波罗的海高盐传送带,或波罗的海中的翻转环流及咸、淡水的混合

我们使用三维波罗的海模型模拟的做法进行了一项波罗的海水团环流的研究.来自北大西洋的咸水经丹麦海峡流入波罗的海,在波罗的海上涌并与从各河流流入的淡水混合形成"波罗的海高盐传送带".我们利用翻转流量函数和拉格朗日轨迹线对来自大贝尔特和厄勒海峡的成水与淡水的混合情况进行了调查.该翻转流量函数被作为一种具有4个不同垂直坐标(深度、盐度、温度和密度)的函数进行计算,以便了解水的路径以及它在什么地方上涌并混合.在波罗的海本体内发现了与南大洋中的迪肯环流(Deacon Cell)类似的虚拟深度翻转环流的存在,它与哥特兰岛附近的旋转环流相符,当翻转流量函数投射在密度层上时,这一虚拟深度翻转环流就消失了.我们已经开展了一项拉格朗日轨迹线研究,以便更好地认识该环流以及咸水与淡水的混合情况.对这些水团在波罗的海中的停留时间的计算结果为26～29年,而拉格朗日扩散在5年后达到海盆饱和.     

Ökotoxikologische Untersuchung von Sedimenten und Schwebstoffen

The potential risk of ground-water contamination through the infiltration of contaminants originating from suspended matter and sediments deposited within flood retention areas in the Upper Rhine valley, as well as subsequent problems for drinking water production, were analyzed by means of the bacterial dehydrogenase activity (DHA; sediment contact test) assay with Arthrobacter globiformis and in a prolonged embryo toxicity assay using zebrafish (Danio rerio). Since the direct uptake of contaminants from particle-bound sources has usually been assumed to play only a minor role in bioaccumulation, the availability of organic extracts to biota has generally been regarded as being overestimated. In order to confirm or discard this hypothesis, organic (acetone) extracts of recently suspended, freeze-dried matter, as well as freeze-dried sediments collected from Rhine flood plains (i.e. soil samples) were compared to corresponding native samples in order to screen for the relative availability of particle-bound contaminants. Whereas a significantly higher ecotoxicological burden was observed for some native soil samples, organic extracts of suspended matter proved to be more toxic than corresponding native samples when compared to organic extracts using each test system. With respect to organic extracts, the suspended matter samples were more toxic than soil samples taken from a rarely flooded site. In contrast to the native samples, the rarely flooded soils revealed a higher toxicity than suspended matter. Therefore, organic extracts did not necessarily overestimate the toxicity of soil and suspended matter samples. Moreover, considerable toxicity of particle-bound contaminants to both bacteria and fish embryos, even in native samples, corroborate the hypothesis that particle-bound contaminants may be more readily available than is generally assumed.     

Pharmazeutische Wirkstoffe und Umweltschutz

On 26 April this year the German Environmental Advisory Council (SRU) published a statement on ‘Pharmaceuticals in the environment’ and pointed considerable need for action to understand and to reduce the risks from diffuse pharmaceutical inputs in the environment. On the one hand, it is urgently necessary to improve the database for environmental risk assessments; on the other hand measures should already be taken to minimize harmful inputs. Fortunately, the new regulations for an application for an authorization to market new pharmaceuticals require an environmental risk assessment. However, there is a lack of information on possible impacts from long time admitted medicines which may be responsible for harmful active substances detectable in the environment. To remove this data deficit, a European programme for risk evaluation of old pharmaceuticals should be established. It is necessary for an adequate risk assessment to look at all impacts of one active substance or all substances same-directed in their active potential summativ and to generate regularly consumption data in particular for the use of veterinary products. The hot spots of contamination are the introduction of large scale volumes of active pharmaceutical ingredients for human use like diclofenac and carbamazepin as well as hormones into surface waters, as well as the application of antibiotics-loaded economic fertilizers on soils. Not to be neglected is the application of antiparasitics in animals kept on pasture. With the assessment of the use of pharmaceuticals for all purposes special attention is needed on antibiotic resistance. For the mitigation of environmental exposures there are exposures measures necessary to reduce use of antibiotics in farming, for the application of new effective technologies in treatment sewage — as for example ozonation, filtration with activated carbon or membrane filtration — as well as for the labelling of environmentally harmful medicinal products.     

Relationship between photosynthesis and non-photochemical quenching of chlorophyll fluorescence in two red algae with different carotenoid compositions

Algae are continuously exposed to short-term fluctuations in irradiance. We investigate how two red algae species regulate photosynthetic efficiency to cope with such changes and identify some strategies that differ from higher plants. Two red algae, Gracilaria domingensis and Kappaphycus alvarezii, with antheraxanthin and lutein as major xanthophylls, respectively, reacted to the onset of low light (below E _k) with a substantial decrease of NPQ. This is different from higher plants, but similar to previous observations in, e.g. cyanobacteria where it indicates an increase in the effective absorbance cross-section of Photosystem II (PSII) by state transition. Kinetic studies in continuous light revealed a high susceptibility of PSII to light stress ((1-q _P)/NPQ) in K. alvarezii immediately after the sudden onset of high light, followed by a decrease. This was caused by a slower onset of NPQ in K. alvarezii, followed by acclimation. In G. domingensis, susceptibility of PSII to light stress was stable with time, but absolute values of (1-q _P)/NPQ were higher than in K. alvarezii. These observations suggest that K. alvarezii may be better adapted to high light levels, but is less well prepared for large sudden changes in irradiation. In K. alvarezii, photosynthesis continued to increase with increasing irradiation when NPQ was saturated. As (1-q _P) and NPQ were still balanced in this situation, most likely, processes other than photosynthetic oxygen release are responsible for the increasing net O₂ production observed.     

Biomarker responses of the earthworm Aporrectodea tuberculata to copper and zinc exposure: differences between populations with and without earlier metal exposure

Biomarkers in the earthworm Aporrectodea tuberculata (Eisen) were measured to find out their possible induction under Cu and Zn exposure and differences in the responses between two populations with different exposure history. The biomarkers applied were concentration of metallothioneins (MT), and cytochrome P4501A (CYP1A) monooxygenase and glutathione-S-transferase (GST) activities. These were measured from earthworms sampled at three distances from a steel smelter in Finland and from the individuals from two populations, one with and another without earlier metal exposure, exposed to three combined Cu/Zn concentrations in the laboratory. In the field, MT concentration, and cytochrome CYP1A and GST activities decreased with increasing distance from the smelter. In the laboratory, biomarker responses varied in relation to the duration and level of exposure, and they were also dependent on the population. The endpoints appeared to be analytically reproducible and sensitive parameters in A. tuberculata, and thus, they can be used in ecotoxicological field monitoring and in experimental research in the laboratory.     

The Baltic haline conveyor belt or the overturning circulation and mixing in the Baltic

A study of the water-mass circulation of the Baltic has been undertaken by making use of a three dimensional Baltic Sea model simulation. The saline water from the North Atlantic is traced through the Danish Sounds into the Baltic where it upwells and mixes with the fresh water inflow from the rivers forming a Baltic haline conveyor belt. The mixing of the saline water from the Great Belt and Oresund with the fresh water is investigated making use of overturning stream functions and Lagrangian trajectories. The overturning stream function was calculated as a function of four different vertical coordinates (depth, salinity, temperature and density) in order to understand the path of the water and where it upwells and mixes. Evidence of a fictive depth overturning cell similar to the Deacon Cell in the Southern Ocean was found in the Baltic proper corresponding to the gyre circulation around Gotland, which vanishes when the overturning stream function is projected on density layers. A Lagrangian trajectory study was performed to obtain a better view of the circulation and mixing of the saline and fresh waters. The residence time of the water masses in the Baltic is calculated to be 26-29 years and the Lagrangian dispersion reaches basin saturation after 5 years.