Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers

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http://hdl.handle.net/10138/311285

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Asmala , E , Carstensen , J & Räike , A 2019 , ' Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers ' , Environmental Research Letters , vol. 14 , no. 12 , 124018 . https://doi.org/10.1088/1748-9326/ab4fa9

Title: Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers
Author: Asmala, Eero; Carstensen, Jacob; Räike, Antti
Contributor organization: Ecosystems and Environment Research Programme
Biological stations
Marine Ecosystems Research Group
Aquatic Biogeochemistry Research Unit (ABRU)
Tvärminne Zoological Station
Date: 2019-12
Language: eng
Number of pages: 10
Belongs to series: Environmental Research Letters
ISSN: 1748-9326
DOI: https://doi.org/10.1088/1748-9326/ab4fa9
URI: http://hdl.handle.net/10138/311285
Abstract: Increases of riverine organic carbon concentrations have been observed across the northern hemisphere over the past few decades. These increases are the result of multiple environmental drivers, but the relative importance of the drivers is still unclear. We analyzed a dataset of >10 000 observations of riverine total organic carbon (TOC) concentrations and associated water chemistry and hydrological observations from 1993 to 2017. The observations span a ~600 km north–south gradient from 30 individual river systems in Finland. Our data show significantly increasing TOC concentrations in 25 out of 30 systems, with an average increase from 12.0 to 15.1 mg l−1. The observed increase in riverine TOC concentrations led to an increase of 0.28 Mt in annual TOC load to the Baltic Sea from 1993 level to 2017 level. We analyzed the role of three putative environmental drivers of the observed TOC trends. Multiple regression analysis revealed that the most common driver was discharge, which alone explained TOC increases in 13 rivers, whereas pH and temperature were less important drivers (sole predictor in one and zero rivers, respectively). Different permutations of these three drivers were also found to be significant; the combination of discharge and pH being the most common (4 rivers). Land use was not in general linked with trends in TOC, except for the proportion of ditched land in the catchment, which was significantly correlated with increases in TOC concentration. Land use showed significant relationships with trends in discharge and pH. We also found that catchment characteristics are regulating the extent of these regional or global environmental changes causing the upward trends of riverine organic carbon.
Subject: total organic carbon
riverine export
land use
ditching
LAND-USE
CLIMATE-CHANGE
FOREST LAKES
NEW-YORK
WATER
EXPORT
SOILS
ACIDIFICATION
TEMPERATURE
INCREASES
1181 Ecology, evolutionary biology
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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