ARPA-E

About: ARPA-E is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Climate change. The organization has 1161 authors who have published 1267 publications receiving 30049 citations. The organization is also known as: Advanced Research Projects Agency - Energy.

Phytoplankton size structure in transitional water ecosystems: a comparative analysis of descriptive tools

Abstract: 1. Individual size has important implications for the physiology and ecology of phytoplankton. The analysis of size structure is a common approach for studying structure and function of planktonic ecosystems, with applications for the monitoring and conservation of aquatic ecosystem health. Several ways to describe the size structure of phytoplankton communities are used, including size-abundance relationships (SAR), non-normalized and normalized biomass size spectra (BSS), non-normalized and normalized number size spectra (NSS). 2. The main goal of this study was to test the effectiveness of the different tools proposed for describing and monitoring phytoplankton guilds in transitional waters. Comparative analyses were undertaken to evaluate (a) the consistency of each tool in describing the phytoplankton guilds, in terms of statistical significance and agreement with theoretical expectations; and (b) the effectiveness of each tool to discriminate conditions/cases. 3. Eleven transitional water bodies occurring along the eastern and western coasts of the Adriatic Basin were sampled in autumn 2004 and spring 2005. 4. Results obtained highlight that: (1) NSS globally showed higher statistical goodness of fit than BSS; (2) slopes of BSS and NSS, both normalized and non-normalized, were less negative than expected following the linear biomass hypothesis; and (3) the non-normalized NSS shape descriptors were best able to discriminate environmental heterogeneity both between and within transitional water ecosystems. 5. Parameters of NSS are suggested to be consistent descriptors of phytoplankton size structure and potentially important tools for monitoring and conservation of transitional water ecosystems.

Mercury Stable Isotopes Discriminate Different Populations of European Seabass and Trace Potential Hg Sources around Europe

Abstract: Our study reports the first data on mercury (Hg) isotope composition in marine European fish, for seven distinct populations of the European seabass, Dicentrarchus labrax. The use of δ202Hg and Δ199Hg values in SIBER enabled us to estimate Hg isotopic niches, successfully discriminating several populations. Recursive-partitioning analyses demonstrated the relevance of Hg stable isotopes as discriminating tools. Hg isotopic values also provided insight on Hg contamination sources for biota in coastal environment. The overall narrow range of δ202Hg around Europe was suggested to be related to a global atmospheric contamination while δ202Hg at some sites was linked either to background contamination, or with local contamination sources. Δ199Hg was related to Hg levels of fish but we also suggest a relation with ecological conditions. Throughout this study, results from the Black Sea population stood out, displaying a Hg cycling similar to fresh water lakes. Our findings bring out the possibility to use Hg is...

TXRF analysis of soils and sediments to assess environmental contamination

Abstract: Total reflection x-ray fluorescence spectroscopy (TXRF) is proposed for the elemental chemical analysis of crustal environmental samples, such as sediments and soils. A comparative study of TXRF with respect to flame atomic absorption spectroscopy and inductively coupled plasma optical emission spectroscopy was performed. Microwave acid digestion and suspension preparation methods are evaluated. A good agreement was found among the results obtained with different spectroscopic techniques and sample preparation methods for Cr, Mn, Fe, Ni, Cu, and Zn. We demonstrated that TXRF is suitable for the assessment of environmental contamination phenomena, even if the errors for Pb, As, V, and Ba are ingent.

The cases of June 2000, November 2002 and September 2002 as examples of Mediterranean floods

Abstract: . Four flood events that affected three different countries are here described in terms of meteorological genesis and in terms of consequences on the population and on the territory. Each event is a good representative of a class of phenomena that produce important effects on the urban and extra-urban tissue and that must be taken into account in an optic of civil protection and risk evaluation. This is the subject of the HYDROPTIMET project, part of the Interreg IIIB program, which is collocated in the framework of the prevention of natural hazards and, in particular, those related to severe meteo-hydrological events. This paper aims at being a general introduction of the four events which are the subject of more detailed studies, already published or under submission.