Geochemical characterisation of the thermo-mineral waters of Greece

Environmental Geochemistry and Health - Geothermal areas of Greece are located in regions affected by recent volcanism and in continental basins characterised by elevated heat flow. Many of them...     

The effect of chlorine position of chlorinated phenols on their dechlorination kinetics by Fenton's reagent

Chlorine position of chlorophenol isomers has a significant effect on the dechlorination kinetics of monochlorophenols, dichlorophenols, and trichlorophenols during Fenton oxidation. The effects have been evaluated by the rate constants of the dechlorination kinetic model developed in this study. It is found that the dechlorination rate of 3-CP is faster than that of 4-CP, which is faster than that of 2-CP. Since OH and Cl groups on the aromatic ring are ortho and para directors, the directory effect of OH and Cl groups enhances the dechlorination kinetics of 2-CP due to acceleration of the hydroxylation of 2-CP. Therefore, the dechlorination kinetics increases accordingly. For trichlorophenols (TCP), steric hindrance plays an important role during their dechlorination process. Specifically, the closer the chlorine atoms locate with each other on the aromatic ring, the more difficult the dechlorination processes will be. The dechlorination kinetics of dichlorophenols seems to be affected by both directory effect of OH and Cl groups and the effect of steric hindrance of chlorine atoms. The directory effect of OH and Cl groups on trichlorophenols decreases since the chlorine atom occupied the positions which are the most favorable for hydroxyl radical attack.     

Versuchsanlage zur energetischen Beurteilung von Substraten und Kofermentaten für Biogasanlagen

Goal, Scope and Background

Worldwide energy requirements are constantly increasing. Rising prices and the necessity to secure the future energy supply have led the decision-makers in politics and economy to focus on the more intensive use of their own resources. Before the background of possible climatic effects caused by the use of fossil energies, the use of renewable resources as primary energies, with its narrow C-circulation, have gained in importance, particularly in terms of economic aspects. The production of biogas is of specific interest here. It is a sensible ecological investment and a solid source of income for our agriculture.

Material and Methods

The operator uses a complex biological system in a plant with high investment costs. An economic operation is only possible if the process parameters are optimized and the properties of the substrates and the co-ferments are known. For the important determination of the blogas potential, we present an efficient and robust system, which is easy to handle and low cost, that has been developed by the LHL and LLH at the Eichhof. This procedure enables one to make statements on the implementation dynamics and is also suited to judge the fermentation process depending on the size of particles, as the co-ferments are used in a practice-oriented consistency.

Results

With the described fermentation apparatus you can not only assess the potential development of biogas and methane, but also the process of fermentation. The sum-graphs determined allow one to make conclusions on the implementation dynamics and, thus, on the optimization of the process. The advanced equipment makes it possible to determine the process of fermentation and the gas yield under different retention times and digester loads. The determination of the potential of the biogas and also the evaluation of the continuous fermentation are related to a specific correction factor won from the standard.

Discussion

A prerequisite for economic process management is the knowledge of the attainable gas yield and the fermentation process of substrates and co-ferments. A precise calibration is the quality basis for the results achieved with this method, as is the case with other fermentation tests as well. For the tests, a highly homogeneous substrate, which guarantees a continuous biological activity in the digesters, ought to be used. The possibility of determining optimum retention times and digester loads with this equipment makes costly tests with a full scale reactor unnecessary.

Conclusions

All tests run demonstrated that the fermentation apparatus originally developed to determine the biogas yield is absolutely suited to also assess the impact of different digester loads and retention times.

Recommendations

The problem of the suitability and the potential of different materials, the optimum reactor performance and the combination of different processes of energy generation from renewable but also conventional resources will increaseingly become the focus of laboratory tests. The following subjects have to be taken into account:

- Testing different materials on their suitability

- Evaluation security of common and new co-ferments

- Guidelines for mixtures to optimize reactor performance

- Mixtures of different substrates and co-ferments available to a particular operator (also with the help of simulation models)

- Processing changing quantity proportions of plants won from a rotation of crops altered for energy generation

- Other parameters like pre-fermentation, particle size and fer mentation supplements.

Perspective

These tests with a high practical relevance are supposed to contribute to a reliable method of producing biogas, in order to optimize the yield of gas production, but also to find a calibration of less costly procedures like those involving Near Infrared Spectroscopy (NIRS).     

High occurrences of brominated lipid fatty acids in boreal sponges of the order Halichondrida

Sponges of warm- and temperate- but also cold-waters are known to synthesize structurally diverse primary and secondary metabolites. These compounds fulfill a variety of functions including adaptations of the cell membranes to environmental conditions. We show here that boreal sponges of the order Halichondrida are rich sources of brominated lipid fatty acids. The comparison of lipid compositions of halichondrid Demospongiae from boreal and warmer waters indicates an accumulation of brominated fatty acids in sponges from colder settings. Moreover, the spatial distribution of brominated fatty acids in the sponge tissue of one widely distributed sponge of the North-East Atlantic (Phakellia ventilabrum) hints to a function related to membrane fluidity and permeability rather than to defense against predation. However, brominated fatty acids are diagnostic for the presence of bromoperoxidases in sponges and may therefore be potentially useful as markers in a chemical screening for secondary metabolites of pharmacological interest.     

Individual variation in pheromone emission and termination patterns in female Anomala cuprea

Summary. Individual variations in pheromone emission patterns were examined in a scarab beetle, Anomala cuprea Hope (Coleoptera: Scarabaeidae), by headspace collection of airborne volatiles from individual females. The amount of pheromone obtained varied among virgin females, and about 16% of these females (“silent” females) did not emit detectable amount of pheromone throughout the experimental period. There was no clear temporal pattern of peak pheromone emission for 19 days after the onset. More than half of the laboratory mated females completely stopped releasing pheromone after the first mating, while the rest of them continued releasing pheromone, frequently followed by additional mating. Received 26 March 2001; accepted 28 January 2002.     

Defining Nutrient and Biochemical Oxygen Demand Baselines for Tropical Rivers and Streams in São Paulo State (Brazil): A Comparison Between Reference and Impacted Sites

Determining reference concentrations in rivers and streams is an important tool for environmental management. Reference conditions for eutrophication-related water variables are unavailable for Brazilian freshwaters. We aimed to establish reference baselines for São Paulo State tropical rivers and streams for total phosphorus (TP) and nitrogen (TN), nitrogen-ammonia (NH₄ ⁺) and Biochemical Oxygen Demand (BOD) through the best professional judgment and the trisection methods. Data from 319 sites monitored by the São Paulo State Environmental Company (2005 to 2009) and from the 22 Water Resources Management Units in São Paulo State were assessed (N = 27,131). We verified that data from different management units dominated by similar land cover could be analyzed together (Analysis of Variance, P = 0.504). Cumulative frequency diagrams showed that industrialized management units were characterized by the worst water quality (e.g. average TP of 0.51 mg/L), followed by agricultural watersheds. TN and NH₄ ⁺ were associated with urban percentages and population density (Spearman Rank Correlation Test, P < 0.05). Best professional judgment and trisection (median of lower third of all sites) methods for determining reference concentrations showed agreement: 0.03 &; 0.04 mg/L (TP), 0.31 &; 0.34 mg/L (TN), 0.06 &; 0.10 mg-N/L (NH₄ ⁺) and 2 &; 2 mg/L (BOD), respectively. Our reference concentrations were similar to TP and TN reference values proposed for temperate water bodies. These baselines can help with water management in São Paulo State, as well as providing some of the first such information for tropical ecosystems.