Search results for "Accumulation"
showing 10 items of 240 documents
Mercury in fishes from Augusta Bay (southern Italy): risk assessment and health implication
2013
Our study reports on the total mercury (HgT) concentrations measured in the muscles and livers of several benthic, demersal and pelagic fish species caught inside and outside of Augusta Bay (southern Italy), a semi-enclosed marine area, highly contaminated by the uncontrolled (since the 1950s to 1978s) discharge of the largest European petrochemical plant. Mercury levels in fish tissues are discussed with regard to specific habitat, size and/or age of the specimens and HgT distribution in the bottom sediments. Results suggest a still active Hg release mechanism from the polluted sediments to the marine environment. Also, the high HgT concentrations measured in fishes caught in the external …
Determination of lead in treated crayfish Procambarus clarkii: accumulation in different tissues.
1988
The continual loading of trace metals into our environment represents a water pollution problem due to their toxic effects on aquatic biota. In addition, metal ions can be incorporated into food chains and concentrated by aquatic organisms to a level that affects their physiological state. There are several investigations on the toxic effects and bioaccumulation of lead in fishes, molluscs, and crustaceans. Lake Albufera (Valencia, Spain) and the surrounding rice-field waters are subjected to large loads of sewage and toxic industrial residues (including heavy metals) from many urban wastewaters in the area. In 1978, the American red crayfish Procambarus clarkii (Girard) appeared in Lake Al…
An approach to the diazinon toxicity in the European eel: bioaccumulation studies
1993
Abstract The acute toxicity effects of diazinon on European eel ( Anguilla anguilla ) were examined using short-term exposures in static conditions. In these conditions the 96-h median lethal concentration (LC 50 ) was 0.086 mg/1. In addition, the eels were exposed to two sublethal diazinon concentrations, 0.042 and 0.056 mg/1 (1/2 and 2/3 LC 50 96-h, respectively) for different exposure times, till a maximum of 96 h, and bioaccumulation and clearance of this insecticide in liver, muscle, gill and blood tissues were studied. BCF values of diazinon after 96 h exposure to 0.042 mg/l were 1850 in liver, 875 in gill and 775 in eel muscle. BCF values of diazinon over a 48-h exposure period to 0.…
Bioaccumulation and subchronic physiological effects of waterborne iron overload on whitefish exposed in humic and nonhumic water.
1999
One-year-old whitefish, Coregonus lavaretus, were exposed to three types of iron-rich water, two dilutions for each, in a subchronic (30-day) experiment. In natural iron-rich humic water, both the bioaccumulation and physiological effects of iron exposure were negligible. In humic-free water with high amount of additional inorganic iron (nominally 8 mg Fe/L), Fe accumulated in gills, liver, and gut. This accumulation was accompanied by decreased glycogen phosphorylase activities and microsomal EROD activity in the liver as well as decreased plasma sodium and potassium concentrations. The third group of whitefish were exposed by adding inorganic iron (nominally 2 and 8 mg Fe/L) to natural ir…
Chemical and biochemical responses to sub−lethal doses of mercury and cadmium in gilthead seabream (Sparus aurata)
2022
Specimens of Sparus aurata were exposed to sub-lethal concentrations of Hg and Cd for 25 days and the levels of both metals were investigated in organs and tissues. Bioaccumulation of Hg decreased as follow: gills > kidney > liver > skin > muscle, while the order of Cd bioaccumulation was: liver > kidney > gills > skin > muscle. Immediately after exposure, both metals showed the highest bioaccumulation in gills and skin indicating that these organs are reliable targets for biomonitoring studies after short term exposure. Metals introduction caused a significant time-dependent concentrations increase in kidney and liver, while in the muscle a significant in-crease of …
The Bossons glacier protects Europe's summit from erosion
2013
13 pages; International audience; The contrasting efficiency of erosion beneath cold glacier ice, beneath temperate glacier ice, and on ice-free mountain slopes is one of the key parameters in the development of relief during glacial periods. Detrital geochronology has been applied to the subglacial streams of the north face of the Mont-Blanc massif in order to estimate the efficiency of erosional processes there. Lithologically this area is composed of granite intruded at ~303 Ma within an older polymetamorphic complex. We use macroscopic features (on ~10,000 clasts) and U-Pb dating of zircon (~500 grains) to establish the provenance of the sediment transported by the glacier and its subgl…
Monitoring glacier elevation and volume changes with digital photogrammetry and GIS at Gepatschferner glacier, Austria
2006
Digital elevation models of Gepatschferner in Northern Tyrol, Austria were obtained with digital photogrammetry from high altitude stereo photo pairs and by digitizing an analogue topographic glacier map, for 1990 and 1971, respectively. A difference map was calculated to identify regions of glacier elevation increases and decreases corresponding to glacier mass gain and loss. While the glacier tongue below 2600 m showed mainly increases in glacier surface elevation as compared to 1971, the remaining glacier thickness experienced both increases and decreases. The accumulation zone above 3200 m contained several extreme cases of morphological features with altitude changes>+30 m. While the i…
Two-dimensional numerical modeling of fracturing and shear band development in glacier fronts
2014
In this contribution we present a two-dimensional numerical model of a deforming glacier front. The model is based on a hybrid lattice spring network approach where particles in the model can deform in a volume conservative visco-elastic manner but at the same time they can be compressed elastically and fracture by discrete failure. We restrict ourselves to a simple setting where the glacier sits on a frictionless slope that dips with 5–10°, the ice block is fixed on one side and has a free surface on the other. The glacier varies in viscosity and can flow at the base, whereas it is brittle at the top. Results show that the head of the glacier is unstable. Failure happens as a combination o…
Change in geometry of a high Arctic glacier to 1948 to 2013 (Austre Lovénbreen, Svalbard)
2017
International audience; The change of Austre Lovénbreen, a 4.5 km2 land-based glacier along the west coast of Spitsbergen, is investigated using geodetic methods and mass balance measurements over 1948–2013. For 2008−2013, annual mass balances computed on 36-stake measurements were obtained, in addition to annual mass balances reconstructed from the neighbouring glaciers, Midtre Lovénbreen (1968−2007) and Austre Brøggerbreen (1963−1967). The mean rate of glacier retreat for 1948–2013 is −16.7 ± 0.3 m a−1. Fluctuations in area (1948–2013 mean, −0.027 ± 0.002 km2 a−1) showed a slowing as the glacier recedes within its valley from 1990 to 1995. For 1962–2013, the average volume loss calculated…
THE INFLUENCE OF LANDFILL FEATURES AND SIDE SLOPES ON METHANE EMISSION RATES
2011
Sanitary landfills for Municipal Solid Waste (MSW) disposal have been identified as one of the most important sources of methane (CH4) emissions; indeed, MSW contains a certain amount of biodegradable organic matter which undergoes anaerobic degradation resulting in the production of the so called landfill gas (LFG), which main component is typically represented by CH4. In general, LFG will escape through any faults in the landfill capping or in the LFG collection system. If the capping is not damaged, low quantities of LFG will be emitted through the permeable material that covers the disposed waste. On the other hand, some zones of the capping are often more permeable than others (e.g. si…