scholarly journals Isotopic Evidence for Sources of Dissolved Carbon and the Role of Organic Matter Respiration in the Fraser River Basin, Canada

2022 ◽  
Author(s):  
Britta M. Voss ◽  
Timothy I. Eglinton ◽  
Bernhard Peucker-Ehrenbrink ◽  
Valier Galy ◽  
Susan Q. Lang ◽  
...  
Keyword(s):  
River Basin ◽  
Dissolved Inorganic Carbon ◽  
River Mouth ◽  
Rocky Mountain ◽  
River System ◽  
Fraser River ◽  
Particulate Carbon ◽  
Close Coupling ◽  
Radiocarbon Age ◽  
Dissolved Carbon

Abstract Sources of dissolved and particulate carbon to the Fraser River system vary significantly in space and time. Tributaries in the northern interior of the basin consistently deliver higher concentrations of dissolved organic carbon (DOC) to the main stem than other tributaries. Based on samples collected near the Fraser River mouth throughout 2013, the radiocarbon age of DOC exported from the Fraser River does not change significantly across seasons despite a spike in DOC concentration during the freshet, suggesting modulation of heterogeneous upstream signals during transit through the river basin. Dissolved inorganic carbon (DIC) concentrations are highest in the Rocky Mountain headwater region where carbonate weathering is evident, but also in tributaries with high DOC concentrations, suggesting that DOC respiration may be responsible for a significant portion of DIC in this basin. Using an isotope and major ion mass balance approach to constrain the contributions of carbonate and silicate weathering and DOC respiration, we estimate that up to 29% of DIC is derived from DOC respiration in some parts of the Fraser River basin. Overall, these results indicate close coupling between the cycling of DOC and DIC, and that carbon is actively processed and transformed during transport through the river network.

scholarly journals Dissolved Carbon Transport and Processing in North America’s Largest Swamp River Entering the Northern Gulf of Mexico

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1395
Author(s):  
Emily M. DelDuco ◽  
Y. Jun Xu
Keyword(s):  
Gulf Of Mexico ◽  
Carbon Cycling ◽  
Mississippi River ◽  
Dissolved Inorganic Carbon ◽  
Isotope Composition ◽  
River System ◽  
Floodplain Wetland ◽  
Co2 Partial Pressure ◽  
River Waters ◽  
Dissolved Carbon

Transport and transformation of riverine dissolved carbon is an important component of global carbon cycling. The Atchafalaya River (AR) flows 189 kilometers through the largest bottomland swamp in North America and discharges ~25% of the flow of the Mississippi River into the Gulf of Mexico annually, providing a unique opportunity to study the floodplain/wetland impacts on dissolved carbon. The aim of this study is to determine how dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in the AR change spatially and seasonally, and to elucidate which processes control the carbon cycling in this intricate swamp-river system. From May 2015 to May 2016, we conducted monthly river sampling from the river’s inflow to its outflow, analyzing samples for concentrations and δ13C stable isotope composition of DOC and DIC. We found that DIC concentrations in the AR were three times higher than the DOC concentrations on average, and showed more pronounced downstream changes than the DOC. During the study period, the river discharged a total of 5.35 Tg DIC and a total of 2.34 Tg DOC into the Gulf of Mexico. Based on the mass inflow–outflow balance, approximately 0.53 Tg (~10%) of the total DIC exported was produced within the floodplain/wetland system, while 0.24 Tg (~10%) of the DOC entering the basin was removed. The AR’s water was consistently oversaturated with CO2 partial pressure (pCO2) above the atmospheric pCO2 (with pCO2 varying from 551 µatm to 6922 µatm), indicating a large source of DIC from river waters to the atmosphere as well as to the coastal margins. Largest changes in carbon constituents occurred during periods of greatest inundation of the swamp-river basin and corresponded with shifts in isotopic composition. This effect was particularly pronounced during the initial flood stages, supporting the hypothesis that subtropical floodplains can act as effective enhancers of the biogeochemical cycling of dissolved carbon.

scholarly journals The Impacts of Hydropower Dams in the Mekong River Basin: A Review

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 265
Author(s):  
Akarath Soukhaphon ◽  
Ian G. Baird ◽  
Zeb S. Hogan
Keyword(s):  
River Basin ◽  
River System ◽  
Economic Security ◽  
Mekong River ◽  
Aquatic Biodiversity ◽  
Environmental Impact Assessments ◽  
The Social ◽  
Hydropower Dams ◽  
River Hydrology ◽  
Riparian Communities

The Mekong River, well known for its aquatic biodiversity, is important to the social, physical, and economic health of millions living in China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. This paper explores the social and environmental impacts of several Mekong basin hydropower dams and groupings of dams and the geographies of their impacts. Specifically, we examined the 3S (Sesan, Sekong Srepok) river system in northeastern Cambodia, the Central Highlands of Vietnam, and southern Laos; the Khone Falls area in southern Laos; the lower Mun River Basin in northeastern Thailand; and the upper Mekong River in Yunnan Province, China, northeastern Myanmar, northern Laos, and northern Thailand. Evidence shows that these dams and groupings of dams are affecting fish migrations, river hydrology, and sediment transfers. Such changes are negatively impacting riparian communities up to 1000 km away. Because many communities depend on the river and its resources for their food and livelihood, changes to the river have impacted, and will continue to negatively impact, food and economic security. While social and environmental impact assessments have been carried out for these projects, greater consideration of the scale and cumulative impacts of dams is necessary.

Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta

2014 ◽  
Vol 70 (4) ◽  
pp. 671-677 ◽  
Author(s):  
Xiaomin Ji ◽  
Youpeng Xu ◽  
Longfei Han ◽  
Liu Yang
Keyword(s):  
River Basin ◽  
River System ◽  
Yangtze River Delta ◽  
System Structure ◽  
River Channels ◽  
Stream Structure ◽  
Impervious Area ◽  
The Status ◽  
Urbanized Areas ◽  
Qinhuai River

Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers.

Variations in the dissolved carbon concentrations of the shallow groundwater in a desert inland river basin

2021 ◽  
pp. 126774
Author(s):  
Jia Xu ◽  
Hongbo Ling ◽  
Guangpeng Zhang ◽  
Junjie Yan ◽  
Mingjiang Deng ◽  
...  
Keyword(s):  
River Basin ◽  
Shallow Groundwater ◽  
Dissolved Carbon ◽  
Inland River ◽  
Inland River Basin ◽  
Carbon Concentrations

Source apportionment of riverine nitrogen transport based on catchment modelling

1996 ◽  
Vol 33 (4-5) ◽  
pp. 109-115 ◽  
Author(s):  
Hans B. Wittgren ◽  
Berit Arheimer
Keyword(s):  
Source Apportionment ◽  
River Basin ◽  
Management Practices ◽  
Arable Land ◽  
Treatment Plant ◽  
River Mouth ◽  
Point Sources ◽  
Nitrogen Transport ◽  
Total N ◽  
Management Measures

Source apportionment of river substance transport, i.e. estimation of how much each source in each subbasin contributes to the river-mouth transport, is a vital step in achieving the most efficient management practices to reduce pollutant loads to the sea. In this study, the spatially lumped (at sub-catchment level), semi-empirical PULSE hydrological model, with a nitrogen routine coupled to it, was used to perform source apportionment of nitrogen transport in the Söderköpingsån river basin (882 km2) in south-eastern Sweden, for the period 1991–93. The river basin was divided into 28 subbasins and the following sources were considered: land leakage from the categories forest, arable and ley/pasture; point sources, and; atmospheric deposition on lake surfaces. The calibrated model yielded an explained variance of 60%, based on comparison of measured and modelled river nitrogen (Total N) concentrations. Eight subbasins, with net contributions to the river-mouth transport exceeding 3 kg ha−1 yr−1, were identified as the most promising candidates for cost efficient nitrogen management. The other 20 subbasins all had net contributions below 3 kg ha−1 yr−1. Arable land contributed 63% of the nitrogen transport at the river mouth and would thus be in focus for management measures. However, point sources (18% contribution to net transport) should also be considered due to their relatively high accessibility for removal measures (high concentrations). E.g., the most downstream subbasin, with the largest wastewater treatment plant in the whole river basin, had a net contribution of 16 kg ha−1 yr−1. This method for source apportionment may provide authorities with quantitative information about where in a river basin, and at which sources, they should focus their attention. However, once this is done, an analysis with higher resolution has to be performed in each of the interesting subbasins, before decisions on actual management measures can be taken.

scholarly journals Hydro-ecological controls on dissolved carbon dynamics in groundwater and export to streams in a temperate pine forest

2018 ◽  
Vol 15 (2) ◽  
pp. 669-691 ◽  
Author(s):  
Loris Deirmendjian ◽  
Denis Loustau ◽  
Laurent Augusto ◽  
Sébastien Lafont ◽  
Christophe Chipeaux ◽  
...  
Keyword(s):  
Water Table ◽  
Hydrological Cycle ◽  
Dissolved Inorganic Carbon ◽  
Shallow Groundwater ◽  
Pine Forest ◽  
Heat Fluxes ◽  
Similar Proportion ◽  
Forest Plot ◽  
Dissolved Carbon ◽  
First Order

Abstract. We studied the export of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from forested shallow groundwater to first-order streams, based on groundwater and surface water sampling and hydrological data. The selected watershed was particularly convenient for such study, with a very low slope, with pine forest growing on sandy permeable podzol and with hydrology occurring exclusively through drainage of shallow groundwater (no surface runoff). A forest plot was instrumented for continuous eddy covariance measurements of precipitation, evapotranspiration, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2 fluxes. Shallow groundwater was sampled with three piezometers located in different plots, and surface waters were sampled in six first-order streams; river discharge and drainage were modeled based on four gauging stations. On a monthly basis and on the plot scale, we found a good consistency between precipitation on the one hand and the sum of evapotranspiration, shallow groundwater storage and drainage on the other hand. DOC and DIC stocks in groundwater and exports to first-order streams varied drastically during the hydrological cycle, in relation with water table depth and amplitude. In the groundwater, DOC concentrations were maximal in winter when the water table reached the superficial organic-rich layer of the soil. In contrast, DIC (in majority excess CO2) in groundwater showed maximum concentrations at low water table during late summer, concomitant with heterotrophic conditions of the forest plot. Our data also suggest that a large part of the DOC mobilized at high water table was mineralized to DIC during the following months within the groundwater itself. In first-order streams, DOC and DIC followed an opposed seasonal trend similar to groundwater but with lower concentrations. On an annual basis, leaching of carbon to streams occurred as DIC and DOC in similar proportion, but DOC export occurred in majority during short periods of the highest water table, whereas DIC export was more constant throughout the year. Leaching of forest carbon to first-order streams represented a small portion (approximately 2 %) of the net land CO2 sink at the plot. In addition, approximately 75 % of the DIC exported from groundwater was not found in streams, as it returned very fast to the atmosphere through CO2 degassing.

The Chao Phraya River Basin: water quality and anthropogenic influences

2018 ◽  
Vol 19 (5) ◽  
pp. 1287-1294 ◽  
Author(s):  
Nuanchan Singkran ◽  
Pitchaya Anantawong ◽  
Naree Intharawichian ◽  
Karika Kunta
Keyword(s):  
Water Quality ◽  
Land Use ◽  
River Basin ◽  
River Mouth ◽  
Oxygen Demand ◽  
Quality Parameters ◽  
Paddy Fields ◽  
Coliform Bacteria ◽  
Wet Season ◽  
Chao Phraya River

Abstract Land use influences and trends in water quality parameters were determined for the Chao Phraya River, Thailand. Dissolved oxygen (DO), biochemical oxygen demand (BOD), and nitrate-nitrogen (NO3-N) showed significant trends (R2 ≥ 0.5) across the year, while total phosphorus (TP) and faecal coliform bacteria (FCB) showed significant trends only in the wet season. DO increased, but BOD, NO3-N, and TP decreased, from the lower section (river kilometres (rkm) 7–58 from the river mouth) through the middle section (rkm 58–143) to the upper section (rkm 143–379) of the river. Lead and mercury showed weak/no trends (R2 < 0.5). Based on the river section, major land use groups were a combination of urban and built-up areas (43%) and aquaculture (21%) in the lower river basin, paddy fields (56%) and urban and built-up areas (21%) in the middle river basin, and paddy fields (44%) and other agricultural areas (34%) in the upper river basin. Most water quality and land use attributes had significantly positive or negative correlations (at P ≤ 0.05) among each other. The river was in crisis because of high FCB concentrations. Serious measures are suggested to manage FCB and relevant human activities in the river basin.

scholarly journals A dynamic water accounting framework based on marginal resource opportunity cost

2015 ◽  
Vol 19 (3) ◽  
pp. 1457-1467 ◽  
Author(s):  
A. Tilmant ◽  
G. Marques ◽  
Y. Mohamed
Keyword(s):  
River Basin ◽  
Value Chain ◽  
Economic Value ◽  
River System ◽  
River Basins ◽  
Management Decision ◽  
Water Fluxes ◽  
Management Actions ◽  
Water Users ◽  
Water Accounting

Abstract. Many river basins throughout the world are increasingly under pressure as water demands keep rising due to population growth, industrialization, urbanization and rising living standards. In the past, the typical answer to meet those demands focused on the supply side and involved the construction of hydraulic infrastructures to capture more water from surface water bodies and from aquifers. As river basins have become more and more developed, downstream water users and ecosystems have become increasingly dependent on the management actions taken by upstream users. The increased interconnectedness between water users, aquatic ecosystems and the built environment is further compounded by climate change and its impact on the water cycle. Those pressures mean that it has become increasingly important to measure and account for changes in water fluxes and their corresponding economic value as they progress throughout the river system. Such basin water accounting should provide policy makers with important information regarding the relative contribution of each water user, infrastructure and management decision to the overall economic value of the river basin. This paper presents a dynamic water accounting approach whereby the entire river basin is considered as a value chain with multiple services including production and storage. Water users and reservoir operators are considered as economic agents who can exchange water with their hydraulic neighbors at a price corresponding to the marginal value of water. Effective water accounting is made possible by keeping track of all water fluxes and their corresponding hypothetical transactions using the results of a hydro-economic model. The proposed approach is illustrated with the Eastern Nile River basin in Africa.

scholarly journals Microglanis cottoides (Boulenger, 1891) (Siluriformes: Pseudopimelodidae): distribution extension to Salí-Dulce River basin, northwestern Argentina

Check List ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 443
Author(s):  
Luis Fernández ◽  
Gladys Gonzo
Keyword(s):  
River Basin ◽  
Geographic Distribution ◽  
Drainage System ◽  
River System ◽  
Northwestern Argentina

Microglanis cottoides (Boulenger 1891) is a known Paraná-Plata River basin catfish. Its geographic distribution is herein extended to a new drainage system, the Salí-Dulce River system, northwestern Argentina, which is a separate drainage from the Paraná-Plata basin.

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