ABSTRACT
Long-term fertilization causes the differences in water, heat, nutrients and microbial activities between topsoil and deep soil, with consequences on the decomposition and turnover of straw carbon (C) in soils. At a long-term positioning experimental station in Shenyang Agricultural University, we mixed the topsoil (0-20 cm) and deep soil (40-60 cm) samples from different fertilization treatments with 13C-labeled straw for in-situ incubation. We analyzed the content of organic C and its δ13C value in soil aggregates, compared the difference in the distribution of straw C between topsoil and deep soil aggregates, and explored the effects of fertilization on the sequestration of straw C in soil aggregates. Compared with fertilization treatments (i.e., single chemical nitrogen fertilizer application and combination of organic manure with nitrogen fertilizer application), the treatment without fertilization increased the content of straw C of <0.053 mm aggregate in the topsoil by 106.7% and that of >0.25 mm aggregate in the deep soil by 34.2%. The contribution percentage of straw C to organic C of >0.053 mm aggregate in the deep soil was about two times of that in the topsoil. About 22.6% and 11.4% of straw C was distributed into the >0.25 mm and <0.25 mm aggregates of topsoil, and about 29.4% and 8.8% of straw C was distributed into the >0.25 mm and <0.25 mm aggregates of deep soil, respectively. In conclusion, straw addition promoted the regeneration and sequestration of carbon in deep soil macroaggregates and increased the carbon sequestration potential of deep soil.
Subject(s)
Carbon , Soil , Agriculture , Carbon Sequestration , Fertilization , Fertilizers , Humans , Nitrogen/analysis , Soil/chemistryABSTRACT
The high value-added conversion of biomass lignin has been paramount in the field of lignin utilization, especially for high performance energy conversion and storage devices. A majority of lignin-based supercapacitors generally exhibit inferior electrochemical performance with low capacitance and slow diffusion kinetics due to the poor interfacial compatibility, low conductivity, and uncontrollable morphology. Herein, we designed all-lignin converted graphene quantum dot and graphene sheet (GQD/Gr) hetero-junction for simultaneous fast charging and boosted specific capacitance. The conversion from lignin to GQDs and then refusion into graphene allows the in situ growth of GQDs on graphene, endowing good interfacial compatibility with the GQD/Gr hetero-junction. Furthermore, both GQDs and graphene sheets exhibit highly crystalline structure with obvious graphene lattice, giving GQDs/Gr good conductivity. GQDs play an additive role for avoiding stacks and agglomerates between graphene layers, which endow the assembled GQDs/Gr with massive electron capacitive sites and more hierarchical channels. Therefore, the GQD/Gr hetero-junction gives rise to a high specific capacitance of 404.6 F g-1 and a short charging time constant (τ 0) of 0.3 s, 2.5 times higher and 7.5 times faster than that of the unmodified lignin electrode with 162 F g-1 and 2.3 s, respectively. This proposed strategy could offer the opportunity to unblock the critical roadblocks for a superior electrochemical performance lignin-based supercapacitor by composing a 0D/2D GQD/Gr hetero-junction system and also paves a bright way for the high-value industrial lignin conversion into cheap, scalable, and high-performance electrochemical energy devices.
ABSTRACT
A facile and green route is introduced to fabricate antimicrobial composite films in this article from xylan (XL) and hydroxyethyl cellulose (HEC) with citric acid (CA) and polyethylene glycol 400 (PEG-400) as crosslinker and plasticizer, respectively. XL was obtained by precipitating wood hydrolysate (WH) produced during pulping process with ethanol. Antimicrobial activity was constructed by incorporating ß-cyclodextrin/sodium benzoate (ß-CD/NaBz) complex into the composite matrix. The interactions, including hydrogen bonds and covalent bonds, between the polymers were confirmed by FT-IR spectroscopy. Morphology and crystallinity of composite films at different curing time were investigated by AFM and XRD, respectively. The composite film cured for 40â¯min exhibits tensile strength up to 62.3â¯MPa and oxygen permeability (OP) as low as 1.0â¯cm3·µmâ¯m-2·d-1·kPa-1. Finally, the antimicrobial test against Staphylococcus aureus reveals superior antimicrobial activity of composite films with complex. In conclusion, the XL/HEC antimicrobial film has great potential in the field of sustainable food packing materials.
