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Novel observations of benthic enrichment in contrasting flow regimes with implications for marine farm monitoring and management Texte intégral
2013
We examine macrofaunal and physico-chemical responses to organic enrichment beneath salmon farms in contrasting flow environments, and reveal pronounced flow-related differences in the magnitude and spatial extent of effects. Total macrofaunal abundances at high flow sites were nearly an order of magnitude greater than at comparable low flow sites, representing a significant benthic biomass. These very high abundances occurred in conjunction with moderate-to-high species richness, and were evident in the absence of appreciable organic matter accumulation. Biological responses to increasing sulfide were variable; however a significant biological threshold was evident at 1500μM. Macrofaunal responses at high flow sites differed substantially from the Pearson–Rosenberg model. The atypical ecological conditions were attributed to (i) limited accumulation of fine sediments, (ii) maintenance of aerobic conditions in near-surface sediments, and (iii) an abundant food supply. Thus, enhanced resilience to organic waste at well-flushed sites appears related to both biological and physical processes.
Afficher plus [+] Moins [-]Assessing the spatial variability, level and source of organic chemical contaminants in bivalve fishing grounds on the Galician coast (NW Spain) Texte intégral
2013
Polychlorinated biphenyls, organochlorine pesticides, organotin compounds and triazines were quantified in sediments and bivalves collected in four areas on the Galician coast. One or several species were analysed at each site depending on their availability, including mussels (Mytilus galloprovincialis), cockles (Cerastoderma edule), clams (Venerupis pullastra and Ruditapes decussatus) and razor shells (Ensis siliqua). The general spatial distribution of contaminants was consistent in spite of the different sources of contamination. High inter-species variability was also observed. M. galloprovincialis and V. pullastra showed the highest levels of contaminants and intra-spatial variability, which highlights them as suitable species to be used as sentinel organisms. The area of O Burgo showed some worrisome results: PCB sediment concentrations were within the range that could cause biological effects. Also the level of heptachlor observed in V. pullastra was above limits accepted on edible seafood. Finally TBT concentration in mussels correlated with concentrations causing imposex in snails.
Afficher plus [+] Moins [-]Biodegradation of low-density polyethylene by marine bacteria from pelagic waters, Arabian Sea, India Texte intégral
2013
Harshvardhan, Kumar | Jha, Bhavanath
Sixty marine bacteria isolated from pelagic waters were screened for their ability to degrade low-density polyethylene; among them, three were positive and able to grow in a medium containing polythene as the sole carbon source. The positive isolates were identified as Kocuria palustris M16, Bacillus pumilus M27 and Bacillus subtilis H1584 based on the 16S rRNA gene sequence homology. The weight loss of polyethylene was 1%, 1.5% and 1.75% after 30days of incubation with the M16, M27 and H1584 isolates, respectively. The maximum (32%) cell surface hydrophobicity was observed in M16, followed by the H1584 and M27 isolates. The viability of the isolates growing on the polyethylene surface was confirmed using a triphenyltetrazolium chloride reduction test. The viability was also correlated with a concomitant increase in the protein density of the biomass. Polyethylene biodegradation was further confirmed by an increase in the Keto Carbonyl Bond Index, the Ester Carbonyl Bond Index and the Vinyl Bond Index, which were calculated from FT-IR spectra.
Afficher plus [+] Moins [-]Effects of varying estuarine conditions on the sorption of phenanthrene to sediment particles of Yangtze Estuary Texte intégral
2013
Shang, Jing | Chen, Jing | Shen, Zhenyao | Wang, Ying | Ruan, Aidong
The sorption of phenanthrene on the Yangtze Estuary sediment was studied under varying conditions of particle size, sediment organic contents, salinity, and dissolved organic matter (DOM) concentrations. Small sediment particles showed higher trapping capacity for phenanthrene due to the higher organic contents associated. The organic carbon-based partition coefficient of phenanthrene to the Yangtze Estuary sediment was obtained as 7120L/kg, lower than the values for other soils or sediments reported in previous studies. The magnitude and direction of the salt effect were complicated by the specific DOM studied. The sediment sorption capacity was greatly increased in saline water in the absence of DOM but decreased in the presence of DOM. Given the conditions in the Yangtze Estuary, the equilibrium sorption of phenanthrene would be decreased with increasing salinity. Overall, the nature and content of both sediment-bound and dissolved organic matter dominate the sorption of hydrophobic organic contaminants in the estuary.
Afficher plus [+] Moins [-]The incidence of plastic ingestion by fishes: From the prey’s perspective Texte intégral
2013
One of the primary threats to ocean ecosystems from plastic pollution is ingestion by marine organisms. Well-documented in seabirds, turtles, and marine mammals, ingestion by fish and sharks has received less attention until recently. We suggest that fishes of a variety of sizes attack drifting plastic with high frequency, as evidenced by the apparent bite marks commonly left behind. We examined 5518 plastic items from random plots on Kamilo Point, Hawai’i Island, and found 15.8% to have obvious signs of attack. Extrapolated to the entire amount of debris removed from the 15km area, over 1.3tons of plastic is attacked each year. Items with a bottle shape, or those blue or yellow in color, were attacked with a higher frequency. The triangular edges or punctures left by teeth ranged from 1 to 20mm in width suggesting a variety of species attack plastic items. More research is needed to document the specific fishes and rates of plastic ingestion.
Afficher plus [+] Moins [-]Distribution and sources of polycyclic aromatic hydrocarbons in Cilician Basin shelf sediments (NE Mediterranean) Texte intégral
2013
This study corresponds to preliminary work representing an initial assessment for spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in the Cilician Basin coastal sediments. The concentrations of PAHs in shelf sediments were determined from the three different regions of Cilician Basin (Eastern Mediterranean) in 2011. Concentrations of PAHs were low 5.43–271ngg−1 with respect to other coastal sediments in the Mediterranean and these results could be compared with concentrations found in open sea areas. PAH composed mainly of pyrolytic four and five-ring compounds. An abundance of high molecular weight PAHs indicated that atmospheric particles and urban aerosols are the major input route of hydrocarbons in the Cilician and Lattakia Basins. PAH levels were assessed in accordance with numerical Sediment Quality Guideline (SQG) of the USEPA. The results showed that no samples exceeded biological thresholds to pose biological impairments.
Afficher plus [+] Moins [-]Lab tests on the biodegradation of chemically dispersed oil should consider the rapid dilution that occurs at sea Texte intégral
2013
Lee, Kenneth | Nedwed, Tim | Prince, Roger C. | Palandro, David
Most crude oils spread on open water to an average thickness as low as 0.1mm. The application of dispersants enhances the transport of oil as small droplets into the water column, and when combined with the turbulence of 1m waves will quickly entrain oil into the top 1m of the water column, where it rapidly dilutes to concentrations less than 100ppm. In less than 24h, the dispersed oil is expected to mix into the top 10m of the water column and be diluted to concentrations well below 10ppm, with dilution continuing as time proceeds. Over the multiple weeks that biodegradation takes place, dispersed oil concentrations are expected to be below 1ppm. Measurements from spills and wave basin studies support these calculations. Published laboratory studies focused on the quantification of contaminant biodegradation rates have used concentrations orders of magnitude greater than this, as it was necessary to ensure the concentrations of hydrocarbons and other chemicals were higher than the detection limits of chemical analysis. However, current analytical methods can quantify individual alkanes and PAHs (and their alkyl homologues) at ppb and ppm levels. To simulate marine biodegradation of dispersed oil at dilute concentrations commonly encountered in the field, laboratory studies should be conducted at similarly low hydrocarbon concentrations.
Afficher plus [+] Moins [-]Comparing effects of land reclamation techniques on water pollution and fishery loss for a large-scale offshore airport island in Jinzhou Bay, Bohai Sea, China Texte intégral
2013
Yan, Hua-Kun | Wang, Na | Yu, Tiao-Lan | Fu, Qiang | Liang, Zhen
Plans are being made to construct Dalian Offshore Airport in Jinzhou Bay with a reclamation area of 21km2. The large-scale reclamation can be expected to have negative effects on the marine environment, and these effects vary depending on the reclamation techniques used. Water quality mathematical models were developed and biology resource investigations were conducted to compare effects of an underwater explosion sediment removal and rock dumping technique and a silt dredging and rock dumping technique on water pollution and fishery loss. The findings show that creation of the artificial island with the underwater explosion sediment removal technique would greatly impact the marine environment. However, the impact for the silt dredging technique would be less. The conclusions from this study provide an important foundation for the planning of Dalian Offshore Airport and can be used as a reference for similar coastal reclamation and marine environment protection.
Afficher plus [+] Moins [-]A baseline assessment of beach debris and tar contamination in Bonaire, Southeastern Caribbean Texte intégral
2013
Debrot, Adolphe O. | van Rijn, Jimmy | Bron, Patrick S. | de León, Ramon
Data on beach debris and tar contamination is provided for 21 natural beach sites in Bonaire, Southeastern Caribbean. Transects amounting to a combined length of 991m were sampled March–May 2011 and a total of 8960 debris items were collected. Highest debris and tar contamination were found on the beaches of the windward east-coast of the island where geometric mean debris concentrations (± approx. 70% confidence limits) were 115±58itemsm−1 and 3408±1704gm−1 of beach front. These levels are high compared to data collected almost 20years earlier on the nearby island of Curaçao. Tar contamination levels averaged 223gm−1 on windward beaches. Contamination levels for leeward west-coast beaches were generally two orders of magnitude less than windward beaches.
Afficher plus [+] Moins [-]Combined SEM/AVS and attenuation of concentration models for the assessment of bioavailability and mobility of metals in sediments of Sepetiba Bay (SE Brazil) Texte intégral
2013
Ribeiro, Andreza Portella | Figueiredo, Ana Maria Graciano | Santos, José Osman dos | Dantas, Elizabeth | Cotrim, Marycel Elena Barboza | Cesar Lopes Figueira, Rubens | V. Silva Filho, Emmanoel | Cesar Wasserman, Julio
This study proposes a new methodology to study contamination, bioavailability and mobility of metals (Cd, Cu, Ni, Pb, and Zn) using chemical and geostatistics approaches in marine sediments of Sepetiba Bay (SE Brazil). The chemical model of SEM (simultaneously extracted metals)/AVS (acid volatile sulfides) ratio uses a technique of cold acid extraction of metals to evaluate their bioavailability, and the geostatistical model of attenuation of concentrations estimates the mobility of metals. By coupling the two it was observed that Sepetiba Port, the urban area of Sepetiba and the riverine discharges may constitute potential sources of metals to Sepetiba Bay. The metals are concentrated in the NE area of the bay, where they tend to have their lowest mobility, as shown by the attenuation model, and are not bioavailable, as they tend to associate with sulfide and organic matter originated in the mangrove forests of nearby Guaratiba area.
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