9
Dissolved Organic Matter in Natural Waters
low (3 years) in temperate forest soils (central Massachusetts, USA), and highest (16 years) in boreal forest soils (Manitoba, Canada) (Trumbore 2000).
Experimental studies using δ 13 C or 14 C to track sources and turnover of DOC
indicate that DOM, which is transported over decimetres or metres down into subsoil, mainly represents highly altered residues of organic matter processing (Schiff
et al. 1997; Flessa et al. 2000; Hagedorn et al. 2004; Fröberg et al. 2007). Note
that allochthonous DOM is mostly derived, in zero to a few decimeter depth from
the decomposition of plant material by microbial processes in soils and shallow
groundwater (Uchida et al. 1998, 2000; Fröberg et al. 2007; IPCC 1996; Buckau et
al. 2000).
DOC leached from soil is partly retained in the vadose zone before reaching aquifers (Siemens and Kaupenjohann 2003; Mikutta et al. 2007; Kalbitz
and Kaiser 2008; Scheel et al. 2008). For the range of groundwater recharge of
95–652 mm yr −1 , it is shown that a constant flux of DOC from soil into surface
waters often takes place (Kindler et al. 2011). Therefore, allochthonous DOM is
partly discharged through hydrological processes directly into streams or riverbeds
or surrounding water bodies, which ultimately flux to lake or oceanic environments as final water reservoir.
3.2 Origin of Autochthonous DOM in Natural Waters
Production of autochthonous DOM is generally observed at the epilimnion (upper
water layers) compared to the hypolimnion (deeper layers) during the summer stratification period, particularly in lakes and oceans. A rough estimation by
comparing the upper with the deeper layers demonstrates that the contribution of
autochthonous DOM is largely varied in lakes and oceans: it reaches 0–55 % in
Lake Hongfeng (181–250 μM C at 0–6 m and 161–223 μM C at 22–25 m depth,
respectively, during March–September), 3–47 % in Lake Baihua (183–264 μM C
at 0–3 m and 157–206 μM C at 14–15 m during March-September), 6–35 % in
Lake Baikal (93–142 μM C at 0–100 m and 88–105 μM C at 600–720 m during
August–September in 1995, 1998, 1999), 3–82 % in Lake Biwa (93–183 μM C
at 2.5–10 m and 78–101 μM C at 70 m during May–September in 1999–2002),
21–49 % in Lake Ashino in Japan (99–111 μM C at 0–10 m and 74–84 μM C at
30–38 m in September 1997), 81–102 % in Lake Ikeda in Japan (101–112 μM C
at 0–10 m and 55–56 μM C at 200–233 m for site I1; at 41 m for site I2 in
October 1997), 52 % in Lake Suwa in Japan (216 μM C at 0 m in September and
142 μM C at 0 m in December 1997), 61–81 % in Lake Inawashiro in Japan (42–
47 μM C at 0–10 m and 26 μM C at 70 m), 13–29 % in Lake Fuxian (123–135
μM C at 0–10 m and 95–105 μM C at 50–140 m in June 2001), 19 % in Lake
Hovsgol (95 μM C at 0 m and 80 μM C at 50–200 m in July 1999), 0–88 % in
Lake Kinneret (270–485 μM C at 0–10 m and 258–368 μM C at 38 m during the
summer period in 2004), 17–41 % in Lake Peter (data not shown), 11–29 % (biological production) in Lake Bret, 0–104 % in Middle Atlantic Bight (82–98 μM C
Dissolved Organic Matter in Natural Waters
low (3 years) in temperate forest soils (central Massachusetts, USA), and highest (16 years) in boreal forest soils (Manitoba, Canada) (Trumbore 2000).
Experimental studies using δ 13 C or 14 C to track sources and turnover of DOC
indicate that DOM, which is transported over decimetres or metres down into subsoil, mainly represents highly altered residues of organic matter processing (Schiff
et al. 1997; Flessa et al. 2000; Hagedorn et al. 2004; Fröberg et al. 2007). Note
that allochthonous DOM is mostly derived, in zero to a few decimeter depth from
the decomposition of plant material by microbial processes in soils and shallow
groundwater (Uchida et al. 1998, 2000; Fröberg et al. 2007; IPCC 1996; Buckau et
al. 2000).
DOC leached from soil is partly retained in the vadose zone before reaching aquifers (Siemens and Kaupenjohann 2003; Mikutta et al. 2007; Kalbitz
and Kaiser 2008; Scheel et al. 2008). For the range of groundwater recharge of
95–652 mm yr −1 , it is shown that a constant flux of DOC from soil into surface
waters often takes place (Kindler et al. 2011). Therefore, allochthonous DOM is
partly discharged through hydrological processes directly into streams or riverbeds
or surrounding water bodies, which ultimately flux to lake or oceanic environments as final water reservoir.
3.2 Origin of Autochthonous DOM in Natural Waters
Production of autochthonous DOM is generally observed at the epilimnion (upper
water layers) compared to the hypolimnion (deeper layers) during the summer stratification period, particularly in lakes and oceans. A rough estimation by
comparing the upper with the deeper layers demonstrates that the contribution of
autochthonous DOM is largely varied in lakes and oceans: it reaches 0–55 % in
Lake Hongfeng (181–250 μM C at 0–6 m and 161–223 μM C at 22–25 m depth,
respectively, during March–September), 3–47 % in Lake Baihua (183–264 μM C
at 0–3 m and 157–206 μM C at 14–15 m during March-September), 6–35 % in
Lake Baikal (93–142 μM C at 0–100 m and 88–105 μM C at 600–720 m during
August–September in 1995, 1998, 1999), 3–82 % in Lake Biwa (93–183 μM C
at 2.5–10 m and 78–101 μM C at 70 m during May–September in 1999–2002),
21–49 % in Lake Ashino in Japan (99–111 μM C at 0–10 m and 74–84 μM C at
30–38 m in September 1997), 81–102 % in Lake Ikeda in Japan (101–112 μM C
at 0–10 m and 55–56 μM C at 200–233 m for site I1; at 41 m for site I2 in
October 1997), 52 % in Lake Suwa in Japan (216 μM C at 0 m in September and
142 μM C at 0 m in December 1997), 61–81 % in Lake Inawashiro in Japan (42–
47 μM C at 0–10 m and 26 μM C at 70 m), 13–29 % in Lake Fuxian (123–135
μM C at 0–10 m and 95–105 μM C at 50–140 m in June 2001), 19 % in Lake
Hovsgol (95 μM C at 0 m and 80 μM C at 50–200 m in July 1999), 0–88 % in
Lake Kinneret (270–485 μM C at 0–10 m and 258–368 μM C at 38 m during the
summer period in 2004), 17–41 % in Lake Peter (data not shown), 11–29 % (biological production) in Lake Bret, 0–104 % in Middle Atlantic Bight (82–98 μM C