Interpretation reduces ecological impacts of visitors to world heritage site

Minimal-impact interpretation is widely used to reduce the ecological impacts of visitors to protected areas. We tested whether verbal appeals and/or role-model demonstrations of minimal-impact behavior by a trained guide reduced noise, litter, and trampling impacts on hiking trails in a subtropical rainforest. Interpretation did reduce impacts significantly. Different interpretive techniques were more effective for different impacts. The experimental groups were mature, well-educated professionals; interpretation may differ in effectiveness for different visitors. Interpretation by skilled guides can indeed reduce visitor impacts in protected areas, especially if role modeling is combined with verbal appeals.     

Calibration of the Chemcatcher passive sampler for monitoring selected polar and semi-polar pesticides in surface water

Passive sampling is a powerful method for continuous pollution monitoring, but calibration experiments are still needed to generate sampling rates in order to estimate water concentrations for polar compounds. We calibrated the Chemcatcher device with an uncovered SDB-XC Empore disk as receiving phase for 12 polar and semi-polar pesticides in aquatic environments in flow-through tank experiments at two water flow velocities (0.135 m/s and 0.4 m/s). In the 14-day period of exposure the uptake of test substances in the sampler remained linear, and all derived sampling rates R(s) were in the range of 0.1 to 0.5 L/day. By additionally monitoring the release of two preloaded polar pesticides from the SDB-XC disks over time, very high variation in release kinetics was found, which calls into question the applicability of performance reference compounds. Our study expands the applicability of the Chemcatcher for monitoring trace concentrations of pesticides with frequent occurrence in water.     

Water quality indices across Europe--a comparison of the good ecological status of five river basins

The European Water Framework Directive (WFD) requires the definition of near-natural reference conditions to determine the extent of water bodies' deviation from "good ecological status" caused by stress gradients. However, the classification of ecological quality depends on the assessment method applied and the stressor concerned. While assessment methods that are generally applicable would be favourable, many European countries employ the locally developed water quality metrics that assess the impact of organic pollution (including eutrophication) and the associated decrease in dissolved oxygen. These indices do not specifically address stress from organic toxicants, such as pesticides. The aim of this study was to examine the performance of presently used assessment methods to identify reference conditions of non-contaminated streams in five selected European river basins, covering the geographical region from Spain to Finland, as a crucial prerequisite to indicate toxic gradients. The analysis comprised the Belgium biotic index (BBI), the biological monitoring working party (BMWP) scoring system and the revised German saprobic index. For comparison, we included an adaptation of the recently developed SPEAR index. In two previous field studies, this metric highly correlated with measured pesticide gradients. In this study, SPEAR was the only indicator that was generally applicable to all monitoring data and capable of determining "high ecological status" of reference conditions in all basins. Thus, based upon previous and own results, the authors suggest the species at risk (SPEAR) index to be potentially useful as a European-wide index to address deviations from "good ecological status" due to organic toxicants and recommend it for consideration in integrated water-resource evaluations under the WFD.     

Influence of the initial state of carbon nanotubes on their colloidal stability under natural conditions

The colloidal stability of dry and suspended carbon nanotubes (CNTs) in the presence of amphiphilic compounds (i.e. natural organic matter or surfactants) at environmentally realistic concentrations was investigated over several days. The suspensions were analyzed for CNT concentration (UV-vis spectroscopy), particle size (nanoparticle tracking analysis), and CNT length and dispersion quality (TEM). When added in dry form, around 1% of the added CNTs remained suspended. Pre-dispersion in organic solvent or anionic detergent stabilized up to 65% of the added CNTs after 20 days of mild shaking and 5 days of settling. The initial state of the CNTs (dry vs. suspended) and the medium composition hence are critical determinants for the partitioning of CNTs between sediment and the water column. TEM analysis revealed that single suspended CNTs were present in all suspensions and that shaking and settling resulted in a fractionation of the CNTs with shorter CNTs remaining predominantly in suspension.     

Recovery of high purity zinc from filter ash produced during the thermal treatment of waste and inerting of residual materials.

The method described below recovers zinc, a valuable metal that is present in high concentrations in filter ash from the thermal treatment of waste, and returns the filter ash stripped of heavy metals to the combustion process in order to destroy organic substances. On an industrial scale, the heavy metals in the filter ash were mobilized by means of hydrochloric acid in the acidic fluids produced in the flue-gas scrubbing process without the addition of further chemicals. A pilot plant for implementing the selective reactive extraction (SRE) method on the ash extracts, using a highly selective complexant, was operated over a period of several months in order to obtain a concentrated, high-purity zinc salt solution (mono metal solution). A zinc depletion rate of 99.8% in the aqueous extract was achieved using mixer-settler units. The residual zinc concentration in the waste water was then < 2 mg L(-1). By stripping the loaded organic phase, a concentrated, high-purity mono metal solution with 190 g L(-1) zinc was obtained. Zinc metal with a purity > 99.99% is then separated by means of electrolysis. To destroy organic substances present in the filter ash, particularly dioxins and furans, the extracted filter ash cake was returned to the combustion process together with household waste. Plant operation, raw and pure gas parameters, and quality of the bottom ash produced were not impacted by such recirculation. The profitability of the overall process is attributable both to the recovery of valuable zinc metal and to the cost savings made in waste water treatment and in the disposal of the waste combustion residues because the remaining mixture of filter ash and bottom ash can be reused in a combined form. This method therefore supports the sustainable and economically viable reuse of filter ash.     

Opportunity cost based analysis of corporate eco-efficiency: A methodology and its application to the CO2-efficiency of German companies

In this paper, we propose the return-to-cost-ratio (RCR) as an alternative approach to the analysis of operational eco-efficiency of companies based on the notion of opportunity costs. RCR helps to overcome two fundamental deficits of existing approaches to eco-efficiency. (1) It translates eco-efficiency into managerial terms by applying the well-established notion of opportunity costs to eco-efficiency analysis. (2) RCR allows to identify and quantify the drivers behind changes in corporate eco-efficiency. RCR is applied to the analysis of the CO₂-efficiency of German companies in order to illustrate its usefulness for a detailed analysis of changes in corporate eco-efficiency as well as for the development of effective environmental strategies.     

Energy or compost from green waste? – A CO2 – Based assessment

Green waste is increasingly extracted from the material recycling chain and, as a result of the financial subsidy arising from the German renewable energy law for the generation of energy from renewable raw materials; it is fed into the energy recovery process in biomass power stations. A reduction in climate relevant gases is also linked to the material recovery of green waste – in particular when using composts gained from the process as a new raw material in different types of potting compost and plant culture media as a replacement for peat. Unlike energy recovery, material valorisation is not currently subsidised. Through the analysis of material and energy valorisation methods for green waste, with particular emphasis on primary resource consumption and CO₂-balance, it could be determined that the use of green waste for energy generation and its recovery for material and peat replacement purposes can be considered to be on a par. Based on energy recovery or material oriented scenarios, it can be further deduced that no method on its own will achieve the desired outcome and that a combination of recycling processes is more likely to lead to a significant decrease of greenhouse gas emissions.