Distribution of iron and manganese in the Seine river estuary: approach with experimental laboratory mixing

The physico-chemical behaviour of iron and manganese has been observed during many surveys covering various hydrodynamic conditions in the Seine river estuary system. The results obtained confirm the non-conservative behaviour of these two metals. Generally, dissolved iron exhibits non-conservative removal and shows a rapid decrease in low salinity; it is moved from fresh waters with high concentrations to saline waters with very low concentrations. This can be attributed to the flocculation processes as confirmed by laboratory experiments. Dissolved manganese versus salinity curves exhibit a peak concentration in the low salinity zone. Laboratory mixing experiments have been undertaken comparing iron and manganese adsorption/desorption from suspended material versus salinity, using a series of water samples collected in the up-river and marine regions in order to assess the importance of particulate material and salinity on iron and manganese distributions. The salinity was controlled by varying the marine to fresh water ratio. The reaction kinetics aspect is developed in more detail for manganese in the last series of remobilization experiments starting from a stock of suspended particles collected in the upstream river site (Caudebec) in mixtures of waters, according to time and salinity. This study has allowed us to show that iron and manganese behaviour in the Seine estuary is strongly influenced: (i) by the high turbidity zone and by the presence of calcium carbonate which could stabilise the Mn(II) form; and (ii) by the increase of salinity, calcium, magnesium and suspended matter concentrations and by complex formation.     

Indoor NO2 pollution and personal exposure to NO2 in two areas with different outdoor NO2 pollution

Indoor NO₂ concentrations were measured in the kitchen, the living room and bedroom of 612 houses in two different areas in the Netherlands. In a group of housewives living in these homes, personal exposure to NO₂ was measured. NO₂ concentrations indoors were dependent on the presence or absence of (un)vented gas appliances. Personal NO₂ exposure was only different between the two areas in the group with the lowest indoor concentrations. In this study, it was determined that gas appliances inside the house are the most important factor with respect to NO₂ exposure and that outside NO₂ concentration played a secondary role, except in situations where gas appliances were absent.     

Assessment of chemical process hazards in early design stages

A new method called SREST-layer-assessment method with automated software tool is presented that in a hierarchical approach reveals the degree of non-ideality of chemical processes with regard to SHE (safety, health and environment) aspects at different layers: the properties of the chemical substances involved (substance assessment layer (SAL)), possible interactions between the substances (reactivity assessment layer (RAL)), possible hazard scenarios resulting from the combination of substances and operating conditions in the various equipments involved (equipment assessment layer (EAL)), and the safety technologies that are required to run a process safely and in accordance with legal regulations (safety-technology assessment layer (STAL)). In RAL, EAL and STAL the main focus is put on process safety. A case study is used to show the principles of the method. It is demonstrated how the method can be used as a systematic tool to support chemical engineers and chemists in evaluating chemical process safety in early process development stages.     

Regional electricity transmission planning and SEA: The case of the electricity company ScottishPower

Since 21 July 2004, formal strategic environmental assessment (SEA) requirements are in place for certain plans and programmes in European Union member states. Many public plans and programmes have been identified to fall under these requirements, and there has been a range of research activities particularly in land use and transport planning. However, the way in which SEA is to be applied in the private sector has remained largely unclear. Furthermore, to date there has been comparatively little reported private sector experience and the concrete benefits that SEA may deliver to private companies have not yet been discussed to any large extent. In order to address this shortcoming, the paper looks at SEA application in electricity transmission planning, taking the specific case of the privatized company ScottishPower as an example. Based on the evidence obtained, it is suggested that a structured SEA process can strengthen the environmental component and improve private sector decision-making processes. Corporate governance can be improved, if SEA is applied in a tiered system, addressing different issues and tasks at distinct stages in a clearly defined decision making hierarchy.