The contribution of fossil sources to the organic aerosol in the Netherlands

We measured the radiocarbon (14C) content of organic carbon (OC) samples from two locations in the Netherlands, the urban location of Amsterdam and the coastal location of Petten. PM10 samples were collected in Amsterdam and total suspended particles were collected in Petten using high volume samplers. The 14C/12C fraction in the samples is reported as fraction modern (F14C). It can be used to roughly estimate the contribution of fossil sources to OC, since F14C of fossil fuels is 0, whereas biogenic and wood burning sources are characterized by F14C values close to 1. At the coastal location organic carbon has higher F14C values (0.83 ± 0.04 standard uncertainty) than at the urban location (0.68 ± 0.05). A fraction modern of 0.68 is in the range of F14C values published for OC of other European urban areas (0.68–0.81). The coastal F14C of 0.83 agrees well with measurements at the coastal location of Mace Head, even though in Mace Head measurements were made on particles smaller than 1.5 μm (PM1.5). A F14C of 0.83 is on the lower end of F14C(OC) values estimated for continental background sites in Europe. Fossil sources might be contributing slightly more to organic carbon in the Netherlands than in other European regions. However, a bigger data set is needed to substantiate this finding. On average, fossil fuel combustion is responsible for approximately 40% of the organic carbon in Amsterdam and approximately 20% at the coastal location. At the coastal location, F14C was clearly lower than average when polluted air masses reached the measurement site, whereas in the urban area, air mass history did not have a strong influence on F14C.