Table 4. CH4 and CO2 concentration and flux in estuaries around the world.
Data represent the range (mean).
| Study area | Country | Latitude | Dominant sources and processes | Measurement year | CH4 | CO2 | CH4 | CO2 | References |
|---|---|---|---|---|---|---|---|---|---|
| Concentration range (µM) | Flux range (mmol m−2 d−1) | ||||||||
| Pulicat Lake Estuary | India | 14°N | Lateral inputs | na | 0.09–0.50 (0.24) | 0.05–0.23 | Shalini et al. (2006) | ||
| New River Estuary | USA | 34°N | Lateral inputs | 2016 | −6.6–98.4 | Van Dam, Edson & Tobias (2019) | |||
| Neuse River Estuary | USA | 35°N | Lateral inputs | 2016 | −2.7–98.4 | Van Dam, Edson & Tobias (2019) | |||
| Hugli Estuary | India | 22°N | Lateral inputs | 2014 | (88.8) | Akhand et al. (2016) | |||
| Hooghly Estuary | India | 21°N | Lateral inputs | 1999 | −2.8–84.4 | Mukhopadhyay et al. (2002) | |||
| Betsibika Estuary (D) | Madagascar | 18°S | Lateral inputs | 2005 | 11–62.5 | (9.1) | Ralison et al. (2008) | ||
| Guadalquivir Estuary | Spain | 37°N | Tidal flats | 2017 | (0.05) | (39.2) | (0.12) | (60) | Sierra et al. (2020) |
| Guadiana Estuary | Spain | 37°N | Tidal flats | 2017 | (0.05) | (24.3) | (0.11) | (40) | Sierra et al. (2020) |
| Tinto-Odiel Estuary | Spain | 37°N | Tidal flats | 2017 | (0.04) | (23.7) | (0.07) | (11.7) | Sierra et al. (2020) |
| Matla Estuary | India | 22°N | Tidal flats | 2014 | (6.3) | Akhand et al. (2016) | |||
| Rajang River Estuary (D) | Malaysia | 2°N | Tidal flats | 2016 | (114) | 15.9–68.2 (45.4) | Müller et al. (2019) | ||
| Rajang River Estuary (W) | Malaysia | 2°N | Tidal flats | 2016 | (122) | 15.9–54.5 (40.9) | Müller et al. (2019) | ||
| Lupar River Estuary (D) | Malaysia | 1°N | Tidal flats | 2013 | 0.01–0.04 (0.02) | <0 | Müller et al. (2016) | ||
| Lupar River Estuary (W) | Malaysia | 1°N | Tidal flats | 2013 | 0–0.06 (0.02) | <0 | Müller et al. (2016) | ||
| Saribas River Estuary (D) | Malaysia | 1°N | Tidal flats | 2013 | 0.01–0.06 (0.03) | <0 | Müller et al. (2016) | ||
| Saribas River Estuary (W) | Malaysia | 1°N | Tidal flats | 2013 | 0.01–0.07 (0.02) | <0 | Müller et al. (2016) | ||
| Lupar River Estuary (D) | Malaysia | 1°N | Tidal flats | 2014 | (101) | (312) | Müller et al. (2016) | ||
| Lupar River Estuary (W) | Malaysia | 1°N | Tidal flats | 2014 | (75.6) | Müller et al. (2016) | |||
| Saribas River Estuary (D) | Malaysia | 1°N | Tidal flats | 2014 | (92.0) | (200) | Müller et al. (2016) | ||
| Saribas River Estuary (W) | Malaysia | 1°N | Tidal flats | 2014 | (91.4) | Müller et al. (2016) | |||
| Furo do Meio in Caeté Estuary | Brazil | 1°S | Tidal flats | 2017 | (0.86) | (174) | Call et al. (2018) | ||
| Altamaha Sound | USA | 32°N | Tidal flats | 2004 | (69.3) | Jiang, Cai & Wang (2008) | |||
| Tagus Estuary | Portugal | 38°N | Tidal dynamics | 2007 | 24.5–65.5 | Oliveira et al. (2018) | |||
| Changjiang River Estuary | China | 29°N | Tidal dynamics | 2006 | 0–0.09 (0.10) | (0.06) | Zhang et al. (2008) | ||
| Pearl River Estuary | China | 26°N | Tidal dynamics | 2003 | 0.02–2.98 (2.9) | 28.2–110 | Chen et al. (2008) | ||
| Jiulong River Estuary | China | 25°N | Tidal dynamics | 2018 | 0.06–1.7 | 0.19–18.6 | Li et al. (2021) | ||
| Columbia River Estuary | USA | 46°N | Landuse activity | 2013 | 0.27–0.73 (0.45) | Pfeiffer-Herbert et al. (2019) | |||
| Oregon Estuary | USA | 44°N | Landuse activity | 1982 | 0–1.30 | De Angelis Marie & Lilley Marvin (1987) | |||
| Mekong Delta | Vietnam | 17°N | Landuse activity | 2004 | 0-2.22 | 9.5–167 | 0.04–0.2 | 105–135 | Borges, Abril & Bouillon (2018) |
| Scheldt Estuary | UK | 51°N | Sewage | 1991 | 0.14–189 (21.6) | 17.5–227 (120) | Middelburg et al. (1996) | ||
| Hudson River Estuary | USA | 42°N | Sewage | 1991 | 0.05–0.94 (0.9) | (0.30) | DeAngelis & Scranton (1993) | ||
| Changjiang River Estuary | China | 29°N | Sewage | 2010 | 7.2–86 | 0–230 (61) | Yu et al. (2013) | ||
| Adyar Estuary (W) | India | 13°N | Sewage | 2001 | (23.1) | Purvaja & Ramesh (2001) | |||
| Adyar Estuary (W) | India | 13°N | Sewage | 2004 | 0.03–5.62 | 0.04–11.0 | Nirmal Rajkumar et al. (2008) | ||
| Cochin Estuary (D) | India | 10°N | Sewage | 2005 | 51.6–105 | 65–267 | Gupta et al. (2009) | ||
| Brisbane River Estuary | Australia | 27°S | Sewage | 2012 | 0.08–0.31 | 0.25–2.2 | Sturm et al. (2017) | ||
| Brisbane River Estuary | Australia | 27°S | Sewage | 2012 | 0.03–0.58 (0.5) | 0.02–1.7 | Musenze et al. (2013) | ||
| Godavari River Estuary (D) | India | 19°N | Urbanization | 2009 | 9–1339 | 80–150 | Sarma et al. (2011) | ||
| Terengganu River Estuary (D) | Malaysia | 5°N | Urbanization | 2018 | 1.60–9.6 (4.0) | 75–312 (212) | 1.6–10.1 | 70–350 (233) | This study |
| Terengganu River Estuary (W) | Malaysia | 5°N | Urbanization | 2018 | 1.90–14.7 (5.7) | 9–271 (135) | 2.5–21.1 | −11–391 (179) | This study |
| Caboolture River Estuary | Australia | 27°S | Urbanization | 2012 | (78) | Jeffrey et al. (2018) | |||