{'fraction_non_alphanumeric': 0.020923520923520924, 'fraction_numerical': 0.03607503607503607, 'mean_word_length': 4.952789699570816, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Polyaromatic hydrocarbons (PAHs) in the Barents Sea sediments: small changes over the recent 10 years

Abstract In order to reveal possible multi-year dynamics in sediment PAH concentrations and composition, data sets from the years 2001–2005 have been compared with data sets obtained during the years 1992–1998. K-means-clustering of the 2001–2005 data sets suggests dividing the sampling area into five geographical areas based upon levels and compositions of PAHs. The five areas are Svalbard offshore, Bear Island Trough, SW Barents Sea, NE Barents Sea and SE Barents Sea. Comparison of the two groups of data sets revealed no significant differences between geometric means of PAH concentrations and PAH ratios for sediments from Svalbard offshore, Bear Island Trough and NE Barents Sea. These results are supported by down core analyses of PAH distributions. In the SW Barents Sea area, mean total PAH concentrations found in the 2000s and 1990s did not differ significantly. However, the sum of two- to three-ring PAH compounds and Fossil Fuel Pollution Index in samples of 2000s were significantly higher than in data sets from the 1990s. In the SE Barents Sea area, both total concentrations of pyrogenic PAHs and PAH ratios in the data sets from the 2000s were significantly higher than the 1990s data sets, which suggest higher input of combustion and/or anthropogenic PAHs.