Calibration and field performance of membrane-enclosed sorptive coating for integrative passive sampling of persistent organic pollutants in water

Membrane-enclosed sorptive coating (MESCO) is a miniaturised monitoring device that enables integrative passive sampling of persistent, hydrophobic organic pollutants in water. The system combines the passive sampling with solventless preconcentration of organic pollutants from water and subsequent desorption of analytes on-line into a chromatographic system. Exchange kinetics of chemicals between water and MESCO was studied at different flow rates of water, in order to characterize the effect of variable environmental conditions on the sampler performance, and to identify a method for in situ correction of the laboratory-derived calibration data. It was found that the desorption of chemicals from MESCO into water is isotropic to the absorption of the analytes onto the sampler under the same exposure conditions. This allows for the in situ calibration of the uptake of pollutants using elimination kinetics of performance reference compounds and more accurate estimates of target analyte concentrations. A field study was conducted to test the sampler performance alongside spot sampling. A good agreement of contaminant patterns and water concentrations was obtained by the two sampling techniques.     

Sperm swimming speed and energetics vary with sperm competition risk in bluegill (<Emphasis Type="Italic">Lepomis macrochirus</Emphasis>)

Under sperm competition, a males fertilization success depends largely on the ejaculate characteristics of competing males. Theoretical models predict that, in external fertilizers, increased risk of sperm competition should result in selection for increased sperm swimming speed. To test this prediction, we studied the behavior of sperm from parental and sneaker male bluegill (Lepomis macrochirus), a fish species characterized by high levels of cuckoldry due to alternative reproductive tactics of males (parentals and cuckolders). Because cuckolders (sneakers and satellites) always spawn in the presence of a parental male, but the reverse is not true, cuckolders experience the greater risk of sperm competition. We show here that the spermatozoa of sneakers have faster initial swimming speeds but shorter periods of motility than the sperm of parental males. Moreover, we show that sperm swimming speeds shortly after activation (when most fertilization occurs) are correlated with starting ATP levels in spermatozoa, suggesting that sperm competition has selected for higher energetic capacity in the sperm of sneakers. Thus, the higher energetic capacity and initial swimming speed of sneaker sperm may explain why, despite having fewer sperm per ejaculate than parentals, sneakers fertilize more eggs than parental males when they compete to fertilize a clutch of eggs.Communicated by L.W. Simmons     

DESIGN AND IMPLEMENTATION OF A COOPERATIVE WATER QUALITY MONITORING PROGRAM IN COLORADO'S BIG THOMPSON WATERSHED1

ABSTRACT: In 1996, the Big Thompson Watershed Forum (BTWF) was formed “to assess and protect the quality of water” in the Big Thompson Watershed in northern Colorado. However, until 1999, water quality monitoring in the watershed was performed by many state, local, and federal agencies with no coordination among programs and with few efforts toward efficiency, data comparability, or information exchange. To better meet the needs of its stakeholders, the BTWF since 1999 has been actively pursuing the design and implementation of a cooperative water quality monitoring program. The program design involved consensus building among the funding participants, primarily drinking water providers. The final design included 38 parameters to be sampled 15 times per year at 24 stream and canal locations plus two reservoirs. Although the collaborative consensus based approach has been successful for the BTWF, this approach has its drawbacks; most notable among these are the time and labor this approach requires. Also, the BTWF struggled with achieving equal representation of all interests, since those agencies that provided funding had the greatest voice in the final product. While a collaborative approach may not always be best for monitoring program design, it should be appropriate for many watershed organizations that face the common problem of severe financial constraints.     

Rhizosphere bacteria and their use to increase plant productivity: A review

Rhizosphere bacteria influence plant growth through several mechanisms. Beneficial interactions are often difficult to identify and isolate for study, and therefore favorable effects on plant productivity are not easily described in quantitative terms. Major beneficial activities of soil bacteria include solubilization of minerals, fixation of nitrogen, production of growth-promoting hormones and competitive suppression of pathogens. Most recent research to improve crop responses has emphasized the study of nitrogen-fixing bacteria indigenous to rhizospheres of cereal crops and other grasses. The amount of nitrogen available to crops from fixation by these organisms is significant under some circumstances, but efforts to control and increase fixation activity have not been consistently successful. Despite considerable research, inoculation experiments frequently fail to improve rates of nitrogen fixation. However, substantial progress has been achieved in understanding mechanisms involved in plant—bacterial interactions, and in defining conditions which control them. Also, recent studies show clearly that bacterial inoculation can be highly beneficial even when nitrogen fixation is not affected. Further research is needed to develop new and effective methods for suppressing growth of competing microorganisms, and promoting dominance of those most useful to plants. Environmental manipulation may not be sufficient to achieve this objective. Genetic development of both plant and bacterial lines which enhance desired interactions is likely to be the most productive research effort for the future.     

The significance of agricultural vs. natural ecosystem pathways in temperate climates in assessments of long-term radiological impact

Recent developments in performance assessment biosphere models have begun to emphasise the importance of natural accumulation pathways. In contrast to the agricultural pathways, the database for natural ecosystem pathways is less well developed, leading to a mismatch in quality of representations of the two types of system. At issue is the lack of reliable soil-plant and animal ingestion transfer factors for key radionuclides in natural ecosystems. The relative importance of the agricultural vs. natural ecosystem pathways is investigated here, in the context of a temperate site in present day, Eastern France. The BIOMASS Candidate Critical Group (CCG) methodology has been applied to map a set of eight candidate critical groups derived from the present-day societal context onto physical locations within a simple model of a river catchment system. The overall assessment model has been implemented using the Aquabios code. Annual individual dose to each of the CCGs has been calculated for each of the key radionuclides (79Se, 94Nb, 99Tc, 129I, 135Cs and 237Np) released to the valley aquifer and river. In addition to the traditional agricultural pathways, lifestyle groups exploiting natural habitats are explicitly addressed. Results show the susceptibility of different candidate critical groups to different radionuclides. A reference database typical of those employed in long-term performance assessment models is employed. Doses from external exposure (94Nb) and dust inhalation (237Np) are shown to dominate agricultural food consumption by factors of more than six, but, with the reference data set, foodstuffs obtained from natural ecosystems do not contribute significantly to critical group dose and, at most, show similar exposures to the agricultural pathways. This may lead to the conclusion that natural food can be ruled out of consideration in performance assessment models. However, systematic parametric sensitivity studies carried out on soil-plant and animal ingestion transfer factors restrict the validity of this observation and demonstrate the limitations of existing databases. Remaining uncertainties can be reduced by improving structural models for performance assessment and by better characterisation of sources of locally obtained foods. Improved characterisation of radionuclide accumulation in natural ecosystems in temperate as well as alternative future climate states should complement the modelling approach.     

?kotoxikologie soll endlich wissenschaftliches Fach werden

Ohne Zusammenfassung     

Removal of polychlorinated biphenyls from capacitors and pressure-sensitive paper by vacuum thermal recycling

This paper describes a new vacuum thermal recycling (VTR) method for treating discarded polychlorinated biphenyls (PCB)-contaminated capacitors and pressure-sensitive paper. Based on results demonstrating an exceptionally high PCB separation efficiency and recovery ratio from capacitors containing high-concentration PCBs, i.e. > 99.9%, respectively, the presented VTR method is verified to effectively remove PCBs. In addition, associated safety aspects of the employed procedure were confirmed.