Distribution and ratios of Cs and K in control and K-treated coconut trees at Bikini Island where nuclear test fallout occurred: effects and implications

Coconut trees growing on atolls of the Bikini Islands are on the margin of K deficiency because the concentration of exchangeable K in coral soil is very low, ranging from only 20 to 80 mg kg⁻¹. When provided with additional K, coconut trees absorb large quantities of K and this uptake of K significantly alters the patterns of distribution of ¹³⁷Cs within the plant. Following a single K fertilization event, mean total K in trunks of K-treated trees is 5.6 times greater than in trunks of control trees. In contrast, ¹³⁷Cs concentration in trunks of K-treated and control trees is statistically the same while ¹³⁷Cs is significantly lower in edible fruits of K-treated trees. Within one year after fertilization (one rainy season), K concentration in soil is back to naturally low concentrations. However, the tissue concentrations of K in treated trees stays very high internally in the trees for years while ¹³⁷Cs concentration in treated trees remains very low in all tree compartments except for the trunk. Potassium fertilization did not change soil Cs availability.     

Urinary and serum metabolites of di-n-pentyl phthalate in rats

Di-n-pentyl phthalate (DPP) is used mainly as a plasticizer in nitrocellulose. At high doses, DPP acts as a potent testicular toxicant in rats. We administered a single oral dose of 500 mg kg⁻¹ bw of DPP to adult female Sprague-Dawley rats (N = 9) and collected 24-h urine samples 1 d before and 24- and 48-h after DPP was administered to tentatively identify DPP metabolites that could be used as exposure biomarkers. At necropsy, 48 h after dosing, we also collected serum. The metabolites were extracted from urine or serum, resolved with high performance liquid chromatography, and detected by mass spectrometry. Two DPP metabolites, phthalic acid (PA) and mono(3-carboxypropyl) phthalate (MCPP), were identified by using authentic standards, whereas mono-n-pentyl phthalate (MPP), mono(4-oxopentyl) phthalate (MOPP), mono(4-hydroxypentyl) phthalate (MHPP), mono(4-carboxybutyl) phthalate (MCBP), mono(2-carboxyethyl) phthalate (MCEP), and mono-n-pentenyl phthalate (MPeP) were identified based on their full scan mass spectrometric fragmentation pattern. The ω − 1 oxidation product, MHPP, was the predominant urinary metabolite of DPP. The median urinary concentrations (μg mL⁻¹) of the metabolites in the first 24 h urine collection after DPP administration were 993 (MHPP), 168 (MCBP), 0.2 (MCEP), 222 (MPP), 47 (MOPP), 26 (PA), 16 (MPeP), and 9 (MCPP); the concentrations of metabolites in the second 24 h urine collection after DPP administration were significantly lower than in the first collection. We identified some urinary metabolic products in the serum, but at much lower levels than in urine. Because of the similarities in metabolism of phthalates between rats and humans, based on our results and the fact that MHPP can only be formed from the metabolism of DPP, MHPP would be the most adequate DPP exposure biomarker for human exposure assessment. Nonetheless, based on the urinary levels of MHPP, our preliminary data suggest that human exposure to DPP in the United States is rather limited.     

A new reliable method for dimethyl sulfoxide analysis in wastewater: dimethyl sulfoxide in Philadelphia's three water pollution control plants.

A simple but reliable procedure was developed to analyze dimethyl sulfoxide (DMSO) in wastewater. The isotope DMSO_d6 was used as the internal standard to ensure accuracy. The DMSO was reduced with stannous chloride and measured as dimethyl sulfide (DMS) with purge-and-trap gas chromatography/mass spectrometry. The method detection limit was at the sub-microgram-per-milliliter level; precision, as measured by standard deviation, was better than +/- 0.5%; and the recoveries were between 95 and 105% at the level of 2 microg/mL. The procedure could use standard analytical instrumentation used for volatile organic compound analysis. A field study was conducted to validate the method and quantify DMSO concentration range in the three water pollution control plants (WPCPs) in the city of Philadelphia, Pennsylvania. Results showed that, when a local chemical facility discharged, DMSO concentration could be as high as 12 mg/L in the influent to a WPCP. This would lead to the formation of a toxic "canned corn" DMS odor during the treatment processes.