15 research outputs found
Priming of Soil Carbon Decomposition in Two Inner Mongolia Grassland Soils following Sheep Dung Addition: A Study Using <sup>13</sup>C Natural Abundance Approach
<div><p>To investigate the effect of sheep dung on soil carbon (C) sequestration, a 152 days incubation experiment was conducted with soils from two different Inner Mongolian grasslands, <i>i.e.</i> a <i>Leymus chinensis</i> dominated grassland representing the climax community (2.1% organic matter content) and a heavily degraded <i>Artemisia frigida</i> dominated community (1.3% organic matter content). Dung was collected from sheep either fed on <i>L. chinensis</i> (C<sub>3</sub> plant with δ<sup>13</sup>C = −26.8‰; dung δ<sup>13</sup>C = −26.2‰) or <i>Cleistogenes squarrosa</i> (C<sub>4</sub> plant with δ<sup>13</sup>C = −14.6‰; dung δ<sup>13</sup>C = −15.7‰). Fresh C<sub>3</sub> and C<sub>4</sub> sheep dung was mixed with the two grassland soils and incubated under controlled conditions for analysis of <sup>13</sup>C-CO<sub>2</sub> emissions. Soil samples were taken at days 17, 43, 86, 127 and 152 after sheep dung addition to detect the δ<sup>13</sup>C signal in soil and dung components. Analysis revealed that 16.9% and 16.6% of the sheep dung C had decomposed, of which 3.5% and 2.8% was sequestrated in the soils of <i>L. chinensis</i> and <i>A. frigida</i> grasslands, respectively, while the remaining decomposed sheep dung was emitted as CO<sub>2</sub>. The cumulative amounts of C respired from dung treated soils during 152 days were 7–8 times higher than in the un-amended controls. In both grassland soils, ca. 60% of the evolved CO<sub>2</sub> originated from the decomposing sheep dung and 40% from the native soil C. Priming effects of soil C decomposition were observed in both soils, <i>i.e.</i> 1.4 g and 1.6 g additional soil C kg<sup>−1</sup> dry soil had been emitted as CO<sub>2</sub> for the <i>L. chinensis</i> and <i>A. frigida</i> soils, respectively. Hence, the net C losses from <i>L. chinensis</i> and <i>A. frigida</i> soils were 0.6 g and 0.9 g C kg<sup>−1</sup> soil, which was 2.6% and 7.0% of the total C in <i>L. chinensis</i> and <i>A. frigida</i> grasslands soils, respectively. Our results suggest that grazing of degraded Inner Mongolian pastures may cause a net soil C loss due to the positive priming effect, thereby accelerating soil deterioration.</p></div
Fates of soil and sheep dung carbon after 152
a<p>Net soil C loss was given by the value of sheep dung C sequestrated in the soil during 152 days subtracted from the primed soil CO<sub>2</sub>.</p>b<p>Soil C loss (%) is the percentage total CO<sub>2</sub>-C loss compared to soil total organic C content.</p
Temporal dynamics of δ<sup>13</sup>C (‰ vs VPDB) signatures in CO<sub>2</sub> emitted during 152 days following sheep dung addition to <i>L. chinensis</i> and <i>A. frigida</i> soil (n = 3).
<p>Temporal dynamics of δ<sup>13</sup>C (‰ vs VPDB) signatures in CO<sub>2</sub> emitted during 152 days following sheep dung addition to <i>L. chinensis</i> and <i>A. frigida</i> soil (n = 3).</p
The relative contribution of dung-derived CO<sub>2</sub>-C and soil-derived CO<sub>2</sub>-C during 152 days incubation calculated from the δ<sup>13</sup> C signature of CO<sub>2</sub> after sheep dung addition (n = 3).
<p>The relative contribution of dung-derived CO<sub>2</sub>-C and soil-derived CO<sub>2</sub>-C during 152 days incubation calculated from the δ<sup>13</sup> C signature of CO<sub>2</sub> after sheep dung addition (n = 3).</p
Two Unprecedented Transition-Metal–Organic Frameworks Showing One Dimensional-Hexagonal Channel Open Network and Two-Dimensional Sheet Structures
Two new metal–organic frameworks, {[Co<sub>3</sub>(μ<sub>3</sub>-DMPhIDC)<sub>2</sub>(H<sub>2</sub>O)<sub>6</sub>]·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>) and {[Mn<sub>5</sub>(μ<sub>3</sub>-DMPhIDC)<sub>2</sub>(μ<sub>2</sub>-HDMPhIDC)<sub>2</sub>(Phen)<sub>5</sub>]·2CH<sub>3</sub>OH·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>) (H<sub>3</sub>DMPhIDC = 2-(3,4-dimethylphenyl)-1<i>H</i>-imidazole-4,5-dicarboxylic acid, Phen = 1,10-phenanthroline), have
been hydrothermally synthesized and structurally characterized by
single-crystal X-ray diffraction, elemental analyses, X-ray powder
diffraction (XRPD), thermal analyses, and IR spectra. Polymer <b>1</b> is an enchanting three-dimensional network containing infinite
one-dimensional-hexagonal channels and [Co<sub>2</sub>(DMPhIDC)]<sub>6</sub> cages, which have two interpenetrating nets topology. Polymer <b>2</b> exhibits a two-dimensional framework, which is composed
of left- and right-handed helices pillared by Mn<sup>2+</sup> linkages.
Antiferromagnetic coupling exists between the CoÂ(II) ions or MnÂ(II)
ions in <b>1</b> or <b>2</b>, respectively
Two Unprecedented Transition-Metal–Organic Frameworks Showing One Dimensional-Hexagonal Channel Open Network and Two-Dimensional Sheet Structures
Two new metal–organic frameworks, {[Co<sub>3</sub>(μ<sub>3</sub>-DMPhIDC)<sub>2</sub>(H<sub>2</sub>O)<sub>6</sub>]·2H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>) and {[Mn<sub>5</sub>(μ<sub>3</sub>-DMPhIDC)<sub>2</sub>(μ<sub>2</sub>-HDMPhIDC)<sub>2</sub>(Phen)<sub>5</sub>]·2CH<sub>3</sub>OH·3H<sub>2</sub>O}<sub><i>n</i></sub> (<b>2</b>) (H<sub>3</sub>DMPhIDC = 2-(3,4-dimethylphenyl)-1<i>H</i>-imidazole-4,5-dicarboxylic acid, Phen = 1,10-phenanthroline), have
been hydrothermally synthesized and structurally characterized by
single-crystal X-ray diffraction, elemental analyses, X-ray powder
diffraction (XRPD), thermal analyses, and IR spectra. Polymer <b>1</b> is an enchanting three-dimensional network containing infinite
one-dimensional-hexagonal channels and [Co<sub>2</sub>(DMPhIDC)]<sub>6</sub> cages, which have two interpenetrating nets topology. Polymer <b>2</b> exhibits a two-dimensional framework, which is composed
of left- and right-handed helices pillared by Mn<sup>2+</sup> linkages.
Antiferromagnetic coupling exists between the CoÂ(II) ions or MnÂ(II)
ions in <b>1</b> or <b>2</b>, respectively
Dissolution-Dictated Recrystallization in Cesium Lead Halide Perovskites and Size Engineering in δ‑CsPbI<sub>3</sub> Nanostructures
Crystal
strain, crystal size, and reactivity with surrounding
species
underlie the thermal stability of the photoactive γ-CsPbI3 in theoretical and practical perspectives. The spontaneous
transformation of optically γ-CsPbI3 nanocrystals
(NCs) to inactive δ-CsPbI3 nanostructures (NSs) hinders
the development of the fabrication of efficient photovoltaic devices.
To understand this process, we conducted a comprehensive investigation
on the phase transformation kinetics and the nucleation and growth
of δ-CsPbI3 NSs from γ-CsPbI3 NCs
(∼8 nm) in a stepwise manner. The reaction scheme involved
independently carrying out reactions where the γ-CsPbI3 NCs reacted with optimized amounts of aprotic polar solvent (acetone),
which leads to dissolution followed by a recrystallization process
at solvent interfaces (acetone/hexane) to observe even the early changes
in this process. Interestingly, the γ-CsPbI3 NCs
during dissolution in acetone enable the release of PbI2 NCs, eventually leading to changes in crystal phase, size, and shape
of the NCs. As a result, we observed unique absorption spectra and
multiple emission features that enable white light emission. In contrast
to the previously explored phase transformation process (γ-CsPbI3 to δ-CsPbI3 NSs) observed in larger-sized
γ-CsPbI3 NCs (∼18 nm), which occurs through
an oriented self-assembly process when the NCs come in contact with
polar solvents, in our two-step solvent introduction procedure, the
γ-CsPbI3 NCs first transform into zero-dimensional
Cs4PbI6 NCs by their dissolution in acetone.
Depending on the rate of dissolution which is proportional to the
amounts of supplied acetone, the reaction solution can result in Cs4PbI6 NCs, γ-CsPbI3 NCs, or δ-CsPbI3 NSs during the recrystallization process. Furthermore, our
investigations provided insights into this phase transition mechanism
governed by the seeded growth phenomenon. This research facilitates
enhanced control over undesired transitions, thereby promoting the
development of refined and uncomplicated methodologies for recycling
stable γ-CsPbI3 NCs
Temporal dynamics of CO<sub>2</sub> fluxes (mg C kg<sup>–1</sup> day<sup>–1</sup>) (A and B), and cumulative CO<sub>2</sub>-C loss (mg C kg<sup>–1</sup> day<sup>–1</sup>) (C and D) during 152 days of incubation of <i>L. chinensis</i> and <i>A. frigida</i> soils amended with C<sub>3</sub> and C<sub>4</sub> dung.
<p>Values are the mean (n = 3) ± SE (bars).</p
Characteristics of sheep dung used in the incubation study. Dung was collected from sheep either fed on L. <i>chinensis</i> (C<sub>3</sub> dung) or C. <i>squarrosa</i> (C<sub>4</sub> dung).
a<p>The content based on 60g fresh dung portions as applied in the experiment.</p>b<p>Numbers are mean ± SE of n = 3 replicates.</p
Primed CO<sub>2</sub> emission (mg C kg<sup>−1</sup> day<sup>−1</sup>) during 152 days of incubation from sheep dung amended <i>L. chinensis</i> and <i>A. frigida</i> soils.
<p>The numbers indicate soil C derived CO<sub>2</sub> emitted in excess to the control soil (n = 3).</p