An aspiring hydrologist

The deeper the waters are, the more still they run. -Korean Proverb

What is Dissolved Organic Matter (DOM)?

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Dissolved organic matter (DOM) is a mixture of organic molecules in aquatic ecosystems and plays diverse biogeochemical and ecological roles.

DOM from marine and aquatic sources – more enriched in aliphatic structures.

DOM from terrestrial and higher plants – more conjugated and higher aromaticity.

DOM in rivers can be affected by various factors such as:

  • pH
  • Salinity
  • Temperature
  • Diagenetic processes – Photodegradation and biodegradation (mainly in tropical rivers/wetlands).

Written by hana.kirana

May 4, 2011 at 8:12 pm

Isotopic composition of dissolved inorganic carbon in a large polluted river: The Vistula, Poland

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Rivers have been recognized as an important component of the global carbon cycle. Fluvial systems directly link the terrestrial biosphere and the oceans which are the only two significant reservoirs of carbon capable of influencing global carbon cycle on a human time scale. Rivers play a significant role in redistribution of carbon between its atmospheric, terrestrial and oceanic sources and sinks. Terrestrial biosphere and weathering processes transform carbon that occurs as atmospheric CO2, carbonate minerals and fossil organic matter into various organic and inorganic, dissolved and particulate forms of carbon which are subsequently transported to the oceans by rivers. The riverine fluxes of carbon constitute an important but not well quantified component of past and present, global and regional carbon budgets.

River waters are usually super-saturated with CO2 and the rivers themselves can be a significant source of atmospheric CO2.

River systems are active transport agents of carbon to the oceans. Dynamics of the internal riverine carbon cycling is controlled by a complex interplay between inorganic and organic carbon pools coupled by the photosynthesis/respiration cycle. Dissolved inorganic carbon (DIC) after assimilation by primary producers is incorporated into a complex riverine food web involving production and consumption of different forms of particulate (POC) and dissolved organic carbon (DOC). The DIC pool is replenished by respiration and photodissociation of auto- and allochtonous organic matter. In rivers this biochemical cycling is interwined with physical processes such as advective transport, dispersion and retardation of carbon species and with exchange of CO2 between river waters and the atmosphere. A characteristic feature of riverine carbon budgets, both for discrete river reaches and for river systems regarded as a whole, is a significant contribution of exports and imports of carbon. Rivers are open systems linked to terrestrial ecosystems and groundwaters through accompanying floodplain, riparian and hyporheic zones where riverine carbon is processed and redistributed. Anthropogenic influences affect all aspects of riverine carbon cycling. The phosynthesis/respiration cycle is intensified by nutrients and organic carbon dumped to rivers with wastewaters and agricultural runoff. Regulation, channelisation and damming influence basic hydraulic characteristics of rivers like water velocity and mixing properties, and disconnect rivers from the adjacent zones.

Wachniew, P. 2006. Isotopic composition of dissolved inorganic carbon in a large polluted river: The Vistula, Poland. Chemical Geology 233: 293-308.

Written by hana.kirana

August 15, 2008 at 5:05 pm