Contaminants of food

A scheme has been developed to rank 70 industrial organic chemicals in order of their priority for further study as potential contaminants of food. Numerical scales were developed for the following seven key criteria concerning environmental issues, food and toxicity:

-Production volume

-Pattern of usage

-Possible fate in the environment

-Likelihood of chemical entering the food chain

-Mechanism of entry into the food chain

-Persistence and accumulation in the food chain

-Toxicity.

Each chemical was assigned a score for the above criteria, which were combined to give an overall ranking for the chemicals. This scheme has been endorsed by the MAFF Steering Group on Chemical Aspects of Food Surveillance. It will be used in the assessment of relative priorities for further non-statutory surveillance for these contaminants in the UK food supply.     

Isolation and identification of an anti-algal compound from Artemisia annua and mechanisms of inhibitory effect on algae

The goals of this work were to isolate and identify an anti-algal compound from extracts of Artemisia annua and study its mode of action on Microcystis aeruginosa. The anti-algal compound was isolated from the extracts using column chromatography and activity-guided fractionation methods. Artemisinin with strong anti-algal activity was identified by gas chromatography-mass spectrometry and ¹H Nuclear Magnetic Resonance. The EC₅₀ of artemisinin on M. aeruginosa was 3.2 mg L⁻¹. Artemisinin decreased the soluble protein content and increased the superoxide dismutase activity and ascorbic acid content of M. aeruginosa, but exerted no effect on soluble sugar content. The results suggested the mode of action of artemisinin on algae may primarily be the increasing level of reactive oxygen species in algae cells. The results of our research could aid in the development of new anti-algal substances and lead to further study of mechanisms of inhibitory effect on algae.     

Mitigation of CO2 Emissions from the EU-15 Building Stock. Beyond the EU Directive on the Energy Performance of Buildings (9 pp)

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Goal Scope and Background. The European Directive on Energy Performance of Buildings which came into force 16 December 2002 will be implemented in the legislation of Member States by 4 January 2006. In addition to the aim of improving the overall energy efficiency of new buildings, large existing buildings will become a target for improvement, as soon as they undergo significant renovation. The building sector is responsible for about 40% of Europe's total end energy consumption and hence this Directive is an important step for the European Union in order that it should reach the level of saving required by the Kyoto Agreement. In this the EU is committed to reduce CO2 emissions relative to the base year of 1990 by 8 per cent, by 2010. But what will be the impact of the new Directive, how large could be the impacts of extending the obligation for energy efficiency retrofitting towards smaller buildings? Can improvement of the insulation offset or reduce the growing energy consumption from the increasing installation of cooling installations? EURIMA, the European Insulation Manufacturers Association and EuroACE, the European Alliance of Companies for Energy Efficiency in Buildings, asked Ecofys to address these questions.

Methods

The effect of the EPB Directive on the emissions associated with the heating energy consumption of the total EU 15 building stock has been examined in a model calculation, using the Built Environment Analysis Model (BEAM), which was developed by Ecofys to investigate energy saving measures in the building stock. The great complexity of the EU-15 building stock had to be simplified by examining five standard buildings with eight insulation standards, which are assigned to building age and renovation status. Furthermore, three climatic regions (cold, moderate, warm) were distinguished for the calculation of the heating energy demand. This gave a basic 210 building types for which the heating energy demand and CO2 emissions from heating were calculated according to the principles of the European Norm EN 832.

Results and Discussion

The model calculations demonstrates that the main contributor to the total heating related CO2 emissions of 725 Mt/a from the EU building stock in 2002 is the residential sector (77%) while the remaining 23% originates from non-residential buildings. In the residential sector, single-family houses represent the largest group responsible for 60% of the total CO2 emissions equivalent to 435 Mt/a.

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- The technical potential: If all retrofit measures in the scope of the Directive were realised immediately for the complete residential and non-residential building stock the overall CO2 emission savings would add up to 82 Mt/a. An additional saving potential compared to the Directive of 69 Mt/a would be created if the scope of the Directive was extended to cover retrofit measures in multi-family dwellings (200-1000m2) and non-residential buildings smaller than 1000m2 used floor space. In addition including the large group of single-family dwellings would lead to a potential for additional CO2 emission reductions compared to the Directive of 316 Mt/a.

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- Temporal mobilization of the potential: Calculations based on the building stock as it develops over time with average retrofit rates demonstrated that regulations introduced following the EPB Directive result in a CO2 emissions decrease of 34 Mt/a by the year 2010 compared to the business as usual scenario. Extending the scope of the EPB Directive to all residential buildings (including single and multi-family dwellings), the CO2 emission savings potential over the 'business as usual' scenario could be doubled to 69 Mt/a in the year 2010. This creates an additional saving potential compared to the Directive of 36 Mt/a.

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- Cooling demand: The analysis demonstrated that in warm climatic zones the cooling demand can be reduced drastically by a combination of lowering the internal heat loads and by improved insulation. With the reduction of the heat loads to a moderate level the cooling demand, e.g. of a terraced house located in Madrid, can be reduced by an additional 85% if the insulation level is improved appropriately.

Conclusions

This study demonstrates that the European Directive on Energy Performance of Buildings will have a significant impact on the CO2 emissions of the European building stock. The main saving potential lies in insulation of the existing building stock. Beyond this, CO2 emissions could, however, be greatly reduced if the scope of the Directive were to be extended to include retrofit of smaller buildings.

Recommendation and Perspective

The reductions should be seen in relation to the remaining gap of 190 Mt CO2 eq. per annum between the current emission levels of EU-15 and the target under the Kyoto-Protocol for the year 2010. The energy and industrial sector will probably contribute only a fraction of this reduction via the newly established EU emissions trading scheme and connected projects under the flexible mechanism. In addition, the traffic sector is likely to continue its growth path leading to a widening of the gap. Thus, there is likely to be considerable pressure on the EU building sector to contribute to the EU climate targets beyond what will be achieved by means of the current EPB Directive. Legislators on the EU and national level are therefore advised to take accelerated actions to tap the very significant emission reduction potentials available in the EU building stock.     

Bioconcentration of superlipophilic persistent chemicals

According to present understanding, persistent superlipophilic chemicals — such as octachlorodibenzo-p-dioxin, octachlorodibenzofuran, Mirex etc — with log K_ow > 6 and cross sections > 9.5 Å, bioconcentrate in aquatic organisms only little from ambient water. The most convincing argument against it is that in bioconcentration experiments with superlipophilic chemicals amounts applied exceeded water solubility by several orders of magnitude. This paper describes various methods for determining bioconcentration factors (BCF) of superlipophilic compounds. As exemplified with octachlorodibenzo-p-dioxin, BCF values evaluated by these methods match well with those calculated by QSARs for fish and mussels based on log K_ow and water solubility. As expected, these BCF values exceed previous values by several orders of magnitude. For BCF evaluation of superlipophilic chemicals in aquatic organisms we recommend:

1. flow-through systems, kinetic method (OECD guideline No. 305 E)
2. ambient concentrations < water solubility
3. during the uptake and especially during the elimination phase no toxic effects of the test organisms should occur.

     

Influence of algal bloom degradation on nutrient release at the sediment–water interface in Lake Taihu, China

Algal bloom could drastically influence the nutrient cycling in lakes. To understand how the internal nutrient release responds to algal bloom decay, water and sediment columns were sampled at 22 sites from four distinct regions of China’s eutrophic Lake Taihu and incubated in the laboratory to examine the influence of massive algal bloom decay on nutrient release from sediment. The column experiment involved three treatments: (1) water and sediment (WS); (2) water and algal bloom (WA); and (3) water, sediment, and algal bloom (WSA). Concentrations of dissolved oxygen (DO), total nitrogen (TN), total phosphorus (TP), ammonium (NH ₄ ⁺ -N), and orthophosphate (PO ₄ ^3? -P) were recorded during incubation. The decay of algal material caused a more rapid decrease in DO than in the algae-free controls and led to significant increases in NH ₄ ⁺ -N and PO ₄ ^3? -P in the water. The presence of algae during the incubation had a regionally variable effect on sediment nutrient profiles. In the absence of decaying algae (treatment WS), sediment nutrient concentrations decreased during the incubation. In the presence of blooms (WSA), sediments from the river mouth released P to the overlying water, while sediments from other regions absorbed surplus P from the water. This experiment showed that large-scale algal decay will dramatically affect nutrient cycling at the sediment–water interface and would potentially transfer the function of sediment as “container” or “supplier” in Taihu, although oxygen exchange with atmosphere in lake water was stronger than in columns. The magnitude of the effect depends on the physical–chemical character of the sediments.     

Characterization of PM10 atmospheric aerosol at urban and urban background sites in Fuzhou city, China

Background

PM₁₀ aerosol samples were simultaneously collected at two urban and one urban background sites in Fuzhou city during two sampling campaigns in summer and winter. PM₁₀ mass concentrations and chemical compositions were determined.

Methods

Water-soluble inorganic ions (Cl^?, NO ₃ ^? , SO ₄ ^2? , NH ₄ ⁺ , K⁺, Na⁺, Ca²⁺, and Mg²⁺), carbonaceous species (elemental carbon and organic carbon), and elements (Al, Si, Mg, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, and Pb) were detected using ion chromatography, thermal/optical reflectance, and proton-induced X-ray emission methods, respectively.

Results

PM₁₀ mass concentrations, as well as most of the chemical components, were significantly increased from urban background to urban sites, which were due to enhanced anthropogenic activities in urban areas. Elements, carbonaceous species, and most of the ions were more uniformly distributed at different types of sites in winter, whereas secondary ion SO ₄ ^2? , NO ₃ ^? , and NH ₄ ⁺ showed more evident urban-background contrast in this season. The chemical mass closure indicated that mineral dust, organic matters, and sulfate were the most abundant components in PM₁₀. The sum of individually measured components accounted for 86.9?C97.7% of the total measured PM₁₀ concentration, and the discrepancy was larger in urban area than in urban background area.

Conclusion

According to the principal component analysis?Cmultivariate linear regression model, mineral dust, secondary inorganic ions, sea salt, and motor vehicle were mainly responsible for the PM₁₀ particles in Fuzhou atmosphere, and contributed 19.9%, 53.3%, 21.3%, and 5.5% of PM₁₀, respectively.     

Effects of allelochemical extracted from water lettuce (Pistia stratiotes Linn.) on the growth, microcystin production and release of Microcystis aeruginosa

This study explored the optimisation of a method of extracting allelochemicals from Pistia stratiotes Linn., identified the optimal dose range for the allelochemicals’ anti-algal effect and investigated their impact on the growth of Microcystis aeruginosa, as well as the production and release of microcystin-LR (MC-LR). Based on measured changes in algal cell density and chlorophyll a (Chl-a) content, the allelochemicals were confirmed to have the strongest anti-algal effect with the lowest half-effect concentration of 65 mg L^?1 when they were extracted using ethyl acetate as the extraction solvent, 1:20 g mL^?1 as the extraction ratio and 1 h as the extraction time. The allelochemicals extracted from P. stratiotes using this optimal method exhibited the strongest inhibitory effect on the growth of algae when used within a dose range of 60–100 mg L^?1; the relative inhibitory ratio reached 50–90 %, and Chl-a content reduced 50–75 % in algae cell cultures within 3–7 days. In addition, the extracted allelochemical compounds demonstrated no significant impact on the extracellular release of MC-LR during the culturing period. The amount of intracellular MC-LR per 10⁶ algal cells increased depending on the increasing dose of allelochemicals from P. stratiotes after 7 days of culturing and maintained stability after 16 days. There was no increase in the total amount of MC-LR in the algal cell culture medium. Therefore, the application of allelochemicals from P. stratiotes to inhibit M. aeruginosa has a high degree of ecological safety and can be adopted in practical applications for treating water subjected to algae blooms because the treatment can effectively inhibit the proliferation of algal cells without increasing the release of cyanotoxin.     

Environmental risk assessment of existing chemicals

Most of the existing chemicals of high priority have been released into the environment for many years. Risk assessments for existing chemicals are now conducted within the framework of the German Existing Chemicals Program and by the EC Regulation on Existing Substances. The environmental assessment of a chemical involves:

1. exposure assessment leading to the derivation of a predicted environmental concentration (PEC) of a chemical from releases due to its production, processing, use, and disposal. The calculation of a PEC takes into account the dispersion of a chemical into different environmental compartments, elimination and dilution processes, as well as degradation. Monitoring data are also considered.
2. effects assessment. Data obtained from acute or long-term toxicity tests are used for extrapolation on environmental conditions. In order to calculate the concentration with expectedly no adverse effect on organisms (Predicted No Effect Concentration, PNEC) the effect values are divided by an assessment factor. This assessment factor depends on the quantity and quality of toxicity data available.

In the last step of the initial risk assessment, the measured or estimated PEC is compared with the PNEC. This “risk characterization” is conducted for each compartment separately (water, sediment, soil, and atmosphere). In case PEC > PNEC an attempt should be made to revise data of exposure and/or effects to conduct a refined risk characterization. In case PEC is again larger than PNEC risk reduction measures have to be considered.     

Toxicity testing of highly volatile chemicals with green algae

A gas-tight system for toxicity testing of highly volatile chemicals with the green algaChlamydomonas reinhardtii was developed. The procedure permits maintenance of constant and defined concentrations of the tested compounds in the vessels. To ensure sufficient CO₂-supply, new bipartite test vessels were used. These vessels allowed spatial separation of a HCO₃-/CO ₃ ^2? buffer used for CO₂ supply and the alga culture to avoid growth inhibition due to ionic strength. Several volatile chlorinated hydrocarbons have been tested. Their EC10 values were several orders of magnitude lower than those obtained with open test systems.     

Biosorption of antimony(V) by freshwater cyanobacteria Microcystis from Lake Taihu,China: effects of pH and competitive ions

There is limited knowledge available on metalloid biosorption by freshwater algae. In this study, biosorption properties of anionic Sb(OH) ₆ ^? by naturally occurring cyanobacteria Microcystis were investigated as a function of initial pH, biosorbent dosage, contact time, and addition sequences of competitive ions, and their binding mechanisms were discussed. The biosorption process was fast and equilibrium was reached at 2 h. Sb(V) biosorption decreased with the increase of pH and the optimum pH range was 2.5–3.0, which corresponded with the changes of surface charges of the cell wall of Microcystis. The biosorption data satisfactorily followed the Freundlich model. The simultaneous addition of H₂PO₄ ^? and Ca²⁺ enhanced Sb(V) biosorption, while NO₃ ^? greatly inhibited the biosorption, compared with single Sb(V) addition. The initial addition of the competitive ions reduced Sb(V) biosorption at higher Sb(V) concentrations, compared with simultaneous addition. A fraction of biosorbed Sb(V) was replaced by the competitive ions which were added subsequently, and the exchange only occurred at higher concentrations of Sb(V). 1.0 mol/L HCl demonstrated the highest desorption efficiency. Speciation analyses indicated that no reduction of Sb(V) into Sb(III) occurred. Based on the results of zeta potential and attenuated total reflection infrared spectroscopy spectra, Sb(OH) ₆ ^? bound to the biomass through electrostatic attraction and surface complexation, and amino, carboxyl, and hydroxyl groups were involved in the biosorption process. The study suggest that Microcystis from cyanobacteria blooms could be used as a potential biosorbent to remove Sb(V) from effluents at environmentally relevant concentrations (≤10.0 mg/L).     

Aquatic photochemistry of paracetamol in the presence of dissolved organic chromophoric material and nitrate

Purpose

This study contains some new findings connected to the photolysis of the drug paracetamol (hereinafter APAP) especially in light of estimating natural conditions, and it will offer information to better evaluate environmental problems connected with this widely used analgesic agent. Only a few studies, so far, have focussed on the photodegradation process of APAP in the natural environment, and the question about the role of the colored/chromophoric dissolved organic matter (CDOM) and nitrate (NO ₃ ^? ) as photoinductors is almost open.

Methods

APAP dissolved in freshwater and pure laboratory water in the presence and absence of CDOM and NO ₃ ^? ions was irradiated using weak-energy photon energies simulating natural conditions.

Results

CDOM and NO ₃ ^? as photoinductors produced only the slow phototransformation of APAP under weak energy radiation, and APAP seemed to be practically resistant to direct photolysis under weak radiant energies available in natural conditions. The estimated reaction efficiencies, in addition to half-lives, speak for that NO ₃ ^? and CDOM do not act as quite independent photoinductors but their effect in conjunction (CDOM?CNO ₃ ^? ?Cwater) is stronger than the separate ones. The principal phototransformation intermediates of APAP were mono-hydroxy derivatives, depending on available photon energies formed via ortho- or meta-hydroxylation, possessing substantial power of resistance to further specific transformation reactions.

Conclusions

The estimated half-life of the phototransformation of APAP in the natural aqueous environment and in the presence of suitable photoinductors will be about 30?days or more.     

Biosorption of zinc and copper from aqueous solutions by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus

Purpose

The objective of this study was to determine the removal of zinc and copper by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus and to investigate changes of algal ultrastructure and photosynthetic pigment.

Methods

Algal cells were exposed for 8 days to different initial zinc or copper concentrations. Heavy metal concentrations were detected by an atomic absorption spectrophotometer. Algal growth, ultrastructure, and photosynthetic pigment were analyzed by a microplate reader, transmission electron microscope, and spectrophotometer, respectively.

Results

Low zinc and copper concentrations induced increase in algal growth, whereas application of high zinc and copper concentrations suppressed the growth of both algae. High metal concentrations also decreased the photosynthetic pigments and destroyed algal cell ultrastructure. The zinc removal efficiency by both algae increased rapidly during the first day and thereafter remained nearly constant throughout the experiment. The copper removal efficiency by both algae increased slowly during the whole experimental periods. In all cultures, the quantity of both metals removed intracellularly was much lower than the adsorbed quantity on the cell surface.

Conclusions

Both strains of the microalgae had proven effective in removing zinc and copper from aqueous solutions, with the highest removal efficiency being near 100%. In addition, C. pyrenoidosa appeared to be more efficient than S. obliquus for removing copper ions. On the contrary, S. obliquus appeared to be more efficient than C. pyrenoidosa for removing zinc ions.     

Determination of microbial activity in activated sewage sludge by dimethyl sulphoxide reduction

A method was developed to determine the dimethyl sulphoxide (DMSO) reduction rate in activated sewage sludge at nearly natural conditions. Linearity of microbially produced dimethyl sulphide with incubation time and sample size was shown. Apart from a fast, sensitive and highly reproducible automatic analysis of dimethyl sulphide, simultaneous determination of mineralisation, respiration and phenol degradation rates was possible. The DMSO reduction rate of samples taken from a municipal sewage plant ranged between 2 and 3 μmol/(g dry matter · h), respiration and mineralisation rates between 30 and 80 μmol/(g · h). Added¹³C₆-phenol was completely degradated after 96 h of incubation. A half-life of 14 h was calculated assuming first order decay. Dose response curves were obtained by incubating samples for 2, 6, 25, and 96 hours after addition of pentachlorophenol. At an incubation time of 6 h, the EC₅₀ values ranged from 20 mg/L (DMSO reduction) to 30 mg/L (phenol degradation) up to 180 mg/L (respiration and mineralisation). Increasing the incubation time to 96 h resulted in a lower EC₅₀ of 9 mg/L for DMSO reduction, whereas it increased to 500 mg/L for respiration and mineralisation.     

Fractionation and Determination of Ah Receptor (AhR) Agonists in Organic Waste After Anaerobic Biodegradation and in Batch Experiments with PCB and decaBDE (8 pp)

Goals, Scope and Background

Anaerobic digestion of organic household waste can lead to an increase in dioxin-like content, as determined by dioxin-specific bioassays. This may be a result of bioactivation of Ah receptor (AhR) agonists into more potent congeners. Work towards identifying the contributing compound groups is important in order to understand the mechanisms and to assess the relevance behind this increase in dioxin-like toxicity, since the residue can be used as a soil fertilising agent. The aim with the present work was to identify compound groups with AhR agonistic properties that caused the previously reported increase in dioxin-like activity after anaerobic biodegradation

Methods

Firstly, chemical fractionation combined with dioxin bioassay testing was used to find bioactive classes of compounds. Secondly, batch digestion experiments with an externally added polychlorinated biphenyl (PCB) mixture (Clophen A50) and with decabrominated diphenyl ether (decaBDE), respectively, were studied as a possible process for transformation of precursors into more potent, dioxin-like compounds. Mesophilic (37ºC) and thermophilic (55ºC) anaerobic digestion were studied. Two different dioxin-specific bioassays were used to analyse AhR agonists in the biodegraded material, the CELCAD and the DR-CALUX.

Results and Discussion

AhR agonist activity was detected in both di- and polyaromatic fractions of digestate extracts, which indicated that a diverse mixture of compounds contributed to the bioassay responses. No quantifiable activities were induced by the monoaromatic fractions. Further fractionation based on planarity revealed higher concentrations of AhR agonists than what was detected after the first fractionation, probably due to non-additive biological interactions of compounds in the extract that were removed in the second fractionation. These results showed significant activity in the non-planar diaromatic fractions and in the co-planar fractions of both diaromates and polyaromates. In the batch experiment with externally added PCB, an increase in dioxin-like activity was seen after 21 days of digestion at mesophilic conditions. After completed digestion, the content of AhR agonists was equal to the start concentration. PCB analysis with GC-MS indicated that dehalogenation of PCBs occurred in the digestors. The batch experiment with decaBDE showed no significant changes in TEQ-concentrations over time.

Conclusions

The results show that the previously reported increase of AhR agonists during mesophilic anaerobic digestion is probably due to an accumulation of several different groups of AhR agonists, both diaromatic and polyaromatic, and both co-planar and non-planar. Batch experiments with externally added PCBs and decaBDE, respectively, did not result in any accumulation of AhR agonist activity after completed digestion, even though chemical analysis indicate a dechlorination of PCBs. Complex, unfractionated extracts were difficult to test using the bioassay approach. Removal of AhR antagonists or otherwise interacting compounds during fractionation may yield bio-TEQ values that are much higher than in the original extract.

Recommendations and Perspective

. Our results indicate that the environmental risk that AhR agonists may pose concerning large-scale anaerobic digestion of organic household waste probably depends on the efficiency of the digester and the sludge residence time. In order to obtain reliable results with the bioassays, an extensive cleanup and fractionation procedure is necessary. Without clean up and fractionation, there is a risk for false negatives and misleading conclusions. DR-CALUX and CELCAD were both suitable for these kinds of studies, provided that suitable fractionation methods are used.

     

Microbial structure and chemical components of aerosols caused by rotating brushes in a wastewater treatment plant

Purpose

Bacterial community structure and the chemical components in aerosols caused by rotating brushes in an Orbal oxidation ditch were assessed in a Beijing municipal wastewater treatment plant.

Methods

Air samples were collected at different distances from the aerosol-generating rotating brushes. Molecular culture-independent methods were used to characterize the community structure of the airborne bacteria in each sample regardless of cell culturability. A clone library of 16S rDNA directly amplified from air DNA of each sample was constructed and sequenced to analyze the community composition and diversity. Insoluble particles and water-soluble ions emitted with microorganisms in aerosols were analysis by a scanning electron microscope together with energy dispersive X-ray spectroscopy and ion chromatogram analyzer.

Results

In total, most of the identified bacteria were Proteobacteria. The majority of sequences near the rotating brushes (the main source of the bioaerosols) were Proteobacteria (62.97 %) with ??-(18.52 %) and ??-(44.45?%) subgroups and Bacteroidetes (29.63 %). Complex patterns were observed for each sampling location, suggesting a highly diverse community structure, comparable to that found in water in the Orbal oxidation ditch. Accompany with microorganisms, 46.36???g/m³ of SO ₄ ^2? , 29.35???g/m³ of Cl^?, 21.51???g/m³ of NO ₃ ^? , 19.76???g/m³ of NH ₄ ⁺ , 11.42???g/m³ of PO ₄ ^3? , 6.18???g/m³ of NO ₂ ^? , and elements of Mg, Cl, K, Na, Fe, S, and P were detected from the air near the aerosols source.

Conclusions

Differences in the structure of the bacterial communities and chemical components in the aerosols observed between sampling sites indicated important site-related variability. The composition of microorganisms in water was one of the most important sources of bacterial communities in bioaerosols. Chemical components in bioaerosols may provide a media for airborne microorganism attachment, as well as a suitable microenvironment for their growth and survival in the air. This study will be benefit for the formulation of pollution standards, especially for aerosols, that take into account plant workers?? health.     

Guide values for contaminated sites in Baden-Württemberg

The treatment of hazardous sites in Baden-Württemberg is based on three legal documents: the state waste disposal art (LAbfG, 1990), the assessment committee directive (KommissionsVO, 1990), and the guide values directive (UM & SM B-W, 1993). The guide values directive was commonly issued by the Ministry of Labor, Health and Social Affairs and the Ministry of the Environment of the state of Baden-Württemberg (UM & SM B-W, 1993) and contains a three-level hierarchy of numerical criteria and rules which serve as both screening levels during the investigation and as remediation objectives. The decision for the appropriate level of remediation is based on feasibility and environmental balance considerations. The levels are ordered as follows:

? Level 1 (Background-Values) On principle, all remediations have to be based first on background levels. In the case of lack of feasibility or negative environmental balance for level-1 objectives use-specific requirements are considered next.

? Level 2 (Assessment-Values for Worst Case Exposure Conditions) The generic requirements underlying level 2 afford appropriate protection for humans regarding the most sensitive uses of the environment. At least four resources are considered on this level: Ground-water as such and its use, the health of humans on contaminated sites, and soil with respect to growth and quality of plants. Barriers against migration of the contaminants, the effect of dilution, and abandonment of certain uses, etc., are not taken into consideration on level 2.

? Level 3 (Site-Specific Requirements) Lack of feasibility or a negative environmental balance of level-2 objectives lead to consideration of site-specific circumstances which may alleviate the requirements. With respect to groundwater, the distinction is again necessary between groundwater as a resource and the use of groundwater. On level 3 the guideline gives rules of how to derive site-specific remediation objectives for groundwater in the form of concentrations and fluxes of contaminants after taking into account barriers, dilution, and the abandonment of uses.

The guideline is the only directive of its kind in the world that regulates both concentrations and fluxes of contaminants into groundwater.     

Differential Sensitivity of a Coccal Green Algal and a Cyanobacterial Species to Dissolved Natural Organic Matter (NOM) (8 pp)

Background

and Aim. In non-eutrophicated freshwaters, humic substances (HS) pose chemical stresses on aquatic organisms and, hence, separating sensitive from less sensitive or even tolerant species. One of the stresses, identified so far, is the reduction of photosynthetic oxygen production and reduction in growth in freshwater macrophytes and algae. In a previous paper, it has been shown that even closely related coccal green algae responded differently upon identical stress by HS, which is consistent with the hypothesis above. Due to their much simpler cellular ultrastructure, cyanobacteria are supposed to be more sensitive to HS exposure than eukaryote should be. One coccal green algal species (Desmodesmus communis) and one cyanobacterium (Chroococcus minutus) were exposed to four natural organic matter (NOM) isolates. One NOM has been isolated from a brown water lake (Schwarzer See) in Brandenburg State; three were obtained from a comprehensive Scandinavian NOM research project and originated from Norway (Birkenes), Finland (Hietajärvi), and Sweden (Svartberget).

Methods

Cultures of D. communis and C. minutus were obtained from the Culture Collection of Algae, Göttingen, and maintained in a common medium. The cultures were non-axenic. The algae and cyanobacteria were exposed under identical conditions to environmentally realistic NOM concentrations. Cell numbers were counted microscopically in Neugebauer cuvettes in triplicates. To avoid limitation by nutrient depletion, the experiments were terminated after 14 to 15 days. Until culture day 12, no growth limitation has been observed in the controls.

Results

All NOM isolates modulated the growth of the algae and cyanobacteria. During the early culture days, there was a slight growth promotion with the coccal green alga and to a much lesser degree with the cyanobacterium. Yet, the major effect were significant reductions in cell yield in both primary producer cultures. C. minutus was much more affected than D. communis. This applies particularly to the three tested Scandinavian NOM isolates, which were effective at concentrations even below 1 mg L-1 DOC.

Discussion

The growth promoting effect may be due to an increase in bioavailability of some trace nutrients in the presence of NOM, the release of some growth promoting substances by microbial or photochemical processing of the NOM, and/or a hormetic effect. The growth reducing effect can be explained as a herbicide-like mode of action that affects the photosystem II most prevalent by blocking the electron transport chain, absorption of electrons, or production of an internal oxidative stress after processing the bioconcentrated HS. Furthermore, it may be postulated that also photo-toxicity of these HS in the algal cells contributes to the overall toxicity; however, experimental evidence is lacking so far.

Conclusions

Upon exposure to HS, cyanobacteria appear to be much more sensitive than coccal green algae and respond in growth reduction. This high sensitivity of cyanobacteria to HS may explain phytoplankton patterns in the field. Eutrophic, humic-rich lakes do not support the cyanobacterial blooms characteristic of eutrophic, but humic-poor lakes. In the humic-rich systems, raphidophytes or, less frequent, specific coccal greens are more common. Obviously, cyanobacteria appear to be unable to make advantage of their accessory pigments (phycocyanin) to exploit the reddish light prevailing in humic-rich lakes.

Recommendation

. At present, no effective structure can be figured out which may be responsible for the adverse effect on the cyanobacterial species. It is reserved to future research whether or not HS may be applied more specifically (for instance, with elevated moieties of the effective structures) as a natural geochemical to combat cyanobacterial blooms.

     

Ecotoxicology,where do you come from and where do you go? (2 pp)

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Does ecotoxicology really contribute to our knowledge about the function of an ecosystem or environment? Is ecotoxicology really a science of its own? The answers to these questions must be NO. The reasons lie in the origin and past of ecotoxicology.Like medicine, ecotoxicology does not have its own scientific theory, but rather borrows from other disciplines: the scientific theory of medicine is biology, and that of ecotoxicology is ecology and pharmacology. Neither medicine nor ecotoxicology see the normal status and routine function of their objects under study. Ecotoxicology regards the environment as being adversely impacted by anthropogenic noxes, mainly chemicals, perhaps based on a paradigm of permanent guilt.

     

Characteristics of precipitation chemistry at Lushan Mountain, East China: 1992–2009

Introduction

Trends in precipitation pH and conductivity during 1992?C2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35?C5.01 and showed a statistically very significant (P?P?Results and discussions Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO ₄ ^2? and NO ₃ ^? were the main anions, and NH ₄ ⁺ and Ca²⁺ the main cations. The anion to cation ratio was 0.8?C1.0, and that of [SO ₄ ^2? ] to [NO ₃ ^? ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH ₄ ⁺ ] to [Ca²⁺] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl^?] to [Na⁺] was about 0.67, somewhat lower than that of natural precipitation.

Conclusions

Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry.