Overlying water incubations

Table 1. Fluxes of Mn (mmol/m2/d) and As (x10 3 mmol/m2/d) in short-term, duplicate and triplicate incubations of cores at three overlying water oxygen concentrations. A/D no data, - core not incubated,

Benthic substrate, which consisted of mediumgrained sands with shells and biotic remains, was hand-collected by SCUBA divers from 12 m depth in a coastal embayment near Bergen, Norway on March 14, 2003. The sediments were kept isolated from the overlying water during collection and experimental preparation, and were overlaid with filtered seawater during incubation. A set of 20 cc aliquots of drained but damp sediments were placed in the bottom of triplicate 250 ml PC bottles and gradually overlaid with 200 ml of the following water types artificial... 

Evidence for the presence of hyperglycemic factors in the CC were reported first in P. americana (1) and supported subsequently in B. discoidalis (3). The HGHs act on the fat body, the synthetic source for trehalose in insects (22), to elevate phosphorylase activity and the conversion of glycogen stores to the precursors for trehalose synthesis (2,3). Initially, it was believed that HGHs activated phosphorylase via the synthesis of adenosine 3 5 -cyclic monophosphate (cAMP) in the same manner that glucagon or epinephrine activate liver phosphorylase in vertebrate animals (23). Injections of intact adult P. americana with synthetic Pea-CAH-I and -II result in a 50% net increase in fat body cAMP over water-injected controls accompanied by a more than 3-fold increase in fat body phosphorylase activity (24). However, the CAHs fail to elevate cAMP levels of fat bodies from P. americana in vitro even though both phosphorylase activity and trehalose synthesis increase (25). In the latter case, Ca + is essential for the action of the CAHs, and its omission from the incubation medium inhibits the hypertrehalosemic response. 

Recently, Devol et al. (2006) have used on-deck and in situ incubation of water samples with added N03 to determine the rate of denitrification by measuring the rate of production. Although these were not true tracer experiments, as the in vitro N03 concentrations were increased 5 iM over the in situ concentration of 25 pM, it is likely that rates were not stimulated by the amendment. In the Arabian Sea ODZ the of the N2 typically increased by 0.4-0.8%o. The average... 

Another variation on a theme includes AATCC 30 Soil Burial Test (a. 11). A temperature of 28 °C, relative humidity of 85% and water content of 20-30% for incubation over 16 weeks is the change in essential criteria. 

The maximum expected steady-state flux of Fe from NWC sediments into overlying water is approximately /pe = RL, where L is the thickness of the modeled interval and R is the constant Fe dissolution rate in that interval. Calculated fluxes range from 7-34 mmoles/mVday and are considerably higher (10-100 x) than directly estimated fluxes from incubated box cores (Tables I and V). This is consistent with the rapid oxidation kinetics of Fe in seawater (Aston and Chester, 1973 Kester et al., 1975) and the expected precipitation of most mobilized Fe from solution as the oxygenated interface is approached. 

Overlying water incubations with intact cores ... 

The temperature of the water bath is controlled as needed, but under most conditions in situ water column temperatures are maintained. Prior to starting the core flux measurements, the overlying water is removed from each core, filtered through a 0.45 pm pore size polyethersulfone filter and gently replaced into the respective cores to a final water column depth of approximately 15 cm. The water column is slowly bubbled with ambient air throughout the incubation period, both to ensure an aerobic water column and to completely mix the water column. Small aliquots ( 20 mL) of water samples are collected and prepared for analysis of desired solutes. 

Digitalis glycosides Apply sample solution as band and then luizyme solution over it if necessary, moisten the application zone with water. Cover the layer, except for the application zone, with a glass plate and incubate at 39 °C for 2 to 5 h. [37]... 

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