations in barnacles, sediment and seawater decreased in the following order Cu>Fe>Zn>Mn>Cd>Cr>Pb>Hg, Fe>Mn>Zn>Cu>Pb>Cr>Hg>Cd and Fe>Zn>Mn>Cu>Pb>Cr>Cd>Hg, respectively. These results showed that barnacles accumulate Cu in a higher degree than both sediment and seawater. Moreover, metal concentrations in barnacle have the potential for use in any future regulatory framework monitoring and eventually controlling ambient metal pollution levels.
Показать больше [+] Меньше [-]