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النتائج 481 - 490 من 1,545
Anthropogenic “Litter” and macrophyte detritus in the deep Northern Gulf of Mexico النص الكامل
2012
Wei, Chih-Lin | Rowe, Gilbert T. | Nunnally, Clifton C. | Wicksten, Mary K.
A deep-sea trawl survey of the Northern Gulf of Mexico has documented the abundance and diversity of human-generated litter and natural detrital plant material, from the outer margin of the continental shelf out to the Sigsbee abyssal plain. Plastics were the most frequently encountered type of material. Litter and debris were encountered more frequently in the eastern than in the western GoM. Land-derived plant material was located primarily within the head of the Mississippi Canyon, whereas ocean-derived plant material was spread evenly throughout the NE GoM. Human discards were principally from ships offshore. Some of the material was contained in metal cans that sank to the sea floor, probably in order to conform to international agreements that prohibit disposal of toxic material and plastics. The Mississippi Canyon was a focal point for litter, perhaps due to topography, currents or proximity to shipping lanes.
اظهر المزيد [+] اقل [-]Heavy metals contamination levels at the Coast of Aliağa (Turkey) ship recycling zone النص الكامل
2012
Neşer, Gökdeniz | Kontas, Aynur | Ünsalan, Deniz | Uluturhan, Esin | Altay, Oya | Darılmaz, Enis | Küçüksezgin, Filiz | Tekoğul, Nermin | Yercan, Funda
Aliağa Bay is one of the most important maritime zones of Turkey where shipping activity, shipbreaking industry, steel works and petrochemical complexes exist together. Concentrations of heavy metals and organic carbon in sediment of the Aliağa Bay were investigated to evaluate an environmental risk assessment from metals contamination in 2009–2010. Comparison of the metal concentrations with average shale and Mediterranean background levels revealed that most of the samples from the Aliağa were polluted with Hg, Cd, Pb, Cr, Cu, Zn, Mn and Ni. It was found that Hg, Pb, Cu, Zn and Ni levels in Aliağa Bay exceeded the PEL values. Sediments, contaminated with Pb, Cr, Cu, Zn and Ni were considered as heavily polluted per the SQG.
اظهر المزيد [+] اقل [-]An empirical model of water quality for use in rapid management strategy evaluation in Southeast Queensland, Australia النص الكامل
2012
de la Mare, William | Ellis, Nick | Pascual, Ricardo | Tickell, Sharon
Simulation models have been widely adopted in fisheries for management strategy evaluation (MSE). However, in catchment management of water quality, MSE is hampered by the complexity of both decision space and the hydrological process models. Empirical models based on monitoring data provide a feasible alternative to process models; they run much faster and, by conditioning on data, they can simulate realistic responses to management actions. Using 10years of water quality indicators from Queensland, Australia, we built an empirical model suitable for rapid MSE that reproduces the water quality variables’ mean and covariance structure, adjusts the expected indicators through local management effects, and propagates effects downstream by capturing inter-site regression relationships. Empirical models enable managers to search the space of possible strategies using rapid assessment. They provide not only realistic responses in water quality indicators but also variability in those indicators, allowing managers to assess strategies in an uncertain world.
اظهر المزيد [+] اقل [-]Benthic recovery after fish farming cessation: A “beyond-BACI” approach النص الكامل
2012
Aguado-Giménez, F. | Piedecausa, M.A. | Gutiérrez, J.M. | García-Charton, J.A. | Belmonte, A. | García-García, B.
The development of a benthic environment after fish-farming cessation was examined. To ascertain whether recovery occurred, several abiotic (granulometry, acid-volatile sulfides, total phosphorus and redox potential) and biotic (polychaete abundance) variables were monitored using a “beyond-BACI” approach. Before the cessation of farming, the geochemical conditions and polychaete assemblages differed among the impacted and control sites. After cessation, an improvement of the geochemical conditions was achieved. A significant tendency toward a recovery of the polychaete assemblage in the impacted area was observed, but significant differences still remained compared with the control sites. The acid-volatile sulfide level was responsible for these differences. The abundance of polychaete families associated with organically enriched sediments diminished at the impacted site after cessation, whereas the abundance of some sensitive and omnivorous families increased. The “beyond-BACI” approach provided a wider framework than other approaches, enabling us to differentiate the natural variability from those changes induced by the fish farm and farming cessation.
اظهر المزيد [+] اقل [-]Long term monitoring of photosystem II herbicides – Correlation with remotely sensed freshwater extent to monitor changes in the quality of water entering the Great Barrier Reef, Australia النص الكامل
2012
Kennedy, Karen | Schroeder, Thomas | Shaw, Melanie | Haynes, David | Lewis, Stephen | Bentley, Christie | Paxman, Chris | Carter, S. (Steve) | Brando, Vittorio E. | Bartkow, Michael | Hearn, Laurence | Mueller, Jochen F.
Photosystem II (PSII) herbicides are used in large quantities on agricultural lands adjoining the Great Barrier Reef (GBR). Routine monitoring at 14 sites in inshore waters of the GBR using passive sampling techniques detected diuron (32–94% of sampling periods) at maximum concentrations of 1.7–430ngL⁻¹ in the relatively pristine Cape York Region to the Mackay Whitsunday Region, respectively. A PSII herbicide equivalent (PSII-HEq) index developed as an indicator for reporting was dominated by diuron (average contribution 89%) and typically increased during the wet season. The maximum PSII-HEq indicates the potential for photosynthetic inhibition of diatoms, seagrass and coral-symbionts. PSII herbicides were significantly positively correlated with remotely sensed coloured dissolved organic matter, a proxy for freshwater extent. Combining these methods provides for the first time the potential to cost-effectively monitor improvements in water quality entering the GBR with respect to exposure to PSII herbicides.
اظهر المزيد [+] اقل [-]CYP4 mRNA expression in marine polychaete Perinereis aibuhitensis in response to petroleum hydrocarbon and deltamethrin النص الكامل
2012
Chen, Xue | Zhou, Yibing | Yang, Dazuo | Zhao, Huan | Wang, Lili | Yuan, Xiutang
A CYP4 cDNA was cloned and characterized to identify the relationship between persistent organic pollutants and stress response in marine polychaete Perinereis aibuhitensis. The full length of PaCYP4 cDNA is 1857bp and encodes 481 amino acids. The deduced amino acid sequence showed 73% identity with CYP4BB1 from polychaete Nereis virens and shared high homology to other known CYP4 sequences. The expression level of PaCYP4 under petroleum hydrocarbon (PH) and deltamethrin (DM) exposure was detected using Real-time PCR. PH and combined toxicity treatments elevated the mRNA level of PaCYP4 in a dose- and time-dependent manner. The mRNA transcripts of PaCYP4 increased at the beginning of DM exposure and then eventually decreased, and the expression level of PaCYP4 down-regulated with increasing concentration of DM. CYP4 in P. aibuhitensis plays an important role in the metabolism of petroleum hydrocarbon and organochlorine pesticide.
اظهر المزيد [+] اقل [-]Sedimentary records of metal contamination and eutrophication in Jinhae-Masan Bay, Korea النص الكامل
2012
Lim, Dhong-il | Jung, Hoi Soo | Kim, Kyung Tae | Shin, Hyeon Ho | Jung, Seung Won
Historical environmental pollution in a semi-enclosed coastal bay was investigated using high-resolution sedimentary records for Cₒᵣg, Nₜₒₜ, CaCO₃, δ¹³C, and δ¹⁵N signatures, and trace metals. A temporal increase in organic matter might have been attributable to enhanced primary marine productivity, presumably caused by increased anthropogenic nutrient inputs in the semi-enclosed, eutrophic system. Metal accumulation occurred in three stages: a preindustrial stage before the 1930s with natural concentrations of metals, an industrialization stage (1940s–1970s) with the highest concentrations, and a postindustrial stage (post 1970s) with stable or decreasing concentrations. However, Hg exhibited a different accumulation history, with concentrations increasing in the early 1900s and accelerating after the 1920s, probably in response to coal burning.
اظهر المزيد [+] اقل [-]Regional assessment of PAHs contamination in SE Brazil using brown mussels (Perna perna Linnaeus 1758) النص الكامل
2012
Yoshimine, Renato V. | Carreira, Renato S. | Scofield, Arthur L. | Wagener, Angela L.R.
Cultured and native brown mussels (Perna perna Linnaeus 1758) were used to evaluate the contamination by PAHs in the SE Brazilian coastal zone. Mean concentrations of total PAH (38 parental and alkylated compounds) and cluster analysis revealed that: (i) mussel farms (32.7–70.1ngg⁻¹) are located in uncontaminated areas; (ii) coastal rockyshore areas (89.7±25.8ngg⁻¹) have low level of contamination; and (iii) the Guanabara Bay (760.9±456.3ngg⁻¹) is chronically contaminated by hydrocarbons, which is consistent with previous results. PAH profiles and diagnostic ratios suggested mixed petrogenic and pyrolitic sources for group (ii) and petrogenic sources for group (iii). The levels of PAH in the cultured and native mussels are below threshold values for safe food, even in Guanabara Bay, and thus in such cases other contaminants and pathogens should be considered in order to evaluate the quality of shellfish for human consumption.
اظهر المزيد [+] اقل [-]Persistent organic pollutants in the endangered Hawaiian monk seal (Monachus schauinslandi) from the main Hawaiian Islands النص الكامل
2012
Bohlander, Jessica | Boyd, Daryle | Ylitalo, Gina M. | Littnan, Charles | Pearce, R. (Ronald)
Little is known about levels or effects of persistent organic pollutants (POPs) in Hawaiian monk seals (HMS) from the main Hawaiian Islands (MHI) subpopulation. This study examined concentrations of a large suite of POPs in blubber and serum of juvenile and adult HMS from the MHI. Adult females have the lowest blubber levels of most POPs, whereas adult males have highest levels. POPs in serum were significantly different in adult males compared with adult females for chlordanes and summed dichlorodiphenyltrichloroethanes (DDTs). Lipid-normalized concentrations of chlordanes, DDTs, polychlorinated biphenyls, and mirex in paired blubber and serum samples were significantly correlated. Contaminant levels from the MHI were at similar or lower levels than those from remote Northwestern Hawaiian Island populations. Determining initial ranges of POPs is an important step towards assessing one of the many potential health threats to this critically endangered species.
اظهر المزيد [+] اقل [-]Twenty years of Belgian North Sea aerial surveillance: A quantitative analysis of results confirms effectiveness of international oil pollution legislation النص الكامل
2012
Lagring, Ruth | Degraer, Steven | de Montpellier, Géraldine | Jacques, Thierry | Van Roy, Ward | Schallier, Ronny
Over the years many policy measures have been taken to prevent illegal oil discharges from ships, like the MARPOL 73/78 Convention (1983) and the Bonn Agreement (1969/1983). However, the number of discharges remained high, leading to chronic oiling of seabirds and sensitive coastlines, therefore further measures were taken. The aim of this study is to quantify the effectiveness of two key legislative regulations: the IMO-designation of the North Sea as MARPOL Special Area which took effect in 1999, and the adoption of the EU Directive on Port Reception Facilities in 2000. Under study is the heavily navigated Belgian Surveillance Area, monitored since 1991, characterised by shallow waters with ecologically important sandbanks. The aerial surveillance data from 1991 to 2010 show a stepwise decrease in ship-source oil pollution. Three time periods can be distinguished with two turning points coinciding with the actual implementation of these key legislative measures, confirming their effectiveness.
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