The continuing digital transformation of the New York Times by Arthur Sulzberger

The chairman of the New York Times Arthur Sulzberger gave a talk at Polis LSE on the continuing digital transformation of the New York Times on November 1st

Chemical characterization of dissolved organic matter (DOM): A prerequisite for understanding UV-induced changes of DOM absorption properties and bioavailability

Abstract.: UV-induced transformations of colored dissolved organic matter (CDOM, which is part of dissolved organic matter, DOM) affect CDOM absorption properties resulting in the loss of color (referred to as photobleaching). CDOM photobleaching increases the penetration depths of the damaging UV-B radiation into water bodies and strongly depends on the wavelength of solar radiation and on the pH of aquatic systems. UV-induced transformations also affect DOM availability to bacterioplankton, often enhancing the bioavailability of terrigenous DOM and in turn microbial respiration. The combination of UV-induced enhancement of DOM bioavailability and increased export of terrigeneous DOM into estuaries and coastal waters due to climate-related changes in continental hydrology could result in a UV-mediated positive feedback of CO2 accumulation in the atmosphere. The extent and type of CDOM photobleaching and of UV-induced changes in DOM bioavailability depend on (C)DOM chemical composition, which in turn undergoes drastic changes upon UV-induced transformations. Therefore, the chemical characterization of (C)DOM is key for rationalizing UV-induced transformations. In the second section (after the "Introduction”), we review important methods for the elucidation of the chemical composition of (C)DOM. However, this article is not intended to be comprehensive regarding (C)DOM chemical characterization. An important purpose is to provide photochemical bases for the understanding of UV-induced changes of (C)DOM absorption properties and bioavailability (mainly discussed in the sections "Pathways of DOM phototransformations” and ”UV-induced changes of the absorption properties of CDOM”

Sources and distribution of organic carbon and nitrogen in the Tagliamento River, Italy

Abstract.: Elemental carbon (C) and nitrogen (N) concentrations, C:N ratios, and stable C and N isotopic compositions (δ13C and δ15N) were used to determine the sources of riverine solid phase extracted and ultrafiltered dissolved organic matter (DOM) and suspended fine particulate organic matter (FPOM). DOM and FPOM as well as potential source materials were seasonally collected in downstream direction along the last large semi-natural river draining the European Alps, the Tagliamento River (Italy). These investigations suggest that the major sources of FPOM and solid phase extracted and ultrafiltered DOM in this river are a mixture of river-borne bacterial and microalgal biomass and soil-derived organic matter. Low C:N ratios of FPOM and bulk DOM, compared to DOM isolates, further indicate that FPOM is highly reactive and that its degradation releases bioavailable DOM compounds. Downstream abundance and distribution of organic C and N were also compared to inorganic nutrient concentrations and indicate that FPOM remineralization is a major pathway for the formation of inorganic nutrients in Tagliamento surface water