Premium
Effects of Climate Change on Peatland Reservoirs: A DOC Perspective
Author(s) -
Fenner N.,
Meadham J.,
Jones T.,
Hayes F.,
Freeman C.
Publication year - 2021
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2021gb006992
Subject(s) - dissolved organic carbon , environmental science , macrophyte , phytoplankton , trophic level , benthic zone , environmental chemistry , ecology , nutrient , chemistry , biology
Peatland reservoirs are global hotspots for drinking water provision and are likely to become more important as demand per capita rises and the climate changes. Dissolved organic carbon (DOC) is associated with harmful disinfection byproducts and reduced aesthetic quality, and its removal is the major treatment cost. Littoral zones are known to be disproportionately important for DOC production through macrophyte inputs, and such communities are predicted to expand with warming in northern regions. However, little is known about autochthonous DOC contributions and their response to climatic change. Here we exposed mesocosms to elevated CO 2 (eCO 2 ), warming and a combined treatment across a trophic gradient. Regression analysis indicated that while sediments, macrophytes, and phytoplankton are important DOC sources ( P < 0.05), benthic algal biomass showed the strongest relationship with DOC ( P < 0.05), suggesting it is an underestimated source. DOC removal indicators, namely phenol oxidase (depolymerization) and respiration (mineralization) were inversely related to DOC concentration in oligohumic ( P < 0.05) and oligotrophic ( P < 0.1) systems, suggesting heterotrophic processes are important in DOC removal. DOC concentrations increased across all systems ( P < 0.05), irrespective of trophic status, due to increased photoautotrophic inputs (macrophyte, pelagic, and benthic algae) under eCO 2 , warming, and combined scenarios, with inhibited depolymerization and mineralization under eCO 2 , even when combined with warming ( P < 0.05 and P < 0.05 excepting the oligo‐mesotrophic reservoir P < 0.1 respectively). Increased DOC loads of all fractions, regardless of provenance, are predicted in a future climate and, thus, investment in techniques to remove a greater range of DOC fractions is proposed to help “future proof” drinking water supplies.