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Resultados 1511-1520 de 5,149
Environmental triggers of a Microcystis (Cyanophyceae) bloom in an artificial lagoon of Hangzhou Bay, China Texto completo
2018
Tang, Chunyu | Sun, Bin | Yu, Kefeng | Shi, Jinting | Liu, Mengmeng | Jiang, Ting | Huo, Yuanzi | He, Peimin
The relationship between Microcystis abundance and environmental variables was studied during a Microcystis bloom in the summer months of 2016 in an artificial lagoon of Hangzhou Bay, China. It was determined that Microcystis abundance increased from 0.16 × 104 cell/L to 5.8 × 107 cell/L within 17 days from 28 July to 14 August, contributing to 96.84–99.56% of the total phytoplankton abundance. Then, Microcystis gradually disappeared 57 days afterwards. The results showed that the growth of Microcystis, including the stage of recovery, outbreak, subsidence and disappearance, was significantly correlated with water temperature, salinity, soluble reactive phosphorus (PO4-P), dissolved inorganic nutrients (DIN), silicate (SiO4-Si), the ratio of DIN/SiO4-Si and zooplankton abundance, and the key environmental triggers which promoted the outbreak of Microcystis were water temperature, PO4-P concentration and zooplankton abundance in this artificial lagoon.
Mostrar más [+] Menos [-]Impact of seasonality on the nutrient concentrations in Gautami-Godavari Estuarine Mangrove Complex, Andhra Pradesh, India Texto completo
2018
Rao, Karuna | Priya, Namrata | Ramanathan, AL.
Spatiotemporal variations of dissolved nutrients were studied along Gautami-Godavari mangrove ecosystem to delineate their sources and fate. Average values of nitrate (NO3−), dissolved silica (DSi) and phosphate (PO43−) is 2.09 mg/l, 12.7 mg/l and 0.16 mg/l in wet season and 0.47 mg/l, 6.96 mg/l and 0.29 mg/l in dry season respectively. In wet season river discharge has significant influence on NO3− and DSi. In dry season, NO3− and PO43− are controlled by groundwater discharge, benthic exchange and various in situ processes owing to sediment redox condition. Mixing model shows net addition of phosphate in Coringa mangroves (95%) and Lower estuary (13%) and net removal of nitrate (24.79%) in Coringa mangrove and in estuary (58.9%). Thus present mangrove acts as net source for phosphate and net sink for nitrate and DSi. Nutrient ratio shows seasonal switching between potential Phosphorus and Nitrogen limitation in wet and dry season respectively.
Mostrar más [+] Menos [-]Assessment of the benthic ecological status in the adjacent waters of Yangtze River Estuary using marine biotic indices Texto completo
2018
Qiu, Baochao | Zhong, Xin | Liu, Xiaoshou
The adjacent waters of the Yangtze River Estuary are influenced by heavy anthropogenic activities. The benthic ecological status was assessed using the Shannon–Wiener diversity index, the AZTI Marine Biotic Index (AMBI), and the multivariate AMBI (M-AMBI) based on macrofaunal data collected in this area at 51 sites in June 2013 and June 2014. In total, 321 species of macrofauna were identified. Polychaetes were the most dominant, followed by mollusks and crustaceans. The AMBI results showed that 72.55% of the sites were under slight disturbance with a decreasing disturbance trend from inshore to offshore. M-AMBI showed that most of the sites were under lower disturbance level than those shown by AMBI. The Shannon–Wiener diversity index showed that only two sites, near the Yangtze River Estuary and the Zhoushan Islands, respectively, were under moderate status. Other sites were under good or high status, which is consistent with the M-AMBI results.
Mostrar más [+] Menos [-]Tape seagrass (Enhalus acoroides) as a bioindicator of trace metal contamination in Merambong shoal, Johor Strait, Malaysia Texto completo
2018
Sidi, Nordiani | Ahmad Zaharin Aris, | Mohamat Yusuff, Ferdaus | Looi, Ley Juen | Mokhtar, Nor Farhanna
Revealing the potential of seagrass as a bioindicator for metal pollution is important for assessing marine ecosystem health. Trace metal (111Cd, 63Cu, 60Ni, 208Pb, 66Zn) concentrations in the various parts (root, rhizome, and blade) of tape seagrass (Enhalus acoroides) collected from Merambong shoal of Sungai Pulai estuary, Johor Strait, Malaysia were acid-extracted using a microwave digester and analysed via inductively coupled plasma-mass spectrometry (ICP-MS). The ranges of trace metal concentrations (in μgg−1 dry weight) were as follows: Cd (0.05–0.81), Cu (1.62–27.85), Ni (1.89–9.35), Pb (0.69–4.16), and Zn (3.44–35.98). The translocation factor revealed that E. acoroides is a hyperaccumulator plant, as its blades can accumulate high concentrations of Cd, Cu, Ni, and Zn, but not Pb. The plant limits Pb mobility to minimize Pb's toxic impact. Thus, E. acoroides is a potential bioindicator of metal pollution by Cd, Cu, Ni, and Zn in estuarine environments.
Mostrar más [+] Menos [-]Contamination, Fate and Management of Metals in Shooting Range Soils—a Review Texto completo
2018
Sanderson, Peter | Qi, Fangjie | Seshadri, Balaji | Wijayawardena, Ayanka | Naidu, R.
Pollution of shooting range soils by lead from bullets represents a widespread and potentially significant concern for impact on the environment. High concentrations of lead in particular are reported in bullet impact berms and shot fall zones. The other components of bullets used in shooting including antimony, copper and zinc may also be present at elevated concentrations. Antimony is a concern due to its mobility in the environment. It has been recognised that the status of contamination is important for the risk presented by shooting ranges. Lead bullets are subject to weathering in the soil, forming secondary minerals, which may be solubilised and may release lead and co-contaminants into the soil. The mobility and availability of contaminants in the soil affect their potential for spreading in the environment and for uptake and toxicity in organisms. Soil physicochemical properties affect bullet weathering and availability of contaminants in the soil. A number of strategies have been researched for management of shooting range pollution such as chemical stabilisation, phytoremediation and soil washing. This review considers the current state of knowledge and research of contamination and management of shooting ranges from recent literature (2014–2017) reflecting on new knowledge and novel management strategies for shooting range soil management. Ultimately, management of pollution in shooting range soils should seek to remove bullets from soil, reduce the weathering of bullets and reduce the mobility and bioavailability of contaminants. Adopted management practices should be based an understanding of site-specific condition, to achieve the most optimal outcome.
Mostrar más [+] Menos [-]Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea Texto completo
2018
Ternengo, S. | Marengo, M. | El Idrissi, O. | Yepka, J. | Pasqualini, V. | Gobert, S.
Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea Texto completo
2018
Ternengo, S. | Marengo, M. | El Idrissi, O. | Yepka, J. | Pasqualini, V. | Gobert, S.
A study on Trace Elements (TE) from sea urchin gonads has been conducted in the western Mediterranean Sea. Contamination data were used to determine a Trace Method Pollution Index (TEPI). TE concentrations varied considerably depending on the location of the sampling stations. The results showed that five trace elements (Zn, Fe, As, Al, Cu) are ubiquitous. The geographical area considered (Corsica) represents an important range of environmental conditions and types of pressure that can be found in the western Mediterranean Sea. TEPI was used to classify the studied sites according to their degree of contamination and allowed reliable comparison of TE contamination between local and international sites. TE contamination of the western Mediterranean Sea displayed a north-to-south gradient, from the Italian coasts down through the insular Corsican coasts to the north African littoral. Due to the increasing environmental pressure on the Mediterranean Sea, a regular monitoring of TE levels in marine organisms is necessary to prevent any further environmental deterioration.
Mostrar más [+] Menos [-]Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea Texto completo
2018
Ternengo, Sonia | Marengo, Michel | El Idrissi, Ouafa | Yepka, Joseph | Pasqualini, Vanina | Gobert, Sylvie | FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
peer reviewed | A study on Trace Elements (TE) from sea urchin gonads has been conducted in the western Mediterranean Sea. Contamination data were used to determine a Trace Method Pollution Index (TEPI). TE concentrations varied considerably depending on the location of the sampling stations. The results showed that five trace elements (Zn, Fe, As, Al, Cu) are ubiquitous. The geographical area considered (Corsica) represents an important range of environmental conditions and types of pressure that can be found in the western Mediterranean Sea. TEPI was used to classify the studied sites according to their degree of contamination and allowed reliable comparison of TE contamination between local and international sites. TE contamination of the western Mediterranean Seadisplayed a north-to-south gradient, from the Italian coasts down through the insular Corsican coasts to the north African littoral. Due to the increasing environmental pressure on the Mediterranean Sea, a regular monitoring of TE levels in marine organisms is necessary to prevent any further environmental deterioration.
Mostrar más [+] Menos [-]Baseline concentrations and distributions of Polycyclic Aromatic Hydrocarbons in surface sediments from the Qatar marine environment Texto completo
2018
Hassan, Hassan Mustafa | Castillo, Azenith B. | Yigiterhan, Oguz | Elobaid, Elnaiem Ali | Al-Obaidly, Abdulrahman | Al-Ansari, Ebrahim | Obbard, Jeffrey Philip
Coastal sediments in marine waters of Qatar have the potential of being contaminated by Polycyclic Aromatic Hydrocarbons (PAHs) due to extensive petroleum exploration and transportation activities within Qatar's Marine Exclusive Economic Zone. In this study, the concentration and distribution of sixteen PAHs classed as USEPA priority pollutants were measured in sediments from the eastern Qatari coast. PAHs were recovered from sediments via accelerated solvent extraction and then analyzed using Gas Chromatography–Mass Spectrometry. Total concentrations of the PAHs were in the range of 3.15–14.35μg/kg, and the spatial distribution of PAHs is evaluated in the context of sediment total organic content, depth and the grain size together with and the proximity of petroleum exploration and transportation activities. The data show that the concentrations of PAHs within the study area were in the low-range, suggesting a low risk to marine organisms and limited transfer of PAHs into the food web.
Mostrar más [+] Menos [-]Polychlorinated biphenyls (PCBs) in recreational marina sediments of San Diego Bay, southern California Texto completo
2018
Neira, Carlos | Vales, Melissa | Mendoza, Guillermo | Hoh, Eunha | Levin, Lisa A.
Polychlorinated biphenyl (PCB) concentrations were determined in surface sediments from three recreational marinas in San Diego Bay, California. Total PCB concentrations ranged from 23 to 153, 31–294, and 151–1387ngg−1 for Shelter Island Yacht Basin (SIYB), Harbor Island West (HW) and Harbor Island East (HE), respectively. PCB concentrations were significantly higher in HE and PCB group composition differed relative to HW and SIYB, which were not significantly different from each other in concentration or group composition. In marina sediments there was a predominance (82–85%) of heavier molecular weight PCBs with homologous groups (6CL-7CL) comprising 59% of the total. In HE 75% of the sites exceeded the effect range median (ERM), and toxicity equivalence (TEQ dioxin-like PCBs) values were higher relative to those of HW and SIYB, suggesting a potential ecotoxicological risk.
Mostrar más [+] Menos [-]Reasons for seagrass optimism: Local ecological knowledge confirms presence of dugongs Texto completo
2018
Cullen-Unsworth, Leanne C. | Jones, Benjamin L. | Seary, Rachel | Newman, Rhian | Unsworth, Richard K.F.
Dugongs (Dugong dugon) depend on seagrass meadows for food. As such seagrass and dugong conservation should go hand in hand. Assessing dugong populations is notoriously challenging. In the most resource dependent communities Local Ecological Knowledge (LEK) is generally high and can provide an alternative to the use of expensive ecological surveys to understand dugong populations and support associated resource management decisions. Residents of the Wakatobi National Park (WNP), SE Sulawesi, Indonesia are highly dependent on marine resources for livelihoods and correspondingly LEK is high. Here LEK documents the presence of D. dugon in the WNP and infers changes in population size. Interviews with local residents in 2012–2013 revealed 99 sightings of dugongs since 1942, 48 of which occurred between 2002 and 2012, with 79.82% of respondents having seen a dugong. Declines in the frequency of sightings within the lifetime of several respondents were reported, respondents speculating that populations are reduced. This information can guide further cooperative research and conservation efforts for the protection of a vulnerable species and the seagrass habitat on which it depends.
Mostrar más [+] Menos [-]Concentrations of polycyclic aromatic hydrocarbons in liver samples of juvenile green sea turtles from Brazil: Can these compounds play a role in the development of fibropapillomatosis? Texto completo
2018
Vilca, Franz Zirena | Rossi, Silmara | de Olinda, Ricardo Alves | Sánchez-Sarmiento, Angélica Maria | Prioste, Fabíola Eloisa Setim | Matushima, Eliana Reiko | Tornisielo, Valdemar Luiz
Fibropapillomatosis (FP) poses a significant threat to the conservation of green sea turtles (Chelonia mydas). Polycyclic aromatic hydrocarbons-PAHs are considered mutagenic, carcinogenic and toxic, and can act as cofactor of this disease. In order to evaluate possible differences between green sea turtles with and without FP, we monitored 15 PAHs in liver samples of 44 specimens (24 with FP) captured in Brazil. We detected eight PAHs and quantified phenanthrene in all green sea turtles with FP. Specimens without FP presented lower values than the tumored ones (1.48 ng g−1 and 17.35 ng g−1, respectively; p < 0.0001). There were no significant differences between tumored and non-tumored specimens, among studied areas, or Southwest Atlantic Fibropapillomatosis Score. Even though we found higher concentrations in the liver samples of green sea turtles with FP, further studies are necessary to confirm if these pollutants are involved in the pathogenesis of the disease.
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