Determination of octanol/water distribution coefficients, water solubilities, and sediment/water partition coefficients for hydrophobic organic pollutants /

Mode of access: Internet.

Hydrology, nutrient, and sediment monitoring for Hurricane and Kickapoo Creek watersheds, water year 2000-2002 : pilot watershed program /

"Prepared for the Illinois Dept. of Natural Resources."

Sediment, water and biomass characteristics along gradients in Kongsfjorden, Svalbard

In contrast to numerous studies on the biomass of marine microphytobenthos from temperate coastal ecosystems, little is known from polar regions. Therefore, microphytobenthos biomass was measured at several coastal sites in Arctic Kongsfjorden (Spitsbergen) during the polar summer (June-August 2006). On sandy sediments, chla varied between 8 and 200 mg/m**2 and was related to water depth, current/wave exposure and geographical location. Biomass was rather independent of abiotic parameters such as sediment properties, salinity, temperature or light availability. At three stations, sediments at water depths of 3-4, 10, 15, 20 and 30 m were investigated to evaluate the effect of light availability on microalgae. Significant differences in distribution patterns of biomass in relation to deeper waters >10 m were found. The productive periods were not as distinct as phytoplankton blooms. Only at 3-4 m water depth at all three stations were two- to threefold increases of biomass measured during the investigation period. Hydrodynamic conditions seemed to be the driving force for differences in sediment colonisation by benthic microalgae. In spite of the extreme Arctic environmental conditions for algal growth, microphytobenthos biomass was comparable to marine temperate waters.

Sulfate and methane concentrations measured in pore water of sediment core GeoB13809-1 and GeoB13849-1

Several previous studies have shown that submarine mass-movements can profoundly impact the shape of pore water profiles. Therefore, pore water geochemistry and diffusion models were proposed as tools for identifying and dating recent (max. several thousands of years old) mass-transport deposits (MTDs). In particular, sulfate profiles evidentially indicate transient pore water conditions generated by submarine landslides. After mass-movements that result in the deposition of sediment packages with distinct pore water signatures, the sulfate profiles can be kink-shaped and evolve into the concave and linear shape with time due to molecular diffusion. Here we present data from the RV METEOR cruise M78/3 along the continental margin off Uruguay and Argentina. Sulfate profiles of 15 gravity cores are compared with the respective acoustic facies recorded by a sediment echosounder system. Our results show that in this very dynamic depositional setting, non-steady state profiles occur often, but are not exclusively associated with mass-movements. Three sites that show acoustic indications for recent MTDs are presented in detail. Where recent MTDs are identified, a geochemical transport/reaction model is used to estimate the time that has elapsed since the perturbation of the pore water system and, thus, the timing of the MTD emplacement. We conclude that geochemical analyses are a powerful complementary tool in the identification of recent MTDs and provide a simple and accurate way of dating such deposits.

Pore water and solid-phase measurements on sediment cores from the Black Sea

The surface sediments in the Black Sea are underlain by extensive deposits of iron (Fe) oxide-rich lake sediments that were deposited prior to the inflow of marine Mediterranean Sea waters ca. 9000 years ago. The subsequent downward diffusion of marine sulfate into the methane-bearing lake sediments has led to a multitude of diagenetic reactions in the sulfate-methane transition zone (SMTZ), including anaerobic oxidation of methane (AOM) with sulfate. While the sedimentary cycles of sulfur (S), methane and Fe in the SMTZ have been extensively studied, relatively little is known about the diagenetic alterations of the sediment record occurring below the SMTZ. Here we combine detailed geochemical analyses of the sediment and pore water with multicomponent diagenetic modeling to study the diagenetic alterations below the SMTZ at two sites in the western Black Sea. We focus on the dynamics of Fe, S and phosphorus (P) and demonstrate that diagenesis has strongly overprinted the sedimentary burial records of these elements. Our results show that sulfate-mediated AOM substantially enhances the downward diffusive flux of sulfide into the deep limnic deposits. During this downward sulfidization, Fe oxides, Fe carbonates and Fe phosphates (e.g. vivianite) are converted to sulfide phases, leading to an enrichment in solid phase S and the release of phosphate to the pore water. Below the sulfidization front, high concentrations of dissolved ferrous Fe (Fe2+) lead to sequestration of downward diffusing phosphate as authigenic vivianite, resulting in a transient accumulation of total P directly below the sulfidization front. Our model results further demonstrate that downward migrating sulfide becomes partly re-oxidized to sulfate due to reactions with oxidized Fe minerals, fueling a cryptic S cycle and thus stimulating slow rates of sulfate-driven AOM (~ 1-100 pmol/cm**3/d) in the sulfate-depleted limnic deposits. However, this process is unlikely to explain the observed release of dissolved Fe2+ below the SMTZ. Instead, we suggest that besides organoclastic Fe oxide reduction, AOM coupled to the reduction of Fe oxides may also provide a possible mechanism for the high concentrations of Fe2+ in the pore water at depth. Our results reveal that methane plays a key role in the diagenetic alterations of Fe, S and P records in Black Sea sediments. The downward sulfidization into the limnic deposits is enhanced through sulfate-driven AOM with sulfate and AOM with Fe oxides may provide a deep source of dissolved Fe2+ that drives the sequestration of P in vivianite below the sulfidization front.