The Rhine red,the fish dead—the 1986 Schweizerhalle disaster,a retrospect and long-term impact assessment

Background

The November 1, 1986 fire at a Sandoz Ltd. storehouse at Schweizerhalle, an industrial area near Basel, Switzerland, resulted in chemical contamination of the environment. The storehouse, which was completely destroyed by the fire, contained pesticides, solvents, dyes, and various raw and intermediate materials. The majority of the approximately 1,250 t of stored chemicals was destroyed in the fire, but large quantities were introduced into the atmosphere, into the Rhine River through runoff of the fire-fighting water, and into the soil and groundwater at the site. The chemicals discharged into the Rhine caused massive kills of benthic organisms and fish, particularly eels and salmonids. Public and private reaction to the fire and subsequent chemical spill was very strong. This happened only a few months after the Chernobyl accident and it destroyed the myth of immunity of Switzerland regarding such catastrophes.

Aim

This article reviews the damaging events of November 1986 and aims at striking stock two decades later.

Results and discussion

In the aftermath of this once-per-century accident, the aim was to obtain new knowledge for the environmental sciences and to achieve progress for water pollution control issues. The following themes are discussed: mitigation measures by the chemical industry and by the governmental authorities, activities of environmental protection organizations, chemical and biological monitoring, alert organization, ecological damages, ecotoxicological effects assessment, recovery and alteration of the river biology, return of the salmon, drinking water supplies, research programs, education of environmental scientists, and visions for the future.

Conclusions

The catastrophic pollution of the Rhine in November 1986 has triggered by the openly visible damages of the river biology that subsequently significant progress was made towards the prevention of such environmental catastrophes. The crucial risk reduction measures in the chemical industry, legal regulations and controls as well as chemical and biological monitoring of the river water quality were substantially improved. Politics and chemical industry have learned their lectures and have proceeded accordingly.

Recommendations

A drastic acute contamination, as it has happened at Schweizerhalle in 1986, is clearly recognizable by the toxic effects, which it is causing. This can lead to mitigation activities, which are positive considering a long-term perspective. However, the less obvious effects of chronic water pollution should receive more attention as well as the ongoing alteration of the biocenosis. A high water quality must be demanded for using water from the Rhine to produce drinking water. In that context, micropollutants should also be considered and particular attention should be payed to emerging contaminants.

Perspectives

The big chemical storehouse fire of 1986 had an important impact on the transboundary cooperation and has improved the willingness for international cooperation. The fire catastrophe of Schweizerhalle has triggered many activities in particular for the Rhine River. Overall, the effects are positive on the basis of a long-term perspective. The applied whole basin approach gives an example on a global basis for other river systems, which still are more heavily polluted.

     

ESTROM,Environmental Science and Technology in Romania—programme overview

Environmental Science and Pollution Research -     

Particle size distribution of airborne Aspergillus fumigatus spores emitted from compost using membrane filtration

Information on the particle size distribution of bioaerosols emitted from open air composting operations is valuable in evaluating potential health impacts and is a requirement for improved dispersion simulation modelling. The membrane filter method was used to study the particle size distribution of Aspergillus fumigatus spores in air 50 m downwind of a green waste compost screening operation at a commercial facility. The highest concentrations (approximately 8 × 10⁴ CFU m⁻³) of culturable spores were found on filters with pore diameters in the range 1–2 μm which suggests that the majority of spores are emitted as single cells. The findings were compared to published data collected using an Andersen sampler. Results were significantly correlated (p < 0.01) indicating that the two methods are directly comparable across all particles sizes for Aspergillus spores.     

Numerical simulation of an array of fences in Saemangeum reclaimed land

This paper discusses about the quantitative effect of windbreak fences on wind velocity in the reclaimed land at Saemangeum in South Korea. Windbreak fences were constructed in the reclaimed land to reduce the wind velocity to prevent the generation and diffusion of dust. However, up to this time, no in-depth studies were conducted to quantitatively measure the effect of the windbreak fences on wind velocity thus an optimum windbreak structure is not yet determined. Using CFD simulations, the effects of fence porosity, fence height, and the distance between the adjacent fences were investigated. A wind tunnel experiment was initially conducted and data gathered were used to develop the CFD models. From the experiments and CFD simulations, the overall percentage difference of the measured velocities was 7.20% which is generally acceptable to establishing the reliability of the CFD models. The reduction effect on wind velocity was measured in between the adjacent fences up to a height of 0.6 m from the ground surface. In terms of porosity ( = 0, 0.2, 0.4, 0.6), 0.2 was found to be the optimum value. Conversely, the effect of fence height (0.6, 0.8 and 1.0 m) showed no significant difference; therefore, 0.6 m height is recommended. In addition, the reduction effect of distance between the adjacent fences (2, 4 and 6 m) on wind velocity having a 0.2 porosity has decreased to about 75% regardless of the distance. In the case of the reclaimed land in Saemangeum, a decrease of 75% can prevent the generation and diffusion of dusts. However, the source of dusts is very large. Therefore, constructing an array of windbreak with 6 m distance between them is deemed necessary.     

Continuous measurement of peroxyacetyl nitrate (PAN) in suburban and remote areas of western China

Knowledge on atmospheric abundance of peroxyacetyl nitrate (PAN) is important in assessing the severity of photochemical pollution, and for understanding chemical transformation of reactive odd nitrogen and its impact on the budget of tropospheric ozone (O₃). In summer 2006, continuous measurements of PAN were made using an automatic GC–ECD analyzer with an on-line calibrator at a suburban site of Lanzhou (LZ) and a remote site of Mt. Waliguan (WLG) in western China, with concurrent measurements of O₃, total reactive nitrogen (NO_y) and carbon monoxide (CO). At LZ, several photochemical episodes were observed during the study, and the average mixing ratio of PAN (plus or minus standard deviation) was 0.76 (±0.89) ppbv with the maximum value of 9.13 ppbv, compared to an average value of 0.44 (±0.16) ppbv at remote WLG. The PAN mixing ratios in LZ exhibited strong diurnal variations with a maximum at noon, while enhanced concentrations of PAN were observed in the evening and a minimum in the afternoon at WLG. The daily O₃ and PAN concentration maxima showed a strong correlation (r² = 0.91) in LZ, with a regression slope (PAN/O₃) of 0.091 ppbv ppbv^?1. At WLG, six well-identified pollution plumes (lasting 2–8 h) were observed with elevated concentrations of PAN (and other trace gases), and analysis of backward particle release simulation shows that the high-PAN events at WLG were mostly associated with the transport of air masses that had passed over LZ.     

A validated 2-D diffusion–advection model for prediction of drift from ground boom sprayers

Correct field drift prediction is a key element in environmental risk assessment of spraying applications. A reduced order drift prediction model based on the diffusion–advection equation is presented. It allows fast assessment of the drift potential of specific ground boom applications under specific environmental wind conditions that obey the logarithmic wind profile. The model was calibrated based on simulations with a validated Computational Fluid Dynamics (CFD) model. Validation of both models against 38 carefully conducted field experiments is successfully performed for distances up to 20 m from the field edge, for spraying on flat pasture land. The reduced order model succeeded in correct drift predictions for different nozzle types, wind velocities, boom heights and spray pressures. It used 4 parameters representing the physical aspects of the drift cloud; the height of the cloud at the field edge, the mass flux crossing the field edge, the settling velocity of the droplets and the turbulence. For the parameter set and range considered, it is demonstrated for the first time that the effect of the droplet diameter distribution of the different nozzle types on the amount of deposition spray drift can be evaluated by a single parameter, i.e., the volume fraction of droplets with a diameter smaller than 191 μm. The reduced order model can be solved more than 4 orders of magnitude faster than the comprehensive CFD model.     

Spatiotemporal modelling of ozone distribution in the State of California

This paper is concerned with the spatiotemporal mapping of monthly 8-h average ozone (O₃) concentrations over California during a 15-years period. The basic methodology of our analysis is based on the spatiotemporal random field (S/TRF) theory. We use a S/TRF decomposition model with a dominant seasonal O₃ component that may change significantly from site to site. O₃ seasonal patterns are estimated and separated from stochastic fluctuations. By means of Bayesian Maximum Entropy (BME) analysis, physically meaningful and sufficiently detailed space–time maps of the seasonal O₃ patterns are generated across space and time. During the summer and winter months the seasonal O₃ concentration maps exhibit clear and progressively changing geographical patterns over time, suggesting the existence of relationships in accordance with the typical physiographic and climatologic features of California. BME mapping accuracy can be superior to that of other techniques commonly used by EPA; its framework can rigorously assimilate useful data sources that were previously unaccounted for; the generated maps offer valuable assessments of the spatiotemporal O₃ patterns that can be helpful in the identification of physical mechanisms and their interrelations, the design of human exposure and population health models, and in risk assessment. As they focus on the seasonal patterns, the maps are not contingent on short-time and locally prevalent weather conditions, which are of no interest in a global and non-forecasting framework. Moreover, the maps offer valuable insight about the space–time O₃ concentration patterns and are, thus, helpful for disentangling the influence of explanatory factors or even for identifying some influential ones that could have been otherwise overlooked.     

Investigations of an intense aerosol loading during 2007 cyclone SIDR – A study using satellite data and ground measurements over Indian region

Tropical cyclones are prominent weather systems characterized by high atmospheric pressure gradients and wind speeds. Intense tropical cyclones occur in India during the pre-monsoon (spring), early monsoon (early summer), or post-monsoon (fall) periods. Originating in both the Bay of Bengal (BoB) and the Arabian Sea (AS), these tropical cyclones often attain velocities of more than 100 km h^?1 and are notorious for causing intense rain and storm surge as they cross the Indian coast. In this study, we examine the changes in the aerosol properties associated with an intense tropical cyclone “SIDR”, that occurred during 11–16 November 2007 over BoB. This cyclone, accompanied with very strong surface winds reaching 223 km h^?1, caused extensive damage over Bangladesh. Ground-based measurements of Aerosol Optical Depth (AOD) in the neighboring urban environment of Hyderabad, India, showed significant variations due to changes in wind velocity and direction associated with the cyclone passage. The Terra-MODIS and AVHRR satellite images showed prevalence of dust particles mixed with emissions from anthropogenic sources and biomass-burning AS, while the aerosol loading over BoB was significantly lower. The positive values of Aerosol index (AI) obtained from the Ozone Monitoring Instrument (OMI) suggested the presence of an elevated aerosol layer over the West coast of India, AS and Thar Desert during and after the cyclone episode. Meteorological parameters from the MM5 mesoscale model were used to study the variations in winds associated with the cyclonic activity. Particulate matter loading over the region during the cyclone period increased by ～45% with an accompanying decrease in columnar aerosol optical depth. The variations in Angstrom parameters suggested coarse-mode particle loading due to dust aerosols as observed in satellite data.     

Heterogeneous uptake of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) onto mineral dust aerosol under variable RH conditions

We have carried out kinetic studies to characterize the heterogeneous decay of octamethylcyclotetrasiloxane (D₄) and decamethylcyclopentasiloxane (D₅) in the presence of representative mineral dust aerosol in order to obtain a better understanding of the atmospheric fate of these siloxanes. The heterogeneous chemistry of D₄ and D₅ with various mineral dusts was studied in an environmental aerosol reaction chamber using FTIR absorption spectroscopy to monitor the reaction. The apparent heterogeneous uptake coefficient, γ_app, for D₄ and D₅ with various mineral dusts was measured under dry conditions and as a function of relative humidity (RH). In addition, the effect of initial D₄ and D₅ concentration on the rate and yield of the reaction was examined. The uptake coefficient, γ_app, for D₄ and D₅ was similar for the most reactive aerosols tested, with kaolinite ≈hematite > silica. Limited uptake onto carbon black and calcite surfaces was observed for either siloxane. Reaction with hematite and kaolinite resulted in multilayer coverages, suggesting extensive polymerization of D₄ and D₅ on the aerosol surface.     

Effects of post-sampling conditions on ambient carbon aerosol filter measurements

Ambient carbonaceous material collected on quartz filters is prone to measurement artifacts due to material gained or lost during post-sampling field latency, shipping, and storage. In seventeen sampling events over a one year period, ambient PM_2.5 aerosols were collected on quartz filters (without denuders) and subjected to various filter treatments to assess the potential for and extent of artifacts. The filter treatments simulated post-sampling environments that filters may be exposed to and included: storage at 40 °C for up to 96 h, storage at ?16 °C for 48 h, and storage at room temperature (～21 °C) for 48 h. Carbon mass on the filters was measured using a thermal-optical method. The total carbon (TC), total organic carbon (TOC) and total elemental carbon (TEC) as well as carbon thermal fraction masses were obtained. Statistical analyses were performed to identify significant differences in carbon fraction concentrations between filters analyzed immediately after sampling and after being subjected to treatment.TOC and TC concentrations decreased by on average 15 ± 5% and 10 ± 4%, respectively, for filters maintained at 40 °C for 96 h but did not change for filters stored at room temperature or frozen for 48 h. TEC did not change for any of the filter treatments. The mass concentration for the organic carbon thermal fraction that evolves at the lowest temperature step (OC1) decreased with increasing storage time at 40 °C with average losses of 70 ± 7% after 96 h. Therefore, OC1 is not a stable measurement due to post-sampling conditions that may be encountered. This work demonstrates that TOC and TC can have substantial measurement artifacts on filters subjected to field latency and other non-temperature controlled post-sampling handling, compared to the carbon loadings on the filter at the end of the sampling period.