The current study aims at estimating the dietary intake of PBDEs in the Netherlands and evaluating the resultant risk. Dietary intake was estimated using results of PBDE analyses in Dutch food products from 2003/2004 and consumption data of the third Dutch National Food Consumption Survey (1997/1998). Assuming that non-detects represent levels of half the detection limit, the median long-term intake of the Dutch population of the sum of five major PBDEs (namely PBDEs 47, 99, 100, 153+154) is 0.79 ng/kg body weight bw/day (P97.5: 1.62 ng/kg bw/day). When non-detects are considered as zeros the values are 0.53 (median) and 1.34 (P97.5) ng/kg bw/day. Environmental concentrations of PBDEs in Europe are expected to decline in the near future because of the ban on penta- and octaBDE technical products. However, it will take at least a decade before this will result in lower PBDE concentrations in food products. Hence, a regular monitoring program for PBDEs is recommended. A risk evaluation at the most sensitive endpoints of BDE 99 carried out in this paper indicates that, although the long-term exposure to BDE 99 is well below the human exposure threshold level for neurodevelopmental toxicity, it may be close to that for reproductive toxicity.

Abstract. The radiative scattering by clouds leads to errors in the retrieval of column densities and concentration profiles of atmospheric trace gas species from satellites. Moreover, the presence of clouds changes the UV actinic flux and the photo-dissociation rates of various species significantly. The Global Ozone Monitoring Experiment (GOME) instrument on the ERS-2 satellite, principally designed to retrieve trace gases in the atmosphere, is also capable of detecting clouds. Four cloud fraction retrieval methods for GOME data that have been developed are discussed in this paper (the Initial Cloud Fitting Algorithm, the PMD Cloud Recognition Algorithm, the Optical Cloud Recognition Algorithm (an in-house version and the official implementation) and the Fast Retrieval Scheme for Clouds from the Oxygen A-band). Their results of cloud fraction retrieval are compared to each-other and also to synoptic surface observations. It is shown that all studied retrieval methods calculate an effective cloud fraction that is related to a cloud with a high optical thickness. Generally, we found ICFA to produce the lowest cloud fractions, followed by our in-house OCRA implementation, FRESCO, PC2K and finally the official OCRA implementation along four processed tracks (+2%, +10%, +15% and +25% compared to ICFA respectively). Synoptical surface observations gave the highest absolute cloud fraction when compared with individual PMD sub-pixels of roughly the same size.

Abstract. The radiative scattering by clouds leads to errors in the retrieval of column densities and concentration profiles of atmospheric trace gas species from satellites. Moreover, the presence of clouds changes the UV actinic flux and the photo-dissociation rates of various species significantly. The Global Ozone Monitoring Experiment (GOME) instrument on the ERS-2 satellite, principally designed to retrieve trace gases in the atmosphere is also capable of detecting clouds. Four cloud fraction retrieval methods for GOME data that have been developed are discussed in this paper (the Initial Cloud Fitting Algorithm, the PMD Cloud Retrieval Algorithm, the Optical Cloud Recognition Algorithm and the Fast Retrieval Scheme for Cloud Observables). Their results of cloud fraction retrieval are compared to each-other and also to synoptic surface observations. It is shown that all studied retrieval methods calculate an effective cloud fraction that is related to a cloud with a high optical thickness. Generally, we found ICFA to produce the lowest cloud fractions, followed by OCRA, then FRESCO and PC2K along four processed tracks (+2%, +10% and +15% compared to ICFA respectively). Synoptical surface observations gave the highest absolute cloud fraction when compared with individual PMD sub-pixels of roughly the same size.

[1] Clouds are a large error source in the retrieval of tropospheric column densities and concentration profiles of trace gas species from satellites and in the calculation of their photodissociation rates. The Global Ozone Monitoring Experiment instrument on the ERS-2 satellite is capable of detecting clouds, and a number of methods have been developed to retrieve their properties. In our previous study it was shown that these cloud retrieval methods calculate an effective cloud fraction that is related to a cloud with a high optical thickness. Furthermore, the retrieved solutions are nonunique, as different combinations of optical thickness, cloud fraction, and cloud top height can give the same albedo at the top of the atmosphere. The impact of the scaling of various cloud solutions to an effective cloud fraction on the vertical photodissociation profiles of ozone (O 3 ) and nitrogen dioxide (NO 2 ) and on the tropospheric column production of the hydroxyl radical (OH) is studied in this paper, using the tropospheric ultraviolet-visible radiative transfer model. Results show that for selected cloud solutions, local differences in the vertical OH primary production profile can be from +7% for small solar zenith angles to À14% for large angles with a cloud between 2 and 3 km. Column-integrated OH primary production differences can be between +9% and À7% depending on the solar zenith angle when a cloud is located between 2 and 3 km but can increase to +23% and À81% for a cloud at higher altitudes. NO 2 photodissociation was shown to be locally more influenced by the scaling of clouds to an effective cloud fraction, but for the tropospheric column difference this influence is less prominent.

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The trace gas observations from satellites can be the powerfull tools for the validation of tropospheric models, because of their global coverage in space and time. For verification of tropospheric models GOME spectrometer [1], which will be launched on ERS-2 satellite in 1994 should be able to measure the changes in tropospheric column densities of species occuring in the atmosphere. The trace species for which the tropospheric columns could be observed by GOME spectrometer are: ozone O3, nitrogen dioxide NO2, sulfur dioxide SO2 and formaldehyde HCHO. In this study we tried to answer the question: what is the sensitivity of GOME spectrometer for the measurement of changes in the tropospheric column densities of these species. We applied only forward modeling to see how large should be the changes in tropospheric column densities of these species to cause the change of GOME signal which will exceed the noise level of the instrument. Though, it is the lowest boarder of detectibility, we tried to find out, and the error caused by the retrieval procedure must be added to our results.