Inter-annual differences of discharge also led to differences in CH4 and N2O that were higher in years with prolonged low water periods. lower gas transfer velocities), both contributing to the accumulation of gases in the water column, combined with higher temperatures favourable to microbial processes. Seasonal variations were related to changes in freshwater discharge following the hydrological cycle, with highest concentrations of CO2, CH4, N2O during low water owing to a longer water residence time and lower currents (i.e. Surface waters of the Meuse river network were over-saturated in CO2, CH4, N2O with respect to atmospheric equilibrium, acting as sources of these greenhouse gases to the atmosphere, although the dissolved gases also showed marked seasonal and spatial variations. We report a data-set of CO2, CH4, and N2O concentrations in the surface waters of the Meuse river network in Belgium, obtained during four surveys covering 50 stations (summer 2013 and late winter 2013, 20), from yearly cycles in four rivers of variable size and catchment land cover, and from 111 groundwater samples. Nitrogen cycling within the catchment, whilst potentially providingįoresight in the impacts of future land management decisions. Δ15NPN of sediments, bivalves and near-shoreĬorals, to reconstruct how historical land-use changes have influenced A strong correlationĪs a proxy of freshwater discharge) presents the possibility ofĮmploying a combination of proxies, such as The intense upper- to mid-catchment N-cycling leads toĪ significantly enriched δ15NPN during theĭry season (mean: +16.5 ± 8.2‰ but reaching as high as Significant role of DIN assimilation by primary producers in theĭrainage network. Over the same reach suggest that benthic denitrification was theĭominant process controlling the removal of NO3-,Īlthough large cyanobacterial blooms further downstream highlight the Nitrous oxide produced was rapidlyĭegassed downstream, while the elevated NO3-Ĭoncentrations steadily decreased to levels observed elsewhere in more (N2O) downstream, pointing towards strong nitrification over Rapid removal of NH4+ in the upper study areaĭuring the dry season was accompanied by a quantitatively similar Of organic matter as the prevailing source of riverine nitrogen. (δ15NPN), strongly reflecting the dominance
Intense DIN cycling, dry season particulate N export is significantly Less DIN export during the dry season, and (2) as a result of the Removal of DIN in the upper- to mid-catchment leads to significantly Increased residence time during the dry season creates two differencesĬomparative to wet season conditions, where (1) intense cycling and Minimal instream N-cycling prior to discharge to the ocean. Long rain seasons (212 and 193 μmol L-1, respectively).ĭuring the rain seasons, low water residence time led to relatively Highest during the dry season (1195 μmol L-1), while totalĭIN concentration was an order of magnitude lower during the short and Inorganic nitrogen (DIN) concentrations entering the study area were
Waste water from the city of Nairobi had a profound impact on theīiogeochemistry of the upper Athi river, leading to low dissolved oxygen Season and long-rain season respectively. November 2011, and April-May 2012, covering the dry season, short-rain The data-set was obtained in August-September 2011, Nitrogen (N) species as they flow through the A-G-S catchment (~47 000 As part of a broader study on the riverine biogeochemistry in theĪthi-Galana-Sabaki (A-G-S) River catchment (Kenya), we present dataĬonstraining the sources, transit and transformation of multiple