Simon Weldon
Forsker
(+47) 407 69 197
simon.weldon@nibio.no
Sted
Ås - Bygg O43
Besøksadresse
Oluf Thesens vei 43, 1433 Ås (Varelevering: Elizabeth Stephansens vei 23)
Forfattere
Simon Weldon Bert van der Veen Eva Farkas Nazli Pelin Kocatürk Schumacher Alba Dieguez-Alonso Alice Budai Daniel RasseSammendrag
Sorption of nutrients such as NH4+ is often quoted as a critical property of biochar, explaining its value as a soil amendment and a filter material. However, published values for NH4+ sorption to biochar vary by more than 3 orders of magnitude, without consensus as to the source of this variability. This lack of understanding greatly limits our ability to use quantitative sorption measurements towards product design. Here, our objective was to conduct a quantitative analysis of the sources of variability, and infer which biochar traits are more favourable to high sorption capacity. To do so, we conducted a standardized remodelling exercise of published batch sorption studies using Langmuir sorption isotherm. We excluded studies presenting datasets that either could not be reconciled with the standard Langmuir sorption isotherm or generated clear outliers. Our analysis indicates that the magnitude of sorption capacity of unmodified biochar for NH4+ is lower than previously reported, with a median of 4.2 mg NH4+ g−1 and a maximum reported sorption capacity of 22.8 mg NH4+ g−1. Activation resulted in a significant relative improvement in sorption capacity, but absolute improvements remain modest, with a maximum reported sorption of 27.56 mg NH4+ g−1 for an activated biochar. Methodology appeared to substantially impact sorption estimates, especially practices such as pH control of batch sorption solution and ash removal. Our results highlight some significant challenges in the quantification of NH4+ sorption by biochar and our curated data set provides a potentially valuable scale against which future estimates can be assessed.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
M. Helbig T. Živković P. Alekseychik M. Aurela T. S. El-Madany E. S. Euskirchen L. B. Flanagan T. J. Griffis P. J. Hanson J. Hattakka C. Helfter T. Hirano E. R. Humphreys G. Kiely R. K. Kolka T. Laurila P. G. Leahy A. Lohila I. Mammarella M. B. Nilsson A. Panov Frans-Jan W. Parmentier M. Peichl J. Rinne D. T. Roman O. Sonnentag E.-S. Tuittila M. Ueyama T. Vesala P. Vestin Simon Weldon P. Weslien S. ZaehleSammendrag
Peatlands have acted as net CO2 sinks over millennia, exerting a global climate cooling effect. Rapid warming at northern latitudes, where peatlands are abundant, can disturb their CO2 sink function. Here we show that sensitivity of peatland net CO2 exchange to warming changes in sign and magnitude across seasons, resulting in complex net CO2 sink responses. We use multiannual net CO2 exchange observations from 20 northern peatlands to show that warmer early summers are linked to increased net CO2 uptake, while warmer late summers lead to decreased net CO2 uptake. Thus, net CO2 sinks of peatlands in regions experiencing early summer warming, such as central Siberia, are more likely to persist under warmer climate conditions than are those in other regions. Our results will be useful to improve the design of future warming experiments and to better interpret large-scale trends in peatland net CO2 uptake over the coming few decades.
Sammendrag
Biochar has been shown to reduce nitrous oxide (N2O) emissions from soils, but the effect is highly variable across studies and the mechanisms are under debate. To improve our mechanistic understanding of biochar effects on N2O emission, we monitored kinetics of NO, N2O and N2 accumulation in anoxic slurries of a peat and a mineral soil, spiked with nitrate and amended with feedstock dried at 105 °C and biochar produced at 372, 416, 562 and 796 °C at five different doses. Both soils accumulated consistently less N2O and NO in the presence of high-temperature chars (BC562 and BC796), which stimulated reduction of denitrification intermediates to N2, particularly in the acid peat. This effect appeared to be strongly linked to the degree of biochar carbonisation as predicted by the H:C ratio of the char. In addition, biochar surface area and pH were identified as important factors, whereas ash content and CEC played a minor role. At low pyrolysis temperature, the biochar effect was soil dependent, suppressing N2O accumulation in the mineral soil, but enhancing it in the peat soil. This contrast was likely due to the labile carbon content of low temperature chars, which contributed to immobilise N in the mineral soil, but stimulated denitrification and N2O emission in the peat soil. We conclude that biochar with a high degree of carbonisation, high pH and high surface area is best suited to supress N2O emission from denitrification, while low temperature chars risk supporting incomplete denitrification.
Sammendrag
I denne rapporten har vi undersøkt i hvilken grad restaurering av myr kan bidra til ny karbonlagring og samtidig reduserte klimagassutslipp. Et litteraturstudium viser at drenert myr er en langt større kilde til CO2-utslipp enn både naturlig og restaurert myr. Årsaken til den høye CO2-emisjonen i drenert myr er lavere grunnvannstand, tilgang på oksygen og økt jordrespirasjon. Høy grunnvannstand i naturlig og restaurert myr motvirker jordrespirasjonen og bidrar til lagring av karbon i jorda. Restaurering av myr vil derfor som regel redusere karbontapet, og kan, avhengig av forholdene på stedet, gjenskape området til et karbonsluk.
Forfattere
Vibeke Lind Özge Sizmaz Ahu Demirtas Mert Sudagidan Simon Weldon Alice Budai Adam O'Toole Dejan Dragan Miladinovic Grete H. M. JørgensenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Rapporten er utarbeidet på oppdrag for Miljødirektoratet. Den gir en oversikt over kunnskapsgrunnlag for mulige tiltak for å redusere utslipp av klimagasser fra drenert organisk jordbruksjord i Norge, både ved restaurering og ved fortsatt jordbruksdrift. Vurdering av egnete arealer for tiltak, muligheter for bokføring i det nasjonale klimagassregnskapet, positive og negative effekter av tiltakene inngår også.
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