Monitoring dissolved organic carbon in surface and drinking waters

The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution. Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer. Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions. Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively. Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment.     

POLICIES FOR RESOLVING THE CLIMATE CHANGE AND THE STRATOSPHERIC OZONE DEPLETION ISSUES: ANTAGONISTIC OR RE-ENFORCING?

Unlike the past, anthropogenic activities have begun to have greaterand greater impact on the environment. Policy formulation is no longerconfined to just responding to an existing set of environmentalconditions, but involves taking into account how the decision mightaffect the original set of environmental conditions to which the originalpolicy was formulated as a response.We discuss how certain policies could be developed, using the resultsfrom two integrated scientific models which incorporate parametersreflecting two air issues: (1) climate change, and (2) stratospheric ozonedepletion. Model results suggest very clearly that these two air issuesare not scientifically independent from each other. Following asingle-issue policy would lead to inconsistencies and undesirableconsequences in other related issues. Thus, the policy decision processhas now become complex.One of the sources of this complexity is the uncertainty in the responseof the environmental system to certain policy decisions, complexityarising from the fact that the environmental system is highly nonlinearand evolving. Model results indicate that it is essential for the policyformulation process to be flexible enough to take into account thenonlinear evolutionary nature of the environmental system. A policymust reflect, and be tailored to, the dynamical history and present stateof the system, if it is to be effective in influencing the future evolution of the system.     

Organizations and supervisors as sources of support and targets of commitment: a longitudinal study

The main objective of this study was to examine the relationship between perceived support and affective commitment, and the linkages between these constructs and some of their common antecedents and consequences. More precisely, using a sample of 238 employees, we conducted a longitudinal study to examine the linkages between the favorableness of intrinsically and extrinsically satisfying job conditions, perceived organizational support, perceived supervisor support, affective commitment to the organization and supervisor, and turnover. Affective commitment to the supervisor was found to completely mediate the effect of perceived supervisor support on turnover, whereas neither perceived organizational support nor organizational affective commitment were significantly related to turnover. Perceived organizational support partially mediated the effect of favorable intrinsically satisfying job conditions on organizational affective commitment and fully mediated the effect of extrinsically satisfying job conditions on organizational affective commitment. Finally, perceived supervisor support totally mediated the effect of favorable intrinsically satisfying job conditions on affective commitment to the supervisor. As a whole, findings suggest that exchange relationships between employees and their supervisors should be further investigated in future turnover research. Copyright © 2003 John Wiley & Sons, Ltd.     

Environmental damage — environmental expenditure 2: Statistical evidence on the Federal Republic of Germany

Summary In part one of this paper (The Environmentalist,1990, pp.301–309) it was shown that conventional economic accounting does not reveal the actual damage to the natural environment, although an ever-increasing share of the Gross National Product is being spent for environmental protection activities. In this, part two of the paper, on the basis of acceptable conventions, the results of an empiric research on defensive expenditures in the GNP are presented, again taking the Federal Republic of Germany as an example. The authors would like to see more research of this type in order to understand better the environmental impacts and the structural deficiencies of modern industrial society. Dr Christian Leipert and Professor Udo E. Simonis have contributed frequently toThe Environmentalist (see 1989, pp.171–183; 1990, pp.25–38; 1990, pp.301–309). Dr Leipert is research fellow, Dr Simonis is research professor at the environmental policy unit of the Science Center Berlin.     

Variation in sensitivity to cadmium among genetically characterized laboratory strains of the midge Chironomus riparius

Estimating the extent of intraspecific variation in sensitivity to contaminant exposure is important in order to explain variation in the outcome of toxicity tests and to predict the effects of chemical stress on natural populations of plants and animals. However, only few studies provide evident data concerning intraspecific variation in life-history traits caused by a differential response to chemical stress. In this study, we compared the life-history response of six laboratory strains of the midge Chironomus riparius to cadmium exposure in a full life-cycle assay. In addition, the level of genetic variation in all strains was measured at five variable microsatellite loci. Several significant differences in life-history traits among the strains were observed in controls and cadmium treatments. The extent of variation among strains was largest at moderate cadmium concentration (0.42 mg Cd/kg dw). At increased Cd concentrations all strains showed similar levels of high mortality and reduced reproductive success. All strains exhibited considerable levels of genetic impoverishment compared to field populations. Strains with low genetic variation showed reduced fitness in the controls and were more susceptible to Cd exposure. For instance, no reproductive success in the lowest Cd treatment was observed for the strain with the lowest level of genetic diversity. In contrast, this Cd concentration had no negative effects on life-history traits of more variable strains. These results confirm recent findings, that inbreeding and reduced genetic variation influence the reaction of populations towards environmental stress. In addition, we show that the level of genetic variation and inbreeding directly influences the outcome of toxicity tests and contributes to the lack of reproducibility of test results among laboratories.     

Risk assessment of biocides in roof paint

BACKGROUND, AIM AND SCOPE: Many surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide may attain in a rainwater collection system. To this end the leaching of specific biocides from a variety of German roof paints was investigated and the resulting concentrations in collected rain water were estimated. MATERIALS AND METHODS: A laboratory simulation was used to determine the time dependant leaching rate of the biocide from the paint into synthetic rainwater. The concentrations of biocide in the leachate were quantified using HPLC. The course of the leachate concentrations over time was fitted using a simple mathematical model. This was then used to estimate concentrations of biocides in a typical household rainwater collection system over time. RESULTS: Surprisingly, the biocides found in the paints did not always concur with the declared biocides. Concerning the modelling of runoff concentrations, it was found that--under the model assumptions--the rain intensity and cumulative raining time after application are the dominant factors influencing the concentration of the biocide. At the highest modelled rain intensity of 40 mm/hour it only takes about 2 hours to reach peak concentrations lower than 0.1 mg/L, at 0.3 mm/hour it takes about 10 hours to reach peak concentrations of 1.3, 0.9, 5.2 and 1.1 mg/L for terbutryn from Emalux paint, terbutryn from Südwest paint, carbendazim from Emalux paint, and carbendazim from MIPA paint, respectively. DISCUSSION: The results confirm that biocides leached from roof paint will be present in roof runoff. The highest estimated peak concentrations are close to the water solubility of the respective biocides. This indicates that the model assumption of a concentration independent leaching rate will tendentially lead to an overestimation of the leached concentrations under these circumstances. However, under most circumstances such as higher rain intensities, and longer time after peak concentrations have been reached, the runoff concentrations are far from the solubility limit, and therefore it is proposed that the model assumptions are tenable. CONCLUSIONS: The leaching of biocides from roof paints can be roughly assessed using a relatively simple approach. The declaration of biocidal ingredients in roof paints should be improved and information on their biocide leaching behaviour should be made available. Furthermore, the estimations should be evaluated by a field study. RECOMMENDATIONS AND PERSPECTIVES: The leaching study indicated that the concentrations of selected biocides can reach significant levels, especially after low intensity rainfall. Taking into account the inherent biological activity of the substances under scrutiny, it can already be concluded that it is not advisable to use runoff water from roofs freshly painted with biocide containing roof paints. These results have been complemented by a literature search of biological effects of the investigated biocides, ecotoxicological tests with several species and a risk analysis for organisms exposed to runoff water. This will be presented in Part 2 of this contribution.     

The use of urban clay-pit ponds for human recreation: assessment of impacts on water quality and phytoplankton assemblages

Artificially created ponds in urban areas may be important biodiversity refugia and may provide recreational services for populations. In order to obtain information on the seasonal development of the environmental conditions, water quality was determined in ten clay-pit ponds situated in the Austrian capital, Vienna. These ponds show high electrical conductivity (up to 3,000 μS cm^???1), indicating elevated levels of salinity, which can be attributed to the geological setting of the underground. Furthermore, the ponds experience a gradient from low to high human pressure resulting from recreational activities (swimming, fishing, urbanisation of the pond boundaries). Results obtained from multivariate statistics methods suggest that ponds were mainly structured by salinity and by algal biomass, which can be attributed to resource supply related with eutrophication. According to their water chemistry, the ponds were classified as meso- to hypereutrophic. Stoichiometric N/P ratios suggest that phytoplankton productivity in hypereutrophic ponds is nitrogen limited, whilst algae in ponds with lower trophic levels experience growth imitation by phosphorus depletion. We eventually related environmental conditions to algal species occurrences and developed a model for algal assemblages indicating the particular trophic state at different seasons.