Zobrazeno 1 - 10
of 122
pro vyhledávání: '"GEORGE R. HELZ"'
Autor:
George R. Helz
Publikováno v:
Geochimica et Cosmochimica Acta. 317:507-522
Compared to continental crust, marine sediments accumulating beneath O2 depleted waters are enriched in Re and Mo, with Re/Mo ratios that vary by more than two orders of magnitude, a remarkably large range. Deposition of both elements begins simultan
Autor:
Trent P. Vorlicek, George R. Helz
Publikováno v:
Chemical Geology. 509:178-193
Molybdenum preserved in organic-rich shales is a key archive employed in studying Earth's past oxygenation and Life's evolution. In these shales, positive correlations between Mo and Corg are common and have been attributed to Mo scavenging from seaw
Publikováno v:
ACS Earth and Space Chemistry. 2:565-576
Relative to continental crust, sediments underlying sulfidic marine waters are molybdenum-rich, a property preserved in the rock record and useful for characterizing paleoenvironments. The enrichment mechanism is not agreed upon but is attributed at
Publikováno v:
Geochimica et Cosmochimica Acta. 177:105-119
Dissolved tungsten (W) and molybdenum (Mo) concentrations were measured in surface waters and sediment pore waters of Terrebonne Bay, a shallow estuary in the Mississippi River delta, to investigate the biogeochemical processes that fractionate these
Autor:
George R. Helz
Publikováno v:
Encyclopedia of Earth Sciences Series ISBN: 9783319393117
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::529a5900cad2fc32685015b5e2e891f4
https://doi.org/10.1007/978-3-319-39312-4_352
https://doi.org/10.1007/978-3-319-39312-4_352
Publikováno v:
Geochimica et Cosmochimica Acta. 144:157-172
Using UV/VIS spectrophotometry the equilibrium constants for the formation of monothiotungstate, WO3S2− ( WO 4 2 - + H 2 S ↔ WO 3 S 2 - + H 2 O; log K01 = 3.08 ± 0.11), dithiotungstate, WO2S22− ( WO 3 S 2 - + H 2 S ↔ WO 2 S 2 2 - + H 2 O; lo
Autor:
George R. Helz
Publikováno v:
Encyclopedia of Earth Sciences Series ISBN: 9783319121277
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::ee93d3803d880af05b12489206d01f8b
https://doi.org/10.1007/978-3-319-39193-9_352-1
https://doi.org/10.1007/978-3-319-39193-9_352-1
Autor:
J.M. Adelson, George R. Helz
Publikováno v:
Environmental Science & Technology. 47:1257-1264
Warm-season dead zones-volumes of coastal water containing too little O(2) to support macrofauna-are a growing global menace. Trace elements that are deposited in sediments in response to reducing or sulfidic conditions can provide proxy records for
Autor:
George R. Helz, Marvourneen K. Dolor
Publikováno v:
Chemical Geology. :131-141
Rhenium is greatly enriched in black shales and euxinic basin sediments relative to its crustal abundance. The enrichment process is generally assumed to involve reduction of ReO 4 − , the principal Re species in seawater, to an insoluble Re IV oxi
Publikováno v:
Geochimica et Cosmochimica Acta. 82:79-91
In Chesapeake Bay sediments, concentrations of 15 chalcophile trace elements, half rarely determined in estuaries, display historical profiles having remarkably similar features. All element concentrations rose more or less simultaneously in the 1920