eprintid: 10166543 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/16/65/43 datestamp: 2023-03-15 15:16:01 lastmod: 2023-03-15 15:16:01 status_changed: 2023-03-15 15:16:01 type: article metadata_visibility: show sword_depositor: 699 creators_name: Salgado, J creators_name: Duc`, TA creators_name: Nga, DT creators_name: Panizzo, VN creators_name: Bass, AM creators_name: Zheng, Y creators_name: Taylor, S creators_name: Roberts, LR creators_name: Lacey, JH creators_name: Leng, MJ creators_name: McGowan, S title: Urbanization and seasonality strengthens the CO2 capacity of the Red River Delta, Vietnam ispublished: pub divisions: UCL divisions: B03 divisions: C03 divisions: F26 note: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. abstract: Tropical rivers are dynamic CO2 sources. Regional patterns in the partial pressure of CO2 (pCO2) and relationships with other a/biotic factors in densely populated and rapidly developing river delta regions of Southeast Asia are still poorly constrained. Over one year, at 21 sites across the river system in the Red River Delta (RRD), Vietnam, we calculated pCO2 levels from temperature, pH, and total alkalinity and inter-linkages between pCO2 and phytoplankton, water chemistry and seasonality were then assessed. The smaller, more urbanized, and polluted Day River had an annual median pCO2 of 5000 ± 3300 µatm and the larger Red River of 2675 ± 2271 µatm. pCO2 was 1.6 and 3.2 times higher during the dry season in the Day and Red rivers respectively than the rainy season. Elevated pCO2 levels in the Day River during the dry season were also 2.4-fold higher than the median value (2811 ± 3577 µatm) of calculated and direct pCO2 measurements in >20 sub/tropical rivers. By further categorizing the river data into Hanoi City vs. other less urban-populated provinces, we found significantly higher nutrients, organic matter content, and riverine cyanobacteria during the dry season in the Day River across Hanoi City. Forward selection also identified riverine cyanobacteria and river discharge as the main predictors explaining pCO2 variation in the RRD. After accounting for the shared effects (14%), river discharge alone significantly explained 12% of the pCO2 variation, cyanobacteria uniquely a further 21%, while 53% of the pCO2 variance was unexplained by either. We show that the urbanization of rivers deltas could result in increased sources of riverine pCO2, water pollution, and harmful cyanobacterial blooms. Such risks could be mitigated through water management to increase water flows in problem areas during the dry season. date: 2022-10-01 date_type: published publisher: IOP Publishing official_url: http://dx.doi.org/10.1088/1748-9326/ac9705 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1989063 doi: 10.1088/1748-9326/ac9705 lyricists_name: Roberts, Lucy lyricists_name: Salgado, Jorge lyricists_id: LRROB14 lyricists_id: JSALG03 actors_name: Salgado, Jorge actors_id: JSALG03 actors_role: owner full_text_status: public publication: Environmental Research Letters volume: 17 number: 10 article_number: 104052 citation: Salgado, J; Duc`, TA; Nga, DT; Panizzo, VN; Bass, AM; Zheng, Y; Taylor, S; ... McGowan, S; + view all <#> Salgado, J; Duc`, TA; Nga, DT; Panizzo, VN; Bass, AM; Zheng, Y; Taylor, S; Roberts, LR; Lacey, JH; Leng, MJ; McGowan, S; - view fewer <#> (2022) Urbanization and seasonality strengthens the CO2 capacity of the Red River Delta, Vietnam. Environmental Research Letters , 17 (10) , Article 104052. 10.1088/1748-9326/ac9705 <https://doi.org/10.1088/1748-9326%2Fac9705>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10166543/1/Salgado_2022_Environ._Res._Lett._17_104052.pdf