Chloroform - Concentration gradients in soil air and atmospheric air, and emission fluxes from soil

Since we demonstrated the natural formation of chloroform in soil, the question arose to which extent this contributes to the chloroform present in the atmosphere. Concentration gradients in soil air and atmospheric air of different forests were measured. Chloroform concentration gradients indicating emission occur in forest soils and the...

Bioremediation of chlorinated solvents ; two interesting cases in difficult soil conditions

Hydrogen as indicator for redox conditions and dechlorination

The use of intrinsic degradation processes (natural attenuation) is becoming the basis for the restoration of many contaminated sites. Within this context, measuring concentrations of hydrogen in groundwater is important in two ways. Firstly, the hydrogen concentration can be used to characterize redox conditions. Secondly, hydrogen may be an...

Time and land-use as interpretation keys for the evaluation of different remedial scenarios

In the regulated community there is often concern as to whether mass removal at a contaminated site actually reduces risk, or whether the small risk reductions achieved warrant the large costs incurred. Decision-makers have to select feasible solutions based on the required risk reduction, costs of the remediation and environmental impact. Thus,...

Innovative reactive barrier technologies for regional contaminated groundwater

At many industrial sites inadequate waste disposal, leakages and war damages have led to severe groundwater contamination on a regional scale. Standard hydraulic groundwater remediation methods, such as pump-and-treat, in most cases do not lead to satisfactory results, due to the persistence of organic contaminants and the resulting very long...

Controlling persistent organic pollutants-what next?

Within the context of current international initiatives on the control of persistent organic pollutants (POPs), an overview is given of the scientific knowledge relating to POP sources, emissions, transport, fate and effects. At the regional scale, improvements in mass balance models for well-characterised POPs are resulting in an ability to...

Intrinsic and enhanced bioremediation in aquifers contaminated with chlorinated and aromatic hydrocarbons in The Netherlands

The feasibility of intrinsic and enhanced bioremediation approaches for 16 contaminated sites in the Netherlands are discussed. At at least five out of 10 chlorinated solvent sites, natural attenuation can be used as one of the tools to prevent further dispersion of the plume. At two sites stimulation of the intrinsic dechlorination processes in...

Inhalation exposure to 1,3-dichloropropene in the Dutch flower-bulb culture. Part I. Environmental monitoring

Respiratory occupational exposure to the Z- and E-isomers of 1,3-dichloropropene (DCP) of twelve commercial applicators was assessed. The time-weighted average (TWA) concentrations of DCP ranged from 1.9 to 18.9 mg/m3. On 30% of the observed working days the Dutch occupational exposure limit of 5 mg/m3 was exceeded. Short-term exposure levels...

Relevance of parameters related to fertility and reproduction in toxicity testing

Toxicity data of 37 compounds tested in both a subchronic study and one or more studies focused on reproduction were evaluated to obtain information on the significance of fertility and reproduction parameters in setting no-effect levels (NEL). It appeared that a) the test system aimed at reproduction and development was more sensitive than the...

Survey of the contamination of Dutch coastal water by chlorinated hydrocarbons, including the occurrence of methylthio-pentachlorobenzene and di-(methylthio)tetrachlorobenzene

In 1976 contamination of Dutch coastal waters by organochlorine compounds was assessed by analysing mussels, Mytilus edulis, as an indicator-organism. HCB, dieldrin, endrin, p,p'-DDT, p,p'-TDE and PCB's were detected, and also two new compounds previously unknown in the aquatic fauna. Using gas-liquid chromatography, mass spectrometry and 13C...