Validation of a flow-through sampler for pesticides and polybrominated diphenyl ethers in air

At locations without access to the electrical grid, a flow-through sampler (FTS) collects large volumes of air for the analysis of semi-volatile organic compounds (SVOCs). To test its performance under field conditions, an FTS and a traditional pumped high volume air sampler, both using polyurethane foam (PUF) as sampling medium, were co-deployed at the campus of the University of Toronto Scarborough from August 2006 to June 2007. Polybrominated diphenyl ethers (PBDEs) and various pesticides were quantified in the samples taken by both samplers to test the FTS's applicability to relatively non-volatile and slightly polar SVOCs. Air concentrations in samples taken with the FTS over five 2-week periods compare favourably with the average of the concentrations in several 24-h active high volume samples taken during the same period. In particular, time trends, temperature dependence relationships, and isomer ratios show a reasonable agreement between the two sampling techniques. An empirical linear solvation energy relationship for predicting the apparent theoretical plate number of the PUF assembly used in the FTS illustrates the effect of chemical properties, as well as temperature and wind speed, on sampling efficiency. In the absence of electrical power, the FTS can collect SVOCs from large air volumes as reliably and quantitatively as traditional HiVol samplers, although without separating gas and particle phase.     

Soil metal concentrations and vegetative assemblage structure in an urban brownfield

Anthropogenic sources of toxic elements have had serious ecological and human health impacts. Analysis of the soil samples from a brownfield within Liberty State Park, Jersey City, NJ, USA, showed that arsenic, chromium, lead, zinc and vanadium exist at concentrations above those considered ambient for the area. Accumulation and translocation features were characterized for the dominant plant species of four vegetative assemblages. The trees Betula populifolia and Populus deltoides were found to be accumulating Zn in leaf tissue at extremely high levels. B. populifolia, P. deltoides and Rhus copallinum accumulated Cr primarily in the root tissue. A comparison of soil metal maps and vegetative assemblage maps indicates that areas of increasing total soil metal load were dominated by successional northern hardwoods while semi-emergent marshes consisting mostly of endemic species were restricted primarily to areas of low soil metal load.     

Effect of phosphogypsum and dicyandiamide as additives on NH3, N2O and CH4 emissions during composting

A laboratory scale experiment of composting in a forced aeration system using pig manure with cornstalks was carried out to investigate the effects of both phosphogypsum and dicyandiamide (DCD, C2H4N4) as additives on gaseous emissions and compost quality. Besides a control, there were three amended treatments with different amounts of additives. The results indicated that the phosphogypsum addition at the rate of 10% of mixture dry weight decreased NH₃ and CH₄ emissions significantly during composting. The addition of DCD at the rate of 0.2% of mixture dry weight together with 10% of phosphogypsum further reduced the N₂O emission by affecting the nitrification process. Reducing the phosphogypsum addition to 5% in the presence of 0.2% DCD moderately increased the NH₃ emissions but not N₂O emission. The additives increased the ammonium content and electrical conductivity significantly in the final compost. No adverse effect on organic matter degradation or the germination index of the compost was found in the amended treatments. It was recommended that phosphogypsum and DCD could be used in composting for the purpose of reducing NH₃, CH₄ and N₂O emissions. Optimal conditions and dose of DCD additive during composting should be determined with different materials and composting systems in further study.     

Prey detection in trawling insectivorous bats: duckweed affects hunting behaviour in Daubenton's bat, Myotis daubentonii

Daubenton's bat, a trawling vespertilionid bat species, hunts for insects that fly close to, or rest on, the water surface. During summer, many ponds at which Daubenton's bats hunt become gradually covered with duckweed. The purpose of this study was to investigate the effects of duckweed cover on the hunting behaviour of Daubenton's bats and on the ultrasound-reflecting properties of the water surface. Our study revealed the following. (1) Daubenton's bat avoids water surfaces covered with duckweed. (2) Prey abundance was related to the number of foraging Daubenton's bats but was independent of duckweed cover. (3) When mealworms were presented among standardized amounts of duckweed to naturally foraging Daubenton's bats, they caught significantly less mealworms when the duckweed cover was increased. (4) Measurements with ultrasonic signals show that a water surface covered with duckweed returns a much stronger background echo at small angles (i.e. parallel to the water surface) compared to an uncovered water surface. It seems likely that a cover of duckweed on the water surface interferes with prey detection by masking the echoes returning from prey. (5) It was relatively difficult for the bats to discriminate small patches of duckweed from mealworms. The proposed discrimination mechanism for this trawling bat species suggests that single duckweed patches can also be mistaken for natural prey by Daubenton's bats. Received: 4 January 1998 / Accepted after revision: 19 July 1998     

Cysteine-glutathione disulfide, the sperm-release pheromone of the marine polychaete Nereis succinea (Annelida: Polychaeta)

Summary. In the marine polychaete Nereis succinea (Frey & Leuckart 1847) a sex pheromone was isolated from the coelomic fluid of sexually mature females and identified by NMR studies and independent synthesis. This pheromone is released by the females during reproduction together with eggs and coelomic fluid into the free water column and induces sperm release of surrounding males. Its structure was ascertained as L-cysteine-glutathione disulfide. It exhibited a response threshold of 0.6 · 10⁻⁷ M. Received 15 July 1997; accepted 25 November 1997.     

The speed of an isolume: a shrimp's eye view

Using data from electroretinogram recordings, we designed a submersible light meter with a spectral luminous efficiency comparable to that of a vertically migrating shrimp. Using this light meter on the “Johnson Sea Link” submersible, we were able to ascend with the isolumes (preferred light levels) associated with the sergestid and euphausiid shrimp layers. The speed of the submersible's movement was recorded and correlated with simultaneous measurements of surface irradiance. In situ measurements of the downwelling spectral distribution were also made with a fiber optic spectrometer. The average measured speed of the sergestid isolume was 8.8 cm s⁻¹, while that of the shallower euphausiid isolume was 6.7 cm s⁻¹. These values are different from those calculated using average diffuse attenuation coefficients and surface light measurements. This difference was due to the broadening of the spectral distribution of downwelling light above 120 m and to the variability of the diffuse attenuation coefficients with depth. These results clearly demonstrate that when investigating the relationship between light and vertical migration patterns, it is important that: (1) the light measurements be made in situ and (2) such measurements take into account the spectral sensitivity of the eyes of the migrators. Received: 7 June 2000 / Accepted: 18 November 2000     

Pharmaceutical residues in the river Rhine--results of a one-decade monitoring programme

In this paper, results of an extensive monitoring programme for pharmaceutical residues in the river Rhine are presented. For one decade (1997 until 2006), the occurrence of widely used human pharmaceuticals like analgesics, lipid regulators, antiepileptics and others has been studied at four locations along the river Rhine. The results of more than 500 analyses clearly prove that compounds such as carbamazepine or diclofenac are regularly found in the river Rhine in concentrations up to several hundred ng per litre. Combining concentration levels with data on water flow enables the calculation of transports, which e.g. for carbamazepine or diclofenac were in the range of several tons per year. The evaluation of the long-term monitoring data shows that only a slight decrease in concentration levels as well as in annual transports can be observed and thus the contamination of the river Rhine by pharmaceutical residues during the last decade has to be regarded as almost constant. Seasonal variations can be detected for bezafibrate, diclofenac and ibuprofen, for which the concentrations are much lower in the summer months. A more effective removal during wastewater treatment in the warmer periods of the year seems to be the major reason for those variations. For carbamazepine, no comparable seasonal effect can be found.