خيارات البحث
النتائج 711 - 720 من 3,240
To swim or not to swim? A disagreement between microbial indicators on beach water quality assessment in Hong Kong النص الكامل
2015
Cheung, Pui Kwan | Yuen, Ka Lai | Li, Ping Fai | Lau, Wai Hing | Chiu, Chung Man | Yuen, Suet Wai | Baker, David M.
The USEPA and the WHO now advocate the use of enterococci as indicators for marine water quality. This study investigated the outcomes for Hong Kong beach water quality assessment by comparing enterococcus measures with data from the HKEPD's monitoring programme. Six beaches were tested once every 2–3months from November 2013 to June 2014 in order to identify the most contaminated sites, followed by intensive water sampling in sites found to have the highest enterococci densities (Clear Water Bay Second and Golden) every five to six days for six sampling events over a 30-day period in 2014. The geometric means of enterococci were found to be 124 and 41cfu/100mL at Clear Water Bay Second and Golden respectively, indicating that there may be higher risks of illness associated with swimming at both beaches than previously known. Moreover, beach sediments contained higher concentrations of enterococci than water, and warrant further study.
اظهر المزيد [+] اقل [-]Quiet(er) marine protected areas النص الكامل
2015
Williams, Rob | Erbe, Christine | Ashe, Erin | Clark, Christopher W.
A core task in endangered species conservation is identifying important habitats and managing human activities to mitigate threats. Many marine organisms, from invertebrates to fish to marine mammals, use acoustic cues to find food, avoid predators, choose mates, and navigate. Ocean noise can affect animal behavior and disrupt trophic linkages. Substantial potential exists for area-based management to reduce exposure of animals to chronic ocean noise. Incorporating noise into spatial planning (e.g., critical habitat designation or marine protected areas) may improve ecological integrity and promote ecological resilience to withstand additional stressors. Previous work identified areas with high ship noise requiring mitigation. This study introduces the concept of “opportunity sites” — important habitats that experience low ship noise. Working with existing patterns in ocean noise and animal distribution will facilitate conservation gains while minimizing societal costs, by identifying opportunities to protect important wildlife habitats that happen to be quiet.
اظهر المزيد [+] اقل [-]Assessing potential risks of wastewater discharges to benthic biota: An integrated approach to biomarker responses in clams (Ruditapes philippinarum) exposed under controlled conditions النص الكامل
2015
Maranho, L.A. | DelValls, T.A. | Martín-Díaz, M.L.
Marine clams Ruditapes philippinarum were exposed under laboratory conditions to sediments sampled at five sites affected by wastewater effluents at the Bay of Cádiz (SW, Spain). Contamination and early biological stress were determined. Metabolism and antioxidant system differed according to seasons. Health status diminished in summer. Metabolism of detoxification, and oxidative effect were related to concentration of metals, PAH, secondary alkane sulfonates (SAS) and antibiotics in winter. Antioxidant system and DNA damage were linked to metals and pharmaceutical products. Phase I and antioxidant system were associated to PAH and SAS in summer. Oxidative stress and effects were related to pharmaceuticals. Phase II was linked to metals and pharmaceuticals. Seasonality of sediment contamination by organic compounds and biological responses was determined. Clams were useful bioindicators, since the set of biomarkers applied was validated as potential tools for sediment quality assessment of wastewater discharges areas.
اظهر المزيد [+] اقل [-]An assessment of human influences on sources of polycyclic aromatic hydrocarbons in the estuarine and coastal sediments of China النص الكامل
2015
Duan, Xiaoyong | Liu, Jinqing | Zhang, Daolai | Yin, Ping | Li, Yanxia | Li, Xianguo
Sediments collected from the coastal area of China, embracing west coast of Bohai Sea, south coast of Shandong Peninsula, and the Changjiang estuary (listed in order of decreasing north latitude), were analyzed for polycyclic aromatic hydrocarbons (PAHs). ∑PAH (Sixteen US EPA priority PAHs) were 2.7–350.9ng/g. Petroleum residue was the major contributor of PAHs in the coastal sediments of China due to oil leakage from ships and offshore oil fields. The contribution of vehicular emissions in coast of North China was significantly lower than that in the Changjiang Estuary, and the reverse was true for coal combustion. PAH concentrations in the sediment core of the Changjiang estuary steadily increased upward and the variation was primarily due to economic development and severe floods. The impact on PAHs by vehicular emissions (37.2%) and petrogenic sources (45.8%) overwhelmed combustion sources (17.0%).
اظهر المزيد [+] اقل [-]Evaluation of metals and hydrocarbons in sediments from a tropical tidal flat estuary of Southern Brazil النص الكامل
2015
Costa, Eduardo S. | Grilo, Caroline F. | Wolff, George A. | Thompson, Anu | Figueira, Rubens Cesar Lopes | Neto, Renato Rodrigues
Although the Passagem Channel estuary, Espírito Santo State, Brazil, is located in an urbanized and industrialized region, it has a large mangrove system. Here we examined natural and anthropogenic inputs that may influence trace metal (Cd, Cr, Cu, Ni, Sc, Pb and Zn) and hydrocarbon (n-alkane and terpane) deposition in three sediment cores collected in the tidal flat zone of the estuary. The cores were also analyzed for carbonate, grain size and stable isotopic composition (δ13Corg. and δ15Ntotal). Metal enrichment and its association to petroleum hydrocarbons in the surficial sediments of one of the cores, indicate crude oil and derivative inputs, possibly from small vessels and road run-off from local heavy automobile traffic. At the landward sites, the major contributions for metals and hydrocarbons are from natural sources, but in one case, Cu may have been enriched by domestic effluent inputs.
اظهر المزيد [+] اقل [-]Physical controls of hypoxia in waters adjacent to the Yangtze Estuary: A numerical modeling study النص الكامل
2015
Chen, Xiaofeng | Shen, Zhenyao | Li, Yangyang | Yang, Ye
A three-dimensional circulation model (the Environmental Fluid Dynamic Code) was used to examine the role that physical forcing (river discharge, wind speed and direction) plays in controlling hypoxia in waters adjacent to the Yangtze Estuary. The model assumes that the biological consumption of oxygen is constant in both time and space, which allows the role of physical forcing in modulating the oxygen dynamics to be isolated. Despite of the simplicity of this model, the simulation results showed that it can reproduce the observed variability of dissolved oxygen in waters adjacent to the Yangtze Estuary, thereby highlighting the important role of changes in physical forcing in the variation of hypoxia. The scenarios tested revealed appreciable changes in the areal extent of hypoxia as a function of wind speed and wind direction. Interestingly, well-developed hypoxia was insensitive to river discharge.
اظهر المزيد [+] اقل [-]Sequencing Batch Reactor for Wastewater Treatment: Recent Advances النص الكامل
2015
Dutta, Aparna | Sarkar, Sudipta
Sequencing batch reactors (SBRs), due to its operational flexibility and excellent process control possibilities, are being extensively used for the treatment of wastewater which nowadays is fast becoming contaminated with newer and more complex pollutants. It is also possible to include different expanding array of configurations and various operational modifications to meet the effluent limits which are also continuously getting upgraded. This article provides basic description of SBR process along with its functional and physical variants that lead to improved the removal of nutrients and emerging contaminants. The significance of selectors and various recent advancements in the application of SBR has been discussed along with the possibilities held by SBR process in the treatment of wastewater of different origins and composition to produce effluent of reusable quality.
اظهر المزيد [+] اقل [-]An effective seed protection method for planting Zostera marina (eelgrass) seeds: Implications for their large-scale restoration النص الكامل
2015
Zhang, Pei-Dong | Fang, Chao | Liu, Jie | Xu, Qiang | Li, Wen-Tao | Liu, Yan-Shan
We describe an innovative method of planting Zostera marina (eelgrass) seeds in which hessian bags filled with high-silted sediments are used as a seed protecting device. Here, we evaluated the effectiveness of the method through a field seed-sowing experiment over a three year period. The suitable seed planting density required by the seeds of Z. marina in this method was also investigated. In the spring following seed distribution, seedling establishment rate of Z. marina subjected to different seed densities of 200–500seedsbag−1 ranged from 16% to 26%. New eelgrass patches from seed were fully developed and well maintained after 2–3years following distribution. The seed planting density of 400seedsbag−1 may be the most suitable for the establishment of new eelgrass patches. Our results demonstrate that seed-based restoration can be an effective restoration tool and the technique presented should be considered for future large-scale Z. marina restoration projects.
اظهر المزيد [+] اقل [-]Proteomic analysis of the European flounder Platichthys flesus response to experimental PAH–PCB contamination النص الكامل
2015
Galland, Claire | Dupuy, Célie | Loizeau, Véronique | Danion, Morgane | Auffret, Michel | Quiniou, Louis | Laroche, Jean | Pichereau, Vianney
Platichthys flesus is often used as a sentinel species to monitor the estuarine water quality. In this study, we carried out an experimental contamination of fish using a PAHs/PCBs mixture, which was designed to mimic the concentrations found in the Seine estuary (C1) and 10 times these concentrations (C2). We used a proteomic approach to understand the molecular mechanisms implied in the response of P. flesus to these xenobiotics. We showed that 54 proteins were differentially accumulated in one or several conditions, which 34 displayed accumulation factors higher than two. 18 of these proteins were identified by MALDI TOF–TOF mass spectrometry. The results indicated the deregulation of oxidative stress- and glutathione metabolism-(GST, GPx) proteins as well as of several proteins belonging to the betaine demethylation pathway and the methionine cycle (BHMT, SHMT, SAHH), suggesting a role for these different pathways in the P. flesus response to chemical contamination.
اظهر المزيد [+] اقل [-]Response of benthos to ocean outfall discharges: does a general pattern exist? النص الكامل
2015
Puente, A. | Diaz, R.J.
We assessed the effects of 40 ocean outfalls on adjacent macrobenthic invertebrates. Data were obtained from a review of gray and peer-review literature. Different parameters describing the outfall characteristics were compiled (length, maximum depth, treatment level, flow and organic matter mass discharged). Exposure to wave action was represented by significant wave height. The magnitude of the effect was categorized in three impact levels and classified considering different ecological indicators. A theoretical predictive model was formulated in which the lower the organic matter and the higher the energy of the system, the lower the benthic impact. The main conclusion was that the general pattern of the succession of benthic communities brought about by ocean outfalls fits the model of Pearson–Rosenberg but with some deviations i) the probability of a significant impact is much lower, ii) not all the successional stages occur and, iii) the magnitude of the changes are usually lower.
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