ALBERT

Description: An increasing body of evidence suggests that much of the trace metal contamination observed in coastal waters is no longer derived from point-source inputs, but instead originates from diffuse, non-point sources. Previous research has shown that water temperature and dissolved oxygen regulate non-point source processes such as sediment diagenesis; however, limited information is available regarding the effect of these variables on toxic trace metal cycling and speciation in natural waters. Here, we present data on the seasonal variation of dissolved Cu cycling in the Long Island Sound, an urban estuary adjacent to New York City. An operationally defined chemical speciation technique based on kinetic lability and organic complexation has been applied to examine the most ecologically relevant metal fraction. In contrast to the decrease from spring to summer observed in the total dissolved Cu pool (average ± SD:  15.1 ± 4.4 nM in spring and 11.8 ± 3.5 nM in summer), our results revealed that in the highly impacted western LIS, levels of labile Cu reached higher levels in summer (range 3.6−7.7 nM) than in spring (range 1.5− 3.9 nM). Labile Cu in surface waters of the western Sound appeared to have a wastewater source during spring high flow conditions, coinciding with elevated levels of sewage-derived Ag. Labile Cu elsewhere in the LIS during spring apparently resulted from fluvial input and mixing. During summer, labile Cu increased in bottom waters (at one site, bottom water labile Cu increased from 1.5 nM in spring to 7.7 nM in summer), and covariance with tracers of diagenetic remobilization (e.g., Mn) revealed a sedimentary source. Although total dissolved Cu showed no consistent trends with water quality parameters, labile Cu in bottom waters showed an inverse correlation with dissolved oxygen and a positive, exponential correlation with water temperature. These results suggest that future increases in coastal water temperatures may cause the benthic source of labile Cu to become proportionally more significant.

Description: The origin of dissolved organic matter (DOM) within sea ice in coastal waters of the Baltic Sea was investigated using parallel factor (PARAFAC) analysis of DOM fluorescence. Sea ice DOM had distinctly different fluorescence characteristics than that of the underlying humic-rich waters and was dominated by protein-like fluorescence signals. PARAFAC analysis identified five fluorescent components, all of which were present in both sea ice and water. Three humic components were negatively correlated to salinity and concluded to be terrestrially derived material. Baltic Sea ice DOM was found to be a mixture of humic material from the underlying water column incorporated during ice formation and autochthonous material produced by organisms within the ice. Dissolved organic carbon (DOC) and nitrogen (DON) concentrations were correlated to the humic fluorescence, indicating that the majority of the organic carbon and nitrogen in Baltic Sea ice is bound in terrestrial humic material trapped within the ice. This has implications for our understanding of sea ice carbon cycling in regions influenced by riverine input (e.g., Baltic and Arctic coastal waters), as the susceptibility of DOM to degradation and remineralization is largely determined by its source.

Description: Diel cycles of dissolved cationic metal concentrations commonly occur in freshwater streams in apparent response to coincident cycles in water quality parameters (pH, O2, temperature). Hourly sampling of the Cd-contaminated Riou Mort (France) revealed large diel cycles in “total” dissolved Cd (232−357 nM; 〈0.45 μm) and “truly” dissolved Cd (56−297 nM; 〈0.02 μm) which were strongly correlated with changes in water pH. Using measured fluxes, a dissolved O2 model was constructed that indicated that benthic metabolic activities, respiration and photosynthesis, were responsible for the diel O2 (and thus, CO2 and pH) variation in the stream. However, microsensor measurements also showed that the pH changes occurred at the biofilm interface earlier than in the bulk water column. This difference in timing was reflected in the Cd dynamics, where pH-controlled sorption effects caused Cd partitioning from the truly dissolved pool onto the biofilm in the morning, and from the truly dissolved pool onto large colloids (0.02−0.45 μm) later in the day. Because this process causes large changes in the bioavailable Cd fraction, it has significant implications for Cd toxicity in freshwater streams. This study demonstrates the profound control of benthic microbiological processes on the cycling of heavy metals in aquatic systems.

Description: Six new linear peptides, pterulamides I−VI (1−6), were isolated from the fruiting bodies of a Malaysian Pterula species. The structures were elucidated by MS and 2D NMR experiments, and the absolute configurations of the constituent amino acids established using Marfey's method. The pterulamides are mainly assembled from nonpolar N-methylated amino acids and, most interestingly, have non-amino-acid N-terminal groups, among them the unusual cinnamoyl, (E)-3-methylsulfinylpropenoyl, and (E)-3-methylthiopropenoyl groups. Furthermore, pterulamides I−V are the first natural peptides with a methylamide C-terminus. Pterulamides I and IV are cytotoxic against the P388 cell line with IC50 values of 0.55 and 0.95 μg/mL (0.79 and 1.33 μM), respectively.

Description: Secretions from the paracloacal glands of alligators (Alligator spp.) and caimans (Caiman spp., Melanosuchus niger, and Paleosuchus spp.) were examined by GC-MS. The secretions of the common caiman (C. crocodilus), the broad-snouted caiman (C. latirostris), the yacare caiman (C. yacare), the dwarf caiman (P. palpebrosus), and the smooth-fronted caiman (P. trigonatus) yielded a new family of 43 aliphatic carbonyl compounds that includes aldehydes, ketones, and β-diketones with an ethyl branch adjacent to the carbonyl group. The identification of these glandular components and the syntheses and stereochemical investigations of selected compounds are described.

Description: Using HPLC/microtiter-plate-based generation of activity profiles the extract of a marine alga-derived fungus, identified as Gliocladium sp., was shown to contain the known strongly cytotoxic metabolite 4-keto-clonostachydiol (1) and also clonostachydiol (2) as well as gliotide (3), a new cyclodepsipeptide containing several d-amino acids. The absolute configuration of 1 was elucidated by reduction to 2, and two further oxidized derivatives of clonostachydiol (5, 6) were prepared and evaluated for biological activity.

Description: In a laboratory-based test series, seven experiments along a simulated Pacific hydrotherm at 152°W, 40°N were carried out to measure the rise velocities of liquefied CO2 droplets under (clathrate) hydrate forming conditions. The impact of a hydrate skin on the rising behavior was investigated by comparing the results with those from outside the field of hydrate stability at matching buoyancy. A thermostatted high-pressure tank was used to establish conditions along the natural oceanic hydrotherm. Under P-/T-conditions allowing hydrate formation, the majority of the droplets quickly developed a skin of CO2 hydrate upon contact with seawater. Rise rates of these droplets support the parametrization by Chen et al. (Tellus 2003, 55B, 723−730), which is based on empirical equations developed to match momentum of hydrate covered, deformed droplets. Our data do not support other parametrizations recently suggested in the literature. In the experiments from 5.7 MPa, 4.8 °C to 11.9 MPa, 2.8 °C positive and negative deviations from predicted rise rates occurred, which we propose were caused by lacking hydrate formation and reflect intact droplet surface mobility and droplet shape oscillations, respectively. This interpretation is supported by rise rates measured at P-/T-conditions outside the hydrate stability field at the same liquid CO2-seawater density difference (Δρ) matching the rise rates of the deviating data within the stability field. The results also show that droplets without a hydrate skin ascend up to 50% faster than equally buoyant droplets with a hydrate skin. This feature has a significant impact on the vertical pattern of dissolution of liquid CO2 released into the ocean. The experiments and data presented considerably reduce the uncertainty of the parametrization of CO2 droplet rise velocity, which in the past emerged partly from their scarcity and contradictions in constraints of earlier experiments.