Particulate and dissolved fluorescent organic matter fractionation and composition: Abiotic and ecological controls in the Southern Ocean.

Phytoplankton-derived organic matter sustains heterotrophic marine life in regions away from terrestrial inputs such as the Southern Ocean. Fluorescence spectroscopy has long been used to characterize the fluorescent organic matter (FOM) pool. However, most studies focus only in the dissolved FOM fraction (FDOM) disregarding the contribution of particles.

Linking landscape heterogeneity with lake dissolved organic matter properties assessed through absorbance and fluorescence spectroscopy: Spatial and seasonal patterns in temperate lakes of Southern Andes (Patagonia, Argentina).

Hydrological connectivity between terrestrial and aquatic systems is influenced by landscape features. Topography, vegetation cover and type, lake morphometry and climate (seasonality, precipitation) drive the timing, concentration and quality of allochthonous dissolved organic matter (DOM) inputs to lakes, influencing lake metabolism. The impact of climate changes on terrestrial-aquatic linkages depends on regional trends and ecosystems properties.

Antarctic sea ice region as a source of biogenic organic nitrogen in aerosols.

Climate warming affects the development and distribution of sea ice, but at present the evidence of polar ecosystem feedbacks on climate through changes in the atmosphere is sparse. By means of synergistic atmospheric and oceanic measurements in the Southern Ocean near Antarctica, we present evidence that the microbiota of sea ice and sea ice-influenced ocean are a previously unknown significant source of atmospheric organic nitrogen, including low molecular weight alkyl-amines. Given the keystone role of nitrogen compounds in aerosol formation, growth and neutralization, our findings call for greater chemical and source diversity in the modelling efforts linking the marine ecosystem to aerosol-mediated climate effects in the Southern Ocean.

CDOM Sources and Photobleaching Control Quantum Yields for Oceanic DMS Photolysis.

Photolysis is a major removal pathway for the biogenic gas dimethylsulfide (DMS) in the surface ocean. Here we tested the hypothesis that apparent quantum yields (AQY) for DMS photolysis varied according to the quantity and quality of its photosensitizers, chiefly chromophoric dissolved organic matter (CDOM) and nitrate. AQY compiled from the literature and unpublished studies ranged across 3 orders of magnitude at the 330 nm reference wavelength.

Seasonal variability of optical properties in a highly turbid lake (Laguna Chascomús, Argentina).

We study the underwater light field seasonality in a turbid lake, Laguna Chascomús (Buenos Aires, Argentina). We report (1) relationships between optical properties (OPs) and optically active substances (OASs); (2) relationships between inherent (IOPs) and apparent (AOPs) optical properties; and (3) the seasonal variability in OASs and OPs. Light absorption was dominated by the particulate fraction.

New evidences of Roundup (glyphosate formulation) impact on the periphyton community and the water quality of freshwater ecosystems.

Argentina is the second largest world producer of soybeans (after the USA) and along with the increase in planted surface and production in the country, glyphosate consumption has grown in the same way. We investigated the effects of Roundup (glyphosate formulation) on the periphyton colonization. The experiment was carried out over 42 days in ten outdoor mesocosms of different typology: "clear" waters with aquatic macrophytes and/or metaphyton and "turbid" waters with great occurrence of phytoplankton or suspended inorganic matter.