54
K. M. G. Mostofa et al.
newly flooded terrestrial vegetation, and leaching of organic matter from floodplain soils. In Latin American Rivers, the major sources of DOC are the dumping
of untreated urban sewage into the rivers, the leaching of DOM from humid evergreen and deciduous forests, floodplains of ox-bows and ponds, seasonally humid
savannas and shrublands, as well as swamps. The sources of DOC in European
Rivers may be natural such as wetlands, swamps and peat-land or anthropogenic
such as industrial activities and sewerage. The major sources in North America
that account for the high DOC levels are natural (wetlands, swamps, marshlands,
ground water of mountainous areas covered by riparian vegetation ecosystems)
and anthropogenic (agricultural, sewerage and industrial effluents).
In groundwater, DOC concentrations are 16–424 μM C in Asia, 183–842 μM
C in Australia, 42–15333 μM C in Europe, 8–8333 μM C in North America,
100–3000 in Brazil, 1108 ± 217–14167 ± 6333 μM C in Botswana, and finally
167–7500 μM C in soil solution in North America and Europe (Table 2) (Thurman
1985a; Mostofa et al. 2007a, Mostofa KMG et al., unpublished data; Buckau et al.
2000; Bertilsson et al. 1999; McIntyre et al. 2005; Mladenov et al. 2008; Meier
et al. 2004; Gielen et al. 2011; Crandall et al. 1999; Schwede-Thomas et al. 2005;
Pabich et al. 2001; Michalzik et al. 2001; Anawar et al. 2002; Richey et al. 2002;
Bradley et al. 2007). The results of the available studies show that DOC concentrations in groundwater are significantly higher in Europe, North America, South
America, and African regions than in Asia. High ground-water DOC concentrations are directly related to the high DOC concentrations in surface waters and
high infiltration rates (Mladenov et al. 2007).
In rainwater, DOC concentrations are substantially varied among different countries, such as 25–3675 μM C in China, 217 μM C in Brazil, 4–1908 μM C in USA,
28–1078 in Europe, 161 μM C in a continental location, and 23 μM C in a marine
location (Table 2) (Likens et al. 1983; Guggenberger and Zech 1993; Sakugawa
et al. 1993; Willey et al. 2000; Ciglasch et al. 2004; Avery et al. 2006; Kieber
et al. 2006; Santos et al. 2009a, b; Southwell et al. 2010; Miller et al. 2008;
Mostofa KMG et al., unpublished data; Xu et al. 2008; Pan et al. 2010). Rainwater
DOC concentrations are significantly high in China and Europe, but relatively low
in USA, and lower in marine locations than in continental ones. These results suggest that DOC concentrations in rainwater are mostly affected by the atmospheric
organic contaminants, which generally derive from the surrounding environments.
DOM Contents in Lakes, Wetland and Swamps
DOC concentrations are significantly variable in lakes situated among different continents: 80–4133 μM C in Asia (Table 2) (Yoshioka et al. 2002a, 2007; Fu
et al. 2010; Mostofa et al. 2005a, Mostofa KMG et al., unpublished data;
Hayakawa et al. 2003, 2004; Sugiyama et al. 2004; Ishikawa et al. 2006; Rae et al.
2001); approximately 21–710 μM C in Latin America (Morris et al. 1995; Farjalla
et al. 2006); approximately 59–3750 μM C in Europe (Bertilsson and Tranvik
2000; Lu et al. 2007; Worrall et al. 2004a; Evans et al. 2006; Monteith and Evans
2005; Guéguen et al. 2002; Larsen et al. 2011); and approximately 70–27500 μM
K. M. G. Mostofa et al.
newly flooded terrestrial vegetation, and leaching of organic matter from floodplain soils. In Latin American Rivers, the major sources of DOC are the dumping
of untreated urban sewage into the rivers, the leaching of DOM from humid evergreen and deciduous forests, floodplains of ox-bows and ponds, seasonally humid
savannas and shrublands, as well as swamps. The sources of DOC in European
Rivers may be natural such as wetlands, swamps and peat-land or anthropogenic
such as industrial activities and sewerage. The major sources in North America
that account for the high DOC levels are natural (wetlands, swamps, marshlands,
ground water of mountainous areas covered by riparian vegetation ecosystems)
and anthropogenic (agricultural, sewerage and industrial effluents).
In groundwater, DOC concentrations are 16–424 μM C in Asia, 183–842 μM
C in Australia, 42–15333 μM C in Europe, 8–8333 μM C in North America,
100–3000 in Brazil, 1108 ± 217–14167 ± 6333 μM C in Botswana, and finally
167–7500 μM C in soil solution in North America and Europe (Table 2) (Thurman
1985a; Mostofa et al. 2007a, Mostofa KMG et al., unpublished data; Buckau et al.
2000; Bertilsson et al. 1999; McIntyre et al. 2005; Mladenov et al. 2008; Meier
et al. 2004; Gielen et al. 2011; Crandall et al. 1999; Schwede-Thomas et al. 2005;
Pabich et al. 2001; Michalzik et al. 2001; Anawar et al. 2002; Richey et al. 2002;
Bradley et al. 2007). The results of the available studies show that DOC concentrations in groundwater are significantly higher in Europe, North America, South
America, and African regions than in Asia. High ground-water DOC concentrations are directly related to the high DOC concentrations in surface waters and
high infiltration rates (Mladenov et al. 2007).
In rainwater, DOC concentrations are substantially varied among different countries, such as 25–3675 μM C in China, 217 μM C in Brazil, 4–1908 μM C in USA,
28–1078 in Europe, 161 μM C in a continental location, and 23 μM C in a marine
location (Table 2) (Likens et al. 1983; Guggenberger and Zech 1993; Sakugawa
et al. 1993; Willey et al. 2000; Ciglasch et al. 2004; Avery et al. 2006; Kieber
et al. 2006; Santos et al. 2009a, b; Southwell et al. 2010; Miller et al. 2008;
Mostofa KMG et al., unpublished data; Xu et al. 2008; Pan et al. 2010). Rainwater
DOC concentrations are significantly high in China and Europe, but relatively low
in USA, and lower in marine locations than in continental ones. These results suggest that DOC concentrations in rainwater are mostly affected by the atmospheric
organic contaminants, which generally derive from the surrounding environments.
DOM Contents in Lakes, Wetland and Swamps
DOC concentrations are significantly variable in lakes situated among different continents: 80–4133 μM C in Asia (Table 2) (Yoshioka et al. 2002a, 2007; Fu
et al. 2010; Mostofa et al. 2005a, Mostofa KMG et al., unpublished data;
Hayakawa et al. 2003, 2004; Sugiyama et al. 2004; Ishikawa et al. 2006; Rae et al.
2001); approximately 21–710 μM C in Latin America (Morris et al. 1995; Farjalla
et al. 2006); approximately 59–3750 μM C in Europe (Bertilsson and Tranvik
2000; Lu et al. 2007; Worrall et al. 2004a; Evans et al. 2006; Monteith and Evans
2005; Guéguen et al. 2002; Larsen et al. 2011); and approximately 70–27500 μM