By using high-performance size exclusion chromatography (HPSEC) and reversed-phase liquid with on-line three-dimensional excitation emission matrix fluorescence detection, we measured properties of natural organic matter (NOM) as a function molecular (MS) polarity. The work was carried out Suwannee River Fulvic Acid, Aldrich Humic naturally occurring river NOM sample. Significant differences in maximum pattern were found separated chromatographically based on MS There existed strong...

A method was developed to measure mercury methylation and demethylation rate constants simultaneously in aquatic samples. Solutions containing stable isotope tracers of 199Hg2+ CH3202Hg+ were spiked into lake sediments at subambient concentrations. The formation CH3199Hg+ the decrease measured time series experiments using gas chromatographic separation isotope-specific detection by inductively coupled plasma mass spectrometry. Specific for two processes calculated compared obtained...

A novel technique for the calculation of mercury methylation rates in sediments by using enriched stable isotopes is described. The method takes advantages ability an inductively coupled plasma mass spectrometry (ICP-MS) instrument to measure individual isotopes. An ICP-MS was used as a detector determination methylmercury compounds after separation gas chromatography (GC). CH3Hg+ isolated from distillation, converted methylethylmercury sodium tetraethylborate and analysed purge-and-trap...

Humic and fulvic acids from lakes in Ontario, Canada, have been isolated examined for their ability to bind methylmercury(II). Equilibrium dialysis has applied differentiate between bound unbound fractions of MeHg(II). Losses methylmercury(II) solutions containing 0.5−100 ng/L MeHg(II) 10 mg/L humic substances (HS) are negligible over a 24-h time interval when using acid-cleaned glass beakers, membrane closures, cellulose ester membranes having molecular weight cutoff 500. Dialysis...

Abstract Methylmercury (MeHg) accumulation in rice has great implications for human health. Here, effects of selenium (Se) on MeHg availability to are explored by growing under soil or foliar fertilization with Se. Results indicate that amendment Se could reduce levels and grain (maximally 73%). In contrast, enhanced plant (3–12 folds) without affecting concentrations. This evidence, along the distinct distribution within plant, demonstrate first time Se-induced reduction (i.e., MeHg-Se...

Uranium contamination of surface environments is a problem associated with both U-ore extraction/processing and situations in which groundwater comes into contact geological formations high uranium. Apart from the environmental concerns about U contamination, its accumulation isotope composition have been used marine sediments as paleoproxy Earth's oxygenation history. Understanding geochemistry then essential either to develop sustainable remediation procedures well for use paleotracer...

Lead-210 dating was used to measure rates of sediment accumulation in 15 cores from Bob Lake, Ontario. The rate highly correlated with sample depth. This relation allowed the calculation sediments over whole lake area. Phosphorus (P) retention calculated mean concentration P and sediment. Retention this way similar previously measured input output P.Key words: lead-210 dating, accumulation, phosphorus

Sediment traps were used to estimate the downward flux of total phosphorus, Kjeldahl nitrogen, and iron in a small Precambrian shield lake for 4 yr. The as determined by sediment trap method was much higher than retention same elements measured mass balance methods (input–outflow). Total phosphorus (TP) sedimentation about 17 times while N three Fe 31 higher. Very high N/P ratios epilimnetic waters (36/1 weight) low material (8/1) surficial sediments (mean 8/1, range 4–11/1), conjunction...

The effects of methylmercury (MeHg) on components the cholinergic system were evaluated in captive mink (Mustela vison). Cholinergic parameters measured brain regions (occipital cortex, cerebellum, stem, basal ganglia) and blood (whole blood, plasma, serum) following an 89-day exposure to MeHg at dietary concentrations 0, 0.1, 0.5, 1, 2 ppm (n = 12 animals per treatment). There no choline acetyltransferase, acetylcholine, transporter. However, significantly higher densities muscarinic...

A rapid technique for the determination of Pu in urine samples using flow injection (FI) on-line preconcentration, desolvation nebulization a highly sensitive APEX device and inductively coupled plasma mass spectrometry with dynamic reaction cell (ICP-DRC-MS) was developed. Using DRC avoided necessity to separate from U, thus made more rapid. Effective preconcentration matrix separation achieved TRU resin as ion exchanger. detection limit 242Pu 1.9 pg L−1 raw, undigested 10 ml sample volume....

Research Article| April 01, 1941 Age measurements by radioactivity CLARK GOODMAN; GOODMAN Search for other works this author on: GSW Google Scholar ROBLEY D. EVANS GSA Bulletin (1941) 52 (4): 491–544. https://doi.org/10.1130/GSAB-52-491 Article history received: 09 Jan first online: 02 Mar 2017 Cite View This Citation Add to Manager Share Icon Twitter LinkedIn Tools Get Permissions Site GOODMAN, EVANS; radioactivity. 1941;; doi: Download citation file: Ris (Zotero) Refmanager EasyBib...

Abstract Acid-volatile sulfide (AVS) is an operational definition for the sulfides removed from sediment by cold acid extraction. It has been proposed that this fraction could be used as indicator of divalent metal toxicity (e.g., Cd, Ni, Hg), it increases metal-binding capacity sediments and hence renders metals unavailable to biota. Before AVS can a predictive tool in freshwater systems, we must develop better understanding impact seasonal turnover events on its geochemistry. An in-depth...