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Sunday, June 6, 2010

The Carbon Isotopic Composition of Trihalomethanes Formed from Chemically Distinct Dissolved Organic Carbon Isolates from the Sacramento-San Joaquin River Delta, California, USA.

. Sunday, June 6, 2010
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Abstract

Dissolved hydrophobic and hydrophilic acids were isolated from samples collected at five channel sites within the Sacramento-San Joaquin Rivers and Delta, California, USA, and from a peat island agricultural drain to examine the relationship between the chemical composition of dissolved organic carbon and the formation of trihalomethane, and to test whether peat island-derived dissolved organic carbon contributed substantially to reactivity. The chemical composition of the isolates was quite variable, as indicated by significant differences in carbon-13 nuclear magnetic resonance spectra and carbon to nitrogen concentrations ratios, though the variability was not consistent with simple mixing of river- and peat-derived dissolved organic carbon. The lowest propensity to form trihalomethane observed was in the peat island agricultural drain sample, suggesting the addition of peat island waters into Delta channels did not increase the amount of trihalomethane formed from channel water dissolved organic carbon. Changes in the chemical and isotopic composition of the isolates suggest the source of the trihalomethane precursors was different among samples and between isolates. The carbon isotopic composition of the trihalomethane formed from the isolates generally tracked the carbon isotopic composition of the isolates themselves, but variability in the carbon isotopic composition of the trihalomethane was higher.

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Seville (sour) Orange Juice: Synephrine Content and Cardiovascular Effects in Normotensive Adults

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Abstract

The Seville orange extract Citrus aurantium contains m-synephrine (phenylephrine) and octopamine; it causes cardiac disturbances in animals and is used by humans for weight loss. Juice from the orange (Seville orange juice [SOJ]) is used to “knock out” intestinal cytochrome P450 (CYP) 3A4 in bioavailability studies. The purpose of this study was to determine synephrine and octopamine concentrations in SOJ and SOJ’s cardiovascular effects in normotensive humans. Subjects consumed 8 ounces of SOJ and water in crossover fashion followed by a repeat ingestion 8 hours later. Hemodynamic (heart rate; systolic, diastolic, and mean arterial pressure) measurements followed. Synephrine and octopamine were determined by high-performance liquid chromatography. Hemodynamics did not differ significantly between water and SOJ groups. Mean synephrine concentration of SOJ samples was 56.9 ± 0.52 μg/ml; octopamine was not detected. SOJ ingestion by normotensive subjects is expected to be safe. Individuals with severe hypertension, tachyarrhythmias, and narrow-angle glaucoma and monoamine oxidase inhibitor recipients should avoid SOJ consumption. Persons taking decongestant-containing cold preparations should also refrain from SOJ intake.

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Production of dissolved organic carbon (DOC) and trihalomethane (THM) precursor from peat soils

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Abstract

Water passing through the Sacramento-San Joaquin Delta contains elevated concentrations of dissolved organic carbon (DOC) and trihalomethane (THM) precursor relative to upstream waters from the Sacramento River and the San Joaquin River. Drainage from agricultural peat soils has been identified as one of the major sources of DOC and THM precursor. A series of controlled laboratory experiments were conducted to evaluate abiotic and biotic effects on the quantity and the nature of DOC and THM precursors produced from oxidized surface and reduced subsurface soils in the Delta. 

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Friday, June 4, 2010

PRIORITY SUBSTANCES LIST STATE OF THE SCIENCE REPORT FOR ALUMINUM CHLORIDE, ALUMINUM NITRATE AND ALUMINUM SULFATE

. Friday, June 4, 2010
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Synopsis

In Canada, pulp and paper mills and municipal water treatment plants (either drinking water or wastewater) are major users of aluminum chloride, aluminum nitrate and aluminum sulfate. They account for about 75% of the 270 000 tonnes of aluminum salts used in Canada in 1996. 

Aluminum sulfate can enter the Canadian environment from natural sources in restricted geological environments; however, since aluminum is present in most rocks, dominantly in aluminosilicate minerals, which weather and slowly release aluminum to the surface environment, releases of aluminum from aluminum sulfate cannot be distinguished from other natural aluminum releases. During their use in water treatment, aluminum salts react rapidly, producing dissolved and solid forms of aluminum, and some are released to Canadian surface waters. The amount of anthropogenic aluminum released is small compared with natural aluminum releases. Concentrations of aluminum are highest in wastewaters released by drinking water treatment plants (DWTPs). However, direct releases of process waters from DWTPs are regulated by many provincial authorities, and these releases typically occur in circumneutral water, where aluminum’s solubility is minimal. Disposal of sludge produced by DWTPs on land through landfarming practices is a source of aluminum to the terrestrial environment. However, the presence of dissolved organic matter and inorganic chelating agents will lower the amount of bioavailable aluminum in both the terrestrial and aquatic environments.

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Photo-oxidation of dissolved organic matter in river water and its effect on trace element speciation

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Abstract

To investigate the effect of photodegradation of fluvial dissolved organic matter (DOM) on dissolved trace element distributions, we performed a 3-week incubation of water from the lower Pearl River (Mississippi). The experiment was performed in natural light (with dark controls) and examined both the changes in DOM and changes in physical–chemical speciation of a suite of trace metals. During the incubation, dissolved organic carbon (DOC) decreased in the light by about 20%, whereas ultraviolet light absorbance decreased by nearly 40%; dark controls showed no significant change in DOC. For the trace elements, a variety of behaviors were observed. Some elements (alkali and alkaline earth metals, Mo, Mn, Cd, and Zn) showed no change in concentration or speciation. A number of elements, however, did show significant changes in the light. For example, there was a significant, continuous decrease in dissolved (,0.02-mm) Fe in the light samples during the experiment. This and other speciation results indicate that organically complexed Fe was released during photo-oxidation of the lowmolecular- weight DOM; this was followed by subsequent precipitation of the released Fe as additional colloidal FeOOH. Other elements (Ce, Cu, Cr, Pb, V, and U) also showed decreases in the dissolved (,0.02-mm) fraction with time. Some of these elements, as well as Co and Ni, also showed decreases in their retention by an anion exchange column, likewise implying a decrease in their organically complexed forms.

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