prior to being transported into the lake system. The combinaThe accuracy of Arctic lake chronologies has been assessed by tion of these factors commonly leads to radiocarbon ages measuring the C activities of modern carbon sources and that are apparently too old. Discrete macrofossils are rarely applying these isotopic mass balances to dating fossil lake materifound in sufficient quantities for...

Although the principal source of marine organic matter is phytoplankton, experimental data on carbon and nitrogen mass balance during their growth cycle are lacking. Phytoplankton from diverse taxonomic groups (Synechococcus bacillaris, Phaeocystis sp., Emiliania huxleyi, Skeletonema costatum) were grown in synthetic seawater media, and changes in particulate and dissolved carbon, nitrogen, and...

The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of...

Biology and the environment interact, one shaping the other (1). In the oceans, the chemistry of seawater and the chemistry of life are intimately linked (2). In 1958, Alfred Redfield (3) noted that the microscopic plankton of the surface ocean contain carbon, nitrogen, and phosphorous atoms in a stoichiometry of ∼105:16:1 and that as these organisms sink and decay, the deep waters of the ocean...

In aquatic ecosystems, carbon (C) availability strongly influences nitrogen (N) dynamics. One manifestation of this linkage is the importance in the dissolved organic matter (DOM) pool of dissolved organic nitrogen (DON), which can serve as both a C and an N source, yet our knowledge of how specific properties of DOM influence N dynamics are limited. To empirically examine the impact of labile ...

Although the freely dissolved form of hydrophobic organic chemicals may best predict aquatic toxicity, differentiating between dissolved and particle-bound forms is challenging at environmentally relevant concentrations for compounds with low toxicity thresholds such as pyrethroid insecticides. The authors investigated the distribution of pyrethroids among 3 forms: freely dissolved, complexed w...