Trace Metal Studies on the Starfish Asterias rubens L. From the Western Baltic Sea

In 1984, 115 samples of the starfish Asterias rubens L. collected in the south-eastern part of Cadet Trench (Mecklenburg Bay/Western Baltic Sea) were analyzed for their contents of a few major (calcium, magnesium) and trace elements (cadmium, copper, iron, mercury, manganese, nickel, lead, selenium and zinc). Distinct differences were found between starfish from different stations, and these are attributed to the composition of the sediments acting as a substrate for their prey (mussels, snails). Except for cadmium, the concentrations of the elements studied all correlated negatively with the diameter and weight of the starfish.

Parallel analyses of starfish arms and the central discs of the same animals showed that iron, zinc, copper and mercury levels were 16 to 30% higher, and selenium, manganese, magnesium, calcium and lead were 4 to 9% higher in the arms. Cadmium concentrations were 20% higher in the central discs than in the arms.

Stock estimations (about 52,000 tons fresh weight) show that starfish play a significant role in the benthic ecosystem of the western Baltic Sea. They can consume up to 200,000 tons of mussels and clams (Mytilus edulis, Macoma baltica) a year and may therefore represent a notable factor in the trace metal balance of the region.     

Methane in the Atmosphere

Methane is present in the troposphere with a volume concentration of about 1.5 ppm. Estimates of Koyama (1963) indicate a predominantly biological origin with a total production rate of about 2.7 × 10¹⁴ g CH₄/yr. From that he estimated the atmospheric lifetime of methane to be around 20 years. Measurements of the C-l4 in methane by Libby and later by Bainbridge, et al. (1961 ) gave a C-l4 content of 75% of recent wood and, therefore, confirm the predominant biological origin, the addition of inactive CH; from industrial sources being only about 25%. Much less is known about sinks of CH₄. Cadle (1966) reported fairly high destruction rates by atomic O, a reaction which should be important at high altitude. Bainbridge (1966) indeed reports a decrease in the measured methane concentration above the tropopause. He, however, considers this decrease too small to account for the destruction rate of 20 years estimated by Koyama. Our measurements on air samples collected on aircraft flights at various altitudes show a high variability of the CH₄ content both with time and altitude.     

Accumulation and elimination of C-PCBs by daphnia magna straus 1820

The accumulation of chlorinated biphenyls in shows a tendency to increase with decreasing water solubility. The depuration times of PCBs from daphnia depend on the temperature of the test water and possibly on the water solubility of the substance. The water solubilities of 2,2′-dichlorobiphenyl, 2,5,4′-trichlorobiphenyl, 2,4,6,2′-tetrachlorobiphenyl and 2,4,6,2′,4′-pentachlorobiphenyl have been determined using ¹⁴C-labelled substances.     

Critical Loads Exceedances in Germany and their Dependence on the Scale of Input Data

Critical load exceedances have been used as an effects-related parameter for guiding international air emission control negotiations. High-resolution critical load data are combined with low-resolution deposition data.This article shows that doing so systematicallyunderestimates `true' critical load exceedances as obtainedfrom combining critical load and deposition data of identicalhigh spatial resolution. 95th percentile critical loadexceedances in EMEP grids based on high resolution depositiondata are 60 and 150% higher (mean values for nutrientnitrogen and acidity, respectively) than critical loadexceedances based on the low resolution EMEP depositionmodel. The latter are used in international negotiations. Differences in individual EMEP grid squares vary betweeninsignificantly different from zero and 340%, depending onregional deposition and critical load characteristics andcritical load types (nutrient nitrogen versus acidity).Exceedances based on high-resolution deposition values arealso compared to EMEP grid averages of these values forforests only. This comparison excludes the effect ofsystematically higher depositions to forests. Still, thescale difference of (averaged, low-resolution) deposition and(high-resolution) critical loads data yields underestimatesof the 95th percentiles by on average ca. 20%.These systematic errors due to the scale dependence should beborne in mind when interpreting effects of internationalemission control measures.     

Neue horizonte für die chemie

The term ‘sustainable development’ is defined and discussed with regard to its significance and its application in the field of chemistry. This is presented using the synthetic organic chemistry as an example. A review of the history of chemistry indicates clearly the necessity for further developments in the course of concepts involving sustainability. Following the eras of bituminous coal tar and mineral oil in both of the two past centuries, a search for new raw materials and a reduction in the global ecotoxicological potential for danger is being strived for. Critical contemplations are mandatory in order to avoid making this term ‘persistence’ into a keyword. Consequently, one must take into consideration the field of research and development as well as reflecting about the classification of chemical and scientific research projects, and their political as well as social relationships. Aside from the new methods of synthesis, this will also require the formulation of other decision-relevant criteria.