Monitoring of iodinated X-ray contrast media in surface water

A monitoring programme was carried out in order to determine iodinated X-ray contrast media (ICM) in the River Danube and to investigate the raw water quality for drinking water production at Langenau waterworks. The study revealed that the maximum concentrations of ICM (over 500 ng l(-1) for diatrizoic acid and iopamidol) were found in 2h-composite samples taken from the downstream of the Ulm/Neu-Ulm metropolitan area. By means of a concentration profile over one month the highest ICM concentrations were observed on weekdays. The extended data evaluation with principal component analysis shows that the upstream and downstream samples had different pattern of variations in ICM concentration and also demonstrates a clear change in ICM composition by the discharge of municipal wastewater. In addition to load profiles of ICM, time-dependent plots of principal component 1 exhibited peaks, indicating a short-term discharge of ICM between the two sampling sites. In conclusion, a point source for ICM contamination between the sampling sites in Ulm upstream and Leipheim downstream seems to be the reasonable explanation for peak ICM concentrations. Due to the observed high variations of ICM concentrations in river, the evaluation of natural waters by means of a single analysis is not representative.     

Landfill leachate treatment methods: A review

Landfilling of municipal waste is still a major issue of the waste management system in Europe. The generated leachate must be appropriately treated before being discharged into the environment. Technologies meant for leachate treatment can be classified as follows (i) biological methods, (ii) chemical and physical methods. Here we review briefly the main processes currently used for the landfill leachates treatments.     

Light harvesting by wavelength transformation in a symbiotic coral of the Red Sea twilight zone

We report an extraordinary depth range for Leptoseris fragilis (Milne Edwards and Haime), a reef building coral of the Red Sea living in cytosymbiosis with zooxanthellae. The coral harbours an as yet unknown pigment system. We suggest that the heterotrophic host — the coral — provides its photoautotrophic symbionts with additional light. The supplementary light is provided by host pigments which transform light of short wavelengths into suitable wavelengths for photosynthesis, thus amplifying and increasing the transfer of photoassimilates from the zooxanthellae to the host.     

Peculiarities of innervation in chromatophore muscle cells ofLoligo vulgaris

The contractile cortex in muscle cells of the large brown chromatophore organs inLoligo vulgaris features a small open slit in its proximal portion. The slit accommodates a nerve fiber, penetrating into the central core of the muscle cell. The functional properties of the fiber, in relation to the contraction of the muscle cell, are discussed.Supported by Deutsche Forschungsgemeinschaft.     

Sublethal pesticide concentrations and predation jointly shape life history: behavioral and physiological mechanisms.

Despite their relevance for risk assessment, the interactive effects of pesticide and predation cues are poorly understood because the underlying behavioral and physiological mechanisms are largely unknown. To explore these mechanisms, we reared larvae of the damselfly Coenagrion puella at three different predation risk levels and a range of environmentally realistic concentrations of three pesticides used worldwide (atrazine, carbaryl, and endosulfan). We compared key development responses (growth rate, developmental time, and final size) against food ingestion, assimilation, and conversion efficiency, and acetylcholinesterase (AChE) activity. Predation risk impaired all endpoints, including AChE activity, while the effects of pesticide stress were smaller for atrazine and endosulfan and absent for carbaryl. The effects of both stressors and their interaction on life history were mostly indirect through resource acquisition and energy allocation. Compensatory physiological mechanisms to pesticide stress (atrazine and endosulfan) were present in larvae reared in the absence of predation stress but were offset under predation stress. As a result, smaller size (atrazine and endosulfan) and lower growth rate (endosulfan) from pesticide stress were only found in the highest predation risk treatment. Our results provide insight as to the conditions under which interactions between stressors are likely to occur: damselfly populations at high density and living in fish ponds will be more affected by pesticides than populations at low densities in fishless ponds. By identifying variables that may shape the interaction between predation stress and other stressors such as pesticides, our mechanistic approach may help to bridge the gap between laboratory and field studies.     

Calculating pesticide sorption coefficients (Kd) using selected soil properties

Pesticide soil/solution distribution coefficients ( Kd values), commonly referred to as pesticide soil sorption values, are utilized in computer and decision aid models to predict soil mobility of the compounds. The values are specific for a given chemical in a given soil sample, normally taken from surface soil, a selected soil horizon, or at a specific soil depth, and are normally related to selected soil properties. Pesticide databases provide Kd values for each chemical, but the values vary widely depending on the soil sample on which the chemicals were tested. We have correlated Kd values reported in the literature with the reported soil properties for an assortment of pesticides in an attempt to improve the accuracy of a Kd value for a specific chemical in a soil with known soil properties. Mathematical equations were developed from regression equations for the related properties. Soil properties that were correlated included organic matter content, clay mineral content, and/or soil pH, depending on the chemical properties of the pesticide. Pesticide families for which Kd equations were developed for 57 pesticides include the following: Carboxy acid, amino sulfonyl acid, hydroxy acid, weakly basic compounds and nonionizable amide/anilide, carbamate, dinitroaniline, organochlorine, organophosphate, and phenylurea compounds. Mean Kd values for 32 additional pesticides, many of which had Kd values that were correlated with specific soil properties but for which no significant Kd equations could be developed are also included.     

Relevance of coplanar PCBs for TEQ emission of fluidized bed incineration and impact of emission control devices

Five fluidized bed incinerators combusting municipal solid waste were assessed for the impact of coplanar PCBs on total TEQ emission. In 17 stack measurements, the coplanar PCBs contributed on average less than 3% to total TEQ with a maximum contribution of 7.5% to total TEQ in one measurement. Differences in the design of the flue gas cooling section did not show an effect on the impact of coplanar PCBs on total TEQ. The effect of emission control devices on the impact of coplanar PCBs on the total TEQ was studied in more detail at one incinerator. The relative contribution of PCBs to total TEQ increased along the flue gas line. This was caused by a slightly higher removal efficiency for TEQ relevant PCDDs/PCDFs compared to coplanar PCBs by the bag filters and a higher destruction efficiency for PCDDs/PCDFs compared to PCBs by the SCR catalyst. Additionally, the removal efficiencies of the emission control devices (bag filters and catalyst) for other chlorinated aromatic compounds which have been proposed as TEQ indicator compounds (polychlorinated benzenes and polychlorinated phenols) were compared with those for PCDDs/PCDFs and coplanar PCBs. Removal efficiencies for polychlorinated benzenes or polychlorinated phenols considerably differed from those of PCDD/PCDF and coplanar PCBs. Implications for TEQ assessments using indicator compounds as proposed in the literature are discussed.