Triazines in the aquatic systems of the Eastern Chinese Rivers Liao-He and Yangtse

The results of a one-year monitoring program on the two Eastern Chinese River systems, i.e. the Liao-He and the Yangtse, with special emphasis on the presence of triazine herbicides are presented. Sediment, suspended solids and water samples from both rivers were analyzed. Additionally, recovery experiments on the SPE-in-field-enrichment procedure and the extraction methods were performed. The samples were measured by gas chromatography coupled with mass spectrometry, electron capture detection and a newly developed mu-plasma atomic emission detector. A typical result of a one-year monitoring was obtained in case of the Liao-He: During winter, at low water period, low triazine values were found. A similar situation was found in early spring. Highest concentrations of atrazine up to 1600 ng/l were found in late spring in the water samples. Maximum concentrations of atrazine, simazine, propazine, simetryn and prometryn were observed in this season as a result of the actual use of triazines. Finally, after the high water period in autumn the triazine concentrations decreased. Additionally, atrazine adsorbed on sediment (up to 2.8 ng/g) and suspended solids was determined (up to 8 ng/l) during late spring sampling. Therefore, the logarithm of the organic carbon based sorption coefficient of atrazine could be calculated. Low levels of atrazine were measured in the water of Yangtse (up to 18.3 ng/l). The concentrations from all sampling points and sampling stations of a particular sampling date were similar, which indicates a homogeneous distribution of this herbicide. Due to the high discharge rate of up to 79,000 m3/s in case of the Yangtse a considerable mass transport of up to 57.5 kg per day atrazine may take place, even at concentrations below the European drinking water limit of 100 ng/l.     

Reactions of cloned poplars to air pollution

Ozone-induced changes in ethylene production, ACC oxidase activity and the contents of ACC, MACC and free PAs were studied inPopulus nigra L. cv. Loenen with high ozone sensitivity as judged by the degree of chlorophyll degradation and premature leaf abscission. Ethylene production, ACC oxidase activity, ACC content and MACC levels were induced by the one-, two-, and three-week ozone exposure (36±9 ppb O₃ for 11 hours a day). In addition, increases in PA levels, especially in spermidine, were measured in ozone treated plants. The role of free PAs and MACC synthesis as possible antisenescence reactions is discussed.     

The dispersion of the Buncefield oil fire plume: An extreme accident without air quality consequences

The dispersion of pollutants from the huge Buncefield oil depot fire that occurred on 11 December 2005 is simulated using a regional Eulerian chemistry-transport model. We analyse the transport and mixing of the fire plume. We show that the hot plume never reached the ground. Instead, it pierced the thin wintertime boundary layer and was injected into the free troposphere at higher altitudes. This is in agreement with data from many air quality stations. This high injection was fortunate because the fine aerosol particles (PM₁₀) mass column generated by the fire smoke exceeded that of ordinary pollution by an order of magnitude. Our regional chemistry-transport modelling is able to predict the early development of the plume dispersion, as shown by a qualitative comparison between simulated PM₁₀ columns and a satellite image obtained by the EOS-TERRA-MODIS sensor.If the accident had occurred in summer when boundary layers are much deeper and convective, a severe degradation in air quality due to PM₁₀ could have occurred, as shown by a sensitivity simulation assuming a similar fire during one of the hottest days of August 2003. The modelled impact of the fire on regional and European air quality levels strongly depends on the altitude reached by the buoyant plume, as shown by a set of sensitivity simulations with variable injection heights. However, in all cases we found that the fire only affected surface aerosol concentrations without increasing photochemical pollution.