| 1. |
- Wang, Congying, et al.
(författare)
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Adsorption of deoxyribonucleic acid (DNA) by willow wood biochars produced at different pyrolysis temperatures
- 2014
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Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 50:1, s. 87-94
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of DNA by biochars was investigated in the present study. Biochars were produced from air-dried willow wood chips at 300, 400, 500, and 600 A degrees C under limited oxygen supply. The resulting products, referred to as BC300, BC400, BC500, and BC600, respectively, were characterized for their elemental composition, cation exchange capacity (CEC), specific surface areas (SSA), and microporosity. According to a Langmuir isotherm, maximum DNA adsorption capacity of biochars was ranked as BC500 > BC600 > BC400 > BC300. Increasing solution pH (from 4.0 to 9.0) faintly decreased DNA adsorption onto biochars. The addition of Na+, Mg2+, and Ca2+ slightly increased the adsorption of DNA, and the effect decreased by increasing the pyrolysis temperature of biochars, indicating that electrostatic interaction was not the main driving force for DNA adsorption onto those biochars. Correlation analysis showed that SSA and micropore surface area were the main factors influencing DNA adsorption on biochars.
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| 2. |
- Wang, Congying, et al.
(författare)
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The chemical composition of native organic matter influences the response of bacterial community to input of biochar and fresh plant material
- 2015
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 395:1, s. 87-104
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Tidskriftsartikel (refereegranskat)abstract
- Aim To investigate how the chemical composition of native organic matter of two contrasting soils varies with inputs of biochar and fresh material (including plant roots) and how these underlying changes influence microbial community structure. Methods Corn stover (CS) and CS-derived biochars produced at 350 °C and 550 °C were applied at a dose of 7.2 t C ha−1 to two contrasting soils—an Alfisol and an Andisol. After 295 days of incubation, two undisturbed subsamples from each pot were taken: (i) in one, lucerne (Medicago sativa L.) was seeded (plant study, P) and (ii) in the other, the incubation was continued without the plants (respiration study, R); all subsamples were incubated for an additional 215 days. Soils without amendments were used as controls. At the end of the incubation (510 days), their bacterial community profiles were characterised using ARISA and the molecular composition of soil organic matter (SOM) was investigated by pyrolysis-GC/MS. Results There were significant interactions between soil type, study type (P or R) and organic amendment. Organic amendments influenced overall SOM composition with microbial community response being mainly influenced by soil type but also strongly affected by the presence or absence of plants. For a specific soil type, ≥ 40 % of total variation in bacterial community ordination could be explained by the molecular composition of SOM. Conclusions The molecular composition of SOM is proposed as an important factor influencing the microbial response to organic amendments, including biochar.
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| 3. |
- Wang, Tao, et al.
(författare)
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Determination of carbonate-C in biochars
- 2014
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Ingår i: Soil Research. - 1838-675X. ; 52:5, s. 495-504
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Tidskriftsartikel (refereegranskat)abstract
- Although carbonate-carbon (C), an integral part of biochar-C, contributes to the liming properties of that material, it also interferes with the estimation of the stable organic C fraction in biochars. In this study, four methods were compared in order to quantify the carbonate-C in biochars: two direct (a titrimetric procedure and thermogravimetric analysis, TGA), and two indirect (acid treatment with separation by filtration and acid fumigation). The titrimetric method showed a high recovery of added carbonate-C (average 98.8%, range 1.5-38 mg), and the standard deviations of carbonate-C for all biochars tested were <0.1% when 1 g of sample was used. The acid treatment with a filtration step overestimated the carbonate-C content (on average by a 4-fold increment) due to the loss of dissolved or fine particulate organic C during filtration. The acid fumigation method was suitable for biochars containing high amount of carbonate-C (>0.3% wt) and when the isotopic signature of organic C in biochars is to be determined. The TGA method (either in N-2 or a dry air atmosphere) was reliable when calcite was the main carbonate form in biochars, but was inadequate for samples containing a considerable amount of whewellite and certain carbonate-bearing minerals (e. g. magnesite) that decompose at <600 degrees C. Because more than half of the biochar samples investigated in the literature and in this study (58% of the 117 samples) contained <0.4% carbonate-C (and 38% of these contained no detectable carbonate-C), low-cost screening methods were developed to identify the biochars needed for carbonate-C analysis. For this purpose, two methods were proposed: (i) a manometric test; and (ii) a ratio between predicted fixed C : total C (FC/TC) and measured FC/TC, where predicted FC/TC was estimated using the following relationship: (FC/TC) = -0.1081(H/C)(2) - 0.1794(H/C) + 1.0097, as derived from values obtained in the literature. A decision tree, including two steps (a screening step and a titrimetric procedure) could be used to determine accurately the carbonate-C in biochars.
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| 4. |
- Liu, Jiang, et al.
(författare)
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Rice-paddy field acts as a buffer system to decrease the terrestrial characteristics of dissolved organic matter exported from a typical small agricultural watershed in the Three Gorges Reservoir Area, China
- 2019
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Ingår i: Environmental Science and Pollution Research. - : SPRINGER HEIDELBERG. - 0944-1344 .- 1614-7499. ; 26:23, s. 23873-23885
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural watersheds are a crucial contributor of terrestrial dissolved organic matter (DOM) for the adjacent aquatic environment. Recently, ecological engineering of the buffer zone such as a rice-paddy field was established to reduce the export of nutrients and contaminants from a small agricultural watershed. However, the potential of the rice-paddy field to reduce the terrestrial signature of DOM is unclear. Therefore, two small agricultural sub-catchments (i.e., sub-1 and sub-2) with different land uses and hill slope angles in the Three Gorges Reservoir (TGR) area of China were studied from 2014 to 2015. The results showed that the terrestrial DOM signals are indicated by optical indices (SUVA(254), S-R, fluorescence index) in the steeper and more forest covered, but rice-paddy field buffered sub-catchment (i.e., sub-2) decreased significantly, as compared to the reference sub-catchment (i.e., sub-1). Regardless of seasonal variations, the rice-paddy field retained a buffering role to reduce the terrestrial property of DOM and the highest capacity was observed during the rice-growth period. However, during storm events, the differences of DOM properties for two sub-catchments were not significant, because the buffer system was weakened. Finally, environmental implications of the role of such a buffer zone in the TGR areas are discussed. These results demonstrate that rice-paddy fields are successful in mitigating the terrestrial property of exported DOM, but the weaker performance during storm events still needs to be considered.
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| 5. |
- Miao, Yubo, et al.
(författare)
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Greening of China and possible vegetation effects on soil moisture
- 2024
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Ingår i: Ecological Indicators. - 1470-160X. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- Wetting and drying climate sequences and anthropogenic vegetation changes can have profound effects on the hydrological cycle and sustainability of terrestrial ecosystems. China contains many different climates, from humid to extremely arid and it contributes to the global mitigation strategies of climate change. China is also an important contributor to global greening and carbon sequestration. In view of this, we estimated the spatial and temporal variation of leaf area index (LAI), dryness/wetness index (DWI), and soil moisture (SM) in arid (A), semi-arid (SA), semi-humid (SH), and humid (H) climate zones during 1981–2018 in China and analyzed the patterns of DWI and LAI effects on SM under different vegetation greenness. The results showed a significantly increasing trend of LAI in all climatic zones, and the contribution was from highest to lowest: SH (8.17 × 10-3 m2 m−2 year−1), SA (7 × 10-3 m2 m−2 year−1), H (4.71 × 10-3 m2 m−2 year−1), and A (3.98 × 10-3 m2 m−2 year−1). The SA and A zones are becoming wetter, while the soil of SH and H zones are drying. The dry/wet climate variation plays a decisive role in soil moisture, while the role of vegetation is limited. Additionally, the LAI3 (mean LAI from 2016 to 2018) thresholds were 0.25–0.41 and 0.84–0.86 for A and SA as a whole, respectively, as well as 0.47–0.54 and 0.93–1.18 for grassland, respectively. When vegetation exceeded this threshold, the effect of vegetation on soil moisture showed a shift from increasing to decreasing change. Overall, the results of the study provide improved understanding of the atmosphere-soil-vegetation interactions under climate change, as well as effects of vegetation restoration and water conservation efforts.
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| 6. |
- Li, Yunyun, et al.
(författare)
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Understanding Enhanced Microbial MeHg Production in Mining-Contaminated Paddy Soils under Sulfate Amendment : Changes in Hg Mobility or Microbial Methylators?
- 2019
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:4, s. 1844-1852
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Tidskriftsartikel (refereegranskat)abstract
- Elevated methylmercury (MeHg) production in mining-contaminated paddy soils, despite the high fraction of refractory HgS(s), has been frequently reported, while the underlying mechanisms are not fully understood. Here, we hypothesized that sulfate input, via fertilization, rainfall, and irrigation, is critical in mobilizing refractory HgS(s) and thus enhancing Hg methylation in mining-contaminated paddy soils. To test this hypothesis, the effects of sulfate amendment on Hg methylation and MeHg bioaccumulation in mining-contaminated soil-rice systems were examined. The results indicated 28-61% higher net MeHg production in soils under sulfate amendment (50-1000 mg kg-1), which in turn increased grain MeHg levels by 22-55%. The enhancement of Hg methylation by Hg mobilization in sulfate-amended soils was supported by two observations: (1) the increased Hg(aq) release from HgS(s), the dominant Hg species in the paddy soils, in the presence of sulfide produced following sulfate reduction and (2) the decreases of refractory HgS(s) in soils under sulfate amendment. By contrast, changes in the abundances/activities of potential microbial Hg methylators in different Hg-contaminated soils were not significant following sulfate amendment. Our results highlight the importance to consider enhanced Hg mobility and thus methylation in soils under sulfate amendment.
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| 7. |
- Wang, Di, et al.
(författare)
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Soil water infiltration characteristics of reforested areas in the paleo-periglacial eastern Liaoning mountainous regions, China
- 2024
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Ingår i: Catena. - 0341-8162. ; 234
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Tidskriftsartikel (refereegranskat)abstract
- Plantation forests (PF) and natural secondary forests (NSF) are the primary reforestation approaches. The establishment of PF can affect forest hydrological processes by changing soil structure. To date, few studies have focused on these changes and the effects on hydrological processes for the paleo-periglacial landform. To reveal reforestation approaches effects on water infiltration, including soil water infiltration capacity, retention capacity, and waterflow path pattern, we conducted field dye-tracer investigations with rainfall and laboratory infiltration experiments for the paleo-periglacial landform of eastern Liaoning mountains, China. The results showed that (1) Soil physical properties (including total porosity (TP), capillary porosity (CP), non-capillary porosity (NCP), initial soil water content (IWC), field water capacity (FWC)) and root abundance (RA) decreased with soil depth in both PF and NSF, while the soil bulk density (BD) and distribution of gravel content showed opposite changes. (2) Establishment of PF reduced the infiltration capacity and water retention capacity in the 0–20 cm layer, but enhanced the water retention capacity in 20–30 cm layer. Low IWC was conducive to increase soil water content (SWC) after infiltration. (3) Infiltration capacity parameters (including saturated hydraulic conductivity (Ks), SWC, difference between SWC and IWC (SWC–IWC), dye coverage ratio (DC)) were significantly correlated with BD, TP, CP, NCP, FWC, and fine roots RA (P < 0.05). Better connectivity gravels were more conducive to water infiltration. (4) Preferential flow was the main infiltration type, but with different waterflow paths pattern, with the 'funnel', 'finger' shape for PF, NSF, respectively. Increasing infiltration could increase flow path connectivity. Our findings show that soil physical properties, roots, and gravel occurrence affected soil infiltration, and different reforestation approaches had varying impacts on soil infiltration, water redistribution, transportation, and storage of surface and groundwater, improving the understanding of ecohydrological processes and effects of water resources management in forest ecosystems of paleo-periglacial landform.
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| 8. |
- Wang, Tao, et al.
(författare)
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Predicting phosphorus bioavailability from high-ash biochars
- 2012
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 357:1-2, s. 173-187
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Tidskriftsartikel (refereegranskat)abstract
- Biochars are highly variable in nutrient composition and availability, which are determined by types of feedstock and pyrolysis conditions. The aim of this research was to (a) study the bioavailability of phosphorus (P) in biochars using different feedstocks and pyrolysis conditions; (b) develop a robust chemical method for biochar P availability measurements. In the present study, (a) chemical analysis - including total P and extractable P (2% citric acid, 2% formic acid, and neutral ammonium citrate extraction), and (b) a bioassay test using rye-grass grown in a P deficient sandy soil were used to compare the P bioavailability of different biochars. Biochars were produced from two different feedstocks (dairy manure-wood mixture, MAe; biosolid-wood mixture, BSe) at four different pyrolysis temperatures (250, 350, 450, and 550A degrees C). Results showed that P in feedstock was fully recovered in the biochars. After 6 harvests, the biochars were as effective as the P fertilizers tested [Sechura phosphate rocks (SPR) and calcium dihydrogen phosphate (CaP)] in increasing the shoot yield. However, P uptake followed the order of CaP > MAe biochars > BSe biochars > SPR, on a same TP basis. Based on the Mitscherlich equation, 2% formic acid was the most sensitive indicator of P bioavailability in biochars. The results suggest that high-ash biochars with high P concentrations are potential P sources with high-agronomic efficiency. We propose the use of 2% formic acid extraction to predict the availability of P in ash-rich biochars.
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| 9. |
- Wang, Tao, et al.
(författare)
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The fate of phosphorus of ash-rich biochars in a soil-plant system
- 2014
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 375:1-2, s. 61-74
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Tidskriftsartikel (refereegranskat)abstract
- The objectives were to investigate (i) the forms and release pattern of P from an ash-rich biochar-amended sandy soil; (ii) the transformation of biochar P in a soil-plant system. Several methodologies (a bioassay test, soluble P extractions, a sequential P fractionation and successive P extractions via resin strips) were used to study the bioavailability and transformation of P in a sandy soil fertilised with either conventional P fertilisers [Ca(H2PO4)(2) (CaP) and Sechura phosphate rock (SPR)] or biochars produced from cattle manure (MAe) and alum-treated biosolids (BSe) at four temperatures (250, 350, 450, and 550 A degrees C). Biochar P mainly contributed to increase soil resin-extractable P- and inorganic NaOH-extractable P-fractions, and thus to plant available P. The decrease in P concentrations of those fractions was caused by the uptake of P by plants rather than their transformations into more stable forms. P release rates diminished following the order: CaP > MAe > BSe > SPR, which indicates a decline in P availability from these P sources. Phosphorus-rich biochar can be used as a slow-release fertiliser. It is necessary to determine available P (either soil or fertiliser tests) in biochars prior to its application to soil, so that dose, frequency and timing of application are correctly established.
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| 10. |
- Dong, Lili, et al.
(författare)
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Effects of different forms of N deposition on leaf litter decomposition and extracellular enzyme activities in a temperate grassland
- 2019
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Ingår i: Soil Biology and Biochemistry. - : Elsevier. - 0038-0717 .- 1879-3428. ; 134, s. 78-80
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of decomposition for biogeochemical cycles, it is still not clear how this process is affected by different forms of nitrogen (N). Equal amounts of N with different ratios of inorganic N: organic N (0 : 0, 10 : 0, 7 : 3, 5 : 5, 3 : 7, and 0 : 10) were added to the soil in a steppe. We studied the response of litter decomposition to different forms of N enrichment. The treatment with 30% organic N resulted in the fastest decomposition, which was higher than with inorganic N or organic N addition alone. Our results highlight the need for studies of N deposition on carbon cycles that consider different components in N deposition.
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