47 research outputs found
Determination of Total Mercury in Waters and Urine by Flow Injection Atomic Absorption Spectrometry Procedures involving On- and Off-line Oxidation of Organomercury Species
Determination of total mercury in waters and urine by flow injection atomic absorption spectrometry procedures involving on- and off-line oxidation of organomercury species
Effect of long-term dietary lead exposure on some maturation and reproductive parameters of a female Prussian carp (Carassius gibelio B.)
Lead accumulation and elimination in tissues of Prussian carp, Carassius gibelio (Bloch, 1782), after long-term dietary exposure, and depuration periods
Phosphorus in sediments of high-elevation lakes in the Sierra Nevada (California): implications for internal phosphorus loading
In high-elevation lakes of the Sierra Nevada (California), increases in phosphorus (P) supply have been inferred from changes in phytoplankton growth during summer. To quantify rates of sediment P release to high-elevation Sierran lakes, we performed incubations of sediment cores under ambient and reducing conditions at Emerald Lake and analyzed long-term records of lake chemistry for Emerald and Pear lakes. We also measured concentrations of individual P forms in sediments from 50 Sierra Nevada lakes using a sequential fractionation procedure to examine landscape controls on P forms in sediments. On average, the sediments contained 1,445 µg P g−1, of which 5 % was freely exchangeable, 13 % associated with reducible metal hydroxides, 68 % associated with Al hydroxides, and the remaining 14 % stabilized in recalcitrant pools. Multiple linear regression analysis indicated that sediment P fractions were not well correlated with soluble P concentrations. In general, sediments behaved as net sinks for P even under reducing conditions. Our findings suggest that internal P loading does not explain the increase in P availability observed in high-elevation Sierran lakes. Rather, increased atmospheric P inputs and increased P supply via dissolved organic C leaching from soils may be driving the observed changes in P biogeochemistry