Factors affecting phosphate adsorption to aluminum in lake water: implications for lake restoration.

Treatment of lake inlets or lake sediments with aluminum (Al) is being increasingly used for lake restoration but only few studies exist concerning competitive substances that might influence phosphate (PO(4)(3-)) removal from lake water. Therefore, chemical interferences of several ions (magnesium, silicate, chloride and humic acid) on PO(4)(3-) adsorption to Al(OH)(3) were studied. Interference of each ion was studied in artificial lake water, and the complex interactions occurring in natural water were studied in water from 30 Danish lakes at pH 7 in both cases. In the artificial lake water Al:P ratio was high as sediment P-pools were the targets while in the natural lake water Al addition was generally lower as only P present in the water was targeted (i.e. inlet water). The single-ion experiments evidenced that silicate (>200 microM) and humic acids significantly decreased the effectiveness of PO(4)(3-) adsorption to Al(OH)(3) by 10-13% at 450 microM Si and 17% at 1 mM C, respectively. NaCl did not influence adsorption of PO(4)(3-) to Al(OH)(3), however, PO(4)(3-) removal was slightly reduced in seawater, mainly due to the presence of Mg(2+). The studies on interferences in natural lake water showed that as long as the PO(4)(3-) concentration was low (<5 microM), silicate competed with PO(4)(3-) for adsorption sites on Al(OH)(3) but at higher PO(4)(3-) concentrations, color and DOC (as indicators of HA) were the main variables decreasing PO(4)(3-) removal from lake water. Inhibition of PO(4)(3-) precipitation in natural lake water appeared complex and did not allow for a simple calculation of Al dose from the concentration of potentially competitive ions. Recommendation for lake management is therefore still that precipitation assays should be carried out for any type of inlet or lake water prior to Al application.

Embryonic nutrition, growth and energetics in Zoarces viviparus L. as indication of a maternal-fetal trophic relationship.

The embryos of Zoarces viviparus (L.) show linear growth during their intraovarian development. In early gestation before hatching, the embryos take up very small amounts of low molecular tracer compounds such as glucose, glycine or taurine. Later in gestation (two months after hatching), the embryos accumulate substantial amounts of the tracer compounds. The uptake rates of the tracer compounds in vitro are correlated with ambient concentrations of unlabelled compounds within the natural concentration range of the ovarian fluid. The highest uptake rates are found for glucose and the lowest for taurine. Release of 14CO2 and dissolved organic carbon (DO14C) from assimilated tracers in the embryos is low. Oxygen uptake and body weight of the embryos appear to be linearly correlated, and the average oxygen uptake is 4.20 (SD 0.73) mumol O2 g-1 h-1 WW at 11 degrees C. The contribution of glucose respiration to total aerobic respiration is 13.9%. A growth to respiration ratio of 0.91 indicates a relatively high efficiency for converting food to growth.

Suprapubic prostatectomy. The removable purse string: a continuing comparative analysis of 300 consecutive cases.

Mortality rates, length of hospitalization, transfusion requirements, weights of excised tissue, complications and operating time are analyzed in this series of 300 patients who underwent suprapubic prostatectomies in which a removable purse-string closure of the bladder neck was used. The results are compared to those in other studies. The mortality rate in our study is the lowest reported to date for a large series. We believe that this technically simple operation, which has the most adaptability for combination with conjunctive operations, low transfusion requirements, few long-term complications and which can be done rapidly, is the most desirable method to remove benign prostates of 40 gm. or larger. We believe that there should be acceptance of broader indications for its use and that greater emphasis should be placed on teaching this procedure in urological training programs.