947 resultados para coastal area


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In the past few years, it has become increasingly apparent that perchlorate (ClO4-) is present on all continents, except the polar regions where it had not yet been assessed, and that it may have a significant natural source. Here, we report on the discovery of perchlorate in soil and ice from several Antarctic Dry Valleys (ADVs) where concentrations reach up to 1100/µg/kg. In the driest ADV, perchlorate correlates with atmospherically deposited nitrate. Far from anthropogenic activity, ADV perchlorate provides unambiguous evidence that natural perchlorate is ubiquitous on Earth. The discovery has significant implications for the origin of perchlorate, its global biogeochemical interactions, and possible interactions with the polar ice sheets. The results support the hypotheses that perchlorate is produced globally and continuously in the Earth's atmosphere, that it typically accumulates in hyperarid areas, and that it does not build up in oceans or other wet environments most likely because of microbial reduction on a global scale.

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In order to examine the spatial distribution of organic-walled dinoflagellate cysts (dinocysts) in recent sediments related to environmental conditions in the water column, thirty-two surface sediment samples from the NW African upwelling region (20-32°N) were investigated. Relative abundances of the dinocyst species show distinct regional differences allowing the separation of four hydrographic regimes. (1) In the area off Cape Ghir, which is characterized by most seasonal upwelling and river discharge, Lingulodinium machaerophorum strongly dominates the associations which are additionally characterized by cysts of Gymnodinium nolleri, cysts of Polykrikos kofoidii and cysts of Polykrikos schwartzii. (2) Off Cape Yubi, a region with increasing perennial upwelling, L. machaerophorum, Brigantedinium spp., species of the genus Impagidinium and cysts of Protoperidinium stellatum occur in highest relative abundances. (3) In coastal samples between Cape Ghir and Cape Yubi, Gymnodinium catenatum, species of the genus Impagidinium, Nematosphaeropsis labyrinthus, Operculodinium centrocarpum, cysts of P. stellatum and Selenopemphix nephroides determine the species composition. (4) Off Cape Blanc, where upwelling prevails perennially, and at offshore sites, heterotrophic dinocyst species show highest relative abundances. A Redundancy Analysis reveals fluvial mud, sea surface temperature and the depth of the mixed layer in boreal spring (spring) as the most important parameters relating to the dinocyst species association. Dinocyst accumulation rates were calculated for a subset of samples using well-constrained sedimentation rates. Highest accumulation rates with up to almost 80.000 cysts cm**-2 ky**-1 were found off Cape Ghir and Cape Yubi reflecting their eutrophic upwelling filaments. A Redundancy Analysis gives evidence that primary productivity and the input of fluvial mud are mostly related to the dinocyst association. By means of accumulation rate data, quantitative cyst production of individual species can be considered independently from the rest of the association, allowing autecological interpretations. We show that a combined interpretation of relative abundances and accumulation rates of dinocysts can lead to a better understanding of the productivity conditions off NW Africa.

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Rin de Aveiro is a coastal lagoon located at the Central Region of Portugal subjected to the influence of the tides, resulting in a set of characteristic biotopes favouring anthropic and natural processes. Once managed and controlled correctly, each of these biotopes will allow simultaneously the biodiversity and integration in the making of the wetland landscape. In 1998, one of the final conclusions of the "MARIA" Demonstration Programme for the Integrated Management of Ria de Aveiro was that the poor current state of the environment area resulted from a set of interrelated factors. The Programme selected four (4) pilot-projects towards the integrated management of the lagoon biotopes as possible scenarios for an intervention. This selection was based in criteria related to environmental priorities and the maintenance of traditional economic activities in the region. The idea of choosing projects that would involve the whole geographic space of the Ria, without forgetting the other important themes interrelated with the Management Structure, emerged as a relevant aspect for their definition. Thus, and as a first test of this Management Structure functionality, the following task forces were put forward: Recovery and valorisation of the piers; Recovery of the former salt pans; Management of the agricultural fields of Baixo-Vouga; Implementation of measures for the classification of the Protected Landscape Area of the River Caster Mouth. This payer will report the main results of these pilot-projects attained during their first year period, especially the intervention strategies defined by the Partnership created for this aim.

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Thesis (Master's)--University of Washington, 2016-06

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This is especially well supported by down core variation Zn concentration. As Caspian Sea water intrudes into the Bay, it may be concluded that some part of pollution has sea origin. The geochemical index (Igeo) was reformulated for the area of study using chemical partitioning as well as Pb-210 results. The newly developed geochemical index is indicative of low to medium pollution intensity in the Bay of Gorgan. Thus, any additional pollution into the area of study may leave adverse effects on the aquatic ecology of Bay of Gorgan. Further, lithogenous and non-lithogenous inputs of metals into the Bay were assessed. For this purpose and through chemical partitioning, association of metals with different sedimentary phases was determined. The overall results show that about 114th total metal concentration have been added into the Bay of Gorgan through human activities.

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Today the Ria de Aveiro of northern Portugal has a hydromorphological regime in which river influence is limited to periods of flood. For most of the annual cycle, tidal currents and wind waves are the major forcing agents in this complex coastal lagoon–estuarine system. The system has evolved over two centuries from one that was naturally fluvially dominant to one that is today tidally dominant. Human influence was a trigger for these changes, starting in 1808 when its natural evolution was halted by the construction of a new inlet/outlet channel through the mobile sand spit that isolates it from the Atlantic Ocean. In consequence, tidal ranges in the lagoon increased rapidly from ~0.1 m to >1 m and continued to increase, as a result of continued engineering works and dredging, today reaching ~3 m on spring tides. Hydromorphological adjustments that have taken place include the deepening of channels, an increase in the area of inter-tidal flats, regression of salt marsh, increased tidal propagation and increased saline intrusion. Loss of once abundant submerged aquatic vegetation (SAV), due to increased tidal flows, exacerbated by increased recreational activities, has been accompanied by a change from fine cohesive sediments to coarser, mobile sediments with reduced biological activity.

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A spatially explicit coupled hydrodynamic-biogeochemical model was developed to study a coastal ecosystem under the combined effects of mussel aquaculture, nutrient loading and climate change. The model was applied to St Peter's Bay (SPB), Prince Edward Island, Eastern Canada. Approximately 40 % of the SPB area is dedicated to mussel (Mytilus edulis) longline culture. Results indicate that the two main food sources for mussels, phytoplankton and organic detritus, are most depleted in the central part of the embayment. Results also suggest that the system is near its ultimate capacity, a state where the energy cycle is restricted to nitrogen-phytoplankton-detritus-mussels with few resources left to be transferred to higher trophic levels. Annually, mussel meat harvesting extracts nitrogen (N) resources equivalent to 42 % of river inputs or 46.5 % of the net phytoplankton primary production. Under such extractive pressure, the phytoplankton biomass is being curtailed to 1980's levels when aquaculture was not yet developed and N loading was half the present level. Current mussel stocks also decrease bay-scale sedimentation rates by 14 %. Finally, a climate change scenario (year 2050) predicted a 30 % increase in mussel production, largely driven by more efficient utilization of the phytoplankton spring bloom. However, the predicted elevated summer temperatures (> 25 A degrees C) may also have deleterious physiological effects on mussels and possibly increase summer mortality levels. In conclusion, cultivated bivalves may play an important role in remediating the negative impacts of land-derived nutrient loading. Climate change may lead to increases in production and ecological carrying capacity as long as the cultivated species can tolerate warmer summer conditions.

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In 2014, the Australian Government implemented the Emissions Reduction Fund to offer incentives for businesses to reduce greenhouse gas (GHG) emissions by following approved methods. Beef cattle businesses in northern Australia can participate by applying the 'reducing GHG emissions by feeding nitrates to beef cattle' methodology and the 'beef cattle herd management' methods. The nitrate (NO3) method requires that each baseline area must demonstrate a history of urea use. Projects earn Australian carbon credit units (ACCU) for reducing enteric methane emissions by substituting NO3 for urea at the same amount of fed nitrogen. NO3 must be fed in the form of a lick block because most operations do not have labour or equipment to manage daily supplementation. NO3 concentrations, after a 2-week adaptation period, must not exceed 50 g NO3/adult animal equivalent per day or 7 g NO3/kg dry matter intake per day to reduce the risk of NO3 toxicity. There is also a 'beef cattle herd management' method, approved in 2015, that covers activities that improve the herd emission intensity (emissions per unit of product sold) through change in the diet or management. The present study was conducted to compare the required ACCU or supplement prices for a 2% return on capital when feeding a low or high supplement concentration to breeding stock of either (1) urea, (2) three different forms of NO3 or (3) cottonseed meal (CSM), at N concentrations equivalent to 25 or 50 g urea/animal equivalent, to fasten steer entry to a feedlot (backgrounding), in a typical breeder herd on the coastal speargrass land types in central Queensland. Monte Carlo simulations were run using the software @risk, with probability functions used for (1) urea, NO3 and CSM prices, (2) GHG mitigation, (3) livestock prices and (4) carbon price. Increasing the weight of steers at a set turnoff month by feeding CSM was found to be the most cost-effective option, with or without including the offset income. The required ACCU prices for a 2% return on capital were an order of magnitude higher than were indicative carbon prices in 2015 for the three forms of NO3. The likely costs of participating in ERF projects would reduce the return on capital for all mitigation options. © CSIRO 2016.

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The Alcantarilha lowland, partly barred by a well developed barrier, including foredunes covering Pleistocene-Holocene beachrock and aeolianite, develops across the Alcantarilha infilled estuary, the beach-dune extending further SE until the Salgados lagoon. A topographic and coring survey revealed a peculiar feature at the leeward toe of the dune ridge close to the inlet area: a sandy fan with location, shape and morphology suggesting emplacement by single or multiple overwash of the barrier tip rather than tidal forcing. Its storm or tsunami origin and age are under investigation, and the only time-constrain available at present is that it should post-date ca. 6600 cal BP, the most recent in situ aeolianite (Moura et al., 2007) dated so far. METHODS, DATA SET AND RESULTS The fan boundaries are distinctive in aerial photos and satellite images: it is roughly ellipsoidal, ~200 m wide and ~300 m elongated paralleling the shoreline, rising ~ 0.9-1.2 m above the surrounding floodplain surface. Detailed topography shows that its short axis aligns with SW-NE elongated (though irregular) depressions in the dune crest, which link the beach with the fan. This could have favoured funnelling of, or erosion by, water overtopping the barrier but, in either case, the fan should correspond to extreme and abrupt event(s) of coastal flooding. 18 trenches and cores were performed in the exposed area of the fan and nearby flood plain to obtain samples and data on its sedimentology, lithostratigraphy and geometry. The fan consists of well sorted and rounded sand (Fig. 2). It thins away and wedges out landwards of the apex (located near Alc29T) where it is partly covered by dune sand. Its lower boundary is undulating and marked by textural contrast between sand (fan) and underlying mud (alluvial/lagoonal); an accumulation of marine-sourced perforated pebbles showing limited lateral continuity may pinpoint this boundary near the foredune (core Alc 25, ca. 80 m westward of profile in Fig.1); mud-balls were also observed immediately above this surface in cores and trenches. As the washover was probably emplaced in a barred lagoonal/estuarine floodplain setting, the fan’s northern outer belt is enclosed by low-energy sediments (not shown in Fig. 2).

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The coastal districts, as an intersection of two perfectly different ecosystems of dry land and sea, is one of the most complicated and the richest natural system on earth. Considering these areas are constantly exposed to aggregation of water pollutants and also consequence resulting from construction and development activities, they are very vulnerable. Therefore, "sensitive Coastal areas" has become a common word in the related subjects to marine environment recently. The said title relates to the areas of the coastal lines which are vulnerable to the natural condition or human actions because of ecological, social, economic, educational and research importance, also they need particular supports. The southern coasts of Caspian Sea, In Iran prominent samples are of these sensitive areas which their environment are exposed to demolition and destruction intensely, due to increasing and uncontrolled development. The first stage of protecting and managing the coastal areas is identifying sensitive Coastal areas and broadening the Coasts. In this survey, we attempted to examine a definite area in the southern coasts of Caspian Sea. In Iran, by profiting from the world experiences and concluded researches in Iran especially the concluded studies by marine environment office and the Environment protection organization on the subject of determination criteria of the sensitive ecological districts. For this purpose (In Gilan Province) Boujagh national park district which is located in the mouth of sefidroud river and also is possessed of the special ecological and environmental features and distinctions. In this survey, first they said district is divided proportionally on the basis of using a grid system in order to identify the sensitive ecological districts and broaden the coast, and then the desired indices have been determined and scored by numeral valuation method in each unit and then analysis has been done by using of the geography information system (GIS) and final has estimated economic valuation of sensitive ecological areas that is presented in this essay.

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In this study, numerical simulation of the Caspian Sea circulation was performed using COHERENS three-dimensional numerical model and field data. The COHERENS three-dimensional model and FVCOM were performed under the effect of the wind driven force, and then the simulation results obtained were compared. Simulation modeling was performed at the Caspian Sea. Its horizontal grid size is approximately equal to 5 Km and 30 sigma levels were considered. The numerical simulation results indicate that the winds' driven-forces and temperature gradient are the most important driving force factors of the Caspian circulation pattern. One of the effects of wind-driven currents was the upwelling phenomenon that was formed in the eastern shores of the Caspian Sea in the summer. The simulation results also indicate that this phenomenon occurred at a depth less than 40 meters, and the vertical velocity in July and August was 10 meters and 7 meters respectively. During the upwelling phenomenon period the temperatures on the east coast compared to the west coast were about 5°C lower. In autumn and winter, the warm waters moved from the south east coast to the north and the cold waters moved from the west coast of the central Caspian toward the south. In the subsurface and deep layers, these movements were much more structured and caused strengthening of the anti-clockwise circulation in the area, especially in the central area of Caspian. The obtained results of the two models COHERENS and FVCOM performed under wind driven-force show a high coordination of the two models, and so the wind current circulation pattern for both models is almost identical.

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The geological evolution of coastal and marine environments offshore the Cilento Promontory through marine geological mapping is discussed here. The marine geological map n. 502 “Agropoli,” located offshore the Cilento Promontory (southern Italy), is described and put in regional geologic setting. The study area covers water depths ranging between 30 and 200 m isobaths. The geologic map has been constructed in the frame of a research program financed by the National Geological Survey of Italy (CARG Project), finalized to the construction of an up-to-date cartography of the Campania region. Geological and geophysical data on the continental shelf and slope offshore the southern Campania region have been acquired in an area bounded northward by the Gulf of Salerno and southward by the Gulf of Policastro. A high-resolution multibeam bathymetry has permitted the construction of a digital elevation model (DEM). Sidescan sonar profiles have also been collected and interpreted, and their merging with bathymetric data has allowed for the realization of the base for the marine geologic cartography. The calibration of geophysical data has been attempted through sea-bottom samples. The morpho-structures and the seismic sequences overlying the outcrops of acoustic basement reported in the cartographic representation have been studied in detail using single-channel seismics. The interpretation of seismic profiles has been a support for the reconstruction of the stratigraphic and structural setting of the Quaternary continental shelf successions and the outcrops of rocky acoustic basement in correspondence to the Licosa Cape morphostructural high. These areas result from the seaward prolongation of the stratigraphic and structural units, widely cropping out in the surrounding emerged sector of the Cilento Promontory. The cartographic approach is based on the recognition of laterally coeval depositional systems, interpreted in the frame of system tracts of the Late Quaternary depositional sequence.

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Geographically isolated wetlands, those entirely surrounded by uplands, provide numerous ecological functions, some of which are dependent on the degree to which they are hydrologically connected to nearby waters. There is a growing need for field-validated, landscape-scale approaches for classifying wetlands based on their expected degree of connectivity with stream networks. During the 2015 water year, flow duration was recorded in non-perennial streams (n = 23) connecting forested wetlands and nearby perennial streams on the Delmarva Peninsula (Maryland, USA). Field and GIS-derived landscape metrics (indicators of catchment, wetland, non-perennial stream, and soil characteristics) were assessed as predictors of wetland-stream connectivity (duration, seasonal onset and offset dates). Connection duration was most strongly correlated with non-perennial stream geomorphology and wetland characteristics. A final GIS-based stepwise regression model (adj-R2 = 0.74, p < 0.0001) described wetland-stream connection duration as a function of catchment area, wetland area and number, and soil available water storage.

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Also shows project area, subregions, and welcome centers.