Solvent toxicity to amphibian embryos and larvae

Organic micropollutants are often damaging for aquatic organisms. Being usually hydrophobic compounds, they are often dissolved in an organic co-solvent which increases their solubility in water. The aim of this study was to study the toxicity of various solvents on embryos (protected or not by jelly coat) and on tadpoles of the common frog (Rana temporaria). Tested solvents were methanol (MeOH), methylene chloride (CH(2)Cl(2)), dimethyl sulfoxyde (DMSO), acetone (Ac) and ethanol (EtOH). Embryos exhibited higher mortality rates than tadpoles. Embryos with jelly were more sensitive to high concentration of solvents than embryos without jelly (except for acetone). According to these results, Ac, DMSO and CH(2)Cl(2) can be used as co-solvents in water to help the dissolution of micropollutants at concentration equal to or lower than 0.001 ml/l for frog embryos, and EtOH, Ac and CH(2)Cl(2) at concentration equal to or lower than 0.01 ml/l for Rana temporaria tadpoles.     

Sampling and analytical methodology development for the determination of primary and secondary low molecular weight amines in ambient air

In this project, a sampling device and an analytical method have been developed to simultaneously analyse the most frequently found low molecular weight amines, including aliphatic, aromatic and alcohol amines. These amines are diethanolamine, ethanolamine, methylamine, isopropylamine, morpholine, dimethylamine, and aniline. A sampling device was developed using a 37 mm cassette with glass fibre filters impregnated with sulfuric acid. Immediately after sampling, the filter was transferred to vials containing a solution of dansyl chloride. Dansyl chloride was used for derivatisation because it forms aromatic sulfonamides that are fluorescent and easy to protonate for MS detection. The effect of using an internal standard made with the dansylated derivative of 1-(2-methoxyphenyl)piperazine (MOPIP) on the uncertainty and efficiency of the method was also evaluated. This internal standard was spiked directly onto filters. The coupling of HPLC/ESI-MS was used for the simultaneous analysis of all the derivatives. This method showed detection limits of about 0.03 microg mL(-1) to 0.3 microg mL(-1) of amine with an average expanded uncertainty of 3% to 6% depending on the amine. The methodology recoveries are close to 100% for all the amines, and the overall estimated expanded uncertainties vary between 10% and 13% depending on the amine. This new strategy will be useful in evaluating workplace air since a unique sampling system will be used, independent of the amine to be quantified.     

A statistical approach to field measurements of the chemical evolution of cold (<0°C) snow cover

Two statistical methods for the analysis of data on the evolution of the chemical composition of cold snow (<0°C) in the field (Lac Laflamme, Quebec) were compared. The methods used on the data were regression analysis (One sample per sampling date over a long cold period) and ANOVA (replicate samples on a restricted number of sampling dates over shorter periods). The relative power of the tests to determine the detectable amplitude of chemical changes was derived from the theoretical power of the tests under comparable conditions of sampling (number of observations) and from the estimated error variances of the measured data.The results of the study on the evolution of sulfates (SO₄) concentrations in discretely identified snow strate clearly showed that for six of the eight strata, significant losses of SO₄ occurred in snow during cold periods. The relative amplitude of the significant losses varied between 1% per day and 4% per day depending on the initial concentrations in the snow and the prevailing meteorological conditions.The analysis of the data also demonstrated that for the same number of samples, the regression analysis is more efficient in detecting the chemical changes in snow than the alternative ANOVA method. The use of this information to plan sampling programs of cold snow under both field and laboratory conditions is discussed.     

Glacial-interglacial changes in the occurrence of Pb, Cd, Cu and Zn in Vostok Antarctic ice from 240 000 to 410 000 years BP

Lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) have been measured by electrothermal atomic absorption spectrometry in various sections of the 3623 m deep ice core drilled at Vostok, in central East Antarctica. The sections were dated from 240 to 410 kyear BP (Marine Isotopic Stages (MIS) 7.5 to 11.3), which corresponds to the 3rd and 4th glacial-interglacial cycles before present. Concentrations are found to have varied greatly during this 170 kyear time period, with high concentration values during the coldest climatic stages such as MIS 8.4 and 10.2 and much lower concentration values during warmer periods, such as the interglacials MIS 7.5, 9.3 and 11.3. Rock and soil dust were the dominant sources for Pb, whatever the period, and for Zn and Cu and possibly Cd during cold climatic stages. The contribution from volcanic emissions was important for Cd during all periods and might have been significant for Cu and Zn during warm periods.     

APPLICATION OF ROSGEN ANALYSIS TO THE NEW JERSEY PINE BARRENS1

ABSTRACT: Rosgen analysis, developed for assessing channel stability in streams from the western United States, is applied to the Oswego River watershed in the New Jersey Pine Barrens. The Rosgen method requires calibration to local conditions due to the impact of peat substrates on channel morphology. In particular, the presence of peat induces low width to depth ratios and greater channel confinement, reversing typical downstream morphologic trends observed in other rivers. Therefore peat is added to those substrates already evaluated by Rosgen. A consistent sequence of Rosgen stream types develops along the Oswego River and its tributaries created by spatially overlapping processes of water table emergence, peat development, and channel formation. This sequence delineates a “natural” transition of stream channel morphology downslope through the watershed. First, as the water table reaches the surface of dry sloughs, Sphagnum growth is stimulated and peat substrates result. These substrates have lower permeability than the underlying gravelly sands. Next, surface runoff, through braided pathways over the peat, eventually erodes mainly anastomosing channels into the peat. Finally, single‐thread channels develop in underlying gravelly sands further downslope. This downslope sequence, expressed as Rosgen stream types, begins generally with DA7 streams arising from dry sloughs. These pass to E7, C7 or DA5 stream types that in turn pass to B5c, C5 and C4 stream types. Departures from the “natural” stream type sequence occur along the course of the Oswego and its tributaries due to human activities such as the construction of dams, bridges and drainage ditches, stream bank erosion at streamside camping and picnic areas and the clear‐cutting of adjacent stands of Atlantic white cedar.     

Spatial variations and temporal trends between 1994 and 2005 in polychlorinated biphenyls, organochlorine pesticides and heavy metals in European eel (Anguilla anguilla L.) in Flanders, Belgium

In Flanders, the northern region of Belgium, European yellow eel muscle tissue was used as an indicator of environmental and potential human dietary exposure by hazardous chemicals of surface waters and sediments. Between 1994 and 2005, over 2800 eel captured at 365 stations were analysed for PCBs, pesticides and heavy metals. Contamination of eel in Flanders fell within the range of reported concentrations in other watersheds of Western Europe. A spatial analysis of the data demonstrated that the variation in pollutant concentration tended towards higher values. This was especially evident for PCBs, lindane, endrin, dieldrin and DDE. The concentration of almost all banned substances decreased significantly during the study period.     

The Potential Use of Synthetic Aperture Radar for Estimating Methane Ebullition From Arctic Lakes1

Abstract: Arctic lakes are significant emitters of methane (CH₄), a potent greenhouse gas, to the atmosphere; yet no rigorous quantification of the magnitude and variability of pan‐Arctic lake emissions exists. In this study, we demonstrate the potential for a new method using synthetic aperture radar (SAR) imagery to detect methane bubbles in lake ice to scale up whole‐lake measurements of CH₄ ebullition (bubbling) to regional scales. We estimated ebullition from lakes, which is often the dominant mode of lake emissions, by mapping the distribution of bubble clusters frozen in early winter ice across surfaces of seven tundra lakes and one boreal forest lake in Alaska. Applying previously measured ebullition rates associated with four distinct classes of bubble clusters found in lake ice, we estimated whole‐lake emissions from individual lakes. The percent surface area of lake ice covered with bubbles (R² = 0.68) and CH₄ ebullition rates from lakes (R² = 0.59) and were correlated with radar return values from RADARSAT‐1 Standard Beam mode 3 for the tundra lakes, suggesting that with appropriate scaling and consideration for variability in lake‐ice conditions, this technique has the potential to be used for estimating broader‐scale regional and pan‐Arctic lake methane emissions.