A Spatially Detailed and Economically Complete Blue Water Footprint of the United States
This paper quantifies and maps a spatially detailed and economically complete blue water footprint for the United States, utilizing the National Water Economy Database version 1.1 (NWED). NWED utilizes multiple mesoscale federal data resources from the United States Geological Survey (USGS), the United States Department of Agriculture (USDA), the U.S. Energy Information Administration (EIA), the U.S. Department of Transportation (USDOT), the U.S. Department of Energy (USDOE), and the U.S. Bureau of Labor Statistics (BLS) to quantify water use, economic trade, and commodity flows to construct this water footprint. Results corroborate previous studies in both the magnitude of the U.S. water footprint (F) and in the observed pattern of virtual water flows. The median water footprint (FCUMed) of the U.S. is 181&thinsp;966&thinsp;Mm3 (FWithdrawal: 400&thinsp;844&thinsp;Mm3; FCUMax: 222&thinsp;144&thinsp;Mm3; FCUMin: 61&thinsp;117&thinsp;Mm3) and the median per capita water footprint (F'CUMed) of the U.S. is 589&thinsp;m3&thinsp;capita&minus;1 (F'Withdrawal: 1298&thinsp;m3&thinsp;capita&minus;1; F'CUMax: 720&thinsp;m3&thinsp;capita&minus;1; F'CUMin: 198&thinsp;m3&thinsp;capita&minus;1). The U.S. hydro-economic network is centered on cities and is dominated by the local and regional scales. Approximately (58&thinsp;%) of U.S. water consumption is for the direct and indirect use by cities. Further, the water footprint of agriculture and livestock is 93&thinsp;% of the total U.S. water footprint, and is dominated by irrigated agriculture more »
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NSF-PAR ID:
10105095
Journal Name:
Hydrology and Earth System Sciences Discussions
Page Range or eLocation-ID:
1 to 54
ISSN:
1812-2116
1. Abstract. Triplet excited states of organic matter are formed when colored organicmatter (i.e., brown carbon) absorbs light. While these “triplets” can beimportant photooxidants in atmospheric drops and particles (e.g., theyrapidly oxidize phenols), very little is known about their reactivity towardmany classes of organic compounds in the atmosphere. Here we measure thebimolecular rate constants of the triplet excited state of benzophenone(3BP), a model species, with 17 water-solubleC3C6 alkenes that have either been found in theatmosphere or are reasonable surrogates for identified species. Measured rateconstants (${k}_{\mathrm{ALK}+\mathrm{3}{\mathrm{BP}}^{\ast }}$) vary by a factor of 30 and are in therange of (0.24–7.5)&thinsp;×109&thinsp;M−1&thinsp;s−1. Biogenic alkenesfound in the atmosphere – e.g., cis-3-hexen-1-ol, cis-3-hexenyl acetate, andmethyl jasmonate – react rapidly, with rate constants above 1×109&thinsp;M−1&thinsp;s−1. Rate constants depend on alkene characteristicssuch as the location of the double bond, stereochemistry, and alkylsubstitution on the double bond. There is a reasonable correlation between${k}_{\mathrm{ALK}+\mathrm{3}{\mathrm{BP}}^{\ast }}$ and the calculated one-electron oxidation potential(OP) of the alkenes (more »); in contrast, rate constants are notcorrelated with bond dissociation enthalpies, bond dissociation freeenergies, or computed energy barriers for hydrogen abstraction. Using the OPrelationship, we estimate aqueous rate constants for a number of unsaturatedisoprene and limonene oxidation products with 3BP: values are inthe range of (0.080–1.7)&thinsp;×109&thinsp;M−1&thinsp;s−1, withgenerally faster values for limonene products. Rate constants with lessreactive triplets, which are probably more environmentally relevant, arelikely roughly 25 times slower. Using our predicted rate constants, alongwith values for other reactions from the literature, we conclude thattriplets are probably minor oxidants for isoprene- and limonene-relatedcompounds in cloudy or foggy atmospheres, except in cases in which the tripletsare very reactive.