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.     

Temporal trends and spatial distribution of PCDD, PCDF, and PCB in pine and spruce shoots

In Germany, there is a lack of consistent and comparable data for the time dependent behaviour and spatial distribution of dioxin-like and indicator PCB in ambient air, deposition and plants. The aim of this study was to improve the data on PCDD/PCDF, dioxin-like PCB and non dioxin-like PCB in spruce and pine shoots from different locations and years by retrospective monitoring. The survey was conducted with archived samples of one-year old spruce shoots (Picea abies) and pine shoots (Pinus sylvestris) from the German environmental specimen bank. Two sets of samples from locations in urbanized areas in western and eastern Germany (Warndt and Duebener Heide Mitte, respectively) were investigated as time series. Additionally, spruce shoots from seven different rural locations sampled in the years 2000-2004 were analyzed in order to get an overview about the spatial distribution of PCB and PCDD/PCDF. The analytical results of the samples from the two urbanized areas clearly show that the atmospheric contamination with PCDD and PCDF has declined by about 75% between 1985 and 1997 at Warndt and about 40% between 1991 and 1997 at Duebener Heide. However, concentrations stayed virtually constant at both locations from 1997 to 2004 at a level of about 1 ng WHO-TEQ/kg dry matter (d.m.). Similarly, the investigation of spruce shoots from rural locations from 2000 to 2004 did not reveal a temporal trend at any site. PCDD/PCDF levels were between 0.1 and 1.0 ng WHO-TEQ/kg d.m. At the urbanized location Warndt the six indicator PCB as well as the 12 dioxin-like PCB according to WHO revealed a significant decline by more than 75% between 1985 and 1999. Thereafter, PCB levels stayed virtually constant. At the location Duebener Heide an overall decrease of PCB concentrations in pine shoots of about 60% was detected between 1991 and 2004. Spruce shoots from all locations showed a relevant contribution of dioxin-like PCB to the total WHO toxicity equivalent (PCDD/PCDF+PCB). In most samples, the contribution of dioxin-like PCB was between 21% and 41%. The TEQ contribution of PCB in the samples from three rural sites was higher and similar to the TEQ value of PCDD/PCDF. The investigated pine shoots from the urbanized site Duebener Heide showed a 15-28% contribution of dioxin-like PCB to total TEQ and thus lower than in spruce shoots from different locations. In all samples except one PCB 126 contributed to more than 80% to the PCB-TEQ.     

Coordinating links among research, standardisation and policy in support of water framework directive chemical monitoring requirements

The need for coordination among scientific and policy activities is an old debate in which respective communities have often tried to impose their views rather than reflecting on pragmatic solutions. In the last few years, however, constructive exchanges have taken place in the context of expert groups linked to the implementation of the Water Framework Directive (WFD) and related EU funded research projects, which have resulted in a better understanding of communication and knowledge transfer gaps. These exchanges concern not only the way research is being interfaced with water policies, but also how improved coordination could be organised regarding technical specifications linked to standardisation. This paper discusses on-going efforts to improve coordination among research, standardisation and policy in support of WFD implementation, with emphasis on chemical monitoring requirements.     

Emissions- und Immissionsprognosen für den Straßenverkehr in Deutschland

The use of such threshold values, which are valid today and will be valid in the future, for waste gas emissions from motor vehicles will continuously serve to further limit the amounts of emissions from the motorized traffic in Germany, even though it must be assumed that an ever increasing amount of mileage will be observed. Following the reduction in emissions which have been calculated, and the estimated improvements to be seen in this area, important goals in atmospheric quality should be achieved in the future. Especially the risk of cancer associated with motorvehicle traffic will drop appreciably below the target goals. The most important problem of the air pollution stemming from traffic emissions, however, seems to be the fine dusts. A reduction in the quantity of these substances may possibly be related to the emissions of nitric oxides and also of NMVOCs. The efficient reduction of the climatically-relevant emissions attributed to motor-vehicle traffic is a great challenge to the fields of technology, fuel supply and user behavior patterns. These factors will therefore represent an important part of the long-term environmental discussions.     

Dust exposure in indoor climbing halls

The use of hydrated magnesium carbonate hydroxide (magnesia alba) for drying the hands is a strong source for particulate matter in indoor climbing halls. Particle mass concentrations (PM10, PM2.5 and PM1) were measured with an optical particle counter in 9 indoor climbing halls and in 5 sports halls. Mean values for PM10 in indoor climbing halls are generally on the order of 200-500 microg m(-3). For periods of high activity, which last for several hours, PM10 values between 1000 and 4000 microg m(-3) were observed. PM(2.5) is on the order of 30-100 microg m(-3) and reaches values up to 500 microg m(-3), if many users are present. In sports halls, the mass concentrations are usually much lower (PM10 < 100 microg m(-3), PM2.5 < or = 20 microg m(-3)). However, for apparatus gymnastics (a sport in which magnesia alba is also used) similar dust concentrations as for indoor climbing were observed. The size distribution and the total particle number concentration (3.7 nm-10 microm electrical mobility diameter) were determined in one climbing hall by an electrical aerosol spectrometer. The highest number concentrations were between 8000 and 12 000 cm(-3), indicating that the use of magnesia alba is no strong source for ultrafine particles. Scanning electron microscopy and energy-dispersive X-ray microanalysis revealed that virtually all particles are hydrated magnesium carbonate hydroxide. In-situ experiments in an environmental scanning electron microscope showed that the particles do not dissolve at relative humidities up to 100%. Thus, it is concluded that solid particles of magnesia alba are airborne and have the potential to deposit in the human respiratory tract. The particle mass concentrations in indoor climbing halls are much higher than those reported for schools and reach, in many cases, levels which are observed for industrial occupations. The observed dust concentrations are below the current occupational exposure limits in Germany of 3 and 10 mg m(-3) for respirable and inhalable dust. However, the dust concentrations exceed the German guide lines for work places without use of hazardous substances. In addition, minimizing dust concentrations to technologically feasible values is required by the current German legislation. Therefore, substantial reduction of the dust concentration is required.     

Sources and spatial distribution of heavy metals in scleractinian coral tissues and sediments from the Bocas del Toro Archipelago, Panama

Marine ecosystems worldwide are threatened by aquatic pollution; however, there is a paucity in data from the Caribbean region. As such, five heavy metals (arsenic, cadmium, copper, zinc, mercury) were measured in tissues of the scleractinian corals Porites furcata and Agaricia tenuifolia and in adjacent sediments in the Bocas del Toro Archipelago, Panama. Samples were collected from five reef sites along a gradient of distance from an international shipping port and were analysed using inductively coupled plasma optical emission spectrometry and atomic absorption spectrophotometry for mercury. Copper and zinc were the most abundant metals and ranged from 11 to 63 mg kg^?1 and from 31 to 185 mg kg^?1 in coral tissues, respectively. The highest concentration of each metal was measured in P. furcata tissues, with copper and mercury concentrations significantly higher in P. furcata than in A. tenuifolia at every site. These results suggest that P. furcata has a higher affinity for metal accumulation and storage than A. tenuifolia. With the exception of cadmium, metal concentrations in coral tissues were generally elevated at coral reefs in closer proximity to the port; however, this pattern was not observed in sediments. Hard coral cover was lowest at reefs in closest proximity to the port, suggesting that metal pollution from port-related activities is influencing hard coral abundance at nearby coral reefs.     

Analysing the fate of nanopesticides in soil and the applicability of regulatory protocols using a polymer-based nanoformulation of atrazine

For the first time, regulatory protocols defined in the OECD guidelines were applied to determine the fate properties of a nanopesticide in two agricultural soils with contrasting characteristics. The nanoformulation studied had no effect on the degradation kinetics of atrazine indicating that (1) the release of atrazine from the polymer nanocarriers occurred rapidly relative to the degradation kinetics (half-lives 36–53 days) and/or that (2) atrazine associated with the nanocarriers was subject to biotic or abiotic degradation. Sorption coefficients, derived from a batch and a centrifugation technique at a realistic soil-to-solution ratio, were higher for the nanoformulated atrazine than for the pure active ingredient. Results indicate that the nanoformulation had an effect on the fate of atrazine. However, since the protocols applied were designed to assess solutes, conclusions about the transport of atrazine loaded onto the nanocarriers should be made extremely cautiously. The centrifugation method applied over time (here over 7 days) appears to be a useful tool to indirectly assess the durability of nanopesticides under realistic soil-to-solution ratios and estimate the period of time during which an influence on the fate of the active ingredient may be expected. More detailed investigations into the bioavailability and durability of nanopesticides are necessary and will require the development of novel methods suitable to address both the “nano” and “organic” characteristics of polymer-based nanopesticides.     

The Baltic Sea spring phytoplankton bloom in a changing climate: an experimental approach

The response of the Baltic Sea spring bloom was studied in mesocosm experiments, where temperatures were elevated up to 6°C above the present-day sea surface temperature of the spring bloom season. Four of the seven experiments were carried out at different light levels (32–202?Wh?m^?2 at the start of the experiments) in the different experimental years. In one further experiment, the factors light and temperature were crossed, and in one experiment, the factors density of overwintering zooplankton and temperature were crossed. Overall, there was a slight temporal acceleration of the phytoplankton spring bloom, a decline of peak biomass and a decline of mean cell size with warming. The temperature influence on phytoplankton bloom timing, biomass and size structure was qualitatively highly robust across experiments. The dependence of timing, biomass, and size structure on initial conditions was tested by multiple regression analysis of the y-temperature regressions with the candidate independent variables initial light, initial phytoplankton biomass, initial microzooplankton biomass, and initial mesozooplankton (=copepod) biomass. The bloom timing predicted for mean temperatures (5.28°C) depended on light. The peak biomass showed a strong positive dependence on light and a weaker negative dependence on initial copepod density. Mean phytoplankton cell size predicted for the mean temperature responded positively to light and negatively to copepod density. The anticipated mismatch between phytoplankton supply and food demand by newly hatched copepod nauplii occurred only under the combination of low light and warm temperatures. The analysis presented here confirms earlier conclusions about temperature responses that are based on subsets of our experimental series. However, only the comprehensive analysis across all experiments highlights the importance of the factor light.     

Null model analysis of species associations using abundance data

The influence of negative species interactions has dominated much of the literature on community assembly rules. Patterns of negative covariation among species are typically documented through null model analyses of binary presence/absence matrices in which rows designate species, columns designate sites, and the matrix entries indicate the presence (1) or absence (0) of a particular species in a particular site. However, the outcome of species interactions ultimately depends on population-level processes. Therefore, patterns of species segregation and aggregation might be more clearly expressed in abundance matrices, in which the matrix entries indicate the abundance or density of a species in a particular site. We conducted a series of benchmark tests to evaluate the performance of 14 candidate null model algorithms and six covariation metrics that can be used with abundance matrices. We first created a series of random test matrices by sampling a metacommunity from a lognormal species abundance distribution. We also created a series of structured matrices by altering the random matrices to incorporate patterns of pairwise species segregation and aggregation. We next screened each algorithm-index combination with the random and structured matrices to determine which tests had low Type I error rates and good power for detecting segregated and aggregated species distributions. In our benchmark tests, the best-performing null model does not constrain species richness, but assigns individuals to matrix cells proportional to the observed row and column marginal distributions until, for each row and column, total abundances are reached. Using this null model algorithm with a set of four covariance metrics, we tested for patterns of species segregation and aggregation in a collection of 149 empirical abundance matrices and 36 interaction matrices collated from published papers and posted data sets. More than 80% of the matrices were significantly segregated, which reinforces a previous meta-analysis of presence/absence matrices. However, using two of the metrics we detected a significant pattern of aggregation for plants and for the interaction matrices (which include plant-pollinator data sets). These results suggest that abundance matrices, analyzed with an appropriate null model, may be a powerful tool for quantifying patterns of species segregation and aggregation.