Patterns of organic osmolytes in two marine bivalves, Macoma balthica, and Mytilus spp., along their European distribution

Patterns of nine intracellular free amino acids (FAA), which are utilized as organic osmolytes for salinity-induced cell volume regulation in marine osmoconformers, were compared in five Macoma balthica populations and seven Mytilus spp. populations along their European distribution. Three types of FAA patterns were classified within both taxa: a northern Baltic type, a southern Baltic type and an Atlantic/Mediterranean type which mainly differ regarding the share of alanine and taurine. Differences are discussed in relation to habitat salinity and population genetics. Along a salinity gradient, the total size of the intracellular FAA pool did not differ between sympatric M. balthica and Mytilus spp., and was significantly correlated with habitat osmolality in a range from 70 to 600 mmol kg⁻¹ H₂O (oligohaline to mesohaline) in both bivalves. In M. balthica, this correlation was mainly based on significant correlations of alanine (15–100 mmol kg⁻¹ DW), glycine (30–100 mmol kg⁻¹ DW) and taurine (0–70 mmol kg⁻¹ DW) with habitat osmolality. In Mytilus spp., only glycine (25–100 mmol kg⁻¹ DW) and taurine (4–180 mmol kg⁻¹ DW) were significantly correlated with habitat osmolality. The concentration of alanine was three times lower in Mytilus spp. than in M. balthica and did not correlate with habitat osmolality. Within a habitat osmolality range from 600 to 1,100 mmol kg⁻¹ H₂O (mesohaline to marine) the concentration of FAA remained constant in both taxa. It is suggested that under marine conditions additional organic osmolytes must become more important for cell volume regulation in Macoma and Mytilus.     

Land-Use Change and Forestry in the Kyoto Protocol

Mitigation and Adaptation Strategies for Global Change -     

Seasonal fluxes and temperature-dependent accumulation of persistent organic pollutants in lakes: The role of internal biogeochemical cycling

A dynamic flux model for lakes taking into account the interactions between atmospheric depositional and biogeochemical processes (BIODEP model) was used to assess the importance of internal cycling and biogeochemical processes with respect to accumulation of four different polychlorinated biphenyls (PCBs) (congeners 28, 52, 101 and 153) in Lake Redo, a high-altitude lake in the Spanish Pyrenees. To investigate the effect of temperature on sediment accumulation, the model was run at different temperatures and corresponding sediment inventories were plotted vs. reciprocal temperature. In line with measurements from a previous study looking at sediment inventories of 19 European high-altitude lakes (MOLAR study), we found a stronger temperature dependence of lake sediment concentrations for the less volatile/less soluble PCBs. Seasonal and annual mass balances were investigated and highlighted the importance of internal lake processes controlling the differences in sediment accumulation for the different PCB congeners. For example, the higher temperature dependence of sediment inventories for the high chlorinated congeners is due to the fast dynamics of water-to-sediment transport in comparison to atmospheric deposition processes.     

Wastewater reuse in Mediterranean semi-arid areas: The impact of discharges of tertiary treated sewage on the load of polar micro pollutants in the Llobregat river (NE Spain)

The presence of sewage-borne micro contaminants in environmental waters is directly related to the discharge of treated effluents from wastewater treatment plants (WWTP) and the flow rate of the receiving river waters. Mediterranean rivers, in particular, are characterized by important fluctuations in the flow rates and heavy pollution pressures resulting from extensive urban, industrial and agricultural activities. This translates into contamination levels in these rivers often higher than those in other larger European basins. The present work provides an overview of the occurrence of five groups of organic contaminants (131 compounds) namely pharmaceuticals, illicit drugs, polar pesticides, estrogens, alkylphenols and related ethoxylates in WWTP tertiary treatment effluents. Data gathered during a period of water reuse carried out in the lower stretch of the Llobregat river (NE Spain), in the surroundings of the town of Barcelona as a consequence of the severe drought that took place along the years 2007-2008 are presented as illustrative example. In general, measured concentrations of the target compounds were in the low to mid ng L⁻¹ range. The total concentration of each compound class downstream to the discharge point was similar or slightly higher than that found upstream. Regarding the loads calculated for each compound, the relative contribution from the river upstream and the tertiary effluent were highly compound depending with no apparent trend. However, estimation of the overall bulk loads for each compound class determined in the Llobregat river showed the following rank order: pharmaceuticals > alkylphenols > pesticides > illicit drugs ? estrogens.     

Structure-activity relationships of larvicidal monoterpenes and derivatives against Aedes aegypti Linn

In the search for larvicidal compounds against Aedes aegypti L. (Diptera: Culicidae), a collection of monoterpenes were selected and evaluated. R- and S-limonene exhibited the highest larvicidal potency (LC₅₀ = 27 and 30 ppm, respectively), followed by γ-terpinene (LC₅₀ = 56 ppm) and RS-carvone (LC₅₀ = 118 ppm). Structural characteristics which may contribute to the understanding of the larvicidal activity of monoterpenes were empirically identified. The presence of heteroatoms in the basic hydrocarbon structure decreases larvicidal potency. Conjugated and exo double bonds appear to increase larvicidal potency. Replacement of double bonds by more reactive epoxides decreases the larvicidal potency. The presence of hydroxyls in the cyclic structure resulted in decreased potency, probably due to increased polarity indicanting that lipophilicity seems to play an important role in increasing the larvicidal potency in this set of compounds.     

Defining Chlorophyll-a Reference Conditions in European Lakes

The concept of “reference conditions” describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between “high” and “good” status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets.     

Morphological Changes in Poly(Caprolactone)/Poly(Vinyl Chloride) Blends Caused by Biodegradation

The biodegradation of blends of poly(caprolactone) (PCL) and poly(vinyl chloride) (PVC) has been studied. Blends of composition PCL/PVC 1:1 and 1:2 w/w were tested. The 1:1 blend contained crystals in the as-cast state and became more crystalline on exposure to different bio-active agents. The 1:2 blend was amorphous in the as-cast state but developed a significant crystal component after 4 months exposure to the bio-agents. Three bio-active agents were used and all were found to produce qualitatively similar behaviour but their activity was somewhat different. For both the 1:1 blend and the 1:2 blend the ranking of the three bio-active agents tested, in increasing order, was Curvularia sp.; Trogia buccinalis; Phanerochaete chrysosporium.