Allochthonous versus autochthonous naturally occurring organic matter in the Anllons river bed sediments (Spain)

作者：Devesa Rey R^*; Barral M T

来源：Environmental Earth Sciences, 2012, 66(3): 773-782.

DOI：10.1007/s12665-011-1286-3

• Humic and fulvic acids
• organic matter
• Photostability
• A4/A6

Despite of the importance of the aquatic ecosystems as organic matter pools within the global carbon cycle, specific studies in river sediments are still insufficient. This study was carried out in an Atlantic basin where nine sites were selected in the lowest middle stretch of the River. The analyses include total organic carbon, C/N ratios, humus composition (humic, fulvic and humin), A2/A4 and A4/A6 ratios, biologically active organic matter (BAOM), water soluble organic matter (WSOC) and coloured water soluble organic carbon (CWSOC). The results suggested a predominance of allochthonous sources to the organic matter, highly influenced by the land uses together with the river hydrodynamics, namely urban and forest at sites 1, 2 and 9, and agricultural at sites 7 and 8. The 38% of the total organic matter was humic and fulvic acids. The biologically active organic matter, which may act as a proxy of microbial activity, showed a mean value of 0.9% of the total organic matter, showing the lowest values at sites with the highest organic matter total, soluble or coloured. This coloured organic matter represented an average of 3.60% of the total organic matter, and showed the highest visible light absorption at those sites more affected by human activities, close to centres of population (1, 2 and 9). This coloured fraction showed also a high degree of photostability. C/N ratios were less effective to discriminate between allochthonous or autochthonous sources, whereas A4/A6 ratios were effective to estimate variations of autochthonous sources, as it measures the variations of phytopigments of the river bed sediments.

• 出版日期2012-6