Per Persson | Lund University (original) (raw)

Papers by Per Persson

Environmental Science & Technology, 2020

Modern vibrational spectroscopy techniques enable rapid collection of thousands of spectra in a s... more Modern vibrational spectroscopy techniques enable rapid collection of thousands of spectra in a single hyperspectral image, allowing researchers to resolve spatially heterogeneous samples down to a resolution of a few μm. A number of algorithms have been developed to correct for effects such as atmospheric absorption, light scattering by cellular structures and varying baseline levels. Following such preprocessing, spectra are commonly decomposed and clustered to reveal informative patterns and subtle spectral changes. Several of these steps are slow, labor-intensive and require programming skills to make use of published algorithms and code. We here present a free and platform-independent graphical toolbox that allows rapid processing of large sets of spectroscopic images, including atmospheric correction and an algorithm for resonant Mie scattering with improved speed and stability. The software includes modules for decomposition into constituent spectra using the popular MCR-ALS ...

Geosciences, 2018

Through geological time, cyanobacterial picoplankton have impacted the global carbon cycle by seq... more Through geological time, cyanobacterial picoplankton have impacted the global carbon cycle by sequestrating CO2 and forming authigenic carbonate minerals. Various studies have emphasized the cyanobacterial cell envelopes as nucleation sites for calcium carbonate formation. Little is known, however, about how environmental conditions (e.g., nutrient content) trigger a cell surface and its properties and, consequently, influence biomineralization. Our study aims to understand how phosphorus (P) concentration impacts the properties of cell surfaces and cell–mineral interactions. Changes to the surface properties of marine Synechococcus strains grown under various P conditions were characterized by potentiometric titrations, X-ray photoelectron spectroscopy (XPS), and tip-enhanced Raman spectroscopy (TERS). Biomineralization experiments were performed using cyanobacterial cells, which were grown under different P concentrations and exposed to solutions slightly oversaturated with respec...

Environmental microbiology, Jan 10, 2017

Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view... more Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view is that oxidation and depolymerization of SOM by microorganisms promote the formation of SOM-mineral associations that is critical for SOM stabilization. To test this hypothesis we performed laboratory-scale experiments involving one ectomycorrhizal and one saprotrophic fungus that represent the two major functional groups of microbial decomposers in the boreal forest soils. Fungal decomposition enhanced the retention of SOM on goethite, partly because of oxidative modifications of organic matter (OM) by the fungi. Moreover, both fungi secreted substantial amounts (>10% new biomass C) of aromatic metabolites that also contributed to an enhanced mineral retention of OM. Our study demonstrates that soil fungi can form mineral-stabilized SOM not only by oxidative conversion of the SOM but also by synthesizing mineral surface-reactive metabolites. Metabolites produced by fungal decompose...

Environmental science & technology, Jan 26, 2017

Hydroquinones are important mediators of electron transfer reactions in soils with a capability t... more Hydroquinones are important mediators of electron transfer reactions in soils with a capability to reduce Fe(III) minerals and molecular oxygen, and thereby generating Fenton chemistry reagents. This study focused on 2,6-dimethoxy hydroquinone (2,6-DMHQ), an analogue to a common fungal metabolite, and its reaction with ferrihydrite and goethite under variable pH and oxygen concentrations. Combined wet-chemical and spectroscopic analyses showed that both minerals effectively oxidized 2,6-DMHQ in the presence of oxygen. Under anaerobic conditions the first-order oxidation rate constants decreased by one to several orders of magnitude depending on pH and mineral. Comparison between aerobic and anaerobic results showed that ferrihydrite promoted 2,6-DMHQ oxidation both via reductive dissolution and heterogeneous catalysis while goethite mainly caused catalytic oxidation. These results were in agreement with changes in the reduction potential (EH) of the Fe(III) oxide/Fe(II)aq redox coup...

Le Journal de Physique IV, 1997

Frontiers in Earth Science

Recent studies have shown that dissolved organic matter (DOM) decomposed by ectomycorrhizal (ECM)... more Recent studies have shown that dissolved organic matter (DOM) decomposed by ectomycorrhizal (ECM) fungi increases adsorptive properties of organic matter towards soil mineral surfaces. Concomitantly, ECM fungi secrete secondary metabolites with iron reducing capacity that are thought to participate in non-enzymatic Fenton-based decomposition of DOM. The aim of this study was to investigate if the iron reduction induced by the ECM fungus Paxillus involutus during organic matter decomposition was conserved in the decomposed DOM. We explored how the modified DOM reductively dissolved ferrihydrite and goethite nanoparticles and how these processes affected the reactions with H2O2 and the Fenton-based oxidation of mineral-associated organic matter. Culture filtrates were obtained from incubation of the ECM fungus on DOM from forest litter of a spruce forest. This modified DOM was separated by extraction into an ethyl acetate and a water fraction. These fractions were reacted with ferrihy...

Soil Science Society of America Journal, 2005

mulation of Al and Fe in organic soils increases the capac- ity of phosphate sorption (Cuttle, 19... more mulation of Al and Fe in organic soils increases the capac- ity of phosphate sorption (Cuttle, 1983; Richardson, 1985; Groundwater discharge areas in boreal forest ecosystems can po- Nieminen and Jarva, 1996). Furthermore, model experi- tentially be areas where Fe and Al accumulate in the forest floor and affect the solubility of P. This study was conducted to determine ments

Geochimica et Cosmochimica Acta

Geochimica et Cosmochimica Acta, 2014

Langmuir, 2004

The nature of the interaction between mellitic acid (benzene hexacarboxylic acid) and the common ... more The nature of the interaction between mellitic acid (benzene hexacarboxylic acid) and the common soil mineral goethite (alpha-FeOOH) has been investigated as a function of pH and ionic strength by use of attenuated total reflection Fourier transform infrared spectroscopy. Molecular orbital calculations of the theoretical vibrational frequencies of the mellitate ion (L6-) and dihydrogen mellitate (H2L4-) have allowed the measured absorption frequencies to be accurately assigned. At pH values above 6, adsorption involves outer-sphere complexation of the deprotonated L6- ion. At lower pH values, there is evidence of a second outer-sphere surface complex involving a partially protonated species, although the extent of protonation of the surface species is significantly less than that found for the solution species at the same pH. While there is no evidence of inner-sphere complexation, increasing the ionic strength to 2.0 M does not displace the adsorbed species but does increase the fraction present on the surface as the fully deprotonated L6-. The small effect of ionic strength suggests that the adsorptive interaction, although outer-sphere in character, is still relatively strong, which indicates that hydrogen bonds may play a significant role. Hydrogen bonding may also help to account for the observed outer-sphere complexation at pH values above the pHiep of goethite.

Geochimica et Cosmochimica Acta, 1996

Complexation of o-phthalate (1,2-benzenedicarboxylate) and competitive complexation of phosphate ... more Complexation of o-phthalate (1,2-benzenedicarboxylate) and competitive complexation of phosphate and phthalate at the goethite-water interface have been studied in 0.1 M Na (NO3) media at 298.2 K within the range 3.0 < -log [H+] < 8.5. Equilibrium measurements were performed as potentiometric titrations supplemented with spectrophotometric phosphate and phthalate analyses.The binary and ternary chemical subsystems H+-goethite and H+-goethite-H2PO4− have been

Geochimica et Cosmochimica Acta, 2000

Geochimica et Cosmochimica Acta, 1996

The complexation of sulfate ions at the goethite-water interface has been studied by equilibrium ... more The complexation of sulfate ions at the goethite-water interface has been studied by equilibrium measurements at 298.2 ± 0.5 K and by infrared spectroscopy. A unified set of data from potentiometric titrations and batch adsorption experiments were evaluated according to an extended Constant Capacitance Model. The obtained equilibrium model consists of two outer-sphere complexes: ≡FeOH2+, SO42− (log β1,1,1(intr)out = 8.3 ± 0.03) and ≡FeOH2+, HSO4− (log β2,1,1(intr)out = 13.5 ± 0.07) and an inner capacitance, C1, of 4.5 and an outer capacitance, C2, of 1.8. The outer-sphere model was confirmed by the infrared data and adsorption experiments at different ionic strengths. Furthermore, the infrared measurements provided direct evidence for protonation of the sulfate ions at the interface.

Geochimica et Cosmochimica Acta, 2005

Environmental Science & Technology, 2002

Environmental Science & Technology, 2020

Modern vibrational spectroscopy techniques enable rapid collection of thousands of spectra in a s... more Modern vibrational spectroscopy techniques enable rapid collection of thousands of spectra in a single hyperspectral image, allowing researchers to resolve spatially heterogeneous samples down to a resolution of a few μm. A number of algorithms have been developed to correct for effects such as atmospheric absorption, light scattering by cellular structures and varying baseline levels. Following such preprocessing, spectra are commonly decomposed and clustered to reveal informative patterns and subtle spectral changes. Several of these steps are slow, labor-intensive and require programming skills to make use of published algorithms and code. We here present a free and platform-independent graphical toolbox that allows rapid processing of large sets of spectroscopic images, including atmospheric correction and an algorithm for resonant Mie scattering with improved speed and stability. The software includes modules for decomposition into constituent spectra using the popular MCR-ALS ...

Geosciences, 2018

Through geological time, cyanobacterial picoplankton have impacted the global carbon cycle by seq... more Through geological time, cyanobacterial picoplankton have impacted the global carbon cycle by sequestrating CO2 and forming authigenic carbonate minerals. Various studies have emphasized the cyanobacterial cell envelopes as nucleation sites for calcium carbonate formation. Little is known, however, about how environmental conditions (e.g., nutrient content) trigger a cell surface and its properties and, consequently, influence biomineralization. Our study aims to understand how phosphorus (P) concentration impacts the properties of cell surfaces and cell–mineral interactions. Changes to the surface properties of marine Synechococcus strains grown under various P conditions were characterized by potentiometric titrations, X-ray photoelectron spectroscopy (XPS), and tip-enhanced Raman spectroscopy (TERS). Biomineralization experiments were performed using cyanobacterial cells, which were grown under different P concentrations and exposed to solutions slightly oversaturated with respec...

Environmental microbiology, Jan 10, 2017

Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view... more Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view is that oxidation and depolymerization of SOM by microorganisms promote the formation of SOM-mineral associations that is critical for SOM stabilization. To test this hypothesis we performed laboratory-scale experiments involving one ectomycorrhizal and one saprotrophic fungus that represent the two major functional groups of microbial decomposers in the boreal forest soils. Fungal decomposition enhanced the retention of SOM on goethite, partly because of oxidative modifications of organic matter (OM) by the fungi. Moreover, both fungi secreted substantial amounts (>10% new biomass C) of aromatic metabolites that also contributed to an enhanced mineral retention of OM. Our study demonstrates that soil fungi can form mineral-stabilized SOM not only by oxidative conversion of the SOM but also by synthesizing mineral surface-reactive metabolites. Metabolites produced by fungal decompose...

Environmental science & technology, Jan 26, 2017

Hydroquinones are important mediators of electron transfer reactions in soils with a capability t... more Hydroquinones are important mediators of electron transfer reactions in soils with a capability to reduce Fe(III) minerals and molecular oxygen, and thereby generating Fenton chemistry reagents. This study focused on 2,6-dimethoxy hydroquinone (2,6-DMHQ), an analogue to a common fungal metabolite, and its reaction with ferrihydrite and goethite under variable pH and oxygen concentrations. Combined wet-chemical and spectroscopic analyses showed that both minerals effectively oxidized 2,6-DMHQ in the presence of oxygen. Under anaerobic conditions the first-order oxidation rate constants decreased by one to several orders of magnitude depending on pH and mineral. Comparison between aerobic and anaerobic results showed that ferrihydrite promoted 2,6-DMHQ oxidation both via reductive dissolution and heterogeneous catalysis while goethite mainly caused catalytic oxidation. These results were in agreement with changes in the reduction potential (EH) of the Fe(III) oxide/Fe(II)aq redox coup...

Le Journal de Physique IV, 1997

Frontiers in Earth Science

Recent studies have shown that dissolved organic matter (DOM) decomposed by ectomycorrhizal (ECM)... more Recent studies have shown that dissolved organic matter (DOM) decomposed by ectomycorrhizal (ECM) fungi increases adsorptive properties of organic matter towards soil mineral surfaces. Concomitantly, ECM fungi secrete secondary metabolites with iron reducing capacity that are thought to participate in non-enzymatic Fenton-based decomposition of DOM. The aim of this study was to investigate if the iron reduction induced by the ECM fungus Paxillus involutus during organic matter decomposition was conserved in the decomposed DOM. We explored how the modified DOM reductively dissolved ferrihydrite and goethite nanoparticles and how these processes affected the reactions with H2O2 and the Fenton-based oxidation of mineral-associated organic matter. Culture filtrates were obtained from incubation of the ECM fungus on DOM from forest litter of a spruce forest. This modified DOM was separated by extraction into an ethyl acetate and a water fraction. These fractions were reacted with ferrihy...

Soil Science Society of America Journal, 2005

mulation of Al and Fe in organic soils increases the capac- ity of phosphate sorption (Cuttle, 19... more mulation of Al and Fe in organic soils increases the capac- ity of phosphate sorption (Cuttle, 1983; Richardson, 1985; Groundwater discharge areas in boreal forest ecosystems can po- Nieminen and Jarva, 1996). Furthermore, model experi- tentially be areas where Fe and Al accumulate in the forest floor and affect the solubility of P. This study was conducted to determine ments

Geochimica et Cosmochimica Acta

Geochimica et Cosmochimica Acta, 2014

Langmuir, 2004

The nature of the interaction between mellitic acid (benzene hexacarboxylic acid) and the common ... more The nature of the interaction between mellitic acid (benzene hexacarboxylic acid) and the common soil mineral goethite (alpha-FeOOH) has been investigated as a function of pH and ionic strength by use of attenuated total reflection Fourier transform infrared spectroscopy. Molecular orbital calculations of the theoretical vibrational frequencies of the mellitate ion (L6-) and dihydrogen mellitate (H2L4-) have allowed the measured absorption frequencies to be accurately assigned. At pH values above 6, adsorption involves outer-sphere complexation of the deprotonated L6- ion. At lower pH values, there is evidence of a second outer-sphere surface complex involving a partially protonated species, although the extent of protonation of the surface species is significantly less than that found for the solution species at the same pH. While there is no evidence of inner-sphere complexation, increasing the ionic strength to 2.0 M does not displace the adsorbed species but does increase the fraction present on the surface as the fully deprotonated L6-. The small effect of ionic strength suggests that the adsorptive interaction, although outer-sphere in character, is still relatively strong, which indicates that hydrogen bonds may play a significant role. Hydrogen bonding may also help to account for the observed outer-sphere complexation at pH values above the pHiep of goethite.

Geochimica et Cosmochimica Acta, 1996

Complexation of o-phthalate (1,2-benzenedicarboxylate) and competitive complexation of phosphate ... more Complexation of o-phthalate (1,2-benzenedicarboxylate) and competitive complexation of phosphate and phthalate at the goethite-water interface have been studied in 0.1 M Na (NO3) media at 298.2 K within the range 3.0 < -log [H+] < 8.5. Equilibrium measurements were performed as potentiometric titrations supplemented with spectrophotometric phosphate and phthalate analyses.The binary and ternary chemical subsystems H+-goethite and H+-goethite-H2PO4− have been

Geochimica et Cosmochimica Acta, 2000

Geochimica et Cosmochimica Acta, 1996

The complexation of sulfate ions at the goethite-water interface has been studied by equilibrium ... more The complexation of sulfate ions at the goethite-water interface has been studied by equilibrium measurements at 298.2 ± 0.5 K and by infrared spectroscopy. A unified set of data from potentiometric titrations and batch adsorption experiments were evaluated according to an extended Constant Capacitance Model. The obtained equilibrium model consists of two outer-sphere complexes: ≡FeOH2+, SO42− (log β1,1,1(intr)out = 8.3 ± 0.03) and ≡FeOH2+, HSO4− (log β2,1,1(intr)out = 13.5 ± 0.07) and an inner capacitance, C1, of 4.5 and an outer capacitance, C2, of 1.8. The outer-sphere model was confirmed by the infrared data and adsorption experiments at different ionic strengths. Furthermore, the infrared measurements provided direct evidence for protonation of the sulfate ions at the interface.

Geochimica et Cosmochimica Acta, 2005

Environmental Science & Technology, 2002