The extensive Argentine continental shelf supports high plankton productivity and fish catches. In particular, El Rincón coastal area and the adjacent shelf fronts (38.5-42 • S, 58.5-62 • W) comprise diverse habitats and hold species of economic and ecological value. So far, studies of the microbial community present at the base of the food web remain scarce. Here, we describe the late winter plankton (5-200 µm) structure in terms of abundance, biomass, species composition, functional groups, and phycotoxin profiles in surface waters of El Rincón in September 2015. Diatoms are the most abundant and the largest contributors to carbon biomass at most stations. They dominated the coastal and inner-shelf (depths <50 m), while dinoflagellates and small flagellates (<15 µm) dominated offshore at the middle-shelf waters (depth ∼100 m). In addition, large (>20 µm) heterotrophic protists such as various ciliates and dinoflagellates species were more abundant offshore. Scanning of phycotoxins disclosed that paralytic shellfish poisoning (PSP) toxins were dominated by gonyautoxins-1/4 (GTX1/4), whereas lipophilic toxins were detected in low abundance, for example, domoic acid (DA). However, a bloom of Pseudo-nitzschia spp. (up to 3.6 × 10 5 cells L −1) was detected at inner-shelf stations. Pectenotoxin-2 (PTX-2) and 13-desmethyl spirolide C (SPX-1) were the most abundant in the field. The PTX-2 cooccurred with Dinophysis spp., mainly D. tripos, while SPX-1 dominated at middle-shelf stations, where cells of Alexandrium catenella (1 strain) and A. ostenfeldii (3 strains) were isolated. The quantitative PSP profiles of the Alexandrium strains differed significantly from the in situ profiles. Moreover, the three A. ostenfeldii strains produced PSP and additionally, five novel spirolides. Phylogenetic analyses of these newly isolated strains
Monitoring of aerosol particle concentrations (PM 10 , PM 2.5 , PM 1 ) and chemical analysis (PM 10 ) was undertaken at a major European airport (El Prat, Barcelona) for a whole month during autumn 2007. Concentrations of airborne PM at the airport were close to those at road traffic hotspots in the nearby Barcelona city, with means measuring 48 mg PM 10 /m 3 , 21 mg PM 2.5 /m 3 and 17 mg PM 1 /m 3 . Meteorological controls on PM at El Prat are identified as cleansing daytime sea breezes with abundant coarse salt particles, alternating with nocturnal land-sourced winds which channel air polluted by industry and traffic (PM 1 /PM 10 ratios > 0.5) SE down the Llobregat Valley. Chemical analyses of the PM 10 samples show that crustal PM is dominant (38% of PM 10 ), followed by total carbon (OC + EC, 25%), secondary inorganic aerosols (SIA, 20%), and sea salt (6%). Local construction work for a new airport terminal was an important contributor to PM 10 crustal levels. Source apportionment modelling PCA-MLRA identifies five factors: industrial/traffic, crustal, sea salt, SIA, and K + likely derived from agricultural biomass burning. Whereas most of the atmospheric contamination concerning ambient air PM 10 levels at El Prat is not attributable directly to aircraft movement, levels of carbon are unusually high (especially organic carbon), as are metals possibly sourced from tyre detritus/smoke in runway dust (Ba, Zn, Mo) and from brake dust in ambient PM 10 (Cu, Sb), especially when the airport is at its most busy. We identify microflakes of aluminous alloys in ambient PM 10 filters derived from corroded fuselage and wings as an unequivocal and highly distinctive tracer for aircraft movement.
Spatial and temporal analysis of the LST-NDVI relationship for the study of land cover changes and their contribution to urban planning in Monte Hermoso, Argentina
AbstractThe aim of this work was to study the spatial distribution of Land Surface Temperature (LST) and its relationship with diverse urban land covers and the Normalized Difference Vegetation Index (NDVI). The study area was Monte Hermoso city, which is located in the southwest of Buenos Aires province, Argentina. To obtain the LST and NDVI parameters, satellite images from LANDSAT 5 TM and LANDSAT 7 ETM+ sensors were seasonally processed for the period 2008-2012. Visual interpretation techniques and empirical intervention were applied to design an urban land cover map on which LST and NDVI were analyzed by tracing four transects oriented in latitudinal and longitudinal directions. Each urban cover presented a particular behavior of these parameters. Furthermore, significant results for the relationship between LST and NDVI were observed (with α 0.1 and 0.05) with R 2 , Pearson, and Spearman indices values higher than 0.7. Finally, LST variation in diverse land covers was observed as a consequence of urban growth and the alteration of the vegetation coverage. Therefore, it was concluded that the spatial and temporal variation of LST values may indicate modifications in urban land covers. The information obtained in this study would be a useful tool to guide future urban management studies and policies. Keywords: Land Surface Temperature (LST); Normalized Difference Vegetation Index (NDVI); seasonal distribution; satellite imagery processing; Monte Hermoso
Resum. Anàlisi espacial i temporal de la relació TST-NDVI per a l'estudi dels canvis de cobertura del sòl i la seva contribució per a la planificació urbana (Monte Hermoso, Argentina)L'objectiu d'aquesta investigació va ser estudiar la distribució espacial de la temperatura de superfície terrestre (TST), la seva relació amb diferents cobertures del sòl urbà i l'índex de vegetació de diferència (NDVI). L'àrea d'estudi seleccionada va ser la ciutat costanera de Monte Hermoso, localitzada al sud-oest de la província de Buenos Aires (Argentina). Per fer-ho, es van processar imatges satel·litàries LANDSAT 5 TM i 7 ETM + per al període 2008-2012 de manera estacional. Amb aquestes imatges es va calcular la TST i l'NDVI. Posteriorment, es van aplicar tècniques d'interpretació visual i es van fer sortides al camp per dissenyar un mapa de cobertures del sòl urbà. Sobre aquestes, es va analitzar la variació de la TST i l'NDVI mitjançant el traçat de quatre transsectes orientats en sentit latitudinal i longitudinal. Cadascuna d'aquestes cobertures va presentar un comportament particular dels paràmetres calculats. D'altra banda, es van observar resultats significatius de la relació TST-NDVI (amb α de 0,1 i 0,05), amb valors de R 2 , índexs de Pearson i Spearman més grans de 0,7. Finalment, es va evidenciar que el canvi en les cobertures del sòl, producte del creixement urbà, va modificar els valors estacional...
Abstract:The aim of this study is to describe and understand the seasonal and inter-annual physical and biological dynamics of the inner and mid shelves of the Southwestern Buenos Aires Province (Argentina). We used chlorophyll-a (chl-a) concentrations and inherent optical properties (IOPs), derived from ocean color products between 2002 and 2010, as a proxy for the physical and biological parameters of interest. This study focuses on the absorption by phytoplankton, aph(443), particulate backscattering, bbp(443), and absorption due to dissolved and particulate detrital matter, adg (443), and chl-a derived from a multiband quasi-analytical algorithm (QAA). A regionalization based on the coefficient of variation and the Census X-11 method were applied to define regions and to analyze the inter-annual and seasonal variability of the ocean color parameters, with regards to climate
OPEN ACCESSRemote Sens. 2015, 7 11822 variability. The coastal zone presents the highest values of chl-a with two maxima in winter and autumn, while the mid-shelf shows a strong spring chl-a maximum. After 2009, all parameters under study shifted their seasonality and their magnitude changed over the entire area. In the coastal zone, mean values of aph(443) and bbp(443) increased, while in the mid-shelf, chl-a and aph(443) decreased. The observed inter-annual and seasonal behavior of the parameters is tightly related to climate variability of the study area.
Validation of sea-surface temperature (SST) provided by the MODIS-Aqua sensor (Moderate Resolution Imaging Spectroradiometer) for the inner and mid-shelves of the southwest of Buenos Aires Province (Argentina), is presented for the first time. In situ data obtained with a multi-parametric sonde YSI-6600 and a CTD SBE91 between 2002 and 2011 are used for comparison with the satellite SST product. The match-up exercise was established after comparing different spatial boxes, time difference windows, wind speeds, and also a coefficient of variation. The comparison exercise was made in the coastal zone and the rest of the inner and mid-shelves separately. In the coastal zone, applying a 3 × 2 pixel box and a time window of ±3 hours led to the most accurate results, with a coefficient of determination (R 2 ) of 0.99, a bias of 0.62°C, and a root-mean-square-error (RMSE) of 0.79°C. In the inner-mid-shelves when applying a coefficient of variability <0.3, a time window of ±3 hours, and taking only values of wind speed > 6 m s −1 , R 2 is 0.97, bias is 0.46°C, and RMSE is 0.95°C. Wind speed plays a major role in the inner-mid-shelves as the SST product is affected by stratification and formation of a diurnal thermocline in the 'skin and sub-skin layer' when wind speed is below 6 m s −1 . The results for the two shelves are very similar. Finally, the spatial and temporal variability of the SST satellite product was analysed in the study area for the period August 2002-December 2010. The results show that interannual variability is not significant and that there is no positive or negative trend for the 9 years of the study. Seasonality is the main component of temporal variability, with variation in amplitude signal depending on bathymetry changes, physical forcing, stability of the water column, and presence of flood plains. waters, which becomes stronger in spring (Romero et al. 2006). The highly diverse
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