Уточнить поиск
Результаты 651-660 из 1,539
Evaluation for the ecological quality status of coastal waters in East China Sea using fuzzy integrated assessment method
2012
Wu, H.Y. | Chen, K.L. | Chen, Z.H. | Chen, Q.H. | Qiu, Y.P. | Wu, J.C. | Zhang, J.F.
This research presented an evaluation for the ecological quality status (EcoQS) of three semi-enclosed coastal areas using fuzzy integrated assessment method (FIAM). With this method, the hierarchy structure was clarified by an index system of 11 indicators selected from biotic elements and physicochemical elements, and the weight vector of index system was calculated with Delphi-Analytic Hierarchy Process (AHP) procedure. Then, the FIAM was used to achieve an EcoQS assessment. As a result of assessment, most of the sampling stations demonstrated a clear gradient in EcoQS, ranging from high to poor status. Among the four statuses, high and good, owning a ratio of 55.9% and 26.5%, respectively, were two dominant statuses for three bays, especially for Sansha Bay and Luoyuan Bay. The assessment results were found consistent with the pressure information and parameters obtained at most stations. In addition, the sources of uncertainty in classification of EcoQS were also discussed.
Показать больше [+] Меньше [-]Ragworm fatty acid profiles reveals habitat and trophic interactions with halophytes and with mercury
2012
Lillebø, Ana Isabel | Cleary, Daniel Francis Richard | Marques, Bruna | Reis, Alberto | Lopes da Silva, Teresa | Calado, Ricardo
The present study aimed to assess if ragworm fatty acids (FA) profiles could be used to discriminate their spatial distribution in an historically mercury-contaminated estuarine environment, i.e., if it was possible to differentiate ragworms present in salt marsh sediments surrounding plant roots and rhizomes (rhizosediment) from adjacent unvegetated sediment. Additionally, we also tried to determine if ragworms differed in mercury content and if these values could also be used to identify the habitat they occur in. Results show that, within the same area, ragworms can be distinguished using FA profiles and that in halophyte rhizosediment ragworms display more than twice the levels of alpha-linolenic acid (18:3n-3). The ratio cis-vaccenic/oleic acids (18:1n-7/18:ln-9) in ragworms suggests higher carnivory in unvegetated sediments. Our study indicates that ragworm FA profiles can be used to identify their habitat, their trophic interaction with halophytes and reveal a spatially contrasting feeding behaviour, which also reflects mercury accumulation.
Показать больше [+] Меньше [-]Sedimentary records of metal contamination and eutrophication in Jinhae-Masan Bay, Korea
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.
Показать больше [+] Меньше [-]Persistent organic pollutants in the endangered Hawaiian monk seal (Monachus schauinslandi) from the main Hawaiian Islands
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.
Показать больше [+] Меньше [-]Foraminifera as indicators of marine pollutant contamination on the inner continental shelf of southern Brazil
2012
Eichler, Patricia P.B. | Eichler, Beatriz B. | Gupta, Barun Sen | Rodrigues, André Rösch
Analyses of living foraminiferal and environmental parameters near an outfall at Mar Grosso Beach (Laguna, SC, Brazil) demonstrate its usefulness as indicators of domestic sewage pollution. The low species diversity may be due to sand accumulation in the central part. Higher diversity was noted closer to the mouth of Laguna estuarine system where reduced salinity and higher temperatures indicate freshwater influence, suggesting a relationship between increased diversity and greater availability of terrestrial food. On the basis of foraminiferal diversity and average coliform count the higher values are closer to the mouth of the estuarine system and under the influence of the outfall. Due to the effect of local hydrodynamics, the particulate organic waste derived from the outfall does not settle down locally, and thus, do not accumulate nearby. Our hypothesis is that the fine material derived from the outfall is accumulating on the southwestern and northwestern parts of the beach.
Показать больше [+] Меньше [-]Monitoring of East Channel dredge areas benthic fish population and its implications
2012
Drabble, Ray
Regional annual sampling of commercial fish stocks formed a high priority for monitoring studies attendant with the granting of aggregate dredging licenses in the Eastern Channel Region (ECR) which had previously not been dredged. An assessment of 4m beam trawl sampling between 2005 and 2008 following the granting of licences in 2006 is provided. The majority of fish species have shown marked reductions in abundance since commencement of dredging. Draghead entrainment has been identified as a possible contributory cause based upon the known vulnerability of selected species (Drabble, 2012). Other environmental factors considered offer no explanation for the changes in abundance. Comparative analyses with ICES data for plaice and sole over the study period demonstrate that changes in the ECR do not result from seasonal flux in the wider populations. An alternative impact model and potential mitigation measures are suggested.
Показать больше [+] Меньше [-]Chemical composition and acute toxicity in the water after in situ burning – A laboratory experiment
2012
Faksness, Liv-Guri | Hansen, Bjørn Henrik | Altin, Dag | Brandvik, Per Johan
The chemical composition and toxicity of a water soluble fraction (WSF) of oil versus the underlying water after in situ burning (ISB), has been studied in a laboratory experiment. A system for allowing water sampling after ISB was developed. Seawater samples and oil were collected prior to and immediately after ISB, and chemical analysis was conducted. The chemical characterization of the water showed that the disappearance of water soluble oil components during ISB was insignificant. Acute toxicity tests with the marine copepod Calanus finmarchicus and Microtox® bioassay was performed to establish LC₅₀/EC₅₀ values of the water. The results were compared with regular WAF systems with unburned weathered oil, and indicated no increase in toxicity in the underlying water after ISB.
Показать больше [+] Меньше [-]Distribution and seasonal variation in the partial pressure of CO₂ during autumn and winter in Jiaozhou Bay, a region of high urbanization
2012
Zhang, Longjun | Siuvai, Ming | Liu, Qizhen
We investigated the partial pressure of carbon dioxide (pCO₂) in Jiaozhou Bay (JZB), which is surrounded by the economically developed city of Qingdao, during two cruises undertaken in November, 2007 (autumn) and February, 2008 (winter). Results indicated that sea surface pCO₂ in autumn varied between 315 and 720μatm, with an average level of 418μatm. In winter the sea surface pCO₂ ranged from 145 to 315μatm with an average of 249μatm, which is below atmospheric pCO₂. Despite seasonal temperature variation between autumn and winter, it was noted that biological process (production and respiration) were responsible for both spatial and seasonal variation during these seasons. We found that Jiaozhou Bay served as a net atmospheric CO₂ source in autumn (November) (2.87mmolm⁻²d⁻¹), while in winter (February) it served as a net sink (−16.22mmolm⁻²d⁻¹).
Показать больше [+] Меньше [-]Long-term monitoring of heavy metals in Chilean coastal sediments in the eastern South Pacific Ocean
2012
Chandía, Cristian | Salamanca, Marco
Concentrations of seven metals (Al, Cd, Cu, Fe, Pb, Ni, Zn) were determined in 256 surface sediment samples, collected between May 2006 and November 2009, from 15 stations at the mouth of the Itata River and its adjacent marine zone (central-southern Chile) as part of an environmental monitoring program. The objectives of the work were to: (i) establish baseline metal concentrations in the sediments of the area and (ii) identify tendencies in the spatial and temporal distribution of the metals in these marine sediments. Concentrations were highest in the north zone of the Itata River mouth (stations E2C, E13C) for all the metals and at the stations farthest offshore from the mouth (E4, E6) for Cu, Fe, Pb, and Ni. The ranges in those concentrations were lower than those reported in other studies performed along the Chilean coast and lower than those observed in most other coastal systems around the world. Based on results of the indices used (geoaccumulation index, enrichment factor), the coastal sediments were not measurably elevated above natural levels.
Показать больше [+] Меньше [-]An empirical model of water quality for use in rapid management strategy evaluation in Southeast Queensland, Australia
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.
Показать больше [+] Меньше [-]