Grenzüberschreitender Seeuferschutz im Spannungsfeld von Nutzungsinteressen am Beispiel Bodensee (Teil 1)

The shores of many Central European lakes located in the hinterland of large conurbations are heavily endangered by intensive settlement, traffic, sewage input, manipulation of the water level, tourism and recreation. This increasing impact has negatively affected the function of the lake shore in respect to conservation and species protection, to water protection and its importance for recreation. This paper describes the overlap of the multiple uses and the precautions planned since 1981 on the national and international level to guarantee the essential multiple functionality, e.g. as drinking water reservoir for the conurbations in the northern part of Baden-Württemberg, as supraregional centre for water sports and tourism, and as an important environment for endangered plant and animal species. Management measures include regional planning as well as the international water protection and preservation with many contributions from non governmental international organisations. Given a high agreement concerning these aims, many indispensable actions could successfully be realised on the political and administrative level. On the basis of 14 topics we follow the development since 1981, most recently also driven by the EU (FFH Natura 2000, Water framework directive). Backlogs became obvious for four topics: 1. The lack of efficient reviews on completed measures, 2. gaps in basic understanding, 3. The dragging harmonisation of an integrated shore protection program across the borders, and 4. the lack of concepts for a sustainable development including plans for monitoring.     

Thermische Schlammkonditionierung nach dem Porteous-Verfahren

In Nuremberg (Germany), each year about 25,000 tons (dry matter) of sewage sludge are obtained as by-product of waste water treatment. The digested sludge consists of 96% water. Until 1992 it was thermally stabilized using the Porteous procedure: the sludge was heated in an autoclave up to a temperature of 180–200 °C at a pressure of 28 bar. After pressure reduction and moving to a thickener, a substantial part of the liquid could be removed. After running through a chamber filter, the sludge contained only about 50% dry matter. This treatment does not only remove water; organic matter is also degraded or evaporated. Between November 1991 and May 1992, the sludge was analyzed four times before and after the drying process and examined for heavy metals (Pb, Cd, Cr, Cu, Ni, Hg, Zn), polychlorinated biphenyls (PCB) and PCDD/F. The concentration of heavy metals and PCB (related to dry matter) increased by a faktor of 1.3 after the drying process. This effect may be explained by the decrease of organic matter during drying. In the case of PCDD/F, the ITQ increased by a factor of 3.2, for some congeners even by a factor of 8. The only explanation can be that during thermal conditioning PCDD/F is formed by precursors as chlorophenols. This formation is probably catalyzed by metals as copper or nickel and sped up by the higher temperatures.     

Computational fluid dynamics analysis of the effects of reactor configuration on disinfection efficiency.

The efficacy of disinfection processes in water purification systems is governed by several key factors, including reactor hydraulics, disinfectant chemistry, and microbial inactivation kinetics. The objective of this work was to develop a computational fluid dynamics (CFD) model to predict velocity fields, mass transport, chlorine decay, and microbial inactivation in a continuous flow reactor. The CFD model was also used to evaluate disinfection efficiency in alternative reactor designs. The CFD reactor analysis demonstrates that disinfection efficiency is affected by both kinetics and mixing state (i.e., degree of micromixing or segregation). Residence time distributions (RTDs) derived from tracer analysis do not describe intrinsic mixing conditions. The CFD-based disinfection models account for reactor mixing patterns by resolution of the reactor velocity field and thus provide a better prediction of microbial inactivation than models that use an RTD.     

Combined effects of copper and food on the midge Chironomus riparius in whole-sediment bioassays

Effects observed in whole-sediment bioassays must be seen as the joint effect of all sediment characteristics. In whole-sediment bioassays, however, adverse effects on test organisms are usually attributed to the presence of contaminants and effects of food are often ignored. The aim of this study was to analyze the response of the midge Chironomus riparius to sediment spiked with different combinations of food and copper. The responses of C. riparius to these spiked sediments were assessed in 10-day whole-sediment bioassays. Decreases in survival, dry weight, and length of C. riparius were observed with increasing copper concentrations. However, an increase in the amount of food resulted in an increase of larval dry weight and length until copper concentrations reached a critical threshold of 200 mg/kg. In addition, an increase in the amount of food resulted in a decrease of accumulated copper in the larvae. The present study demonstrated that the combination of copper and food in the sediment determines the performance of C. riparius in whole-sediment bioassays. The dependency of C. riparius on high feeding levels, which mask toxic effects, questions its suitability as a test organism for whole-sediment bioassays. Because benthic communities in polluted ecosystems are often exposed to varying levels of both food and toxicants it is concluded that the trophic state of the ecosystem may alter the ecological risk of sediment-bound toxicants to opportunistic benthic invertebrates such as C. riparius.     

Municipal landfills exhale newly formed organotins

For the first time we are able to report the identification and quantification of several unexpected alkylated tin compounds such as dimethyldiethyltin, trimethylethyltin and propyltrimethyltin in European municipal waste deposits, by using GC-ICP-MS. Future studies will reveal whether their origin is from the degradation of butyl-, or octyltin compounds or simply products of de novo synthesis within the landfill environment.     

An Overview of Contaminant-Related Issues Identified by Monitoring in San Francisco Bay

The San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP) began in 1993 and is sponsored by 74 local, state, and federal agencies and companies through their discharge or Bay use permits. The RMP monitors water, sediment, toxicity, and bivalve bioaccumulation at 25 sites in the Bay that are considered to represent "background" conditions. Several major environmental issues have been identified by the RMP. Polychlorinated biphenyls and mercury were often above water quality guidelines, and often occurred in fish tissues above U.S. Environmental Protection Agency (U.S. EPA) screening values. Concentrations do not appear to be decreasing, suggesting continuing inputs. Episodes of aquatic toxicity often occurred following runoff events that transport contaminants into the Bay from urbanized and agricultural portions of the watershed. Sediment toxicity occurred throughout the Bay, and has been correlated with concentrations of specific contaminants (chlordanes, polynuclear aromatic hydrocarbons) at some locations; mixtures of contaminants were probably also important. Since the RMP does not monitor all ecosystem components, assessments of the overall condition of the Bay cannot be made. However, in terms of contamination, the RMP samples suggest that the South Bay, and North Bay sites are moderately contaminated.