Distribution of some organochlorine compounds in pine needles from Central and Northern Europe

Levels of selected organochlorine compounds in pine needles were measured in two sampling series. The first series collected in 1989 covered Southern Germany to Northern Scandinavia, and the second collected in 1990 covered Czechoslovakia to Estonia. The levels of alpha-hexachlorocyclohexane (alpha-HCH) and hexachlorobenzene (HCB) were relatively uniform throughout Europe, while the levels of gamma-hexachlorocyclohexane (gamma-HCH) and the DDT group show higher levels in the southern parts of the investigated area. The deposition patterns of all compounds except alpha-HCH indicate a dependence on fresh release from diffuse or point sources rather than global fractionation. The analytes accumulate in the needles until senescence starts and, generally, the oldest needles have the highest concentrations. The accumulation rate of the analytes in mountain pine needles is about half that of Scots pine needles indicating the importance of species differences.     

Leaching of pesticides through normal-tillage and low-tillage soil--a lysimeter study. II. Glyphosate

Glyphosate is a widely used non-selective herbicide. Leaching of glyphosate (N-(phosphonomethyl)glycine) and/or its metabolite AMPA (aminomethylphosphonic acid) was studied in four lysimeters, two of them being replicates from a low-tillage field (lysimeter 3 and 4), the other two being replicates from a normal tillage field (lysimeter 5 and 6). In both cases the soil was a sandy loam soil with 13-14% clay. The lysimeters had a surface area of 0.5 m2 and a depth of 110 cm. Lysimeter 3 and 4 were sprayed with a mixture of 14C-labelled glyphosate and unlabelled glyphosate, while lysimeter 5 and 6 were sprayed with unlabelled glyphosate. The spraying took place September 18, 1997. The total amount of glyphosate sprayed onto each lysimeter was 40 mg, corresponding to 0.8 kg active ingredient per ha. The lysimeters were installed in an outdoor system in Research Centre Flakkebjerg and were thus exposed to normal climatic conditions of the area. A mean of 260 l drainage water were collected from lysimeter 3 and 4 and a mean of 375 litres from lysimeter 5 and 6. The mean yearly concentration of leached glyphosate and/or AMPA was significantly below 0.1 microg/l from both sets of lysimeters, and thus no significant difference between the two lysimeter sets was shown. However, in both sets of lysimeters several single findings at concentrations above 0.1 microg/l was seen, which might be due to the leaching of particle-bound compounds. A significant difference between the soil residual concencentrations of AMPA was seen, the higher concentration was found in the set of lysimeter where low-tillage had been practiced and where Round Up had been used several times in the years before sampling of the lysimeter soil.     

Baltic Sea hazardous substances management: results and challenges

The introduction into the Baltic Sea of hazardous substances that are persistent, bioaccumulate, and are toxic is an important environmental and human health problem. Multilateral efforts to address this problem have primarily been taken under the Helsinki Commission (HELCOM). This article examines past HELCOM efforts on hazardous substances, and discusses future challenges regarding their management. The article finds that past actions on hazardous substances have had a positive effect on improving Baltic environmental quality and reducing human health risks, although there are remaining issues and difficulties that need to be addressed. In particular, four related future challenges for HELCOM management of hazardous substances are identified and discussed: i) the need to engender further implementation and building public and private sector capacities; ii) the need to improve data availability, quality and comparability across the region and international fora; iii) the need to strengthen existing regulations and incorporate new issues; and iv) the need to effectively coordinate HELCOM activities with efforts on hazardous substances in other international fora.     

Carbendazim sorption-desorption in Vietnamese soils

Four Vietnamese soils (denoted AG, CT, ST and TG) which differed with respect to pH (pH 2.9-5.4), clay (17-50%) and organic matter (0.3-9.8%) content, were selected for sorption and desorption studies of carbendazim using the batch equilibration technique. Sorption increased with increasing organic carbon (OC) and clay content. Kd values for carbendazim sorption on AG, CT, ST, TG soils at initial concentration of 20 microg/g were 12.5, 127, 8.1 and 9.6 ml/g, respectively. The OC partition coefficients (Koc) for AG, CT, ST and TG were 1140, 1300, 2700 and 960 ml/g, respectively. Carbendazim was strongly sorbed and the binding was less reversible in the acid sulfate soil (CT), than in the other soils. The CT soil had both the highest OC content (9.8%) and the highest clay content (49.8%). The influence of pH on carbendazim sorption was studied in the ST and CT soils. Sorption of carbendazim by the sandy ST soil (OC 0.3%; clay content 26.3%) increased as the pH decreased, while sorption of carbendazim by the CT soil decreased as pH decreased.     

Statistical control of hygienic quality of bathing water

In Denmark the hygienic quality of the bathing water has been controlled, based on general guidelines since 1978. Today more than 1100 control sites in marine areas have been established to ensure safe bathing water quality. According to EEC directives and Danish tradition, the control is usually performed by measuring the content of the indicator bacteria Escherichia coli (E. coli) in 5 to 20 test samples each bathing season.In Denmark, control programmes and data are evaluated using basic statistical quality control principles. This paper presents general guidelines for bacterial control, their statistical background and practical application. Furthermore, the evaluation and application of a specific programme for control of Staphylococcus aureus (S. aureus) are presented. This programme was used in a Danish bay where the authorities prescribe direct control of these potentially harmful bacteria.     

Infrared spectroscopic probing of dimethylamine clusters in an Ar matrix

Amines have many atmospheric sources and their clusters play an important role in aerosol nucleation processes. Clusters of a typical amine, dimethylamine (DMA), of different sizes were measured with matrix isolation IR (infrared) and NIR (near infrared) spectroscopy. The NIR vibrations are more separated and therefore it is easier to distinguish different sizes of clusters in this region. The DMA clusters, up to DMA tetramer, have been optimized using density functional methods, and the geometries, binding energies and thermodynamic properties of DMA clusters were obtained. The computed frequencies and intensities of NH-stretching vibrations in the DMA clusters were used to interpret the experimental spectra. We have identified the fundamental transitions of the bonded NH-stretching vibration and the first overtone transitions of the bonded and free NH-stretching vibration in the DMA clusters. Based on the changes in vibrational intensities during the annealing processes, the growth of clusters was clearly observed. The results of annealing processes indicate that DMA molecules tend to form larger clusters with lower energies under matrix temperatures, which is also supported by the calculated reaction energies of cluster formation.     

Mutual information in the Tangled Nature model

We consider the concept of mutual information in ecological networks, and use this idea to analyse the Tangled Nature model of co-evolution. We show that this measure of correlation has two distinct behaviours depending on how we define the network in question: if we consider only the network of viable species this measure increases, whereas for the whole system it decreases. It is suggested that these are complimentary behaviours that show how ecosystems can become both more stable and better adapted.     

The role of environmental and spatial factors for the composition of aquatic bacterial communities

This study investigates the importance of local vs. spatial factors on bacterial community composition of 35 rock pools at the Baltic Sea coast. The pools were located in five distinct spatial clusters over a total scale of <500 m and differed widely in terms of water chemistry. To determine the fractions of the variance in bacterial community composition (BCC) between rock pools that are explained by local environmental vs. spatial factors, a variance partitioning procedure using partial canonical correspondence analysis was performed. Three environmental variables (salinity, chlorophyll a concentration, and water color) had a significant effect on BCC, irrespective of the spatial location of the pools. Vice versa, there was a significant effect of spatial factors on BCC irrespective of any of the environmental factors included in this study. Hence, the patchy spatial distribution of the pools was partly reflected in the composition of the bacterial communities in the pools, which might be caused by congruent colonization events of adjacent pools, such as simultaneous seaspray inputs or direct exchange of bacteria via connecting rivulets. This study shows that the composition of planktonic bacteria can show provincialism at small spatial scales, which is likely to be caused by environmental conditions as well as historical events.     

GENETIC PROGRAMMING AND ITS APPLICATION IN REAL‐TIME RUNOFF FORECASTING1

ABSTRACT: Genetic programming (GP), a relatively new evolutionary technique, is demonstrated in this study to evolve codes for the solution of problems. First, a simple example in the area of symbolic regression is considered. GP is then applied to real‐time runoff forecasting for the Orgeval catchment in France. In this study, GP functions as an error updating scheme to complement a rainfall‐runoff model, MIKE11/NAM. Hourly runoff forecasts of different updating intervals are performed for forecast horizons of up to nine hours. The results show that the proposed updating scheme is able to predict the runoff quite accurately for all updating intervals considered and particularly for updating intervals not exceeding the time of concentration of the catchment. The results are also compared with those of an earlier study, by the World Meteorological Organization, in which autoregression and Kalman filter were used as the updating methods. Comparisons show that GP is a better updating tool for real‐time flow forecasting. Another important finding from this study is that nondimensionalizing the variables enhances the symbolic regression process significantly.