Hjalmar Laudon

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[1] The regulation of the spatial and seasonal variation in terrestrial dissolved organic carbon (DOC) exports was studied in a 68 km boreal stream system in northern Sweden. A total of 1213 DOC samples were collected in 15 subcatchments over a 3 year period (2003–2005). The mean annual DOC exports from the 15 subcatchments (0.03–21.72 km) ranged from 14.8(More)
The aim of this investigation was to determine the lateral exportof dissolved inorganic carbon (DIC) from soils of a Swedish boreal forest to a first order stream and to estimate the partitioning of this DIC into CO2 evasion from the stream surface and the DIC pool exported down through the catchment by streamwater. The groundwater entering the stream was(More)
We bring together three decades of research from a boreal catchment to facilitate an improved mechanistic understanding of surface water dissolved organic carbon (DOC) regulation across multiple scales. The Krycklan Catchment Study encompasses 15 monitored nested research catchments, ranging from 3 to 6900 ha in size, as well as a set of monitored transects(More)
[1] Acidity is well known to influence stream biota, but the less well-studied spatial and temporal distributions of acidity are likely to play a larger ecological role than average values. We present data on spatial variability of chemical parameters contributing to acidity during winter baseflow and spring flood periods in Krycklan, a fourth-order boreal(More)
Total organic carbon (TOC) concentrations from seven boreal catchments in northern Sweden were monitored between June 1996 and May 1998 to examine spatial and temporal variations in streamwater TOC export and its relationship with catchment characteristics. The annual average export of TOC ranged between 36 and 76 kg ha–1 yr–1 and correlated positively with(More)
[1] Carbon dioxide (CO2) and dissolved inorganic carbon (DIC) concentrations and export were analyzed throughout a 67 km boreal stream network in northern Sweden. 700 DIC and CO2 samples from 14 subcatchments were collected in 2006 and 2007. All sites were consistently supersaturated in CO2 with respect to the atmosphere. Temporal variability of DIC and CO2(More)
Carboxylic acids (CAs), amino acids (AAs) and carbohydrates (CHs) in dissolved free forms can be readily assimilated by aquatic bacteria and metabolized at high growth efficiencies. Previous studies have shown that these low-molecular-weight (LMW) substrates are released by phytoplankton but also that unidentified LMW compounds of terrestrial origin is a(More)
[1] Large spatial and temporal variations in stream total organic carbon (TOC) concentration and export occurred during an 11-year observation period (1993–2003) in a boreal headwater catchment. TOC flux and concentration patterns from mireand forestdominated subcatchments differed (mean annual flux 8.2 g m 2 a 1 versus 5.8 g m 2 a ). Temporal variations in(More)
Evasion of gaseous carbon (C) from streams is often poorly quantified in landscape C budgets. Even though the potential importance of the capillary network of streams as C conduits across the land-water-atmosphere interfaces is sometimes mentioned, low-order streams are often left out of budget estimates due to being poorly characterized in terms of gas(More)
[1] The character and quantity of dissolved organic carbon (DOC) were studied in nine small boreal streams and adjacent soils during two years, with focus on the spring snowmelt period. The streams cover a forest-wetland gradient, spanning from 0% to 69% wetland coverage. Lower values of the absorbance ratio measured at 254 nm and 365 nm (A254/A365), in(More)